FR2635795A1 - METHOD FOR DYING AND PRINTING CELLULOSIC SUBSTRATES WITH SULFUR COLORANTS - Google Patents

Abstract

The subject of the invention is a process for dyeing or printing substrates containing cellulosic fibers, a process according to which: a) an aqueous dispersion of a sulfur dye is continuously applied to the substrate and, simultaneously or after, it is applies a reducing sugar together with an alkali, then b) the substrate is heat treated to effect reduction of the sulfur dye on the substrate.

Description

l

  The present invention relates to a method of

  die dyeing and printing substrates containing

  cellulosic fibers with sulfur dyes.

  The present invention relates in particular to

  a process for dyeing or printing substrates containing cellulosic fibers, wherein

  a) a dispersion is continuously applied to the substrate

  aqueous solution of a sulfur dye and, simultaneously,

  afterwards, a reducing sugar is applied together with an alkali, and then b) the substrate is treated with heat to perform

  reducing the sulfur dye on the substrate.

  The heat treatment for reducing the sulfur dye on the substrate is preferably carried out by treating the substrate at a temperature between 98 and 105 C, more preferably between

and 1030C.

  The substrate to be dyed or printed according to the present invention may be any substrate containing cellulosic fibers. The substrate may be in any form, for example in the form of yarn, fabric or knit. It may contain only cellulosic fibers or a mixture of cellulosic fibers and synthetic fibers such as for example polyamide fibers, polyesters or polyacrylonitrile. The preferred cellulosic substrates contain cotton. More preferably, the substrate contains cotton alone or blended with polyester. The dyeing is carried out preferably by the pad-steam process or

  pad-dry-pad-steam (padding-drying-padding-

  steaming). According to the pad-steam process, we apply

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  preferably an aqueous dye bath containing the sulfur dye, a reducing sugar and an alkali, at a temperature at which the sulfur dye remains in oxidized form, preferably between 20 and C, more preferably between 25 and 50C.

  the substrate with the dyebath at a rate of ab-

  sorption between about 55 and 70% based on the weight of the substrate. After application of the dyebath to the substrate, the substrate is heated to a temperature high enough to effect dye reduction, usually between 98.degree.

   C, preferably between 100 and 103 C.

  According to the pad-dry-pad-steam process, the bath

  stain containing the sulfur dye is applied

  padding on the substrate, at a rate of absorption

  between 55 and 70% and at a temperature between 20 and 75 C, preferably between 30 and C, the substrate is dried, then it is padded with a solution of a reducing sugar in an aqueous alkali, preferably an absorption rate between 90 and 120%, and then heated

  indicated above to carry out the reduction of

  rant. The printing can be carried out analogously to the paddry-pad-steam process, by printing the substrate with a printing paste in place of the

  padding with a dye bath.

  When the substrate is a cellulosic mixture

  se-polyester, the pad process is preferably used.

  dry-thermosol-pad-steam (padding-drying-thermo-

  solage-pad-steam). A suitable disperse dye is added to the dyebath together with the sulfur dye, followed by thermosol treatment after the drying step. If not,

  this process is identical to the pad-dry-pad-steam process.

  The heat treatment indicated above is preferably carried out with steam, more preferably in the unpressurized vaporizer of a conventional scarf / vaporizer in which the substrate is under a pressure only slightly high for

  avoid the entry of air into the vaporizer, usually

  up to about 1.15 atmosphere. The heating must be carried out for a time that is long enough to carry out the complete reduction of the dye

  on the substrate at the temperature used but sufficient

  short enough to allow continuous operation in the particular equipment used. The heating time is preferably between about 20 and seconds, more preferably between 40 and 110

  seconds, especially between 40 and 75 seconds.

  Dyeing can be carried out using conventional dyeing equipment continuously. As is known to specialists, such equipment consists of one or more scarves for continuously applying a dye bath and a reducing agent on the substrate, and a non-pressurized zone, for example a vaporizer, in which the substrate so

  The treated is then heated to reduce the dye.

  Printing can also be performed using conventional printing equipment together with a non-pressurized vaporizer, preferably a vaporizer

  particularly suitable for the vaporization of impres-

  and in which the printed portion of the substrate

  is not in contact with the cylinders.

  An advantage of the present invention is that dyeing or printing with a sulfur dye can be carried out using a reducing sugar, which is not a problem from an ecological point of view, and in a conventional non-pressurized apparatus . After applying the dye bath or printing paste to the substrate and reducing the sulfur dye, it is generally advantageous to subject the thus treated substrate to oxidation.

  to improve the solidities of dyeing or

  pressure. Although some dyes and prints may be sufficiently oxidized by

  water normally made after dyeing, preferably

  re perform a chemical oxidation. For this purpose, hydrogen peroxide or a sodium bromate / catalyst system may be used. The oxidation conditions are those usually used and vary depending on the equipment used and the unwinding speed of the substrate. In general, when sodium bromate and vanadium pentoxide are used as the catalyst, the amount of oxidizing agent is usually

  between 3.75 and 11.25 g / l, the pH is preferably

  between 3 and 4.5 and the temperature is usually

  45 to 85.degree. C., more preferably 49.degree. to 820.degree. C., especially 60 to 75.degree. C. In a hydrogen peroxide system, about 1 to about 1 g / l of oxygenated water is used at a pH in the range and 7.5, preferably between 5.5 and 6, and at a temperature between 35 and 60 C. Acetic acid or formic acid is usually used to obtain the required pH. The substrate is subjected to the action of the aqueous oxidation bath for about 5 to 70 seconds,

  usually for 10 to 40 seconds.

  The dyebath is prepared preferably

  by mixing an aqueous dispersion of the sulfur dye, previously prepared, with an additional quantity of water and, when the process is used,

  pad-steam, with a reducing sugar and an alkali.

  The preferred reducing sugars include carbohydrates or combinations thereof which reduce Fehling's liquor, for example aldopentoses such as L-arabinose, D-ribose and D-xylose, hexoses such as D-glucose, D-ribose and D-xylose. fructose, D-mannose and Dgalactose, and disaccharides such

  than cellobiose, lactose and maltose. Some

  such as corn syrup, invert sugar and molasses containing a reducing sugar, can also be used as well as dextrose

  prepared in situ from sucrose. Sugar

  The preferred conductor is D-glucose.

  The amount of reducing sugar should be sufficient to reduce the sulfur dye when the substrate treated with the dye or printed bath is heated as described above. The reducing sugar is preferably used in an amount of from 30 to 135 grams per liter, more preferably from to 120 grams per liter, whether applied from the dyebath or separately from an aqueous alkaline solution. Larger amounts can also be used, but in general this does not improve the quality of the dye. The reducing sugar is preferably the only reducing agent added to the bath of

  sulfur dye or aqueous alkaline solution.

  The alkali may be any alkali known for the reduction of sulfur dyes, especially sodium hydroxide or carbonate or

  potassium, especially sodium hydroxide.

  The alkali is preferably used in an amount of from about 8 to 70 grams, more preferably from 10 to 35 grams per liter of separately applied aqueous dye bath or bath containing the sugar.

  reducing agent so that the pH is at least 10, preferably

10.5.

  The dyebath may also contain a wetting agent to improve bath penetration into the substrate during application. The wetting agent used is not critical. Anionic compounds are preferred, especially the sodium salt of 2-ethylhexanol phosphate. The appropriate amount of wetting agent is between 1 and

g per liter of dye bath.

  The aqueous dye bath used for the pad-dry-pad-steam process preferably contains an agent that inhibits dye migration during the drying step. Such products are known and can be synthetic products, for example based on polyacrylate, or natural, for example based on alginates.

  When the dye is applied by printing

  In this process, customary thickeners are used to prepare a printing paste having the desired properties. The aqueous dispersion of the sulfur dye used for the preparation of the dye bath or printing paste is advantageously a mixture of a sulfur dye, in the oxidized state, in water containing a sufficient amount of dispersing agent for dispersing the dye in water. It suits

  to use, as a starting material, the filter cake

  of the oxidized sulfur dye as usually obtained by thionation, dilution of thionation mass in water, oxidation, filtration and

washing the filter cake.

  Oxidation (aeration) of the filter cake

  is preferably carried out until the

  reaction mixture is free of mineral sulfides.

  This point is reached when the reduction equivalent of the reaction mixture is 0, as determined by potentiometric titration with an O 2N solution of

ammonium cuprosulfate.

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  It is preferable that the poly-

  The sulphides in the dye suspension are also very low, more preferably 0. Aeration of the suspension at a reduction equivalent of 0 can also be used to reduce the polysulfide content to the desired level. It is appropriate to carry out a ventilation test up to a reduction potential of 0 and

  to then examine the polysulfide content of the

  Duit. 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. When the polysulfide content is too high, the particular dye precipitation step is preferably modified, prior to aeration, to include a treatment with an amount of sodium sulfite and / or sodium nitrite effective to lower content

in polysulfides.

  Aeration is preferably discontinued on

  as soon as possible after the elimination of

  res. It has been found that overoxidation can cause the formation of crosslinked polycondensation products that

  it can not be easily reduced with glucose / al-

  cali and which, therefore, are not desired in the dyeing and printing process of the present invention. It is advantageous to determine the particle size of the suspension, for example using a particle size analyzer, and to interrupt the aeration before it occurs.

  increasing the particle size.

  Preferably, the filter cake is

  washed to remove the mineral salts that are usually

  associated with such thionation products. The washing is advantageously carried out until the mineral sulphate content, relative to the weight of the

  solids in the filter cake, either

  less than 2%, preferably less than 0.6% by weight.

  More preferably, the washing is carried out until the content of all the inorganic salts is less than 2%, especially less than 0.6% by weight. An advantageous way to determine whether the salt content has been reduced to the desired level is to determine the electrical conductivity of the wash water, for example using a Chemtrix Type 700 conductivity meter. this method, the washing is preferably continued until the conductivity of the water after washing is not 140 micromhos / cm, more preferably not 60 micromhos / cm

  greater than the conductivity of the water before washing.

  The filter cake is combined with additional water in such an amount that the dye content of the resulting mixture is between about 8 and 40%, preferably between 10 and 35%, more preferably between 15 and 35% by weight. . The particular dispersing agents used to prepare the dye dispersions are not critical. Good results are obtained using various agents

  anionic or nonionic surfactants and their

  for example sodium lignin sulphonates sold under the trade names Vanisperse CB, ReaxR 85

  A and Reaxe PC 946, the sodium salts of alkyl-

  naphthalenesulphonic compounds (eg Tamol a SN) and

  mixtures of glycols. The amount of dispersing agent

  Depending on the known methods, this will depend to a certain extent on the particular dye to be dispersed. Good results are obtained using from 5 to 20% dispersing agent relative to the total weight of the dispersion. Other additives, for example a biocide, may also be added to the dispersion. The components of the dispersion are

  preferably added with stirring and the mixture

  sultant is crushed until a good

  wherein the particles of the disperse sulfur dye have a size of between 0.1 and microns, more preferably between 0.3 and 1.5 microns, measured using a Microtrac R Particle-Size

Analyzer (Leeds-Northrup).

  The amount of the dye dispersion used to prepare the dyebath or printing paste depends on the dye content of the

  dispersion and intensity of the desired shade.

  Generally, per liter of dye bath, we add

  from about 15 to 165 grams of dye dispersion.

  The process of the invention is especially

  suitable for dyeing textile materials containing

  cellulose with sulfur dyes requiring a relatively low reduction potential

  weak for their solubilization, for example the colo-

  Oxidized sulfur rays which can be reduced within 60 seconds at 102 ° C with glucose and sodium hydroxide at the concentrations previously specified. Examples of such dyes are

  cite the following: C.I. Sulfur Black 1 (Const.

  NOT . 53185), C.I. Sulfur Black 2 (Const., No. 53195),

  C.I. Sulfur Black 18, C.I. Sulfur Green 2 (Const.

  NO. 53571), C.I. Sulfur Green 36 (as described in Example 1 of US Pat. No. 3,338,918), C.I. Sulfur

  Blue 7 (Const 53440), C.I. Sulfur Blue 13 (Const.

  NOT . 53450), C.I. Sulfur Blue 43 (Const.No. 53630), C.I. Sulfur Red 10 (Const.No. 53288), C.I. Sulfur Red

  14, C.I. Sulfur Brown 37 and C.I. Sulfur Yellow 22.

  - Since the dyes are in oxidized form insoluble in water when they are

  apply to the substrate according to the process of the invention.

  they are not substantive for cellulosic fibers and do not rise immediately to

  but tend to be evenly distributed

  on the substrate before being made substantive by heating, which avoids problems such as the difference in edge-center and queuing. The following examples illustrate the present invention without in any way limiting its scope. In these examples, the parts and percentages are by weight and the temperatures are indicated in degrees Celsius.

EXAMPLE 1

  A mixture of 250 parts of a green leuco dye thionation mass of the green sulfur dye prepared as described in Example 1 of US Pat. No. 3,338,918 and 488 parts of water were aerated for 2 hours at 88 ° C. cooled to 45 and filtered. The filter cake is washed with tap water having a conductivity of 65 micromhos / cm until the wash water is clear and has a conductivity of micromhos / cm. We get 55 parts of a cake of

  filtration having a solids content of 43.2%.

  In a laboratory ball mill, we introduce:

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  13.9 parts of the filter cake of the sulfur dye prepared above, 2.4 parts of sodium lignin sulphonate (brand Vanisperse CB),

  1.5 parts of the sodium salt of an alkylnaphthalic acid

  lenesulphonic (Tamol SN brand), 0.6 part of a mixture of diethylene glycol and 2,4,7,9-tetramethyl-5-decyne-4,6-diol (trade mark Surfynol 104 E), 0.1 part of sodium salt of chlorinated bis-phenol (Givgard G4-40 brand) and

11.0 parts of water.

  The resulting mixture is stirred and ground

  for 24 hours giving 28.5 parts of a

  persion of the sulfur dye prepared above.

  5 parts of the dye dispersion prepared above and 50 parts of water are stirred until a homogeneous mixture is obtained. 12 parts of glucose, 12 parts of aqueous sodium hydroxide (50%), 10 parts of water and 0.5 part of the sodium salt of ethylhexanol phosphate are added to this mixture. The mixture obtained is stirred for 5 minutes and diluted

  then to 133 parts by adding additional water

  silent. The dye bath prepared above is heated to 430 and poured into the dyeing vessel

  an Aztec laboratory vaporizer / vaporizer

  unpressurized. A cotton twill, pre-bleached, is padded through the dyebath at an absorption rate of 70-80%, then vaporized for 60

  seconds at 101-103 and rinsed with hot tap water.

  A solution for the oxidation is prepared by adding 7.5 g of hydrogen peroxide (35% solution) and 7.5 g of glacial acetic acid to sufficient water to obtain a total volume of 1 liter. This solution is heated to 60, the dyed substrate is added higher, and the solution is stirred for 30 seconds. The substrate is then rinsed with hot tap water until it is clean and dried. We obtain

a solid green dye.

EXAMPLE 2

  At 402 parts of a gross mass of thiona-

  C.I. Sulfur Blue 13 (C.I. Const.

  Born. 53450), 1354 parts of water are added. The resulting mixture is aerated for 11 hours at 900 until all the sulfides are completely oxidized (reduction potential - 0). The pH of the slurry obtained at pH 5.6 was lowered by addition of 7.5 parts of sulfuric acid (70%) and filtered. The filter cake is washed with tap water having a conductivity of 65 micromhos / cm until the conductivity of the wash water is less than 110 micromhos / cm, which gives 285 parts of a cake. filtering having

  a solids content of 27.5%.

  In a ball mill, there are introduced: 203 parts of the sulfur dye filter cake prepared above, parts of sodium lignin sulphonate (Vanisperse CB),

  12 parts of the sodium salt of an alkylnaphthalene

  nesulfonic acid (Tamol SN), 1 part of 6-acetoxy-2,4-dimethyl-M-dioxane (brand GIV-GARD DXN) and,

63 parts of water.

  the mixture obtained is milled for 24 hours with beads and then for 24 hours with sand until a particle size of between 1 and 5 microns is obtained and then separated.

sand.

  An aqueous dye bath containing

  For each 1000 parts of water, 30 parts of the dye paste prepared as described above and 15 parts of an alginate-type migration inhibitor are used. This bath is fouled with a mercerised and bleached cotton twill, at an absorption rate of between 60 and 60%, subjected to pre-drying in an infra-red dryer (Forstoria) to remove 30% of moisture and dried thoroughly in an 82-99 oven. Using a scarf / vaporizer from Greenville Steel Textile Machinery Corp. (Serial No. 39377), the substrate is padded at room temperature to a 100% absorption rate with an aqueous bath containing, per 1000 parts of water, 60 parts of aqueous sodium hydroxide (50%). and 120 parts of dextrose and is sprayed for 60 seconds at 103

  in the non-pressurized vaporizer of said scarf / vapo-

  riseur. The substrate is then washed at room temperature

  with water and subjected to oxidation-

  degreasing combined for 30 seconds at 65 in an aqueous bath containing, per 1000 parts of water, 7.5 parts of acetic acid (at 56%), 7.5 parts of sodium bromate / vanadium pentoxide and 3.75 parts of a commercial nonionic degreasing agent (Sodyeco R Scour TR). After washing with water at -700 and then with water at room temperature, a solid blue dye is obtained

  characterized by excellent gloss.

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Claims (13)

  1. Method of dyeing or printing   substrates containing cellulosic fibers, characterized rised in that   a) a continuous dispatcher is applied to the substrate   aqueous solution of a sulfur dye and, simultaneously,   afterwards, a reducing sugar is applied together with an alkali, and then b) the substrate is treated with heat to perform   reducing the sulfur dye on the substrate.   2. A method according to claim 1, characterized in that the substrate is heated to a temperature between 98 and 105 C for a time sufficient to effect the complete reduction of sulfur dye.   3. A process according to claim 1 or 2,   characterized in that the reduction of   sulfur content by heating the substrate in a unpressurized riser.   4. A process according to any one of   Claims 1 to 3, characterized in that the colorant   sulfur is applied to the substrate by padding.   5. A method according to any one of   Claims 1 to 4, characterized in that it applies   on the substrate an aqueous dye bath containing the   sulfur dye, a reducing sugar and an alkali.   6. A method according to any one of   Claims 1 to 4, characterized in that it applies   on the substrate an aqueous dye bath containing the sulfur dye and then applying to the substrate a solution of a reducing sugar in a aqueous alkali.   7. A method according to any one of   Claims 1 to 6, characterized in that the sugar reducer is glucose.   8. A process according to any one of   Claims 1 to 7, characterized in that the colorant   Sulfur is free of mineral sulfides.   9. a method according to any one of   Claims 1 to 8, characterized in that the colorant   sulfur is selected from C.I. Sulfur dyes   Black 1, 2 and 18, C.I. Sulfur Green 2 and 36, C.I.   Sulfur Blue 7, 13 and 43, C.I. Sulfur Red 10 and 14, C.I.   Sulfur Brown 37 and C.I. Sulfur Yellow 22.   10. A process according to claim 5 or 6, characterized in that the reducing sugar is   the only reducing agent added to the dye bath.   11. A textile substrate containing cellulosic fibers, characterized in that it has been dyed   according to the method specified in any one of the 1 to 10.   12. A padding bath to use in a   pad-steam process according to claim 5 or using   in a pad-dry-pad-steam process according to the   cation 6, characterized in that it contains from 30 to   g / l of reducing sugar and 8 to 70 g / l of alkali.   13. A padding bath according to claim   cation 12, characterized in that it contains from 50 to 90   g / l of reducing sugar and 10 to 35 g / l of alkali.