Industrial scale-up of bio-based insulating panel production

Abstract

ISOBIO Project aims to produce highly insulating panels from bio-resources. This study focuses on the constrains associated to the production of panel at the industrial scale using thermal treatment. Three types of processes are considered (wet processes for rigid panels, dry processes for rigid or flexible panels and Stramit process®) and the limits of each process are identified according to the formulation characteristics (moisture content, binder type and content), binding mechanisms (melting, thermosetting or drying), process parameters (pressure, time and temperature) and targeted material properties (density and thickness). Cavac Biomatériaux industrial oven is used to study the dry and wet processes for the production of rigid panels. The temperature distribution in the material thickness was recorded. Difficulties to reach sufficient temperature level for high panel thicknesses or for high water content are observed. As a consequence, an excessively long drying time is needed to produce rigid panel using the wet process. Only small panel thicknesses are possible options. The addition of thermosetting binder is an alternative way to reduce water content and processing time. Rigid panel are easily produced using the dry manufacturing process and a hydraulic press with hot plates. Various tests are performed adjusting panel characteristics and formulations. Interesting results are obtained with hemp shiv bonded with a bio-based thermosetting binder. The binder content ranged from 5% to 23% and the targeted density from 155 to 245 kg/m3. Mechanical characterization shows that the binder formulation, proportion, water content and panel density are crucial parameters to be adjusted to optimize panel manufacturing process and properties. The dry process appears more versatile than wet process and leads to lower processing time. It allows the production of hemp shiv insulation panels within a large range of density and having compressive and flexural strength reaching 1 and 1.7 MPa respectively.