Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-07-26
2001-05-15
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S211000, C524S212000
Reexamination Certificate
active
06232374
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to spandex having low tackiness and, more particularly, to spandex having dispersed therein effective amounts of an anti-tack additive.
2. Description of the Background Art
Spandex is known to be tacky. This is especially important in wound packages of dry-spun spandex, where the pressure can be very high due to “package relaxation”, which is the recovery of the filament from the stretch it experiences during spinning. The high pressure can make it especially difficult to remove and use filament near the core of the package, where conditions are most extreme. Time and temperature contribute to tackiness, so that wound packages of spandex that have been stored, for example for months, experience significantly more core waste than freshly spun and wound packages. Reducing the tackiness and the resulting waste would improve the economics of spandex filament production. Steps taken to reduce tack, however, should not interfere with the continuity of the dry-spinning process by which spandex is made.
U.S. Pat. No. 4,296,174 discloses the incorporation of metal salts of fatty acids such as calcium stearate into dry-spun spandex to reduce the tackiness of the spandex. However, such additives are problematic in the dry-spinning process, creating deposits within the spinneret capillaries and plugging filters in the polymer solution lines. These effects are detrimental to spinning continuity, i.e. when the capillaries or filters become plugged, the continuous filament production is interrupted and the process must be stopped to clean out the plugging deposits or replace the plugged parts with clean ones. An anti-tack additive with a combination of good dry-spinning processibility and anti-tack characteristics is still desired.
Japanese Patent Application Publication Number 1-298259 (“JP '259”) discloses a method for producing thermoplastic polyurethane elastic nonwoven fabric by melt-extruding and melt-blowing thermoplastic polyurethane which has been blended with 0.1-2.0 wt % of a compound represented by the formula:
(C
n
H
2n+1
)
m
X
wherein n is 15 to 35; m is 1 to 3; and X is a fatty acid ester having 5 or less carbons, a fatty amide having 5 or less carbons, or a fatty acid ester having 5 or less carbons that includes a calcium salt. In this method, the thermoplastic resin is melt-spun and simultaneously powerfully impacted by a high-temperature, high-speed gas discharged from adjoining gas jets which blasts apart the melt-spun fibers into ultrafine fibers which are then collected on a moving plate thereby giving a nonwoven sheet. The sheet can be unrolled after having been rolled up. In the Description of the Prior Art, JP '259 teaches the undesirability of polyurethane elastic fiber production by dry spinning, as disclosed in Japanese Patent Application Publication No. 52-81,177. An anti-tack additive for dry-spun polyurethane fiber is still desired.
U.S. Pat. No. 3,382,202 discloses an additive system to impart substantially non-blocking and non-tacky characteristics to formed polyurethane structures. The additive system consists essentially of (1) about 0.5 to 4.0 parts of certain amides and bis-amides derived from fatty acids, including ethylene bis-stearamide and stearamide, and (2) about 1 to 15 parts of a finely divided inert particulate solid such as diatomaceous earth, silica, talc, feldspar, mica, carbon black, calcium bicarbonate, or sodium bicarbonate. An anti-tack additive that does not require a second inert component is still desired.
SUMMARY OF THE INVENTION
The spandex of the present invention contains 0.1-5.0% by weight of the spandex of an anti-tack additive dispersed in the spandex wherein the additive is a compound of formula (I) or mixtures thereof:
R
1
—Z—R
2
(I)
wherein
each of R
1
and R
2
is independently selected from the group consisting of alkyl having 14 to 22 carbon atoms and alkenyl having 14 to 22 carbon atoms, and
Z is selected from the group consisting of
—C(O)—NH—R
3
—NH—C(O)—,
—NH—C(O)—NH—R
4
—NH—C(O)—NH—, and
—NH—C(O)—NH—,
wherein
R
3
is alkylene having 2 to 6 carbon atoms, and
R
4
contains an aromatic or a cycloaliphatic group and has 6 to 18 carbon atoms, each of the nitrogen atoms being bonded to a ring carbon in the R
4
moiety.
The process of the present invention for making spandex comprises the steps of:
preparing a polyurethane solution;
mixing into the solution 0.1-5.0% by weight of the spandex of an anti-tack additive of formula (I) or mixtures thereof; and
dry-spinning the solution to form spandex.
The spandex supply package of the present invention comprises a cylindrical core and spandex wound up on said core, wherein the spandex contains 0.1-5.0% by weight of the spandex of an anti-tack additive of formula (I) or mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTION
The following abbreviations are used herein:
EBS Ethylene bis-stearamide (N,N′-1,2-ethanediylbis-octadecanamide)
MDI 1,1′-Methylenebis(4-isocyanatobenzene)
PICM Bis (4-isocyanatocyclohexyl)methane
EDA Ethylenediamine
MPMD 2-Methyl-1,5-pentanediamine
DEA Diethylamine
As used herein, “spandex” means a dry-spun, manufactured fiber in which the fiber-forming substance is a long chain synthetic elastomer comprised of at least 85% by weight of a segmented polyurethane. Polyurethaneureas are a sub-class of such polyurethanes. Such spandex can be typically wound up on a cylindrical core, or tube, to form a supply package.
The polymers used to make the spandex of this invention can be generally prepared by capping a macromolecular glycol with a diisocyanate, dissolving the resulting capped glycol in a suitable solvent, and chain extending the capped glycol with a diamine, a diol or an aminoalcohol. Small amounts of monofunctional chain terminators such as dialkylamines can be added to control the molecular weight of the polymer.
Any organic diisocyanate can be used for the purposes of this invention, such as MDI, 2,4-tolylene diisocyanate, PICM, hexamethylene diisocyanate, 3,3,5-trimethyl-5-methylenecyclohexyl diisocyanate (isophorone diisocyanate), and the like. MDI is referred.
The macromolecular glycol can be selected from one or more of several types of such glycols. Polyether glycols suitable for use in the present invention include those derived from tetramethylene glycol, 3-methyl-1,5-pentane diol, tetrahydrofuran, 3-methyltetrahydrofuran, and the like, and copolymers thereof. Glycol-terminated polyesters which can be used in the conjunction with the present invention include the reaction products of ethylene glycol, tetramethylene glycol (butanediol), and/or 2,2-dimethyl-1,3-propane diol and the like with diacids such as adipic acid, succinic acid, dodecanedioic acid, and the like. Copolymers are also contemplated. Also contemplated as glycols for use in the present invention are polyetheresters comprised of elements of the above polyethers and polyesters, and diol-terminated polycarbonates such as poly(pentane-1,5-carbonate) diol, poly(hexane-1,6-carbonate) diol, and the like.
Completion of the formation of the polymer can be accomplished by dissolving the capped glycol in a suitable solvent and chain extending with diols or diamines to form polyurethanes or the sub-class known as polyurethaneureas, respectively. Solvents suitable include dimethylacetamide (DMAc), N-methylpyrrolidone, and dimethylformamide. DMAc is preferred. Suitable diol chain extenders include ethylene glycol, tetramethylene glycol, and the like. Diamines that can be used with the present invention include EDA, 1,3-cyclohexane diamine, 1,4-cyclohexane diamine, 1,3-propylene diamine, 2-methylpentamethylene diamine (MPMD), 1,2-propylene diamine, and the like, and mixtures thereof. Diamine chain extenders and the resulting polyurethaneureas are preferred. A small amount of a monoamine such as DEA can be mixed into the chain extender and reacted with the capped glycol in order to control the molecular weight of the final polyurethaneurea or polyurethane.
Following the preparation of
Karimi Iftekhar A.
Liu Hong
Lock Robert Lee
Sauer Bryan Benedict
Cain Edward J.
E. I. Du Pont de Nemours and Company
Frank George A.
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