There are different methods of recycling and regenerating textiles from textile waste. This process is however strongly influenced by factors such as high prices, volumes and availability of virgin raw materials. For this reason, this line of work has not been fully integrated into the overall textile supply chain and it still has challenges for sustainable and economically feasible operations.
Processes such as trimming industrial and post-consumer waste, pulping cotton and linen, and producing non-woven materials have existed for centuries. Recently, there has been great interest in the growth of the reuse and recycling of textile waste, further developing the recycling processes, due to a greater awareness of the impacts of the current supply chain of fashion industry.
There are many research and development projects focusing on chemical recycling methods and machinery. Below are some examples:
The Finnish company Infinited Fiber (a VTT Technical Research Centre of Finland spin-out) has revealed that it is recycling cotton into a novel cellulose carbonate fiber. The cellulose is modified before the dissolution step by the addition of urea. Heat is applied to break the urea down to form isocyanic acid, which the hydroxyl groups on the cellulose react with to form carbamates. This is then dissolved, and the resulting pulp is regenerated into fibers using the viscose production process.
The industrial process developed make possible to use the old viscose production plants, but without the negative aspects for the environment such as the use of carbon disulfide. The consistency and strength of the fibers obtained are comparable with those of virgin cotton. Its fiber has been tested by global brands including H&M and VF Corporation.
Blend Re:wind – Mistra Future Fashion
Blend Re:wind is a new process (developed only at laboratory scale) to recover and recycle cotton and polyester. The technology is the result of a Swedish research program called Mistra Future Fashion supported by The Chalmers University of Technology in Gothenburg.
The technology is based on an innovative chemical recycling process that produces new viscose filaments starting from polyester and cotton fibers. The separation of the fibers takes place by alkaline hydrolysis with the addition of a catalyst which avoids the degradation effect of the polyester. The process generates three circular flows of outgoing products: cotton pulp extracted can be regenerated in high quality viscose, polyester filaments are transformed into two new “pure” monomers that can be rebuilt in new and reinforced fiber. The filaments have the same quality as those obtained in a standard way used in the production of existing viscose.
The new recycling technique was accepted as a circular solution for both materials, as well as a development key for future global textile recovery systems, to allow the circularity of fashion and close the circuit for textile production.
PTF-COLDPLAST – Next Technology Tecnotessile
PTF-COLDPLAST is a technology, developed by Next Technology Tecnotessile, that allows, thanks to a non-invasive process, to separate thermoplastic fibers from other fibers, in other words it is possible to separate polyester, nylon, elastomers from natural or artificial fibers (wool, cottons, viscose, hemp and others). The advantage of this new technology is that thermoplastic materials are recovered and supplied directly in the form of granules that can be easily re-used in industrial molding processes. Natural or artificial fibers, still in the same form of the input waste stream, however must be processed mechanically before obtaining a fiber that can be used in new textile processing cycles.
PTF technology can be defined as a “thermal process in fluid”, which has the purpose of separating synthetic textile materials by type with a high degree of purity (Nylon 6 66 – Polyester PET PBT, acrylics – polyurethane elastomers – Polyolefins in general from fibers artificial (Rayon / viscose) and / or natural (wool, cotton, linen and others). Products obtainable at the end of the process are:
-plastic pellets (granule for molding);
-flakes of artificial and natural fibers for further mechanical recycling process
DEMETO – GR3N
Gr3n is an innovative technological company, which has developed a chemical recycling process for some types of plastics, in particular for PET (mainly used for the production of packaging: beverage bottles and food trays) and for polyester (the most used fiber in the world for the production of fabrics).
The technology developed by Gr3n is called DEMETO (Depolymerization by MicrowavE TechnolOgy) and is based on the application of microwaves to the depolymerization process, functioning as a catalytic agent and improving the efficiency of the reaction. This makes the whole process sustainable not only from an environmental point of view, but also from an economic one. The core of technology is DEMETO (DEpolymerization by MicrowavE TechnolOgy), a patented technology, able to depolymerise, in continuously, a wide range of PET manufactures (e.g. color bottles, food containers, polyester textile). DEMETO technology reduces the reaction time from 180 to 10 minutes, making easier the industrial implementation.
The technology developed by gr3n is self-sufficient from the point of view of the chemical reagents used for the process, which are recycled on site, without any production of hazardous waste. The process requires only electricity and water for its operation, in addition of course to the plastic waste to be treated.
Econyl – AQUAFIL
Nylon is more difficult to recycle, because, it needs a large input of the same kind of nylon for it to be feasible. However, Aquafil, a leading company in the production of Nylon 6, has developed the Econyl Regeneration System, which produces Nylon 6 from nylon waste such as fishing nets and carpet fibres. The ECONYL® yarn can be regenerated infinitely without any loss in quality, using the following process:
-fishing nets and other nylon waste (e.g. carpets) is collected and sorted;
-a cleaning and shredding process creates small pieces of nylon;
-depolymerization occurs through a series of chemical reactions that convert nylon pieces into nylon monomers;
-Econyl® is created by polymerizing the monomers back into nylon.
Founded in 2012, Re:newcell is a Swedish company that recycles garments using a chemical process. The process, initially developed by the Royal Institute of Technology in Stockholm, is developed as follows:
-collection of pre- and post-consumer textiles made out of cotton or cellulosic fibers from textile collecting and sorting companies, retailers and textile manufacturers.
-textile waste chopping to equal size, de-dye and de-finish the textiles
-pre-processed textile dissolution to molecular level and separation of cellulose from other materials such as polyester;
-cellulose drying: the dried cellulose is called dissolving pulp, of which viscose and lyocell products can be made.
Worn Again Technologies
Worn Again Technologies, a London based technology licensing company, is developing unique polymer recycling processes that will be able to recycle used polyester and cotton clothing. To recycle both the polyester and the cotton components of this blend, the recycling process must first separate them. This isn’t easy mechanically but can be achieved chemically by playing on the different physical properties of the two fibers.
The first steps in Worn Again Technologies’ process are similar to those developed for cotton-only chemical recycling: non-woven materials removal and de-dyeing. Polyester fibers and other polymers, such polyurethane and cellulose acetate, are also washed out during this stage.
All that remains after washing is solvent saturated pure polycotton. Subsequently, this is heated at high temperature, the polyester dissolves and goes into solution. Cotton and polyester are then separated by filtration.
Subsequently, they separate the solvent from the polymer, restore the polymer in the correct chemical structure for re-use in the textile market. The process output is exactly the same as a virgin PET pellet that would come out of a polymerization plant.
The solid cotton fibers are then dissolved using an ionic liquid to produce a pulp, equivalent to a wood pulp, which can be used as a raw material for the spinning processes of existing cellulosic fibers.