Union production of low chlorinated polyethylene and chlorinated paraffin via a carbon tetrachloride solvent free process

• Published in: Journal of applied polymer science 2009-01, Vol.111 (1), p.63-69
• Main Authors: Tan, Kui-Long, Lu, Ying-Zhou, Sun, Ai-Jun, Li, Chun-Xi, Wang, Zi-Hao
• Format: Article
• Language: English
• Subjects: carbon tetrachloride; chlorinated polyethylene; chlorination; paraffin; reactive solvent
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.29048

A novel process for producing low chlorinated polyethylene (LCPE) with chlorinity of 28-33% by weight is presented, in which a reactive solvent, paraffin, is used as a green solvent to replace the commonly used inert solvent, carbon tetrachloride (CTC), an ozone depleting substance (ODS) being phased out under the Montreal Protocol. This process utilizes the principle that paraffin can dissolve high density polyethylene (HDPE) at about 135°C and the resulting solution can be chlorinated by chlorine forming two useful products simultaneously, viz chlorinated paraffin (CP) and LCPE, which are mutual soluble even at lower temperature e.g.70°C. The present process is superior to the conventional CTC solvent method because it can reduce the solvent emission dramatically, enhance the volume efficiency of reactor and achieve a union production of LCPE and CP under atmospheric pressure. The structure and properties of LCPE produced by two different methods are determined by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectrometer, proton magnetic resonance (¹H NMR), and gel permeation chromatography (GPC). The results indicate that polyethylene chain can be homogeneously chlorinated in paraffin as in CTC solvent via a radical mechanism, and the chlorinity of CP and LCPE is virtually same under optimal conditions.