Light stabilizer precursor triacetoneamine process technology and product applications
Hindered amine light stabilizers help prevent plastic products from decomposing under the influence of sunlight, air and heat, and can improve the environmental weather resistance and service life of plastic products. In addition to being used as plastic additives, they are also widely used in products such as automobiles, construction and agricultural films. Triacetoneamine is the most important precursor in hindered amine light stabilizers and is also a high-value derivative product of propylene. There is a lack of related synthesis technology in China, so ITRI has developed a high-yield triacetoneamine process, hoping to help domestic companies independently establish related synthesis technology to avoid reliance on imports and foreign manufacturers' monopoly.
Hindered Amine Light Stabilizers
Light stabilizers are mainly used to protect various outdoor products from degradation damage caused by light, especially high-energy ultraviolet light. They can delay side reactions such as photodegradation, thermal degradation or deliquescence, and further improve the service life and weather resistance of plastic or wood products. According to the type of action, they can be simply divided into: UV absorber, hindered amine light stabilizer (HALS) and light quencher. UV absorbers can absorb UV light through their own molecular structure, thereby reducing the direct damage of UV light intensity to materials or products. Hindered amine light stabilizers do not absorb UV light themselves, but rather transform into a stable molecular form (NOR) by combining the N-O free radicals in the structure with the free radicals (R·) formed by the initial photolysis of the material, thus avoiding chain reactions; through reactions with other free radicals (ROO·), they can be restored to stabilizers with active N-O free radical forms, thus greatly extending the tolerance and resistance to photodegradation of materials or products. They are also one of the materials with the largest share in the current light stabilizer market.
Triacetoneamine (TAA) is an important precursor for the synthesis of hindered amine light stabilizers. It is an organic molecule synthesized by the reaction of three acetones and one ammonia. Since acetone is mainly produced from propylene and benzene, it must be produced through the cumene process (Cumene Process) under oxygen to form (acetone and phenol), so triacetoneamine can be regarded as a high-value derivative of propylene.
Traditional triacetoneamine process and improved method
Triacetoneamine has been traditionally produced via batch reaction whereby acetone, ammonia, and a catalyst are heated together and subsequently distilled to yield pure triacetoneamine. Not only does the reaction of acetone and ammonia lead to the formation of triacetoneamine, but it also leads to the formation of various by-products; in addition, the reactions are reversible. The traditional catalytic agent used has been ammonium nitrate, which is itself explosive, hence requiring increased attention for workplace safety concerns and risk during storage and operation. A proper drawback is the necessity for sodium hydroxide to neutralize the catalyst after the reaction; this will add to the solid waste and increase subsequent treatment costs. As a result, in traditional batch reactions, it has been impossible to control the formation of by-products; thus, constant control of temperature and pressure during subsequent distillation purification has been rendered a necessity to separate the product and by-products effectively.
