Why toner powder get negative charge?

Toner powder acquires a negative charge primarily through the process of triboelectric charging, which occurs when the toner particles are rubbed against other materials during manufacturing. This process causes electrons to transfer from one material to another, resulting in the toner particles gaining a negative charge. The negative charge is essential for the electrostatic attraction between the toner and the positively charged areas of the paper during the printing process, ensuring that the toner adheres properly to create the desired image.