JP4533692B2 - Development device and image forming apparatus having conductive member - Google Patents

Description

The present invention relates to a developing device of an image forming apparatus, particularly, a developing device having a toner regulating conductive member used in the developing apparatus, an image forming apparatus.

  In the electrophotographic process, since the toner, which is a resin powder having a low melting temperature, is present, it is desirable to prevent the toner from adhering to or adhering to parts around the electrostatic latent image carrier. It is rare.

  The charging member, toner carrier, toner regulating member, transfer member, etc. are accompanied by toner adhesion on the surface of the member, and each member rotates in contact with the other member. The toner may melt and adhere to the surface of the member. For this reason, it is often used to coat a material that prevents toner from adhering to the surface of the member.

  As a material having good releasability for preventing toner adhesion, a fluorine-based material is well known and is actually used. However, such a fluorine-based material has a small fluorine content and is difficult to selectively orient fluorine on the part surface in order to make it a paint and improve the workability.

  Therefore, for example, in the case of a toner carrier and a toner regulating member, the toner is directly carried on the surface of the carrier, or the developer mixed with the toner and the carrier is pressed or pressed. Alternatively, the toner tends to adhere to the regulating member, and the toner is subjected to strong stress at the contact portion between the carrier and the regulating member, so that the toner may be fused over time.

  In particular, in the case of the one-component development method using only toner, the toner supply member and the toner regulating member are brought into strong contact with the toner carrier in order to charge the toner on the toner carrier, so that the toner fixation is further improved. It becomes easy to generate. In order to prevent this toner sticking, a fluorine-based material is used on the surface of the toner carrier or on the toner regulating member.

  However, as described above, since the orientation of fluorine on the surface of the member is not sufficient, the effect of preventing toner fusion over time has not been sufficient. Further, in the case of a negatively chargeable toner that is generally used, the fluorine-based material has a problem that the toner charge amount is low because the toner chargeability tends to be reversely charged.

  Further, when the surface friction coefficient is high, frictional heat with the toner is generated, so that the toner is easily fused. Further, since the fluorine-based material is inferior in wear resistance, it has been difficult to extend the life of parts.

  Conventionally, it is a low-hardness conductive roll in which at least one layer is formed on the outer peripheral surface of a shaft body, and the outermost layer is a silicone-grafted acrylic polymer, which is an acrylic polymer portion excluding a structural portion derived from siloxane. A low-hardness conductive roll having a glass transition temperature set in the range of −35 to 30 ° C. has been proposed (see, for example, Patent Document 1).

The difference between this proposal and the conductive member of the present invention is that the acrylic silicone resin used in the present invention has a glass transition temperature exceeding 30 ° C. in the acrylic polymer portion. Moreover, hardness is JIS-A 60-80 degree | times and is different in the part called the low hardness of 35 degree | times described in the said Example.

  Further, (a) a fluorinated (meth) acrylate, (b) a polysiloxane group-containing (meth) acrylate (c), a copolymer (A) other than (a) and (b) (meth) acrylate (A) ), (B) fluorinated olefin resin, (C) (meth) acrylic resin, (D) amino resin, (E) conductive agent, and (E) conductive composition containing (A) to (E) as essential components And the electroconductive roll using the same is proposed (for example, refer patent document 2).

A difference of this Patent Document 2 and the electrically conductive composition of the present invention, the conductive composition of the present invention, the fluorinated (meth) acrylate, fluorinated olefin resins, amino resins do not contain the material The configuration requirements are different.

(A) fluorinated (meth) acrylate, (b) polysiloxane group-containing (meth) acrylate, (c) (meth) acrylate (A) other than (a) and (b), (B) fluorinated olefin (C) (meth) acrylic resin, (D) a curing agent comprising at least one of an isocyanate curing agent and an amino resin, and (E) a carbon black obtained by grafting or coating a polymer on the surface. A conductive composition having A), (B), (C), (D), and (E) as essential components and a conductive roll using the same have been proposed (for example, see Patent Document 3). Differs from the electrically conductive composition of the electrically conductive composition and the present invention, the conductive composition of the present invention, the fluorinated (meth) acrylate, a fluorinated olefin resin does not include the material constituent of the Is different.

  The outermost resin layer of the conductive member is a roll containing a resin containing a polysiloxane-containing acrylic monomer as a base resin. The base resin is a urethane-modified acrylic resin conductive composition and a conductive material using the same. A roll has also been proposed (see, for example, Patent Document 4).

The difference between the electrically conductive composition of the roll and the conductive composition of the present invention, in the conductive composition of the present invention, and using an acrylic resin obtained by polymerizing acrylic acid monomer (polymer), the acrylic monomer is not.

  Regarding a developing device, a toner regulating roller used therein, a method for incorporating the toner regulating roller into the developing device, and an image forming apparatus using the developing device, the surface layer of the toner regulating roller is applied to the developing device similar to the present embodiment. An apparatus composed of a fluororesin has been proposed (see, for example, Patent Document 5).

The difference between this disclosure and the present invention is that the conductive composition of the present invention is composed of an acrylic silicon resin having a hydroxyl group in the surface layer and a crosslinked product formed from an isocyanate group. Other toner carriers, toner supply members, operations, etc. are the same.

  In addition, a ceramic in which a resistance adjusting layer made of a thermoplastic resin composition in which a polymer ion conductive material is dispersed is formed on a conductive support, and the surface of the resistance adjusting layer contains a polysiloxane component in an acrylic skeleton A charging member coated with a protective layer made of a hybrid material, the polysiloxane of which has at least one alkyl group in silicon, and the protective layer is rich in acrylic components at the interface between the resistance adjusting layer and the protective layer. A charging member is disclosed that has a gradient structure rich in polysiloxane components on the surface of the layer (see, for example, Patent Document 6).

Differs from the electroconductive composition of the present invention, the electrically conductive composition of the present invention is different in that the crosslinking with a crosslinking agent to the hydroxyl group of the acrylic acid in the polymer, and has a charging member limiting.
Japanese Patent No. 3221385 JP 2002-298647 A JP 2003-3032 A Japanese Patent Laid-Open No. 2003-140418 JP 2002-323816 A JP 2003-76116 A

  The present invention has been made in consideration of the above-described circumstances, and in particular, prevents toner fusion (adhesion) of a component in which the toner directly contacts the surface, that is, a component incorporated in the developing device. It is another object of the present invention to provide a component that can properly charge a toner, has high wear resistance, and can achieve a long life. In particular, by using an acrylic silicon resin on the surface of the toner regulating member, the friction coefficient of the surface is lowered, the frictional force with the toner is reduced, and the toner is prevented from sticking over time. In addition, toner chargeability is improved, and high image quality as an image forming apparatus is achieved.

  Furthermore, the acrylic silicon resin having a hydroxyl group is cross-linked with a cross-linking agent to make it irreversible, improving mechanical strength (wear resistance), improving water resistance, and improving environmental resistance (resistance fluctuation). The object of the present invention is to reduce the coefficient of friction with silicon and improve the toner chargeability.

  Moreover, it aims at preventing the abrasion property of polysiloxane by copolymerizing with the acrylic resin formed from an acrylic acid polymer with favorable abrasion resistance.

  It is another object of the present invention to adhere the acrylic silicon resin so that the resin layer does not peel off due to stress during sliding with other members.

  Furthermore, it is an object of the present invention to exhibit flexibility and wear resistance by forming a urethane bond with an isocyanate group and a hydroxyl group, and to prevent problems such as cracking even when formed on an elastic substrate. Another object of the present invention is to improve toner chargeability by urethane bonding.

  In addition, since the polysiloxane is oriented (collected) in the surface direction, the alkyl group bonded to the polysiloxane is oriented on the surface, so that the water repellency is improved and the oil repellency due to the orientation of silicon is improved. The object is to reduce adhesion.

  Further, when the conductive member slides with another member while forming a nip, torque increase is prevented by a low coefficient of friction. In addition, when toner is present in the nip portion, the object is to prevent the heat generation and the fixation by improving the slipperiness of the toner.

  In addition, using a conductive member made of acrylic silicon resin as a toner regulating member of the developing device, contacting the toner carrier and regulating the toner prevents torque increase with a low coefficient of friction, toner chargeability An object of the present invention is to prevent toner adhesion due to orientation on the surface of silicon.

  In addition, by forming the toner regulating member into a roller shape and appropriately rotating it during non-development, the contact surface with the toner carrying member does not have to be the same surface over time. Another object of the present invention is to prevent streaks of the toner thin layer on the toner carrying member due to accumulation of toner aggregates, toner external additives, etc., and to prevent wear of the toner regulating member due to the same surface usage over time.

  In addition, by forming the nip (contact area) with the toner carrier by forming the hardness of the toner regulating roller within an appropriate range, it is possible to form an appropriate toner layer with an appropriate charge amount on the toner carrier. Objective.

  An object of the present invention is to prevent image defects such as scumming by preventing the passage of poorly charged toner.

  The object is to make the pressure on the contact nip between the toner carrier and the toner regulating member uniform so that the toner amount and the toner charge amount on the toner carrier are uniform.

  It is another object of the present invention to form an appropriate toner layer having an appropriate charge amount on the toner carrier by forming a nip (contact area) with the toner carrier.

  The object is to make the pressure on the contact nip between the toner carrier and the toner regulating member uniform so that the toner amount and the toner charge amount on the toner carrier are uniform.

It is an object of the present invention to prevent non-uniform pressure in a nip portion due to deformation of a conductive support when a toner regulating member is pressed against a toner carrier.

  In addition, by defining the surface roughness of the toner regulating roller, it is possible to prevent toner accumulation on the irregular surface of the toner regulating roller and to prevent toner fusion over time.

  In addition, by regulating the undulation of the surface of the toner regulation roller (having a longer wavelength than the surface roughness), the nip pressure between the toner carrier and the toner regulation roller is made uniform so that the amount of toner on the toner carrier and the toner charge The purpose is to make the amount uniform.

  Another object of the present invention is to prevent toner from adhering to the electrostatic toner regulating roller by defining the volume resistance value of the toner regulating roller.

  Another object of the present invention is to prevent toner from adhering to the electrostatic toner regulating roller by defining the volume resistance value of the conductive polymer layer forming the toner regulating roller.

  Another object of the present invention is to provide a stable image forming apparatus by preventing occurrence of stable image defects by preventing toner fusion between the toner carrier and the toner regulating member over time.

In order to solve the above-mentioned problems, the invention according to claim 1 forms an image in order to make contact with the image carrier on which the electrostatic latent image is formed and to attach the toner to visualize the electrostatic latent image. A developing device used in an image forming apparatus, comprising: a toner carrier that rotates occasionally; and a toner regulating roller that regulates the amount of toner adhering to the toner carrier and forms a toner thin layer on the toner carrier The toner regulating roller is stopped at the time of development, and at the time of non-development, as the toner carrier rotates in the direction opposite to the rotation direction at the time of image formation, friction with the toner carrier is caused. And an acrylic silicon resin having a layer made of a conductive member composed of at least two different materials, the outermost layer having a hydroxyl group, and a crosslinking agent. Before Hydroxyl groups characterized in that it is formed from a crosslinked product by crosslinking with a crosslinking agent.

According to a second aspect of the present invention, in the developing device according to the first aspect, the toner regulating roller has a roller hardness of JIS-A 60 to 80 degrees.

According to a third aspect of the present invention, in the developing device according to the first aspect, the toner regulating roller forms a conductive polymer layer on a conductive support, and a surface layer is formed on the upper surface thereof. The formed structure is characterized in that 0.16 ≦ (B × 2) /A≦0.40 where A is the outer diameter of the conductive support and B is the thickness of the conductive layer. And

According to a fourth aspect of the present invention, in the developing device according to the first aspect, a surface roughness Ra of the toner regulating roller is 0.8 μm or less .

According to a fifth aspect of the present invention, in the developing device according to the first aspect, the surface waviness Wca of the toner regulating roller is 0.3 μm or less .

According to a sixth aspect of the present invention, in the developing device according to the first aspect, the volume resistance of the toner regulating roller is 1.0 × 10 ^{4 to} 1.0 × 10 ¹² Ω. To do.

According to a seventh aspect of the present invention, in the developing device according to the first aspect, the volume resistance of the conductive polymer layer of the toner regulating roller is 1.0 × 10 ^{3 to} 1.0 × 10 ⁷ Ω. It is characterized by the following.

According to an eighth aspect of the present invention, in the developing device according to the first aspect, the acrylic silicon resin is made of an acrylic acid polymer and polysiloxane .

According to a ninth aspect of the present invention, in the developing device according to the first aspect, the resin layer formed of the acrylic silicon resin and the crosslinking agent is formed on a polymer substrate. To do.

According to a tenth aspect of the present invention, in the developing device according to the first aspect, the crosslinking agent has an isocyanate group, and forms a urethane bond with a hydroxyl group of acrylic silicon .

The invention described in Claim 11 is the developing device according to claim 1, wherein the pre-Symbol polysiloxane is selectively oriented toward the surface of the conductive member.

According to a twelfth aspect of the present invention, in the developing device according to the first aspect, the maximum static friction coefficient of the surface of the conductive member is 0.2 or less .

The invention described in Claim 13, developing equipment according to claim 1, the image bearing member, a charging means, an optical writing unit, a transfer member, the image forming the fixing device is characterized in that it is at least provided Features the device.

  According to the present invention, the conductive member used in the image forming apparatus is composed of at least two layers of different materials, the outermost layer is composed of an acrylic silicon resin having a hydroxyl group and a crosslinking agent, and the hydroxyl group is crosslinked. The outermost layer is composed of an acrylic silicone resin having a hydroxyl group and a crosslinking agent, and the hydroxyl group of the crosslinking agent is crosslinked and crosslinked by a conductive member characterized by being formed from a crosslinked product by crosslinking with an agent. By forming the product, it becomes water and oil repellency, low friction coefficient, so when sliding with other parts, it becomes difficult to cause stick slip and it is possible to prevent toner adhesion (fusion) Become.

  In addition, by forming a resin layer formed of an acrylic silicon resin and a crosslinking agent on a polymer substrate (layer), the adhesiveness of the resin layer is improved, so that a force such as twisting is applied to the resin layer. However, it does not peel off at the interface with the substrate.

  Since the crosslinking agent has an isocyanate group, it is possible to cause a crosslinking reaction at a low temperature, so that it can be used in a polymer substrate such as a thermoplastic resin or rubber. Moreover, since the urethane bond is formed by the reaction between the hydroxyl group of the acrylic silicon and the isocyanate group, it becomes possible to add wear resistance and flexibility of the resin layer.

  Further, by using the conductive member in the developing device as a toner regulating member that regulates the amount of toner that adheres to the toner carrier, it is possible to prevent the toner from adhering to the regulating member surface over time.

  Further, when the toner regulating member is a roller and stops during development, the toner carrying member rotates in a direction opposite to the rotation direction during image formation during non-development, and friction with the toner carrying member By rotating around the toner carrier, the contact surface between the regulating member and the toner carrier can be changed intermittently, so that the surface of the regulating roller can be a new part and wear over time. Changes can be prevented. Moreover, the heat storage of the heat generated by the contact can be reduced.

  Further, the toner regulating roller of the present invention is stopped at the time of development, and as the toner carrier rotates in a direction opposite to the rotation direction at the time of image formation at the time of non-development, friction with the toner carrier causes By incorporating a developing device that rotates together with the toner carrier into the image forming apparatus, a stable image can be obtained over time, and maintenance of the apparatus can be performed without replacing the developing device. Since only replenishment is required, user maintenance can be made very easy.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In general, a conductive member used in an OA device has a surface layer (functional surface) formed on a substrate having a high mechanical rigidity (strength) such as a metal in order to add various functions. As a configuration, a surface layer may be formed directly on a metal or the like, or a resin and rubber (elastomer) may be formed and a surface layer may be formed thereon. In many cases, the conductive member is used in contact with other components. In that case, one of the members needs to be an elastic body. The material of the substrate is appropriately selected from metal and polymer (rubber, plastic, elastomer).

  The acrylic silicone resin having a hydroxyl group can be obtained by copolymerizing a hydroxyl group-containing acrylic acid polymer and polysiloxane. As a ratio of the acrylic acid polymer and the polysiloxane, the ratio of dimethylsiloxane constituting the polysiloxane is preferably 10 to 20% of the entire copolymerization. If it is less than 10%, the amount of orientation on the surface becomes insufficient, so the friction coefficient increases and the water and oil repellency decreases. On the other hand, if it exceeds 20%, the compatibility with the acrylic acid polymer is deteriorated, so that it becomes difficult to function as a resin.

  There are various compounds having an isocyanate group (crosslinking agent), such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), Isophorone diisocyanate (IPDI), phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), cyclohexane diisocyanate, lysine ester triisocyanate, undecane triisocyanate, hexamethylene triisocyanate, triphenylmethane triisocyanate, and these Isocyanate compound polymers, derivatives, modified products, hydrogenated products, etc. It is.

Among these, aliphatic or alicyclic isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and polymers, derivatives and modified products thereof are particularly preferably used because they are excellent in ozone resistance and heat resistance. The isocyanate compound reacts with a hydroxyl group to form a crosslinked structure. In addition, the number of isocyanate groups in one molecule of the compound is desirably two or more, and the cross-linked structure with the acrylic silicone resin differs depending on the number of functional groups, and the three-dimensional structure develops as the number of functional groups per molecule increases. It becomes a rigid resin. Therefore, the isocyanate compound is examined according to the elasticity such as the hardness of the substrate.

  As shown in FIG. 1, the acrylic silicon resin used in the present invention has an acrylic silicon resin layer 22 disposed on a substrate 21, and dimethyl silicon 23 constituting polysiloxane is contained in the acrylic silicon resin layer 22. , Tends to be oriented in the surface direction. As shown in FIG. 2, methyl groups 24, which are alkyl groups of polysiloxane, are oriented on the outermost surface, thereby exhibiting water repellency (hydrophobicity).

  The oil repellency is expressed by silicon. FIG. 3 shows a state of a general coating film surface, and the surface 25 formed and formed by a general paint has a high hydrophilicity and is inferior in water repellency and oil repellency because a carboxyl group and a hydroxyl group exist. The reason why the polysiloxane is oriented in the surface direction is considered to be that the polysiloxane moves together as the solvent evaporates in addition to the poor compatibility between the polysiloxane and the acrylic part.

  Therefore, the degree of orientation varies depending on the type of solvent of the paint, the dilution rate, the coating method, and the like. Although the coating method will be described later, various known coating methods such as a dip method, a spray coating method, and a roll coating method are exemplified. In particular, the spray coating method is excellent in film thickness uniformity, and in this example, the spray coating method was used.

  In many cases, the conductive member is used in contact with other components, and in particular, in the contact charging device, the developing device, and the transfer device, sliding due to rotation or the like reduces motor torque, abnormal noise, A low coefficient of friction is required to prevent heat generation. Further, when the friction coefficient is high, banding (unevenness) occurs in the image due to sticking.

  The friction coefficient of the surface of the polymer layer such as rubber or plastic is very high and cannot be used alone. For this reason, a coating that exhibits various functions on the surface is performed. In the present invention, by using an acrylic silicon resin, a low friction coefficient can be achieved as compared with a fluorine-based resin generally used for reducing the friction coefficient. As a result, it was possible to reduce motor torque, reduce stress on toner in the developing section, and prevent banding. As a coefficient of friction, 0.7 or less is desirable, but when the sliding speed is increased, it is desirable that the friction coefficient is lower, and 0.2 or less is the best.

(Maximum friction coefficient measurement method) (See Fig. 4)
Put copy paper (Ricoh Type 6500) on a roller, attach a weight of 0.98N (100g weight) 30 on one side, and pull paper 32 from the other side with a digital push-pull gauge 31 at a constant speed (1mm / s) 10mm. Read the maximum value of. If the value at this time is F (N), the maximum coefficient of static friction (μ) is obtained by the following equation.

μ = [ln (F / 0.98)] / (π / 2)

It shows the current image device of the present invention in FIG. The operation of this developing device will be described. In FIG. 5, reference numeral 1 denotes a one-component developing device. In the housing 2 of the developing device 1, a developing roller 3, a toner supply roller 4, a toner conveying stirring member 5, and a toner regulating roller 6 as a toner regulating member are provided, and 7 is toner. Although not shown, a developing bias is applied to the developing roller to form an electric field with the image carrier. The toner regulating roller and the toner supply roller are connected so as to have the same potential as the developing roller.

(Development roller configuration)
The developing roller 3 is composed of an aluminum cylinder having a diameter of 26 mm.
As shown in FIG. 6, a rotating shaft 3a is formed at both ends of the aluminum cylinder. In FIG. 6, reference numeral 3c denotes a bearing. A surface layer 3b having a layer thickness of about 10 μm is formed on the surface of the aluminum cylinder. The surface roughness of the developing roller 3 is a smooth surface of 2 μm or less according to the JIS Rz standard. The surface layer 3b is formed by spraying a paint on the surface of an aluminum cylinder and curing it. As the coating material, one prepared by dispersing a polyester resin, a melamine curing agent, and ITO as conductive particles is used.

  Melamine curing agent is a substance containing amino groups, and is a substance (positive chargeability) that is opposite in polarity to negatively charged toner. ITO is based on alumina powder, and the surface of this alumina powder is coated with indium-doped tin oxide. It is a thing.

(Configuration of toner regulation roller)
(1) Elastic Layer Here, the toner regulating roller 6 is composed of an elastic roller because the developing roller 3 is made rigid. The hardness is lower than the hardness of the developing roller 3.
Thereby, the durability of the developing roller 3 is relatively improved. Materials include polyurethane, EPDM, natural rubber, butyl rubber, nitrile rubber, NBR, epichlorohydrin rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, and these A mixture is mentioned. Furthermore, a crosslinking agent and a vulcanizing agent can be added in order to form a rubbery substance by crosslinking. In this case, a vulcanization aid, a vulcanization accelerator, a vulcanization retarder, etc. can be used in both cases of organic peroxide crosslinking and sulfur crosslinking. In addition to the above, the properties of foaming agents, plasticizers, softeners, tackifiers, tackifiers, separating agents, mold release agents, extenders, colorants, etc., commonly used as rubber compounding agents are impaired. It is possible to add in the range which is not. In addition, thermoplastic elastomers such as chlorinated polyethylene, EEA, and EVA can also be used.

Here, as shown in FIG. 7, this toner regulating roller 6 forms an elastic layer 6b by coating nitrile-butadiene rubber (NBR) on the outer circumference of a stainless steel cylindrical cored bar (conductive support) 6a. did. The elastic layer can have a predetermined resistance value by adding or adjusting conductivity by adding a conductive agent. The conductive agent is not particularly limited, but lauryltrimethylammonium, stearylmethylammonium, octadodecyltrimethylammonium, hexadecyltrimethylammonium, modified fatty acid / dimethylethylammonium perchlorate, chlorate, borofluoride , Cationic surfactants such as quaternary ammonium salts such as halogenated benzyl salts such as sulfates, etosulphate salts, benzyl bromide salts, benzyl chloride salts, aliphatic sulfonates, higher alcohol sulfates, Anionic surfactants such as higher alcohol ethylene oxide addition sulfate, higher alcohol phosphate, higher alcohol ethylene oxide addition phosphate, higher alcohol ethylene oxide, polyethylene glycol fatty acid ester Antistatic agents such as polyhydric alcohol fatty acid ester nonionic antistatic agents such _{as, NaClO 4, LiAsF 6, LiBF} 4, NaSCN, KSCN, Li + such as NaCl, Na ^+, periodic containing ions of K ^+, etc. Table 1 Group 1 metal salt or NH ₄ ⁺ salt electrolyte, conductive carbon such as ketjen black, acetylene black, rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT Carbon, oxidized color (ink) carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium and other metals and metal oxides And conductive polymers such as polyaniline, polypyrrole, and polyacetylene.

In this case, the blending amount of these conductive agents is appropriately selected according to the type of the composition and the type of the conductive member, and is not particularly limited, but is 10 ² to 10 ¹⁰ Ω, preferably 10 ³ to 10 Adjusted to ⁷ Ω. In the present invention, resistance adjustment was performed using acetylene black.

By setting the volume resistance of the toner regulating roller to 10 ⁴ to 10 ¹² Ω, it is possible to prevent the occurrence of afterimages on the image on the high resistance side and the occurrence of background contamination on the low resistance side.

By setting the volume resistance of the conductive polymer layer to 10 ³ to 10 ⁷ Ω or less, the volume resistance of the entire toner regulating roller can be easily adjusted without adjusting the resistance of the surface layer. In addition, the surface layer can be set to a high resistance, and the surface property of the surface layer can be improved (surface roughness and undulation can be reduced).

  The roller hardness (on-axis hardness) is preferably JIS-A 60 to 80 degrees in order to secure a nip for forming an appropriately charged toner layer on the developing roller. If it is less than 60 degrees, it is necessary to lower the material hardness of the elastic layer, and if the hardness is low, the surface roughness increases in processing. If it exceeds 80 degrees, a sufficient nip with the developing roller cannot be secured.

  By setting the roller hardness to JIS-A 60 to 80 degrees, it is possible to form a nip that can make the toner adhesion amount and the toner charge amount appropriate on the toner carrier. Since the passage of the low-charged toner can be prevented, the background stain can be prevented.

  The thickness of the elastic layer is appropriately set according to the type, form, size, layer configuration, etc. of the member, and is not particularly limited, but in order to make the contact pressure with the developing roller uniform. In this case, the ratio of the outer diameter (A) of the conductive support of the toner regulating roller to the thickness (B) of the elastic conductive layer is preferably 0.16 ≦ (B × 2) /A≦0.40. . If it is less than 0.16, the elasticity of the elastic layer does not contribute and is almost equal to the hardness of the conductive support, so that a sufficient nip with the developing roller cannot be formed.

  In addition, since the load applied to the toner becomes strong because it is close to line contact, problems such as pulverization of the toner or burying of the external additive occur. On the other hand, if it exceeds 0.40, the nip with the developing roller becomes wide, and the passage time of the toner in the nip becomes long. The toner regulating roller not only satisfies the above relational expression but also requires a minimum outer diameter of the conductive support as rigidity. The minimum outer diameter of the support is 8 mm or more, preferably 10 mm or more. As a result, an unprecedented long-life developing device can be provided.

  The elastic layer is formed on the conductive support by a molding method such as extrusion molding or press molding. Thereafter, in order to finish the shape, cylindrical polishing was performed, and in order to further reduce the surface roughness and waviness, finisher processing with a lapping sheet was performed. By performing such processing, an elastic layer having a surface roughness Ra of 0.8 μm or less and a waviness Wca of 0.3 μm or less was obtained (measurement method is as follows).

  By setting the surface roughness to Ra 0.8 μm or less, generation of toner aggregates due to the accumulation of fine powder toner can be prevented, and toner fixation can be prevented. In addition, by setting the swell to Wca 0.3 μm or less, it is possible to prevent the occurrence of uneven toner thin layer on the toner carrier. Here, the reason for using the polar rubber is to increase the adhesive strength of the surface layer 6c to the elastic layer 6b and to prevent the peeling. Thus, it is possible to form a good image with little background contamination by preventing the toner from adhering to the non-image portion when the image is printed.

  It is desirable to connect the elastic layer 6b and the cylindrical cored bar 6a via an adhesive 6m. When the elastic layer 6b is bonded to the cylindrical cored bar 6a using the adhesive 6m in this way, peeling between the cylindrical cored bar 6a and the elastic layer 6b can be prevented, and the shape of the elastic layer 6b can be kept stable. . The adhesive 6m is preferably conductive. By making the adhesive 6m conductive, a good image with little background stain can be formed.

(Hardness measurement method)
Using a type A hardness meter, a load of 1 kg was applied, and the hardness meter was pressed onto the roller shaft to obtain a measured value after 30 seconds.
(Surface roughness, waviness measurement method)
Measuring instrument; Kosaka Laboratory SE-30H
Measurement conditions Surface roughness: Longitudinal magnification: × 2000, Horizontal magnification: × 20,
Measurement length: 2.5mm,
Feed: 0.5mm / s,
Cut-off: λc 0.8mm
Swell; Vertical magnification: × 2000, Horizontal magnification: × 5,
Measurement length: 25mm,
Feed: 2mm / s,
Cut off: fh0.8mm, fl2.5mm

(2) Surface layer The surface layer is formed on the substrate by various known coating methods such as dipping, spray coating, and roll coating. The film thickness of the surface layer is determined in consideration of the amount of wear according to the required life of each member, and is arbitrary. However, in order to cope with the recent increase in image quality, it is desirable that the surface roughness of the member be as small as possible. Therefore, in forming the surface layer, it has become necessary to smooth the roller surface. For this purpose, a coating method is performed in which the film thickness is equal to or greater than the surface roughness of the substrate and the irregularities of the elastic layer are filled. In coating, the resin is dissolved in a solvent and diluted in order to adjust the viscosity of the paint suitable for each method. After coating, it is desirable to perform heating and baking in order to promote the volatilization of the solvent and the crosslinking reaction. A surface layer 6c made of an acrylic silicon resin and an isocyanate crosslinking agent was formed on the surface of the elastic layer 6b by spray coating, and was cured by heating in a hot air drying oven at 80 ° C. for 1 hour in order to promote the crosslinking reaction. . The layer thickness of the surface layer 6c made of the acrylic silicon resin is 20 μm. Thus, the surface roughness after forming the surface layer was Ra 0.8 μm or less and the waviness Wca 0.3 μm or less (the measurement method is the above). In the present embodiment, the surface layer is not imparted with conductivity, but may be rendered conductive with a conductivity imparting agent according to the specifications of the system.

(3) Resistance value (measurement method is shown in FIGS. 14A and 14B)
The resistance value of the toner regulating roller is preferably 1.0 × 10 ^{4 to} 1.0 × 10 ¹² Ω. If it exceeds 1.0 × 10 ¹² Ω, an afterimage is generated in the image. Further, when the density is 1.0 × 10 ⁴ Ω or less, the surface layer must be filled with a conductive agent, surface roughness and undulation increase, and the toner thin layer on the developing roller becomes uneven. Occurs.
The measurement conditions are applied voltage: 100 V, voltage application time: 15 seconds, electrode diameter: φ26, and measurement is performed under the above-mentioned conditions by applying a load of 18 N to both ends of the toner regulating member (FIG. 14B).

(Rotation operation method of toner regulating roller)
The toner regulating roller 6 has rotating shaft portions 6d at both ends thereof. The rotary shaft portion 6d is rotatably supported by the inner cylinder 6f of the one-way clutch 6e shown in FIG. A ball 6h is provided between the inner cylinder 6f and the outer cylinder 6g of the one-way clutch 6e, and a biting protrusion 6i is provided. In the one-way clutch 6e, when the inner cylinder 6f is rotated in the direction of the arrow D, the ball 6h bites into the biting protrusion 6i and prevents the toner regulating roller 6 from rotating. When the inner cylinder 6f rotates in the direction opposite to the arrow D direction, the bit 6h and the biting protrusion 6i are released, and the toner regulating roller 6 is rotated smoothly. Here, the toner regulating roller 6 in the arrow D direction is rotated. The rotation in the direction opposite to the rotation corresponds to the rotation in the direction of arrow C shown in FIG. 5 (the driven rotation direction during non-image formation).

  The toner regulating roller 6 is urged by a pair of urging springs 8 in a direction (contact direction) in contact with the developing roller 3. Here, the biasing spring 8 is configured to bias the one-way clutch 6e.

  The developing roller 3 is rotated in the direction of arrow A shown in FIG. 5 at the time of image formation, so that the toner 7 is supplied from the upstream side 9 to the downstream side 10 of the toner. Further, the developing roller 3 is rotated in the direction B opposite to the arrow A direction when the image is not formed. The toner regulating roller 6 is stopped when the developing roller 3 rotates in the direction of arrow A shown in FIG. 5, and when the developing roller 3 rotates in the direction of arrow B, friction contact with the developing roller 3 causes an arrow C direction. It is driven and rotated.

  The toner regulating roller 6 can be forced to rotate in the opposite direction (arrow C direction) to the rotation direction (arrow B direction) of the developing roller 3 during non-image formation, but the configuration of the developing device 1 becomes complicated. Also, depending on the configuration of the drive gear, side effects such as banding may occur, so care must be taken.

  According to the developing device 1, the toner 7 formed by the developing roller 3 and the toner regulating roller 6 and accumulated in the wedge-shaped region 11 existing on the upstream side 9 of the toner 7 can be discharged back to the upstream side 9. Therefore, the wedge-shaped region 11 can be prevented from being clogged and fixed.

  The elastic biasing force F of the toner regulating roller 6 to the developing roller 3 connects the rotational center O1 of the developing roller 3 and the rotational center O2 of the toner regulating roller 6 as shown in FIG. When the direction component F1 in the direction along the line segment L and the orthogonal direction component F2 orthogonal to the direction component F1 are decomposed, the orthogonal direction component F2 is not imaged at the contact point between the developing roller 3 and the toner regulating roller 6. It is desirable that the toner restricting roller 6 is directed in the driven rotation direction (arrow C direction).

  With this configuration, even if the friction force of the toner regulating roller 6 is small, the toner regulating roller 6 can be driven and rotated more reliably by the developing roller 3.

  As shown in FIG. 10, when the elastic layer 6b is ground with the grinding wheel 12, as shown in FIG. 11, eyes 6j are formed on the surface of the elastic layer 6b of the toner regulating roller 6. If the toner restricting roller 6 is incorporated in the developing device 1 so that the developing roller 3 at the time of non-image formation is rotated in a direction against the forward direction of the elastic layer 6b, the toner restricting roller 6 of the toner restricting roller 6 is formed at the time of image formation. Since the static friction coefficient with respect to the developing roller 3 can be reduced, it is possible to suppress the frictional heat generation of the developing roller 3 during image formation, and to reduce the welding of the toner 7 to the developing roller 3.

  On the other hand, since the frictional force of the toner regulating roller 6 against the developing roller 3 can be increased during non-image formation, the driven rotation of the toner regulating roller 6 during non-image formation can be ensured.

  Further, the frictional force can be adjusted by effectively using the eyes 6j generated when the toner regulating roller 6 is manufactured.

  Further, as shown in FIG. 12 (a), the outer diameter of the elastic layer 6b is a crown (drum) shape in which the diameter smoothly increases from the direction of the rotating shafts 6d and 6d in the extending direction of the cylindrical core 6a toward the center. If so, the contact pressure of the toner regulating roller 6 with respect to the developing roller 3 can be made more uniform.

  The shape of the outline when the elastic layer 6b is below the cross section along the longitudinal direction is preferably a quadratic or higher-order curve or an arc curve. That is, as shown in FIG. 12B, for example, the developing roller 3 is urged on both sides of the rotating shaft portion 6d of the toner regulating roller 6 formed of an elastic layer 6b whose contour shape has corner portions k1 to k4. Only the corner portions k1 to k4 are in contact with the developing roller 3, and the portions other than the corner portions k1 to k4 are recessed and do not come into contact with the developing roller 3. However, as shown in FIG. When formed into a curve having a smooth contour line as shown, the elastic layer 6b comes into contact with all the portions in the longitudinal direction of the developing roller 3 uniformly, and the contact portions can be homogenized. As shown in FIG. 12A, the contour shape of the toner regulating roller 6 is an experiment in which the length L1 and the height H1 in the longitudinal direction of the elastic layer 6b are appropriately considered. It may be determined by

The developing device is in the form of FIG.
Although not shown, a developing bias is applied to the developing roller in order to form an electric field with the image carrier. The toner regulating roller and the toner supply roller are connected so as to have the same potential as the developing roller.
A load of 24 N was applied to both ends of the toner regulating roller by springs.

(Development roller)
The cored bar is a three-piece aluminum pipe with a diameter of 26 mm (t = 1.5 mm) in which a rotating shaft with a diameter of 8 mm is press-fitted at both ends.
Surface layer: Polyester resin and melamine resin in a solid content ratio of 7 to 3 and ITO in an amount of 55 wt% (based on the resin solid content) were dispersed with a paint shaker and diluted with MEK and toluene to obtain a paint. A resin layer having a film thickness of about 10 μm was formed on the core metal by spray coating, and then heated and baked at 160 ° C. for 1 hour in a hot air oven to crosslink the polyester resin and the melamine resin. Thereafter, the surface was finished by polishing with a # 1000 wrapping film. The surface roughness Ra was 0.4 μm or less.

(Toner regulation roller)
Forming method of elastic layer The cored bar is coated with a conductive adhesive at both ends φ6mm and elastic layer forming φ12mm, then set in a mold, and filled with a rubber material kneaded with carbon black, vulcanizing agent, etc. After press forming, demolding, grinding, finishing the outer diameter, and polishing with # 1000 and # 1500 wrapping films to finish φ14 mm. The shape was a crown shape so that the center portion was thicker than the end portion direction, and the quaternary expression was used such that the outer diameter difference between the end portion and the center portion was 240 μm.

(Method for forming surface layer)
A resin layer having a film thickness of about 10 μm is formed on the elastic layer surface by spray coating with the materials shown in the following examples and comparative examples shown in Table 1, and then heated and baked in a hot air furnace. A surface layer was obtained.

Kawakami Paint Co., Ltd. Muki Coat 3000VH
Yamamoto Ceramics Co., Ltd. Ceratop Silicone Si
Kansai Paint Co., Ltd. Ares Silicon Shinto Paint Co., Ltd. High Ten Top KS-057
Asahi Glass Co., Ltd. Lumiflon Nippon Atchison Co., Ltd. Emeralon Nagase ChemteX Co., Ltd. Zithrone EC06

  Next, a toner regulating roller coated with each surface material shown in Table 1 was incorporated in the developing device, and durability evaluation was performed in an image forming apparatus (IpSiO Color6500) as shown in FIG.

As an operating condition, one cycle was defined as rotating the developing roller 3 in the image forming direction for 1 minute, then performing reverse rotation for 0.1 second, and then stopping for about 10 seconds. The process speed was 20 sheets per minute with A4 paper. A 5% chart was used for the image pattern.
Table 2 shows the result of evaluating the toner adhesion state on the surface of the toner regulating roller and the background contamination due to the toner adhesion to the non-image area for each number of sheets.

  The acrylic silicon resins of Examples 1 to 4 are good for toner fixation, and therefore, no scumming occurred in the non-image portion of the image even with 30000 prints.

A structural cross-sectional view of a conductive member of the present invention. It is a schematic diagram which shows the orientation of the methyl group of the polysiloxane of this invention. It is a schematic diagram which shows the surface state without the orientation of the general coating-film surface. It is a schematic diagram which shows the maximum friction coefficient measuring method used for this invention. A structural cross-sectional view of the current image device of the present invention. 2 is a cross-sectional view of a developing roller used in the present invention. FIG. FIG. 3 is a cross-sectional view of a toner regulating roller of the present invention. FIG. 4 is a cross-sectional explanatory view of a rotation control mechanism for a toner regulating roller of the present invention. It is explanatory drawing of the elastic urging | biasing force to the developing roller of the regulation roller of this invention. It is explanatory drawing of the grindstone grinding of the elastic layer of the roller of this invention. FIG. 6 is an explanatory diagram of the relationship between the rotation direction of the roller of the present invention and the reverse order of the roller surface. It is sectional drawing of the crown shape of the roller of this invention. 1 is a configuration diagram of an example of an image forming apparatus using a roller of the present invention. It is structure explanatory drawing of the resistance value measuring method used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single component developing device 2 Case 3 Developing roller 3a Rotating shaft 3b Surface layer 3c Bearing 4 Toner supply roller 5 Toner conveying stirring member 6 Toner regulating roller 6a Cylindrical cored bar 6b Elastic layer 6d Rotating shaft 6e One-way clutch 6f Inner cylinder 6 g Outer cylinder 6 h Ball 6 i Protrusion 7 Toner 8 Energizing spring 9 Toner upstream 10 Downstream 11 Wedge-shaped region 12 Grinding wheel O 1, O 2 Rotation center F Elastic urging force F 1 Direction component F 2 Orthogonal direction component L Line segment

Claims (13)

A toner carrier that is rotated at the time of image formation in order to make the electrostatic latent image visible by contacting the image carrier on which the electrostatic latent image is formed and attaching the toner; and the toner adhering to the toner carrier A developing device used in an image forming apparatus, comprising a toner regulating roller that regulates the amount and forms a toner thin layer on the toner carrier,
The toner regulating roller is stopped during development, and when not developed, the toner carrier is rotated by the friction with the toner carrier as the toner carrier rotates in the direction opposite to the rotation direction during image formation. It rotates together with the body and has a layer made of a conductive member composed of at least two layers of different materials, and the outermost layer is made of an acrylic silicon resin having a hydroxyl group and a crosslinking agent, A developing device, wherein a hydroxyl group is formed from a crosslinked product formed by crosslinking with a crosslinking agent. The developing device according to claim 1 , wherein the toner regulating roller has a roller hardness of JIS-A 60 to 80 degrees. The toner regulating roller has a configuration in which a conductive polymer layer is formed on a conductive support and a surface layer is formed on the upper surface thereof. The outer diameter of the conductive support is A, and the conductive layer 2. The developing device according to claim 1 , wherein when the thickness is B, 0.16 ≦ (B × 2) /A≦0.40. The developing device according to claim 1 , wherein the toner regulating roller has a surface roughness Ra of 0.8 μm or less. 2. The developing device according to claim 1 , wherein a surface waviness Wca of the toner regulating roller is 0.3 [mu] m or less. 2. The developing device according to claim 1, wherein a volume resistance of the toner regulating roller is 1.0 × 10 ^{4 to} 1.0 × 10 ¹² Ω. The developing device according to claim 1, wherein a volume resistance of the conductive polymer layer of the toner regulating roller is 1.0 × 10 ^{3 to} 1.0 × 10 ⁷ Ω or less. The developing device according to claim 1, wherein the acrylic silicon resin is made of an acrylic acid polymer and polysiloxane. 2. The developing device according to claim 1, wherein the resin layer formed of the acrylic silicon resin and the crosslinking agent is formed on a polymer substrate. The developing device according to claim 1, wherein the crosslinking agent has an isocyanate group and forms a urethane bond with a hydroxyl group of acrylic silicon. The developing device according to claim 1, wherein the polysiloxane is selectively oriented in a surface direction of the conductive member. The developing device according to claim 1, wherein a maximum static friction coefficient of the surface of the conductive member is 0.2 or less. 2. An image forming apparatus comprising: the developing device according to claim 1; and a developing device mounted thereon, an image carrier, a charging unit, an optical writing unit, a transfer member, and a fixing device.

Images