| 摘要 |
PROBLEM TO BE SOLVED: To provide a development device in which it is possible to reduce the occurrence of fogging in a low temperature environment, and an electrophotographic image formation device with which it is possible to stably form an image over a long period of time.SOLUTION: Toner satisfies the following conditions: 40≤Z(25)≤80 and 10≤Z(50)≤55 (where Z(Y) represents the percentile of (X3(Y)-X4(Y)) relative to X3(Y) at Y°C, X3(Y) represents the displacement amount obtained after displacement amount (X2(Y)) is left to stand for 0.1 seconds, X2(Y) represents the displacement amount when a 2.94×10-4 N load is applied at 9.8×10-5 N/sec, and X4(Y) represents the displacement amount at 0 N when the load is reduced by 9.8×10-5 N/sec); 0.49×10-3≤R(25)≤1.70×10-3 (where R(25) represents the tilt from the starting point to the maximum load at 25°C); and 15°C≤(P1-TgA)≤70°C (where TgA represents a glass transition temperature between 40 and 60°C, and P1 represents the maximum heat absorption peak temperature between 70 and 110°C). A development roller has a surface layer containing urethane resin. |
