Patent GB-435767-A (GB)
Title: Manufacture of colour lakes
IPC: C09B69/04
Filed: 1934-03-27
Abstract: Colour lakes are prepared by interaction of soluble acid dyestuffs with urea-formaldehyde condensation products, which latter are subjected to a heat-treatment at 70--160 DEG  C. conducted at least in part in the absence of water.  The dyestuffs may be of the azo, triphenylmethane, azine or anthraquinone series containing such acid substituent as sulphonic and carboxylic groups.  The condensation products may be prepared not only from urea but also from thiourea, dicyandiamide, biuret, guanidine, cyanuric acid, phenyl urea, or mixtures thereof, or the products resulting from the heat treatment of urea at 160 DEG  C. for 12--48 hours.  In the preparation of the lakes, which is conducted as usual in an aqueous solution or suspension, the customary lake-forming materials such as aluminium hydroxide, green earth, tannic acid, colophony, tartar emetic, barium and calcium sulphates, zinc oxide, zinc sulphite or titanium oxide may also be present.  According to the examples: (1) urea is dissolved in aqueous formaldehyde in the presence of active carbon, the solution heated and thiourea added; an aqueous solution of Cloth fast violet R together with hydrochloric acid is then stirred in, whereupon the lake separates out and after washing is dried overnight at a temperature of 80 DEG  C.; other dyestuffs which may be added are Alizarine cyanine green E, Malachite green, Kiton pure blue Y, Safranine and Crysoidine Y, in some cases with the further addition of tannin, tartar emetic or clay; (2) heat-treated urea is added to aqueous formaldehyde in the presence of active carbon and the solution concentrated to a syrup to which Neolan blue 2G or Eosine Y and hydrochloric acid are added; the precipitate is dried overnight at 80 DEG  C.; (3) the condensation product of (1) is evaporated to dryness, ground, and suspended in water; on adding the suspension to an aqueous solution of Cloth fast orange R, Malachite green or Scarlet 2R, together with a solution of sodium sulphate, tannin and tartar emetic, or aluminium sulphate, sodium chloride and barium chloride respectively, the lake precipitates leaving an exhausted solution; in the case of Malachite green, some of the condensation product of (2) may be present; (4) Neolan bordeaux R or Cloth fast orange R is dissolved in an aqueous alcoholic solution of the condensation product of (1) and the whole baked for 4 hours at 130 DEG  C. to give a foamy hard mass; (5) Scarlet 2R is dissolved in the urea-formaldehyde condensation product of (2) and the solution baked; (6) Kiton fast yellow 3G is added to an aqueous solution of dimethylolurea, or of mixed dimethylolurea and dimethylolthiourea, or of a dicyandiamide - formaldehyde condensation product and the solution heated at 130 DEG  C. for 4 hours to give a solid lake; (7) cyanuric acid is heated with aqueous formaldehyde, Alizarine sapphire blue 3G added, and the solution heated to dryness at 130 DEG  C. for 4 hours; (8) Methyl violet 4B is dissolved in the aqueous condensation product of (1) together with tannin and tartar emetic and the mixture heated to 130 DEG  C. for 4 hours; (9) a suspension of the condensation product of (3) is added to an aqueous solution of Rhodamine B, tannin and tartar emetic, and the precipitate washed and dried.  The products are useful as colouring matters for oil colours, varnishes and linoleum and for making printing colours for printing paper or floor coverings.  The Specification as open to inspection under Sect. 91 refers also to thiazine, oxazine and acridine dyestuffs and to dyestuffs containing phenolic groups.  This subject-matter does not appear in the Specification as accepted.