Patent GB-699530-A (GB)
Title: Foaming agents and processes for their production from starch or high polymeric starch derivatives
IPC: B03D1/004
Filed: 1951-07-04
Abstract: Foaming agents comprise starchy materials in which some of the hydroxyl groups are substituted by hydrophilic groups and some by hydrophobic groups containing at least 3 carbon atoms, said hydrophilic and hydrophobic groups being ether groups or ester groups and being present in such proportions that upon subjecting a 0.5 per cent aqueous solution of the foaming agent to the foam test of Ross and Miles, the height of the foam produced after 3 minutes at 20 DEG C. is at least 30 mm.  The foaming agents are soluble in water or in water to which a little alkali has been added.  For the introduction of the hydrophilic and hydrophobic groups known methods for the etherification and esterification of starch and similar carbohydrates may be used.  Suitable etherifying or esterifying agents for the introduction of hydrophobic groups are higher alkyl and aralkyl halogenides, e.g. lauryl chloride, benzyl chloride, chlorobenzyl chloride or chloromethyl naphthalene; higher fatty acid chlorides or anhydrides, cyclohexene oxide, benzoyl chloride, p-toluene sulphochloride and higher aliphatic and aromatic isocyanates. Suitable hydrophilia groups are, e.g., ether or ester groups containing carboxylic and sulphonic acid residues.  Hydroxy alkyl groups are also suitable.  Suitable etherifying or esterifying agents with which such groups may be introduced into the starch are halogenated fatty acids, e.g. chloroacetic or chloropropionic acid, glycidic acid, chloroethane sulphonic acid, chloro-oxypropane sulphonic acid, epoxypropane sulphonic acid, polybasic acid anhydrides such as phthalic, succinic or maleic acid anhydrides, chlorosulphonic acid, epoxyethane, epoxy-1.2-propane, epoxy-1.2-propanol 3, ethylene chlorohydrin and glycerol monochlorohydrin.  In the preferred method of preparing the ethers and esters a mixture of starch or a starch derivative with water, an etherifying and/or esterifying agent and an alkaline substance, if desired, after the completion of the reaction is pressed on a roller and heated to a temperature above the gelatinizing temperature of starch.  The dried film is comminuted whereby dry cold swelling starch ethers or esters are obtained.  The starch material used as starting material may be natural starches, high molecular starch derivatives such as modified starches, dextrins and cold swelling starches, and starch containing products such as wheat and rye flour, buckwheat flour and the like.  The products may be used as foaming agents and as addition to detergents.  In the example (a) benzyl chloride and epoxy-1 : 2-propane are added to a hot alkaline paste of potato starch; the mixture is neutralized with acetic acid and the reaction product consisting of mixed ether is precipitated with ethanol and dried; (b) corn or cassava starch is made into a suspension with a solution of potassium iodide and the sodium salt of monochloracetic acid; benzyl chloride is added followed by the addition of caustic soda solution; the excess alkali is neutralized with hydrochloric acid and the mixture dried to give benzyl carboxymethyl starch.  Specification 601,374 is referred to.ALSO:Starch derivatives obtained by replacing some of the hydroxyl groups in a starchy material by hydrophilic groups and some by hydrophobic groups containing at least three carbon atoms, the hydrophilic and hydrophobic groups being ether groups or ester groups, are stated to effect an improvement in the foaming properties of detergents.  The addition of these products, e.g. benzyl carboxy-methyl starch, to concentrated solutions of the sulphuric acid ester salts of higher primary or secondary fatty alcohols, fatty alcohol sulphates, the alkali salts of paraffin sulphonic acids and the like produce thickened solutions which are stable and clear and do not separate.  In an example a detergent is prepared by adding benzyl carboxymethyl starch to a solution of a mixture of sulphuric acid ester salts of secondary alcohols with 10-18 carbon atoms; this detergent may be mixed with the usual constituents of washing agents such as sodium sulphate, soda, sodium phosphate, sodium percarbonate, sodium perborate or the like.ALSO:Starch derivations in which some of the hydroxy groups of a starchy material are replaced by hydrophilic groups and some by hydrophobic groups containing at least three carbon atoms, the hydrophilic and hydrophobic groups being ester or ether groups may be used as auxiliary agents in the foam flotation or ores and other minerals.ALSO:Starchy materials, in which some of the hydroxyl groups are substituted by hydrophilic groups and some by hydrophobic groups containing at least three carbon atoms, the hydrophilic and hydrophobic groups being ether or ester groups, may be used to increase the foaming properties and the stability of the foam of beer or other beverages.  In an example benzyl carboxymethyl starch, prepared by treating corn or cassava starch with monochloracetic acid and benzyl chloride, is added to beer to improve its foaming properties.