WO2023161074A1

WO2023161074A1 - Process of producing a multi-filament, multi-filament produced therefrom and use of the multi-filament

Info

Publication number: WO2023161074A1
Application number: PCT/EP2023/053574
Authority: WO
Inventors: De Hui YIN; Hui Zhi YAN; Qing Huai TANG; Dian Jun CHEN
Original assignee: Basf Se; Basf (China) Company Limited
Priority date: 2022-02-24
Filing date: 2023-02-14
Publication date: 2023-08-31
Also published as: WO2023160618A1

Abstract

The present invention relates to a process of producing a multi-filament by melt- spinning a composition containing a thermoplastic polyurethane, comprising: (a) passing the composition in a molten state through a spinneret, to obtain an extruded filament; (b) passing the extruded filament through a set of godet rollers; and (c) winding the extruded filament from step (b) onto a bobbin through a winder with a winding speed of 2000-5000 m/min, wherein the thermoplastic polyurethane has a Shore hardness measured according to DIN ISO 7619-1 of 68D-90D; to a multi- filament obtained from the process of the present invention; and to a use of the multi- filament of the present invention.

Description

Process of Producing a Multi-filament, Multi-filament Produced therefrom and Use of the Multi-Filament

TECHNICAL FIELD

The present invention relates to a process of producing a filament. In particular, the present invention relates to a process of producing a multi-filament from a composition containing a thermoplastic polyurethane (TPU), to a multi-filament produced from the process and to the use of the multi-filament.

BACKGROUND

Rigid TPU multi-filament, i.e., low-elasticity and high-modulus TPU multi-filament, generally has a large thermal shrinkage. An as-spun rigid TPU multi-filament usually is produced with a boiling water shrinkage (BWS) of larger than 20% or even as higher as 30%. Articles knitted by such multi-filament in turn show a great shrinkage during steaming/ironing processing, because of which the original size and hand-feeling of the articles will deteriorate.

Furthermore, the current rigid TPU multi-filament is produced with a high elongation at break, which needs special control for the filament tension in the subsequent processing steps, where even a little bit filament tension fluctuation between skeins will influence the evenness of the filament, thus generating defect to the final products.

WO 2020/169417 A1 discloses a heat-setting process to reduce the thermal shrinkage of a TPU multi-filament produced by high-speed spinning, through which the boiling water shrinkage of the multi-filament can be decreased from 30% to less than 10%. This process relies on a heat-setting stage to reduce the thermal shrinkage of the TPU multi-filament obtained from melt-spinning, which needs additional equipment and working hours, resulting in high production cost. Furthermore, heat-setting will negatively influence the evenness of the TPU filament, and will make the filament yellow during heat-setting, which is not desired especially for light color products.

In addition, the rigid TPU multi-filament produced in WO 2020/169417 A1 has high elongation at break at a relatively low winding speed. For example, the multi-filament produced in Experiment 1-1 of WO 2020/169417 A1 shows an elongation of 60%. With decreasing of the winding speed, the elongation at break is even larger. Due to the high elongation at break, the filament tension will be difficult to be controlled in the subsequent processing steps where uniformity of tension along the skeins is needed, such as winding, unwinding, twisting, knitting and some other steps. The fluctuation of the skein tension will then give rise to some defect on the obtained products, such as the multi-filaments and knitted articles prepared therefrom.

Therefore, to simplify the producing process and meanwhile to improve the product qualities, there is a strong need to provide a process of producing a TPU multi-filament with low thermal shrinkage and low elongation at break by melt-spinning a composition containing a thermoplastic polyurethane, during which the TPU multi-filament is produced in melt-spinning stage directly and without additional heat-setting stage, wherein the TPU multi-filament produced therefrom will have low thermal shrinkage and low elongation at break, will have improved filament properties such as good evenness and low defect rate, and will bring about improved article properties such as good dimensional stability, good hand-feeling and low defect rate of knitted articles from the multi-filament.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a process of producing a multifilament by melt-spinning a composition containing a thermoplastic polyurethane. The process can produce a multi-filament of low thermal shrinkage and low elongation at break and improved filament properties directly and without the need of an additional processing stage, such as heat-setting stage.

Another objective of the present invention is to provide a multi-filament produced by the process of the present invention, which has low thermal shrinkage, low elongation at break, and improved filament properties.

A further objective of the present invention is to provide a use of the multi-filament in producing articles.

It has been surprisingly found that the above objectives can be achieved by following embodiments:

1 . A process of producing a multi-filament by melt-spinning a composition containing a thermoplastic polyurethane, comprising:

(a) passing the composition in a molten state through a spinneret, to obtain an extruded filament,

(b) passing the extruded filament through a set of godet rollers, and

(c) winding the extruded filament from step (b) onto a bobbin through a winder with a winding speed of 2000-5000 m/min, preferably 2000-4000 m/min, preferably 2100-2900 m/min, more preferably 2400-2900 m/min, wherein the thermoplastic polyurethane has a Shore hardness measured according to DIN ISO 7619-1 of 68D-90D, preferably in the range from 70D-90D, more preferably in the range from 75D-88D, more preferably in the range from 81 D-87D, still more preferably in the range from 82D-86D.

2. The process of embodiment 1 , wherein the set of godet rollers in step (b) comprises a first godet roller operating at a speed of 1000-4000 m/min, preferably 1000-3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min, and preferably, the first godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C.

3. The process of embodiment 1 or 2, wherein the set of godet rollers in step (b) comprises a first godet roller, a second godet roller, and a third godet roller positioned in series, wherein: the first godet roller operates at a speed of 1000-4000 m/min, preferably 1000- 3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min; the second godet roller operates at a speed of 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2500-3500 m/min, more preferably 2600-3200 m/min; and the third godet roller operates at a speed of 2000-5000 m/min, preferably 2000- 4000 m/min, more preferably 2200-3200 m/min, more preferably 2400-3000 m/min, preferably, the speed of the second godet roller is higher than either of the first godet roller and third godet roller.

4. The process of embodiment 3, wherein the first godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C, the second godet roller operates at a surface temperature of 60-170°C, preferably 80-160°C, more preferably 90-130°C, and the third godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C, preferably, the surface temperature of the second godet roller is higher than either of the first godet roller and third godet roller.

5. The process of any one of embodiments 1 to 4, further comprising:

(a1) oiling the extruded filament with a spinning oil before step (b).

6. The process of any one of embodiments 1 to 5, wherein the thermoplastic polyurethane comprises a reaction product of:

(A) a polyol;

(B) a diisocyanate; and

(C) a chain extender, wherein the polyol is selected from the group consisting of polyether polyols, polyester polyols, and any mixture thereof.

7. A multi-filament obtained from the process of any one of embodiments 1 to 6.

8. The multi-filament of embodiment 7, wherein the boiling water shrinkage according to ASTM D2259-02 of the multi-filament is no more than 18%, preferably no more than 17%, more preferably no more than 15%, still preferably no more than 13%, still more preferably no more than 10%. 9. The multi-filament of embodiment 7 or 8, wherein the elongation at break of the multi-filament is less than 55%, such as less than 50%, such as less than 46%, such as less than 40%, at relatively low winding speed of lower than 3000 m/min, measured according to IS02062:2009, method A.

10. The multi-filament of any one of embodiments 7 to 9, which is of bi-component structure or micro tube structure.

11. Use of the multi-filament of any one of embodiments 7 to 10 in producing clothes, shoes, or accessories, such as shoes, pants, T-shirt, chair mesh, watch band, or hair band.

The TPU multi-filament produced by the process of the present invention has low thermal shrinkage and low elongation at break, has improved filament properties such as good evenness and low defect rate, and brings about improved article properties such as good dimensional stability, good hand-feeling and low defect rate of articles from the multi-filament, such as knitted articles from the multi-filament, wherein the TPU multi-filament is produced by the process of the invention directly and without the need of an additional heat-setting stage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of an apparatus for melt-spinning of TPU multi-filaments.

DETAILED DESCRIPTION OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.

The articles “a”, “an” and “the” mean one or more of the species designated by the term following said article.

In the context of the present disclosure, any specific values mentioned for a feature (comprising the specific values mentioned in a range as the end point) can be recombined to form a new range.

Further embodiments of the present invention are discernible from the claims, the description, and the examples. It will be understood that the aforementioned and hereinbelow still to be elucidated features of the subject matter of the present invention are utilizable not only in the particular combination indicated, but also in other combinations without leaving the realm of the present invention. Process of producing a multi-filament

One aspect of the present invention relates to a process of producing a multi-filament by melt-spinning a composition containing a thermoplastic polyurethane, comprising:

(a) passing the composition in a molten state through a spinneret, to obtain an extruded filament and

(b) passing the extruded filament through a set of godet rollers, and

The process of the present invention comprises step (a) passing the composition containing a thermoplastic polyurethane in a molten state through a spinneret, to obtain an extruded filament.

Step (a) of the process of the present invention is not particularly limited and can be carried out by a skilled person. Melt-spinning is a technique in which a raw material composition in a molten state obtained by heating the raw material composition to a temperature equal to or higher than the melting point by using an extruder or the like is discharged from a spinneret into an atmosphere (for example, into the air or into the air cooled if necessary). The positioning of the spinneret is not limited. However, it is preferable to direct the spinneret downward so that the molten composition (the molten filament) is discharged downward (drawn down). The discharged molten filament is cooled and solidified in the atmosphere while being made fine, and then is taken up at a certain speed. There may be a multiplicity of spinnerets set in any group or pattern. When multiple spinnerets are used, the composition exiting the spinnerets may be guided by a mechanical mechanism and form an extruded filament. The number of the spinnerets is not limited.

The atmosphere for the melt-spinning is not particularly limited, and may be various atmospheres such as an inert atmosphere and the ambient atmosphere, and preferably the ambient atmosphere (air) from the viewpoint of the cost. The temperature of the atmosphere can be any temperature lower than the melting point of the raw material composition, for example is from -10 °C to 50 °C and more preferably from 10 °C to 40 °C (in consideration of the cost).

It is also possible to melt a main component (the thermoplastic polyurethane of the present invention) of the raw material composition separately from other component(s) (if any) of the raw material composition so that the molten main component is mixed with other component(s) just before being discharged from the spinneret. The apparatus for producing a multi-filament by melt-spinning is not particularly limited and is known by a skilled person. An example of such apparatus is illustrated in figure 1. Generally, the apparatus for melt-spinning includes an extruder (not shown), a spinning package, godet rollers (such as GR1 , GR2 and GR3) and a winder. The spinning package is known in the art, and primarily consists of melt reservoir and spinneret.

When using one or more additives (the other components) such as a crosslinker, at least one mixer such as a static or a dynamic mixer, preferably a static mixer may be provided in the apparatus. In this case, the main component comprising the TPU, in one preferred embodiment consisting of the TPU, is molten in the extruder separately from the crosslinker; the crosslinker is mixed with the molten main component by using the mixer; and then the mixed composition in a molten state (i.e., the raw material composition in the molten state) is discharged from the nozzle of the spinning head. The TPU of the raw material composition is crosslinked with the crosslinker during the melt spinning process. Or else, the dried TPU granules are melted in the extruder and the crosslinker (0-20%) is fed at end of the extruder. The blend of crosslinker and TPU melt passes through the mixer and the melt pipeline, and after metering, it is pressed into the spinning package, and finally exits the spinneret.

Spinning temperature is a parameter of the spinning conditions for melt-spinning. The spinning temperature is defined as, for example, the heating temperature not only in the extruder, but also that in the raw material composition pipe and in the spinning package. The spinning temperature is not particularly limited, and can be appropriately varied according to the melting point of the raw material composition. From the viewpoint of spinnability, in the present invention, the spinning temperature is preferably 225°C or higher, but preferably no higher than 250°C, such as no higher than 240°C. Especially when using a TPU having high hardness (for example, more than shore 68D), a higher spinning temperature (for example, 225°C or more) enables the spinning at a higher spinning speed. From the viewpoint of the suppression of the thermal decomposition of the raw material composition, the spinning temperature is usually 240°C or lower, and preferably 235°C or lower.

After exiting the spinneret, the extruded filament is sent to step (b) for being drawn or oriented by passing through a set of godet rollers.

In step (b), the extruded filament passes through a set of godet rollers. The set of godet rollers in step (b) of the process of the present invention may comprises two or more godet rollers positioned in series. Preferably, the set of godet rollers in step (b) comprises a first godet roller operating at a speed of 1000-4000 m/min, preferably 1000-3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min. In a preferable embodiment of the invention, the first godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C. The operating speed of godet roller(s) after the first godet roller can be chosen by a skilled person. In a preferable embodiment of the invention, the set of godet rollers in step (b) comprises a first godet roller (GR1), a second godet roller (GR2), and a third godet roller (GR3) positioned in series. Preferably, godet rollers operate at speeds as follows, respectively:

GR1 : 1000-4000 m/min, preferably 1000-3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min;

GR2: 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2500-3500 m/min, more preferably 2600-3200 m/min; and

GR3: 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2200-3200 m/min, more preferably 2400-3000 m/min.

Preferably, the speed of the second godet roller is higher than either of the speed of the first godet roller and the speed of the third godet roller.

According to the TPU materials and/or end application, more godet rollers may be used. For example, the set of godet rollers in step (b) may include four or more godet rollers. In an embodiment of the invention, in addition to the first godet roller, the second godet roller, and the third godet roller, the set of godet rollers in step (b) of the process of the present invention may further comprise 1 , 2 or 3 godet rollers.

In an embodiment of the invention, the number of the godet rollers for step (b) of the process of the present invention is 3, i.e., only the first godet roller, the second godet roller, and the third godet roller are used in step (b) of the process of the present invention.

In the present invention, the “speed of a godet roller” and the “operating speed of a godet roller” are used interchangeable, which refer to the peripheral speed of the godet roller, unless otherwise indicated.

The surface temperature of the godet rollers in step (b) of the present invention can be chosen by a skilled person. In an embodiment, the set of godet rollers in step (b) comprises the first godet roller, the second godet roller, and the third godet roller positioned in series, wherein the first godet roller operates with a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C, the second godet roller operates with a surface temperature of 60-170°C, preferably 80-160°C, more preferably 90-130°C, and the third godet roller operates with a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C.

Preferably, the surface temperature of the second godet roller is higher than either of the surface temperature of first godet roller and the surface temperature of the third godet roller. In an embodiment, in step (b) of the process of the present invention, the surface temperatures and speeds of the first godet roller (GR1), second godet roller (GR2) and third godet roller (GR3) are as follows, respectively:

GR1 : the surface temperature is 30-120°C, preferably 50-100°C, more preferably 60- 90°C, and independently, the speed is 1000-4000 m/min, preferably 1000-3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min

GR2: the surface temperature is 60-170°C, preferably 80-160°C, more preferably 90- 130°C, and independently, the speed is 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2500-3500 m/min, more preferably 2600-3200 m/min, GR3: the surface temperature is 30-120°C, preferably 50-100°C, more preferably 60- 90°C, and independently, the speed is 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2200-3200 m/min, more preferably 2400-3000 m/min.

Preferably, in step (b) of the process of the present invention, the surface temperatures and speeds of the first godet roller (GR1), second godet roller (GR2) and third godet roller (GR3) are as follows, respectively,

GR1 : the surface temperature is 30-120°C, preferably 50-100°C, more preferably 60- 90°C, and independently, the speed is 1100-2300 m/min, more preferably 1200-2100 m/min,

The process of the invention further comprises step (c) winding the filament from step (b) onto a bobbin through a winder with a winding speed of 2000-5000 m/min, preferably 2000-4000 m/min, preferably 2100-2900 m/min, more preferably 2400-2900 m/min.

In a preferable embodiment of the present invention, the process of producing a multifilament by melt-spinning a composition containing a thermoplastic polyurethane comprises:

(a) passing the composition in a molten state through a spinneret, to obtain an extruded filament

(b) passing the extruded filament through a set of godet rollers, and

(c) winding the extruded filament from step (b) onto a bobbin through a winder with a winding speed of 2100-2900 m/min, more preferably 2400-2900 m/min, wherein the thermoplastic polyurethane has a Shore hardness measured according to DIN ISO 7619-1 of 68D-90D, preferably in the range from 70D-90D, more preferably in the range from 75D-88D, more preferably in the range from 81 D-87D, still more preferably in the range from 82D-86D. In a more preferable embodiment of the present invention, the process of producing a multi-filament by melt-spinning a composition containing a thermoplastic polyurethane comprises:

(b) passing the extruded filament through a set of godet rollers, and

(c) winding the extruded filament from step (b) onto a bobbin through a winder with a winding speed of 2100-2900 m/min, more preferably 2400-2900 m/min, wherein the thermoplastic polyurethane has a Shore hardness measured according to DIN ISO 7619-1 of 81 D-87D, more preferably in the range from 82D-86D.

In a more preferable embodiment of the present invention, the process of producing a multi-filament by melt-spinning a composition containing a thermoplastic polyurethane comprises:

(b) passing the extruded filament through a set of godet rollers comprising a first godet roller operating at a speed of 1100-2300 m/min, more preferably 1200-2100 m/min, at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C, and

In a still more preferable embodiment of the present invention, the process of producing a multi-filament by melt-spinning a composition containing a thermoplastic polyurethane comprises:

(b) passing the extruded filament through a set of godet rollers comprising a first godet roller (GR1), a second godet roller (GR2) and a third godet roller (GR3) positioned in series, wherein the surface temperatures and speeds of the first godet roller (GR1), second godet roller (GR2) and third godet roller (GR3) are as follows, respectively,

GR1 : the surface temperature is 30-120°C, preferably 50-100°C, more preferably 60-90°C, and independently, the speed is 1100-2300 m/min, more preferably 1200-2100 m/min,

GR2: the surface temperature is 60-170°C, preferably 80-160°C, more preferably 90-130°C, and independently, the speed is 2000-5000 m/min, preferably

2000-4000 m/min, more preferably 2500-3500 m/min, more preferably 2600-3200 m/min,

GR3: the surface temperature is 30-120°C, preferably 50-100°C, more preferably 60-90°C, and independently, the speed is 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2200-3200 m/min, more preferably 2400-3000 m/min, preferably the speed of the second godet roller is higher than either of the speed of the first godet roller and the speed of the third godet roller, and the surface temperature of the second godet roller is higher than either of the surface temperature of the first godet roller and the surface temperature of the third godet roller, and

Optionally and preferably, after exiting the spinneret and before reaching the godet rollers, the extruded filament may be oiled. The oiling step could lubricate the filament and reduce the friction between the filament and the metallic/ceramic parts of the spinning line; allow dissipation of the static charges generated due to contact of filament with the machine parts; and keep the filaments together, so that unwinding from the spun cake becomes easier. The filament may be oiled by any conventional spinning oil.

Thickness of the rigid TPU multi-filament obtained from the process of the present invention can be controlled in the range of 2-70 DPF (denier per filament) according to different applications, for example in the range of 2 to 50 DPF, or 2 to 40 DPF, or 2 to 30 DPF, or 2 to 20 DPF, or 2 to 10 DPF, measured according to 1502060:1994. Thermoplastic polyurethane

The thermoplastic polyurethane used in the process of the present invention comprises reaction product of (A) a polyol; (B) a diisocyanate; and (C) a chain extender.

The thermoplastic polyurethane used in the process of the present invention is generally obtained, without being particularly limited, by allowing the polyol, the diisocyanate and the chain extender as the essential components to react with each other, if necessary, in the presence of a catalyst and/or an aid (auxiliary agent). The reaction can be a one-stage reaction allowing the whole of the essential components to react with each other in one stage in a preferred embodiment in the presence of the optional components such as a catalyst and/or an aid (auxiliary agent), or a reaction having a plurality of stages allowing some of the polyol and the diisocyanate to react with each other to form a prepolymer and then allowing the prepolymer and the rest of the essential components to react with each other, preferably in the presence of a catalyst and/or an aid (auxiliary agent).

Examples of the catalyst in the reaction, if used, may be selected from, without being particularly limited to: trimethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N’- dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo(2,2,2)octane and the analog thereof; in particular, organometallic compounds such as titanium ester; iron compounds such as iron (III) acetylacetonate; tin compounds such as tin diacetate, tin dioctoate and tin dilaurate; and tin dialkyl salts of aliphatic carboxylic acids such as dibutyltin diacetate and dibutyltin dilaurate and the equivalents thereof. The amount of the catalyst for the reaction can be determined by a skilled person according to practical application.

Examples of the auxiliary agent, a may be selected from, without being particularly limited to: a surfactant, a nucleating agent, a gliding and demolding aid, a dye, a pigment, an antioxidant (for example, in relation to hydrolysis, light, heat and discoloration), an ultraviolet absorber, a flame retardant, a reinforcing agent, a plasticizer or a flowability improver and a cross-linking agent; one or more selected from these can be used. The amount of the auxiliary agent can be determined by a skilled person according to practical application.

The thermoplastic polyurethane used in the process of the present invention has a Shore hardness measured according to DIN ISO 7619-1 of 68D-90D, preferably in the range from 70D-90D, more preferably in the range from 75D-88D, more preferably in the range from 81 D-87D, still more preferably in the range from 82D-86D.

The thermoplastic polyurethane used in the process of the present invention may have a weight-average molecular weight in the range of 50,000 to 400,000, preferably 60,000 to 300,000, such as 80,000 to 200,000g/mol. The thermoplastic polyurethane used in the process of the present invention has (A) a polyol as one of the raw materials.

As the polyol used in the present invention, compounds generally known as isocyanate reactive compounds can be used. In particular, the polyol used in the present invention may be selected from the group consisting of polyester polyols, polyether polyols, and any mixture thereof.

Preferably, the functionality of the polyol used in the present invention is in the range from 1.5 to 2.5, preferably 1.8 to 2.3, more preferably 1.9 to 2.1 , for example 2.

The polyether polyols may be obtained by known methods, for example by polymerization of alkylene oxides with addition of at least one starter molecule which comprises from 2 to 8, preferably from 2 to 6, reactive hydrogen atoms in the presence of a catalyst. As the catalyst, it is possible to use alkali metal hydroxides such as sodium or potassium hydroxide or alkali metal alkoxides such as sodium methoxide, sodium or potassium ethoxide or potassium isopropoxide or, in the case of cationic polymerization, Lewis acids such as antimony pentachloride, boron trifluoride etherate or bleaching earth as the catalyst. Furthermore, double metal cyanide compounds, known as DMC catalysts, can also be used as the catalyst.

As the alkylene oxide, preference is given to using one or more compounds having from 2 to 4 carbon atoms in the alkylene radical, e.g., ethylene oxide, 1 ,3-propylene oxide, tetrahydrofuran, 1 ,2- or 2,3-butylene oxide, in each case either alone or in the form of mixtures, and preferably ethylene oxide, 1 ,2-propylene oxide and/or tetrahydrofuran, most preferably tetrahydrofuran.

Possible starter molecules are, for example, ethylene glycol, diethylene glycol, glycerol, trimethylolpropane, pentaerythritol, sugar derivatives such as sucrose, sugar alcohol such as sorbitol, methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, toluenediamine, naphthylamine, ethylenediamine, diethylenetriamine, 4,4'-methylenedianiline, 1 ,3-propanediamine, 1 ,6-hexanediamine, ethanolamine, diethanolamine, triethanolamine and other dihydric or polyhydric alcohols or monofunctional or polyfunctional amines.

Examples of polyether polyols can also include a ring-opening polymer of tetrahydrofuran (polytetramethylene glycol, PTMEG), natural oil-based polyether polyols like alkoxylated castor oil or other polyether polyols based on natural oils or fats, e.g., those obtained by ring opening reaction of epoxidized unsaturated vegetable oils, polyether polyols based on saccharides.

The polyester polyol may be prepared by condensation of polyfunctional alcohols having from 2 to 12 carbon atoms with polyfunctional carboxylic acids having from 2 to 12 carbon atoms. The polyfunctional alcohols or polyfunctional carboxylic acids may have a functionality of around 2. The examples of the polyfunctional alcohols may be ethylene glycol, diethylene glycol, butanediol, or a combination thereof. The examples of the polyfunctional carboxylic acids may be succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, the isomers of naphthalenedicarboxylic acids, or the ester or anhydrides of the acids mentioned.

Preferably, the polyol used in the present invention is selected from the group consisting of polyester diols, polyether diols, and any mixture thereof.

The thermoplastic polyurethane used in the process of the present invention has (B) a diisocyanate as one of the raw materials.

Diisocyanate of the present invention may be selected from any organic compound having two isocyanate groups per molecule.

Diisocyanate of the present invention may be an aliphatic diisocyanate, or araliphatic diisocyanate, or cycloaliphatic diisocyanate, or aromatic diisocyanate.

For example, the diisocyanate may contain from 3 to 40 carbon atoms, and in various embodiments, the diisocyanate may contain from 4 to 20, from 5 to 24, or from 6 to 18, carbon atoms. In certain embodiments, the diisocyanate is a symmetrical aliphatic or cycloaliphatic diisocyanate.

Preferred examples of suitable diisocyanates of the present invention include isomers of diphenylmethane diisocyanates, 1 ,5-naphthylene diisocyanate, isomers of tolylene diisocyanates, 3,3'-dimethyldiphenyl diisocyanate, 1 ,2-diphenylethane diisocyanate, phenylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, 2-methylpentamethylene- 1 ,5-diisocyanate, 2-ethylbutylene-1 ,4-diisocyanate, isophorone diisocyanate, isomers of bis(isocyanatomethyl)cyclohexanes, 1-methyl-2,4-cyclohexane diisocyanate, 1- methyl-2,6-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'- dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, and any mixture thereof; more preferably the diisocyanate is selected from the group consisting of isomers of diphenylmethane diisocyanates, 1 ,5-naphthylene diisocyanate, isomers of tolylene diisocyanates, hexamethylene diisocyanate, isophorone diisocyanate, and any mixture thereof; in particular, the diisocyanate is diphenylmethane diisocyanate, hexamethylene diisocyanate, and any mixture thereof, especially 4,4’-diphenylmethane diisocyanate. In an embodiment of the invention, only one diisocyanate is used.

Chain extender

The thermoplastic polyurethane used in the process of the present invention has (C) a chain extender as one of the raw materials.

Chain extender of the present invention may comprise aliphatic, araliphatic, aromatic, and/or cycloaliphatic compounds having two or three functional groups. For example, the chain extender suitable for the present invention may be selected from bifunctional or trifunctional amines and alcohols, in particular diols, triols or both, such as diamines and/or alkanediols having from 2 to 10 carbon atoms in the alkylene radical.

As examples of the chain extender suitable for the present invention, it may be mentioned ethylene glycol, 1 ,2-propanediol, 1 ,3-propanediol, 1 ,4-butanediol, 1 ,2- pentanediol, 1 ,3-pentanediol, 1 ,10-decanediol, 1 ,2-dihydroxycyclohexane, 1 ,3- dihydroxycyclohexane, 1 ,4-dihydroxycyclohexane, diethylene glycol and triethylene glycol, dipropylene glycol and tripropylene glycol, 1 ,6-hexanediol and bis(2- hydroxyethyl) hydroquinone; triols such as 1 ,2,4-trihydroxycyclohexane, 1 ,3,5- trihydroxycyclohexane, glycerol and trimethylolpropane. A particularly preferable chain extender includes 1 ,3-propanediol, 1 ,4-butanediol, or 1 ,6-hexanediol. In certain cases, it is possible to use the mixture of two chain extenders.

Preferably, in order to form the thermoplastic polyurethane of the present invention, the polyol, the diisocyanate, and the chain extender are used with the molar ratio of isocyanate groups from the diisocyanate to the isocyanate-reactive groups from both the polyol and the chain extender, in the range from 0.9: 1.0 to 1.1 : 1.0, preferably from 0.95: 1.0 to 1.05: 1.0, and more preferably from 0.97: 1 .0 to 1.03: 1.0.

Multi-filament of the present invention

The multi-filament of the present invention is produced from a composition containing the thermoplastic polyurethane discussed above. Preferably, the composition used in the process of the present invention essentially consists of the thermoplastic polyurethane. The term "essentially consists of" means that the composition contains the thermoplastic polyurethane and optionally unintended materials such as residues, contaminants or the like. In other words, the composition contains 95 % by weight (wt.%) or more of the thermoplastic polyurethane, preferably 99 wt.% or more, or preferably 99.5 wt.% or more, especially 99.9 wt.% or more, even 100 wt.% of the thermoplastic polyurethane.

The multi-filament obtained from the process of the present invention has greatly lowered boiling water shrinkage and greatly lowered elongation at break, has improved filament properties such as good evenness and low defect rate, and brings about improved properties for the articles prepared from the multi-filament, such as good dimensional stability, good hand-feeling and low defect rate of the articles, such as knitted articles, from the multi-filament.

Preferably, the multi-filament obtained from the process of the present invention has the boiling water shrinkage according to ASTM D2259-02 of no more than 18%, preferably no more than 17%, preferably no more than 15%, still preferably no more than 13%, more preferably no more than 10%.

Preferably, the multi-filament obtained from the process of the present invention has the elongation at break at relatively low winding speed of lower than 3000 m/min, according to IS02062:2009 method A, of less than 55%, such as less than 50%, such as less than 46%, such as less than 40%.

In some embodiments of the invention, the multi-filament obtained from the process of the present invention is of bi-component structure or micro tube structure.

The multi-filament obtained from the process of the present invention may find uses in various applications. For example, the multi-filament obtained from the process of the present invention is well suitable for manufacturing fabric. Such manufactured fabric may be used in producing articles such as knitted or wove articles, for example clothes, shoes, or accessories, e.g., shoes, pants, T-shirts, chair meshes, watch bands, or hair bands.

Moreover, the multi-filament obtained from the process of the present invention has very low boiling water shrinkage, which makes it well suitable as the main raw material in fabrics. Therefore, the size and haptics of the fabrics produced by the multi-filament could be well controlled during steaming or ironing process.

By using super hard TPU with hardness in the range of 68D-90D in the process of the present invention, boiling water shrinkage (BWS) of the obtained multi-filaments can be decreased to smaller than 20% as measured according to ASTM D2259-02, without the need of heat setting process after the spinning. By further increasing the hardness to more than 75D, the BWS of the obtained multi-filaments can be controlled to smaller than 15%. Furthermore, if the hardness exceeds 80D, a very low BWS of smaller than 10% can be achieved.

By using super hard TPU in the process of the present invention for multi-filament production, elongation at break of the obtained multi-filaments can also be decreased, which can be less than 60% or even less than 40% at relatively low winding speed of lower than 3000 m/min, as measured according to IS02062:2009, method A.

The multi-filament of the present invention is produced by the process of the invention directly without additional heat-setting stage. Because of omitting a heat-setting stage, for producing a multi-filament of lowered boiling water shrinkage and lowered elongation at break and improved filament properties, the present invention also provides a simplified process, as compared with conventional process.

Examples

The present invention will be better understood in view of the following non-limiting examples.

Abbreviations

MDI: diphenylmethane diisocyanate

PTMEG: polytetramethylene ether glycol

PBA: poly(1 ,4-butylene adipate) diol

PM MA: polymethyl methacrylate

Materials

The TPU materials used in the examples are as follows.

Hard TPU:

TPU 1 (obtained from BASF, with a hardness of 62D) with weight-average molecular weight of 80 000-120 000 based on PTMEG with number-average molecular weight of 1000, MDI and 1,4-butanediol was used for preparing the filaments.

Super hard TPU:

TPU 2 (obtained from BASF, with a hardness of 70D) with weight-average molecular weight of 100 000-150 000 based on PBA with number-average molecular weight of 1000, MDI and 1,4-butanediol was used for preparing the filaments

TPU 3, TPU 4, and TPU 5 (obtained from BASF, with a hardness of 74D, 78D and 83D, respectively) with weight-average molecular weight of 80 000-120 000 based on PTMEG with number-average molecular weight of 1000, MDI and 1 ,4-butanediol were used for preparing the filaments.

Measuring and test methods:

In the present invention, the weight-average molecular weight of the thermoplastic polyurethane is measured by gel permeation chromatography (GPC) based on DIN 55672-1 (date: August 2007). The procedures are according to specifications as below:

The calibration plot (5th-order polynomial) is constructed from the PMMA standards with different molecular weights, by determining the respective retention time of the individual PMMA standards for the analysis series.

Sample was dissolved in a mixture of 99wt.% DMF and 1wt.% di-n-butylamine at 4mg/mL for at least 18 h, filtered by 0.45 pm membrane filter before injection.

Process of producing a multi-filament sample

In examples, TPU materials stated above were used for melt-spinning.

The multi-filament samples in the examples were produced by a process comprising:

(a) passing a TPU composition in a molten state at a temperature of 230°C through a spinneret, to obtain an extruded TPU filament,

(a1) oiling the extruded TPU filament from step (a) with a spinning oil with the brand name “Delion F-1782” from Takemoto Oil & Fat Co., Ltd,

(b) passing the extruded TPU filament from step (a1 ) through a set of godet rollers comprising a first godet roller (GR1), a second godet roller (GR2), and a third godet roller (GR3) positioned in series, and

(c) winding the TPU filament from step (b) onto a bobbin through a winder with a defined winding speed to obtain the final multi-filament sample.

The composition, parameters of the process and results of the multi-filament sample of each example are provided in table 1.

Table 1

Claims

(b) passing the extruded filament through a set of godet rollers, and

2. The process of claim 1 , wherein the set of godet rollers in step (b) comprises a first godet roller operating at a speed of 1000-4000 m/min, preferably 1000-3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min, and preferably, the first godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C.

3. The process of claim 1 or 2, wherein the set of godet rollers in step (b) comprises a first godet roller, a second godet roller, and a third godet roller positioned in series, wherein: the first godet roller operates at a speed of 1000-4000 m/min, preferably 1000- 3000 m/min, more preferably 1100-2300 m/min, more preferably 1200-2100 m/min; the second godet roller operates at a speed of 2000-5000 m/min, preferably 2000-4000 m/min, more preferably 2500-3500 m/min, more preferably 2600-3200 m/min; and the third godet roller operates at a speed of 2000-5000 m/min, preferably 2000- 4000 m/min, more preferably 2200-3200 m/min, more preferably 2400-3000 m/min, preferably, the speed of the second godet roller is higher than either of the speed of the first godet roller and the speed of the third godet roller.

4. The process of claim 3, wherein the first godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C, the second godet roller operates at a surface temperature of 60-170°C, preferably 80-160°C, more preferably 90-130°C, and the third godet roller operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C, preferably, the surface temperature of the second godet roller is higher than either of the surface temperature of the first godet roller and the surface temperature of the third godet roller.

5. The process of any one of claims 1 to 4, further comprising:

(a1) oiling the extruded filament with a spinning oil before step (b).

6. The process of any one of claims 1 to 5, wherein the thermoplastic polyurethane comprises a reaction product of:

(A) a polyol;

(B) a diisocyanate; and

7. A multi-filament obtained from the process of any one of claims 1 to 6.

8. The multi-filament of claim 7, wherein the boiling water shrinkage according to ASTM D2259-02 of the multi-filament is no more than 18%, preferably no more than 17%, more preferably no more than 15%, still preferably no more than 13%, still more preferably no more than 10%.

9. The multi-filament of claim 7 or 8, wherein the elongation at break of the multifilament is less than 55%, such as less than 50%, such as less than 46%, such as less than 40%, at relatively low winding speed of lower than 3000 m/min, measured according to 1802062:2009, method A.

10. The multi-filament of any one of claims 7 to 9, which is of bi-component structure or micro tube structure.

11. Use of the multi-filament of any one of claims 7 to 10 in producing clothes, shoes, or accessories, such as shoes, pants, T-shirt, chair mesh, watch band, or hair band.