GB1430841A - Foundry moulds or cores - Google Patents

Abstract

1430841 Foundry moulds CENTRE TECHNIQUE DES INDUSTRIES DE LA FONDERIE WENDEL - SIDELOR and INDUSTRIES CHIMIQUES DE VOREPPE 16 March 1973 [27 March 1972] 12773/73 Heading C3N A method of manufacturing foundry moulds and cores of increased mechanical resistance comprises mixing a refractory sand, a binding agent for the refractory sand which is either a urea-formaldehyde resin together with a fluidizing agent therefor, a resin containing urea, formaldehyde and furfuryl alcohol in polymerized form optionally with a fluidizing agent therefor, or a mixture of a urea-formaldehyde resin and a precondensate of furfuryl alcohol, optionally with formaldehyde, optionally with a fluidizing agent therefor, a mineral acid or organic acid as setting agent, water and a surface-active agent which produces a foam which substantially completely subsides before the sand begins to set, thereby to prepare a selfhardening liquid sand, moulding the liquid sand and subjecting it to mechanical stresses between the time the sand begins to settle and the time it begins to set, the amount of furfuryl alcohol in polymerized or non-polymerized form not being such as to prevent a foam from forming and wherein the surface-active agent used in an amount 0À01-2% by weight of the liquid sand is chosen from one of the following:- (a) an alkylbenzenesulphonate of Formula (I): in which R 1 , R 2 , R 3 , R 4 each represent an atom of hydrogen or an alkyl group, the alkyl groups having a total of more than 9 carbon atoms and occupying any position on the benzene ring with respect to the sulphonyl group, and Me represents a hydrogen atom, or alkali metal or an HX group, X being an amine, alone or mixed with an alkylbenzene sulphonate of Formula II : in which R<SP>1</SP> 1 and R<SP>1</SP> 2 represents an atom of hydrogen or an alkyl group (C 1-3 ) with the proviso that at least one of R<SP>1</SP> 1 and R<SP>1</SP> 2 is such an alkyl group, and Me is as previously defined: (b) an alkylamine salt of the formula RNH 2 .YH in which R is alkyl (more than C 9 ) and Y is the anionic portion of an acid; (c) a compound of formula in which R represents alkyl (more than C 9 ) and Me is an alkali metal. The fluidizing agent may be furfuryl alcohol or a solvent such as an alcohol or a ketone. Examples of suitable binding agents are: (i) urea-formaldehyde-furfuryl alcohol polycondensates; (ii) mixtures of ureaformaldehyde resin and a furfuryl alcoholformaldehyde precondensate; (iii) resins obtained by the prepolymerization of furfuryl alcohol and a urea-formaldehyde resin; (iv) superpolymerized resins obtained by the further polymerization of prepolymers (iii) above; (v) mixtures of a precondensate of furfuryl alcohol and a urea-formaldehyde resin; and (vi) mixtures of resins (iii) and (iv) either with a urea-formaldehyde resin or with furfuryl alcohol. The fluidizing agent may be furfuryl alcohol, or a solvent such as an alcohol or a ketone. The sulphonic acid may also serve as the setting agent. Setting agents disclosed are sulphuric and phosphoric acids. Numerous examples disclose many compositions which may be used. Specific surface-active agents disclosed are n-dodecylbenzenesulphonic acid optionally with p-toluene sulphonic acid, monolaurylethanolamide - sulphosuccinate, laurylamine acetate, oleylamine acetate and tetra isopropylbenzene sulphonate.