Novel Gelling Catalyst for Non-Emission Flexible Polyurethane Foam

Flexible and semi-rigid polyurethane foams have been widely used in automotive interior parts, residential upholstered furniture and bedding. In these, as well as other end use industries, a reduction of Volatile Organic Compounds (VOCs) emissions from polyurethane foams continues to be an important issue [1, 2]. To address this challenge, reactive amine catalysts, which have an active hydrogen group, have been developed, evaluated, and used for the purpose of reducing VOC emissions. Unfortunately, many of these reactive catalysts tend to lose their catalytic activity during the latter stages of the foaming process resulting in decreased performance during the curing function. TOSOH Corporation has continued to research the next-generation of non-fugitive catalysts for polyurethane systems, and recently developed a novel gelling catalyst that provides improved performance in overall catalytic activity. This catalyst has a similar function as TEDA and exhibits better durability performance compare to other non-fugitive catalysts. TOSOH Corporation will review this work and propose solutions for reduced VOC systems with low or non-emission catalyst. INTRODUCTION Polyurethane foam is made from polyols, isocyanates and additives such as catalysts, silicone surfactants, flame retardants, anti-oxidants, chain-extenders, crosslinkers, release agents, etc. In general, the automotive and furniture industries are sensitive to VOCs due to customer specifications and regulations. Tertiary amine catalysts such as TEDA have been used for many years in the production of polyurethane foam. Their usage, however, is targeted for reduction due to emissions from the finished foam and associated unpleasant odor. In order to overcome the emission problems, a wide variety of non-fugitive amines containing hydroxyl, amino and urea groups have been proposed and evaluated[3-9], because such catalysts can react with isocyanate group during the foaming process and become part of polymer network. However, a fully adequate replacement catalyst system has not been found yet. The catalytic activity of these non-fugitive catalysts is lower than conventional catalysts and the foam properties, curing function and durability performance, tend to worsen due to the lack of gelling activity. For this reason, amine catalysts that have high gelling activity such as TEDA and exhibit low-emissions are a consistent demand from the market. Previously, Tosoh has reported the gelling properties and potential of reactive TEDA (RTEDA) by using computational chemistry [10]. To establish this result, RTEDA was synthesized and evaluated by comparison of various kinds of reactive amines. In this paper, the characteristics of RTEDA are discussed. In addition, novel amine catalysts systems are proposed for Flexible and semi-rigid polyurethane foams.