Synthesis and Characterization of Novel Alkyd-Siloxane Hybrid Resins

摘要

Alkyds have been used as binders for paints for centuries. But due to the development of synthetic polymers alkyd usage have been diminished during the past 40 years. Severe restrictions on VOCs by recent legislation, has led to resurgence in alkyd use. Some of the benefits in using alkyds is that much of the ‘high solids’ coatings used earlier had alkyds in them, alkyd synthesis requires naturally occurring oils as raw materials and resultant coatings are more environmentally compatible than the coating binders from other systems . Inspite of the benefits, the unmodified alkyds are soft, lack moisture and alkali resistance, have poor outdoor weatherability and color retention. The ability of the alkyds to be modified in wide variety of ways accounts for their use in more type of paints than any other binder. This versatility can be used in an attempt to avoid disadvantages of unmodified alkyds, by synthesizing its hybrids with various other resin systems. One of them blends of silicones and alkyd resins. This system made their first appearance at the end of 1946 and it use have been discussed increasingly in many literature . Importance of silicon- alkyd system is derived from the properties of the two resins which complements each other thus enabling the resultant copolymer to have high-temperature surface finish properties . In the present study a series of alkyd resins with different oil length is taken and coupled with siloxanes having different substitutions at the backbone as methyl, cyclopentyl and cyclohexyl. The characterization of the synthesized hybrids have been done by FT-IR and 1H-NMR. Mechanical, Viscoelastic and coating charecterization of these hybrids were then performed.