JP4587168B2 - Developing apparatus and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which prevents density unevenness on an image caused when it is used for a long time, and gives stable images over a prolonged period of time. <P>SOLUTION: The developing device has a developer carrier and a developing container capable of storing a nonmagnetic one-component developer, wherein a thin layer of the nonmagnetic one-component developer is formed on a surface of the developer carrier and an electrostatic latent image formed on a surface of a latent image holding member is visualized with the nonmagnetic one-component developer forming the thin layer. The developing device satisfies the formula (I): y&le;4.97Ln(x)+41.5 and the formula (II): 20&le;y&le;38, wherein x is a microcompressive strength (kg/mm<SP>2</SP>) of the nonmagnetic one-component developer; and y is a surface microhardness (MD1) (&deg;) of the developer carrier. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a developing device used in an electrophotographic apparatus. More specifically, the present invention relates to a developing device that can prevent occurrence of density unevenness on an image when used for a long time and can obtain a stable image over a long period of time.

  In a printer using an electrophotographic method, a photosensitive member, which is a latent image carrier, is uniformly charged by a charging roller, and an electrostatic latent image is formed by removing a part of the charge with a laser or the like. Next, the developer in the developer container is uniformly applied on the developing roller as the developer carrying member with appropriate charges by the developer supplying roller and the developer regulating member, and developed at the contact portion between the photosensitive member and the developing roller. The agent is transferred (developed). Thereafter, the developer on the photoconductor is transferred onto a recording sheet by a transfer roller and fixed by heat and pressure. The developer remaining on the photoconductor is removed by a cleaning blade, and a series of processes is completed.

  At this time, the developing roller is always in pressure contact with the photosensitive member and the developer regulating member, and when performing development, the developer is interposed between the developing roller and the photosensitive member, and the developing roller and the developer regulating member. It is in pressure contact. The developer that is not transferred to the photoreceptor is peeled off by the developer supply roller, returned to the developing container again, stirred in the container, and again conveyed onto the developing roller by the developer supplying roller. As a result of repeating these steps, the developer is subjected to great stress.

  Therefore, for the purpose of reducing stress on the developer, a developing roller made of a material made of a low-hardness elastic body has been used. In particular, the material properties near the surface layer of the developing roller have a great influence on the developer, and the selection of the material properties plays a very important role.

  The following is mentioned as a prior art of a developer carrier. (1) The developer carrying member has a coating layer made of a material containing a resin having a low glass transition point on the surface of the conductive elastic layer, and the dynamic elastic modulus and loss tangent tan δ of the coating layer are predetermined. If it is within the range, a stable image can be obtained without toner filming (a phenomenon in which the developer melts and adheres to the surface of the developer carrying member) or cracking of the coating layer even when used for a long time or for a long time. Is obtained (see Patent Document 1). (2) When the surface layer of the developer carrier is formed of a polymer composition in which a solvent-soluble polymer (component a) and a blocked isocyanate (component b) are blended at a specific blending ratio, toner filming does not occur. It is excellent in durability (see Patent Document 2). In these conventional techniques, it is said that toner filming can be prevented by devising a surface layer of the developer carrying member.

Moreover, the following is mentioned as a prior art which paid its attention to the material property of developer (toner) itself. (3) By increasing the mechanical strength of the toner to a predetermined value or more, it becomes difficult for the toner to be crushed, and it is possible to prevent the toner from adhering or aggregating to the pressure contact member or the developer carrying member. The amount and developer transportability are stable over a long period of time (see Patent Document 3). (4) By setting the mechanical strength of the toner within a predetermined range, the stress in the developing machine can be reduced, the toner can be prevented from being pulverized and adhered to the carrier surface, and stable image characteristics and fixability can be obtained ( (See Patent Document 4). In these conventional techniques, the developer (toner) has a mechanical strength within a predetermined range, whereby the developer can be prevented from being crushed (pulverized) or deteriorated.
JP 2001-34059 A JP-A-11-267583 JP-A-6-102699 JP-A-9-319136

  In recent years, the required performance of an electrophotographic apparatus has become higher with the increase in speed and the quality of image quality. More specifically, there is a strict demand for differences in fine image characteristics in the environment, image durability accompanying high-speed operation, and component durability. Various problems have become apparent which cannot be achieved by simply applying a carrier or a developer. For example, an unprecedented new problem that density unevenness appears on the image in the direction perpendicular to the image forming direction when a developer carrier that has been treated to prevent toner filming on the surface is used for a long time. There has occurred.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a developing device capable of preventing density unevenness on an image that occurs when used for a long time and obtaining a stable image over a long period of time. .

The present invention
A developer carrier, a non-magnetic one-component developer, a developing container in which the non-magnetic one-component developer is disposed, and a developer regulating member,
In the developing device configured such that a thin layer of the non-magnetic one-component developer is formed on the surface of the developer carrying member by the developer regulating member.
Micro compression strength of the non-magnetic one-component developing agent is 0.5 ~1.0kg / mm ^2,
The developer carrier has at least a shaft, a conductive elastic layer provided around the shaft, and a conductive surface layer provided on the conductive elastic layer,
The conductive surface layer contains a polyurethane obtained by polymerizing the polyurethane polyol prepolymer (A) and the isocyanate compound (B),
The polyurethane polyol prepolymer (A) is a chain extension of a bifunctional polyol compound (a) and a difunctional isocyanate compound (b) diphenylmethane diisocyanate, and has a weight average molecular weight Mw of 10,000 to 50,000 and a molecular weight. A linear polyurethane polyol prepolymer having a dispersity Mz / Mw of 2.5 or less, and
A developing device having a surface microhardness (MD1) of 35 to 38 ° of the developer carrying member .

According to another aspect of the present invention, there is provided an electrophotographic apparatus comprising: the developing device described above; and a latent image carrier disposed in pressure contact with the developer carrier in the developing device.

  According to the developing device of the present invention, it is possible to prevent density unevenness on an image that occurs when used for a long time, and a stable image can be obtained over a long period of time.

  The inventors of the present invention have investigated the cause of the above-mentioned problem, and have obtained new knowledge. Even if the developer does not melt and adhere to the surface of the developer carrying member, density unevenness on the image occurred after long-term use, but as a result of observing the density unevenness on the image, the density unevenness is in the image forming direction. On the other hand, it was found that it occurred in the vertical direction. Further, when the occurrence position of density unevenness was examined, it was found that there was a relationship between the density of the image and the outer diameter of the developer carrier. The result showed that the concentration was thin when the outer diameter was small, whereas the concentration was thick when the outer diameter was large. The difference in the outer diameter of the developer carrying member is caused by the fact that the developer continues to receive great stress from the developer regulating member and the developer carrying member in the process of circulating in the developer container, and the circulation process is prolonged. It is considered that the external additive for imparting tribo to the developer and the external additive for maintaining the fluidity of the developer are embedded in the developer surface or peeled off from the surface. As a result, the developer loses fluidity and charge control ability, and a phenomenon occurs such that the developer is scattered or not transferred when transferred to the latent image carrier. In other words, if there are parts with different outer diameters in the developer carrying body, the nip width with the developer regulating member differs depending on the position, the difference in the time during which the developer is frictionally charged, and the larger outer diameter. It has been found that the difference in the charge imparting ability of the developer appears at a small value, and as a result, density unevenness appears in the direction perpendicular to the image forming direction.

  As a result of intensive studies to achieve the above-described object, the present inventors have determined that the developer satisfies a specific relationship between the mechanical strength near the surface of the developer carrier and the mechanical strength of the developer. It has been found that the above-mentioned problems can be solved when a carrier and a developer are combined.

  The present invention is capable of forming a thin layer of a non-magnetic one-component developer by carrying a non-magnetic one-component developer on the surface of the developer carrying member. A developing device for visualizing an electrostatic latent image by attaching it to the surface of a latent image holding member on which an electrostatic latent image is formed, satisfying the following formulas (I) and (II): It is.

y ≦ 4.97Ln (x) +41.5 (I)
20 ≦ y ≦ 38 (II)
x: Micro compressive strength of non-magnetic one-component developer [Unit: kg / mm ² ]
y: Surface microhardness of developer carrying member (MD1) [Unit: °]
According to the present invention, density unevenness on an image can be prevented, and a stable image can be obtained even when used for a long time. The surface microhardness of the developer carrier that satisfies the above formulas (I) and (II) and the microcompressive strength of the nonmagnetic one-component developer (hereinafter simply referred to as “developer”) are shown in the graph of FIG. In the hatched area.

  When the surface microhardness of the developer carrying member and the micro compressive strength of the developer satisfy the above relational expression (I), the flexibility of the vicinity of the surface of the developer carrying member with respect to the hardness of the developer is sufficient, The developer is not subjected to great stress in the process of circulating in the developing container, and the developer can sufficiently exhibit fluidity and charge control ability even when the circulation process is prolonged. It is more preferable to satisfy the following relational expression (I ′).

y ≦ 4.32Ln (x) +38 (I ′)
However, the surface microhardness of the developer carrier needs to satisfy the above formula (II), that is, 20 to 38 °. When the surface microhardness exceeds 38 °, the hardness is too high for a high-gloss developer capable of handling high speed, and the developer deteriorates faster, so that it cannot be used for a long time. When the angle is less than 20 °, the surface of the developer carrying member becomes sticky and cannot be used as a developer carrying member. The surface microhardness of the developer carrying member is preferably 25 to 35 °.

The fine compressive strength of the developer is preferably in the range of 0.1 to 1.5 kg / mm ² . More preferably 0.1~1.0kg / mm ^2, further preferably 0.5~1.0kg / mm ^2. When it is larger than 1.5 kg / mm ² , since the surface of the developer is hard, the anchor effect can be brought out when the external additive is kneaded with a mixer, and the external additive cannot be retained for a long time. There is a case. If it is less than 0.1 kg / mm ^2, it may not be possible to withstand the toner strength.

Among the developing devices described above, the developing device of the present invention includes a developer carrier, a nonmagnetic one-component developer, a developing container in which the nonmagnetic one-component developer is disposed, and a developer regulating member. A developing device configured to form a thin layer of the non-magnetic one-component developer on the surface of the developer-carrying member by the developer-regulating member, the non-magnetic one-component developer the micro compression strength degree is 0.5 ~1.0kg / mm ^2, the developer carrying member, the shaft member and a conductive elastic layer provided around the shaft member, the conductive elastic layer A conductive surface layer provided thereon, and the conductive surface layer contains a polyurethane obtained by polymerizing a polyurethane polyol prepolymer (A) and an isocyanate compound (B), The polyurethane polyol prepolymer (A) is a bifunctional poly The chain compound (a) and diphenylmethane diisocyanate, which is a bifunctional isocyanate compound (b), are chain-extended and have a weight average molecular weight Mw of 10,000 to 50,000 and a molecular weight dispersity Mz / Mw of 2.5 or less. It is a chain polyurethane polyol prepolymer, and the developer carrier has a surface microhardness (MD1) of 35 to 38 ° .

  FIG. 2 is a diagram illustrating a schematic configuration of an image forming apparatus including the developing device of the present invention.

  In this image forming apparatus 3, the photosensitive drum 21 as a latent image carrier rotates in the direction of arrow A, and the surface of the photosensitive drum 21 that has passed therethrough by the antistatic roller 22 provided in the charging device for charging the photosensitive drum 21. These areas are uniformly charged, and in this charged area, an electrostatic latent image is formed on the surface by laser light 23 which is an exposure means for writing an electrostatic latent image. The electrostatic latent image is disposed in proximity to the photosensitive drum 21 and is given toner as a developer 28 by the developing device 2 held in a process cartridge (not shown) that is detachable from the image forming apparatus main body. The toner image is developed and visualized as a toner image.

  For development, a method such as so-called reversal development in which a toner image is formed on the exposed portion can be used. The visualized toner image (image) on the photosensitive drum 21 is transferred onto a transfer paper 33 such as paper by a transfer roller 29. The paper 33 to which the toner image has been transferred is subjected to a fixing process by the fixing device 32, discharged outside the device, and the printing operation is completed. The transfer roller 29 is configured to press the transfer paper 33 from the back surface to the area of the photosensitive drum 21 where the toner image is held to transfer the toner image onto the surface of the transfer paper, and holds the toner image of the photosensitive drum 21. Transfer of the toner image is promoted by charging opposite to the area. The transfer sheet 33 is pressed against the surface of the photosensitive drum 21 by automatically inserting the transfer sheet 33 into a portion where the photosensitive drum 21 and the transfer roller 29 are in contact with each other. Achieved.

  On the other hand, the toner remaining on the photosensitive drum 21 without being transferred is scraped off by the cleaning blade 30 and stored in the waste toner container 31, and the same process is repeated on the cleaned photosensitive drum 21 to repeat the above process. Can be copied and a new image can be transferred.

  In the illustrated example, the developing device 2 includes a developer container 34 that contains the developer 28, and a developer carrier that is located in an opening extending in the longitudinal direction in the developer container 34 and that is opposed to the photosensitive drum 21. Development roller 25, and the electrostatic latent image on the photosensitive drum 21 is developed and visualized.

  The developing roller 25 is in contact with the photosensitive drum 21 with a contact width. In the developing device 2, the developer supply roller 26 having elasticity is brought into contact with the contact portion of the developer regulating member 27 with the surface of the developing roller 25 in the developing container 34 on the upstream side in the rotation direction of the developing roller 25. And is rotatably supported. As the structure of the developer supply roller 26, a foamed skeleton-like sponge structure or a fur brush structure in which fibers such as rayon and nylon are planted on a cored bar supplies toner 28 to the developing roller 25 and peels off undeveloped toner. It is preferable from the point of taking. For example, a developer supply roller 26 having a diameter of 16 mm in which a polyurethane foam is provided on a metal core can be used.

  The contact width of the developer supply roller 26 with respect to the developing roller 25 is preferably 1 to 8 mm, and it is preferable that the developing roller 25 has a relative speed at the contact portion. The width is set to 3 mm, and a driving means (not shown) is set at a predetermined timing so that the peripheral speed of the developer supply roller 26 is 50 mm / s during development operation (the relative speed with respect to the developing roller 25 is 130 mm / s). It can be rotated.

  As described above, the developing device of the present invention includes at least a developing roller as a developer carrying member and a developing container capable of storing the developer.

  As the developer carrier provided in the developing device of the present invention, for example, as shown in FIG. 1, a shaft core 11 as a shaft, a conductive elastic layer 12 provided around the shaft, A developing roller 1 having a conductive surface layer 13 provided on a conductive elastic layer can be used.

  Since the developer carrying member used in the developing device of the present invention is generally used with an electrical bias applied or grounded, the shaft body is usually a conductive substrate, so-called A form of the shaft core 11 is adopted. The shaft core 11 is made of a conductive material sufficient to apply a predetermined voltage. In the developer carrier used in the electrophotographic apparatus, the outer diameter of the shaft is usually in the range of 4 to 10 mm.

  The conductive elastic layer 12 serving as a base layer is usually formed as a molded body using rubber as a resin component and blending a desired amount of a conductivity-imparting substance. As the rubber, various rubbers conventionally used for elastic rollers can be used. The thickness of the conductive elastic layer is usually in the range of 0.5 to 5.0 mm.

  Examples of the conductivity-imparting material blended in the conductive elastic layer and the conductive surface layer described later include electron conductive materials such as carbon black, graphite, metal filler, and metal oxide whisker, and ion conductive materials such as metal salts. Can be mentioned. Among these, carbon black, which is inexpensive in cost, is widely used.

The conductive elastic layer 12 preferably has a volume resistivity of 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm, and more preferably 1 × 10 ⁴ to 1 × 10 ⁸ Ω · cm.

  The conductive surface layer 13 is usually a resin such as polyurethane, acrylic, nylon, or silicone as a resin component, or a modified product thereof. A desired amount of a conductivity-imparting substance is blended and dissolved in a solvent such as MEK. It is formed by coating the surface of the conductive elastic layer with the dispersed paint. Among them, it is preferable to use polyurethane as described below as a raw material main component. The thickness of the conductive surface layer is usually in the range of 5 to 30 μm.

When carbon black is used as the conductivity-imparting substance blended in the conductive surface layer, the carbon black content in the conductive surface layer is preferably in the range of 10 to 40% by mass, and 15 to 35% by mass. % Is more preferable. The volume resistivity of the conductive surface layer is preferably 1 × 10 ³ to 1 × 10 ¹⁰ Ωcm, and more preferably 1 × 10 ⁴ to 1 × 10 ⁸ Ωcm.

  The conductive surface layer that is the outermost layer of the developer carrying member preferably contains a spherical filler.

  As the spherical filler, acrylic, nylon, silicone, urethane, polyester or the like is used as a resin component. The spherical filler refers to, for example, a nearly spherical powder formed by a polymerization method such as a suspension polymerization method or an emulsion polymerization method. A spherical filler having an average particle diameter of 5 to 30 μm is preferably used because of the relationship with the thickness of the conductive surface layer. The blending amount is appropriately adjusted in order to obtain the target surface roughness, but is used in the range of 5 to 60% by mass with respect to the binder resin.

  Here, polyurethane that can be suitably used as a resin component for forming the conductive surface layer will be described.

  The polyurethane is a polyurethane obtained by polymerizing a polyurethane polyol prepolymer (A) and an isocyanate compound (B), and the polyurethane polyol prepolymer (A) is a bifunctional polyol compound (a). And a bifunctional isocyanate compound (b), which is a linear polyurethane polyol prepolymer having a weight average molecular weight Mw of 10,000 to 50,000 and a molecular weight dispersity Mz / Mw of 2.5 or less. preferable. By using the polyurethane having such a structure as a resin component for forming the conductive surface layer, the adhesiveness and material strength can be improved.

  As the bifunctional polyol compound (a), polyester polyol, polypropylene glycol, polytetramethylene glycol, polyolefin polyol and the like can be used, and polytetramethylene glycol having strong molecular crystallinity of the polyol itself is preferable. The polyol compound (a) may be used alone or in combination of two or more. The weight average molecular weight (Mw) of the polyol compound (a) is preferably about 500 to 5000 to bring out the effects of the present invention, and more preferably about 500 to 3000. If it is 5000 or less, the proportion of the soft segment in the urethane chain is not too high, and the material strength can be maintained without extremely softening the material, so it can be used as a material for the conductive surface layer of the developer carrier. Can withstand.

  The bifunctional isocyanate compound (b) is not particularly limited, but is preferably an aromatic isocyanate compound, and more preferably a highly crystalline isocyanate compound such as diphenylmethane diisocyanate is used as a material for adhesion and developer. Excellent for preventing fusion. The isocyanate compound (b) may be used alone or in combination of two or more.

  By using as a polyurethane polyol prepolymer (A) a linear polyurethane polyol prepolymer obtained by combining these bifunctional polyol compounds (a) and a bifunctional isocyanate compound (b) and extending the chain, It is possible to bring out flexibility that does not give stress to the developer, and to have crystallinity that prevents the developer from being fused. About the usage-amount of a bifunctional polyol compound (a) and a bifunctional isocyanate compound (b), it uses in the range of 0.7-0.95 by an isocyanate index.

  The weight average molecular weight of the polyurethane polyol prepolymer (A) is preferably in the range of 10,000 to 50,000. If it exceeds 50,000, the crosslink density becomes too low and the residual deformation with respect to stress becomes too large, which may cause image defects such as set marks. On the other hand, if it is less than 10,000, sufficient flexibility that does not give stress to the developer may not be obtained. The weight average molecular weight is preferably 10,000 to 40,000, and more preferably 10,000 to 30,000.

  As the molecular weight dispersity of the polyurethane polyol prepolymer (A), Mw / Mw is preferably 2.5 or less, more preferably 2.0 or less, using Mw: weight average molecular weight, Mz: Z average molecular weight. It is. The Z average molecular weight Mz is the one that places the highest importance on the contribution of the high molecular weight compound to the average molecular weight, and is defined by the following formula (1) when Ni molecules having a molecular weight Mi exist in the polymer. It is.

Mz = (ΣMi ³ Ni) / (ΣMi ² Ni) (1)
If Mz / Mw is greater than 2.5, the molecular weight between crosslinks may vary, which may cause a problem that the change in mechanical properties in the environment increases. By setting Mz / Mw = 2.5 or less, it is possible to obtain an effect of further suppressing changes in mechanical properties in the environment.

  The polyurethane is obtained by polymerizing the polyurethane polyol prepolymer (A) and the isocyanate compound (B). As the isocyanate compound (B), those having an average number of functional groups larger than 2 are suitable. For example, polynuclear compounds such as polymeric MDI, polyfunctional isocyanates having three or more functional groups, blends with diisocyanates, and modified urethanes of diisocyanates. Further, modified products such as allophanate modified products, burette modified products, and nurate modified products can be suitably used. The isocyanate compound (B) may be used alone or in combination of two or more. Moreover, about the usage-amount of a polyurethane polyol prepolymer (A) and an isocyanate compound (B), it is preferable to set so that an isocyanate index (NCO / OH) may become the range of 0.9-1.5. More preferably, it is the range of 1.0-1.2.

  In the developing container provided in the developing device of the present invention, a nonmagnetic one-component developer is disposed as a developer. In the developing device of the present invention, the developer may be provided from the beginning in the developing container, or may be in a state in which the developer can be introduced later and placed in the developing container. As the developer, for example, a developer in which a binder and a colorant are essential components and other components are blended as necessary can be used.

  As the binder contained in the developer, one obtained by polymerizing a polymerizable monomer component can be used. Examples of the polymerizable monomer component include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene; methyl acrylate, ethyl acrylate Acrylic acid such as n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, etc. Esters: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate , Dimethylaminoethyl methacrylate, methacrylic acid esters such as diethylaminoethyl methacrylate; acrylonitrile, methacrylonitrile, and the like monomers acrylamide. The polymerizable monomer component may be composed of a single monomer, or may be a mixture of two or more monomers selected as appropriate.

  As a polymerization initiator used for polymerizing the monomer component, a polymerization initiator having a half-life of 0.5 to 30 hours at a predetermined polymerization reaction temperature is 0 with respect to 100 parts by mass of the polymerizable monomer component. It is preferable to use in an addition amount of 5 to 20 parts by mass. Under such conditions, it is possible to obtain a polymer having a mode distribution with a molecular weight of 10,000 to 100,000, giving desirable strength and suitable melting characteristics as a binder used in a developer. be able to. As the polymerization initiator, an azo or diazo polymerization initiator or a peroxide polymerization initiator is preferably used. The polymerization can be performed by, for example, emulsion polymerization.

  A high molecular weight polymer can also be added to said polymerization system. For example, a polymer having a hydrophilic functional group such as an amino group, a carboxylic acid group, a hydroxyl group, a sulfonic acid group, a glycidyl group, or a nitrile group can be used. That is, when polymerization is carried out by emulsion polymerization, the monomer component containing the hydrophilic functional group as described above cannot be used because it is water-soluble, and the hydrophilic functional group cannot be introduced into the binder. If it is added as a polymer having a group, a hydrophilic functional group can be introduced into the binder. As such a high molecular polymer, a random copolymer of a monomer having a hydrophilic functional group as described above and a vinyl compound such as styrene or ethylene, a block copolymer, a graft copolymer, etc. A copolymer, a polycondensate such as polyester or polyamide, a polyaddition polymer such as polyether or polyimine can be used. In particular, a polyester-based polymer is preferable.

  When the above polymer is used, the number average molecular weight is preferably 5,000 or more. If it is less than 5,000, especially not more than 4,000, the present polymer tends to concentrate near the surface of the developer particles, so that adverse effects on developability, blocking resistance, etc. are likely to occur, which is not preferred.

  As addition amount of these high molecular polymers, 1-20 mass parts is preferable with respect to 100 mass parts of polymerizable monomer components. If the amount is less than 1 part by mass, the effect is small, and if it exceeds 20 parts by mass, it may be difficult to design various physical properties of the developer.

  The glass transition temperature (Tg) of the binder resin is preferably 40 to 70 ° C, and more preferably 45 to 65 ° C. If the glass transition temperature is less than 40 ° C., problems may occur in terms of storage stability and durability stability of the developer, and if it exceeds 70 ° C., the fixing point of the developer may be increased. . In particular, in the case of a color developer for forming a full-color image, the color mixing property at the time of fixing each color developer is lowered and the color reproducibility is poor, so the above range is preferable. The Tg of the binder resin can be estimated by DSC (differential scanning calorimetry). Specifically, after the temperature of the sample is once raised and cooled, from the DSC curve at the time of the second temperature rise, the Tg To do.

  Specifically, an organic pigment or a dye is preferably used as the colorant contained in the developer.

  As the cyan colorant, a copper phthalocyanine compound and a derivative thereof, an anthraquinone compound, a basic dye lake compound, and the like are preferably used.

  As magenta colorants, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are preferably used.

  As yellow colorants, condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are preferably used.

  As the black colorant, carbon black, or one prepared by adjusting the color to black using the yellow / magenta / cyan colorant is preferably used.

  These colorants can be used alone or in combination, and can also be used in a solid solution state. The colorant is appropriately selected and used from the viewpoint of hue angle, saturation, brightness, light resistance, OHP transparency, and dispersibility in developer particles.

  The addition amount of the colorant is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

  The developer can further contain a charge control agent in order to stabilize the charge characteristics. As the charge control agent, a known one can be used, and a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Further, when the developer is produced by a polymerization method described later, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous dispersion medium is particularly preferable.

  The charge control agent is preferably used in an amount of 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin. However, it is not always necessary to include a charge control agent in the developer by positively utilizing frictional charging with the developer layer thickness regulating member or the developer carrier.

  Various fine powders generally known as external additives can be added to the developer. As the external additive, known inorganic fine powders or resin particles are preferably used. In order to improve charging stability, developability, fluidity, and storage stability, inorganic substances such as silica, alumina, titania, or double oxides thereof are used. It is preferably selected from fine powders. In addition, for the purpose of hydrophobization and charge control, silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having functional groups, other organic silicon compounds, organic titanium It can also be treated with a treating agent such as a compound or in combination with various treating agents. As a method for adding the external additive, a conventionally known method such as a Henschel mixer can be used.

  In addition, a mold release agent, a plasticizer, etc. can also be added to a developing agent as needed.

  The developer as described above can be prepared by a known method such as a polymerization method or a pulverization method.

  When preparing a developer by a polymerization method, a polymerizable monomer component and a polymerization initiator which are raw materials of a binder, a colorant, and other necessary components are a homogenizer, a ball mill, a colloid mill, a high-speed stirrer, The mixture is uniformly mixed by a disperser such as an ultrasonic disperser, and suspended in an aqueous medium using a dispersion stabilizer or the like as appropriate. At this time, it is preferable to use a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser at a stretch to obtain a desired developer particle size because the particle diameter of the obtained developer particles becomes sharper. The polymerization initiator may be added at the same time as other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Also, a polymerization initiator dissolved in a polymerizable monomer or solvent can be added immediately after granulation and before starting the polymerization reaction. After granulation, stirring may be performed using a normal stirrer to such an extent that the particle state is maintained and the particles are prevented from floating and settling.

  When the developer is prepared by a polymerization method, a crosslinking agent capable of crosslinking the polymerizable monomer component can also be added. As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used, and an aromatic divinyl compound, a divinyl compound having two double bonds, a compound having three or more vinyl groups alone or Used as a mixture. A preferable addition amount is 0.001 to 15% by mass in 100% by mass of the polymerizable monomer component.

  When a developer is prepared by a polymerization method, it is preferable to add a known surfactant or organic / inorganic dispersant as a dispersion stabilizer. In particular, inorganic dispersants are unlikely to produce harmful ultrafine powders, and because of their steric hindrance, dispersion stability is obtained. Therefore, it can be preferably used. As examples of such inorganic dispersants, polyvalent metal phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate are preferably used.

  These inorganic dispersants are preferably used in an amount of 0.2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer component. Further, although the inorganic dispersant does not easily generate ultrafine particles, it is slightly weak at atomizing the developer, and thus a surfactant can be used in combination. The surfactant is preferably used in an amount of 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the polymerizable monomer component. The inorganic dispersant and the surfactant can be almost completely removed by dissolving with an acid or alkali after completion of the polymerization.

  When preparing a developer by the polymerization method, it is necessary to pay attention to the polymerization inhibitory property and water phase transferability of the colorant, and preferably, surface modification, for example, hydrophobic treatment with a substance that does not inhibit polymerization. It is preferable to give it. In particular, dyes and carbon blacks have many polymerization inhibiting properties, so care must be taken when using them. A preferable method for surface-treating the dye system includes a method in which a part of the polymerizable monomer component is polymerized in the presence of these dyes in advance, and in this case, the obtained colored polymer is used as the remaining polymerizable polymer. Polymerization is carried out by adding to the monomer component. Carbon black can be treated with a substance that reacts with the surface functional group of carbon black, such as polyorganosiloxane, in addition to the same treatment as the above dye.

  In the polymerization step, the polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. When the polymerization is carried out in this temperature range, the release agent or wax to be sealed inside is precipitated by phase separation, and the encapsulation becomes more complete. In order to consume the remaining polymerizable monomer component, the reaction temperature can be increased to 90 to 150 ° C. at the end of the polymerization reaction.

  After completion of the polymerization, a developer can be obtained by filtering, washing and drying by a known method, mixing the inorganic fine powder and adhering it to the surface. Moreover, it is one of the desirable forms of this invention to put a classification process in a manufacturing process and to cut coarse powder and fine powder.

  When a developer is prepared by a pulverization method, a known method is used.For example, a pre-polymerized binder resin and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then heated rolls, While melt-kneaded using a heat kneader such as a kneader or extruder and mixed with each other, the remaining components such as colorants are dispersed or dissolved, cooled and solidified, ground, classified, if necessary Developer particles can be obtained by performing a surface treatment such as a spheroidizing treatment. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

  The pulverization step can be performed by a method using a known pulverizer such as a mechanical impact type or a jet type.

[Various measurement methods]
In the present invention, various characteristics are measured by the following methods.

<Thickness measurement method>
As for the thickness of the conductive surface layer of the developer carrier, the conductive elastic layer and the conductive surface layer are cut out from the developer carrier, and the cross section of the conductive surface layer portion is video micro (magnification 1000 to 2000 times). 9 points were measured and calculated as the average value.

<Surface roughness measurement method>
The surface roughness (Rz) of the developer-carrying member is defined by a value measured according to JIS B-0601 Rzjis, measured at three points divided into four equal parts in the axial direction, and the average value is calculated as the surface roughness. It is a thing.

<Method for measuring molecular weight and molecular weight dispersion>
The molecular weight and molecular weight dispersity are calculated by measurement by gel permeation chromatography (GPC) under the following conditions. Specifically, the column was stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) as a solvent was passed through the column at this temperature at a flow rate of 1 ml / min, and the sample concentration was 0.05 to 0.6% by mass. Inject approximately 50 to 200 μl of the THF sample solution prepared in the above. The molecular weight (Mn, Mw, Mz) of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from a monodisperse polystyrene standard sample and the count number (retention time). Standard polystyrene samples for preparing calibration curves include Tosoh Corporation or Pressure Chemical Co. Number average molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and at least about 10 standard polystyrene samples are used. An RI (refractive index) detector is used as the detector. As the column, a combination of a plurality of commercially available polystyrene gel columns, for example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, 807 (above, trade names) manufactured by Showa Denko, or manufactured by Waters [Mu] -styragel 500, 103, 104, and 105 (product names) are used.

<Volume average particle size measurement>
0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 to 150 ml of an electrolyte solution (about 1% by mass NaCl aqueous solution), and 2 to 20 mg of a measurement sample is added thereto. Disperse the electrolyte in which the sample is suspended with an ultrasonic disperser for 1 to 3 minutes, and use a 100 μm aperture with a Coulter Counter Multisizer (manufactured by Beckman Coulter) to target particles with a particle size of 2 to 40 μm. The particle size distribution on the basis of volume shall be measured.

<Micro compression strength measurement method>
The minute compressive strength (kg / mm ² ) of the developer and the spherical filler constituting the developing device of the present invention is expressed by the following formula.

X = 2.8P / πd ²
(Wherein, P is indicated 10% deformation load (kgf), d represents the toner particle diameter before deformation was measured using an optical microscope (mm))
The fine compressive strength is obtained by, for example, applying a load at a constant increase rate to the toner fixed between the upper pressure indenter and the lower pressure plate by an electromagnetic force or the like, and the toner particle diameter (mm) for each toner particle is The load (kgf) when deformed by 10% can be measured and calculated from the above formula.

  In order to apply the load, for example, a micro-compression tester (manufactured by Shimadzu Corporation, trade name) having a flat plate indenter of 50 μm in diameter at the top and a pressure plate made of SKS (alloy tool steel) at the bottom. MCT type) and a method of applying a load at a load speed of 0.00145 gf / sec for each developer in an atmosphere with a room temperature of 10 to 35 ° C. and a relative humidity of 30 to 80% with no condensation. On the other hand, the particle diameter of the developer can be determined by measuring the particle diameters in the vertical and horizontal directions of the toner using an optical microscope attached to the testing machine and taking the average value. From these measured values, 30 developer particles having a particle diameter of 3 to 10 μm were selected and subjected to the above measurement, and the average value was calculated as the micro compressive strength of the developer.

<Surface micro hardness (MD1) measurement>
The surface microhardness is measured using a micro rubber hardness meter MD-1 type A type (trade name, manufactured by Kobunshi Keiki Co., Ltd.). The distance between the developer carrying member and the measurement terminal is set to 7 to 8 mm, the central part of the developer carrying member, a total of three axial directions 15 mm inside from both ends, and a total of nine points shifted by 120 degrees in the outer circumferential direction. And the average value was defined as the value of the surface microhardness.

  Hereinafter, the present invention will be described more specifically with reference to examples. These examples are examples of the best mode of the present invention, but the present invention is not limited to the examples.

  In the specific examples described below, commercially available high-purity products were used as reagents used in the respective examples unless otherwise specified.

<Examples of developer production>
(Developer Production Example 1)
3 parts by weight of tricalcium phosphate is added to 900 parts by weight of ion-exchanged water heated to 60 ° C., and stirred at 10,000 rpm using a stirrer (trade name: TK type homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.). Then, an aqueous medium was produced.

on the other hand,
Styrene 90 parts by mass n-butyl acrylate 10 parts by mass divinylbenzene 4 parts by mass Ester wax mainly composed of stearyl stearate (maximum endothermic peak 67 ° C. in DSC measurement)
7 parts by mass of saturated polyester resin (polycondensate of propylene oxide-modified bisphenol A and isophthalic acid,
(Tg = 65 ° C., Mn = 17000, Mw / Mn = 2.4)
1 part by mass of aluminum salicylate compound (trade name: Bontron E-88, manufactured by Orient Chemical Co., Ltd.)
Carbon black (specific surface area 60 m ³ / g) A mixture 1-1 consisting of 7 parts by mass was heated to 60 ° C., and then stirred, melted and dispersed at 9,000 rpm using the stirring device.

  Into this, 5 parts by mass of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved at 60 ° C. to prepare a polymerizable monomer composition.

  The polymerizable monomer composition was charged into the aqueous medium, and the mixture was granulated by stirring at 8,000 rpm using the stirring device at 60 ° C. in a nitrogen atmosphere.

  Thereafter, while stirring with a paddle stirring blade, a polymerization reaction was carried out at 60 ° C. for 8 hours to produce polymer particles. After completion of the reaction, the suspension containing the particles was cooled to room temperature (25 ° C.). Hydrochloric acid was added to the cooled suspension to dissolve the calcium phosphate salt, followed by filtration, washing with water and drying, and then colored particles (developer particles 1) were obtained by air classification.

100 parts by mass of the developer particles 1 and 0.7 parts by mass of a hydrophobic silica fine powder having a BET specific surface area of 200 m ² / g and a primary particle size of 12 nm treated with silicone oil were mixed with a Henschel mixer (Mitsui The developer 1 having a volume average particle size of 10.0 μm was obtained by mixing with Miike Chemical Industries Co., Ltd.). The minute compressive strength of Developer 1 was measured and found to be 1.5 kg / mm ² .

(Developer Production Example 2)
Instead of the mixture 1-1 used in Developer Production Example 1,
Styrene 80 parts by mass n-butyl acrylate 20 parts by mass Divinyl benzene 1 part by mass Ester wax mainly composed of stearyl stearate 9 parts by mass (maximum endothermic peak 67 ° C. in DSC measurement)
7 parts by mass of saturated polyester resin (polycondensate of propylene oxide-modified bisphenol A and isophthalic acid,
(Tg = 65 ° C., Mn = 17000, Mw / Mn = 2.4)
1 part by mass of aluminum salicylate compound (trade name: Bontron E-88, manufactured by Orient Chemical Co., Ltd.)
Carbon black (specific surface area 60 m ³ / g) The developer particles 2 were prepared by the same production method as in Developer Production Example 1 except that the mixture 1-2 consisting of 7 parts by mass was used and the air classification conditions were changed. Obtained.

Using this developer particle 2, a developer 2 having a volume average particle diameter of 7.5 μm was obtained in the same manner as in Developer Production Example 1. The minute compressive strength of Developer 2 was measured and found to be 1.0 kg / mm ² .

(Developer Production Example 3)
Similar to Developer Production Example 2 except that the mixture 1-3 used in Developer Production Example 2 was changed to an air classification condition using a mixture 1-3 in which the addition amount of divinylbenzene was changed to 0.2 parts by mass. Thus, developer particles 3 were obtained.

Using this developer particle 3, a developer 3 having a volume average particle size of 6.0 μm was obtained in the same manner as in Developer Production Example 1. The minute compressive strength of Developer 3 was measured and found to be 0.5 kg / mm ² .

(Developer Production Example 4)
Add 12 parts by mass of tricalcium phosphate to 900 parts by mass of ion-exchanged water heated to 60 ° C., and stir at 10,000 rpm using a stirrer (trade name: TK type homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.). Then, an aqueous medium was produced.
Instead of the mixture 1-1 used in Developer Production Example 1,
Styrene 70 parts by mass n-butyl acrylate 30 parts by mass Ester wax mainly composed of stearyl stearate 9 parts by mass (maximum endothermic peak 67 ° C. in DSC measurement)
3 parts by mass of saturated polyester resin (polycondensate of propylene oxide-modified bisphenol A and isophthalic acid,
(Tg = 65 ° C., Mn = 17000, Mw / Mn = 2.4)
1 part by mass of aluminum salicylate compound (trade name: Bontron E-88, manufactured by Orient Chemical Co., Ltd.)
Carbon black (specific surface area 60 m ³ / g) The developer particles 4 were prepared in the same manner as in Developer Production Example 1 except that the mixture 1-4 consisting of 7 parts by mass was used and the air classification conditions were changed. Obtained.

Using this developer particle 4, a developer 4 having a volume average particle size of 3.0 μm was obtained in the same manner as in Developer Production Example 1. The micro compressive strength of this developer 4 was measured and found to be 0.1 kg / mm ² .

<Example of developer carrier production>
(Developer carrier production example 1)
As the shaft core body, a SUM metal core (outer diameter: 8 mm) was subjected to nickel plating, and an outer peripheral surface was coated with an adhesive (silane coupling agent) and baked. This shaft core was placed in a mold, and liquid silicone rubber 1 (made by Toray Dow Corning Silicone) was injected into a cavity formed in the mold. Subsequently, the mold was heated, and the injected silicone rubber 1 was heated at 150 ° C. for 30 minutes to be cured. After cooling and demolding, a heat treatment was further performed at 200 ° C. for 4 hours to provide a conductive elastic layer having a thickness of 4 mm as a main component of silicone rubber on the outer peripheral surface of the shaft core. . At this time, the hardness (Asker C) of the conductive elastic layer was 40 °.

next,
82 parts by mass of polyurethane polyol prepolymer (trade name: Takelac TE5060; manufactured by Mitsui Takeda Chemical Co., Ltd.,
Weight average molecular weight Mw = 20000)
63 parts by mass of isocyanate compound (trade name: Coronate 2521; manufactured by Nippon Polyurethane Co., Ltd.)
20 parts by mass of carbon black (trade name: MA100; manufactured by Mitsubishi Chemical Corporation, pH 3.5)
10 parts by weight of spherical filler (trade name: CFB100; manufactured by Dai Nippon Ink Co., Ltd.)
MEK was added to the mixture 2-1, and the mixture was dispersed with a sand mill for 1 hour. After dispersion, MEK was further added to adjust the solid content in the range of 20% by mass to 30% by mass (so that the film thickness was 20 μm) to obtain a raw material liquid for the conductive surface layer.

  The shaft core after the formation of the conductive elastic layer was immersed in the raw material liquid for the conductive surface layer to coat the outer surface of the conductive elastic layer, and then pulled up and dried naturally. Next, the raw material of the coated conductive surface layer is cured by heat treatment at 140 ° C. for 60 minutes, the conductive surface layer is laminated on the outer peripheral surface of the conductive elastic layer, and the thickness is 20 μm. A conductive surface layer having an average surface roughness (Rz) of 7.2 μm with an average of 9 points was formed, and a developer carrying member 1 was obtained.

  The developer carrying body 1 thus obtained had a surface microhardness of 43 °.

(Developer carrier production example 2)
First,
100 parts by mass of polytetramethylene glycol (trade name: PTG1000SN; manufactured by Hodogaya Chemical Co., Ltd.,
f = 2 (f represents the number of functional groups))
Difunctional isocyanate compound 19 parts by mass (trade name: Millionate MT; MDI; manufactured by Nippon Polyurethane Industry Co., Ltd., f = 2)
Are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 6 hours under a nitrogen atmosphere to give a weight average molecular weight Mw = 10000, a hydroxyl value of 18.2, and a molecular weight dispersity Mz / Mw = 2.2. A functional polyurethane polyol prepolymer A was obtained.

Instead of the mixture 2-1 used in Developer Carrier Production Example 1,
Polyurethane polyol prepolymer A 100 parts by mass isocyanate compound 33 parts by mass (trade name: Coronate 2521; manufactured by Nippon Polyurethane Co., Ltd.)
20 parts by mass of carbon black (trade name: MA100; manufactured by Mitsubishi Chemical Corporation, pH 3.5)
10 parts by weight of spherical filler (trade name: CFB100; manufactured by Dai Nippon Ink Co., Ltd.)
A conductive surface layer having a thickness of 20 μm and an average surface roughness (Rz) of 7.8 μm was obtained by the same production method as in Developer Carrier Production Example 1 except that the mixture 2-2 comprising A developer carrying member 2 was obtained.

  The developer carrying member 2 thus obtained had a surface microhardness of 38 °.

(Developer carrier production example 3)
A conductive elastic layer having a thickness of 5 mm was formed in the same manner as in Developer Carrier Production Example 1. Further, the conductive elastic layer was polished to form a conductive elastic layer having a thickness of 4 mm.

Also, instead of the mixture 2-1 used in Developer Carrier Production Example 1,
100 parts by mass of polyurethane polyol prepolymer A (synthesized by the method described in Example 2)
Isocyanate 33 parts by mass (trade name: Coronate 2521; manufactured by Nippon Polyurethane Co., Ltd.)
20 parts by mass of carbon black (trade name: MA100; manufactured by Mitsubishi Chemical Corporation, pH 3.5)
Using the mixture 2-3 consisting of the above, the developer is supported except that the solid content is adjusted in the range of 10% by mass to 20% by mass (so that the film thickness is 10 μm) and the raw material liquid for the conductive surface layer is used. The developer carrying body 3 having a conductive surface layer having a thickness of 10 μm and an average surface roughness (Rz) of 8.2 μm with a thickness of 10 μm was obtained by the same production method as the body production example 1.

  The developer carrier 3 thus obtained had a surface microhardness of 30 °.

(Developer carrier production example 4)
The conductive elastic layer was formed and polished by the same method as in Developer Carrier Production Example 3 to obtain a conductive elastic layer. Furthermore, the raw material for the conductive surface layer was prepared by using the mixture 2-3 used in Developer Carrier Production Example 3 and adjusting the solid content in the range of 5% by mass to 20% by mass (so that the film thickness was 2 μm). A developer carrier 4 having a conductive surface layer having a thickness of 2 μm and a 9-point average surface roughness (Rz) of 8.5 μm by the same production method as in Developer Carrier Production Example 1 except that the liquid is used. Got.

  The developer carrier 4 thus obtained had a surface microhardness of 20 °.

(Developer carrier production example 5)
The conductive elastic layer was formed and polished by the same method as in Developer Carrier Production Example 3 to obtain a conductive elastic layer. Furthermore, the raw material of the conductive surface layer was prepared by using the mixture 2-3 used in Developer Carrier Production Example 3 and adjusting the solid content in the range of 10% by mass to 20% by mass (so that the film thickness was 18 μm). A developer carrier 5 having a conductive surface layer having a thickness of 18 μm and a nine-point average surface roughness (Rz) of 7.6 μm, by the same production method as in Developer carrier production example 1 except that the liquid is used. Got.

  The developer carrier 5 thus obtained had a surface microhardness of 35 °.

<Examples , reference examples and comparative examples>
(Outer diameter difference selection of developer carrier)
The outer diameter of the developer carrier formed in Developer Carrier Production Examples 1 to 5 is measured in the axial direction at five points (5 points that divide the axial direction into six equal parts), and the difference between the maximum and the minimum is 50 to 60 μm. Some were selected and used for evaluation.

(Evaluation)
As Examples 1 to 3, Reference Examples 1 to 2 and Comparative Examples 1 to 3, the developers described in Table 1 and developer carriers are combined and incorporated into a developing apparatus having the configuration of FIG. 2, and the configuration of FIG. In the image forming apparatus having the above, continuous image formation with a printing rate of 2% was performed, and the following items were evaluated after printing 30000 sheets. Table 1 shows the evaluation results.

<Image lateral density unevenness>
A solid image was formed after printing 30000 sheets. For the obtained solid image, measure 6 points for each image using a Macbeth densitometer (6 points measurement is on a line at the center of the image that divides the image into two equal parts in the image forming direction, and is divided into seven equal parts in the horizontal direction of the image) And the concentration difference (MAX / MIN) was calculated and evaluated as follows.
A: The density difference in the horizontal direction of the image is 0.05 or less, and there is no problem on the image. Thing x: The difference in density in the horizontal direction of the image exceeds 0.1 and there is a problem on the image

It is a figure which shows the structure of the developing roller which the developing device of this invention comprises. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a developing device of the present invention. It is a figure which shows the relationship between the micro compressive strength of a developer, and the surface micro hardness of a developer carrier.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Developing apparatus 3 Image forming apparatus 11 Core metal 12 Conductive elastic layer 13 Conductive surface layer 21 Photosensitive drum 22 Charging roller 23 Laser beam 25 Developing roller 26 Developer supply roller 27 Developer regulating member 28 Developer ( toner)
29 Transfer roller 30 Cleaning blade 31 Waste toner container 32 Fixing device 33 Paper 34 Developer container

Claims (3)

A developer carrier, a non-magnetic one-component developer, a developing container in which the non-magnetic one-component developer is disposed, and a developer regulating member,
In the developing device configured such that a thin layer of the non-magnetic one-component developer is formed on the surface of the developer carrying member by the developer regulating member.
Micro compression strength of the non-magnetic one-component developing agent is 0.5 ~1.0kg / mm ^2,
The developer carrier has at least a shaft, a conductive elastic layer provided around the shaft, and a conductive surface layer provided on the conductive elastic layer,
The conductive surface layer contains a polyurethane obtained by polymerizing the polyurethane polyol prepolymer (A) and the isocyanate compound (B),
The polyurethane polyol prepolymer (A) is a chain extension of a bifunctional polyol compound (a) and a difunctional isocyanate compound (b) diphenylmethane diisocyanate, and has a weight average molecular weight Mw of 10,000 to 50,000 and a molecular weight. A linear polyurethane polyol prepolymer having a dispersity Mz / Mw of 2.5 or less, and
A developing device having a surface microhardness (MD1) of 35 to 38 ° of the developer carrying member . The developing device according to claim 1, wherein the bifunctional polyol compound (a) is polytetramethylene glycol . A developing device according to claim 1 or 2,
An electrophotographic apparatus comprising: a latent image carrier disposed in pressure contact with a developer carrier in the developing device.

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