The nature and processing characteristics of plastics have their own characteristics, which makes the application of fluorescent brighteners in plastics very different from their applications in textile printing and dyeing.
The nature and processing characteristics of plastics have their own characteristics, which makes the application of fluorescent brighteners in plastics very different from their applications in textile printing and dyeing.
The way in which the fluorescent whitening agent is added directly affects its state of existence in the plastic, and the presence state directly affects the use effect of the fluorescent whitening agent. There are three main methods for adding fluorescent whitening agents in plastics: ① direct participation method, that is, to directly process the fluorescent whitening agent with resin and other additives after high-speed mixing; ② pre-dispersion method, that is, pre-dispersing the fluorescent whitening agent in Plasticizer or other additives are used in the form of plasticizer dispersion. This is the case for whitening of soft PVC; ③ masterbatch method, the fluorescent whitening agent is made into concentrated masterbatch and then processed with resin . This method is conducive to the dispersion of low concentration optical brighteners in plastics. In fiber whitening, the fluorescent whitening agent must be formulated into a solution or dispersion and used by dip dyeing. Fluorescent whitening agent molecules are diffused, adsorbed and fixed on the fiber in an ideal single-molecule dispersed state. The method of using the fluorescent whitening agent for plastics is different from that in the fiber. Its dispersion state has its own characteristics.
The amount of fluorescent whitening agent added to the plastic varies according to the substrate. Generally speaking, for colored substrates, the amount of addition is between 0.01% and 0.15%; for transparent products, the amount of addition The amount is between 0.0001%-0.001%. Each fluorescent whitening agent has a saturation concentration in the plastic. Above this saturation value, not only the whitening agent effect will increase but the matrix yellowing phenomenon will appear. This limit is called the fluorescent whitening agent in a matrix. Yellow spots.
