Cold cure foam

Cold cure foam is made by mixing polymeric materials in specialized machinery that maintains precise temperature and pressure. It uses high-reactivity polyols along with low molecular weight curing agents. To achieve the desired level of cross-linking, relatively high-reactivity isocyanates are also incorporated. This leads to a reaction between isocyanate (NCO) groups and hydroxyl (OH) groups before the foam begins to expand, which is caused by the production of CO2 gas from the reaction of NCO with water. This quick polyurethane reaction results in a foam that has greater intrinsic stability during the blowing process compared to hot cure foam. As a result, cold cure foam needs stabilizers to manage cell size and distribution, as well as to maintain the foam’s structure. In contrast, hot cure foam, which has lower intrinsic stability, requires a greater amount of stabilizers. The polyols used in cold cure foams are highly reactive, with 70% to 95% of their hydroxyl groups being primary. These polyols can contain up to 90% propylene oxide but mainly consist of primary OH groups sourced from ethylene oxide. In polyols, primary OH groups react more easily with isocyanates (commonly used in flexible hot cure foams) than secondary OH groups do. The OH values, which have molecular weights between 3000 and 4500 g/mol, generally fall between 42 and 56 mg KOH/g. A variety of isocyanates are employed for slab stock and molded foams, including modified TDI types combined with highly reactive polyols. However, pure MDI formulations are seldom used for cold cure slab stock foams. Foam density is regulated by adding water, usually around 1.5 to 5 parts for every 100 parts of polyol. The production process, including the assessment of properties and structures, must be closely monitored to ensure high quality.