A NEW PROCESS FOR THE CONTINUOUS ACETYLATION OF LIGNOCELLULOSIC FIBER

A new process for the continuous acetylation of lignocellulosic fiber has been developed. The fiber enters a pre-heated reactor and a specified concentration of acetic anhydride is applied. The fiber moves through the reactor at a rate needed for the acetylation to take place to the desired weight gain. The fiber then goes into a first stripper loop unit where the loop atmosphere consists of superheated vapors of acetic anhydride and acetic acid. Excess chemicals are evaporated from the fiber material and the chemicals recovered. In a second stripper, any remaining acetic anhydride is hydrolyzed to acetic acid by treatment with water vapor and the acetic acid is stripped off in a stream of superheated steam. The acetylated fiber can be conditioned and resinated in a final step before processing into composites. Composites made from acetylated fiber have been shown to have greatly improved dimensional stability and biological resistance