Reason 1: The material used in the protective film is not up to standard in terms of cleanliness, perhaps because it is polluted by dust.
Reason two: In the selection of raw materials, there is no suitable choice. Perhaps the compatibility between several raw materials is not good, and then crystal spots occur.
Reason three: In the processing of the protective film, the processing temperature is not well controlled, and then the material is not plasticized, or it is over-plasticized, and then crystal spots occur.
Reason 4: There is a problem in the processing equipment, the equipment itself has quality problems, perhaps the equipment's processing ability is not good, etc.