Stable polyurethaneurea solutions

Details Stable polyurethaneurea solutions Stable polyurethaneurea solutions

1999-09-01

2001-05-01

Sergent, Rabon (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...

C528S061000, C528S906000, C524S873000, C524S874000

Reexamination Certificate

active

06225435

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a viscosity-stable solution of polyurethaneureas and, more specifically, to such solutions without viscosity stabilizer additives.
2. Discussion of Background Art
Polyurethane solutions, generally dry-spun or wet-spun to make spandex, face a common problem of viscosity instability and gelation during storage prior to spinning. Such increases in viscosity can make the solution unusable for spinning into spandex and are, therefore, highly undesirable. U.S. Pat. No. 5,288,779 discloses the need for special additives to stabilize the solutions of polyurethaneureas, including those made from polyethers derived from tetrahydrofuran and 3-methyltetrahydro-furan, bis(4-isocyanatcocyclohexyl)methane, and ethylene diamine.
SUMMARY OF THE INVENTION
The composition of the present invention is a 30-40% by weight solids content viscosity-stable solution of polyurethaneurea in an inert organic solvent and in the substantial absence of a viscosity stabilizer wherein the polyurethaneurea is based on:
a polymeric glycol selected from the group consisting of poly(tetramethyleneether)glycol and poly(tetra-methyleneether-co-3-methyltetramethyleneether)glycol;
a diisocyanate selected from the group consisting of bis(4-isocyanatocyclohexyl)methane and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, present at a capping ratio in the range of about 1.5 to 3.0; and
ethylenediamine.
The invention also provides a spandex dry-spun from such solution.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
After the formation of a polyurethane (for example a polyurethaneurea) solution in a commercial process, the solution is often held in storage for a long time before being spun into spandex. In addition, any small zones of low-flow in the process equipment can also retain polymer solution for extended periods. During this time, solution viscosity can rise to levels which can cause the production of nonuniform fiber and interfere with spinning continuity. In more severe cases, gel formation can result, which can require frequent cleaning of equipment such as filters and spinnerets. Very little, if any, gel formation or crosslinking can be tolerated during spinning.
It has now been found surprisingly that solutions of the polyurethaneurea compositions of this invention have unexpectedly good solution viscosity stability in the substantial absence of viscosity stabilizing additives. The polyurethaneureas of this invention are prepared from poly(tetramethyleneether)glycol or poly(tetramethyleneether-co-3-methyltetramethylene-ether)glycol and bis(4-isocyanatocyclohexyl)methane or 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-cyclohexane (isophorone diisocyanate) and chain-extended with ethylenediamine. The number-average molecular weight of the macromolecular diol utilized is in the range of about 1000 to 5000 and preferably in the range of about 1500 to 3500.
The ratio of diisocyanate to macromolecular glycol (the “capping ratio”) is in the range of about 1.5 to 3.0, preferably in the range of about 1.5 to 2.5, and more preferably in the range of about 1.6 to 2.0. The capping ratio when poly(tetramethyleneether-co-3-methyltetramethyleneether)glycol is used is at the upper end of these ranges.
The chain extender used in the present invention is ethylene diamine. Use of other diamines results in polyurethaneurea solutions with unstable viscosities over time. Also, other diamine chain extenders, such as bis(4-aminocyclohexyl)methane, resulted in unsatisfactory polymer solution stability while 1,2-diaminopropane, 1,4-diaminobutane and/or 1,6-diaminohexane resulted in fibers with unacceptably low softening temperatures.
The number-average molecular weight of the polyurethaneurea polymers of the present invention is in the range of about 40,000 to 150,000 while the temperature of the high end of the melting range of the spandex made from the present solutions is in the range of about 200-250° C. in order to provide good thermal stability during processing.
Spandex prepared from the solutions of this invention has high elongation-at-break, good tenacity, low set, low stress decay, and excellent light stability. Elongation generally exceeds 300% and often exceeds 450%. The percent set is generally in the range of about 10-25% while the stress decay is generally in the range of about 15-30%. The &Dgr;b value (a measure of whiteness retention after environmental exposure) is 10 or less. After exposure to artificial sunshine, the retention of the elongation-at-break of the spandex made from the solutions of the present invention is generally at least 80% and usually at least 90%, and the tenacity retention is generally at least 50% and often at least 65%.
There are no particular restrictions on the denier or the cross-section of the fiber of the present invention.
The polymer solution of the present invention can contain pigments and various types of stabilizers, provided they do not adversely affect the solution stability. For example, hindered phenol-based anti-oxidant reagents such as 2,6-di-t-butyl-4-methylphenol and Sumylzer® GA-80 (Sumitomo Chemical, Tokyo, Japan); benztriazole and hindered amine-based stabilizers such as various types of Tinuvins (Ciba Geigy, Basle, Switzerland); phosphorus-based stabilizers such as Sumilyzer® P-16 (Sumitomo Chemical); inorganic pigments such as titanium oxide, zinc oxide and carbon black; metal soaps such as magnesium stearate; antibacterial agents such as silver, zinc and compounds thereof; odor inhibitors; silicone oil, mineral oil, and other lubricants; and various types of antistatic agents such as barium sulfate, cerium oxide, betaine and phosphoric acid-based compounds can also be included. In order to increase further the durability of the thread, particularly with respect to light stability and resistance to nitrogen oxides, nitrogen oxide trappers such as HN-150 (an aromatic hydrazide manufactured by Nippon Hydrazine, Chiyoda-ku, Tokyo, Japan), thermal oxidation stabilizers such as Sumilyzer GA-80 and light stabilizers such as Sumisorb® 300-622 (Sumitomo Chemical) can be utilized. There are no particular restrictions on the method of addition, and any common method such as static mixing can be used.
The solids content of polyurethaneurea solution of this invention is 30-40% by weight and the solution viscosity is in the range of about 1200-6500 Poise and preferably in the range of about 2000 to 6000 Poise to maintain spinning continuity and consistent spandex properties. These viscosities are generally fairly constant over a 10-day aging period at 40° C.
The following test methods were used:
The isocyanate content of the prepolymers was determined according to the method of S. Siggia, “Quantitative Organic Analysis via Functional Group”, 3rd Edition, Wiley & Sons, New York, pages 559-561 (1963).
The strength and elastic properties of the spandex were measured in accordance with the general method of ASTM D 2731-72. Using an Instron Model 4502 tensile tester at 21° C. and 65% relative humidity, three filaments, a 2-inch (5-cm) gauge length and a zero-to 300% elongation cycle were used for each of the measurements. The samples were cycled five times at a constant elongation rate of 50 centimeters per minute. The percent set (“% S”) was then calculated as
%
S=
100(
Lf−Lo
)
/Lo,
where Lo and Lf are, respectively, the filament (yarn) length when held straight without tension before and after the five elongation/relaxation cycles. Percent elongation at break and tenacity were measured on a sixth extension cycle.
To measure stress decay, the filament was held at 300% extension for 30 seconds on the fifth extension. At the end of 30 seconds, the stress was recorded, and initial and final stress were used to determine stress decay:
stress decay (%)=(
Si−Sf
)×100/
Si
where
Si=initial stress at 300% extension
Sf=final stress at 300% extension after 30 second hold at 300% extension on the fifth cycle.
Using a Scott Controlled Atmosphere test

Affiliated with

Also associated with

Rating

Stable polyurethaneurea solutions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Stable polyurethaneurea solutions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stable polyurethaneurea solutions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2569788