P-22

Cotton is the most abundant natural fiber in the textiles industry and has been used since the beginning of the industrialization as major raw material for garment production. Despite our high industrial standards, cotton recycling was restricted to the mechanical down-cycling of the fibers to products of lower value for a long time. Considering the enormous burden cotton cultivation has on the environment, the creation of a closed material cycle is expected to decrease this impact significantly. In fact, cotton waste can also be seen as valuable source of cellulose. With a typical α-cellulose content of >94% and an average DP >1500, cotton waste is well suited to replace common dissolving pulp in the production of regenerated cellulose fibers. The workwear industry is a highly demanding industry for fiber and product quality. Workwear is often industrially washed and collected, which gives rise to a stock of discarded workwear that knows no valuable recycling process.

In this contribution, the project “From Workwear to Workwear” will be presented. In this case study, the SaXcell chemical recycling technology invented at Saxion is used to recycle worn-out cotton workwear into a virgin fiber that can be used to construct a new piece of workwear with very high quality.

The project started with an overall look at the collected workwear cloth. It was found that the workwear contains – next to the cotton fabric that will be recycled - three types of materials. Materials that will be sorted out during the mechanical unraveling of the workwear, i.e. buttons and other heavy parts (accessories), materials that cannot be sorted out mechanically, but can be separated from the cotton fabric during the chemical recycling process, i.e. sewing threads and parts that cannot be sorted out mechanically or chemically, i.e. elastomeric material. These non removeable parts need to be cut out by hand. To avoid this in an industrial process, design rules will be developed to assist designers of workwear cloth by the choice of their materials.

First laboratory experiments showed that it is possible to use the cotton fabric of workwear cloth to produce virgin blue fibers of unique quality. However, the polyester sewing threads in the overalls are disturbing the recycling process and a treatment needs to be developed to remove the sewing threads from the cotton fabric.

When the laboratory investigations are finalized the process will be scaled-up to produce several kg of the blue SaXcell fibers. With these fibers a new piece of workwear will be constructed that should fulfil the high quality standards of the workwear industry. By this, the material cycle for cotton workwear would be closed and real up-cycling of worn-out workwear would be reality.