Polyester resins based on fatty acids that have a short oil length, aqueous dispersions and associated coatings
The invention relates to a polyester resin which is based on at least one fatty acid, with zero oil length (0%) or an oil length of between 0 and 35%, with a weight ratio of oxidizable fatty acids (monoacids), relative to the overall fatty acids, of 0 or greater than 0 and ranging up to 1, and which is based on an acid component comprising, in addition to the fatty acid, from 30% to 85% by weight, relative to the total weight of said resin, of rosin and/or of derivatives thereof bearing at least one carboxylic acid function.
1. A polyester alkyd resin,
derived from at least one fatty acid and an alcohol component comprising at least one polyol of functionality ranging from 2 to 10, and
an acid component comprising, in addition to said fatty acid, from 45% to 75% by weight, relative to the total weight of said resin, of rosin and/or rosin derivatives bearing at least one carboxylic acid function,
said resin having a zero oil content (0%) and said fatty acid being selected from the group consisting of non-oxidizable fatty acids with a corresponding content of oxidizable unsaturations that is 0 mmol per g of dry resin or said resin having an oil content up to 5% and wherein in addition to said fatty acid selected from the group consisting of non-oxidizable fatty acids, further comprising in minor weight proportions the oxidizable fatty acid leading to said oil content ranging up to 5%, and having a weight ratio of oxidizable fatty monoacids relative to the overall fatty acids of 0 or higher than 0 and corresponding to said oil content up to 5%,
said resin having an acid number less than 8 and a number-average molecular mass Mn, measured by GPC as polystyrene equivalents in THF, ranging from 1,000 to 10,000,
wherein said non-oxidizable fatty acid is selected from the group consisting of fatty acid oligomers.
2. The resin of claim 1 , comprising less than 5% by weight of aromatic compound besides the optional rosin derivatives.
3. The resin of claim 1 , having a Tg, measured by DSC, ranging from −40 to 50° C.
4. The resin of claim 1 wherein said resin is derived from an alcohol component comprising glycerol oligomer, and as non-oxidizable fatty acid a fatty acid oligomer which is a C 36 fatty acid dimer and/or a C 54 fatty acid trimer.
5. An organic, non-water-base binder composition comprising at least one resin of claim 1 .
6. The organic, non-water-based binder composition of claim 5 , wherein, in addition to the at least one resin of claim 1 , further comprising at least one second resin different from the first, the second resin being selected from the group consisting of polyester resins derived from fatty acids.
7. The resin of claim 2 , comprising no aromatic compounds other than the optional rosin derivatives.
8. A coating composition comprising the organic, non-water-based binder composition of claim 5 , wherein said coating is a protective coating in coil applications.