The central issue in all polyurethane applications is the conversion from the past linear economy into a circular economy, and the use of sustainable raw materials in manufacturing. To do so, manufacturers are taking measures such as using bio-based raw materials, chemical recycling, and CO2 as a synthesis component. Digitalization, electromobility, autonomous driving and the construction industry are also driving PU development.

Polyurethane (PU)

Bauwesen

Bauchemie

Baustoffe

Automotive

Elektronik

Polyurethan-Schaumstoffe (PUR)

Halbzeuge und Zwischenprodukte

Kunststoff-Halbzeuge

Baubetrieb / Bauwirtschaft

Kunststoff Werkstoffe

Polyurethan

Windkraft

Energieerzeugung

Erneuerbare Energie

Kunststoff

Kunststoff-Recycling

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

Sustainable Growth

For a long time, chemical recycling was considered an unfinished addition to established material processes. In the meantime, however, some technologies are making the leap into large-scale industrial use: an overview of the various processes and providers.

Overview of the Various Processes and Suppliers

Recycling

Umweltmanagement

Polypropylen

Thermoplaste

What Is Happening in Chemical Recycling?

That polyurethane can make a valuable contribution to the current trends of resource efficiency, lightweight design, sustainability and recycling that are prevalent in every industrial sector is demonstrated by the PU industry in the form of new solutions for increasingly demanding economical and ecological challenges. In this way, PU as a reactive material is confirming its great potential to be a long-term alternative to existing materials, and this not only because of its versatility. 

Ecological as well as Economical Requirements as Targets 

Faserverarbeitung

Schäumen / Reaktive Verarbeitung

Resin Transfer Molding

PUR-Schäummaschinen

Kunststoff-Rohre

Polyurethane World Becoming  More Sustainable 

In the midterm, a worldwide increase in PU consumption of 4 to 5 % per year is to be expected. Growth drivers are the sound economic performance in the major industrialized nations so far, and in particular the increasing prosperity in China and emerging markets. In future, the PU business will be strongly influenced by digitalization and the development of closed material life cycles.

The Global PU Sales Reached a New Record in 2018 with just over 20 Million Tons

Schaumstoffe und Vorprodukte

Schaumstoffe

Standardkunststoffe

At the first glance, this year’s K was clearly focused on recycling and the circular economy. However, apart from these topics, many novelties were also exhibited in the classical plastics fields such as automotive. And many materials producers showed exciting new developments for electromobility in particular.

Automotive Trends at the K 2019

Elektromobilität

Mobilität

Streifinger, Florian

Verbände, Institutionen, Messen

Dienstleistungen

Polyamide

Electromobility and a Concept Vehicle

Utech Europe, the world-leading polyurethanes exhibition and conference taking place at the MECC in Maastricht, the Netherlands has been rescheduled to 16–18 November 2021.

Kunststoffverarbeitung allgemein

Kunststoffverarbeitung

Utech Europe Rescheduled to November 2021

How can gas mixtures from industrial production be put to good use to produce valuable materials and save crude oil at the same time? The research consortium of the project Carbon4PUR has found answers to this question.

Valued Materials from the Chimney

Thanks to new technologies and together with other chemical derivatives the greenhouse gas CO2 can be converted into plastic precursors. Covestro is developing sustainable insulating materials for the construction sector based on this raw material.

Dämmstoffe

Using CO2 in Rigid Foam Insulation Boards

The Danish company Plastix recycles old fishing nets and ropes. The granules produced are used by JSP International, among others, to manufacture expanded polypropylene (EPP).

Expanded Polypropylene from Maritime Plastic Waste

Polypropylen-Compound

Kunststoff-Rezyklat

From Fishing Net to Particle Foam

Because of its good temperature resistance, impact resistance and aesthetics appearance, acrylonitrile-butadiene-styrene is often used in household goods and in the automotive industry. The development of a circular economy also shows successes.

Acrylonitrile-Butadiene-Styrene (ABS)

Kunststoffe

Photonik

Optik

Polystyrol

ABS / ASA-Kunststoffe

Technische Kunststoffe

Lightweight construction, functionality and design are characteristic of material development in all areas of application for PC compounds, composites and films. The range of materials has enormous opportunities when it comes to the mobility of the future, lightweight structural construction with continuous fiber-reinforced composites, 5G technology and medical technology.

Polycarbonate (PC)

Medizintechnik

Polycarbonat

Medizinprodukte

Present in a Multitude of Trends

Plastics processors have a wide range of colors at their disposal to color their products. Choosing the right color can ultimately be the key to success. But colors are just as subject to trends as materials and designs. Kunststoffe asked manufacturers of pigments, masterbatches, and colorants which colors would be particularly popular in the coming year.

Trend Report on the Coloration of Plastics

Pigmente

Additive

Pigmente, bunt

Masterbatches

Farbstoffe und Pigmente

Farbkonzentrate (Batches)

Farbstoffe

Effektpigmente

Farben, flüssig

What Will Be the Color of 2021?

Plastic waste in the sea has been shaping the negative image of the industry for several years. Various initiatives and mergers of companies have therefore launched projects to tackle this Ocean-bound Plastics (OBP). Components made of OBP could become a symbol for a sustainable use of plastics.

Flame Retardant for Compounds Based on Recycled Ocean-Bound Plastics

Polybutylenterephthalat

Polyethylenterephthalat

Flammschutzmittel

From the Sea to Electronics

Plastics are among the materials most widely used for food contact applications. While there is pressure to use recycled plastics in packaging in order to combat plastic waste, certain conditions must be met before food packaging can be considered safe.

Plastics Recycling for Direct Food Contact and Alternative Applications

Verpackungsmittel aus Kunststoffen

Food Safe Post Consumer Recyclate

Polymer materials, including synthetic polymers, have a bad reputation. These image problems do not just arise from the current environmental debate but also have earlier origins. In the past, too, polymer materials were subject to unjustified criticism. This often stemmed from non-scientists and frequently betrayed a lack of scientific knowledge.

On the Image of Plastics and their Responsible Use

Polymer Materials

Solvolysis Using Different Solvents in Practice

By means of high-performance processes, chemical recycling converts plastic waste into high-grade material for new plastic products. Moreover, freedom of design results by selecting a suitable process and the matching waste material. Hereby, the right combination permits customized polyols to be created for the desired application area.

Old mattresses, insulating material, furniture, and steering wheels – this raw material, which Rampf Eco Solutions GmbH & Co. KG, Pirmasens, Germany, processes, is not particularly appealing. The company has specialized on the recycling of polyurethane (PU) and polyethylene terephthalate (PET) waste material. For this, Rampf makes use of the solvolysis process in two of the largest multifunctional plants in Europe. Hereby, solvents are used to split the polymers – the urethane group in the case of PU, for example. The processes differ in the splitting medium applied. Water is used for the hydrolysis process, and acid for acidolysis. Depending on the process, this results in various polyols with different properties. Consequently, the most suitable polyols for the required application area can be created precisely by selecting the corresponding process.

The polyols produced in this way are then returned to the customer’s production facility either by Rampf Eco Solutions or another PU system company. Due to the renewed cross-linking, the materials reobtain their initial properties plus high quality. In this way, a recirculatory system is created, with combined economic and ecologic advantages.

For solvolysis, Rampf frequently relies on the glycolysis and acidolysis processes. With glycolysis, the urethane group is split by means of transesterification, mostly with bivalent alcohols (glycols, Fig. 1). The process can be used for practically all polyurethanes, although the hydroxyl value (OH value, which indicates the number of hydroxyl groups in a substance) is increased during the reaction. It even exceeds that of the initial polyol, which leads to a higher hardness of the end product. Therefore, polyols obtained with the glycolysis process are mainly used for the production of hard foams, hard integral foams, and durable integral foams.

In contrast, the acidolysis process splits the urethane group with acids or acid anhydride (Fig. 2). Compared with glycolysis, the acidolysis process is more complex and more expensive. Because it does not increase the OH value, the acidolysis process is used mainly to obtain polyols for the production of rigid foams, rigid integral skin foams and semi-rigid integral skin foams.

Neither process involves downcycling – instead they are self-supporting upcycling processes with a high added value. For example, by adding recycling polyols, the compressive strength of insulating foams, the chemical resistance of casting compounds, or the compatibility of polyurethane systems can be improved. Consequently, the polyols can be used for the production of numerous end products, e. g. mattresses, seating furniture, automobile and motorcycle seats, fitness and recreation products, as well as insulating materials.

Other polymers are also suitable for chemical recycling. For example, way back in 1999 Rampf Eco Solutions developed a process for chemical recycling of PET together with the Deutsche Gesellschaft für Kreislaufwirtschaft und Rohstoffe (German Society for Circular Economy and Raw Materials) in Cologne, Germany. The resulting polyols are mainly suited for the production of hard foams. High mechanical strength and improved flame retardance are the properties which are influenced decisively by these aromatic polyester polyols.

Also polyesters such as polylactide (PLA, polylactic acid), polycarbonate (PC) and polyhydroxyalkanoate (PHA) are used as raw material for producing recycled polyols. Chemical recycling of PC produces aromatic polyester polyols with rigid and very strong bisphenol A structural elements, making them highly suitable for mechanical reinforcement. The compressive strength of polyisocyanurate foams (PIR) could be improved significantly by adding PC polyols. In contrast, polyols made of bio-based PLA are purely aliphatic and very flexible. By adding these polyols, soft segments can be integrated in PU, and the embrittlement tendency of very strong hard foams and casting compounds reduced (Table 1).

Hence, functioning chemical recycling processes are available. But compared with mechanical recycling, their application is limited, although they are a good supplement for existing recycling systems – particularly for plastic waste that is difficult to recycle. For example, recycling of bulky waste still represents a great challenge. More than 60 % of the estimated 19 million t of furniture, mattresses, upholstery, textiles, and plastic garden furniture that are thrown away in European countries every year, finish up in landfills.

Therefore, to improve the logistics as well as the disposal and reuse of bulky waste, the recently completed Urbanrec project (Fig. 3) was initialized. Companies and organizations in seven countries participated, including national institutions in Belgium, Poland, Spain, and Turkey. Aim was the development and implementation of an ecologically effective and integral disposal system for bulky waste, in order to promote waste prevention as well as recycling, combined with improved logistics.

Within this project, and together with partner companies and institutions, Rampf Eco Solutions had the task of developing chemical solutions for obtaining high-grade recycled polyols from plastic waste such as mattresses and upholstery. The aim was to reduce the amount of waste delivered to landfills and incineration plants. In addition, new products based on the recycled raw materials were developed during the project, such as adhesives, foams, and insulating materials. Hereby, the polyols involved were produced with the glycolysis and the acidolysis processes.

The glycolysis polyols were used to produce insulating foams with a content of up to 50 % recycling polyol. Acidolysis polyols were used in the top layers of viscoelastic mattresses (12 % recycling content) and for PU hot-melt adhesives (up to 50 %). Hereby, it became clear that separation of the PU foam qualities – i. e. ether or ester foams based on methylene diphenylisocyanate (MDI) or toluene diisocyanate (TDI) – was necessary to ensure high-quality polyols. Separation was done by means of near infrared spectroscopy.

Basically, solvolysis is very suitable for obtaining chemical raw materials from PU and PET. Depending on the plastic waste and the required properties of the end product, the glycolysis or the acidolysis process is suitable. Gradually, chemical recycling is evolving into an alternative for mechanical recycling. Increasing prices for petrochemical products, tighter environmental regulations, and changing sustainability mindsets of consumers make it attractive. Moreover, projects such as Urbanrec illustrate the potentials of chemical recycling in practice.

Rampf Holding GmbH & Co. KG 

https://www.rampf-gruppe.de

Ausgabenartikel

Fig. 3. The Urbanrec project involved the recycling of bulky waste such as mattresses and furniture

Not only can multifunctional recycling plants split polyurethane by means of different processes; they are also able to recycle other plastics

Table 1. Performance data of Rampf’s alternative polyols, divided according to source materials

Fig. 2. Acidolysis of polyurethane: hereby, the urethane group is split by the addition of an acid

Fig. 1. Reaction equations for production and glycolysis of polyurethane

Rampf - Hauptartikel

Dr. Frank Dürsen works for the Rampf Group since 2011. As Head of Future & Sustainability, he is also involved in the development of thermosetting materials based on sustainable raw materials; frank.duersen@rampf-group.com

issue 04/2021

issue 03/2021

issue 02/2021

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