An improved curable formaldehyde-free binding composition is provided.
Such curable composition comprises the reaction product of a
polyanhydride and a polyol crosslinker and a lower molecular weight
anhydride. Initially, the polyanhydride is modified through reaction with
a polyol (e.g., a glycol or an alkanolamine) and subsequently is grafted
with the lower molecular weight anhydride (e.g., maleic anhydride) to
form a water-soluble or water-dispersible curable reaction product. The
composition is well suited for binding fibrous materials (e.g., a mat of
glass fibers) or for bonding together non-fibrous materials. The binder
composition displays an advantageous viscosity so as to facilitate a
flowable application with ease combined with an adequately high molecular
weight to satisfactorily undergo service as a binder following curing
even when harsh environmental conditions (e.g., hot humid air) are
encountered for a prolonged period of time