GB2201165A

GB2201165A - Leuco sulphur dye compositions with reduced content of inorganic sulphide

Info

Publication number: GB2201165A
Application number: GB08803293A
Authority: GB
Inventors: Manuel Jose Domingo; Laszlo A Meszaros
Original assignee: Sandoz AG
Current assignee: Sandoz AG
Priority date: 1987-02-16
Filing date: 1988-02-12
Publication date: 1988-08-24
Anticipated expiration: 2008-02-12
Also published as: FR2610942B1; FR2610942A1; BR8800624A; GB8803293D0; GB2201165B; HK102694A; JPS63258956A; KR880010077A; CN1017623B; IT8847630A0; JP2743322B2; CH679724B5; CN88100593A; CH679724GA3; IT1219446B; DE3804700C2; DE3804700A1; KR940002561B1; RU2042689C1

Description

-I- 4 2 2- 0 1165- IMPROVEMENTS IN OR RELATING TO ORGANIC COMPOUNDS The

present invention relates to liquid compositions of sulphur dyes reduced in leuco form.

The production of prereduced (leuco form) sulphur dyes com- prises a plurality of Steps and invariably at least one of these steps results in the presence of one or more salts in the product. For instance, sulphuric acid and hydrochloric acid are frequently used in condensation reactions for producing indophenol intermediates and also in the step whereby various sulphur dyes are precipitated from a solution following the thionation (sulphurization) reaction. Such acids may produce salts by reacting with sodium sulphide and/or sodium hydroxide which are widely used in sulphur dye production. Salts such as sodium sulphide, copper sulphate and sodium chlorideare often used during the thionation step which is an essential part of sulphur dye manufacture and salt may also be used to aid in the precipitation of the dye from a solution. Furthermore, in the production of leuco sulphur dyes, sodium sulphide is frequently used as reducing agent. Other salts either introduced or produced at one stage or another in the production of prereduced sulphur dyes include sodium thiosulphate, sodium nitrite and.sodium thiocyanate.

W C 150-5164 It has now been found that liquid compositions of prereduced sulphur dyes having a reduced amount of inorganic sulphides and preferably also a low amount of all inorganic salts which usually result from the manufacture of prereduced sulphur dyes, can be 5 obtained.

Accordingly, there is provided a liquid dye composition comprising at least one sulphur dye reduced in leuco form and a reducing agent for said dye which is selected from a sulphide formed in situ or stemming from thionation, and a reducing sugar, the composition having a total inorganic sulphide content of < 3% by weight based on the total weight of the composition.

The sulphide content of the liquid dye composition as indicated above is preferably as can be determined by known analytical techniques, e.g. by an iodometric method using sodium thiosulphate and refers to the total amount of sodium sulphide and sodium hydrogen sulphide present. According to a preferred method, the sodium sulphide and sodium hydrogen sulphide are first separated from the dye liquid with acetic acid using conventional methods, e.g. a stream of carbone dioxide, and then treated using a 0,1 N iodine solution and a 0,1 N sodium thiosulphate solution. There are other titration methods for determining the sulphide content; however, it should be acknowledged that some methodsthnd to interfere with the sulphur dye, e.g. the potentiometric titration with 0,2 N cupric ammonium sulphate solution which may give a sulphide content of up to 13%.

Preferably, the liquid sulphur dye compositions of the invention have an inorganic sulphide content that does not exceed 2.5% and is more preferably within the range 1 to 2.5%, particularly 1.5 to 2.5% based on the total we ight of the liquid dye composition. Based on the weight of prereduced sulphur dye, the inorganic sulphide content is usually in the range 0 to 18.5%, particularly 1 to 14%. By sulphur dye, there is meant a known water-soluble or water- insoluble sulphur dye, a sulphur vat dye or a mixture of these dyes.

i 11 -1 150-5164 Preferably, the liquid dye composition of the invention contains an alkali and, as reducing agent, pieferably a reducing sugar.

The present invention further provides a process for the production of such liquid sulphur dye compositions. The process of the invention comprises reducing a sulphur dye in an aqueous alkaline medium containing,, as reducing agent for the sulphur dye, a reducing sugar and/or a sulphide which is formed in situ or stems from thionation.

The alkali used to produce the alkaline medium is usually an alkali metal hydroxide, carbonate or phosphate (e.g. tetrasodium pyrophosphate, trisodium phosphate or disodium phosphate), preferably potassium hydroxide or sodium hydroxide, most preferably the latter. The amount of alkali should be sufficient to maintain an alkaline pH, usually in the range 9 to 14. Preferably, sufficient alkali is used to give a pH which is initially in the range 10 to 12 and which may fall slightly when a reducing sugar is used as discussed below, due to conversion of some reducing sugar to organic acid. The amount of alkali will normally range from about 1 to about 17%, particularly 2 to 13%, based on the total wbight of the reaction mixture.

Preferably, the aqueous alkaline medium is heated to a temperature of 60 to 1100C, more preferably 70 to 950C, to enhance the reducing activity of the reducing agent. Heating is-preferably continued until a sufficient amount of the dyestuff is reduced so that at least 90%, preferably at least 95%, most preferably atleast 99%, by weight, of the dyestuff becomes dissolved.

With some sulphur dyes, such as C.I.. Sulphur Black 1 and 2, it has been found that sufficient reduction can be effected without adding any reducing agent to the alkaline medium. The alkali, such as sodium hydroxide, reacts with sulphur associated with the dye to form, in situ, sulphides such as sodium sulphide 150-5164 and sodium hydrogen sulphide, which, in turn, reduce the dye and render it soluble in the aqueous alkaline medium.

Preferably, a reducing sugar is included in the aqueous alkaline medium.

As the reducing sugar, there may be used any of those carbohydrates or combinations thereof which reduce a Fehling solution, e.g. monosaccharides, for example aldopentoses such as arabinose, ribose and xylose, hexoses such as glucose, fructose, mannose and galactose, and the deoxy, dideoxy and aminodeoxy derivatives thereof, disaccharides, such as sucrose, lactose, maltose and cellobiose, and tri-, tetra- and pentasaccharides. Products such as corn syrup, invert sugar and molasses which contain reducing sugar, may also be used, as may glucose prepared in situ from sucrose. The preferred reducing sugar is glucose.

The amount of reducing sugar will vary with the particular sulphur dye and the concentration thereof in the aqueous alkaline medium- Enough should be used to reduce the dye sufficiently to render it completely dissolved or miscible to the extent of at least 90% in the aqueous alkaline medium. Preferably, the amount of reducing sugar is sufficient to assure complete dissolution or miscibility of the dye in the dye liquid composition at any concentration and temperature at which the dye composition is likely to be stored or shipped. Typically, the amount of reducing sugar is in the range 1 to 25%, preferably 4 to 18%, based on the total weight of the reaction mixture. Based on'the weight of dye, the amount of- reducing sugar, when used, is usually in the range 2 to 200%, particularly 8 to 95%, more particularly 25 to 85%.

Preferably, no sodium sulphide or other sulphide reducing agent is added to the aqueous alkaline medium. More preferably, reducing-sugars are the only reducing agents added during the preparation of the prereduced sulphur dye liquid. However, as a result of interaction of sulphur, which may be present as elemen V - Q 14 1505164 tal sulphur or attached to the dye chromophore as a polythio group, with the alkali, as discussed above, and/or with electrons of oxidation of the reducing agent which takes place during the reduction of the dye, a small amount of sulphide, e. g. sod-ium sulphide, or sodium hydrogen sulphide, may be formed in situ. The amounts of. elemental sulphur which may be present in the thionation product may be lowered by known methods, such as by treating the oxidized thionation product with aqueous sodium sulphite to dissolve the sulphur, followed by filtration.

- When necessary, the total inorganic sulphide content of the liquid dye composition may be controlled by regulating the amounts of alkali and especially of reducing sugar in the reaction mix ture.

The sulphur dye used in the process of the invention may be any such dye obtained by a conventional thionation (sulphuriza- tion) reaction, either directly after thionation or after the procedure of precipitatind and optionally isolating as disclosed thereafter. Representative of such dyes are C.I Sulphur Black 1 (Constitution No. 53 185), 2 (Constitution No. 53 195), 11 (Con stitution 53 290) and 18, C.I. Sulphur Green 2 (Constitution No.

53 571), 16 and 36, C.I. Vat Blue 43 (Constitution No 53 630), C.I. Sulphur Blue 7 and 13 (Constitution Nos 53 440 and 53 450), C.I. Sulphur Red 10 (Constitution No 53 228) and 14, C.I. Sulphur Brown 37, 10 (Constitution No. 53 055), 96, 52 (Constitution No.

-53 320), Cj. Sulphur Orange 1 (Constitution No. 53 050) and C.T.

Sulphur Yellow 22.

According to a preferred embodiment of the invention, the sulphur dye is one which has been washed to remove salts which are usually associated with such thionation products. Accordingly, a further aspect of the process of the present invention is the step of washing a sulp6ur dye with water prior to introducing it into the aqueous alkaline medium to be reduced. Preferably, the wash water is at a temperature such as to most efficiently remove the 150-5164 salts without dissolving a significant amount of the dye, e. g. 20 to 70% more preferably 30 to 500C. Preferably, the washing is carried out until the inorganic sulphate content, based on the weight of solids in the presseake, is less than 6%, especially less than 2%, more especially less than 0.6% by weight. More preferably, said percentages represent the maximum percentages of total inorganic salts. A convenient way to determine when the salt content is sufficiently low is by testing samples of the used wash water for electrical conductivity. The washing is continued until a sample of the wash water after washing shows a sufficiently low. conductivity, preferably one which is close to or more preferably the same as that of the wash water prior to washing. A conductivity meter, such as a Chemtrix type 700, may be used for this purpose. Using such an apparatus and washing with water having a conductivity of 60 to 80 micromhos/cm, good results are obtained when the washing is carried out until the used wash water shows a conductivity of 60 to 200, preferably 60 to 120 micromhos/cm. However, with a few sulphur dyes which exhibit some degree of water-solubility in the oxidized form, a somewhat higher conduc- tivity reading, e.g. up to 400 micromhos, may be obtained due to the presence in the used wash water of a small amount of dissolved dye in addition to inorganic salts.

Preferably, the sulphur dye is one-which, in oxidized form passes the following test; Disperse 5.0 g presscake in 10 cm3 water at room temperature by vibration in a Fischer Benchtop Ultrasonic Cleaner for 15 minutes. Filter the resulting dispersion through a 0.45 micron Metrical Membrane Filter, 47 mm diameter, (Millipore Corp.) at No. XX 1004700. The filtrate should have no colour.

As indicated above, the thionation and-precipitation steps whereby the sulphur dyes used in the process of the invention are produced are conventional. The thionation reaction may, for in stance, be carried out as disclosed in Colour Index, volume 4, third edition (1971), page 4475 to 4501. As is clear from this 1 1 150-5164 reference, a wide variety of organic compounds can be used as starting materials. The thionating agent is usually sulphur or an alk li metal polysulphide and is preferably used in a minimum amount. The thionation may be effected by baking or by refluxing the reactants in a liquid medium, such as water or a lower alcohol, e.g ethanol or butanol. If necessary, particularly where thionation has been effected by baking, the product is dissolved In aqueous sodium sulphide or caustic, usually at elevated temperatures.

Precipitation is effected by treating the thionation product in an aqueous medium with a sufficient amount of an oxidizing agent and optionally an ac1d or an alkali to precipitate the -sulphur dye. Any oxidizing agent known to be useful in the art may be employed, such as sodium nitrite, hydrogen peroxide, oxygen or air. Suitable acids include-sulphuric acid and/or hydrochloric acid. The amount of oxidizing agent and/or acid will vary depending on the nature of the particular thionation product, e.g. the particular dye produced and the amount of sulphides p.resent. Preferably, it will be sufficient to completely precipitate the sul- phur dye. When an alkaline medium is used, it may contain up to 5% by weight of an alkali as indicated.

Preferably, the sulphur dyes used in the present invention are precipitated by oxidation. More preferably, the oxidation is carried out until the oxidation mass is free of sodium sulphide, and sodium hydrogen sulphide, as can be determined by known analytical methods, e.g. the iodometric titration with sodium thiosulphate solution. Most preferably, the thionation product is diluted with water or a concentrated alkalimetal hydroxide and aerated at about 40 to 90C until complete precipitation of the dyes-ogcurs.

It may on occasion be advantageous to add a salt such as sodium chloride to promote precipitation of the-dye, as disclosed in the description of CI Sulphur Blue 11 (Constitution No. 53235) at page 4487 of the aforementioned Colour Index.

150-5164 The precipitated sulphur dye Is isolated by known methods, e.g. filtration, and preferably washed as discussed above.

In addition to the prereduced sulphur dye, alkali, reducing sugar and water, there may be included in the dye liquid an agent which further increases the solubility of the reduced dye therein Once the precipitated dye has been separated from the residue of the thionation reaction mixture and preferably washed, it is further preferred to avoid adding thereto any ionic components. Therefore, the solubility-increasing agent is advantageously non- ionic. Suitable for this purpose are non-ionic hydrotropic agents, such as ethylene glycol, diethylene glycol, polyethylene glycol, diethylene glycol mono C1-6 alkyl ether, preferably diethylene glycol mono methyl or mono ethyl ether,diethylene glycol di C 1-4 alkyl ether, propylene glycol and urea, as well as triethanol- amine. The preferred hydrotrope is diethylene glycol. The hydrotrope is used in an amount of about 3 to 35%, usually 4 to 22 %, based on the total weight of the liquid dye composition.

The order of addition of the components is not critical. All of the components, i.e. dye, reducing sugar, alkali, water and optional solubility-increasing agent may be mixed together and then heated. Preferably, however, the components other than the reducing sugar are combined and heated to 60 to 110% preferably 80 to 95% and the reducing sugar is then added. Heating is continued, preferably with agitation, until all of the components have gone into solution.

According to a further preferred embodiment, the sulphur dye reduction of the invention is effected under an inert atmosphere, such as nitrogen. Preventing contact of the dye liquid with oxygen increases the efficiency of the reduction and lowers the require- ments of reducing sugar and alkali, thus permitting higher concentrations of dye in the final product.

d 5; 1.

150-5164 In some instances it may be desirable to control the reduction conditions in order to avoid the co-production of an excessive amount of sulphides, such as sodium sulphide. This may result in a small portion, e.g. up to 10%, preferably no more than 5% by weight of the dye remaining undissolved. In such instances it is advantageous to subject the prereduced sulphur dye liquid to a final clarification step. This can be achieved by filtering the liquid, preferably while s till at or near the temperature at which the reduction is effected. More preferably, a filtration aid, such as a diatomaceous earth or activated charcoal, is added to the liquid with stirring and the liquid is filtered. The amount-of such filtration aid may vary over a wide range but is usually 1 to 12%, preferably 2 to 6% by weight, based on the weight of the dye liquid.

The preferred liquid compositions of the invention have in addition to their low inorganic sulphide content, also a low content of inorganic salts. Preferably they contain less than 3%, more preferably less than 1.5%, especially less than 0.4%, more especially less than 0.1% by weight of inorganic sulphates, more preferably less than said percentages of total inorganic salts other than sulphides.

The prereduced sulphur dye content of the compositions pref erably exceeds,8% by weight and more preferably is in the range 8.5 to 40%, especially 15 to 36% by weight.-Typically, a composi tion of this invention further contains 1 to 25%, particularly 4 to 18% reducing sugar and/or oxidized derivatives thereof, 1 to 17%, particularly 2 to 13% alkali metal hydroxide, carbonate or phosphate (or sufficient to give a pH of about 9 to 14), 22 to 75%, particularly 22 to 55% water and, when present, about 2 to 35%, particularly 4 to 22% solubility-increasing agent, by weight.

The liquid dye compositions of the invention provide several advantages.

150-5164 Their low content of inorganic sulphides, e.g. sodium sulphide, sodium hydrogen sulphide and sodium polysulphides, reduces unpleasant odours, decreases the danger of hydrogen sulphide formation, lessens the need for effluent treatment and reduces the loss of tensile strength (tendering) of cotton fabrics dyed with black sulphur dyes.

Because sulphur dyes have high molecular weights and contain as solubilizing groups only thiol groups, they have limited solubility in water. Therefore, the presence of salt has a powerful salting out effect on the dye. The low inorganic salt content of the instant compositions gives them improved stability during shipping and storage. They are stable for at least 24 hours and preferably longer than Z8 hours at -60C. While the compositions may contain limited amounts of inorganic sulphides, as dis- cussed above, it is believed that in such controlled amounts these sulphides may enhance the stability of the compositions by supplementing the reducing power of the reducing sugar.

Since all ionic components, except the dye and a necessary amount of alkali to establish a satisfactory pH, are either drastically reduced or completely eliminated, the above formulation results in a unique dye liquid in which the ionic character of the dye solution is substantially reduced and, rather, a nonionic (or organic liquid) behavior predominates when'such liquid is applied to a fabric.

Their low salt content also enables.the compositions of the invention to have a high content of dye.

Because of the decreased tendency to be salted out, the dyes of these compositions exhibit improved penetration. During the initial penetration phase of an exhaust dyeing process the dyes become more evenly distributed throughout the fibre before salt is added to cause them to exhaust onto the fibre. This reduces the likelihood of the dye precipitating onto the fibres prematurely, 1 150-5164 resulting in less even distribution and undesirable "bronzing" effect.

The compositions of the present invention also show a more moderate affinity or substantiyity for cellulosic materials. Con- sequently, they can be used in continuous dyeing of cotton and cotton/polyester to give level dyeings which are characterized by the absence of side-center-side cross shading and minimal tailing effects.

The liquid dye compositions of the invention can be used to 10 dye or print substrates dyeable with leuco sulphur dyes, such as cellulosics and blends thereof with other fibres, such as polyester, by methods which are conventional for dyeing and printing with previously known prereduced (leuco) sulphur dye liquids, as disclosed for example in the Colour Index, volume 3, third edition (1971) page 3649. The dye liquids of the invention can be used for discontinuous or continuous dyeing methods as well as for printing methods, e.g. beam, jig, package, beck, jet, pad-steam, pad-dry-pad-steam or pad-dry-thermosol-padsteam dyeing. T hey can be admixed to the dyebath or printing paste by simple dilution.

The amount of liquid dye composition added to the dyebath or printing pastg will depend upon the dye content of the particular liquid being employed and the desired characteristics of the dye ing or printing and is within the skill of the art to determine.

In general, about 7 to 350 preferably about 25 to 200 g of dye liquid are added per liter of dyebath.

While the amount of reducing agent included in the dye liquid during its preparation is usually sufficient to assure good dissolution of the dye in the dyebath, it is sometimes advantageous to add a supplemental portion of reducing agent to the dyebath.

Such reducing agents include the compounds conventionally employed for this purpose, such as sodium sulphide, sodium hydrogen sulphide, sodium polysulphide, sodium hydrosulphite or sodium 150-5164 formaldehyde sulphoxylate. However, the preferred supplemental reducing agents are the reducing sugars mentioned above, especially glucose. The amount of such optional supplemental reducing agent should be sufficient to assure complete dissolution of the dye in the dyebath and uniform and reproducible dyeings. It is well within the skill of the art to determine a suitable amount, depending on the particular dye liquid and reducing agent being used and the dyeing conditions. Typically, the amount is in the range 7 to 120 g, preferably 15 to 60 g per liter of dyebath.

Preferably a supplemental portion of alkali, such as sodium or potassium carbonate, hydroxide or phosphate is also added to the dyebath with the reducing agent, e.g. in an amount of about 3.5 to 60, preferably 5 to 30 g per liter.

The dyebath or printing liquors may contain further dyeing assistants, e.g. a wetting agent, for example in an amount of 1.0 to 15 g per liter.

After application of the dye, the substrate is subjected to an oxidation step as conventional when dyeing with sulphur or sulphur vat dyes. While some dyeings may become sufficiently oxidized by the water-rinsing step which normally follows the dyeing, it is preferable to carry out a-chemical oxidation. Suitable oxidizing agents are for example a combination of hydrogen peroxide and acetic acid or a catalyzed sodium bromate system.

In the following examples, which illustrate the invention, parts and percentages are by weight and temperatures are in Centigrade degrees.

1 150-5164 Example 1

382 g of crude thionation mass of CI Sulphur Blue 13 (CI No. 53450) prepared by the usual thionation technique are dissolved in 800 g water and the resulting solution is aerated at 68-70 for 6 hours, whereby the dye completely precipitates from solution. The precipitated dyestuff is filtered and the filter cake is washed with tap water at ambient temperature until a sample of the wash water shows no increase in conductivity from before washing to after washing. The yield is 349.4 g filter cake with a solids content of 25.4%.

57 g of filter cake pepared as described above, 18 g -diethylene glycol, 10g water and 16 g 50% sodium hydroxide liquid are mixed together and heated to 800. The mixture is then heated at 85 under nitrogen atmosphere and 11 g glucose are added gradually with stirring. Heating is discontinued after 25 minutes. A stable liquid dye composition having a sulphide content of 6.5% (as determined by potentiometric titration with 0.2 N.cupric ammonium sulphate) and a pH of 10.9 is obtained in a yield of 110.3 g.

Example_2

400 g of crude thionation mass of C.I. Sulphur Red 10 (CI 53228) prepared by the usual thionation technique are dissolved in 3000 g water at about 500 and the solution is heated to 70-75 and aerated at that temperature for 6 hours. The sulphide content of the resulting oxidation mass is 0, as determined by iodometric titration with OAN sodium thiosulphate solution. The precipitated dye is isolated by filtration and the filter cake is washed with tap water having a conductivity of about 60 micromhos/cm until the used wash water shows a conductivity of about 95.micromhos/cm. The resulting presscake weighs 273.5 g and has a solids content of 63.0%.

150-5164 44.9 g of the above prepared-filter cake, 30.0 g diethylene glycol and 23.Og 50% sodium hydroxide are mixed together and heated at 851 under a nitrogen atmosphere while 4.0 g glucose are added gradually with stirring. After 30 minutes 2 g of Filter Aid 4200 FW50, a diatomaceous earth filtering aid, are added and the liquid is stirred for two minutes and filtered through 11 cm Fischer filter paper. A stable liquid dye composition having a pH 11.1 is obtained in a yield of 100.0g.

Example 3

Over a period of 20 minutes 192 g crude thionation melt of C.I. Sulphur Yellow 22 are added to a mixture of 180 g water and 330 g sodium hydroxide 50 % solution while said mixture is heated at a temperature of 115-120'. Heating is continued at 1201 for 2 hours while keeping the volume constant. The resulting mixture is diluted to 1500 ml with additional water and 200 g sodium chloride are added thereto. The resulting mixture is aerated at 85 for 58 hours, until the sulphide content is 0, and then cooled to room temperature. The pH is then adjusted to 6.0 by addition of 36.4 g sulphuric acid 75% solution and the resulting mixture is stirred overnight at room temperature. It is then filtered and the filter cakels washed with 14 liters tap water at 4011 until the conductivity of the used wash water is 82 micromhos/cm. The yield is 666.0 g presscake having a solids content of 11.2 %.

A mixture of 84.0 g of the above-prepared presscake and 12.0 g sodium hydroxide (50% solution) is heated to 75 under a nitrogen atmosphere. 6 g glucose are added and heating is continued at 85 for 30 minutes. The resulting liquor is filtered through 11 cm Fisher filter paper to give 101.0 g liquid dye having a sulphide content of 1.18% (as determined by potentiometric titration with 0.2N cupric ammonium sulphate) and a pH of 11.6.

Z_ 1.

- is - 1 t" 150-5164 Example 4

A mixture of 200 g of C.I. Sulphur Black 2 (CI 53195) press- cake and 2 liters of water is stirred at room temperature for 30 minutes and then filtered. The filtrate is washed with 16 liters tap water at 501. The final used wash water has a conductivity of 300 micromhos/cm due to the presence of a small amount of dissolved dye therein. There is obtained 165.9 g of presscake having a solids content of 60.1%.

A 46.6 g portion of the above-prepared presscake is mixed with 20 g aqueous sodium hydroxide (50%) and 15 g water and heated at 901 for 40 minutes under a nitrogen atmosphere. A stable liquid dye composition having a sulphide content of 7.94% (as determined by potentiometric titration with 0.2N cupric ammonium sulphate) and a pH of 11.4 is obtained in a yield of 80 g.

Example 5

A mixture of 963 g thionation mass of C.I.. Sulphur Blue 7 (CI 53 440) and 2000 g water is aerated at 851 for 14 hours until the sulphide content is 0 and the dye is completely out of solution.

The resulting slurry is filtered and the filter cake is washed with 3 liters water at 50 and 100 g sodium sulphite are added thereto. The resulting mixture is heated at 721 for 2 hours to effect further desulphurization and then filtered. The filter cake is washed with 10 liters water at 500. Yield: 533 g.

77 g of the above-prepared filter cake having a solids con- tent of 91.7%, 30 g diethylene glycol, 25 g aqueous sodium hydroxide (50%) and 50 g water are mixed together and heated to 880 under a nitrogen atmosphere. 20 g glucose are added and heat ing is continued for 20 minutes. A liquid dye composition having a sulphide content of 5.15% (as determined by potentiometric titra tion with 0.2N cupric ammonium sulphate) and a pH of 11.1 is ob tained in a yield of 200 g.

Example 6

150-5164 A mixture of 250 parts crude thionation mass of the green sulfur dye prepared according to Example 1 of US Patent 3,338,918 and 488 parts water is aerated at 88 for 2 hours, cooled to 451 and filtered. The filter cake is washed with 12,000 parts tap water until the washing liquid isclear and has a conductivity of 110 micromhos/cm. A presscake having a weight of 55 parts and a solids content of 43.2% is obtained.

6.5 Parts of the aboveprepared presscake, 2.0 parts water.

2.0 parts diethylene glycol and 2.2 parts sodium hydroxide 50% solution are mixed together and heated to 781 under a nitrogen atmosphere. 1.2 Parts o f'glcose are added and the mixture is stirred at 85 for 30 minutes. The resulting liquid is filtered through 11 cm Fischer filter paper and there is obtained 13.7 parts of a green liquid dye composition having a pH of 11.5 and a sulphide content of 4.2% (as determined -by' potentiometric titration with 0.2N cupric ammonium sulphate).

Example 7

78 g diphenylamine are reacted with 71 g p-nitrosophenol at 0-5 to provide the corresponding indophenol which is reacted under boiling at 1100 with 67 g sodium sulphide 60% and 100 g sulphur. The resulting blue sulphur dye (CI Sulphur Blue 13, Con stitution No. 53 450) is diluted with 1,250 g water, 180 g sodium hydroxide 50% and 215 g glucose are added to the sulphur dye and the resulting mixture is heated for 15 minutes at 70. A stable prereduced sulphur dye composition having a sodium sulphide content of 1.5 to 2.5% (as determined by iodometric titration) is obtained.

1 1 150-5164 Example 8

325 g p-Hydroxy-diphenylamine is reacted at 120 with 383 sodium sulphide 60% and 490 g sulphur to yield a reddish-brown sulphur dye (CI Sulphur Brown 96). At the the end of the thiona tion reaction 770 g water, 268 g sodium hydroxide 50% and 156 g glucose are added. The mixture is then heated to 80-850 for 30 minutes and a total reduction of the dye is observed. The re sulting liquid composition has a sulphide content of 2-3% (as determined by iodometric titration).

Example 9

A mixture of 73.5 g p-phenylenediamine, 43.5 g m-toluenediamine and 12 g p-aminophenol is reacted with 242 g sulphur at 250-300 for 26 hours to yield an olive green dye (CI Sulphur Green 16). The dye is dissolved in 366 g of sodium hydroxide 50% and desulphurized by blowing air through the solution until the sodium sulphide content is lower than 2%. After addition of 110 g glucose and 163 g sodium hydroxide 50% while heating at 800, there is obtained a liquid composition of the reduced dye having a low sulphide content.- Application Example A g of the dye liquid prepared according to Example 1 and 50 g water are stirred together until a clear solution is obtained.. To this solution art added 8 g glucose, 4 g NaOH 50% liquid, 10 additional g water and 0.5 g Penetrant EH (anionic phosphate ester). The resulting mixture is stirred for 5 minutes and then diluted to 133 C with additional water.

The above prepared dyeing solution is heated to 430 and poured into a dye pan. Pre-bleached cotton twill cloth is padded through the dyeing solution to a wet pick-up of 70-80%, steamed for 60 seconds at 101-103' and then rinsed with warm tap water.

150-5164 An oxidizing solution is prepared by adding 7.5 g hydrogen peroxide (35% solution) and 7.5 g glacial acetic acid to sufficient water to give a total volume of one liter. This solution is heated to 600 and the above- dyed substrate is added and the solution is stirred for 30 seconds. The substrate is then rinsed with warm tap water until clean and then dried.

Application Example B The following percentages are based on the weight of the textile material.

A cotton fabric is introduced in a dyebath containing 1 % of a commercially available wetting agent, 5 % sodium hydroxide 50%, 6 % glucose and 4 % of the liquid dye composition of Example 7. The liquor ratio is 10:1. The temperature of the dyebath is raised to 90-950 and then 20-40% sodium sulphate are added to the dyebath in 3 portions within 16 minutes. Dyeing is continued at 90-950 for 45 minutes. Thereafter the dyebath is cooled to 7C and the dyed fabric is rinsed until water is clear.

An oxidizing solution is prepared by adding 2% hydrogen peroxide (35% solution) and 2% acetic acid 80% to sufficient water to have a liquor to goods ratio of 10:1. The fabric is introduced in this bath and is treated for 20 minutes at 500 with this bath.

After rinsing, the fabric is soaped for 15 minutes at 800 with 2% of a commercially available soaping agent based on polyacrylate and then rinsed and dried.

- 19 150-5164

Claims

Claims: -

1. A liquid dye composition comprising at least one sulphur dye reduced in leueo form and a reducing agent for said dye which is selected from a sulphide formed in situ or stemming from thionation and a reducing sugar, the composition having a total inorganic sulphide content of < 3% by weight based on the total weight of the composition. -

2. A liquid dye composition according to Claim 1, having a total inorganic sulphide content in the range 1 to 2.5% by weight 10 based on the total weight of the composition.

3. A liquid dye composition according to Claim 1 or 2, containing an alkali.

4. A liquid dye composition according to Claim 3, containing as alkali an alkali metal hydroxide, carbonate or phosphate.

5. A liquid dye composition according to any one of the preceding claims,-comprising the leuco reduced sulphur dye in an.

amount exceeding 8 % by weight.

6. A liquid dye composition according to Claim 59 comprising 8.5 to 40 % by weight of sulphur dye reduced in leuco form.

7. A liquid dye composition according to Claim 5 or 6, having a total inorganic sulphide content in the range 0 to 18.5% based on the weight of leuco r educed sulphur dye.

8. A liquid dye_composition according to Claim 7, having a total inorganic sulphide content in the range 1 to 14% based on the weight of leuco reduced sulphur dye.

7 150-5164

9. A liquid dye composition-according to any one of the preceding claimso having an inorganic sulphate content less than 3 % by weight.

10. A liquid dye composition according to Claim 9, having an 5 Inorganic sulphate content less than 1.5% by weight.

11. A liquid dye composition according to any one of the preceding claims, hiving a total Inorganic salt content other than sulphides less than 3 % by weight.

12. A liquid dye composition according to Claim 11, which Is 10 essentially free of inorganic salts other than sulphides.

13. A liquid dye composition according to any one of the preceding claims, containing 1 to 17 % by weight alkali.

14. A liquid dye composition according to any one of the preceding Claims, free from reducing sugar.

is

15. A liquid dye -composition according to Claim 14, containing as leuco reduced sulphur dye,.a dyestuff derived from C.I. Sulphur Black 1 or 2.

16. A liquid dye composition according to any oneof Claims 1 to 13, containing a reducing sugar as reducing agent.

17_. A liquid dye composition according to Claim 16 containing the reducing sugar in an amount of from 1 to 25 % by weight based on the total weight of the composition.

18. A liquid dye composition according to Claim 17 containing 4 to 18 % by weight reducing sugar.

150-5164 111

19. A liquid dye composition according to Claim 16 containing 2 to 200% by weight reducing sugar based on the weight of dye.

20, A liquid dye composition according to any one of Claims 5 16 to 199 in which the reducing sugar is selected from reducing monosaccharides, di- , tri-, tetra- and pentasaccharides.

21. A liquid dye composition according to Claim 20, in which the reducing sugar is selected from arabinose, ribose, xylose, glucose, fructose, mannose, galactose, sucrose, lactose, maltose 10 and cellobiose.

22. A liquid dye composition according to any one of the preceding claims, containing a non-ionic hydrotropic agent which furth r increases the solubility of the reduced dye therein.

23. A liquid dye composition according to Claim 22 containing 2 to 35 % by weight of a non-ionic hydrotropic agent.

24. A liquid dye composition sustantially as hereinbefore described with reference to any one of Examples 1 to 9.

-

25. A process for producing a liquid composition of a sulphur dye in reduced leuco form which comprises reducing a sulphur dye-in an aqueous alkaline medium containing, as the reducing agent for the sulphur dye, a reducing sugar or a sulphide which is formed in situ or stems from thionation.,

26. A process according to Claim 25 wherein no sulphide reducing agent is added to the aqueous alkaline medium.

27. A process according to Claim 25 wherein a reducing sugar is present in the aqueous alkaline medium.

150-5164

28. A process according to any one of Claims 25 to 27 wherein the sulphur dye is one obtained by oxidizing in an aqueous medium or an alkaline medium the product obtained by thionating an organic compound.

29. A process according to any one of Claims 25 to 28 wherein the aqueous alkaline medium also contains a non-ionic hydrotropic agent.

30. A process according to any one of Claims 25 to 29 which further comprises the step of washing the sulphur dye to remove inorganic salts prior to adding said dye to the aqueous alkaline medium.

31. A process according to Claim 30 wherein the sulphur dye is washed until it contains less than 6 % inorganic sulphates based on the total weight of solids.

32. A process for producing a liquid composition of a sulphur dye in reduced leuco form, substantially as hereinbefore described with reference to any one of Examples 1 to 9.

33. A method of dyeing or printing a textile substrate which comprises applying thereto a composition according to any of Claims 1 to 24.

Published 1988 at The Patent Office, State House, 66171 High Holborn, London WClR 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Max7 Cray, Orpington, Kent BR5 3RD. Printed by Multiplex teobniques ltd, St Mary Cray, Kent Con. 1/87.

i ig