JP2006039031A - Elastic member for electrophotography, manufacturing method thereof, electrophotographic device, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastic member for electrophotography which has the electrostatic capacity and the electric resistance most suitably controlled by preventing diffusion of isocyanate due to an organic solvent or to heating and by centralizing an isocyanate treatment layer near a surface, and also to provide a manufacturing method thereof, and a process cartridge and an electrophotographic device provided with the elastic member. <P>SOLUTION: In the elastic member for electrophotography has a support material an elastic layer provided on the support material, the elastic layer is impregnated with a solventless isocyanate compound from a surface thereof, and then the isocyanate compound is reformed by hardening the compound in a temperature environment of a setting point of the isocyanate compound or lower. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic elastic member having one or more elastic layers on a support and a method for producing the same. The present invention also relates to a process cartridge and an electrophotographic apparatus having a charging unit including the elastic member as a charging member.

  In an image forming apparatus employing an electrophotographic system, that is, an electrophotographic apparatus, a conductive member is used for various purposes, for example, a member such as a charging member, a developing member, and a transfer member.

  Examples of the shape of the conductive member arranged in contact with or close to the electrophotographic photosensitive member include a roller shape, a blade shape, a brush shape, a belt shape, a film shape, a sheet shape, and a chip shape. (That is, a charging roller, a developing roller, a transfer roller, etc.) are often used.

  As the conductive member used for such an application, a member having a multilayer structure has been used in order to adjust the electric resistance value and prevent the image carrier from being contaminated. As a result, the manufacturing process becomes complicated and the cost of the members is high.

  On the other hand, as in Patent Document 1 and Patent Document 2, a roller made of conductive polyurethane is immersed or brought into contact with a solution containing polyisocyanate, and is then heat-cured and surface-treated. A roller has been proposed. Moreover, the conductive roller which immerses and heats an isocyanate containing compound in the conductive roller which has an elastic layer which has epichlorohydrin rubber as a main body like patent document 3 is proposed.

  These rollers are described as being capable of avoiding contamination due to exudates on the image carrier by a simple surface treatment method. However, by diluting the isocyanate compound with an organic solvent, there is a problem that the treatment liquid is easily diffused into the roller, the treatment thickness is increased, and the treatment density of the treatment layer is diluted. Moreover, the diffusion of the isocyanate compound is promoted by the heat treatment, resulting in problems such as an increase in the treatment thickness and bleeding on the roller surface.

When the treatment thickness is increased, there is a drawback that it is difficult to ensure the electrical capacitance required for the charging roller or the like. Further, the low processing density of the processing layer has a drawback that the high surface resistance necessary for the charging roller or the like cannot be ensured.
Japanese Patent No. 3072799, page 2, paragraph number [0005] Japanese Patent No. 3133468, page 2, paragraph number [0005] Japanese Patent Laid-Open No. 10-45935, page 2, paragraph numbers [0009] and [0017]

  The object of the present invention is to eliminate the above-mentioned problems, prevent diffusion of isocyanate due to organic solvents and heating, concentrate the isocyanate-treated layer near the surface, and optimally control the capacitance and electrical resistance. It is an object to provide an elastic member for photography, a manufacturing method thereof, a process cartridge and an electrophotographic apparatus including the elastic member.

  As a result of intensive investigations, the present inventors have found that the above problem is a method for modifying the elastic layer by impregnating the elastic layer with a solvent-free liquid isocyanate compound, and then quickly immobilizing the isocyanate compound. It was clarified that the problem can be solved by curing in a temperature environment below the freezing point temperature.

  That is, the present invention impregnates an elastic layer with a solvent-free isocyanate compound (hereinafter referred to as “isocyanate compound stock solution”) at a set time and temperature to form a high-density treatment layer and control its thickness. Then, after washing and removing the isocyanate remaining on the elastic layer surface as necessary, the isocyanate compound is quickly cured under a temperature environment below the freezing point temperature of the isocyanate compound to prevent diffusion of the impregnated isocyanate. The inventors have found that the object of the present invention can be achieved by curing, and have achieved the present invention.

  According to one aspect of the present invention, there is provided an electrophotographic elastic member having a support and an elastic layer provided on the support, wherein the elastic layer contains a solvent-free isocyanate compound. An electrophotographic elastic member, which is modified by impregnating from the surface of the resin, and then curing the isocyanate compound at a temperature not higher than the freezing point temperature of the isocyanate compound, and a process comprising the electrophotographic elastic member A cartridge and an electrophotographic apparatus are provided.

According to another aspect of the present invention, there is provided a method for producing an electrophotographic elastic member comprising a support and a modified elastic layer on the support,
As a modification step of the elastic layer,
(I) a step of impregnating a solventless isocyanate compound from the surface of the elastic layer on the support; and (ii) a step of curing the isocyanate compound in the elastic layer in a temperature environment below its freezing point temperature; A method for producing an elastic member for electrophotography is provided.

  According to the present invention, an elastic member subjected to a surface treatment with a high impregnation density can be produced. Thereby, an elastic member for electrophotography in which the capacitance and electric resistance are optimally controlled can be provided, and a process cartridge and an electrophotographic apparatus having the members can be provided.

  The electrophotographic elastic member according to the present invention is used in contact with an image carrier, and is used as a member of various uses of an electrophotographic apparatus, for example, a charging member, a developing member, a transfer member and the like. Yes. Hereinafter, the charging roller will be described as an example.

  As an example of use, the charging roller is placed in contact with the image carrier and connected to a power source to apply a bias to the roller shaft to charge the image carrier to a desired potential.

  In this charging roller, a polymer elastic body elastic layer is formed concentrically around the core metal, and the surface of the elastic body layer is surface-treated.

  Hereinafter, an example in which the elastic layer is polyurethane will be described.

  The elastic polymer elastic layer is composed of at least one polyol selected from polyether polyol and polyester polyol, a chain extender, a crosslinking agent, an isocyanate, a catalyst, an auxiliary agent commonly used in the production of polyisocyanate and polyurethane, and the like. It is obtained by mixing and stirring a compound that imparts conductivity and injecting it into a mold. Polyether polyol and polyester polyol may be used in combination.

  The polyether polyol or polyester polyol may be any as long as it can prepare a polyurethane elastic body that forms the elastic layer of the charging roller. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polypropylene glycol-ethylene glycol, and polyalkylene glycols known as blends thereof, polytetramethylene glycol, copolymer polyols of tetrahydrofuran and alkylene oxide, and various kinds thereof. Examples thereof include modified products and blends thereof.

  Examples of the polyester polyol include condensed polyester polyols, lactone polyester polyols, polycarbonate polyols or blends thereof obtained by condensation of dicarboxylic acids such as adipic acid and polyols such as ethylene glycol.

  The polyisocyanate may be any one as long as it is commonly used in preparing polyurethane elastic bodies.

  Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  As the compound imparting electrical conductivity, an alkali metal salt, lithium perchlorate, or the like can be used.

  After sufficiently mixing these compounds with a mixing device, an elastic layer can be formed on the surface of the core metal by using a known molding method. For example, in the present invention, the elastic layer can be formed by employing a known one-shot method or prepolymer method.

  From the surface of the elastic body formed on the surface of the metal core, an isocyanate stock solution is impregnated into the elastic body. It is known that an isocyanate group is rich in reactivity, and forms a urethane bond or an allophanate bond in the active hydrogen of a hydroxyl group or a urethane group. It is also known that it reacts with moisture present in the atmosphere to form urea bonds and burette bonds (the reaction is further accelerated by heating, but after impregnating the desired amount, the elastic body It is preferable to quickly wash and remove the isocyanate remaining on the roller surface with the poor solvent). The present invention does not adversely affect the function of the photoreceptor used in electrophotography while changing the elastic body of the elastic body containing these reaction products derived from isocyanate groups and adding a new function. It was completed based on the finding. The isocyanate is a compound having a plurality of isocyanate groups at the terminal or side chain, and any compound can be used as long as it can be impregnated into the elastic layer without using a solvent. It is preferable to change the state from solid to liquid / liquid to solid. Specific examples thereof include diphenylmethane diisocyanate and polyisocyanate of tolylene diisocyanate, but are not limited thereto. Moreover, you may use what mixed these 2 or more types.

  The surface treatment of the urethane elastic body is performed by bringing the surface of the elastic layer into contact with an isocyanate compound stock solution and then washing and removing the isocyanate compound remaining on the surface with a solvent. This is performed by curing the isocyanate compound impregnated in the elastic layer under a temperature environment. Specifically, examples of the method of impregnating the elastic body by bringing it into contact with an isocyanate compound stock solution include dipping, spray coating, and roll coating. The elastic layer may be exposed to the vapor of the isocyanate compound. In either case, it is more effective if placed in a pressurized environment during impregnation. In the case where the isocyanate compound remains on the surface of the elastic layer, the solvent for washing / removing the remaining isocyanate compound may be a good solvent that dissolves the isocyanate such as toluene, but is washed with a poor solvent for the isocyanate compound. It is preferable. Due to the poor solvent, the isocyanate compound is dispersed as colloidal fine particles and removed from the surface of the elastic layer, and the isocyanate compound impregnated in the elastic body is not diluted or extracted by the washing, and the surface of the elastic layer High-density processing is possible.

  As another method for impregnating the elastic layer with isocyanate, a method in which a powder of an isocyanate compound is applied to the surface of the elastic layer, and then the powder is dissolved and impregnated can be mentioned. As the powder of the isocyanate compound, for example, a pulverized solid of 4,4′-diphenylmethane diisocyanate can be used. Such powder can be impregnated by covering the surface of the elastic layer and heating and dissolving the powder with warm air, infrared rays or the like. By adjusting the amount of powder coating, it is possible to omit the step of washing and removing the excess isocyanate compound on the surface of the elastic layer.

  As a method for fixing and curing the impregnated isocyanate compound in the elastic layer, the isocyanate compound is cured with moisture in the atmosphere under a temperature environment below the freezing point of the isocyanate compound. For example, when 4,4'-diphenylmethane diisocyanate is used as the isocyanate compound, its freezing point is about 38 ° C, and it becomes a solid at lower temperatures. In addition, after the isocyanate compound reacts with moisture in the environment and changes to a urea derivative or the like, it does not dissolve even when reheated, and the particulate isocyanate compound derivative is fixed in the elastic layer. .

  It is preferable that the surface treatment is performed up to about 1 mm from the surface of the elastic layer to about 10 μm to 0.5 mm.

  Deeper than the transition region in the storage elastic modulus curve obtained by measuring the storage elastic modulus near the surface of the surface-treated elastic layer obtained in this way substantially continuously using a nanoindenter. The difference between the storage elastic modulus in the region where the storage elastic modulus was almost constant and the storage elastic modulus of the untreated elastic layer was the largest. Immediately cooled to the freezing point temperature of the isocyanate (Example 6 in FIG. 2). What is impregnated with a solvent-diluted isocyanate compound, or is obtained by curing the impregnated isocyanate compound at a temperature higher than the freezing point of the isocyanate compound, from the transition region in the storage elastic modulus curve in the nanoindenter However, the value of the storage elastic modulus in the region where the storage elastic modulus is almost constant is small from the value of the storage elastic modulus of the untreated elastic layer, and the curing density in the elastic layer is low ( In FIG. 2, Comparative Example 1).

  On the other hand, when the cut surface of the elastic layer according to the present invention is observed with a video micro, the impregnated portion appears white. When further expanded, the impregnated isocyanate is scattered in granular form, and the particle size and density of the dispersion change depending on the ratio of the hard segment and the soft segment of the urethane elastic substrate, the impregnation time and temperature, It was found that the particle size and dispersion density can be controlled by setting the conditions. Specifically, according to the present invention, the liquid isocyanate compound impregnated in the elastic layer is aggregated and dispersed spherically in the elastic layer. The portion close to the surface of the elastic layer has a large amount of impregnation and is dispersed as large particles. On the other hand, in the deep part far from the surface, the amount of impregnation is small and the particles are dispersed as small particles. The isocyanate agglomerates crystallize due to curing of the isocyanate compound in a temperature environment below the freezing point temperature of the impregnated isocyanate compound, react with moisture in the environment, change to a urea derivative, etc., and dissolve even when reheated. No longer.

  In the case of immersing the elastic body in the solvent-free isocyanate stock solution, more specific treatment conditions will be described. The temperature of the stock solution is preferably from 100 ° C. to the melting point temperature of the isocyanate to be used, particularly 40 ° C. to 90 ° C. It is preferable to set it to ° C. The immersion time depends on the type of isocyanate, but is within 1 minute, preferably within 30 seconds, and more preferably from 1 second to 10 seconds. If the time is out of the range, the surface treatment layer expands and is likely to be deformed, and no excellent effect is obtained.

  In the above description, the main constituent material of the elastic layer has been described by taking polyurethane as an example. However, other acrylonitrile butadiene rubber (NBR), hydrogenated NBR (H-NBR), NBR copolymerized with a third component such as isoprene, Alkyl ethers such as modified NBR introduced with a functional group such as a carboxyl group, nitrile rubber such as NBR having a butadiene moiety internally cross-linked, ethylene oxide-propylene oxide copolymer, ethylene oxide-propylene oxide-allyl glycidyl ether copolymer Polymer, epichlorohydrin rubber (CO), epichlorohydrin-ethylene oxide copolymer rubber (ECO), epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, etc., hydrin rubber, urethane rubber, chloroprene rubber, chloros Hong polyethylene rubber. Among these, hydrin rubbers such as CO and ECO, nitrile rubbers such as NBR and H-NBR, ethylene oxide-propylene oxide copolymers, ethylene oxide-propylene oxide-allyl glycidyl ether, in terms of low electrical resistance of the polar polymer itself. Alkyl ether polymers such as copolymers, NR (IR) (isoprene rubber), BR (butadiene rubber), SBR (styrene butadiene rubber), EPDM (ethylene propylene diene terpolymer), IIR (butyl rubber), olefin elastomer, SEBS A system elastomer, a polystyrene system elastomer, etc. are used suitably.

The electrophotographic elastic member according to the present invention is 1 × 10 ² Ω to 1 × 10 ⁷ Ω before the surface treatment, and 1 × 10 ⁵ Ω to 1 × 10 ¹⁰ Ω after the surface treatment. Such a resistance range allows a good image to be obtained without causing problems such as uneven image density and fog when the electrophotographic elastic member according to the present invention is used for a charging roller. . Moreover, it is preferable to adjust the surface average roughness of an elastic body layer to 10 micrometers or less. If it is this range, if it is a charging roller, when the electrophotographic elastic member which concerns on this invention is used for a charging roller, favorable charge can be made, for example. The charging roller thus obtained charges the surface of the photoconductor, for example, by contacting the surface of the photoconductor. Examples of the photoreceptor include various types of photoreceptors known per se, and an organic photoreceptor is particularly preferable.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
NCO% of 5.5% from polytetramethylene glycol (manufactured by Hodogaya Chemical Co., Ltd., PTG2000) and 4,4′-diphenylmethane diisocyanate (trade name: Millionate MT, manufactured by Nippon Polyurethane) A prepolymer was produced. 88 parts by mass of polytetramethylene glycol having a number average molecular weight of 2000 (manufactured by Hodogaya Chemical Co., Ltd., PTG2000), 12 parts by mass of a mixture of 1,4-butanediol and trimethylolpropane (mass ratio 65:35), Urethane catalyst {Potassium acetate (made by Nippon Emulsifier Co., Ltd., trade name: P15) is used in an amount of 500 ppm of the entire urethane cured product; The amount which becomes 2000ppm of the whole. }, A lithium perchlorate complex compound (complex compound with a mass ratio of 3: 7 of LiClO ₄ and CH ₃ CH ₂ OCH ₂ CH ₂ OH) was added and mixed and dispersed so as to be 6.6% of the whole. The cross-linking agent was mixed so that the molar ratio of hydroxyl group / isocyanate group was 0.95, and this mixture was put into a mold preheated to 130 ° C. where a shaft (φ: 6 mm, l: 255 mm) was previously arranged. Injected and heated at 130 ° C. for 10 minutes to obtain a 8.5 mm roll having a conductive polyurethane elastic layer formed on the shaft surface excluding both ends. The hardness of this roll was 68 ° (JIS A). Yes, the roll resistance value measured by applying a voltage of 200 V in a 15 ° C./10% RH environment was 9 × 10 ⁵ Ω.

<Surface treatment>
This roller was immersed in 4,4′-diphenylmethane diisocyanate (trade name: Millionate MT, manufactured by Nippon Polyurethane Co., Ltd., freezing point temperature of about 38 ° C.) for 20 seconds, pulled up, and 4,4′-diphenylmethane diisocyanate remaining on the surface. Was removed by wiping with a sponge soaked with Actorel 1140L (exxon), which is a poor solvent. Thereafter, it was quickly cooled to 25 ° C. and left in an environment of 32.5 ° C./80% RH for 2 days. The resistance of the obtained surface treatment roller was 2.3 × 10 ⁶ Ω under an environment of 15 ° C./10% RH. Dielectric constant (dielectric constant measuring device: manufactured by Toyo Technica Co., Ltd. was measured by placing a roller parallel to a horizontally installed φ30 mm aluminum tube and loading both ends with 500 g each.) Same environment, 3 V, 0.01 Hz When measured, | ε | was 2 × 10 ⁻⁶ .

  Nano indenter (MTS nano indenter. Measurement conditions: DCM head, test mode is CSM option + viscoelastic option, terminal is Berkovic diamond indenter, measurement position is 10 points at 100μm interval, measurement parameters The surface application sensitivity is 3%, the strain rate is 0.05, the Poisson's ratio is 0.25, the indentation depth is 10,000 nm, the vibration frequency is 75 Hz, and the sampling rate is 5 times / second. When the elastic modulus was measured in the above-described manner, an elastic modulus lowering curve was obtained from the surface toward the center as shown in FIG. The storage elastic modulus of the treated layer read from the curve is an area where the storage elastic modulus is deeper than the transition region and the storage elastic modulus is almost constant, and the average value at a distance of 1500 nm to 2000 nm from the surface is 21.2 Mpa. The storage elastic modulus of the treated elastic layer was 2.2 times. there were. As a comparative control, the storage elastic modulus of the base layer not subjected to the surface treatment under the same conditions was 9.7 Mpa. Moreover, the processing thickness measured by Video Micro (Keyence Corporation, 2000 times) was 170 μm. Further, it was observed that the particle size was about 3 μm near the surface and the particle size decreased toward the inside.

<Evaluation of charging uniformity when only DC voltage is applied to the charging roller>
The charging roller was attached to the electrophotographic apparatus having the configuration shown in FIG. 3, and a halftone image was output in an environment of a temperature of 15 ° C./humidity of 10% RH. The electrophotographic apparatus used in this embodiment has a process speed of 94 mm / s and 30 mm / s. At this time, the surface potential V _D of the electrophotographic photosensitive member 1 was adjusted to an applied voltage in each environment so that the surface potential V _D was −600 V, and an image was output. The image level rank was 2.

  The results are shown in Table 1.

  As for the image level in the table, rank 1 is very good, rank 2 is good, rank 3 has a slight streak and spot image defect, and rank 4 has a streak and spot image defect. Is the level.

(Comparative Example 1)
In the surface treatment of Example 1, this roller was immersed in 4,4′-diphenylmethane diisocyanate at 80 ° C. for 20 seconds, but 4,4′-diphenylmethane diisocyanate / toluene at 80 ° C. = 10% by mass / 90% by mass. The toluene solution was wiped with a sponge, dried by air drying, and allowed to stand in an environment of 32.5 ° C./80% RH for 2 days. Others were performed in the same manner.

The resistance of the obtained surface treatment roller was 1.1 × 10 ⁶ Ω. The dielectric constant was 4 × ^{10 -7.} The processing thickness measured by Video Micro (Keyence Corporation, 2000 times) was 85 μm. Moreover, it was observed that the particle size was about 2 μm near the surface and the particle size decreased toward the inside.

  When the elastic modulus was measured with a nanoindenter, an elastic modulus decreasing curve was obtained from the surface toward the center as shown in FIG. The storage elastic modulus of the treated layer read from the curve was 12.6 Mpa at an average value of the distance from the surface of 1500 nm to 2000 nm, which was 1.3 times that of the base layer. The image level rank was 4.

(Example 2)
In the surface treatment of Example 1, the roller was exposed to 4,4′-diphenylmethane diisocyanate vapor at 130 ° C. for 20 seconds, then not washed, immediately cooled to 25 ° C., and 32.5 ° C./80% It was left for 2 days in an RH environment. Others were performed in the same manner.

Resistance of the resulting surface-treated roller was 1 × 10 ⁶ Ω. The dielectric constant was 8 × 10 ⁻⁶ . The processing thickness measured by Video Micro (Keyence Corporation, 2000 times) was 130 μm. Moreover, it was observed that the particle size was about 2 μm near the surface and the particle size decreased toward the inside. The storage elastic modulus of the treated layer read from the curve was 2.3 times that of the base layer at an average value of a distance of 1500 nm to 2000 nm from the surface at 22.7 MPa. The image level was 1.

(Example 3)
In the surface treatment of Example 1, the roller was immersed in 4,4′-diphenylmethane diisocyanate at 80 ° C. for 2 seconds in a pressure vessel pressurized to 0.2 MPa, pulled up, and left on the surface. '-Diphenylmethane diisocyanate was wiped off with a sponge soaked with toluene as a good solvent, dried with toluene, quickly cooled to 25 ° C., and allowed to stand in an environment of 32.5 ° C./80% RH for 2 days. Others were performed in the same manner.

The resistance of the obtained surface treatment roller was 7 × 10 ⁶ Ω. The dielectric constant was 1 × ^{10 -5.} The treatment thickness measured by Video Micro (Keyence Corporation, 2000 times) was 260 μm. Moreover, it was observed that the particle size was about 5 μm near the surface and the particle size decreased toward the inside. The storage elastic modulus of the treated layer read from the curve was 2.5 times the base layer at 24.6 MPa with an average value of the distance from the surface of 1500 nm to 2000 nm. The image level was 1.

Example 4
The surface treatment of Example 1 was carried out in the same manner except that 4,4′-diphenylmethane diisocyanate remaining on the surface was wiped off with a sponge soaked with toluene as a good solvent. Resistance of the resulting surface-treated roller was 1.3 × 10 ⁶ Ω. The dielectric constant was 1 × 10 ⁻⁶ . The processing thickness measured by Video Micro (Keyence Corporation, 2000 times) was 100 μm. Further, it was observed that the particle size was about 3 μm near the surface and the particle size decreased toward the inside.

  The storage elastic modulus of the treated layer read from the curve was 18.2 Mpa at an average value of a distance of 1500 nm to 2000 nm from the surface, which was 1.9 times that of the base layer. The image level was 1.

(Example 5)
75 parts by mass of epichlorohydrin rubber (trade name: Epichromer CG-102; manufactured by Daiso), 25 parts by mass of NBR rubber (trade name: N230S; manufactured by JSR), 1 part by mass of zinc stearate, 5 parts by mass of zinc oxide , 30 parts by weight of calcium carbonate, 5 parts by weight of MT carbon, 1 part by weight of M (vulcanization accelerator), 1 part by weight of DM (vulcanization accelerator), 1 PMC (sulfur, manufactured by Tsurumi Chemical Co., Ltd.) .2 parts by mass of material was kneaded to obtain a roller having an elastic layer formed on the surface excluding both ends of the shaft (φ: 6 mm, L: 255 mm). The roller hardness is 50 ° (JIS A), the roller resistance value was 4 × 10 ⁸ Ω.

  This roller was immersed in 4,4′-diphenylmethane diisocyanate (trade name: Millionate MT, manufactured by Nippon Polyurethane Co., Ltd.) at 80 ° C. for 20 seconds, pulled up, and 4,4′-diphenylmethane diisocyanate remaining on the surface was removed with a poor solvent. A certain Actrel 1140L was wiped off with a sponge soaked and removed. Thereafter, toluene was quickly dried, cooled to 25 ° C., and allowed to stand for 2 days in an environment of 32.5 ° C./80% RH.

The resistance of the obtained surface treatment roller was 2.4 × 10 ⁷ Ω. The dielectric constant was 2 × 10 ⁻⁶ . The processing thickness measured by Video Micro (Keyence Corporation, 2000 times) was 90 μm. Further, it was observed that the particle size was about 3 μm near the surface and the particle size decreased toward the inside. The storage elastic modulus of the treated layer read from the curve was 1.9 times the 7.9 MPa of the base layer at 14.6 Mpa at an average value of the distance from the surface of 1500 nm to 2000 nm. The image level was 1.

(Example 6)
In the surface treatment of Example 1, this roller was immersed in 4,4′-diphenylmethane diisocyanate at 80 ° C. for 20 seconds, pulled up, and 4,4′-diphenylmethane diisocyanate remaining on the surface was replaced with 1140 L of Actrel 1 which is a poor solvent. Instead of immersing in 50 ° C. solution for 10 seconds and washing / removing, 500 mg of 4,4′-diphenylmethane diisocyanate powder at 25 ° C. was applied, then heated in an 80 ° C. atmosphere and allowed to stand for 5 minutes for impregnation. After that, without washing, it was quickly cooled to 25 ° C. and left for 2 days in an environment of 32.5 ° C./80% RH. Others were performed in the same manner.

The resistance of the obtained surface treatment roller was 7.3 × 10 ⁶ Ω. The dielectric constant was 8 × 10 ⁻⁶ . The processing thickness measured by Video Micro (Keyence Corporation, 2000 times) was 230 μm. Moreover, it was observed that the particle size was about 5 μm near the surface and the particle size decreased toward the inside. The storage elastic modulus of the treated layer read from the curve was 2.7 times that of the base layer at 26.4 MPa with an average value of the distance from the surface of 1500 nm to 2000 nm. The image level was 1.

It is a schematic sectional drawing which shows an example of the elastic member of this invention. It is the depth of a nano indenter of an elastic member obtained in an example, and a storage elastic modulus curve. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention.

Explanation of symbols

1 Electrophotographic photoreceptor 2 Charging member (charging roller)
2a Support (conductive support)
2b Elastic layer 2c Resistance layer 2d Surface layer 2e Second resistance layer 3 Exposure means 4 Development means 4a Toner carrier 4b Stirring member 4c Toner magnetic member 5 Transfer means 6 Cleaning means L Laser light S1, S2, S3 Bias application power source P Transfer material

Claims (14)

  An electrophotographic elastic member having a support and an elastic layer provided on the support, wherein the elastic layer is impregnated with a solvent-free isocyanate compound from the surface of the elastic layer. An elastic member for electrophotography, which is then modified by curing the isocyanate compound in a temperature environment below the freezing point temperature of the isocyanate compound.   In a region where the storage elastic modulus of the elastic layer is continuously lower from the surface toward the center and deeper than the transition region of the storage elastic modulus of the elastic layer, the storage elastic modulus is substantially constant. The elastic member for electrophotography according to claim 1, wherein the storage elastic modulus is 1.5 times or more the storage elastic modulus of the elastic layer before modification.   The elastic member for electrophotography according to claim 1 or 2, wherein the elastic layer includes particles made of a cured product of the isocyanate compound, and the particle diameter of the particles decreases from the surface to the inside of the elastic layer.   The electrophotographic elastic member according to claim 1, wherein the elastic layer contains polyurethane. The electrophotographic elastic member according to claim 1, wherein the elastic layer has an electric resistance value of 1 × 10 ⁵ Ω to 1 × 10 ¹⁰ Ω. The electrophotographic elastic member according to claim 1, wherein a dielectric constant | ε | of the elastic layer is 1 × 10 ⁻⁵ to 1 × 10 ⁻⁷ .   The electrophotographic elastic member according to claim 1, wherein the electrophotographic elastic member is a charging roller.   A process cartridge comprising the electrophotographic elastic member according to claim 1.   An electrophotographic apparatus comprising the electrophotographic elastic member according to claim 1. A method for producing an electrophotographic elastic member comprising a support and a modified elastic layer on the support,
As a modification step of the elastic layer,
(I) a step of impregnating a solventless isocyanate compound from the surface of the elastic layer on the support; and (ii) a step of curing the isocyanate compound in the elastic layer in a temperature environment below its freezing point temperature; A method for producing an elastic member for electrophotography, comprising:   The method for producing an electrophotographic elastic member according to claim 10, wherein the step (i) includes a step of impregnating the elastic layer with the isocyanate compound under pressure.   The method for producing an elastic member for electrophotography according to claim 10 or 11, wherein the step (i) includes a step of exposing the elastic layer to the vapor of the isocyanate compound.   The method for producing an elastic member for electrophotography according to claim 10, wherein the step (i) includes a step of melting the powder of the isocyanate compound after the powder of the isocyanate compound is coated on the surface of the elastic layer.   Before the step (ii), the step (iii) of washing and removing the isocyanate compound remaining on the surface of the elastic layer obtained by the step (i) using a poor solvent for the isocyanate is included. The manufacturing method of the elastic member for electrophotography in any one of Claims 10-13.

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