Synthetic fibers are widely used as reinforcing materials for rubber products such as tires and automobile hoses. In general, RFL adhesive (Resorcinol, Formaldehyde, Latex) is used to bond rubber and fibers. However, resorcinol and formaldehyde are chemicals with a high environmental impact, and with the recent rise in environmental awareness, there is a growing need for the development of new eco-friendly RF-free adhesives. Toray has developed an eco-friendly adhesive for rubber reinforcing fibers that does not contain resorcinol/formaldehyde (RF) and uses plant-derived materials as alternative ingredients. Reinforcement fibers (dip cords) using this RF-free adhesive exhibit adhesive strength equivalent to that of RFL adhesives for various rubber applications. It was also confirmed that the existing production equipment can be utilized in dip cord processing production using new RF-free adhesives.