Thixotropic unsaturated polyester resins of prolonged durability with modified smectites added

The durability and reactivity of saturated polyester resins modified with smectites (added to enhance compatibility and resistance to sedimentation) (Table 2) were studied in relation to the structure of the substituent at the nitrogen atom in quarternary ammonium (R1R2R3R4)N+X- salts (Table 1). Altogether 56 salts were examined. Bentonite was used as smectite. The effect of the ammonium salts was evaluated by comparison with the model system (styrene + maleic anhydride), commercial unsaturated polyester resin and commercial pre-accelerated resin (Tables 3, 4, Figs. 1, 2). The quarternary ammonium salt added directly to the resin or present in the modified bentonite, enhanced the durability of the resin with the reactivity only slightly affected. The salts with one aromatic substituent (benzyl) and the other aliphatic (systems with salt 21) proved best.