The writing principle of the ball-point pen is mainly to use the ball to directly contact the paper surface to generate friction when writing, so that the ball rolls in the ball seat and brings out the ink or ink in the pen core to achieve the purpose of writing.

A ballpoint pen is a pen that uses ink and different pigments to write. The nib is a small steel ball. The small steel ball is embedded in a small cylindrical copper bowl, and then connected to a plastic tube containing ink. The ink flows down from the surroundings as the steel ball rotates.

The pigment of ballpoint pen ink is dye. The ink colors are mainly blue, red and black, among which blue ink is used most. In the past, the pigment components in blue ink were salt-based royal blue and salt-based green lotus, and the solvent was oxidized castor oil and ricinoleic acid. Because the basic dyes are not light fast (light fastness is only level 1-2), are not heat resistant, and are not resistant to acids and alkalis, they have poor durability and have been eliminated.