One-Step Recycling And Inline Spinning Of PET Waste Into High-End Fibers

REMSCHEID, Germany — February 18, 2021 — German company BB Engineering combines its VacuFil process with the directly-connected VarioFil spinning system, hence creating a one-step process for recycling and inline spinning of post-consumer and post-production polyester (PET) waste into partially oriented yarn (POY) or fully drawn yarn (FDY).

Manufacturing polyester fibers for demanding textile applications from recycled PET (rPET) granulate — particularly using the inline spinning process — is an extremely challenging task. It requires recycling know-how and spinning plant expertise. The starting material has to be continually processed into an homogeneous, spinnable melt.

All processing steps must ensure the required melt properties and keep these stable throughout the entire process runtime. For numerous textile applications, parameters such as viscosity and homogeneity are decisive and must be subject to the only the minutest fluctuations. In other words: using recycled polyester within the textile segment requires suitable pretreatment processes in conjunction with precise process management.

BB Engineering, a subsidiary of Oerlikon Textile, has decades of experience and know-how in the development of spinning plant components and systems. And it was this spinning plant expertise that was decisive for the successful development of the VacuFil PET recycling system. On this basis, the company developed a Liquid-State Polycondensation recycling system for further processing post-production spinning waste and post-consumer bottle flakes, optimally aligned to the textile further processing of the recycled materials in the spinning plant (patent currently pending).

The core component of this process is the vacuum filter, with which the viscosity can be separately controlled and monitored. To this end, the required melt properties can be achieved inline in a reliable and reproducible manner and controlled during operation. In various spinning trials, the rPET granulates manufactured at the Oerlikon Textile R&D Center using the VacuFil produced convincing results.

Virgin PET reference Bottle flakes
Indian customer
Bottle flakes
European origin
Fiber waste POY
Input IV 0.66 dl/g 0.81 dl/g 0.80 dl/g 0.624 dl/g
Output IV VacuFil 0.646 dl/g 0.66 dl/g (±0.06) 0.643 dl/g (±0.05)
Quality No. 22.1 22.8 21.8 20.9
Frays / 10,000m 0.65 0 0.75 0.41
Yarn breaks / 1t 0 0 0 0
Dyeing uniformity

(1: best – 6: worst)

1-2 1-2

>4.5 (gray scale) AA



The results of the various spinning trials demonstrate that the new VacuFil technology is so effective that the rPET produced is of outstanding quality and comparable to that of virgin material.

The granulation step can be dispensed with if you combine the VacuFil with BB Engineering’s rPET-compatible VarioFil* R+ compact spinning system (or other direct spinning systems capable of processing rPET). The waste material is recycled and directly spun in a single seamless process – in superlative quality thanks to optimum melt treatment. [Anm.: Den folgenden, englischen Part hat der Kunde so abgesegnet. Bitte nicht verändern.] Eco Spindles – a Sri Lanka-based customer of BB Engineering – has been so convinced by the VarioFil R+ spinning system with VacuFil extrusion that it is investing in a further rPET VarioFil system. Dr. Anush Amarasinghe, managing director of Eco Spindles, produces POY from bottle flake material and explains: “Our clients are increasingly asking for recycled fibers and we of course wish to fulfill their requirements and demands. For this reason, expanding our portfolio to cater to this has been an important step for us. Bottle recycling is still a niche market in Sri Lanka and we have been determined to maintain our high quality standards. We have special requirements and needed a cutting-edge partner for this project. A few years ago, we opted to purchase a BBE VarioFil R+ compact spinning system to allow us to manufacture POY from bottle flakes. We wanted to first test the set-up – also due to the fact that the bottles collected from beaches are in part problematic starting materials. However, the extremely good customer feedback and the fact that our product is profitable have prompted us to invest further. We have decided to acquire a further VarioFil R+ line with VacuFil recycling system. What is particularly great is the fact that the entire process is completely coherent. We are able to produce extremely homogeneous, viscosity-stable rPET melt and spin it directly into high-end fibers.”

In the case of Eco Spindles, this is a flexible VarioFil R+ compact spinning system with upstream VacuFil inline recycling unit with a direct feed. It has been designed to manufacture using recycled bottle flakes, recycled chips and virgin chips. On the one hand, this is possible as a result of the drying system that is suitable for both flakes and chips. On the other hand, the vacuum extruder can be operated without or without vacuum and is therefore able to melt recycled and virgin starting materials. The experience acquired from >20,000 sold units has influenced the extruder design. As a result of the gentle melting, BBE extruders form the basis for absolutely-homogeneous melt, as required by the spinning plant. The single-screw technology ensures the robustness necessary in recycling. Last but not least, the special metering system for several components also provides producers with flexibility: either two additives can be fed into the melt simultaneously or the metering unit can be used for fast dye switches. With 6 positions, this VarioFil configuration achieves product throughputs of up to 150kg/h and offers a broad end product range with final titers of between 50 and 150 den (DTY) with a DPF range of between 0.7 and 4.0 dpf. In other set-ups, the VarioFil R+ covers a range of 20-600 den POY or 30-500 den FDY with recycled PET.*

With this, the VarioFil is not only a versatile spinning machine for the most diverse applications, it also caters to the constantly-rising demand for rPET fibers. Leading textile-processing businesses and corporations — be these fashion brands, sports apparel and furniture manufacturers or those operating within the automobile industry — are increasingly focusing on sustainable products and products made from recycled materials. Today, they are already telling suppliers of filaments, fibers and nonwovens that they will be switching from exclusively virgin polyester to recycled polyester — in some cases up to 100 percent — for the manufacture of their textile products in the near future.

*VarioFil is the name given to BB Engineering’s compact spinning systems product family. In general, VarioFil systems are able to process PET, PA6, PA6.6, PP, PLA, PBT, PTT and bi-components into POY, FDY or IDY. The VarioFil R+ system has been designed especially for rPET and bottle flakes.

Posted February 18, 2021

Source: BB Engineering GmbH