Composition and structure
The main component of Finnfoam is clear polystyrene.
Finnfoam is a cell plastic primarily made of polystyrene. Polystyrene is not hazardous to health and is frequently used as a packaging material for foods. Polystyrene is a recyclable plastic, which can be re-melted and used again as a raw material.
Another important component of Finnfoam cell plastic is carbon dioxide, which is obtained from sources including the emissions of other industrial plants. It therefore causes no negative environmental impact. The boards release the carbon dioxide, which is replaced with air, within a few weeks of manufacture. Polystyrene and carbon dioxide account for approximately 96–98% of the raw materials. The remainder consists of additives such as colour agents, process stabilisers and cell structure modifiers.
No CFC, HCFC or HCF gases or fire prevention materials that contain bromide compounds harmful to health are used in the production of Finnfoam. Finnfoam releases no gases, particles or fibres harmful to health. Finnfoam is classified as M1 – the best indoor emissions classification in Finland.
Finnfoam is an extrusion-compressed polystyrene (XPS) thermal insulation material. Its excellent characteristics are based on its cell structure, which is completely homogenous and closed – significantly different from, for example, the cell structure of EPS insulation materials.
Finnfoam's fully homogeneous cell structure is achieved using a production process where carbon dioxide is dissolved into melted polystyrene under high pressure. The carbon dioxide gasifies when it comes out of the nozzle into atmospheric air pressure. Cell structure modifier agents and machine settings are used to produce cells of the desired size and shape. The cells of the very strong boards (over 70,000 kg/m2) are in a slightly upturned position. In the production process, cells are produced at a rate exceeding over 23 billion per second.
Finnfoam insulation boards have a leather-like protective surface layer (cell diameter less than 0.1 mm).
In addition, during the manufacturing process, a uniform surface layer is created where instead of the cells, there is a homogenous layer of polystyrene. This homogenous surface layer repels water. The surface layers on both sides of the board along with the cell structure in the middle results in a layered board structure that further increases the stiffness of the board.