PE protective film is a typical crystalline polymer. In order to improve its transparency, first of all, it is necessary to add a nucleating agent to the particles. The nucleating agent is used in the processing and molding process of the crystalline polymer. It can replace the crystal nucleus and make the polymer molecules grow into crystals on the nucleating agent. Because the nucleating agent is added, the number of crystal nuclei available for crystallization at the melting point of the PE protective film and PP protective film melt is greatly increased.
When the PE protective film is in production, it is necessary to pay attention to the acceleration of the crystallization speed and the miniaturization of crystal particles, so that the crystal does not affect the transparency of the film, so as to improve the crystallinity of the PE protective film and the PP film and increase the strength of the film. It can also improve transparency.
Nucleating agents are divided into organic nucleating agents and inorganic nucleating agents. Organic nucleating agents include benzoic acid and sodium benzoate, and inorganic nucleating agents include talc and sodium carbonate. In terms of the actual addition amount, it actually means sodium benzoate 0.25PHR, benzoic acid 0.4PHR, Na2CO30.2PHR, and talc 0.05PHR. For example, it is necessary to pay attention to adding 0.3-0.7% calcium stearate nucleating agent in HDPE, which will increase the transparency of HDPE film from 67% to 73.5%.
In order to improve the transparency of PE protective film, it is necessary to add 0.5-1% homogeneous oil in the particles. This homogeneous oil can be the same as PVC, PE, PP, PU, PC, PS, HIPS, ABS , AAS, PMMA, PET, PBT, etc. It has good compatibility. It can be dyed into uniform and transparent colored plastics with direct pigment powder, and the homogeneous oil is non-toxic. It only needs to be stirred at high speed at 50-70℃. Can be used for molding processing.
To improve the transparency of the PE protective film, it is also necessary to pay attention to the addition of the polyolefin transparency additive DBS in the protective film. It is a dibenzylidene sorbitol synthesized from sorbitol and benzaldehyde, which is specially used for polyolefins. It can reduce the haze of PP by 60%, and LLDPE can reduce the haze by 61%, and can increase the rigidity by 8-10%. It can also increase the heat resistance by 9-10℃ and increase the crystallization speed of PO by more than 1 time. In this way, the gloss and brilliance of the film are improved.