Patent GB-853940-A (GB)
Title: Phenolic resin and moulding composition
Inventor: LESS FRANK W
IPC: B22C1/22
Filed: 1956-12-17
Abstract: A thermosetting phenolic resin composition comprises (a) a solid acid-catalysed reaction product of 0,5-0,8 mols of formaldehyde and 1 mol of phenol, (b) 4-20% by weight of (a) of hexamethylene tetramine, and (c) 0,5-20% by weight of (a) of an aromatic monocarboxylic acid which is benzilic acid or an acid of the formula: R-Ar-X-COOH where X is a direct link, an alkylene or an alkylenylene radical containing at most 5 carbon atoms in the chain, Ar is a benzene or a naphthylene residue, and R is H, OH or methyl, or, when Ar is a benzene residue, may also be ethyl or propyl, or represents two alkyl or hydroxyl radicals.  Acids specified which fall within the formula are:benzoic, salicylic, p-hydroxy benzoic, o-, m- or p-toluic, a -or b -naphthoic, which may be substituted with a methyl or hydroxyl group, phenyl-acetic,- propionic or -valeric, cinnamic, hydrocinnamic, o-, m- or p-methyl phenyl acetic, o-, m- or p-hydroxy phenyl acetic and naphthyl-and methyl-naphthyl-acetic.  The only acid catalyst specified for (a) is sulphuric acid.  The aromatic acid (c) may be added to the phenol before it is reacted with formaldehyde, or it may be added to the molten resin, or it may be mixed with the other components in solid or molten form.  A minor proportion by weight of such a phenolic resin composition may be mixed with, or used to coat, a major proportion of inert particles, eg.. Al2O3 or SiC to make grinding wheels, sand to make foundry shell moulds or wood sawdust to make woodwaste boards.  In the case of coating, coating agents may be used, e.g. a mixture of ethyl alcohol and water, or an organic ester of phthalic, maleic, sebacic or adipic acids, e.g. dibutyl phthalate. Other additives specified are calcium stearate, carnauba or montan wax, and anhydrous magnesium silicate. Specification 842,632 is referred to.ALSO:A major proportion by weight of inert particles (e.g. sand for foundry moulds, and Al2O3 or SiC for grinding wheels) may be coated with a minor proportion of a thermosetting phenolic resin composition comprising (a) a solid acid-catalysed reaction product of 0.5-0.8 mols of formaldehyde and 1 mol of phenol, (b) 4-20% by weight of (a) of hexamethylene tetramine, and (c) 0.5-20% by weight of (a) of an aromatic monocarboxylic acid which is benzilic or an acid of the formula: R-Ar-X-COOH where X is a direct link, an alkylene or an alkyterylene radical containing at most 5 carbon atoms in the chain, Ar is a benzene or a naphthylene residue and R is H, OH or methyl, or, when Ar is a benzene residue, may also be ethyl or propyl, or represents two alkyl or hydroxyl radicals.  Acids specified which fall in this the formula are:-benzoic, salicylic, p-hydroxy benzoic, o-, m- or p-toluic, a - or b -naphthoic which may be substituted with a methyl or hydroxyl group, phenylacetic, -propionic or -valenic, cinnamic, hydrocinnamic, o-, m- or p-methyl phenyl acetic, o-, m- or p-hydroxyphenyl acetic, and naphthyl- and methylnaphthyl-acetic.  Coating agents may be used, e.g. a mixture of ethyl alcohol and water, or an organic ester of phthalic, maleic, sebaccic or adipic acids, e.g. dibutylphthalate.  Other additives specified are calcium stearate, carnauba or montan wax, and anhydrous magnesium silicate.  Specification 843,632 is referred to.