Circular economy in the plastics industry
The introduction of closed loop recycling management in the plastics industry is overdue. Imperfect waste management systems lead to the pollution of nature. Social environmental awareness is growing, consumers prefer to buy recycled products – forcing more and more companies to rethink. At the same time, recycling plastics is a challenge.
Therefore, a circular economy model needs to be developed in which plastic waste generated after production (post-industrial or pre-consumer waste) and after the use phase of the products (post-consumer waste) can be recycled and recovered as effectively as possible.
What makes recycling plastic difficult?
The challenge to optimize recycling is to generate a plastic waste that is of a single-variety as possible. Unlike material waste such as metal, glass or paper, the waste management and recycling system for plastic waste must technologically cover a much wider variety of materials, products and designs. Diverse recycling approaches such as mechanical, chemical or solvent-based recycling are used today. Mechanical recycling is already well developed, while the other processes are mostly still being scaled up and still require a lot of research work.
In addition to the technological aspects, logistics and the availability of sufficient plastic waste are prerequisites for a plastics recycling economy. Currently, recyclate demand in the market exceeds the supply, despite the known amounts of waste in nature. The imperative is to get plastics to where they can be recycled, so they can later be processed as recyclates all over the world.
Uniformly characterize plastic recyclates: DIN SPEC 91446
Introduction of a sustainable recycling economy is difficult due to different reasons. Firstly, the legal and normative requirements in some cases vary greatly from region to region. Furthermore, different terminology has historically been established in practice for different applications. Finally, strongly insufficient normative requirements for characterisation of the plastic recyclates cannot promote their practical use.
To overcome this challenge, a consortium consisting of 16 members from industry, science, and associations under the technical leadership of IKK was formed in 2021 and developed a first standard for plastic recyclates. Initiated by cirplus GmbH, which founded a virtual marketplace for plastic waste and recyclates and needed standards for evaluating recyclates to do so, “DIN SPEC 91446, Classification of recycled plastics by Data Quality Levels for use and (digital) trading” has now been available since the beginning of the year.
Since this standard was explicitly developed for the characterization of plastic recyclates, it places particular emphasis on the history of the material and on the internationally standardized determination of the material properties as well as the correct wording.
Data Quality Levels (DQL) for plastic recyclates
Plastic recyclates are classified into four Data Quality Levels (DQL) according to the depth of information (see Figure 2). The more information available on a recyclate, the higher the DQL categorization and the higher the monetary value and marketability. Thus, this standard simplifies communication between international B2B decision-makers and indirectly promotes rapid market introduction of newly developed plastic recyclates, since the newly developed high-value plastic recyclates are characterized according to a standard known in the industry.
In order to characterize a plastic recyclate according to DIN SPEC 91446 for the lowest level DQL 1, it is sufficient to determine the recyclate content of a material type (PE, PP, PET, etc.) using a specified procedure.
In contrast, characterization according to the highest DQL 4 requires additionally a detailed description of the recyclate history and the material properties. This includes, for example, the presence of fillers and colors, the recycling technology used, the recycled state, the waste source, the content of other plastics (determined using specified measurement methods), the primary use before disposal or the description of the waste (bottles or containers, injection molded parts, mixed plastic waste), and a standard-compliant determination of the material properties such as viscosity, ash content, residual moisture, density, bulk density, thermal and mechanical properties, and much more.
Recyclate, regrind, regranulate: DIN SPEC creates uniform definitions
In addition to characterizing material properties, DIN SPEC defines important terms such as recyclate, regrind, regranulate or recompound in the context of plastics recycling. These terms are not protected and are sometimes used differently in international practice.
The developed standard defines “recyclate” as a generic term (see Figure 3) for
- “Regrind” – grinded recovered plastics material, which is used directly in production in some applications such as construction
- “Regranulate” – input stream processed by a remelting process such as extrusion without changing its composition
- “Recompound” – input stream modified by the addition of virgin material or additives during a remelting process.
In addition, it makes clear specifications on how the recycled content is to be correctly calculated and stated.
Technology transfer from research to industrial practice
In its application-oriented research projects, IKK has frequently worked on the correct characterization of recyclates. This experience has been incorporated into the DIN SPEC, and now IKK characterizes all of the developed plastic recyclates at institute according to DIN SPEC 91446, DQL 4, in order to enable, together with industrial partners, a timely implementation and use of high-quality recyclates in practice.
At the same time, it is not only in the area of material development of recyclates, but also in the area of process and technology development that it is crucial for rapid research transfer to use uniform definitions. Standards thus play an essential role in the transfer of research findings into practice.
For the future, it is planned to develop further plastics- and industry-specific sub-standards for the characterization of plastics recyclates based on DIN SPEC 91446, which, among other things, take into account the special requirements of individual applications or are specific to certain material types such as polyamides.