An image forming apparatus comprising: a latent electrostatic image bearing member; a charging unit configured to uniformly charge a surface of the image bearing member; an exposing unit configured to form a latent electrostatic image on the surface of the charged image bearing member; a developing unit configured to develop the latent electrostatic image formed on the surface of the image bearing member by supplying a toner to form a visible image; a transferring unit configured to transfer the visible image formed on the surface of the image bearing member to a recording medium; a fixing unit configured to fix the visible image on the recording medium by application of at least one of heat and pressure; a cleaning unit configured to clean a residual toner on the image bearing member; and a toner replenishing device configured to replenish the toner to the developing unit, wherein the toner is replenished by the toner replenishing device comprising a pump configured to supply the toner and a toner container arranged in conjunction with the pump, and wherein the toner comprises a binder resin, a colorant and a releasing agent and has a dynamic friction coefficient of 0.15 to 0.35.

The object is to provide a toner which can be smoothly replrenished by a toner replenishing device using a powder pump even when the toner containes a releasing agent, and an image forming apparatus using the toner. There is provided a toner, which comprises a binder resin, a colorant and a releasing agent, has a dynamic friction coefficient of 0.15 to 0.35, and is replenished by the toner replenishing device having a powder pump configured to automatically supply the toner and a toner container arranged in conjuction with the powder pump so as to develop a latent electrostatic image on a image bearing member.

The present invention provides a dry two-component type developer for electrophotography comprising a carrier particle and a toner particle, wherein a toner water adsorption ratio (T) obtained by a following equation (1) for the toner particle ranges from 1.0 to 7.0 and a carrier water adsorption ratio (C) obtained by a following equation (2) is 20. 0 or less, and a water adsorption ratio (T/C) expressed in a following equation (3) representing a relationship between the toner water adsorption ratio (T) and the carrier water adsorption ratio (C) is 5.0 or less;$$\begin{gathered} \begin{array}{c}\text{a toner water adsorption ratio (T) =} \\ \text{[a water adsorption amount (T}{\text{}}_{\text{H}}\text{)} \\ \text{of the toner particle /} \\ \text{an N}{\text{}}_{\text{2}}\text{adsorption amount (T}{\text{}}_{\text{N}}\text{)} \\ \text{of the toner particle]}\end{array} \end{gathered}$$$$\begin{gathered} \begin{array}{c}\text{a carrier water adsorption ratio (C) =} \\ \text{[a water adsorption amount (C}{\text{}}_{\text{H}}\text{)} \\ \text{of the carrier particle /} \\ \text{an N}{\text{}}_{\text{2}}\text{adsorption amount} \\ \text{(C}{\text{}}_{\text{N}}\text{) of the carrier particle]}\end{array} \end{gathered}$$ and$$\begin{gathered} \begin{array}{c}\text{a water adsorption ratio (T/C) =} \\ \text{[a toner water adsorption ratio (T) /} \\ \text{a carrier water adsorption} \\ \text{ratio (C)]}\end{array} \end{gathered}$$

In the dry two-component type developer for electrophotography according to the present invention, even if use conditions are changed, a developing characteristic is less varied.