Nozzle protective cap, head unit, and method of attaching nozzle protective cap

A method of attaching a nozzle protective cap to a head unit so that the nozzle protective cap is attachable and detachable with respect to the head unit,

• the nozzle protective cap being configured to be attached and detached with respect to the head unit, and the nozzle protective cap including:
• a base part having a facing surface configured to face a nozzle surface of a recording head including a nozzle array configured to eject liquid droplets;
• a seal member positioned in the facing surface and including an elastic member configured to press the nozzle surface in a state that the seal member surrounds the nozzle array;
• a first engaging part configured to press the seal member against the nozzle surface and to engage with the recording head so that the nozzle protective cap and the recording head are integrated;
• and a second engaging part configured to press the seal member against the nozzle surface and to engage with the recording head to an extent stronger than the first engaging part engages with the recording head so that the nozzle protective cap and the recording head are integrated, and
• the head unit including the recording head having the nozzle surface, a nozzle guide having a contact surface configured to contact the facing surface of the nozzle protective cap and surrounding the nozzle surface of the recording head, and a first engagement receiving part configured to engage with the first engaging part,
• the method comprising:
• holding the first engaging part and the first engagement receiving part by a force of 40N or more so that the first engaging part and the first engagement receiving part are attracted to each other.