A FIBER

Abstract

 A fiber comprising a first component and a second component, wherein the first component comprises a first polymer and a first additive, and the second component comprises a second polymer and a second additive, characterized in that the first polymer is different to the second polymer and the first additive is different to the second additive.

Description

[0001] The invention pertains to a fiber comprising a first component and a second component and to a textile fabric comprising such a fiber.

[0002] Textile fabrics comprising fibers can be used in a huge amount of applications such as in carpets and window shades. Any of the applications have their own demands on textile fabrics physical properties e.g. in view of softness, flexibility, stiffness, tensile strength, tensile modulus and resilience. In view of the application, the properties of the textile fabrics need to be more or less distinct in various combinations.

[0003] The main requirement, which all applications demand, is that the physical properties of the textile fabrics are maintained for a long period of time.

[0004] As the textile fabrics can be used in several outdoor applications, the textile fabrics may be exposed to weather. Humidity, wind, temperature and UV-irradiation impact on the textile fabrics and on the fibers comprised therein.

[0005] Impacting the textile fabrics by weather leads to deterioration of the physical properties of the textile fabric and fiber, e.g. the fibers become brittle, the color of the fibers fades out. Further, due to UV-irradiation induced polymer degradation, the fibers may lose some of their physical properties e.g. their tensile strength.

[0006] For providing textile fabrics and fibers which maintain their physical properties when irradiated by UV-light, or at least reduce the impact on the properties of the textile fabrics and the fibers, EP 2 826 895 B1 discloses a spun-bond nonwoven comprising bicomponent fibers of a core/sheath model. The bicomponent fibers comprise e.g. an UV-stabilizer in the core and in the sheath, and the sheath comprises a higher concentration of the UV-stabilizer than the core.

[0007] Combinations of UV-stabilizer with other additives such as flame retardants and adhesion promoters are disclosed by US 2003/0087092 A1 and US 2011/0189916 A1.

[0008] As the UV-irradiation on textile fabrics is still a major impact on the physical properties of the textile fabrics and the comprised fibers, there is still a demand for improved UV-stable textile fabrics and fibers or at least of textile fabrics and fibers reducing the impact of UV-irradiation on their physical properties.

[0009] The object of the present application is to provide a fiber and a textile fabric having good UV-stability.

[0010] The object is solved by a fiber comprising a first component and a second component, wherein the first component comprises a first polymer and a first additive, and the second component comprises a second polymer and a second additive, characterized in that the first polymer is different to the second polymer and the first additive is different to the second additive.

[0011] Within the scope of the invention, the phrase "the first polymer is different to the second polymer" has to be understood that at least a part of the monomeric units of the first polymer is different to the monomeric units of the secondary polymer. Preferably, at least 50 %, more preferably at least 70 %, even more preferably 85 %, even more preferably 95 % of the monomeric units of the first polymer are different to the monomeric units of the second polymer. In a further preferred embodiment all monomeric units of the first polymer are different to the monomeric units of the second polymer.

[0012] The phrase "the first additive is different to the second additive" has to be understood that the first additive is chemically different to the second additive. Hence a first additive needs to be different in at least one atom, preferably in at least one functional group in its molecular structure, in view of the second additive.

[0013] Within the scope of the present invention it has to be understood that the term "fiber(s)" refers to both staple fiber(s) and filament(s). Staple fibers are fibers which have a specified, relatively short length in the range of 2 to 200 mm. Filaments are fibers having a length of more than 200 mm, preferably more than 500 mm, more preferably more than 1000 mm. Filaments may even be virtually endless, for example when formed by continuous extrusion and spinning of a filament through a spinning hole in a spinneret.

[0014] The first additive may be present in the first component as a blend, but it may also be possible that the first additive is co-polymerized into the first polymer or grafted onto the first polymer.

[0015] The second additive may be present in the second component as blend, but it may also be possible that the second additive is co-polymerized into the second polymer or grafted onto the second polymer.

[0016] In a preferred embodiment, the first additive is a first UV-stabilizer and the second additive is a second UV-stabilizer.

[0017] Within the scope of the invention, the term "UV-stabilizer" has to be understood in its broadest sense. The term comprises any additive which is able to contribute to the protection mechanism against UV-light, including e.g. antioxidants, UV-light absorbing compounds or UV-reflecting compounds.

[0018] In a further preferred embodiment, the first UV-stabilizer and the second UV stabilizer are selected from a group of molecules comprising functional groups of one or more hindered amines, one or more phenols, one or more triazines, one or more triazoles, and/or one or more benzotriazoles.

[0019] Preferably, the first UV-stabilizer comprises molecules comprising functional groups of one or more phenols and one or more benzotriazoles, and the second UV-stabilizer comprises molecules comprising functional groups of one or more hindered amines and one or more triazines.

[0020] In a more preferred embodiment the first UV-stabilizer is 2-[2-hydroxy-3,5-di-(1,1-dimethylbenzyl)]-2H-benzotriazole and the second UV-stabilizer is Poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]).

[0021] The fiber may comprise any suitable thermoplastic polymer as a first polymer and any suitable thermoplastic polymer as a second polymer, which is different to the first polymer.

[0022] In a preferred embodiment, the first polymer has a first melting temperature and the second polymer has a second melting temperature, wherein the second melting temperature of the second polymer is lower than the first melting temperature of the first polymer. The second melting temperatures of the second polymer is at least 5 °C, preferably at least 10 °C, more preferably at least 15 °C, even more preferably at least 20 °C, and most preferably at least 25 °C lower than the first melting temperature of the first polymer.

[0023] The melting temperatures of the first polymer and the second polymer are determined by Differential Scanning Calorimetry (DSC) as the temperature at the maximum value of the endothermic melting peak upon heating of the polymer at a rate of 20°C/min.

[0024] The advantage that the first polymer has a higher melting temperature than the second polymer is that second polymer can be used as a thermal bonding and/or consolidating agent by heating the second polymer to or close to its melting temperature, wherein the first polymer maintains its structural integrity.

[0025] Preferably, the first polymer and the second polymer are thermoplastic polymers, each selected from a group comprising polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene 1,4-furanodicarboxylate (PEF), polyamides such as polyamide 6 (PA6), polyamide 6,6 (PA6,6), polyolefins such as polyethylene (PE), polypropylene (PP), polybutylene (PB), and blends or copolymers thereof.

[0026] In a further preferred embodiment, the first polymer is a polyester and the second polymer is a polyamide. Preferably, the first polymer is polyethylene terephthalate (PET) and the second polymer is polyamide 6 (PA6).

[0027] In an embodiment, the second component surrounds the first component and wherein the fiber is of the island-in-the-sea model or of the core/sheath model. For clarity reasons, the first component constitutes the core in the fiber of the core/sheath model and the islands in the fiber of the island-in-the-sea model, and the second component constitutes the sheath in the fiber of the core/sheath model and the sea in the fiber of the island-in-the-sea model.

[0028] Preferably, the fiber is of a concentric or eccentric core/sheath model.

[0029] In the case of a fiber of the concentric core/sheath model, the properties of the components are distributed along the length of the fiber such that at any position in length of the fiber, the fiber has e.g. the same tensile strength, modulus and/or adhesion properties. Further, as the fiber of the concentric core/sheath model has a symmetrical cross section, the properties are also distributed uniformly in radial direction of the cross section. This can prevent an unwanted crimping.

[0030] Further, due to the core/sheath model it is possible to use different polymers for the core and the sheath such that specific demands can be targeted simultaneously. In the case, the core has a higher melting temperature than the sheath, it is possible to provide e.g. a fiber having a high tensile strength and the ability to be consolidated thermally in a textile fabric without deteriorating mechanical properties, e.g. the tensile strength, of the fiber.

[0031] This concept is also applicable to a fiber of the island-in-the-sea model.

[0032] In another preferred embodiment, the sheath of the fiber of the core/sheath model has an average thickness of 0.1 to 10 µm, preferably of 0.2 to 8 µm, more preferably of 0.4 to 7 µm, even more preferably of 0.8 to 6 µm, and most preferably of 1 to 5 µm.

[0033] The thickness of the sheath of the fiber of the core/sheath model is measured by scanning electron microscopy (SEM). Thereby, the SEM is used on a cross section of a fiber, or a yarn comprising the fiber or a nonwoven comprising the fiber and then measuring the thickness of core and sheath of the fiber. Within the scope of the invention, the average thickness of the sheath of the fiber of the core/sheath model has to be understood as the average distance between the surface of the fiber and the interface of the core and the sheath of the fiber.

[0034] As described above, by using a fiber of the core/sheath model, it is possible to combine properties by using different polymers. By variation of the average thickness of the sheath, the intensity of the properties of the sheath can be manipulated. As the average thickness is going to higher values e.g. above 5 µm, the properties of the sheath appear stronger, such as the protection of the core against UV-light irradiation. However, the transparency of the sheath decreases. If the average thickness is going to lower values e.g. below 1 µm the properties of the sheath appear less strong such as the protection of the core against UV-light irradiation, or also binding effect which are originating from the sheath. However, the transparency of the sheath increases.

[0035] In a further preferred embodiment, the first additive is present in the first component in an amount of at least 0.25 wt.-%, preferably of at least 0.5 wt.-%, more preferably of at least 1.0 wt.-%, even more preferably of at least 1.5 wt.-%, and most preferably of at least 2.0 wt.-% in view of total weight of the first component.

[0036] In another preferred embodiment, the second additive is present in the second component of at least 0.25 wt.-%, preferably of at least 0.5 wt.-%, more preferably of at least 1.0 wt.-%, even more preferably of at least 1.2 wt.-%, and most preferably of at least 1.5 wt.-% in view of the total weight of the second component.

[0037] In a further preferred embodiment, the first additive is present in the first component in an amount of at least 0.25 wt.-%, preferably of at least 0.5 wt.-%, more preferably of at least 1.0 wt.-%, even more preferably of at least 1.5 wt.-%, and most preferably of at least 2.0 wt.-% in view of total weight of the first component and the second additive is present in the second component of at least 0.25 wt.-%, preferably of at least 0.5 wt.-%, more preferably of at least 1.0 wt.-%, even more preferably of at least 1.2 wt.-%, and most preferably of at least 1.5 wt.-% in view of the total weight of the second component.

[0038] Without being bound to theory, it is believed that if the amount of the first additive in the first component is below 0.25 wt.-% and/or the amount of the second additive in the second component is below 0.25 wt.-%, the effect(s) of the additive(s) in the fiber deteriorate.

[0039] Further, without being bound to theory, it is believed that if the amount of a UV-stabilizer as the first additive in the first component is below 0.25 wt.-% and/or the amount of a UV-stabilizer in the second additive in the second component is below 0.25 wt.-%, the effect of protection of the fiber against UV-light irradiation deteriorates.

[0040] The first additive may be applied to the first component in a masterbatch, which means that a polymer masterbatch may comprise higher weight percentages of the additive, e.g. in the case the first component comprises 2 wt.-% of the first additive, the masterbatch comprising 40 wt.-% of the first additive is comprised in the polymer forming the first component in an amount of 5 wt.-%. This has to be understood as a concept, thus the percentage of the first additive in the master batch and the percentage of the masterbatch comprised in the first polymer can vary. The same concept is true for the second additive comprised in the second component.

[0041] Preferably, the first component and/or the second component comprises additionally to the first additive and the second additive further additives, such as processing stabilizer and/or fire retardant. The further additives can be phosphite compounds such as Irgafos 168 or hindered phenol compounds such as Irganox 245.

[0042] In a preferred embodiment, the first component comprises one or more coloring agents such as dyes or pigments.

[0043] The advantage of a core/sheath model fiber according to the invention comprising one or more coloring agents in the first component forming the core is that in particular in the embodiment when the sheath has a thickness of 0.1 to 10 µm, the color remains visible for the naked eye. Another advantage may be that the color in the core is protected against the fading caused by UV-light by the second additive comprised in the second component forming the sheath such that the fiber maintains its color for a prolonged period of time. This is also applicable to a fiber of the island-in-the-sea model.

[0044] In a further preferred embodiment, the fiber can have a cross-sectional area in a circular, elliptical, trilobal, square, rectangular from.

[0045] The object of the present application is also solved by a textile fabric comprising a fiber according to the invention.

[0046] As the textile fabric comprises the fibers according to the invention, the same advantages are provided by the textile fabric. Hence, the textile fabric may maintain its physical properties for a prolonged period of time.

[0047] The textile fabric can be a woven fabric, or a knitted fabric.

[0048] Such a textile fabric can be used for e.g. cloth, window shades, tents or blankets.

[0049] In a preferred embodiment, the textile fabric is a nonwoven.

[0050] Such a textile fabric may be used as e.g. carpet backing, carrier for bitumen membranes or as underslating.

[0051] The nonwoven may be carded nonwoven, a needled nonwoven, an air-laid nonwoven, a wet-laid nonwoven or a spunbonded/spun-laid nonwoven.

[0052] Within the scope of the present invention the terms "spunbonded" and "spun-laid", mean the production of a nonwoven in a one step process, wherein the fibers are extruded from a spinneret and subsequently laid down on a conveyor belt as a web of filaments and subsequently bonded the web to form a nonwoven layer of fibers, or by a two-step process, wherein filaments are spun and wound up on bobbins, preferably in the form of multifilament yarns, followed by the steps of unwinding the multifilament yarns and laying the filaments down on a conveyor belt as a web of filaments and bonding the web to form a nonwoven layer of fibers.

[0053] In the two-step process it is possible to provide high linear density filaments with a high stretching ratio due to mechanical stretching instead of using air. This can improve the stiffness and moldability.

[0054] The advantage of a two-step process is that a linear density, a pore size and a distribution of the pore size can be tuned to match the desired properties. Further, it can be possible to use different fibers (e.g. of different denier, different cross section) in only one nonwoven. Additionally, it could be possible to construct a nonwoven, which can comprise multiple plies having different properties.

[0055] In a preferred embodiment of the invention, the fibers comprised in the nonwoven are bicomponent fibers, preferably of the island-in-the-sea model or of the core/sheath model.

[0056] In a further preferred embodiment, the fibers comprised in the textile fabric are filaments.

[0057] Without being bound to theory, it is believed that the tensile strength along the filament in the textile fabric is increased in view of staple fibers such that the tensile strength and modulus of the textile fabric is also increased.

[0058] In another preferred embodiment, the textile fabric comprises one or more further layers of fibers, wherein the fibers in the one or more further layers of fibers comprise a lower amount of additives than the fibers according to the above described embodiments.

[0059] In a further preferred embodiment, the textile fabric comprises a layer of fibers according to the invention, which is exposed to weather, and at least one further layer which is embedded in a matrix such as bitumen or any suitable thermoplastic matrix.

[0060] For example, a textile fabric comprising three layers of fibers, wherein the layers are located plane parallel to each other, the layers located peripheral are used for the protection against UV-irradiation. Thus, it is believed that the layer located between the peripheral layers does not need additives or at least needs less amount of additives to maintain their physical properties.

[0061] Also possible is a textile fabric comprising more than three layers, wherein the peripheral layers comprise the additives in the fibers according to the invention. The further layers in the textile fabric have a decreasing gradient of the amount of additive in the fiber as greater the distance to the surface of the textile fabric is.

Claims

1. A fiber comprising a first component and a second component, wherein the first component comprises a first polymer and a first additive, and the second component comprises a second polymer and a second additive, characterized in that the first polymer is different to the second polymer and the first additive is different to the second additive.

2. The fiber according to claim 1, wherein the first additive is a first UV-stabilizer and the second additive is a second UV-stabilizer.

3. The fiber according to claim 2, wherein the first UV-stabilizer and the second UV stabilizer are selected from a group of molecules comprising functional groups of one or more hindered amines, one or more phenols, one or more triazines, one or more triazoles, and/or one or more benzotriazoles.

4. The fiber according to claims 2 or 3, wherein the first UV-stabilizer comprises molecules comprising functional groups of one or more phenols and one or more benzotriazoles and the second UV-stabilizer comprises molecules comprising functional groups of one or more hindered amines and one or more triazines.

5. The fiber according to claims 2 to 4, wherein the first UV-stabilizer is 2-[2-hydroxy-3,5-di-(1,1-dimethylbenzyl)]-2H-benzotriazole and the second UV-stabilizer is Poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]).

6. The fiber according to any of the preceding claims, wherein the first polymer and the second polymer are thermoplastic polymers, each selected from a group comprising polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene 1,4-furanodicarboxylate (PEF), polyamides such as polyamide 6 (PA6), polyamide 6,6 (PA6,6), polyolefins such as polyethylene (PE), polypropylene (PP), polybutylene (PB), and blends or copolymers thereof.

7. The fiber according to claim 6, wherein the first polymer is a polyester and the second polymer is a polyamide.

8. The fiber according to any of the preceding claims, wherein the second component surrounds the first component and wherein the fiber is of the island-in-the-sea model or of the core/sheath model.

9. The fiber according to claim 8, wherein the sheath of the fiber of the core/sheath model has an average thickness of 0.1 to 10 µm, preferably of 0.2 to 8 µm, more preferably of 0.4 to 7 µm, even more preferably of 0.8 to 6 µm, and most preferably of 1 to 5 µm.

10. The fiber according to any of the preceding claims, wherein the first additive is present in the first component in an amount of at least 0.25 wt.-%, preferably of at least 0.5 wt.-%, more preferably of at least 1.0 wt.-%, even more preferably 1.5 wt.-%, and most preferably of at least 2.0 wt.-% in view of total weight of the first component and the second additive is present in the second component of at least 0.25 wt.-%, preferably of at least 0.5 wt.-%, more preferably of at least 1.0 wt.-%, even more preferably 1.2 wt.-%, an most preferably 1.5 wt.-% in view of the total weight of the second component.

11. The fiber according to any of the claims 2 to 10, wherein the first component comprises one or more coloring agents such as dyes or pigments.

12. A textile fabric comprising a fiber according to claims 1 to 11.

13. The textile fabric according to claim 12, wherein the textile fabric is a woven fabric, or a knitted fabric.

14. The textile fabric according to claim 12, wherein the textile fabric is a nonwoven.

15. The textile fabric according to any of the claims 12 to 14, wherein the textile fabric comprises one or more further layers of fibers, wherein the fibers in the one or more further layers of fibers comprise a lower amount of additives than the fibers according to any of claims 1 to 11 or are free of additives.