Description

PROCESS FOR THE PRODUCTION OF CASHMERE YKRNS

Technical Field

The present invention relates to the processing of cashmere fibres to obtain cashmere yarns and cashmere or cashmere - mix textile products, characterised by high quality in terms of fineness (count) , mechanical properties and purity.

Background Art

As is known, cashmere is a fibre obtained from a particular type of goat and, like all animal fibres, has physical properties directly affected by the collection period (by means of combing) , the breed and origin of the goats .

It is also known that amongst natural textile fibres cashmere has different morphological - organoleptic properties (length, fineness, shine, handle) and physical - mechanical properties (hygroscopicity, thermal stability, combustion method, felting, insulation, toughness, resilience) which may be enhanced during processing, depending on the methods used.

Cashmere processing includes opening, carding, combing, stretching, twisting, spinning, double winding, twining, conditioning and weaving.

Added to this chiefly mechanical processing are chiefly chemical steps such as dyeing and printing (using various types of dyes) or finishing (such as sanforising, teaseling, calendering, fulling, mercerising, starching, making crease-resistant, waterproofing) .

At present, cashmere yarns are widely used in particular for the production of knitwear textile products.

However, the known processes for producing cashmere yarns have many limitations regarding the achievement of high levels of yarn fineness or count values, currently not generally higher than

100000, because with cashmere, more than with any other type of fibres, the conditions which first the fibres and then the semifinished products are in during all steps of processing, from selection of the raw material to finishing the fabric, affect and determine the end quality of the yarn and the fabric.

A consequence of the limits of the known types of processes is that, at present, there are no spinning processes available suitable for the production of cashmere textile products which require very high quality and fineness, for example, bed sheets. Another disadvantage is that the relatively low quality of cashmere or cashmere - mix fabrics currently available has traditionally relegated these fabrics to "winter" use, since it does not allow the best use to be made of some cashmere fibre qualities, such as heat regulation, which is a potential characteristic allowing universal use (also called "four seasons") with changes in outside climatic conditions.

Disclosure of the Invention

The aim of the present invention is, therefore, to overcome these disadvantages by providing a process for the production of cashmere or cashmere - mix yarns and fabrics characterised by high level mechanical properties in terms of both durability when used and quality to the touch (softness, voluminosity) .

According to the invention, this aim is achieved by a process as defined in the main claims herein.

Brief Description of the Drawings

Further advantages and innovative features of the invention are obtained with a process, a yarn and a textile product as defined in the secondary claims, and are more apparent in the detailed description which follows, with reference to the accompanying drawings, in which:

- Figure 1 is a complete block diagram of a process for the production of cashmere yarns and fabrics in accordance with the invention;

- Figure 2 is a block diagram of the step of dyeing the fibres;

- Figure 3 is a block diagram of the step of finishing the fabric .

Detailed description of the preferred embodiments of the invention According to the invention, in a process for the production of a cashmere yarn, there is a preliminary step of selecting fibres obtained using suitable recipes .

In particular, the fibres are selected according to criteria of greatest length, lowest micron category, and greatest quantity of cuticle scales per single fibre, to improve the mechanical properties of the finished yarn.

In more detail, choosing the raw material involves making a selection to maximise and standardise the properties which can be achieved, including: length, fineness, cleanness, coefficient of variation, mean height and number of scales, cuticle width.

Using the selection described above it is possible to begin the spinning process from an extremely regular sliver, so that narrowing or thickening can be prevented during spinning.

Moreover, the rigorousness of the selection allows optimisation and standardisation of both the physical - mechanical and the chemical - physical properties of the fibres, which proved essential in order to produce the textile fibre (pure cashmere or silk blend) used to produce a yarn with a count of up to 200,000, having a high mean number of fibres per section, which thanks to the invention may even be 30 or more.

Once selected, any impurities are removed from the cashmere fibres through a customary kemp removal process then it is combed to obtain slivers with aligned fibres, also known as "tops".

Once the tops have been obtained, they can be sent to a dye bath (Figure 3) which advantageously is performed in controlled temperature and pressure conditions, and separately from the dyeing of any other fibres constituting the yarn, for example silk fibres.

According to the invention, during dyeing the tops are in the form of bobbins, or bumps, protected from the dye bath by a protective layer, or bag with micro-holes in it, permeable to the dye bath, in which the bobbins are immersed to limit the assault

on the fibres by the dyeing agents and additives and to prevent loss of the parallelism of the fibres.

After dyeing, the tops are washed and dried, the drying preferably being simultaneous with a straightening step. As illustrated in Figure 3, to standardise the chemical - physical properties in the dyeing process described above, specific products are also used for cleaning such as solvent soaps used to treat the material in advance, and the use of conditioners which precede the step of drying by means of straightener and drier, in order to relax and distribute the fibres again after the dyeing step.

When dyeing is complete, the dried and washed tops can be spun to obtain a single yarn with cashmere fibre .

In a preferred embodiment, a single yarn may be produced, of pure cashmere or cashmere mixed with other fibres, for example 70% cashmere fibres and 30% silk fibres.

In this first spinning step it is important to try to optimise and render uniform the mechanical and chemical - physical properties of the single yarn. In particular, for the former it was found that continuous monitoring and adjustment of the environmental conditions is essential for processing the material in ideal temperature and pressure conditions .

For this purpose, the spinning according to this invention may take place in a climatic chamber, under controlled temperature, humidity and pressure operating conditions.

According to the invention, during spinning of the fibres "ring" processing is used, adapted in the feed system to perform the yarn doubling and simultaneous twining processes. This avoids the use of the common double twist twisters on the market, which allow a high level of productivity, but which use high processing speeds, making the yarn cover long distances on the ring and so generating friction and resistance which increase the risks of the yarns breaking and/or having much more "nap" due to loss of fibre parallelism.

With the selected processing it is also possible to avoid the use of common doubling machines, which have feed systems with

yarn extensions and processing corners creating resistance and friction that in turn creates a risk of breaks and loss of parallelism.

Advantageously, the processing used according to the invention, through a repetition of the various spinning production steps, for example on the combing machine, guarantee standardisation and greater uniformity of the twisted yarn, even at the expense of processing speed and productivity.

When spinning is complete, the next step of quality control or "yarn clearing" is carried out on the already twisted yarn with the result of having fewer processing actions (involving higher quality and fewer rejects) .

After the spinning step a step of weaving the yarns is performed which, according to the invention, takes place in a climatic chamber, under controlled temperature, humidity and pressure conditions, to improve the workability of the yarns and the end quality of the textile product.

After weaving, the fabric obtained is further treated to improve the properties which the user can perceive, that is to say, the quality to the touch.

This processing (Figure 2) is the finishing step in which, according to the invention, a process involving double decatising was set up.

For this purpose, the weaving step is followed by a first step of stabilising through intermittent decatising (KD) performed in a kier under controlled temperature and pressure conditions, to prepare the fabric for the subsequent finishing step, consisting of washing and ennobling.

Finally, after finishing the fabric is subjected to a second intermittent decatising step.

According to the invention during the finishing step it is also possible to use a decatising wrapper able to allow fabric fixing, preserve the physical - mechanical properties and enhance the aesthetic characteristics such as the elegance, practicality, exclusivity and the "handle" (softness and voluminosity to the touch, that is to say, when felt between the area of the palm next to the thumb and the fingers on the hand) , as well as improving

functional properties such as lightness and heat regulating capacity unique to cashmere.

By way of example below is a table (Table 1) containing some properties characteristic of the yarn and the fabric obtained using the process disclosed, starting with a predetermined selected material and in predetermined environmental conditions .

As may be inferred from Table 1, the yarn and the fabric obtained in this way have excellent mechanical properties, which make them suitable for the production of superior products such as sheets, pillowcases and other items. However, it shall be understood that a process and a product according to the present invention may also have different applications and be modified without thereby departing from the scope of the inventive concept .

TABLE 1