Low VOC vinylester resin and applications
View Patent ↗A low viscosity (and therefore low VOC) resin can be produced by limiting the molar ratio of the reactants, especially the dicarboxylic acid compound, used in the reaction. Specifically, reacting a reaction mixture comprising (i) one mole of a diepoxide having at least two glycidyl ether type epoxy groups; (ii) 0.5 to 2.0 moles of an unsaturated monocarboxylic acid; (iii) 0.1 to 0.5, preferably 0.1 to 0.3, moles of maleic anhydride; and, (iv) water, until substantially all of the epoxy groups disappear leads to the formation of a resin with a high shear (at least 500 s −1 ) viscosity of less than 1200 cP when measured in a 70% NVM (non-volatile matter) styrene solution. The resin may be used in barrier coatings, gel coatings, skin coatings and as a laminate resin.
1. A resin comprising the reaction product obtained by reacting a mixture comprising; (i) a diepoxide having at least two glycidyl ether epoxy groups; (ii) an unsaturated monocarboxylic acid; (iii) maleic anhydride; and, (iv) water, until substantially all of the epoxy groups react wherein the molar ratio of diepoxide: unsaturated monocarboxytic acid; maleic anhydride is 1:0.5 to 2.0:0.1 to 0.5, respectively.
2. The resin of claim 1 wherein at least about 50% of the reaction product is a linear monomer or dimer.
3. The resin of claim 1 wherein the diepoxide is the condensation product of an epichlorahydrin and a diol.
4. The resin of claim 3 wherein the diepoxide is the condensation product of epichlorahydrin and bisphenol-A.
5. The resin of claim 1 wherein the unsaturated monocarboxylic acid is acrylic acid or methacrylic acid.
6. The resin of claim 1 wherein the water is present in about stoichiometric ratio with the maleic anhydride.
7. The resin of claim 1 wherein the resin has a viscosity of less than 1200 cP measured at a shear of 500 s −1 in styrene at 70% non-volatile matter.