Alternative flame retardants for plastic materials in electrical and electronic applications

Sammanfattning

Flame retardants (FRs) are incorporated into plastic materials used in electrical and electronic applications to enhance fire safety by delaying ignition and slowing the spread of flames. The global FR market is expected to continue growing, largely driven by increasing demand in the electrical and electronics sector. However, increasing evidence shows that certain traditional FRs pose significant environmental and human health risks. NIBE is a Swedish manufacturer of energy solutions such as heat pumps, ventilation systems, and other indoor climate technologies. As part of its sustainability strategy, the company is engaged in investigating safer alternative FRs for use in its products. This thesis examines sustainable alternatives to harmful FRs used in plastic materials for electrical and electronic products. The objective is to identify and assess these alternatives in terms of flame-retardant performance, technical feasibility, and environmental and health impacts. In addition, the study provides an overview of commonly used FRs with environmental and health risks, relevant regulatory frameworks, as well as the research gaps and challenges associated with the implementation of alternative FRs. This literature study has identified 28 substances as alternative FRs. They are categorized into four groups: organic, inorganic, nanomaterial, and bio-based substances, each with varying properties, performance, and limitations. Organic alternatives such as pentaerythritol and triazine compounds perform effectively in intumescent systems, while inorganic alternatives including aluminium and magnesium hydroxide offer broad plastic compatibility but require high loading levels. Several zinc-containing substances have been identified as safer alternatives to diantimony trioxide. The nanomaterials montmorillonite (MMT), layered double hydroxides (LDHs), molybdenum disulphide, MXenes, graphene, and carbon nanotubes (CNTs) improve flame retardancy and mechanical properties of composites at low concentrations. However, surface modification is required to ensure efficient performance, and the practical application of MXenes, graphene, and CNTs is limited due to high production costs. Further research is also needed to understand their long-term environmental and health impacts. The bio-based substances cellulose, chitosan, lignin, phytic acid, and deoxyribonucleic acid (DNA) are among the most sustainable options identified, although challenges remain related to high production costs and the need to improve both performance and quality consistency for industrial applications. While none of the alternatives identified in this study is currently subject to regulatory restrictions, many have self-classified risks such as eye and skin irritation, respiratory irritation, and acute toxicity if swallowed, inhaled, or in contact with skin. The findings also show that several widely used FRs such as certain halogenated and organophosphorus compounds, as well as melamine and boric acid are classified as substances of very high concern (SVHCs) under REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals). Other substances including some borate substances, diantimony trioxide, and silicon-based compounds are under regulatory review due to their potential hazards. Moreover, nitrogen-containing FRs raise concerns due to exposure patterns similar to those of organophosphorus compounds. In addition to REACH, other regulatory frameworks such as RoHS (Restriction of Hazardous Substances), WEEE (Waste Electrical and Electronic Equipment), CLP (Classification, Labelling and Packaging), ESPR (Ecodesign for Sustainable Products Regulation), and the Stockholm Convention also help regulate harmful substances and promote the use of safer alternatives. This study highlights the importance of conducting regular risk assessments of FRs throughout their entire life cycle to prevent regrettable substitutions, and emphasizes the need for improved waste management and responsible chemical handling to ensure their sustainable use.