Pages 173–176
Abstract
Research summary supplied by the authors
In the finishing process for grain corrected leather, a common technique involves buffing the grain side with buffing paper, then impregnating it with synthetic resin to tighten the surface. Conventionally used synthetic resins have leaned heavily toward components forming rigid structures, such as urethane and acrylic, many of which are derived from fossil fuels. Against this background, the leather industry cannot ignore the trend toward Sustainable Development Goals (SDGs), needing the development of new materials aimed at reducing environmental impact. Therefore, this study focuses on carbon-neutral natural rubber, sourced from the Hevea brasiliensis tree, as a natural material alternative to conventional synthetic resins. Just as leather is a sustainable material, natural rubber also has sustainability. Combining the two is expected to yield synergistic effects. Furthermore, natural rubber supplied as an emulsion can undergo chemical modification. It has recently garnered renewed attention, and application development is progressing. Natural rubber also combines flexibility with excellent mechanical properties and has the characteristic of allowing elastic modulus control through vulcanization, making it promising as a leather finishing material. This study aimed to develop a leather finishing technology using natural rubber. We conducted solid viscoelasticity measurements, evaluated the permeability and coating properties of natural rubber formulations, and produced prototype leather samples. The results showed that the prototype leather showed higher tear strength compared to Raw hides used as materials for leather production vary individually. Raw hides with minimal damage, such as scratches and pinholes, are used as grain leather with thin coatings that preserve the grain surface, which is the surface of the dermis after removing hair and epidermis, and greatly affects the product value of leather. Conversely, raw hides with considerable damage cannot use the grain surface and are processed into buffed leather by sanding the grain with sandpaper. Buffed leather is characterized using coatings containing pigments, which conceal grain damage to some extent and result in a uniform appearance and high yield. In Japan, the volume and quality of imported raw hides have been declining annually, making finishing technology for buffed leather increasingly important. In the finishing process of buffed leather, after buffing the grain surface with sandpaper, synthetic resin is impregnated to tighten the grain. The synthetic resins used in the leather industry are mainly hard-structured resins such as urethane and acrylic, most of which are derived from fossil fuels. The leather industry cannot ignore the trend toward SDGs, and proactive efforts toward sustainable development goals are required. Here, we focused on carbon-neutral natural rubber harvested from the Para rubber tree as a natural alternative to these synthetic resins. Natural rubber is soft and has strong Corresponding author email : washiya@lyogo-kg.jp conventional products, suggesting the potential applicability of natural rubber.