CH683663B5 - Process for the continuous dyeing or printing of cellulosic substrates with dispersed sulfur dyes. - Google Patents

Description

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description

This invention relates to an improved process for dyeing or printing cellulose substrates with sulfur dyes and to a block liquid as a means for carrying out this process, as defined in the claims.

The substrate to be colored or printed according to the invention can be any substrate containing cellulose fibers. The substrate can be in any form, e.g. as yarn, woven or knitted fabric. It can only contain cellulose fibers or a mixture of cellulose fibers with synthetic fibers such as polyamide, polyester or polyacrylonitrile. The preferred cellulose material contains cotton. Even better, the substrate comprises cotton alone or mixed with polyester.

The dyeing is preferably carried out using the pad-steaming method or the pad-dry-pad-steaming method.

According to the pad-steaming method, an aqueous dye liquor containing the sulfur dye, a reducing sugar and alkali is preferably applied at a temperature at which the sulfur dye remains in the oxidized state, preferably in the range from 20 to 60 ° C., even better 25 to 50 ° C. In general, so much liquor is applied that 55 to 70% (based on the weight of the substrate) remains on the substrate. After the dye liquor has been applied, the substrate is heated to a temperature which is sufficiently high to bring about the reduction in the dye, usually from 98 to 105 ° C., preferably from 100 to 103 ° C.

According to the pad-dry-pad-steaming process, a dye liquor containing the sulfur dye is brought to the substrate at a temperature of 20 to 75 ° C., preferably 30 to 65 ° C., up to a moisture absorption of 55 to 70%, the substrate is dried, then padded with a solution of a reducing sugar in aqueous alkali, preferably to a moisture absorption of 90 to 120%, and then heated as above to effect the reduction of the dye.

Printing can be carried out in a similar manner to the pad-dry-pad-steaming process, by printing the substrate with a printing paste instead of padding it with a dyeing liquor.

If the substrate is a cellulose-polyester mixture, the block-dry-thermosol-block-steaming method is used with advantage. A suitable disperse dye is introduced into the dye liquor together with the sulfur dye, and a thermosol treatment is carried out after the drying step. Apart from this, this process is similar to the block-dry-block-steaming process.

As indicated above, the heating is preferably carried out with steam, more preferably in a non-pressurized damper of a conventional foulard damper, in which the substrate is only under a slightly elevated pressure sufficient to allow air to enter the To prevent dampers, usually up to about 1.15 atmospheres. The heating should be carried out until the complete reduction of the dye on the substrate has been effected at the temperature used, but so short that a continuous process control in the particular device used is ensured. Preferably the heating time is about 20 to 110 seconds, more preferably 40 to 110 seconds and most preferably 40 to 75 seconds.

The dyeing can be carried out using conventional continuous dyeing equipment. As will be appreciated by those skilled in the art, such conventional devices include means such as one or more foulards for the continuous application of a dye liquor and a reducing sugar to the substrate and a non-pressurized zone, e.g. a damper in which the substrate treated in this way is then heated in order to reduce the dye. Similarly, printing can be done using conventional printing equipment in conjunction with a non-pressurized damper, preferably one specially designed to dampen prints and in which the printed portion of the substrate does not come into contact with rollers.

An advantage of the present invention is that the dyeing or printing with a sulfur dye can be carried out using an environmentally safe reducing sugar and conventional equipment. After the dye liquor or the printing paste has been applied to the substrate and the sulfur dye has been reduced, it is generally advantageous to subject the substrate treated in this way to an oxidation step in order to further improve the authenticity of the dyeing or the print. While some dyeings and prints are sufficiently oxidized with water by a rinse step normally performed after dyeing, it is preferred to perform chemical oxidation. Hydrogen peroxide or a catalyzed sodium bromate system can be used. The process conditions for the oxidation are the usual and vary depending on the device used and the speed at which the substrate travels. In general, sodium bromate, which is catalyzed with vanadium pentoxide, is used in amounts of 3.75 to 11.25 g / l, the pH is preferably 3 to 4.5 and the temperature is usually 45 to 85 ° C., preferably 49 to 82 ° C., more preferably 60 to 75 ° C. Hydrogen peroxide is used in amounts of 1 to 5 g / l at a pH of 5 to 7.5, preferably 5.5 to 6, and at a temperature of 35 to 60 ° C. To achieve this pH, acetic acid or formic acid is added. The substrate is exposed to the action of this oxidation liquor for 5 to 70 seconds, better for 10 to 40 seconds.

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The dye liquor is preferably prepared by mixing a previously prepared aqueous sulfur dye dispersion with additional water and, if the pad-steaming method is used, with a reducing sugar and alkali.

Preferred reducing sugars include those carbohydrates or combinations thereof that reduce Fehling's solution, e.g. Aldopentoses such as L-arabinose, D-ribose and D-xylose, hexoses such as D-glucose, D-fructose, D-mannose and D-galactose, and disaccharides such as cellobiose, lactose and maltose. Products such as corn syrup, invert sugar and molasses containing reducing sugar can also be used, as can dextrose made from sucrose in situ. The preferred reducing sugar is D-glucose. The amount of reducing sugar should be sufficient to reduce the sulfur dye when the liquor treated or printed substrate is heated as described above. Preferably, the reducing sugar is used in an amount of 30 to 135 grams per liter, more preferably 50 to 120 grams per liter, regardless of whether it is used in the dye liquor or separately in an aqueous alkali solution. The reducing sugar is preferably the only reducing agent added to the sulfur dye liquor or the aqueous alkali solution.

The alkali can be any that is known to be useful in the reduction of sulfur dyes, especially sodium or potassium hydroxide or carbonate, especially sodium hydroxide. The alkali is preferably used in an amount of about 8 to 70 grams, more preferably 10 to 50 grams, per liter of the dye liquor or the aqueous liquid containing reducing sugar used separately. The pH of this liquor or liquid should be at least 10, preferably at least 10.5.

The dye liquor can also contain a wetting agent to improve the penetration of the liquor into the substrate during use. The wetting agent in question is not critical. Anionic compounds are preferred, such as the sodium salt of phosphated 2-ethylhexanol. Typical amounts of wetting agent are in the range of 1 to 15 grams per liter of dye liquor.

The aqueous dye liquor to be used in the pad-dry pad-steaming process preferably contains an agent against migration of the dye during the drying step. Such products are known and can either be synthetic, e.g. based on polyacrylate, or with advantage naturally, e.g. based on alginates.

If the dye is to be applied by printing, conventional thickeners are used to produce a printing paste with the desired properties.

An aqueous sulfur dye dispersion used to prepare the dye liquor or printing paste is expediently a mixture of an oxidized sulfur dye in water which contains a sufficient amount of dispersant to bring about the dispersion of the dye in the water. It is expedient to start from a press cake of the oxidized sulfur dye, as is obtained by conventional sulfurization, dilution of the sulfurization mass with water, oxidation, filtration and washing of the filter cake.

The oxidation (aeration) is preferably carried out until the reaction mixture is free from inorganic sulfides. This point is displayed when the reduction equivalent of the reaction mixture is zero, as can be determined by potentiometric titration with 0.2N Cupri ammonium sulfate solution.

For some dyes, it is preferred to lower their poly-sulfur content to make them more dispersible. The amount of covalently bound sulfur, which connects the thiol groups of the dye with the chromophore, is defined as poly-sulfur content. This content varies from dye to dye and should be such that the dye is readily dispersible and can be easily reduced when heated. In general, this content is in the range from 0 to 3%, based on the dry weight of the dye, and can be determined by known methods.

Aeration of the suspension down to a reduction equivalent of zero can also serve to reduce the poly-sulfur content to the desired extent. It is advisable to carry out a test ventilation up to a reduction potential of zero and then to test the product for the poly-sulfur content. This can be done by treating a sample of the product with excess sodium sulfide, followed by calorimetric titration of the sample with sodium cyanide. If it is found that the poly sulfur content is higher than 7%, based on the dry weight of the dye, or better than 3%, the precipitation stage for the dye in question is expediently modified by treating with sodium sulfite and / or sodium nitrite before aeration in an amount effective to lower the poly sulfur content.

It is preferred to stop aeration as soon as possible after eliminating the sulfides. It has been found that overoxidation can lead to the formation of crosslinked polycondensation products which cannot be properly reduced by glucose caustic alkali and which are therefore undesirable in the dyeing and printing processes of this invention. It is advisable to monitor the particle size of the suspension, e.g. with a particle size analyzer, and shut off ventilation before an increase in particle size begins to occur.

The press cake is preferably washed to remove inorganic salts commonly associated with such sulfurization reaction products. The washing is conveniently carried out until the inorganic sulfate content is based on the weight of the solids

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in the press cake is less than 2%, preferably less than 0.6% by weight. It is even better to carry out the washing until the content of all inorganic salts is less than 2%, in particular less than 0.6% by weight. A useful way to determine when the salinity has dropped to the desired level is to check the electrical conductivity of the wash water used, for example with a Chemtrix Type 700 conductivity meter. When using this method, washing is preferably carried out until the conductivity of the wash water after use is not more than 140, more preferably not more than 60 micromhos / cm higher than the conductivity of the wash liquid before use. The press cake is combined with additional water in an amount so that the dye content of the mixture obtained is in the range of -40%, preferably 10-35%, more preferably 15-35% by weight. The relevant dispersants used to make the dye dispersions are not critical. Good results have been obtained when various anionic and or nonionic surfactants and mixtures thereof are used, such as sodiumignin sulfonates, commercially available under the trademarks Vanisperse CB, Reax® 85 A and Reax® PC 946, sodium salts of polymerized alkylnaphthalenesulfonic acids (for example Ta- mol® SN) and mixtures of glycols. The amount of dispersant required depends in part on the dye to be dispersed and can easily be determined by a person skilled in the art. Good results have been obtained when 5 to 20% dispersant is used based on the total weight of the dispersion. Other additives, such as biocides, can also be included in the dispersion. The constituents of the dispersion are preferably stirred together and the mixture obtained is ground until a good dispersion is obtained in which the particles of the dispersed sulfur dye preferably have a size in the range from 0.1 to 5) x, more preferably 0.3 to 1.5fi , measured with a Microtrac® particle size analyzer (Leeds-Northrup). The amount of dye dispersion used to prepare the dye liquor or the printing paste varies depending on the dye content of the dispersion and the desired depth of shade. About 15 to 165 grams of dye dispersion per liter of dye liquor are usually added.

The method of the present invention is particularly suitable for dyeing cellulosic textile material with sulfur dyes which require a relatively low reduction potential for their solubilization, e.g. oxidized sulfur dyes that can be reduced with glucose and sodium hydroxide at concentrations in the ranges given above within 60 seconds at 102 ° C. Representative representatives of such dyes are C.I. Sulfur Black 1 (Const.No. 53185), C.I. Sulfur Black 2 (Const.No. 53195). C.l. Sulfur Black 18, C.I. Sulfur Green 2 (Const.No. 53571), C.I. Sulfur Green 36, C.I. Sulfur Blue 7 (Const.No. 53440), C.I. Sulfur Blue 13 (Const.No. 53450), C.I. Sulfur Blue 43 (Const.No. 53630), C.I. Sulfur Red 10 (Const.No. 53228), C.I. Sulfur Red 14, C.I. Sulfur Brown 37 and C.I. Sulfur Yellow 22. Since the dyes are in the water-insoluble oxidized state when applied to the substrate in accordance with the process of this invention, they are not substantive to the cellulose fibers and do not immediately absorb onto the fibers, but rather have the possibility of being uniform to distribute before they become substantive through the heating level. It follows that problems like side-center overstaining and final waste are avoided. The invention is illustrated by the following examples, in which the parts and percentages are based on weight.

EXAMPLE 1

A mixture of 250 parts of a raw sulphurized mass of C.I. Sulfur Green 36, prepared according to Example 1 of US Pat. No. 3,338,918, and 488 parts of water are aerated at 88 ° C. for 2 hours, cooled to 45 ° C. and filtered. The filter cake is washed with tap water with a conductivity of 65 micromhos / cm until the washing liquid is clear and has a conductivity of 110 micromhos / cm. 55 parts of a press cake with a solids content of 43.2% are obtained.

A laboratory ball mill is loaded with:

13.9 parts of the sulfur dye press cake prepared above

2.4 parts of sodium iignin sulfonate (Vanisperse CB),

1.5 parts sodium salt of polymerized alkylnaphthalenesulfonic acid (Tamol® SN)

0.6 parts of a mixture of diethylene glycol and 2,4,7,9-tetramethyl-5-decyne-4,6-diol (Surfynol® 104 E), 0.1 part of sodium salt of chlorinated bis-phenol (Giv-gard G4-40) and 11.0 parts water.

The resulting mixture is stirred and then milled for 24 hours, whereby 28.5 parts of a dispersion of the sulfur dye prepared above are obtained. 5 parts of the dye dispersion prepared above and 50 parts of water are stirred together until a uniform mixture is obtained. 12 parts of glucose and 12 parts of aqueous sodium hydroxide are added to this mixture

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(50%), 10 parts of water and 0.5 part of sodium salt of ethylhexanol phosphate ester were added. The resulting mixture is stirred for 5 minutes and then diluted with 133 parts of additional water.

The dye liquor prepared above is heated to 43 ° C and poured into the dyeing trough of an Aztec® Laboratory foulard damper that has a non-pressurized damper. Pre-bleached cotton body fabric is padded through the dye solution to a wet absorption of 70-80%, steamed at 101-103 ° C for 60 seconds and rinsed with warm tap water.

By adding 7.5 g of hydrogen peroxide (35% solution) and 7.5 g of glacial acetic acid to enough water to make a total volume of 1 liter, an oxidation solution is prepared. This solution is heated to 60 ° C. The substrate colored as above is added and the solution is stirred for 30 seconds. The substrate is then rinsed with warm tap water until it is clean and then dried. A uniform green color is achieved.

EXAMPLE 2

To 402 parts of a raw sulfurization mass of C.I. Sulfur Blue 13 (C.I.Const.No. 53450) is added to 1354 parts of water. The mixture obtained is aerated at 90 ° C. for 11 hours until all of the sulfides are completely oxidized (determined by measuring a reduction potential of 0). The pH of the resulting slurry is lowered to pH 5.6 by the addition of 7.5 parts sulfuric acid (70%) and it is then filtered. The filter cake is washed with tap water with a conductivity of 65 micromhos / cm until the conductivity of the wash water is less than 110 micromhos / cm, whereby 285 parts of a filter cake with a solids content of 27.5% are obtained.

A ball mill is loaded with:

203 parts of the sulfur dye filter cake prepared above,

15 parts sodium iignin sulfonate (Vanisperse CB),

12 parts sodium salt of polymerized alkylnaphthalenesulfonic acid (Tamol® SN)

1 part of 6-acetoxy-2,4-dimethyl-M-dioxane (GIV-GARD DXN) and

63 parts of water.

The resulting mixture is milled with balls for 24 hours and then with sand for 24 hours until the particle size is in the range 1-5p. lies, and then separated from the sand.

An aqueous dye liquor is prepared which contains 30 parts of the dye paste prepared as described above and 15 parts of an alginate-type anti-migration agent per 1000 parts of water. Bleached, mercerized cotton twill is padded with this liquor at 60 ° C to a wet absorption of 60 to 70%, pre-dried in an infrared dryer (Forstoria) to remove 30% of the moisture and then in an oven at 82-99 ° C until dried completely dry. The material is then processed at room temperature in a foulard damper manufactured by Greenville Steel Textile Machinery Corp. (Serial No. 39377), padded to 100% wet with an aqueous liquid containing 1000 parts water, 60 parts aqueous sodium hydroxide (50%) and 120 parts dextrose, and then 60 seconds at 103 ° C in the damping chamber of the foulard damper not pressurized. The material is then washed with water at room temperature and subjected to a combined oxidation rinse at 65 ° C. for 30 seconds in an aqueous bath which is based on 1000 parts of water, 7.5 parts of acetic acid (56%), 7.5 parts of sodium bromate catalyzed with vanadium pentoxide and 3.75 parts commercial nonionic detergent (Sodyeco® Scour TR). After further washing with water at 65-70 ° C and then with water at room temperature, a uniform blue color is obtained, which is characterized by its excellent gloss.

Claims (1)

Claims 1. A process for dyeing or printing a cellulose-containing substrate, characterized in that an aqueous dispersion of a sulfur dye and either simultaneously or subsequently a reducing sugar together with alkali is applied to this substrate in a continuous manner and then the substrate thus treated is heated sufficiently to to effect the reduction of the sulfur dye thereon. 2. The method according to claim 1, characterized in that the reduction of the sulfur dye is carried out by heating the substrate in a non-pressurized damper. 3. The method according to claim 1 or 2, characterized in that an aqueous dye liquor containing the sulfur dye, reducing sugar and alkali is applied to the substrate. 4. The method according to claim 1 or 2, characterized in that one on the substrate 6 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 CH 683 663G A3 aqueous dye liquor containing the sulfur dye and then applying a solution of a reducing sugar in aqueous alkali. 5. The method according to any one of the preceding claims, characterized in that the reducing sugar is glucose. 6. The method according to any one of the preceding claims, characterized in that the sulfur dye is free of inorganic sulfides. 7. The method according to any one of the preceding claims, characterized in that the sulfur dye is selected from C.I. Sulfur Blacks 1, 2 and 18, C.I. Sulfur Greens 2 and 36, C.l Sulfur Blues 7, 13 and 43, C.l. Sulfur Reds 10 and 14, C.I. Sulfur Brown 37 and C.I. Sulfur Yellow 22. 8. Cellulose-containing textile substrate, dyed according to the method according to one of the preceding claims. 9. Block liquid as a means for carrying out the block steaming method according to claim 3 or the block dry block steaming method according to claim 4, containing 30 to 135 grams per liter of reducing sugar and 8 to 70 grams per liter of alkali. 10. Block liquid according to claim 9, containing 50 to 90 grams per liter of reducing sugar and 10 to 35 grams per liter of alkali. 7