Patented Aug. 1941 2,253,457

UNITED ‘STATES. PATENT OFFICE 2,253,457 IMPROVING THE DYEIING OF TEXTILES Croyden Meredith Whittaker, Cheadle Hulme, Clifford Collier Wilcock, Salford, and Charles Percival. Tattersileld, Audenshaw, near Man chester, England, assignors to Courtaulds Lim ited, London, England, a British company No Drawing. Application June 6, 1939, Serial No. 277,732. In Great Britain June 13, 1938 6 Claims. invention relates to the treatment of order according to whether the compound of textile materials and is particularly concerned cyanamide and formaldehyde is ‘with improvements in and relating to the dyeing 1. Dissolved in dilute sulphuric acid. > of such materials. 2. Dissolved in dilute formic acid. It has already been proposed in the speci?ca 3. Dissolved'in dilute acetic acid or tion of British Patent No. 506,793 to obtain good 4. Dissolved in dilute acetic acid and then th results in respect of dyeing and fastness to wash solution neutralised with ammonia. > ing by incorporating in such materials a product The treatment may comprise soaking the ma obtained by causing cyanamide and formalde terial in the said solution either hot or cold and hyde to react under acid or neutral conditions. may be applied to the material either before or The process according to the present invention after dyeing. We have found that if the treat comprises treating the material with a solution ment is applied before dyeing, the'exhaustion of made by dissolving in acid the product which is the dyebath, which is subsequently obtained in formed by the interaction of cyanamide and the case of the soluble vat dyes known com formaldehyde. ' _ mercially as the Soledon and Indigosal dyes, and The cyanamide and formaldehyde react either of azoic, sulphur, basic and direct cotton dyes, directly or in solution. A convenient method of including direct cotton dyes subsequently diazo obtaining the reaction product comprises mixing tised and developed, is more complete than when their aqueous solutions preferably in approxi dyeing without the pretreatment; in other words mately equimolecular proportions and then ad 20 the ai?nity of the material for these dyes is justing the pH value of the solution to a value increased. Moreover, the treatment imparts to of 6 01' greater, preferably between 6 and 9. The the material an ai?nity for acid dyes, which higher the pH value, that is the more alkaline the previously it did not possess. Both-the above solution, the more rapidly is the reaction product effects are obtained to different extents with precipitated. The rate of precipitation can also 25 different dyestuffs. If the treatment is applied be accelerated by increasing the temperature, either before or after dyeing, we ha "i found and we have found a temperature of 70° centi-> that the fastness to cross-dyeing, colo wafer grade to be satisfactory although temperatures steeping, perspiration, desizing compounm and up to boiling point may be used. The precipitated washing is improved. product which is then separated by ?ltration, 30' In addition to the obvious advantage of em no '1 I washed and dried, is soluble in acids. Its solu my due to the improved exhaustion of the dye bility is affected by its manner of production. bath, the invention may be utilized by the com For example the more alkaline the solution from bination of treated and'untreated material in ’ which it is precipitated the lower is the solubility same fabric to obtain double-tone dyeing using of the product in acetic acid, On the other hand a single dyebath. Similarly by applying varying a higher reaction temperature tends to give a ‘ strengths of the acid solution to the ?bre and product more readily soluble in acetic acid. then combining vthe treated materials in one Again if it'has been dried at a high temperature fabric, multitone dyeing can be obtained. such as from 150'’ to 160° centigrade, boiling with If, when carrying out the process of the present a strong mineral acid, for example sulphuric or 40 invention, any tendency for a reduction in the hydrochloric acid, may be required to obtain dis fastness of the dyestuff to light is found, im solution, but if it has been dried at a lower tem provements are obtained by adding to the treat perature, as for example at 100° centigrade or be ing solution a small proportion of copper acetate (other than basic copper acetate) or those sub low, it may be dissolved on heating with a weak is stances such as copper carbonate and acetic acid acid such as formic or acetic acid. _ which will produce copper acetate in situ. The Naturally, in view of the deleterious action of amount of’ copper acetate which should be added mineral acids on some textiles, for example cellu varies with the dyestuif and the amount of dye losic materials, it is preferred to use the solutions stu? on the material, but about 2 per cent calcu in the weaker organic acids. As hereinafter ex 50 lated on the weight of the material has been plained material treated according to this inven found satisfactory, ' ‘ tion has generally a greater affinity for dyestuffs. The materials, to which the process of this in This increase in amnity varies according to the vention can be applied include those of silk and method of preparing the solution used for the casein,‘ and cellulose materials such as cotton, treatment. Thus, the increase is in ascending linen and rayon obtainable ~ from viscose or 2 2,958,467 cuprammonium cellulose, or by, de-esterifying» _ hours the precipitate is ?ltered off, washed with cellulose esters such as cellulose acetate, water and dried at 70° centigrade. 3 parts of The cyanamide can conveniently be obtained the product so obtained are dissolved by boiling from crude calcium cyanamide by extraction in 12 parts of 25 per cent acetic acid solution with water and, after ?ltration, neutralising the 5 and the solution diluted with water to 2,000 resulting solution with sulphuric or hydrochloric parts. A fabric made from regenerated cellulose acid.’ staple ?bre sold under the registered trade-mark The following examples will further illustrate “Flbro” is dyed with "Chlorazul Fast Black BKS” how the said invention may be carried out in (Imperial Chemical Industries Limited), and is practice, although the invention is not limited to 10 then treated with the above solution for 20 min these examples. In all the examples the parts utes at 40° centigrade, the liquor to fabric ratio are by weight. being 20 to 1. After washing and drying it is Example 1 found that the dye in the treated material is considerably faster to wet processing than that 12 parts of crude calcium cyanamide are ex in the untreated material. tracted with 60 parts of water at from 35° to 45° Example 4 centigrade for 30 minutes and then ?ltered and A piece of fabric made from regenerated cel the solution neutralised with strong sulphuric lulose staple ?bre is dyed in a dyebath contain acid. The calcium sulphate thus precipitated is ing 1.5 per cent on the weight of the fabric of ?ltered off and to the ?ltrate 5 parts of com 20 the dyestu? marketed under the name “Viscose mercial formaldehyde solution containing 40 per Blue Grey NB” (Kuhlmann, France). The 're cent of formaldehyde are added. The solution sulting dyed material is treated for 20 minutes is made slightly alkaline with caustic soda. and at room temperature in a dilute acetic acid bath the product which precipitates out is ?ltered off, containing 3 per cent calculated on the weight of washed with water and dried at 100° centigrade. 25 the fabric of the product precipitated from an One part of the product thus obtained is dis alkaline cyanamide formaldehyde solution as de solved by boiling in 4 parts of 25 per cent acetic scribed in Example 1, and in addition 2 per cent acid solution and made up to a stock solution calculated on the weight of the material of nor containing 1 per cent of the product. 100 parts mal copper acetate. The liquor to fabric ratio of of a piece of fabric made from regenerated cel 30 the after-treating bath is 40 to 1. The fabric lulose staple ?bre are treated with 500 parts of thus treated shows greater fastness to light than the above stock solution to which have already similarly dyed material treated with an acid solu been added 1,500 par-ts of water. The treatment tion of the product not containing copperacetata. is continued for 15 minutes at a temperature of What we claim is: 60° centigrade. The treated fabric is then dyed 35 l. A process for improving the dyeing proper in a bath containing 2 parts of Indigosol blue ties of textile materials which comprises treat I. B. C. (Durand I-Iuegenin 8: Co.) and 40 parts ing the material with a solution obtained by of sodium chloride dissolved in 4,000 parts of dissolving in acid the condensation product which water. The exhaustion of the dyebath obtained is produced by the interaction of an alkaline is substantially greater than when dyeing un 40 solution of cyanamide and formaldehyde at a treated material under otherwise identical con temperature within the range of 70° C. to 100° C. ditions. 2. Process for improving the dyeing properties Example 2 of textile materials which comprises treating the material with a solution obtained by dissolv 100 parts of a piece of fabric made from re . ing in acetic acid the condensation product which generated cellulose staple ?bre and dyed with is produced by the interaction of cyanamide and the dyestuff marketed under the name “Solar formaldehyde in an aqueous solution having a Rubinole B” ($andoz Chemical Works) are treat pH value ranging between six and nine at a ed with a solution obtained by diluting 200 parts temperature ranging between 70° C. and 100° C'. of the stock solution described in Example 1, 50 3. Process for improving the dyeing properties with 1,800 parts of water. The treatment is con of textile materials which comprises treating the tinued for 20 minutes at 40° centigrade, and after material with a hydrochloric acid solution of the washing and drying, the dye in the treated mate condensation product which is produced by the rial is considerably faster to wet processing than interaction of equimolecular proportions in alka that in the untreated material. line solution and at a temperature within the Example 3 range of 70° C. to 100° C. of cyanamide and Calcium cyanamide is vigorously agitated with formaldehyde. six times its weight of water at 50° centigrade 4. Process for improving the dyeing properties for 30 minutes. The slurry obtained is ?ltered of textile materials which comprises mixing aque and the ?ltrate rapidly cooled to below 20° centi ous solutions of cyanamide and formaldehyde grade. The residue on the ?lter is washed with in approximately equimolecular proportions, the minimum of water-not more than say 5 per then adjusting the pH value of the mixture to cent of the total volume of ?ltrate. Hydro a value between 6 and 9 and the temperature chloric acid is added to the ?ltrate until the to between 70° C. and 100° centigrade thereby solution is only faintly alkaline and the tempera ' precipitating the reaction product, separating the ture is then rapidly raised to 70° centigrade. precipitated condensation product from the liq The cyanamide content of the solution having uid, drying said condensation product at a tem been determined by analysis, slightly more than perature lower than the reaction temperature the molecular equivalent of formaldehyde is now 70 dissolving the condensation product in a weaker added in the form of a 40 per cent solution. The organic acid at a boiling temperature thereby resulting solution is maintained faintly alkaline forming a treating solution, and treating the by the addition of caustic soda solution and at textile material with said treating solution at about 70° centigrade, whereupon an insoluble a lower temperature. product is precipitated. After standing for 2 76 5. Textile materials the dyeing properties of _ 2,253,457 3 which have been improved according to the proc- lution oi‘ cyanamide and formaldehyde at a tem ess claimed in claim 1. perature between 70° C. and 100° C.’and adding ' 6. Process for improving the dyeing properties a small proportion 01' copper acetate to the treat of textile materials which comprises treating the ing solution. material after dyeing with a solution obtained by c CROYDEN MEREDITH WHI'I'I‘AKER. dissolving in acid the condensation product which CLIFFORD COILIER WILCOCK, is produced by the interaction of an alkaline so- , CHARLES PERCIVAL TA'I'I‘ERSFIEID.