Title of Invention

"POLYURETHANE ELASTOMERIC FIBER AND PROCESS FOR MAKING THE FIBER"

Abstract A thermoplastic polyurethane elastomer obtained by a bulk melt polymerization of: A. a polyurethane derived from a diisocyanate reacted with a hydroxyl terminated polyether intermediate and a glycol chain extender; wherein the amount of said chain extender is from 0.7 to less than 1.0 mole per mole of said hydroxyl terminated intermediate, and B. an isocyanate-terminated polyether additive, wherein said additive is capable of cross-linking said polyurethane in (A), wherein said polyether additive is terminated via reacting with diphenyl methane diisocyanate.
Full Text POLYURETHANE ELASTOMERIC FIBER AND
PROCESS FOR MAKING THE FIBER
Background of the Invention
The present invention relates to a polyurethane elastomeric fiber made by melt
spinning a urethane having a rebound of 60% or higher and a isocyanate-terminated
polyether or polyester to yield elastic fibers with low shrinkage, high heat resistance, low
tensile sets and high elongation. Polyurethanes having improved elastomeric properties
have many practical applications such as fabrics in consumer goods, such as hosiery and
clothing, medical applications, recreational applications, automotive applications, or
industrial applications, such as conveyor belting, cable jacketing, and the like.
A common elastic fiber used in the clothing industry is spandex. It is a
stretchable fiber with a high elastic recovery. Spandex is used in many commercial
yarns and fabrics to add elasticity to the clothing.
Spandex is defined by the Federal Trade Commission as a long-chain synthetic
polymer comprising at least 85% of a segmented polyurethane. It is made by reacting a
high molecular weight dihydroxy compound with an organic diisocyanate and chain
extender to form an elastomer polymer. It is segmented because it is composed of
alternating soft and hard regions within the polymer structure. The hard segments act as
physical cross-links that tie the polymer chains together. The soft segments of the
polymer chains are composed of polymers containing long, coiled, segments that can
orient upon stretching the material. The cross-links prevent the polymer chains from
moving significantly past each other. After stretching, the linear soft segments recover
to a coiled form so that the fiber returns to its original shape.
It is preferably made by a dry spun process, although wet spinning and melt
spinning processes are known. Du Pont first introduced spandex elastic
polyurethane(urea) fiber in 1959, using a dry-spinning method. In 1937 Bayer
introduced polyurethane elastic fiber made by a melt spinning method.
The dry spinning method is a process in which a long chain diol is reacted with
aromatic diisocyanate (usually 4,4'-methylene diphenyldiisocyanate, 1VIDI) to produce an
isocyanate-terminated prepolymer. Chain extension is accomplished by reacting the
prepolymer with diamine in the presence of a polar solvent to prepare spinning dope.
The dope is then extruded from the nozzle in multi-filament form. The solvent is
evaporated by coming in contact with hot air or hot N2 in the spinning column. The spun
yarn is then false-twisted, oil-treated and wound up on a bobbin. Dry spun fibers tend to
lose strength upon aging.
The melt-spinning method is different in that both prepolymer preparation and
chain-extension are conducted in the absence of solvent. To achieve a fiber with
properties comparable to those achieved by dry spinning, it is necessary to subject the
spun fiber to heat-aging treatment to promote cross-linking through the remaining
isocyanate group.
The melt spinning method for polyurethane thermoplastic elastomers developed
by Bayer in the late 1930s and early 1940s did not give satisfactory properties. Other
melt spinning processes for polyurethanes are known. U.S. Pat No. 3,503,933 disclosed
a melt spun spandex which used asymmetric diisocyanates which have a five-fold
difference in the reactivity of the two isocyanate groups. These diisocyanates resulted in
the spandex having poor processing qualities such as high tack, poor fabric qualities such
as low unload power, poor fabric processing properties in areas such as dyeing, finishing,
and laundering. U.S. Pat. No. 5,840,233 to Foss et al. teaches a process for making meltspun
elastomeric fibers from a melt-spinnable elastomeric polymer comprising a
diisocyanate-capped polyol prepolymer that is chain-extended with an aromatic
dihydroxy compound. The fibers produced can be knit or woven into textile articles,
such as hosiery or pantyhose.
U.S. Pat. No. 6,127,506, Green teaches a process for melt spinning spandex in
which a polyurethane(urea) polymer is prepared from a purified capped glycol, linear
aliphatic diamines and a monoamine chain terminator. During the process, the
diisocyanate is contacted with the polymeric glycols to yield a capped glycol. The
process in Green focuses on prepurifying the capped glycol prior to the formation of the
polyurethaneurea. The polymeric glycols used in the process include polyether glycols,
polyester glycols, polycarbonate glycols, and copolymers of the glycols. The
diisocyanate has substantially the same reactivities toward the hydroxyl groups as the
polymeric glycol. The preferred diisocyanate is MDI. In Green, the monomers are
polymerized and then melt spun to yield spandex or polyurethane(urea).
Traditionally, spandex has been prepared by either dry-spinning or wet-spinning.
Melt spinning is the most advantageous of the processes in terms of health, safety and
environmental concerns because it does not involve the use of organic solvents. But, the
dry-spun spandex produces a fiber having the best balance of properties compared to
those made by the other processes. Therefore, a fiber material with the properties of
spandex but which can be melt-spun instead of dry-spun is desirable. Although
thermoplastic polyurethanes generally have desirable properties with regard to abrasion
resistance, they do not generally exhibit properties such as high melting point, low
tensile set, low compression set, good rebound, and low hysteresis.
Polyether polyurethanes are known. For example, U.S. Pat. No. 5,959,059 to
Vedula et al. teaches a polyether urethane that has good physical properties when
prepared by the melt polymerization of a hydroxyl-terminated polyether intermediate,
containing alkylene oxide repeat groups of from 2 to 6 carbon atoms, and a chain
extender with a diisocyanate. Vedula et. al, used aromatic diisocyanates, with MDI being
preferred. Further, the thermoplastic polyether urethanes were produced by a "one-shot
process," where the hydroxyl terminated polyether intermediate, the chain extender, and
the diisocyanate were added together, mixed, and polymerized. Polyurethanes produced
by this "one-shot" method are polyurethanes in which the chain extender includes
aromatic moieties, having higher melting points. The resulting polyether urethanes
exhibited high melting points, from 170°C to 230°C, low densities, 1.10 or less, and
Shore D hardness of at least 15 or 20. Additionally, the polyether urethanes exhibited
good tear resistance, good abrasion resistance, and hydrolytic stability.
Melt spinning of polyurethane polymers is also known, including combining,
with the polyurethane polymer in the melt additional materials to achieve various
benefits. For example, Japanese Patent Publication JP58098421 (1983) (Yasuhiro et al.)
teaches adding a reaction product from a polyisocyanate and a blocking agent to a
polyurethane elastomer to produce an elastic yarn with high recovery from deformation
at high temperatures. The reaction in the Yasuhiro publication, is between a
polyisocyanate of 400 or more molecular weight, preferably p,p -diphenyl methane
diisocyanate (MDI) and polytetramethylene glycol on both terminals and a blocking
agent. Japanese patent publication 60048617 (2000) to Yamakawa et al., teaches melt
spinning butylene terephthalate-based crystalline polyester and thermoplastic
polyurethane to make an elastic fiber having a degree of luster of 70 or less. Japanese
patent publication No. JP1282387 (1989) to Yoshimoto et al. teaches an elastic
polyurethane yam produced by kneading a polyisocyanate prepolymer as a crosslinking
agent, where the yarn is subsequently treated with a mineral oil, polysiloxane, and
diamine mixture, to prevent the sticking of the fibers. Japanese patent publication No.
JP58186609 (1983) to Ogawa teaches fibers having improved heat resistance made by
adding a polyisocyanate compound and a pigment to a molten polyurethane elastomer.
Japanese patent publication No. JP57112409 (1982) to Ogawa et al. teaches an elastic
yarn of high recovery from the deformation at elevated temperature made by adding to a
molten polyurethane, a polyisocyanate reaction product having blocked NCO terminals
from a polyether of 300 to 2,500 molecular weight and diphenylmethane diisocyanate.
Summary of the Invention
This invention is the result of the discovery that a polyurethane elastomeric fiber
can be obtained by bulk melt spin polymerization of a polyurethane having a rebound of
60% or higher and a chain extending or cross-linking isocyanate-terminated polyether or
polyester additive. The polyurethane is preferably derived from a diisocyanate reacted
with a hydroxyl-terminated polyether and a glycol chain extender. The polyether
urethane preferably results from the polymerization of a hydroxyl terminated polyether
intermediate and a chain extender with a diisocyanate, where the hydroxyl terminated
polyether has alkylene oxide repeat units containing from 2 to 6 carbon atoms and has a
weight average molecular weight of at least 1,500. The chain extender is a substantially
non-branched glycol having 2 to 16 carbon atoms, and the amount of the chain extender
is from 0.7 to less than 1.0 mole per mole of hydroxyl terminated polyether.
In the present invention, the polyurethane polymer, when it is melt spun to
produce a fiber, is chain extended or cross-linked by incorporating the isocyanateterminated
pre-polymers. The resulting fiber has improved heat resistance and reduced
hysteresis loss, as compared to dry spun spandex, while still maintaining all the favorable
properties of dry-spun spandex.
Detailed Description of the Invention
This invention is directed to a polyurethane elastomeric fiber which can
be obtained by bulk melt spun polymerization of a polyurethane and a isocyanateterminated
polyether or polyester additive. The polyurethane is derived from a
diisocyanate reacted with a hydroxyl terminated polyether and a glycol chain extender.
The polyurethane used in this invention can be a polyether polyurethane or a
polyester polyurethane which has a rebound of 60% or higher. One polyurethane that
can be employed is a polyether polyurethane described in US Pat. No. 5,959,059 to Ravi
Vedula, the disclosure of which is incorporated by reference, although the present
invention is not limited to the polyether urethanes described in the Vedula Patent. For
example, U.S. Patent No. 3,016,364, to Muller, which is also incorporated by reference,
also teaches polyether urethanes which can be employed. A polyether urethane having
good physical properties can be prepared by melt polymerization of a hydroxylterminated
polyether intermediate and a chain extender with a diisocyanate. The
hydroxyl-terminated polyether has alkylene oxide repeat units containing from 2 to 6
carbon atoms and has a weight average molecular weight of at least 1,500. The chain
extender is a substantially non-branched glycol having 2 to 16 carbon atoms. The
amount of the chain extender is from 0.7 to less than 1.0 mole per mole of hydroxyl
terminated polyether. It is preferred that the polyether polyurethane have a melting point
of about 160°C or greater (e.g., 160°C to 230°C) with 175°C or greater being preferred,
although the softening point can be used to characterize the polyurethane. Further, it is
preferred that the urethane has a rebound of 60% or more with 65% or greater being
further preferred.
The additive is an isocyanate-terminated polyether or polyester additive, such as
isocyanate-capped polyol prepolymer, which is preferably chain-extended with an
aromatic dihydroxy compound. The term "isocyanate-terminated polyether or
polyurethane additive" refers generally to a prepolymer which comprises a polyol that
has been reacted with a diisocyanate compound (i.e., a compound containing at least two
isocyanate (— NCO) groups). In preferred form, the prepolymer has a functionality of
2.0 or greater, an average molecular weight of about 250 to 10,000, and is prepared so as
to contain substantially no unreacted monomeric isocyanate compound. The term
"unreacted isocyanate compound" refers to free monomeric isocyanate-containing
compound, i.e., diisocyanate compound which is employed as a starting material in
connection with the preparation of the prepolymer and which remains unreacted in the
prepolymer composition. The term "polyol" as used herein, generally refers to a
polymeric compound having more than one hydroxy (—OH) group, preferably an
aliphatic polymeric compound which is terminated at each end with a hydroxy group. A
wide variety of polyol compounds is available for use in the preparation of the
prepolymer. In preferred embodiments, the polyol may comprise a polymeric diol
including, for example, polyether diols and polyester diols and mixtures or copolymers
thereof. Preferred polymeric diols are polyether diols, with polyalkylene ether diols
being more preferred. Exemplary polyalkylene polyether diols include, for example,
polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol
(PTMEG) and polyhexamethylene ether glycol and mixtures or copolymers thereof.
Preferred among these polyalkylene ether diols is PTMEG. Preferred among the
polyester diols are, for example, polybutylene adipate glycol and polyethylene adipate
glycol and mixtures or copolymers thereof. Other polyol compounds, in addition to
those exemplified above, would be readily apparent to one of ordinary skill in the art,
once armed with the present disclosure.
The number average molecular weight of the polyols from which the prepolymers
may be derived may range from about 800 to about 3500 and all combinations and
subcombinations of ranges therein. More preferably, the number average molecular
weights of the polyol may range from about 1500 to about 2500, with number average
molecular weights of about 2000 being even more preferred.
The polyol in the prepolymers is capped with an isocyanate compound. A wide
variety of diisocyanate compounds is available for use in the preparation of the
prepolymers of the present invention. Generally speaking, the diisocyanate compound
may be aromatic or aliphatic, with aromatic diisocyanate compounds being preferred.
Examples of suitable aromatic diisocyanate compounds include diphenylmethane
diisocyanate, xylene diisocyanate, toluene diisocyanate, phenylene diisocyanate, and
naphthalene diisocyanate and mixtures thereof. Examples of suitable aliphatic
diisocyanate compounds include dicyclohexylmethane diisocyanate and hexamethylene
diisocyanate and mixtures thereof. Preferred among the diisocyanate compounds is MDI
due, at least in part, to its general commercial availability and high degree of safety, as
well as its generally desirable reactivity with chain extenders (discussed more fully
hereinafter). Other diisocyanate compounds, in addition to those exemplified above,
would be readily apparent to one of ordinary skill in the art, once armed with the present
disclosure.
A preferred additive is diphenyl methane diisocyanate-terminated poly ether
prepolymer or diphenylmethane diisocyanate-terminated polyester prepolymer. These
are polyether or polyester glycols where the hydroxyl groups are converted to isocyanate
groups to provide the isocyanate termination. The former composition is available from
Hyperlast Limited, UK, as Hyperlast® 5130, while the latter composition also is
available from Hyperlast® Limited, as Diprane® 5128, which is derived from functional
ethylene adipate and MDI, and Diprane® 5184, which is derived from butylene/hexylene
adipate and MDI. The preferred additive is Hyperlast® 5130, which is a diphenyl
methane diisocyanate-terminated polyether prepolymer derived from poly
(tetramethylene ether) glycol having a MW of about 2000, and MDI.
The fiber is made by melt spinning the polyether urethane and the additve. Melt
spinning is a well known process in which a polymer is melted by extrusion, passed
through a spinning nozzle into air, solidified by cooling, and collected by winding the
fibers on a collection device. Typically the fibers are melt spun at a polymer temperature
of about 150°C to about 300°C.
The invention can best be understood by reference to the following examples, in
which the invention is presented in greater detail. The examples are not, however, to be
construed to limit the invention herein in any manner, the scope of which is defined in
the appended claims.
The properties of the fibers made in accordance with the present invention can be
exemplified by comparing their performance with a Lycra® spandex fibers (from E.I.
duPont), which are commercially available and made by a dry spinning process. The
fibers in accordance with the present inventions were made by feeding Estane® 58280
polyether polyurethane, which has a melting point in the range of about 170°C to about
230°C (available from the The BF Goodrich Company) and Hyperlast® diphenyl
8
methane diisocyanate-terminated polyether cross-linking in the relative amounts
indicated below, additive through an extruder under 12 MPa pressure, at a screw speed
of 20 to 22 rpm, and a polymer temperature of 219°C to react the polyurethane and the
cross-linker, and subsequently passing the molten polymer to a melt spinning apparatus,
operated at 195°C. The resulting fiber is cooled and recovered, and subjected to physical
evaluation. The results of the evaluation are shown in Table I.
(Table Removed) Table I demonstrates the difference in performance between Lycra®, the
polyurethane, the polyurethane with 10% of the cross-linker Hyperlast 5130, and the
polyurethane with 15% of the cross-linker Hyperlast 5130. As Table I shows, when the
polymer is chain extended and to some extent cross-linked by incorporating a
isocyanate-terminated pre-polymer, such as Hyperlast 5130, the heat resistance is further
improved.
Hysteresis is a measure of the energy loss during stretching and retraction of an
elastic material. This energy loss translates into a loss of the fiber's elasticity. A large
energy loss means an increase in heat generation and consequently an increase in
discomfort. Table I shows that the addition of 15% Hyperlast can significantly reduce
the hysteresis as compared to Lycra®.
Additional comparisons between Lycra® spandex and Estane® 58280
polyurethane, with and without Hyperlast® 5130 are presented in Tables II and III.
(Table Removed)As can be seen from Tables II and III, the melt spun fibers, made from
polyurethane and a diisocyanate-terminated polyether additive, had heat set data
recovery, and tenacity (tensile strength), comparable to Lycra® spandex.
The foregoing embodiments of the present invention have been presented for the
purposes of illustration and description. These descriptions and embodiments are not
intended to be exhaustive or to limit the invention to the precise form disclosed, and
obviously many modifications and variations are possible in light of the above
disclosure. The embodiments were chosen and described in order to best explain the
principle of the invention and its practical applications to thereby enable others skilled in
the art to best utilize the invention in its various embodiments and with various
modifications as are suited to the particular use contemplated. It is intended that the
invention be defined by the following claims.











We Claim:
1. A thermoplastic polyurethane elastomer obtained by a bulk melt polymerization of:
A. a polyurethane derived from a diisocyanate reacted with a hydroxyl
terminated polyether intermediate and a glycol chain extender; wherein the
amount of said chain extender is from 0.7 to less than 1.0 mole per mole of said
hydroxyl terminated intermediate, and
B. an isocyanate-terminated polyether additive, wherein said additive is
capable of cross-linking said polyurethane in (A), wherein said polyether additive
is terminated via reacting with diphenyl methane diisocyanate.
2. The elastomer as claimed in claim 1, wherein said hydroxyl terminated polyether
has alkylene oxide repeat units containing from 2 to 6 carbon atoms and has a
weight average molecular weight of at least 1,500,
- said chain extender is substantially non-branched glycol having from 2 to 16 carbon atoms,
- the amount of said chain extender is from 0.7 to less than 1.0 mole per mole of said hydroxyl terminated polyether, and
- the polyurethane in (A) has a rebound of at least 60 percent when measured in accordance with ASTM D2632.
3. The elastomer as claimed in claim 1, wherein the polyurethane in (A) has a
melting point of 160°C to 230°C.
4. The elastomer as claimed in claim 1, wherein the polyurethane in (A) has a rebound of 60% to 100%, when measured in accordance with ASTM D2632.
5. The elastomer as claimed in claim 1, wherein the polyurethane in (A) has a rebound of 65% to 100%, when measured in accordance with ASTM D2632.
6. The elastomer as claimed in claim 1, wherein said isocyanate-terminated polyether in (B) has a molecular weight of from 250 to 10,000 and a functionality of 2.0 or greater.
7. A method for the preparation of a melt-spun fiber comprising a melt-spinnable thermoplastic polyurethane elastomer composition as claimed in claim 2, said elastomer composition comprising:
A. a polyether urethane derived from a diisocyanate reacted with a hydroxyl terminated polyether intermediate and a glycol chain extender,
- said hydroxyl terminated polyether intermediate having alkylene oxide repeat units containing from 2 to 6 carbon atoms and having a weight average molecular weight of at least 1,500,
- said chain extender being a substantially non-branched glycol having from 2 to 16 carbon atoms.
- wherein the amount of said chain extender is from 0.7 to less than 1.0 mole of said hydroxyl terminated polyether intermediate and wherein said polyether urethane has a rebound of at least 60% when measured in accordance with ASTM D2632; and
B. a diphenyl methane dusocyanate-terminated polyether additive, wherein said additive is capable of cross linking said polyether urethane in (A); and melt spinning said elastomer composition at a polymer temperature of between 150°C and 300°C to provide a fiber.
8. An elastic fiber obtainable by melt spinning the thermoplastic polyurethane elastomer of any claims 1 to 6, wherein said fiber has a percent elongation and break of between 300 and 700 percent, and shrinkage of less than 10 percent, at 100°C in water for 30 minutes, and weight average molecular weight of between 300,000 and 500,000, and a recovery, at 30 minutes, 130°C, and 200% elongation, of more than 70 percent.

Documents:

01260-delnp-2003-abstract.pdf

01260-delnp-2003-claims.pdf

01260-delnp-2003-correspondence-others.pdf

01260-delnp-2003-description (complete).pdf

01260-delnp-2003-form-1.pdf

01260-delnp-2003-form-18.pdf

01260-delnp-2003-form-2.pdf

01260-delnp-2003-form-5.pdf

01260-delnp-2003-form-6.pdf

01260-delnp-2003-pct-105.pdf

01260-delnp-2003-pct-210.pdf

01260-delnp-2003-pct-220.pdf

01260-delnp-2003-pct-304.pdf

01260-delnp-2003-pct-401.pdf

01260-delnp-2003-pct-409.pdf

01260-delnp-2003-pct-416.pdf

01260-delnp-2003-pct-gpa.pdf

1260-DELNP-2003-Abstract (21-10-2009).pdf

1260-DELNP-2003-Claims (21-10-2009).pdf

1260-DELNP-2003-Claims-(15-02-2010).pdf

1260-DELNP-2003-Correspondence-Others (15-02-2010).pdf

1260-DELNP-2003-Correspondence-Others (21-10-2009).pdf

1260-DELNP-2003-Correspondence-Others- (03-03-2010).pdf

1260-DELNP-2003-Correspondence-Others-(03-03-2010).pdf

1260-DELNP-2003-Description (Complete) (21-10-2009).pdf

1260-DELNP-2003-Form-2 (21-10-2009).pdf

1260-DELNP-2003-Form-3 (21-10-2009).pdf

1260-DELNP-2003-Form-3-(15-02-2010).pdf

1260-DELNP-2003-GPA (21-10-2009).pdf

1260-DELNP-2003-Petition-137 (21-10-2009).pdf

1260-DELNP-2003-Petition-138 (21-10-2009).pdf


Patent Number 242239
Indian Patent Application Number 01260/DELNP/2003
PG Journal Number 35/2010
Publication Date 27-Aug-2010
Grant Date 19-Aug-2010
Date of Filing 08-Aug-2003
Name of Patentee LUBRIZOL ADVANCED MATERIALS ,INC
Applicant Address 9911 BRECKSVILLE ROAD, CLEVELAND, OHIO 44141-3247, U.S.A.
Inventors:
# Inventor's Name Inventor's Address
1 RAVI RAM VEDULA 34936 CLEAR CREEK DRIVE, NORTH RIDGEVILLE, OHIO 44039, U.S.A.
PCT International Classification Number C08L 75/04
PCT International Application Number PCT/US02/03477
PCT International Filing date 2002-02-05
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/792,604 2001-02-23 U.S.A.