Application of Fluorescent Whitening Agents in Plastic Products

Fluorescent whiteners are colorless organic compounds that absorb near ultraviolet light (wavelength range 300-400 nm) invisible to the naked eye and emit blue-purple fluorescence (wavelength range 420-480 nm) visible to the naked eye. Fluorescent whiteners are widely used in textile, paper, plastic and synthetic detergent industries because of their remarkable improvement in whiteness and gloss. Fluorescent whiteners can also be considered a white dye, or a white fluorescent dye, which uses fluorescence to give the visual organs a sense of whiteness.

Generally speaking, there are three ways to use fluorescent whitening agents in plastic guessing: dry whitening, wet whitening and color masterbatch whitening. Next, the small edition of the specific for us to introduce the following three different processes, as well as the trial terminal products.

Many plastic terminal manufacturers do not know how to use fluorescent whiteners correctly. Today, we are looking at the common methods of using fluorescent whiteners in plastic guessing, and how to choose the best method according to the function of the product.

1. Plastic dry whitening is to add a certain amount of fluorescent whitening agent dry powder directly to the plastic substrate before plasticizing, mix with the plastic substrate first, and when the extruder reaches the melting temperature of plastics, extrude the mixture into the screw to melt, so that fluorescent whitening agent evenly distributes in the melt, and finally granulate or restrict the molding. Dry whitening agents are mainly used for injection molding of rigid polyethylene, polyethylene, polypropylene, ABS and other thermoplastic resins. Fluorescent brighteners used as dry whiteners are relatively cheap, but they have the disadvantages of large dust dispersibility and environmental pollution.

2. In order to improve the dispersing effect of wet whitening, some adhesives should be added to the fluorescent whitening agent to make the fluorescent whitening agent adhere to the material surface better, so as to reduce the dust flying and pollution. The fluorescent whitening agent can also be dispersed in the auxiliaries solution and participated in batches in the form of auxiliaries. For example, it can be used in flexible polyethylene (PVC) and mixed into 10% dioctyl phthalate plasticizer solution, then participated in batches. In wet whitening fluorescent whitening agent is a fine loose slurry, because there are non-gray organic solvents mixed into the plasticizer, so there is a defect of viscosity. This method is mainly used for soft vinyl polymerization and whitening.

3. Now the use of plastic masterbatch has become an important method of plastic coloring. When using color masterbatch, as long as the color masterbatch and resin are mixed evenly according to the proportion, it can be directly used for plastic molding. A small amount of mixing only by hand, in the case of a large amount of processing, in order to ensure the dispersity of masterbatch, can use mechanical mixing. Color masterbatch and resin plastic mechanical mixing can be sent to the injection molding machine with pre-molding device, while pre-molding side color.