Durable crimping of silk multifilaments or staple filaments

Abstract

The present invention relates to a method for air jet texturizing or air entangling a silk filament or multifilament. Further, the present invention relates to a texturized or entangled silk filament or multifilament obtained by this method. Furthermore, the present invention relates to a yarn comprising the texturized or entangled silk filament or multifilament. In addition, the present invention relates to the use of the silk filament, multifilament, or yarn in the textile industry.

Description

[0001] AMSilk GmbH

[0002] Our Ref.: 558-126 PCT

[0003] DURABLE CRIMPING OF SILK MULTIFILAMENTS OR STAPLE FILAMENTS

[0004] The present invention relates to a method for air jet texturizing or air entangling a silk filament or multifilament. Further, the present invention relates to a texturized or entangled silk filament or multifilament obtained by this method. Furthermore, the present invention relates to a yam comprising the texturized or entangled silk filament or multifilament. In addition, the present invention relates to the use of the silk filament, multifilament, or yam in the textile industry.

[0005] BACKGROUND OF THE INVENTION

[0006] It has long been known that certain filaments produced in nature possess remarkable mechanical properties in terms of strength, resilience and flexibility. These protein based filaments, exemplified by spider silk, have been the subject of much interest due to spider silk’s incredible toughness. Because of its strength, resilience and flexibility, spider silk holds great promise for commercial and consumer applications.

[0007] For some time now, it is possible to produce spider silk recombinantly, spin it into filaments and make yarns therefrom. The production of recombinant spider silk in commercial quantities holds the potential of materials, which are lighter, thinner, more flexible, and tougher than steel.

[0008] However, certain physical characteristics common to some natural filaments, such as wool and cotton, are not present in these silk filaments. As an instance, the filaments of wool in their natural form containing a plurality of crimps consisting of waves which are approximately sinusoidal in form with the number of crimps per inch in the individual filaments varying widely within the different grades of wool. It has been determined that these crimps are primarily responsible for the softer hand, greater warmth and ability to absorb moisture in wool as the crimps tend to hold the individual filaments in a wool yarn apart. In addition, the peculiar elastic qualities of wool are thought to stem in great degree from these crimps in that, when such filaments are stretched, the crimps are subjected to a straightening influence and in the straightened condition internal stresses are set up the net effect of which are to urge the filaments to assume their original crimp configuration.

[0009] Thus, there is a need for a new method that enables the generation of silk multifilaments or silk filaments with improved properties, such as improved haptic, optic, elasticity and / or thermal properties. Such a method would increase the industrial applicability of silk multifilaments or silk filaments manufactured therefrom.

[0010] The present inventors developed a new method for air jet texturizing or air entangling a silk filament or multifilament comprising the silk filament. In this method, a silk filament or multifilament comprising the silk filament in a working fluid is provided, and then passed / delivered along / to a pressurized air nozzle, where the silk filament or multifilament is subjected to non-laminar air flow texturing or air turbulence. Thereby, a texturized or entangled silk filament or multifilament is generated. This texturizing process results in the formation of loops, waves, and / or undulations. Such changes in the physical form of a filament affect the behaviour and hand of fabrics made therefrom. Said method, therefore, allows the production of silk filaments or multifilaments comprising the silk filament having improved properties with regard to haptic, optic, elasticity and / or thermal properties.

[0011] SUMMARY OF THE INVENTION

[0012] In a first aspect, the present invention relates to a method for air jet texturizing or air entangling a silk filament or multifilament comprising the silk filament comprising the steps of:

[0013] (i) providing a silk filament or multifilament comprising the silk filament in a working fluid, and

[0014] (ii) passing / delivering the silk filament or multifilament in the working fluid along / to a pressurized air nozzle, where the silk filament or multifilament is subjected to non- laminar airflow texturing or air turbulence, thereby generating a texturized or entangled silk filament or multifilament.

[0015] In a second aspect, the present invention relates to a texturized or entangled silk filament or multifilament obtainable / obtained by the method of the first aspect.

[0016] In a third aspect, the present invention relates to a silk filament or multifilament having a texturized or entangled structure comprising a repeating wave-like or crimped portion, wherein the filament exhibits a length reduction of at least 10%, preferably at least 30%, more preferably at least 50%.

[0017] In a fourth aspect, the present invention relates to a yam comprising the texturized or entangled silk filament or multifilament of the second or third aspect. In a fifth aspect, the present invention relates to an article comprising the texturized or entangled silk filament or multifilament of the second or third aspect or the yarn of the fourth aspect.

[0018] In a sixth aspect, the present invention relates to the use of the texturized or entangled silk filament or multifilament of the second or third aspect or the yarn of the fourth aspect in the textile industry.

[0019] In a seventh aspect, the present invention relates to the use of the texturized or entangled silk filament or multifilament of the second or third aspect or the yarn of the fourth aspect in the manufacture of a textile.

[0020] This summary of the invention does not necessarily describe all features of the present invention. Other embodiments will become apparent from a review of the ensuing detailed description.

[0021] DETAILED DESCRIPTION OF THE INVENTION

[0022] Definitions

[0023] Before the present invention is described in detail below, it is to be understood that this invention is not limited to the particular methodology, protocols and reagents described herein as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0024] Preferably, the terms used herein are defined as described in “A multilingual glossary of biotechnological terms: (TUPAC Recommendations)”, Leuenberger, H.G.W, Nagel, B. and Kolbl, H. eds. (1995), Helvetica Chimica Acta, CH-4010 Basel, Switzerland).

[0025] Several documents are cited throughout the text of this specification. Each of the documents cited herein (including all patents, patent applications, scientific publications, manufacturer's specifications, instructions, GenBank Accession Number sequence submissions etc.), whether supra or infra, is hereby incorporated by reference in its entirety. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention. In the event of a conflict between the definitions or teachings of such incorporated references and definitions or teachings recited in the present specification, the text of the present specification takes precedence. The term “comprise” or variations such as “comprises” or “comprising” according to the present invention means the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. The term “consisting essentially of’ according to the present invention means the inclusion of a stated integer or group of integers, while excluding modifications or other integers which would materially affect or alter the stated integer. The term “consisting of’ or variations such as “consists of’ according to the present invention means the inclusion of a stated integer or group of integers and the exclusion of any other integer or group of integers.

[0026] The terms “a” and “an” and “the” and similar reference used in the context of describing the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

[0027] The terms “polypeptide” and “protein” are used interchangeably in the context of the present invention.

[0028] The present invention relates to a method for air jet texturizing or air entangling a silk filament or multifilament comprising the silk filament.

[0029] The term “air jet texturizing”, as used herein, refers to a process to create textured filaments or multifilaments by using a high-speed air stream. This technique involves feeding a continuous filament or multifilament through a jet of compressed air, which disrupts the linear arrangement of the filaments. The air causes the filaments to form loops, tangles, waves, undulations and / or other surface irregularities, resulting in textured filaments or multifilaments with characteristics such as improved bulk, softness, and elasticity.

[0030] The process not necessarily involves heat or chemicals, making it a mechanical texturizing method. Air jet texturized filaments or multifilaments have improved properties like an increased volume, a soft touch, and a resemblance to natural filaments such as cotton or wool, while maintaining the strength and durability of synthetic materials. Commonly, these filaments or multifilaments are employed in fabrics for clothing, upholstery, and other industrial textiles. Besides a continuous filament or multifilament, also short filaments such as staple filaments may be air jet texturized.

[0031] The term “air entangling” (also known as “intermingling”), as used herein, is a mechanical process to bind individual filaments within a multifilament together by using compressed air. In this process, a jet of air is directed at the filaments as it passes through a specially designed nozzle. The air creates small, localized tangles or nodes along the filament’s length, which help hold the filaments together without the need for twisting. This technique improves the cohesion and handling properties of the filaments, making it easier to process in downstream applications like weaving, knitting, or further textile production. Air entangled filaments maintain their smooth appearance, while benefiting from enhanced stability, reduced filament separation, and improved uniformity. This method is commonly used for further processing filaments / multifilaments in applications like apparel, home textiles, and industrial fabrics.

[0032] The present invention relates to the (further) processing / finishing of filaments or multifilaments after their production. Generally, the term “texture” in textiles characterises the surface as rough or smooth, which is determined by tactile and visual perception. The texture of textiles is affected by yam manipulations, finishing techniques, and fabric structures. In this respect, the term “texturizing”, as used herein, refers to a process by which filaments (e.g. synthetic filaments) are modified to change their texture - the physical appearance of the filaments. Texturizing takes advantage of the plastic deformation capacity of filaments (e.g. synthetic filaments), and uses it to set texturized features in place.

[0033] For example, filaments may be texturized to improve the fibre's insulation properties (as processes like bulking allow it to trap air better), to minimise a shiny, synthetic-looking appearance, to reduce the silky nature of the fibre, and / or to create special effects (fancy yams). Specifically, texturizing is the formation of crimps, loops, coils, waves, and / or crinkles in filaments. Such changes in the physical form of the filaments affect the behaviour and hand of fabrics made from them. For example, the modifications introduced by texturizing improve the drape, appearance, luster, warmth, elasticity, and / or handle of articles comprising the filaments, e.g. finished fabrics.

[0034] In this regard, the term “hand / handle”, as used herein, is a general term for the characteristics perceived by the sense of touch when a yarn, yam bundle, or fabric is held in the hand, such as drapability, softness, elasticity, coolness or warmth, stiffness, roughness, and resilience.

[0035] The term “non-laminar air flow” (also known as “turbulent air flow”), as used herein, refers to a type of airflow in which the air does not move in smooth, parallel layers, but instead follows irregular, chaotic paths. In this state, the velocity, pressure, and direction of the air continuously fluctuate in an unpredictable manner.

[0036] Non-laminar airflow occurs when the flow rate exceeds a critical threshold, or when obstacles and irregularities disrupt the smooth flow of air, leading to eddies, swirls, and vortices. This type of airflow is commonly encountered in natural environments, industrial processes, and aerodynamic applications, where it can influence factors like drag, heat transfer, and mixing efficiency.

[0037] In contrast, the term “laminar air flow”, as used herein, refers to a type of airflow which is smooth and orderly, with air particles moving in parallel layers without significant mixing between them.

[0038] The terms “non-laminar air flow texturing” or “air turbulence texturing”, as used herein, refers to a process used to modify the structure and surface properties of filaments or multifilaments by utilizing turbulent airflow. Unlike laminar flow, where air moves smoothly, non-laminar or turbulent airflow creates chaotic and high-energy patterns that interact with the filaments or multifilaments when they pass through a jet or nozzle.

[0039] In this process, the turbulent air disrupts the arrangement of the individual filaments or multifilaments, forming loops, tangles, waves, undulations, and / or textures. The resulting filaments or multifilaments have increased bulk, elasticity, and softness, with a structure resembling natural filaments like cotton or wool. This method is especially used in creating airtextured filaments or multifilaments, which are valued for their versatility and resemblance to natural spun yarns.

[0040] The use of non-laminar air flow allows for precise control over the texturing effects, making it a preferred method in producing filaments or multifilaments for applications such as active wear, upholstery, and other textiles requiring specific aesthetic and functional properties.

[0041] The term “pressurized air nozzle”, as used herein, refers to a device designed to direct and control the flow of compressed air with precision. It typically features an inlet for the compressed air and an outlet with a specific shape or configuration that determines the velocity, pressure, and direction of the exiting air stream.

[0042] In industrial applications, pressurized air nozzles are used for various purposes, such as cleaning, drying, cooling, or conveying materials. In the textile industry, they are integral to processes like air texturizing or air entangling, where high-speed air streams manipulate filaments or multifilaments to create desired textures, tangles, or other structural modifications. The design of a pressurized air nozzle, including its dimensions and geometry, is crucial for optimizing performance, efficiency, and safety in specific applications. Preferably, the pressurized air nozzle is a Venturi nozzle.

[0043] The term “Venturi nozzle”, as used herein, refers to a device that uses the Venturi effect to create a drop in pressure and increase the velocity of a fluid or gas as it flows through a constricted section of the nozzle. It consists of three main sections:

[0044] (i) an inlet opening configured to receive the working fluid into a flow channel, (ii) a constricted section (throat) that reduces the cross-sectional area of the flow channel to increase the working fluids velocity and decrease its static pressure, and

[0045] (iii) a downstream diffuser section with a gradually increasing cross-sectional area to reduce the velocity and restore the fluid pressure, wherein the geometry of the nozzle is designed to optimize flow conditions within the nozzle by generating a vacuum in the constricted section.

[0046] The term “Venturi effect”, as used herein, refers to a principle in fluid dynamics that describes how the pressure of a (working) fluid (liquid or gas) decreases as the (working) fluid flows through a constricted section of a pipe or channel, while its velocity increases. This phenomenon is a direct consequence of the principle of conservation of energy and Bernoulli’s equation, which relates the pressure, velocity, and potential energy of a moving fluid.

[0047] The key characteristics of the Venturi effect are:

[0048] Velocity Increase: When the cross-sectional area of the flow channel decreases, the (working) fluid is forced to speed up to maintain the same flow rate.

[0049] Pressure Decrease: The increased velocity results in a reduction of pressure in the constricted section.

[0050] Applications: This effect is widely used in devices like Venturi nozzles.

[0051] The term “filament”, as used herein, refers to a material that is significantly longer than it is wide. The filament can be present as continuous strand, staple filament, or in a discrete elongated piece. The term “filament”, as used herein, further encompasses a single-drawn or multi-drawn (e.g. double-drawn) filament. Said filament has been stretched one or more times during its preparation process, in particular wet-spinning process. An exemplarily process for producing a filament which may be used in the present invention is described in WO 2014 / 037453. The filament can be a natural or synthetic (e.g. recombinant) filament.

[0052] The term “multifilament”, as used herein, refers to a material that is composed of multiple filaments, usually made from synthetic or natural filaments. These filaments are packed together to form a bundle. The number of filaments in the bundle usually corresponds to the number of openings in the product! on / spinning nozzle through which they were formed. A multifilament is known for its smoothness, softness, and flexibility, and it can be engineered to provide specific characteristics like strength, elasticity, or bulk. A multifilament is widely used in textiles, ranging from delicate fabrics to more robust applications such as ropes, industrial fabrics, or sportswear. The properties of the multifilament can be further enhanced or modified through processes like air jet texturizing or air entangling. In one embodiment, the filament or multifilament comprising the filament is a continuous / infinite long filament or multifilament. Preferably, the continuous filament or multifilament has a length of between 500 and 100.000 m, e.g. a length of 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10.000, 20.000, 30.000, 40.000, 50.000, 60.000, 70.000, 80.000, 90.000, or 100.000 m.

[0053] In one another embodiment, the filament or multifilament comprising the filament is a finite long filament or multifilament such as a staple filament. Preferably, the staple filament has a length of between 15 and 70 mm, e.g. a length of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 mm.

[0054] The term “staple filament”, as used herein, refers a filament of discrete length. The opposite is a filament, which comes in continuous lengths. Staple length is a characteristic filament length of a sample of staple filaments. It is an essential criterion in yam spinning, and aids in cohesion and twisting. Preferably, the staple filament has a length of between 15 and 70 mm, e.g. a length of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 mm.

[0055] The filaments or multifilaments described herein are specifically silk filaments or multifilaments. They comprise a silk polypeptide. The term “silk polypeptide”, as used herein, refers to a polypeptide which shows, in comparison to other polypeptides, a quite aberrant amino acid composition. In particular, a silk polypeptide possess large quantities of hydrophobic amino acids such as glycine or alanine, but, for example, no (or only very little) tryptophan. In addition, a silk polypeptide contains highly repetitive amino acid sequences or repetitive units (repeat units, modules), especially in their large core domain.

[0056] Based on DNA analysis, it was shown that all silk polypeptides are chains of repetitive units which further comprise a limited set of distinct shorter peptide motifs. The expressions “peptide motif’ and “consensus sequence” can be used interchangeably herein. Generally, the silk consensus sequences can be grouped into four major categories: GPGXX, GGX, Axor (GA)nand spacers. These categories of peptide motifs in silk polypeptides have been assigned structural roles. For example, it has been suggested that the GPGXX motif is involved in a P- turn spiral, probably providing elasticity. The GGX motif is known to be responsible for a glycine-rich 3i-helix. Both GPGXX and GGX motifs are thought to be involved in the formation of an amorphous matrix that connects crystalline regions, thereby providing elasticity of the filament. Alanine-rich motifs typically contain 6-9 residues and have been found to form crystalline P-sheets. The spacers typically contain charged groups and separate the iterated peptide motifs into clusters. Preferably, the silk polypeptide is a spider silk polypeptide. More preferably, the silk polypeptide, e.g. spider silk polypeptide, is a recombinant polypeptide.

[0057] The silk filament or multifilament comprising the silk filament is formed by extruding a solution comprising a silk polypeptide through a spinneret nozzle having one or more spinning holes. Upon extrusion, the silk filament has preferably a diameter in the range of between 5 pm and 200 pm, e.g. a diameter of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,

[0058] 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,

[0059] 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98,

[0060] 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 pm, or the silk multifilament has preferably a diameter in the range of between 20 pm pm and 1000 pm, e.g. a diameter of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,

[0061] 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,

[0062] 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,

[0063] 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300, 400, 500, 600, 700,

[0064] 800, 900, or 1000 pm.

[0065] In one embodiment, the extruded silk filament or multifilament is subsequently extended in a stretching / drawing step.

[0066] Without wishing to be bound by any theory, it is believed that the extension / stretch leads to an alignment and more regular distribution of the silk polypeptide molecules within the filament and, thereby, improves the properties of the filament. It is preferred that the filament is extended after it has been extruded. Such extension can be carried out in a continuous or discontinuous process. In the continuous process it is preferred that the filament is exposed to a pulling force. Preferably, the extension of the filament is by at least 2-fold in comparison to the length of the filament as extruded, more preferably the extension is at least 4-fold, at least 5-fold, at least 6- fold, at least 7-fold, or at least 8-fold, and even more preferably at least 10-fold.

[0067] During extension the cross-sectional area of the filament is reduced. For example, the extension / stretch leads to a reduction of the cross-sectional area of at least 10, 20, 30, 40, 50, 60, or 70%.

[0068] The extension may be carried out in the presence of a coagulation solution. In this case, the filament - after extrusion of a dope solution from a spinneret or after generation by drawing - is fed or at least partially submerged in the coagulation solution for precipitation and solidification. It is (alternatively or additionally) also possible to carry out the extension in one or more washing solutions. Therefore, the filament is - after incubation in the coagulation solution - transferred into one or more washing solutions. To achieve the extension, the filament is pulled out of the coagulation solution and / or the one or more washing solutions. This process is carried out under tension. The skilled person is well aware of various methods to apply a defined pulling force to achieve the above outlined extension. If, for example, the filament is drawn or extruded from the nozzle of the spinneret with a speed of 10 cm / s and the filament is subsequently wound up with a speed of 1 m / s, the extension will be at least 10-fold. The skilled person is well aware of various methods to stretch an extruded filament in a predetermined way. For example, a roller may be positioned behind the nozzle that draws out the filament with a speed of 1 m / s, the next roller moves with a speed of 2 m / s and subsequent rollers may have an even higher speed, which will lead to an incremental increase of the stretching. As outlined above, the foldness of extension is calculated on the basis of the filament as drawn or extruded and the product at the end of the stretching (and possible relaxing) process.

[0069] The stretched / extended filament can be a single-drawn and multi-drawn (e.g. double-drawn) filament. The stretched / extended filament can also be a full drawn filament, i.e. a filament that is (almost) completely stretched / extended (until shortly before the filament was pulled off) after its production.

[0070] Upon extension, the silk filament has preferably a diameter in the range of between 2.5 pm and 100 pm, e.g. a diameter of 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,

[0071] 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,

[0072] 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69,

[0073] 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94,

[0074] 95, 96, 97, 98, 99, or 100 pm, or the silk multifilament has preferably a diameter in the range of between 20 pm pm and 500 pm, e.g. a diameter of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,

[0075] 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,

[0076] 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80,

[0077] 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300, 400, or 500 pm.

[0078] The terms “filament” and fiber” are used interchangeably in the context of the present invention.

[0079] The term “yarn”, as used herein, refers to a strand composed of filaments, either natural or synthetic. The term “yam”, as used herein, also refers to a long continuous length of interlocked filaments, twisted filaments, or filaments grouped together (but not interlocked or twisted). The yam can be used in sewing, crocheting, knitting, weaving, embroidery, rope making, and the production of textiles.

[0080] The yarn is composed of 2 or more filaments (monofilaments). Thus, a yam is a multifilament which is composed of a number of monofilaments. These filaments are twisted, interlocked, or grouped together.

[0081] For example, a yam is a multifilament which is composed of between 2 and 10000 filaments, preferably between 2 and 1000 filaments, and more preferably between 2 and 500 filaments, e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000 filaments.

[0082] The yarn may be present in staple form. In this respect, the term “staple-spun yarn”, as used herein, refers to a linear assembly of many filaments in the cross section and along the length, held together usually by the insertion of twist to form a continuous strand, small in diameter but of any specified length. It is used for interlacing in processes such as knitting, weaving, and sewing.

[0083] The term “article”, as used herein, refers to any object comprising or consisting of the texturized or entangled silk filament or multifilament of the present invention. It is preferred that the article is a textile / fabric. It is more preferred that the textile / fabric is / part of a garment, an apparel, or footwear (e.g. a shoe). It is also more preferred that the textile / fabric is a technical textile, smart textile, industrial fabric, or a high-performance material.

[0084] The textile / fabric may be a woven textile / fabric or a knitted textile / fabric. The garment may be a fashion, a sport, an outdoor, a medical, or an orthopaedic garment. Particularly, the garment may be fashion articles, fashion goods, shirts, socks, stockings, e.g. compression stockings, medical stockings, or support stockings, tights, e.g. support tights, pants, e.g. sport or outdoor pants, underwear, e.g. sport or outdoor underwear, gloves, caps, storm hoods, footwear or bandages.

[0085] The term “synthetic material”, as used herein, refers to a material that has been manufactured or otherwise created by human beings, as opposed to those occurring in nature. The synthetic material is preferably a synthetic filament. The term “synthetic filament” also covers a filament which is recombinantly produced. More preferably, the synthetic filament is selected from the group consisting of a plastic filament, a recombinant polypeptide filament, a PET filament, a PA filament, a PP filament, and an EA filament. The word “synthetic” also means artificially put together in the context of the present invention. The term “naturally material / natural occurring material”, as used herein, refers to a material which exists in nature, which may, however, be modified and further processed, e.g. by bleaching, washing, stretching, spinning etc., as long as the modification does not significantly alter the polymer backbone of the material. The naturally material / natural occurring material is preferably a natural / naturally occurring filaments. More preferably, the natural / naturally occurring filament is selected from the group consisting of a cotton filament, a flax filament, a wool filament, a hemp filament, a bamboo filament, a cellulose filament, and a silk filament (e.g. spider silk filament).

[0086] The term “silk polypeptide”, as used herein, refers to a polypeptide which shows, in comparison to other polypeptides, a quite aberrant amino acid composition. In particular, a silk polypeptide possess large quantities of hydrophobic amino acids such as glycine or alanine, but, for example, no (or only very little) tryptophan. In addition, a silk polypeptide contains highly repetitive amino acid sequences or repetitive units (repeat units, modules), especially in their large core domain.

[0087] Based on DNA analysis, it was shown that all silk polypeptides are chains of repetitive units which further comprise a limited set of distinct shorter peptide motifs. The expressions “peptide motif’ and “consensus sequence” can be used interchangeably herein. Generally, the silk consensus sequences can be grouped into four major categories: GPGXX, GGX, Axor (GA)nand spacers. These categories of peptide motifs in silk polypeptides have been assigned structural roles. For example, it has been suggested that the GPGXX motif is involved in a P- turn spiral, probably providing elasticity. The GGX motif is known to be responsible for a glycine-rich 3i-helix. Both GPGXX and GGX motifs are thought to be involved in the formation of an amorphous matrix that connects crystalline regions, thereby providing elasticity of the filament. Alanine-rich motifs typically contain 6-9 residues and have been found to form crystalline P-sheets. The spacers typically contain charged groups and separate the iterated peptide motifs into clusters. Preferably, the silk polypeptide is a spider silk polypeptide. More preferably, the silk polypeptide, e.g. spider silk polypeptide, is a recombinant polypeptide.

[0088] Embodiments of the invention

[0089] The present invention will now be further described. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous, unless clearly indicated to the contrary.

[0090] The present inventors developed a new method for air jet texturizing or air entangling a silk filament or multifilament comprising the silk filament. In this method, a silk filament or multifilament comprising the silk filament in a working fluid is provided, and then passed / delivered along / to a pressurized air nozzle, where the silk filament or multifilament is subjected to non-laminar air flow texturing or air turbulence. Thereby, a texturized or entangled silk filament or multifilament is generated. This texturizing process results in the formation of loops, waves, and / or undulations. Such changes in the physical form of a silk multifilament or silk filament affect the behaviour and hand of fabrics made therefrom. Said method, therefore, allows the production of silk filaments or multifilaments comprising the silk filament having improved properties with regard to haptic, optic, elasticity and / or thermal properties.

[0091] Thus, in a first aspect, the present invention relates to a method for air jet texturizing or air entangling a (at least one) silk filament or multifilament comprising the (at least one) silk filament comprising the steps of:

[0092] (i) providing a (at least one) silk filament or multifilament comprising the (at least one) silk filament in a working fluid, and

[0093] (ii) guiding / passing / delivering the (at least one) silk filament or multifilament in the working fluid along / to a pressurized air nozzle, where the (at least one) silk filament or multifilament is subjected to non-laminar air flow texturing or air turbulence, thereby generating a (at least one) texturized or entangled silk filament or multifilament.

[0094] In particular, the method for air-jet texturizing or air-entangling a silk filament or a multifilament comprising at least one silk filament comprises the steps of:

[0095] (i) providing the silk filament or multifilament in a working fluid, and

[0096] (ii) guiding the silk filament or multifilament in the working fluid to or along a pressurized air nozzle, wherein the silk filament or multifilament is subjected to non-laminar air flow or air turbulence generated by the nozzle, thereby producing a texturized or entangled silk filament or multifilament.

[0097] Specifically, the pressurized air nozzle causes air turbulences deforming the linear form of the (at least one) silk filament or multifilament and transforming it into a wave shape or crimped structure. In any case, the (at least one) air treated silk filament or multifilament has loops, waves, and / or undulations. The fact that the method of the present invention produces silk filament or multifilament controlled crimp and entanglement without damage is surprising. In one embodiment, the pressurized air nozzle generated turbulences with an amplitude of between 0.5 and 5 mm, preferably of between 0.5 and 3 mm, e.g. 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mm, and / or a frequency of between 1 and 20 waves / cm, preferably of between 5 and 20 waves / cm, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 waves / cm.

[0098] In one another embodiment, the subjection of the (at least one) silk filament or multifilament to the non-laminar air flow leads to a length reduction / shrinkage of the (at least one) silk filament or multifilament of at least 10%, preferably of at least 30%, and more preferably of at least 50%, e.g. of at least 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50%.

[0099] In one preferred embodiment, the (at least one) silk filament or multifilament which is passed along the air texturizing nozzle is in a wet state / not dried.

[0100] For example, the (at least one) silk filament or multifilament has a moisture content of at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least

[0101] 90%, at least 95% or even 100%, e.g. at least 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,

[0102] 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,

[0103] 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82,

[0104] 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or even 100%.

[0105] The (at least one) silk filament or multifilament is preferably passed along / delivered to the pressurized air nozzle via a delivering device. For example, the delivering device is a tube through which a working fluid is used to guide the (at least one) filament or multifilament along a spinning machine, along drawing godets, wash or drying sections, and / or texturizing devices. An exemplarily delivering device is shown in Figure 3.

[0106] In one more preferred embodiment, the pressurized air nozzle is a Venturi nozzle. Specifically, the Venturi nozzle comprises

[0107] (i) an inlet opening configured to receive the working fluid into a flow channel,

[0108] (ii) a constricted section (throat) that reduces the cross-sectional area of the flow channel to increase the working fluids velocity and decrease its static pressure, and

[0109] (iii) a downstream diffuser section with a gradually increasing cross-sectional area to reduce the velocity and restore the fluid pressure, wherein the geometry of the nozzle is designed to optimize flow conditions within the nozzle by generating a vacuum in the constricted section.

[0110] More specifically, the Venturi nozzle generated turbulences with an amplitude of between 0.5 and 5 mm, preferably of between 0.5 and 3 mm, e.g. 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 mm, and / or a frequency of between 1 and 20 waves / cm, preferably of between 5 and 20 waves / cm, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 waves / cm.

[0111] The combination of wet processing, fluid guidance and Venturi turbulence is not derivable from the known processes for synthetic, non-protein derived fibers. The method of the present invention results in: controlled wave-like or crimped structure, length reduction, increased bulkiness, improved cohesion between filaments, and / or better yarn handling. These effects arise specifically from wet state processing, fluid environment, and Venturi-induces turbulence. An exemplarily Venturi nozzle is shown in Figure 2.

[0112] In one even more preferred embodiment, the method comprises the steps of:

[0113] (i) introducing the (at least one) silk filament or multifilament in the working fluid via an / the inlet opening into a / the flow channel of the Venturi nozzle,

[0114] (ii) accelerating the (at least one) silk filament or multifilament in the working fluid through a / the constricted section (throat) of the nozzle, thereby increasing the fluid velocity and decreasing the static pressure,

[0115] (iii) subjecting the (at least one) silk filament or multifilament to differential drag forces and air turbulences in the constricted section (throat), resulting in the formation of a (at least one) wave-like or crimped silk filament or multifilament,

[0116] (iv) optionally applying heat to the (at least one) silk filament or multifilament during the process to soften the (at least one) silk filament or multifilament and enable permanent waves or crimps, and

[0117] (v) allowing the (at least one) waved or crimped silk filament or multifilament to exit the nozzle through a diffuser section, where the working fluid velocity decreases and the pressure stabilizes, thereby retaining the waved or crimped structure in the (at least one) silk filament or multifilament.

[0118] An exemplarily texturizing process is shown in Figure 1.

[0119] The use of a Venturi-type nozzle was found to be particularly suitable in the present method. A Venturi nozzle comprises an inlet opening for introducing the silk filament or multifilament in the working fluid into a flow channel, a constricted throat region, and a downstream diffuser section. When the working fluid and the filament are accelerated through the constricted section (throat), the cross-sectional area is reduced, resulting in an increase in fluid velocity and a corresponding decrease in static pressure. This pressure gradient creates a region of reduced pressure or partial vacuum within the throat. Without wishing to be bound by theory, it is believed that this local pressure reduction stabilises the wet silk filament while it is subjected to differential drag forces and air turbulences in the throat. The presence of the working fluid supports the filament against excessive mechanical stress, and the altered pressure conditions help to maintain filament integrity during the deformation process.

[0120] When the accelerated fluid and the filament exit the throat into the diffuser section, the cross- sectional area gradually increases and the velocity of the working fluid decreases, allowing the static pressure to stabilise again. It is believed that this region, in which the flow transitions and non-laminar or turbulent flow conditions occur, contributes to the formation of wave-like or crimped structures along the filament. The combination of increased flow velocity, pressure variation and turbulent eddies appears to deform the originally linear filament into a repeating pattern, and this structure is retained when the filament exits the nozzle through the diffuser section. These results were surprising for the present inventors, as conventional air-jet texturing processes for synthetic fibres are generally carried out on dry, thermoplastic filaments and do not make use of a working fluid or a Venturi geometry. Such processes would not have been expected to be suitable for delicate silk filaments, which are prone to damage in the dry state. In contrast, the use of a Venturi nozzle in a fluid environment enabled controlled deformation of the wet silk filament without rupture, and resulted in stable wave-like or crimped structures that could not have been predicted from the prior art on synthetic fibres.

[0121] The working fluid may be a gas or liquid. It flows to guide / transport the (at least one) silk filament or multifilament. The choice of gas or liquid as working medium depends on the specific application and the physical properties of the (at least one) filament or multifilament being processed. The working liquid is preferably selected from the group consisting of an aqueous solution (such as water or a buffered aqueous solution) and a solution comprising synthetic polymers such as polyethylene glycol (PEG). The working gas is preferably selected from the group consisting of (ambient) air, nitrogen, carbon dioxide, and noble gases.

[0122] The (at least one) silk filament or multifilament comprising the (at least one) silk filament may be a continuous / infinite long silk filament or multifilament. Preferably, the (at least one) continuous filament or multifilament has a length of between 500 and 100.000 m, e.g. a length of 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10.000, 20.000, 30.000, 40.000, 50.000, 60.000, 70.000, 80.000, 90.000, or 100.000 m.

[0123] Alternatively, the (at least one) silk filament or multifilament comprising the (at least one) silk filament may be a finite long silk filament or multifilament such as a staple silk filament or multifilament. Preferably, the (at least one) staple silk filament or multifilament has a length of between 15 and 70 mm, e.g. a length of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 mm. The (at least one) silk filament or multifilament comprising the (at least one) silk filament provided in step (i) is preferably formed by extruding a solution comprising a silk polypeptide through a spinneret nozzle having one or more spinning holes.

[0124] Extrusion in this context means the application of pressure to the solution to force it through a spinneret nozzle having one or more spinning holes. In the art of polymer technology, extrusion processes are often used to form filaments from molten thermoplasts, i.e. the entire extruded material solidifies after it has left the opening. In the context of the present invention, the extruded solution does not solidify entirely. Rather the dissolved polymers that are comprised in the extruded solution associate to form a filament, which is typically smaller in diameter than the opening through which the solution is extruded, while the remaining solvent is separated from the filament thus formed. In some embodiments, the filament initially formed is attached to a filament recovery device, e.g. a cylinder, spool or bobbin, onto which the filament is continuously wound. Depending on the relative speed of the, e.g. cylinder, with respect to the speed of filament formation during extrusion, there may also be a pulling force exerted onto the extruded filament, i.e. the filament in some embodiments may be considered to be drawn from the extruded solution.

[0125] Particularly, a spinneret nozzle having between 1 and 1000 spinning holes, more particularly a spinneret nozzle having between 1 and 500 spinning holes, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,

[0126] 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,

[0127] 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,

[0128] 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 150, 200, 250, 300, 350, 400, 450, 500,

[0129] 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 spinning holes, is used.

[0130] The number of silk filaments produced in the extrusion process corresponds to the number of holes in the nozzle through which they were formed.

[0131] Alternatively or additionally, a spinneret nozzle with spinning holes having a diameter of between 10 pm and 500 pm, e.g. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,

[0132] 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,

[0133] 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75,

[0134] 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 150, 200, 250, 300, 350, 400, 450, or 500 pm, is used.

[0135] The solution comprising the silk polypeptide may comprise an organic or inorganic solvent. A preferred organic solvent is formic acid, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), or hexafluoroisopropanol (HFIP). The concentration of the silk polypeptide in the solution may be between 5% and 50%, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50%. Particularly, the concentration of the silk polypeptide in the solution is between 5% and 40%. More particularly, the concentration of the silk polypeptide in the solution is between 10% and 30%. More preferably, the solution comprising the silk polypeptide is extruded into a coagulation bath. The coagulation bath may comprise alcohol, e.g. ethanol, butanol, methanol, propanol, polyethylene glycol, or isopropanol. The alcohol can be mixed with water or fully demineralised water in a concentration between 10% and 95%, e.g. 10, 11, 12, 13, 14, 15, 16,

[0136] 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,

[0137] 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,

[0138] 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,

[0139] 92, 93, 94, or 95%.

[0140] Upon extrusion, the (at least one) silk filament has particularly a diameter in the range of between 5 pm and 200 pm, e.g. a diameter of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 pm, or the (at least one) silk multifilament has particularly a diameter in the range of between 20 pm pm and 1000 pm, e.g. a diameter of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,

[0141] 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,

[0142] 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84,

[0143] 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170,

[0144] 180, 190, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 pm.

[0145] Even more preferably, the (at least one) extruded silk filament or multifilament is subsequently extended in a stretching / drawing step. The stretching / drawing step may be carried out in a stretching / drawing bath. The stretching / drawing bath may comprise alcohol, particularly ethanol, butanol, methanol, propanol, polyethylene glycol, or isopropanol. The alcohol can be mixed with water or fully demineralised water in a concentration between 0% and 50%, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50%. Without wishing to be bound by any theory, it is believed that the extension / stretch leads to an alignment and more regular distribution of the silk polypeptide molecules within the filament and, thereby, improves the properties of the filament. It is preferred that the filament is extended after it has been extruded in a continuous or discontinuous process. In the continuous process it is preferred that the filament is exposed to a pulling force. Specifically, the extension of the filament is by at least 2-fold in comparison to the length of the filament as extruded, more specifically the extension of the filament is by at a least 4-fold, at least 5-fold, at least 6-fold, at least 7-fold, or at least 8-fold, and even more specifically the extension of the filament is by at least 10-fold.

[0146] During extension the cross-sectional area of the filament is reduced. For example, the extension / stretch leads to a reduction of the cross-sectional area of at least 10, 20, 30, 40, 50, 60, or 70%.

[0147] The extension may be carried out in the presence of a coagulation solution. In this case, the filament - after extrusion of a dope solution from a spinneret or after generation by drawing - is fed or at least partially submerged in the coagulation solution for precipitation and solidification. It is (alternatively or additionally) also possible to carry out the extension in one or more washing solutions. Therefore, the filament is - after incubation in the coagulation solution - transferred into one or more washing solutions. To achieve the extension, the filament is pulled out of the coagulation solution and / or the one or more washing solutions. This process is carried out under tension. The skilled person is well aware of various methods to apply a defined pulling force to achieve the above outlined extension. If, for example, the filament is drawn or extruded from the nozzle of the spinneret with a speed of 10 cm / s and the filament is subsequently wound up with a speed of 1 m / s, the extension will be at least 10-fold. The skilled person is well aware of various methods to stretch an extruded filament in a predetermined way. For example, a roller may be positioned behind the nozzle that draws out the filament with a speed of 1 m / s, the next roller moves with a speed of 2 m / s and subsequent rollers may have an even higher speed, which will lead to an incremental increase of the stretching. As outlined above, the foldness of extension is calculated on the basis of the filament as drawn or extruded and the product at the end of the stretching (and possible relaxing) process.

[0148] The stretched / extended filament can be a single-drawn and multi-drawn (e.g. double-drawn) filament. The stretched / extended filament can also be a full drawn filament, i.e. a filament that is (almost) completely stretched / extended (until shortly before the filament was pulled off) after its production. Upon extension, the (at least one) silk filament has particularly a diameter in the range of between 2.5 pm and 100 pm, e.g. a diameter of 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13,

[0149] 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,

[0150] 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,

[0151] 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,

[0152] 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 pm, or the (at least one) silk multifilament has particularly a diameter in the range of between 20 pm pm and 500 pm, e.g. a diameter of 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,

[0153] 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60,

[0154] 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85,

[0155] 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170,

[0156] 180, 190, 200, 300, 400, or 500 pm.

[0157] In one still even more preferred embodiment, the method further comprises step (iii) of spinning the (at least one) multifilament into a yarn, or spinning the (at least one) silk filament together with one or more filaments of a different material into a yarn.

[0158] Particularly, the (at least one) multifilament is spun into a yam together with one or more filaments of a different material.

[0159] The yarn may be a continuous / infinite long yarn composed of multifilaments or a finite long staple yarn composed of staple filaments.

[0160] More particularly, the one or more filaments of the different material are synthetic filaments, natural filaments or regenerated filaments.

[0161] Even more particularly,

[0162] (a) the synthetic filaments are selected from the group consisting of plastic filaments, recombinant polypeptide filaments, PET filaments, PA filaments, PP filaments, and EA filaments,

[0163] (b) the natural filaments are selected from the group consisting of cotton filaments, flax filaments, wool filaments, hemp filaments, bamboo filaments, and cellulose filaments, or

[0164] (c) the regenerated filaments are selected from the group consisting of viscose filaments, modal filaments, and cupro filaments.

[0165] Still even more particularly, the plastic filaments are selected from the group consisting of polyester filaments, elastane filaments, polyamide filaments, polyacrylic filaments, and polyurethane filaments. The yarn may be composed of between 2 and 500 filaments, e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,

[0166] 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,

[0167] 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,

[0168] 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 150, 200, 250, 300, 350, 400, 450, or 500 filaments.

[0169] The proportion of the silk in the yarn is preferably at least between 60% and 70%, more preferably at least between 80% and 90%, and even more preferably more than 90%, e.g. at least 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%.

[0170] Preferably, the (at least one) silk filament or multifilament used in the method of the present invention is a silk polypeptide filament or multifilament, e.g. a recombinant silk polypeptide filament or multifilament. Preferably, the silk polypeptide used in the method of the present invention is a recombinant silk polypeptide.

[0171] It is particularly preferred that the (recombinant) silk polypeptide is a polypeptide with an amino acid sequence which comprises or consists of at least 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% multiple copies of repetitive units. Said repetitive units may be identical or different.

[0172] It is further particularly preferred that the (recombinant) silk polypeptide consists of between 40 to 4000 amino acids. For example, the (recombinant) silk polypeptide consists of between 100 to 3500 amino acids, between 200 to 2500 amino acids, or between 250 to 2000 amino acids.

[0173] It is also particularly preferred that the (recombinant) silk polypeptide comprises or consists of (at least two identical) repetitive units. For example, the (recombinant) silk polypeptide may comprise between 2 to 100 repetitive units, e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,

[0174] 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

[0175] 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,

[0176] 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90,

[0177] 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 repetitive units.

[0178] Specifically, the (recombinant) silk polypeptide is a (recombinant) spider silk polypeptide, e.g. a major ampullate silk polypeptide such as a dragline silk polypeptide, a minor ampullate silk polypeptide, or a flagelliform silk polypeptide of an orb-web spider.

[0179] It is particularly more preferred that the repetitive units are independently selected from the group consisting of module C having an amino acid sequence according to SEQ ID NO: 1 or variants thereof, module CCyshaving an amino acid sequence according to SEQ ID NO: 2 or variants thereof, and module CLyshaving an amino acid sequence according to SEQ ID NO: 3 or variants thereof.

[0180] The module C variant differs from the reference module C from which it is derived by up to 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, 11, 12, 13, 14, or 15 amino acid changes in the amino acid sequence (i.e. substitutions, additions, insertions, deletions, N-terminal truncations and / or C-terminal truncations). Such a module variant can alternatively or additionally be characterized by a certain degree of sequence identity to the reference module from which it is derived. Thus, the module C variant has a sequence identity of at least 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99% or even 99.9% to the respective reference module C. Preferably, the sequence identity is over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 27, 28, 30, 34, or more amino acids, preferably over the whole length of the respective reference module C.

[0181] The sequence identity may be at least 80% over the whole length, may be at least 85% over the whole length, may be at least 90% over the whole length, may be at least 95% over the whole length, may be at least 98% over the whole length, or may be at least 99% over the whole length of the respective reference module C. Alternatively, the sequence identity may be at least 80% over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 28, or 30 amino acids, may be at least 85% over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 28, or 30 amino acids, may be at least 90% over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 28, or 30 amino acids, may be at least 95% over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 28, or 30 amino acids, may be at least 98% over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 28, or 30 amino acids, or may be at least 99% over a continuous stretch of at least 5, 10, 15, 18, 20, 24, 28, or 30 amino acids of the respective reference module C.

[0182] A fragment (or deletion) variant of module C has preferably a deletion of up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 amino acids at its N-terminus and / or at its C-terminus. The deletion can also be internally.

[0183] Additionally, the module C variant or fragment is only regarded as a module C variant or fragment within the context of the present invention, if the modifications with respect to the amino acid sequence on which the variant or fragment is based do not negatively affect the ability of the silk polypeptide to deform under pressurized air. The skilled person can readily assess whether the silk polypeptide comprising a module C variant or fragment still has this property. In this respect, it is referred to the examples comprised in the experimental part of the present patent application.

[0184] Module CCysor CLysvariants may also be encompassed by the present invention. Regarding the module CCysor CLysvariants, the same explanations / definitions apply which have been made with respect to the module C variant (see above).

[0185] It is particularly even more preferred that the silk polypeptide comprises (C)m, (C)mCCys, (C)mCLys, CCys(C)m, CLys(C)m, (CCys)m, or (CLys)m, wherein m is an integer of 2 to 96, e.g. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 29,

[0186] 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,

[0187] 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,

[0188] 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, or 96.

[0189] It is particularly most preferred that the silk polypeptide comprises C2, C4, Ce, C8, Ci6, C32, C48, (C)2CCys, (C)4CCys, (C)6CCys, (C)8CCys, (C)i6CCys, (C)32CCys, (C)48CCys, (C)2CLys, (C)4CLys, (C)6CLys, (C)8CLys, (C)i6CLys, (C)32CLys, (C)48CLys, CCys(C)2, CCys(C)4, CCys(C)6, CCys(C)8, CCys(C)i6, CCys(C)32, CCys(C)48, CLys(C)2, CLys(C)4, CLys(C)6, CLys(C)8, CLys(C)i6, CLys(C)32, CLyS(C)48, CCyS2, CCyS4, CCyS6, CCyS8, CCyS16, CCyS32, CCyS48, CLyS2, CLy% CLyS6, CLyS8, CLyS16, CLyS32, or CLys48.

[0190] The silk polypeptide C8has the amino acid sequence according to SEQ ID NO: 4 (8 times module C), the silk polypeptide Ci6 (16 times module C) has the amino acid sequence according to SEQ ID NO: 5, the silk polypeptide C32 (32 times module C) has the amino acid sequence according to SEQ ID NO: 6, and the silk polypeptide C48(48 times module C) has the amino acid sequence according to SEQ ID NO: 7.

[0191] The above-described silk polypeptide preferably consists exclusively of repetitive units. In other words, the silk polypeptide preferably does not comprise / is free of non-repetitive units.

[0192] The only component that can additionally be present as part of the silk polypeptide is a tag or moiety, e.g. allowing easy transcription of said silk polypeptide in expression systems and / or allowing easy isolation of said silk polypeptide from the expression systems. Said tag may be an his tag or a flag tag.

[0193] It should be noted that a silk multifilament which is used in the method of the present invention is composed of multiple silk filaments. These silk filaments are packed together to form a bundle. The number of filaments in the bundle usually corresponds to the number of openings in the spinning nozzle through which they were formed. For example, with a spinning nozzle having 500 holes, a silk multifilament composed of / comprising 500 silk filaments (which build a bundle) can be produced. This silk multifilament composed of multiple silk filaments is then air jet texturized or air entangled in the method of the present invention. Preferably, the silk multifilament comprises multiple continuous / infinite long silk filaments. More preferably, the multiple continuous / infinite long silk filaments have a length of between 500 and 100.000 m, e.g. a length of 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10.000, 20.000, 30.000, 40.000, 50.000, 60.000, 70.000, 80.000, 90.000, or 100.000 m. Figure 1 shows, for example, the air jet texturizing of a silk multifilament comprising 6 silk filaments using a Venturi nozzle.

[0194] Thus, in one particular embodiment, the present invention relates to a method for air jet texturizing or air entangling a silk multifilament comprising silk filaments which comprises the steps of

[0195] (i) providing a silk multifilament comprising silk filaments in a working fluid, and

[0196] (ii) passing / delivering the silk multifilament in the working fluid along / to a pressurized air nozzle, where the silk multifilament is subjected to non-laminar air flow texturing or air turbulence, thereby generating a texturized or entangled silk multifilament.

[0197] In case silk (mono) filaments (and not a silk multifilament) are air jet texturized or air entangled in the method of the present invention, preferably staple silk filaments are meant. Staple silk filaments exist as finite long pieces. More preferably staple silk filaments have a length of between 15 and 70 mm, e.g. a length of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 mm. Figure 1 shows, for example, the air jet texturizing of 8 silk staple filaments using a Venturi nozzle.

[0198] Thus, in one another particular embodiment, the present invention relates to a method for air jet texturizing or air entangling silk filaments comprising the steps of

[0199] (i) providing silk filaments in a working fluid, and

[0200] (ii) passing / delivering the silk filaments in the working fluid along / to a pressurized air nozzle, where the silk filaments are subjected to non-laminar air flow texturing or air turbulence, thereby generating texturized or entangled silk filaments.

[0201] The above silk filaments are preferably silk staple filaments.

[0202] Air-jet texturing processes are known in the art, e.g. with regard to synthetic, nonprotein derived fibers. The known air-jet texturing processes for synthetic fibers are generally applied to dry, thermoplastic and dimensionally stable filaments such as polyester or nylon, which can withstand aerodynamic forces and mechanical stress without loss of integrity. In contrast, silk filaments, and in particular spider silk filaments, are protein-based, hygroscopic, mechanically sensitive in the dry state, and combine high tensile strength with high extensibility. Because of these fundamental material differences, the skilled person would not have expected that air-jet texturing methods developed for synthetic fibres could be transferred to silk filaments without damage. In fact, the present inventors assumed that exposing delicate silk filaments to turbulent air flow would result in fibrillation, splitting or breakage, and therefore conventional processes taught away from such an approach. It was therefore highly surprising for the present inventors that subjecting wet silk filaments to turbulent flow in a working fluid, in combination with a Venturi-type nozzle, resulted in stable wave-like or crimped structures without filament damage. The controlled formation of waviness and length reduction, together with increased bulkiness and cohesion between filaments, was not anticipated and could not be predicted from the known texturing processes used for synthetic fibres. These advantageous effects arise specifically from the combination of wet processing, fluid guidance and Venturi-induced turbulence, and could not have been derived from the prior art.

[0203] In a second aspect, the present invention relates to a (at least one) texturized or entangled silk filament or multifilament obtained by the method of the first aspect.

[0204] In one particular embodiment, the present invention relates to a texturized or entangled silk multifilament comprising silk filaments obtained by the method of the first aspect.

[0205] In one another particular embodiment, the present invention relates to texturized or entangled silk filaments, e.g. silk staple filaments, obtained by the method of the first aspect.

[0206] In a third aspect, the present invention relates to a silk filament or multifilament having a texturized or entangled structure comprising a repeating wave-like or crimped portion, wherein the filament exhibits a length reduction of at least 10%, preferably at least 30%, more preferably at least 50%.

[0207] In one preferred embodiment, the wave-like or crimped portion has an amplitude between 0.5 and 5 mm and / or a frequency between I and 20 waves / cm.

[0208] The filament or multifilament is characterised by an increased bulkiness and inter-filament friction compared to a non-texturized silk filament or multifilament.

[0209] As to further preferred embodiments, it is referred to the first aspect of the present invention.

[0210] In a fourth aspect, the present invention relates to a yarn comprising the (at least one) texturized or entangled silk filament or multifilament of the second or third aspect.

[0211] In one particular embodiment, the present invention relates to a yarn comprising the texturized or entangled silk multifilament comprising silk filaments of the second or third aspect.

[0212] In one another particular embodiment, the present invention relates to a yam comprising texturized or entangled silk filaments of the second or third aspect. In one preferred embodiment, the yarn is composed of between 2 and 500 filaments, e.g. 2, 3,

[0213] 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,

[0214] 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,

[0215] 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80,

[0216] 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 150, 200, 250, 300, 350, 400, 450, or 500 filaments.

[0217] In one another preferred embodiment, the yam further comprises one or more filaments of a different material. The one or more filaments of the different material are particularly synthetic filaments, natural filaments or regenerated filaments.

[0218] Specifically,

[0219] (a) the synthetic filaments are selected from the group consisting of plastic filaments, recombinant polypeptide filaments, PET filaments, PA filaments, PP filaments, and EA filaments,

[0220] (b) the natural filaments are selected from the group consisting of cotton filaments, flax filaments, wool filaments, hemp filaments, bamboo filaments, and cellulose filaments, or

[0221] (c) the regenerated filaments are selected from the group consisting of viscose filaments, modal filaments, and cupro filaments.

[0222] More specifically,

[0223] (ai) the plastic filaments are selected from the group consisting of polyester filaments, elastane filaments, polyamide filaments, polyacrylic filaments, and polyurethane filaments.

[0224] In this case, the proportion of the silk in the yam is preferably at least between 60% and 70%, more preferably at least between 80% and 90%, and even more preferably more than 90%, e.g. at least 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%.

[0225] In a fifth aspect, the present invention relates to an article comprising the (at least one) texturized or entangled silk filament or multifilament of the second or third aspect or the yarn of the fourth aspect.

[0226] In one particular embodiment, the present invention relates to an article comprising the texturized or entangled silk multifilament comprising silk filaments of the second or third aspect or the yarn of the fourth aspect.

[0227] In one another particular embodiment, the present invention relates to an article comprising the texturized or entangled silk filaments of the second or third aspect or the yam of the fourth aspect. In one preferred embodiment, the article is a textile / fabric. Thus, the article may be a textile / fabric comprising the (at least one) texturized or entangled silk filament or multifilament. The textile / fabric may be a knitted textile / fabric, a woven textile / fabric, or non-woven textile / fabric. In one more preferred embodiment, the textile / fabric is / part of a garment, an apparel, or footwear, e.g. a shoe. The garment may be a fashion, a sport, an outdoor, a medical, or an orthopaedic garment. Particularly, the garment may be fashion articles, fashion goods, shirts, socks, stockings, e.g. compression stockings, medical stockings, or support stockings, tights, e.g. support tights, pants, e.g. sport or outdoor pants, underwear, e.g. sport or outdoor underwear, gloves, caps, storm hoods, footwear or bandages. In one alternative more preferred embodiment, the textile / fabric is a technical textile, smart textile, industrial fabric, or a high- performance material.

[0228] Specifically, the (at least one) textured or entangled silk filament or multifilament comprises waves, crimps, and / or undulations. Such changes in the physical form of the (at least one) silk filament or multifilament affect the behaviour and hand of fabrics made from them. For example, the modifications introduced by texturizing improve the drape, appearance, luster, warmth, elasticity, and / or handle of textiles comprising the (at least one) silk filament or multifilament, e.g. finished fabrics.

[0229] In a sixth aspect, the present invention relates to the use of the (at least one) texturized or entangled silk filament or multifilament of the second or third aspect or the yam of the fourth aspect in the textile industry.

[0230] In one particular embodiment, the present invention relates to the use of the texturized or entangled silk multifilament comprising silk filaments of the second or third aspect or the yarn of the fourth aspect in the textile industry.

[0231] In one another particular embodiment, the present invention relates to the use of texturized or entangled silk filaments of the second or third aspect or the yam of the fourth aspect in the textile industry.

[0232] In one preferred embodiment, the silk filament or multifilament or the yarn is used in apparel, footwear, technical textiles, smart textiles, industrial fabrics, or performance materials.

[0233] In a seventh aspect, the present invention relates to the use of the (at least one) texturized or entangled silk filament or multifilament of the second or third aspect or the yam of the fourth aspect in the manufacture of a textile.

[0234] In one particular embodiment, the present invention relates to the use of the texturized or entangled silk multifilament comprising silk filaments of the second or third aspect or the yarn of the fourth aspect in the manufacture of a textile. In one another particular embodiment, the present invention relates to the use of texturized or entangled silk filaments of the second or third aspect or the yam of the fourth aspect in the manufacture of a textile / fabric.

[0235] In one preferred embodiment, the textile / fabric is / part of an apparel or a shoe.

[0236] In one alternative preferred embodiment, the textile / fabric is a technical textile, smart textile, industrial fabric, or a high-performance material.

[0237] In a further aspect, the present invention relates to a Venturi-type pressurized air nozzle for texturizing a silk filament or multifilament, the nozzle comprising:

[0238] (i) an inlet opening configured to receive a working fluid containing at least one silk filament or multifilament,

[0239] (ii) a constricted throat section having a flow channel dimensioned to guide the silk filament or multifilament in the working fluid while reducing the cross-sectional area and generating an increased flow velocity and a reduced static pressure, and

[0240] (iii) a diffuser section downstream of the throat with a gradually increasing cross-sectional area, wherein the flow channel geometry is adapted to stabilise the wet silk filament or multifilament against excessive mechanical stress, while enabling the generation of non-laminar, turbulent flow for forming wave-like or crimped structures along the silk filament or multifilament.

[0241] Various modifications and variations of the invention will be apparent to those skilled in the art without departing from the scope of invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art in the relevant fields are intended to be covered by the present invention.

[0242] BRIEF DESCRIPTION OF THE FIGURES

[0243] The following figures and examples are merely illustrative of the present invention and should not be construed to limit the scope of the invention as indicated by the appended claims in any way.

[0244] Figure 1: Shows a schema of air jet texturizing or air entangling of silk filaments (staple silk filaments) and a silk multifilament comprising silk filaments using a Venturi nozzle. Figure 2: Shows an exemplary Venturi nozzle. The Venturi nozzle comprises (i) an inlet opening configured to receive the working fluid (motive fluid) into a flow channel, (ii) a constricted section (diffuser throat) that reduces the cross-sectional area of the flow channel to increase the working fluids (motive fluid) velocity and decrease its static pressure, and (iii) a downstream diffuser section (diverging outlet diffuser) with a gradually increasing cross- sectional area to reduce the velocity and restore the fluid pressure, wherein the geometry of the nozzle is designed to optimize flow conditions within the nozzle by generating a vacuum in the constricted section.

[0245] Figure 3: Shows a delivery device used in the present invention. The silk filaments or the silk multifilament is / are passed along / delivered to the pressurized air nozzle (e.g. Venturi nozzle) via the delivering device.

[0246] Figure 4: Shows different texturized multimer silk fibers and controls.

[0247] (A) Shows a first example of a texturized multifilament comprising 40 silk filaments produced by air jet texturizing via a Venturi nozzle. The multifilament has a titer of about 100 dTex. The texturization has a frequency of around 2,5 crimps / cm and an amplitude of around 1,8mm.

[0248] (B) Shows a second example of a texturized multifilament comprising 40 silk filaments produced by air jet texturizing via a Venturi nozzle. The multifilament has a titer of about 90dTex. The texturization has a frequency of around 3,5 crimps / cm and an amplitude of around 1,3mm.

[0249] (C) Shows a second example of a texturized multifilament comprising 40 silk filaments produced by air jet texturizing via a Venturi nozzle. The multifilament has a titer of about 90Tex. The texturization has a frequency of around 1,8 crimps / cm and an amplitude of around 0,5mm.

[0250] (D) Shows a multifilament comprising of 67 filaments produced from PET (Polyethylenterephthalat) known as Polyester. The multifilament has a titer of about 75 dTex. The texturization was done by a thermoplastic process. The crimp is achieved by feeding the filaments between hot and wavy surfaces. The frequency of around 3 crimps / cm and an amplitude of around 0,3mm

[0251] (E) Shows shows a multifilament comprising of 40 silk filaments produced with recombinant silk and texturized by air jet texturizing via a Venturi nozzle. The multifilament has a titer of about 100 dTex and is not texturized / crimped at all. No frequency or amplitude can be measured. EXAMPLES

[0252] The examples given below are for illustrative purposes only and do not limit the invention described above in any way.

[0253] EXAMPLE 1 :

[0254] 1, Spider silk protein preparation:

[0255] Recombinant spider silk proteins (e.g. C32, C48, C48CCys) were prepared as described in WO 2006 / 008163.

[0256] 2, Spider silk protein spinning dope preparation:

[0257] 500 mg of the recombinant spider silk proteins (e.g. C32, C48, C48CCys) were dissolved in 10 mL of 6 M GdmSCN (5% (w / v)). After recombinant spider silk protein dissolution, insoluble parts were removed by centrifuging (8500 rpm, 30 min, 18°C). The supernatant was dialyzed (MWCO: 6-8 kDa) each time for 4 hours with the following buffers:

[0258] 1) Buffer 1 : 50 mM NH4HCO3 (pH 7.8), 500 mM urea, 500 mM GdmSCN,

[0259] 2) Buffer 2: 50 mM NH4HCO3 (pH 7.8), 500 mM urea, 250 mM GdmSCN, and

[0260] 3) Buffer 3 : 50 mM NH4HCO3 (pH 7.8), 500 mM urea.

[0261] Subsequently, the recombinant spider silk protein was dialyzed against 20 % (w / v) PEG (35 kDa), 500 mM urea until a concentration of 15% was reached. The spinning dope was then used for spinning.

[0262] 3, Spider silk protein multi filament production:

[0263] For wet spinning, the spinning dope comprising the spider silk protein was transferred into a spinneret with a spinning nozzle. The spinning nozzle had 40spinning holes. The spinning nozzle submerged into a coagulation bath. As coagulation bath, ethanol, butanol, methanol, propanol, polyethylene glycol, or isopropanol was used. The spinning dope was extruded into the coagulation bath. The coagulated silk multifilament comprising 40 silk filaments was taken out of the coagulation bath and used for texturizing (in a wet state).

[0264] 4, Spider silk protein multi filament texturizing using a Venturi nozzle: For air jet texturizing using a Venturi nozzle, the silk multi filament composed of 40 silk filaments was passed / delivered in an air or water stream to the Venturi nozzle. The Venturi nozzle generated a non-laminar air flow / air turbulences with an amplitude of between 0.5 and 5 mm and a frequency of between 1 and 20 waves / cm. The Venturi nozzle generated a non- laminar air flow / air turbulences deforming the linear form of the silk multifilament and transforming it into a wave shape and crimped structure.

[0265] 5, Spider silk protein filament texturizing using a Venturi nozzle:

[0266] The most widely used polyester fiber is made from the linear polymer poly (ethylene terephtalate), and this polyester class is generally referred to simply as PET. Features are high strength, high modulus, low shrinkage, heat set stability. The heat set stability is utilised to crimp / texturize the PET fibers.

[0267] The same experiment was performed with silk staple filaments having a discrete length of between 15 and 70 mm. The Venturi nozzle generated air turbulences deforming the linear form of the silk filaments and transforming them into a wave shape and crimped structure. As comparative example, a PET texturized fiber was used. In addition, a non-texturized multifilament comprising 40 silk filaments was used. The results are shown in Figure 4.

[0268] There are several alternative ways to crimp texturize thermoplastic based fibers. During the time the fibers are exposed to a temperature close to the glass point the thermoplastic fiber can be deformed. E.G. feeding them between wave surfaces and afterwards cooling them down.

Claims

CLAIMS1. A method for air jet texturizing or air entangling a silk filament or multifilament comprising the silk filament comprising the steps of:(i) providing a silk filament or multifilament comprising the silk filament in a working fluid, and(ii) passing / delivering the silk filament or multifilament in the working fluid along / to a pressurized air nozzle, where the silk filament or multifilament is subjected to non-laminar air flow texturing or air turbulence, thereby generating a texturized or entangled silk filament or multifilament.

2. The method of claim 1, wherein the pressurized air nozzle causes air turbulences deforming the linear form of the silk filament or multifilament and transforming it into a wave shape or crimped structure.

3. The method of claims 1 or 2, wherein the subjection of the silk filament or multifilament to the non-laminar air flow leads to a length reduction / shrinkage of the silk filament or multifilament of at least 10%, preferably of at least 30%, and more preferably of at least 50%.

4. The method of any one of claims 1 to 3, wherein the pressurized air nozzle generated turbulences with an amplitude of between 0.5 and 5 mm and / or a frequency of between 1 and 20 waves / cm.

5. The method of any one of claims 1 to 4, wherein the silk filament or multifilament which is passed along the air texturizing nozzle is in a wet state / not dried.

6. The method of any one of claims 1 to 5, wherein the silk filament or multifilament is passed along / delivered to the pressurized air nozzle via a delivering device.

7. The method of claim 6, wherein the delivery device is a tube through which the working fluid flows to guide / transport the silk filament or multifilament.

8. The method of any one of claims 1 to 7, wherein the pressurized air nozzle is a Venturi nozzle.

9. The method of claim 8, wherein the Venturi nozzle comprises(i) an inlet opening configured to receive the working fluid into a flow channel,(ii) a constricted section (throat) that reduces the cross-sectional area of the flow channel to increase the working fluids velocity and decrease its static pressure, and(iii) a downstream diffuser section with a gradually increasing cross-sectional area to reduce the velocity and restore the fluid pressure, wherein the geometry of the nozzle is designed to optimize flow conditions within the nozzle by generating a vacuum in the constricted section.

10. The method of claims 8 or 9, wherein the method comprises the steps of:(i) introducing the silk filament or multifilament in the working fluid via an / the inlet opening into a / the flow channel of the Venturi nozzle,(ii) accelerating the silk filament or multifilament in the working fluid through a / the constricted section (throat) of the nozzle, thereby increasing the fluid velocity and decreasing the static pressure,(iii) subjecting the silk filament or multifilament to differential drag forces and air turbulences in the constricted section (throat), resulting in the formation of a wave-like or crimped silk filament or multifilament,(iv) optionally applying heat to the silk filament or multifilament during the process to soften the silk filament or multifilament and enable permanent waves or crimps, and(v) allowing the waved or crimped silk filament or multifilament to exit the nozzle through a diffuser section, where the working fluid velocity decreases and the pressure stabilizes, thereby retaining the waved or crimped structure in the silk filament or multifilament.

11. The method of any one of claims 1 to 10, wherein the filament or multifilament is a continuous / infinite long filament or multifilament.

12. The method of claim 11, wherein the continuous filament or multifilament has a length of between 500 and 100.000 meters.

13. The method of any one of claims 1 to 12, wherein the filament or multifilament is a finite long filament or multifilament.

14. The method of claim 13, wherein the finite long filament or multifilament is a staple filament or multifilament.

15. The method of claim 14, wherein the staple filament or multifilament has a length of between 15 and 70 mm.

16. The method of any one of claim 1 to 15, wherein the silk filament or multifilament comprising the silk filament provided in step (i) is formed by extruding a solution comprising a silk polypeptide through a spinneret nozzle having one or more spinning holes.

17. The method of claim 16, wherein the solution comprising the silk polypeptide comprises an organic or inorganic solvent.

18. The method of claims 16 or 17, wherein the concentration of the silk polypeptide in the solution is between 5% and 50%, preferably between 5% and 40%, and more preferably between 10% and 30%.

19. The method of any one of claims 16 to 18, wherein the spinneret nozzle has between 1 and 500 spinning holes.

20. The method of claim 19, wherein the spinning holes have a diameter of between 10 pm and 500 pm.

21. The method of any one of claims 16 to 20, wherein the solution comprising the silk polypeptide is extruded into a coagulation bath.

22. The method of claim 21, wherein the coagulation bath comprises alcohol, preferably ethanol, butanol, methanol, propanol, polyethylene glycol, or isopropanol.

23. The method of any one of claims 16 to 22, wherein the silk filament upon extrusion has a diameter in the range of between 5 pm and 200 pm or wherein the silk multifilament has a diameter in the range of between 20 pm pm and 1000 pm.

24. The method of any one of claims 16 to 23, wherein the extruded silk filament or multifilament is subsequently extended in a stretching / drawing step.

25. The method of claim 24, wherein the stretching / drawing step is carried out in a stretching / drawing bath.

26. The method of claim 25, wherein the stretching / drawing bath comprises alcohol, ethanol, butanol, methanol, propanol, polyethylene glycol, or isopropanol.

27. The method of any one of claims 24 to 26, wherein the extended silk filament has a diameter in the range of between 2.5 pm and 100 pm or the silk multifilament has a diameter in the range of between 20 pm and 500 pm.

28. The method of any one of claims 1 to 27, wherein the method further comprises step (iii) of spinning the multifilament into a yam, or spinning the silk filament together with one or more filaments of a different material into a yarn.

29. The method of claim 28, wherein the multifilament is spun into a yam together with one or more filaments of a different material.

30. The method of claims 28 or 29, wherein the yam is a continuous / infinite long yarn composed of multifilaments or a finite long staple yarn composed of staple filaments.

31. The method of any one of claims 28 to 30, wherein the one or more filaments of the different material are synthetic filaments, natural filaments or regenerated filaments.

32. The method of claim 31, wherein(a) the synthetic filaments are selected from the group consisting of plastic filaments, recombinant polypeptide filaments, PET filaments, PA filaments, PP filaments, and EA filaments,(b) the natural filaments are selected from the group consisting of cotton filaments, flax filaments, wool filaments, hemp filaments, bamboo filaments, and cellulose filaments, or(c) the regenerated filaments are selected from the group consisting of viscose filaments, modal filaments, and cupro filaments.

33. The method of claim 32, wherein(ai) the plastic filaments are selected from the group consisting of polyester filaments, elastane filaments, polyamide filaments, polyacrylic filaments, and polyurethane filaments.

34. The method of any one of claims 28 to 33, wherein the yam is composed of between 2 and 500 filaments.

35. The method of any one of claims 28 to 34, wherein the proportion of the silk in the yam is at least between 60% and 70%, preferably at least between 80% and 90%, and more preferably more than 90%.

36. The method of any one of claims 1 to 35, wherein the silk is spider silk, preferably recombinant spider silk.

37. The method of any one of claims 16 to 36, wherein the silk polypeptide is a spider silk polypeptide, preferably a recombinant spider silk polypeptide.

38. A texturized or entangled silk filament or multifilament obtainable / obtained by the method of any one of claims 1 to 37.

39. A silk filament or multifilament having a texturized or entangled structure comprising a repeating wave-like or crimped portion, wherein the filament exhibits a length reduction of at least 10%, preferably at least 30%, more preferably at least 50%.

40. The silk filament or multifilament of claim 39, wherein the wave-like or crimped portion has an amplitude between 0.5 and 5 mm and / or a frequency between 1 and 20 waves / cm.

41. The silk filament or multifilament of claims 39 or 40, wherein the filament or multifilament is characterised by an increased bulkiness and inter-filament friction compared to a non-texturized silk filament or multifilament.

42. A yam comprising the texturized or entangled silk filament or multifilament of any one of claims 38 to 41.

43. The yarn of claim 42, wherein the yam is composed of between 2 and 500 filaments.

44. The yarn of claims 42 or 43, wherein the yarn further comprises one or more filaments of a different material.

45. The yarn of claim 44, wherein the one or more filaments of the different material are synthetic filaments, natural filaments or regenerated filaments.

46. An article comprising the texturized or entangled silk filament or multifilament of any one of claims 38 to 41 or the yarn of any one of claims 42 to 45.

47. The article of claim 46, wherein the article is a textile48. The article of claim 47, wherein the textile is / part of an apparel or a shoe.

49. The article of claim 47, wherein the textile is a technical textile, smart textile, industrial fabric, or a high-performance material.

50. Use of the texturized or entangled silk filament or multifilament of any one of claims 38 to 41 or the yarn of any one of claims 42 to 45 in the textile industry.

51. The use of claim 50, wherein the silk filament or multifilament or the yarn is used in apparel, footwear, technical textiles, smart textiles, industrial fabrics, or performance materials.

52. Use of the texturized or entangled silk filament or multifilament of any one of claims 38 to 41 or the yarn of any one of claims 42 to 45 in the manufacture of a textile.

53. The use of claim 52, wherein the textile is / part of an apparel or a shoe.

54. The use of claim 52, wherein the textile is a technical textile, smart textile, industrial fabric, or a high-performance material.

55. A Venturi-type pressurized air nozzle for texturizing a silk filament or multifilament, the nozzle comprising:(i) an inlet opening configured to receive a working fluid containing at least one silk filament or multifilament,(ii) a constricted throat section having a flow channel dimensioned to guide the silk filament or multifilament in the working fluid while reducing the cross-sectional area and generating an increased flow velocity and a reduced static pressure, and(iii) a diffuser section downstream of the throat with a gradually increasing cross- sectional area, wherein the flow channel geometry is adapted to stabilise the wet silk filament or multifilament against excessive mechanical stress, while enabling the generation of non- laminar, turbulent flow for forming wave-like or crimped structures along the silk filament or multifilament.

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