Slip for producing long-lasting mold release layer, useful on mold for casting nonferrous metal under pressure, comprises boron nitride suspension in silanized silica in organic solvent or aqueous colloidal zirconia, alumina or boehmite

摘要

Slip for producing long-lasting mold release layers contains (A) inorganic binder with colloidal inorganic particles based on silicon (Si), zirconium or aluminum oxide or boehmite, where (i) binders based on Si oxide contain silane(s) with hydrolysable groups and substoichiometric amount of water, (ii) others contain water as solvent and form nanocomposite sol, (B) boron nitride suspension in medium and (C) medium of (i) organic solvent or (ii) water. Slip for producing mold release layers with long-term stability contains (A) inorganic binder containing colloidal inorganic particles based on silicon (Si), zirconium (Zr) or aluminum (Al) oxide, boehmite or a mixture with inorganic filler selected from Si, titanium, Zr, Al, yttrium, cerium, tin and iron oxides, AlOOH and carbon, where (i) binder containing colloidal inorganic particles based on Si oxide also contains silane(s) of formula (I) and less than stoichiometric amounts of water with respect to the hydrolysable groups in (I) or (ii) binder free from particles based on Si oxide also contains water as solvent and forms a nanocomposite sol under sol-gel process conditions, (B) a suspension of boron nitride (BN) particles in (i) an organic solvent or (ii) water and (C) (i) an organic solvent or (ii) water: R x-Si-A 4-x(I); A : hydrolysable groups selected from hydrogen, halogens, hydroxyl and (un)substituted 2-20 C alkoxy, 6-22 C aryloxy, alkylaryloxy, acyloxy and alkylcarbonyl groups; R : unhydrolysable groups selected from 1-20 C alkyl, 2-20 C alkenyl, 2-20 C alkynyl, 6-22 C aryl, alkaryl and arylalkyl groups; x : 0, 1, 2, 3 such that x is 1 or more in not less than 50% of the silanes . Independent claims are also included for the following: (1) production of the slip; (2) mold release layers with long-term stability produced from the slip as 0.5-250 mu m thick hardened layer; (3) production of the release layers.