INFLUENCE OF RAW-MATERIAL QUALITY AND PROCESS PARAMETERS IN THE PRODUCTION OF INSULATION CORK AGGLOMERATES

Insulation cork agglomerates are produced with different low-cost raw-materials unsuitable for other products: virgin corks (from prunings, thinnings and dead trees), reproduction corks (refuse and underaged) and industrial byproducts (corkback strips). These materials were analysed in relation to chemical composition, structure and trituration behaviour. The industrial byproducts differ significantly from the other materials due to the presence of an important amount of the unsuberised lignocellulosic phloem (the back of the corkboards) in a way that is detrimental to the agglomeration process. The influence of raw-material, granulometry and process parameters (time, temperature and pressure) were studied using an experimental autoclave. Temperature is the determining factor for agglomeration. Insufficient adhesion is obtained under 230-degrees-C and adequate agglomeration is attained only with temperatures in the range 230-300-degrees-C, corresponding to mass losses of 10-25%.