Patent GB-743904-A (GB)
Title: Casting moulds and compositions for use in the production thereof
IPC: B22C1/02
Filed: 1952-11-17
Abstract: A shell moulding composition comprises (a) 100 parts by weight of a particulate inorganic material fusing above 2,500 DEG  F., (b) 1-15 parts fusible pulverulent thermosetting condensation product, (c) 0.1-20 parts of (1) a complex fluoride of aluminium and one or more alkali or alkaline earth metals or a mixture thereof, or (2) a metal oxide or carbonate, an oxyacid of a metal, a metal salt of said oxyacid or boron oxide or mixture thereof, or (3) a compound as set forth under (2) together with (d) a complex fluoride in which one of the cations is an alkali metal or ammonium and the other cation or cations is or are any metal other than an alkali metal, or (e) an alkali metal or ammonium fluoborate, or (4) a metal or ammonium salt of a phosphoric acid, a phosphometallic acid or a mixture thereof. Examples of the foregoing are (a) sand, silica, zirconite, fly ash, coke breeze alumina, (b) phenol-formaldehyde, urea-formaldehyde, melamine-formaldehyde, alkyd, furfural, or lignin resins; a minor part of the thermosetting resins may be replaced by thermoplastic resins, e.g. vinyl or vinylidene polymers, cellulose derivatives, polyamides, polystyrene, and polyethylene; (c) (1) cryolite, cryolithionite, pachnolite, apatite, zirconium fluoride; (2) alkali or alkaline earth metal oxides and carbonates; (3) ammonium fluoborate; potassium zirconium fluoride; (4) phosphomolybdic and phosphotungstic acids, metaphosphoric acid.  In examples ((1)-(3)) 100 parts foundry sand, 6 parts phenolformaldehyde resin and 5 parts cryolite; the phenol resin may be replaced by urea-aldehyde, melamine-aldehyde or alkyd resins; (4) 80 parts sand, 20 parts zirconite, 5 parts ureaformaldehyde resin, 1 part polystyrene, 6 parts cryolite; ((5)-(7) 100 parts sand, 6 parts phenol-aldehyde resin, 2.5 parts borax, 2 parts litharge or ZnO or molybdic acid; (8) 100 parts and, 1.5 parts melamine-formaldehyde resin, 0.25 parts zinc borate and 0.25 parts litharge; (9) 100 parts sand, 6 parts phenolformaldehyde resin, 6 parts melamine formaldehyde resin, 3 parts boron oxide and 3 parts molybdenum oxide; (10) 80 parts sand, 20 parts zirconite flour, 5 parts urea-formaldehyde resin, 1 part polystyrene and 6 parts Na2CO3; (11) 100 parts sand, 6 parts phenol-formaldehyde resin and 5 parts sodium potassium metaphosphate; (13) 100 parts foundry sand, 6 parts phenol-formaldehyde resin, 6 parts melamine-formaldehyde resin and 6 parts aluminium potassium phosphate; (14) 80 parts sand, 20 parts zirconite flour, 5 parts urea-formaldehyde resin 1 part polystyrene, 3 parts aluminium potassium phosphate and 3 parts dibasic magnesium phosphate; (15) 100 parts sand, 5 parts phenolformaldehyde resin and 6 parts phosphotungstic acid; (16) 100 parts foundry sand, 6 parts phenol-formaldehyde resin, 215 parts boron oxide and 2.5 parts potassium titanium fluoride; (19) 100 parts sand, 1.5 parts melamine-formaldehyde resin, 0.25 parts sodium fluoborate and 1.25 parts zinc oxide.  Small quantities of anti-dusting liquids, e.g. tetraethyl silicate, may be added and also mould release agents, e.g. naphthenic acids, fatty acids or silicones.