Usage and dosage of fluorescent whitening agent for plastics
1. Usage and precautions
The general usage of fluorescent brightener for plastics is to add it to the powder, pellets or flakes of the resin together with other plastic additives, mix well and then plasticize and shape. It should be noted that there is no whitening effect before plasticization and the mixture presents the original color of the whitening agent.
(1)According to the type of plastic and the specific requirements of customers, choose the right fluorescent brightener or fluorescent whitening agents(FWA).
(2) To be accurately measured, not gross estimates.
(3)In the case of using recycled plastic materials, the recycled materials should be basically white, not too dark gray tones, otherwise they cannot be whitened and can only be grayed. This is the result of the "brightening" of the optical brightener.
(4) Pay attention to taboo requirements to avoid application accidents.
(5)"The hue of the optical brightener" refers to the hue of the product after application, not the hue (appearance) of the fluorescent brightener itself.
(6)In the case of using color paste, the optical brightener should be added to the "color paste" in advance for ease of use, and attention should be paid to understanding the market.
2. General dosage
(1)In plastics, the dosage of optical brightener is 0.01-0.05% of the resin in most cases. For PVC products with more calcium powder, the situation is special. Some factories use about 0.1%, which is only a special case.
(2) In the masterbatch, the general dosage of optical brightener is 0.5-1.0%. The color of the masterbatch is the color of the brightener itself.
(3)In the color paste, the dosage of optical brightener should be determined according to the amount of color paste of the downstream product. Make sure that the fluorescent brightener introduced after using the color paste does not exceed 0.05% of the resin.
(4)The dosage of optical brightener in inks and coatings is similar to that in plastics.
No matter where optical brightener is used, the amount of brightener is not as large as possible. After using too much waste (not white), the whiteness problem can not be solved by adding more whitening agents. The whitening agent cannot "resurrect the dead".