The Goodyear & Tire Rubber Company

John R Wilson

Fred L Massey

Marian M Rousek

Richard Robinson Smith

Isophthalic acid is commonly utilized as a comonomer in the preparation of copolyester resins which are utilized as solution adhesives. Unfortunately, solutions of such resins frequently become hazy due to the presence of cyclic oligomers. This invention is based upon the unexpected discovery that the presence of protonic acids during the synthesis of the copolyester resins containing isophthalic acid utilizing conventional metallic catalysts results in solutions of the resins in organic solvents being virtually haze free. The subject invention more specifically reveals a process for synthesizing a polyethylene terephthalate/isophthalate/azelate copolyester resin which is particularly useful as a solution adhesive resin, comprising reacting ethylene glycol with a diacid component which is comprised of (a) from about 25 to about 45 mole percent terephthalic acid, (b) from about 10 to about 30 mole percent isophthalic acid, and (c) from about 30 to about 55 mole percent azelaic acid based upon the diacid component; in the presence of at least one metallic catalyst selected from the group consisting of antimony compounds, titanium compounds; manganese compounds, and germanium compounds and in the presence of at least one protonic acid having a pKa of less than about 2.5; wherein the amount of metallic catalyst present is within the range of about 130 ppm to about 1500 ppm and wherein the amount of protonic acid present is within the range of about 50 ppm to about 500 ppm, with said amounts being based upon the weight of the copolyester resin produced.

Process for the synthesis of a copolyester adhesive resin

Isophthalic acid is commonly utilized as a comonomer in the preparation of copolyester resins which are utilized as solution adhesives. Unfortunately, solutions of such resins frequently become hazy due to the presence of cyclic oligomers. This invention is based upon the unexpected discovery that the presence of protonic acids during the synthesis of the copolyester resins containing isophthalic acid utilizing conventional metallic catalysts results in solutions of the resins in organic solvents being virtually haze free. The subject invention more specifically reveals a process for synthesizing a polyethylene terephthalate/isophthalate/azelate copolyester resin which is particularly useful as a solution adhesive resin, comprising reacting ethylene glycol with a diacid component which is comprised of (a) from about 25 to about 45 mole percent terephthalic acid, (b) from about 10 to about 30 to about 55 mole percent azelaic acid based upon the diacid component; in the presence of at least one metallic catalyst selected from the group consisting of antimony compounds, titanium compounds; manganese compounds, and germanium compounds and in the presence of at least one protonic acid having a pKa of less than about 2.5; wherein the amount of metallic catalyst present is within the rang eof about 130 ppm to about 1500 ppm and wherein the amount of protonic acid present is within the range of about 50 ppm to about 500 ppm, with said amounts being based upon the weight of the copolyester resin produced.

Melt blends of polyethylene isophthalate with polyethylene terephthalate or polybutylene terephthalate or copolymers thereof have good barrier resistant properties to oxygen. Such blends are useful as packaging materials, for example films, containers, bottles, and the like.

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Hartville, OH, United States of America

John R Wilson