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...
Reexamination Certificate
1998-05-19
2001-08-21
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...
C528S079000, C528S906000, C428S364000
Reexamination Certificate
active
06277942
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel melt-spun elastomeric fibers and the preparation thereof. More particularly, the present invention relates to novel melt-spun elastomeric fibers which may be useful in the preparation of textile articles and which may be prepared from melt-spinnable elastomeric polymers.
BACKGROUND OF THE INVENTION
Elastomeric polymers, particularly polyurethane elastomers, are becoming increasingly important in commercial applications. Unlike many other thermoplastic and thermoset elastomers, a wide variety of raw materials may be employed in the preparation of polyurethane elastomers, thereby allowing the preparation of elastomers with physical properties geared to the intended application. Thus, there are a myriad of diverse applications for polyurethane elastomers including, for example, caulks and sealants, elastomeric fibers, viscoelastic and energy absorbing materials, and extrusion and injection moldable articles such as gears, automobile fascias, and ski boots.
Spandex is a particular elastomeric polymer in fiber form which is a well-known component of clothing, particularly sportswear, which adds stretch to the clothing. Spandex is a urethane-containing polymer composed of alternating soft and hard regions within the polymer structure. Generally speaking, there are three methods for manufacturing fibers, including Spandex fibers, from polyurethane polymers: (1) dry-spinning; (2) wet-spinning, and (3) melt-spinning. Both dry-spinning and wet-spinning involve the use of organic solvents which, due to health, safety and environmental considerations, is preferably avoided. Melt-spinning is thus advantageous inasmuch as it does not involve the use of solvents.
Prior art polyurethanes are often prepared by the “one-shot” method. This method involves reacting together, at the same or about the same time, the various reaction components including, for example, polyol, diisocyanate compound and chain extender. The one-shot method often leads to polyurethanes, particularly polyurethanes in which the chain extender includes aromatic moieties, which typically contain higher melting material, i.e., material having melting points of, for example, about 225° C. or greater, including above about 235° C. The use of melt-spinning temperatures of greater than about 225° C. may therefore be required during melt-spinning of prior art polyurethanes. However, the polyurethanes themselves are generally thermally unstable at temperatures above about 225° C. Thus, the use of higher temperatures during melt-spinning may result in thermal decomposition of the polyurethane, whereas the use of lower melt-spinning temperatures may result in plugging or clogging by the higher melting material of the melt-spinning apparatus. Accordingly, polyurethanes generally cannot be melt-spun with the continuity required for commercial operations if they contain any higher melting material. As a consequence, polyurethanes generally must be dissolved in a solvent and either dry or wet spun into fibers which, as noted above, poses safety and environmental concerns.
In attempting to address the aforementioned problems with prior art polyurethanes, polyurethanes have also been prepared in which the involved chain extender is a compound which contains no aromatic moieties, i.e., an aliphatic compound. However, these polyurethanes are generally characterized by undesirable chemical and/or physical properties, including tackiness, low melting temperatures and low heat distortion temperatures. Products melt-spun from these polyurethanes are readily prone to melting or to becoming misshapen upon exposure to slightly elevated temperatures. To improve their heat resistance, prior art melt-spun polyurethanes have been crosslinked during and/or after the spinning process. Crosslinking in melt-spinning processes is generally undesirable in that it adds complexity and cost to the spinning methods. Unexamined Japanese application No. SHO 63(1988)-317238 describes an alternate crosslinking process in which unreacted ingredients are injected into the spin cell to complete the crosslinking reaction. This process is also undesirable in that it leaves the vam only partially cured as it is wound during spinning and it must be permitted to cure before rewinding and/or shipping.
Accordingly, new and/or better alternatives to prior art methods and elastomeric polymers for use in the manufacture of melt-spun fibers are needed. The present invention is directed to these as well as other important ends.
SUMMARY OF THE INVENTION
The present invention is directed generally to melt-spun fibers which may be useful in the preparation of textile articles. Specifically, in one embodiment, there is provided a melt-spun fiber which is prepared from a melt-spinnable elastomeric polymer having the formula:
[Pr−Ar]
n
(I)
wherein:
n is from about 30 to about 65;
Ar is a residue of an aromatic dihydroxy compound; and
Pr is a prepolymer which comprises:
from about 85 to about 95 mole % of a prepolymer component of formula T-G-T;
from about 3 to about 15 mole % of a prepolymer component of formula T-G-T-G-T; and
from 0 to about 2 mole % of a prepolymer component of formula T-G-T-G-T-G-T, wherein:
G is a residue of a polyol; and
T is a residue of a diisocyanate compound;
wherein in the preparation of the melt-spinnable elastomeric polymer, which preparation comprises combining together said polyol, said diisocyanate compound and said aromatic dihydroxy compound, said polyol and said diisocyanate compound are combined together in a mole ratio of about 1:2 to provide the melt-spinnable elastomeric polymer with substantially no higher melting polymeric component.
Another aspect of the invention relates to a fiber which is melt-spun from a melt-spinnable elastomeric polymer, wherein the melt-spinnable elastomeric polvmer comprises a diisocyanate-capped polyol prepolymer which is chain-extended with an aromatic dihydroxy compound, wherein in the preparation of said melt-spinnable elastomeric polymer, which preparation comprises combining together said polyol, said diisocyanate compound and said aromatic dihydroxy compound, said polyol and said diisocyanate compound are combined together in a mole ratio of about 1:2 to provide the melt-spinnable elastomeric polymer with substantially no higher melting polymeric component.
Yet another aspect of the invention relates to a method for the preparation of a melt-spun fiber comprising providing a melt-spinnable elastomeric polymer having the formula:
[Pr−Ar]
n
(I)
wherein:
n is from about 30 to about 65;
Ar is a residue of an aromatic dihydroxy compound; and
Pr is a prepolymer which comprises:
from about 85 to about 95 mole % of a prepolymer component of formula T-G-T;
from about 3 to about 15 mole % of a prepolymer component of formula T-G-T-G-T; and
from 0 to about 2 mole % of a prepolymer component of formula T-G-T-G-T-G-T, wherein:
G is a residue of a polyol; and
T is a residue of a diisocyanate compound; and
melt spinning said melt-spinnable elastomeric polymer; wherein said meltspinnable elastomeric polymer is prepared by a method which comprises combining together said polyol, said diisocyanate compound and said aromatic dihydroxy compound, wherein said polyol and said diisocyanate compound are combined together in a mole ratio of about 1:2 to provide the melt-spinnable elastomeric polymer with substantially no higher melting polymeric component.
Still another aspect of the invention relates to a method for the preparation of a melt-spun fiber comprising;
providing a melt-spinnable elastomeric polymer which comprises a diisocyanate-capped polyol prepolymer which is chain-extended with an aromatic dihydroxy compound, wherein said melt-spinnable elastomeric polymer is prepared by a method comprising combining together said polyol, said diisocyanate compound and said aromatic dihydroxy compound, wherein said polyol and said diisocyanate compound are combined together in a mole ratio of about 1:2 to provide said me
Gorr Rachel
Optimer, Inc.
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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