Applications Sustainable
Applications Sustainable adhesive tapes A contribution to the reduction of the carbon footprint By: Ingo Neubert R&D, Backings and Film Development tesa SE Norderstedt, Germany Adhesive tape applications are all around us. Tape applications well known to the public include packaging tapes, office tapes as well as DIY tapes. However, approximately 75 % of the most important applications are specialized industrial applications. Today, such industrial adhesive tapes are widely used in consumer electronics, automotive, aeroplanes, trains, medical and hygiene sectors. Industries like wind and solar, constructions, white goods as well as paper and print use adhesive tapes in manufacturing and mounting processes. The adhesive tape market has a total volume of 7 billion m² (67 % packaging tapes, 10 % consumer and office tapes, 8 % masking tapes, 15 % specialty tapes) [1]. The current trend towards more sustainability also has a big impact on the adhesive tape market. Adhesive tapes can improve sustainability as enabler aids for production processes or product designs. An additional contribution to sustainability comes from the design of the adhesive tape itself, thanks to measures like downgauging, reusability, and incorporation of recycled or biobased raw materials. tesa (Norderstedt, Germany), one of the leading tape manufacturers worldwide, strives to reduce the carbon footprint of its products and its manufacturing processes for many years. For example, new technologies were developed for solvent-free processing with natural rubber and acrylic adhesive. In total, solvent consumption was reduced by 40 % between 2001 and 2019. Furthermore, more than 10 years ago tesa launched the sustainable ecoLogo ® product assortment for consumer applications: It includes, for example, the first office and packaging tape based on a 100 % post-industrial recycling backing film. For the redesign of existing products and the development of new products, new sustainable raw materials will be necessary for the adhesive tape product designs. However, currently, only a limited choice of sustainable raw materials and plastics are commercially available (see bioplastics MAGAZINE 03/2021) [2]. Most of them have only low relevance for adhesive tape applications because the properties are not matching the requirements. Therefore, intensified R&D efforts will be necessary to make do with the available raw materials and to meet the requirements of the many different applications. One big focus of the current development at tesa is on the largest part for adhesive tape applications – the packaging tape market. In April 2021, tesa launched a new sustainable packaging tape – tesapack ® Bio & Strong. The product is certified by DIN Certco and TÜV Austria with a biobased content of 98 % (as measured according to ASTM D6866 and EN 11640). This packaging tape is based on a special biaxially-oriented PLA film coated with solvent-free natural rubber adhesive. The special biaxially-oriented PLA film consists of PLLA resin that guarantees better heat stability in the production process. The replacement of the conventional fossil-based OPP or PVC backing by a BO-PLA film from renewable resources in tesapack Bio & Strong results in a reduction of CO 2 . emission of 15–20 % CO 2 eq. (compared to OPP) and 30–35 % CO 2 eq. (compared to PVC). This reduction is related to the backing material only. The carbon footprint calculation is based on a cradle-to-grave approach regarding IPCC AR5 GWP100 (incl. land-use change) and with respect of generic information of the film manufacturing process. 30 bioplastics MAGAZINE [04/21] Vol. 16
Other interesting developments for sustainable adhesive tapes at tesa are taking place with a focus on tape backings and release liners – both may make a significant contribution to the reduction of carbon emission. Besides the mentioned biobased plastics, recycled plastics could be an interesting option too. The plastics get a second life instead of being incinerated and replace the use of virgin material, thus saving resources and CO 2 emissions. PP and PET are very common materials used in tape design, in form of films, cloth, or nonwoven. For both materials, circular recycling processes for post-consumer waste are established. PP on the one hand is currently available as PCR PP material mainly for moulding applications but unfortunately not in grades suitable for film applications. Therefore, it is currently only possible to produce an adhesive tape based on e.g., PIR* but not PCR* OPP film (* see separate box). Due to the worldwide established recycling of PET bottles a mature circular economy around PET waste is being created. Mechanical as well as chemical PCR PET grades based on waste streams are available in reliable quantities to produce biaxially-oriented PET films. PET films with up to 100 % chemical PCR content are commercially available from some PET film manufacturers. With cross-functional development efforts, such films with 70 % up to 100 % PCR content could be successfully incorporated into new sustainable adhesive tapes, performing equivalently to analogue fossil-based products in terms of processability, adhesive anchorage, tensile strengths, elongation, resistance, and targeted applications. The PCR PET can be widely used as backing and liner for different kinds of adhesive tapes e.g.: • (a) double-sided mounting tapes based on 10–40 µm PCR PET film • (b) single-side carton sealing tapes with 20–50 µm PCR PET film • (c) single-side strapping tapes with e.g., 36 µm PCR PET backing (the use of PCR films is highly significant for such single-use products) • (d) thick PCR PET films (70–200 µm) for hole covering in automobile applications (in this case, the sustainability factor is high due to the high thickness of the PET film) • (e) paint or pre-bond masking tapes based on 25–80 µm PCR PET films • (f) release liners with a release coating to protect the adhesive before final usage (normally, the customer throws the release liner away when using the adhesive tape, such processing aids could be ideally made from recycled plastic) • (g) PCR PET woven and non-woven adhesive tape backings for repairing or wire harnessing applications Currently, there are many developments for sustainable raw materials with potential relevance for adhesive tape applications. One central topic is the mass-balance approach for drop-in standard polymers like polyethylene and polypropylene based on bio-naphtha. Bio-naphtha is produced from organic waste like tall oil or vegetable oil. The newest development uses this concept in combination with chemical recycling of mixed plastic waste via a pyrolysis process. The mass-balance approach offers the opportunity to produce polymeric films like OPP films e.g., as adhesive tape backing with reduced carbon footprint. Furthermore, some new sustainable materials are in the scaling-up pipeline. Prime candidates to produce polymeric films and probably tape backings could be biobased polyhydroxyalkanoate (PHA) polymers and polyethylene 2,5-furandicarboxylate (PEF) polymers. PEF is a new polyester based on biobased ethylene glycol and biobased 2,5-furandicarboxylic acid (FDCA) as a sustainable replacement to PET. There are many interesting developments happening in the plastic market that strive to increase the sustainability factor and reduce the carbon footprint. That will have an impact on industries like the adhesive tape industry. In the next couple of years, there will be many new adhesive tapes based on biobased, recycled, or biodegradable materials with a lower carbon footprint on the market. The transition processes have started already. www.tesa.com [1] AWA Alexander Watson Associates, Global Pressure-Sensitive Adhesive Study 2021 Recycled plastics are differentiated between post-industrial (PIR) and post-consumer (PCR) recycled material. PIR plastics are much cleaner and better usable because of their single source. However, the availability of PIR plastics is limited. On the other hand, it is an abundant source of post-consumer plastic waste(PCR). Unfortunately, the post-consumer plastic waste is a wild and contaminated mix, exudes a strong smell, consist in multiple plastic grades and is often laminated with materials like cardboard or aluminium foil that disturb the recycling process. Recycling this type of multi-component post-consumer plastic waste is quite difficult. The most common use for post-consumer plastic waste is incineration, downcycling to low-quality products, and landfill. But many technological developments took place to increase the recycling process to obtain qualitative high-value PCR plastics with the opportunity to use them in high-quality products. Some PCR plastic fractions like LDPE, HDPE, PP and PET are available in good quality today. But all those mechanical recycled plastics have lower performance compared to virgin plastics due to their multiple processing and lifetime. As an alternative to the mechanical recycling processes, there are established chemical recycling processes for some polymers like PET. The chemical recycling process splits the polymer into monomers and builds up new polymers. Cleaning processes of the monomers are possible. The big advantage of the chemical recycling process is that the new polymer is indistinctive from the original virgin polymer except for a much lower carbon footprint. Applications bioplastics MAGAZINE [04/21] Vol. 16 31
