ECOLOGICAL BOARDS MADE OF SUNFLOWER WASTES FOR EXTERIOR LINING AND PROCESS FOR MAKING THE SAME

摘要

The invention relates to an ecological board made of sunflower wastes, i.e. sunflower seed hull, meant for exterior lining in sandwich structures of civil and industrial wooden constructions. According to the invention, the board is made of a mixture consisting of sunflower seed hulls, as reinforcing elements, having a humidity in the range of 8.5...9%, 5.5% polyurethane adhesive, 15% water, 1% paraffin emulsion at a volume mass = 480...490 kg/m, a thermal conductivity coefficient = 0.074 W/mK, a thickness swelling after an immersion of 24 h u= 19...20%, formaldehyde emission E= 0.8 mg/mh, elasticity modulus E= 1900...1970 N/mm, bending strength f= 7.1...7.5 N/mm, internal cohesion f= 0.9...1.7 N/mmand a maximum screw pull-out force F= 480...560 N. The process, as claimed by the invention, consists in mixing the sunflower seed hulls with polyurethane adhesive in a ratio of 5.5%, water in a ratio of 15% and paraffin emulsion in a ratio of 1%, at the ambient temperature, the mixture being then poured into a mould having the dimensions of 620x620x16 mm, the mould being introduced into a press where it is subjected to a uniform pressure of 50 bar, at a temperature of 180°C, for 5 min, after which the boards are conditioned for 24 h at the ambient temperature and dimension-cut by removing 10 mm from the edges.