Global environmental protection requirements are becoming increasingly stringent, and humanity's demand for environmental purification is growing stronger. The regulatory pressure to limit the use of heavy metal heat stabilizers is intensifying, accelerating the development and production of heat stabilizers towards non-toxic, efficient, and multifunctional directions. Low lead, low dust, and alternative lead salts have become the focus of heat stabilizer variety development worldwide. There are relatively few new chemical substances introduced as stabilizers, while composite stabilizers are ubiquitous.
The development of various stabilizers shows the following trends.
(1) Dust-free lead salts are the most basic requirement, and low lead is a necessity imposed by the environment. Given the excellent performance of lead salts in pipes and insulation materials, the process of lead-free transition is slow worldwide. The true exit of lead salts from the historical stage requires the emergence of lead-free products with excellent performance-to-price ratios, the strengthening of environmental regulations, and time.
(2) Organotin products with excellent performance, particularly methyl tin, have seen significant development, especially in China. Our country has several patents in the field of methyl tin, and in recent years, Shenzhen Fansheng and Hubei Nanxing have made remarkable efforts in the production and promotion of methyl tin. Fansheng Company has mastered the key technology for producing 6000 tons of methyl tin annually using its patented technology, and has developed new reverse-cool organic tin compounds, marking that our country's production of organotin has reached a high level. Currently, there are no technical barriers to vigorously developing our organotin stabilizers, and what is needed is guidance from policies and regulations.
(3) Non-toxic metal soap calcium/zinc stabilizers have vast development potential. Abroad, calcium/zinc stabilizers have been used in large diameter pipes and insulation fields. However, domestic development of composite metal soaps is not given enough attention, and there is a lack of high-performance auxiliary stabilizer varieties, resulting in a significant contrast compared to foreign countries. The development of high-performance composite metal soaps relies on high-performance auxiliary stabilizers.
(4) Rare earth stabilizers are a type of heat stabilizer with Chinese characteristics and are developing vigorously. Currently, more than ten manufacturers and research institutions in the country are involved in the development of rare earth stabilizers. Manufacturers in places like Baotou are seizing the opportunity of China's large-scale development in the west and plan to build large-scale rare earth stabilizer bases. However, most of the rare earth stabilizers currently introduced are composites of rare earth and lead salts, which can only serve as a transitional product for low lead. The widespread use of rare earth stabilizers still needs to address the issues of insufficient lubricity and processability.
(5) Pure organic compounds are gaining attention as alternatives to metal stabilizers. Companies like Ciba Specialty Chemicals and Morton have successively introduced pure organic compound varieties represented by amino ketones. Compared to metal stabilizers, pure organic products are considered environmentally friendly and are expected to play a significant role in replacing toxic heavy metal stabilizers.
(6) Other products in recent years include new compounds used as heat stabilizers, such as hydrotalcite series and perchlorates. Cabot Corporation has combined perchlorates and their salts with epoxy compounds and antioxidants for use in PVC, achieving excellent heat resistance and color change resistance; the hydrotalcite series launched by Japan's Kyowa Pharmaceutical is a magnesium/aluminum composite used with zinc stearate in PVC to prevent coloration of the blend; Southern Chemical Company in Germany has built a production facility with an annual output of 5000 tons of hydrotalcite and holds patented technology. As a completely environmentally harmless additive, hydrotalcite has broad application prospects.