GB2623761A - Method of separating polyester and cotton - Google Patents
Method of separating polyester and cotton Download PDFInfo
- Publication number
- GB2623761A GB2623761A GB2215744.0A GB202215744A GB2623761A GB 2623761 A GB2623761 A GB 2623761A GB 202215744 A GB202215744 A GB 202215744A GB 2623761 A GB2623761 A GB 2623761A
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- United Kingdom
- Prior art keywords
- fabric
- polyester
- cotton
- fibers
- suspension
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229920000742 Cotton Polymers 0.000 title claims abstract description 110
- 229920000728 polyester Polymers 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 67
- 239000004744 fabric Substances 0.000 claims abstract description 131
- 239000000835 fiber Substances 0.000 claims abstract description 114
- 239000000725 suspension Substances 0.000 claims abstract description 42
- 239000006260 foam Substances 0.000 claims abstract description 32
- 239000012530 fluid Substances 0.000 claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000010924 continuous production Methods 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 238000010923 batch production Methods 0.000 claims description 4
- 239000002736 nonionic surfactant Substances 0.000 claims description 3
- 230000005587 bubbling Effects 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 27
- 238000000926 separation method Methods 0.000 description 21
- 239000000463 material Substances 0.000 description 18
- 239000007789 gas Substances 0.000 description 15
- 239000000047 product Substances 0.000 description 14
- 239000004745 nonwoven fabric Substances 0.000 description 9
- 238000010338 mechanical breakdown Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 239000002699 waste material Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000000945 filler Substances 0.000 description 4
- 238000009413 insulation Methods 0.000 description 4
- 239000002759 woven fabric Substances 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 239000000470 constituent Substances 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000010409 ironing Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 206010011906 Death Diseases 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005276 aerator Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000012223 aqueous fraction Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 150000001875 compounds Chemical group 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000009950 felting Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000003698 laser cutting Methods 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000012958 reprocessing Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000010025 steaming Methods 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 239000000126 substance Chemical group 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000009941 weaving Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
- D01G5/00—Separating, e.g. sorting, fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/0084—Enhancing liquid-particle separation using the flotation principle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/01—Separation of suspended solid particles from liquids by sedimentation using flocculating agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/04—Disintegrating plastics, e.g. by milling
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
- D01G11/00—Disintegrating fibre-containing articles to obtain fibres for re-use
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
- B29B2017/0203—Separating plastics from plastics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
- B29B2017/0213—Specific separating techniques
- B29B2017/0217—Mechanical separating techniques; devices therefor
- B29B2017/0248—Froth flotation, i.e. wherein gas bubbles are attached to suspended particles in an aerated liquid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/04—Disintegrating plastics, e.g. by milling
- B29B2017/0424—Specific disintegrating techniques; devices therefor
- B29B2017/0476—Cutting or tearing members, e.g. spiked or toothed cylinders or intermeshing rollers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2001/00—Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/726—Fabrics
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Environmental & Geological Engineering (AREA)
- Mechanical Engineering (AREA)
- Textile Engineering (AREA)
- Preliminary Treatment Of Fibers (AREA)
- Nonwoven Fabrics (AREA)
Abstract
A method of separating polyester and cotton from a polyester/cotton blended fibre fabric 101 comprises shredding the blended fibre fabric into a shredded fabric 102, adding a fluid 103, and mechanically working the fabric. A fabric suspension 105 is formed, and an aqueous flocculant solution 106 is added to the fabric suspension 105. A gas 107 is bubbled through the fabric suspension 105 thereby generating a foam 108. The foam 108 is then removed from the fabric suspension 105. Polyester fibres of the polyester/cotton blended fibre fabric are suspended in the foam and cotton fibres of the polyester/cotton blended fibre fabric remain in the suspension 105.
Description
Method of Separating Polyester and Cotton [0001] This invention relates to a method of separating polyester and cotton from a polyester/cotton blended fiber fabric.
BACKGROUND
[0002] Reprocessing of materials for reuse is an increasingly important issue. Changes in legislation has increased the obligation of companies to include recycled material in their products. Furthermore, to reprocess materials for reuse is simply the right thing to do and there must be a move away from a throwaway society to a circular and sustainable economy.
[0003] Materials to reprocess and reuse are normally sourced from consumer or industrial waste streams. Due to the shift to increase the amount of recycled or reprocessed material in products many of the easy-to-reprocess waste streams are over exploited. Other, more difficult to process, waste streams must therefore be explored. Companies are therefore searching for such waste streams to exploit.
[0004] One particular waste stream, and material, that is of interest are polyester and cotton blended fiber fabrics. These are woven or non-woven fabrics that comprise cotton and polyester in any proportion. Such fabrics are well known and popular due to their breathability, durability, and ability to be less prone to wrinkling (therefore requiring less ironing). However, the combination of polyester and cotton fibers in these fabrics make them hard to repurpose. The very nature of fabrics requires the close mechanical intertwining of the materials whether that is through making individual threads (spinning individual cotton and polyester fibers together to form a thread), weaving of wholly cotton and wholly polyester threads together, or non-woven methods such as felting. All of these mechanically bind the polyester with the cotton and while producing a strong coupling between the fibers resulting in a durable product. This, however, hinders later separation and purification of the materials for repurposing, as these strong mechanical bonds are hard to break down.
[0005] Previous methods of separating polyester cotton blended fabrics back into bulk polyester and bulk cotton fibers are energy intensive and harsh. These methods require relatively high temperatures and environmentally unfriendly chemistry to, for example, break down the polyester back into monomers, then extract these from the cotton. Such methods can degrade the integrity of the fibers limiting the options for subsequent reuse. Repurposing of polyester cotton blended fiber fabrics is therefore not yet seen as economical or environmentally friendly. However, this is juxtaposed with the volume of used polyester cotton blended fiber fabrics available for repurposing with, taking just the hospitality industry for example, producing a vast amount of end-of-life polyester cotton fabrics from bed sheets, tablecloths, and napkins. When also considering the popularity of these fabrics in other industries such as clothing and homeware the amount of fabric available for repurposing is extensive.
BRIEF SUMMARY OF THE DISCLOSURE
[0006] In accordance with the present invention there is provided a method of separating polyester and cotton from a polyester/cotton blended fiber fabric. The method comprises shredding the blended fiber fabric into a shredded fabric; mechanically working the fabric; adding a fluid to the shredded fabric, forming a fabric suspension; adding an aqueous flocculant solution to the fabric suspension; bubbling a gas through the fabric suspension thereby generating a foam; removing the foam from the fabric suspension; wherein polyester fibers of the polyester/cotton blended fiber fabric are suspended in the foam and cotton fibers of the polyester/cotton blended fiber fabric remain in the suspension.
[0007] Suitably, the fiber fabric is a woven fiber fabric and, optionally, the fiber fabric comprises a plurality of polyester fibers and plurality of cotton fibers.
[0008] Preferably, the polyester/cotton blended fiber fabric comprises any of: threads formed of only cotton fibers; threads formed of only polyester fibers; threads formed of cotton fibers and polyester fibers.
[0009] The mass ratio of polyester fibers to cotton fibers may be in the range 1:99 to 99:1 cotton:polyester, and optionally 50:50, 70:30, or 80:20 cotton:polyester, which corresponds to the most common blend ratios of cotton polyester fabrics.
[0010] Preferably, shredding the blended fiber fabric comprises shredding until the fibers not greater than 1mm in length, and optionally in the range 0.6mm to 0.8mm. This facilitates mechanically working the fabric. Longer fibers outside of this range can tangle and aggregate hindering fiber separation. Shorter fibers outside of this range have limited used in later processes as they are too small to be used in conventional processes. Furthermore, such shorter fibers are hard to obtain and require finer or longer shredding times to obtain, thereby increasing energy use and cost.
[0011] Suitably the weight ratio of flocculant to dry fiber mass is in the range 1:99 to 10:90, preferably 5:95, ensuring sufficient flocculant is present to achieve successful separation while also minimizing excess flocculant thereby improving efficiency and reducing cost. The flocculant may be a flocculant, and/or preferably a non-ionic surfactant. As such there should be an affinity for polyesters to mix with the flocculant such that the polyester fibers are readily trapped in subsequent foam formed in the solution for easy separation.
[0012] Preferably, the fabric suspension is mechanically worked for a period of time (such as, but not limited to around 50 minutes) in order to obtain a homogenous solution of shredded fabric and aqueous flocculant solution, ensuing good separation of all the fibers in solution ready for separation.
[0013] Optionally, liquid can later be removed from the suspension to produce separated cotton fibers. This can be achieved through filtering, sieving, evaporative drying, centrifuge, or any standard separation method to obtain bulk cotton fibers from the solution, absent the polyester fibers.
[0014] Suitably the method further comprises washing the polyester/cotton blended fiber fabric.
This wash step would ensure that the fabric is free of contaminants such as unknown detergent residue originating from previous use of the fabric. This optional wash also provides an opportunity to provide a dopant or additive if desired.
[0015] Optionally, the method is a batch process allowing small amounts of fabric to be processed and separated into the constituent polyester fibers and cotton fibers. Such batch processing may be useful to handle fabrics originating from discrete waste streams or to separate fabric properties, such as fabrics dyed a particular color.
[0016] Preferably, the method is a continuous process in order to handle significant volumes of fabric and to separate the constituent polyester fibers and cotton fibers without downtime that must be incurred between batches.
[0017] Suitably, in a continuous process, the aqueous flocculant solution is formed by drip feeding flocculant to the fabric suspension. This maintains the required concentration of flocculant in such a continuous process to successfully achieve separation. Advantageously the amount of flocculant could be varied on-the-fly during a continuous process to achieve consistent fiber separation and maintain quality (such as to minimize residual polyester fibers in the cotton fiber fraction).
[0018] Preferably the fabric suspension comprises shredded fabric in the range 0.01% and 0.5% w/w relative to the fluid, still more preferably the fabric suspension comprises shredded fabric in the range 0.0162% and 0.1% w/w relative to the fluid. This allows the fibers enough space in solution for the physics of density to dominate over tangling and allows the separation of the fibers to occur. A sufficiently low concentration of fibers in solution is required to minimize aggregation and tangling of cotton and polyester threads which would hinder separation.
[0019] Preferably the gas is air. Other gases may be used, such as nitrogen or carbon dioxide, however air is readily available and inexpensive. The purpose of the gas is to form a foam in the solution allowing easy separation of the polyester and cotton fibers.
[0020] Suitably, removing the foam comprises use of any of the following: a weir, suction, and/or a skimmer in order to effectively separate the foam layer from the aqueous solution.
[0021] Optionally, the shredded fabric may be provided time to soak in the aqueous flocculant solution prior to mechanically working the fabric in order to ensure the flocculant has permeated throughout the fabric and adhered or associated with the polyester fibers therein. Alternatively, a minimum time may be used to soak the fabric in the solution in order to minimize fiber swelling. Such swelling can hinder subsequent processing of the fabric suspension, making mechanical working of the fabric more difficult for example as the weight of each cotton fiber increases as it swells with water.
[0022] Preferably the polyester/cotton blended fiber fabric comprises bed linen, tableware, and/or clothing.
[0023] Suitably the cotton fibers remaining in the suspension in a paper product manufacturing process. The aqueous fraction comprising the cotton fibers may be fed straight into a paper manufacturing process without further changes or removal of water from the suspension. Paper products may therefore be manufactured directly as part of the disclosed method.
[0024] Advantageously, the method can be conducted at ambient temperature and/or pressure, thereby minimized energy usage. The solutions do not need to be handled under increased pressure or increased temperatures to achieve successful fiber separation.
[0025] Suitably, an output of the disclosed method is bulk Cotton fibers extracted from polyester/cotton blended fiber fabric. Such bulk cotton fibers may comprise residual polyester fibers by up to 2% mass.
BRIEF INTRODUCTION OF THE DRAWINGS
[0026] An embodiment of the invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure 1 is process overview of a method of separating polyester and cotton fibers; Figure 2 is a process overview of shredding bulk product into a shredded fabric; Figure 3 shows an example separation apparatus; and Figure 4 shows cotton and polyester fibers.
DETAILED DESCRIPTION OF AN EXAMPLE
[0027] In Figure 1, there is shown a process 100 for separating polyester fibers from cotton fibers. Often different materials are combined to produce a single product. This is normally done to take advantage of the unique properties of each material, with the end product exhibiting elements of both materials. Polyesters are known for their durability and resistance to creasing.
Cotton is known to be absorbent and breathable. Combining these two materials yield products which are comfortable to touch or wear, absorbent (properties provided by cotton fibers), durable, and resistance to creasing (properties provided by polyester fibers). Where the products are, by way of non-limitative example, clothing, table linen, or bed linen, the creasing resistance is advantageous in that no or minimal ironing or pressing of the product is required due to the presence of polyester fibers. Such materials are therefore favored by manufactures, particularly, but not exclusively, in the clothing, table linen, bed linen, home or hospitality furnishings, curtain, carpet and rug industries.
[0028] Such hybrid products normally take the form a woven fabric 101 comprising weft and warp threads which are combined in a controlled way to produce a dense and tough fabric. The weft and warp comprise individual threads which are formed from fibers which are twisted into roving, and then spun together forming the complete thread.
[0029] Such threads may be wholly formed from a single material such that the fibers forming a given thread are of only polyester or only of cotton. Alternatively, the threads may be formed of a mixture of cotton fibers or polyester fibers. As threads are formed of multiple roving it will be apparent that each roving used to form a composite thread may be of a single material (i.e. just cotton or just polyester), or of the fibers used to form the roving may be a mixture of cotton and polyester. As such a given thread may be homogenous in composition (an equal dispersion of cotton and polyester fibers throughout a cross section of the thread) or heterogeneous in composition (an unequal dispersion of cotton and polyester fibers throughout a cross section with areas of the thread that are only cotton and other areas that are only polyester).
[0030] It will be apparent that when forming a composite thread the ratio of polyester and cotton fibers may be varied. Typical ratios of cotton:polyester fibers used are 50:50, 70:30, and 80:20 respectively, but it will be apparent that any ratio may be suitable depending on the desired properties and intended function of the end product, as such any ratio in the range 1:99 to 99:1 may be used.
[0031] Non-woven fabrics may be equally processed according to the present disclosure such as, but not limited to, felts, duvet fillers, mattress fillers, air filters, particulate filters, liquid filters (such as coffee), other filters, thermal insulation, sound and/or vibrational insulation, wadding, and upholstery. Non-woven fabrics comprise threads or strands of materials that are combined and tangled together in a non-uniform manner. Other than the bulk morphology of the material (i.e. physical dimensions and bulk properties of the final product), the individual location of a given fiber within the bulk is not. Non-woven fabrics may comprise homogenous or heterogeneous polyester cotton threads in the same way as woven fabrics. It will also be apparent that non-woven fabrics may, in of themselves, be homogenous or heterogenous in composition. What is meant by this is that a given non-woven fabric 101 may comprise a consistent ratio of polyester and cotton fibers throughout (i.e. it is homogenous) or the non-woven fabric 101 may comprise regions of changing polyester and cotton fiber density with some regions consisting of only polyester or only cotton fibers (i.e. it is heterogeneous).
[0032] It will be apparent that all products have a finite lifespan with fabrics in particular becoming worn, frayed, stained, soiled, or otherwise no longer fit for their intended purpose. In the case of non-woven fabrics, such as but not limited to upholstery, for example, the fabric 101 may have lost its required density or resilience (i.e. whether it springs back into its original shape when deformed in used) and can no longer fulfil its intended purpose.
[0033] In the process, such fabrics 101 (woven or non-woven) are collected. These fabrics 101 may be "raw" in that the fabrics 101 are not treated and have arrived directly in their last used state. Alternatively, the fabrics 101 may arrive in a treated form having undergone a treatment such as, but not limited to, partial mechanical break-down (cut into suitable size to allow easy transportation), washing, sterilizing, bleaching, and steaming.
[0034] The collected fabrics 101 may be from a single collection stream (e.g. the fabric 101 is only bed linen, by way of non-limitafive example) or the fabrics 101 may be from multiple collection streams (e.g. woven and/or non-woven fabrics 101 from any of the aforementioned product manufacturers and/or any other suitable source).
[0035] The fabric 101 is then shredded into a shredded fabric 102 (see figure 2). Any suitable means may be used to produce the shredded fabric 102 such as, but not limited to, mechanical cutters, shredders, laser cutting, chipping, and grinding. The purpose of shredding is to yield shredded fabric 102 in segments having dimensions of the order to 1cm2 or other suitable dimension to render fibers in the shredded fabric 102 to be not more than 3mm in length, and preferably not more than 1 mm in length, and more preferably in the range 0.6mm to 0.8mm. Any shredding method that can accomplish this outcome may be used.
[0036] The shredded fabric 102 may then be mixed with a fluid 103, such as an aqueous liquid, although any suitable carrier medium may be used provided it allows for dispersion of the fibers and possesses the required solubility compatibility with the flocculant solution (discussed later). The mixture comprises shredded fabric 102 in the range 0.01% and 0.5% w/w relative to the fluid 103. The purpose of using this weight range is to ensure a sufficiently low concentration of fibers in solution to allow density effects to dominate and reduce the changes of polyester and cotton fiber entanglement which would hamper subsequent fiber separation.
Therefore, it is apparent that other concentrations may be used depending upon the circumstances provided that the concentration achieved the desired purpose of allowing separated polyester fibers to rise in the solution, cotton fibers to sink in the solution, and minimize entanglement of the separated polyester fibers with the cotton fibers.
[0037] The fluid 103 and the shredded fabric 102 are then mechanically worked or otherwise bulk agitated 0.e. mechanically manipulated on a scale larger than the wavelength of ultrasonic sound waves which is 1.9cm or less). Suitable methods to mechanically work the fabric therefore include mechanical motorized beater 104, paddles, rolls, discs, knives or the like. The purpose of mechanically working the shredded fabric 102 with the fluid 103 is to break down the individual shredded fabric segments into threads, and then further break those threads down to their constituent fibers. This mechanical working of the material mechanically breaks down composite fabrics 101 into component cotton fibers and polyester fibers. Therefore, any suitable mechanical means that achieves the required mechanical breakdown to release the fibers from the fabric threads may be used. When the fluid is included at this stage a fabric suspension 105 is formed. It is also possible to mechanically breakdown the fabric in a dry-state (i.e. without the prior addition of fluid). Dry mechanical breakdown may be advantageous in minimizing the weight of the fabric which may hinder effective mechanical breakdown. Mechanical breakdown, whether with fluid or dry, is considered successful once the individual cotton and/or polyester fibers have a length in the range 0.5mm to 1 mm, preferably 0.6mm to 0.8mm. Such a range yields fibers which are particularly suitable for paper making.
[0038] In order to reduce the absorption of water by threads comprising cotton fibers it is preferably to commence mechanical breakdown promptly after forming the fabric suspension 105. Absorption of water increases the weight of the fabric segments requiring more energy to mechanically breakdown the fibers from the threads. This issue may be avoided by dry mechanical breakdown as described above, and then adding the fluid and forming the fabric suspension afterwards.
[0039] Sufficient time must be afforded to successfully separate the fibers from the threads. Typically, the fabric suspension 105 may be mechanically worked for around 1 or more hours. Around 50 minutes is the minimum required mechanical working time to achieve a high degree of fiber breakdown sufficient to progress the disclosed method.
[0040] Once a fabric suspension 105 comprising separated polyester fibers and cotton fibers is formed, a flocculant 106 is added to the suspension. A carrier medium such as water may be used to introduce the flocculant 106 to the suspension. A carrier medium is beneficial to pre-dilute the flocculant 106 to allow for easy and quick dissolution of the flocculant 106 into the fabric suspension 105. The viscosity of the neat flocculant 106 may be too high for the flocculant 106 to be introduced directly into the fabric suspension 105 and prevent complete dissolution in a suitable fimeframe, if at all. It is worth nothing that mechanical manipulation must cease in order to allow density effects to dominate and for the cotton fibers to sink (forming a cotton fraction 110 in solution), and the polyester fibers to rise in the solution (forming a polyester fraction 111 in solution). Mechanical mixing of the flocculant 106 solution is therefore undesirable as this may result in premature foam formation and the contamination of either the cotton or the polyester fractions.
[0041] Suitable flocculants 106 are a non-ionic surfactants. The weight ratio of flocculant 106 to dry fiber mass used in the method to achieve successful separation should be maintained in the range 1:99 to 10:90, and preferably 5:95 respectively. Where the method is implemented as a continuous process (as opposed to a batch process) the concentration of the aqueous flocculant solution 106 may be maintained within the required range by drip feeding the aqueous flocculant solution 106 into the mechanically worked fabric suspension 105.
[0042] Following addition of the flocculant 106 to the fabric suspension 105 a gas 107 is then bubbled through the fabric suspension 105 in order to allow the flocculant to generate a foam 108. The gas bubbles 109 further exaggerate the density difference between the cotton fibers and the polyester fibers. The polyester fibers are caught and encapsulated in the foam 108 ensuring a successful separation of the polyester fibers from the cotton fibers.
[0043] It will be apparent that any suitable gas 107 may be used provided that gas 107 allows the production of a stable foam 108 from the fabric solution 105 and flocculant 106. Here a stable foam 108 means one of sufficient durability to allow the foam 108 to be collected or otherwise separated from the fabric solution. Accordingly, the foam 108 should not immediately disintegrate. Suitable gases 107 include air and/or nitrogen.
[0044] The amount of gas 107 bubbled through the solution should be sufficient to produce sufficient foam 108 for a successful fiber separation. It will be apparent that too vigorous or too little gas 107 should be avoided to prevent excess production of foam 108 (risking overflow) or insufficient gas 107 such that too little foam 108 is formed.
[0045] The gas 107 may be introduced using any suitable means such as a perforated plate or other aerator (not shown).
[0046] The gas 107 may be introduced at any suitable location in the vessel containing the fabric suspension 105, however it is advantageous to introduce the gas 107 above the cotton fraction 110 in order to minimize the risk of cotton fibers being caught in the foam 108 production and carried to the surface foam 108 thereby contaminating the polyester fraction 111 [0047] With reference to figures 1 and 3, once a foam 108 is formed on the solution the foam 108 may then be removed. This may be achieved through the use of a weir 112 where the foam 108 may be permitted to overflow to a suitable collection vessel 113. Alternative methods may be used such as a skimmer or suction to mechanically remove the foam 108 to the collection vessel 113.
[0048] Following separation of the foam 108 from the fabric suspension 105 the polyester fibers are predominantly located in the foam 108 and the cotton fibers remain in the mother liquor as a cotton fraction 110.
[0049] The relevant fiber can then be reclaimed from each fraction by removing the fluid 103 (by filtration and drying) and flocculent 106 (such as by washing) from the fractions to yield bulk fibers which may then be repurposed or reused in for example, fabric 101 (woven or nonwoven) manufacture and/or paper manufacture.
[0050] Figure 4 shows a microscope image of an example cotton fraction 110 achieved via the method of this disclosure. The cotton fibers 401 are visible as curvilinear structures some comprising forked sections. The polyester fibers 402 are much reduced in number compared to the cotton fibers and are visible as relatively thinner, straight fibers without forked sections. The cotton fibers are particularly suitable for use in a paper product manufacturing process which includes, but is not limited to paper sheets, cartons, containers, casings, and carboard. The cotton fibers may also be re-used in other industries including those from which the fibers were originally sourced, including but not limited to textiles, clothing, felts, duvet fillers, mattress fillers, air filters, particulate filters, liquid filters (such as coffee), other filters, thermal insulation, sound and/or vibrational insulation, wadding, and upholstery. The polyester fibers are suitable for recycling and reuse in other cotton polyester fabric or other uses. The polyester fibers may be re-used in industries including those from which the fibers were originally sourced.
[0051] It is inevitable that a residual or trace amount of polyester fiber will remain in the cotton fraction, and vice versa. Such trace amounts may be acceptable, up to 2% by weight, or the relevant fiber fraction may be further processed using the method of this disclosure to achieve greater separation of the polyester and cotton fibers. Preferably the trace amounts would not be more than 1% by weight.
[0052] The above disclosed process may be performed as a batch process or a continuous process depending on the volume of fabric 101 available for fiber separation.
[0053] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
[0054] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
[0055] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.
Claims (25)
- CLAIMS1. A method of separating polyester and cotton from a polyester/cotton blended fiber fabric, the method comprising: shredding the blended fiber fabric into a shredded fabric; mechanically working the fabric; adding a fluid to the fabric to form a fabric suspension; adding an aqueous flocculant solution to the fabric suspension; bubbling a gas through the fabric suspension thereby generating a foam; removing the foam from the fabric suspension; wherein polyester fibers of the polyester/cotton blended fiber fabric are suspended in the foam and cotton fibers of the polyester/cotton blended fiber fabric remain in the suspension.
- 2. The method of claim 1, wherein the fiber fabric is a woven fiber fabric.
- 3. The method of claim 1 or 2, wherein the fiber fabric comprises a plurality of polyester fibers and plurality of cotton fibers.
- 4. The method of claim 3, wherein the fiber fabric comprises any of: threads formed of only cotton fibers; threads formed of only polyester fibers; threads formed of cotton fibers and polyester fibers.
- 5. The method of any preceding claim, wherein the mass ratio of polyester fibers to cotton fibers is in the range 1:99 to 99:1 cotton:polyester, and optionally 50:50, 70:30, or 80:20 cotton: polyester.
- 6. The method of any preceding claim wherein shredding the blended fiber fabric comprises shredding until the fibers not greater than 1mm in length, and optionally in the range 0.6mm to 0.8mm.
- 7. The method of any preceding claim, wherein the weight ratio of flocculant to dry fiber mass is in the range 1:99 to 10:90, and preferably 5:95.
- 8. The method of any preceding claim, wherein the fabric is mechanically worked for a period of time, optionally around 50 minutes.
- 9. The method of any preceding claim further comprising removing liquid from the suspension to produce separated cotton fibers.
- 10. The method of any preceding claim wherein the method further comprises washing the polyester/cotton blended fiber fabric.
- 11. The method of any preceding claim wherein the method is a batch process.
- 12. The method of any of claims 1 to 10 wherein the method is a continuous process.
- 13. The method of claim 12, wherein the aqueous flocculant solution is formed by drip feeding flocculant to the fabric suspension.
- 14. The method of any preceding claim, wherein the fabric suspension comprises shredded fabric in the range 0.01% and 0.5% w/w relative to the fluid.
- 15. The method of any preceding claim, wherein the flocculant is a flocculant.
- 16. The method of any preceding claim, wherein the flocculant is a non-ionic surfactant.
- 17. The method of any preceding claim, wherein the gas is air.
- 18. The method of any preceding claim, wherein removing the foam comprises use of any of the following: a weir, suction, and/or a skimmer.
- 19. The method of any preceding claim, further comprising allowing the fabric suspension time to soak prior to addition of the aqueous flocculant solution.
- 20. The method of any preceding claim wherein the polyester/cotton blended fiber fabric comprises bed linen, tableware, and/or clothing.
- 21. The method of any preceding claim, further comprising using the cotton fibers remaining in the suspension in a paper product manufacturing process.
- 22. The method of any preceding claim, wherein the method is conducted at ambient temperature.
- 23. Paper products manufactured using the method of claim 21.
- 24. Cotton fibers extracted from a polyester/cotton blended fiber fabric using a method as claimed in claims 1 to 20, and 22 and optionally wherein the cotton fibers comprise up to 2% polyester fibers.
- 25. Use of a polyester/cotton blended fiber fabric for the method as claimed in any of claims 1 to 22.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2215744.0A GB2623761A (en) | 2022-10-24 | 2022-10-24 | Method of separating polyester and cotton |
PCT/GB2023/052636 WO2024089387A1 (en) | 2022-10-24 | 2023-10-11 | Method of separating polyester and cotton |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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GB2215744.0A GB2623761A (en) | 2022-10-24 | 2022-10-24 | Method of separating polyester and cotton |
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GB202215744D0 GB202215744D0 (en) | 2022-12-07 |
GB2623761A true GB2623761A (en) | 2024-05-01 |
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GB2215744.0A Pending GB2623761A (en) | 2022-10-24 | 2022-10-24 | Method of separating polyester and cotton |
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GB (1) | GB2623761A (en) |
WO (1) | WO2024089387A1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3511140A1 (en) * | 2018-01-15 | 2019-07-17 | Lenzing Aktiengesellschaft | A process for separating a fibrous target component from textile waste |
WO2022136724A1 (en) * | 2020-12-23 | 2022-06-30 | Valmet Technologies Oy | Method of processing recycled textile fibers and a process system of processing recycled textile fibers |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2011077446A1 (en) * | 2009-12-23 | 2011-06-30 | Varun Gambhir | Process for recycling cotton fabrics |
FR2991600B1 (en) * | 2012-06-06 | 2014-07-18 | Fibers | PROCESS FOR SEPARATING POLYESTER AND COTTON FOR RECYCLING TEXTILE WASTE |
JP7212603B2 (en) * | 2019-10-28 | 2023-01-25 | 倉敷紡績株式会社 | Cellulose separation method |
CA3200047A1 (en) * | 2020-11-25 | 2022-06-02 | Zahlen TITCOMB | Modular textile recycling system and processes |
-
2022
- 2022-10-24 GB GB2215744.0A patent/GB2623761A/en active Pending
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2023
- 2023-10-11 WO PCT/GB2023/052636 patent/WO2024089387A1/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3511140A1 (en) * | 2018-01-15 | 2019-07-17 | Lenzing Aktiengesellschaft | A process for separating a fibrous target component from textile waste |
WO2022136724A1 (en) * | 2020-12-23 | 2022-06-30 | Valmet Technologies Oy | Method of processing recycled textile fibers and a process system of processing recycled textile fibers |
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WO2024089387A1 (en) | 2024-05-02 |
GB202215744D0 (en) | 2022-12-07 |
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