WO2025042846A1

WO2025042846A1 - Recyclable and recycled spandex fibers and method of manufacturing

Info

Publication number: WO2025042846A1
Application number: PCT/US2024/042950
Authority: WO
Inventors: Hong Liu; Matthew W SPENCER; Steven Wayne Smith; Enkhjargal TSOGTGEREL; David L. GODSHALL; Elizabeth Mei Zhen KIRKWOOD; Alberto CERIA
Original assignee: Lycra Co LLC
Current assignee: Lycra Co LLC
Priority date: 2023-08-18
Filing date: 2024-08-19
Publication date: 2025-02-27
Anticipated expiration: 2026-02-18

Abstract

Included are elastic fibers prepared by a solution-spinning process including a recycled segmented polyurethane, such as post-consumer spandex, also known as elastane fiber. The spandex includes a branched aliphatic diamine chain extender.

Description

Recyclable and Recycled Spandex Fibers and Method of Manufacturing

Background of the Invention

Field of the Invention

Included are elastic fibers prepared by a solution-spinning process including a recycled segmented polyurethane, such as post-consumer spandex, also known as elastane liber.

Description of the Related Art

Elastic fibers such as spandex (also known as elastane) are used today in a wide variety of products. Examples include hosieiy, swimwear, clothing, hygiene products such as diapers, among many others. The polyurethane compositions that are used to prepare spandex fibers have some limitations that have led to modifications such as including additives or altering the polymer composition to prevent degradation and to enhance dyeability, among many others. These elastic fibers are currently prepared from non-renewable resources.

W02013032408A1 discloses a method of recycling polyamide fibers including polyamide 6 and polyamide 6.6, from elastomeric fabrics comprising polyamide and spandex. In this process, the spandex fibers are removed from the fabrics by thermal degradations in an autoclave at high temperatures followed with solvent washing, and the degraded spandex polymer cannot be used for re-spinning back into fibers. WO 2021165531A2 also discloses a method to extract elastane fiber from mixed fabrics at an elevated temperature >100 °C (typically in in the range of 140°C to 200°C) using cyrene or 2,5-dimethyl isosorbide as solvent in a first step and are washed with a further solvent in a second step.

Summary of the Invention

Separating spandex fibers from finished fabrics or garments is a challenge, and more difficult is achieving the separation without substantial degradation of the segmented polyurethanes in a recycling process. As a result, the recovered polyurethanes are not suitable to be used for re-spinning into spandex fibers. A further challenge is to control the polymer molecular weight changes of the segmented polyurethane throughout fiber processing, garment preparation and garment utilization, As a result, the recovered polyurethanes are not suitable to be used for re-spinning into spandex fibers.

The recycled polyurethanes under prior treatments also suffer significant degradations, which are not suitable for re-spinning into fibers without deteriorated properties. Therefore, a new spandex fiber is needed which can be recycled under relatively mild thermal conditions (<100°C) without substantial degradations of the polymer and is capable of re-spinning back into fibers with acceptable properties.

Additionally, the recovered spandex polymers after separating from the fabrics or garments, if in a solid form, are required to be re-dissolved back into a solvent such as DMAc from which it is originally spun. The recycled polymer from incumbent spandex fibers on the market cannot be re-dissolved without the use of excessive heat, typically by high temperatures at >100°C. The resulted polymer solutions either have substantially degraded polymers, or reduced solution viscosity, or reduced polymer solids, not suitable to be re-spun back into fibers at high recycled polymer contents (typically <50%) or with desired fiber denier and properties as the original spandex fibers. Therefore, a new spandex fiber with modified chemistry is needed so that the recovered polymer from a recycling process can be readily re-dissolved into DMAc without degradations, and yet to achieve a polymer solution with solids and viscosity compatible to the existing spinning processes and further to have the fiber the deniers and properties comparable to the original spandex fibers.

Detailed Description of the Invention

The present invention covers a dry-spun spandex fiber based on a segmented polyurethaneurea capable of post-consumer recycling to complete the fiber circularity, including separating from the hard yams in the fabrics, redissolving or concentrating and re- spinning the polymer back into fibers, without significant degradations of the polymer. The recycled polymer, when re-dissolved or concentrated in a polar aprotic organic solvent such as N,N-dimethylacetamide (DMAc), provides a solution with a viscosity of 2500 to 6500 poises at 40°C within a solids range of 30 to 40% by weight. Additionally, the recycled polymer content, when re-spun into fibers, occupies at least 50%, preferably 100%, by weight of the total polymer content in the re-spun or recycled spandex fibers.

With extensive experiments, it was found that certain segmented polyurethanes with selected urea hard segment structures (such as predominantly branched ureas with branched aliphatic diamine chain extenders) are easier to be recycled than the incumbent commercial products in processes under mild conditions without severe degradations, and such polymers with controlled polymer molecular weight (by the use of combined permanent and temporary chain terminators) can be re-dissolved into a solution of desired solids and viscosity for re- spinning into spandex fibers.

The spandex fibers from the present invention, based on a segmented polyurethaneurea with designed sequence structures and controlled polymer molecular weight, are to be recycled under mild processing conditions without substantial polymer degradations. The recycled polymer from post-consumer fabrics and garments can also be re-dissolved back into DMAc solvent for a solution with a viscosity of 2500 to 6500 poises at 40°C within a solids range of 30 to 40% by weight desired for re-spinning back into fibers with a recycled content >50% up to 100%. Additionally, the re-spun spandex fibers have the same deniers and comparable properties for the same applications as the original spandex fibers.

Definitions

As used herein, “solvent” refers to an organic solvent such as dimethylacetamide (DMAC), dimethylformamide (DMF) and N-methyl pyrrolidone.

The term “solution-spinning” as used herein includes the preparation of a fiber from a solution which can be either a wet-spun or dry-spun process, both of which are common techniques for fiber production. Post-consumer recyclable spandex fiber - a spandex fiber can be used in normal textile applications and is capable of recycling after the fiber knitting or weaving, heat-setting and dyeing/finishing, and cutting/ sewing up to finished garments.

Post-consumer recycled polymer - Segmented polyurethane polymer recovered in recycling processes after separating out from the companion fibers in fabrics or garments containing spandex fibers.

Recycled spandex fiber - Re-spun spandex fibers containing post-consumer recycled segmented polyurethanes with content large than 50% and ideally 100%.

In order to help insure suitability of the spandex fiber to yam processing, fabric manufacturing, and consumer satisfaction when contained in a garment, a number of additional properties can be adjusted. Spandex compositions are well-known in the art and may include may variations such as those disclosed in Monroe Couper. Handbook of Fiber Science and Technology: Volume III, High Technology Fibers Part A. Marcel Dekker, INC: 1985, pages 51-85. Some examples of those are listed here.

Spandex fiber may contain a delusterant such as TiO₂, or another other particle with at refractive index different from the base fiber polymer, at levels of 0.01-6% by weight. A lower level is also useful when a bright or lustrous look is desired. As the level is increased the surface friction of the yam may change which can impact friction at surfaces the fiber contacts during processing.

The fiber breaking strength as measured in grams of force to break per unit denier (tenacity in grams/ denier) may be adjusted as needed. An example includes from 0.7 to 1.2 grams/denier dependent on molecular weight and/or spinning conditions.

The denier of the fiber may be produced from 5-2000 based on the desired fabric construction. A spandex yam of denier 5-30 denier may have a filament count of between 1 and 5, and a yarn of denier 30-2000 may have a filament count from 2 to 200. The fiber may be used in fabrics of any sort (wovens, warp knits, or weft knits) in a content from 0.5% to 100% depending on the desired end use of the fabric.

The spandex yarn may be used alone or it may be plied, twisted, co-inserted, or mingled with any other yam such as those suitable for apparel end uses, as recognized by the FTC (Federal Trade Commission). This includes, but is not limited to, fibers made horn nylon, polyester, multi-component polyester or nylon, cotton, wool, jute, sisal, help, flax, bamboo, polypropylene, polyethylene, poly fluoro carbons, rayon, cellulosics of any kind, and acrylic fibers.

The spandex fiber may have a lubricant or finish applied to it during the manufacturing process to improve downstream processing of the fiber. The finish may be applied in a quantity of 0.5 to 10% by weight.

The spandex fiber may contain additives to adjust the initial color of the spandex or to prevent or mask the effects of yellowing after exposure to elements that can initiate polymer degradation such as chlorine, fumes, UV, NOx, or burnt gas. A spandex fiber may be made to have a “CIE” whiteness in the range of 40 to 160.

Polyurethaneurea and Polyurethane Compositions

Polyurethaneurea compositions useful for preparing fiber or long chain synthetic polymers that include at least 85% by weight of a segmented polyurethane. Typically, these include a polymeric glycol or polyol which is reacted with a diisocyanate to form an NCO -terminated prepolymer (a “capped glycol”), which is then dissolved in a suitable solvent, such as dimethylacetamide, dimethylformamide, or N-methylpynolidone, and then reacted with a difunctional chain extender. Polyurethanes are formed when the chain extenders are diols (and may be prepared without solvent). Polyurethaneureas, a sub-class of polyurethanes, are formed when the chain extenders are diamines. In the preparation of a polyurethaneurea polymer which can be spun into spandex, the glycols are extended by sequential reaction of the hydroxy end groups with diisocyanates and one or more diamines. In each case, the glycols must undergo chain extension to provide a polymer with the necessary properties, including viscosity. If desired, dibutyltin dilaurate, stannous octoate, mineral acids, tertiary amines such as triethylamine, N,N^Ldimethylpiperazine, and the like, and other known catalysts can be used to assist in the capping step.

Suitable polyol components (also referred to as polymeric glycols) include polyether glycols, polycarbonate glycols, and polyester glycols of number average molecular- weight of about 600 to about 3,500. Mixtures of two or more polyols or copolymers can be included. The polyol component desirably includes at least one polymer derived from a bio-derived 1,4- butanediol.

Examples of polyether polyols that can be used include those glycols with two or more hydroxy groups, from ring-opening polymerization and/or copolymerization of ethylene oxide, propylene oxide, trimethylene oxide, tetrahydrofuran, and 3 -methyltetrahydrofuran, or from condensation polymerization of a poly hydric alcohol, such as a diol or diol mixtures, with less than 12 carbon atoms in each molecule, such as ethylene glycol, 1,3-propanedioI, 1 ,4-butanediol, 1,5-pentanediol 1,6-hexanediol, neopentyl glycol, 3 -methyl- 1,5 -pentanediol, 1,7 -heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10 -decanediol and 1,12-dodecanediol. A linear, bifunctional polyether polyol is preferred, and a poly(tetramethylene ether) glycol of molecular weight of about 1,700 to about 2,100, such as Terathane® 1800 (INVISTA of Wichita, KS) with a functionality of 2, is one example of a specific suitable polyol. Co- polymers can include poly(tetramethylene-co-ethyleneether) glycol.

Examples of polyester polyols that can be used include those ester glycols with two or more hydroxy groups, produced by condensation polymerization of aliphatic polycarboxylic acids and polyols, or their mixtures, of low molecular’ weights with no more than 12 carbon atoms in each molecule. Examples of suitable polycarboxylic acids are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, and dodecanedicarboxylic acid. Examples of suitable polyols for preparing the polyester polyols are ethylene glycol, 1,3 -propanediol, 1 ,4-butanediol, 1,5- pentanediol 1,6-hexanediol, neopentyl glycol, 3-methyl-l,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10 -decanediol and 1,12-dodecanediol. A linear bifunctional polyester polyol with a melting temperature of about 5°C to about 50°C is an example of a specific polyester polyol.

Examples of polycarbonate polyols that can be used include those carbonate glycols with two or more hydroxy groups, produced by condensation polymerization of phosgene, chloro formic acid ester, dialkyl carbonate or diallyl carbonate and aliphatic polyols, or their mixtures, of low molecular weights with no more than 12 carbon atoms in each molecule. Examples of suitable polyols for preparing the polycarbonate polyols are diethylene glycol, 1,3 -propanediol, 1 ,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3- methyl- 1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol and 1,12-dodecanediol. A linear, bifunctional polycarbonate polyol with a melting temperature of about 5°C to about 5 CPC is an example of a specific polycarbonate polyol.

The diisocyanate component can also include a single diisocyanate or a mixture of different diisocyanate including an isomer mixture of diphenylmethane diisocyanate (MDI) containing 4,4 ’-methylene bis(phenyl isocyanate) and 2,4’- methylene bis(phenyl isocyanate). Any suitable aromatic or aliphatic diisocyanate can be included. Examples of diisocyanates that can be used include, but are not limited to, l-isocyanato-4-[(4- isocyanatophenyl)methyl]benzene, 1 -isocyanato-2-[(4-cyanatophenyl)methyl]benzene, bis(4- isocyanatocyclohexyl)methane, 5-isocyanato-l-(isocyanatomethyl)-l,3,3- trimethylcyclohexane, 1 ,3-diisocyanato-4-methyl-benzene, 2,2’-toluenediisocyanate, 2,4'- toluenediisocyanate, and mixtures thereof. Examples of specific polyisocyanate components include Mondur® ML (Bayer), Lupranate® MI (BASF), and Isonate® 50 O,P’ (Dow Chemical), and combinations thereof.

A chain extender may be either water or a diamine chain extender for a polyurethaneurea. The present invention will include at least one branched aliphatic diamine chain extender such as 1 ,2-propanediamine. Combinations of different chain extenders may be included depending on the desired properties of the polyurethaneurea and the resulting fiber. Examples of suitable diamine chain extenders include: hydrazine; 1,2-ethylenediamine; 1,4- butanediamine; 1 ,2-butanediamine; 1,3 -butanediamine; l,3-diamino-2,2-dimethylbutane; 1,6-hexamethylenediamine; 1,12-dodecanediamine; 1,2-propanediamine; 1,3- propanediamine; 2-methy 1-1, 5 -pentanediamine; l-amino-3,3,5-trimethyl-5- aminomethy Icy clohexane ; 2 ,4-diamino- 1 -methylcy cl ohexane; N -methy lamino-bis(3 - propylamine); 1 ,2-cyclohexanediamine; 1 ,4-cyclohexanediamine; 4,4 ’-methy lene- bis(cyclohexylamine); isophorone diamine; 2,2-dimethyl-l,3-propanediamine; meta- tetramethylxylenediamine; 1 ,3 -diamino-4-methyl cyclohexane; 1 ,3-cyclohexane-diamine;

1 , 1 -methylene-bis(4,4'-diaminohexane); 3 -aminomethyl-3 ,5,5-trimethylcyclohexane; 1,3- pentanediamine (1,3 -diaminopentane); m-xylylene diamine; and Jeffamine® (Texaco).

When a polyurethane is desired, the chain extender is a diol. Examples of such diols that may be used include, but are not limited to, ethylene glycol, 1,3-propanediol, 1,2-propylene glycol, 3 -methyl- 1,5 -pentanediol, 2,2-dimethyl-l,3-trimethylene diol, 2,2,4-trimethyl-l,5- pentanediol, 2-methyl-2-ethyl- 1,3-propanediol, l,4-bis(hydroxyethoxy)benzene, and 1,4- butanediol and mixtures thereof.

A blocking agent which is a monofunctional alcohol or a monofunctional dialkylamine may optionally be included to control the molecular weight of the polymer. Blends of one or more monofunctional alcohols with one or more dialkylamine may also be included.

Examples of monofunctional alcohols useful with the present invention include at least one member selected from the group consisting of aliphatic and cycloaliphatic primary and secondary alcohols with 1 to 18 carbons, phenol, substituted phenols, ethoxylated alkyl phenols and ethoxylated fatty alcohols with molecular weight less than about 750, including molecular weight less than 500, hydroxy amines, hydroxymethyl and hydroxy ethyl substituted tertiary amines, hydroxymethyl and hydroxyethyl substituted heterocyclic compounds, and combinations thereof, including furfuryl alcohol, tetrahydrofurfuryl alcohol, N-(2-hydroxy ethyl) succinimide, 4-(2-hydroxyethyl)moipholine, methanol, ethanol, butanol, neopentyl alcohol, hexanol, cyclohexanol, cyclohexanemethanol, benzyl alcohol, octanol, octadecanol, N,N-diethylhydroxylamine, 2-(diethylamino)ethanol, 2-dimethylaminoethanol, and 4-piperidineethanol, and combinations thereof.

Examples of suitable mono-functional dialkylamine blocking agents include: N,N- diethylamine, N-ethyl-N-propylamine, N,N-diisopropylamine, N-tert-butyl-N-methylamine, N-tert-butyl-N-benzylamine, N,N-dicyclohexylamine, N-ethyl-N-isopropylamine, N-tert- butyl-N-isopropylamine, N-isoprqpyl-N-cyclohexylamine, N-ethyl-N-cyclohexylamine, N,N-diethanolamine, and 2,2,6,6-tetramethylpiperidine.

Additives

Classes of additives that may be optionally included in polyurethaneurea compositions are listed below. An exemplary and non-limiting list is included. However, additional additives are well-known in the art Examples include: anti-oxidants, UV stabilizers, colorants, pigments, cross-linking agents, phase change materials (paraflin wax), antimicrobials, minerals (i.e., copper), microencapsulated additives (i.e., aloe vera, vitamin E gel, aloe vera, sea kelp, nicotine, caffeine, scents or aromas), nanoparticles (i.e., silica or carbon), nano-clay, calcium carbonate, talc, flame retardants, antitack additives, chlorine degradation resistant additives, vitamins, medicines, fragrances, electrically conductive additives, dyeability and/or dye-assist agents (such as quaternary ammonium salts). Other additives which may be added to the polyurethaneurea compositions include adhesion promoters, anti-static agents, anti-creep agents, optical brighteners, coalescing agents, electroconductive additives, luminescent additives, lubricants, organic and inorganic fillers, preservatives, texturizing agents, thermochromic additives, insect repellents, and wetting agents, stabilizers (hindered phenols, zinc oxide, hindered amine), slip agents (silicone oil) and combinations thereof.

The additive may provide one or more beneficial properties including: dyeability, hydrophobicity (i.e., polytetrafluoroethylene (PTFE)), hydrophilicity (i.e., cellulose), friction control, chlorine resistance, degradation resistance (i.e., antioxidants), adhesiveness and/or fusibility (i.e., adhesives and adhesion promoters), flame retardance, antimicrobial behavior (silver, copper, ammonium salt), barrier, electrical conductivity (carbon black), tensile properties, color, luminescence, recyclability, biodegradability, fragrance, tack control (i.e., metal stearates), tactile properties, set-ability, thermal regulation (i.e., phase change materials), nutriceutical, delustrant such as titanium dioxide, stabilizers such as hydrotalcite, a mixture of huntite and hydromagnesite, UV screeners, and combinations thereof.

The bicomponent spandex fibers may also be prepared by separate capillaries to form separate filaments which are subsequently coalesced to form a single fiber.

Process of Making Fibers

The fiber of some embodiments is produced by solution spinning (either wet-spinning or dry spinning) of the polyurethane-urea polymer from a solution with conventional urethane polymer solvents (e.g., DMAc), The polyurethaneurea polymer solutions may include any of the compositions or additives described above. The polymer is prepared by reacting an organic diisocyanate with appropriate glycol, at a mole ratio of diisocyanate to glycol in the range of 1.6 to 2.3, preferably 1.8 to 2.0, to produce a "capped glycol". The capped glycol is then reacted with a mixture of diamine chain extenders. In the resultant polymer, the soft segments are the polyether/urethane parts of the polymer chain. These soft segments exhibit melting temperatures of lower than 60°C. The hard segments are the polyurethane/ urea parts of the polymer chains; these have melting temperatures of higher than 200°C. The hard segments amount to 5.5 to 9%, preferably 6 to 7.5%, of the total weight of the polymer.

In one embodiment of preparing fibers, the polymer solutions containing 30-40% polymer solids are metered through desired arrangement of distribution plates and orifices to form filaments. Extruded filaments are dried by introduction of hot, inert gas at 300°C-400°C and a gas:polymer mass ratio of at least 10:1 and drawn at a speed of at least 400 meters per minute (preferably at least 600 m/min) and then wound up at a speed of at least 500 meters per minute (preferably at least 750 m/min), Standard process conditions are well-known in the art. Yarns formed from elastic fibers made in accordance with the present invention generally have a tenacity at break of at least 0.6 cN/dtex, a break elongation of at least 400%, an unload modulus at 300% elongation of at least 27 mg/dtex.

Strength and elastic properties of the spandex were measured in accordance with the general method of ASTM D 2731-72. For the examples reported in Tables below, spandex filaments having a 5 cm gauge length were cycled between 0% and 300% elongation at a constant elongation rate of 50 cm per minute. Modulus was determined as the force at 100% (M100) and 200% (M200) elongation on the first cycle and is reported in grams. Unload modulus (U200) was determined at 200% elongation on the fifth cycle and is reported in the Tables in grams. Percent elongation at break and force at break was measured on the sixth extension cycle.

Percent set was determined as the elongation remaining between the fifth and sixth cycles as indicated by the point at which the fifth unload curve returned to substantially zero stress. Percent set was measured 30 seconds after the samples had been subjected to five 0-300% elongation/relaxation cycles. The percent set was then calculated as % Set=100(Lf-Lo)/Lo, where Lo and Lf are the filament (yam) length, when held straight without tension, before (Lo) and after (Lf) the five elongation/relaxation cycles.

The features and advantages of the present invention are more fully shown by the following examples which are provided for purposes of illustration, and are not to be construed as limiting the invention in any way.

While there have been described what are presently believed to be the preferred embodiments of the invention, those skilled in the art will realize that changes and modifications may be made thereto without departing from the spirit of the invention, and it is intended to include all such changes and modifications as fall within the true scope of the invention. Examples

A spandex fiber off 44 dtex, based on a segmented polyurethaneurea with poly(tetramethylene ether) glycol or PTMEG (Mn-1800 g/mol) capped with methylene bis (4 -phenyl isocyanate) (MDI), chain extended with 1,2-propanedi amine (PDA) and terminated with a mixture of cyclohexylamine (CHA) and diethylamine (DEA) at the weight ratio of 2/1 and 1/1, has been produced. Small amounts of diethylenetriamine (DETA) were added during the chain extension process.

The polymer molecular weights of the as-made virgin polymer, the as-spun yam, and the heated-yam simulating the post-consumer process were monitored and controlled. The fiber properties were collected. The properties were found to be comparable to virgin spandex.

The initial fabric evaluations of this new spandex fiber in circular knits and seamless fabrics with nylon fiber were evaluated, the performance of these fabrics met the expectations.

The initial re-dissolving tests of the as-spun yarn and heated yarn were carried out at ambient conditions, with solids and viscosity of the solutions met the expectations of a recycled polymer. The re-dissolved polymers were also re-spun into 44 dtex yams with properties comparable to the original yarns.

Example 1

79.62 parts by weight of a PTMEG with a number average molecular weight of 1800 grams per mole was reacted with 18.05 parts by weight of MDI to form an isocy ante-terminated polyurethane prepolymer or capped glycol, which was dissolved in N,N-dimethylacetamide (DMAc), followed with chain extension with PDA and chain termination with a mixture of cyclohexylamine (CHA) and diethylamine (DEA) at the weight ratio of 2/1 to give a viscous polyurethaneurea DMAc solution with a solids of 36.0 wt%. About 100 parts per million (ppm) of DETA based on the chain extended polymer solids was also added during the chain extension process. The formed polyurethaneurea had a weight average polymer molecular weight of 92814 grams per mole, with a polydispersity of 2.81 as measured by GPC. This polymer solution was mixed with a slurry of additives including 1.32 wt% antioxidant, 2 ppm blue-toner, 0.60 wt% silicone oil, 2.00 wt% chlorine bleaching resistant and 0.17 wt% TiO2 delustrant based on the total solid weight. The polymer solution with mixed additives was spun into spandex fibers of 44 decitex with 4 filaments in a thread by a conventional drying spinning process, The as-spun yarn had a weight average polymer molecular weight of 104330 grams per mole, with a poly dispersity of 4.50 as measured by GPC. The as-spun fiber properties were given in the Table 1.

Example 2

The ingredients and processes used in Example 2 were essentially the same as those described in Example 1, except with changes in the quantities of the ingredients. In this example, 78.97 parts by weight of PTMEG and 18.53 parts by weight of MDI were used to prepare the polyurethane prepolymer. During the chain extension process, 300 ppm of DETA was used, and the polymer solids was adjusted to 34.7 wt%. The formed polyurethaneurea had a weight average polymer molecular weight of 100110 grams per mole, with a polydispersity of 2.62. The additives in the polymer mixture were also adjusted to have 0.80 wt% antioxidant, 2 ppm blue-toner, 0.27 wt% silicone oil, 2.40 wt% chlorine bleaching resistant and 0.20 wt% T1O2 delustrant based on the total solid weight. This polymer solution with mixed-in additives was spun into spandex fibers of 44 decitex with 4 filaments in a thread by a conventional drying spinning process. The as-spun fiber properties were given in the Table 1.

Example 3

The polymer and additive compositions were the same as Example 2, except that a fiber of 78 dtex with 5 filaments in a thread was made. The as-spun properties of the 78 dtex fiber with 5 filaments were given in the Table 1.

Example 4

The polymer and additive compositions were the same as Example 2, except that a fiber of 44 dtex with 3 filaments in a thread was made. The as-spun properties of the 44 dtex fiber with 3 filamebnts were given in the Table 1. Table 1. As-spun fiber properties

Example 5

A single jersey circular knit fabric, containing Example 1 fiber at 17%, were prepared with a texturized nylon fiber (1/44 dtex/34f), followed with scouring, heat-setting (190°C for 60 seconds) and typical acid dyeing conditions, gave about the same fabric performances in comparison with commercial 44 dtex LYCRA® fibers. This demonstrates that the fiber performances according to the present invention meet the commercial expectations.

Example 6

A single jersey circular knit fabric, containing re-dissolved and re-spun Example 3 fiber at 17%, were prepared with a texturized nylon fiber (4 dtex4/34 filaments), followed with scouring, heat-setting (190°C for 60 seconds) and typical acid dyeing conditions, gave about the same fabric performances in comparison with Example 5. This demonstrates that the fiber according to the present invention can be recycled in a post-industrial process and still meet the commercial expectations. A comparison of the fabric performances of Example 5 and Example 6 is given in the table below.

Example 7

A single jersey circular knit fabric, containing Example 3 at 24%, was prepared with a 78 dtex polyester fiber, followed with scouring, heat-setting (190°C for 60 seconds) and disperse dyeing conditions, for fabric power and power retention evaluations, which resulted in a comparable performances as the previous prepared nylon fabric (Example 5). This finished fabric was treated in enzymatically catalysed depolymerization process to remove the polyester fiber and to recover the polymer according to the present invention. This recycled spandex polymer was dissolved in DMAc with vigorous agitation at room temperature, blended with a commercial spandex polymer solution, without any additives, at 37% solids containing 50% by weight of the recycled spandex polymer of the present invention, and spun into a 44 dtex/4 filament yam using a conventional dry spinning process. Example 8

Example is the same as described in Example 7, except that the recycled spandex polymer was dissolved in DMAc with vigorous agitation at room temperature, blended with a commercial spandex polymer solution, without any additives, at 38.5% solids containing 75% by weight of the recycled spandex polymer of the present invention, and spun into a 44dtex/4 filament yam using a conventional dry spinning process. Example 7 and 8 simulate the feasibility of spandex recycling in a post-consumer process for the fiber circularity. The fiber properties from the recycled spandex polymers in comparison to the original fibers (Example 1 through 4) are given below:

Example 9

The re-spun fiber based on recycled spandex polymer according to the present invention as described from Example 7 was knitted into a seamless fabric with a 28 gauge machine, 2 feeds bare and a polyester fiber plated in (PES 83 dtex /100 fil). The fabric was heast set at 183°/50 seconds in a mini stenter, followed with a disperse dyeing at 120°C. The fabric performances with the re-spun fiber from the recycled polymer were compared against the fabric with original as-spun fiber according to the present invention, and found to be comparable.

Example 9 confirms that for these processing conditions, the tensile performance of the fabric containing a fiber based on 50% recycled spandex polymer according to the present invention are boradly similar to the original fiber based on 100% virgin polymer.

Claims

1. A segmented polyurethaneurea fiber comprising a polyol; a diisocyanate; and a branched aliphatic diamine chain extender.

2. The fibers under present invention can be separated in recycling processes in form of post-consumer fabrics and garments without substantial degradations of the polymer.

3. The recycled polymer can be re-dissolved back into the solvent or concentrated into a solution from which the spandex fiber is originally spun without substantial degradations of the polymer;

4. The re-formed polymer solution can be re-spun into spandex fibers of its original deniers with a recycled polymer content >50% up to 100% in the re-spun fibers.