Plastic noctilucent refers to a plastic additive which can be absorbed by sunlight or other light after being added to plastic, store light energy and automatically emit light in the dark.
At present, there are two main types of plastic luminous agents: one is metal sulfide, which is the first plastic luminous agent to be applied, generally called the first generation plastic luminous agent; The other is rare earth. Metal sulfides can be divided into two types: one is transition metal sulfide system, such as ZnS and CdS; The other is alkaline earth metal sulfide system, such as MgS and CaS.
SrS and so on. The luminous substance of transition metal sulfide system ZnS:Cu has been gradually improved. After adding activators such as Co and Tm, the luminous time can be extended from 200min to about 500min, but its biggest disadvantage is that it is not resistant to ultraviolet rays, and it will gradually decay and turn black under ultraviolet irradiation. Alkaline earth metal sulfide systems mainly include CaS, (Ca, Sr)S and (Ca, Mg).
In S, (Sr, Mg)S and SrS systems, the activators are mostly rare earth ions such as Bi3+ or Eu2+, such as red luminous substance CaS:Eu2+. The initial brightness of (Mg, Sr)S:Eu+ is the best, and the luminescence time is similar to that of CaS:Eu2+. The biggest advantage of this system is bright color and fast absorption rate in weak light.
Rare earth luminous agents mainly include rare earth aluminates, rare earth silicates and rare earth oxides, which are the second generation luminous agents. Rare earth aluminate luminous agents have the advantages of stable luminous performance, high luminous efficiency, long luminous time, no radioactive damage,
Rich in resources and good in comprehensive performance, it has been widely used in the field of plastic processing. Rare earth aluminate luminous agents mainly include
SrAlzO:Eu2+, Dy3+ and La120:: Eu2+, Dy3+ such as CaAlz0:, SrAlOzs, SrAl0 and BaAlz0 excited by Eu2+are typical luminous substances, and SrAl20 is the basic substance of its composition, referred to as matrix for short.
Eu2+ is an activating ion (activator), and Dys+ is a co-activating ion (sensitizer). It is difficult to emit luminous light without adding excitation substance into plastic luminous agent, and the addition of auxiliary excitation substance can improve the quality of luminous light, that is, it can improve the intensity of luminous light and prolong the time of automatic luminous light.