Process for manufacture of plasticized homopolymeric polyvinyl alcohol and plasticized polyvinyl alcohol polymer obtained therefrom

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

• introducing into a mixing reactor a polyvinyl alcohol polymer comprising polyvinyl alcohol or a blend thereof having a degree of hydrolysis in the range of 93 wt % or greater;
• 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 the primary outlet, the inter-engaging components being arranged to apply a shearing force to the polyvinyl alcohol polymer while the polyvinyl alcohol polymer is conveyed by the components from the primary inlet through a reaction zone to the primary outlet;
• one or more secondary inlets located downstream from the primary inlet for introducing reactants comprising a processing aid, a plasticizer and a reactive stabilizer to the blending chamber to form a reaction mixture;
• wherein the plasticizer comprises two compounds selected from the group consisting of:
• diglycerol, triglycerol, xylose, D-mannitol, dipentaerythritol, triacetin, 1,4 butanediol, 3,3-dimethyl-1,2-butanediol, caprolactam and mixtures thereof;
• wherein the reactive stabilizer is selected from the group consisting of:
• potassium oleate, sodium benzoate, and mixtures thereof;
• wherein the blending chamber comprises a plurality of heated regions arranged so that the mixture is subjected to a temperature profile whereby the temperature increases from the primary inlet to the primary outlet;
• a secondary outlet located between the reaction zone and primary outlet arranged to allow removal of processing aid from the chamber;
• reacting the processing agent, plasticizer and polyvinyl alcohol polymer in the reaction zone to form plasticizer polyvinyl alcohol polymer;
• and
• allowing the plasticized polyvinyl alcohol polymer to pass from the primary outlet.