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edited bv the trading post MARCIA C. BONNEA; SUNY-Cortland Cortland. NY 13045 The Chemistry of Fabric Reactive Dyes Marcia C. Bonneau SUNY-Cortland Cortland, NY 13045 Developing an activity that can relate chemistry con- cepts to that which is interesting and relevant to high school students is a challenging one, but tie dyeing is one of those phenomena that has been found to be very popular and successful in many high schools. Even though it ap- pears to be an "arts and crafts" project, the activity can be justified in a high school chemistry course if the chemistry involved in tie dyeing can be related to the organic chemis- try unit. The objective of this article is to describe the method of application and the chemistry of the most popu- lar fiber reactive dyes, roci ion' MX dyes, used in tie dye- ing. The Dyes Procion MX is the commercial name for dichlorotriazine dyes. They are the most reactive and versatile of the fiber reactive dyes, which means that the dye molecule actually reacts with fabric molecules. These dyes can be used on cotton, silk, wool, rayon, linen, paper, and wood but not on Figure 1. Procion MX (dichlorotriazine). synthetic fibers. The reactive group is shown below in Fig- ure 1 (I). The "D represents the color-forming or chromophore part of the molecule attached to the reactive group. Exam- ples of three of these common dyes are given in Figure 2 (21. Mixing the Dyes Caution: The dyes are sold in the form of a powder and are considered to be nontoxic. Common sense should be used in handline anv chemical. however. Proloneed inhalation of the -, d w powder ran muw sn dllcwc rtatllun in somc pwplc A dust mark and ruhher gloves should be worn to mix the rhcmicnls, and mixing should he done in a hood. Approximately 10-20 mL of dye may be mixed with 250 mL of warm water or urea solution. Hot water up to 120' F may be used to dissolve the less soluble dyes, but the dye solution should be cold when the alkali is present to pre- vent premature reaction with water (3). Urea solution, made by mixing 125 mL of urea in a liter of water (2 cups per gallon), is optional. It helps to dissolve the less soluble 'Procion is a trade mark of Zeneca Colours formerly ICI (Imperial Chemical Industries) a. Procion Brilliant Yellow M-6G (ICI)('CI Reactive Yellow 1) b. Procion Brilliant Red M-2B (ICI)(CI Reactive Red 1) c. Procion Brilliant Blue M-R (ICI)(CI Reactive Blue 4) Figure 2. Three common dichlorotriazine dyes. 'CI refers to the Colour Index. Published jointly by the American As- sociation of Textile Chemists and Colorists, Research Triangle Park, NC, and The Society of Dyers and Colourists, Bradford, England. dyes and, being hydrophilic, keeps the fabric damp during the processing time. Urea also "drives" the dye into the fabric during the heat-fixing process so that the colors come out brighter. Once the dye powders are mixed with water or urea solution, they have a shelf-life of four to five days. Liquid fiber reactive dyes by Createx Colors have a shelf-life of two years and may he used as an alternative to the powdered dye. Some sources for fiber reactive dyes are listed at the end of the article. The Application of the Dye Refore dye is ndded to the f:ihric, the fabric is washed in a mild drrrrarnt or rh(, commtwi.ll product called Ssn- thrapol SP t{remove sizing and other-chemicals that may interfere with the dve. Plastic doves, aprons, and safety goggles must be wain, and tnblrs should 116: covtwd with plastic. 'l'hc fal~ric is sw~kc,d in a sodium carbonate soda ish) solution for at least 15 min. The solution is made by adding 60 mL of sodium carbonate per liter of water (one cup per gallon). The sodium carbonate is used to "activate" or weaken the bond between the "H" and the "0" on the "OH" (hydroxyl) group of the cellulose molecule. Cellulose is ionized under these alkaline conditions. The solution of soda ash has a pH of 10.6 and also will neutralize the HC1 formed during the reaction (4). The fabric is wrung out to remove excess solution and folded, twisted, and tied. The methods of folding and tying 724 Journal of Chemical Education

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Page 1: The Chemistry of Fabric Reactive Dyes - WikispacesPaper.pdf · The Chemistry of Fabric Reactive Dyes Marcia C. Bonneau SUNY-Cortland Cortland, NY 13045 Developing an activity that

edited bv

the trading post MARCIA C. BONNEA;

SUNY-Cortland Cortland. NY 13045

The Chemistry of Fabric Reactive Dyes

Marcia C. Bonneau SUNY-Cortland Cortland, NY 13045

Developing a n activity that can relate chemistry con- cepts to tha t which is interesting and relevant to high school students is a challenging one, but tie dyeing is one of those phenomena that has been found to be very popular and successful in many high schools. Even though it ap- pears to be a n "arts and crafts" project, the activity can be justified in a high school chemistry course if the chemistry involved in tie dyeing can be related to the organic chemis- try unit. The objective of this article is to describe the method of application and the chemistry of the most popu- lar fiber reactive dyes, roci ion' MX dyes, used in tie dye- ing.

The Dyes Procion MX i s the commercial name for dichlorotriazine

dyes. They are the most reactive and versatile of the fiber reactive dyes, which means that the dye molecule actually reacts with fabric molecules. These dyes can be used on cotton, silk, wool, rayon, linen, paper, and wood but not on

Figure 1. Procion MX (dichlorotriazine).

synthetic fibers. The reactive group is shown below in Fig- ure 1 ( I ) .

The " D represents the color-forming or chromophore part of the molecule attached to the reactive group. Exam- ples of three of these common dyes are given in Figure 2 (21.

Mixing the Dyes Caution: The dyes are sold in the form of a powder and are considered to be nontoxic. Common sense should be used in handline anv chemical. however. Proloneed inhalation of the - , dw powder ran muw sn dl lcwc rtatllun in somc pwplc A dust mark and ruhher gloves should be worn to mix the rhcmicnls, and mixing should he done in a hood.

Approximately 10-20 mL of dye may be mixed with 250 mL of warm water or urea solution. Hot water up to 120' F may be used to dissolve the less soluble dyes, but the dye solution should be cold when the alkali is present to pre- vent premature reaction with water (3). Urea solution, made by mixing 125 mL of urea in a liter of water (2 cups per gallon), is optional. It helps to dissolve the less soluble

'Procion is a trade mark of Zeneca Colours formerly ICI (Imperial Chemical Industries)

a. Procion Brilliant Yellow M-6G (ICI) ('CI Reactive Yellow 1)

b. Procion Brilliant Red M-2B (ICI) (CI Reactive Red 1)

c. Procion Brilliant Blue M-R (ICI) (CI Reactive Blue 4)

Figure 2. Three common dichlorotriazine dyes. 'CI refers to the Colour Index. Published jointly by the American As- sociation of Textile Chemists and Colorists, Research Triangle Park, NC, and The Society of Dyers and Colourists, Bradford, England.

dyes and, being hydrophilic, keeps the fabric damp during the processing time. Urea also "drives" the dye into the fabric during the heat-fixing process so that the colors come out brighter. Once the dye powders are mixed with water or urea solution, they have a shelf-life of four to five days. Liquid fiber reactive dyes by Createx Colors have a shelf-life of two years and may he used a s an alternative to the powdered dye. Some sources for fiber reactive dyes are listed a t the end of the article.

The Application of the Dye

Refore dye is ndded to the f:ihric, the fabric is washed in a mild drrrrarnt or rh(, commtwi.ll product called Ssn- thrapol S P t{remove sizing and other-chemicals that may interfere with the dve. Plastic doves, aprons, and safety goggles must be wain, and tnblrs should 116: covtwd with plastic. 'l'hc fal~ric is sw~kc,d in a sodium carbonate soda i sh ) solution for a t least 15 min. The solution is made by adding 60 mL of sodium carbonate per liter of water (one cup per gallon). The sodium carbonate is used to "activate" or weaken the bond between the "H" and the "0" on the "OH" (hydroxyl) group of the cellulose molecule. Cellulose is ionized under these alkaline conditions. The solution of soda ash has a pH of 10.6 and also will neutralize the HC1 formed during the reaction (4).

The fabric is wrung out to remove excess solution and folded, twisted, and tied. The methods of folding and tying

724 Journal of Chemical Education

Page 2: The Chemistry of Fabric Reactive Dyes - WikispacesPaper.pdf · The Chemistry of Fabric Reactive Dyes Marcia C. Bonneau SUNY-Cortland Cortland, NY 13045 Developing an activity that

Simplified Version can be represented as:

HO-Cellulose

Figure 3. Cellulose represented as poly-l.4D-glucopyranose

D-C: N + HCI

HOH CI

P ,OH

alkali !'%, + HO- cellulose- D-C, N + HCI N=C, IOW T N-c:

CI CI

Figure 4. Two possible reactions of the dyes at low temperature.

can be found in many sources such a s arts and crafts books and, therefore, not included in this article. The dye may be applied by means of squirt bottles or jumbo pipets to the fabric. The dyed fabric should be allowed to drain prefer- ably on a rack over the sink or dishpan before i t wrapped in newspaper or paper toweling. The dyed fabric is placed in a plastic bag, tied tightly, and allowed to set for a t least four hours (24 hours for ereen or turauoise) before i t is rinsed thoroughly in cold water to remove the hydrolyzed dve. I t is then untied and washed in verv hot water with a mild dc,tc,rgent or Synrhnpol. The hbric"is then drred in a hut drver, so the heat will "fix" the dve which is then color- fast (5).

The Chemistry of the Dyeing Process Cellulose is a complex molecule shown as

poly-1,4-D-glucopyranose in Figure 3. The structural formula of cellulose can be simpli- 0 fied to show that i t is a large molecule with a n active " O H end. Under alkaline conditions, D -C, , the dye reacts with the 6-hydroxyl position of N'C, the glucopyranose ring (6). CI

The dye can react with cellulose and/or water. The dyes all contain two chlorines which combine with the hydrogen from the "OH" on the cellulose molecule or the " H on the water molecule to form HC1. When the dye reads with the cellulose, one chlorine reacts a t the low temperature of application. The sec- ~i~~~~ 5,

ond chlorine becomes much less reactive once the first he- comes combined with the fiber a s shown in Figure 4.

During the hot wash-off process, the second chlorine either reacts with water (hydrolyzes) or reacts with the cel- lulose a s shown in Figure 5.

The reaction of the excess dye with water i s also sequen- tial due to the lower reactivity of the second chlorine. The first chlorine group may be substituted after dyeing a t low temperature followed by substitution of the less reactive chlorine after washing a t a high temperature (7, 8).

The loss of the dye by hydrolysis during dyeing varies over a range of 15 to 40%. Because the dye is so rapidly absorbed by the fiber, the reactive groups in the dye and fiber are brought into close proximity and the heterogene- ous reaction with the fiber predominates over the homoge- neous reaction with the water molecules (9).

The hig advantage of using these dyes is that once the fabric is washed in hot water, the colors will not run or fade easily unless exposed to bleach or bright sunlight.

Sources of Fiber Reactive Dyes PRO Chemical and Dye Ine., 6.0. Box 14, Somerset, MA02726;

Tel. (508) 676-3838. Createx Colors, ColarCRAFT Ltd., 14 Airport Park Rd., East

Granhv. CT 06026: Tel. (2031 653-6225. Grateful d ies , Inc., 2139 S. Sheridan Blvd., Denver, CO.

80227; Tel. (303) 753-8774.

Acknowledgment I would like to thank Elnore Grow of Horizon High

School, Brighton, Colorado, for sharing her expertise on tie dyeing, and Peter J. Dolby of Dolby Dyeing Systems, Char- lotte, NC, formerly of ICI- America for sharing his knowl- edge of dyes.

Literature Cited

7. Dolby P J. Tezlile Chemist ond Colorist. 1880.12 .(9), 74. 8. Dolby P d., Personal communication, 199%. 9. Allen. R. L. M., p 203

O- cellulose

+ HOH O- cellulose

high T N-c,' D-6 N + HCI

ossible reactions of the dye after washing at high temperature.

Volume 72 Number 8 August 1995 725