FR2769646A1 - Production of modified wool with reduced felting - Google Patents

Abstract

A modified animal protein fibre especially wool from which surface scales have been removed, without damaging the cortex, to leave a surface comprising residual scales and the imprints of removed scales is new. Also claimed is a process for removing scales from an animal protein fibre, in which the keratin cement layer that binds the scales (cuticle) to the cortex is weakened or destroyed. Also claimed are textile articles made from such a fibre.

Description

 The present invention relates to the technical sector of spinning and the manufacture of textile products from natural fibers of animal origin, and more particularly, but not limited to, the technical sector of the preparation and spinning of wool , and the manufacture of woolen textile products and articles.

 We know that wool consists of a protein fiber, mainly keratin (amino acids).

We also know that wool fiber is mainly composed of the cortex, which is covered by scales. The scales or cuticles are essentially composed of three layers, the epicuticle, the exocuticle and the endocuticle (from the outside of the fiber to the cortex). The cuticle is fixed to the cortex by a keratin cement.

 The industry has developed numerous efforts for decades to improve the properties of textile fibers of animal origin, and in particular wool (in what follows, the term n wool will be used in this general and non-limiting sense, for example more specifically, the industry is committed to improving the properties of wool with regard, above all, to felting resistance. Efforts have also been made to improve dyeing characteristics, pilling resistance, whiteness and the like.

 First of all, from around 1930, animal or vegetable enzymes such as trypsin or papain were used. More recently, techniques have been used for chlorination or treatment with chemicals having the same oxidizing function such as hydrogen peroxide or a "wolframate", or a bisulfite, which for the most part have serious drawbacks for the environment.

Mechanical treatments by ultrasound are also known, or surface treatments by discharge.
Corona, possibly in combination with treatments with resins or polymers aimed at smoothing the surface of the fiber. The techniques comprising a biochemical stage have moreover been developed, in the general sense of an "enzymatic filing of the scales, according to which the cuticle is destroyed by a powerful and long enzymatic treatment, generally 1 or 2 to 6 hrs. times of the order of tens of minutes are sometimes mentioned, but these times are not applicable (or not with good results and have never been used in industry.

Furthermore, an oxidizing treatment often precedes the enzymatic treatment, which does not represent a satisfactory formula. The common objective of these techniques is mainly to fight against the felting of the fiber, which occurs by hooking the fibers together by their protruding scales.

Logically, we therefore sought to eliminate the main factor of the felting, that is to say the scales, and / or to mask the residual roughness by a surface treatment with a resin.

 Patent WO / 89 I 03909 (Schoeller) describes a process comprising a light chlorination and a treatment with Bacillus subtillis, at pH 5 and at 40 OC, for approximately 60 minutes.

 The product "Bactosol" (Sandoz brand) allows an "enzymatic filing" of the wool. The chlorination treatment is suppressed, but the filing damages the cortex. Such an alteration of the cortex is shown in Figures 6 (beginning) and 7 (fiber burst).

 WO 96 t 19611 (Novo Nordisk) describes a process applicable on combed wool ribbons or "tops" or possibly on individual fibers called "loose". According to this process, a Delhey type treatment is carried out (hydrogen peroxide or "wolframate") ") or plasma, associated with a proteolytic treatment. The enzyme treatment times are of the order of 45 to 120 minutes.

 A general problem of the prior art, in addition to the serious implications of certain processes on the environment, in particular those using chlorine, is that the fibers are too little or too little free of scales and that the processes are very long. If the fiber is too little smoothed, a significant feurability remains, and it is necessary to try to remedy it for example by an additional step, therefore problematic and expensive, which consists in applying resin on the fiber so as to cover the scales. If the fiber is treated too powerfully, the cortex is attacked.

On the other hand, the prior art does not allow satisfactory removal of the scales, except taking the risk of an overly powerful treatment which will damage the cortex.

 There is therefore an important need for a process which, starting from the observation that the scales must be removed - to an extent to be determined would lead to an improved product while presenting less disadvantages than the previous processes.

 The problem with which the invention is attacked is therefore the improvement of the treatments of such fibers, in particular wool, in order to improve the properties, mainly the softness and the resistance to felting.

 The invention provides a method comprising a general concept, a biochemical aspect and a mechanical aspect, which is based on a radically new approach to treatment, and leads to a fiber of a new type. Also surprisingly, the new product obtained has properties such that the entire chain for preparing natural material and its spinning is improved and facilitated on an industrial level, which represents another decisive advantage.

Other characteristics and advantages of the invention will be better understood on reading the description which follows, and with reference to the attached drawing, in which
- Figure 1 shows in longitudinal section a wool fiber, and shows the cuticle, cortex and bonding cement.

 - Figure 8 shows a cross section of wool fiber, showing the external cuticles, the central cortex and the bonding cement.

 - Figure 2, which consists of Figures 2a, 2b, 2c and 2d, schematically shows a preferred embodiment of the method according to the invention.

 - Figure 3 shows a comparison between a section of wool fiber treated according to the invention (Figure 3 b) and a section of identical fiber, treated identically except that its treatment does not include a step of opening scales (Figure 3 a), at 2000 magnification.

 - Figure 4 shows a comparison between a section of wool fiber with open scales by the method according to the invention (Figure 4 b) and the same fiber with the closed scales (Figure 4 a).

 - Figure 5 shows a view of a section of a new wool fiber according to the invention, at 3500 magnification, showing the trace left by the imprints of the scales which have been detached.

 - Figure 6 shows the beginning of alteration of a section of the wool fiber, with attack of the cortex.

 - Figure 7 shows the end of the alteration of a section of the wool fiber, with bursting of the fiber.

 - Figure 9 shows a section of wool fiber undergoing flaking according to the invention (during flaking).

 - Figure 10 shows a section of wool fiber undergoing flaking according to the invention (at the end of flaking, the scales have not yet fallen).

 - Figure 11 shows the scales which, in the method according to the invention, detach themselves and fall into the treatment bath, before the "mechanical" step.

In the figures, the same references have the same meanings, which are as follows: 1 fiber cortex 2 keratinous cement 3 exocuticle (scale) 4 endocuticle (scale) 5 opening area of scales 6 (hatching) area of attack of the keratin cement and the joint with the endocuticle, the arrows indicating the probable progression of the attack 7 "n imprint of the scale
In Figure 1 attached, we see that the scale (formed of exocuticle 3 - the epicuticle is not shown - and endocuticle 4) is linked to cortex 1 by a bond of keratin cement 2.

 FIG. 8 is a cross-sectional view of a fiber on which we find the external arrangement of the scales (3,4), the central core formed by the cortex 1, and the binding zone or keratin cement 2.

 It can be seen in FIG. 8 that the bonding zone is much less regular than that shown in FIG. 1. In the present application, when the enzymatic attack on the keratinous cement, or on the keratinous cement and the part of it, is mentioned. the cuticle fixed to the cement, reference will be made to a relatively irregular structure of the type of FIG. 8. This corresponds to the zone of enzymatic attack that we have tried to represent in hatching in FIG. 2 b. Those skilled in the art will understand, without it being specified again in the following, that this representation of the attack zone is given purely by way of non-limiting illustration.

 According to a first aspect, the invention relates generally to a method of flaking fibers of animal origin, of protein type, which comprises at least one step in which the keratinous cement layer "support" is significantly weakened or destroyed. forming the link between the scale (cuticle) and the cortex.

 According to another aspect, said step of weakening or destroying the keratinous "support" of the scale comprises a step during which an "opening" movement of the scales is carried out. By "opening" is meant the fact that one seeks to cause a fault or the beginning of a fault between the shell and its keratinous "support".

 The invention therefore also relates to a general method for treating the fibers considered, characterized in that it comprises a step in which the opening, as defined above, is caused, that is to say total or partial , of part of the scales. It has been discovered that this stage plays a preponderant role in the embrittlement process of the scale support. The methods which incorporate such a step will therefore be clearly preferred.

 According to yet another aspect, the invention relates generally to an enzymatic treatment process for the fiber which consists in selectively attacking by enzymatic means the layer of keratinous cement serving as a bond between the shell and the cortex.

 According to a second aspect, the invention relates generally to a method which consists in combining an opening movement of the scale with a selective enzymatic treatment.

 According to a third aspect, the invention relates generally to the combination of the above methods with at least one mechanical treatment making it possible to detach those from the scales whose support has been weakened or destroyed by said methods.

 According to a fourth aspect, the invention covers the new product which has been obtained by these processes, and which is characterized by a particular elimination of a certain number of scales, leaving a surface state markedly different from that obtained in the prior art, in particular because it comprises scales not eliminated or only partially eliminated, the imprint of the scales eliminated and, moreover, because the cortex was not damaged.

 The invention finally relates to the methods of treatment, preparation and spinning of natural fibers, in particular wool fibers, as well as of treatment and preparation of textile articles such as combed wool ribbons and the like, incorporating at least one step of the methods described above, as well as textile articles, or knitted items, or otherwise produced by textile or other means, from fibers obtained by these processes.

 The invention results from a radically original approach.

 According to the most general aspect of the invention, it is sought to significantly weaken or destroy the layer of keratin cement and the part of cuticle attached thereto and forming the connection between the scale (cuticle) and the cortex. In the present application, the term “keratinous cement” or “support” will denote the assembly formed by the cement itself and the part of the cuticle which is liable to be attacked. the support to the point that a subsequent mechanical treatment is sufficient to detach the scales from the cortex.

 For this purpose, a short enzymatic treatment of wool fibers (or other animal fibers) is carried out under conditions such that the enzyme will preferentially and selectively attack the "support" layer of keratinous cement.

 The invention therefore relates to a process for flaking animal fibers of the protein type, comprising a cortex and scales, characterized in that it comprises at least one step according to which the keratinous cement layer forming the layer is significantly weakened or destroyed. connection between a sufficient part of the scales (cuticle) and the cortex.

 "A sufficient part of the scales" designates the statistical proportion of scales above which the advantages of the invention are observed. Surprisingly, it is sufficient for an extremely small percentage of scales to be weakened and detached according to the method of the invention. The minimum threshold seems to be around 2 to 5% of statistically treated scales. Values below about 2 - 5% do not give any significant advantage.

Values above about 7-10% are very difficult to obtain.

 The determination of this percentage, which is a "statistical" representation of the effect of the treatment according to the invention, consists in placing in parallel between 200 and 300 fibers of approximately 600 mm in length, and placing under the microscope a " section11 of length approximately 6 mm from the beam thus formed. On each section, the effect of the treatment is observed. The scales are either detached, and their "imprint" remains, or are not detached, and then remain either intact, either very slightly attacked on the surface, or else they are broken. We can then easily establish the% of "attacked" fibers, the% of "loose" fibers and the% of unaffected fibers (except for a slight attack on the surface).

Method for examining fibers under a microscope
electronic:
Fiber sample:
The fibers are taken individually from inside and outside the tuft of a batch of wool. The fibers are fixed parallel to each other on a cardboard window. They are straightened but not stretched. The preparation is positioned on a sample holder, it is immersed in an inert atmosphere of argon and then is metallized by sputtering with gold (Ion Sputter 1100).

Visualization:
The preparation is observed by scanning electron microscopy (JEOL-T330A-Scanning microscope) under the following adjustment conditions: vacuum 10-4 Pa, potential difference 10kV, magnification 2000, incidence of the beam on the sample plate 450.

Statistical data acquisition:
Each fiber is observed on a single field.

At least 100 fibers are observed per batch of wool. The observations are repeated on n independent batches (n = 6 to 8) of wool having undergone a single type of treatment.

Observation criteria counted:
The observation of the surface appearance of each fiber makes it possible to "arrange" or classify it in one of the categories below: - modified fiber: this category includes fibers presenting modified surface images with regard to those of untreated fibers. These modifications can be classified in the following subcategories:
* altered surface
* swollen scales edges
* raised scales
* broken scales
* loss of scaly structure - unmodified fiber: fiber whose surface appearance does not allow it to be classified in the previous category and which can be considered "normal" by those skilled in the art.

According to a first aspect, the invention relates to a method characterized in that said step comprises a
movement of opening a sufficient part of the scales. According to another particular embodiment, the invention relates to a method characterized in that said step comprises the combination of an opening movement of a sufficient part of the scales with a selective enzymatic treatment.

 According to a preferred embodiment of the invention, represented in the appended FIG. 2, the conditions of preferential attack of the keratinous cement are obtained when a movement of opening of the shell is combined with the enzymatic treatment, and when also combined with a high ionic strength of the enzymatic treatment bath.

We will then seek in a first bath to open the shell (by the addition in particular of a surfactant in the bath) before, or simultaneously with, the enzymatic treatment. A suitable surfactant consisting of a synergistic mixture of ethoxylates and special products is known under the brand name
VALSOL ((m), HERE). Other surfactants or mixtures of surfactants are within the reach of those skilled in the art on reading the description and examples given here.

The opening of the scale (Figure 2b) allows the penetration of the enzyme mainly at the level of the keratinous cement layer (Figure 2c). The scales are opened at low ionic strength. Before or at the time of the enzymatic treatment, an additive capable of increasing the ionic strength of the bath is added. Such an additive will for example be a suitable buffer, such as a phosphate buffer, or a mixture of such buffers. These buffers are within the reach of those skilled in the art on reading the description and examples given here. It is surprising to note that the keratinous cement forming the "support" of the scales is thus selectively attacked, and above all that the attack is effective despite the fact that the treatment is short (of the order of a few minutes, for example 2 minutes ).

 According to a preferred embodiment of the invention, the bath will be very short and very little agitated.

In the same way, the wool will be shaken only slightly or not at all in order to avoid felting. Good efficiency is thus obtained even if the% of scales removed remains surprisingly low, of the order of 3 to 10%.

 FIG. 2a represents a cross section of a wool fiber, before the treatment according to the invention.

 Figure 2b shows the fiber when the scale begins the opening movement. Without wishing to be bound by any theory, the Applicant considers that a rupture occurs substantially at the interface between the endocuticle 4 and the keratin cement 2. "Substantially" means in this context that it is very likely that the break does not happen exactly at the interface. FIG. 4b, on the other hand, clearly indicates the opening movement of the scales, compared with FIG. 4a.

 FIG. 2c shows, in hatched lines, a probable zone of enzymatic attack. It is almost certain that the keratin cement 2 is attacked quite preferentially, according to the arrows shown purely by way of illustration in the figure. On the other hand, it seems that the endocuticle is only very little, or not at all, attacked. As will be seen below, this attack takes place either after the opening, or simultaneously with the opening. Figure 2 shows for simplicity the simultaneous attack with the opening, without limitation.

 FIG. 2d represents the section considered of the fiber substantially when the attack is finished.

The keratin cement 2 and possibly a small part of the scale were destroyed. The scale is therefore no longer attached to the cortex except by its base. The shape of the latter and its location are probably responsible for the existence of a characteristic "imprint" 7 after disappearance of the scale, as will be seen below and as shown in FIG. 5.

 The statistically weakened scales of FIG. 2d are then very easily detached or torn off during a subsequent mechanical treatment even with low energy. However, at the end of the attack step, the attachments of the scales are already statistically weakened to such an extent that a large percentage of the scales (among those actually weakened) detaches spontaneously under the simple agitation of the treatment bath. We then find the scales at the bottom of the bath, where it is easy to highlight them (see Figure 11 attached).

 The invention therefore generally relates to a method of flaking animal fibers, characterized in that a statistically sufficient part of the scales is opened, before or simultaneously with an enzymatic treatment, in that the ionic strength is increased. of the bath before or during the enzymatic treatment, and in that the enzyme is allowed to act for a time sufficient to weaken or destroy the keratinous cement forming the "support" of the scales actually weakened, but insufficient to damage the cortex.

 It is believed that the selectivity of the process is due to the fact that the enzymatic treatment is carried out under a strong ionic force, equivalent to a phosphate buffer solution of molarity 0.05 to 0.2 M. Thus, one of the originality of the invention is to penetrate the enzyme at the place selected for attack, thanks to the opening of the scales, at a time when the enzymatic activity is high because the ionic strength is chosen at a high value , and paradoxically without damaging the cortex. Thus, the enzyme will act effectively at the places where it has statistically penetrated, that is to say on the keratinous cement.

 This is a possible explanation, made a posteriori, and which does not bind the plaintiff. In reality, it was not obvious to think that one could selectively attack only a part of the scale, since a priori the same enzyme attacks all the layers of the scale simultaneously. There was also no reason to think that a short treatment, 10 to 100 times shorter than in the prior art, and not accompanied by oxidizing treatments, could make it possible to remove the scales, nor especially that one would remove enough scales to obtain a favorable result, which is not, and by far, accessible by the prior art, or else with rhedibitory damage to the cortex (cf. FIGS. 6 and 7 representing the beginning of alteration and respectively splitting of the fibers in the event of improper treatment) or other problems such as those arising from pollution by chemical agents. It was also absolutely not obvious that a statistical elimination of the order of 3 to 5% of the scales would be sufficient to produce an appreciable result in terms of feutrability in particular.

 This selectivity makes it possible to choose a very short treatment time, because only a small part of the scale is attacked, and, statistically, only a small proportion of scales, unlike the enzymatic filing processes where all of the scales are attacked. The treatment time will be chosen so that it is sufficient to weaken at least "significantly" the attachment or "support" of the scale, but insufficient to damage the cortex. The appraisal of the processing time by a person skilled in the art can be carried out using simple routine tests on samples, and using the general knowledge of a person skilled in the art.

 In a representative manner, the duration of the treatment is of the order of a few minutes, in particular from two to six minutes, and will preferably be a time as short as one minute.

 After this embrittlement step, a mechanical means or process is made to detach or finish detaching the flake. This process is as gentle as possible. One thus obtains a fiber of which enough scales are statistically detached, or "fall" in an almost "natural" manner after embrittlement.

We therefore obtain a product unknown to date, whose cortex has a remarkable surface condition, which is on the one hand undamaged and which on the other hand retains the imprint of the scales removed. This conservation of the imprint is due to the fact, as indicated above, that the very small percentage of scales which are weakened fall naturally or are eliminated by a relatively gentle mechanical treatment. It is therefore a physical elimination, the result of which is "natural". It is surprising to note that, despite their small statistical proportion, the fingerprints of the detached scales, which "naturally" subsist on the surface of the new fiber, favor the ability to spin, probably because their thickness (from l (0.1 to 0.2 microns, instead of 0.8 - 0.9 microns for scales) is perfectly suitable for ensuring good "cohesion" of the spinning fibers without affecting the speed of the operation . The 96 concerned is however so weak that the plaintiff does not wish to be bound by any theory.

It is also remarkable to note that a large part of the weakened scales detach by themselves in the bath comprising the step of enzymatic treatment, without it being necessary to carry out a mechanical treatment. This can be seen by the scales that collect at the bottom of the bath (fig. 11)
The method of the invention can be implemented according to all the variants accessible to those skilled in the art, and in particular in a single bath for opening and enzymatic treatment, or in two successive baths for opening the scales and then treating enzymatic, or in two identical successive baths (each comprising the step of opening and enzymatic treatment, with a dosage of approximately 1/2 of the enzyme in each bath), or in two successive repeated baths (opening then enzyme then opening then enzyme, with appropriate dosages and times). The determining criterion will be to increase the probability that the scales are well accessible to treatment, for a maximum opening and detachment yield.

 The appropriate enzymes according to the invention are known proteases, and mixtures thereof. Mention will in particular be made of a strongly alkaline protease known under the brand name MAXACAL <m) from the company GENENCOR and a biocatalyst based on selected enzymes known by the brand name BACTOSOL <TM) from the company SASOZ. Such enzymes and their mixtures can be selected by one skilled in the art on the basis of the present description and a few routine tests, in particular by checking the criterion of rapid and selective attack of the "support". It is in particular possible to carry out counting of the% of attacked fibers, of fibers with raised scales, of "split" fibers, etc., as described above or by other methods, using an electron microscope.

 The concentration of enzyme (s) will be chosen according to the invention between 0.1 and 0.4%, preferably between 0.1 and 0.2%, by weight relative to the bath, that is to say approximately 5 to 10 times less than the manufacturers' recommendations.

 It has been shown in fact, surprisingly, that the most important factor according to the invention is the% of open scales. This factor is more important than the time of enzymatic treatment or the enzymatic activity. Thus, optimal opening of the scales by a surfactant makes it possible to envisage a minimum enzymatic treatment time of the order of one minute for different enzymes and different conditions, and a higher percentage of "open" scales, therefore a percentage higher scales removed.

 The process can be carried out by adding a separate step (or bypass).

 In addition to direct economic and industrial criteria, we will seek to eliminate all of the scales in an aqueous medium, in order to avoid the treatment of ambient air to remove the fibers and comply with strict regulations in this area.

 The advantage of the invention is that it can be applied to raw fibers already washed in an aqueous medium, or in a solvent medium (degreasing), or also to ribbons of combed fibers, for example on the trowel, or to any other semi-finished, woven or knitted product.

 According to the invention, the conventional method and equipment can be adapted in order to optimize the benefits obtained.

 The new product has a spinnability, or aptitude for undergoing spinning, much greater than the spinnability of previously known products. We can thus clearly improve the steps leading to spinning, and the spinning itself. In particular, the operations are much faster than in the prior art.

This is indeed the mark of a new product, original in itself by its structure, and more precisely by its surface condition presenting the imprints of the scales removed and residual scales.
it is surprising to note that the spinability of the new product according to the invention is close to that of cotton, which is the perfect model in this area (spinning at very high speed and nevertheless retaining "cohesion"), while wool untreated is, on the contrary, the opposite model (slow spinning, very strong cohesion due to scales). The wool according to the invention therefore becomes a product very close to cotton and superior to synthetic fibers, in particular polyester (very fast spinning because the surface is very smooth, but lack of cohesion), and also very superior to the products obtained by "filing" of the scales, especially by chlorine filing like Supersoft (TM ,.

 The invention also relates to the fibers obtained by implementing the method according to the invention, as well as textile articles such as ribbons, threads, spun articles, knitted articles, and the like, made from said fibers whether they are considered as being obtained by the process according to the invention or as a new raw material in soil.

EXAMPLE
A wool of 21.5 micrometers was used, taken up at about 60% humidity after the last rinsing tank and dried to about 1% humidity under conditions of the order of 1 / 4h at 1900C.

The wool is immersed in a phosphate buffer solution (0.2M, pH = 8.2) with a bath ratio of 1:80. The bath temperature is 600C. This solution also contains a surfactant consisting of a synergistic mixture of ethoxylates and special products which is known under the name of VALSOL LTA-N (TM)), the concentration of which is 1 g / l. After 5 min of impregnation of the wool in the bath, the enzymatic reaction is triggered by adding the mixture of enzymes, so that the respective final concentrations of
MAXACAL 600,000 L TM) and BACTOSOL WO (TM) are 2g / l and igîl.

 Mild mechanical treatment may or may not be carried out, which mechanical treatment consists of slight agitation of the treatment bath or of the wool in the treatment bath.

 The enzymatic reaction is stopped at the end of two minutes 30 s by acidification of the treatment water or temperature rise by new passage in the dryer.

 The results are as follows.

Fibers Fibers Density of
modified% flaking% the ball g / cm3 reference 0 0 0.217 treatment
(*) 54 +/- 10 3 0.194 (**) read
(*) without stirring the wool in the bath
(**) with weak agitation of the wool in the bath
The observed difference in ball density is
results in a significant improvement in terms of
felting.

Claims (21)

 1. - New fiber of animal origin, of the protein fiber type, comprising a cortex coated with scales, characterized by a very regular and very complete elimination of a sufficient part of the scales, leaving a surface state comprising the imprint of statistically removed scales, residual scales, and without damage to the cortex.  2. - Process for flaking fibers of animal origin, of the protein fiber type, comprising a cortex coated with scales, characterized in that it comprises at least one step according to which the cement layer is significantly weakened or destroyed. "support" keratin forming the connection between the scale (cuticle) and the cortex, for a statistically sufficient proportion of scales.  3. - Method according to claim 2, characterized in that said step comprises an opening movement of a statistically sufficient proportion of scales.  4. - Method according to claim 2 or 3, characterized in that a combination of said step is carried out with, simultaneously or subsequently, a selective enzymatic treatment.  5. - Method according to claim 4, characterized in that the enzymatic treatment is carried out with high ionic strength, and in that the enzyme is left to act for a time sufficient to weaken or destroy the "support" keratin cement, but insufficient to damage the cortex.  6. - Method according to any one of claims 2 to 5, characterized in that said statistically sufficient proportion of scales is of the order of 3 to 5 or 10%.  7. - Method according to any one of claims 2 to 6; characterized in that the scales which are opened are opened by one or more surfactants.  8. - Method according to any one of claims 2 to 7, characterized in that the surfactant is a synergistic mixture of ethoxylates and special products, known under the brand name VALSOL (TM) from the company ICI.  9. - Method according to any one of claims 2 to 8, characterized in that the enzymes are chosen from proteolytic enzymes and their mixtures, in particular a biocatalyst based on selected enzymes known under the brand name BACTOSOL (TM) and a strongly alkaline protease known under the brand name is MAXACAL (TM) and mixtures thereof.  10. - Method according to any one of claims 2 to 9, characterized in that the concentration of enzymes or their mixtures is from 0.1 to 0.4%, preferably from 0.1 to 0.2% by weight compared to the bath.  11. - Method according to any one of claims 2 to 10, characterized in that the concentration in mixture of a strongly alkaline protease known under the brand name MAXACAL 600,000 L and a biocatalyst based on selected enzymes, known under the brand name BACTOSOL WO, is 2 g / l and 1 g / l respectively.  12. - Method according to any one of claims 2 to 11, characterized in that the duration of the enzymatic treatment is of the order of a few minutes, in particular from one or two to six minutes.  13. - Method according to any one of claims 2 to 12, characterized in that the enzymatic treatment is carried out in a bath with high ionic strength.  14. - Method according to any one of claims 2 to 12, characterized in that the enzymatic treatment is carried out in a bath of ionic strength equivalent to a phosphate buffer solution of molarity 0.05 to 0.2 M.  15. - Method according to any one of claims 2 to 14, characterized in that one then performs or simultaneously a gentle mechanical treatment to detach the scales and separate them from the cortex.  16. - Method according to any one of claims 2 to 15, characterized in that the mechanical treatment consists of slight agitation of the treatment bath or of the wool in the treatment bath.  17. - Method according to any one of claims 2 to 16, characterized in that the enzymatic treatment step is carried out in a separate washing column.  18 - Process for treatment, preparation and spinning of natural fibers, in particular wool fibers, characterized in that they comprise at least one treatment process according to any one of claims 2 to 17.  19. - Textile or knitted articles, or otherwise manufactured by textile or other means, characterized in that they are obtained by the process according to claim 18.  20. - Fibers obtained by a process according to any one of claims 2 to 18.  21. - Textile articles such as ribbons, threads, spun articles, knitted articles, made from fibers according to claim 1 or according to claim 20.