PROCESS AND PLANT FOR RECYCLING FABRICS

Abstract

In a process for recycling waste fabric comprising elastomeric material a polar solvent is flowed through the waste fabric in an extraction chamber to dissolve and remove the elastomeric material; the solvent is evaporated in an evaporation chamber and condensed to be sent to a solvent collection tank or back to the extraction chamber; the dissolved elastomeric material is eventually recovered from the concentrated polar solvent.

Claims

1. A process for recycling waste textile (2) containing elastomeric material, preferably elastomeric fibers, (1), comprising the step of extracting said elastomeric material from said waste textile (2), characterized in comprising the following steps: a) providing an amount of said waste textile in an extraction chamber (4), b) circulating a solvent (3) through said extraction chamber (4) and said waste textile (2) to dissolve and remove the elastomeric material from the waste textile; c) feeding the solvent exiting said extraction chamber (4) back to the extraction chamber to increase the content of elastomeric material (1) dissolved in the solvent; d) evaporating at least part of the solvent obtained in step c) in an evaporation chamber (6) to increase the amount of elastomeric material in the solvent; e) condensing the evaporated solvent (3) in at least one condensation chamber (7); f) feeding at least part of the condensed solvent (3) directly or indirectly to said extraction chamber (4); g) repeating steps b)-f); h) removing said concentrated solution (3′) from said evaporation chamber (6) to recover the elastomeric material (1).

2. A process according to claim 1, wherein the solvent exiting said extraction chamber (4) is filtered, preferably by a filter means (40) housing said waste textile (2) in said extraction chamber (4)

3. A process according to claim 1, wherein said textiles are in a static condition during said process.

4. A process according to claim 1, wherein at least said evaporation and condensation steps (d, e) are carried out under reduced pressure.

5. A process according to claim 1, comprising the step of heating said extraction chamber (4).

6. A process according to claim 1 wherein at least in step c) said solvent is re-circulated by means of a pump (9).

7. A process according to claim 4, wherein the pressure in said evaporation chamber (6) is lower than the pressure in said extraction chamber (4) and the solvent containing dissolved elastomeric material is transferred from said extraction chamber to said evaporation chamber (6) by fluidically connecting said chambers (4; 6) together.

8. A process according to claim 1, wherein said solvent is or comprises dimethylacetamide (DMAC).

9. A process according to claim 8, wherein the solvent temperature in said extraction chamber is in the range of 65-80° C., preferably 70-75° C.

10. A process according to claim 1, further comprising a step to remove and recover solvent from said waste textile, preferably said solvent recovering step being selected from pressing, squeezing, spinning or centrifuging said waste textile.

11. A plant to carry out a process according to claim 1, characterized in that it comprises an extraction chamber (4) configured to contain a waste textile (2) containing an elastomeric material and a solvent (3) suitable to dissolve said elastomeric material, said extraction chamber (4) preferably comprising at least a heater (8); circulation means (9) to circulate said solvent at least once through said extraction chamber (4); an evaporation chamber (6) configured to collect the solvent containing dissolved elastomeric material (1) and to evaporate at least part of said solvent (3); at least one condensation chamber (7) comprising a cooling system (10) configured to condensate said solvent evaporated in said evaporation chamber (6) and to feed said condensed solvent back to said plant.

12. A plant according to claim 11, wherein the extraction chamber (4) comprises filtering means, preferably a filtering basket (40) to house said waste textile (2).

13. A plant according to claim 11, wherein at least part of said plant is connected or connectable to a reduced pressure circuit (71), said circuit preferably including a vacuum pump (70), wherein said reduced pressure circuit (71) is connected or connectable to said at least one condensation chamber (7) that is connected or connectable to said evaporation chamber.

14. A plant according to claim 11, wherein said circulation means comprises a re-circulating circuit (42) and a pump (9) for circulating solvent in and out of said extraction chamber (4).

15. A plant according to claim 11, further comprising a solvent collecting tank (20) to contain said solvent (3), said solvent collecting tank (20) being connected or connectable to said extraction chamber (4) and to said condensation chamber (7).

16. A plant according to claim 15, wherein said condensation chamber (7) is connectable to said solvent collecting tank (20).

Description

[0045] Further aspects and advantages in accordance with the present disclosure will be discussed more in detail with reference to the enclosed drawings, given by way of non-limiting example, wherein:

[0046] FIG. 1 shows a schematic representation of a plant according to a possible embodiment of the present invention; and

[0047] FIG. 2 is a flow chart illustrating an extraction process according to the invention.

[0048] With reference to the exemplary embodiment of FIG. 1, a textile recycling plant 100 comprises an extraction chamber 4 configured to contain a waste textile 2 that is an elastic textile, i.e. a textile comprising an elastomeric material 1. Extraction chamber 4 is configured to receive and contain a solvent 3 suitable to dissolve the elastomeric material 1. The extraction chamber 4 is connected to a re-circulating circuit 42 in which the solvent 3 exiting the extraction chamber from chamber outlet conduit 43 can be recirculated to the extraction chamber 4 through chamber inlet conduit 44 by circulating means 9. Preferably said circulating means 9 is a pump. Valves V are located on the circuit ducts to control the flow of solvent.

[0049] In the embodiment of FIG. 1, the extraction chamber 4 is connected to an evaporation chamber 6 through conduit 41. The extraction chamber 4 is connected to a condensation chamber 7 through conduit 72. The extraction chamber 4 is also connected to a solvent collection tank 20 through a conduit 201. Suitable valves V are provided on the cited conduits to selectively direct the flow of solvent to the required component of the plant.

[0050] The process of the invention preferably provides for the solvent containing the extracted elastomeric material to be filtered to remove fibers of other materials than the elastomeric one, e.g. to remove cotton fibers. Preferably the extraction chamber 4 comprises filtering means, such as a mesh filter basket 40, to contain the waste textile 2 comprising the elastomeric material 1.

[0051] The mesh filter basket 40 is provided with openings not shown in FIG. 1, which allow the solvent to flow inside the entire volume of the extraction chamber 4 and at the same time to keep the waste textile 2 inside the mesh filter basket 40. In a preferred embodiment the filtering basket is in stainless steel or is a non-woven fabric that lines it internally and acts as a filter; the non-woven fabric is resistant to the solvent used in the extraction chamber and may be used alone or may be fixed to or housed by a metal stricter such as filter basket 40 so as to retain any fiber or particles that detach from the textile material.

[0052] According to a possible aspect, the extraction chamber 4 comprises at least a heater 3. Said heater 3, during the process, heats the solvent and the waste textile 2 that are located in the extraction chamber 4 to facilitate extraction of the elastomeric material from the waste textile.

[0053] The plant further comprises an evaporating chamber 6. Said evaporating chamber 6 is configured to collect, i.e. to receive, the solution 3′ containing solvent 3 and dissolved elastomeric material 1 that is obtained by recirculation of solvent in chamber 4 and to evaporate at least part of the solvent from the solution 3′ to recover solvent 3 to be used in the extraction step. As previously mentioned evaporation chamber 6 is connected to extraction chamber 4 by conduit 41.

[0054] According to a possible aspect, the evaporating chamber 6 comprises stirring means, e.g. a mixer 66. Typically, as known in the art, a mixer 66 comprises a rotating rod 61 and a plurality of protrusions 62. The rotation of the protrusions 62 inside solution 3′ maximises the evaporation of solvent 3 from the same. Evaporation chamber 6 is also provided with heating means to bring the solvent therein contained, preferably under reduced pressure, to its boiling point, as below detailed.

[0055] In order to recover the evaporated solvent, the plant further comprises at least one condensation chamber 7. The evaporating chamber 6 is fluidically connected to condensation chamber 7 through a duct 60. In the preferred embodiment shown in the figures the plant is provided with two condensation chambers 7a, 7b arranged and connected in series.

[0056] The condensation chamber 7 comprises a cooling system 10 configured to condensate the solvent evaporated from solution 3′ housed in the evaporation chamber 6 and to feed through conduit 72 the condensed solvent to at least one of extraction chamber 4 and a solvent collection tank 20. In other words, the solvent 3 in the condensation chamber reaches the dew point allowing the solvent to condense and to be fed back to the extraction step (if the process is operated) in the extraction chamber 4 or to a solvent collection tank 20.

[0057] In the shown embodiment the plant is connected to a reduced pressure circuit 71 including a vacuum pump 70 and a separator element 75 in order to collect the solvent 3 which might flow back in the extraction chamber 4 or in the solvent collection tank 20 (batch process). Preferably, the vacuum circuit is connected to the condensation chamber that is connected to the evaporation chamber. Thus, at least evaporation chamber 6 and condensation chamber(s) 7 are kept at a reduced pressure during the invention process.

[0058] Advantageously, the reduced pressure circuit 71 is connected to the at least one condensation chamber 7 through conduit 80; in the embodiment of FIG. 1, which includes condensation chambers 7 and 7a, vacuum circuit 71 is connected to the end portion of chamber 7a, so as to condensate all the evaporated solvent in the two chambers before it reaches the end of the condensation chambers system.

[0059] At least the major components of the plant, i.e. extraction chamber 4, evaporation chamber 6, condensation chambers 7,7a,7b and solvent collection tank 20, are provided with ducts and valves Av to connect the plant to the atmosphere when a reduced pressure in the plant is not required.

[0060] As above mentioned, preferably the plant further comprises a solvent collecting tank 20 to store solvent 3. Said solvent collecting tank 20 is connected to the extraction chamber 4 thought a conduit 74,201 and is connected to the evaporation chamber 6 through a conduit 75. According to a possible embodiment, the condensation chamber(s) 7 is/are connected to the solvent collecting tank 20 through a conduit 202 provided with valves to direct the solvent flow either to chamber 20 or to extraction chamber 4. Preferably, the stored solvent 3 in the solvent collecting tank 20 can be directed to the extraction chamber 4 through conduits 74, 201 under reduced pressure through the reduced pressure circuit 71 and vacuum pump 70.

[0061] The invention further includes a process for recycling waste textile 2 containing elastomeric material; the elastomeric material generally is in the form of fibers in the core of yarns, the yarns usually being combined in a fabric. The fabric may be treated in a known way, e.g. by shredding or cutting into small pieces, or it may be left at least in part in its original garment form, e.g. as a pair of pants, possibly after removal of parts such as plastic labels or zippers, metal parts etcetera.

[0062] Initially, in step a), an amount of waste textile 2 is loaded into extraction chamber 4, which is preferably comprising a filter means such as a metal basket 40 and a non-woven fabric to house the waste textile 2. Preferably, the textile content of the elastomeric material is known, so as to estimate the final amount of material that can be extracted and the process conditions.

[0063] In subsequent step b), as previously discussed, solvent 3 is fed to chamber 4 and is passed through the extraction chamber to dissolve and remove the elastomeric material 1 from the waste textile 2. A preferred solvent for the elastomeric materials is DMAC. In a preferred embodiment the plant is provided with a means to feed the solvent into the extraction chamber, through the waste textile and out of chamber 4 in a controlled flow; such a flow is preferably obtained with a pump 9 that forces the solvent along the required path.

[0064] In step c) the solvent 3 that exits the extraction chamber 4 through outlet duct 43 is directed along re-circulating circuit 42 to flow back to the extraction chamber 4 through inlet duct 44 at least once to extract more elastomeric material and increase its content in the solvent. In other words, the recirculation of the solvent through circuit 42 allows to maximise the concentration of dissolved elastomeric material 1 in the solvent.

[0065] During the extraction process at least a part of the plant, namely the evaporation chamber and the condensation chambers, is normally kept under reduced pressure by connecting the plant to circuit 71. Suitable pressure values in the plant, i.e. chambers 4, 6 and 7, is about 20 to 200 mBar. Advantageously the reduced pressure will lower the boiling temperature of the solvent to facilitate evaporation of the solvent in step d) so as to reduce or prevent degradation of the extracted polymers.

[0066] To enhance extraction of the elastomeric polymer material, the extraction chamber 4 is heated. According to a possible aspect the solvent 3 is dimethylacetamide DMAC and the temperature in the extraction chamber 3 is in the range of 65-80° C., preferably 70-75° C. The extraction chamber is normally not connected with reduced pressure circuit 71. In a preferred embodiment, in order to transfer solvent containing the extracted elastomers from extraction chamber 4 to evaporation chamber 6, chamber 4 is connected to chamber 6 that, as above discussed, is under reduced pressure: once the two chambers are connected through duct 41 the liquid content of chamber 4 will be transferred to chamber 6.

[0067] Solvent transfer from solvent reservoir 20 to extraction chamber 4 may also be carried out by temporarily reducing pressure in chamber 4 before connecting it with reservoir 20. In general, apart from using pump 9 for circulating solvent in and out of the extraction chamber, the polar solvent is transferred to various parts of the plant by using a difference in pressure between said plant parts.

[0068] According to a possible aspect, the solvent 3 exiting the extraction chamber 4 is filtered through the mesh filter basket 40. In other words, said filtering allows to keep the waste textile 2 inside the mesh filter basket 40 during step c) allowing only the solvent 3 to exit the extraction chamber 4 through the outlet 43, the re-circulating circuit 42 and flow back to the extraction chamber 3 through the inlet 44 while keeping the waste textile 2 inside the extraction chamber 4.

[0069] Once the solvent, containing the elastomeric material 1 extracted as described at step c), has been re-circulated through the textile material enough times, i.e. for a time long enough to result in the required degree of extraction of the elastomeric material, it is directed through the conduit 41 to the evaporation chamber 6. In chamber 6 at least part of the solvent evaporates to increase the concentration of the elastomeric material 1 in the solution 3′ present in evaporation chamber 6.

[0070] As above mentioned, evaporation and condensation steps are preferably carried out under reduced pressure thanks to reduced pressure circuit 71 and vacuum pump 70. The solvent 3 in the evaporation chamber 6 can thus be heated to a temperature value that is below the its boiling point at atmospheric pressure, preferably below 100° C., to prevent degradation of the elastomeric material 1.

[0071] In step e) the solvent vapour flow along the conduit 60 to condensation chambers 7 where the vapour condenses. In the embodiment shown in FIG. 1 there are provided two condensation chambers 7a and 7b that are arranged and connected in series. The condensed solvent 3 is fed to the extraction chamber 4 through conduit 72; alternatively, the liquid solvent may be fed to solvent reservoir 20 through conduit 202 to be stored there or to be pumped back into extraction chamber 4 via conduit 74.

[0072] In a possible embodiment, as schematically shown in FIG. 2, the solvent is recirculated through the extraction chamber until a required concentration of elastomeric material is detected before sending it to evaporation chamber 6. In a possible embodiment, steps b)-f) may be preferably repeated for at least 3 times or for 20-30 minutes.

[0073] Finally, in step h) the concentrated solution 3′ is removed from the evaporation chamber 6 and the elastomeric material 1 in the evaporation chamber 6 is recovered in a way known per se. For example, the extracted material may be precipitated from the solution 3′ of DMAC and elastomeric material by mixing the solution with water. The recovered elastomeric material may be recycled by adding it to virgin material before wet or dry spinning. The recovered material may be further treated, e.g. to remove contaminants, if any.

[0074] At the end of the extraction process it may be carried out a further step to remove and recover solvent from said waste textile, preferably said solvent recovering step is selected from pressing, squeezing, spinning or centrifuging the solvent-soaked waste textile.

[0075] The invention will be further illustrated by reference to the following non limiting examples.

EXAMPLE 1

[0076] 2 kg of fabric (79% PES-21% Elastane) were prepared by cutting the fabric in pieces, preferably cut 5×5 cm. The total amount of elastomeric material in the 2 kg of fabric was about 420 grams. The fabric was housed in a stainless-steel filtering basket. The 2 kg of fabric were put in an extraction chamber heated to 70-73° C. and subjected to re-circulating of DMAC for 20 minutes. During re-circulation the solution exiting was sent to an evaporation chamber heated at 85° C. at 40 mbar; the solvent was evaporated and stored in a solvent collection tank (20). At the end of the extraction process the fabric was pressed to remove the remaining solvent that was added to the solution in the evaporation chamber. The elastomeric material was precipitated from DMAC with water and dried; the recovered amount was 414.54 grams, providing a yield of 98.7% of the initial material. The recovered material can be mixed with virgin elastomeric material in an amount of 10-30% and wet spun into elastomeric fibers.

EXAMPLE 2

[0077] 1.8 kg of fabric (% 89 PES-% 11 Elastane) were prepared by cutting the fabric in pieces, preferably cut 5×5 cm. The total amount of elastomeric material in the 1.8 kg of fabric was about 198 grams. The fabric was housed in a stainless-steel filtering basket. The 1.8 kg of fabric were put in an extraction chamber heated to 70-73° C. and subjected to re-circulating of DMAC for 20 minutes. During re-circulation the solution exiting was sent to an evaporation chamber heated at 85° C. at 40 mbar; the solvent was evaporated and stored in a solvent collection tank (20) (batch process). At the end of the extraction process the fabric was pressed to remove the remaining solvent that was added to the solution in the evaporation chamber. The elastomeric material was precipitated from DMAC with water and dried; the recovered amount was 194.04 grams, providing a yield of 98.18% of the initial material. The recovered material can be mixed with virgin elastomeric material in an amount of 10-30% and wet spun into elastomeric fibers.

EXAMPLE 3

[0078] 2 kg of fabric (% 70 Cotton-% 21 PES-% 9 Elastane) were prepared by cutting the fabric in pieces, preferably cut 5×5 cm. The total amount of elastomeric material in the 2 kg of fabric was about 180 grams. The fabric was housed in a stainless-steel filtering basket. The 1.8 kg of fabric were put in an extraction chamber heated to 70-73° C. and subjected to re-circulating of DMAC for 20 minutes. During re-circulation the solution exiting was sent to an evaporation chamber heated at 85° C. at 40 mbar; the solvent was evaporated and stored in a solvent collection tank (20) (batch process). At the end of the extraction process the fabric was pressed to remove the remaining solvent that was added to the solution in the evaporation chamber. The elastomeric material was precipitated from DMAC with water and dried; the recovered amount was 176 grams, providing a yield of 97.7% of the initial material. The recovered material can be mixed with virgin elastomeric material in an amount of 10-30% and wet spun into elastomeric fibers.

EXAMPLE 4

[0079] 2 kg of fabric (% 79 PES-% 21 Elastane) were prepared by cutting the fabric in pieces, preferably cut 5×5 cm. The total amount of elastomeric material in the 2 kg of fabric was about 420 grams. The fabric was housed in a stainless-steel filtering basket. The 2 kg of fabric were put in an extraction chamber heated to 70-73° C. and subjected to re-circulating of DMF for 20 minutes. During re-circulation the solution exiting was sent to an evaporation chamber heated at 70° C. at 40 mbar; the solvent was evaporated and stored in a solvent collection tank (20) (batch process). At the end of the extraction process the fabric was pressed to remove the remaining solvent that was added to the solution in the evaporation chamber. The elastomeric material was precipitated from DMF with water and dried; the recovered amount was 414.2 grams, providing a yield of 98.6% of the initial material.