The mechanism of color penetration is not only related to the characteristics of pigment itself, such as molecular weight and water effect, but also related to the characteristics of film.
The diffusion and permeation of pigment on the film is affected by the polarity, crystallinity, density and molecular arrangement of polymer molecules. It depends on the size of the pores formed between the polymers when the polymer chain in the film moves in thermal motion, and the expansion of the pores when the temperature increases. Diffusion infiltration mainly occurs in the amorphous region. When the temperature is low, the pigment is not easy to pass through the film. This is because at low temperature, the energy of pigment molecules is low, it is not easy to overcome the intermolecular force, and the motion range of polymer chain segment is small, which is not enough to generate the large pores required for pigment molecules to pass through. For films with high crystallinity and stretching orientation, such as pet, BOPP, HDPE, etc., due to the high regularity of molecular arrangement, even at higher temperatures, the total creep and creep rate are still low, and the movement of molecular segments is difficult. Therefore, it is difficult for such films to have pigment color penetration. But for nylon, non-linear polyethylene and other types of film, due to its amorphous state, low degree of crystallization, large molecular gap, color penetration occurs easily at higher temperature, especially nylon has the disadvantages of low thermal deformation temperature, unstable size, large water absorption, easy degradation in hot water, so the cooking bag and boiling bag made of nylon film are easy to seep Through some colors. However, in dry state, the penetration of these pigments on nylon film is weakened because the double influence of moisture on nylon film and pigment is eliminated.
The color penetration of binder in the ink layer is not very strong, because pigment molecules can overcome the internal intermolecular force movement, and generally can overcome the force between pigment molecules and resin molecules in binder, and break through the "encirclement" of binder and migrate. However, the polarity of resin molecules in binder has an effect on the movement and migration of pigment molecules. The stronger the polarity is, the more difficult the migration is. For example, the migration of pigments such as blue lotus and peach red in offset printing ink made of rosin resin is lower than that in ordinary gravure composite ink (chlorinated polypropylene type), which is the reason.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
We uphold the integrity of cooperation, good quality, good service business philosophy, won the industry's approval, products sold to all over the world; welcome friends from all walks of life to inquire, visit our factory to investigate guidance and business negotiations.