Late addition of alkali metal sulfonate dye receptivity additive in polyesterification process

Claim 2

IN A POLYESTERIFICATION PROCESS COMPRISING CONTACTING A DICARBOXYLIC ACID OR ITS ESTER-FORMING DERIVATIVE AND A DIOL UNDER POLYESTER-FORMING CONDITIONS, THE IMPROVEMENT COMPRISING ADDING AN EFFECTIVE DYE RECEPTIVITY IMPROVING AMOUNT OF A SULFONATE COMPOUND HAVING THE GENERAL FORMULA

Claim 3

In a polyesterification process comprising contacting a dicarboxylic acid or its ester-forming derivative and a diol under polyester forming conditions, the improvement comprising incorporating into said polyesterification process a sulfonate represented by the general formula

Claim 4

In a polyesterification process comprising contacting a dicarboxylic acid or its ester-forming derivative and a diol under polyester forming conditions, the improvement comprising incorporating into said polyesterification process a sulfonate represented by the general formula

Claim 5

A process according to claim 2 wherein said sulfonate is a mixture of

Claim 6

A method according to claim 2 wherein said sulfonate is a mixture of

Claim 7

A method accorDing to claim 2 wherein said sulfonate is represented by the formula

Claim 8

A process according to claim 2 wherein said sulfonate is

Claim 9

A method according to claim 2 wherein said sulfonate is selected from the group consisting of dimethyl sodium 5-sulfoisophthalate, dimethyl potassium 5-sulfoisophthalate, di-n-pentyl lithium 3-sulfoterephthalate, potassium 5-sulfoisophthalic acid, monosodium 5-sulfosalicylic acid, monopotassium 5-sulfosalicylic acid, methyl lithium 5-sulfosalicylate, n-propyl sodium 3-hydroxy-4-sulfobenzoate, and monopotassium 2,5-dimethyl-4-hydroxy-3-sulfobenzoic acid.

Claim 10

A method according to claim 2 wherein said sulfonate is selected from dimethyl sodium 5-sulfoisophthalate and monosodium 5-sulfosalicylic acid.

Claim 11

A method according to claim 2 wherein said dicarboxylic acid or its ester-forming derivative is an ester of an aromatic dicarboxylic acid and said diol is a glycol containing two to 10 carbon atoms per molecule.

Claim 12

A method according to claim 9 wherein said ester is dimethyl terephthalate and said glycol is ethylene glycol.

Claim 13

A method according to claim 10 wherein said alkali metal hydroxide is sodium hydroxide.

Claim 14

A method according to claim 11 wherein said dimethyl terephthalate and said ethylene glycol are heated at a temperature of 150* C. to 270* C. to effect an initial transesterification reaction with removal of the methyl alcohol thus evolved; and thereafter the reaction mixture is further heated to complete the polycondensation and to distill excess glycol from the reaction mixture, the initial molar ratio of glycol to terephthalate being in the range of 2:1 to 4:1, there being present during said polyesterification a catalyst selected from the group consisting of antimony oxide, zinc acetate, manganese acetate, and cobaltous acetate.