GB770561A - Improvements in or relating to core for foundry purposes and process for producing the same - Google Patents

Abstract

770,561. Core materials. CORN PRODUCTS REFINING CO. Nov. 17, 1954 [April 21, 1954], No. 33273/54. Class 83 (1). A core sand-binder comprises a mixture of 100 parts of a carbohydrate binder and 2-15 parts, dry basis, of an adjunct selected from the group consisting of sulphuric acid, phosphoric acid, and salts and mixtures of salts which produce said acids under heating at a temperature of at least 350‹ F. Carbohydrate binders include cereal binders, and sugars, and any mixtures thereof. Cereal binders include pregelatinized starches, pregelatinized starchy flours, the latter usually containing small amounts of protein or fibre, and dextrins. By sugar is meant those mono- and di-saccharides of an aldose or ketose character, or such non- reducing saccharides which may be hydrolysed, under conditions of use, viz. baking in the presence of water at a temperature of at least 350‹ F., to give aldose or ketose saccharides. Preferred sugars are dextrose, sucrose, and fructose. Others are maltose, lactose, beet or cane molasses and hydrol. The chemical adjuncts are sulphuric and phosphoric acids, and any chemical or mixture of chemicals which will yield these acids under the aforesaid conditions of use, such as ammonium sulphate, ammonium acid sulphate, ammonium persulphate and the alkali metal persulphates, ammonium sulphamate, and pyrophosphoric acid. The make-up is 100 parts of core sand, 0.5-5 parts of carbohydrate binder-adjunct mixture and 1.5-6.0 parts of water, the carbohydrate binder-adjunct mixture comprising 100 parts binder to 2-15 parts of adjunct. Tables are included showing the comparative tensile strengths, green and baked strengths, and volume of gas liberated, for various cores. Specification 515,470 is referred to.