Polyurethane resin propellant rod support - loaded with fillers and rein-forced for greater heat stability

摘要

Parent patent described mfr. of a flare or projectile incorporating an array of rod shaped propellant individually anchored by one end in a block made of polyurethane resin. Addn. involves addn. of 5-50% by wt. of a mineral or thermally stable org. filler to the polyurethane for the block. Pref. mineral filler particles are 30, pref. 10-20 mu across of ferric oxide and/or silica, pref. at 10-30 %. Pref. organic filler is trichlorethyl phosphate. Pref. a metallic plast is stuck behind the block to reinforce it. Pref. the propellant rods are pretreated with an anhydrous solvent comprising a 1-3C nitroalkane or ketones of mol. wt. 300 pref. nitromethane or MEK to increase the stiffness and the heat stability of the block and reduces the post moulding shringage. Pretreatment with solvent enhances subsequent bond between the propellant rods and the block, is cheaper than prior use of an epoxy resin primer.