Use of Carbodiimides for Interior Clear Wood Floor Finishes

By Pat Bell, Ben Glowacki

Since the early 1800s, traditional solvent-based coatings have been manufactured and used extensively in the United States to protect interior woodwork, including commercial and residential floors. However, to meet the growing health and environmental concerns, regulatory agencies throughout the world have begun to reduce the allowable amount of volatile organic compounds (VOC) that coatings can release into the atmosphere.

These regulations have initiated the transition from solvent-based to water-based coatings. Early water-based coatings technology did not offer the same level of durability as solvent-based systems, so the use of external cross-linkers emerged. Crosslinkers such as aziridines, isocyanates, and carbodiimides have been and continue to be used to increase the durability of water-based coatings. Each crosslinker brings with it positives and negatives, but they all improve coating properties to some degree.

Aziridines and carbodiimides react with carboxyl groups present in most water-based acrylics and urethanes, while isocyanates typically require hydroxyl-functionality to maximize their benefits. Although aziridines and isocyanates are used extensively in the professional market, carbodiimides have a very limited commercial presence.

Traditionally, they have not been considered a true workhorse capable of delivering the increased level of durability required by the professional market. The objective of the work presented here has been to determine the effectiveness of a specific carbodiimide and if its performance can approach the durability demanded by the professional market.