Ink jet method and ink jet apparatus

An ink jet apparatus comprising:

• an ink jet head that discharges a radiation-curable ink jet composition;
• and
• a radiation source that emits radiation to the discharged radiation-curable ink jet composition, wherein
• the ink jet head includes a first nozzle group including a plurality of nozzles in a column direction and a second nozzle group including a plurality of nozzles in the column direction, and the first nozzle group and the second nozzle group are arranged at different positions from each other in the column direction and in a scanning direction intersecting the column direction,
• the radiation source is disposed at a side of the ink jet head opposite to the scanning direction when the ink jet head is scanned in the scanning direction,
• the discharged radiation-curable ink jet composition contains a monofunctional monomer including a nitrogen-containing monofunctional monomer, an amount of the monofunctional monomer being 80 mass % of more relative to a total amount of the radiation-curable ink jet composition, and
• an amount of the nitrogen-containing monofunctional monomer is from 5 to 20 mass % relative to the total amount of the radiation-curable ink jet composition.

An ink jet head used to discharge a radiation-curable ink jet composition, the ink jet head comprising:

• a first nozzle group including a plurality of nozzles in a column direction;
• and a second nozzle group including a plurality of nozzles in the column direction, the first nozzle group and the second nozzle group being arranged at different positions from each other in the column direction and in a scanning direction intersecting the column direction, wherein
• the radiation-curable ink jet composition to be discharged contains a monofunctional monomer including a nitrogen-containing monofunctional monomer, an amount of the monofunctional monomer being 80 mass % or more relative to a total amount of the radiation-curable ink jet composition, and
• an amount of the nitrogen-containing monofunctional monomer is from 5 to 20 mass % relative to the total amount of the radiation-curable ink jet composition.

A set comprising a radiation-curable ink jet composition and an ink jet head, wherein

• the ink jet head is used to discharge the radiation-curable ink jet composition,
• the ink jet head includes a first nozzle group including a plurality of nozzles in a column direction and a second nozzle group including a plurality of nozzles in the column direction, and the first nozzle group and the second nozzle group are arranged at different positions from each other in the column direction and in a scanning direction intersecting the column direction,
• the radiation-curable ink jet composition contains a monofunctional monomer including a nitrogen-containing monofunctional monomer, an amount of the monofunctional monomer being 80 mass % or more relative to a total amount of the radiation-curable ink jet composition, and
• an amount of the nitrogen-containing monofunctional monomer is from 5 to 20 mass % relative to the total amount of the radiation-curable ink jet composition.