US20090305593A1

US20090305593A1 - Method for manufacturing a non-woven fabric based on natural wool, plant for applying such method, and product obtained by such method

Info

Publication number: US20090305593A1
Application number: US12/375,227
Authority: US
Inventors: Alberto Schiavi; Lorenzo Pernigotti
Original assignee: ORSA Srl
Current assignee: ORSA Srl
Priority date: 2006-07-27
Filing date: 2007-07-24
Publication date: 2009-12-10
Also published as: ITMI20061484A1; WO2008029307A3; WO2008029307A2; EP2049719A2; JP2009544862A

Abstract

A plant and method for manufacturing a wool-based, non-woven fabric is disclosed, wherein the steps are carried out of providing flocks based on natural wool fibres, of carrying out a carding and veiling of the flocks based on wool fibres, up until obtaining a veil based on wool fibres, and of carrying out needle-punching on the veil based on wool fibres, wherein at the end of the needle-punching a water-jet interleaving step is also carried out. Some products which may advantageously be obtained through such method and plant are also disclosed.

Description

The present invention concerns a method and a plant for the manufacture of a non-woven fabric, in particular a non-woven fabric based on natural wool, as well as the product obtained by such method.
As known, a non-woven fabric is a substantially bi-dimensional, semi-processed product, which is obtained by assembling a plurality of natural or synthetic fibres of a certain length. From this point of view, it is radically different from a classic woven fabric, which is instead put together starting from yarns of indefinite length and using weaving machines which accomplish a classic weft-warp configuration.
In order to consolidate a plurality of fibres in a fabric, various techniques exist, which substantially aim at interleaving in a mutually stable way the fibres—both through a purely mechanical action, and with the help of binding agents —so as to prevent the product from coming undone with use.
In the industrial field various synthetic fibres have been developed and manufactured which are particularly suitable for the composition of non-woven fabrics. Conversely, there are some natural fibres which instead are very unsuitable for this processing, having a natural tendency not to interleave or to loosen the bonds thereof over time and with use.
With such respect, so far it has not been possible to detect any processing which allows to obtain a good non-woven fabric with natural wool fibres.
In some cases it was possible to obtain a processable woollen support using needle punching machines.
A needle punching machine is a work station equipped with one or more pairs of arrays of opposite needles (having specific arrangements), which are interpenetrated and alternately moved apart, while a veil of fibres to be processed is made to move between the same; when the two opposite arrays of needles are repeatedly moved closer and further apart, causing the needles to interpenetrate, the interposed fibres are “needle punched”, i.e. they interleave and mechanically connect with one another: this allows to impart a certain cohesion to the veil of fibres.
The consistence and the physical properties of the natural wool fibres, however, are such that the needle punching process may work—i.e. it may supply a stable non-woven fabric—only in specific conditions, i.e. when the veil of raw material is of an adequate basic weight and when the needles are arranged diagonally and/or characterised by the presence of special hooks.
In these conditions, with natural wool fibres it is nevertheless possible to form only a sort of felt, i.e. a rather thick, rigid product, with an unpleasant handle and unpleasant to the touch, as well as having a limited number of applications.
The need is instead felt for a better-quality non-woven fabric based on natural wool fibres, since it potentially serves for a number of advantageous applications, also due to the inherent insulating and fire retarding properties of these fibres.
In particular, it would be desirable to be able to obtain such a non-woven fabric having sufficient resistance to mechanical stress (tearing, cutting, and so on) and maintaining good cohesion with use, also to be able to dye it with conventional finishing treatments.
The object of the present invention is hence that of providing a plant and relative treatment method for obtaining non-woven fabrics based on natural wool. A further object of the invention is to provide a product of non-woven fabric based on natural wool which is soft, with a good handle, resistant (also to dying treatments) and suited to a number of applications.
Such objects are achieved through a method, an apparatus and a product as described in their essential features in the accompanying claims.

Further features and advantages of the device according to the invention will in any case be more evident from the following detailed description of a preferred embodiment of the same, given by way of example and illustrated in the accompanying drawings, wherein:

FIG. 1 is a schematic view illustrating an exemplifying plant of the invention;

FIG. 2 is an elevation side view of an exemplifying plant of the invention;

FIG. 3 is a section view of an exemplifying plate of needles of the needle punching machine employed in the invention;

FIG. 4 is an elevation view of a needle of the plate of FIG. 3;

FIG. 5 is a schematic view of an enlarged detail of the water jet station shown in FIG. 2;

FIGS. 6A and 6B are microscope pictures, with 4× lens, 40× eyepiece, 128× video enlargement and 10× lens, 100× eyepiece, 320× video enlargement, respectively, of the fabric according to the invention after needle punching;

FIGS. 7A and 7B are pictures as in FIGS. 6A and 6B of the non-woven fabric after treatments with water jets; and

FIGS. 8A and 8B are pictures as in FIGS. 6A and 6B of the non-woven fabric after a dying treatment.

The manufacturing process provides to start from processed wool, in a manner known per se, so as to have flocks of sufficient volume and uniformity. This first treatment may be performed for example with any known-type mechanical process.
According to the invention, the wool flocks are then mixed with variously-sized flocks of synthetic fibres, such as fibres of polyester, polyamide, viscose, acrylic, Bamboo, PLA and preferably microfibre, in an amount ranging from 20 to 50% by weight, better about 30%. From tests carried out by the Applicant, it has been detected that microfibre flocks are particularly preferred, which impart excellent mechanical and physical qualities to the final woollen fabric; a particularly suited microfibre is the one called “mechanical splittable”, made of polyester/polyamide, for example the one marketed by Far East Textile Ltd. under the name EASTLON SY1250SMS MICRO-SPLIT.
By the term microfibre in this context fibres are intended with a count below 1 dtex or conjugated fibres, with count above 1 dtex, splittable into ultrafine or super ultrafine segments (with count of 0.09-0.13 dtex) through solvents, alkali or mechanical action (high-pressure water jets).
These “splittable” microfibres have the feature of splitting into many very fine (below 1 den) fibres when they undergo a mechanical impact, which produces an advantageous effect which will be illustrated in the following.
The mixing of the wool flocks with the synthetic fibre flocks must be carried out until a uniform base product is achieved; mixing can be carried out, for example, in a carding willow and mixing box for a time of about 3-4 hours depending on the amount of fibres to be mixed.
The mixed mass then undergoes a process by means of a carding machine/veil-forming machine 2, with subsequent possible pleating machine, to obtain a continuous processable veil, of a thickness from 6 to 8 cm and weight from 120 to 300 g/m², depending on the thickness of the final product which it is intended to achieve.
At the exit of veil-forming machine 2 and of the possible pleating machine, the veil of fibres is preferably stretched by a gill box and then placed on a first needle-punching station 3, where it is needle-punched with techniques known per se. For example, a needle punching machine manufactured by Fehrer AG may be used.
Needle punching may also be carried out through one or more subsequent steps, for example carrying out also a pre-needle-punching.
In this process a first mechanical interleaving between the fibres making up the veil takes place. Needle-punching is performed until a carpet of non-woven fabric is obtained of thickness 2.5-4.0 mm.
The presence of synthetic fibres, in particular of microfibre, aids a good result already at this stage.
Moreover, according to the invention, at the exit from needle punching machine 3 the fabric undergoes an interleaving treatment with water jets 4 (a so-called “spunlace” treatment), which dignifies the non-woven, needle-punched fabric. In particular, the Applicant has detected that this stage is very advantageous for the good outcome of the process with woollen fibres, because the number and solidity of the bonds between the fibres is increased. During this last treatment, the microfibres are divided (split) by the water jets and the ultrathin fibres thereby forming further bind the woollen fibres.
Water-jet interleaving hence allows to complete and dignify the non-woven, needle-punched fabric, making it more close-knit, uniform and soft, which result is critical to be able to obtain the desired product based on woollen fibres.
Water-jet interleaving is preferably carried out with a jet density of 12-18 per linear cm, preferably 16 per linear cm, at a pressure of 250-400 bar, preferably 150-250 bar, at a low advancement speed.
This allows to obtain a density between 150 and 180 gr/dm³and a thickness between 0.8 and 1.6 mm.
Thanks to this combination of needle-punching and water-jet interleaving, as well as to the presence of synthetic fibres, it is hence possible to obtain a wool-based, non-woven fabric having excellent mechanical and physical qualities.
Needle-punching, in particular, allows to provide a first compaction and intersecting of the mixed woollen/synthetic fibres, also starting from a veil of a significant width (for example above 8 cm). This allows to obtain a substrate suitable to make the subsequent water-jet interleaving effective—which would otherwise be unable to interact with the deeper fibres—which imparts desired characteristics of handle, feel, porosity and cohesion. It is thereby possible to obtain soft and close-knit fabrics, starting from a veil of a thickness even above 8 cm, without nevertheless excessively forcing the needle-punching process which would inevitably lead to a felt-type product.
Thanks to the final treatment with water-jet interleaving, the non-woven fabric based on natural wool has the characteristic pore fineness and hairiness as the “spunlace”, as well as the good edge shear resistance. Due to the high cohesion obtainable through coupling the two treatments, the woollen, non-woven fabric also has a high resistance to tearing and withstands multiple washing cycles. Moreover, precisely in the light of these qualities, the non-woven fabric of the invention can perfectly withstand a dying treatment even at the end of the process, which dying would instead be much more difficult to carry out on the raw material (i.e., upstream of the processing, directly on the fibres). Also this last feature further extends the field of application of the product according to the invention.
The Applicant was able to ascertain that the woollen fabric obtained through the process and the plant of the inventions surprisingly has features never obtained so far by using needle-punching processes only or of water-jet interleaving only.
The number of and variety of applications which this original woollen fabric meets are remarkable, also thanks to the characteristics of the woollen fibre itself, such as the fire-retarding and insulating character.
In particular, it has been detected that the non-woven fabric manufactured according to the invention may find application in the field of blankets or insulating panels, in lining materials and tapestry (including the automotive industry)—also as a replacement of foams, provided it is manufactured with a suitable thickness/volume—in filters, both dry ones and wet ones, in the field of cleaning cloths (wherein it develops a polishing effect, thanks to the wool component), in the clothing industry and other.
However, it is intended that the invention is not limited to the particular configurations illustrated above, which represent only non-limiting examples of the scope of the invention, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of the invention.

Claims

1. Plant for manufacturing non-woven fabric based on natural woollen fibres in flocks, characterised in that it comprises in succession at least one needle-punching station and one water-jet interleaving station.

2. Plant as claimed in claim 1, wherein upstream of the needle-punching station there is furthermore prearranged a carding and veil-forming station.

3. Plant as claimed in claim 1, wherein there is further provided, upstream of the needle-punching station, a flock-mixing station, capable of mixing wool fibre flocks with synthetic fibre flocks in an amount from 20 to 50% by weight.

4. Manufacturing method of a wool-based, non-woven fabric, comprising the steps of

providing flocks based on natural wool fibres,

carrying out carding and veiling of said flocks based on wool fibres, up until obtaining a veil based on wool fibres,

performing needle-punching on said veil based on wool fibres to obtain a needle-punched carpet, characterised in that at the end of the needle punching the following step is also carried out

water-jet interleaving of said needle-punched carpet.

5. Manufacturing method as claimed in claim 4, wherein before said carding and veiling, said flocks based on wool fibres are mixed with flocks of synthetic fibres to an amount of 20-50% by weight.

6. Manufacturing method as claimed in claim 5, wherein said flocks of synthetic fibres are flocks of splittable microfibres.

7. Manufacturing method as claimed in claim 4, wherein said wool-based veil has a thickness above 8 cm.

8. Wool-based, non-woven fabric, characterised in that it is obtained through a method as claimed in claim 4.

9. Insulating blanket, characterised in that it consists of a non-woven fabric as claimed in claim 8.

10. Fabric for lining, characterised in that it consists of a non-woven fabric as claimed in claim 8.

11. Clothing component, characterised in that it consists of at least in part of a non-woven fabric as claimed in claim 8.

12. Plant as claimed in claim 2, wherein there is further provided, upstream of the needle-punching station, a flock-mixing station, capable of mixing wool fibre flocks with synthetic fibre flocks in an amount from 20 to 50% by weight.

13. Manufacturing method as claimed in claim 5, wherein said wool-based veil has a thickness above 8 cm.

14. Manufacturing method as claimed in claim 6, wherein said wool-based veil has a thickness above 8 cm.