ITMI20132090A1 - PROCEDURE FOR THE PRODUCTION OF A YARN WITH CHARACTERISTICS OF FITNESS FOR WEAVING AND ITS RELATED PROCESS OF WEAVING SUCH YARN - Google Patents

Description

DESCRIPTION

The present invention refers to a process for the production of a yarn with characteristics of suitability for weaving, specifically a thin yarn of natural animal fibers, vegetable fibers, synthetic polymeric fibers, natural polymer techno-fibers, continuous filaments of origin animal and / or discontinuous filaments of animal origin used in pure or blended form.

According to a further aspect, the present invention also refers to a weaving process of the aforesaid yarn for making a fabric.

In the context of the present invention, the term weaving is generically used both to distinguish warp and weft weaving and to distinguish weaving for knitwear.

In the context of this description, by way of example:

- for thin yarns we mean yarns in which the value of the yarn count measured in Nm takes on a value of the order of 70 or more, with the specification that as the number of Nm increases, the yarn becomes increasingly thinner;

- by animal fibers we mean fleece or horsehair fibers (for example wool, alpaca, vicunia, cashmere and others);

- by continuous filaments of animal origin we mean filaments obtained by reeling from intact cocoons (for example silk);

- discontinuous filaments of animal origin are intended for example filaments obtained by fraying from non-intact cocoons (for example silk waste);

- by vegetable fibers we mean all the fibers obtained from plants, shrubs, florescences, roots, leaves (for example cotton, linen, hemp, jute, coconut, ramie, bamboo, and others);

- by synthetic polymeric fibers we mean, for example, polyamide, polyester, acrylic, polypropylene fibers and others;

- for natural polymer techno-fibers we mean, for example, viscose rayon, modal, acetate, cupro, tencel, and others.

The difficulty of spinning and weaving thin yarns of the type identified above is known which, precisely because of their high thinness, tend to break during spinning or subsequent weaving.

Furthermore, it should be noted that in the field of yarns and weaving the following needs are nowadays strongly felt:

- enhance the mechanical properties such as the abrasion resistance of a thin yarn and reduce the mechanical friction between the weft yarn and the warp yarn in order to allow weaving without any kind of problem;

- to develop an ecological and low energy consumption process for the production of a yarn with increased characteristics of suitability for weaving;

- to develop a process for the production of a yarn with improved characteristics of high resistance to pilling, felting and rubbing, as well as high mechanical properties, while maintaining the desired characteristics of softness, bulkiness, brilliance and lightness;

- developing a process for the production of a yarn having an improved dyeing affinity or for subsequent finishing stages such as printing.

In order to increase the characteristics of suitability for weaving of the yarns, in other words to give the yarns the necessary tensile strength to be able to be loomed, it has been known for more than a decade to produce yarns comprising an intimate blend of fine fibers and of water-soluble synthetic fibers, for example Polyvinyl Alcohol (PVA) fibers, the resulting yarns having an increased tensile strength due to the presence of the water-soluble synthetic fibers. However, it should be noted that the weaving of very thin yarns, such as yarns having a count value greater than or equal to Nm 70, for example yarns having a fineness value of the order of Nm 95, spinability is still very problematic.

The prior document EP 050845 teaches to carry out a subsequent step in which the yarns comprising an intimate blend of quality fibers and water-soluble synthetic fibers are further coupled and twisted with yarns of water-soluble fibers, specifically PVA.

With reference to EP 050845, however, it should be considered that although the process envisaged therein allows to arrive at a final yarn, twined and twisted, having a torsional tensile strength more than sufficient to be able to be loomed, it is not exempt. d problems, among which are highlighted:

- the use of an extremely high quantity of PVA for each kilo of quality fibers used, in this regard the negative aspects deriving from the use of PVA should be remembered, not only for the increase in production costs, but also and above all for the difficulties in removing the PVA from the final fabric and the need to dispose of the bath containing the PVA removed from the fibers;

- the twist of at least 200 turns per linear meter applied after the aforementioned doubling phase changes the number of final twisting turns detectable in the yarns of the fabric obtained, since this doubling twist is added to or algebraically subtracted from the initial twisting of the yarn depending on whether it is a concordant twist (Z-Z or S-S) or a discordant twist (Z-S or S-Z). In this regard, it is only necessary to point out that, in a yarn of thin fibers, an increase or decrease in torsion of the order of 200 revolutions per linear meter involves the production of very different fabrics, the difference being detectable even at a visual examination of the tissues;

- the doubling with PVA yarns and the subsequent removal of the fabric produced from the weave, by dissolving in a liquid bath, entails the possibility of being able to produce only fabrics with a low number of yarns per centimeter, since the PVA yarns after their dissolution in liquid from the weave of the fabric leaves gaps between the remaining yarns made up of only fine fibers.

The problem underlying the present invention is to devise and make available a process for the production of a thin yarn, natural animal fibers, vegetable fibers, synthetic polymeric fibers, natural polymer techno-fibers, continuous filaments of origin animal and / or discontinuous filaments of animal origin used in pure or in blends with each other, with increased characteristics of suitability for weaving, which satisfies the aforementioned requirements while avoiding the drawbacks highlighted above with reference to the known art.

This problem is solved by a process in accordance with claim 1 to increase the characteristics of suitability for weaving of a thin yarn of natural animal fibers, of vegetable fibers, of synthetic polymeric fibers, of techno-fibers of natural polymer, of continuous filaments of origin animal and / or discontinuous filaments of animal origin used in pure or blended form.

According to a further aspect, the invention also relates to a weaving process of the aforementioned yarn for the production of a fabric in accordance with claim 14.

The process according to the invention for the production of a yarn with characteristics of suitability for weaving, including the steps of:

- prepare raw fibers comprising natural animal fibers, vegetable fibers, synthetic polymeric fibers, natural polymer techno-fibers, continuous filaments of animal origin and / or discontinuous filaments of animal origin to be used in pure or blended form;

- prepare water-soluble synthetic fibers;

- spinning a fine yarn formed by an intimate blend of the aforementioned first fibers and the aforementioned water-soluble synthetic fibers.

Advantageously, the process is characterized in that it comprises a sizing step of the aforesaid fine yarn by means of a sizing solution, to obtain a sizing fine yarn having an increased tensile strength with respect to the tensile strength of the starting fine yarn.

Preferably the value of the count of the fine yarn is of the order of Nm 70 or higher.

More preferably, the count value of the fine yarn is greater than or equal to Nm 90.

Preferably, the aforesaid first fibers substantially consist of pure cashmere or cashmere and silk.

Preferably, the aforementioned water-soluble synthetic fibers substantially consist of Polyvinyl Alcohol (PVA) fibers.

Preferably the aforementioned sizing step of the aforesaid fine yarn is carried out by means of a sizing solution comprising a composition of chitosan and / or its derivatives.

Preferably, during sizing, the temperature of the sizing solution is maintained at a temperature higher than 60 ° C and lower than the boiling temperature, for example a temperature in the range between 60 ° C and 90 ° C, more preferably a temperature of the order of 70 ° C.

By way of example only, the size composition used can comprise natural substances and their derivatives, such as for example:

- starch and starch derivatives (natural starch and chemically modified starch products);

- cellulosic derivatives (carboxymethylcellulose (CMC);

- based on proteins (glue, gelatin, albumin).

Alternatively, a synthetic size can be used comprising one or more of the following components:

- polyacrylates;

- modified polyesters;

- polyvinyl alcohols (PVA);

- copolymers of styrene / maleic acid.

Additives such as surfactants, solvents, defoamers, etc. they can then be added in the size formulation according to the specific needs to be met for each type of fine yarn.

The size solution is prepared by performing a hot mixing of its components, in order to achieve an optimal mixing of the components. Generally, at the preparation / mixing temperature of the size it is higher than 60 ° C and it is kept below the boiling temperature of the solution, in order not to degrade one or more components of the size due to boiling. Preferably, the temperature range at which the mixing of the components of the size takes place is between 60 ° C and 92 ° C, more preferably this temperature range is greater than or equal to 70 ° C and less than 90 ° C.

It should be noted that it is also possible to provide a size solution comprising both synthetic substances and natural substances and their derivatives.

By way of example only, a size solution comprising Polyvinyl Alcohol (PVA) is the following:

- 220 liters of water;

- Kg 25 Polyvinyl alcohol with low viscosity; - 25 kg acrylic resin;

- Kg 12.5 CMS carboxymethylfecule;

- Kg 1 fat composed of fatty acids e

- 8 liters softener

It should be noted that the presence of Polyvinyl Alcohol allows to greatly increase the tensile strength of the yarns, without giving rise to the problems referred to with reference to the doubling of the fine yarn with a PVA yarn and to the dissolution of the PVA yarn from weave of the finished fabric.

In accordance with the preferred embodiment considered above, the size solution used can advantageously comprise chitosan and / or its derivatives.

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

The reinforcing product based on chitosan and / or its derivatives used as sizing of fibers and / or filaments has sizing properties superior to many other natural substances. For example, increases in the toughness of cotton fabrics up to 55% have been obtained by adding concentrations of carboxymethylchitosan from 5 to 15% in the sizing step.

Preferably the aforementioned size containing chitosan comprises:

- chitosan and / or its derivatives, preferably chitosan with a low molecular weight, more preferably chitosan having a molecular weight equal to 150,000 Da, with a degree of deacetylation 75-85%; viscosity of 20-200 cps in a concentration of 0.5-10% w / v, preferably 0.8-3% w / v, more preferably 1% w / v;

- an acidic aqueous solution e

- a radical photoinitiator.

The aforementioned acidic aqueous solution preferably comprises acetic acid in a concentration of 1.5-3.8% v / v, preferably in a concentration of 1.8-2.22% v / v, more preferably in a concentration of 2% v / v.

If the above step of applying to the fibers of the fine yarn a reinforcing product comprising a composition of chitosan and / or its derivatives is carried out by immersion in a bath of said composition, it is preferable to provide a bath ratio comprised between 1-7 and 1- 35, more preferably a bath ratio comprised between 1-10 and 1-30, even more preferably a bath ratio comprised between 1-16 and 1-24.

In accordance with a preferred and advantageous embodiment of the process according to the invention, this process provides for a step of crosslinking at least a part of the chitosan and / or its derivatives of the size applied to the fibers of the fine yarn after sizing, so as to obtain a reinforcing cross-linked polymer permanently anchored to the fibers of the fine yarn itself.

The aforementioned cross-linking of at least one part of the chitosan and / or its derivatives of the size applied to the fibers of the fine yarn is carried out overcoming a technical prejudice present in the yarn and weaving sector: the chitosan polymer can only be used to give the fibers and / or to the filaments of the yarns a temporary effect which vanishes following a first washing or in other finishing stages.

Contrary to this technical prejudice, the crosslinking of chitosan and / or its derivatives on the fibers of the fine yarn ensures permanent adhesion of the polymer derived from chitosan and / or its components, ensuring the lasting beneficial effects due to the presence of chitosan over time. .

The cross-linking of chitosan and / or its derivatives gives the fibers of the fine yarn a considerable physical and mechanical resistance, a sanitizing and long-lasting effect that is resistant even after numerous and subsequent washes with hot and / or soapy water, as well as a significant improvement in the affinity to finishing, for example the dyeing affinity, of the fibers of the fine yarn.

The cross-linking technique of chitosan and / or its derivatives applied to the fibers of the fine yarn is carried out before the weaving of the fine yarn itself, overcoming a widespread prejudice in the sector of fine yarns, such as cashmere or silk, according to which the crosslinking of the chitosan involves an excessive undesired structural stiffening of the yarns not suitable for the production of quality fabrics which must be soft.

Contrary to this prejudice, in accordance with a further secondary aspect of the present invention, a veil of reinforcing product is created on the fibers and filaments of the treated yarns which can be at least partially cross-linked, and where necessary, partially removed in a partial and calibrated. The part of cross-linked chitosan and / or its derivatives remaining on the fibers of the fine yarn, differently, continues to carry out over time the beneficial effects previously highlighted due to the presence of the chitosan.

Preferably, the aforementioned step of crosslinking at least a part of the chitosan and / or its derivatives of the size applied to the fibers of the fine yarn is preceded by a step of drying the fibers of the fine yarn and of the size applied to it, so as to favor crosslinking. of chitosan and / or its derivatives.

Preferably the crosslinking of the chitosan and / or its derivatives of the size applied to the fibers of the fine yarn is carried out by means of a step of exposure to ultraviolet rays of the chitosan and / or its derivatives of the size applied to the fibers of the fine yarn.

Preferably, the aforementioned partial and calibrated removal step of the aforementioned reinforcing cross-linked polymer from the fibers of the fine yarn is carried out in such a way as to leave on the fibers of the fine yarn at least a quantity of the aforementioned reinforcing cross-linked polymer obtained from chitosan and / or its derivatives equal to 0.1-9% w / w of the dry weight of the fibers.

Preferably, the aforesaid step of partial and calibrated removal from the fibers of the fine yarn of the reinforcing cross-linked polymer is carried out with a hydrolyzing desizing solution, for example by immersion in this desizing solution. This desizing phase:

- is an enzymatic desizing, preferably with protease, amylase and / or cellulase enzymes or

- it is a chemical desizing carried out with hydrolyzing acids, preferably hydrochloric and / or hydrogen sulphide diluted in a concentration of 3-10% v / v, more preferably 5-7% v / v.

As possible examples of sizing solutions comprising chitosan the following three composition examples can be considered:

EXAMPLE 1 of sizing with chitosan

- cold water 192 liters

- chitosan Kg 10

- acetic acid 10 l

- starch 17 kg

- fat kg 0,8

- softener 6.7 liters

EXAMPLE 2 of sizing with chitosan

- cold water 192 liters

- chitosan 11.5 kg

- acetic acid 11.5 kg

- starch kg 15

- fat kg 0,8

- softener 6.7 liters

EXAMPLE 3 of sizing with chitosan

- cold water 155 liters

- chitosan Kg 3

- ac. citric Kg 8

- catalyst

6 kg

(NaH2PO4)

with the clarification that size compositions of the type indicated in examples 1 and 2 are particularly suitable for cashmere fibers, wools and the like, while the composition referred to in example 3 is more suitable for fibers such as cotton and the like.

Obviously, the choice of the specific size composition to be used can be made according to the specific fibers of the fine yarn to be sized.

In this regard, it is highlighted how it is possible to provide a composition of size comprising both chitosan and polyvinyl alcohol (PVA).

As regards possible examples of possible fine yarns in an intimate blend to be sized, by way of example only, it is possible to consider the following yarns:

- single-ply yarn having a count of Nm 70 comprising said first fibers in a 50% intimate blend with water-soluble synthetic fibers;

- single-ply yarn having a count of Nm 80 comprising said first fibers in a 50% intimate blend with water-soluble synthetic fibers;

- single-ply yarn having a count of Nm 90 comprising said first fibers in a 50% intimate blend with water-soluble synthetic fibers;

- single-ply yarn having a count of 95 Nm comprising said first fibers in a 50% intimate blend with water-soluble synthetic fibers;

- single-ply yarn having a count of Nm 100 comprising said first fibers in a 50% intimate blend with water-soluble synthetic fibers;

- single-ply yarn having a 110 Nm count, comprising said first fibers in an intimate blend at 50% with water-soluble synthetic fibers;

- single-ply yarn having a 120 Nm count, comprising said first fibers in a 50% intimate blend with water-soluble synthetic fibers.

It should be noted that the percentage of first fibers can vary with respect to the 50% indicated above, being able to vary between 30% and 80% of the total fibers of the fine yarn, preferably varying between 35% and 70% of the fibers overall of the fine yarn.

Furthermore, while respecting the quantities of first fibers and water-soluble fibers indicated above, it is possible to provide fine yarns with two, three or more plies, such as: a fine yarn Nm 2/90 (i.e. a yarn up to two plies, or threads, with a count equal to Nm 90) or a fine yarn Nm 3/90 (i.e. a yarn up to three plies, or threads, with a count equal to Nm 90).

Starting from sized fine yarns of the type considered above, the process for making a fabric of fine yarns includes the following steps:

- a phase of weaving fine sized yarns of the type considered above e

- a subsequent step of dissolution in aqueous solution of the water-soluble synthetic fibers contained in the yarns of said plurality of fine sized yarns of the fabric,

so as to obtain a fabric formed only by the first fibers present in said fine yarns subjected to a weaving operation.

In the aforementioned weaving phase, the fine yarns in intimate and sized blends used can also be of different types. Not only is it possible to provide different weft and warp fine threads, but it is also possible to provide different weft fine threads and / or warp fine threads different from each other according to the specific type of fabric to be made.

The aforesaid process for manufacturing a fabric considered above preferably comprises a step of desizing from the fibers of said fabric of the sizing solution applied to the fibers of the fine sized yarns.

This desizing phase can take place before, after or during the eventual calibrated partial removal of a part of the cross-linked chitosan applied to the fibers of the thin yarns after any crosslinking, provided that there is a need to remove a part of it.

The dissolution of the Polyvinyl Alcohol (PVA) present in an intimate blend in the fine yarns of the fabric can conveniently be carried out by immersing the fabric itself in a slightly acid water-soluble aqueous solution (indicatively with pH values between 4 and about 6) at a suitable temperature , indicatively comprised in the interval between 30 ° C or more degrees centigrade. Preferably the bath temperature must be between 50 ° C and 70 ° centigrade in consideration of the fact that:

- at temperatures that are too low (for example 1520 ° C) it is difficult if not impossible to obtain complete dissolution of the PVA fibers, while - at temperatures of 85-90 ° C or more there is a risk of deteriorating the aforementioned first fibers of the fabric ( for example in the case of cashmere or wool fibers).

In consideration of the foregoing, it is clear that the process described above according to the invention, as well as the yarn obtainable with this process, allows to meet the needs referred to.

In fact, the sizing phase of the fine yarn in an intimate blend allows such yarn to be woven without problems of yarn breakage, while avoiding having to resort to doubling the fine yarn in an intimate blend with another PVA yarn which, as mentioned , is completely unwanted.

Furthermore, it should be pointed out that in the fabrics made with the process according to the invention considered above, the presence of the chitosan present on the fibers allows to confer qualities of dimensional stability and resistance to pilling of the fibers of the fabric such as to make it no longer necessary to perform it on the fibers. of the fabrics produced by anti-pilling procedures and / or procedures to confer dimensional suitability, thereby avoiding having to carry out treatment and / or finishing procedures which, in addition to being expensive, involve the use of harmful substances, whose residues of processing require to be disposed of as special waste.

The above described is susceptible of numerous modifications and variations, all falling within the scope of the inventive concept identified by the following claims.

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Claims (15)

CLAIMS 1. Process for the production of a yarn with characteristics of suitability for weaving, comprising the steps of: - prepare raw fibers comprising natural animal fibers, vegetable fibers, synthetic polymeric fibers, natural polymer techno-fibers, continuous filaments of animal origin and / or discontinuous filaments of animal origin to be used pure or in blends with each other; - prepare water-soluble synthetic fibers; - spinning a fine yarn formed by an intimate blend of said first fibers and said water-soluble synthetic fibers, characterized in that it comprises a sizing step of said fine yarn by means of a sizing solution to obtain a sizing fine yarn having an increased tensile strength with respect to the tensile strength of the starting fine yarn. 2. Process for the production of a yarn in accordance with claim 1, in which the value of the count of said fine yarn is of the order of 70 Nm or greater. 3. Process for producing a yarn according to claim 1 or 2, wherein the count value of said fine yarn is greater than or equal to Nm 90. 4. Process for the production of a yarn according to the claim according to any one of the claims 1 to 3, wherein said first fibers are substantially constituted by pure cashmere or by cashmere and silk. 5. Process for the production of a yarn according to any one of claims 1 to 4, wherein said water-soluble synthetic fibers are substantially constituted by polyvinyl alcohol (PVA) fibers. 6. Process for the production of a yarn according to any one of claims 1 to 5, wherein said sizing step of said fine yarn is carried out by means of a sizing solution comprising a composition of chitosan and / or its derivatives. 7. Process for the production of a yarn according to claim 6, wherein said size solution comprises: - chitosan, preferably chitosan with a low molecular weight, more preferably chitosan having a molecular weight equal to 150,000 Da, with a degree of deacetylation 75-85%; viscosity of 20-200 cps in a concentration of 0.5-10% w / v, preferably 0.8-3% w / v, more preferably 1% w / v; - acid aqueous solution e - radical photoinitiator. 8. Process for the production of a yarn according to claim 7, wherein said acidic aqueous solution comprises acetic acid in a concentration of 1.5-3.8% v / v, preferably in a concentration of 1.8-2.22% v / v, more preferably in a concentration of 2% v / v. 9. Process for the production of a yarn according to any one of claims 6 to 8, comprising a step of crosslinking at least a part of the chitosan and / or its derivatives of said size applied by sizing to the fibers of said fine yarn , to obtain a reinforcing cross-linked polymer permanently anchored to the fibers of said fine yarn. 10. Process for the production of a yarn according to claim 9, in which said step of crosslinking at least a part of the chitosan and / or its derivatives of said size applied to the fibers of said fine yarn is preceded by a step of drying of said fibers and / or of said fine yarn and of the size applied to the fibers of said fine yarn. 11. Process for the production of a yarn according to claim 9 or 10, wherein said step of crosslinking at least a part of the chitosan and / or its derivatives of said size applied to the fibers of said fine yarn is carried out by means of a step of exposure to ultraviolet rays of chitosan and / or its derivatives of said size applied to the fibers of said fine yarn. 12. A process for the production of a yarn according to any one of claims 9 to 11, comprising a step of partial and calibrated removal of said reinforcing cross-linked polymer from said fibers of said fine yarn, to leave on said fibers of said fine yarn an amount of said reinforcing cross-linked polymer obtained from chitosan and / or its derivatives equal to 0.1-9% w / w of the dry weight of said fibers. 13. A process for producing a yarn according to any one of claims 1 to 12, wherein said size solution comprises low viscosity polyvinyl alcohol. 14. Process for making a fabric characterized by comprising: - a weaving step comprising the use of a plurality of fine sized yarns in accordance with any of claims 1 to 13 and - a subsequent step of dissolution in aqueous solution of the water-soluble synthetic fibers contained in the yarns of said plurality of fine sized yarns of the fabric. 15. Process for making a fabric according to claim 14, comprising a desizing step from the fibers of said fabric of the sizing solution contained in the yarns of said plurality of fine sized yarns.