WO2008058689A1

WO2008058689A1 - Process for the treatment with liquid ammonia or with liquid ammonia solutions of woven fabrics, non-woven fabrics, yarns, slivers or tow

Info

Publication number: WO2008058689A1
Application number: PCT/EP2007/009758
Authority: WO
Inventors: Roberto Franchetti
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-11-13
Filing date: 2007-11-12
Publication date: 2008-05-22
Anticipated expiration: 2009-05-13
Also published as: WO2008058689B1; ITVI20060332A1

Abstract

This is a process for the treatment with liquid ammonia or with liquid ammonia solutions of woven fabrics, non-woven fabrics, knitted fabrics, yarns, slivers or tow based on cellulosic, animal, artificial or synthetic fibres, or relatively mixed ones. This process is characterised in that the products in question are impregnated with liquid ammonia or with a liquid ammonia solution in an adjustable percentage of between 0.1% and 200% by weight of the products concerned, in order for them to react with said chemical substances. The said textiles (3) are mechanically wound around the outside of a drum (2), either alone or in conjunction with a blanket, so as to prevent unwanted modifications of their dimensions.

Description

TITLE:

PROCESS FOR THE TREATMENT WITH LIQUID AMMONIA OR WITH LIQUID AMMONIA SOLUTIONS OF WOVEN FABRICS, NON-WOVEN FABRICS, KNITTED FABRICS, YARNS, SLIVERS OR TOW BASED ON CELLULOSIC, ANIMAL, ARTIFICIAL OR SYNTHETIC FIBRES, OR RELATIVELY MIXED ONES. Description The present invention concerns a process for the treatment with liquid ammonia or with a liquid ammonia solution of woven fabrics, non-woven fabrics, knitted fabrics, yarns, slivers or tow based on cellulosic, animal, artificial or synthetic fibres, or relatively mixed ones.

Among the finishing treatments for cellulosic fabrics, a process has long been known, envisaging the use of liquid ammonia baths in which a fabric is impregnated for a time varying from a few seconds to some minutes.

Liquid ammonia treatment of cellulosic fabrics gives considerable advantages, among which the following may be listed: improving of the dyes affinity, improving of the dimensional stability, improving of wash and wear characteristics, softer touch, prolonged maintenance of the "new aspect", even after several washes, higher resistance to abrasion and tear. It is also known that liquid ammonia treatment is particularly complicated. In fact, ammonia has a suffocating odour and may not be released into the atmosphere, as a concentration of only 150-200 ppm is high enough to cause serious irritation of the eyes and of the respiratory tract. According to the current state of the art technology, fabrics are impregnated by means of liquid ammonia, which is then removed from same by evaporation or washing. The ammonia removed from the fabric is then re-condensed, so as to be used again. Both operations require highly complicated ammonia treatment and recovery plants, as well as involving huge energy and management costs. As an instance of patent documents on this subject, the following are cited: US-A-4074969, US-A.-4189847, US-A- 3721097, US-A-4152907, BE-A-1009874.

Document DE.CI. 19639141 describes a machine, similar to a so-called "Jigger", for the discontinuous treatment of fabrics by means of liquid ammonia, with the drawbacks of very low productivity and high power consumption.

Document WO-A-2004088027 describes an ammonia treatment of a textile product, wherein the textile article is impregnated by condensation from the gaseous to the liquid state. According to the said document, condensation takes place at the atmospheric pressure, at a temperature of approx. - 33° C. Hence the need to use high power to obtain condensation of the ammonia; in practice, the entire surface of the rollers must be taken to a temperature of approx. - 45° C, in order to obtain good results. Finally, the plant described in the above document works "on a continuous basis", which results in uncontrolled shrinkage of the fabric. The liquid ammonia treatment plants currently in use cannot be used to treat knitted fabrics or yarns; moreover, they are unable to properly control the percentage of impregnation of the textiles with liquid ammonia_and, finally, they cannot effectively compensate for the high shrinkage of cellulosic fabrics, which is due to fibre swelling. By way of example, a warp and weft cotton fabric weighing 180 g/sq.m, not mechanically bound, will undergo the following amounts of shrinkage: - 120% liquid ammonia impregnation; 15% shrinkage after 8 seconds

75% liquid ammonia impregnation; 15% shrinkage after 15 seconds 60% liquid ammonia impregnation; 15% shrinkage after 30 seconds 40% liquid ammonia impregnation; 10% shrinkage after 30 seconds 25% liquid ammonia impregnation; 5% shrinkage after 30 seconds. Document JP 10 088 465 describes a machine that carries out the treatment with liquid ammonia of cellulosic yarns wound on cones. In this case, the absorption of liquid ammonia on the outer part of the cones and the swelling of the fibres generate very high pressure on the inside of the cones, due to which this treatment is extremely uneven. Document US 5 953 780 describes a machine for dyeing synthetic yarns or webs, wound on reels, with dyestuff dispersed in a supercritical liquid, such as carbon dioxide or liquid ammonia. This system does not offer the possibility to control the impregnation percentage and involves high energy costs. Document GB 854 221 describes a machine for dyeing fabrics wound around a drum, which can rotate at adjustable speed.

Various processes are also known, wherein liquid ammonia is used in order to apply the dyestuff to a web. In practice, the fabric is padded, at atmospheric pressure, with dyestuff dispersed in liquid ammonia. Subsequently, the liquid ammonia is evaporated and the dyestuff is fixed by means of a thermal treatment or by steaming.

These processes are quite simple; unfortunately, they, too, require a complex and costly ammonia recovery plant, due to which their implementation has been extremely limited. The purpose of this invention is to create a process for the treatment with liquid ammonia or with liquid ammonia solutions of woven fabrics, non-woven fabrics, knitted fabrics, yarns, slivers or tow based on cellulosic, animal, artificial and synthetic fibres and relatively mixed ones, free from the problems mentioned above. The textile products to be treated can be raw, bleached, dyed or resin-finished, either thoroughly dried or slightly moistened. In particular, this invention can be used in the finishing and dyeing of woven fabrics, non-woven fabrics, knitted fabrics, slivers or tows based on cellulosic fibres (such as cotton, flax, ramie, hemp...), or animal fibres (such as wool, mohair, alpaca, silk...), or artificial fibres (such as polynosic, viscose, acetate, triacetate...), or synthetic fibres (such as polyester, acrylic, polyamide, micro-fibres...), as well as on combinations of relatively mixed fibres. According to this invention, this is obtained by impregnation of the textiles with liquid ammonia, or with a liquid ammonia solution, in an adjustable percentage of between 0.1% and 200% by weight of the textiles, said textiles being placed in a vessel which houses a drum around which the textile material is wound and said drum being located along the longitudinal axis of the vessel. The impregnation of the textile material with liquid ammonia, or with a liquid ammonia solution with pre-set pick-up, as well as the dwelling time for the reaction between the fibres and the ammonia, the removal of liquid ammonia from the textile after the treatment and the final removal of all residual ammonia, take place with the textile product mechanically bound around the drum, in order to prevent unwanted dimensional changes, warping or creasing. In particular, the vessel, which obviously is to remain closed for the entire duration of the treatment, prevents the leakage of ammonia into the atmosphere. The working pressure inside the vessel can be the either the same as the atmospheric pressure, or below or above it. This feature, as well other features of this invention, are illustrated in detail below, with reference to a specific embodiment thereof, provided purely by way of a non-limiting example of embodiment, with the help of the enclosed table, where: Figure 1 is a schematic longitudinal view of a vessel inside which the process referred to in this invention is carried out. Figure 2 is a schematic cross-sectional view of the above.

The reference numbers that will be used hereinafter are listed below:

1 - vessel

2 - drum

3 - textile product 4 - condenser

5 - inlet duct

1. outlet duct

2. duct

3. tank 4. motor

5. pump

6. duct

7. distribution bar 8. duct

9. duct

10. jacket (can be replaced with a technical heat exchanger)

1 1. duct 12. duct

13. duct

14. steam dispenser

15. steam vent

16. vacuum pump 17. duct

18. distributor

19. discharge

As can be seen in the enclosed figures, the process in this invention involves the use of a vessel 1, housing a drum 2 with holes on its side surface. Said drum 2 is placed along the longitudinal axis of vessel 1 and, to advantage, it can be made to rotate about its axis for the purposes specified hereinafter. In fact, the textile product 3 is wound around said drum 2, with a predetermined and controlled tension. The thickness of the textile product clearly wound up in coils can be adjusted based on the type of article and relevant finishing process. The textile product 3 and a blanket can also be wound together around drum 2. It can be useful to use a blanket, such as a synthetic satin one, which, thanks to its smooth surface and excellent permeability, will ensure excellent surface finishing of the fabrics. It can also be useful to use a blanket, which will act as a container, for treating slivers. The fabric can be wound around the drum outside the machine and the drum 2 can than be inserted in vessel 1 ; alternatively, the fabric can be wound directly around drum 2 inside vessel 1 , obviously before the liquid ammonia, or a liquid ammonia solution, is fed into the vessel. In this regard, by "liquid ammonia solution" we mean liquid ammonia with water and/or with finishing chemical products and/or with ammonia salts and/or with solvent and/or with alcohol and/or with glycol and/or with urea and/or with dyes and/or with caustic soda. It is understood that this list is not limiting, as the ammonia can be dissolved in other chemical substances, or in a combination of various chemicals. After vessel 1 has been closed, with the drum inside it, all the air is sucked out of the vessel by means of vacuum pump 21 and then the pressure inside vessel 1 is compensated by the introduction of ammonia gas.

The liquid ammonia or a liquid ammonia solution is then fed to the vessel in the liquid state from tank 8, through pump 10 and duct 11 , connecting it to distribution bar 12, located inside drum 2. The latter is set in rotation about its axis via a motor 9, and it is then made to rotate at a pre-set speed, for a fast and even distribution of the liquid ammonia or liquid ammonia solution through the coils of the textile product 3 wound around drum 2. In fact, the ammonia molecules are very small and thus can quickly and deeply penetrate the cellulosic structure of textile 3, causing the fibres to swell. By contrast, such events as dimensional changes, an undesirable effect, creasing, weft distortion and edge curling, in the case of knitted fabrics, are prevented thanks to the fact that the textile product 3 is mechanically bound around drum 2. The cellulosic fibre, swollen by the action of the liquid ammonia or liquid ammonia solution, is not free to contract and, as a result, it takes on a round shape and sheen. The rotational speed of drum 2 is determined so as to ensure perfect and even distribution of the liquid ammonia or liquid ammonia solution through the coiled textile, in order to guarantee thorough impregnation of all fibres and, finally, to control the amount of liquid ammonia or liquid ammonia solution which is to be left on the textile 3 (pick-up), in a range from 0.1 % to 200%. This technical solution allows reducing the amount of ammonia or of liquid ammonia solution present inside vessel 1 and ensures a closer ratio of the liquid ammonia bath, or liquid ammonia solution bath, to the textile product 3. In fact, by adjusting the rotational speed of drum 2, starting from a few dozens of revolutions per minute, the centrifugal force can be changed, which makes it possible to determine the exact percentage of liquid ammonia or liquid ammonia solution to be left on the textile 3 (pick-up). This percentage will affect the desired degree of finishing. A low pick-up of liquid ammonia or liquid ammonia solution by textile 3 (say, 20%) will promote a change on the surface of the cellulosic fibre, improving the wash and wear characteristics of the product, as well as its final touch; conversely, a high pick-up percentage (say, 50%) will promote a change inside the cellulosic fibre, amorphous and crystalline regions, thereby improving the dyes affinity. To ensure even swelling of all of the cellulosic fibres of the textile wound around the drum, with a high pick-up percentage, the rotational speed of drum 2 will be high at the beginning of the centrifugal dispersion of the ammonia liquid through the coils of the textile, but it will decrease slowly until reaching the pre-set speed for a given pick-up. The decrease of the rotational speed and of the relevant centrifugal force will ensure a gradual increase in ammonia pick-up, allowing even treatment across the entire textile product 3 wound around drum 2. In practice, textile 3 is treated with liquid ammonia or with a liquid ammonia solution with a pre-selected pick-up and for a pre-set time period, varying from a few seconds to a few minutes. The cycle can take place at the atmospheric pressure, or below or above it. This process can undoubtedly be used to dye a textile product 3 by means of dyestuffs dissolved in liquid ammonia, said dyestuffs being quick-reaction ones, thanks to the high and even distribution of the bath through the wound-up textile. The ammonia will then be evaporated and the dye will be fixed according to its recipe. Furthermore, this process can be used to dye textile products previously impregnated, with a given pick-up, with liquid ammonia or with a liquid ammonia solution, by subsequent addition of a solution of chosen, compatible dyes.

The treatment with liquid ammonia or with a liquid ammonia solution will increase the volume of many textile fibres, resulting in improved penetration of the dye solution inside them. In the case of cellulosic fibres, the removal of liquid ammonia from the swollen fibres by means of an aqueous solution of compatible dyes will result in a markedly-oriented crystalline crosslinking of the cellulose fibres, whereby the final result will be an excellent colour yield. The ammonia present in the new solution will then be evaporated and recovered, while the dyeing process will be completed according to its recipe.

According to a special embodiment of the process in this invention, impregnation of the textile 3 wound around drum 2 is accomplished by condensation of the ammonia or ammonia mixture from the gaseous to the liquid state, at a pressure above the atmospheric pressure.

It is known that as pressure increases, ammonia condenses accordingly at increasingly higher temperatures, while the energy required for its condensation decreases sensibly. Most advantageously, condensation occurs at a pressure between 2 to 1 13 atmospheres and, preferably, between 5 to 40 atmospheres. The table below shows the ammonia condensation temperatures at different pressures: 1 atm (atmospheric pressure) : - 33° C 4.4 atm : 0° C

10 atm : + 25° C

20 atm : + 50° C 30 atm : + 65° C

40 atm : + 78° C

Critical point 113 atm.

For instance, a solution containing 85% ammonia and 15% water, at the above condensation temperatures, will require a pressure approximately 15% lower than the values indicated above.

The textile product 3, wound around drum 2, is cooled before the cycle starts (even down to temperatures well below 0°), through the effect of the vacuum created by pump 21 and by radiation-induced cooling provided by jacket 15 (whose function can also be performed by an appropriate heat exchanger), through which a cooling liquid can be passed.

In an alternative solution, the textile product 3 can be cooled by passing a flow of nitrogen through the coils. According to another embodiment, cooling of the textile product 3 can be achieved by passing a flow of pressurised air through the coils, said air being cooled down, in turn, by contact with the walls of jacket 15, supplied internally with a cooling liquid. After cooling, all gas will be removed from the textile 3 by means of vacuum pump 21. Vessel 1 will then be brought to the same pressure as that of the outer tank containing the ammonia or ammonia solution, or to a pressure below such pressure, by means of appropriate adjustment valves, in the customary ways.

The difference between the temperature of the textile (say, 0° C) and the condensation temperature (say, 50° C at a pressure of 20 atm) will determine the impregnation of the textile product 3 by condensation of the ammonia or of the ammonia mixture from the gaseous to the liquid state. Changing the inlet pressure of the ammonia gas entering vessel 1 and the temperature of the textile, will cause the impregnation percentage of textile 3 to change accordingly.

Condensation under high pressure of the ammonia or ammonia mixture on the textile product 3 ensures a very fast, even and deep treatment of all fibres in the product wound around drum 2, as well as precise adjustment of the percentage of ammonia, or of liquid ammonia solution, which is to impregnate the entire textile product.

In another embodiment of this intention, impregnation of the textile product 3, wound around drum 2, is accomplished in two subsequent steps.

First step: partial impregnation of textile 3, with a pre-set pick-up, by condensation of ammonia or of an ammonia mixture from the gaseous to the liquid phase, at a pressure above the atmospheric one.

Second step: complete impregnation of textile 3, with a pre-set pick-up, by mechanical centrifugal distribution of liquid ammonia or liquid ammonia solution through all the coils. In yet another embodiment of this invention, impregnation of the textile product 3, wound around drum 2, again takes place in two steps.

First step: partial impregnation of textile 3, with a pre-set pick-up, by mechanical centrifugal distribution of liquid ammonia or liquid ammonia solution through all the coils.

Second step: complete impregnation of textile 3, with a pre-set pick-up, by condensation of ammonia or of an ammonia mixture from the gaseous to the liquid phase, at a pressure above the atmospheric one. It is then necessary to remove the liquid ammonia or liquid ammonia solution, after chemical reaction with the fibre has occurred. As is obvious, increasing the rotational speed of drum 2, up to some thousands of revolutions per minute, increases the centrifugal acceleration imposed on the liquid ammonia, which has a low viscosity (approx. 25% as compared to the viscosity of water) and low surface tension (approx. 50% as compared to water), and so the liquid ammonia is extracted in the liquid state in very high percentages from textile 3. It then returns to tank 8 through duct 14, so as to be re-used. The ammonia vapours generated in the centrifugation phase will be conveyed through duct 13 to a condenser 4, so as to be re-condensed to the liquid state and then sent back to tank 8 through duct 7. The cooling fluid is supplied through the inlet duct 5 and is discharged from condenser 4 through the outlet duct 6, after the heat exchange has been completed. The cycle can take place at the atmospheric pressure, or below or above it.

The removal of liquid ammonia or liquid ammonia solution by centrifugation allows to recover almost all of the ammonia, at absolutely negligible energy costs if compared with the costs of the ammonia recovery systems currently in use. Final removal of all ammonia traces from the textile product 3 must then be accomplished, in order to eliminate any traces of ammonia remaining in the spaces between fibres. For this purpose, steam (water vapour) will be introduced in vessel 1 at a given pressure, through duct 18, and from there, through the distributor 19, located inside drum 2 kept in rotation, the steam will eliminate all ammonia residues from the fibres and will then be discharged from vessel 1 through vent 20, bringing with it the last traces of ammonia.

The vapours containing water and ammonia will be collected in a scrubber located outside the machine.

With an alternative method, the final removal of ammonia can be achieved by washing with water in the liquid state at pre-set pressure and temperature.

The latter will be conveyed inside drum 2, kept in rotation, through duct 22, which conveys the water up to a bar 23, located inside drum 2, running along the entire length of the drum.

The water containing the ammonia traces will then be discharged from the vessel through the discharge device 24 and will then be conveyed to an appropriate support tank 1 ; such NH40H solution can then be treated inside a distillation tower, which will separate the aqueous part from the liquid ammonia, so that the latter can be re-used in the finishing treatment.

In another variation of this invention, which is not illustrated, the liquid ammonia remaining on the textile product 3 after centrifugation, will be removed by rinsing with water, whereby an ammonia hydroxide solution (NH4OH) will be formed, to which a diluted sodium hydrate (NaOH) solution will be added. As the ammonia hydroxide solution (NH4OH) is a chemically weak base, while the sodium hydrate (NaOH) solution is a strong one, a new balance will be created inside the solution, whereby a large amount of ammonia (NH3) in the gaseous form will be released; this, in turn, will be conveyed through duct 13 to condenser 4, where it will be converted into liquid ammonia, ready to be re-used. The bath containing mainly sodium hydrate and the subsequent washings will then be discharged through the discharge device 24.

At this point, it might be necessary to cool down vessel 1 by means of a cooling fluid, such as, for instance, cold water, which will be made to flow in and out of jacket 15 through ducts 17. Vessel 1 can now be opened and, depending on the construction methods chosen, the drum can be unloaded from vessel 1 or, alternatively, the textile can be unwound from said vessel 1. The device is now ready to start a new cycle, either by loading the drum 2 - with the textile product 3 wound around it - into vessel 1 , or by winding the textile product 3 around drum 2 while the latter is still inside vessel 1. The choice of whether to leave the drum inside the vessel or to remove it and then fit it back in said vessel will be dictated by constructional and functional factors. As is obvious, the textile product 3 treated with liquid ammonia or with a liquid ammonia solution, still wound around the drum 2, can then be dyed through the application of known dyeing recipes based on aqueous solutions; dyeing can be accomplished using dyestuffs in aqueous solutions, followed by washing.

It is also obvious that the textile product 3, wound around drum 2, can be washed with water or steam (water vapour) at atmospheric pressure, or above it, prior to treatment with liquid ammonia or with a liquid ammonia solution. It also as obvious that the textile product 3, wound around drum 2, can be washed with a solvent such as perchloroethylene, trichloroethylene, freon or other solvents, prior to the treatment with liquid ammonia or with a liquid ammonia solution. In these cases, the machine needs to be completed with a supplementary circuit for washing with water/steam, or with a circuit for washing with solvents complete with distillation system, or with a circuit suitable for dyeing, followed by washing. After the dyeing, washing or final water- washing steps, the textile product 3, still wound around drum 2, can be dried inside the machine, under pressure and at a temperature above 100° C, through the forced passage of air, or of another gas, heated by contact with the heat exchanger 15, supplied with a heating fluid. The resulting vapours will be conveyed into exchanger 4, to be liquefied and then sent to an auxiliary tank. Drying under pressure, at a temperature above 100° C, confers excellent final dimensional stability to the textile product 3, especially in the case of cellulosic fibres previously treated with liquid ammonia. When not used for liquid ammonia treatments, machine 1 can be used for the known water/steam washing operations, for washing with solvent, carbonising, vaporization, dyeing, caustic soda treatment, setting, impregnation of textiles with chemical products, drying under pressure or for various combinations of the said operations. However, it must be noted that the process and relevant device described herein have been described purely by way of a non-limiting example. In particular, not all of the above-mentioned ammonia removal systems need to be present (centrifugal action, heating, final removal of ammonia by steam or by water in the liquid state). In fact, depending on the type of processing for which the process herein is to be implemented, or depending on the needs of the user, just one or two systems for the removal of liquid ammonia or liquid ammonia solution may be needed.

The tests carried out showed that the discontinuous process referred to in this invention is capable to ensure a highly uniform treatment, through the use of liquid ammonia or of a liquid ammonia solution, and very high outputs. In particular, the entire work cycle can be completed in a limited time of approximately 15 minutes.

The process referred to in this invention can be used to treat woven fabrics, non-woven fabrics, knitted fabrics, yarns, slivers and tow consisting of various types of different fibres, without resulting in unwanted shrinkage of the textile product 3. As for the chemical product used in the process, this can be, depending on the case, either 100% pure liquid ammonia, or a liquid ammonia solution, with an adjustable pick-up range of between 0.1 % to 200% relative to the weight of the textile product 3. Hereinafter is a non-limiting list of finishing treatments:

In the case of cotton fabrics, the treatment with a solution containing 90% ammonia and 10% concentrated caustic soda proved effective to obtain excellent dyeing performances and sheen; pick-up 100%.

In the case of flax yarns, the treatment with liquid ammonia proved effective to improve the mechanical resistance of yarns, to increase weaving output as well as to ensure excellent wrinkle-free effect of the final clothes; pick-up 50%. In the case of cotton knitwear, the treatment with liquid ammonia proved effective in order to improve the pilling resistance as well as the touch and dimensional stability of the fabric; pick-up 40%.

In the case of a woollen fabric wound up alongside with a blanket, the treatment with an ammonia solution containing 15% water proved effective to ensure non-felting properties and permanent setting of the fibres. After centrifugation, the wool textile item was subjected to steaming at 120° C for two minutes; pick-up 100%.

In the case of a nylon 6 fabric, the treatment with liquid ammonia proved effective to improve the touch as well as the dyeing performance; pick-up 10%.

In the case of a silk fabric, the treatment with liquid ammonia proved effective to improve the look of the fabric, as well its final touch; pick-up 5%. In the case of a cotton fabric previously treated with flame-resistant resins and then dried, the treatment with liquid ammonia proved effective in order to achieve complete crosslinking of the resins; pick-up value of approx. 0.1 %.

In the dyeing process, a solution consisting of ammonia and selected dyes dissolved in it, or an ammonia solution with selected dyes and chemicals dissolved in it, or else a solution consisting of ammonia, water and dyes proved effective; varying pick-up value, up to 200%. In the process referred to in this invention no ammonia leakage occurs, since vessel 1 is essentially a closed machine and a very safe one. Said vessel 1 is also simple from a constructional viewpoint, as well as easy to manage and with very limited dimensions. In practice, vessel 1 will be capable of treating the textile product 3 at atmospheric pressure, or below or above the atmospheric pressure. It should also be considered that the power installed in order to recover the ammonia or the ammonia solution is very limited, thanks to the extremely high percentage of liquid that is mechanically removed from the textile product 3. Finally, it should be noted that the various embodiments of the invention herein have been described purely by way of a non-limiting example. In practice, other constructional solutions can be adopted, in terms of the diameter of drum 2, of the peculiar technical/constructional solution of drum 2 around which the textile product 3 is wound (for instance, two rotors can be installed on the two heads of pierced drum 2, which will cause a high stream of gas to pass through all the coils of the rolled up textile 3, either inside out or vice-versa, while drum 2 is kept in rotation), as well as in terms of the various heating systems (radiation, contact, infrared, passage of pre-heated gas, microwaves), pressure and discharge systems, type of condenser used, type of cooling system, final elimination of all ammonia traces from the textile by water vapour or by nitrogen in the gaseous form, or else the possibility to cause the vessel to rotate at the same speed as the drum inside it, without falling outside the scope of the patent itself.

Claims

1. THE PROCESS for the treatment with liquid ammonia or with a liquid ammonia solution of woven fabrics, non-woven fabrics, knitted fabrics, yarns, slivers or tow based on cellulosic, animal, artificial or synthetic fibres or relatively mixed ones, the said process being characterised in that the textile products (3) are impregnated with an adjustable percentage of between 0.1 % and 200% by their weight, said textiles being wound around the outside of a drum (2), either alone or in conjunction with a blanket, so as to prevent unwanted modifications of their dimensions.

2. THE PROCESS, according to claim 1 , characterised in that the adjustment of the impregnation percentage of the textile product (3) is achieved by mechanical centrifugal distribution of the liquid ammonia or liquid ammonia solution across all the fibres, as the rotational speed of the drum (2) can be adjusted from a few dozens of revolutions per minute to a few thousands.

3. THE PROCESS, according to claim 2, characterised in that the mechanical centrifugal distribution of the liquid ammonia or liquid ammonia solution across all the textile product (3) takes place at the atmospheric pressure, or below or above the atmospheric pressure.

4. THE PROCESS, according to claim 1 , characterised in that the impregnation of the textile product (3) wound around the drum (2) occurs by condensation, at a pressure above the atmospheric pressure, of the ammonia or of an ammonia mixture from the gaseous to the liquid state.

5. THE PROCESS, according to claim 4, characterised in that the condensation takes place at a pressure adjustable from 2 to 1 13 atmospheres and, to advantage, from 5 to 40 atmospheres.

6. THE PROCESS, according to claim 1, 2 and 4, characterised in that the textile product (3) wound around the drum (2) is cooled down prior to treatment with liquid ammonia or with a liquid ammonia solution.

7. THE PROCESS, according to claim 1 , 2 and 4, characterised in that the partial or complete removal of the liquid ammonia or liquid ammonia solution, after reaction, from the textile product (3) wound around the drum (2) is achieved by centrifugation of the liquid ammonia, or liquid ammonia solution, as the rotational speed of the drum (2) can be adjusted up to a few thousand revolutions per minute.

8. THE PROCESS, according to claim 7, characterised in that the partial or complete removal of the liquid ammonia, or of the liquid ammonia solution, from the textile product (3) wound around the drum (2) takes place at the atmospheric pressure, or below or above the atmospheric pressure.

9. THE PROCESS, according to one or more of the previous claims, characterised in that the partial or complete removal of the liquid ammonia, or of the liquid ammonia solution, from the textile product (3) is effected by washing with water the said textile (3) wound around the drum (2), under controlled pressure and temperature conditions.

10. THE PROCESS, according to claim 9, characterised in that the partial or complete removal of the liquid ammonia, or of the liquid ammonia solution, from the textile product (3) is effected by washing with water, followed by admission of a sodium hydrate solution, or of another chemically strong basic solution, while the textile product (3) is wound around the drum (2).

11. THE PROCESS, according to one or more of the previous claims, characterised in that the partial or complete removal the liquid ammonia, or of the liquid ammonia solution, from the textile product (3) wound around the drum (2) is effected by treating the said product with steam (water vapour) at pre-set temperature and pressure conditions.

12. THE PROCESS, according to one or more of the previous claims, characterised in that it foresees, prior to treatment with liquid ammonia or with a liquid ammonia solution, a water- or steam- washing step at atmospheric pressure/temperature, or above it.

13. THE PROCESS, according to one or more of the previous claims, characterised in that it foresees, prior to treatment with liquid ammonia or liquid ammonia solution, a washing step with a solvent such as perchloroethylene, trichloroethylene, freon or other solvents.

14. THE PROCESS, according to one or more of the previous claims, characterised in that it foresees, after the water- washing step, drying of the textile product (3) wound around the drum (2), at a pressure above the atmospheric pressure and at a temperature above 100° C.