Repairing metal-polyurethane-metal sandwich elements for ships or buildings involves cutting out the damaged part, removing plastic to leave overhanging metal, replacing the metal and filling the space with isocyanate and polyol

摘要

Metal-polyurethane-metal sandwich elements are repaired by cutting out the damaged part, removing the plastic interlayer so that the metal extends by at least 7 cm beyond the plastic at the cut edge, replacing the cut-out metal with new metal and reacting isocyanates with isocyanate-reactive compounds in the space thus formed between the metal layers. A method for repairing composite elements comprising the following layers: (i) 1-20 mm metal, (ii) 10-300 mm polyisocyanate-polyaddition product obtained by reacting (a) isocyanates with (b) isocyanate-reactive compounds (iii) 1-20 mm metal. The method involves cutting out a section containing (i), (ii) and optionally (iii), removing (ii) at the cut surfaces of the remaining element so that layer (i) and optionally (iii) extends beyond (ii) by a distance (x) of at least 7 cm, replacing the cut-out metal by new layer(s) (ia) and optionally (iiia) and bonding these new layers with the remaining layers (i and iii), and then reacting components (a) and (b) in the space thus formed between the metal layers. Independent claims are also included for composite elements obtained by this method and ships or buildings containing such composite elements.