CN111575817A - Method for manufacturing thermoplastic polyurethane fiber - Google Patents

Abstract

The invention relates to a method for producing thermoplastic polyurethane fibers. The method includes first melt spinning a composition including a Thermoplastic Polyurethane (TPU) resin to obtain a fiber to be heat-set, and heat-setting the fiber to be heat-set, wherein the heat-setting step includes heat-treating and twisting to form the thermoplastic polyurethane fiber. Wherein the heat treating comprises heating the fiber to be heat-set at about 160 ℃ to about 170 ℃ to shrink it.

Description

A kind of manufacturing method of thermoplastic polyurethane fiber

technical field

The present invention relates to a manufacturing method of thermoplastic polyurethane fiber.

Background technique

Thermoplastic polyurethane (hereinafter referred to as "TPU") has excellent physical properties and processability. More importantly, TPU is an environmentally friendly material, which can be degraded naturally in the soil, or can be recycled and reused in the form of raw materials. Therefore, TPUs have received extensive attention in recent years, and have been attempted to be applied to many technical fields.

In the field of shoemaking, TPU has been used to make soles and related parts. However, at present, the uppers of the vast majority of footwear products with TPU as the sole are still made of other materials. Although such products have recyclable TPU soles, because the uppers are made of different materials, their recycling is still extremely difficult and/or has high recycling costs. Therefore, it has become the current research direction in the field of shoemaking to make TPU into shoe uppers and other components to produce shoe products made entirely of TPU that can be recycled and reused.

The inclusion of TPU fibers in fabrics as an auxiliary material is known. TPU fibers as auxiliary materials generally have higher elasticity and lower modulus. Highly elastic TPU fibers are used in fabrics in the form of auxiliary materials, commonly known as spandex. However, due to its performance characteristics, high elastic TPU fibers can only be used as elastic components of fabrics, and it is difficult to be used as the main raw materials of fabrics.

TPU fiber with low elasticity and high modulus has similar rigidity as polyamide fiber and polyester fiber, and has high toughness, high modulus and low elongation, which can replace polyamide fiber and polyester fiber in related technical fields useful material. TPU fibers with low elasticity and high modulus can be used as auxiliary materials of fabrics or as raw materials of fabrics. When using TPU fiber with low elasticity and high modulus to make upper, it can be recycled together with TPU sole, and its friction performance is better than that made of polyamide fiber or polyester fiber. Therefore, for the huge footwear market every year, the application of TPU fibers in the production of shoe uppers is of great significance for environmental protection.

PCT international patent application WO 2018/146192 A1 discloses a production process for melt spinning a TPU-containing raw material composition at a relatively high spinning speed (>2000 m/min). However, the TPU fibers produced by this process will shrink to a greater extent when treated with boiling water or steam. Correspondingly, articles woven with such TPU fibers will shrink to a greater extent (usually 20%-40% shrinkage) during steam or ironing. Shrinking so much reduces the original size of the item, making it tighter and stiffer. As a result, the original good feel of the item is destroyed, making it feel like a plastic product.

There are a number of prior art attempts to address the shrinkage problem of TPU fibers. For example, US patent application US2009/0311529 A1 discloses the production of high tenacity, high modulus TPU monofilaments (rigid TPU monofilaments) in an extrusion, orientation and final dynamic annealing process. The shrinkage rate of TPU monofilament produced by this process is as low as 10% at 140°C, and the denier of the monofilament is 80 to 20,000 deniers. During production, the extrudate has a diameter of 0.95 mm and is oriented after quenching. Thus, the extrusion and orientation steps are not continuous. In addition, US2009/0311529 A1 also does not mention the technology of high spinning speed.

Korean Patent KR 100587903 B1 discloses a dry spinning process for producing low shrinkage polyurethane fibers. The elastic fibers that have undergone the spinning process are then heat-treated in a heat-treating apparatus at a temperature higher than 100° C. for 0.01 to 0.05 seconds. Suitable heat treatment equipment includes heated tubes or rolls of 20 to 30 cm in length. The obtained polyurethane fiber has a shrinkage of less than 7% in boiling water and a shrinkage of less than 5% after heat treatment in a hot air oven at 100° C. for one hour. KR 100587903 B1 deals with the dry spinning process and does not mention the melt spinning process, especially the melt spinning process at high spinning speeds.

US Patent Application US 5,066,439 A discloses a spin-draw process for producing polyester fibers with dimensional stability. The polyester fiber is obtained by melt-spinning polyethylene terephthalate, drawing, merging and relaxation heat treatment to obtain polyester fiber with high strength and low shrinkage. In the drawing step, a heating plate with a temperature of 250 to 500°C is used to assist the relaxation of the fibers.

US patent application US 2009/0124149 A1 discloses a multifilament polyamide (nylon) yarn with high tenacity and low shrinkage rate and a manufacturing process thereof. The fabrication process includes spinning-drawing molten nylon, relaxing and controlling yarn tension, and then winding the yarn.

Chinese patent CN 102168319 B discloses a high-strength, high-modulus and low-shrinkage polyester industrial yarn and a production process thereof. Its production process relaxes the tow after the spinning step.

PCT international patent application PCT/CN2019/075473 (hereinafter referred to as the '473 application) relates to a method for producing TPU fibers with low shrinkage through a melt-spinning-heat-setting process. High spinning speeds (>2000 m/min) were used in the melt spinning step. The heat setting step is divided into two ways: online and offline. The in-line heat setting is carried out by passing the TPU fibers through multiple heat rollers. This heat setting method has high requirements on production equipment (multiple heat rollers are required), and the fibers stay in the heat setting step for a long time, which increases the production cost of TPU fibers, and has low operability and controllability. The off-line heat setting of the application is carried out by placing the silk cake in a steam box, so that the fiber is shrunk and set at a certain temperature for a certain period of time until it releases all the stress. The shrunken silk cake is re-rolled and oiled, and then re-winded and twisted. In this way without in-line heat setting, the fibers in the inner and outer layers of the silk cake have different shrinkage rates due to different degrees of heat and exposure to air (especially oxygen) (there can be a shrinkage difference rate of more than 5%), so that the silk cake has a different shrinkage rate. The quality of the inner and outer layers of fibers is quite different. For example, the fibers in the inner layer of the silk cake treated by this off-line heat setting method do not change color and have higher hardness, while the outer layer fibers of the silk cake turn yellow and are relatively soft. More importantly, the difference in shrinkage of the inner and outer layers of the silk cake is non-linear and unpredictable, resulting in different uppers or even the same upper made of TPU fibers that are not processed by in-line heat setting. / or inconsistency in hardness, poor production stability. Therefore, this off-line heat setting method is not suitable for industrial mass production of TPU fibers for making shoe bodies.

European patent EP 3081109 B1 discloses a technical solution for making shoe body and shoe sole with TPU. However, its published technical solution only mentions TPU fiber for making shoe body in general, and does not involve the specific composition of TPU fiber and its production process.

Therefore, although the prior art has conducted research and exploration on the production process and application of TPU fibers, there is still a need for a production process capable of industrially mass-producing TPU fibers with low shrinkage and high strength.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a method for producing thermoplastic polyurethane fibers. The method includes first melt spinning a composition comprising a thermoplastic polyurethane (TPU) resin to obtain fibers to be heat-set, and heat-setting the fibers to be heat-set, wherein the heat-setting step includes heat treatment and twisting to form thermoplastic polyurethane fibers. Among them, the heat treatment includes heating the fibers to be heat-set at about 160°C to about 170°C to shrink them.

The invention provides a production process capable of industrially producing TPU fibers. The TPU fiber produced according to this process has the characteristics of high strength and low shrinkage rate, which meets the requirements of shoe body production. In addition, the properties of the TPU fibers produced according to the process of the present invention are similar in each layer of the silk cake, which is beneficial to the stability of industrial production.

Description of drawings

In order to facilitate the clear description of the content of the present invention, the present invention will be described below with reference to the accompanying drawings illustrating possible embodiments of the present invention. Those skilled in the art will understand that other embodiments than those shown in the accompanying drawings are possible and within the scope of the present invention. The specific examples of the drawings do not limit the protection scope of the present invention, nor do they limit the generality of the foregoing description of the present invention.

Figure 1 shows an exemplary apparatus for a melt spinning process;

Figure 2 illustrates a heat setting method according to one embodiment of the present invention; and

Figure 3 illustrates a heat setting method according to another embodiment of the present invention.

Those skilled in the art should understand that the accompanying drawings in the present application are for reference purposes only, and do not necessarily reflect the proportions or dimensions of specific embodiments of the present invention.

Detailed ways

Unless specifically stated otherwise, all measurements, weights, lengths, etc. in this application are in metric units and all temperatures are in degrees Celsius. Unless otherwise specified, all materials, compounds, chemicals, etc. in this application are common commercial products and/or industrial standard products, available from numerous suppliers and sales sources around the world.

One aspect of the present invention relates to a method for producing thermoplastic polyurethane fibers. The method includes first melt spinning a composition comprising a thermoplastic polyurethane (TPU) resin to obtain fibers to be heat-set, and heat-setting the fibers to be heat-set, wherein the heat-setting step includes heat treatment and twisting to form thermoplastic polyurethane fibers. Among them, the heat treatment includes heating the fibers to be heat-set at about 160°C to about 170°C to shrink them.

In one embodiment, heat treatment is performed prior to twisting. In another embodiment, the heat treatment is performed after twisting.

In one embodiment, the heat setting step further comprises oiling. Among them, a spin finish can be used to oil the fibers.

In one embodiment, the melt spinning step comprises melt spinning a composition comprising a TPU resin at a spinning speed of about 2000-6500 m/min; or melt spinning the composition at a spinning speed of about 2000-5000 m/min.

In one embodiment, the melt spinning step includes passing the fibers to be heat set through about 2 to about 6 godet rolls. Alternatively, the godet rolls may be thermal rolls.

In another embodiment, the fibers to be heat-set are passed through 3 godets. Alternatively, all three godet rolls may be heated rolls. Wherein, the temperature of the first godet may be about 30°C to about 150°C; or about 60°C to about 100°C. The temperature of the second godet may be about 60°C to about 200°C; or about 100°C to about 160°C. The temperature of the third godet may be about 30°C-150°C; or about 60°C-100°C.

In one embodiment, the speed of the first godet may be about 1000-6000 m/min; or about 1000-4500 m/min. The speed of the second godet may be about 2000-6000 m/min; or about 2000-4500 m/min. The speed of the third godet may be about 2000-6000 m/min; or about 2000-4500 m/min.

In one embodiment, thermally treating the fibers to be heat-set includes passing the fibers to be heat-set through a heat pipe. In another embodiment, the fibers to be heat-set may be passed through the heat pipe at a speed of about 20-200 m/min; or 30-150 m/min; or 40-120 m/min. Specifically, the heat pipe passing speed may be about 20m/min, 30m/min, 40m/min, 50m/min, 60m/min, 70m/min, 80m/min, 90m/min, 100m/min, 110m/min, 120m /min, 130m/min, 140m/min, 150m/min, 160m/min, 170m/min, 180m/min, 190m/min or 200m/min.

In one embodiment, the length of the heat pipe is about 70-120 m. Specifically, the length of the heat pipe may be about 70 m, about 75 m, about 80 m, about 85 m, about 90 m, about 95 m, about 100 m, about 105 m, about 110 m, about 115 m, or about 120 m.

In one embodiment, the heat pipe residence time of the fibers to be heat set is 0.5-5 seconds.

In one embodiment, the heat treatment, oiling and twisting are performed in a continuous manner. In this way, the production efficiency is high, and the production cost of the TPU fiber can be reduced.

In one embodiment, the production method of the present invention further comprises winding the fibers to be heat treated after the melt spinning step in preparation for the heat setting step. In another embodiment, the production method of the present invention further comprises unwinding the fibers to be heat-set prior to the heat-setting step.

In one embodiment, the TPU fibers produced in accordance with the present invention have a denier of about 30-600 de; about 100-500 de; or about 200-400 de. Specifically, the denier of the TPU fibers produced according to the present invention may be about 100de, 200de, 300de, 400de, 500de or 600de.

In one embodiment, the TPU fibers produced in accordance with the present invention have a denier per filament of about 3-50 denier per filament; 5-30 denier per filament; or 6-20 denier per filament. Specifically, the denier per filament of the TPU fibers produced according to the present invention may be about 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, or 20 denier per filament.

In one embodiment, the TPU has a hardness of Shore 80 A to Shore 80 D, a hardness of Shore 80 A to Shore 74 D, or Shore 90 A to Shore 70 D. The hardness is determined according to DIN ISO 7619-1.

In one embodiment, the TPU is the reaction product of an isocyanate or salt, a polyol, and a chain extender. Optionally, the reaction is carried out in the presence of catalysts and/or adjuvants.

In one embodiment, the isocyanate or salt is selected from the group consisting of diphenylmethane diisocyanate (eg, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate, phenylmethane diisocyanate), 1,5-naphthalene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 3,3'-dimethylbiphenyl diisocyanate, 1,2-diphenyl Ethylene diisocyanate, p-phenylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate Isocyanate, 1,5-diisocyanato-2-methylpentane, 1,4-diisocyanato-2-ethylbutane, 1,5-pentamethylene diisocyanate, 1,4-tetramethylene Methylene diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,4 - cyclohexane diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, 4,4'-dicycloethylmethane diisocyanate, The group consisting of 2,4'-dicycloethylmethane diisocyanate, 2,2'-dicycloethylmethane diisocyanate.

In another embodiment, the isocyanate or salt is selected from the group consisting of 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1 , The group consisting of 5-naphthalene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate. In another embodiment, the isocyanate is selected from the group consisting of 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene group consisting of diisocyanates. In yet another embodiment, the isocyanate is selected from the group consisting of 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate.

In one embodiment, the polyol is selected from the group consisting of polyester polyols, polyether polyols, polycaprolactone polyols, and polycarbonate polyols. In another embodiment, the polyol is selected from the group consisting of polyester polyols and polyether polyols. In yet another embodiment, the polyol is polytetramethylene ether glycol.

In one embodiment, the chain extender is selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,10-decanediol , 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol , 1,6-hexanediol, the group consisting of bis(2-hydroxyethyl)hydroquinone and triols. In another embodiment, the chain extender is selected from the group consisting of 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. Among them, the trihydric alcohol may be selected from the group consisting of 1,2,4-trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane.

(A) Melting step

The melt spinning process, also known as melt spinning, is to heat the raw material to a temperature equal to or higher than its melting point to make it in a molten state, and use an extruder or similar equipment to extrude the raw material in a molten state (ie "melt") through spraying. The filaments are discharged into a gaseous atmosphere (eg air or cooled air), and the discharged melt stream is cooled and solidified in the gaseous atmosphere to form fibers. The discharged melt stream is usually cooled and solidified before being drawn into filaments at high speed by a winding device.

In the melt-spinning process, the main component of the raw material (eg TPU) and other components can also be separately heated to a molten state and mixed before extrusion in an extruder.

Melt spinning equipment is known in the art. FIG. 1 shows a melt spinning apparatus comprising an extruder (not shown in FIG. 1 ), a spinning pack 1 and a winding device 2 . Spin packs are known in the art and consist essentially of melt distribution plates and spinnerets.

The raw material composition, or its main components, enters the extruder through a hopper and becomes a molten state, after which it is discharged through a spinneret of a spinning pack to form fibers in a solidified state.

One or more additives, such as cross-linking agents, may be included in the feedstock composition. The production plant may be equipped with at least one mixer, eg a dynamic or static mixer, preferably a static mixer. In one embodiment, the main component of the raw material composition includes or consists of TPU. In this embodiment, the TPU is brought into a molten state in the extruder without the cross-linking agent, and the cross-linking agent and the molten main components are mixed by a mixer. Thereafter, the mixed composition (ie, the raw material composition and the crosslinking agent) is discharged from the spinneret in a molten state. The TPU in the raw material composition is cross-linked with the cross-linking agent during the melt-spinning process. Alternatively, the dried TPU pellets are melted in an extruder and the crosslinker (0-20%) is added at the end of the extruder. The cross-linking agent and TPU melt mixture pass through the mixer and melt line together, are pumped to the spinning pack after metering by the metering pump, and finally extruded from the spinneret. In one embodiment, the feedstock composition used in the present invention does not use a crosslinking agent.

After extrusion from the spinneret, the TPU fibers are drawn or oriented through a series of godet rolls (eg, godet rolls GR1 , GR2 and GR3 in FIG. 1 ) having different ratios of linear speeds. It should be noted that the number of godet rollers is not limited to 3; the number of godet rollers may be greater than or equal to 2 and less than or equal to 6, such as 2, 3, 4, 5 or 6. However, the number of godet rolls is preferably three.

During spinning, fibers can be processed via shrinkage control. This process fixes the degree of orientation of the TPU fibers by heating the godet to a certain surface temperature, so that the shrinkage caused by high-speed spinning can be controlled, for example, to less than 30%.

The surface temperature and speed of godet rolls GR1, GR2, GR3 can be set as follows:

GR1: The temperature can be 30-150°C, preferably 60-100°C; its speed is 1000-6000m/min. Preferably 1000-4500m/min;

GR2: the temperature can be 60-200°C, preferably 100-160°C; its speed is 2000-6000m/min. preferably 2000-4500m/min; and

■ GR3: the temperature can be 30-150°C, preferably 60-100°C; its speed is 2000-6000m/min, preferably 2000-4500m/min.

In this application, unless expressly stated otherwise, the speed of the godet refers to its peripheral speed.

At the end of the melt spinning step, the TPU fibers are wound to the bobbin at high speed (eg 2000-6500 m/min, preferably 2000-5000 m/min) by means of the winding device 2 in Figure 1 . In the present invention, the spinning speed refers to the winding speed.

Additionally, the fibers can be oiled before the fibers extruded from the spinneret reach the godet rolls. The oiling step can lubricate the fibers to reduce friction between the metal and ceramic parts and the fibers in the spinning line. In addition, oiling dissipates static electricity generated by the fibers coming into contact with machine components, bringing the fibers together for easy unwinding from the cake. Fibers can be oiled with conventional spin finishes.

The gas phase in the melt spinning process can be selected in various ways, such as an inert gas atmosphere or an air atmosphere. An air atmosphere (ie, air) is preferred from the standpoint of cost. The temperature of the gas phase can be any temperature below the melting point of the raw material composition, from -10°C to 50°C, preferably 10°C to 40°C from a cost point of view.

The parameters of spinning are not particularly limited except for the spinning speed, but preferred parameters are listed below.

Spinning temperature

In this application, spinning temperature refers not only to the temperature in the extruder, but also the temperature in the polymer line and the spinning pack. The setting of the spinning temperature is not particularly limited, and can be appropriately adjusted according to the melting point of the raw material composition. From the viewpoint of spinnability, the spinning temperature is usually 180°C or higher, preferably 200°C or higher, more preferably 220°C or higher, but preferably not higher than 260°C. Especially when using TPU with high hardness (eg shore 60D or higher), higher spinning temperature (eg higher than 220°C, preferably 225°C or higher) enables higher spinning speed to spin Silk. From the viewpoint of suppressing thermal decomposition of the raw material composition, the spinning temperature is usually 240°C or lower, preferably 235°C or lower.

raw material composition

The feedstock composition may comprise a resin comprising TPU, preferably the resin consists essentially of TPU. "Consisting essentially of TPU" means that the resin includes TPU as well as other substances such as residues, contaminants, or the like. In other words, the resin includes 95% by mass (wt %) or more of TPU, preferably 99 wt % or more, more preferably 99.5 wt % or more, especially 99.9 wt % or more, even 100 wt % of TPUs. The choice of TPU is not limited, and one or more TPUs can be selected. Suitable TPUs are described below.

TPU

In the present invention, there is no special requirement for the applicable TPU. Typically, TPUs can be reacted with each other via (a) isocyanates or esters, preferably organic diisocyanates; (b) polyols; and (c) chain extenders as primary reactants. Chain extenders are typically short chain polyols such as short chain diols. If desired, (d) catalysts and/or (e) adjuvants may also be added to the reaction. In a preferred embodiment, the molecular weight of the chain extender is from 50 g/mol to 499 g/mol. Polyols, also known as long-chain polyols, typically have number average molecular weights ranging from 500 g/mol to 8000 g/mol. The reaction may be a one-step reaction whereby the main reactants (a)-(c) are reacted with each other. In a preferred embodiment, the reaction may be carried out in the presence of optional reactants (d) and (e). Alternatively, the reaction can also be carried out in multiple stages such that two or more of the main reactants (a)-(c) are reacted with each other to form a prepolymer, which is then reacted with the other reactants, preferably at The reaction is carried out in the presence of optional reactants (d) and (e).

The hardness of TPU is tested according to DIN ISO 7619-1. The hardness of TPU is usually Shore 80 A to Shore 80D, preferably Shore 80 A to Shore 74 D, more preferably Shore 90 A to Shore 70D.

The weight-average molecular weight of the TPU is not limited, but is usually from 50,000 to 800,000, preferably from 80,000 to 600,000, and more preferably from 80,000 to 400,000.

For the reactant (a) isocyanate or ester, aromatic, aliphatic and/or araliphatic isocyanates or esters known in the art can be used, preferably diisocyanates or esters. Specifically, one or more of the following substances can be selected: diphenylmethane diisocyanate (MDI), such as 2,2'-, 2,4'-, 4,4'-diphenylmethane diisocyanate; 1 , 5-naphthalene diisocyanate (NDI); 2,4-, 2,6-toluene diisocyanate (TDI); 3,3'-dimethylbiphenyl diisocyanate; 1,2-diphenylethane diisocyanate ; p-phenylene diisocyanate; trimethylene diisocyanate; tetramethylene diisocyanate; pentamethylene diisocyanate; hexamethylene diisocyanate; heptamethylene diisocyanate; octamethylene diisocyanate; 1,5 -2-methylpentane diisocyanato; 1,4-diisocyanato-2-ethylbutane; isophorone diisocyanate (IPDI); 1,3-, 1,4-bis( Isocyanatomethyl)cyclohexane (HXDI); 1,4-cyclohexanediisocyanate; 1-methyl-2,4-cyclohexanediisocyanate, 1-methyl-2,6-cyclohexane alkane diisocyanate; and/or 4,4'-, 2,4'-, 2,2'-dicyclohexylmethane diisocyanate. Preferably, the isocyanate or ester is 2,2'-, 2,4'-, 4,4'-diphenylmethane diisocyanate (MDI); 1,5-naphthalene diisocyanate (NDI); 2, 4-, 2,6-Toluene diisocyanate (TDI); hexamethylene diisocyanate (HDI) and/or isophorone diisocyanate (IPDI). In particular, the isocyanate or ester is MDI and/or HDI. More preferably, the isocyanate or ester is MDI.

For the reactant (b) polyol, polyols known in the art that can react with isocyanates or esters can be used. For example, polyester polyols, polyether polyols, polycaprolactone polyols and/or polycarbonate polyols may be suitable. These compounds are included in the art under the term "polyol". Preferably, the reactant (b) may be a polyether polyol or a polyester polyol. In some cases, mixtures of polyether polyols and polyester polyols can be used. Typically, the polyol has a number average molecular weight of, for example, 500 g/mol to 8000 g/mol, preferably 600 g/mol to 6000 g/mol, more preferably 700 g/mol to 4000 g/mol, still more preferably 800 g/mol to 3000 g/mol. The molecular weight here is the index average molecular weight.

Among these polyols, polyether polyols or polyester polyols may be preferred. While among these two polyols, polyether polyols may be preferred in view of microbial erosion resistance and water repellency, while polyester polyols may be preferred in view of mechanical properties.

The polyether polyols can be synthesized in a manner known in the art, for example by means of alkylene oxides and starters with active hydrogen atoms (2-8 active hydrogen atoms, preferably 2-6 active hydrogen atoms) in the presence of a catalyst polymerization. Catalysts can be selected from alkali metal hydroxides (such as potassium hydroxide or sodium hydroxide), alkali metal alkoxides (such as sodium methoxide, sodium or potassium ethoxide or potassium isopropoxide) or, in the case of cationic polymerization, Lewis Acids (eg antimony pentachloride, boron trifluoride ether or fuller's earth). In addition, double metal cyanide (DMC) can also be used as a catalyst.

For the choice of alkylene oxides, compounds having 2 to 4 carbon atoms in the alkyl moiety are preferred, such as ethylene oxide, 1,2-propylene oxide, tetrahydrofuran, 1,2- or 2,3-epoxybutylene alkyl. The alkylene oxides can be used alone or in a mixture. Preference is given to ethylene oxide, 1,2-propylene oxide and/or tetrahydrofuran. More preferred is tetrahydrofuran.

Possible starters can be, for example, ethylene glycol, diethylene glycol, glycerol, trimethylolpropane, pentaerythritol, sugar derivatives (eg, sucrose, sugar alcohols such as sorbitol), methylamine, ethylamine, isopropylamine, Butylamine, aniline, benzylamine, toluidine, diaminotoluene, naphthylamine, ethylenediamine, diethylenetriamine, 4,4'-methylenediphenylamine, 1,3-propanediamine, 1,6 - Hexamethylenediamine, ethanolamine, diethanolamine, triethanolamine, other dihydric or polyhydric alcohols or monofunctional or polyfunctional amines.

Examples of polyether polyols may include ring-opening polymers of tetrahydrofuran (polytetramethylene ether glycol, PTMEG), polyols based on natural oils such as castor oil, or alkoxides of natural oils or fatty acids.

The polyester polyol can be prepared by a condensation reaction of a polyfunctional alcohol having 2 to 12 carbon atoms and a polyfunctional carboxylic acid having 2 to 12 carbon atoms. The functionality of the multifunctional alcohol or carboxylic acid may be about 2. The multifunctional alcohol can be ethylene glycol, diethylene glycol, butylene glycol, or combinations thereof. Multifunctional carboxylic acids can be succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, phthalic acid, m- Isomers of phthalic acid, terephthalic acid, naphthalene dicarboxylic acid and esters or anhydrides of these acids.

The polyether polyols or polyester polyols described herein have a hydroxyl number of about 15 to about 225 mg KOH/g, preferably a hydroxyl number of about 20 to about 190 mg KOH/g, more preferably a hydroxyl number of about 30 to about 160 mg KOH/g g, most preferably a hydroxyl number of about 40 to about 140 mg KOH/g.

For reactants (c) chain extenders, difunctional or trifunctional amines and alcohols, especially diols, triols, or both, can be used. Difunctional compounds of this type are known as chain extenders, while trifunctional or higher functional compounds are known as crosslinkers. Exemplary compounds may include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,10- Decanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,6- Hexylene glycol and bis(2-hydroxyethyl)hydroquinone; trihydric alcohols such as 1,2,4-trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane . Particularly preferred chain extenders include 1,3-propanediol, 1,4-butanediol or 1,6-hexanediol. In some cases, a mixture of two chain extenders can be used.

The hardness of TPU can be controlled by the molar ratio of reactants (b) and (c). Specifically, the ratio of the molar amount of reactant (b) polyol to the total molar amount of reactant (c) chain extender is in the range of 10:1 to 1:10, especially in the interval of 1:1 to 1:5 . With the increase of the amount of chain extender of reactant (c), the hardness of TPU increases.

The reactant (d) catalyst is optional. Examples thereof may include: trimethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, 1,4- diazidebicyclo[2.2.2]octane and its derivatives; in addition, organometallic compounds, such as titanates; iron-containing compounds, such as iron(III) acetylacetonate; tin-containing compounds, such as stannous acetate, octoate Tin and stannous laurate and their equivalents. The amount of the catalyst to be used is usually 0.0001 to 0.1 part by mass of the catalyst for 100 parts by mass of the long-chain polyol.

Reactant (e) adjuvants are optional. These include: surface actives, nucleating agents, gliding aids and demolding aids, dyes, pigments, antioxidants (eg, against hydrolysis, light, heat, and decolorization), UV absorbers, flame retardants agents, reinforcing agents, plasticizers, flow improvers and/or crosslinking agents. One or more of them can be selected.

The TPU used in the present invention may be polyether TPU or polyester TPU. In this application, "polyether TPU" refers to a TPU obtained using one or more polyether polyols as the main component (eg, 50 wt % or more) of the reactant (b) long-chain polyol. Likewise, "polyester TPU" refers to a TPU obtained using one or more polyester polyols as the main component (eg, 50 wt % or more) of the reactant (b) long-chain polyol.

TPU。The TPU products used in the present invention are also available from suppliers such as BASF's

TPU.

The raw material composition used in the present invention may include the above-mentioned TPU as a main component. However, other additives may also be included in the feedstock composition. The selection of suitable additives is not particularly limited. For example, one or more additives commonly used in the fiber field, such as flame retardants, fillers, pigments, dyes, antioxidants, UV absorbers, and light stabilizers, can be used.

Crosslinking agents can be used as additives. Any crosslinking agent can be used, but is preferably selected from (i) one or more polyols, (ii) one or more isocyanates or esters, and optionally (iii) one or more other reaction products of compounds. One or more polyether or polyester crosslinking agents are preferably used in view of the properties of the final product (ie fibers). Typically, the molecular weight of the crosslinker is lower than that of the TPU.

The crosslinking agent used may be a prepolymer with NCO-functional groups at the end, with a functionality of 1.5-3, preferably 1.6-2.5, more preferably 1.8-2.1. The NCO-content of the prepolymer is 3-15 wt%, preferably 4-10 wt%, more preferably 4-8 wt%.

The polyether polyol content of the reactant (i) polyol for preparing the polyether crosslinking agent is at least 50 wt %, preferably at least 80 wt %, more preferably at least 95 wt %. In other words, the polyether crosslinking agent comprises one or more structural units derived from polyether polyols (ie, polyether polyol units).

The choice of polyether polyol is not particularly limited. Examples thereof may include ring-opening polymers of tetrahydrofuran (polytetramethylene ether glycol, PTMEG), alkylene oxides (especially ethylene oxide, propylene oxide, and mixtures thereof), and alcohol adducts. Preferably, the polyether polyol has a number average molecular weight (Mn) of 500 g/mol-4000 g/mol, more preferably 600 g/mol-3000 g/mol, especially 800 g/mol-2000 g/mol.

The content of the polyester polyol in the reactant (i) polyol for preparing the polyester crosslinking agent is at least 50 wt%, preferably at least 80 wt%, more preferably at least 95 wt%. In other words, the polyester crosslinking agent contains one or more structural units derived from polyester polyols (ie, polyester polyol units). Preferably, the polyester polyol has a number average molecular weight (Mn) of 600 g/mol-4000 g/mol, more preferably 800 g/mol-3000 g/mol, especially 1000 g/mol-3000 g/mol.

The choice of reactant (ii) isocyanate or ester for preparing the crosslinking agent is not particularly limited, and it can be selected from aromatic, aliphatic, cycloaliphatic diisocyanates. The above-mentioned preferred examples of reactants (a) isocyanates or esters for the preparation of TPUs also apply to reactants (ii) isocyanates or esters for the preparation of crosslinking agents. Among them, MDI is preferable.

The amount of the polyether or polyester crosslinking agent is not limited, but preferably it is used in an amount of 1 wt % or more, 3 wt % or more, or even 5 wt % or more, based on the total amount of the raw material composition. When the main ingredient (ie, the TPU resin) is melted separately from the other ingredients (eg, one or more cross-linking agents and/or one or more other additives), the total amount of the feedstock composition is the sum of the main ingredient and the other ingredients the sum of the quantities.

The upper limit of the amount of the crosslinking agent is not particularly limited, but in a preferred embodiment, the upper limit is 25 wt % or less, 20 wt % or less, and more preferably 15 wt % or less. The calculation of the amount is based on the total amount of the raw material composition.

Non-polyether or non-polyester crosslinking agents can also be used. In this case, at least 50% by weight of the reactant (i) polyol from which the crosslinking agent is prepared is selected from non-polyether polyols (ie polyols other than polyether polyols) or non-polyester polyols (ie not polyesters) polyols of polyols), such as polycaprolactone polyols and/or polycarbonate polyols.

In a preferred embodiment of the present invention, the TPU is prepared from (a) PTMEG, (b) MDI and (c) 1,4-butanediol.

(B) Heat setting step

After melt spinning the TPU, the prepared TPU fibers are subjected to heat setting treatment.

According to the present invention, two methods can be adopted for the heat setting treatment of TPU fibers: method A and method B. Each heat setting method is further described below.

In Method A, the fibers are first heated to shrink, then oiled, coiled, and finally twisted. Specifically, as shown in Fig. 2, the fibers pass through the heat pipe 5 and are heated by hot air (the air temperature reaches about 160°C-170°C) and shrink immediately, and the shrunk thread is oiled through an oil tanker 7 (oil nozzle), and then It is then wound onto the bobbin 9. Next, the fibers are twisted on the twisting machine 11 . Among them, shrinking, oiling and winding can be completed on one equipment, twisting can be completed on another equipment, and several processes are carried out in a continuous manner (ie "on-line"). In this way, the inner and outer quality of the silk cake is uniform.

Optionally, the method further includes unwinding the fibers from the original package prior to shrinking. Fiber twisting is usually carried out in an S-twist or Z-twist mode to reduce friction in the subsequent weaving process. The fibers can pass through the heat pipe at a speed of about 20-200 m/min while shrinking. The heating method of the heat pipe makes the fibers heat and heat rapidly to achieve shrinkage and shape. Specifically, the fibers may pass through the heat pipe at a speed of about 20-200 m/min; or about 30-150 m/min; or about 40-120 m/min.

Method A treated TPU fibers have a boiling water shrinkage of less than 2%.

In method B, the fibers are rewound, oiled, and then twisted and then shrunk and set, where shrinking and twisting can be done on a single machine. Specifically, as shown in FIG. 3 , the fibers are first unwound from the raw silk cake, passed through the oil tanker 7 (nozzle), and then wound on the tube 9, and then twisted 11 on the setting twisting machine before shrinking. stereotypes. Shrinking is also accomplished by the heat pipe 5 at a temperature of about 160°C-170°C. The fibers may pass through the heat pipe at a speed of about 20-200 m/min; or about 30-150 m/min; or about 40-120 m/min while shrinking. As mentioned above, the heat pipe provides rapid and uniform heating of the fibers so that they can shrink and set. Among them, unwinding and oiling can be completed on one equipment, and twisting and shrinking can be completed on another equipment. Twisting is usually carried out in an S-twist or Z-twist manner to reduce friction in the subsequent weaving process. After heat setting, the TPU fibers can be wound again. During this time, the fibers are optionally oiled. Similar to method A, method B is also carried out in a continuous "on-line" manner for several processes.

Method B treated TPU fibers also had a boiling water shrinkage of less than 2%.

As mentioned above, both Method A and Method B are "on-line" heat-setting processes, which are convenient for industrial mass production of TPU fibers with high efficiency. In particular, compared with the previous method of shrinking and setting of heat rollers, methods A and B do not require multiple heat rollers to be equipped on the machine, which reduces the requirements for production equipment. Also, the shrinkage of the hot roll requires the fibers to stay on the hot roll for a long time to complete the shrinkage, while the method A and the method B avoid the long stay of the fiber on the hot roll, which improves the production efficiency. In addition, compared with the previous method of shrinking and shaping the silk cake in the steamer, the inner and outer quality of the silk cake obtained by the method A and the method B is uniform, which overcomes the aforementioned problem of uneven quality of the inner and outer layers of the silk cake. More importantly, the TPU fibers processed by Method A and Method B have lower shrinkage and higher strength than the TPU fibers processed by the hot roll and steam box shrink setting methods disclosed in the '473 application.

Those skilled in the art should understand that the winding and/or unwinding steps in Method A and Method B are not necessary, and their use or omission can be determined by those skilled in the art as required. In addition, those skilled in the art should also understand that the purpose of oiling is to reduce friction and disperse static electricity, and its use or omission can be determined by those skilled in the art according to requirements.

TPU fibers having a denier per fiber (DPF) of 3-50 produced according to the present invention have a boiling water shrinkage of less than 2%. It has a strength higher than 2 cN/dtex. Its elongation at break is less than 120%. The TPU fibers produced according to the present invention may have a denier per filament of 3-50, preferably 5-30 denier per filament, more preferably 6-20 denier per filament.

The properties of the TPU fibers produced according to the present invention allow their use in the production of fabrics, in particular for shoe uppers, shoelaces, sportswear (eg sports short-sleeved or long-sleeved tops, sports shorts or trousers, windbreakers, sports underwear) etc.), seat mesh, watch straps, etc. Fabrics made using TPU fibers produced according to the present invention have a boiling water shrinkage of less than 10%, preferably less than 5%.

The invention combines the high-speed spinning process and the heat setting process, improves the production efficiency of the TPU fiber, and can reduce its production cost. In addition, the TPU fibers produced according to the present invention have a boiling water shrinkage rate of less than 2%, and the properties of the TPU fibers in each layer of the silk cake are similar, making it suitable as the main raw material for producing fabrics. The size, properties and feel of the resulting fabric can be controlled during the ironing process.

Example

Measurement and Determination Methods

The measurement and determination methods used in this example are shown in Table 1.

Table 1 - Measurement Assay Methods

In addition, the shrinkage rate of the fabric was measured as follows: take a piece of fabric with a size of 50cm x 50cm as a sample; make two marks on the sample; measure the initial distance between the two marks and set it as L ₀ ; use a commercial steam ironer to iron Iron the sample for 15 seconds under the condition of ironing synthetic fibers; cool the sample to room temperature, measure the distance between the two marks, and set it as L ₁ ; calculate the shrinkage rate of the fabric, shrinkage rate=(L ₀ -L ₁ )/L ₀ x 100%.

Material

The materials used in this example are as follows.

SP9519制备纤维，其基于PTMEG、MDI和1，4-丁二醇，具有80，000-200，000的重均分子量。该产品购自BASF，具有60-64Shore D硬度。使用的油剂购自竹本油脂株式会社(Takemoto Oil&Fat Co.，Ltd)。This example uses polyether type products

SP9519 produces fibers based on PTMEG, MDI and 1,4-butanediol with a weight average molecular weight of 80,000-200,000. This product is available from BASF and has a Shore D hardness of 60-64. The used oil was purchased from Takemoto Oil & Fat Co., Ltd.

The fibers to be heat-set were prepared by using the apparatus shown in FIG. 1 . Specifically, TPU fibers were spun out of the spin pack at 230°C. The fibers were oiled after spinning and then continued through godet rolls GR1, GR2, and GR3, where the temperature and speed of each godet roll are shown in Table 2.

Table 2 - Godet Temperatures and Speeds

Next, TPU fibers having a denier of 300 de and a denier per filament of 8.3 were prepared using the method described above for heat-setting experiments, and the TPU fibers were heat-set according to method A of the present invention and mode A in the '473 application, respectively.

In mode A of the '473 application, the TPU fibers to be heat set are heated in a steam box at 80-110°C for 60-120 minutes. The properties of the resulting TPU fibers are shown in Table 3.

Table 3 - A-Mode Processed TPU Fiber Properties in the '473 Application

According to the heat setting of method A of the present invention, the TPU fibers to be heat set are heated in-line at 160-170° C. using a heat pipe. The length of the heat pipe is 70-120m, and the speed of the TPU fiber to be heat-set through the heat pipe is 40-100m/min. The properties of the resulting TPU fibers are shown in Table 4.

Table 4 - TPU Fiber Properties Processed by Method A of the Invention

It can be proved from the above experiments that the fibers that have only undergone shrinkage control treatment during the spinning process and have not been heat-set after spinning are far inferior to the fibers that have undergone heat-setting treatment in terms of boiling water shrinkage and elongation at break. Different heat-setting methods will also lead to differences in the properties of heat-setting fibers. Comparing the data in Table 3 and Table 4, it can be concluded that the TPU fibers treated by the method A of the present invention are superior to the TPU fibers subjected to the '473 mode A heat setting in both the elongation at break and the boiling water shrinkage.

In addition, according to the data of the layered detection of the silk rolls in Table 3 and Table 4, it can be calculated that the fineness of the inner and outer layers of the TPU fibers subjected to the '473 A mode heat setting is as high as 22.1de, while the TPU fibers treated by the method A of the present invention have The change in denier inside and outside is only 7.7de. It verifies that the properties of the inner and outer layers of the A-mode heat-set TPU fibers of '473 are quite different.

It is also worth noting that the boiling water shrinkage of the '473 A-mode heat-set TPU fibers is negative, ie, it does not shrink in the shrinkage test, but instead increases. This proves that the coil shrinks excessively during heat setting in the steam box = this test result reflects the uncontrollability of heat setting in the steam box. Also, the oil content of the '473 A-mode heat-set TPU fibers is not higher than 0.7%. Such a low oil content makes TPU fibers prone to static electricity, which is not conducive to subsequent processing.

Method B of the present invention can also achieve similar technical effects as method A, and the obtained TPU fibers are superior to the A-mode heat-set TPU fibers of '473 in terms of elongation at break, boiling water shrinkage and yarn uniformity.

In addition, the heat-setting method of the B-mode of '473 uses a method in which the fibers to be heat-set are heated by a heat roller. This heating method requires the TPU fiber to stay in the hot roller for a long time, otherwise it is difficult to fully heat the fiber. In the case of using multiple heat rollers, the fibers are quenched by air between the heat rollers at low speed, which is not conducive to stable and continuous heat setting. Therefore, its practical operability and maneuverability are poor. Compared with the heat setting mode, the TPU fibers treated by the method A and the method B of the present invention can achieve better technical effects in terms of elongation at break and shrinkage in boiling water.

Unless expressly stated otherwise, all terms (including technical and scientific terms) in this application have the meanings that are understood by those of ordinary skill in the art of the present invention. Additionally, it should be further understood that terms, such as those defined in commonly used dictionaries, should be construed to have meanings consistent with their meanings in the relevant art and the context of this application; they should not be construed as in an ideal context or An overly formal meaning unless explicitly defined in this application.

While the invention has been described herein with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be used without departing from the scope of the disclosure Replace one or more of its elements. In addition, several modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its essential scope. Therefore, the present invention is not limited to the best mode disclosed in the embodiments of the present invention, but includes all embodiments falling within the scope of the appended claims.

All references specifically cited herein are incorporated by reference in their entirety. However, citation or incorporation of such reference should not be considered as an admission that it is available as prior art to the present invention.

Non-limiting embodiments of the present invention include:

1. A method of producing thermoplastic polyurethane fibers, comprising:

(1) melt-spinning a composition comprising a thermoplastic polyurethane resin to obtain fibers to be heat-set; and

(2) heat setting the fibers to be heat set, wherein the heat setting step comprises heat treatment and twisting to form thermoplastic polyurethane fibers,

It is characterized in that the heat treatment comprises heating the fibers to be heat-set at about 160°C to about 170°C to shrink them.

2. The method of claim 1, wherein the heat treatment is performed before the twisting.

3. The method of claim 1, wherein the heat treatment is performed after the twisting.

4. The method of claim 1 or 2, wherein the heat setting step further comprises oiling.

5. The method of claim 1, wherein the melt spinning step comprises melt spinning the composition at a spinning speed of about 2000-6500 m/min; or melt spinning the composition at a spinning speed of about 2000-5000 m/min combination.

6. The method of any preceding claim, wherein the melt spinning step comprises passing the fibers to be heatset through about 2 to about 6 godet rolls.

7. A method as claimed in the preceding claim 6, wherein the godet is a thermo roll.

8. The method of claim 5 or 6, wherein the fibers to be heat-set are passed through 3 godets.

9. The method of claim 8, wherein:

(1) The temperature of the first godet of the three godet rolls is about 30°C to about 150°C; or about 60°C to about 100°C;

(2) the temperature of the second of the three godet rolls is about 60°C to about 200°C; or about 100°C to about 160°C; and

(3) The temperature of the third godet of the three godet rolls is about 30°C-150°C; or about 60°C-100°C.

10. The method of claim 9, wherein:

(1) the speed of the first godet is about 1000-6000m/min; or about 1000-4500m/min;

(2) the speed of the second godet is about 2000-6000 m/min; or about 2000-4500 m/min; and

(3) The speed of the third godet is about 2000-6000 m/min; or about 2000-4500 m/min.

11. The method of any preceding claim, wherein the thermal treatment of the fibers to be heat-set comprises passing the fibers to be heat-set through a heat pipe.

12. The method of claim 11, wherein the fibers to be heat-set are passed through the heat pipe at a speed of about 20-200 m/min; or at a speed of 30-150 m/min; or at a speed of 40- A speed of 120 m/min was passed through the heat pipe.

13. The method of claim 11, wherein the heat pipe residence time of the fibers to be heat-set is 0.5-5 seconds.

14. The method of claim 11, wherein the length of the heat pipe is about 70-120 m.

15. The method of any preceding claim, wherein the heat treatment, oiling and twisting are performed in a continuous manner.

16. The method of any preceding claim, further comprising winding the fibers to be heat treated onto a tube.

17. The method of any preceding claim, wherein the finishing uses a spin finish.

18. The method of any preceding claim, further comprising unwinding the fibers to be heat-set prior to the heat-setting step.

19. The method of any preceding claim, wherein the thermoplastic polyurethane has a hardness of Shore 80 A to Shore 80 D, the hardness being determined according to DIN ISO 7619-1; a hardness of Shore 80 A to Shore 74 D, the hardness Determined according to DIN ISO 7619-1; or Shore 90 A to Shore 70D, the hardness is determined according to DIN ISO 7619-1.

20. The method of any preceding claim, wherein the thermoplastic polyurethane is the reaction product of an isocyanate or salt, a polyol and a chain extender.

21. The method of claim 20, wherein the reaction is carried out in the presence of a catalyst and/or an adjuvant.

22. The method of claim 20 or 21, wherein the isocyanate or salt is selected from:

(1) from 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 2, 4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, 3,3'-dimethylbiphenyl diisocyanate, 1,2-diphenylethane diisocyanate, p-phenylene diisocyanate , trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, 1,5-diisocyanate -2-methylpentane, 1,4-diisocyanato-2-ethylbutane, 1,5-pentamethylene diisocyanate, 1,4-tetramethylene diisocyanate, isophorone Diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,4-cyclohexanediisocyanate, 1-methyl yl-2,4-cyclohexanediisocyanate, 1-methyl-2,6-cyclohexanediisocyanate, 4,4'-dicycloethylmethane diisocyanate, 2,4'-dicycloethylmethane The group consisting of diisocyanate, 2,2'-dicycloethylmethane diisocyanate, and combinations thereof;

(2) from 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 2, The group consisting of 4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and combinations thereof;

(3) consists of 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate and combinations thereof group; or

(4) The group consisting of 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate.

23. The method of any of claims 20-22, wherein the polyol:

(1) selected from the group consisting of polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols and combinations thereof;

(2) selected from the group consisting of polyester polyols, polyether polyols, and combinations thereof; or

(3) is polytetramethylene ether glycol.

24. The method of any one of claims 20-23, wherein the chain extender is selected from the group consisting of:

(1) Composed of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,10-decanediol, 1,2-cyclohexanediol Diol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol The group consisting of alcohols, bis(2-hydroxyethyl)hydroquinone, trihydric alcohols, and combinations thereof; or

(2) The group consisting of 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and combinations thereof.

25. The method of claim 24, wherein the trihydric alcohol is selected from the group consisting of 1,2,4-trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, glycerol, trimethylolpropane and its combinations.

Claims (18)

1. A method of producing thermoplastic polyurethane fibers, comprising: (1) melt-spinning a composition comprising a thermoplastic polyurethane resin to obtain fibers to be heat-set; and (2) heat setting the fibers to be heat set, wherein the heat setting step comprises heat treatment and twisting to form thermoplastic polyurethane fibers, It is characterized in that the heat treatment comprises heating the fibers to be heat-set at about 160°C to about 170°C to shrink them. 2. The method of claim 1, wherein the heat treatment is performed before the twisting. 3. The method of claim 1, wherein the heat treatment is performed after the twisting. 4. The method of claim 1 or 2, wherein the heat setting step further comprises oiling. 5. The method of claim 1, wherein the melt spinning step comprises melt spinning the composition at a spinning speed of about 2000-6500 m/min; or melt spinning the composition at a spinning speed of about 2000-5000 m/min combination. 6. The method of any preceding claim, wherein the melt spinning step comprises passing the fibers to be heatset through about 2 to about 6 godet rolls. 7. A method as claimed in the preceding claim 6, wherein the godet is a thermo roll. 8. The method of claim 5 or 6, wherein the fibers to be heat-set are passed through 3 godets. 9. The method of claim 8, wherein: (1) The temperature of the first godet of the three godet rolls is about 30°C to about 150°C; or about 60°C to about 100°C; (2) the temperature of the second of the three godet rolls is about 60°C to about 200°C; or about 100°C to about 160°C; and (3) The temperature of the third godet of the three godet rolls is about 30°C-150°C; or about 60°C-100°C. 10. The method of claim 9, wherein: (1) the speed of the first godet is about 1000-6000m/min; or about 1000-4500m/min; (2) the speed of the second godet is about 2000-6000 m/min; or about 2000-4500 m/min; and (3) The speed of the third godet is about 2000-6000 m/min; or about 2000-4500 m/min. 11. The method of any preceding claim, wherein the thermal treatment of the fibers to be heat-set comprises passing the fibers to be heat-set through a heat pipe. 12. The method of claim 11, wherein the fibers to be heat-set are passed through the heat pipe at a speed of about 20-200 m/min; or at a speed of 30-150 m/min; or at a speed of 40- A speed of 120 m/min was passed through the heat pipe. 13. The method of claim 11, wherein the heat pipe residence time of the fibers to be heat-set is 0.5-5 seconds. 14. The method of claim 11, wherein the length of the heat pipe is about 70-120 m. 15. The method of any preceding claim, wherein the heat treatment, oiling and twisting are performed in a continuous manner. 16. The method of any preceding claim, further comprising winding the fibers to be heat treated onto a tube. 17. The method of any preceding claim, wherein the finishing uses a spin finish. 18. The method of any preceding claim, further comprising unwinding the fibers to be heat-set prior to the heat-setting step.

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