Polyacetal (Polyoxymethylene) is known as Super Steel for its strength and superior resistance to the environment and all the benefits of being a thermoplastic. While processing it, workplace pollution due to the release of toxic formaldehyde fumes is a serious problem (more in the case of homopolymer and less in the case of co-polymer). Reprocessing of the same has further serious headaches. For years, a steric hindered phenol with high molecular weight was used as an antioxidant which resolved the problem only to some extent. This was the Industry standard. Using a conventional Phosphite e.g. Tris (2,4- ditert-butylphenyl) Phosphite (CAS NO 31570-04- 4) did not help much. In India, the potential in terms of usage of Polyacetal has not been fully realized and possibilities of reprocessing are not adequately utilized. This is unfortunate. Antioxidant technology today has advanced to such an extent that various versions of Phenolics and Phosphites are available, and if the choices of both are right then we stand a good chance of resolving problems.

This concept led to this Innovation. A study of various primary Antioxidants let us evaluate 2 products and further study showed that a blend of high molecular weight Phenolics having low volatility was right. This was confirmed by the manufacturer.

The experiment showed that the Yellowness Index (YI) was 23 with the new system as compared to 30 of regularly used products at 230 c/60 minutes. The initial YI was 6.0 for both trials. Though this was better, it was not so good on the balance of formaldehyde weight loss and YI was concerned. A real synergist Phosphite was definitely required. Going through the range of Phosphites and eliminating a few, was a dilemma that would work well with the Primary chosen. Dialogue could only narrow down the possibilities. One particular Phosphite having higher active phosphorus content and NOT decomposing at high temperatures was of Particular interest. After verifying the details with the manufacturer, the same was shortlisted. One trial was organized in a highly reputed company. Good results were obtained. Subsequently, further trials were organized in the same company and a repeat trial in another reputed company. Very encouraging results were obtained in both the trials. The generation of formaldehyde was substantially lesser as compared to the conventional Antioxidant for Polyacetal in both trials. Thus the combination has been validated. The Engineering Plastics industry should now be able to utilize the potential of Polyacetal more, and save precious natural resources.

This breakthrough was obtained more than 10 years ago. In January 2013, the combination of Primary 245 and Secondary 168 resolved the problem only 50% but OM Innovations resolved 100% in 2 companies.

• 1. Gujarat Petrosynthese Ltd., Bengaluru.
  2. GLS Polymers, Bengaluru.

POM is as strong as steel, lightweight and can be shaped by Plastic Processing thus the nickname "Super Steel".

Reference: Published as News in IPI Journal in Feb/March 2013.

Bharat should NOW fully exploit the Potential of this Polymer.