Bio-based plastic

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Packaging made from bioplastics ( cellulose acetate )

As bio-based plastics (English bio-based plastics ; also "technical biopolymers ") are plastics that are produced on the basis of renewable raw materials . Biodegradable plastics are to be distinguished from this , because biogenic origin and biodegradability do not necessarily go hand in hand.

Differentiation from other terms

Biodegradable plastics

Bio-based plastics are often referred to as bioplastics or bioplastics . However, these terms can be misunderstood and - depending on the definition - also designate plastics that are also or only biodegradable.

Due to the ambiguity, the terms bioplastics and bioplastics should therefore not be used.

Biobasedness is a property that both biodegradable plastics (e.g. PLA ) and non-biodegradable plastics (e.g. CA ) can have. In return, there are also biodegradable plastics that are not bio-based (e.g. PCL ).

Plastics can be bio-based (yellow and green), biodegradable (blue and green), or none of these.

history

Schildkröt doll Inge made of celluloid (1950)

Bio-based plastics were the first mass-produced plastics to be produced industrially. As early as 1869, the Hyatt brothers opened the first factory to manufacture celluloid , a thermoplastic based on cellulose. John Wesley Hyatt invented celluloid as part of a competition aimed at finding an inexpensive alternative to the ivory used in billiard balls . As a result, celluloid was used for a number of other uses, most notably for films, eyeglass frames, toys, combs and table tennis balls; however, due to its rapid flammability, it was quickly displaced. The material galalith (made from casein ) was invented in 1897 and is very similar to animal horn or ivory. For example, buttons, pins, housings for radios, cigarette boxes, toys, handles for umbrellas and much more were made in a wide variety of colors.

Printed cellophane bag and clear cellophane packaging

In 1923 the mass production of cellulose hydrate , the cell glass under the brand name "Cellophane", started, which was also based on cellulose and is mainly used for packaging as well as for use in envelopes. It was mainly used for the production of transparent foils, whereby the costs for the production were very high compared to later competitors and cell glass was thus displaced in many areas. However, due to its sensitivity to water, cellulose glass is coated with polyvinylidene chloride and is therefore no longer biodegradable.

The discovery of plastics based on mineral oils quickly resulted in competition in which the first bio-based ones were largely displaced. 1907 were purchased from Leo Baekeland the Bakelite invented thermosetting plastics on the basis of phenolic resin . Acrylic glass (polymethyl methacrylate), better known under the brand name Plexiglas, followed in 1930, followed by polyamide ( nylon , perlon ), polystyrene and polytetrafluoroethylene (Teflon). From 1956, large-scale manufacturing processes were finally introduced for the plastics polyethylene and polypropylene , which are still dominant today , and plastics were developed for a wide variety of applications with different material properties.

It was only after 1980 that there were innovations again in the field of bio-based plastics, which are primarily due to a change in ecological awareness. Renewable raw materials and closed material cycles were cited as arguments, later the substitution of crude oil as the main raw material came into play due to the rising oil prices and the finite nature of resources. While the number of new patents in the field of petrochemical plastics subsequently declined, patent applications for bio-based plastics, especially those based on starch and cellulose, increased. Currently, the development of bioplastics - although not necessarily more sustainable than conventional polymers - is being driven primarily on the basis of sustainability and resource conservation. Agricultural land for the material use of renewable raw materials will in future be regarded as an essential pillar of agriculture, with new technologies such as industrial white biotechnology also playing a major role in the development of new and the optimization of existing technologies. The new bio-based plastics include mainly thermoplastic starch (TPS), cellulose acetate and polylactides (PLA; only in "blends" (polymer mixtures)) during processes for the production of bio-based polyethylene (Bio-PE), polypropylene (Bio-PP) and others Plastics are developed and established.

Grouping of bio-based plastics

As mentioned above, bio-based plastics can be classified according to their biodegradability.

In addition, they are also classified according to how long they have been known. Bio-based plastics, which existed before petrochemical plastics, are known as the old economy . Examples of this are rubber and cellophane. Newer plastics are counted as part of the new economy , which in turn can be subdivided. On the one hand in novel bioplastics , these are plastics that are based on chemically novel polymers, such as PLA or PHA. On the other hand, in drop-ins, i.e. known polymers, in the manufacture of which fossil raw materials were wholly or partially replaced by renewable raw materials, such as bio-PET or bio-PE.

Raw materials and types of bio-based plastics

The main raw materials for bio-based plastics are currently starch and cellulose as biopolymers of sugars , possible starting plants are starchy plants such as corn or sugar beet and wood from which cellulose can be extracted. Other potential raw materials such as chitin and chitosan , lignin , casein , gelatine , grain proteins and vegetable oil can also be used for the production of bio-based plastics. Depending on their composition, the manufacturing process and the addition of additives , formability, hardness , elasticity , breaking strength , temperature and heat resistance and chemical resistance change .

Starch and starch blends

Cornstarch chips as children's toys

With a market share of around 80 percent, thermoplastic starch is currently the most important and most common representative of bio-based plastics. The most important plants that are used to produce starch are currently corn , wheat and potatoes in Europe, Africa and North America and tapioca in Asia. The raw mass is cleaned of by-products such as proteins , vegetable oils and vegetable fibers and prepared accordingly for use.

Pure starch has the property of absorbing moisture and is therefore mainly used in the pharmaceutical sector to produce drug capsule shells . Here, however, it was largely replaced by hard gelatine. Natural softeners and plasticizers such as sorbitol and glycerine are added to make the readily available starch thermoplastic . These additives allow a specific change in the material properties of the so-called thermoplastic starch, which is adapted to the intended use.

Thermoplastic starch, due to its negative property of absorbing water, is usually just one of the components from which modern starch-based products are made. The second basic component of these plastic blends consists of water-repellent, biodegradable polymers such as polyester , polyester amides , polyurethanes or polyvinyl alcohol . A plastic blend is therefore composed of the hydrophobic polymer phase and the disperse and hydrophilic starch phase. During the melting process in the extruder , the water-soluble, disperse starch phase and the water-insoluble, continuous plastic phase combine to form a water-resistant starch plastic. These findings formed the basis for the further development and the eventual breakthrough of starch plastics (EP 0596437, EP 0799335).

Starch blends and compounds are developed and produced individually for further use in the plastics processing industry, depending on the area of ​​application. As plastic granulates , they can be processed into foils, thermoformable flat foils, injection molded articles or coatings on the existing systems. Examples of this are carrier bags, yoghurt or drinking cups, plant pots, cutlery, diaper foils, coated paper and cardboard. Starch can also be thermoplastically modified by chemical changes such as conversion to starch esters or starch ethers with a high degree of substitution. However, because of the high costs involved, these methods have not yet caught on.

Cellulose products

Transparent cellulose acetate cubes

Just like starch, cellulose is also a natural biopolymer made from sugar molecules. Cellulose is the main structural building material in most plants alongside lignin and can accordingly be obtained from plant material. Their share is almost 95 percent for cotton , 75 percent for hemp , 40 to 75 percent for hardwood and 30 to 50 percent for softwood . Accordingly, cellulose is the world's most important renewable raw material after wood and around 1.3 billion tons of it is used annually. The cellulose is cleaned of lignin and pentoses using various chemical processes and processed into cellulose , the basis for paper , cardboard and other materials such as viscose .

The production of bio-based plastics based on cellulose usually requires further chemical modification. The purified cellulose is mainly esterified in order to obtain cellulose acetate (CA) as the most important cellulose-based plastic. Cellulose acetate is counted among the thermoplastics, is a correspondingly modified natural substance that is neither biodegradable nor compostable. As early as 1919, a cellulose acetate modified with plasticizers was patented as the first injection molding compound, thus enabling completely new and very effective production methods for umbrella handles, keyboards, steering wheels, toys, pens and many other products.

Also, the celluloid and the cellophane , plastics are based on cellulose . Other cellulose-based plastics are vulcanized fiber , cellulose nitrate , cellulose propionate and cellulose acetate butyrate .

Polylactic acid (PLA)

The polylactic acid (polylactide, PLA) is produced by polymerization of lactic acid , which in turn is a product of fermentation of sugar and starch by lactic acid bacteria is. The polymers are then mixed during the polymerization from the different isomers of lactic acid, the D- and the L-form, according to the desired properties of the resulting plastic. Other properties can be achieved through copolymers such as glycolic acid .

Packaging for sweets made from polylactic acid (PLA)

The transparent material not only resembles conventional mass-produced thermoplastics in terms of its properties, but can also be easily processed on existing systems. PLA and PLA blends are offered as granulates in various qualities for the plastics processing industry for the production of foils, molded parts, cans, cups, bottles and other commodities. The raw material has great potential, especially for short-lived packaging films or thermoformed products (for beverage and yoghurt cups, fruit, vegetable and meat trays). The world market for the "transparent plastics" market segment was already 15 million tons in 2001. The transparency is not only positive for packaging , it also has advantages for applications in the construction industry, technology, optics and automotive engineering. There are also lucrative specialty markets, for example in the medical and pharmaceutical sectors, where PLA has been used successfully for a long time. Screws, nails, implants and plates made from PLA or PLA copolymers that can be absorbed by the body are used to stabilize bone fractures. Resorbable suture material and active ingredient depots made of PLA have also been in use for a long time.

Piggy bank made from PLA

A great advantage of PLA is the special diversity of this bio-based plastic, which can be made to be quickly biodegradable or to work for years. Further advantages of the polylactide plastics are the high strength, the thermoplasticity and good processing on the existing systems of the plastics processing industry. Nonetheless, PLA also has disadvantages: since the softening point is around 60 degrees Celsius, the material is only partially suitable for the production of drinking cups for hot drinks. The copolymerization to form more heat-resistant polymers or the addition of fillers can ensure greater temperature stability. The Japanese electronics company NEC Corporation was able to remedy the heat sensitivity by reinforcing it with kenaf fibers and metal hydroxides, thus developing an easily malleable and flame-retardant material. The first product to be developed for the Japanese market was the housing of the FOMA N701iEco cell phone . For the production of PLA from glucose via the intermediate steps lactic acid and dilactide, there are both batch processes and - so far largely implemented on a pilot scale - continuous processes. This enables the industry to manufacture the material inexpensively and in the medium term competitive with mass plastics. The world's first larger PLA production plant was put into operation in the USA in 2003, with a theoretical annual capacity of 70,000 t. Further systems are available internationally today. A first German pilot plant for the production of PLA was put into operation in 2011 in Guben, Brandenburg, with a capacity of 500 t; a second plant in Leuna should start production in mid-2012.

Polyhydroxyalkanoates, especially polyhydroxybutyric acid (PHB)

The biopolymer polyhydroxybutyric acid (PHB) is a polyester that can be produced by fermentation and has properties similar to those of the petrochemically produced plastic polypropylene . It can be made on the basis of sugar and starch, but synthesis is also possible from other nutrients such as glycerine and palm oil.

Numerous companies around the world are announcing that they are going into PHB production or expanding their production. In addition to some medium-sized manufacturers, the South American sugar industry is now also planning to manufacture PHB on an industrial scale. PHB is biodegradable, has a melting point of over 130 ° C, forms clear films and has optimal mechanical properties for many applications. Obtaining the plastic from the bacteria is one of the main difficulties. The cells have to be lysed by chloroform or enzymes , and one kilogram of PHB currently requires three kilograms of sugar, which is limited mainly due to the high demand for biofuels and the food industry.

PHB is also used in combination with other ingredients as a PHB blend. Special material properties can be achieved by adding cellulose acetates , for example. The range of properties of PHB blends extends from adhesives to hard rubber. Instead of cellulose acetate, starch, cork and inorganic materials are also conceivable as additives. Mixing it with cheap additives (cellulose acetate is an inexpensive waste product from cigarette filter production) also has a positive effect on the production costs of PHB blends. In the medium term, according to numerous researchers, this will reduce manufacturing costs down to the area of ​​petroleum-based plastic materials.

Other biopolymers

Drug capsules made from hard gelatine

In addition to the bio-based plastics mentioned, there are a number of approaches to using other renewable raw materials such as lignin , chitin , casein , gelatine and other proteins as well as vegetable oils (e.g. castor oil ) for the production of bio-based plastics. Arboform was developed as a lignin plastic back in 1998 and is still marketed today; the material is used for consumer goods and in the automotive industry. Chitosan as a product made from chitin waste from shrimp recycling is also established as a raw material for fibers, foams, membranes and foils. In addition, plastics are produced that are based to a relatively large extent on renewable raw materials, such as the biodegradable plastics Ecovio from BASF with 45% PLA and polytrimethylene terephthalate (PTT) from DuPont .

More recently, some companies have pursued the strategy of replacing the fossil raw material base of established standard thermoplastics with a renewable raw material base; Examples of this are Bio- PE and Bio- PP based on sugar cane in Brazil. Biorefineries are also being researched, which are also supposed to produce platform chemicals for the chemical industry on the basis of biopolymers such as sugar, starch or lignocellulose with the help of white biotechnology .

Current scientific research and developments also aim to produce plastics from agricultural residues and by-products.

Certification

The term “bio-based plastic” is not protected, so there is no statutory minimum percentage that is necessary for the use of the term. However, there are two different voluntary certification systems in which different logos are awarded, depending on the proportion of carbon atoms in the product that are of biological origin.

DIN CERTO

The DIN CERTO certification distinguishes between three levels (20–50%, 50–85% and> 85%), each of which has its own logo on which the level is also specified. It is also required that the proportion of organic material must be greater than 50%.

Vincotte

The Vincotte certification has four different logos, in which the number of stars allows conclusions to be drawn about the proportion of bio-based carbon atoms. The gradations are 20–40% (one star), 40–60% (two stars), 60–80% (three stars) and 80–100% (four stars).

Ecological aspects

Bio-based plastics obtained from plants only release as much CO 2 during degradation or when used for energy purposes as they absorbed during the growth phase. This gives them an advantage over plastics based on petrochemicals in terms of CO 2 emissions based on the raw materials. However, bio-based plastics are not CO 2 neutral as their transport and manufacture cause emissions. Overall, there is too little data on environmental and socio-economic influences to comprehensively compare conventional and bio-based plastics in this regard. In addition, existing data can only be compared to a limited extent due to different measurement methods. Sufficient data is only available in relation to the global warming potential that is somewhat comparable and shows an advantage of bio-based plastics over conventional plastics. Individual studies show that petrochemical plastics have advantages in terms of eutrophication potential and soil acidification .

Market situation and prospects

Today, standard plastics are mainly made from crude oil , less often from natural gas or other raw materials. The price of crude oil therefore has a direct impact on the price of plastics. Factors that are causing this price to rise are above all the increasing global demand for energy and raw materials and political conflicts in the producing countries. In contrast , fracking , which is particularly widespread in the USA, increases the supply of fossil raw materials and therefore lowers their price. So far, bioplastics can hardly compete with conventional plastics in terms of price. Nevertheless, their market share is increasing rapidly. One reason for this is the growing environmental awareness among industry and end consumers, who also want appropriate packaging for organic food, for example.

In 2018, the production capacity of bio-based and partially bio-based plastics totaled approx. 19 million tons and thus almost 6% of the production capacity of all plastics. Growth to a share of 10% is expected by 2023. The market for bio-based new economy plastics is growing particularly strongly , which in 2018 comprised 2.27 million tons. Almost 40% of the bio-based New Economy plastics were also biodegradable.

literature

  • Hans-Josef Endres , Andrea Siebert-Raths: Technical biopolymers. Hanser-Verlag, Munich 2009, ISBN 978-3-446-41683-3 .
  • Jürgen Lörcks: Bioplastics. Plants - raw materials, products. Fachagentur Nachwachsende Rohstoffe eV, Gülzow 2005. ( PDF download )
  • P. Eyerer, P. Elsner, T. Hirth (Eds.): The plastics and their properties. 6th edition. Springer Verlag, Heidelberg 2005, ISBN 3-540-21410-0 , pp. 1443-1482.
  • Jörg Müssig, Michael Carus: Bio-polymer materials as well as wood and natural fiber reinforced plastics. In: Market Analysis of Renewable Raw Materials Part II. Agency for Renewable Raw Materials eV, Gülzow 2007. ( PDF download )
  • Biodegradability and compostability ( Memento from May 29, 2017 in the Internet Archive )

Broadcast reports

Web links

Individual evidence

  1. ↑ Michael Thielen: Bioplastics. Fachagentur nachwachsende Rohstoffe eV (FNR), 2019, accessed on 23 September 2019 .
  2. ↑ Keyword bioplastics in: Brockhaus Enzyklopädie online, accessed on August 8, 2008.
  3. ↑ Hans-Josef Endres & Andrea Siebert-Raths: Technical biopolymers - framework conditions, market situation, production, structure and properties . Hanser Verlag, Munich 2009, ISBN 978-3-446-41683-3 , p. 6 .
  4. ↑ European Bioplastics: What are bioplastics? Retrieved September 23, 2019 .
  5. ↑ a b Fachagentur Nachwachsende Rohstoffe eV (FNR): 10 points on bio-based plastics. 2018, accessed September 23, 2019 .
  6. ↑ Neus Escobar, Salwa Haddad, Jan Börner, Wolfgang Britz: Land use mediated GHG emissions and spillovers from increased consumption of bioplastics. In: Environmental Research Letters. 13, 2018, p. 125005, doi : 10.1088 / 1748-9326 / aaeafb .
  7. ↑ Preliminary studies by the FOEN: The challenging path to more transparency on the store shelf. In: bafu.admin.ch . Retrieved October 2, 2019 .
  8. ↑ a b Institute for bioplastics and biocomposites (IfBB): Biopolymers - Facts and statistics - capacities Production, processing routes, feed stock, land and water use. 2018, accessed September 20, 2019 .
  9. ↑ Future market for bioplastics (PDF; 563 kB), on Umweltdaten.de
  10. ↑ a b Veronika Szentpétery: Naturally artificial. Technology Review September 2007, pp. 89-90.
  11. ↑ Sven Jacobsen, 2000: Representation of polylactides by means of reactive extrusion. Dissertation, University of Stuttgart, p. 16. ( PDF available online ( Memento from March 4, 2016 in the Internet Archive ))
  12. ↑ Chris Smith: Natureworks PLA capacity is 70,000tpa. prw.com dated December 10, 2007.
  13. ↑ Press release from Uhde Inventa-Fischer December 1, 2011, accessed March 30, 2012.
  14. ^ Elisabeth Wallner: Production of polyhydroxyalkanoates on the basis of alternative raw material sources. Dissertation at the Institute for Biotechnology and Bioprocess Engineering, Graz University of Technology, 2002.
  15. ↑ PE-HD bio-based on materialarchiv.ch, accessed on March 22, 2017.
  16. ↑ Birgit Kamm: The concept of the biorefinery - production of platform chemicals and materials. In: Brickwede, Erb, Hempel, Schwake: Sustainability in chemistry. 13th International Summer Academy St. Marienthal. Erich Schmidt Verlag, Berlin 2008.
  17. ↑ Hans-Josef Endres, Maren Kohl & Hannah Berendes: Bio-based plastics and bio-based composite materials . In: Market analysis of renewable raw materials (= Fachagentur Nachwachsende Rohstoffe eV [Hrsg.]: Series of publications renewable raw materials . Volume 34 ). 2014, chap. 5 , p. 206-208 ( fnr.de [PDF]).
  18. ↑ Oliver Türk: Material use of renewable raw materials . 1st edition. Springer Vieweg, Wiesbaden 2014, ISBN 978-3-8348-1763-1 , p. 431-438 .
  19. ↑ a b Sebastian Spierling, Eva Knüpffer, Hannah Behnsen, Marina Mudersbach, Hannes Krieg, Sally Springer, Stefan Albrecht, Christoph Herrmann & Hans-Josef Endres: Bio-based plastics - A review of environmental, social and economic impact assessments . In: Journal of Cleaner Production . tape 185 , 2018, p. 476–491 , doi : 10.1016 / j.jclepro.2018.03.014 .
  20. ↑ Stefan Albrecht, Hans-Josef Endres, Eva Knüpffer & Sebastian Spierling: Bioplastics - quo vadis? In: UmweltWirtschaftsForum (uwf) . tape 24 , 2016, p. 55-62 , doi : 10.1007 / s00550-016-0390-y .
This version was added to the list of articles worth reading on August 13, 2008 .