United States Patent Office Patented Mar
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3,124,411 United States Patent Office Patented Mar. 10, 1964 2 The amount of sodium hydroxide required in the re 3,124,411 ducing bath varies with the class of vat dye used and can METHOD FOR DYENG TEXTELEMATERALS be determined from the booklets published by the dye WITH WAT DYES manufacturer. Each dye works best at a certain sodi Gilbert S. Pansoa and Carol E. Weill, Livingston, N.J., um hydroxide level. Sufficient sodium hydroxide in ex assignors to Metal Hydrides Incorporated, Beverly, cess of the amount required to convert the dye to its Mass., a corporation of Massachusetts alkali leuco form must be present to stabilize the bath. No Drawing. Fied July 17, 1961, Ser. No. 124,373 In some instances in commercial operation it is desira 6 Claims. (C. 8-34) ble to dry the impregnated fabric before immersion in This invention relates to dyeing textile materials with 0. the reducing bath. Cloth impregnated with vat dye and vat dyes. sodium bisulfite in accordance with the invention can be Textile materials, such as cotton fabrics, usually are dried at 110 C. for 1 to 2 hours and then immersed dyed by padding a vat dye on to the fabric, squeezing in the reducing bath and obtain the desired shade. This out the excess, and then passing the dye impregnated indicates the great stability of the mixture of bisulfite fabric through an aqueous bath containing sodium hy and vat dye. droxide, sodium hydrosulfite and sodium chloride. The Reduction of the dye to the sodium leuco and ex reducing liquor reduces the dye and converts it to the haustion of the dye in to the fabric is dependent upon the water soluble sodium leuco form, the presence of the salt temperature of the bath and the time of contact. At shifting the equilibrium of the reduced dye from the solu high temperatures, such as 80° C. and higher, the con tion to the fabric. The cloth then is removed from the 20 tact time is less than 10 seconds which makes the inven bath and the dye oxidized to give a level dyeing of de tion particularly useful for continuous dyeing, such as sired shade. This procedure requires the use of as much in the Williams unit. At lower temperatures, longer con as 5 to 40 fold excess of hydrosulfite over the stoichio tact times are needed to insure full reduction and pene metric requirement since the hydrosulfite is very unstable tration of the dye. The latter conditions are more useful under the conditions of air oxidation present in dyeing 25 in the Beck dyeing operations or package dyeing opera and the high temperatures used in the dyeing operation. tions where longer contact times are needed. It has been proposed heretofore that an alkali metal The mixture of alkali metal bisulfite and vat dye used bisulfite, such as sodium bisulfite, can be converted to in the practice of the invention is completely stable and alkali metal hydrosulfite in an aqueous medium by the can be stored for long periods of time. The aqueous so addition of an alkali metal borohydride, such as sodium. 30 lution of alkali metal hydroxide and alkali metal boro or potassium borohydride. Thereafter, an alkali metal hydride is available in concentrations which also are ex hydroxide may be added and the resulting alkaline solu tremely stable even at high temperatures for long periods tion may be used for reducing vat dyes and for dyeing of time. When the fabric impregnated with the mix textile fabrics by immersing the textile fabric in the al ture of alkali metal bisulfite and vat dye is passed into kaline hydrosulfite solution. This procedure does not 35 the reducing solution, the vat dye is reduced and con solve the instability problem of the hydrosulfite and re verted to its water soluble alkali leuco form in a vey quires the substantial absence of alkaline metal hydroxide few seconds. Consequently, the residence time required during the reaction between the alkali metal bisulfite and in the reducing bath is very short and there is very little alkali metal borohydride. opportunity for the side reaction of air oxidation to oc The present invention is based upon the discovery that 40 cur. This is of particular industrial significance because if a textile fabric is impregnated with a mixture of a it makes possible vatting operations with substantially less vat dye and an alkali metal bisulfite and the thus im reducing agent than has heretofore been required. pregnated fabric is passed through a reducing liquor con While we have described the use of the alkali metal sisting of an aqueous solution of an alkali metal hy borohydrides in the practice of the invention, the quater droxide and an alkali metal borohydride having a pH 45 nary ammonium borohydrides may be used in place between about 9.5 and 13, the vat dye is reduced and thereof if desired. As illustrative of water soluble qua converted to its water soluble alkali leuco form. Thus, ternary ammonium borohydrides we may mention the in accordance with the method of the present invention, lower tetraalkyl ammonium borohydrides, such as tetra a mixture of a vat dye and an alkali metal bisulfite, such ethyl, tetraethyl, trimethyl ethyl, dimethyl diethylam as sodium bisulfite, in the form of an aqueous dispersion 50 monium borohydrides, as well as quaternary ammonium is padded on to the textile fabric, the excess being borohydrides responding to the formula R(CH),NBH squeezed out. The thus impregnated fabric then is passed where R is a saturated or unsaturated straight chain through an aqueous reducing solution consisting essen aliphatic hydrocarbon radical containing about 7 to 21 tially of an alkali metal hydroxide, such as sodium hy carbon atoms, x and y are integers from 1 to 3, and x droxide, an alkali metal borohydride, such as sodium or 55 plus y equals 4, such as tricapryl methyl ammonium potassium borohydride, and a salt, such as sodium chlo borohydride, cetyl trimethyl ammonium borohydride, etc. ride. The fabric then is removed from the reducing We have successfully used in the practice of the inven solution and subjected to an oxidizing operation. tion many vat dyes selected from the various types com Since the composition of the various vat dyes varies, the monly used in commercial practice. As illustrative of amounts of alkali metal bisulfite and alkali metal boro 60 such vat dyes we may mention anthraquinone type dyes, hydride required in the practice of the invention will such as Mayvat Jade Green (C.I. #59,105), Carbanthrene vary. In general, about 4 to 400 parts by weight of Blue BCS (C.I. #69,825), Ponsul Brilliant Violet 4RN alkali metal bisulfite and about 0.2 to 20 parts by weight (C.I. #60,010), Ponsul Golden Orange 3G (C.I. of alkali metal borohydride per 100 parts by weight of #69,025), Indanthrene Golden Yellow RK (Vat. Orange vat dye may be used. The use of greater amounts of 65 1, C.I. #59,105/6), Indanthrene. Brilliant Orange RK bisulfite and borohydride are not harmful. It will be (Vat. Orange 3, C.I. #59,300), Amanthrene Golden understood that in a continuous dyeing operation, the Orange F (Vat. Orange 9, C.I. #59,700), Indanthrene concentration of alkali metal hydroxide, alkali metal Orange RRT (Vat. Orange 1, C.I. ii. 59,705), and In borohydride, and salt in the reducing bath must be main danthrene Dark Blue BO (Vat. Blue 20, C.I. #59,800), tained sufficiently high and, preferably, substantially con 70 Tinon Navy Blue RAF (Vat. Blue 18, C.E. #59,815), stant to effect the desired reduction and obtain level dye Ahcovat Jade Green B (Vat. Green 1, C.I. #59,825), 1ng. Indanthrene Brilliant Violet 3B (Vat. Violet 9, C.I. 3,124,411 3. 4. #60,005), Cibanone Violet 4R (Vat. Violet 1, C.I. The pH indicated is that at the temperature shown in the iF60,010); anthraquinone type dyes containing amino table before immersing the impregnated cloth. groups, such as Cibanone Black DRB (Vat. Black 9, C.I. it 65,230); dyes containing a heterocyclic nucleus Table II fixed to a central vatting system, such as Indanthrene Red 5 This table illustrates the effect of the ratio of dye to FBB (Vat. Red 10, C.I. # 67,000), Tinon Yellow GC sodium bisulfite, the dye used being Vat Green 1 (C.I. (Vat. Yellow 2, C.I. iF67,300), Carbanthrene Red BN #73,360). (Vat. Red 35, C.I. it 68,000), Cibanone Violet BNA (Vat Violet 13, C.I. it 68,700), Indanthrene Brown RN (Vat Dye in NaHSO3 Ratio of Brown 3, C.I. #69,015), Indanthrene Red Brown 5 RF 10 Example grains in grams dye to pH. Comment (Vat. Brown 25, C.I. #69,020), Tinon Olive BF (Vat NaISO3 Green 3, C.I. #69,500), Tinon Olive SF (Vat. Black 25, 0.5 30.0 1.3 Reduction C.I. it 69,525), Cibanone Blue GCDN (Vat. Blue 14, C.I. incoIl - pletc. #68,810), Ponsul Blue BF (Vat Blue 6, C.I. it 69,825), 1.0 20.0 li. 3 Reduced. Indanthrene Khaki GG (Vat. Green 8, C.I. ii. 71,050); 1.0 10.0 1.3 Do. indigo and its derivatives and homologues, such as 8.3 1.8 1.3 Do. Cibanone Blue 2BGD (Vat. Blue 5, C.I. #73,065); thio 8.3 0.48 11.3 Do. indigo and its derivatives and homologues, such as 12.0 0.33 1.3 Do.