INFLUENCE OF DIBASIC ACIDS ON THE PROPERTIES OF MODIFIED POLYURETHANECOATINGS

In recent years, High Solids coatings have gained importance because t hey are environmentally friendly. In their formulations, it is especia lly difficult to balance the need;or high solids and low application v iscosity without sacrificing the properties. For the purpose of develo ping high solids formulations five polyester-polyols were synthesized at 210-230 degrees C. Conversion of the polyester polyols was monitore d by determining the acid number with respect to time The hydroxyl num ber of the polyester polyols was determined practically and also calcu lated theoretically. The number, weight and Z-average molecular weight and polydispersity of the polyester polyols were obtained from GPC. T he viscosity of polyester polyols in tetrahydrofurane (THF) and methyl isobutyl ketone (MIEK) was determined by using Emila Rotational Visco meter. Polyurethane resins prepared by adding the required amount of d iphenyl methyle diisocyanate (MDI) to polyester polyol solution in MIB K were applied to different substrates for determining properties such as drying time scratch hardness. tensile strength, flexibility, resis tance to impact and chemicals. The results indicate that the neopentyl glycol polyester polyol prepared by using 1:1 adipic acid and isophth alic acid have better properties This is probably because of the fact that isophthalic acid constitutents improve the rigidity and the adipi c acid component adds to the flexibility of polyurethane coatings.