Method for texturizing silk fibers

Abstract

The present invention relates to a method for texturizing a yarn or yarn bundle comprising shrinkable silk polypeptide fibre. Further, the present invention relates to a texturized yarn or yarn bundle obtained by the method. Furthermore, the present invention relates to the use of the texturized yarn or yarn bundle in the textile industry.

Description

[0001] AMSilk GmbH

[0002] Our Ref.: 558-117 PCT

[0003] METHOD FOR TEXTURIZING SILK FIBERS

[0004] The present invention relates to a method for texturizing a yarn or yarn bundle. Further, the present invention relates to a texturized yam or yam bundle obtained by the method. Furthermore, the present invention relates to an article comprising the texturized yam or yarn bundle. In addition, the present invention relates to the use of the texturized yam or yam bundle in the textile industry.

[0005] BACKGROUND OF THE INVENTION

[0006] It has long been known that certain fibers produced in nature possess remarkable mechanical properties in terms of strength, resilience and flexibility. These protein based fibers, 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 fibers 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 fibers, such as wool and cotton, are not present in these silk fibers. As an instance, the fibers 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 fibers 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 fibers 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 fibers 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 fibers to assume their original crimp configuration.

[0009] Thus, there is a need for a new method that enables the generation of silk yarns or silk yarn bundles with improved properties, such as improved haptic, optic, elasticity and / or thermal properties. Such a method would increase the industrial applicability of silk fibers manufactured therefrom. The present inventors developed a new method for texturizing a yarn or yam bundle comprising silk fibers. In this method, at least one first shrinkable silk polypeptide fiber or yarn comprising the at least one first fiber is twisted with at least one second fiber or yarn comprising the at least one second fiber. The resulting yam or yarn bundle is subsequently shrunk in order to texturize the yarn or yam bundle. It is, thereby, preferred that the first fiber and the second fiber differ in their shrinkage ability, whereby it is more preferred that the first fiber has a higher ability to shrink than the second fiber. In which the first fiber shrinks and the second fiber does not or less in comparison, the second fiber is bulked / puffed up. This texturizing process results in the formation of crimps, loops, coils, and / or crinkles. Such changes in the physical form of a fiber affect the behaviour and hand of fabrics made therefrom. Said method, therefore, allows the production of yams or yam bundles comprising silk fibers having improved properties with regard to haptic, optic, elasticity and / or thermal properties.

[0010] SUMMARY OF THE INVENTION

[0011] In a first aspect, the present invention relates to a method for texturizing a yam or yarn bundle comprising the steps of:

[0012] (i) providing at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first fiber,

[0013] (ii) twisting the at least one first fiber or yarn provided in (i) with at least one second fiber or yarn comprising the at least one second fiber, thereby obtaining a yam or yarn bundle, and

[0014] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle.

[0015] In a second aspect, the present invention relates to a texturized (and shrunk) yam or yam bundle obtained / obtainable by the method according to the first aspect.

[0016] In a third aspect, the present invention relates to a texturized (and shrunk) yam or yarn bundle comprising at least one first shrunk silk polypeptide fiber or yam comprising the fiber and at least one second fiber or yarn comprising the fiber, wherein the at least one second fiber or yam comprising the fiber is twisted around the at least one first shrunk silk polypeptide fiber or yarn comprising the fiber.

[0017] In a fourth aspect, the present invention relates to an article comprising the texturized (and shrunk) yam or yarn bundle according to the second or third aspect.

[0018] In a fifth aspect, the present invention relates to the use of the texturized (and shrunk) yarn or yam bundle according to the second or third aspect in the textile industry. In a sixth aspect, the present invention relates to the use of the texturized (and shrunk) yarn or yam bundle according to the second or third aspect for the manufacture of a textile, preferably an apparel or a shoe.

[0019] 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.

[0020] DETAILED DESCRIPTION OF THE INVENTION

[0021] Definitions

[0022] 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.

[0023] Preferably, the terms used herein are defined as described in “A multilingual glossary of biotechnological terms: (IUPAC Recommendations)”, Leuenberger, H.G.W, Nagel, B. and Kolbl, H. eds. (1995), Helvetica Chimica Acta, CH-4010 Basel, Switzerland).

[0024] 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.

[0025] 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 term “fiber”, as used herein, refers to a material that is significantly longer than it is wide. The fiber can be present as continuous strand, staple fiber, or in a discrete elongated piece. The term “fiber”, as used herein, further encompasses single-drawn and multi-drawn (e.g. double-drawn) fibers. Said fibers have been stretched one or more times during their preparation process, in particular wet-spinning process. An exemplarily process for producing fibers which may be used in the present invention is described in WO 2014 / 037453. The fiber can be a natural or synthetic (e.g. recombinant) fiber.

[0029] It is preferred that the fiber has a linear density of between 0.5 and 700 Decitex (dtex). It is more preferred that the fiber has a linear density of between 0.5 and 300 dtex. It is even more preferred that the fiber has a linear density of between 0.5 and 10 dtex. For example, the fiber has a linear density of 0.5, 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, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, or 700 dtex.

[0030] It is (alternatively or additionally) preferred that the fiber has a thickness (diameter) of between 0,5 pm and 300 pm. It is more preferred that the fiber has a thickness (diameter) of between 1 pm and 200 pm. For example, the fiber has a thickness of 0,5, 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, 60, 70, 80, 90, 100, 150, 200, 250, or 300 pm.

[0031] The terms “fiber” and filament” are used interchangeably in the context of the present invention.

[0032] The term “staple fiber”, as used herein, refers a fiber of discrete length. The opposite is a filament fiber, which comes in continuous lengths. Staple length is a characteristic fiber length of a sample of staple fibers. It is an essential criterion in yam spinning, and aids in cohesion and twisting. Preferably, the staple fiber has a length of between 10 and 100 mm and more preferably a length of between 20 and 70 mm, e.g. a length of 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, 60, 70, 80, 90, or 100 mm. The term “yarn”, as used herein, refers to a strand composed of fibers, either natural or synthetic. The term “yam”, as used herein, also refers to a long continuous length of interlocked fibers, twisted fibers, or fibers grouped together (but not interlocked or twisted). The yarn can be used in sewing, crocheting, knitting, weaving, embroidery, rope making, and the production of textiles.

[0033] The yarn is composed of 2 or more fibers (monofilaments). Thus, a yam is a multifilament which is composed of a number of monofilaments. These fibers are twisted, interlocked, or grouped together.

[0034] For example, a yarn is a multifilament which is composed of between 2 and 10000 (mono)filaments, preferably between 2 and 1000 (mono)filaments, and more preferably between 2 and 500 (mono) 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 (mono)filaments.

[0035] It is preferred that the yarn has a linear density of between 2 and 800 Decitex (dtex). It is more preferred that the yam has a linear density of between 30 and 500 dtex. It is even more preferred that the yam has a linear density of between 50 and 300 dtex. For example, the yam has a linear density of 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, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, or 800 dtex.

[0036] It is (alternatively or additionally) preferred that the yarn has a thickness (diameter) of between 1 pm and 400 pm. It is more preferred that the yam has a thickness (diameter) of between 10 pm and 300 pm. For example, the yarn has a thickness of 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, 60, 70, 80, 90, 100, 150, 200, 250, 300, or 400 pm.

[0037] 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 fibers 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.

[0038] The term “yarn bundle”, as used herein, refers to a strand composed of yams, either natural or synthetic. The term “yam bundle”, as used herein, also refers to a long continuous length of interlocked yams, twisted yams, or yams grouped together (but not interlocked or twisted). The yam bundle can be used in sewing, crocheting, knitting, weaving, embroidery, rope making, and the production of textiles.

[0039] The yarn bundle is composed of 2 or more yams. These yarns are twisted, interlocked, or grouped together.

[0040] For example, a yarn bundle is a complex composed of between 2 and 100 yarns, preferably between 2 and 50 yarns, 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, or 50 yams. The yarn bundle can also be designated as cord.

[0041] The present invention relates to the (further) processing / finishing of fibers or yams 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 yarn manipulations, finishing techniques, and fabric structures. In this respect, the term “texturizing”, as used herein, refers to a process by which fibers (e.g. synthetic fibers) are modified to change their texture - the physical appearance of the fibers Texturizing takes advantage of the plastic deformation capacity of fibers (e.g. synthetic fibers), and uses it to set texturized features in place.

[0042] For example, fibers 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).

[0043] Specifically, texturizing is the formation of crimps, loops, coils, and / or crinkles in fibers. Such changes in the physical form of the fibers 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 fibers, e.g. finished fabrics.

[0044] 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 yam, yam bundle, or fabric is held in the hand, such as drapability, softness, elasticity, coolness or warmth, stiffness, roughness, and resilience.

[0045] The term “shrinkable fiber”, as used herein, refers to a fiber the length of which is shrinkable / reducible after contact with a chemical, e.g. water. The fiber may be exposed to the chemical, e.g. water (like hot water), by incubating the fiber in the chemical, e.g. water (like hot water), or by exposing the fiber to vapor or steam of the chemical, e.g. water.

[0046] Preferably, the length of the fiber is shrinked / reduced by at least 10%, more preferably by at least 20%, and even more preferably by at least 30%, with regard to its total length after contact with the chemical, e.g. water. For example, the length of the fiber is shrinked / reduced by 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% with regard to its total length.

[0047] 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.

[0048] 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 fiber. 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.

[0049] The term “first shrinkable silk polypeptide fiber”, as used herein, refers to a silk polypeptide material that is significantly longer than it is wide. The silk polypeptide fiber can be present as continuous strand, staple fiber, or in a discrete elongated piece. The term “first shrinkable silk polypeptide fiber”, as used herein, also refers to a silk polypeptide fiber the length of which is shrinkable / reducible after contact with a chemical, e.g. water. The silk polypeptide fiber may be exposed to the chemical, e.g. water, by incubating the fiber in the chemical, e.g. water (like hot water), or by exposing the fiber to vapor or steam of the chemical, e.g. water.

[0050] It is preferred that the length of the silk polypeptide fiber can shrink by at least 10% with regard to its total length after contact with a chemical, e.g. water. It is more preferred that the length of the silk polypeptide fiber can shrink by at least 20% with regard to its total length after contact with a chemical, e.g. water. It is even more preferred that the length of the silk polypeptide fiber can shrink by at least 30% with regard to its total length after contact with a chemical, e.g. water. For example, the length of the silk polypeptide fiber can shrink by 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% with regard to its total length. The fiber may be a fiber as produced in WO 2014 / 037453.

[0051] It is further (alternatively or additionally) preferred that the silk polypeptide fiber has a linear density of between 0.5 and 700 Decitex (dtex). It is more preferred that the silk polypeptide fiber has a linear density of between 0.5 and 300 dtex. It is even more preferred that the silk polypeptide fiber has a linear density of between 0.5 and 10 dtex. For example, the silk polypeptide fiber has a linear density of 0.5, 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, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, or 700 dtex.

[0052] It is also (alternatively or additionally) preferred that the silk polypeptide fiber has a thickness (diameter) of between 0,5 pm and 300 pm. It is more preferred that the silk polypeptide fiber has a thickness (diameter) of between 1 pm and 200 pm. For example, the fiber has a thickness of 0,5, 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, 60, 70, 80, 90, 100, 150, 200, 250, or 300 pm.

[0053] It is more preferred that the first shrinkable silk polypeptide fiber is a stretched / extended fiber, e.g. a single-drawn and multi-drawn (e.g. double-drawn) fiber. It is even more preferred that the first shrinkable silk polypeptide fiber is a full drawn fiber, i.e. a fiber that is (almost) completely stretched / extended (until shortly before the fiber was pulled off) after its production. This fiber may also be designated as flex fiber herein.

[0054] 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 fiber and, thereby, improves the properties of the fiber. It is preferred that the fiber is extended after it has been drawn or extruded. Such extension can be carried out in a continuous or discontinuous process. In the continuous process it is preferred that the fiber is exposed to a pulling force. Preferably, the extension of the fiber is by at least 2-fold in comparison to the length of the fiber as drawn or 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.

[0055] During extension the cross-sectional area of the fiber 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%. For example, such extension is carried out in the presence of a coagulation solution. In this case, the fiber - 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 fiber is - after incubation in the coagulation solution - transferred into one or more washing solutions. To achieve the extension, the fiber is pulled out of the coagulation solution and / or the one or more washing solutions. The coagulation solution may be selected from the group consisting of ethanol, butanol, methanol, propanol, polyethylene glycol, and isopropanol. 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 fiber is drawn or extruded from the nozzle of the spinneret with a speed of 10 cm / s and the fiber 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 fiber in a predetermined way. For example, a roller may be positioned behind the nozzle that draws out the fiber 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 fiber as drawn or extruded and the product at the end of the stretching (and possible relaxing) process.

[0056] Specifically, the first shrinkable silk polypeptide fiber is a spider silk polypeptide fiber, e.g. a recombinant spider silk polypeptide fiber.

[0057] Especially, the first shrinkable silk polypeptide fiber has no thermoplastic properties but hydroplastic properties which are used in the method of the present invention, namely by exposing the first shrinkable silk polypeptide fiber to a chemical such as water or water vapor to induce shrinkage in order to texturize the yam or yam bundle comprising the first silk polypeptide fiber.

[0058] The term “yam comprising the first shrinkable silk polypeptide fiber”, as used herein, refers to a yarn comprising the shrinkable silk polypeptide fibers as described above. It is composed of 2 or more first shrinkable silk polypeptide fibers. These fibers are twisted, interlocked, or grouped together.

[0059] For example, a yarn comprising the first shrinkable silk polypeptide fiber is composed of between 2 and 10000 first shrinkable silk polypeptide fibers, preferably between 2 and 1000 first shrinkable silk polypeptide fibers, and more preferably between 2 and 500 first shrinkable silk polypeptide fibers, 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 first shrinkable silk polypeptide fibers.

[0060] It is preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a linear density of between 2 and 800 Decitex (dtex). It is more preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a linear density of between 30 and 500 dtex. It is even more preferred that the yam comprising the first shrinkable silk polypeptide fiber has a linear density of between 50 and 300 dtex. For example, the yarn comprising the first shrinkable silk polypeptide fiber has a linear density of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,

[0061] 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,

[0062] 44, 45, 46, 47, 48, 49, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, or 800 dtex.

[0063] It is (alternatively or additionally) preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a thickness (diameter) of between 1 pm and 400 pm. It is more preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a thickness (diameter) of between 10 pm and 300 pm. For example, the yarn comprising the first shrinkable silk polypeptide fiber has a thickness of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,

[0064] 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,

[0065] 45, 46, 47, 48, 49, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, or 400 pm.

[0066] The term “second fiber”, as used herein, refers to a material that is significantly longer than it is wide. The fiber can be present as continuous strand, staple fiber, or in a discrete elongated piece.

[0067] In contrast to the first silk polypeptide fiber, it is preferred that the second fiber is not extended / stretched or only minimally extended / stretched (e.g. less than 1-fold). Thus, the second fiber is preferably relaxed / in a relaxed state. This fiber may also be designated as prime fiber herein.

[0068] It is preferred that the second fiber is a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber.

[0069] The second fiber may be a synthetic fiber, a natural fiber, or a regenerated fiber, e.g. a shrunk, shrinkable, non-shrinkable synthetic fiber, a shrunk, shrinkable, non-shrinkable natural fiber, or a shrunk, shrinkable, non-shrinkable regenerated fiber.

[0070] Preferably, the synthetic fiber is selected from the group consisting of a plastic fiber, a recombinant polypeptide fiber, a PET fiber, a PA fiber, a PP fiber, and an EA fiber, the natural fiber is selected from the group consisting of a cotton fiber, a flax fiber, a wool fiber, a hemp fiber, a bamboo fiber, a cellulose fiber, and a silk fiber, or the regenerated fiber is selected from the group consisting of a viscose fiber, a modal fiber, and a cupro fiber.

[0071] More preferably, the plastic fiber is selected from the group consisting a polyester fiber, an elastane fiber, a polyamide fiber, a polyacrylic fiber, and a polyurethane fiber, or the recombinant polypeptide fiber is a silk polypeptide fiber.

[0072] Even more preferably, the recombinant silk polypeptide fiber is a recombinant spider silk polypeptide fiber.

[0073] As to the linear density and / or thickness of the second fiber, it is referred to the first fiber.

[0074] The term “yarn comprising the second fiber”, as used herein, refers to a yam comprising the second fiber as described above. It is composed of 2 or more second fibers. These fibers are twisted, interlocked, or grouped together.

[0075] For example, a yam comprising the second fiber is composed of between 2 and 10000 second fibers, preferably between 2 and 1000 second fibers, and more preferably between 10 and 100 second fibers, 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 second fibers.

[0076] As to the linear density and / or thickness of the yarn comprising the second fiber, it is referred to the yarn comprising the first fiber.

[0077] It is preferred that the “first silk polypeptide fiber” and the “second fiber” are characterized by a different shrinkage ratio. In other words, it is preferred that the “first silk polypeptide fiber” and the “second fiber” differ from each other in their ability to shrink. It is more preferred that the “first silk polypeptide fiber” has a higher ability to shrink than the “second fiber”.

[0078] As mentioned above, the second fiber can be a shrunk fiber, a shrinkable fiber, or a non- shrinkable fiber. Thus, in one example, the first silk polypeptide fiber has a higher ability to shrink than the second fiber as the second fiber is a non-shrinkable fiber or a shrunk fiber (which cannot shrink anymore). In one another example, the first silk polypeptide has a higher ability to shrink than the second fiber as the first polypeptide fiber can shorten more in length than the second fiber. As aforementioned, it is preferred that the length of the first silk polypeptide fiber can shrink by at least 10% with regard to its total length after contact with a chemical, e.g. water. It is more preferred that the length of the silk polypeptide fiber can shrink by at least 30% with regard to its total length after contact with a chemical, e.g. water. For example, the length of the silk polypeptide fiber can shrink by 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% with regard to its total length. The second fiber shrinks correspondingly less.

[0079] The difference between the shrinkage rate / shrinkability of the at least one first fiber or yarn when being brought into contact with a chemical, e.g. water, and the shrinkage rate / shrinkability of the at least one second fiber or yarn when being brought into contact with the chemical, e.g. water, may be, for example, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more, or 50% or more.

[0080] The present inventors found that this difference in shrinkage ability is preferably reached by stretching / extending the first silk polypeptide fiber before it is used in the method of the present invention. More preferably, a full drawn first silk polypeptide fiber, i.e. a fiber that is (almost) completely stretched / extended (until shortly before the fiber was pulled off), is used in the method of the present invention. In contrast thereto, the second fiber is preferably not extended / stretched or only minimally extended / stretched (e.g. less than 1-fold), i.e. a fiber in a relaxed state.

[0081] The term “twisting”, as used herein, refers to a yam or yam bundle (cord) production process that binds fibers and / or yarns together in a continuous strand. In the method of the present invention, at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first shrinkable silk polypeptide fiber is twisted with at least one second fiber or yarn comprising the at least one second fiber.

[0082] A single yam is formed by twisting two or more single fibers together. A yam bundle (cord) is made by twisting two or more single yarns together.

[0083] The direction of the twist may be to the right, described as Z twist, or to the left, described as S twist.

[0084] Specifically, when a twisted yarn is held vertically, the individual fibers are appearing in this case as the diagonal in the letter "S". The same can apply if several yarns have been twisted together: their combined twist can again appear as the diagonal of the letter "S".

[0085] In addition, when a twisted yam is held vertically, the individual fibers are appearing in this case as the diagonal in the letter "Z". The same can apply if several yarns have been twisted together: their combined twist can again appear as the diagonal of the letter "Z". For example, a yam bundle (cord) can be made with a cable twist (S / Z / S or Z / S / Z) or with a hawser twist (S / S / Z or Z / Z / S). The number of turns per unit of length in a yam affects the appearance and durability of fabric made from that yarn. Yarns used for soft-surfaced fabrics have less twist than those used for smooth-surfaced fabrics. Yams made into crepe fabrics have maximum twist.

[0086] The number of tums / twists is stated in turns per meter (tpm or T / m). There are two different kinds of this indication:

[0087] Nominal number of turns: The number of turns per meter (T / m) stated as a nominal value.

[0088] Effective number of turns: This is the nominal turns per meter (tpm or T / m) with variations consistent with production processing.

[0089] The coefficient of twist is a measure of the level of twist of a yam, determined by the multiplication of the turns per unit length by the square root of the linear density on a direct system, or the division of the turns per unit length by the square root to the count on an indirect system

[0090] Preferably, the twisting carried out in the method of the present invention results in between 20 and 1000 twisting turns per metre. More preferably, the twisting carried out in the method of the present invention results in between 100 and 300 twisting turns per metre. For example, the twisting carried out in the method of the present invention results in 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, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, or 1000 twisting turns per metre.

[0091] More preferably, the at least one second fiber or yam comprising the fiber is twisted around the at least one first shrinkable silk polypeptide fiber or yam comprising the fiber.

[0092] The term “shrinking”, as used herein, refers to a process which results in the reduction of the length of the yarn or yarn bundle. The length of the yarn or yam bundle may be reduced after contact of the yarn or yarn bundle with a chemical, e.g. water. For shrinkage, the yarn or yarn bundle may be exposed to the chemical, e.g. water, by incubating the yarn or yam bundle in the chemical, e.g. water (like hot water), or by exposing the yarn or yarn bundle to vapor or steam of the chemical, e.g. water. When the shrinkage is carried out in a water bath, the water bath has preferably a temperature of > 20°C, more preferably of between 40°C and 80°C, e.g. 21, 22, 23, 24, 25, 26, 27, 28, 29,

[0093] 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,

[0094] 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, or 80°C. When the shrinkage is alternatively carried out in water vapor, the water vapor has preferably a temperature of > 80°C, more preferably between 85°C and 110°C, e.g. 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, or 110°C.

[0095] It is preferred that the length of the yarn or yarn bundle shrinks by at least 10% with regard to its total length after contact with a chemical, e.g. water. It is more preferred that the length of the yarn or yam bundle shrinks by at least 30% with regard to its total length after contact with a chemical, e.g. water. For example, the length of the yam or yam bundle shrinks by 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% with regard to its total length.

[0096] The term “irreversible shrinkage”, as used herein, means that the fiber does not return to its original shape without external impacts / influences, in particular without a force application, e.g. fiber extrusion, fiber extension, or fiber stretching.

[0097] The term “chemical”, as used herein, refers to any agent, e.g. in form of a solution or vapor, which allows fiber shrinkage. Preferably, the solution is an aqueous solution or a solution comprising alcohol. More preferably, the aqueous solution is a buffered aqueous solution, such as Tris / HCl, or water (H2O), such as technical H2O or deionized H2O, and / or the alcohol is ethanol or isopropanol.

[0098] The term “article”, as used herein, refers to any object comprising or consisting of the texturized yam or yarn bundle of the present invention.

[0099] It is preferred that the article is a textile / fabric. In one more preferred embodiment, the textile / fabric is a technical textile, smart textile, industrial fabric, or a high-performance material. In one another more preferred embodiment, the textile / fabric is / part of a garment, an apparel, or footwear (e.g. a shoe). The textile / fabric may be a woven textile / fabric or 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. 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 fiber. The term “synthetic fiber” also covers a fiber which is recombinantly produced. More preferably, the synthetic fiber is selected from the group consisting of a plastic fiber, a recombinant polypeptide fiber, a PET fiber, a PA fiber, a PP fiber, and an EA fiber. The word “synthetic” also means artificially put together in the context of the present invention.

[0100] 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 fiber. More preferably, the natural / naturally occurring fiber is selected from the group consisting of a cotton fiber, a flax fiber, a wool fiber, a hemp fiber, a bamboo fiber, a cellulose fiber, and a silk fiber (e.g. spider silk fiber).

[0101] Embodiments of the invention

[0102] 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.

[0103] The present inventors developed a new method for texturizing a yarn or yam bundle comprising silk fibers. In this method, at least one first shrinkable silk polypeptide fiber or yarn comprising the at least one first fiber is twisted with at least one second fiber or yarn comprising the at least one second fiber. The resulting yam or yarn bundle is subsequently shrunk in order to texturize the yarn or yam bundle. It is, thereby, preferred that the first fiber and the second fiber differ in their shrinkage ability, whereby it is more preferred that the first fiber has a higher ability to shrink than the second fiber. In which the first fiber shrinks and the second fiber does not or less in comparison, the second fiber is bulked / puffed up. This texturizing process results in the formation of crimps, loops, coils, and / or crinkles. Such changes in the physical form of a fiber affect the behaviour and hand of fabrics made therefrom. Said method, therefore, allows the production of yarns or yam bundles comprising silk fibers having improved properties with regard to haptic, optic, elasticity and / or thermal properties.

[0104] Thus, in a first aspect, the present invention relates to a method for texturizing a yarn or yarn bundle comprising the steps of:

[0105] (i) providing at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first fiber,

[0106] (ii) twisting the at least one first fiber or yarn provided in (i) with at least one second fiber or yarn comprising the at least one second fiber, thereby obtaining a yam or yarn bundle, and

[0107] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle.

[0108] In particular, the present invention relates to a method for texturizing a yam or yarn bundle comprising the steps of:

[0109] (i) providing at least one first shrinkable silk polypeptide fiber (e.g. at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000 fiber(s)) or at least one first yarn (e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000 yarn(s)) comprising the at least one first fiber,

[0110] (ii) twisting the at least one first fiber or the at least one yam provided in (i) with at least one second fiber (e.g. at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, or 10000 fiber(s)) or at least one second yam (e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000 yam(s)) comprising the at least one second fiber, thereby obtaining a yarn or yarn bundle, and

[0111] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle.

[0112] Step (i) of the method of the present invention requires the provision of at least one first shrinkable silk polypeptide fiber.

[0113] The at least one first shrinkable silk polypeptide fiber may be a staple fiber or a continuous / endless fiber.

[0114] It is preferred that the length of the silk polypeptide fiber can shrink by at least 10% with regard to its total length after contact with a chemical, e.g. water. It is more preferred that the length of the silk polypeptide fiber can shrink by at least 20% with regard to its total length after contact with a chemical, e.g. water. It is even more preferred that the length of the silk polypeptide fiber can shrink by at least 30% with regard to its total length after contact with a chemical, e.g. water. For example, the length of the silk polypeptide fiber can shrink by 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% with regard to its total length. The fiber may be a fiber as produced in WO 2014 / 037453.

[0115] It is further (alternatively or additionally) preferred that the silk polypeptide fiber has a linear density of between 0.5 and 700 Decitex (dtex). It is more preferred that the silk polypeptide fiber has a linear density of between 0.5 and 300 dtex. It is even more preferred that the silk polypeptide fiber has a linear density of between 0.5 and 10 dtex. For example, the silk polypeptide fiber has a linear density of 0.5, 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, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, or 700 dtex.

[0116] It is also (alternatively or additionally) preferred that the silk polypeptide fiber has a thickness (diameter) of between 0,5 pm and 300 pm. It is more preferred that the silk polypeptide fiber has a thickness (diameter) of between 1 pm and 200 pm. For example, the fiber has a thickness of 0,5, 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, 60, 70, 80, 90, 100, 150, 200, 250, or 300 pm.

[0117] Especially, the first shrinkable silk polypeptide fiber has no thermoplastic properties but hydroplastic properties which are used in the method of the present invention, namely by exposing the first shrinkable silk polypeptide fiber to a chemical such as water or water vapor to induce shrinkage in order to texturize the yam or yam bundle comprising the first silk polypeptide fiber.

[0118] The first yam which is alternatively provided in step (i) of the method of the present invention is composed of 2 or more first shrinkable silk polypeptide fibers. These fibers are twisted, interlocked, or grouped together.

[0119] For example, a yarn comprising the first shrinkable silk polypeptide fiber is composed of between 2 and 10000 first shrinkable silk polypeptide fibers, preferably between 2 and 1000 first shrinkable silk polypeptide fibers, and more preferably between 2 and 500 first shrinkable silk polypeptide fibers, 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 first shrinkable silk polypeptide fibers. It is preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a linear density of between 2 and 800 Decitex (dtex). It is more preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a linear density of between 30 and 500 dtex. It is even more preferred that the yam comprising the first shrinkable silk polypeptide fiber has a linear density of between 50 and 300 dtex. For example, the yarn comprising the first shrinkable silk polypeptide fiber has a linear density of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,

[0120] 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,

[0121] 44, 45, 46, 47, 48, 49, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, or 800 dtex.

[0122] It is (alternatively or additionally) preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a thickness (diameter) of between 1 pm and 400 pm. It is more preferred that the yarn comprising the first shrinkable silk polypeptide fiber has a thickness (diameter) of between 10 pm and 300 pm. For example, the yarn comprising the first shrinkable silk polypeptide fiber has a thickness of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,

[0123] 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,

[0124] 45, 46, 47, 48, 49, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, or 400 pm.

[0125] It is more preferred that the first shrinkable silk polypeptide fiber which is provided in step (i) of the method of the present invention is a stretched / extended fiber, e.g. a single-drawn and multi-drawn (e.g. double-drawn) fiber. It is even more preferred that the first shrinkable silk polypeptide fiber is a full drawn fiber, i.e. a fiber that is (almost) completely stretched / extended (until shortly before the fiber was pulled off) after its production.

[0126] 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 fiber and, thereby, improves the properties of the fiber. It is preferred that the fiber is extended after it has been drawn or extruded. Such extension can be carried out in a continuous or discontinuous process. In the continuous process it is preferred that the fiber is exposed to a pulling force. Preferably, the extension of the fiber is by at least 2-fold in comparison to the length of the fiber as drawn or 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.

[0127] During extension the cross-sectional area of the fiber 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%.

[0128] In step (ii) of the method of the present invention, the at least one first fiber or yarn comprising the at least one first fiber provided in (i) is twisted with at least one second fiber or yarn comprising the at least one second fiber. Thereby, a yarn or yam bundle is obtained. For example, at least one first fiber is twisted with at least one second fiber, at least one first yam is twisted with at least one second yarn, at least one first fiber is twisted with at least one second yam, or at least one first yarn is twisted with at least one second fiber in step (ii) of the method of the present invention.

[0129] In step (ii) of the method of the present invention, a second fiber is used for the twisting. The at least one second fiber may be a staple fiber or a continuous / endless fiber.

[0130] It is preferred that the second fiber has a linear density of between 0.5 and 700 Decitex (dtex). It is more preferred that the second fiber has a linear density of between 0.5 and 300 dtex. It is even more preferred that the second fiber has a linear density of between 0.5 and 10 dtex. For example, the second fiber has a linear density of 0.5, 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, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, or 700 dtex.

[0131] It is further (alternatively or additionally) preferred that the second fiber has a thickness (diameter) of between 0,5 pm and 300 pm. It is more preferred that the second fiber has a thickness (diameter) of between 1 pm and 200 pm. For example, the fiber has a thickness of 0,5, 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, 60, 70, 80, 90, 100, 150, 200, 250, or 300 pm.

[0132] The second yam which is alternatively used in step (ii) of the method of the present invention is composed of 2 or more second fibers. These fibers are twisted, interlocked, or grouped together.

[0133] For example, a yarn comprising the second fiber is composed of between 2 and 10000 second fibers, preferably between 2 and 1000 second fibers, and more preferably between 10 and 100 second fibers, 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 second fibers.

[0134] It is preferred that the yarn comprising the second fiber has a linear density of between 2 and 800 Decitex (dtex). It is more preferred that the yam comprising the second fiber has a linear density of between 30 and 500 dtex. It is even more preferred that the yarn comprising the second fiber has a linear density of between 50 and 300 dtex. For example, the yarn comprising the second fiber has a linear density of 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, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, or 800 dtex.

[0135] It is (alternatively or additionally) preferred that the yarn comprising the second fiber has a thickness (diameter) of between 1 pm and 400 pm. It is more preferred that the yam comprising the second fiber has a thickness (diameter) of between 10 pm and 300 pm. For example, the yarn comprising the second fiber has a thickness of 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, 60, 70, 80, 90, 100, 150, 200, 250, 300, or 400 pm.

[0136] In particular, the twisting step establishes a defined torsional relationship between the at least one first fiber or yarn and the at least one second fiber or yam. This configuration enables the storage of mechanical energy within the yarn structure, which becomes an active architectural driver in the subsequent shrinking step. The resulting geometry is not merely a byproduct of fiber or yam processing, but rather a functional determinant of the final three- dimensional microstructure.

[0137] The twisting in step (ii) can be carried out in Z direction (from top right to bottom left) or S direction (from top left to bottom right). The twisting may result in between 20 and 1000, particularly between 100 and 300, twisting turns per metre. For example, the twisting carried out in the method of the present invention results in 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, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, or 1000 twisting turns per metre.

[0138] Preferably, the at least one second fiber or yarn comprising the fiber is twisted around the at least one first shrinkable silk polypeptide fiber or yarn comprising the fiber.

[0139] This twisting specifically results in a wrapping of the at least one second fiber or yarn around the at least one first fiber or yam in a helical manner.

[0140] In other words, step (ii) creates a core-sheath torsional architecture in which the at least one second fiber or yarn forms a helical structure around the at least one first fiber or yarn.

[0141] This helical orientation offers diverse advantages. Said core-sheath topology provides a directed spatial arrangement at the fiber or yam level, enabling uniform transmission of torsional stress and controlled redistribution of stress upon shrinkage. This architecture is reproducible, adjustable through twist density, and inherently scalable.

[0142] When the at least one first fiber or yarn shrinks, the release of stored torsional stress leads to a predictable formation of loops, waves, and undulations in the at least one second fiber or yarn. The microstructure generated is inherently directional and structurally defined by the pre- established twist geometry. The resulting texturized yarn exhibits a stable and consistent morphology along its length.

[0143] The helical wrapping is not a transient feature but a persistent geometric relationship in the yarn. It remains present in the final product after texturization and contributes directly to its tactile, mechanical, and optical properties. The twist of the at least one second fiber or yarn comprising the fiber around the at least one first shrinkable silk polypeptide fiber or yam comprising the fiber is not solely a method of yarn formation but a structural characteristic of the finished yam itself.

[0144] Thus, in one preferred embodiment, the present invention relates to a method for texturizing a yam or yarn bundle comprising the steps of

[0145] (i) providing at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first fiber,

[0146] (ii) twisting at least one second fiber or yarn comprising the fiber around the at least one first shrinkable silk polypeptide fiber or yam comprising the fiber provided in (i), thereby obtaining a yarn or yarn bundle, and

[0147] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle.

[0148] The helical core-sheath architecture provides a controlled and directed spatial arrangement of the fibers / yarns, enabling storage of torsional energy during twisting and its targeted release during shrinkage of the core (first) fiber / yam. This structural relationship results in a predictable formation of loops and undulations in the sheath (second) fiber, creating a defined three-dimensional micro-topography along the yarn / yam bundle. The core-sheath configuration improves redistribution of tensile stress, reduces peak strain concentration, and enhances fatigue resistance and elongation performance of the yam. Furthermore, the geometry acts as a mechanical buffer system, supporting energy absorption, adaptive deformation behavior, and improved material resilience. The resulting yarn / yam bundle exhibits enhanced functional, tactile, and mechanical characteristics that are not achievable with randomly blended fiber systems.

[0149] In addition, the helical core-sheath system allows the degree of texturization to be tuned through parameters such as twist density, twist direction, fiber composition, and shrinkage conditions. This structural controllability enables the yarn / yam bundle to exhibit defined mechanical and morphological characteristics, including adjustable elasticity, damping behavior, and surface complexity. The architecture can therefore be engineered to meet specific performance requirements for a wide range of applications, from flexible textiles and reinforcement structures to biofunctional or mechanically active material systems that benefit from controlled microstructural design.

[0150] The second fiber can be a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber. In contrast to the first silk polypeptide fiber, it is preferred that the second fiber is not extended / stretched or only minimally extended / stretched (e.g. less than 1-fold). Thus, the second fiber is preferably relaxed / in a relaxed state. This fiber may also be designated as prime fiber herein.

[0151] The first silk polypeptide fiber provided in step (i) of the method of the present invention and the second fiber used for the twisting in step (ii) of the method of the present invention are preferably characterized by a different shrinkage ratio. In other words, it is preferred that the first silk polypeptide fiber and the second fiber differ from each other in their ability to shrink. It is more preferred that the first silk polypeptide fiber has a higher ability to shrink than the second fiber.

[0152] As mentioned above, the second fiber can be a shrunk fiber, a shrinkable fiber, or a non- shrinkable fiber. Thus, in one example, the first silk polypeptide fiber has a higher ability to shrink than the second fiber as the second fiber is a non-shrinkable fiber or a shrunk fiber (which cannot shrink anymore). In one another example, the first silk polypeptide has a higher ability to shrink than the second fiber as the first polypeptide fiber can shorten more in length than the second fiber. As aforementioned, it is preferred that the length of the first silk polypeptide fiber can shrink by at least 10% with regard to its total length after contact with a chemical, e.g. water. It is more preferred that the length of the silk polypeptide fiber can shrink by at least 30% with regard to its total length after contact with a chemical, e.g. water. For example, the length of the silk polypeptide fiber can shrink by 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% with regard to its total length. The second fiber shrinks correspondingly less.

[0153] The difference between the shrinkage rate / shrinkability of the at least one first fiber or yarn when being brought into contact with a chemical, e.g. water, and the shrinkage rate / shrinkability of the at least one second fiber or yarn when being brought into contact with the chemical, e.g. water, may be, for example, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more, or 50% or more.

[0154] The present inventors found that this difference in shrinkage ability is preferably reached by stretching / extending the first silk polypeptide fiber before it is used in the method of the present invention. More preferably, a full drawn first silk polypeptide fiber, i.e. a fiber that is (almost) completely stretched / extended (until shortly before the fiber was pulled off), is used in the method of the present invention. In contrast thereto, the second fiber is preferably not extended / stretched or only minimally extended / stretched (e.g. less than 1-fold), i.e. a fiber in a relaxed state.

[0155] Thus, in one more preferred embodiment, the present invention relates to a method for texturizing a yarn or yarn bundle comprising the steps of:

[0156] (i) providing at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first fiber,

[0157] (ii) twisting at least one second fiber or yarn comprising the fiber around the at least one first shrinkable silk polypeptide fiber or yam comprising the fiber provided in (i), thereby obtaining a yarn or yarn bundle, and

[0158] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle, wherein the at least one first shrinkable silk polypeptide fiber and the at least one second fiber differ in their ability to shrink, whereby the at least one first shrinkable silk polypeptide fiber has a higher ability to shrink than the second fiber.

[0159] In this respect, it should be noted that the second fiber can be a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber.

[0160] In one even more preferred embodiment, the present invention relates to a method for texturizing a yarn or yarn bundle comprising the steps of:

[0161] (i) providing at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first fiber,

[0162] (ii) twisting at least one second fiber or yarn comprising the fiber around the at least one first shrinkable silk polypeptide fiber or yam comprising the fiber provided in (i), thereby obtaining a yarn or yarn bundle, and

[0163] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle, wherein the at least one first shrinkable silk polypeptide fiber is a full drawn first silk polypeptide fiber, i.e. a fiber that is (almost) completely stretched / extended (until shortly before the fiber was pulled off) and the second fiber is not extended / stretched or only minimally extended / stretched (e.g. less than 1-fold), i.e. a fiber in a relaxed state, and wherein the at least one first shrinkable silk polypeptide fiber and the at least one second fiber differ in their ability to shrink, whereby the at least one first shrinkable silk polypeptide fiber has a higher ability to shrink than the second fiber.

[0164] Again, in this respect, it should be noted that the second fiber can be a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber. The shrinkage in step (iii) of the method of the present invention is a process which results in the reduction of the length of the yarn or yam bundle. The length of the yarn or yarn bundle may be reduced after contact of the yarn or yam bundle with a chemical, e.g. water. For shrinkage, the yarn or yam bundle may be exposed to the chemical, e.g. water, by incubating the yam or yam bundle in the chemical, e.g. water, or by exposing the yam or yam bundle to vapor of the chemical, e.g. water.

[0165] In step (iii) of the method of the present invention, the shrinking is preferably performed by incubating the yam or yarn bundle in a water bath or by exposing the yam or yarn bundle to water vapor.

[0166] When the shrinkage is carried out in a water bath, the water bath has preferably a temperature of > 20°C, more preferably of between 40°C and 80°C, e.g. 21, 22, 23, 24, 25, 26, 27, 28, 29,

[0167] 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,

[0168] 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, or 80°C. When the shrinkage is alternatively carried out in water vapor, the water vapor has preferably a temperature of > 80°C, more preferably between 85°C and 110°C, e.g. 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, or 110°C.

[0169] It is preferred that the length of the yarn or yarn bundle shrinks by at least 10% with regard to its total length after contact with a chemical, e.g. water. It is more preferred that the length of the yarn or yam bundle shrinks by at least 30% with regard to its total length after contact with a chemical, e.g. water. For example, the length of the yam or yam bundle shrinks by 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% with regard to its total length.

[0170] It is preferred that the shrinkage is irreversible, i.e. that the shrunk fiber does not change in length afterwards anymore.

[0171] As to the shrinkage, it should be noted that in step (iii) the at least one first silk polypeptide fiber comprised in the yam or yam bundle preferably shrinks. The shrinkage of the first silk polypeptide fiber also leads to the shrinkage of the yam or yam bundle comprising said fiber. In particular, due to the shrinkage, an emergent micro-architecture comprising non-linear fiber geometries that protrude from the core vector of the yam are formed.

[0172] The shrinkage of the at least one first fiber or yarn generates a tensile distortion force that acts upon the at least one second fiber or yam and alters its spatial arrangement. Specifically, the at least one second fiber or yarn comprising the fiber forms, as a result of the shrinkage of the at least one first silk polypeptide fiber or yam comprising the fiber, loops, waves, and / or undulations.

[0173] Preferably, the at least one first silk polypeptide fiber shrinks by at least 10% with regard to its total length. More preferably, the at least one first silk polypeptide fiber shrinks by at least 30% with regard to its total length. For example, the at least one first silk polypeptide fiber shrinks by 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% with regard to its total length.

[0174] As mentioned above, the at least one second fiber is a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber. Specifically, the shrunk fiber is obtained by incubating the fiber in a water bath or by exposing the fiber to water vapor.

[0175] When the shrinkage is carried out in a water bath, the water bath has preferably a temperature of > 20°C, more preferably of between 40°C and 80°C, e.g. 21, 22, 23, 24, 25, 26, 27, 28, 29,

[0176] 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,

[0177] 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, or 80°C. When the shrinkage is alternatively carried out in water vapor, the water vapor has preferably a temperature of > 80°C, preferably between 85°C and 110°C, e.g. 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, or 110°C.

[0178] Accordingly, in this method, at least one first shrinkable silk polypeptide fiber or yam comprising the at least one first fiber is twisted with at least one second fiber or yarn comprising the at least one second fiber. The resulting yam or yarn bundle is subsequently shrunk in order to texturize the yarn or yam bundle. It is, thereby, preferred that the first fiber and the second fiber differ in their shrinkage ability, whereby it is more preferred that the first fiber has a higher ability to shrink than the second fiber. In which the first fiber shrinks and the second fiber does not or less in comparison, the second fiber is bulked / puffed up. This texturizing process results in the formation of crimps, loops, coils, and / or crinkles. Such changes in the physical form of a fiber affect the behaviour and hand of fabrics made therefrom. Said method, therefore, allows the production of yams or yarn bundles comprising silk fibers having improved properties with regard to haptic, optic, elasticity and / or thermal properties.

[0179] Specifically, the proportion of the silk polypeptide fiber(s) in the yarn or yarn bundle obtained in step (iii) is at least 10%. More specifically, the proportion of the silk polypeptide fiber(s) in the yarn or yam bundle obtained in step (iii) is at least between 20% and 30%. Even more specifically, the proportion of the silk polypeptide fiber(s) in the yam or yarn bundle obtained in step (iii) is at least between 40% and 50%. Still even more specifically, the proportion of the silk polypeptide fiber(s) in the yarn or yarn bundle obtained in step (iii) is at least between 60% and 70%, or even higher. For example, the proportion of the silk polypeptide fiber(s) in the yarn or yam bundle obtained in step (iii) is at least 10, 11, 12, 13, 14, 15, 16, 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, 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%, or even higher. Most specifically, the yam or yam bundle obtained in step (iii) is entirely composed of silk polypeptide fibers, i.e. 100%.

[0180] Especially, the ratio of the at least one first silk polypeptide fiber or yam comprising the fiber and the ratio of the at least one second fiber or yarn comprising the fiber in the yam or yarn bundle obtained in step (iii) is 1 : 1, 1 :2, 1 :3, or 1 :4.

[0181] The method of the present invention additionally allows fine-tuning of textural properties through adjustment of several variables, including twist rate, twist direction, fiber composition, and shrinkage parameters. The responsiveness of the system to these variables offers a robust control framework enabling tailoring for different end uses and performance requirements.

[0182] The method of the present invention may further comprise step (iv) of drying the yarn or yam bundle. The drying may be performed in the ambient air, in a hot chamber, or with hot air. The drying may be performed at a temperature of between 20 and 100°C, preferably of between 60 and 100°C, and / or over a specific period of time. Particularly, the drying time depends on the equipment. Typically for conductive drying (warm surface contact, between 60 and 100°C), the drying time is between 1 and 30 seconds, preferably between 10 and 30 seconds. Typically for convective drying (hot air flow, between 60 to 100°C), the drying time is between 5 and 100 seconds, preferably between 20 and 80 seconds. For example, the drying may be performed at 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 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,

[0183] 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,

[0184] 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100°C and / or for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,

[0185] 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 29, 30, 31, 32, 33, 34, 35, 36,

[0186] 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,

[0187] 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,

[0188] 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 seconds.

[0189] Preferably, the at least one first silk polypeptide fiber used in the method of the present invention is a recombinant silk polypeptide fiber. 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.

[0190] 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.

[0191] 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,

[0192] 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,

[0193] 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,

[0194] 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,

[0195] 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 repetitive units.

[0196] 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.

[0197] 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.

[0198] 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,

[0199] 18, 20, 24, 27, 28, 30, 34, or more amino acids, preferably over the whole length of the respective reference module C. 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.

[0200] 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.

[0201] 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 shrink and, thus, for texturizing. 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.

[0202] 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).

[0203] 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,

[0204] 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,

[0205] 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,

[0206] 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, or 96.

[0207] 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, CLy% CLyS16, CLyS32, or CLys48.

[0208] The silk polypeptide Cs has 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.

[0209] 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.

[0210] 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.

[0211] Preferably, the at least one second fiber used in the method of the present invention is a synthetic fiber, a natural fiber, or a regenerated fiber.

[0212] As mentioned above, is preferred that the second fiber is a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber. Thus, the second fiber may be a shrunk, shrinkable, non-shrinkable synthetic fiber, a shrunk, shrinkable, non-shrinkable natural fiber, or a shrunk, shrinkable, non-shrinkable regenerated fiber.

[0213] More preferably

[0214] (a) the synthetic fiber is selected from the group consisting of a plastic fiber, a recombinant polypeptide fiber, a PET fiber, a PA fiber, a PP fiber, and an EA fiber,

[0215] (b) the natural fiber is selected from the group consisting of a cotton fiber, a flax fiber, a wool fiber, a hemp fiber, a bamboo fiber, a cellulose fiber, and a silk fiber, or

[0216] (c) the regenerated fiber is selected from the group consisting of a viscose fiber, a modal fiber, and a cupro fiber.

[0217] Even more preferably,

[0218] (ai) the plastic fiber is selected from the group consisting a polyester fiber, an elastane fiber, a polyamide fiber, a polyacrylic fiber, and a polyurethane fiber, or

[0219] (aii) the recombinant polypeptide fiber is a silk polypeptide fiber such as a spider silk polypeptide fiber.

[0220] Still even more preferably, at least one first shrinkable (recombinant) silk polypeptide fiber and at least one second (recombinant) silk polypeptide fiber is used for twisting / shrinking. Thus, in one still even more preferred embodiment, the present invention relates to a method for texturizing a yarn or yarn bundle comprising the steps of:

[0221] (i) providing at least one first shrinkable (recombinant) silk polypeptide such as spider silk polypeptide fiber or yarn comprising the at least one first fiber,

[0222] (ii) twisting at least one second (recombinant) silk polypeptide such as spider silk polypeptide fiber or yam comprising the fiber around the at least one first shrinkable silk polypeptide fiber or yarn comprising the fiber provided in (i), thereby obtaining a yarn or yarn bundle, and

[0223] (iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle, wherein the at least one first shrinkable (recombinant) silk polypeptide such as spider silk polypeptide fiber is a full drawn first silk polypeptide fiber, i.e. a fiber that is (almost) completely stretched / extended (until shortly before the fiber was pulled off) and the second (recombinant) silk polypeptide such as spider silk polypeptide fiber is not extended / stretched or only minimally extended / stretched (e.g. less than 1-fold), i.e. a fiber in a relaxed state, and / or wherein the at least one first shrinkable (recombinant) silk polypeptide such as spider silk polypeptide fiber and the at least one second (recombinant) silk polypeptide such as spider silk polypeptide fiber differ in their ability to shrink, whereby the at least one first shrinkable (recombinant) silk polypeptide such as spider silk polypeptide fiber has a higher ability to shrink than the second (recombinant) silk polypeptide such as spider silk polypeptide fiber.

[0224] In a second aspect, the present invention relates to a texturized (and shrunk) yam or yam bundle obtained / obtainable by the method according to the first aspect.

[0225] In a third aspect, the present invention relates to a texturized (and shrunk) yam or yarn bundle comprising at least one first shrunk silk polypeptide fiber or yam comprising the fiber and at least one second fiber or yarn comprising the fiber, wherein the at least one second fiber or yam comprising the fiber is twisted around the at least one first shrunk silk polypeptide fiber or yarn comprising the fiber.

[0226] Preferably, the twist in the texturized (and shrunk) yam or yarn bundle is between 20 and 1000 twisting turns per metre, more preferably between 100 and 300 turns per metre. For example, the twist in the texturized (and shrunk) yarn or yarn bundle is 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, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, or 1000 twisting turns per metre.

[0227] More preferably, the at least one second fiber is a shrunk / non-shrinkable fiber. The shrunk second fiber is specifically not able to shrink anymore. It is irreversibly be shrunken. The at least one second fiber forms loops, waves, and / or undulations in the yam or yarn bundle.

[0228] Particularly, the at least one second fiber is a synthetic fiber, a natural fiber, or a regenerated fiber.

[0229] More particularly

[0230] (a) the synthetic fiber is selected from the group consisting of a plastic fiber, a recombinant polypeptide fiber, a PET fiber, a PA fiber, a PP fiber, and an EA fiber,

[0231] (b) the natural fiber is selected from the group consisting of a cotton fiber, a flax fiber, a wool fiber, a hemp fiber, a bamboo fiber, a cellulose fiber, and a silk fiber, or

[0232] (c) the regenerated fiber is selected from the group consisting of a viscose fiber, a modal fiber, and a cupro fiber.

[0233] Even more particularly,

[0234] (ai) the plastic fiber is selected from the group consisting a polyester fiber, an elastane fiber, a polyamide fiber, a polyacrylic fiber, and a polyurethane fiber, or

[0235] (aii) the recombinant polypeptide fiber is a silk polypeptide fiber such as a spider silk polypeptide fiber.

[0236] Still even more particularly, the at least one second fiber is a shrunk silk polypeptide fiber.

[0237] The texturized (and shrunk) yarn or yam bundle as described herein has advantages over the yarn or yam bundle of the prior art. First, the contraction of silk yam or yarn bundles (respective multifilamenf s) leads to permanent ondulation of yam or yam bundles. Second, the waviness results in a softer feel or fluffmess on the yarn side, but also on the textile side. In addition, more air is trapped in the textile surface, thus reducing heat conduction. The feel and look is much more like animal wool. The yarn or yarn bundles as described in the prior art are not curled, crimped or textured. In addition, known crimped thermoplastic fibers lose their crimp when they cross the glass point and become straight again. In this way, they become useless.

[0238] As mentioned above, a texturized (and shrunk) yarn or yarn bundle comprising at least one first shrunk silk polypeptide fiber or yam comprising the fiber and at least one second fiber or yam comprising the fiber is provided in the third aspect, wherein the at least one second fiber or yarn comprising the fiber is twisted around the at least one first shrunk silk polypeptide fiber or yarn comprising the fiber.

[0239] In this regard, it should be noted that the at least one second fiber or yarn comprising the fiber is twisted around the at least one first shrunk silk polypeptide fiber or yarn comprising the fiber in a helical core-sheath configuration. The shrinkage of the at least one first silk polypeptide fiber has resulted in the formation of loops, waves, and / or undulations of the at least one second fiber.

[0240] As to all other embodiments of the silk polypeptide fiber or yam comprising said fiber and the second fiber or yam comprising said fiber, it is referred to the first aspect of the present invention.

[0241] In a fourth aspect, the present invention relates to an article comprising the texturized (and shrunk) yam or yarn bundle according to the second or third aspect.

[0242] The article may be any object comprising or consisting of the texturized yarn or yarn bundle of the present invention. In one preferred embodiment, the article is a textile / fabric. In one more preferred embodiment, the textile / fabric is a technical textile, smart textile, industrial fabric, or a high-performance material. In one another more preferred embodiment, the textile / fabric is / part of a garment, an apparel, or footwear (e.g. a shoe). The textile / fabric may be a woven textile / fabric or 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.

[0243] An article comprising the texturized and shrunk yarn benefits from the engineered microstructure of the yam, resulting in improved mechanical robustness, surface characteristics, and functional adaptability. When the article is a textile, the three-dimensional fiber topology can impart enhanced durability, tactile comfort, elasticity, and structural consistency throughout the fabric. In apparel or footwear, these properties translate into superior wearing comfort, fit, and resistance to deformation under repeated use. In technical textiles, smart textiles, industrial fabrics, or high-performance material applications, the yarn contributes to improved structural reinforcement, targeted load distribution, and precise control over fabric behavior under mechanical or environmental stress.

[0244] Specifically, the textured yarn or yam bundle comprises fiber crimps, loops, coils, and / or crinkles. Such changes in the physical form of the fibers 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 fibers, e.g. finished fabrics.

[0245] Thus, in a fifth aspect, the present invention relates to the use of the texturized (and shrunk) yarn or yarn bundle according to the second or third aspect in the textile industry. Preferably, the yarn or yam bundle is used in apparel, footwear (e.g. shoes), technical textiles, smart textiles, industrial fabrics, or performance materials.

[0246] The use of the texturized and shrunk yam / yarn bundle in the textile industry provides a versatile platform for engineering fabrics with enhanced functional performance and customized material behavior. Owing to its defined microstructural architecture, the yarn can contribute to improved flexibility, comfort, mechanical resilience, and stress distribution within the final textile product. Whether employed in apparel, footwear, technical textiles, smart textiles, industrial fabrics, or performance materials, the yarn / yarn bundle enables application-specific optimization of fabric characteristics, supporting the development of advanced textile solutions for diverse markets and use conditions.

[0247] In a sixth aspect, the present invention relates to the use of the texturized (and shrunk) yarn or yarn bundle according to the second or third aspect for the manufacture of a textile / fabric.

[0248] It is preferred that the textile / fabric is / part of an apparel or a shoe. It is also preferred that the textile / fabric is a technical textile, smart textile, industrial fabric, or a high-performance material.

[0249] The use of the texturized and shrunk yam / yam bundle for textile manufacture enables the production of fabrics with tailored mechanical and tactile performance characteristics. Depending on the application, the yarn / yarn bundle can impart improved elasticity, localized compression response, enhanced surface structure, or increased energy dissipation into the resulting textile. When implemented in apparel or footwear, this contributes to superior comfort, fit, and durability. In technical, smart, industrial, or high-performance textile systems, the yarn can provide targeted functional properties such as controlled deformation, structural reinforcement, or elevated material responsiveness to environmental or mechanical stimuli.

[0250] In a further aspect, the present invention relates to a method for producing a texturized yarn or yam bundle by creating internal torsional stress and releasing the same through differential shrinkage of at least one first fiber component, thereby forming a texturized yarn or yarn bundle microstructure. The internal torsional stress is created by twisting at least one second fiber or yam comprising the fiber around the at least one first fiber component. The at least one first fiber component is preferably a silk polypeptide, e.g. spider silk polypeptide, fiber or yam.

[0251] The at least one second fiber is preferably a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber. In case the at least one second fiber is a shrinkable fiber, it has a lower shrinkage ability than the at least one first fiber component. As to all other preferred embodiments, it is referred to the first aspect of the present invention.

[0252] In a further aspect, the present invention relates to a yam or yam bundle produced by inducing mechanical torsional energy storage followed by shrink-triggered internal reorganization at the fiber scale.

[0253] In one preferred embodiment, the mechanical torsional energy storage is generated by twisting at least one second fiber or yam comprising the fiber around at least one first shrinkable silk polypeptide fiber or yarn comprising the fiber in a helical manner, preferably in S- or Z- direction.

[0254] Specifically, the twisting comprises between 20 and 1000 twisting turns per metre, particularly between 100 and 300 twisting turns per metre.

[0255] In one more preferred embodiment, the shrink-triggered internal reorganization results in the formation of loops, waves, and / or undulations of the at least one second fiber or yarn comprising the fiber.

[0256] In one even more preferred embodiment, the at least one first fiber or yarn comprises a spider silk polypeptide fiber or yarn, particularly a recombinant spider silk polypeptide fiber or yarn. As to all other preferred embodiments, it is referred to the first aspect of the present invention.

[0257] 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.

[0258] BRIEF DESCRIPTION OF THE FIGURES

[0259] 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.

[0260] Figure 1: (A) shows a first shrinkable silk polypeptide fiber or yarn at a defined length (x) before exposition to warm water (50°C-80°C) or steam. (B) shows a second shrunk silk polypeptide fiber or yarn after exposition to warm water (50°C-80°C) or steam. (C) shows a first shrinkable fiber or yam (filament bundle (1 - 500 single filaments combined) or a POY staple fiber yarn (30 - 500 dtex)) combined with a second shrunk silk polypeptide fiber or yam (filament bundle (1 - 500 single filaments combined or a staple fiber yam (30 - 500 dtex)). (D) shows a combination of the first shrinkable silk polypeptide fiber or yam and the second shrunk silk polypeptide fiber or yarn twisted together in “Z” or “S” direction with a twist between 50 and 2000 turns / meter. (E) shows the combination of both fibers or yarns (B) after exposition to warm water (50°C-80°C) or steam. The first shrinkable silk polypeptide fiber or yarn contracts and forces the second shrunk silk polypeptide fiber or yam to build loops / undulations (bundle). With the drying of the fiber bundle the form will be fixated.

[0261] Figure 2: (A) shows a first shrinkable silk polypeptide fiber multifilament (40 filaments, 95dtex) twisted with a second silk polypeptide fiber multifilament (40 filaments, 95dtex) after exposition of the fiber bundle to warm water (50°C-80°C). (B) shows a two first shrinkable silk polypeptide fiber multifilaments (40 filaments, 95dtex) twisted with a second silk polypeptide fiber multifilament (40 filaments, 95dtex) after exposition of the fiber bundle to warm water (50°C-80°C).

[0262] Figure 3: Shows a first shrunk silk polypeptide fiber twisted together with a second silk polypeptide fiber. la: AMSILK = silk polypeptide fiber twisted together with HT-PET = High Tenacity

[0263] Polyester fiber lb: AMSILK = silk polypeptide fiber twisted together with primed HT-PET = High

[0264] Tenacity Polyester fiber

[0265] 2a: AMSILK = silk polypeptide fiber twisted together with CO = cotton fiber

[0266] 2b: AMSILK = silk polypeptide fiber twisted together with primed CO = cotton fiber

[0267] 3a: AMSILK = silk polypeptide fiber twisted together with LI = linen fiber

[0268] 3b: AMSILK = silk polypeptide fiber twisted together with primed LI = linen fiber

[0269] 4a: AMSILK = silk polypeptide fiber twisted together with SE = silk mulberry fiber

[0270] 4b: AMSILK = silk polypeptide fiber twisted together with primed SE = silk mulberry fiber

[0271] 5a: AMSILK = silk polypeptide fiber twisted together with WO = wool like fiber which can be sheep, Merino sheep, goat like vicunia, alpaca, mohair, or camel like fiber

[0272] 5b: AMSILK = silk polypeptide fiber twisted together with primed WO = wool like fiber which can be sheep, Merino sheep, goat like vicunia, alpaca, mohair, or camel like fiber EXAMPLES

[0273] The examples given below are for illustrative purposes only and do not limit the invention described above in any way.

[0274] EXAMPLE 1 :

[0275] 1, Spider silk protein preparation:

[0276] Recombinant spider silk proteins (e.g. C48CCys) were prepared as described in WO 2006 / 008163.

[0277] 2, Spider silk protein spinning dope preparation:

[0278] 500 mg of the recombinant spider silk protein (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:

[0279] 1) Buffer 1 : 50 mM NH4HCO3 (pH 7.8), 500 mM urea, 500 mM GdmSCN,

[0280] 2) Buffer 2: 50 mM NH4HCO3 (pH 7.8), 500 mM urea, 250 mM GdmSCN, and

[0281] 3) Buffer 3 : 50 mM NH4HCO3 (pH 7.8), 500 mM urea.

[0282] 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.

[0283] 3, Spider silk protein fiber production:

[0284] For wet spinning, the spinning dope comprising the spider silk protein was transferred into a spinneret with a spinning nozzle. 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 fiber was taken out of the coagulation bath and was stretched in a stretching bath. As stretching bath, ethanol, butanol, methanol, propanol, polyethylene glycol, isopropanol, or H2O was used. After stretching, the fiber was taken out of the stretching bath. In order to produce fibers with different shrinkage potential, a coagulated fiber can alternatively be taken out of the coagulation bath without stretching in a stretching bath (e.g. for the use as the first fiber or yarn) and another coagulated fiber can be taken out of the coagulation bath and can be stretched in a stretching bath (e.g. for the use as the second fiber or yam).

[0285] 4, Spider silk protein fiber texturizing:

[0286] In the next experiment, texturization of silk-based yarns by controlled shrinkage in water was tested. Specifically, the objective was to investigate the texturization of a yam comprising shrinkable silk polypeptide fibers as first component and a second type of fibers as second component using a differential shrinkage method, wherein the yam is twisted by exposure to water or water vapor which induces shrinkage. The goal was to observe the formation of crimps, loops, coils, and / or crinkles due to differential shrinkage between the fibers. Besides yarns of different composition, also yarn bundles were in focus.

[0287] MATERIALS:

[0288] Fibers / Yarns:

[0289] First fiber or yam: shrinkable silk polypeptide fiber or yam (with high shrinkage potential) composed of this fiber.

[0290] Second fiber or yam: silk polypeptide fiber or yarn composed of this fiber (with low or negligible shrinkage potential), e.g. an already shrunk silk polypeptide fiber or yarn, or a fiber or yarn composed of a different material with a lower shrinkage potential than the shrinkable silk polypeptide fiber or yarn. As to the materials used, it is referred to Figures 2 and 3.

[0291] A) Equipment:

[0292] The following equipment was used:

[0293] - twisting machine (for twisting fibers / yarns),

[0294] - water bath or water vapor producing system,

[0295] - warm / hot water (temperature: 40°C to 80°C) ,

[0296] - water vapor (temperature: 85°C and 100°C),

[0297] - weight balance (to measure pre- and post-shrinkage dimensions),

[0298] - ruler or caliper (for measuring yam length),

[0299] - microscope (for observing fiber morphology post-texturization), and

[0300] - humidity-controlled drying chamber or open drying rack.

[0301] B) Procedure 1. Preparation of yarns or yam bundles:

[0302] The fibers / yarns were selected: one with a high shrinkage potential and one with low / no shrinkage potential (see fiber / yarn selection above).

[0303] The fibers / yarns were cut to an equal length (e.g. 20 cm).

[0304] The fibers / yarns were twisted together using a twisting machine to achieve a uniform twist ratio (e.g., between 100 and 300 twists per meter), thereby a yarn or yarn bundle is achieved.

[0305] In this respect, it should be noted that the second fiber or yarn comprising the fiber was twisted around the first shrinkable silk polypeptide fiber or yarn comprising the fiber.

[0306] 2. Baseline Measurement:

[0307] The initial length of the twisted yarn or yam bundle was measured and recorded.

[0308] The twisted yarn or yarn bundle was weighed for reference.

[0309] Micrographs of the untwisted yarn or yarn bundle was captured to record the initial fiber morphology.

[0310] 3. Water Treatment:

[0311] The twisted yarn or yarn bundle was submerged in a beaker containing warm / hot water (temperature: 40°C to 80°C) for 30 seconds.

[0312] Another twisted yam or yam bundle was exposed to water vapor (temperature: 85°C and 100°C) for 30 seconds.

[0313] After this time period, the yam or yarn bundle was removed from the water or the exposure to a water vapour environment was stopped.

[0314] 4. Drying and Final Measurements:

[0315] Excess water was removed from the yarn or yarn bundle. The yarn or yarn bundle was allowed to dry in a humidity-controlled chamber or on an open rack. After drying, the final length of the yam bundle was measured. The yam or yam bundle was weighed to determine mass loss. The drying fixed the texturization.

[0316] 5. Analysis of Texturization:

[0317] A microscope was used to observe and document changes in the fiber morphology, focusing on the formation of crimps, loops, coils, and crinkles. The results were compared to the initial morphology. C) Data Collection:

[0318] Quantitative Data:

[0319] Length reduction percentage after shrinking was determined.

[0320] Weight change (if any) was documented.

[0321] Shrinkage differential between the two fibers was tested.

[0322] D) Qualitative Data:

[0323] Micrographs showing crimp formation were analysed.

[0324] Visual assessment of texturization (degree of crimp / coil) was performed.

[0325] RESULTS:

[0326] In Figure 1, the above described procedure is illustrated. In (A) a first shrinkable silk polypeptide fiber or yarn at a defined length (x) before exposition to warm water (50°C-80°C) or steam is shown. (B) shows a second shrunk silk polypeptide fiber or yarn after exposition to warm water (50°C-80°C) or steam. (C) shows a first shrinkable fiber or yarn (filament bundle (1 - 500 single filaments combined) or a POY (pre-oriented yarn or partially oriented) staple fiber yarn (30 - 500 dtex)) combined with a second shrunk silk polypeptide fiber or yarn (filament bundle (1 - 500 single filaments combined or a staple fiber yam (30 - 500 dtex)). (D) shows a combination of the first shrinkable silk polypeptide fiber or yam and the second shrunk silk polypeptide fiber or yarn twisted together in “Z” or “S” direction with a twist between 50 and 2000 turns / meter. (E) shows the combination of both fibers or yarns (B) after exposition to warm water (50°C-80°C) or steam. The first shrinkable silk polypeptide fiber or yarn contracts and forces the second shrunk silk polypeptide fiber or yam to build loops / undulations (bundle). With the drying of the fiber bundle the form will be fixated (first shrinkable silk polypeptide fiber = FDY, second silk polypeptide fiber = POY).

[0327] The aforementioned experiments showed that the first silk polypeptide yarn or yam bundle (with higher shrinkage potential) contracted more significantly than the second yarn or yarn bundle, causing the second yam or yarn bundle to puff up and form loops, crimps, or coils. The twisted yarn or yarn bundle exhibited noticeable texturization effects upon drying, resulting in a more textured and voluminous yam structure. Diverse yarns were tested and the results are shown in Figures 2 and 3. Figure 2 (A) shows a first shrinkable silk polypeptide fiber multifilament (40 filaments, 95dtex) twisted with a second silk polypeptide fiber multifilament (40 filaments, 95dtex) after exposition of the fiber bundle to warm water (50°C-80°C). Figure 2 (B) shows a two first shrinkable silk polypeptide fiber multifilaments (40 filaments, 95dtex) twisted with a second silk polypeptide fiber multifilament (40 filaments, 95dtex) after exposition of the fiber bundle to warm water (50°C-80°C).

[0328] Figure 3: Shows a first shrunk silk polypeptide fiber twisted together with a second silk polypeptide fiber. la: AMSILK = silk polypeptide fiber twisted together with HT-PET = High Tenacity

[0329] Polyester fiber lb: AMSILK = silk polypeptide fiber twisted together with primed HT-PET = High

[0330] Tenacity Polyester fiber

[0331] 2a: AMSILK = silk polypeptide fiber twisted together with CO = cotton fiber

[0332] 2b: AMSILK = silk polypeptide fiber twisted together with primed CO = cotton fiber

[0333] 3a: AMSILK = silk polypeptide fiber twisted together with LI = linen fiber

[0334] 3b: AMSILK = silk polypeptide fiber twisted together with primed LI = linen fiber

[0335] 4a: AMSILK = silk polypeptide fiber twisted together with SE = silk mulberry fiber

[0336] 4b: AMSILK = silk polypeptide fiber twisted together with primed SE = silk mulberry fiber

[0337] 5a: AMSILK = silk polypeptide fiber twisted together with WO = wool like fiber which can be sheep, Merino sheep, goat like vicunia, alpaca, mohair, or camel like fiber

[0338] 5b: AMSILK = silk polypeptide fiber twisted together with primed WO = wool like fiber which can be sheep, Merino sheep, goat like vicunia, alpaca, mohair, or camel like fiber

Claims

1. CLAIMS1. A method for texturizing a yarn or yam bundle comprising the steps of:(i) providing at least one first shrinkable silk polypeptide fiber or yarn comprising the at least one first fiber,(ii) twisting the at least one first fiber or yam provided in (i) with at least one second fiber or yam comprising the at least one second fiber, thereby obtaining a yarn or yam bundle, and(iii) shrinking the yarn or yam bundle, thereby texturizing the yarn or yam bundle.

2. The method of claim 1, wherein the at least one second fiber or yarn comprising the fiber is twisted around the at least one first shrinkable silk polypeptide fiber or yam comprising the fiber.

3. The method of claims 1 or 2, wherein the twisting is carried out in Z direction (from top right to bottom left) or S direction (from top left to bottom right).

4. The method of any one of claims 1 to 3, wherein the twisting results in between 20 and 1000 twisting turns per metre.

5. The method of claim 4, wherein the twisting results in between 100 and 300 twisting turns per metre.

6. The method of any one of claims 1 to 5, wherein the shrinking is performed by incubating the yarn or yarn bundle in a water bath or by exposing the yarn or yam bundle to water vapor.

7. The method of claim 6, wherein the water bath has a temperature of > 20°C or the water vapor has a temperature of > 80°C.

8. The method of claim 7, wherein the water bath has a temperature of between 40°C and 80°C or the water vapor has a temperature of between 85°C and 110°C.

9. The method of any one of claims 1 to 8, wherein in step (iii) the at least one first silk polypeptide fiber comprised in the yarn or yarn bundle shrinks.

10. The method of claim 9, wherein the at least one first silk polypeptide fiber shrinks by at least 10% with regard to its total length.

11. The method of claim 10, wherein the at least one first silk polypeptide fiber shrinks by at least 30% with regard to its total length.

12. The method of any one of claims 1 to 11, wherein the at least one second fiber or yam comprising the fiber forms, as a result of the shrinkage of the at least one first silk polypeptide fiber or yam comprising the fiber, loops, waves, and / or undulations.

13. The method of any one of claims 1 to 12, wherein the at least one first shrinkable silk polypeptide fiber is a staple fiber or a continuous / endless fiber.

14. The method of any one of claims 1 to 13, wherein the at least one second fiber is a staple fiber or a continuous / endless fiber.

15. The method of any one of claims 1 to 14, wherein the method further comprises step (iv) of drying the yam or yarn bundle.

16. The method of claim 15, wherein the drying is performed in the ambient air, in a hot chamber, or with hot air.

17. The method of any one of claims 1 to 16, wherein the at least one first silk polypeptide fiber is a spider silk polypeptide fiber, preferably a recombinant spider silk polypeptide fiber.

18. The method of any one of claims 1 to 17, wherein the at least one second fiber is a shrunk fiber, a shrinkable fiber, or a non-shrinkable fiber.

19. The method of claim 18, wherein the shrunk fiber is obtained by incubating the fiber or the yarn comprising the fiber in a water bath or by exposing the fiber or the yam comprising the fiber to water vapor.

20. The method of any one of claims 1 to 19, wherein the at least one second fiber is a synthetic fiber, a natural fiber, or a regenerated fiber.

21. The method of claim 20, wherein(a) the synthetic fiber is selected from the group consisting of a plastic fiber, a recombinant polypeptide fiber, a PET fiber, a PA fiber, a PP fiber, and an EA fiber,(b) the natural fiber is selected from the group consisting of a cotton fiber, a flax fiber, a wool fiber, a hemp fiber, a bamboo fiber, a cellulose fiber, and a silk fiber, or(c) the regenerated fiber is selected from the group consisting of a viscose fiber, a modal fiber, and a cupro fiber.

22. The method of claim 21, wherein(ai) the plastic fiber is selected from the group consisting a polyester fiber, an elastane fiber, a polyamide fiber, a polyacrylic fiber, and a polyurethane fiber, or(aii) the recombinant polypeptide fiber is a silk polypeptide fiber.

23. The method of any one of claims 1 to 22, wherein the at least one first yarn is composed of between 2 and 10000 fibers.

24. The method of claim 23, wherein the at least one first yarn is composed of between 2 and 1000 fibers.

25. The method of any one of claims 1 to 24, wherein the at least one second yam is composed of between 2 and 10000 fibers.

26. The method of claim 25, wherein the at least one second yam is composed of between 2 and 1000 fibers.

27. The method of any one of claims 1 to 26, wherein the proportion of the silk polypeptide fiber(s) in the yam or yarn bundle obtained in step (iii) is at least 10%.

28. The method of claim 27, wherein the proportion of the silk polypeptide fiber(s) in the yarn or yam bundle obtained in step (iii) is at least between 20% and 30%, preferably at least between 40% and 50%, and more preferably at least 60% and 70%.

29. The method of claim 28, wherein the yam or yam bundle obtained in step (iii) is entirely composed of silk polypeptide fibers.

30. The method of any one of claims 1 to 29, wherein the ratio of the at least one first silk polypeptide fiber or yam comprising the fiber and the ratio of the at least one second fiber or yarn comprising the fiber in the yarn or yarn bundle obtained in step (iii) is 1 : 1, 1 :2, 1 :3, or 1 :4.

31. A texturized (and shrunk) yam or yarn bundle obtained by the method of any one of claims 1 to 30.

32. A texturized (and shrunk) yarn or yarn bundle comprising at least one first shrunk silk polypeptide fiber or yam comprising the fiber and at least one second fiber or yarn comprising the fiber, wherein the at least one second fiber or yarn comprising the fiber is twisted around the at least one first shrunk silk polypeptide fiber or yarn comprising the fiber.

33. The texturized (and shrunk) yam or yam bundle of claim 32, wherein the twist is between 20 and 1000 twisting turns per metre, preferably between 100 and 300 turns per metre.

34. The texturized (and shrunk) yam or yarn bundle of claims 32 or 33, wherein the at least one second fiber is a shrunk / non-shrinkable fiber.

35. The texturized (and shrunk) yarn or yarn bundle of any one of claims 32 to 34, wherein the at least one second fiber forms loops, waves, and / or undulations in the yarn or yarn bundle.

36. The texturized (and shrunk) yarn or yam bundle of any one of claims 32 to 35, wherein the at least one second fiber is a shrunk silk polypeptide fiber.

37. An article comprising the texturized (and shrunk) yarn or yam bundle of any one of claims 31 to 36.

38. The article of claim 37, wherein the article is a textile.

39. The article of claim 38, wherein the textile is / part of an apparel or a shoe.

40. The article of claim 38, wherein the textile is a technical textile, smart textile, industrial fabric, or a high-performance material.

41. Use of the texturized (and shrunk) yam or yarn bundle of any one of claims 31 to 36 in the textile industry.

42. The use of claim 41, wherein the yarn or yam bundle is used in apparel, footwear, technical textiles, smart textiles, industrial fabrics, or performance materials.

43. Use of the texturized (and shrunk) yam or yam bundle of any one of claims 31 to 36 for the manufacture of a textile.

44. The use of claim 43, wherein the textile is / part of an apparel or a shoe.

45. The use of claim 43, wherein the textile is a technical textile, smart textile, industrial fabric, or a high-performance material.

46. A method for producing a texturized yarn or yarn bundle by creating internal torsional stress and releasing the same through differential shrinkage of at least one first fiber component, thereby forming a texturized yam or yarn bundle microstructure.

47. A yarn or yarn bundle produced by inducing mechanical torsional energy storage followed by shrink-triggered internal reorganization at the fiber scale.

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