PVC plastic formulations stabilizer design of the main idea of

PVC processed at high temperatures , can easily emit HCL, form unstable polyolefin structure . Meanwhile , HCL has a self- catalysis , will make further degraded PVC . In addition, if the presence of oxygen or iron, aluminum, zinc , tin, copper and cadmium ions , will catalyze the degradation of PVC , accelerate aging. Therefore, the plastic will be a variety of undesirable phenomena such as discoloration , deformation , cracking , mechanical strength , electrical insulation performance , brittle hair and so on. To solve these problems , the formula must be added stabilizers, in particular heat stabilizers is essential. For PVC stabilizers include thermal stabilizers, antioxidants , ultraviolet absorbers , and a chelating agent. Formulation design products according to the requirements and processing requirements of different species, different amounts of stabilizer. Heat stabilizer must be heat stabilizer for panel  able to capture the heat stabilizer having a pvc resin discharged from the catalytic HCL, or PVC resin can be produced with polyolefin structural instability reflected from the addition , to prevent or reduce the decomposition of PVC resin . Generally used in the formulation of the thermal stabilizer features, functions and products required to consider. For example: lead salt stabilizer is mainly used in hard products in . Lead salt stabilizer has good thermal stability , excellent electrical properties , low cost and so on. But its toxicity, easily contaminated products, can only produce opaque products. In recent years, compound stabilizer is a large number , one-component stabilizer has the danger of being replaced . Composite stabilizer is characterized by specific and strong , pollution, processing enterprises, the advantages of simple ingredients . However, no uniform standard, so each of the composite stabilizer vary greatly. Barium cadmium -based stabilizers is better performance of a heat stabilizers . Wider use of PVC plastic sheeting . Usually barium cadmium and zinc and organic phosphite antioxidant and use . Calcium zinc stabilizers can be used as non-toxic stabilizers used in food packaging and  triple pressed stearic acid medical devices, pharmaceutical packaging, but its stability is relatively low education , a large amount of calcium -based stabilizers when transparency is poor , easy to spray cream. Calcium zinc stabilizers are usually used polyols and antioxidants to improve its performance, the country has recently been used in rigid pipe Ca-Zn compound stabilizer appears. Organotin heat stabilizers better performance for rigid PVC products with a better variety of transparent products , especially toxic octyl tin packaging products almost become indispensable stabilizer, but its price is more expensive. Epoxy- type stabilizers usually used as secondary stabilizer. Such stabilizers and calcium barium cadmium zinc stabilizers are used together can improve the stability of light and heat , the drawback is easy to bleed . As well as the auxiliary stabilizer polyols, organic phosphites can . In recent years, there is also a rare earth -based stabilizers , and hydrotalcite -based stabilizer , a rare earth stabilizer is characterized by excellent processability , and hydrotalcite stabilizer is non-toxic . ( Two ) Antioxidant PVC products used in the processing of the process, due to heat , ultraviolet light oxidation , which generates free radicals and oxidative degradation related . Strand terminators primary antioxidant is also known as free radical scavenger . Its main role is Dioctyl phthalate  to combine with free radicals to form a stable compound , the chain reaction terminated , PVC with a primary antioxidant is generally bisphenol A. There secondary antioxidant or hydrogen peroxide decomposition agent , PVC secondary antioxidant as triphenyl phosphite and di-iso- octyl phenyl phosphite esters. Primary and secondary antioxidants can play with synergy. (C ) UV absorber PVC products used outdoors , because it is sensitive to the wavelength range by ultraviolet radiation , PVC molecules into the excited state , or a chemical bond is destroyed , causing radical chain reaction , and to promote the aging degradation of PVC . In order to improve UV resistance , often by adding an ultraviolet absorber .