Abstract: A developing roller, including: a shaft containing a metal; an elastic layer on a circumference of the shaft; and a surface layer on a circumferential surface of the elastic layer, wherein the surface layer contains: a polyurethane which is a reaction product between a fluoroethylene vinyl ether copolymer and an isocyanurate form of an isocyanate; and particles having an average primary particle diameter of 5 nm to 30 nm, and wherein the polyurethane has a peak intensity ratio of a NCO group to a hydroxyl group of 5.6 to 8.8 in an infrared absorption spectrum obtained by an attenuated total reflection method.

Abstract: A developing roller to bear toner thereon is provided. The developing roller includes a cylindrical electroconductive substrate; an electroconductive elastic layer located on a peripheral surface of the cylindrical electroconductive substrate; and a toner bearing layer located on a peripheral surface of the electroconductive elastic layer. The toner bearing layer includes a polyurethane resin, which is a reaction product of at least an isocyanate compound having an isocyanurate structure and a polyol at a NCO/OH molar ratio of from 90 to 110. The toner bearing layer has a water contact angle of from 135° to 155°, and a static friction coefficient of from 0.10 to 0.15.

Abstract: An image developer, including a developer container containing a developer developing a latent image on a latent image bearer; a developer bearer bearing the developer, located close to or contacting the latent image bearer; and a developer feeding and collection roller feeding the developer onto the developer bearer and scraping the developer therefrom, rotating while contacting thereto with pressure, wherein the developer feeding and collection roller includes an inner layer formed of an electroconductive foamed rubber; and an outer layer formed of an insulative foamed rubber, and wherein the following relationship is satisfied: ??T wherein ? represents a compression amount of the pressure of the developer feeding and collection roller to the developer bearer; and T represents a thickness of the outer layer, and wherein an offset voltage having a polarity opposite to that of the charged developer is applied to the developer feeding and collection roller.

Abstract: A developing roller including: a core metal; and an elastic layer formed on an outer circumference of the core metal, wherein an outermost surface of the developing roller is roughened, and wherein a difference between a maximum value and a minimum value of indentation power is 10% to 21%, wherein the indentation power is measured by a micro-indentation test at 120 locations with 3 degrees apart on a circumference of the developing roller, which is at a center of the developing roller with respect to a longitudinal direction.

Abstract: A developing roller including: an electrically-conductive base; an elastic layer formed on an outer circumference of the electrically-conductive base; and a toner bearing layer formed on the elastic layer, wherein the toner bearing layer contains a polyurethane resin having an isocyanurate structure, and wherein the polyurethane resin has a ratio A/B of 1.0 to 10.0 where A denotes absorbance attributed to C?O of cyanurate and B denotes absorbance attributed to C?O of urethane in an infrared absorption spectrum of the polyurethane resin obtained by an ATR method.

Abstract: An image developer, including a developer container containing a developer developing a latent image on a latent image bearer; a developer bearer bearing the developer, located close to or contacting the latent image bearer; and a developer feeding and collection roller feeding the developer onto the developer bearer and scraping the developer therefrom, rotating while contacting thereto with pressure, wherein the developer feeding and collection roller includes an inner layer formed of an electroconductive foamed rubber; and an outer layer formed of an insulative foamed rubber, and wherein the following relationship is satisfied: ??T wherein ? represents a compression amount of the pressure of the developer feeding and collection roller to the developer bearer; and T represents a thickness of the outer layer, and wherein an offset voltage having a polarity opposite to that of the charged developer is applied to the developer feeding and collection roller.