Hydrophobicizing mould release agent for press moulding

摘要

Purpose - This paper seeks to address the preparation of new compositions of hydrophobicizing liquids as release agent for press moulds in the production of plastic articles of all kinds of polymers. Design/methodology/approach - Mixtures of thermo-stable polyethers (copolymer of ethylene oxide and propylene oxide) and polyols esters/mixed esters in the presence of phenothiazine as antioxidant were prepared and tested. Findings - All compositions were tested and compared with silicone oil polymethylsiloxane-100 (PMS-100). The lubricant was manually applied on a hot surface (160-190℃) of tray of press mould, without any change in the operating cycle. The finished products were easily removed from press mould, and showed higher durability. The release agent was also checked for production of polyethylene lids by automatic moulding at 170-200℃, and 17 lids have been obtained on one application. This is quite a good result compared with silicone oil PMS-100, which produced only four to five lids. Research limitations/implications - Because of complexity of obtained mixture, it was impossible to study the structure and composition of the obtained products by modern spectroscopy techniques. Practical implications - In order to obtain compositions of optimum properties a lot of mixtures were prepared and tested. Only compositions which showed suitable properties were reported. Originality/value - This paper provides detailed information on the experimental preparation of 37 compositions for hydrophobicizing mould release agents. Testing of different obtained hydrophobicizing liquids showed positive results, in production of plastic household articles, over silicone oil PMS-100. The finished products were easily removed from press mould and prepared hydrophobicizing liquids showed higher durability than silicone oil PMS-100. The obtained compositions are also favored from the point of view of commercial availability and ecology and can be considered as replacements for PMS-100 release agent.