Blend Optimization of Low-VOC Benzoate Coalescents

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Dibenzoate glycol esters have been used extensively as plasticizers and coalescent film-forming aids for many years. The advantages of dibenzoates have been discussed previously, but they include: low vapor pressure (in the range of 10-6-10-8 mmHg) resulting in low VOC content, appropriate solubility parameters for applications with polar polymers such as PVC and acrylates, biologically biodegradable, and environmentally safe for food contact applications in adhesives and coatings.1 Previous research presented at the Waterborne Symposium has shown the usefulness of these molecules as film-forming aids for architectural coatings in both interior and exterior applications.2,3 Dibenzoate glycol esters are low-VOC coalescent aids, and their performance advantages in architectural coatings include increased volume solids, gloss and scrub resistance.

This research seeks to expand upon hardness increases found in previous coatings research for direct-to-metal applications and use that concept as a formulary tool for architectural coatings.4 In this previous work dibenzoates and dipropylene glycol n-butyl ether (DPnB) were blended in 1:1 ratios, and the resulting hardness development in a styrene acrylic binder exceeded that of formulations containing 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPDMIB) while containing lower levels of VOC.4 This result was interesting, and warranted further exploration of this performance aspect in architectural coatings.