CN118786258A - Method for producing multifilament yarn, multifilament yarn produced thereby and use of the multifilament yarn - Google Patents

Abstract

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

Description

Method for producing multifilament yarn, multifilament yarn produced thereby and use of the multifilament yarn

Technical Field

The present invention relates to a method for producing filaments. In particular, the present invention relates to a method for producing multifilaments from a composition containing thermoplastic polyurethane (TPU), the multifilaments produced by the method and the use of the multifilaments.

Background Art

Rigid TPU multifilaments, i.e., TPU multifilaments with low elasticity and high modulus, generally have a large heat shrinkage. As-spun rigid TPU multifilaments are generally produced to have a boiling water shrinkage (BWS) greater than 20% or even up to 30%. Articles woven from such multifilaments will then show a large shrinkage during the steaming/ironing process, and therefore, the original size and feel of these articles will be deteriorated.

Furthermore, current rigid TPU multifilaments are produced with high elongation at break, which requires special control of the filament tension in subsequent processing steps, where even a slight fluctuation in filament tension between hanks can affect the uniformity of the filaments, thereby creating defects in the final product.

WO 2020/169417 A1 discloses a heat setting method to reduce the heat shrinkage of TPU multifilaments produced by high-speed spinning, by which the boiling water shrinkage of the multifilaments can be reduced from 30% to less than 10%. The method relies on a heat setting stage to reduce the heat shrinkage of the TPU multifilaments obtained by melt spinning, which requires additional equipment and working time, resulting in high production costs. In addition, heat setting will have a negative impact on the uniformity of the TPU filaments, and will cause the filaments to turn yellow during the heat setting process, which is particularly undesirable for light-colored products.

In addition, the rigid TPU multifilament produced in WO 2020/169417 A1 has a high elongation at break at a relatively low winding speed. For example, the multifilament produced in Experiment 1-1 of WO 2020/169417 A1 showed an elongation of 60%. As the winding speed decreases, the elongation at break is even greater. Due to the high elongation at break, it will be difficult to control the filament tension in subsequent processing steps (such as winding, unwinding, twisting, weaving, and some other steps) in which uniformity of tension along the skein is required. Fluctuations in the skein tension will cause some defects in the obtained products such as multifilaments and woven products prepared therefrom.

Therefore, in order to simplify the production process and improve the product quality at the same time, it is urgently needed to provide a method for producing TPU multifilaments with low heat shrinkage and low elongation at break by melt spinning a composition containing thermoplastic polyurethane, during which the TPU multifilaments are directly produced in the melt spinning stage without an additional heat setting stage, wherein the TPU multifilaments produced therefrom will have low heat shrinkage and low elongation at break, will have improved filament properties such as good uniformity and low defect rate, and will bring improved product properties such as good dimensional stability, good feel and low defect rate of woven products from the multifilaments.

Summary of the invention

The object of the present invention is to provide a method for producing multifilament yarns by melt spinning a composition containing thermoplastic polyurethane, which method can directly produce multifilament yarns with low heat shrinkage and low elongation at break and improved filament properties without the need for additional processing stages, such as heat setting stages.

Another object of the present invention is to provide a multifilament produced by the method of the present invention, the multifilament having low heat shrinkage, low elongation at break and improved filament properties.

Another object of the present invention is to provide the use of the multifilament in the production of articles.

It has been unexpectedly found that the above objects can be achieved by the following embodiments:

1. A method for producing multifilament yarn by melt spinning a composition containing thermoplastic polyurethane, the method comprising:

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

(b) passing the extruded filaments through a set of godet rolls, and

(c) winding the extruded filaments from step (b) onto a bobbin through a winder at 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 of 68D-90D, preferably in the range of 70D-90D, more preferably in the range of 75D-88D, more preferably in the range of 81D-87D, still more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1.

2. The method of embodiment 1, wherein the godet roller set in step (b) comprises a first godet roller running 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 operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C.

3. The method of embodiment 1 or 2, wherein the godet set in step (b) comprises a first godet, a second godet and a third godet arranged in series, wherein:

The first godet roll runs 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 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 roll runs 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 is higher than any of the first godet and the third godet.

4. The method of embodiment 3, wherein:

The first godet operates at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C,

The second godet operates at a surface temperature of 60°C to 170°C, preferably 80°C to 160°C, more preferably 90°C to 130°C, and

The third godet operates at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C,

Preferably, the second godet has a higher surface temperature than any of the first godet and the third godet.

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

(a1) Oiling the extruded filaments with spinning oil prior to step (b).

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

(A) polyol;

(B) diisocyanates; and

(C) a chain extender,

The polyol is selected from the group consisting of polyether polyols, polyester polyols and any mixture thereof.

7. A multifilament obtained by the method as described in any one of embodiments 1 to 6.

8. The multifilament yarn as described in embodiment 7, wherein the boiling water shrinkage of the multifilament yarn according to ASTM D2259-02 is not more than 18%, preferably not more than 17%, more preferably not more than 15%, further preferably not more than 13%, further more preferably not more than 10%.

9. The multifilament yarn of embodiment 7 or 8, wherein the elongation at break of the multifilament yarn is less than 55%, such as less than 50%, such as less than 46%, such as less than 40%, measured according to ISO 2062:2009 method A at a relatively low winding speed of less than 3000 m/min.

10. The multifilament yarn according to any one of embodiments 7 to 9, which has a bicomponent structure or a microtubular structure.

11. Use of the multifilament according to any one of embodiments 7 to 10 in the production of clothing, shoes, or accessories, such as shoes, pants, T-shirts, seat meshes, watch straps, or hair bands.

The TPU multifilament produced by the method of the present invention has low heat shrinkage and low elongation at break, has improved filament properties such as good uniformity and low defect rate, and brings improved product properties such as good dimensional stability, good feel and low defect rate of products derived from the multifilament (such as woven products derived from the multifilament), wherein the TPU multifilament is directly produced by the method of the present invention without the need for an additional heat setting stage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an apparatus for melt spinning of TPU multifilaments.

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below unless otherwise indicated.

The articles "a," "an," and "the" are intended to refer to one or more than one substance represented by the term following the article.

In the context of this disclosure, any specific values mentioned for features (including specific values mentioned as endpoints in ranges) can be recombined to form new ranges.

Further embodiments of the invention can be seen from the claims, the description and the examples. It is to be understood that the above-mentioned features of the subject matter of the invention and the features still to be elucidated below can be used not only in the specific combination indicated but also in other combinations without departing from the scope of the invention.

Method for producing multifilament yarn

One aspect of the present invention relates to a method for producing multifilament yarn by melt spinning a composition containing thermoplastic polyurethane, the method comprising:

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

(b) passing the extruded filaments through a set of godet rolls, and

(c) winding the extruded filaments from step (b) onto a bobbin through a winder at 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 of 68D-90D, preferably in the range of 70D-90D, more preferably in the range of 75D-88D, more preferably in the range of 81D-87D, still more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1.

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

The step (a) of the inventive method is not particularly limited and can be carried out by a technician. Melt spinning is such a technology, in which, by using an extruder or similar equipment, the 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 is discharged from the spinneret into the atmosphere (for example, discharged into the air or discharged into the cooling air if necessary). The position of the spinneret is not limited. However, it is preferred that the spinneret is positioned downward so that the molten composition (molten filament) is discharged downward (drawn downward). The discharged molten filament is cooled and solidified in the atmosphere, thinned simultaneously, and then wound up at a certain speed. There can be a plurality of spinneret groups in any group or pattern. When using a plurality of spinnerets, the composition leaving these spinnerets can be guided by a mechanical mechanism and form the filaments extruded. The number of spinnerets is not limited.

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

It is also possible to melt the main component of the raw material composition (the thermoplastic polyurethane of the present invention) independently of one or more other components (if any) of the raw material composition so that the molten main component is mixed with the one or more other components just before being discharged from the spinneret.

The device for producing multifilament by melt spinning is not particularly limited and is known to the technician. The example of this device is shown in Figure 1. Usually, the device for melt spinning includes an extruder (not shown), a spinning package, a godet roll (such as GR1, GR2 and GR3) and a winder. The spinning package is known in the art and is mainly composed of a melt storage tank and a spinneret.

When one or more additives (other components) such as a crosslinking agent are used, at least one mixer, such as a static or dynamic mixer, preferably a static mixer, may be provided in the device. In this case, the main component containing TPU (in a preferred embodiment, the main component consisting of TPU) is melted in the extruder independently of the crosslinking agent; the crosslinking agent is mixed with the molten main component by using a mixer; and then the mixed composition in a molten state (i.e., the raw material composition in a molten state) is discharged from the nozzle of the spinning head. During the melt spinning process, the TPU of the raw material composition is crosslinked with the crosslinking agent. Alternatively, the dried TPU pellets are melted in the extruder, and the crosslinking agent (0%-20%) is fed at the end of the extruder. The blend of the crosslinking agent and the TPU melt passes through the mixer and the melt pipe, and after metering, is pressed into the spinning package, and finally leaves the spinneret.

Spinning temperature is a parameter of the spinning conditions of melt spinning. The spinning temperature is defined not only as, for example, the heating temperature in the extruder, but also as the heating temperature in the raw material composition tube and in the spinning bag. The spinning temperature is not particularly limited and can be appropriately changed according to the melting point of the raw material composition. From the perspective of spinnability, in the present invention, the spinning temperature is preferably 225°C or higher, but preferably not higher than 250°C, such as not higher than 240°C. Especially when using TPU with high hardness (e.g., greater than Shore 68D), a higher spinning temperature (e.g., 225°C or higher) enables spinning at a higher spinning speed. From the perspective of suppressing thermal decomposition of the raw material composition, the spinning temperature is generally 240°C or lower, and preferably 235°C or lower.

After leaving the spinneret, the extruded filaments are sent to step (b) to be stretched or oriented by passing through a set of godet rolls.

In step (b), the extruded filaments pass through a godet set. The godet set in step (b) of the method of the present invention may include two or more godets arranged in series. Preferably, the godet set in step (b) includes a first godet running 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 preferred embodiment of the present invention, the first godet runs at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C.

The running speed of one or more godet rollers after the first godet roller can be selected by a technician. In a preferred embodiment of the present invention, the godet roller group in step (b) comprises a first godet roller (GR1), a second godet roller (GR2) and a third godet roller (GR3) arranged in series. Preferably, the godet rollers run at the following speeds 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 is higher than any of the speeds of the first godet and the third godet.

Depending on the TPU material and/or the final application, more godets may be used. For example, the godet set in step (b) may include four or more godets. In an embodiment of the present invention, in addition to the first godet, the second godet and the third godet, the godet set in step (b) of the method of the present invention may further include 1, 2 or 3 godets.

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

In the present invention, unless otherwise specified, "the speed of the godet roller" and "the running speed of the godet roller" are used interchangeably, which refers to the circumferential speed of the godet roller.

The surface temperature of the godet roller in step (b) of the present invention can be selected by a technician. In an embodiment, the godet roller group in step (b) comprises a first godet roller, a second godet roller and a third godet roller arranged in series, wherein the first godet roller operates at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C, the second godet roller operates at a surface temperature of 60°C-170°C, preferably 80°C-160°C, more preferably 90°C-130°C, and the third godet roller operates at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C.

Preferably, the surface temperature of the second godet is higher than any of the surface temperature of the first godet and the surface temperature of the third godet.

In an embodiment, in step (b) of the method of the present invention, the surface temperatures and speeds of the first godet roller (GR1), the second godet roller (GR2) and the third godet roller (GR3) are respectively as follows:

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

GR2: surface temperature is 60°C-170°C, preferably 80°C-160°C, more preferably 90°C-130°C, and independently, the speed is 2000-5000m/min, preferably 2000-4000m/min, more preferably 2500-3500m/min, more preferably 2600-3200m/min,

GR3: The surface temperature is 30-120°C, preferably 50-100°C, more preferably 60-90°C, and independently, the speed is 2000-5000m/min, preferably 2000-4000m/min, more preferably 2200-3200m/min, more preferably 2400-3000m/min.

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

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

GR2: surface temperature is 60°C-170°C, preferably 80°C-160°C, more preferably 90°C-130°C, and independently, the speed is 2000-5000m/min, preferably 2000-4000m/min, more preferably 2500-3500m/min, more preferably 2600-3200m/min,

GR3: The surface temperature is 30-120°C, preferably 50-100°C, more preferably 60-90°C, and independently, the speed is 2000-5000m/min, preferably 2000-4000m/min, more preferably 2200-3200m/min, more preferably 2400-3000m/min.

The method of the present invention further comprises the step (c) of winding the filament from step (b) onto a bobbin by a winder at 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 preferred embodiment of the present invention, the method for producing multifilament by melt spinning a composition containing thermoplastic polyurethane comprises:

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

(b) passing the extruded filaments through a set of godet rolls, and

(c) winding the extruded filaments from step (b) onto a bobbin via a winder at a winding speed of 2100-2900 m/min, more preferably 2400-2900 m/min,

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

In a more preferred embodiment of the present invention, the method for producing multifilament by melt spinning a composition containing thermoplastic polyurethane comprises:

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

(b) passing the extruded filaments through a set of godet rolls, and

(c) winding the extruded filaments from step (b) onto a bobbin via a winder at a winding speed of 2100-2900 m/min, more preferably 2400-2900 m/min,

The thermoplastic polyurethane has a Shore hardness in the range of 81D-87D, more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1.

In a more preferred embodiment of the present invention, the method for producing multifilament by melt spinning a composition containing thermoplastic polyurethane comprises:

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

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

(c) winding the extruded filaments from step (b) onto a bobbin through a winder at 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 of 68D-90D, preferably in the range of 70D-90D, more preferably in the range of 75D-88D, more preferably in the range of 81D-87D, still more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1.

In a still more preferred embodiment of the present invention, the method for producing multifilament by melt spinning a composition containing thermoplastic polyurethane comprises:

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

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

(c) winding the extruded filaments from step (b) onto a bobbin via a winder at a winding speed of 2100-2900 m/min, more preferably 2400-2900 m/min,

The thermoplastic polyurethane has a Shore hardness in the range of 81D-87D, more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1.

In a still more preferred embodiment of the present invention, the method for producing multifilament by melt spinning a composition containing thermoplastic polyurethane comprises:

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

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

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

GR2: surface temperature is 60°C-170°C, preferably 80°C-160°C, more preferably 90°C-130°C, and independently, the speed is 2000-5000m/min, preferably 2000-4000m/min, more preferably 2500-3500m/min, more preferably 2600-3200m/min,

GR3: surface temperature is 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C, and independently, the speed is 2000-5000m/min, preferably 2000-4000m/min, more preferably 2200-3200m/min, more preferably 2400-3000m/min,

Preferably, the speed of the second godet is higher than any one of the speeds of the first godet and the third godet, and the surface temperature of the second godet is higher than any one of the surface temperature of the first godet and the third godet, and

(c) winding the extruded filaments from step (b) onto a bobbin via a winder at a winding speed of 2100-2900 m/min, more preferably 2400-2900 m/min,

The thermoplastic polyurethane has a Shore hardness in the range of 81D-87D, more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1.

Optionally and preferably, the extruded filaments may be oiled after leaving the spinneret and before reaching the godet rolls. The oiling step lubricates the filaments and reduces friction between the filaments and the metal/ceramic parts of the spinning line; allows dissipation of electrostatic charges generated by contact of the filaments with machine parts; and holds the filaments together, making unwinding from the spun cake easier. The filaments may be oiled by any conventional spinning oil.

The thickness of the rigid TPU multifilament obtained by the method of the present invention, measured according to ISO2060:1994, can be controlled within the range of 2-70DPF (denier/filament) according to different applications, for example, within the range of 2 to 50DPF, or 2 to 40DPF, or 2 to 30DPF, or 2 to 20DPF, or 2 to 10DPF.

Thermoplastic polyurethane

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

The thermoplastic polyurethane used in the method of the present invention is generally (but not particularly limited to) obtained by allowing polyol, diisocyanate and chain extender as essential components to react with each other in the presence of a catalyst and/or an auxiliary agent (auxiliary agent) if necessary. The reaction may be a one-stage reaction that allows the essential components as a whole to react with each other in one stage (in a preferred embodiment, in the presence of optional components such as a catalyst and/or an auxiliary agent (auxiliary agent)), or a reaction having multiple stages that allows some of the polyol and diisocyanate to react with each other to form a prepolymer, and then allows the prepolymer and the remaining essential components to react with each other, these reactions are preferably carried out in the presence of a catalyst and/or an auxiliary agent (auxiliary agent).

Examples of the catalyst in the reaction (if used) can be selected from, but not particularly limited to, trimethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo(2,2,2)octane and the like; in particular, organometallic compounds such as titanium esters; 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 their equivalents. The amount of the catalyst used in the reaction can be determined by a skilled person according to actual application.

Examples of auxiliary agents may be selected from, but are not particularly limited to, surfactants, nucleating agents, sliding and demoulding aids, dyes, pigments, antioxidants (e.g., related to hydrolysis, light, heat and discoloration), ultraviolet absorbers, flame retardants, reinforcing agents, plasticizers or fluidity improvers and crosslinking agents; one or more selected from these auxiliary agents may be used. The amount of the auxiliary agent may be determined by a technician according to actual application.

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

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 200,000 g/mol.

Polyols

The thermoplastic polyurethane used in the method of the present invention has (A) a polyol as one of the raw materials.

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

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

The polyether polyols can be obtained by known methods, for example by polymerizing alkylene oxides in the presence of a catalyst by adding at least one starter molecule containing 2 to 8, preferably 2 to 6, reactive hydrogen atoms. As catalysts, alkali metal hydroxides such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides such as sodium methoxide, sodium ethoxide 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 can be used as catalysts. In addition, double metal cyanide compounds (known as DMC catalysts) can also be used as catalysts.

As alkylene oxides, preference is given to using one or more compounds having 2 to 4 carbon atoms in the alkylene group, for example ethylene oxide, 1,3-propylene oxide, tetrahydrofuran, 1,2- or 2,3-butylene oxide, in each case individually or in the form of a mixture, 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 alcohols such as sorbitol, methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, toluenediamine, naphthylamine, ethylenediamine, diethylenetriamine, 4,4′-methylenedianiline, 1,3-propylenediamine, 1,6-hexanediamine, ethanolamine, diethanolamine, triethanolamine and other di- or polyols or mono- or polyfunctional amines.

Examples of polyether polyols may also include ring-opening polymers of tetrahydrofuran (polytetramethylene glycol, PTMEG), natural oil-based polyether polyols like alkoxylated castor oil or other natural oil or fat-based polyether polyols (e.g., those obtained by ring-opening reactions of epoxidized unsaturated vegetable oils), sugar-based polyether polyols.

Polyester polyols can be prepared by condensing a polyfunctional alcohol having 2 to 12 carbon atoms with a polyfunctional carboxylic acid having 2 to 12 carbon atoms. The polyfunctional alcohol or the polyfunctional carboxylic acid can have a functionality of about 2. Examples of polyfunctional alcohols can be ethylene glycol, diethylene glycol, butanediol, or a combination thereof. Examples of polyfunctional carboxylic acids can be succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isomers of isophthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, or esters or anhydrides of the acid mentioned.

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

Diisocyanates

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

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

The diisocyanate of the present invention may be an aliphatic diisocyanate, or an araliphatic diisocyanate, or an alicyclic diisocyanate, or an aromatic diisocyanate.

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

Preferred examples of suitable diisocyanates of the present invention include isomers of diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, isomers of toluene diisocyanate, 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)cyclohexane, 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 diisocyanate, 1,5-naphthalene diisocyanate, isomers of toluene diisocyanate, 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 the examples of the present 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.

The chain extenders of the present invention may comprise aliphatic, araliphatic, aromatic, and/or alicyclic compounds having two or three functional groups. For example, chain extenders suitable for use in the present invention may be selected from difunctional or trifunctional amines and alcohols, particularly diols, triols, or both, such as diamines and/or alkanediols having 2 to 10 carbon atoms in the alkylene group.

As examples of chain extenders suitable for the present invention, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 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 can be mentioned. Particularly preferred chain extenders include 1,3-propylene glycol, 1,4-butanediol, or 1,6-hexanediol. In some cases, a mixture of two chain extenders can be used.

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

The multifilament of the present invention

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

The multifilament yarn obtained by the process of the present invention has greatly reduced boiling water shrinkage and greatly reduced elongation at break, has improved filament properties, such as good uniformity and low defect rate, and brings improved properties to products prepared from the multifilament yarn, such as good dimensional stability, good hand and low defect rate of these products (such as woven products from the multifilament yarn).

Preferably, the multifilament obtained by the process of the present invention has a boiling water shrinkage according to ASTM D2259-02 of not more than 18%, preferably not more than 17%, preferably not more than 15%, further preferably not more than 13%, more preferably not more than 10%.

Preferably, the multifilament obtained by the process of the present invention has an elongation at break according to ISO 2062:2009 method A at a relatively low winding speed below 3000 m/min of less than 55%, such as less than 50%, such as less than 46%, such as less than 40%.

In some embodiments of the present invention, the multifilament obtained by the method of the present invention has a bicomponent structure or a microtubular structure.

The multifilaments obtained by the method of the present invention can be used in various applications. For example, the multifilaments obtained by the method of the present invention are very suitable for the manufacture of fabrics. The fabrics manufactured in this way can be used to produce products such as braided or woven products, such as clothing, shoes, or accessories, for example, shoes, pants, T-shirts, seat meshes, watchbands, or hairbands.

In addition, the multifilament obtained by the method of the present invention has a very low boiling water shrinkage, which makes it very suitable as the main raw material in fabrics. Therefore, during the steaming or ironing process, the size and touch of the fabric produced by the multifilament can be well controlled.

By using an ultra-hard TPU having a hardness in the range of 68D-90D in the method of the present invention, the boiling water shrinkage (BWS) of the obtained multifilament can be reduced to less than 20% (as measured according to ASTM D2259-02) without the need for a heat setting process after spinning. By further increasing the hardness to more than 75D, the BWS of the obtained multifilament can be controlled to less than 15%. In addition, if the hardness exceeds 80D, a very low BWS of less than 10% can be achieved.

By using superhard TPU for multifilament production in the method of the present invention, the elongation at break of the obtained multifilament can also be reduced. As measured according to ISO2062:2009 method A, at a relatively low winding speed of less than 3000 m/min, the elongation at break can be less than 60% or even less than 40%.

The multifilament yarn of the present invention is produced directly by the method of the present invention without an additional heat setting stage. Due to the omission of the heat setting stage, the present invention also provides a simplified process compared to conventional processes for producing multifilament yarns with reduced boiling water shrinkage and reduced elongation at break and improved filament properties.

Examples

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

abbreviation

MDI: Methylene diphenyl diisocyanate

PTMEG: Polytetramethylene ether glycol

PBA: Poly(1,4-butylene adipate) glycol

PMMA: Polymethyl methacrylate

Material

The TPU materials used in the examples are as follows.

Hard TPU:

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

Super Hard TPU:

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

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

Measurement 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). These procedures are in accordance with the following specifications:

column PSSSDV Linear XL Mobile phase DMF Column temperature 35℃ flow 0.6mL/min Sample injection 20μl Detector Refractive Index Detector

The calibration curve (5th order polynomial) was constructed from PMMA standards with different molecular weights by determining the retention time of each individual PMMA standard for the analytical sequence.

The sample was dissolved in a mixture of 99 wt.% DMF and 1 wt.% di-n-butylamine at 4 mg/mL for at least 18 h, filtered through a 0.45 μm membrane filter, and then injected.

Method for producing multifilament samples

In an example, the above TPU material is used for melt spinning.

The multifilament samples in the examples were produced by a method comprising the following steps:

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

(a1) the extruded TPU filaments from step (a) are oiled with spinning oil of the brand name "Delion F-1782" from Takemoto Oil & Fat Co., Ltd.,

(b) passing the extruded TPU filaments from step (a1) through a godet set comprising a first godet (GR1), a second godet (GR2) and a third godet (GR3) arranged in series, and

(c) The TPU filaments from step (b) are wound onto a bobbin by a winder at a defined winding speed to obtain a final multifilament sample.

The composition, process parameters and results of the multifilament samples of each example are provided in Table 1.

Table 1

Claims (11)

1. A method for producing multifilament yarn by melt spinning a composition containing thermoplastic polyurethane, the method comprising: (a) passing the composition in a molten state through a spinneret to obtain extruded filaments, (b) passing the extruded filaments through a set of godet rolls, and (c) winding the extruded filaments from step (b) onto a bobbin through a winder at 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 of 68D-90D, preferably in the range of 70D-90D, more preferably in the range of 75D-88D, more preferably in the range of 81D-87D, still more preferably in the range of 82D-86D, measured according to DIN ISO 7619-1. 2. The method of claim 1, wherein the godet set in step (b) comprises a first godet 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 operates at a surface temperature of 30-120°C, preferably 50-100°C, more preferably 60-90°C. 3. The method of claim 1 or 2, wherein the godet set in step (b) comprises a first godet, a second godet and a third godet arranged in series, wherein: The first godet roll runs 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 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 roll runs 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 is higher than any of the speed of the first godet and the speed of the third godet. 4. The method of claim 3, wherein: The first godet operates at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C, The second godet operates at a surface temperature of 60°C to 170°C, preferably 80°C to 160°C, more preferably 90°C to 130°C, and The third godet operates at a surface temperature of 30°C-120°C, preferably 50°C-100°C, more preferably 60°C-90°C, Preferably, the surface temperature of the second godet is higher than any one of the surface temperature of the first godet and the surface temperature of the third godet. 5. The method according to any one of claims 1 to 4, further comprising: (a1) Oiling the extruded filaments with spinning oil prior to step (b). 6. The method of any one of claims 1 to 5, wherein the thermoplastic polyurethane comprises the reaction product of: (A) polyol; (B) diisocyanates; and (C) a chain extender, The polyol is selected from the group consisting of polyether polyols, polyester polyols and any mixture thereof. 7. A multifilament yarn obtained by the method according to any one of claims 1 to 6. 8. The multifilament according to claim 7, wherein the boiling water shrinkage of the multifilament according to ASTM D2259-02 is not more than 18%, preferably not more than 17%, more preferably not more than 15%, further preferably not more than 13%, further more preferably not more than 10%. 9. The multifilament yarn according to claim 7 or 8, wherein the elongation at break of the multifilament yarn is less than 55%, such as less than 50%, such as less than 46%, such as less than 40%, measured according to ISO 2062:2009 method A at a relatively low winding speed below 3000 m/min. 10. The multifilament according to any one of claims 7 to 9, which has a bicomponent structure or a microtubular structure. 11. Use of the multifilament according to any one of claims 7 to 10 in the production of clothing, shoes, or accessories, such as shoes, trousers, T-shirts, seat meshes, watch straps, or hair bands.