Patent DE-3163745-D1 (DE)
Title: Method for the manufacture of fire-resistant building slabs
Inventor: ZIDAR ANTON DIPL ING
IPC: E04B1/94
Filed: 1981-07-02
Granted: 1984-06-28
Abstract: 1. A method of manufacturing pressed, fireproof, three-ply building boards made from inorganic expanded material, in which method the granules of expanded material, that is to say expanded vermiculite or expanded perlite for the outer layers and/or expanded vermiculite or expanded perlite for the inner layer, are first separately glued with water glass as an inorganic bonding agent and/or with thermosetting resin and/or with monoaluminium phosphate, a first layer of glued vermiculite or glued perlite occupying 1/6 of the total thickness is then deposited, the centre layer of glued vermiculite and/or glued perlite occupying approximately 4/6 of the total thickness is deposited thereon and, finally, the second layer of glued vermiculite or glued perlite occupying approximately 1/6 of the total thickness is finally deposited thereon and, after a pre-pressing stage, this three-layer deposit is solidified under the application of pressure and heat, characterised by the method steps in which a) a mixture comprising expanded vermiculite or expanded perlite and a solution of water glass with 48-50 Be and urea is used for the outer layers of the board and is used to glue the vermiculite or the perlite, the proportion of solids in the solution being up to 41% and the proportion of moisture in the mixture being up to 40%, in each case calculated to the weight of the vermiculite or of the perlite each in its absolutely dry state, b) expanded vermiculite and/or expanded perlite and the waste products largely originating from dry waste products, namely dust occuring during expanding and the cooling of granulated material and the machining of the edges of the boards, and crushed trimming residues, are used for the centre layer of the board, and the mixture of vermiculite and/or perlite and the waste products is resinified with an approximately 70% solution of phenolic resin and is glued with a 50% solution of monoaluminium phosphate and urea, the solids content of the two components being up to 24% relative to the weight of the mixture in its absolutely dry state, the ratio of the solids of the phenolic resin to the solids of the monoaluminium phosphate being 40 : 60, the moistness of the glued mixture being up to 18%, and the glued mixture for the centre layer containing up to 17.5% less solids in the bonding agent and up to 23.4% less moisture than the glued granulated vermiculite or granulated perlite for the outer layer, c) the components serving as a bonding agent are tempered to a temperature of from 25 to 30 degrees C before glueing and are then sprayed separately onto the granulated material by conducting the expanded granulated material as a falling curtain through a mist produced by spray guns from the bonding agent, d) the three-layer deposit is solidified at a temperature between 170 and 210 degrees C, such that, commencing from a high initial pressure, the pressure exerted by the heating plates on the article being pressed is reduced within predetermined intervals of time.