Copolymerization of dicarboxylic acids and dialkyl esters of dicarboxylic acids to form polyesters
AssigneeEastman Chemical Company
InventorsCharles E. Sumner, Jr., Gary D. Boone
Life of this patent
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Abstract
The present invention relates to a process for copolymerizing a dicarboxylic acid, a dialkyl ester, and a diol in the presence of a transesterification catalyst. The process involves heating a mixture containing carboxylic acids and esters in excess diol at elevated temperatures in the presence of a transesterification catalyst and returning any vaporized diol to the reaction vessel until the theoretical amount of alcohol and/or water have been evolved. The alcohol and/or water of reaction is not allowed to return to the vessel. When the theoretical weight of alcohol and/or water is collected, the excess diol is removed and the polymerization is allowed to proceed.
Claims22
A process for preparing a polyester or copolyester, said process comprises the following steps:
- (I) reacting
- (A) a dicarboxylic acid or a copolymerizable carboxylic acid wherein the copolymerizable carboxylic acid contains a primary alkyl ester group having 1 to 6 carbon atoms;
- (B) a dialkyl ester having 2 to 4 carbon atoms of a dicarboxylic acid;
- and
- (C) a diol,
- in the presence of at least one transesterification catalyst at temperatures in the range of 150.degree. C. to 300.degree. C., and pressures of atmospheric to about 0.2 mm Hg wherein the reaction between the dicarboxylic acid and diol produces an ester and water, and the reaction between the dialkyl ester of a dicarboxylic acid and diol produces an ester and alcohol, provided the concentration of diol is maintained, by backadding the diol to the reaction, at a level equal to at least a 2% molar excess of the total concentration of components (A) and (B);
- and (II) polycondensing the reaction product of Step (I) to form a polyester or copolyester under increased temperature and reduced pressure while excess diol is removed.
A process for preparing a polyester or copolyester, said process comprises the following steps:
- (I) reacting
- (A) a dicarboxylic acid or a copolymerizable carboxylic acid wherein the copolymerizable carboxylic acid contains a primary alkyl ester group having 1 to 6 carbon atoms;
- (B) a dimethyl ester of a dicarboxylic acid;
- and
- (C) a diol,
- in the presence of at least one transesterification catalyst at temperatures in the range of 150.degree. C. to 300.degree. C., and pressures of atmospheric to about 0.2 mm Hg wherein the reaction between the dicarboxylic acid and diol produces an ester and water, and the reaction between the dimethyl ester of a dicarboxylic acid and diol produces an ester and methanol, provided the concentration of diol is maintained, by backadding the diol to the reaction, at a level equal to at least 2% molar excess of the total concentration of components (A) and (B);
- and
- (II) polycondensing the reaction product of Step (I) to form a polyester or copolyester under increased temperature and reduced pressure while excess diol is removed.
Dependencies are inferred from the claim text.