Process and apparatus for manufacture of processable polyvinyl alcohol

A method for manufacture of plasticized homopolymeric polyvinyl alcohol, the method comprising the steps of:

• introducing into a mixing reactor a polyvinyl alcohol polymer consisting of polyvinyl alcohol or a blend thereof having a degree of hydrolysis greater than 93 wt %;
• wherein the mixing reactor comprises a blending chamber having a primary inlet, a primary outlet and at least two inter-engaging components extending between the primary inlet and primary outlet, the components being arranged to apply a shearing force to the polymer while the polymer is conveyed by the components from the inlet through a reaction zone to the outlet;
• one or more secondary inlets located downstream from the primary inlet for introducing ingredients consisting of water, a plasticizer and a reactive stabilizer to the chamber;
• wherein the plasticizer is selected from the group consisting of:
• diglycerol, triglycerol, fructose, ribose, xylose, D-mannitol, triacetin, pentaerythritol, dipentaerythritol, methyl pentanediol, 1,2-propanediol, 1,4-butanediol, 2-hydroxy-1,3-propanediol, 3-methyl-1,3-butanediol, 3,3-dimethyl-1,2-butanediol, caprolactam, tricyclic trimethylolpropane formal, erucamide and mixtures thereof;
• wherein the reactive stabilizer is selected from the group consisting of:
• sodium stearate, potassium oleate, sodium benzoate, calcium stearate, dimethyl propionic acid, and mixtures thereof;
• wherein the blending chamber comprises a plurality of heated regions arranged so that the ingredients are subjected to a temperature profile whereby the temperature increases from the inlet to the outlet;
• a secondary outlet located between the reaction zone and primary outlet arranged to allow removal of water from the chamber;
• reacting water, plasticizer, reactive stabilizer and the polyvinyl alcohol polymer in the reaction zone to form the plasticized polymer;
• and
• allowing the plasticized polymer to pass from the primary outlet.