Natural Colorants in the Mass Coloration of Plastics

Environmental concerns with regard to microplastics, disposed or incinerated wastes, and sustainability as well as potential impact on global warming have altered the assessment of polymers used for manufacturing of mass products. Many pigments and synthetic dyes used at present in mass coloration of plastics exhibit low biodegradability and thus will be released into the environment in case of biodegradation of the polymer matrix. Natural colorants can be understood as a group of dyes for which we can expect good environmental compatibility; thus, in particular when biodegradation of the polymer is the foreseen pathway, the use of natural colorants will be a valuable alternative to improve overall environmental compatibility of such polymer-based products. The use of natural colorants for mass coloration of polymer material is of growing interest; however, activities are mainly on scientific level and research is required for successful future introduction in production scale. In this chapter, general requirements for the use of natural colorants and pigments, for example, dye lakes, for mass coloration of plastics are discussed. Representative examples for approaches to substitute synthetic dyes with nature-based dye products in mass coloration of polymers are given.