Patent GB-388563-A (GB)
Title: Manufacture of colour lakes
IPC: C09B69/06
Filed: 1932-02-13
Abstract: Colour lakes are manufactured by treating basic dyes with or without acid groups, acid dyes containing amino or substituted amino groups, or compounds containing these groups which are not basic dyestuffs with a complex acid of selenium or a salt thereof or with substances capable of forming such acid or salt.  The complex acid preferably comprises selenious acid and one or more acids derived from molybdenum, tungsten, arsenic, antimony, phosphorus or silicon, examples being seleno- (or selenoso) - molybdic acid, seleno - molybdo - tungstic acid and seleno-tungstic acid.  The complex acids or their alkali salts may be prepared by dissolving the alkali salts or acids of their respective components in hot water and acidifying with excess of a mineral acid, e.g. hydrochloric or sulphuric acid, and boiling if necessary.  The salt may then be isolated by neutralizing with, for example, sodium carbonate or hydroxide.  A further series of acids which may be used for preparing colour lakes may be obtained by reduction of the normal acids, e.g. by means of sulphur dioxide, sodium hydrosulphite, zinc, tin or organic reducing agents in the presence of acid.  Dispersing agents, e.g. turkey red oils, soaps, resins or glue may be added during or subsequent to the lake formation.  The lakes may also be formed in the presence of salts, e.g. aluminium sulphate or zinc chloride, in order to maintain a particular degree of acidity, and the precipitation may be carried out in the presence of substrata, e.g. barium sulphate or aluminium hydroxide.  In order to enhance the fastness of the lakes they may be prepared under pressure or heated under pressure subsequent to their formation either suspended in water as precipitated or in paste form after filtration, with or without further addition of complex acids or their components or of mineral acids, organic acids or salts, e.g. molybdates, tungstates or aluminium sulphate.  In examples: (1) hydrochloric acid is added to a boiling solution of sodium tungstate and sodium selenite, and the paste of sodium seleno-tungstate obtained is added to an aqueous solution of a dyestuff to which hydrochloric acid or alum has been added; the filtered product is heated under pressure; (2) Brilliant Green Y.S. dissolved in boiling water is precipitated by means of the paste obtained by acidifying with hydrochloric acid a boiling solution of sodium selenite, disodium hydrogen phosphate and sodium tungstate, rendering slightly alkaline with sodium carbonate and filtering; the product is heated under pressure, yielding a bright green lake; (3) a boiling solution of Rhodamine B is precipitated by means of the solution obtained by adding hydrochloric acid to a solution of sodium selenite, sodium molybdate and sodium tungstate; the filtered and washed product is heated under pressure, yielding a clear red lake; (4) Rhodamine 6 G is precipitated from a boiling aqueous solution containing hydrochloric acid by means of a hot solution of sodium selenite and sodium tungstate; the product is heated under pressure to produce a magenta lake; (5) hydrochloric acid is added to a boiling solution of sodium tungstate and sodium selenite and the product is reduced by means of sodium hydrosulphite; the paste obtained is added to a boiling solution of Brilliant Green Y.S.; the filtered and washed precipitate is heated under pressure. Samples have been furnished of lakes obtained according to the following examples: (6) Brilliant Green Y.S. dissolved in boiling water is precipitated by means of the product obtained by acidifying with hydrochloric acid a boiling solution of sodium tungstate, sodium selenite and sodium arsenate; (7) Ethyl Violet is precipitated from a boiling aqueous solution containing turkey red oil by means of the product obtained by adding hydrochloric acid to a boiling solution of sodium tungstate, sodium selenite and potassium metantimonate, to yield a blueish violet lake; (8) a boiling solution of Rhodamine B is precipitated by means of the product obtained by adding hydrochloric acid to a boiling solution of sodium tungstate and sodium selenite and then adding a solution of sodium silicate; a deep red lake is obtained; the products of (6), (7) and (8) may be heated under pressure; (9) Victoria Pure Blue BOS in boiling aqueous solution containing hydrochloric acid is precipitated by means of the product obtained by acidifying with hydrochloric acid a boiling solution of sodium tungstate and sodium selenite; the product is heated under pressure.ALSO:Complex acids containing selenium, and alkali metal salts thereof, are manufactured by dissolving the alkali salts or acids of their respective components in hot water and acidifying with excess of a mineral acid, e.g. hydrochloric or sulphuric acid, and boiling if necessary.  The salt may then be isolated by neutralizing with, for example, sodium carbonate or hydroxide. The complex acids preferably comprise selenoius acid and one or more acids derived from molybdenum, tungsten, arsenic, antimony, phosphorus, or silicon.  A further series of acids may be obtained by reduction of the normal acids, e.g. by means of sulphur dioxide, sodium hydrosulphite, zinc, tin, or organic reducing agents in the presence of acid.