JP2008191463A5 - - Google Patents

Claims (6)

A carrier having a carrier core containing a magnetic material and a resin coating layer on the surface of the carrier core,
The 10-point deviation of the specific resistance of the carrier at 5000 V / cm is within 0.5 digits,
The number-based circle equivalent diameter 50% value in the range of the circle equivalent diameter of 0.5 to 200.0 μm of the carrier is 15 to 70 μm, and the circularity in the range of the circle equivalent diameter of 0.5 to 200.0 μm is 0. The average circularity at 200 to 1.000 is 0.960 or more,
A carrier characterized in that the ratio of particles having a circularity of 0.200 to 0.925 within a circle equivalent diameter of 15.0 to 100.0 μm is 15.0% by number or less. The carrier according to claim 1, wherein the true specific gravity of the carrier is 2.5 to 4.2 g / cm ³ . The carrier according to claim 1 or 2, wherein a specific resistance of the carrier core at 500 V / cm is 1.0 x 10 ^{6 to} 1.0 x 10 ⁸ Ω · cm. A carrier manufacturing method according to any one of claims 1 to 3 ,
Using carrier core particles having a number-based circle equivalent diameter 50% value of 15 to 70 μm and an apparent density of 1.5 g / cm ³ or more and 2.2 g / cm ³ or less ,
The carrier core particles and / or a gas for fluidizing the carrier particles are introduced from the bottom of the processing container in which a screen having rotating blades is disposed, and the carrier core particles in the processing container and / or Alternatively, the carrier particles rise in the space between the inner wall of the processing container and the screen, and form a fluidized bed that circulates in the downward direction inside the screen,
Crushing and dispersing the carrier core particles and / or agglomeration of carrier particles descending along the interior of the screen by rotating blades inside the screen as it passes through the screen ;
A coating step of spraying a resin solution containing a resin and a solvent onto carrier core particles and / or carrier particles that have passed through the screen ;
After the coating of the resin solution onto the carrier core particles in the coating step, the step of cooling the temperature of the carrier to a temperature not higher than Tg of the resin ,
In the coating step, when the boiling point of the main solvent of the resin solution is T ° C , the carrier is coated under the condition that the supply air temperature is T ° C-60 ° C to T ° C-20 ° C. The method for manufacturing a carrier according to claim 4, wherein the diameter of the screen is 0.5 to 2.0 mm. After the coating step, the product temperature of the carrier particles is cured at a temperature of Tg to Tg + 30 ° C. of the resin while flowing, rolling, or vibrating, and the product temperature of the carrier particles is equal to or lower than the Tg of the resin. method for producing a carrier according to claim 4 or 5, characterized by comprising the step of cooling to a temperature.