EP2780499B1

EP2780499B1 - Method for treating semi-finished wool

Info

Publication number: EP2780499B1
Application number: EP12795371.9A
Authority: EP
Inventors: Illya Kulyk
Original assignee: Olimpias Group Srl
Current assignee: Olimpias Group Srl
Priority date: 2011-11-17
Filing date: 2012-11-14
Publication date: 2016-01-06
Anticipated expiration: 2032-11-14
Also published as: ITTV20110160A1; EP2780499A1; WO2013072339A1; ES2567049T3

Description

The present invention relates to a method for treating semi-finished wool, more in particular to a method for treating semi-finished wool that provides for the use of gas ionized and/or in plasma state, at atmospheric pressure.
Woollen textile items, although having universally known qualities, are characterized by some problematic aspects.
Among these latter, the phenomenon of felting of the wool must without doubt be mentioned. As known, felting of the wool, typically caused by washing in water, implies an aesthetic deterioration of the textile item and a decrease in its dimensions (shrinkage).
For the aforesaid reasons, to maintain its structure and appearance unchanged, it is advisable to wash the textile item by a dry cleaning process. Naturally, this can imply greater inconvenience and costs for the user.
To limit the phenomenon of felting, it is known to subject the semi-finished wool to chemical treatments based on Basolan^®.
These chemical treatments are, in general, highly polluting and require, for execution thereof, the involvement of specialized companies, with consequent increase of the overall industrial costs of the wool processing cycle.
In alternative to chemical treatments with Basolan^®, methodologies have recently been developed using reactive processes of enzymatic type to perform an anti-felting treatment of the wool.
Currently, these procedures are somewhat wasteful, above all in relation to the water volumes used and the energy consumption required.
It is known to subject a semi-finished textile, for example a sliver of combed fibre, to a treatment with gases ionized and/or in plasma state, to improve the surface properties thereof, as a function of subsequent treatments of finishing, dyeing and the like or to improve the resistance to felting thereof.
In the textile industry, treatments that use gases ionized and/or in plasma state, at atmospheric pressure, are currently very promising.
The main benefits offered by these treatments include, for example, reduced environmental impact and relatively low electric energy consumption with respect to the wet treatments described above.
The procedures that use gases ionized and/or in plasma state, at atmospheric pressure, currently available, suffer from significant limitations in terms of efficacy and reliability. Often, they require relatively long processing time of a textile item with a consequent increase of the overall costs.
A further very significant problematic aspect consists in the fact that during the treatment, a significant percentage of wool fibres is subject to burning.
It has been verified that this phenomenon causes an appreciable reduction in the surface quality of the textile item, in particular if this latter is knitted.
Patent documents US3817701 , WO96/19611 and WO2011/101780 relate to known processes to treat wool.
The document "Plasmabehandlung bei Atmosphärendruck - ein umweltschonendes Verfahren für die Veredlung von Wollgeweben" by Dr. H. Thomas, Dr. Lehmann, Prof. Dr. H. Höcker, 75. Tagung des Wissenschaftliches Rates der AiF, 28 November 2002 (2002-11-28), pages 1-2, XP055031356, discloses a further known process to treat wool.
From the above it is evident that, in the textile industry there is still the need to provide methods for treating semi-finished wool, by gases ionized and/or in plasma state, at atmospheric pressure, which are more reliable and effective with respect to the methodologies currently available.
The present invention intends to meet this need by providing a method for treating semi-finished wool according to claim 1 and the related dependent claims, set forth below.
In a general definition thereof, the processing method according to the invention is characterized in that it comprises the following steps:

providing a quantity of semi-finished wool to be treated;
processing said semi-finished wool so as to lay a wool layer, which has a basis weight lower than the basis weight of the semi-finished wool, provided in the previous step, on a continuous slide surface, along an advancing direction;
moving forward said wool layer continuously along said advancing direction, said wool layer sliding through one or more plasma treatment stations, at each of which said wool layer passes through a volume in which there is a process gas ionized and/or in a plasma state, at atmospheric pressure.

Preferably, said wool layer is ventilated by a first ventilation gas at said plasma treatment stations. Preferably, said step of providing a quantity of semi-finished wool comprises the step of providing a first sliver of semi-finished wool.
Preferably, said first sliver of semi-finished wool is opened and enlarged to obtain said wool layer having a basis weight lower than the basis weight of said semi-finished wool.
Preferably, said first sliver of semi-finished wool is opened and enlarged to obtain a wool layer that has a homogeneous basis weight.
Preferably, said wool layer is moved forward through an even number of plasma treatment stations.
Preferably, said wool layer is ventilated by fluxes of said first ventilation gas, which are directed along opposite directions, at plasma treatment stations that are placed at consecutive positions along said advancing direction.
Preferably, said wool layer is moved forward along said advancing direction, without exerting a traction force on the fibres of said wool layer.
Preferably, said wool layer is moved forward through a ventilation station, positioned upstream with respect to said plasma treatment stations, said wool layer being ventilated by a second ventilation gas, at said ventilation station.
In a further aspect, the present invention relates to a method for fabricating a woollen textile item according to claim 15, set forth below.
Further characteristics and advantages will be more apparent from the description of preferred but non-exclusive embodiments of the present invention, illustrated by way of non-limiting example with the aid of the accompanying drawings wherein Figs. 1-2 schematically illustrate the processing method according to the invention.
With reference to the aforesaid figures, the present invention relates to a method for treating semi-finished wool.
The method according to the invention comprises a step of continuously providing a quantity of semi-finished wool to be treated 101.
The semi-finished wool 101 can be any mixture of wool fibres not yet subjected to spinning, such as wool in staple form, in sliver form and the like.
Preferably, said step of providing the semi-finished wool to be treated comprises the step of providing at least a first sliver 101 of semi-finished wool.
The sliver of wool 101 can be any sliver of wool not yet subjected to spinning, such as a sliver of combed wool with selected fibre (also called wool top), a carded roving, a combed roving, and so forth.
Preferably, the method according to the invention comprises a step of providing a slide surface 11 for continuous moving forward, along a prevalent advancing direction D, of the semi-finished wool 101 to be treated.
In the practical embodiment of the method according to the invention, the slide surface 11 can advantageously be the surface of a sliding belt of an apparatus capable of treating with gas ionized and/or in a plasma state, at atmospheric pressure, a continuous substrate of textile type.
Alternatively, the slide surface 11 can be a supporting surface along which the semi-finished wool is pushed or pulled or advances by free falling.
The method according to the invention, comprises the step of continuously processing, preferably at a processing station 12_D, the semi-finished wool 101 so as to obtain a wool layer 100 laid on the slide surface 11 and destined to move forward continuously along the advancing direction D.
According to the invention, the wool layer 100, laid on the slide surface 11, has a basis weight lower than the basis weight of the semi-finished wool 101 supplied initially.
The term "basis weight" is intended, in this context, as a quantity indicating the volumetric distribution of the fibres, expressed as weight per surface unit.
Preferably, said step of processing the semi-finished wool 101 comprises the step of opening and enlarging the first sliver of wool 101 so as to reduce the volumetric density of the fibres and obtain a wool layer 100 with basis weight lower than that of the sliver of wool 101. Opening of the first sliver 101 advantageously takes place in a direction perpendicular to the advancing direction D, on a plane substantially horizontal and parallel to the slide surface 11. Preferably, the first sliver wool 101 is enlarged so as to obtain a wool layer 100, which has a homogeneous basis weight over its width.
With the term "homogeneous basis weight" it is intended, in this context, that the basis weight selected for the wool layer 100 is substantially kept constant point by point (i.e. not only on an average basis) across the section of wool layer 100.
In this manner, when the wool layer 100 is ventilated by a ventilation gas (as it will be described in more details in the following), the pressure exerted by said ventilation gas is substantially constant over the ventilated surface of the wool layer 100.
Preferably, before the step opening and enlarging, the first sliver of wool 101 is processed so as to improve the alignment of the wool fibres and reduce their twist degree. To this aim, various procedures are currently available in the state of the art.
The method according to the invention comprises the step of continuously moving forward the wool layer 100, laid on the slide surface 11, along the advancing direction D.
Preferably, the wool layer 100 is moved forward without exerting a traction force on the fibres, for example by continuous movement of the slide surface 11. Alternatively, the wool layer 100 can be pushed or moved forward by free falling.
According to the invention, the sliver of wool 100, during its forward movement, slides through one or more plasma treatment stations 12₁, 12₂, 12_N, advantageously positioned downstream of the processing station 12_D, taking as reference the advancing direction D. These plasma treatment stations can advantageously be formed by plasma treatment modules of an apparatus capable of treating with gas ionized and/or in a plasma state, at atmospheric pressure, a continuous substrate of textile type.
At each of the plasma treatment stations 12₁, 12₂, 12_N, the wool layer 100 passes through a volume 121 in which there is a process gas G ionized and/or in a plasma state, at atmospheric pressure. As it will clearly shown in the following, the process gas G is the gas, ionized and/or in a plasma state, which chemically interacts with the wool layer 100 passing through said treatment stations.
Preferably, a plurality of plasma treatment stations 12₁, 12₂, 12_N is provided. It has been found that by dividing the contact areas between the wool layer 100 and the process gas G, ionized and/or in a plasma state, at atmospheric pressure, the uniformity of the treatment is improved. In a preferred embodiment of the present invention, the process gas G, ionized and/or in a plasma state, is generated by a plasma generation procedure, at atmospheric pressure, of Dielectric Barrier Discharge (DBD) type.
For this purpose, the method according to the invention advantageously provides that pairs of electrodes 122_A, 122_B, separated and mutually opposed, are arranged at each of the plasma treatment stations 12₁, 12₂, 12_N.
Advantageously, the wool layer 100 is made to pass through the volume 121 comprised between each pair of opposed electrodes 122_A, 122_B, between which electric fields of relatively high intensity are applied.
When the wool layer 100 passes through the gap between said opposed electrodes, filamentary discharges E_S are triggered between these latter.
In the volume 121 concerned by these discharges, the process gas G, at atmospheric pressure, ionized and/or taken to a plasma state, is formed.
Chemical species present in the process gas G, ionized and/or in a plasma state, in the form of free radicals, are thus able to penetrate the wool layer 100 passing through and interact with the fibres of this latter, for example, activating the surface layer and/or modifying the physical and chemical surface properties and/or the morphology thereof.
Preferably, the process gas G is formed by ambient air between the electrodes 122_A, 122_B.
The treatment with process gas G is characterized by a certain specific energy value. This term is intended, in this context, as a size indicating the energy per surface unit that the process gas G, ionized and/or in a plasma state, is capable of transmitting to the fibres of the wool layer 100, passing through the volume 121.
Preferably, at the plasma treatment stations 12₁, 12₂, 12_N, the wool layer 100 is ventilated by a first ventilation gas F₁ that passes through the volume 121.
Preferably, the ventilation gas F₁ is directed in substantially transverse direction with respect to the slide surface 11.
Preferably, the ventilation gas F₁ is formed by ambient air that is advantageously conveyed at the plasma treatment stations 12₁, 12₂, 12_N by appropriate ventilation means.
Preferably, the ventilation gas F₁ provides the gas (e.g. ambient air) that it is ionized and/or brought into a plasma state between the electrodes 122_A, 122_B of each plasma treatment stations 12₁, 12₂, 12_N, thereby forming the process gas G.
In other words, at least a part of the ventilation gas F₁ preferably forms the process gas G ionized and/or brought into a plasma state when it passes through the electrodes 122_A, 122_B. According to other variants of the present invention, the gas forming the process gas G may be different from the ventilation gas F₁.
For the purpose of limiting total consumptions, the wool layer 100 is not ventilated by the ventilation gas F₁ in areas other than the plasma treatment stations 12₁, 12₂, 12_N.
In the practical embodiment of the method according to the invention, the number of plasma treatment stations 12₁, 12₂, 12_N, the dimensions of the electrodes 122 and the electric power absorbed by the plasma generation process can be selected as a function of the advancing speed of the wool layer 100 and of the specific energy value selected for the process gas G. Preferably, the wool layer 100 is moved forward through an even number N of plasma treatment stations 12₁, 12₂, 12_N.
At plasma treatment stations 12₁, 12₂, placed in consecutive positions along the advancing direction D, the wool layer 100 is preferably ventilated by fluxes of ventilation gas F1 which are directed along opposite directions. This solution contributes to reduce the occurrence of phenomena of burning to the fibres.
Preferably, the method according to the invention comprises the step of moving forward said wool layer 100 through a ventilation station 12_T, positioned upstream with respect to the plasma treatment stations 12₁, 12₂, 12_N, taking the advancing direction D as reference.
At the ventilation station 12_T, the wool layer 100 is ventilated by a second ventilation gas F₂, preferably directed in substantially orthogonal direction with respect to the slide surface 11. This pre-treatment allows the wool layer 100 to be suitably conditioned before contact with the process gas G, for example by regulating the humidity of the fibres.
Further, it has been noticed that such a pre-treatment remarkably improves the alignment of the fibres of the wool layer 100.
Preferably, the method, according to the invention, comprises the step of processing the wool layer 100, at the exit of the plasma treatment stations 12₁, 12₂, 12_N, so as to obtain a second sliver 102 of semi-finished wool.
Advantageously, this processing is carried out at a pick-up station 12_P of the wool layer 100, positioned downstream of the stations 12₁, 12₂, 12_N, taking the advancing direction D as reference.
The aforesaid processing preferably provides for thickening of the wool layer 100 so as to increase the volumetric density of the fibres, so that the resulting sliver of wool 102 has a basis weight higher than that of the wool layer 100, laid on the slide surface 11.
In this way, the sliver of wool 102 is suitable to be subjected to further processing (spinning cycle).
In an alternative embodiment (non illustrated), the method according to the invention advantageously provides that several slivers of wool 101 are processed so as to obtain a single wool layer 100 or several wool layers 100 placed side by side.
In this latter case, the wool layers 100 are laid on the slide surface 11 and moved forward through the pre-treatment station 12_T and the plasma treatment stations 12₁, 12₂, 12_N.
At the pick-up station 12_P, the wool layers 100 are processed further to obtain one or more slivers 102 of treated wool.
The method according to the invention advantageously provides for the following preferred operating conditions:

basis weight of the wool layer 100 (laid on the slide surface 11): comprised between 0.003 g/cm² and 0.018 g/cm²;
pressure of the process gas G: atmospheric pressure;
specific energy of the treatment with process gas G, ionized and/or in plasma state: comprised between 5 J/cm² and 30 J/cm²;
process gas G: air;
first ventilation gas F1: air;
second ventilation gas F2: air;

It has been verified experimentally how these operating conditions ensure good penetration of the process gas G, ionized and/or in plasma state, in the wool layer 100, promoting interaction of the free radicals generated in the process gas G with the surface of the fibres.
It has also been verified experimentally how these operating conditions determine a substantial decrease in phenomena of burning of the wool fibres placed in contact with this process gas.
The method according to the invention advantageously provides for the following further preferred operating conditions:

advancing speed of the wool layer 100: comprised between 3 m/min and 20 m/min;
speed of the ventilation gases F ₁ and F ₂: comprised between 5 m/s and 20 m/s;
relative humidity of the ventilation gases F ₁ and F ₂: comprised between 20% and 80%, preferably around 70%;
gap between the electrodes 122 _A , 122 _B: comprised between 1 mm and 3 mm, preferably between 2 mm and 2.5 mm.

Experimental tests have shown how in the wool subjected to the treatment method according to the invention, there is a significant decrease in the occurrence of felting phenomena, after washing in water.
In particular, it has been found that shrinkage of a textile item, produced with wool treated according to the method of the present invention, is, given the same conditions, much lower with respect to a textile item produced with untreated wool.
Typical shrinkage values in area for a textile item treated are comprised between 5% and 9%, therefore much lower than the values that characterise an untreated textile item, generally comprised between 20% and 25%

EXAMPLE

A wool top was subjected to the treatment method according to the present invention. The treatment was performed using an apparatus for continuous treatment of a textile substrate, by gas ionized and/or in plasma state, at atmospheric pressure.
The process gas was generated by a plasma generation process of DBD type.
In the apparatus used, the wool layer 100 is moved forward, along a slide surface, through two plasma treatment stations, through the action of a series of advancing rollers. At the treatment stations, the electrodes for generation of the plasma are formed by pairs of advancing rollers, positioned opposed so as to define the volume 121 in which the process gas ionized and/or in plasma state is generated. The wool layer 100 moved forward in the gap between the pair of rollers that form the electrodes.

The main operating conditions of the treatment carried out are listed below:

Parameter	Value
Number of plasma treatment stations (N)	2
Length of each plasma treatment station (according to the direction D)	0.4 m
Average power supplied to the plasma treatment apparatus	8 KW
Average total power supplied to the plasma treatment stations	5 KW
Voltage applied between each pair of electrodes	13 KV
Process gas (G)	ambient air
Process gas pressure (G)	atmospheric
First ventilation gas (F1)	ambient air
Basis weight of the wool top (first sliver 101)	0.036 g/cm²
Basis weight of the wool layer in contact with the process gas (wool layer 100)	0.010 g/cm²
Width of the wool layer in contact with the process gas (wool layer 100)	20 cm
Thickness of the wool layer in contact with the process gas (wool layer 100)	2 mm
Specific energy of the process gas (G), in plasma state	25 J/cm²
Advancing speed of the wool layer in contact with the process gas (wool layer 100)	4 m/min
Speed of the first ventilation gas (F1) in the plasma treatment stations	11 m/s
Relative humidity of the first ventilation gas (F1) in the plasma treatment stations	20%
Distance between the electrodes (122_A, 122_B) in the plasma treatment stations	2 mm
Length of the electrodes (in transverse direction with respect to the direction D)	0.6 m
Diameter of the electrodes (rollers)	7 cm

The wool subjected to the treatment method according to the present invention was used to produce a textile item (knitted piece 100% wool).
The textile item has a weave of single jersey type (tricot) with basis weight of 0.034 g/cm². An analogous textile item was produced with untreated wool.
Both samples were subjected to a washing process and to measurement of the resulting shrinkage due to felting. This characterisation process comprises the following steps:

a) drawing a first test rectangle on the sample. Dimensions: 26 cm in weft and 32 cm in warp;
b) drawing a second test rectangle inside said first test rectangle on the sample. Dimensions: 20 cm in weft and 25 cm in warp;
c) weighing the sample and adding a ballast to reach the weight of 500 g;
d) inserting the ballasted sample in a REX washing machine type RWF8140W;
e) performing a pre-wash cycle of type 7-A (standard UNI ISO 6330-1984) of the ballasted sample. Operating conditions:
- detergent used: DIXAN^® CLASSIC, 20ml;
- programme set: WOOL;
- duration: until the end of the programme;
- spin setting: 500 rpm;
- wash temperature setting: 40 °C;
f) removing the ballasted sample from the washing machine and taking measurements in water, using the test rectangles;
g) performing a wash cycle of type 5-A (standard UNI ISO 6330-1984) of the ballasted sample. Operating conditions:
- detergent: "DIXAN^® CLASSIC", 20ml;
- wash duration: 13.5 min.
- programme setting: NORMAL SYNTHETICS;
- wash temperature setting: 40 °C;
h) setting the RINSE programme with spin at 500 rpm and ending the set programme;
i) repeating steps g)-h), without removing the ballasted sample from the washing machine;
j) removing the ballasted sample from the washing machine and taking measurements in water, using the test rectangles.

The measurements for characterising shrinkage of the tested textile items, net of the normal relaxation of the fabric (excluded in the pre-wash step) provided the following results:

Untreated textile item Treated textile item

Shrinkage in warp (%) 16.2 7.4

Shrinkage in weft (%) 6.7 0.8

Shrinkage in area (%) 22.9 8.2
Further experimental tests have shown how the wool subjected to the treatment method according to the invention offers improved performances with regard to its dyeability.
It has been verified that, for the wool subjected to the treatment method according to the invention, it is possible to decrease the dyeing temperature and decrease the total times of the dyeing process, even eliminating the scouring step.
A significant decrease (around 50%) in the drying times after washing was also found in the treated wool.
On the basis of the above, it is evident how the method according to the invention enables the aim and objects stated to be achieved.
The method according to the invention allows the semi-finished wool to be reliably and effectively treated and therefore makes it possible to obtain woollen textile items characterized by high quality and capable of offering high performances with regard to dyeability and resistance to felting.
The method according to the invention is easily implemented at industrial level and is particularly suitable to be implemented within wool processing cycles commonly adopted at industrial level.
Due to its efficacy, the method according to the invention allows a significant decrease in the times and industrial costs required to produce woollen textile items.

Claims

Method for treating semi-finished wool characterised in that it comprises the following steps:
- providing a quantity of semi-finished wool (101);

- processing said semi-finished wool (101), so as to lay a wool layer (100), which has a basis weight lower than the basis weight of said semi-finished wool (101), on a continuous slide surface (11) along an advancing direction (D);

- moving forward said wool layer (100) along said advancing direction (D), said wool layer sliding through one or more plasma treatment stations (12₁, 12₂, 12_N), at each of which said wool layer (100) passes through a volume (121), in which there is a process gas (G) ionized and/or in a plasma state, at atmospheric pressure.
Method, according to claim 1, characterised in that said wool layer (100) is ventilated by a first ventilation gas (F₁) at said plasma treatment stations.
Method, according to one or more of the previous claims, characterised in that said step of providing a quantity of semi-finished wool (101) comprises the step of providing a first sliver (101) of semi-finished wool.
Method according to claim 3, characterised in that said step of processing said semi-finished wool (101) comprises the step of opening and enlarging said first sliver (101) of semi-finished wool.
Method according to claim 4, characterised in that said first sliver (101) of semi-finished wool is enlarged so as to obtain a wool layer (100) that has a homogeneous basis weight.
Method according to one or more of the previous claims, characterised in that the specific energy of the treatment with said process gas (G), ionized and/or in a plasma state, is comprised between 5 J/cm² and 30 J/cm².
Method according to one or more of the previous claims, characterised in that the basis weight of said wool layer (100) is comprised between 0.003 g/cm² and 0.018 g/cm².
Method according to one or more of the previous claims, characterised in that said wool layer (100) is moved forward through an even number (N) of plasma treatment stations (12₁, 12₂, 12_N).
Method according to claim 8, characterised in that said wool layer (100) is ventilated by fluxes of said first ventilation gas (F₁), which are directed along opposite directions, at plasma treatment stations (12₁, 12₂) that are placed at consecutive positions along said advancing direction (D).
Method according to one or more of the previous claims, characterised in that said wool layer (100) is moved forward along said advancing direction (D), without exerting a traction force on the fibres of said wool layer.
Method according to one or more of the previous claims, characterised in that it comprises the step of moving forward said wool layer (100) through a ventilation station (12_T), positioned upstream with respect to said plasma treatment stations (12₁, 12₂, 12_N), said wool layer (100) being ventilated by a second ventilation gas (F₂), at said ventilation station (12_T).
Method according to one or more of the previous claims, characterised in that it comprises the step of processing said wool layer (100), at the exit of said plasma treatment stations (12₁, 12₂, 12_N), so as to condense said wool layer (100) and obtain a second sliver (102) of semi-fmished wool that has a basis weight higher than the basis weight of said wool layer (100).
Method according to one or more of the previous claims, characterised in that at each of said plasma treatment stations (12₁, 12₂, 12_N) a pair of separated and opposed electrodes (122_A, 122_B) is arranged, said wool layer (100) passing through a gap between said electrodes.
Method according to one or more of the previous claims, characterised in that said process gas (G), said first ventilation gas (F₁) and/or said second ventilation gas (F₂) are formed by air.
A method for fabricating a woollen textile item that comprises a method according to one or more of the previous claims.