Selection of coalescing solvents for coatings derived from polyurethane dispersions utilizing high throughput research methods

Abstract

Reduction of volatile organic compounds (VOCs) in coatings is being driven by regulation and consumer preference. Development of binders that are capable of delivering expected performance at low VOC is a major thrust of coatings research and development. Toward this end, polyurethane dispersions (PUDs) from natural oil polyester polyols (NOPs) have been developed. These hydrophobic NOP-based PUD coatings exhibit exceptional early water resistance and hydrolytic stability, excellent acid resistance, and good toughness & abrasion resistance. Most high performance PUDs require large amounts of solvent to form crack-free films with good properties. However, with the right choice of process and solvent parameters, PUDs have been shown to require reduced amounts of coalescing solvents to yield the desirable array of end-user properties with ambient temperature drying. High-throughput research (HTR) was used as a means to accelerate formulation and product development of PUDs. Rapid formulation and testing allows for probing of interactions between variables in greater depth and breadth than conventional formulation techniques, leading to rapid development of robust products and formulations. The HTR methods for coatings applications include the use of specially designed experiments, robotic formulation, coating, and characterization tools as well as informatics for data visualization, extraction, and modeling. This paper details the use of HTR capability to explore the effect of cosolvents on end-use properties of NOP based PUD coatings as well as the proposed mechanisms of film formation in NOP-PUDs. The results provide a basis for guidelines for selection of cosolvents for PUD coatings with high performance and low VOC (<100 g/L VOC).