Dyeable spandex
View Patent ↗Commercial spandex can be prepared with greater efficiency, improved consistency and at lower costs from a high-solids content polyurethaneurea polymer solution. The polyurethaneurea is prepared using a combination of 4,4′-MDI and 2,4′-MDI, and an amount of chain extenders and chain terminators such that the polymer solution, prior to spinning, is highly soluble and has an appropriate pre-spun IV and primary amine content. Such spandex fibers, and the fabrics and garments comprising them, have good dyeability and colorfastness, as well as other desirable characteristics.
1. A method of making a polyurethaneurea comprising the steps of:
(a) contacting at least one polymeric glycol selected from the group consisting of polyether glycols and polyester glycols; with a diisocyanate mixture comprising at least about 78 mole percent 4,4′-MDI and at least about 5 mole percent 2,4′-MDI; wherein the molar ratio of the at least one glycol to the total moles of diisocyanate is between about 1:1.5 and about 1:2;
(b) contacting the product of step (a) with a composition comprising:
(1) a solvent selected from the group consisting of N,N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide, N,N-dimethylpyrrolidinone, and mixtures thereof;
(2) at least one chain extender comprising ethylenediamine or a mixture of chain extenders comprising ethylenediamine and a secondary chain extender; wherein ethylenediamine is at least about 90 mole percent of the total moles of chain extenders;
(3) a chain terminator selected from the group consisting of diethylamine, diisopropylamine, piperidine, dibutylamine, and mixtures thereof;
to form a polymer, wherein the pre-spun IV of the polymer is between about 0.65 and about 1.0 dl/g and the primary amine content is between about 25 and about 70 meq/Kg.
2. The method of claim 1 wherein: (i) the polymeric glycol is a polyether glycol having a number average molecular weight between about 1600 and about 2500; (ii) the molar ratio of the at least one glycol to the total moles of diisocyanate is between about 1:1.6 and about 1:1.8; and (iii) the diisocyanate mixture comprises between about 80 and about 95 mole percent 4,4′-MDI and further comprises between about 5 and about 20 mole percent 2,4′-MDI.
3. The method of claim 2 wherein: (i) the polyether glycol has a number average molecular weight between about 1800 and about 2000 and is selected from the group consisting of polyethyleneether glycol, polytrimethyleneether glycol, polytetramethyleneether glycol, polytetramethylene-co-2-methyl-tetramethyleneether glycol, polytetramethylene-co-tetraethyleneether glycol, and mixtures thereof; and (ii) at least one secondary chain extender is present and selected from 2-methyl-1,5-pentanediamine and 1,2-propanediamine.
4. The method of claim 3 wherein: (i) the polyether glycol is polytetramethyleneether glycol having a number average molecular weight of about 1800; (ii) the diisocyanate mixture comprises between about 83 and about 91 mole percent 4,4′-MDI and further comprises between about 9 and about 17 mole percent 2,4′-MDI and further comprises less than 1 mole percent 2,2′-MDI; (iii) the chain terminator is diethylamine; and (iv) the solvent is N,N-dimethylacetamide.
5. A polyurethaneurea polymer formed by the reaction of:
(a) at least one polymeric glycol selected from the group consisting of polyether glycols and polyester glycols;
(b) a diisocyanate mixture comprising at least about 78 mole percent 4,4′-MDI and at least about 5 mole percent 2,4′-MDI; wherein the molar ratio of the at least one glycol to the total moles of diisocyanate is between about 1:1.5 and about 1:2; and
(c) a composition comprising:
(1) at least one chain extender comprising ethylenediamine or a mixture of chain extenders comprising ethylenediamine and a secondary chain extender; wherein ethylenediamine is at least about 90 mole percent of the total moles of chain extenders;
and (2) a chain terminator selected from the group consisting of diethylamine, diisopropylamine, piperidine, dibutylamine, and mixtures thereof;
wherein the resulting polyurethaneurea polymer has a pre-spun IV between about 0.65 and about 1.0 dl/g and a primary amine content between about 25 and about 70 meq/Kg.
6. The polyurethaneurea polymer of claim 5 wherein: (i) the polymeric glycol is a polyether glycol having a number average molecular weight between about 1600 and about 2500; (ii) the molar ratio of the at least one glycol to the total moles of diisocyanate is between about 1:1.6 and about 1:1.8; and (iii) the diisocyanate mixture comprises between about 80 and about 95 mole percent 4,4′-MDI and further comprises between about 5 and about 20 mole percent 2,4′-MDI.
7. The polyurethaneurea polymer of claim 6 wherein: (i) the polyether glycol has a number average molecular weight between about 1800 and about 2000 and is selected from the group consisting of polyethyleneether glycol, polytrimethyleneether glycol, polytetramethyleneether glycol, polytetramethylene-co-2-methyl-tetramethyleneether glycol, polytetramethylene-co-tetraethyleneether glycol, and mixtures thereof; (ii) at least one secondary chain extender is present and selected from 2-methyl-1,5-pentanediamine and 1,2-propanediamine.
8. The polyurethaneurea polymer of claim 7 wherein: (i) the polyether glycol is polytetramethyleneether glycol having a number average molecular weight of about 1800; (ii) the diisocyanate mixture comprises between about 83 and about 91 mole percent 4,4′-MDI and further comprises between about 9 and about 17 mole percent 2,4′-MDI and further comprises less than 1 mole percent 2,2′-MDI; and (iii) the chain terminator is diethylamine.
9. Spandex prepared from the polyurethaneurea polymer of claim 5 .