Introduction of additives for biodegradable plastic products

Organic compounds
Organic nucleating agents have the advantages of small dosage, quick effect and good compatibility, and have become a research hotspot in recent years. The relatively mature categories at home and abroad are mainly concentrated in the two categories of hydrazine and amide, the main manufacturers are Nissan Chemical, Shanxi Chemical Research Institute and so on.
(1) hydrazides
Hydrazides are compounds containing R1 -- CONHNH -- R2 groups formed by the reaction of carboxylic acids and their derivatives with hydrazine or alkyl substituted hydrazine. At present, the main varieties of polylactic acid special hydrazide nucleating agents are arylhydrazide compounds.
Asahi Kawamoto et al. synthesized a series of hydrazide nucleating agents and tested the effect of these agents on the crystallization of PLA. The results showed that dicarboxylic acid salicylate hydrazide greatly promoted the crystallization of PLA. Recently, the Wang Kezhi team of Shanxi Institute of Chemical Engineering launched the PLA nucleating agent with the brand name TMC-300 and TMC-306 for the first time in China. It was found that the half-crystal time of PLA was reduced to 40s and the non-isothermal crystallization temperature and crystallinity of PLA were greatly increased by TMC-300 at 110 ℃ and 0.8%. It was also found that the thermal deformation temperature (HDT) was as high as 129 ℃ after tempering PLA with TMC-300 combined with talC powder.
(2) Amides
Some studies have shown that ethyl distearamide (EBS, EBH-SA) compounds can promote the crystallization process of PLA. In 2006, a PLA nucleating agent with aryl triamide structure was introduced by NiKEN Riken Corporation. Recently, Nissan Chemical launched a series of nucleating agents under the brand name Ecopromote. It is reported that the nucleating agent can not only increase the crystallization speed of PLA, but also improve the thermal deformation temperature and transparency of PLA.
At the same time, the Wang Kezhi team of Shanxi Chemical Research Institute took the lead in launching the polyamide PLA nucleating agent with the brand TMC-328 in China, opening up a new road for the research and development of biodegradable plastic nucleating agents in China. Bai Hongwei et al. from Sichuan University used TMC-328 nucleating agent to blend with PLA and proved that TMC-328 can self-polymerize in PLA melt through intermolecular hydrogen bond, thereby inducing PLA molecular chain segments to attach to it for growth.
(3) Organic salts
Organophosphates are also a kind of PLA nucleating agents with excellent properties. The results show that this kind of nucleating agent can promote the crystallization growth of PLA well, and can fine the grain well, the effect is much better than the inorganic nucleating agent such as talc powder.
The PLA nucleating agent with the brand TMC-210 developed and launched by Wang Kezhi team of Shanxi Institute of Chemical Engineering effectively increased the crystallization temperature and crystallinity of PLA during the crystallization process, and shortened the molding cycle of PLA. In addition, the crystallization temperature of PHAs can be significantly increased. In addition, the LAK series nucleating agent announced and launched by Takemoto Oil & Fat Company in Japan has also been successfully used for crystallization modification of polylactic acid.
(4) supramolecular chemistry
The representative types of supramolecular chemical nucleating agents are calixarene and cyclodextrin. Studies have shown that such nucleating agents can improve the crystallization properties of polylactic acid, but there are no mature industrial varieties.
(5) Polymer materials
Nucleating agents of polymer materials include polyglycolic acid and its derivatives, polyglycolic acid and its derivatives and all-aromatic polyesters. Among them, the most studied and most widely used is PLLA/PDLA stereopsis. A large number of studies have shown that the crystals of the stereomorphs can be formed before the homopolymers of simple PLLA or PDLA, and the nucleation rate of the stereomorphs is very fast, so it can provide a large number of crystal nuclei and effectively promote the crystallization process of pure PLLA.
In summary, the research on the supporting nucleating agent of biodegradable plastic PLA has been widely carried out at home and abroad, and has obtained excellent results. The research and development directions of PLA nucleating agents mainly focus on improving the heat resistance, transparency and crystallization behavior of PLA. At the same time, the high efficiency, green, harmless nucleation agent is also one of the main directions of future development.