Method of drying honeycomb formed body

1. A method of drying a plurality of unfired honeycomb formed bodies each comprising a raw material composition containing a ceramic material, a dispersion medium, an auxiliary forming agent, and an addition agent, and each having a plurality of cells partitioned by partition walls, the cells serving as fluid through channels, the method comprising the steps of

causing a current to flow, in a dry space, between opposing electrode plates that are provided at an upper side of an opening top end surface and at a lower side of an opening bottom end surface of each honeycomb formed body, to perform dielectric drying while maintaining throughout the entire duration of dielectric drying a power density with respect to each honeycomb formed body to be in a range of 5 to 20 [kW/kg (water)], and

performing at least one of microwave drying and hot-air drying after performing the dielectric drying,

wherein current is caused to flow between the opposing electrode plates until a predetermined level of water content factor of each honeycomb body is reached,

wherein a water content factor of each honeycomb formed body before dielectric drying is 20 to 25% by mass,

wherein the dielectric drying is performed until a water content factor of each honeycomb formed body after the dielectric drying becomes 10 to 40% with respect to the water content factor before the dielectric drying, and

wherein the method maintains the power density in the dry space to be in the range of 5 to 20 [kW/kg (water)] by reducing a filling factor of the honeycomb formed bodies in the dry space to no more than 60%.

2. The method of drying the plurality of honeycomb formed bodies according to claim 1 , wherein the method maintains the power density in the dry space to be in the range of 5 to 20 [kW/kg (water)] by suppressing an area of the opposing electrode plates to be a minimum size effective for drying.

3. The method of drying the plurality of honeycomb formed bodies according to claim 1 , wherein a binder having thermal gelation property and/or thermosetting property is included in the raw material composition as the auxiliary forming agent.

4. The method of drying the plurality of honeycomb formed bodies according to claim 3 , wherein a content of the binder in the raw material composition is 1 to 10% by mass by mass.

5. The method of drying the plurality of honeycomb formed bodies according to claim 1 , wherein the method performs the dielectric drying while maintaining a wet-bulb temperature in the dry space to be not less than 60° C. and less than 100° C.

6. The method of drying the plurality of honeycomb formed bodies according to claim 1 , wherein opening ratios of the plurality of cells of each honeycomb formed body are 70 to 90%, and thicknesses of the partition walls are 0.05 to 0.2 mm.

7. The method of drying the plurality of honeycomb formed bodies according to claim 1 , further comprising the step of arranging the honeycomb formed bodies on carriers, and spacing the carriers from one another to achieve a filling factor of no more than 60%.