DE2409237

1436930 Laminates UBE INDUSTRIES Ltd 14 March 1974 [27 July 1973] 11504/74 Heading B5N A composite plate comprising at least one aluminium plate and at least one stainless steel plate is produced by interposing between the superposed platesto be bonded at least, one layer of an isotactic propylene polymer modified by reaction, at a temperature higher than the melting point of the propylene polymer, e.g. 180-250‹ C., with a mixture of 0À2-5% of an organic silane compound and 0À1-3% of an organic peroxide based on the weight of the propylene polymer, and pressing the superposed plates at a temperature higher than the melting point of the modified propylene polymer, e.g. at a pressure of 3-100 kg. cm.2 and temperature of 170-240‹ C. The isotactic propylene polymer may be a homopolypropylene or random or block copolymer containing at most 15% by weight of at least one other olefin, e.g. ethylene or butene-1, the balance being propylene. The organic silane compound may have the formula in which R 1 is a hydrogen atom or C 1 -C 4 alkyl radical, R 3 is a C 1 -C 5 alkoxy radical, C 2 -C 5 acyloxy radical, a halogen atom or a group of the formula -O-R 4 -O-R 5 in which R 4 is a C 1 -C 3 alkylene radical and R 5 is a C 1 -C 10 alkyl radical, m is zero or 1 and n is zero or an integer of 1-10. The modified propylene polymer may have a melt flow index of not more than 120 and may be adjusted to the desired value by admixture with non-modified isotactic propylene polymer. The modified propylene isotactic polymer may be used in the form of a powder or film, e.g. of thickness 30-150 Á. The aluminium plates may have a thickness of 0À1-5 mm. and the stainless steel plates a thickness of 0À05-1 mm. The aluminium and stainless steel plates may be degreased prior to bonding. An aluminium plate may have a stainless steel plate bonded to each surface, or two or more aluminium plates and three or more stainless steel plates may be alternately superposed and bonded to each other by the modified propylene polymer.