Spandex having low set at low temperatures

Details Spandex having low set at low temperatures Spandex having low set at low temperatures

2002-05-31

2003-10-28

Gorr, Rachel (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

C528S064000, C528S065000, C528S076000, C528S079000, C528S906000

Reexamination Certificate

active

06639041

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to spandex comprising a polyurethane based on copoly(alkylene ethers) comprising tetramethylene ether and either ethylene ether or 1,2-propylene ether moieties in certain proportions.
2. Discussion of Background Art
Spandex can be prepared from a variety of polymeric glycols, diisocyanates, and difunctional chain extenders. The polymeric glycols used can be copolyethers, as disclosed in European Patent EP158,229 and EP004,356 and U.S. Pat. Nos. 4,224,432 and 4,658,065. However, spandex made from such copolyether glycols has an unsatisfactory combination of high set at low temperatures when unload power is adequate or low unload power when set is low, and improvements are still needed. Copolyethers are also disclosed in U.S. Pat. No. 3,425,999 and Japanese Patent Applications JP01-098624 and JP62-101622, but their use in making fibers is unknown.
SUMMARY OF THE INVENTION
The spandex of the present invention comprises a polyurethane reaction product of:
(A) a copoly(alkylene ether) glycol selected from the group consisting of poly(tetramethylene-co-ethylene ether) glycols wherein the ethylene ether moiety is present at about 15-37 mole % and poly(tetramethylene-co-1,2-propyleneether) glycols wherein the 1,2-propylene ether moiety is present at about 15-30 mole %, based on total alkylene ether moieties;
(B) a diisocyanate; and
(C) a chain extender selected from the group consisting of diamines and diols.
The process of the present invention comprises the steps of:
(A) contacting a copoly(alkylene ether) glycol selected from the group consisting of poly(tetramethylene-co-ethylene ether) glycols wherein the ethylene ether moiety is present at about 15-37 mole % and poly(tetramethylene-co-1,2-propyleneether) glycols wherein the 1,2-propylene ether moiety is present at about 15-30 mole %, based on total alkylene ether moieties with a diisocyanate to form a capped glycol;
(B) dissolving the capped glycol in a solvent;
(C) contacting the solution of the capped glycol formed in step (B) with a chain extender selected from the group consisting of diamines and diols to form a polyurethane spinning solution; and
(D) spinning the solution formed in step (C) to form the spandex.
DETAILED DESCRIPTION OF THE INVENTION
It has now been found that spandex comprising polyurethanes derived from certain copoly(alkylene ether) glycols has a surprisingly good combination of high unload power (especially at low extensions) and low set (including at low temperatures, an advantage when fabrics comprising the spandex are used in winter) while retaining high elongation and heat-set efficiency.
As used herein, ‘spandex’ has its customary definition: a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer comprised of at least 85% by weight of a segmented polyurethane.
Fabrics are generally worn at relatively low elongations. Therefore, unload power at low fiber elongations (for example 30% and 60%) is important in uses such as tricot knits. When the spandex unload power is too low, the fabric knit from it has little or no sensible recovery power or restraining force. Similarly, low set is important so that after stretching the fabric can return to its intended dimensions without permanent distortion. The spandex of the invention can have an unload power at 30% elongation of at least 0.006 dN/tex, an unload power at 60% elongation of at least 0.012 dN/tex, and a set at −5° C. of not more than about 26%, the unload powers being measured after five 0-200% stretch and relax cycles, and the set being measured after five 0-300% stretch and relax cycles. It has now been found that when the amount of ethylene ether or 1,2-propylene ether moiety in the copoly(alkylene ether) glycol used in making the present spandex is too high, unload power at low elongations is unacceptably low, and set rises. When such ether moiety content is too low, it has little effect, and the set at low temperatures rises.
The copoly(alkylene ether) glycol can be a random copolyether, can be obtained by copolymerization of such a random copolyether with another polymeric glycol, or can be a mixture of such a random copolyether with another polymeric glycol. The copoly(alkylene ether) glycol used in the spandex of the invention can have a number-average molecular weight of about 1300-4500, more typically about 2000-3500.
Diisocyanates useful in making the polyurethane of which the present spandex is comprised include 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene, 1-isocyanato-2-[(4-isocyanato-phenyl)methyl]benzene, 1,1′-methylenebis(4-isocyanatocyclohexane), 4-methyl-1,3-phenylene-diisocyanate, and combinations thereof. 1-isocyanato4-[(4-isocyanato-phenyl)methyl]benzene (“MDI”) and mixtures thereof with 1-isocyanato-2-[(4-isocyanato-phenyl)methyl]benzene are preferred because of their ready commercial availability. The mole ratio of the diisocyanate(s) to the copoly(alkylene ether) glycol can be about 1.2-2.3.
Diol chain extenders useful in making the polyurethane used in the spandex of the invention include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,2-propylene glycol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-trimethylenediol, 2,2,4-trimethyl-1,5-pentanediol, 2-methyl-2-ethyl-1,3-propanediol, 1,4-bis(hydroxyethoxy)benzene, bis(hydroxyethylene) terephthalate, and mixtures thereof.
Use can be made of one, or a mixture of two or more, amine catalyst or organic metal catalyst in the preparation of the polyurethane. Illustrative examples of suitable amine catalysts include N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N,N′,N′-tetramethylethylenediamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, N,N,N′,N′-tetramethylhexanediamine, bis-2-dimethylaminoethyl ether, N,N,N′,N′,N′-pentamethyldiethylenetriamine, tetramethylguanidine, triethylenediamine, N,N′-dimethylpiperazine, N-methyl-N′-dimethylaminoethylpiperazine, N-(2-dimethylaminoethyl)morpholine, 1-methylimidazole, 1,2-dimethylimidazole, N,N-dimethylaminoethanol, N,N,N′-trimethylaminoethyl ethanolamine, N-methyl-N′-(2-hydroxyethyl)piperazine, 2,4,6-tris(dimethyl-aminomethyl)phenol, N,N-dimethylaminohexanol and triethanolamine. Suitable examples of organic metal catalysts include tin octanoate, dibutyltin dilaurate and dibutyllead octanoate.
Diamine chain extenders that can be used when a polyurethaneurea is desired as the fiber-forming substance of the spandex include hydrazine, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 2-methyl-1,5-pentanediamine, 1,2-diaminobutane, 1,3-diaminobutane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 2,2-dimethyl-1,3-diaminopropane, 1,3-diamino-2,2-dimethylbutane, 2,4-diamino-1-methylcyclohexane, 1,3-pentanediamine, hexamethylenediamine, 1,3-cyclohexanediamine, bis(4-aminophenyl)phosphine oxide, and mixtures thereof.
To control polyurethane molecular weight and the viscosity of a polyurethane spinning solution, a chain terminator such as n-butanol, diethylamine, cyclohexylamine, or n-hexylamine can be used, generally as a mixture with the chain extender. Small amounts of trifunctional materials such as diethylenetriamine and glycerol can also be used for polymer solution viscosity control.
Either melt polymerization or solution polymerization can be used. In the process of the invention solution polymerization is preferred for less thermal degradation of the polyurethane, especially when a polyurethaneurea is being prepared, since polyurethaneureas are generally too high melting to be prepared by melt polymerization. Useful solution polymerization methods include a “one-shot” method, in which each of the starting materials can be added to the solvent and dissolved and then heated to a suitable temperature and reacted so as to form the polyurethane, and a “prepolymer me

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