Process for improving the stability of acetal polymers
AssigneeSocieta' Italiana Resine S.I.R. S.p.A.
InventorsPierino Radici, Sergio Custro, Paolo Colombo
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Abstract
The terminal hydroxyl groups of an acetal polymer are esterified or etherified by reaction with an end-capping agent chosen from anhydrides of carboxylic acids, orthoesters and orthocarbonates, by forming an intimate mixture of polymer in powder form and liquid end-capping agent, the amount of said agent in the mixture being less than that which results in loss of the free-flowing characteristics of the powder, and reacting said mixture under stirring at 50.degree.-170.degree. C.
Claims15
A process for esterifying or etherifying the terminal hydroxyl groups of an acetal polymer by reacting said polymer with an end-capping agent selected from the group consisting of anhydrides of carboxylic acids, orthoesters and orthocarbonates, which comprises forming an intimate mixture of acetal polymer in powder form and end-capping agent in liquid form, the amount of said liquid end-capping agent in the mixture being from 0.01 to 0.30 parts by weight per part by weight of acetal polymer and less than that which results in loss of the free-flowing characteristics of the polymer powder, reacting said mixture under stirring at a temperature of at least 50.degree. C. until completion or substantial completion of the end-capping reaction, and recovering the polymer thus end-capped from the reaction product.
A process for esterifying or etherifying the terminal hydroxyl groups of an acetal polymer by reacting said polymer with an end-capping agent selected from the group consisting of acetic, propionic and butyric anhydrides, methyl and ethyl orthoformates, methyl and ethyl orthoacetate and methyl and ethyl orthocarbonates, which comprises forming an intimate mixture of acetal polymer in powder form and end-capping agent in liquid form, the amount of said liquid end-capping agent in the mixture being 0.01 to 0.30 parts by weight per part by weight acetal polymer and less than that which results in loss of the free-flowing characteristics of the polymer powder, reacting said mixture under stirring at a temperature of at least 50.degree. C. until completion or substantial completion of the end-capping reaction, and recovering the polymer thus end-capped from the reaction product.
Dependencies are inferred from the claim text.