EP4603625A1

EP4603625A1 - Thermoplastic polyurethane multifilament yarn for a textile product

Info

Publication number: EP4603625A1
Application number: EP24157428.4A
Authority: EP
Inventors: Ann-Christin KIEWIDT; Olaf Michel; Giacomo GIANNINI; Hugo Verbeke
Original assignee: Huntsman Europe BV; Huntsman International LLC
Current assignee: Huntsman Europe BV; Huntsman International LLC
Priority date: 2024-02-13
Filing date: 2024-02-13
Publication date: 2025-08-20
Also published as: WO2025172128A1; TW202546291A

Abstract

The present disclosure provides a thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising:(v) a thermoplastic polyurethane component;(vi) a polystyrene component;(vii) an ultraviolet absorber; and(viii) a hindered amine light stabilizer,wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material.

Description

FIELD OF THE INVENTION

The present disclosure relates to a thermoplastic polyurethane multifilament yarn for a textile product. The present disclosure also relates to a textile product comprising the thermoplastic polyurethane multifilament yarn, use of the thermoplastic polyurethane multifilament yarn in the production of a textile product, such as a shoe component (preferably a shoe upper), and a method of producing the thermoplastic polyurethane multifilament yarn.

BACKGROUND

Thermoplastic polyurethanes (TPUs) have many uses, including use in the textile industry. In particular, the TPU may be made into a filament (or fiber) to form a yarn. The yarn may then be made into a textile product such as a textile component of a shoe (e.g., a shoe upper). There are two main types of yarn, namely monofilament yarn and multifilament yarn. A monofilament yarn comprises one filament. A multifilament yarn comprises more than one filament, e.g., multiple filaments may be combined (optionally by twisting them together) to form a multifilament yarn. A textile product may be formed from either a monofilament yarn or a multifilament yarn.
A current problem with using multifilament yarns made from TPUs in the textile industry is that TPUs are typically sticky, which may make TPUs less favourable for multifilament yarn manufacturing relative to other readily available alternatives. In yarn manufacturing, a multifilament is typically formed by melt spinning, e.g., melting a TPU and extruding the molten TPU through a spinneret to form multiple filaments, followed by cooling and winding, thereby forming a multifilament yarn. However, due to the sticky nature of TPU, extruded filaments made from TPU may easily entangle once formed and therefore may not be effectively made into a multifilament yarn.
Moreover, it is desirable in the textile industry to include an ultraviolet (UV) absorber and/or a hindered amine light stabilizer into the multifilament yarns to prevent discolouration of the yarn when exposed to sunlight. Discoloration of the multifilament yarn would impact the appearance of a textile made from the yarn. However, the ultraviolet (UV) absorber and hindered amine light stabilizer are typically temperature sensitive and suffer from thermal decomposition when exposed to the temperatures required for melt spinning. The present inventors have found that when the ultraviolet (UV) absorber and/or the hindered amine light stabilizer (HALS) thermally decompose, the stickiness of the thermoplastic polyurethane filaments may increase, thereby affecting the ability to form a multifilament yarn.
Accordingly, there is a need for a TPU material which may be made into a multifilament yarn through melt spinning which does not suffer from excessive stickiness. That is, there is a need for a thermoplastic polyurethane multifilament yarn, wherein the filaments are made from a TPU material which does not suffer from excessive stickiness and wherein the filaments may be effectively made into a multifilament yarn.
The present disclosure addresses the problems and needs mentioned above, namely by adding an amount of polystyrene to a TPU, along with an ultraviolet (UV) absorber and a hindered amine light stabilizer, to form a TPU material which in turn is used to form a UV-resistant filament with a matte surface that is not sticky.

SUMMARY

In a first aspect, there is provided a thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material.
The thermoplastic polyurethane material containing from about 5 wt% to about 20 wt% of a polystyrene component allows for the production of filaments (from the thermoplastic polyurethane material) which do not have a sticky surface. Accordingly, the filaments can be effectively made into a multifilament yarn, without suffering from the adverse effects that the use of sticky filaments results in. Without being limited by theory, it is believed that the addition of a polystyrene component to the thermoplastic polyurethane component allows the melt viscosity of the resultant thermoplastic polyurethane material to be lowered and hence the extruder torque during production of a filament decreases. Also, the extrusion temperature during production of the filament can be decreased. The combination of lower extrusion temperature and lower extruder torque leads to a filament having a matte surface which is not sticky.
One purpose of the ultraviolet (UV) absorber and the hindered amine light stabilizer is to reduce discoloration of the thermoplastic polyurethane material and therefore the multifilament yarn. In particular, when aromatic isocyanate is used to produce the thermoplastic polyurethane component, a yellow discoloration may occur; the ultraviolet (UV) absorber and the hindered amine light stabilizer work to prevent such undesirable discoloration.
In one embodiment, the polystyrene component may be present in an amount of from about 8 wt% to about 12 wt%, based upon the total weight of the thermoplastic polyurethane material. The mechanical and chemical properties of the multifilament yarn are excellent when the polystyrene component is used in this amount.
In one embodiment, the polystyrene component may be a modified polystyrene. The modified polystyrene is typically made by thermal or radical polymerization of styrene containing dissolved diene compounds (such as butadiene/polybutadiene). The mechanical and chemical properties of the multifilament yarn are excellent when the polystyrene component is a modified polystyrene.
In one embodiment, the ultraviolet absorber may be present in an amount of from about 0.1 to about 1 wt%, based upon the total weight of the thermoplastic polyurethane material. The prevention of the discoloration of the thermoplastic polyurethane material is excellent when the UV absorber is used in this amount, without materially affecting the mechanical and/or chemical properties of the thermoplastic polyurethane material.
In one embodiment, the hindered amine light stabilizer may be present in an amount of from about 0.1 to about 1 wt%, based upon the total weight of the thermoplastic polyurethane material. The prevention of the discoloration of the thermoplastic polyurethane material is excellent when the hindered amine light stabilizer is used in this amount, without materially affecting the mechanical and/or chemical properties of the thermoplastic polyurethane material.
In one embodiment, the UV absorber is represented by the structure: and/or the hindered amine light stabilizer is represented by the structure: wherein n is from 1 to 25. These additives are particularly preferred due to their thermal stability, which allows the thermoplastic polyurethane material comprising the additives to be processed into multifilament yarn via e.g., melt spinning at relatively high temperatures, e.g., 220°C.
In one embodiment, each of the ultraviolet absorber and hindered amine light stabilizer does not substantially thermally decompose in the melting temperature range of the thermoplastic polyurethane material. It has been found by the inventors that some UV additives may thermally decompose at the required temperature for melt extrusion of the thermoplastic polyurethane material, which may cause an increase in stickiness of the resultant filaments.
In one embodiment, the ultraviolet absorber and/or the hindered amine light stabilizer has a relative weight loss (wt%) of less than about 2 wt% at the melting temperature of the thermoplastic polyurethane material, or less than about 5 wt% at 250°C, or less than about 10 wt% at 300°C, wherein the relative weight loss of each the ultraviolet absorber and/or the hindered amine light stabilizer is measured by thermogravimetric analysis in the temperature range of 40 to 450°C at a heating rate of 20°C/min and an air flow of 50 mL air/min, and using a test sample of 15 mg of the ultraviolet absorber or the hindered amine light stabilizer. Such relative weight losses indicate substantially no, or very little, thermal decomposition of the additives at the specified temperatures.
In one embodiment, the thermoplastic polyurethane component may be obtained from a reaction mixture comprising an aromatic isocyanate component and an isocyanate-reactive component, wherein the aromatic isocyanate component comprises methylene diphenyl diisocyanate (MDI), a prepolymer of MDI, or a combination thereof, and optionally the isocyanate-reactive component comprises a polyol. Aromatic-based polyurethanes generally suffer more from yellow discoloration due to UV.
In one embodiment, the thermoplastic polyurethane material may have a shore A hardness of at least 80, preferably 85 to 98, and more preferably 88 to 94, as measured by a Shore Durometer according to ASTM D 2240.
In a second aspect, there is provided a textile product comprising the thermoplastic polyurethane multifilament yarn as defined herein.
In a third aspect, there is provided a use of the thermoplastic polyurethane multifilament yarn as defined herein in the production of a textile product such as a shoe component, preferably a shoe upper. At least the portion of the textile product made from the thermoplastic polyurethane multifilament yarn is recyclable, which is beneficial to the environment.
In a fourth aspect, there is provided a method of producing the thermoplastic polyurethane multifilament yarn as defined herein, the method comprising the following steps: providing a thermoplastic polyurethane material as defined herein; and melt extruding the thermoplastic polyurethane material to form the multifilament yarn.
In one embodiment, the melt extrusion temperature in step (ii) may be less than the thermal decomposition temperature of each of the ultraviolet absorber and the hindered amine light stabilizer. This ensures that the additives are not thermally decomposed, which affects the stickiness of the resultant filaments.
In one embodiment, the melt extruding is a melt spinning process.
The foregoing embodiments should not be read to limit or otherwise narrow the scope of any inventive concepts otherwise provided by the present disclosure. While multiple embodiments are disclosed, other embodiments will become apparent to those skilled in the art from the following description. Accordingly, the description is to be regarded as illustrative rather than restrictive.

DETAILED DESCRIPTION

The present disclosure provides a thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material.
The present disclosure also provides a thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn comprises: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane multifilament yarn. This may be the case if there is no, or substantially no, degradation, decomposition or chemical change of the thermoplastic polyurethane material when producing the thermoplastic polyurethane multifilament yarn, that is, the composition of the thermoplastic polyurethane material is essentially the same as the composition of the thermoplastic polyurethane multifilament yarn. In one embodiment, the method of producing the thermoplastic polyurethane multifilament yarn from the thermoplastic polyurethane material does not substantially decompose or chemically change the thermoplastic polyurethane material.
The thermoplastic polyurethane material containing from about 5 wt% to about 20 wt% of a polystyrene component allows for the production of filaments (from the thermoplastic polyurethane material) which do not have a sticky surface. Accordingly, the filaments can be effectively made into a multifilament yarn, without suffering from the adverse effects that the use of sticky filaments results in. Without being limited by theory, it is believed that the addition of a polystyrene component to the thermoplastic polyurethane component allows the melt viscosity of the resultant thermoplastic polyurethane material to be lowered and hence the extruder torque during production of a filament decreases. Also, the extrusion temperature during production of the filament can be decreased. The combination of lower extrusion temperature and lower extruder torque leads to a filament having a matte surface which is not sticky.
One purpose of the ultraviolet absorber and the hindered amine light stabilizer is to reduce discoloration of the thermoplastic polyurethane material and therefore the multifilament yarn. In particular, when aromatic isocyanate is used to produce the thermoplastic polyurethane component, a yellow discoloration may occur; the ultraviolet absorber and the hindered amine light stabilizer work to prevent such undesirable discoloration.
In the context of the present disclosure, the term "multifilament yarn" refers to a yarn made from multiple (i.e. two or more, e.g. 5 to 100) filaments. The yarn must be suitable for a textile product, meaning that the yarn can be used to knit a textile product, e.g., the multifilament yarn is suitable to be used to knit a shoe upper or fabrics in furniture or an automobile. In one embodiment, a suitable denier value for the multifilament yarn may be less than 500 denier, or less than 400 denier, or less than 300 denier, or less than 200 denier, or less than 100 denier, or from 10 to 500 denier, or from 10 to 200 denier. Denier refers to the weight in grams of 9000 meters of the yarn.

[Thermoplastic polyurethane material]

The thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material. Thus, the present disclosure provides a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of about from 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material.
In one embodiment, the thermoplastic polyurethane material may be made by compounding the thermoplastic polyurethane component, the polystyrene component, the UV absorber and the hindered amine light stabilizer (along with any other components of the material) together to form the thermoplastic polyurethane material. The compounding may be achieved by any suitable process known in the art, such as melt blending the materials together. In one embodiment, the components of the thermoplastic polyurethane material are compounded together such that the components are substantially uniformly mixed. In one embodiment, the form of the thermoplastic polyurethane material may be a pellet, flake or powder, preferably a pellet.
In one embodiment, the thermoplastic polyurethane material may have a Shore A hardness of at least about 80, preferably about 85 to about 98, and more preferably about 88 to about 94, as measured by ASTM D 2240.
In the context of the present disclosure, the term "thermoplastic" refers to a material which softens and becomes pliable or mouldable upon heating to an elevated temperature, and which hardens and solidifies upon cooling. The process is reversible and can be performed several times, i.e., heating and cooling of the material may be performed multiple times.

[Thermoplastic polyurethane component]

The thermoplastic polyurethane component is not limited, and any known thermoplastic polyurethane component suitable for use in a multifilament yarn may be used.
In one embodiment, the thermoplastic polyurethane component may be obtained by reacting a reaction mixture comprising an isocyanate component, an isocyanate-reactive component and optionally a chain extender, optionally in the presence of a catalyst.
The isocyanate component is not limited, and any known isocyanate component suitable for use in producing the thermoplastic polyurethane component may be used. The isocyanate component typically is one or more compounds having the structure R-(NCO)_x, wherein x is at least 2 and R is an aromatic group, alicyclic group, an aliphatic group, or a combination thereof. The isocyanate component may comprise any one or more isocyanate compounds selected from hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene dicyclohexyl diisocyanate, cyclohexane diisocyanate, toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), tetramethylxylene diisocyanate, phenylene diisocyanate, and diphenylmethane diisocyanate (also known as methylene diphenyl diisocyanate, MDI). Any isomer of the isocyanate compounds may be used. For example, when referring to MDI, at least the isomers 2,2'-MDI, 2,4'-MDI, 4,4'-MDI or a combination thereof are referred to. In a preferred embodiment, the isocyanate component is an aromatic diisocyanate, preferably MDI.
In one embodiment, the isocyanate component may be a prepolymer of an isocyanate compound, such as a prepolymer of any of the above-mentioned isocyanate compounds. In one embodiment, the isocyanate component may be a prepolymer of MDI.
The isocyanate-reactive component is not limited, and any known isocyanate-reactive component suitable for use in producing the thermoplastic polyurethane component may be used. In one embodiment, the isocyanate-reactive component comprises one or more polyol compounds having at least two hydroxyl groups (termed "polyols" herein). In one embodiment, the polyol may be selected from any one or more of a polyether polyol, a polyester polyol, a polyether-polyester polyol, a polycaprolactone polyol and a polycarbonate polyol. In one embodiment, the polyol is a polyether polyol or a polyester polyol.
The polyether polyol may be made by the addition of alkylene oxides to initiators, which may contain from 2 to 8 active hydrogen atoms per molecule. In some embodiments, the initiators may include glycols, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose, ethylenediamine, ethanolamine, diethanolamine, aniline, toluenediamines (e.g., 2,4 and 2,6 toluenediamines), polymethylene polyphenylene polyamines, N-alkylphenylene-diamines, o-chloro-aniline, p-aminoaniline, diaminonaphthalene, or a combination thereof. Suitable alkylene oxides that may be used to form the polyether polyols include ethylene oxide (EO), propylene oxide (PO), butylene oxide, or a combination thereof.
When the alkylene oxide used to form the polyether polyol is EO and/or PO, the polyether polyol may comprise PO, EO, or a combination of PO and EO groups or moieties in the polymeric structure. These PO and EO units may be arranged randomly or in block sections throughout the polymeric structure. In some embodiments, the EO content of the polyol may range from 0 to 100% by weight based on the total weight of the polyol (e.g., 5% to 20% by weight). In some embodiments, the PO content of the polyol may range from 100 to 0% by weight based on the total weight of the polyol (e.g., 95% to 80% by weight). Accordingly, in some embodiments, the EO content of a polyol can range from 5% to 20% by weight of the polyol while the PO content can range from 80% to 95% by weight of the polyol. Moreover, in some embodiments, the EO and/or PO units can either be located terminally on the polymeric structure of the polyol or within the interior sections of the polymeric backbone structure of the polyol. Suitable polyether polyols include poly(oxyethylene oxypropylene) diols and triols obtained by the sequential addition of PO and EO to di- or tri- functional initiators that are known in the art.
Commercially available polyether polyols which may be suitable for use in the present disclosure are sold under the DALTOCEL^® tradename by Huntsman Corporation.
Other suitable polyols that may be used in the present disclosure include Mannich polyols having a nominal hydroxyl functionality of at least 2, and having at least one secondary or tertiary amine nitrogen atom per molecule. In some embodiments, Mannich polyols are the condensates of an aromatic compound, an aldehyde, and an alkanol amine. For example, a Mannich condensate may be produced by the condensation of either or both of phenol and an alkylphenol with formaldehyde and one or more of monoethanolamine, diethanolamine, and diisopropanolamine. In some embodiments, the Mannich condensates comprise the reaction products of phenol or nonylphenol with formaldehyde and diethanolamine. The Mannich condensates of the present disclosure may be made by any known process. In some embodiments, the Mannich condensates serve as initiators for alkoxylation. Any alkylene oxide (e.g., those alkylene oxides mentioned above) may be used for alkoxylating one or more Mannich condensates. When polymerization is completed, the Mannich polyol comprises primary hydroxyl groups and/or secondary hydroxyl groups bound to aliphatic carbon atoms.
The polyester polyol may be made by condensation of polyfunctional alcohols having from e.g., 2 to 12 carbon atoms with polyfunctional carboxylic acids having from e.g., 2 to 12 carbon atoms. Examples of suitable polyfunctional alcohols include, but are not limited to, ethylene glycol, diethylene glycol, butanediol, or any combination thereof. Examples of suitable polyfunctional carboxylic acids include, but are not limited to, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, or any ester or anhydride thereof.
The chain extender is not limited, and any known chain extender suitable for use to produce the thermoplastic polyurethane component may be used. The chain extender may have at least two active hydrogens in its molecule and be capable of reacting with an isocyanate compound. In one embodiment, the chain extender may have a molar mass below 500 g/mol, and is preferably a polyhydric alcohol. The chain extender may be a single chain extender or a mixture of chain extenders. Examples of suitable chain extenders include, but are not limited to, one or more of the following: ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, methylpentanediol, 1,6-hexanediol, dipropylene glycol and tripropylene glycol.
The catalyst is not limited, and any known catalyst suitable for use in producing the thermoplastic polyurethane component may be used. Examples of the catalyst may include, but are not limited to, amines such as trimethylamine, dimethylcyclohexylamine, N-methylmorpholine, and organometallic compounds such as titanium ester, iron (III) acetylacetonate and tin dialkyl salt. The skilled person would know suitable catalysts to use.
The weight average molecular weight of the thermoplastic polyurethane component is not limited. In one embodiment, the thermoplastic polyurethane component may have a weight average molecular weight (g/mol) of about 10,000 to about 1,000,000, or about 25,000 to about 800,00, or about 50,000 to about 700,000, or about 75,000 to about 500,000, as measured by gel permeation chromatography (GPC).
The skilled person would know the weight ratios or isocyanate index to mix the components of the reaction mixture in order to produce the desired thermoplastic polyurethane component.
In one embodiment, the thermoplastic polyurethane component may be obtained from a reaction mixture comprising an aromatic isocyanate component and an isocyanate-reactive component, wherein the aromatic isocyanate component comprises methylene diphenyl diisocyanate (MDI), a prepolymer of MDI, or a combination thereof, and the isocyanate-reactive component comprises a polyol.
Suitable commercially available thermoplastic polyurethane components may be sold under the tradename IROGRAN^® (available from Huntsman Corporation).
In one embodiment, the thermoplastic polyurethane component may have a softening temperature of less than about 200°C, or less than about 195°C, or less than about 190°C, or less than about 185°C, or less than about 180°C, or less than about 175°C, or less than about 170°C, or less than about 165°C, or less than about 160°C, or from about 100°C to about 250°C, or from about 110°C to about 240°C, or from about 110°C to about 230°C, or from about 120°C to about 220°C, or from about 130°C to about 210°C, or from about 140°C to about 210°C, or from about 150°C to about 210°C, as measured by thermomechanical analysis (TMA). The "softening temperature" herein refers to the temperature at which the thermoplastic first shows signs of softening in TMA.
In one embodiment, the thermoplastic polyurethane component may have a melting point range within from about 100°C to about 250°C, or from about 110°C to about 240°C, or from about 110°C to about 230°C, or from about 120°C to about 220°C, or from about 130°C to about 210°C, or from about 140°C to about 210°C, or from about 150°C to about 210°C, as measured by differential scanning calorimetry (DSC).
In one embodiment, the thermoplastic polyurethane material may contain less than about 95 wt%, or less than about 94 wt%, or less than about 93 wt%, or from about 50 wt% to less than about 95 wt% thermoplastic polyurethane component, or from about 60 wt% to less than about 95 wt% thermoplastic polyurethane component, or from about 70 wt% to about 94 wt% thermoplastic polyurethane component, or from about 80 wt% to about 94 wt% thermoplastic polyurethane component, or from about 85 wt% to about 94 wt% thermoplastic polyurethane component, or from about 86 wt% to about 94 wt% thermoplastic polyurethane component, or from about 87 wt% to about 93 wt% thermoplastic polyurethane component, or from about 88 wt% to about 92 wt% thermoplastic polyurethane component, or from about 89 wt% to about 91 wt% thermoplastic polyurethane component, based upon the total weight of the thermoplastic polyurethane material. For the avoidance of doubt, the total weight of the thermoplastic polyurethane material is 100 weight%.

[Polystyrene component]

The polystyrene component is not limited, and any known polystyrene component suitable for use in a multifilament yarn may be used. The polystyrene component may be obtained by polymerizing styrene, or by polymerizing styrene in the presence of one or more further monomers, according to processes known in the art.
In one embodiment, the polystyrene component may be a modified polystyrene, such as an impact modified polystyrene. In one embodiment, the modified polystyrene may be a polystyrene modified with an elastomer. The elastomer may be a polydiene, such as polybutadiene. In one embodiment, the polystyrene may be mixed with the elastomer (such as polybutadiene) to form the modified polystyrene. In one embodiment, the modified polystyrene may be obtained by polymerizing styrene in the presence of a diene, such as butadiene, to obtain a co-polymer. In one embodiment, a suitable modified polystyrene is a polystyrene-polybutadiene block polymer, e.g., a polystyrene-block-polybutadiene-block-polystyrene, or poly(styrene-co-butadiene). In one embodiment, the modified polystyrene may have a weight average molecular weight (g/mol) of from about 10,000 to about 200,000, or from about 30,000 to about 180,000, or from about 50,000 to about 170,000, or from about 70,000 to about 160,000, or from about 90,000 to about 160,000 or from about 100,000 to about 160,000, as measured by GPC.
A suitable commercially available modified polystyrene is available with CAS No. 9003-55-8.
The thermoplastic polyurethane material contains from about 5 wt% to about 20 wt% polystyrene component, based upon the total weight of the thermoplastic polyurethane material. In one embodiment, the thermoplastic polyurethane material may contain from about 6 wt% to about 19 wt% polystyrene component, or from about 7 wt% to about 18 wt% polystyrene component, or from about 8 wt% to about 17 wt% polystyrene component, or from about 8 wt% to about 16 wt% polystyrene component, or from about 8 wt% to about 15 wt% polystyrene component, or from about 8 wt% to about 14 wt% polystyrene component, or from about 8 wt% to about 13 wt% polystyrene component, or from about 8 wt% to about 12 wt% polystyrene component, or from about 9 wt% to about 11 wt% polystyrene component, or about 10 wt% polystyrene component, based upon the total weight of the thermoplastic polyurethane material.

[Ultraviolet absorber and hindered amine light stabilizer]

One purpose of the ultraviolet absorber and hindered amine light stabilizer is to reduce discoloration of the thermoplastic polyurethane material and therefore the multifilament yarn. In particular, when aromatic isocyanate is used to produce the thermoplastic polyurethane component, a yellow discoloration may occur; the ultraviolet absorber and hindered amine light stabilizer work to prevent such undesirable discoloration.
The ultraviolet absorber and hindered amine light stabilizer are different from each other.
It is important that the ultraviolet absorber and hindered amine light stabilizer do not affect the stickiness of the thermoplastic polyurethane filaments produced from the thermoplastic polyurethane material by a melt extrusion process. When either the UV absorber or hindered amine light stabilizer decompose, they may make the thermoplastic polyurethane sticky.
In one embodiment, each of the ultraviolet absorber and hindered amine light stabilizer does not substantially thermally decompose in the melting temperature range of the thermoplastic polyurethane material. The term "substantially" used in this context means that there is a negligible amount of thermal decomposition of the additives, such that their function is not inhibited.
In one embodiment, the ultraviolet absorber and/or the hindered amine light stabilizer may have a relative weight loss (wt%) of less than about 2 wt%, or less than about 1.9 wt%, or less than about 1.8 wt%, or less than about 1.7 wt%, or less than about 1.6 wt%, or less than about 1.5 wt%, or less than about 1.4 wt%, or less than about 1.3 wt%, or less than about 1.2 wt%, or less than about 1.1 wt%, or less than about 1 wt%, at the melting temperature of the thermoplastic polyurethane material. In this context, "melting temperature" refers to the temperature at which the material first shows signs of melting in DSC.
In one embodiment, the ultraviolet absorber and/or the hindered amine light stabilizer may have a relative weight loss (wt%) of less than about 5 wt%, or less than about 4.5 wt%, or less than about 4 wt%, or less than about 3.5 wt%, or less than about 3 wt%, or less than about 2.5 wt%, or less than about 2 wt%, or less than about 1.5 wt%, or less than about 1 wt%, at 250°C.
In one embodiment, the ultraviolet absorber and/or the hindered amine light stabilizer may have a relative weight loss (wt%) of less than about 10 wt%, or less than about 9 wt%, or less than about 8 wt%, or less than about 7 wt%, or less than about 6 wt%, at 300°C.
The relative weight loss of each of the ultraviolet absorber and/or the hindered amine light stabilizer is measured by thermogravimetric analysis (TGA) in the temperature range of 40 to 450°C at a heating rate of 20°C/min and an air flow of 50 mL air/min, and using a test sample of 15 mg of the ultraviolet absorber or hindered amine light stabilizer.
In one embodiment, the ultraviolet absorber and/or the hindered amine light stabilizer may have a relative weight loss (wt%) of less than about 1 wt% at the melting temperature of the thermoplastic polyurethane material, less than about 2 wt% at 250°C, and less than about 7 wt% at 300°C.
In one embodiment, it is preferred that the ultraviolet absorber and the hindered amine light stabilizer satisfy the relative weight losses at the varying temperatures described above.
In one embodiment, the ultraviolent absorber exhibits UV absorbance in the wavelength range of less than 400 nm.
In one embodiment, the ultraviolet absorber is represented by the following structure: wherein R1 is independently any one selected from hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkylaryl group, a substituted or unsubstituted aminoalkyl group, and a substituted or unsubstituted alkoxy group; R2 is independently any one selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkylaryl group, a substituted or unsubstituted aminoalkyl group, and a substituted or unsubstituted alkoxy group, wherein at least one R2 group is a substituted or unsubstituted alkylaryl group; X is 1, 2 or 3; Y is 1 or 2; and Z is 1, 2 or 3.
In one embodiment, X is 0, y is 1 and Z is 1 or 2, preferably 2.
In one embodiment, R₂ is independently any one selected from an alkylphenyl group or an alkyl group.
The alkyl, alkenyl and alkynyl groups herein may have from 1 to 30 carbon atoms, or from 1 to 20 carbon atoms, or from 1 to 12 carbon atoms. The aryl, alkylaryl and heterocyclic groups may have from 1 to 30 carbon atoms, or from 1 to 20 carbon atoms, or from 1 to 12 carbon atoms.
The substituent may be a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a silyl group, an alkoxy group, an amino group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, an acylamino group, an aminocarbonylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, an alkylthio group, an arylthio group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a silyloxy group, a heterocyclic oxy group, a carbamoyl group, a carbamoyloxy group, a heterocyclic thio group, a sulfamoyl group, an arylazo group, a heterocyclic azo group, an imide group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a hydrazino group, an imino group, a cyano group, a hydroxy group, a nitro group, a mercapto group, a sulfo group, a carboxy group, a hydroxamic acid group, a sulfino group, a boronate group (-B(OH)₂), a phosphato group (-OPO(OH)₂), a phosphono group (-PO(OH)₂) or a sulfate group (-OSO₃H). The alkyl, alkenyl and alkynyl groups may be linear, branched or cyclic.
In one embodiment, the molar mass of the ultraviolet absorber is below about 1000 g/mol, or below about 900 g/mol, or below about 800 g/mol, or below about 700 g/mol, or below about 600 g/mol, or below about 500 g/mol, or from about 200 g/mol to about 1000 g/mol, or from about 300 g/mol to about 700 g/mol, or from about 400 g/mol to about 600 g/mol.
In one embodiment, the hindered amine light stabilizer may be a piperidine-based compound. In one embodiment, the hindered amine light stabilizer may be derived from a dicarboxylic acid and a piperidine-based diol. The dicarboxylic acid may have from 2 to 12 carbon atoms, or from 2 to 10 carbon atoms, or from 3 to 8 carbon atoms, or from 3 to 5 carbon atoms. The dicarboxylic acid may be malonic acid, succinic acid, glutaric acid, adipic acid, or any derivative thereof, and optionally the dicarboxylic acid may contain a substituent as described herein with respect to the ultraviolet absorber. The piperidine-based diol may independently contain a hydroxy group or an alkyl group substituted with a hydroxy group, positioned on the nitrogen of the piperidine ring (1-position) as well as on the 4-position of the piperidine ring. The alkyl group may contain from 1 to 10 carbon atoms, or from 1 to 5 carbon atoms, or from 1 to 3 carbon atoms. The hindered amine light stabilizer may be an oligomer or a polymer formed from the dicarboxylic acid and a piperidine-based diol. In one embodiment, the molar mass of the hindered amine light stabilizer may be from about 1000 g/mol to about 10,000 g/mol, or from about 2000 g/mol to about 8000 g/mol, or from about 2000 g/mol to about 6000 g/mol, or from about 2500 g/mol to about 5000 g/mol.
In a preferred embodiment in terms of the thermal stability of the additives, the ultraviolet absorber is represented by the structure (1): and/or the hindered amine light stabilizer is represented by the structure (2): wherein n is from 1 to 25, preferably 3 to 20, preferably 8 to 17, preferably 8 to 16. Alternatively, "n" is such that the number average molecular weight (g/mol) of the hindered amine light stabilizer according to structure (2) may be about 3100 to about 4000 (measured by GPC). That is, the hindered amine light stabilizer may be represented by the structure (2): wherein the number average molecular weight (g/mol) of the hindered amine light stabilizer according to structure (2) may be about 3100 to about 4000 (measured by GPC).
Without being limited by theory, it is believed that the hindered amine light stabilizer according to structure (2) and the UV absorber according to structure (1) work in synergy to achieve particularly good UV protection and prevention of discolouration in multifilament yarns, when the yarns are made via melt extrusion. It appears that the hindered amine light stabilizer according to structure (2) and the UV absorber according to structure (1) are generally stable at the temperatures used in a typical melt extrusion process for producing a multifilament yarn.
A UV absorber according to structure (1) is commercially available from BASF as TINUVIN^®234, and a hindered amine light stabilizer according to structure (2) is commercially available from BASF as TINUVIN^®622.
In one embodiment, the ultraviolet absorber may be present in an amount of from about 0.1 to about 2 wt%, or from about 0.1 wt% to about 1 wt%, or from about 0.1 wt% to about 0.9 wt%, or from about 0.15 wt% to about 0.8 wt%, or from about 0.2 wt% to about 0.7 wt%, or from about 0.2 wt% to about 0.6 wt%, or from about 0.3 wt% to about 0.5 wt%, based upon the total weight of the thermoplastic polyurethane material.
In one embodiment, the hindered amine light stabilizer may be present in an amount of about 0.05 wt% to about 2 wt%, or from about 0.1 wt% to about 1 wt%, or from about 0.1 wt% to about 0.7 wt%, or from about 0.1 wt% to about 0.5 wt%, or from about 0.1 wt% to about 0.4 wt%, or from about 0.1 wt% to about 0.3 wt%, or from about 0.1 wt% to about 0.2 wt%, based upon the total weight of the thermoplastic polyurethane material.

[Further additives]

The thermoplastic polyurethane material may contain further additives which are common in the art and which are not listed above. Examples of suitable additives include antioxidants, dyeing agents or pigments, flame retardants, and the like.

[A method of producing the thermoplastic polyurethane multifilament yarn]

The thermoplastic polyurethane multifilament yarn may be made via melt extruding. Any melt extruding process known in the art may be used, as long as it is suitable for making the multifilament yarn. Melt extrusion is common in the art and the skilled person would know how to perform a suitable melt extrusion to form the multifilament described herein.
The present disclosure describes a method of producing the thermoplastic polyurethane multifilament yarn, the method comprising the following steps: (i) providing a thermoplastic polyurethane material as described herein; and (ii) melt extruding the thermoplastic polyurethane material to form the multifilament yarn.
Melt extruding involves melting the thermoplastic polyurethane material and then extruding the molten thermoplastic polyurethane material through a suitable extrusion die to form a multifilament. Parameters of the melt extruding are well known to the skilled person in the art and therefore specific details need not be included in the present disclosure.
In one embodiment, the melt extrusion temperature in step (ii) may be less than the thermal decomposition temperature of the UV absorber and/or the hindered amine light stabilizer. In this case, the UV absorber and/or the hindered amine light stabilizer do not decompose and cause the filaments to be sticky. The "the melt extrusion temperature in step (ii)" refers to the maximum temperature used in the melt extruding. The "thermal decomposition temperature of the UV absorber and/or the hindered amine light stabilizer" is the temperature at which the additive begins to substantially thermally decompose. In one embodiment, the UV absorber and/or the hindered amine light stabilizer may have a relative weight loss (wt%) of less than about 2 wt%, or less than about 1.5 wt%, or less than about 1 wt%, at the melt extrusion temperature in step (ii), as determined by the TGA method described herein.
In one embodiment, the melt extruding may be a melt spinning process. Melt spinning is a process in which the thermoplastic polyurethane material is introduced into an extruder, heated to the molten state in the extruder, and discharged in the molten state from a spinning nozzle (into the air or into a liquid) to form a multifilament. The positioning of the spinning nozzle is not limited but is preferably directed downwards so the filaments are discharged downwards. The discharged filaments are cooled and solidified while being made fine, and then taken up at a certain speed, to form a multifilament.

[A textile product comprising the thermoplastic polyurethane multifilament yarn, and use of the thermoplastic polyurethane multifilament yarn in the production of a textile product]

The multifilament yarn described herein is particularly suited for a textile product. It is important for textile products to be protected from discolouring, and therefore the multifilament yarn of the present disclosure is ideally suited for textile products.
In one embodiment, the textile product is produced by knitting the multifilament yarn into the product. In one embodiment, the textile product is a garment or footwear, preferably footwear. In one embodiment, the textile product is a shoe component, preferably a shoe upper. In one embodiment, the textile product is a fabric used in furniture or an automobile such as a car seat. The "shoe upper" as used herein refers to part or all of a section of the shoe above the sole.
Thermoplastic polyurethane is recyclable, and therefore a textile product made from the multifilament yarn of the present disclosure may be recyclable.
The present disclosure provides the use of the thermoplastic polyurethane multifilament yarn in the production of a textile product. As mentioned above, the multifilament yarn described herein is particularly suited for textile products, such as shoe components and preferably shoe uppers.

[Non-limiting embodiments]

Listed below are some preferred, but non-limiting, embodiments.
A thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material, and wherein each of the ultraviolet absorber and hindered amine light stabilizer does not substantially thermally decompose in the melting temperature range of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material, and wherein the ultraviolet absorber and/or the hindered amine light stabilizer has a relative weight loss (wt%) of less than about 2 wt% at the melting temperature of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a polystyrene component; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material, and wherein the ultraviolet absorber is represented by the structure: and/or the hindered amine light stabilizer is represented by the structure: wherein n is such that the number average molecular weight (g/mol) of the hindered amine light stabilizer according to structure (2) is from about 3100 to about 4000.
A thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a modified polystyrene, wherein the modified polystyrene is a polystyrene modified with an elastomer; (iii) an ultraviolet absorber; and (iv) a hindered amine light stabilizer, wherein the polystyrene component is present in an amount of from about 8 wt% to about 12 wt%, based upon the total weight of the thermoplastic polyurethane material,
wherein the ultraviolet absorber is represented by the structure: and/or the hindered amine light stabilizer is represented by the structure: wherein n is such that the number average molecular weight (g/mol) of the hindered amine light stabilizer according to structure (2) is from about 3100 to about 4000, and wherein the thermoplastic polyurethane component is obtained from a reaction mixture comprising an aromatic isocyanate component and an isocyanate-reactive component, wherein the aromatic isocyanate component comprises methylene diphenyl diisocyanate (MDI), a prepolymer of MDI, or a combination thereof, and the isocyanate-reactive component comprises a polyol.
A thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising: (i) a thermoplastic polyurethane component; (ii) a modified polystyrene, wherein the modified polystyrene is a polystyrene modified with an elastomer; (iii) an ultraviolet absorber according to structure (1); and (iv) a hindered amine light stabilizer according to structure (2), wherein the modified polystyrene is present in an amount of from about 8 wt% to about 12 wt%, based upon the total weight of the thermoplastic polyurethane material, wherein the ultraviolet absorber according to structure (1) is present in an amount of from about 0.1 to about 1 wt%, based upon the total weight of the thermoplastic polyurethane material, and wherein the hindered amine light stabilizer according to structure (2) is present in an amount of from about 0.1 to about 1 wt%, based upon the total weight of the thermoplastic polyurethane material, wherein the ultraviolet absorber is represented by the structure (1): and the hindered amine light stabilizer is represented by the structure (2): wherein n is such that the number average molecular weight (g/mol) of the hindered amine light stabilizer according to structure (2) is from about 3100 to about 4000, and wherein the thermoplastic polyurethane component is obtained from a reaction mixture comprising an aromatic isocyanate component and an isocyanate-reactive component, wherein the aromatic isocyanate component comprises methylene diphenyl diisocyanate (MDI), a prepolymer of MDI, or a combination thereof, and the isocyanate-reactive component comprises a polyol.

[Examples]

Reference Example 1

IROGRAN^® A92 E 4860 (commercially available from Huntsman Corporation) was used as the thermoplastic polyurethane material. IROGRAN^® A92 E 4860 is a polyester-based thermoplastic polyurethane having a Shore D hardness of 42 and a Shore A hardness of 91 (measured by ASTM D 2240), which is produced using an aromatic diisocyanate and a polyester polyol. The thermoplastic polyurethane material was formed into filaments by melt extrusion. The resultant filaments were sticky and could not be spun into a multifilament yarn.

Example 1

10 wt% modified polystyrene (polystyrene-block-polybutadiene-block-polystyrene, styrene approx. 30 wt%, weight average molecular weight (g/mol) of 140,000 by GPC; available with CAS No. 9003-55-8), 0.16 wt% TINUVIN^® 622SF (UV additive, available from BASF), 0.4 wt% TINUVIN^® 234 (UV additive, available from BASF) and remainder IROGRAN^® A92 E 4860 was used as the thermoplastic polyurethane material. The thermoplastic polyurethane material was formed into filaments by melt extrusion. The resultant filaments had a matte surface and could be spun into a multifilament yarn.
All ranges described herein are exemplary in nature and include any and all values in between. The terms "substantially", "approximately" and "about" used herein are interchangeable and refer to a measurement that includes the stated measurement and any measurements reasonably close to the stated measurement. Measurements that are reasonably close to the stated measurement deviate from the stated measurement by a reasonably small amount as understood and readily ascertained by individuals having ordinary skill in the relevant art. Such deviations may be attributable to measurement error, differences in measurement and/or manufacturing equipment calibrations, human error in reading and/or setting measurements, minor adjustments made to optimize performance and/or structural parameters in view of differences in measurement associated with other components, particular implementation scenarios, imprecise adjustment and/or manipulation of objects by a person or machine. In the event it is determined that individuals having ordinary skill in the relevant art would not readily ascertain values for such reasonably small differences, the terms "about" and "approximately" can be understood to mean plus or minus 10% of the stated value.
Throughout the description and claims, the terms take the meanings explicitly defined herein, unless the context clearly dictates otherwise.
The phrases "in one embodiment", "in an embodiment" and "in some embodiments" etc. as used herein do not necessarily refer to the same embodiment(s), though they may. Furthermore, the phrases "in another embodiment" and "in some other embodiments" as used herein do not necessarily refer to a different embodiment, though they may. All embodiments of the present disclosure are intended to be combinable.
The terms "comprises" and "comprising" mean to include but not limited to, such that further features may be present. The terms may also mean to consist of or consist essentially of.
All references and test methods cited herein are incorporated by reference in their entireties.

Claims

A thermoplastic polyurethane multifilament yarn for a textile product, wherein the thermoplastic polyurethane multifilament yarn is produced from a thermoplastic polyurethane material comprising:
(i) a thermoplastic polyurethane component;

(ii) a polystyrene component;

(iii) an ultraviolet absorber; and

(iv) a hindered amine light stabilizer,
wherein the polystyrene component is present in an amount of from about 5 wt% to about 20 wt%, based upon the total weight of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn according to Claim 1, wherein the polystyrene component is present in an amount of from about 8 wt% to about 12 wt%, based upon the total weight of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn according to Claim 1 or Claim 2, wherein the polystyrene component is a modified polystyrene.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein the ultraviolet absorber is present in an amount of from about 0.1 to about 1 wt%, based upon the total weight of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein the hindered amine light stabilizer is present in an amount of from about 0.1 to about 1 wt%, based upon the total weight of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein the ultraviolet absorber is represented by the structure: and/or the hindered amine light stabilizer is represented by the structure: wherein n is from 1 to 25.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein each of the ultraviolet absorber and hindered amine light stabilizer does not substantially thermally decompose in the melting temperature range of the thermoplastic polyurethane material.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein the ultraviolet absorber and/or the hindered amine light stabilizer has a relative weight loss (wt%) of less than about 2 wt% at the melting temperature of the thermoplastic polyurethane material, and/or less than about 5 wt% at 250°C, and/or less than about 10 wt% at 300°C, wherein the relative weight loss of each of the ultraviolet absorber and/or the hindered amine light stabilizer is measured by thermogravimetric analysis in the temperature range of 40 to 450°C at a heating rate of 20°C/min and an air flow of 50 mL air/min, and using a test sample of 15 mg of the ultraviolet absorber or hindered amine light stabilizer.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein the thermoplastic polyurethane component is obtained from a reaction mixture comprising an aromatic isocyanate component and an isocyanate-reactive component, wherein the aromatic isocyanate component comprises methylene diphenyl diisocyanate (MDI), a prepolymer of MDI, or a combination thereof.
A thermoplastic polyurethane multifilament yarn according to any preceding claim, wherein the thermoplastic polyurethane material has a Shore A hardness of at least 80, preferably 85 to 98, and more preferably 88 to 94, as measured by ASTM D 2240.
A textile product comprising the thermoplastic polyurethane multifilament yarn as defined in any preceding claim.
Use of the thermoplastic polyurethane multifilament yarn as defined in any of Claims 1-10 in the production of a textile product, such as a shoe component, preferably a shoe upper.
A method of producing the thermoplastic polyurethane multifilament yarn as defined in any of Claims 1-10, the method comprising the following steps:
(i) providing a thermoplastic polyurethane material as defined in any of Claims 1-10; and

(ii) melt extruding the thermoplastic polyurethane material to form the multifilament yarn.
A method according to Claim 13, wherein the melt extrusion temperature in step (ii) is less than the thermal decomposition temperature of each of the ultraviolet absorber and the hindered amine light stabilizer.
A method according to Claim 13 or Claim 14, wherein the melt extruding is a melt spinning process.