This study evaluates the thermoacoustic performance of a composite material formulated from high-density recycled plastic (HDPE) and a bovine-derived biobinder. Three 10x10x2 cm cubic specimens were manufactured and subjected to controlled thermal conductivity and airborne sound attenuation tests, comparing them with glass wool and polyurethane foam specimens. The biobinder was obtained by cooking and filtering bovine dermal collagen, while the recycled plastic corresponded to HDPE granules smaller than 0.5 cm. The mixture was prepared maintaining specific matrix-binder ratios and cured under controlled conditions for physicochemical stabilization. The experimental results indicate that the composite material presents a lower conductive heat flux than conventional insulators, demonstrating a greater thermal insulation effect. In terms of acoustic insulation, the composite exhibited comparable performance to polyurethane foam and glass wool, achieving similar levels of sound absorption and attenuation after 300 seconds of measurement. Swelling and absorption tests remained below 3% for all materials evaluated. These findings demonstrate that the proposed material constitutes a sustainable, efficient, and competitive alternative to traditional insulation, with potential application in steel frame construction systems and buildings seeking to optimize energy efficiency and acoustic performance.