Truetzschler and Erema have collaborated to develop a one-step system to pre-process and spin polyester flakes into bulked continuous filament (BCF) yarn for carpet applications, it has been announced.
The new system directly links Erema’s Vacurema® technology with Truetzschler Switzerland’s symTTex BCF machinery. Erema’s contribution consists of a vacuum reactor, a directly linked single-screw extruder and a high-performance filter.
As per the process, washed R-PET flakes are dried and decontaminated in the Erema reactor, melted in the extruder and then forced through a large area filter of variable fineness. After that, the high-quality melt is transferred to Truetzschler’s spinning system.
The established high quality spin packs, dual shell draw rolls, the HPc texturising system and fully driven winders form filaments which are wound onto bobbins. An industrial line based on this new concept is already running in Poland successfully.
A one-step process for high-quality yarns
Erema’s patented system enables the feeding of clean flakes directly into the reactor without using a crystalliser and dryer. A major advantage is the energy saving achieved because energy-intensive drying and crystallising steps are omitted.
The yarn Intrinsic Viscosity (IV) value virtually reaches the IV value of the flakes. This proves that the drying process is extremely efficient since the vacuum before the extrusion process removes moisture and volatile material very effectively.
The combination of Erema’s and Truetzschler systems allows for producing distinct bulked continuous filament (BCF) yarns with high efficiency, excellent process stability and with low transformation costs. Market requirements and expectations when using 100% recycled PET flakes or flakes with virgin material are thus fulfilled.
The co-operation of Truetzschler with Erema for recycled polyester constitutes a major pillar in Truetzschler’s product portfolio of solutions. It perfectly adds to the already established systems for the production of PA6, PA6-6, virgin PET and PP BCF yarns. It is a step ahead toward market demand for more sustainable end products.
As compared to glass, the material most used for bottle-making in years past, plastic bottles have the distinct advantage of being light weight and almost unbreakable. Now-a-days, most producers and consumers favour PET – polyethylene terephthalate – bottles. Thus plastic bottles are really most of the time actually “polyester” bottles.
In many regions of the world recycling is an option. In Asia, the probability that an empty bottle will be recycled is more than 75%.
Recycling of plastic bottles in Asia is widespread especially because entrepreneurs in China and India recognised quite early on that PET bottles are in fact valuable raw material. Using recycled polyester flakes offers advantages both economical (flakes are cheaper than virgin chips) and ecological (due to the sustainability and good image or green label aspect).
Recycling PET bottles
However, a long and complex process chain is needed to turn used bottles into usable raw material. It all starts with the collection of the bottles and pressing them into bales. Afterwards, the bales are opened, and the contents sorted out and ground. The flakes obtained are washed (cold and hot) and separated from the polyolefin, which comes from caps and gaskets. After drying and metal separation, the flakes are filled into silos or big bags.
One of the main uses for recycled polyester is the spinning of staple fibres, which can be used for instance as spun yarns, textile fillings or nonwoven materials. The collection and recycling rate of plastic bottles is growing worldwide and therefore new end uses of the recycled PET like making carpets are being explored.
Spinning BCF yarn from PET and Recycled PET
PET fibres offer numerous advantages in carpet applications. Especially their high stain resistance which is even higher than that of chemically treated polyamide bulk continuous filament or PA BCF. Moreover, PET can be spun in un-dyed form, which is not the case for polypropylene or PP. Un-dyed yarns can be twisted, heat set, dyed and tufted or the finished carpet can be printed.
Using recycled PET for manufacturing continuous filaments is more challenging as compared to staple fibre production. In filament spinning, the quality of the yarn is determined by homogeneity of raw material.
Recycled flakes are often an instability factor and small deviations in quality can lead to an increased number of filament breaks or broken filaments. Further, variance in the quality of flakes could affect the yarn’s colour pick-up in a way that the finished carpet shows streaks.