A BICOMPONENT FIBER, THE PREPARATION PROCESS AND THE USE THEREOF, AND THE FABRICS COMPRISING THE SAME

Description

Technical Field

[0001] The present invention relates to a bicomponent fiber, the preparation process and the use thereof, and the fabrics comprising the same.

Background Art

[0002] Multi-component fibers, displaying various properties, undergo much development and find wide use. An important use of them is in knitting or woven fabrics. Knitting or woven fabrics, as opposed to nonwoven fabrics, have relatively high elasticity and recovery property so that the final product is durable and easily conforms to the subject using or wearing these products.

[0003] Currently, multi-component or bicomponent fibers are usually made by solution spinning process. This process, however, leads to inclusion in the final fibers of impurities, such as solvents, monomers and oligomers, which negatively affect the mechanical property or durability of the fiber or human health. For example, DMF (dimethylformide) is commonly used in the solution spinning process as solvent, but its inclusion in the final fibers would raise health concerns. Melt-spinning process is commonly used in preparing polyester, nylon and polyolefin fibers which may find use in garment production, but is seldom used for preparing fibers made of thermoplastic polyurethanes. With the increasing demands for diversified knitting or woven products, there is a constant need to develop highly elastic fibers for making knitting or woven articles, such as lady underwear and pantyhose, with zero content of solvents and low contents of monomers and oligomers.

[0004] US2011/0275262 discloses a bicomponent spandex which comprises polyurethane-urea compositions in at least one region of the cross-section. It finds use in products such as garments, swimwear and hosiery. The bicomponent spandex disclosed therein is prepared by solution spinning techniques.

[0005] US 6, 773, 810 B2 discloses elastic bicomponent fibers having a core/sheath construction, especially a fiber in which the polymer that forms the sheath has a lower melting point than the polymer that forms the core. It also discloses that the core comprises the thermoplastic elastomer, preferably a thermoplastic polyurethane (TPU), and the sheath comprises homogeneously branched polyolefins.

[0006] US 7, 740, 777 B2 discloses a method and apparatus for producing polymer fibers and non-woven fabrics including multiple polymer components.

[0007] EP 1,944, 396 A1 discloses an elastomeric core-sheath conjugate fiber by melt-spinning process for stretchable clothing, in which the materials for both the core and the sheath can be TPU. However, it does not disclose using cross-linkers in preparing the fiber.

[0008] WO2010/045637 discloses multiple component elastic fibers prepared by a solution-spinning process of spandex fibers. These fibers have a cross-section with at least two separate regions at least one region includes a polyurethaneurea or polyurethane composition and one region of the fiber includes a fusiblitity improvement additive to enhance adhesion to itself or to a substrate.

Contents of the Invention

[0009] It is thus an object of the present invention to provide a bicomponent fiber comprising thermoplastic polyurethane (TPU) components and being at least partly cross-linked by thermoplastic urethane prepolymers, said fiber being superior in high recovery, heat-bonding behavior, dyeability and chemical-resistance.

[0010] Specifically, the bicomponent fiber according to the invention comprises

i) a first thermoplastic polyurethane component; and

ii) a second thermoplastic polyurethane component, which may be the same as or different from component i),
wherein at least one of components i) and ii) is crosslinked by a crosslinker to form at least one polymer of polymer i) and polymer ii), of which polymer i) has a melting point higher than that of polymer ii) by at least 10°C, and
the fiber size is between 8 denier and 300 denier, more preferably between 10 denier and 100 denier.

[0011] In a specific embodiment, component i) is the same as component ii).

[0012] According to a second aspect of the invention, the bicomponent fiber is prepared by a melt-spinning process, in which a cross-linker is added separately to either or both of the melt of TPU components i) and ii).

[0013] According to a further aspect of the invention, provided are knitting or woven fabrics with excellent elastic extensibility made by using the bicomponent fiber of the present invention, thus providing materials for stylish, stretchable clothing of high supportability, such as lady underwear, stocking and pantyhose.

[0014] A further aspect of the invention relates to the use of the fiber of the present invention in of the invention, in which polymer i) is for the core and polymer ii) is for the sheath.

[0015] FIG. 2b is a schematic view of a side-by-side bicomponent fiber according to one embodiment of the invention.

[0016] FIG. 3 is a micrograph of a core-sheath (50%/50%) bicomponent fiber according to one embodiment of the invention. The fiber size is 30 denier.

Modes of carrying out the invention

[0017] In a first aspect, the present invention provides a bicomponent fiber, which comprises

i) a first thermoplastic polyurethane component; and

ii) a second thermoplastic polyurethane component, which may be the same as or different from component i),
wherein
at least one of components i) and ii) is crosslinked by a crosslinker to form at least one polymer of polymer i) and polymer ii), of which polymer i) has a melting point higher than that of polymer ii) by at least 10°C, and
the fiber size is between 8 denier and 300 denier, more preferably between 10 denier and 100 denier.

[0018] As used herein, "bicomponent fiber" means a fiber comprising at least two components, i.e., having at least two distinct polymeric regions. For the sake of simplicity, the inventive bicomponent fibers may be depicted as a core/sheath structure; however, the fiber can also have a structure of any one of the configurations such as symmetrical (concentric) core/sheath, asymmetrical (eccentric) core/sheath, side-by-side, pie sections, crescent moon and the like. Preferably, the bicomponent fiber of the present invention consists of two polymers that are each derived from the same or different TPU components which have been at least partly crosslinked by the same or different crosslinkers, with the proviso that the polymers have a melting temperature difference of at least 10°C. Preferably, the melting temperature difference is at least 15°C.

[0019] The TPU component i) and TPU component ii) may be the same or different, which are prepared by reaction of (a) isocyanates with (b) compounds which are reactive toward isocyanates and have a number average molecular weight of from 400 g/mol to 8000 g/mol, and (c) chain extenders having a number average molecular weight of from 50 g/mol to 500 g/mol, optionally in the presence of (d) catalyst and/or (e) customary auxiliaries and/or (f) additives.

[0020] Organic isocyanates (a) which may be used are generally known aliphatic, cycloaliphatic, araliphatic and/or aromatic isocyanates, preferably diisocyanates, for example tri-, tetra-, penta-, hexa-, hepta- and/or octa-methylenediisocyanate, 2-methylpentamethylene 1,5-diisocyanate, 2-ethylbutylene 1,4-diisocyanate, pentamethylene 1,5-diisocyanate, butylene 1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophoronediisocyanate, IPDI), 1,6-Hexamethylendiisocyanat (HDI), 2,4-Tetramethylenxylendiisocyant (TMXDI), 1,4- and/or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), cyclohexane 1,4-diisocyanate, 1-methylcyclohexane 2,4- and/or 2,6-diisocyanate and/or dicyclohexylmethane 4,4'-, 2,4'- and 2,2'-diisocyanate, diphenylmethane 2,2'-, 2,4'- and/or 4,4'-diisocyanate (MDI), naphthylene 1,5-diisocyanate (NDI), tolylene 2,4- and/or 2,6-diisocyanate (TDI), 3,3'-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and/or phenylenediisocyanate, or mixtures thereof.

[0021] In a particularly preferred embodiment, the organic isocyanate is an isocyanate which comprises at least 90% by weight, more preferably at least 95% by weight, particularly preferably at least 99% by weight, of diphenylmethanediisocyanate (MDI).

[0022] The generally known compounds reactive toward isocyanates may be used as polyhydroxy compounds (b), for example polyesterols, polyetherols and/or polycarbonatediols, which are usually also summarized under the term "polyols (b1)", having number average molecular weights of from 400 to 8000 g/mol, preferably from 500 g/mol to 6000 g/mol, in particular from 1000 g/mol to 4000 g/mol, and preferably an average functionality of from 1.8 to 2.3, preferably from 1.9 to 2.2, in particular 2. It is also possible to use mixtures of polyols (b1).

[0023] The polyols (b1) are commonly known in the art, and has been described in "Polyurethane Handbook, 2nd Edit. Günter Oertel", Carl Hanser Verlag, Munich 1994 in chapter 3.1.

[0024] Chain extenders (c) which may be used are generally known aliphatic, araliphatic, aromatic and/or cycloaliphatic compounds having a molecular weight of from 50 to 500, preferably difunctional compounds, for example diamines and/or alkanediols having 2 to 10 carbon atoms in the alkylene radical, in particular 1,4-butanediol, 1,6-hexanediol, and/or di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- and/or decaalkylene glycols having 3 to 8 carbon atoms, preferably corresponding oligo- and/or polypropylene glycols, it also being possible to use mixtures of chain extenders. Particularly preferred chain extender is 1,4-butanediol.

[0025] Suitable catalysts (d) which accelerate in particular the reaction between the NCO groups of the diisocyanates (a) and the hydroxyl and/or amino groups of the components (b) and (c) are the customary tertiary amines known according to the prior art, such as, for example, triethylamine, dimethylcyclohexylamine, N-methyl-morpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo-(2,2,2)octane and the like, and metal compounds, such as titanic acid esters, iron compounds, e.g. iron(III) acetylacetonate, tin compounds, e.g. tin diacetate, tin dioctanoate, tin dilaurate or the dialkyltin salts of aliphatic carboxylic acids, such as dibutyltindiacetate, dibutyltindilaurate or the like. The catalysts are usually used in amounts of from 0.0001 to 0.1 parts by weight per 100 parts by weight of polyhydroxy compound (b).

[0026] In addition to catalysts (d), customary auxiliaries (e) and/or additives (f) can also be added to the components (a) to (c), including surface-active substances, inorganic and/or organic fillers, reinforcing agents, plasticizers, flame proofing agents, nucleating agents, oxidation stabilizers, lubricants and mold release agents, dyes and pigments, if appropriate further stabilizers in addition to the stabilizer mixture according to the invention, e.g. hydrolysis, light or heat stabilizers or stabilizers to prevent discoloration. In a preferred embodiment, the component (e) also includes hydrolysis stabilizers, such as, for example, polymeric and low molecular weight carbodiimides. Component (f) may include other thermoplastics, such as polycarbonate (PC), polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polyamide (PA), polybutylene terephthalate (PBT), polystyrene (PS), thermoplastic polyester elastomers (TPEE), etc.

[0027] In addition to said components (a), (b) and (c) and, if appropriate, (d), (e)and (f), chain regulators, usually having a molecular weight of from 31 to 499, may also be used. Such chain regulators are compounds which have only one functional group reactive toward isocyanates, such as, for example, monofunctional alcohols, monofunctional amines and/or monofunctional polyols. By means of such chain regulators, it is possible to establish flow behavior, in particular in the case of TPUs, in a controlled manner. Chain regulators can be used in general in an amount of from 0 to 5 parts by weight, preferably from 0.1 to 1 part by weight, based on 100 parts by weight of component b) and by definition are included under the component c).

[0028] All molecular weights mentioned herein are presented in the measurement unit of g/mol, except defined otherwise.

[0029] Alternatively, the preparation process for the TPU used in the present invention may be found in EP1078944B1. According to one embodiment of the invention, the TPU used may have a weight average molecular weight of 20,000 to 1,000,000, preferably 40,000 to 500,000, and more preferably 50,000 to 300,000. Some commercialized products can be used in the present invention as the TPU component, such as TPUs with the trademark of Elastollan^® from BASF. Most preferably, Elastollan^® 2200, 1100 or 600 series from BASF are used.

[0030] The TPU used in the present invention preferably has, independent of one another, a Shore A hardness measured in accordance with DIN 53505 of from 65 Shore A to 98 Shore A, more preferably from 70 Shore A to 95 Shore A, even more preferably from 75 Shore A to 90 Shore A, which may be different or the same for the two TPU components. If the hardness is too low, the fiber will have very low strength; on the other hand, if the hardness is too high, the fiber will have very low elasticity.

[0031] According to the present invention, a crosslinker is added into at least one of the TPUs to improve mechanical properties of the bicomponent fibers. In one embodiment of the present invention, a crosslinker is only added into the TPU component i), which may form the polymer i) for providing high recovery in the bicomponent fiber. In another embodiment of the present invention, one or more crosslinkers are added to both TPU components i) and ii), producing polymer i) and polymer ii) respectively.

[0032] In a core-sheath type bicomponent fiber, polymer i) having a higher melting point is for core and polymer ii) having a lower melting point is for sheath, such as one shown in Fig 2(a). For a side-by-side type bicomponent fiber, such as one shown in Fig 2(b), polymer i) having a higher melting point may provide the fiber with crimping property and polymer ii) having a lower melting point provide the fiber with heat bonding property.

[0033] In the preparing process of the inventive fibers, crosslinker as defined below is added to either or both of the melted components i) and ii). When added, the crosslinkers are added in an amount of from about 0% to about 15%, preferably 1% to 10%, more preferably 2% to 8% by weight of the TPU for polymer ii), and in an amount of from about 5% to 25%, preferably 8% to 20%, and more preferably 10% to 15% by weight of the TPU for polymer i).

[0034] The crosslinker used in the present invention is a NCO-terminated prepolymer with a functionality of 1.5 to 3, preferably 1.5 to 2.5, and more preferably 1.6 to 2.1. In one embodiment of the present invention, the crosslinkers used is a prepolymer having a NCO content of 3% to 20% by weight, preferably 4% to 10% by weight, and more preferably 5% to 8% by weight.

[0035] The crosslinker can be prepared by reaction of isocyanates with compounds which are reactive toward isocyanates and have a number average molecular weight of from 200 g/mol to 10000 g/mol, preferably 250 g/mol to 8000 g/mol, and more preferably 500 g/mol to 6000 g/mol.

[0036] In some embodiments of the present invention, the crosslinkers are added into the melt of the TPU components. In some other embodiments, the crosslinkers are added into the TPU components before melting. There is no restriction as to the time for adding the prepolymers, and it can be determined by a person skilled in the art according to actual process. The crosslinkers can be either in a solid or in a liquid state.

[0037] Appropriate crosslinkers and also their production and processing are described in, for example, EP2139934A1. The crosslinkers may be based on aliphatic and/or aromatic isocyanates, preferably on aromatic isocyanates. Preferably, the crosslinkers used in the present invention can be commercialized products, such as prepolymers with the trademark of Elastollan^® from BASF. Most preferably, type PLP9302 or CR-1 from BASF can be used.

[0038] In one embodiment of the present invention, polymer i) has a melting point higher than polymer ii) by at least 10°C, preferably by at least 15°C, more preferably by at least 20°C. Preferably, in the bicomponent fiber of the present invention, polymer i) has a melting point higher than polymer ii) by up to 80°C, more preferably by up to 60°C and even more preferably by up to 40°C.

[0039] In the bicomponent fibers, polymer ii), such as for sheath, is present in an amount of 5 to 80% by weight, preferably 8% to 50% by weight, more preferably 10% to 40% by weight, based on the total weigh of the bicomponent fiber.

[0040] The bicomponent fiber may have a cross-section of sheath-core type (concentric or eccentric), or side-by-side type. Sheath-core type (concentric or eccentric) structure is preferred. Preferably, in a sheath/core structure, the fiber contains polymer i) for core and polymer ii) for sheath, in which polymer i) has a higher melting point, such as more than 170°C, and polymer ii) may have a lower melting point such as less than 170°C, more preferably less than 160°C and even more preferably less than 150°C.On the other hand, polymer i) usually has a higher elasticity than polymer ii), resulting in the final fiber having a 300% recovery of more than 80%. The 300% recovery was tested according to DIN 53835. In this case, the fibers have good elasticity and heat bonding property at the same time, which is particularly suitable for producing lady underwear, pantyhose, etc.

[0041] In other embodiments, the fiber may further include additives in one or both of the two components. For example, in a core-sheath type fiber, the sheath includes additives to improve chemical resistance or dyeability of the fiber.

[0042] Surprisingly, it has been found that since the two components in the fiber are both TPUs, the compatibility of the two polymers according to the present invention can be improved as compared with conventional bicomponent fibers made from different types of polymers. Thus, even after numerous times of repeated stretching based on DIN 53835, the bicomponent fibers according to the present invention still have outstanding recovery, for example, a 300% recovery of more than 75%, more preferably more than 80%, and even more preferably more than 88%.

[0043] In the second aspect of the invention, the bicomponent fiber is made from a process including the following steps:

(1) melting component i) and ii) in different extruders at a temperature of 160 to 230°C,

(2) adding crosslinker(s) into either or both of the TPUs during the melt process (1),

(3) extruding the melts of components i) and ii) with a spin head having two or more nozzles, which is heated at 160 to 230°C to obtain a bicomponent fiber,

(4) winding up the fiber through a roller at a spinning rate of 100 m/min to 1000 m/min.

[0044] It would be appreciated by those skilled in the art that the spin head having two or more nozzles have such configurations that the produced bicomponent fiber has a core/sheath structure, or has a structure of any one of the configurations such as symmetrical (concentric) core/sheath, asymmetrical (eccentric) core/sheath, side-by-side, pie sections, crescent moon and the like.

[0045] The fiber is wound up in a stretched state through one or more godet rollers, and wound up on a bobbin by the rotation of a winder. Preferably, a spin oil such as silicone-based oil or mineral oil is applied, preferably sprayed, on to the fibers to facilitate winding.

[0046] In the process, prepolymers as defined above are added to either or both of the melted components i) and ii) as the crosslinker. In one embodiment of the invention, the prepolymer is added in an amount of from about 0% to about 15%, preferably 1% to 10%, more preferably 2% to 8% by weight of the TPU for polymer ii), and in an amount of from about 5% to 25%, preferably 8% to 20%, and more preferably 10% to 15% by weight of the TPU for polymer i).

[0047] The inventors have found that, in the case of fibers for particular use, such as for lady underwear or pantyhose, which needs high recovery and elasticity as well as comfortable skin feelings, the roller for drawing the fiber preferably has a speed of 200 m/min to 800 m/min, and even more preferably 300 m/min to 700 m/min.

[0048] Preferably, 2 to 5 godet rollers are used; more preferably, 2 to 4, most preferably 3, godet rollers are used. In one embodiment of the invention, 2 to 4 godet rollers are used to draw the fiber at a speed of 300 m/min to 700 m/min, thus preparing a fiber with a great balance between appropriate size and high recovery.

[0049] The bicomponent fibers prepared according to the present invention are for producing woven or knitting fabrics. In fibers of the sheath-core structure, the sheath polymer having a relatively lower melting temperature has a good bonding ability while the core polymer provides the fiber with high recovery. After being knitted to form a product, a further heating step may be applied to the product, rendering the sheath polymer to be partly melted so that binding sites are formed at the place where two fibers connect. By so doing, the running problem with articles made from high-elasticity fibers are avoided. This is particularly advantageous in producing lady underwear or pantyhose.

Examples

[0050] The following methods and criteria are used in determination and evaluation of each parameter.

Tensile strength

[0051] Tensile strength is determined according to DIN 53834.

Elongation at break

[0052] Elongation at break is determined according to DIN 53834.

300% recovery

[0053] 300% recovery is determined according to DIN53835, in which the recovery after 5 successive load-recovery cycles with the elongation of 300% at a stretching speed of 100 mm/min is tested. The following criteria are provided to assess the result ("+" means good, and "-" means poor).

≤80	≤81-85	≤86-90	>90
-	-+	+	++

Melting point T_m

[0054] The Flow Beginning Temperature (FBT) tested by a capillary rheometer isregarded as the T_m, under the condition of 30 kg force, 1mm die I.D., 10 mm die length, and 3°C/min heating rate. The following criteria are provided to assess the test results("+" means good, and "-" means poor).

Tm	≤159	160-169	170-179	≥180
Heat bonding behavior	++	+	-+	-

[0055] Fiber size is measured by microscope.

Example 1

[0056] Two commercialized TPUs E1180A and E2280A (obtained from BASF, both having a Shore A hardness of 80A; their weight average molecular weight is 130,000 and 210,000, respectively) are used for preparing monocomponent fibers. The commercialized prepolymer PLP9302 (obtained from BASF with a molecular weight of about 2500) is used as the cross-linker (the functionality of PLP9302 is 2.0 and the NCO% is about 5.3).

Table 1: Properties of mono-component fibers (30 denier)

	components	Weight percentage (%)
Monocomponent fibers	E1180A	100	100	100
	E2280A				100	100	100
	PLP9302		2	5		5	10
Tensile strength (cN/D)		1.3	1.5	1.4	1.3	1.5	1.4
Elongation at break (%)		390	410	400	420	425	430
300% recovery (%)		75	80	84	80	88	94
Evaluation of the recovery		-	-	-+	-	+	++
Melting point Tm (°C)		150	160	170	155	175	180
Evaluation of heat bonding behavior by the Tm		++	+	-+	++	-+	-

[0057] E1180A, E2280A and PLP9302 are also used to prepare bicomponent fibers. Specifically, the fibers are prepared by the following steps:

(1) E1180A and E2280A are melted in different extruders at a temperature of 200°C and 210°C respectively,

(2) PLP9302 is mixed into melted E1180A and E2280 in an amount of 2% and 10% by weight of respective base TPU, respectively,

(3) The two melts are extruded to a spin head having two nozzles in concentric arrangement, which are heated at 210°C to obtain a bicomponent fiber in a core-sheath structure,

(4) The fiber, after passing through a spray of spin oil obtained from Takemoto Oil & Fat Co., Ltd, is wound up through three godet rollers and wound up at a spinning rate of 300 m/min.

Table 2: Properties of bicomponent fibers (30 denier)

	Sheath: E1180A+2% PLP9302;
	Core: E2280A+10% PLP9302
	Sheath/Core
	50%/50%	30%/70%	20%/80%
Tensile strength, cN/D	1.4	1.5	1.4
Elongation at break, %	420	420	420
300% recovery, %	90	92	93
Evaluation of the recovery	+	++	++
Melting point (Tm), °C	160	160	160
Evaluation of heat bonding behavior by the Tm	+	+	+

[0058] As can be seen from Table 1, with the addition of crosslinker, recovery of the monocomponent fibers becomes higher, which is favorable for the final use; heat bonding temperature (T_m) of the fibers also becomes higher, which is unfavorable for the final usage. That is to say, by using a monocomponent fiber, it is difficult to achieve the good recovery and good heat bonding behavior at the same time.

[0059] As can be seen from Table 2, for the core-sheath bicomponent fiber, even using substantial amount of polymer ii) for the sheath, the fiber still shows good recovery. Together with the good heat bonding behavior provided by the sheath, the thus-formed fibers are favorable for the final use.

Claims

1. A bicomponent fiber, comprising

i) a first thermoplastic polyurethane component; and

ii) a second thermoplastic polyurethane component, which may be the same as or different from component i),
wherein at least one of components i) and ii) is crosslinked by a crosslinker to form at least one polymer of polymer i) and polymer ii), of which polymer i) has a melting point higher than that of polymer ii) by at least 10°C,
the fiber size is between 8 and 300 denier, more preferably between 10 and 100 denier, and the crosslinker is a NCO-terminated prepolymers with a functionality of 1.5 to 3.

2. The bicomponent fiber of claim 1, in which polymer i) has a melting point higher than that of polymer ii) by at least 15°C, more preferably at least 20°C.

3. The bicomponent fiber of claim 1 or 2, in which the polymer i) has a melting point higher than that of polymer ii)by up to 80°C, more preferably by up to 60°C.

4. The bicomponent fiber of any one of the preceding claims, in which the polymer ii) is 5% to 80% by weight, preferably 8% to 50% by weight, more preferably 10% to 40% by weight, based on the total weight of the bicomponent fiber.

5. The bicomponent fiber of any one of the preceding claims, in which the component i) or ii) has a Shore A hardness measured in accordance with DIN 53505 of from 65 to 98, preferably from 70 to 95, more preferably 75 to 90.

6. The bicomponent fiber of any one of the preceding claims, in which the component i) or ii) is, independent of one another, crosslinked by a NCO-terminated prepolymer with a functionality of 1.5 to 3 and a NCO content of 3% to 20% by weight of the prepolymer.

7. The bicomponent fiber of claim 6, in which the prepolymer is polyurethane.

8. The bicomponent fiber of any one of the preceding claims, in which the fiber has a cross-section of sheath-core type or side-by-side type.

9. The bicomponent fiber of claim 1, in which the crosslinker for the polymer ii) is from about 0% to about 15%, preferably 1% to 10%, more preferably 2% to 8% by weight of the TPU component ii); and the crosslinker for polymer i) is from about 5% to 25%, preferably 8% to 20%, and more preferably 10% to 15% by weight of the TPU component i).

10. The bicomponent fiber of claim 8, in which the polymer i) in the sheath-core type fiber is for core and the polymer ii) in the sheath-core type fiber is for sheath.

11. The bicomponent fiber of the preceding claims, in which the fiber has a 300% recovery of more than 80% according to DIN 53835.

12. A process for preparing the bicomponent fiber of the preceding claims, including the following steps:

(1) melting component i) and ii) in different extruders at a temperature of 160°C to 230°C,

(2) adding crosslinker(s) into either or both of the TPUs during the melt process (1),

(3) extruding the melts of components i) and ii) with a spin head having two or more nozzles, which is heated at 160°C to 230°C to obtain a bicomponent fiber,

(4) winding up the fiber through a roller at a spinning rate of 100 m/min to 1000 m/min.

13. The process of claim 12, in which the spinning rate of the roller is 300 m/min to 700 m/min.

14. A knitting or woven fabric comprising the bicomponent fiber as defined in any one of claims 1 to 12 or the bicomponent fiber prepared according to claim 13.

15. The use of the bicomponent fiber as defined in any one of claims 1 to 12 or the bicomponent fiber prepared according to claim 13 for preparation of knitting or woven fabrics, which are used to produce lady underwear and pantyhose.

Ansprüche

1. Zweikomponentenfaser, umfassend

i) eine erste Komponente des Typs thermoplastisches Polyurethan sowie

ii) eine der Komponente i) gleiche oder davon verschiedene, zweite Komponente des Typs thermoplastisches Polyurethan,
wobei mindestens eine der Komponenten i) und ii) mit einem Vernetzungsmittel zu mindestens einem Polymer aus Polymer i) und Polymer ii) vernetzt ist, von denen das Polymer i) über einen gegenüber dem Polymer ii) um mindestens 10°C höheren Schmelzpunkt verfügt,
der Fasertiter zwischen 8 und 300 den und besonders bevorzugt zwischen 10 und 100 den liegt sowie als Vernetzungsmittel ein NCO-terminiertes Prepolymer mit einer Funktionalität von 1,5 bis 3 dient.

2. Zweikomponentenfaser nach Anspruch 1, bei der das Polymer i) um einen gegenüber dem Polymer ii) um mindestens 15°C und besonders bevorzugt mindestens 20°C höheren Schmelzpunkt hat.

3. Zweikomponentenfaser nach Anspruch 1 oder 2, bei der das Polymer i) um einen gegenüber dem Polymer ii) bis zu 80°C und besonders bevorzugt bis zu 60°C höheren Schmelzpunkt hat.

4. Zweikomponentenfaser nach einem der vorhergehenden Ansprüche, bei der das Polymer ii) bezogen auf das Gesamtgewicht der Zweikomponentenfaser 5 bis 80 Gew.-%, bevorzugt 8 bis 50 Gew.-% und besonders bevorzugt 10 bis 40 Gew.-% ausmacht.

5. Zweikomponentenfaser nach einem der vorhergehenden Ansprüche, bei der die Komponente i) oder ii) über eine gemäß DIN 53505 gemessene Shore-A-Härte von 65 bis 98, bevorzugt von 70 bis 95 und besonders bevorzugt von 75 bis 90 verfügt.

6. Zweikomponentenfaser nach einem der vorhergehenden Ansprüche, bei der die Komponente i) oder ii) unabhängig voneinander mit einem NCO-terminierten Prepolymer mit einer Funktionalität von 1,5 bis 3 und einem NCO-Gehalt von 3 bis 20 Gew.-%, bezogen auf das Prepolymer, vernetzt ist.

7. Zweikomponentenfaser nach Anspruch 6, bei der es sich bei dem Prepolymer um Polyurethan handelt.

8. Zweikomponentenfaser nach einem der vorhergehenden Ansprüche, bei der die Faser über einen Querschnitt des Typs Kernmantel oder des Typs Seite an Seite verfügt.

9. Zweikomponentenfaser nach Anspruch 1, bei der das Vernetzungsmittel bei Polymer ii) bezogen auf die TPU-Komponente ii) etwa 0 bis 15, bevorzugt 1 bis 10 und besonders bevorzugt 2 bis 8 Gew.-% und bei Polymer i) bezogen auf die TPU-Komponente i) etwa 5 bis 25, bevorzugt 8 bis 20 und besonders bevorzugt 10 bis 15 Gew.-% ausmacht.

10. Zweikomponentenfaser nach Anspruch 8, bei der im Falle des Fasertyps Kernmantel das Polymer i) für den Kern und das Polymer ii) für den Mantel bestimmt ist.

11. Zweikomponentenfaser nach den vorhergehenden Ansprüchen, bei der die Faser sich gemäß DIN 53835 von einer 300%igen Dehnung zu mehr als 80% erholt.

12. Verfahren zur Herstellung der Zweikomponentenfaser gemäß den vorhergehenden Ansprüchen, umfassend die folgenden Schritte:

(1) Aufschmelzen der Komponenten i) und ii) in verschiedenen Extrudern bei einer Temperatur von 160°C bis 230°C,

(2) Versetzen der TPU beim Aufschmelzen (1) je einzeln oder beide mit Vernetzungsmittel(n),

(3) Extrudieren der Schmelzen der Komponenten i) und ii) über einen auf 160°C bis 230°C erhitzten Spinnkopf mit zwei oder mehr Düsen zur Zweikomponentenfaser,

(4) Aufwickeln der Faser über eine Rolle bei einer Spinngeschwindigkeit von 100 m/min bis 1000 m/min.

13. Verfahren nach Anspruch 12, bei dem die Spinngeschwindigkeit der Rolle bei 300 m/min bis 700 m/min liegt.

14. Maschen- oder Webware, umfassend die Zweikomponentenfaser gemäß einem der Ansprüche 1 bis 12 oder die gemäß Anspruch 13 hergestellte Zweikomponentenfaser.

15. Verwendung der Zweikomponentenfaser gemäß einem der Ansprüche 1 bis 12 oder die gemäß Anspruch 13 hergestellte Zweikomponentenfaser zur Herstellung von Maschen- oder Webwaren für die Herstellung von Damenunterwäsche und Strumpfhosen.

Revendications

1. Fibre à deux composants, comprenant :

i) un premier composant polyuréthane thermoplastique ; et

ii) un deuxième composant polyuréthane thermoplastique, qui peut être identique au ou différent du composant i),
dans laquelle au moins l'un des composants i) et ii) est réticulé par un agent de réticulation pour former au moins un polymère du polymère i) et du polymère ii), le polymère i) ayant un point de fusion qui est supérieur d'au moins 10 °C à celui du polymère ii),
la taille de fibre est de 8 à 300 deniers, plus préférablement de 10 à 100 deniers, et l'agent de réticulation est un prépolymère à terminaisons NCO ayant une fonctionnalité de 1,5 à 3.

2. Fibre à deux composants selon la revendication 1, dans laquelle le polymère i) a un point de fusion qui est supérieur d'au moins 15 °C, plus préférablement d'au moins 20 °C, à celui du polymère ii).

3. Fibre à deux composants selon la revendication 1 ou 2, dans laquelle le polymère i) a un point de fusion qui est supérieur d'au maximum 80 °C, plus préférablement d'au maximum 60 °C, à celui du polymère ii).

4. Fibre à deux composants selon l'une quelconque des revendications précédentes, dans laquelle le polymère ii) représente de 5 % à 80 % en poids, préférablement de 8 % à 50 % en poids, plus préférablement de 10 % à 40 % en poids, relativement au poids total de la fibre à deux composants.

5. Fibre à deux composants selon l'une quelconque des revendications précédentes, dans laquelle le composant i) ou ii) a une dureté Shore A, mesurée selon la norme DIN 53505, de 65 à 98, préférablement de 70 à 95, plus préférablement de 75 à 90.

6. Fibre à deux composants selon l'une quelconque des revendications précédentes, dans laquelle le composant i) ou le composant ii) est, indépendamment de l'autre, réticulé par un prépolymère à terminaisons NCO ayant une fonctionnalité de 1,5 à 3 et une teneur en NCO de 3 % à 20 % en poids du prépolymère.

7. Fibre à deux composants selon la revendication 6, dans laquelle le prépolymère est un polyuréthane.

8. Fibre à deux composants selon l'une quelconque des revendications précédentes, la fibre ayant une section transversale de type « enveloppe-partie centrale » ou de type « côte à côte ».

9. Fibre à deux composants selon la revendication 1, dans laquelle l'agent de réticulation pour le polymère ii) représente d'environ 0 % à environ 15 %, préférablement de 1 % à 10 %, plus préférablement de 2 % à 8 % en poids du composant polyuréthane thermoplastique ii) ; et l'agent de réticulation pour le polymère i) représente d'environ 5 % à 25 %, préférablement de 8 % à 20 %, et plus préférablement de 10 % à 15 % en poids du composant polyuréthane thermoplastique i).

10. Fibre à deux composants selon la revendication 8, dans laquelle le polymère i) dans la fibre de type « enveloppe-partie centrale » est pour la partie centrale et le polymère ii) dans la fibre de type « enveloppe-partie centrale » est pour l'enveloppe.

11. Fibre à deux composants selon les revendications précédentes, la fibre ayant une reprise, à un allongement de 300 %, qui est supérieure à 80 % selon la norme DIN 53835.

12. Procédé de fabrication de la fibre à deux composants selon les revendications précédentes, comprenant les étapes suivantes :

(1) la fusion des composants i) et ii) dans différentes extrudeuses à une température de 160 °C à 230 °C,

(2) l'addition d'un ou plusieurs agents de réticulation dans l'un ou l'autre des polyuréthanes thermoplastiques ou dans les deux polyuréthanes thermoplastiques durant le procédé de fusion (1),

(3) l'extrusion des masses fondues des composants i) et ii) avec une tête de filage comportant deux buses ou plus, qui est chauffée à une température de 160 °C à 230 °C pour obtenir une fibre à deux composants,

(4) l'enroulement de la fibre en utilisant un rouleau tournant à une vitesse de 100 m/min à 1 000 m/min.

13. Procédé selon la revendication 12, dans lequel la vitesse de rotation du rouleau est de 300 m/min à 700 m/min.

14. Tissu tricoté ou tissé comprenant la fibre à deux composants telle que définie dans l'une quelconque des revendications 1 à 12 ou la fibre à deux composants fabriquée selon la revendication 13.

15. Utilisation de la fibre à deux composants telle que définie dans l'une quelconque des revendications 1 à 12 ou de la fibre à deux composants fabriquée selon la revendication 13 pour la fabrication de tissus tricotés ou tissés qui sont utilisés pour produire des sous-vêtements féminins et des collants.

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