Calcium Zinc Compound Stabiliser

About This Product

A calcium-zinc compound stabiliser is a lead-free heat stabiliser system for PVC, supplied ready to use as a one-pack. It combines calcium and zinc carboxylates, usually stearates, with co-stabilisers such as polyols, beta-diketones, hydrotalcite or zeolites, and often with lubricants and antioxidants. Because it has no single chemical identity, there is no one CAS number for the product; the safety data sheet lists the classified components of each grade. The range here runs from the 21 series to the 81 series, each designed for a particular process or product family. The two metals do different jobs. Zinc soaps react quickly with unstable chlorine sites in the PVC chain, which protects early colour, but the zinc chloride they form can trigger sudden blackening, known as zinc burning. Calcium soaps react with that zinc chloride and regenerate the zinc soap, while also absorbing hydrogen chloride and providing long-term stability. The co-stabilisers extend this balance, and the lubricants built into a one-pack control fusion and metal release. Formulating a grade is therefore about matching the metal ratio, co-stabilisers and lubricant balance to one process. Calcium-zinc systems are the mainstream replacement for lead stabilisers in pressure and drainage pipe, window and building profiles, cable insulation and sheathing, foam board, fittings and injection mouldings. With suitable grades they are also used in flexible PVC, including calendered film, hoses and plastisols, and in food-contact and medical applications where their low toxicity profile is an advantage. Typical addition in rigid pipe and profile is a few parts per hundred resin, depending on the grade's lubricant content. Buyers usually agree the physical form (powder, flake or dust-free granule), calcium and zinc content, volatile matter, and a heat-stability or Congo red result at a stated temperature, together with the recommended dosage for the process. Ask for a statement that lead and cadmium are not added, and, for food-contact or potable-water articles, a declaration of compliance against the applicable plastics regulations and approvals. Many calcium-zinc one-packs are not classified as dangerous goods for transport, but grades containing zinc compounds may carry aquatic hazard classifications, and fine powders can form combustible dust clouds. Check sections 2 and 14 of the safety data sheet for the exact grade. Under EU REACH and UK REACH, each registrable component of a mixture must be covered for import, so ask the importer to confirm this and to state whether any component is on the Candidate List. Store bags sealed in a cool, dry place, because moisture can cause lumps and affect dispersion. Use dust extraction at charging points and bond equipment to avoid static ignition of fine powder. When you enquire, state the product and process (pipe, profile, cable, film or foam), the extruder type, the stabiliser you use now and its dosage, the physical form you want, and any food-contact, potable-water or colour requirement.