ACETYLAYLATION TECHNOLOGY
The new process can be broken down into four basic steps : addition of chemical, reaction, and stripping of surplus acetic anhydride and formed acetic acid in two stepsตฝ . Ameasured amount of preheated acetic anhydride is mixed with the dried wood fiber in continuous moving screw reactor at approximately 140 c with a residence time of 5 to 10 minutes. Aplug screw at the end of the reactor separates the reactor from the first stripping tower. The atmosphere moving the fibers through the first stripper consists of a mixture of anhydride and acetic acid vapors. The vapors are kept superheated by a steam-heated exchanger and the fibers are separated in cyclone before being discharged to the next stripping step. Superheated steam (water vapor) is used in the second stripping tower to convert un-reacted anhydride to acid. The dry fiber is then remove from the system and ready for adhesive application if the acetylate fiber is to be made into composite