DESCRIPTION

The present invention relates to a process of making a yarn, preferably a thin yarn having suitability for weaving features, particularly a yarn having natural animal fibers, vegetable fibers, synthetic polymer fibers, man-made natural fibers, continuous filaments of animal origin and/or discontinuous filaments of animal origin, to be used in a pure state or blended together.

As used herein, the term weaving is generally used both for designating warp-and-weft weaving and knit-weaving .

The invention also relates to a yarn, preferably a thin yarn, made of natural animal fibers, vegetable fibers, synthetic polymer fibers and/or man-made natural fibers, continuous filaments of animal origin and/or discontinuous filaments of animal origin, to be used in a pure state or blended together, obtained with such process. As used herein, for example:

- thin yarns are intended to cover yarns having a yarn count ranging from 40 to 200 Nm, and preferably a yarn count ranging from 65 to 200 Nm;

- animal fibers are intended to cover fleece or hair fibers (such as wool, alpaca, vicuna, cashmere and others) ;

- continuous filaments of animal origin are intended to cover filaments obtained by reeling from whole cocoons (such as silk) ;

- discontinuous filaments of animal origin are intended to cover filaments obtained by unravelling from defective cocoons (such as waste silk) ;

- vegetable fibers are intended to cover all the fibers obtained from plants, shrubs, inflorescences, roots, leaves (such as cotton, flax, hemp, jute, coir, ramie, bamboo, and others);

- synthetic polymer fibers are intended to cover, for example, polyamide, polyester, acrylic, polypropylene fibers, and others;

- man-made natural fibers are intended to cover, for example, rayon viscose, modal, acetate, cupro, tencel® and others.

These yarns of the above mentioned type are known to be difficult to spin and weave, due to their thinness which makes them prone to breaking during spinning or later weaving.

Furthermore, at present the following needs are strongly felt in the field of yarns and weaving:

- enhancing mechanical properties, such as abrasion resistance, of a thin yarn, and reducing mechanical friction between weft yarns and warp yarns, for trouble-free weaving;

- developing an environment-friendly and low- power-consumption process of making a yarn having improved suitability for weaving features;

- developing a process of making a yarn having improved features in terms of high resistance to pilling, felting and rubbing, as well as superior mechanical properties while maintaining the desired softness, volume, brightness and lightness features;

- developing a process of making a yarn having improved dye affinity, or improved affinity for the later finishing steps, such as printing.

The present invention is based on the problem of conceiving and providing a process of making a yarn having suitability for weaving features, which fulfills the above mentioned needs.

This problem is solved by a process of making a yarn having suitability for weaving features as defined in claim 1.

In a further aspect, the invention also relates to the use of a reinforcement product comprising a composition of chitosan and/or derivatives thereof in a process of making a yarn having suitability for weaving features as defined in claim 25.

According to the invention, before the step of spinning, the fibers and/or filaments undergo a step of application of a reinforcement product comprising a composition of chitosan and/or derivatives thereof, and a subsequent step of crosslinking of the chitosan and/or derivatives thereof of said reinforcement product applied to said fibers and/or to said filaments, such that a crosslinked reinforcement polymer permanently anchored to said fibers and/or to said filaments is obtained from said chitosan and/or derivatives thereof.

Chitosan is a natural polymer derived from chitin, which is a protein contained in the exoskeleton of crustaceans, and is a nature-renewable material, since it is obtained from food industry by ^¬ products .

A reinforcement product based on chitosan and/or derivatives thereof, used as a sizing agent for the fibers and/or filaments has better sizing properties than other natural substances. For instance, the addition of 5 to 15% carboxymethyl chitosan concentrations in the sizing step has provided increases in toughness of cotton fabrics by up to 55%, with 3% reduction of elongation.

The core of the invention consists in overcoming a technical prejudice existing in the field of yarns and weaving: i.e. that the chitosan polymer may only be used to impart a temporary effect to the fibers and/or filaments of the yarns, which is designed to disappear after a first washing step or in other finishing steps.

Unlike prior art teachings, the present invention provides crosslinking of chitosan and/or derivatives thereof, to ensure permanent adhesion of chitosan to the fibers and/or filaments, such that the beneficial effects of chitosan may be maintained with time.

The advantage of the step of crosslinking of chitosan and/or derivatives thereof is that the fibers and/or filaments of the yarn are imparted a considerable physical-mechanical resistance, a long- lasting sanitization effect, resisting many repeated washes with hot and/or soapy water, as well as a considerable improvement in the affinity of the fibers and/or filaments.

In a further auxiliary aspect, the technique of crosslinking chitosan and/or its derivatives for application to the fibers and/or filaments of the yarn before weaving is used against the prejudice existing in the field of yarns and weaving, particularly for valuable yarns/fabrics such as cashmere or silk: i.e. that crosslinking of chitosan causes an undesired structural stiffening on the surface of the fibers and/or filaments of the yarns, which is unacceptable for valuable yarns/fabrics.

Conversely, according to a further auxiliary aspect of the present invention, the fibers and filaments of the treated yarns are coated with a thin layer of reinforcement product, which is first crosslinked and then, if needed, mostly removed in a partial and calibrated manner, the rest of the crosslinked chitosan and/or derivatives thereof applied to the fibers and/or filaments maintaining its beneficial effects, as mentioned above.

The process of making a yarn having suitability for weaving features, according to the invention comprises the steps of:

- providing natural animal fibers, vegetable fibers, synthetic polymer fibers and/or man-made natural fibers, continuous filaments of animal origin and/or discontinuous filaments of animal origin, to be used in a pure state or blended together;

- performing one or more processing operations on said fibers and/or said filaments for preparing them to spinning, selected from the group comprising: washing, drying, blending, cleaning, opening, reeling, unravelling, carding, combing, parallelization of fibers and/or filaments, web formation, stretching/thinning, rove formation and/or dyeing and

- spinning said fibers and/or said filaments once one or more of said processing operations have been performed on said fibers and/or said filaments for preparing them to spinning, to obtain a yarn.

Advantageously, the process is characterized in that it comprises:

- a step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments, said step of applying said reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments being carried out before spinning said fibers and/or said filaments, and - performing a subsequent step of crosslinking of the chitosan and/or derivatives thereof of said reinforcement product applied to said fibers and/or to said filaments, such that a crosslinked reinforcement polymer is obtained from said chitosan and/or derivatives thereof, which is permanently anchored to said fibers and/or to said filaments.

Preferably, said step of crosslinking of the chitosan and/or derivatives thereof of said reinforcement product applied to said fibers and/or to said filaments, is carried out before the step of spinning of said fibers and/or said filaments.

Alternatively, said step of crosslinking of the chitosan and/or derivatives thereof of said reinforcement product applied to said fibers and/or to said filaments, may be carried out after the step of spinning of said fibers and/or said filaments.

Preferably, in order to facilitate the subsequent step of crosslinking of the chitosan and/or derivatives thereof, after said step of application of a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments, a drying step is provided, for drying said fibers and/or said filaments as well as said reinforcement product, before crosslinking the chitosan and/or derivatives thereof of said reinforcement product applied to said fibers and/or to said filaments.

Preferably, said step of crosslinking of the chitosan and/or derivatives thereof of said reinforcement product applied to said fibers and/or to said filaments before the step of spinning the fibers, is carried out by a step of UV exposure of said chitosan and/or derivatives thereof.

Preferably, the process of the invention comprises a step of partial and calibrated removal of the crosslinked reinforcement polymer from said fibers and/or said filaments, which is carried out before the step of spinning of said fibers and/or said filaments.

Alternatively, said partial and calibrated removal of said crosslinked reinforcement polymer from said fibers and/or said filaments may be carried out after or at the same time as the spinning step.

Preferably, said step of partial and calibrated removal of said crosslinked reinforcement polymer from said fibers and/or said filaments is carried out by a hydrolyzing desizing step, and more preferably by immersion in a hydrolyzing desizing solution.

Such hydrolyzing desizing solution: - provides enzymatic desizing or

- provides chemical desizing, using hydrolyzing acids .

Preferably, said partial and calibrated desizing step, which does not involve complete removal of the crosslinked polymer applied on the fibers, is at least partially carried out by mechanical desizing, whereby the fibers to be desized are physically acted upon by abrasion, rubbing, brushing and/or by treatments adapted to remove part of the crosslinked chitosan and/or chitosan-derived polymer from the fibers, such as by ultrasonic treatment.

Such mechanical abrasion and/or rubbing treatment for partial and calibrated removal of the crosslinked chitosan and/or chitosan-derived polymer may be carried out on the yarn during weaving, e.g. by sliding the yarn in contact with special rigid surfaces. These rigid surfaces may consist of the surfaces of the teeth of the weaving comb, eyelets through which the yarn is slid during weaving, surfaces of rollers contacted by the sliding yarn during the weaving step, bristles of a brush, and others .

These mechanical abrasion and/or rubbing treatments may be carried out on yarn fibers even after the weaving or knitting step, i.e. by directly acting upon the finished fabric or knit. In this case, these mechanical treatments are advantageously carried out by brushing the fabric or the knit.

According to an alternative embodiment, the partial and calibrated mechanical desizing step for removing the crosslinked chitosan and/or chitosan- derived polymer from the fibers may be carried out by ultrasonic treatment of such fibers. Conveniently this may take place, for example, with the fibers immersed in a liquid in which an ultrasound-emitting probe is introduced.

Advantageously, the ultrasonic treatment of the fibers may be carried out at the same time as a step of weaving or finishing during which the fibers are already immersed in a bath, for example during a fiber washing or a fiber dyeing step before weaving of the yarn or the fabric or knit.

The possibility of performing partial and calibrated mechanical desizing of the crosslinked polymer on the fibers does not exclude the possibility that such step may be carried out before or after, and in addition to a partial and calibrated chemical or enzymatic desizing step.

A partial and calibrated desizing step using ultrasounds may be carried out at the same time as a chemical or enzymatic desizing step, using the same bath, which will afford a synergy of effects between the different desizing steps.

Preferably, the above mentioned step of partial and calibrated removal of said crosslinked reinforcement polymer from said fibers and/or said filaments will leave said crosslinked chitosan- derived reinforcement polymer on said fibers and/or said filaments, in an amount of 0.1-9% w/w based on the dry weight of said fibers and/or said filaments after said crosslinking step.

The above mentioned step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be carried out using various methods, such as: foularding, spraying, dipping, aerosol, atomization and/or at least partial coating of the fibers and/or the filaments.

Preferably, the composition of chitosan and/or derivatives thereof is a solution comprising:

- chitosan, preferably of low molecular weight, more preferably of 150,000 Da, degree of deacetylation 75-85%; viscosity 20-200 cps at a concentration range of 0.5-10% w/v, preferably 0.8-3% w/v, more preferably 1% w/v;

- acid aqueous solution and

- radical photoinitiator .

Preferably, said acid aqueous solution comprises acetic acid at a concentration of 1.5-3.8% v/v, preferably at a concentration of 1.8-2.22% v/v, more preferably at a concentration of 2% v/v.

Such solution may be prepared through the steps of:

- dissolving the chitosan of low molecular weight in an acid aqueous solution of acetic acid,

- adding the photoinitiator in an amount of 1.4- 4% w/w based on the dry weight of chitosan, preferably 1.8-2.2% w/w based on the dry weight of chitosan, more preferably 2% w/w based on the dry weight of chitosan, and

- stirring the solution, preferably by magnetic stirring .

If the above mentioned step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments is carried out by dipping the latter into a bath of said composition, there will be preferably a bath ratio ranging from 1-7 to 1-35, more preferably a bath ratio ranging from 1-10 to 1-30, most preferably a bath ratio ranging from 1- 16 to 1-24.

According to different embodiments of the process of the invention:

- if the above mentioned processing steps for preparation to weaving comprise a washing step, then said step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be advantageously carried out during said washing step;

- if the above mentioned processing steps for preparation to weaving comprise a blending step in a blending chamber, then said step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be carried out in said blending chamber during said blending step;

- if the above mentioned processing steps for preparation to weaving comprise a carding step, then said step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be carried out on the carded fibers and/or filaments, preferably immediately after the carding step;

- if the above mentioned processing steps for preparation to weaving comprise a combing step, then said step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be carried out on the combed fibers and/or filaments, preferably immediately after the combing step;

- if the above mentioned processing steps for preparation to weaving comprise a step for preparation of a tuft, a top, a web, a ribbon and/or a roving, then said step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be carried out on said tuft, said top, said web, said ribbon or said roving, or

- if the above mentioned processing steps for preparation to weaving comprise a dyeing step, then said step of applying a reinforcement product comprising a composition of chitosan and/or derivatives thereof to said fibers and/or to said filaments may be carried out on said fibers and/or said filaments before said dyeing step.

A yarn made of natural animal fibers, vegetable fibers, synthetic polymer fibers and/or man-made natural fibers, continuous filaments of animal origin and/or discontinuous filaments of animal origin, to be used in a pure state or blended together, which may be obtained with a process according to the present invention, comprises a crosslinked reinforcement chitosan and/or chitosan-derived polymer, which is applied to said fibers and/or to said filaments.

Preferably, such yarn has a count ranging from 40 Nm to 200 Nm, preferably from 65 Nm to 200 Nm.

In the light of the above disclosure, the process of the invention as described above, and the yarn that can be obtained with such process, can fulfill the needs addressed herein.

The above disclosure is susceptible to a number of changes and variants within the inventive concept, as outlined by the annexed claims.