Melt-spun thermoplastic polyurethane fibers

Abstract

The present invention relates to melt-spun thermoplastic polyurethane fibers comprising a copolymer diol derived from caprolactone and a polyether polyol, both of which are capable of being dyed under disperse dyeing conditions, and fabrics made therefrom.

Description

Background Technology

[0001] In the apparel market, there is a growing interest in fabrics that can stretch while maintaining shape and fit. Thermoplastic polyurethane (“TPU”) fibers show great potential to provide stretch and fit properties, but have some drawbacks. Many polyurethane fibers are produced via dry spinning, which involves dissolving the reactive components in a solvent. Such fibers generally have good heat resistance, but dry spinning is expensive, time-consuming, and involves the use of volatile solvents, creating environmental problems. Melt spinning offers manufacturing advantages, but not all TPUs are suitable for forming fibers under melt spinning conditions. Furthermore, existing TPU technologies that can be melt-spun into fibers do not possess the heat resistance that allows them to withstand certain dyeing conditions. This makes it difficult to combine melt-spun TPU fibers with other common synthetic or natural fibers, as TPU fibers may lose their stretch and recovery properties after exposure to dyeing conditions.

[0002] Therefore, melt-spun TPU fibers with good tensile and recovery properties, but which can be dyed under disperse dyeing conditions (e.g., at temperatures of about 130°C to 135°C), are desired. Fabrics made from TPU fibers alone or in combination with other fiber materials are also desired to provide dyeable fabrics with the desired properties.

[0003] Furthermore, the recycling of waste or used fabrics is an area of ​​increasing interest. There is a desire to develop methods for recycling textile materials to produce other products. Summary of the Invention

[0004] In one embodiment, the present invention is a melt-spun fiber comprising a thermoplastic polyurethane composition and an isocyanate-functionalized crosslinking agent. The thermoplastic polyurethane composition used in the fiber comprises the reaction products of: (i) a polyol component comprising or consisting of a copolymer diol derived from a self-lactone monomer and poly(tetramethylene ether diol), (ii) a hydroxyl-terminated chain extender component, and (iii) a first diisocyanate component.

[0005] In another embodiment, the present invention includes a method for preparing a thermoplastic polyurethane, the method comprising the steps of: (a) preparing a reactive thermoplastic polyurethane composition, which is a reaction product of: (a) a polyol component, wherein the polyol component comprises a copolymer diol derived from an autolactone monomer and poly(tetramethylene ether diol); (b) a chain extender component comprising 1,4-bis(β-hydroxyethoxy)benzene; and (c) a diisocyanate; (2) drying the reactive thermoplastic polyurethane composition; (3) melting the reactive thermoplastic polyurethane composition in an extruder; (4) adding an isocyanate-functionalized prepolymer to the extruder; (5) mixing the reactive thermoplastic polyurethane composition and the isocyanate-functionalized prepolymer in the extruder to form a crosslinked thermoplastic polyurethane polymer; (6) feeding the crosslinked thermoplastic polyurethane polymer into at least one spinneret to produce melt-spun fibers; (7) cooling the melt-spun fibers; and (8) winding the melt-spun fibers onto a spool.

[0006] In yet another embodiment, the present invention provides a fabric comprising a first fiber component and a second fiber component, the first fiber component comprising a stiff yarn, such as polyester fiber, having a limiting elongation of 10% to 75% as measured according to ASTM D2256, and the second fiber component comprising melt-spun thermoplastic polyurethane filament having a limiting elongation of at least 300% as measured according to ASTM D2731, wherein the first fiber component and the second fiber component are knitted together to form the fabric, and wherein the fabric is dyed using disperse dyeing conditions.

[0007] In another embodiment, the present invention provides a method for recycling fabrics prepared herein to prepare other articles.

[0008] These various implementation schemes are described in more detail below. Detailed Implementation

[0009] The features and embodiments of the present invention will be described below by means of the following non-limiting description.

[0010] The disclosed technology includes a melt-spun fiber comprising a thermoplastic polyurethane (“TPU”) composition and an isocyanate-functionalized crosslinking agent. The TPU composition used to prepare the melt-spun fiber of the present invention is a reaction product of a polyol component, a hydroxyl-terminated chain extender component, and a diisocyanate component. The isocyanate-functionalized crosslinking agent is a reaction product of a polyol and an excess of isocyanate. Each of these components will be described in more detail below.

[0011] As used in this paper, the weight-average molecular weight (Mw) was measured using polystyrene standards by gel permeation chromatography, and the number-average molecular weight (Mn) was measured by end-group analysis.

[0012] thermoplastic polyurethane composition

[0013] The TPU compositions used to prepare the melt-spun fibers of the present invention comprise a polyol component, which can also be described as a hydroxyl-terminated intermediate. In the present invention, the polyol component comprises or is composed of a copolymer diol derived from a self-lactone monomer and a hydroxyl-functionalized polyether intermediate.

[0014] Caprolactone monomers that can be used to prepare the copolymer polyols used in this invention include ε-caprolactone and 2-oxetaneheptanone. In one embodiment, the caprolactone monomer is reacted with a polyether diol to form a copolymer diol. In another embodiment, ε-caprolactone may be reacted with another bifunctional initiator such as diethylene glycol, 1,4-butanediol, neopentyl glycol, or any other diol and / or glycol known to those skilled in the art.

[0015] In embodiments of the reaction of ε-caprolactone with polyether polyol intermediates, suitable hydroxyl-functionalized polyether intermediates include polyether polyols derived from diols or polyols having a total of 2 to 15 carbon atoms, and in some embodiments, alkyl diols or diols reacting with ethers containing alkylene oxides (typically ethylene oxide or propylene oxide or mixtures thereof) having 2 to 6 carbon atoms. For example, hydroxyl-functionalized polyethers can be prepared by first reacting propylene glycol with propylene oxide, followed by reacting it with ethylene oxide. The primary hydroxyl groups generated from ethylene oxide are more reactive than secondary hydroxyl groups and are therefore likely preferred. Available commercial polyether polyols include poly(ethylene glycol) containing ethylene oxide reacted with ethylene glycol, poly(propylene glycol) containing propylene oxide reacted with propylene glycol, and poly(tetramethylene ether glycol) containing water reacted with tetrahydrofuran, which can also be described as polytetrahydrofuran and is commonly referred to as PTMEG. In some embodiments, the hydroxyl-functionalized polyether intermediate used in this invention comprises or is composed of PTMEG.

[0016] In one embodiment, the polyol component comprises or consists of a copolymer diol as a reaction product of caprolactone monomer and poly(tetramethylene ether glycol). In another embodiment, the polyol component comprises or consists of a reaction product of about 50 wt% ε-caprolactone monomer and about 50 wt% poly(tetramethylene ether glycol).

[0017] In one embodiment of the invention, the reaction mixture forming the TPU composition used herein comprises about 50% to about 80% by weight of a polyol component, for example about 60% to about 75% by weight or even about 65% to about 70% by weight.

[0018] Chain extender components

[0019] The TPU compositions described herein were prepared using chain extender components. Suitable chain extenders include diols, diamines, and combinations thereof.

[0020] Suitable chain extenders include relatively small polyhydroxy compounds, such as lower aliphatic or short-chain diols having 2 to 20, 2 to 12, or 2 to 10 carbon atoms. Suitable examples include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol (BDO), 1,6-hexanediol (HDO), 1,3-butanediol, 1,5-pentanediol, neopentanediol, 1,4-cyclohexanediol (CHDM), 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane (HEPP), 1,4-bis(β-hydroxyethoxy)benzene (HQEE), hexamethylenediol, heptaethylenediol, nonanediol, dodecanediol, 3-methyl-1,5-pentanediol, ethylenediamine, butylenediamine, hexamethylenediamine, and hydroxyethyl resorcinol (HER), as well as mixtures thereof. In one embodiment, the chain extender comprises or consists of 1,4-bis(β-hydroxyethoxy)benzene (HQEE).

[0021] In one embodiment of the invention, the reaction mixture forming the TPU composition used herein comprises about 5% to about 25% by weight of a chain extender component, for example about 5% to about 15% by weight or even about 8% to 10% by weight.

[0022] Isocyanate components

[0023] The TPU of the present invention is prepared using an isocyanate component. The isocyanate component may include one or more polyisocyanates, or more particularly, one or more diisocyanates. Suitable polyisocyanates include aromatic diisocyanates, aliphatic diisocyanates, or combinations thereof. In some embodiments, the polyisocyanate component includes one or more aromatic diisocyanates. In some embodiments, the polyisocyanate component is substantially free of or even completely free of aliphatic diisocyanates. In other embodiments, the polyisocyanate component includes one or more aliphatic diisocyanates. In some embodiments, the polyisocyanate component is substantially free of or even completely free of aromatic diisocyanates. In some embodiments, a mixture of aliphatic and aromatic diisocyanates may be useful.

[0024] Examples of available polyisocyanates include aromatic diisocyanates such as 4,4′-methylene bis(phenyl isocyanate) (MDI), 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), m-xylene diisocyanate (XDI), phenylene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, and toluene diisocyanate (TDI); and aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate (HDI), isoflurone diisocyanate (IPDI), 1,4-cyclohexyl diisocyanate (CHDI), decane-1,10-diisocyanate, lysine diisocyanate (LDI), 1,4-butane diisocyanate (BDI), isoflurone diisocyanate (PDI), and dicyclohexylmethane-4,4′-diisocyanate (H12MDI). These diisocyanate isomers may also be useful. Mixtures of two or more polyisocyanates can be used. In some embodiments, the isocyanate component comprises or is composed of aromatic diisocyanates. In some embodiments, the isocyanate component comprises or is composed of MDI.

[0025] In one embodiment of the invention, the reaction mixture forming the TPU composition used herein comprises about 15% to about 30% by weight of an isocyanate component, for example about 15% to about 25% by weight or even about 18% to about 20% by weight.

[0026] Optionally, one or more polymerization catalysts may be present during the polymerization reaction of TPU. Generally, any conventional catalyst can be used to react the diisocyanate with the polyol intermediate or chain extender. Examples of suitable catalysts, particularly those accelerating the reaction between the NCO group of the diisocyanate and the hydroxyl groups of the polyol and chain extender, are conventional tertiary amines known in the art, such as triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N′-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo[2.2.2]octane, etc., and also particularly organometallic compounds, such as titanates, iron compounds such as iron acetylacetonate, tin compounds such as stannous diacetate, stannous octate, stannous dilaurate, bismuth compounds such as bismuth trinedecanoate, or dialkyltin salts of aliphatic carboxylic acids such as dibutyltin diacetate, dibutyltin dilaurate, etc. The commonly used amount of catalyst is 0.001 to 0.1 parts by weight per 100 parts by weight of the polyol component. In some embodiments, the reaction that forms the TPU of the present invention is substantially free of or completely free of catalyst.

[0027] The TPU composition used in this invention can be prepared via a "one-step" method, wherein all components are added together simultaneously or substantially simultaneously to a heated extruder and reacted to form the TPU. The equivalence ratio of the total equivalence of the diisocyanate to the hydroxyl-terminated intermediate and chain extender is typically from about 0.95 to about 1.10, for example from about 0.97 to about 1.03 or even from about 0.98 to about 1.0. In one embodiment, the equivalence ratio may be less than 1.0, such that the TPU has terminal hydroxyl groups to enhance the reaction with the crosslinking agent during the fiber spinning process. The weight-average molecular weight (MW) of the TPU is typically from about 25,000 to about 300,000, for example from about 50,000 to about 200,000, or even further, for example from about 75,000 to about 150,000.

[0028] In another embodiment, TPU can be prepared using a prepolymer method. In the prepolymer method, a hydroxyl-terminated intermediate reacts with one or more diisocyanates, typically in an equivalence excess, to form a prepolymer solution having free or unreacted isocyanates therein. Subsequently, a chain extender as described herein is added in an equivalence typically equal to the isocyanate end groups and any free or unreacted diisocyanate compounds. Thus, the total equivalence ratio of total diisocyanates to the total equivalence of the hydroxyl-terminated intermediate and the chain extender is about 0.95 to about 1.10, for example, about 0.97 to about 1.03 or even about 0.98 to about 1.0. In one embodiment, the equivalence ratio may be less than 1.0, such that the TPU has terminal hydroxyl groups to enhance the reaction with the crosslinking agent during the fiber spinning process. Typically, the prepolymer method can be carried out in any conventional apparatus such as an extruder.

[0029] Optional additive components may be present during the polymerization reaction, and / or optional additive components may be incorporated into the above-mentioned TPU elastomer to improve processing and other properties. These additives include, but are not limited to, antioxidants, organophosphites, phosphine and phosphonates, hindered amines, organic amines, organosulfur compounds, lactones and hydroxylamine compounds, biocides, fungicides, antimicrobial agents, compatibilizers, dissipative or antistatic additives, fillers and reinforcing agents such as titanium dioxide, alumina, clay and carbon black, flame retardants such as phosphate esters, halogenated materials and metal salts of alkylbenzene sulfonic acids, impact modifiers such as butadiene-styrene methacrylate (“MBS”) and methyl methacrylate butyl acrylate (“MBA”), release agents such as waxes, greases, pigments and colorants, plasticizers, polymers, rheology modifiers such as monoamines, polyamide waxes, silicones and polysiloxanes, slip additives such as paraffin wax, hydrocarbon polyolefins and / or fluorinated polyolefins, and UV stabilizers, which may be hindered amine light stabilizers (HALS) and / or UV light absorbers (UVA). Other additives may be used to enhance the properties of TPU compositions or blends. All of the above additives can be used in the commonly used effective amounts of these substances.

[0030] These additional additives can be incorporated into the components used in the preparation of TPU resin or into the reaction mixture used in the preparation of TPU resin, or they can be incorporated after the preparation of TPU resin. In another method, all materials can be mixed with TPU resin and then melted, or they can be directly incorporated into the melt of TPU resin.

[0031] Isocyanate functional crosslinking agent

[0032] The TPU composition described above is combined with an isocyanate-functionalized crosslinking agent. The crosslinking agent is a reaction product of a hydroxyl-terminated polyol selected from polyethers, polyesters, polycaprolactone, polycarbonates, and mixtures thereof, and an excess of diisocyanate. In one embodiment, the hydroxyl-terminated polyol used in the crosslinking agent is a polyether polyol. For example, the hydroxyl-terminated polyether may comprise or consist of poly(tetramethylene ether glycol). In another embodiment, the hydroxyl-terminated polyol used in the crosslinking agent is a polyester. For example, the hydroxyl-terminated polyester may comprise or consist of neopentyl adipate. In one embodiment, the polyisocyanate component is an aromatic diisocyanate, such as MDI. In another embodiment, the polyisocyanate component is an aliphatic diisocyanate, such as H12MDI. The crosslinking agent has an isocyanate functionality greater than 1.0, for example, from about 1.5 to 2.5, and further, for example, from about 1.8 to 2.2. Isocyanate-functionalized crosslinking agents can be prepared using a prepolymer method as described herein, wherein a hydroxyl-terminated intermediate reacts with an equivalence excess of one or more diisocyanates to form a prepolymer solution having free or unreacted isocyanates.

[0033] The crosslinking agent used with the TPU polymer is used at a weight percentage of about 5.0 wt% to about 20 wt%, for example, about 8.0 wt% to about 15 wt%. The percentage of crosslinking agent used is based on the total weight percentage of the TPU and the crosslinking agent.

[0034] thermoplastic polyurethane fiber

[0035] Melt-spun TPU fibers are prepared by melting a TPU composition in an extruder and adding a crosslinking agent to the molten TPU. The TPU melt and crosslinking agent are fed into a spinneret. The melt exits the spinneret to form fibers, and the fibers are cooled and wound onto a spool. The method comprises the following steps: (1) preparing a reactive thermoplastic polyurethane composition, which is a reaction product of the following substances: (a) a polyol component, wherein the polyol component comprises or is composed of a copolymer diol derived from a self-lactone monomer and poly(tetramethylene ether diol); (b) a chain extender component, wherein the chain extender component comprises or is composed of 1,4-bis(β-hydroxyethoxy)benzene; and (c) a diisocyanate; (2) drying the reactive thermoplastic polyurethane composition; (3) melting the reactive thermoplastic polyurethane composition in an extruder; (4) adding an isocyanate-functionalized prepolymer to the extruder; (5) mixing the reactive thermoplastic polyurethane composition and the isocyanate-functionalized prepolymer in the extruder to form a crosslinked thermoplastic polyurethane polymer; (6) feeding the crosslinked thermoplastic polyurethane polymer into at least one spinneret to produce melt-spun fibers; (7) cooling the melt-spun fibers; and (8) winding the melt-spun fibers onto a spool core. The steps of the method will be described in more detail below.

[0036] Melt spinning begins with feeding a pre-formed TPU polymer into an extruder. The TPU is melted in the extruder, and a crosslinking agent is continuously added downstream, either near the point where the TPU melt exits the extruder or after the TPU melt has exited the extruder. If the crosslinking agent is added after the melt exits the extruder, a static or dynamic mixer is required to mix the crosslinking agent with the TPU melt to ensure that the crosslinking agent is properly incorporated into the TPU polymer melt. After exiting the extruder and mixer, the molten TPU polymer and crosslinking agent flow into a manifold. The manifold splits the melt flow into different streams, each of which is fed to multiple spinnerets. Typically, each different stream exiting the manifold has a melt pump, with each melt pump feeding several spinnerets. The spinnerets will have orifices through which the melt is forced and exits the spinneret in the form of fibers. The size of the orifices in the spinneret will depend on the desired fiber size (denier). The fibers are drawn or stretched as they exit the spinneret and are cooled before being wound onto a spool. Fibers are stretched by winding the spool at a speed higher than the speed at which the fiber leaves the spinneret. For melt-spun TPU fibers, the spool is typically wound at a rate greater than the speed at which the fiber leaves the spinneret; for example, in some embodiments, it is wound at a rate 4 to 8 times the speed at which the fiber leaves the spinneret, but this can be slower or faster depending on the specific equipment. Typical spool winding speeds range from 100 m / min to 3000 m / min, but for TPU melt-spun fibers, speeds more typically range from 300 m / min to 1200 m / min. Finishing oils (such as silicone oil) are usually added to the surface of the fiber after cooling and just before winding onto the spool.

[0037] An important aspect of melt spinning is the mixing of the TPU polymer melt and the crosslinking agent. Proper, uniform mixing is crucial for achieving uniform fiber properties and long run times without fiber breakage. The mixing of the TPU melt and crosslinking agent should be a piston-flow (i.e., first-in, first-out) method. Proper mixing can be achieved using either a dynamic mixer or a static mixer. For example, a dynamic mixer with a feed screw and a mixing pin can be used. U.S. Patent 6,709,147 describes such a mixer and features a rotatable mixing pin.

[0038] During the fiber spinning process, TPU reacts with a crosslinking agent to obtain TPU in fibrous form with a weight-average molecular weight (MW) of about 200,000 to about 800,000, preferably about 250,000 to about 500,000, more preferably about 300,000 to about 450,000. At the point where the TPU exits the spinneret, the reaction between the TPU and the crosslinking agent in the fiber spinning process should be greater than 20%, preferably about 30% to about 60%, and more preferably about 40% to about 50%. Typical prior art TPU melt spinning reaction between the TPU polymer and the crosslinking agent is less than 20%, and typically about 10% to 15%. The reaction is determined by the disappearance of NCO groups. The higher reaction percentage of the present invention improves melt strength, thus allowing for higher spinning temperatures, which improves the spinnability of the TPU. The fibers are typically aged on a spool in an oven until the molecular weight reaches a stable level.

[0039] The spinning temperature (the temperature of the polymer melt in the spinneret) should be higher than the polymer's melting point, and preferably about 10°C to about 20°C higher. Higher usable spinning temperatures generally result in better spinning. However, if the spinning temperature is too high, the polymer may degrade. Therefore, about 10°C to about 20°C higher than the TPU polymer's melting point is the optimal temperature for achieving a balance between good spinning and no polymer degradation. If the spinning temperature is too low, the polymer may solidify in the spinneret and cause fiber breakage. The fibers produced by this invention are spun at temperatures greater than 190°C, and preferably about 190°C to about 220°C, or even about 190°C to about 200°C.

[0040] An important aspect of preparing melt-spun TPU fibers is the duration for which the method can be run continuously. The necessity to stop the method is usually a result of fiber breakage. Fiber breakage occurs when the pressure at the spinneret increases to unacceptable levels. Fiber breakage typically occurs when the pressure reaches approximately 140 to 200 kgf / cm². Pressure buildup can occur due to several reasons, such as improper mixing. This leads to the formation of products due to the self-reaction of the crosslinking agent, which can cause the fibers to partially block the small exit orifices in the spinneret. This invention allows for a much longer run time before the harmful pressure buildup that leads to fiber breakage.

[0041] Melt-spun TPU fibers can be produced in various deniers. The term "denier" is defined as the mass in grams of 9000 meters of fiber, filament, or yarn. It describes the linear density of the fiber, filament, or yarn, the mass per unit length, and is measured according to ASTM D1577 Option B. Typical melt-spun TPU fibers are produced in sizes smaller than 240 deniers, more typically from 10 to smaller than 240 deniers, with 20 and 40 deniers being commonly used sizes.

[0042] Due to the high temperatures required for polyester dyeing, existing melt-spun TPU fibers are generally not used in combination with polyester fibers. Because of the lack of polarity and extremely strong crystallinity of both polyester polymers and fibers, disperse dyes are typically used for dyeing. These fibers are usually dyed at 120°C to 135°C (e.g., approximately 130°C) for 60 minutes at a pressure of 1 to 1.5 kg / cm². 2 This pressure dyeing process "opens" the polyester polymer, allowing dye molecules to penetrate. When dyeing is complete and the fabric is removed from the pressure dyeing container (called a dyeing machine), the polyester polymer system "closes" again, trapping the disperse dye molecules inside. Existing melt-spun TPU fibers cannot withstand this type of temperature for 60 minutes without losing their physical properties, such as toughness and shape retention percentage as measured according to ASTM D2731. Furthermore, when exposed to the aforementioned elevated temperatures and pressures, existing melt-spun TPU fibers tend to fuse with adjacent fibers, which is detrimental to the tensile properties of the fabric.

[0043] The high heat resistance of the melt-spun TPU fiber of the present invention can withstand the dyeing process of polyester fiber while retaining sufficient physical properties to maintain elasticity.

[0044] Another feature of the high heat-resistant melt-spun TPU fibers of this invention is their ability to absorb disperse dyes. Disperse dyeing methods involve exposure to a temperature of approximately 130°C for approximately 60 minutes (dyeing conditions for polyester fibers). Many TPU fibers fail to exhibit dye absorption, colorfastness (after washing), and bleach resistance after exposure to these temperatures.

[0045] The melt-spun fibers prepared according to the present invention possess unique physical properties not exhibited by prior art TPU fibers. Firstly, the fibers exhibit unique elastic properties. For example, the fibers prepared according to the present invention exhibit the following hysteresis after 5 loading and unloading cycles: less than 20% at 100% elongation; less than 18% at 150% elongation; and less than 18% at 200% elongation. The term "hysteresis" is defined as the residual physical effect after the removal of the external stimulus, which in the fiber is observed as the dimensional change after stretching and recovery. It is expressed as a percentage of hysteresis at the corresponding elongation (or strain). Hysteresis is measured according to ASTM D2731. The hysteresis can be calculated using the following information and equation:

[0046] Modulus at 100% elongation during load cycling = m1

[0047] Modulus at 100% elongation during unloading cycle = m2

[0048] Hysteresis % at 100% elongation = (m1-m2) / m1×100. Hysteresis can be calculated similarly at 150% and 200% elongation.

[0049] The melt-spun TPU fibers prepared according to the present invention also have a limiting elongation of at least 300% (e.g., 300% to 650%) as measured by ASTM D2731. Generally, elastic materials are characterized by their ductility and elasticity: when an external force is released, these materials almost completely return to their original dimensions. For an ideal elastic material, only one curve depicts the loading and unloading cycles on a stress-strain diagram. However, for most materials, due to energy loss (in the form of heat), most materials exhibit different loading and unloading curves, also known as "hysteresis." A lower hysteresis percentage value implies excellent elasticity. The use of elastic fibers with extremely low hysteresis percentages can be used to obtain fabrics with less deformation in clothing.

[0050] Furthermore, the melt-spun TPU fibers prepared according to the present invention may also have a melt initiation of 140°C to 170°C, for example 150°C to 170°C, and further, for example, about 155°C to 166°C, as measured according to ASTM D3418, and an elastic modulus of 3.5E+05 to 12E+05 Pa at 130°C, as measured by DMA (Dynamic Mechanical Analysis). DMA measurements were performed using a parallel plate configuration at a frequency of 1 Hz at 0.1% strain, with a heating rate of 2°C / min from -100°C to 250°C.

[0051] fabric

[0052] The TPU fibers of this invention can be used alone or combined with other natural or synthetic fibers through knitting or weaving to prepare fabrics that can be used in a variety of articles. It is desirable to dye such fabrics in a variety of colors.

[0053] In one embodiment, the melt-spun TPU fibers of the present invention can be woven to prepare fabrics. In another embodiment, the melt-spun TPU fibers of the present invention can be combined with one or more different TPU fibers to prepare fabrics. In yet another embodiment, the melt-spun TPU fibers of the present invention can be combined with other fibers such as cotton, nylon, or polyester to prepare various end-use articles, including clothing.

[0054] For example, fabrics according to the invention may combine the melt-spun TPU fibers of the invention with yarns (also referred to herein as “stiff yarns”) that have lower elasticity than the TPU fibers of the invention. Stiff yarns may include, for example, polyester, nylon, cotton, wool, acrylic, polypropylene, or viscose rayon. Stiff yarns may also include, for example, other TPU fibers (not TPU fibers of the invention) with lower elasticity than the TPU fibers of the invention. In one embodiment, the stiff yarn has a limiting elongation of 10% to 200%, for example 10% to 75%, or even 10% to 60%, or even 10% to 50%, or even 10% to 30%, and the melt-spun TPU fibers of the invention have a limiting elongation of at least 300%, for example 300% to 650%. Each fiber component may be included in the composition in an amount from 1% by weight to 99% by weight. The percentage by weight of melt-spun TPU fibers in the end-use application may vary depending on the desired elasticity. For example, woven fabrics contain 1% to 8% melt-spun TPU fibers, underwear contains 2% to 5% melt-spun TPU fibers, swimwear and sportswear contains 8% to 30% melt-spun TPU fibers, corsets contain 10% to 45% melt-spun TPU fibers, and medical tubing contains 35% to 60% melt-spun TPU fibers, with the remainder being stiff, inelastic fibers. Fabrics made from these two fiber materials can be constructed by various methods, including but not limited to circular knitting, warp knitting, weaving, braiding, nonwovens, or combinations thereof. In one embodiment, fabrics made from the fibers of the present invention will have an elongation greater than 100% as measured by ASTM D4964. The fibers can be dyed at elevated temperatures of at least 130°C.

[0055] In this application and the following embodiments, the following characteristics and methods for measuring such characteristics are mentioned:

[0056] ● Denier is a measure of linear density and is measured according to ASTM D1577 Option B;

[0057] ● The toughness of the elastic filament (which is the tensile strength normalized by Denier) is also measured and reported according to ASTM D2731;

[0058] ● The ultimate elongation (which is the elongation at break) of the elastic filament is also measured and reported in accordance with ASTM D2731.

[0059] ●Hysteresis, as previously mentioned in this article, is defined and calculated at the corresponding elongation and reported according to ASTM D2731 for elastic filaments;

[0060] ● For non-elastic stiff yarns such as polyester, measure toughness and elongation using ASTM D2256 standard;

[0061] ● Measure the content of individual components in the fabric according to ASTM D629

[0062] ● Measure the fabric tensile strength and fabric modulus according to ASTM D4964.

[0063] ●Wash fabrics according to Test Method 135 of the American Association of Textile Chemists and Printers (“AATCC”).

[0064] The invention will be better understood by referring to the following embodiments.

[0065] Example

[0066] Table 1 lists the TPU compositions prepared for manufacturing the fibers of this invention. The TPU hard segments are the total amount of isocyanate and chain extender in the TPU composition by weight.

[0067] Table 1

[0068]

[0069] The TPU polymers of Examples A through G were pre-dried at 80°C for 12 hours in a vacuum intermittent dryer. After drying, the TPU polymers were melted in a 1.25-inch single-screw extruder with an L / D ratio of 24. The extruder had four heating zones maintained between 180°C and 225°C throughout the process. Upon exiting the extruder, the TPU polymer melt was mixed with 10 wt% of a prepolymer crosslinker (90 wt% TPU polymer melt / 10 wt% crosslinker). The TPU and crosslinker combinations are summarized in Table 2.

[0070] Table 2

[0071]

[0072]

[0073] The crosslinking agent was mixed with the TPU polymer melt in a dynamic mixer and then pumped to the spinnerets via a manifold. Each spinneret had a 0.65 mm orifice size. The polymer stream exiting the spinnerets was cooled by air, a silicone finishing oil was applied, and the resulting fibers were wound onto spools. The fibers on the spools were heat-aged at 80°C for 24 hours before testing the physical properties of the fibers. Table 3 summarizes the key properties of the fibers.

[0074] Table 3

[0075]

[0076] The fibers of Example 1 were used to prepare single-knitted fabrics on a Vanguard circular knitting machine. 70D (68 filaments) multifilament textured polyester yarn (as stiff yarn) was combined with the examples in Table 3. The knitting tension on the machine was adjusted to achieve a balanced knitting ratio throughout the fabric, containing 25% of the elastic yarn from Table 3 and 75% of the polyester yarn (this was confirmed according to ASTM D629-15 by mechanically separating the elastic and stiff yarns by weight in a fabric sample). Fiber Example 1 in Table 2 was successfully converted into fabric. Fibers Examples 2 through 7 were too sticky and consistently broke during the knitting process, failing to convert into fabric.

[0077] The knitted fabric using the fibers of Example 1 is dyed as described below.

[0078] Scouring, dyeing, and reduction cleaning solutions: 1000ml of scouring solution contains 2g Na₂CO₃, 6g NaOH, and the remainder is deionized water. 1000ml of dye solution contains 2g Foron Navy S-2GRL200 (Archroma US), 6g Na₂CO₃, and the remainder is deionized water. The pH of the dye bath is adjusted to 4.5 using acetic acid. 1000ml of reduction cleaning solution contains 6g NaOH, and the remainder is deionized water.

[0079] Place a 10-meter-long, 1-kg piece of fabric on Thies In the dyeing machine, the dyeing machine is programmed to perform scouring, dyeing, and reduction cleaning temperature cycles.

[0080] Scouring was performed at 65°C for 30 minutes using one liter of the scouring solution prepared above, followed by rinsing with warm tap water. Then, the dye container was filled with one liter of dye solution. The dyeing process was initiated at 50°C, and the bath temperature was then slowly increased to 130°C at a rate of 2°C / min and maintained at that temperature for 60 minutes. The temperature was then lowered to 80°C, after which the dye solution was drained from the dye container, followed by two cycles of rinsing with tap water.

[0081] After rinsing, introduce one liter of the reducing cleaning solution prepared above into the dyeing container at 75°C to 80°C and maintain for 30 minutes. Then, rinse the fabric sample with warm tap water until no more dye seeps out. Finally, immerse the fabric in a 1% acetic acid neutralization solution for 30 seconds.

[0082] The wet fabric sample was air-dried overnight. Once dry, the fabric was heat-set in a tenter frame and pre-stretched 20% beyond its initial width. The fabric was then passed through the tenter frame twice.

[0083] Next, the fabric samples were washed using American Association of Textile Chemists and Finishers (“AATCC”) Test Method 135-2018. After washing, the tensile properties of the fabric samples were evaluated according to the table below:

[0084] Table 4

[0085]

[0086] *According to ASTM D4964, a constant load of 10 lb-f is applied in both the warp (fabric length) and weft (fabric width) directions.

[0087] Fabrics made from the fibers of this invention can also be recycled. In one embodiment, the fabric prepared according to this invention is recycled to prepare extruded or molded articles. Therefore, this invention provides a method for preparing articles comprising providing a disperse-dyed fabric prepared according to this invention, shredding such fabric, heat-treating such shredded fabric to form granules, and then melting and shearing these granules in an extruder to form articles.

[0088] Each of the foregoing references is incorporated herein by reference, including any prior application claiming priority thereto, whether or not specifically listed above. Reference to any document is not an admission that such document constitutes prior art or general knowledge to a person skilled in the art in any jurisdiction. Unless expressly stated in the examples or otherwise, all numerical quantities of matter, reaction conditions, molecular weight, number of carbon atoms, etc., specified in this specification should be understood to be modified by the word “about.” It should be understood that the upper and lower limits of the quantities, ranges, and proportions described herein can be combined independently. Similarly, the ranges and quantities of each element of the invention can be used in conjunction with the ranges or quantities of any other element.

[0089] As used herein, the transitional term "comprising," synonymous with "comprising," "containing," or "characterized in," is inclusive or open-ended and does not exclude additional, unlisted elements or method steps. However, in every use of "comprising" herein, it is intended that the term also cover the phrases "consistently composed of" and "composed of" as alternative embodiments, wherein "consisting of" excludes any elements or steps not specified, and "consisting of" allows the inclusion of additional, undescribed elements or steps that do not materially affect the essential and novel characteristics of the composition or method under consideration.

[0090] While certain representative embodiments and details have been shown to illustrate the purpose of this invention, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention. In this respect, the scope of the invention is defined only by the following claims.

Claims

1. A melt-spun fiber, said melt-spun fiber comprising: (a) A thermoplastic polyurethane composition comprising the reaction product of the following substances: i. A polyol component, wherein the polyol component comprises a copolymer diol derived from its own lactone monomer and poly(tetramethylene ether diol); ii. Hydroxyl-terminated chain extender components; and iii. The first diisocyanate component; and (b) An isocyanate-functionalized prepolymer crosslinking agent, wherein the isocyanate prepolymer crosslinking agent comprises a reaction product of poly(tetramethylene ether glycol) and a second diisocyanate component or neopentyl adipate and a second diisocyanate component.

2. The melt-spun fiber according to claim 1, wherein the isocyanate prepolymer crosslinking agent is composed of a reaction product of poly(tetramethylene ether glycol) and a second diisocyanate component or neopentyl adipate and a second diisocyanate component.

3. The melt-spun fiber according to claim 1, wherein the copolymer diol comprises a reaction product of 50% by weight caprolactone monomer polyol and 50% by weight poly(tetramethylene ether diol).

4. The melt-spun fiber according to any one of claims 1 to 3, wherein the copolymer has a number-average molecular weight of 2000 Daltons as measured by end-group analysis.

5. The melt-spun fiber according to any one of claims 1 to 3, wherein the chain extender component comprises 1,4-bis(β-hydroxyethoxy)benzene.

6. The melt-spun fiber according to any one of claims 1 to 3, wherein the chain extender component is composed of 1,4-bis(β-hydroxyethoxy)benzene.

7. The melt-spun fiber according to claim 5, wherein the chain extender component further comprises a co-chain extender.

8. The melt-spun fiber according to claim 7, wherein the co-chain extender is selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-butanediol, 1,5-pentanediol, neopentanediol, 1,4-cyclohexanediol, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, hexamethylenediol, heptaethylenediol, nonanediol, dodecanediol, 3-methyl-1,5-pentanediol, ethylenediamine, butylenediamine, hexamethylenediamine, hydroxyethyl resorcinol, and mixtures thereof.

9. The melt-spun fiber according to any one of claims 1 to 3, wherein the first diisocyanate component comprises an aromatic diisocyanate.

10. The melt-spun fiber according to any one of claims 1 to 3, wherein the first diisocyanate component is composed of an aromatic diisocyanate.

11. The melt-spun fiber according to claim 9, wherein the first diisocyanate component comprises 4,4′-diphenylmethane diisocyanate.

12. The melt-spun fiber according to claim 9, wherein the first diisocyanate component is composed of 4,4′-diphenylmethane diisocyanate.

13. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 50% to 80% by weight of the polyol component.

14. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 60% to 80% by weight of the polyol component.

15. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 70% to 80% by weight of the polyol component.

16. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 5% to 25% by weight of the chain extender component.

17. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 5% to 15% by weight of the chain extender component.

18. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 5% to 10% by weight of the chain extender component.

19. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 15% to 30% by weight of the first diisocyanate.

20. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 15% to 25% by weight of the first diisocyanate.

21. The melt-spun fiber according to any one of claims 1 to 3, wherein the thermoplastic polyurethane composition contains 15% to 20% by weight of the first diisocyanate.

22. The melt-spun fiber according to any one of claims 1 to 3, wherein the second diisocyanate component comprises an aromatic diisocyanate.

23. The melt-spun fiber of claim 22, wherein the second diisocyanate component comprises 4,4′-methylenebis(phenyl isocyanate).

24. The melt-spun fiber according to claim 22, wherein the second diisocyanate component is composed of 4,4′-methylenebis(phenyl isocyanate).

25. The melt-spun fiber of claim 1, wherein the second diisocyanate component comprises an aliphatic diisocyanate.

26. The melt-spun fiber of claim 19, wherein the second diisocyanate component comprises an aliphatic diisocyanate.

27. The melt-spun fiber of claim 25, wherein the second diisocyanate component comprises dicyclohexylmethane-4,4′-diisocyanate.

28. The melt-spun fiber according to claim 25, wherein the second diisocyanate component is composed of dicyclohexylmethane-4,4′-diisocyanate.

29. A melt-spun thermoplastic polyurethane fiber, said melt-spun thermoplastic polyurethane fiber comprising the reaction products of the following substances: (a) A thermoplastic polyurethane composition comprising the reaction product of the following substances: i. A polyol component, wherein the polyol component comprises a copolymer diol derived from its own lactone monomer and poly(tetramethylene ether diol); ii. A hydroxyl-terminated chain extender component comprising 1,4-bis(β-hydroxyethoxy)benzene; and iii. The first diisocyanate component; and (b) An isocyanate-functionalized prepolymer crosslinking agent, wherein the isocyanate prepolymer crosslinking agent comprises a reaction product of poly(tetramethylene ether glycol) and a second diisocyanate component or neopentyl adipate and a second diisocyanate component. The thermoplastic polyurethane fiber described therein has a weight-average molecular weight of 300,000 to 450,000 as measured by gas permeation chromatography.

30. The melt-spun thermoplastic polyurethane fiber according to claim 29, wherein the hydroxyl-terminated chain extender component is composed of 1,4-bis(β-hydroxyethoxy)benzene.

31. The melt-spun thermoplastic polyurethane fiber according to claim 29, wherein the isocyanate prepolymer crosslinking agent is composed of the reaction product of poly(tetramethylene ether glycol) and a second diisocyanate component or neopentyl adipate and a second diisocyanate component.

32. The melt-spun thermoplastic polyurethane fiber according to claim 29, wherein the copolymer diol comprises 50% by weight of the reaction product of caprolactone monomer polyol and 50% by weight of poly(tetramethylene ether diol).

33. The melt-spun thermoplastic polyurethane fiber according to claim 29, wherein the first diisocyanate component comprises an aromatic diisocyanate.

34. The melt-spun thermoplastic polyurethane fiber according to claim 29, wherein the first diisocyanate component is composed of an aromatic diisocyanate.

35. The melt-spun thermoplastic polyurethane fiber according to claim 32, wherein the first diisocyanate component comprises an aromatic diisocyanate.

36. The melt-spun thermoplastic polyurethane fiber according to claim 32, wherein the first diisocyanate component is composed of an aromatic diisocyanate.

37. The melt-spun thermoplastic polyurethane fiber of claim 33, wherein the first diisocyanate component comprises 4,4′-diphenylmethane diisocyanate.

38. The melt-spun thermoplastic polyurethane fiber according to claim 33, wherein the first diisocyanate component is composed of 4,4′-diphenylmethane diisocyanate.

39. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 50% to 80% by weight of the polyol component.

40. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 60% to 80% by weight of the polyol component.

41. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 70% to 80% by weight of the polyol component.

42. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 5% to 25% by weight of the chain extender component.

43. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 5% to 15% by weight of the chain extender component.

44. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 5% to 10% by weight of the chain extender component.

45. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 15% to 30% by weight of the first diisocyanate.

46. ​​The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 15% to 25% by weight of the first diisocyanate.

47. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the thermoplastic polyurethane composition contains 15% to 20% by weight of the first diisocyanate.

48. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the second diisocyanate component comprises an aromatic diisocyanate.

49. The melt-spun thermoplastic polyurethane fiber according to claim 48, wherein the second diisocyanate component comprises 4,4′-methylenebis(phenyl isocyanate).

50. The melt-spun thermoplastic polyurethane fiber according to claim 48, wherein the second diisocyanate component is composed of 4,4′-methylenebis(phenyl isocyanate).

51. The melt-spun thermoplastic polyurethane fiber according to any one of claims 29 to 38, wherein the second diisocyanate component comprises an aliphatic diisocyanate.

52. The melt-spun thermoplastic polyurethane fiber according to claim 51, wherein the second diisocyanate component comprises dicyclohexylmethane-4,4′-diisocyanate.

53. The melt-spun thermoplastic polyurethane fiber according to claim 51, wherein the second diisocyanate component is composed of dicyclohexylmethane-4,4′-diisocyanate.

54. A method for preparing thermoplastic polyurethane fibers, the method comprising the following steps: (1) A reactive thermoplastic polyurethane composition is prepared as a reaction product of the following substances: (a) a polyol component, wherein the polyol component comprises a copolymer diol derived from an autolactone monomer and poly(tetramethylene ether diol); (b) a chain extender component, wherein the chain extender component comprises 1,4-bis(β-hydroxyethoxy)benzene; and (c) a diisocyanate. (2) Dry the reactive thermoplastic polyurethane composition; (3) Melt the reactive thermoplastic polyurethane composition in an extruder; (4) Add an isocyanate-functionalized prepolymer to the extruder, wherein the isocyanate prepolymer comprises a reaction product of poly(tetramethylene ether glycol) and a second diisocyanate component or neopentyl adipate and a second diisocyanate component. (5) The reactive thermoplastic polyurethane composition and the isocyanate-functionalized prepolymer are mixed in the extruder to form a crosslinked thermoplastic polyurethane polymer; (6) The cross-linked thermoplastic polyurethane polymer is fed into at least one spinneret to produce melt-spun fibers; (7) Cool the melt-spun fibers; as well as (8) The melt-spun fibers are wound onto a spool.

55. The method according to claim 54, wherein the isocyanate prepolymer comprises a reaction product of poly(tetramethylene ether glycol) and a second diisocyanate component or neopentyl adipate and a second diisocyanate component.

56. The method of claim 54, wherein the copolymer diol comprises 50% by weight of the reaction product of caprolactone monomer polyol and 50% by weight of poly(tetramethylene ether diol).

57. The method of claim 54, wherein the thermoplastic polyurethane fiber has a weight-average molecular weight of 300,000 to 450,000 as measured by gas permeation chromatography.

58. The method of claim 56, wherein the thermoplastic polyurethane fiber has a weight-average molecular weight of 300,000 to 450,000 as measured by gas permeation chromatography.

59. The method according to any one of claims 54 to 58, wherein the first diisocyanate component comprises an aromatic diisocyanate.

60. The method according to any one of claims 54 to 58, wherein the first diisocyanate component is composed of an aromatic diisocyanate.

61. The method of claim 59, wherein the first diisocyanate component comprises 4,4′-diphenylmethane diisocyanate.

62. The method of claim 59, wherein the first diisocyanate component comprises 4,4′-diphenylmethane diisocyanate.

63. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 50% to 80% by weight of the polyol component.

64. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 60% to 80% by weight of the polyol component.

65. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 70% to 80% by weight of the polyol component.

66. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 5% to 25% by weight of the chain extender component.

67. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 5% to 15% by weight of the chain extender component.

68. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 5% to 10% by weight of the chain extender component.

69. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 15% to 30% by weight of the first diisocyanate.

70. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 15% to 25% by weight of the first diisocyanate.

71. The method according to any one of claims 54 to 58, wherein the reactive thermoplastic polyurethane composition contains 15% to 20% by weight of the first diisocyanate.

72. The method according to any one of claims 54 to 58, wherein the second diisocyanate component comprises an aromatic diisocyanate.

73. The method of claim 72, wherein the second diisocyanate component comprises 4,4′-methylenebis(phenyl isocyanate).

74. The method according to claim 72, wherein the second diisocyanate component comprises 4,4′-methylenebis(phenyl isocyanate).

75. The method according to any one of claims 54 to 58, wherein the second diisocyanate component comprises an aliphatic diisocyanate.

76. The method of claim 75, wherein the second diisocyanate component comprises dicyclohexylmethane-4,4′-diisocyanate.

77. The method of claim 75, wherein the second diisocyanate component comprises dicyclohexylmethane-4,4′-diisocyanate.

Images