What issues should be noted when applying plastic luminous agents?

Plastic luminous agents can be used for both thermoplastic and thermosetting plastics. However, to fully leverage their effectiveness, they are more effective in manufacturing light-colored or transparent luminous plastic products. The luminous plastics produced from the widely used rare earth aluminate-based plastic luminous agents at present have relatively good comprehensive performance. In order to produce luminous plastics that satisfy customers, the following issues should be noted during the use of plastic luminous agents.
① The uniformity of dispersion of plastic luminous agents and their influence on the physical and mechanical properties of plastics. The widely used plastic luminous agents nowadays are inorganic substances, while plastics are organic polymer materials. Inorganic substances have poor compatibility with organic polymer materials, and it is difficult for powdered plastic luminous agents to be evenly dispersed in them. Another issue is the poor compatibility between inorganic molecules and organic polymer material molecules, which leads to a small interaction force between them and thus affects the physical and mechanical properties of plastics. To address the issue of poor dispersibility and compatibility between plastic luminous agents and organic polymer materials, dispersants are added during the mixing process to improve the dispersibility of plastic luminous agents, and coupling agents are added to enhance the interaction between plastic luminous agents and plastic molecules.
② The problem of blackening of rare earth aluminate products after contact with metals. During the manufacturing process of luminous plastic products, regardless of the addition method used, attention should be paid to the plastic luminous agent. Especially for rare earth aluminate-based plastic luminous agents, friction with the metal parts of the equipment can lead to a decline in luminous performance. In severe cases, it may cause the plastic parts to turn black and other phenomena. For instance, after rare earth aluminate-based plastic luminous agents are added to plastics and processed by plastic machinery, their luminous effect drops significantly. Some products even turn black and lose their luminous performance. During the preparation of luminous plastics, there are mainly two measures to prevent the blackening of luminous plastics: On the one hand, the plastic luminous agents can be coated, that is, they can be coated with other substances. Form a coating film on the plastic luminous agent particles
Then it is added to the plastic raw materials; On the other hand, it is necessary to minimize the friction between the plastic luminous agent and the mechanical surface as much as possible. For instance, adding external lubricants to the plastic raw materials can largely prevent the deterioration of the plastic luminous agent’s performance. The main substances currently used for coating plastic luminous powder include stearic acid, silane coupling agent, dimethyl silicone oil, silica and organic polymer materials, etc. They respectively have the functions of lubricating coupling and preventing the contact and friction between the luminous agent and the metal, thereby enhancing the luminescence effect of the plastic luminous agent.
The usage amount of luminous agent is generally 10% to 20%. Generally, the greater the amount of luminous agent used, the brighter and more lasting the light will be. However, the increase in the luminescent effect is much smaller than that of the proportion of luminous powder, and the difference in afterglow time is also not significant. This is mainly because in a matrix with a high content of luminescent powder, each particle of the luminescent powder cannot act as an effective light-emitting body. Some of the luminescent powder particles will be blocked by the surrounding luminescent powder particles and cannot effectively absorb and emit light. Therefore, it can be concluded that an excessive amount of luminescent powder added to the product is of little significance for plastic products with a certain thickness.
For the same type of luminous powder, the larger the particle size, the better the luminous performance of the luminous powder. This is because the larger the particle size and the more complete the grains, the brighter the light can be emitted after the excitation stops, providing more space for the movement of electrons and holes, accumulating more energy after excitation, and the afterglow time is longer. When preparing luminescent plastics, the particle size range of the material should be selected based on the process conditions. When adding pigments (dyes) for coloring, be cautious in your selection to avoid reducing the luminous intensity.