Method of making polyester prepolymers
AssigneeEastman Kodak Company
InventorChen-i Lu
Life of this patent
Estimating the term…
Abstract
A polyester prepolymer having increased reactivity when subjected to molecular weight buildup, such as in solid phase polymerization is prepared by an improved method which includes the steps of: reacting a dicarboxylic acid and a glycol in the presence of a transesterification catalyst to form a reaction mixture containing condensation oligomers; purifying the reaction mixture to remove substantially all of the reaction by-products and residual dicarboxylic acid, glycol and catalyst and to crystallize the condensation oligomers; and polycondensing the oligomers to form a molten prepolymer.
Claims19
In a method for preparing a prepolymer composed of constituents of a dicarboxylic acid and a glycol, which method comprises:
- (a) reacting said dicarboxylic acid and said glycol in the presence of a transesterification catalyst at a reaction temperature and pressure effective to form a reaction mixture containing condensation oligomers, reaction by-products and residual dicarboxylic acid, glycol and catalyst;
- and
- (b) subjecting said reaction mixture to a temperature and pressure effective to polycondense substantially all of said oligomers to form a molten prepolymer,
- the improvement which comprises purifying said reaction mixture prior to said polycondensation step (b) to remove substantially all of said reaction by-products and said residual dicarboxylic acid, glycol and catalyst and to crystallize said condensation oligomers, whereby said prepolymer has increased reactivity when subjected to polymerization.
In a method for preparing a prepolymer composed of constituents of a dicarboxylic acid represented by the formula ##STR4## wherein n is 0 or 1, each of R and R.sup.1 is hydroxy or alkoxy of from 1 to 12 carbon atoms, and R.sup.2 is alkylene, cycloalkylene or arylene of from 1 to 18 carbon atoms;
- and at least one glycol represented by the formula HO--R.sup.5 --OH wherein R.sup.5 is alkylene, cycloalkylene or arylene of from 1 to 18 carbon atoms, which method comprises:
- (a) reacting said dicarboxylic acid and said glycol in the presence of a transesterification catalyst at a temperature in the range of from about 180.degree. to about 220.degree. C. and a pressure in the range of from about 760 to about 1520 mm Hg to form a reaction mixture containing condensation oligomers, reaction by-products and residual dicarboxylic acid, glycol and catalyst;
- and
- (b) subjecting said reaction mixture to a temperature in the range of from about 209.degree. to about 300.degree. C. and a pressure in the range of from about 0.2 to about 5 mm Hg to polycondense substantially all of said oligomers to form a molten prepolymer,
- the improvement which comprises purifying said reaction mixture prior to said polycondensation step (b) by extracting substantially all of said reaction by-products and said residual dicarboxylic acid, glycol and catalyst with a solvent heated to a temperature in the range of from about 20.degree. to about 70.degree. C., thereby crystallizing said condensation oligomers, whereby said prepolymer has increased reactivity when subjected to polymerization.
In a method for preparing a polyester composed of constitutents of a dicarboxylic acid and a glycol, which process comprises:
- (a) reacting said dicarboxylic acid and said glycol in the presence of a transesterification catalyst at a reaction temperature and pressure effective to form a reaction mixture containing condensation oligomers, reaction by-products and residual dicarboxylic acid, glycol and catalyst;
- and
- (b) subjecting said reaction mixture to a temperature and pressure effective to polymerize substantially all of said oligomers to form a polyester,
- the improvement which comprises purifying said reaction mixture immediately after said reaction step (a) to remove substantially all of said reaction by-products and said residual dicarboxylic acid, glycol and catalyst and to crystallize said condensation oligomers.
Dependencies are inferred from the claim text.