Process for the preparation of polyesters from dicarboxylic acids and bis (hydroxy-alkyl) esters

Claim 1

A PROCESS FOR THE PREPARATION OF A SYNTHETIC FIBERFORMING LINEAR POLYESTER IN WHICH THE RECURRING ESTER LINKAGES ARE AN INTEGRAL PART OF THE POLYMER CHAIN WHICH COMPRISES POLYMERIZING A MIXTURE CONSISTING ESSENTIALLY OF (A) A MONOMERIC BIS(HYDROXYALKYL)ESTER OF AN AROMATIC DICARBOXYLIC ACID, THE ALKYL SUBSTITUENT OF SAID BIS(HYDROXYALKYL) ESTER HAVING THE FORMULA -(CH2)N-, WHERE N IS AN INTEGER FROM 1-10 AND (B) A DICARBOXYLIC ACID, THE MOLAR RATIO OF SAID ESTER TO SAID ACID BEING AT LEAST 1.0:0.9, WITH AT LEAST 0.1 MOL OF DICARBOXYLIC ACID BEING PRESENT PER MOL OF SAID ESTER, THE POLYMERIZATION BEING CONDUCTED AT A TEMPERATURE OF AT LEAST ABOUT 220* C. IN THE PRESENCE OF AT LEAST ABOUT 0.01 MOL PERCENT, BASED ON THE ESTER GLYCOL AND SUFFICIENT TO REDUCE ETHER FORMATION, OF A BASIC SALT OF A METAL HAVING AN ATOMIC NUMBER LESS THAN 26 AND CAPABLE OF REACTING WITH THE DICARBOXYLIC ACID UNDER THE CONDITIONS OF REACTION, SAID POLYMERIZATION BEING CONTINUED UNTIL THE PRODUCT HAS AN INHERENT VISCOSITY OF AT LEAST 0.3 IN A MIXTURE OF 60% PHENOL AND 40% SYM-TETRACHLORETHANE.