US2518153A - Dyeing of cellulose esters with reduced vat dyes in alcoholic solution - Google Patents

Description

i atented Aug. i950 .1

1DYEING OF CELLULOSE ESTERS WITH RE-i DUCED VAT DYES IN ALCOHOLIC SOLU- TION Edwin E. Laughlin, West Newton, Mass., and

1 Raymond W. Foulk, Bridgeport, N. J assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application J anuary7, 1948,

Serial No. 1,066

This invention relates to the dyeingof cellulose esters, and moreparticularly to the dyeing of fabrics composed of or containing cellulose esters, such as cellulose acetate, with vat dyes;

Vat dyes are used extensively in the dyeing of cellulose fibers such as cotton, regenerated cellulose's, etc., when it-is desired to impart to those fibers colors having maximum fastness properties, especially fastness to light, weather and laundering. Because ,the vat dyes are usually applied to cellulose material from solutions having relatively high alkalinity, they have not found general application in the dyeing of cellulose acetate or other esters'because the'highly alkaline vat causes saponification of the cellulose ester with the result that the desirable characteristics and advantages which the. cellulose acetate fibers possess over the viscose rayons is lost.

Cellulose acetate 1 and, other esters .are customarily dyed with acetate colors, which, although they exhibit moderate to vfairlygood light fastness, do not exhibit the fastness to Washing, especially repeated washing or laundering, that is desired, and some of the dyes of this class are sensitive to gas fume fading and undergo drastic.

changes in colorwhen the dyed material is exposed to fumes of burning natural gas, oxides of nitrogen and other gases norm-ally present in the atmosphere, particularly in highly industrialized communities.

The fact that it has heretofore been impossible to dye cellulose acetatereadily in a range of colors which may be characterized as,fast in the same sense that fast colors are easily obtainable on other textile fibers, such as cotton, regenerated celluloses, silk and wool, has materiallyretarded 2 Claims. (01. 8-36) the more-extensiveuse of jcellulose, acetate as-a textile material. A continuingeffort is being made to provide a commercially feasible-process for dyeing cellulose acetate withdyeswhich have.

better fastness properties than thosethat are now available for general use on thatfiber, and-with a class of colors tha 3mi. et ii ra e, o

shades. H I v Previous attempts have beenmade to, dye cellulose acetate with reduced vat'd'y'es'lfrom the usual vat'e'm ploye'd in the dyeing of cotton'andregenerated celluloses, but it has been found that, if

the time of dyeing is"co'mparatively short, little or no color is imparted to the fiber, while-,fi'f a longer time of contact is employed,'-the alkaline dye liquor causesf'saponification of the cellulose ester, resultingin the formation of somecenmese for which the dye'liquorhasgreaterisubstantivity' t an r the ell lo e ace a th reby causing very uneven and undesirable dyeings. Another proposal has been to replace the strongv alkalies normally used in vat dyeings by Weak alkalies, However, such a process limits'the number of vat dyes applicable and actually does not completely prevent saponification.

It is an object of this invention to provide'a process for dyeing cellulose acetate and related esters with vat dyes. A further object of the invention is to provide a commercially feasible process for the dyeing of cellulose acetate with vat dyes Without damage to the acetate and With-' out causing any material amount of saponification of the same during the dyeing process. Another object of the invention is toprovide a process for dyeing. celluloseacetate with all types of vat dyes. A stillfurther object of the invention is to permit vat dyeings of cellulose acetate by a continuous process without saponification so that all the excellent esthetic and physical properties of this valuable, fiber are retained. Further objects will appear'hereinafter.

We havefound that the above objects maybe very effectively accomplished by maintaining a relatively high concentration of alcohol in the alkaline hydrosulfite vat ofthe vat dye together with a wetting agent, a dispersing agent, and an additional type of adjuvant which We call a vatstabilizing agent consisting of diethylene glycol, thiodiethylene glycol, or glycerine. The cellulose ester absorbs in this manner a sufficient amount of the dye liquor to impart the desired color thereto, and if the alkalinity of the solution in the fiber is quickly lowered to a pointwhere saponification of the fiber does not occur, very satisfactory dyeings with the vat dye can b attained. By this method, we have found-that the cellulose ester fiber itself is not harmed or degraded and the dyed material possesses the excellent fastness properties usually associated with this type of dye when applied to cotton or regenerated cellulose.

The alcohol which acts as a swelling agent on the cellulose ester fiber permits the leuco'vat dye to quickly penetrate into the fiber itself. For the purpose of our invention We have found that'alcohols having up to and including four carbon atoms, such as tertiary-butyl, propyl, isopropyl ncentration used,

alcohol should be fully miscible with Water at the V t it is necessary to employ in the padding solution agents which will facilitate uniform wetting and swelling of the cellulose esters. In addition the leuco vat color must either be com pletely in solution or in a state of highly dispersed colloidal solution for successful operation. The use of dispersing agents in aqueous systems has ng been used. We find that their use is helpful in our process, but the dispersing agents for use in the aqueous-alcohol media areby them-- selves not satisfactory when the final alcohol content in the solution is 30% to 60% which is within the scope of our invention. At such concentrations of alcohol the leuco vat color quickly agglomerates and is precipitated. We have found the pad-bath. For the purpose of our invention this time may range generally from four to ten seconds.

After padding through the aqueous alcohol solution, the fabric is squeezed sufficiently to prevent run-back of color on the fabric as it is carried over and under the guide rolls. We have found that with cellulose acetate the liquor retention by the fabric, or pick-up as it is called that certain agents which we call vat-stabilizing agents can be used to enable the vat leuco tore main either dissolved or highly dispersed in the presence of such a great quantity of the alcohol.

The vat-stabilizing agents which we have found effective are: polyhydroxy alkyl compounds such as diethylene glycol, tliiodiethyl-ene glycol, or glycerine.

Any of the wetting agents usually employed in the dyeing or treating of textile fibers be used in this process, such as the sodium salt. of the. sulfates of straight chain aliphatic alcohols containing eight or more carbon atoms, the sodium salts of the allayl naphthalene sulfonic acids such as isopropylatecl naphthalene sulionic' acid, the sodium salts of the sulfonates of higher molecular weight aliphatic hydrocarbons, the sodium salts of sulfonated tetralin, etc.

The dispersing agents may be any of those suitablefor dispersing finely divided solids in allal-ine solutions, such as sodium ligno:-sullfonates, the naphthalene beta-sulionic acid formaldehyde condensation products such as produced by the process of United States Patent 1,336,759, the triamine bases such as the trialkyl trimeth-ylene tri amines, etc;

The Wetting agent is. preferably employed in the dye bath in an amount ranging from 0.1 to 4 ounces: r gallon. The dispersing agent and the glycerine or glycois may each be used in an amount ranging from 0 .25 to 4 ounces per gallonof dye solution.

In practice, the material to be dyed maybe padded inthe alkaline hydrosulfite vat of" the vat. dye containing the alcohol, the swelling agent,.the dispersing agent, and the vat-stabilizing agent. The fabric is then passed immediately into a bathof lower alkalinity such as water, or, preferably,

a soda ash developmentbath of the type'described in United States Patent 2,318,133. The cellulose ester is then rinsed, the dye oxidized, and the material dried.

For satisfactory operation as acontinuous process it is necessary that the temperature be sufiiciently high to insure prompt swelling oi the cellulose ester, but not so high that saponification of the fiber occurs in any substantial amount, or that much of the alcohol isv lost by vaporization. We have found that in the padding operation temperatures in the range of 110 F. to- 150 F. are operable, but the preferred range is 115 to 140 F. Below 110 F'. swelling of the fiber is slow, while above 150 F. saponifi'cation takes place. The time in the pad-bath mustv be sufiicient to allow good swelling, but not so great that saponification of the fabric commences. The im-- mersion time depends on the alcohol used, the

alcohol concentration and the temperature of in the trade, should be in the range of 40% to based on the weight of the cloth, but the preferred range is 50% to 70%.

The following examples are given to illustrate the invention. In these examples the ingredients added are based on ounces by weight per gallon of dye solution.

Example 1 A-two ounce per gallon pad liquor of Ponsol Golden Orange RRT (Color Index 1098) was prepared as follows:

2.0 oz. Ponsol Golden Orange RRT paste (1 color solids) 2.0 oz. potassium hydroxide 2.5 oz. sodium hyd-rosulfite 20oz. sodium hydrocarbon sulfonate wetting agent (product of Example III of U. S. P. 2,360,027.)

1.0 oz. naphthalene sulfonic' acid-formaldehyde condensation product 215 oz. diethylene glycol Reduction was carried out. for 1 5 minutes at 140 F. in 3.5 pints of water. The volume was made up to 0.5 gallon: with Water and then 0.5 gallon of ethyl alcohol. and 015 oz. of. triethyl triniethylenetria-mine were added- Cellulose acetate satin was padded with this liquor at 1 20 F1 for six seconds and at 55% pick-up, and was then immediately led intoan aqueous soda ash development bath for 60' secondsv at F. which contained:

- 1.00 oz./gal. soda ash 0.08 oz./ga1. potassium hydroxide 0.25 oz/gal. sodiumhydrosulfite 4.00 oz./ gal. common salt The fabric was then oxidized by passing through a bathcontaining:

0.13 oz./gal. sodium dischromate 0.40 oz./ gal. acetic acid 28% Following this, the tabric was rinsed, soaped,

rinsed, and dried.

' The resultant fabric was uniformly dyed a pleasing reddish-orange of excellent fastness to light, crocking, perspiration and repeated laundering. Furthermore, the resultant fabric had not been damaged nor saponified. The class of dyes known as'direct dyes will dye viscose rayon readily and leave cellulose acetate unstained. The most sensitive indication of saponification of cellulose acetate consists in subjecting the material to the action of a direct dye bath. If even a trace of surface sap'onification has occurred, too small to be determined b the customary acetone solubility or hydrolysis tests, the material will nevertheless be stained by' the direct dye. In the above example, the material was'cross-dyed with Pontamine Sky Blue 63X, Color Index 518, and left completely unstained, indicating that there had been no trace ofsaponification.

.fGolden Orange RRT2(Co1or Index=1098l pared'asfollowsa 0.5" oz. Ponsol Golden "ma-aw pastln'a color sol1ds) I i 1.5 oz. potassium hydroxide I 2.0 "02. "sodium hydrocarbon "Susann wetting agent (product of Example 111 of U." SJ P. 2,366,027)

1.0 oz. naphthalene sulfonic acid-formaldehyde condensation product 2.5 oz. diethylene glycol Reduction was carried out for minutes at 140 F. in 3.5 pints of water. The volume was made up to 0.5 gallon of water, and then 0.5 gallon of ethyl alcohol and 0.5 oz. of triethyl trimethylene triamine were added.

The dyeing of the cellulose acetate satin was carried out as in Example 1 to give equally satisfactory results.

Example 3 A four ounce per gallon pad liquor of Ponsol Golder Orange RRT (Color Index 1098) was prepared as follows:

4.0 oz. Ponsol Golden Orange RRT paste (11% color solids) 2.0 oz. potassium hydroxide 2.5 oz. sodium hydrosulfite 2.0 oz. sodium hydrocarbon sulfate wetting agent (product of Example III of U. S. P. 2,366,027)

1.0 oz. naphthalene sulfonic acid-formaldehyde condensation product 2.5 oz. diethylene glycol Alkaline reduction was carried out for 15 minutes at 140 F. in 3.5 pints of water. The volume was made up to 0.5 gallon of water and 0.5 gallon of ethyl alcohol and 0.5 oz. of triethyl trimethylene tri-amine were added.

The cellulose acetate satin was then dyed and finished in the manner described in Example 1 above to give a dyeing which was equally satisfactory.

Thiodiethylene glycol and glycerine maybe substituted in the above Examples 1, 2, and 3 for diethylene glycol and at the same concentration to give equivalent effectiveness as vat stabilizing agents.

Example 4 The following vat colors were applied to cellulose acetate satin by the process similar to that described in Examples 1, 2, and 3 with equivalent satisfying results:

Sulfanthrene Yellow R supra -C. I. #1170 Sulfanthrene Orange R paste C. I. #1217 Vat dye of Example 3 of U. S. P. 1,234,171 Sulfanthrene Red 33 paste C. I. #1212 Sulfanthrene Blue 2BD paste C. I. #1184 Sulfanthrene Blue GR paste C. I. 969 Sulfanthrene Navy Blue MR paste C. I. #1183 Vat dye of Example 1 of U. S. P. 1,090,621 Ponsol YellowG double paste C. I. #1118 Ponsol Yellow AR double paste C. I. #1132 Ponsol Golden Orange G paste C. I. #1096 Ponsol Brown AG double paste C. I. #1152 Ponsol Brown AR double paste C. I. #1151 Ponsol Brown BB paste C. I. #1120 Vat dye of Example 3 of U. S. P. 1,329,435

Ponsol Red BN double paste C. I. #1162 Ponsol Violet AR double paste C. I. #1135 P011 01 Brilliant Violet. 3B paste........... I. #1105 Ponsol Violet 2RD paste C. I. #1104 Ponsol Red Violet RRNX paste C I. #1161 Ponsol Blue BF double paste" C. 1.}?1113 Ponsol Blue GD double paste; C'."I.'#11'12 Ponsol Blue BCS- double paste LG. I. #1114 PonsolBrilliant Blue R paste C. I. til-106 Bonsol Blue 3G paste (;3;. I 1109 Vat dye of-Example 1 of U. S. 1,761,624 -Ponsol-Dark Blue BR paste C. I.,# 1099 n el de re n dQ 1 s ee---- 11354 .9 Vat dye of Example 2 of U. S. P. 1,596,528 Ponsol Olive AR double paste C. I. #1150 Vat dye of U. S. P. 995,396

Ponsol Black BA double paste C. I. #1102 The advantages of our invention are obvious. We are enabled to dye cellulose ester fabrics with the full range of vat colors without the attendant disadvantages of saponification of the fiber. The result leads to a cellulose ester fabric dyed with the fastest line of dyestuff known today. The vat colors also may'be applied in fairly heavy shades, and the deficiencies of poor fastness to light, rubbing, perspiration, washing, especially repeated washing and laundering and gas fume fading are overcome by our process. An especial advantage is the fact that the cellulose ester fabric after vat dyeing by our process shows no adverse effects or deterioration but fully retains all of the esthetic properties of pleasing handle and outstanding draping qualities inherent in this type of fabric. A further advantage of our invention is that due to the rapidity with which the process may be performed it is readily applicable to continuous process.

We claim:

1. A process of dyeing cellulose esters with vat dyes, which comprises padding thecellulose ester material for a period no more than 10 seconds with an aqueous alkaline solution of a reduced vat dye containing in the solution from 30% to 60% of alcohol, and, for each gallon of dye liquor, alkali in an amount equivalent to no more than 2.0 ounces of potassium hydroxide, from 0.1 to 4 ounces of a wetting agent, 0.25 to 4 ounces of a dispersing agent and from 0.25 to 4 ounces of a stabilizing agent of the group consisting of diethylene glycol, thiodiethylene glycol and glycerine, maintaining the pad bath temperature between 110 F. and F. and, immediately after padding, passing the material into an aqueous solution having an alkalinity below that at which saponification of the cellulose ester takes place, and oxidizing the reduced vat dye on the material.

2. In a continuous process for dyeing cellulose acetate fibers, the steps which comprise padding the fibers for a period no more than 10 seconds with an aqueou alkaline solution of the reduced vat dye containing in the solution from 30% to 60% of alcohol, and, for each gallon of dye liquor, alkali in an amount equivalent to no more than 2.0 ounces of potassium hydroxide, from 0.1 to 4 ounces of a wetting agent, 0.25 to 4 ounces of a dispersing agent and from 0.25 to 4 ounces of a stabilizing agent of the group consisting of diethylene glycol, thiodiethylene glycol and glycerine, maintaining the pad bath temperature between 110 F. and 150 F. and, immediately after padding, passing the impregnated fibers into a solution having an alkalinity below that at which saponification of the cellulose acetate takes place, and thereafter oxidizing the reduced vat dye on the fiber.

' EDWIN R. LAUGHLIN. RAYMOND W. FOULK.

(References an following page) 7 8 REFERENCES CITED H FOREIGN-PATENTS The following references are of recotdjlrr'the Number Country Date fiIe. of this patent: 47936182 Great Britain Feb; 14,1938 e 847,107 France June 26, 1939 N b UNHEDNSTATES PA'IENTSD t 7 583,349 Great Britain Y Dec. 16, 1946 um er am'e a e 1,398,357 Briggs Nov. 29,1921 OTHER REFERENCES 1,968,856 Rivat Aug. '7, 1934 Amer. Dye. Rep. forMay 21., 1945, page P212;

2 ,067,926 Kern Jan. 19", 193-7 R yon Textile Monthly for March 1947, page 2,090,511 Crossley AugxlT, 193-7 10 100 (155).; I

Claims (1)

1. A PROCESS OF DYEING CELLULOSE ESTERS WITH VAT DYES, WHICH COMPRISES PADDING THE CELLULOSE ESTER MATERIAL FOR A PERIOD NO MORE THAN 10 SECONDS WITH AN AQUEOUS ALKALINE SOLUTION OF A REDUCED VAT DYE CONTAINING IN THE SOLUTION FROM 30% TO 60% OF ALCOHOL, AND, FOR EACH GALLON OF DYE LIQUOR, ALKALI IN AN AMOUNT EQUIVALENT TO NO MORE THAN 2.0 OUNCES OF POTASIUM HYDROXIDE, FROM 0.1 TO 4 OUNCES OF A WETTING AGENT, 0.25 TO 4 OUNCES OF A DISPERSING AGENT AND FROM 0.25 TO 4 OUNCES OF A STABILIZING AGENT OF THE GROUP CONSISTING OF DIETHYLENE GLYCOL, THIODIETHYLENE GLYCOL AND GLYCERINE, MAINTAINING THE PAD BATH TEMPERATURE BETWEEN 110*F. AND 150*F. AND IMMEIATELY AFTER PADDING, PASSING THE MATERIAL INTO AN AQUEOUS SOLUTION HAVING AN ALKALINITY BELOW THAT AT WHICH SAPONIFICATION OF THE CELLULOSE ESTER TAKES PLACE, AND OXIDIZING THE REDUCED VAT DYE ON THE MATERIAL.