i i FIRST PLACE WINNER: Quebec Section

Effects of Substantiv ity in Cotton with Reactiv :?

n dyeing cotton with fiber reactive the material. The dyebath exhaustion at In almost any range of commercial 1 dyes, the addition of alkali to the the end of this phase is called the primary reactive dyes, there is a graduation of dyebath not only promotes formation of exhaustion. substantivity from very low to medium, or the covalent bond between the dye and the 0 The fixation phase. This begins when even quite high substantivity, particularly cellulose but also causes hydrolysis of the alkali is added to the dyebath to raise the in the presence of salt. The dyer is thus reactive group of the dye. Unfixed hydro- pH to the point where the dissociated faced with the problem of deciding how lyzed dye remaining in the fabric after the hydroxyl groups of the cellulose begin to severe the washing conditions should be dyeing process must be removed by wash- react with the dye. Migration of the fixed for removal of unfixed dye from the ing, otherwise the optimal fastness to dye is impossible. During this stage, more material since he must decrease the resid- washing and crocking of the final fabric dye is absorbed from the solution and ual amount to the level that his client is will not be realized. The batch dyeing reacts with the cellulose. The exhaustion satisfied with the fastness properties of the process thus consists of three stages: of the dyebath at the end of the process is final product. To achieve the best product The migration phase. In this first called the secondary or final exhaustion. quality, the dyer can wash the goods stage, the cotton is treated with dye The washing phase. Once dyeing is repeatedly, consuming more hot water solution in the presence of salt at about pH completed, the material is washed several than may be absolutely necessary. On the 6, but little reaction with the cellulose times to remove unfixed dye. The fixation other hand, from the point of view of cost occurs. The dye is free to migrate from the is calculated using a simple mass balance and productivity, it is important to keep more heavily to the lightly dyed areas of based on the total amount of dye added to hot water consumption to a minimum. the initial dyebath, the amount remaining The problem of dyeing on shade with in the final bath and the amount removed trichromatic mixtures of reactive dyes is by washing. also related to the substantivity of the .S The primary and final dyebath exhaus- dyes. The best color control results by If :e ABSTRACT tion and the fixation yield are defined as using dyes which all have the same reac- follows: tive group, and which also have compara- .h Fiber reactive dyes for cotton were 70 Exhaustion ble rates of dye absorption and fixation. Jl shown to vary widely in their substan- = 100 x (C,- Cf)/ c, The dyer then only needs to be concerned 'P tivity for the fiber. Substantivity also where C, = initial concentration of dye about the gradual development of the :h depended on dyebath temperature and (g/L) and CJ = final concentration of dye depth of the particular shade. When using cs salt concentration, as expected. The dyes of quite different reactivity or sub- er relative substantivities of the hydrolyzed WL). %Fixation stantivity towards the cellulose, there will id forms of the reactive dyes were assessed = loox(Mi-Mf-M,)/M, in the laboratory by means of a simple, be pronounced color changes during the quick and inexpensive paper chrom- where Mi = mass of dye in the initial dyeing operation, as well as the usual build atography test. Correlation of the sub- dyebath (g), MI = mass of dye in the final up in depth. This makes color matching stantivity of the dye with the amount dyebath (g) and M, = mass of dye re- very difficult. removed from the cotton under various moved by washing (g). This project was developed in response washing conditions indicated that it The primary dyebath exhaustion, and to these practical problems related to the should be possible to select higher or the ease with which unfixed dye can be substantivity of reactive dyes. The objec- lower washing temperatures based on removed by washing after dyeing, depend tive was to examine how the substantivity the substantivity of the dye to be re- on the substantivity of the , or of these dyes influences dyeing with tri- 'es . moved. In addition, the paper chroma- 1 or of its hydrolysis product, for the cotton. In chromatic mixtures, and the ease with tography test was useful for quick .be general, the two forms have almost identi- which unfixed dye can be washed off the selection of dyes of about the same Idi- substantivity. Mixtures of such dyes cal substantivities. Many of the early cotton after dyeing is completed. It was dyed cotton with little change in hue reactive dyes for cotton were, by design, also decided that it would be valuable to We- re. during the dyeing process; dyes of dyes of low substantivity whose chemical have some simple laboratory test which different substantivity gave pronounced structures resembled low molecular the dyer might use to evaluate the substan- pn- color changes. weight acid dyes rather than the more tivity of reactive dyes. The results of such a rely ub- complex direct dyes. It was not possible, test might be used to select dyes for dyeing 1 in- however, to provide a complete range of in combination and also for establishing Key Terms pg colors, including navy blues for example, more or less severe washing conditions, me Dyeing Cotton without introducing at least some dyes and thus contribute to energy savings I as Fiber Reactive Dyes which had substantially higher substantiv- where this is possible. Paper Chromatography ity for cotton. Some of the newer bifunc- Reactive Dyes tional reactive dyes, such as those synthe- Experimental Techniques , 41 Reactive Groups sized by coupling two monofunctional For paper chromatography of the dyes, a Su bstantivity reactivedye molecules together, are also of solution of dye (1 .OO g/L) was prepared in increased substantivity. aqueous NaOH solution (1 .OO g/L). The

November 1991 Ca, 21

--.. -- c Dye Substantivity 2-propanol/water/concentrated aqueous trations were determined by absorbance ammonia (9%: 1 by volume). measurements at the wavelength of maxi- All analyses of dye solutions were per- mum absorption and calculation from the solution was allowed to stand for several formed using standard spectrophotomet- slope of the Beer-Lambert calibration days to ensure that the reactive groups of ric techniques (3).Transmission measure- graph prepared using dye solutions con- the dyes were hydrolyzed and then neu- ments were carried out using a Diano taining the same amount of phosphate tralized to pH 6 with acetic acid. Small Match Scan I1 double beam reflectance buffer. volumes of the dye solutions were then spectrophotometer with matched 1.00 cm The material used was a bleached cot- spotted onto a small piece (2 X 4 in.) of glass cuvettes. To ensure that the dye in ton jersey knit (I63 g/m2). The reactive Whatman $1 filter paper. After drying, the solution always had the same environ- dyes were applied at a depth of 1 .OO% owf the papers were developed by standing ment, and thus did not undergo changes in at temperatures, and salt and alkali con- them in a shallow pool of solvent in a closed extinction coefficient. samples of the dye- centrations, according to the recommen- jar and the chromatograms developed by bath to be analyzed were mixed with dations of the manufacturers (see Table the ascending technique (I,2). The devel- phosphate buffer solution (0.10M I). All dyeings were carried out in sealed oping solvents used were 2-propanol/wa- Na2HPO4X7H20, 0.10 M KH~POJ)and stainless steel pots using a Zeltex Poly- ter/acetic acid (18: 17: 1 by volume) and diluted by a factor of five (4).Dye concen- color laboratory dyeing machine equipped with a Szdo PC 1000 microprocessor controller. In all cases, a liquor-to-goods Table 1. Dyeing Conditions for the Exhaustion and Fixation Data ratio of 20: 1 was used (5.00 g cotton plus 100 mL dye solution). The alkali was added in the form of powdered sodium Salt N a2C03 Time of Time of carbonate. or a very small volume of Dyeing Conc. Conc. Migration Fixation concentrated sodium hydroxide solution. Dye Temp (C) (P/U (g/L) (min.) (min.) After dyeing, the cotton was washed six 40 50 5a 30 15a times in clean water, for 5 min. at 30C and + 0.5 NaOHa 45a then for 15 min. at temperatures of 60,60, 30 40 10 40 60 100 1 45 30 10 30 60 100, and 60C using a 16: liquor ratio. 30 40 10 30 60 In trials to measure the exhaustion of 5O-8OQ 20 15 40b 453 the hydrolyzed forms of the dyes, stock 50-80' 40 15 40° 453 solutions were prepared as described foi 30 40 10 30 60 paper chromatography. The dyebath ea- 40 40 10 40 60 haustion after 60 min. was measured for 50-80' 20 15 40° 453 1 .OO% owf dyeings carried out at either 30, Gation with soda ash for 15 min followed by NaOH for 45 min b50C/10 min plus salt. 50-80C/30 50.75 or IOOC, in the presence of either 0, min.. add alkali. fixation at 80C/45 min IO. 20 or 30 g/L salt using a 20:l liquor ratio. In tests of dyeings using washing condi- Table 11. Commercial Names of Dyes Used in the Study tions of increasing severity, dyeings at a I I 1.0Occ owf strength were prepared using Code the conditions given in Table I. For each Number' Commercial Name, C.I. Name dye. three dyeings were prepared, and one sample of each was submitted to one of the Dyes Studied in Detail three washing procedures. These consisted 1 Remazol Yellow R vs of five- 15 min. washes at a 16: 1 liquor ratio 2 Procton Blue MX-R. Blue 4 DCT using the following temperatures: 3 Levafix Brilliant Blue E-E. Blue 29 DCC 0 Wash GI: 30,30,60,60, and 60C. 4 Blue MX-7RX. Blue 161 DCT 5 Ctbacron Red C-2G. Red 228 MFT-VS 0 Wash =2: 30,60,60,100, and 60C. 6 Cibacron Yellow C-R. Yellow 168 MFT-VS 0 Wash =3: 30,60,100,100, and 60C. 7 Procion Turquoise MX-G. Blue 140 DCT To evaluate the efficiency of these pro- 8 Drtmarene Navy Blue K-26. Blue 19 DFCP cedures, the final air dried dyeings were 9 Procion Red HE-7B. Red 141 MCT-MCT again washed for 15 min. at the boil, using Other Dyes Used the same liquor ratio, and the amount of extracted dye was measured. 10 Remazol Navy Blue RGB 11 Procion Red MX-5B. Red 2 DCT Dyeings with mixtures of reactive dyes, 12 Drimarene Brilliant Red K-4BL. Red 47 DFCP to test for the constancy of the hue during 13 Procion Yellow MX-3R DCT the process, were carried out in a Benz 14 Procion Yellow HE-6R MCT pilot scale jet dyeing machine using the 15 Basilen Yellow E-3R. Yellow 3 MCT dyeing method starting at 5OC and adding 16 Levafix Yellow E-2RA DCC alkali at 8OC (see Table I). Samples of Dyes Used in Mixtures for Dyeing Cotton dyed cotton were cut at five min. intervals 17 Remazol Brilliant Blue R spec., Blue 19 vs after the addition of the alkali. These were 18 Remazol Yellow 3RS well washed in hot water and dried at room 19 Remazol Brilliant Blue RBC temperature. The CIELAB color co-ordi- i 20 Procion Brilliant Red H-EGXL MCT-MCT nates were measured using the Diano 21 Pricion Blue H-EGN. Blue 198 MCT-MCT Match Scan reflectance spectropho- 22 Procion Yellow H-E4R. Yellow 84 MCT-MCT I1 23 Procion Turquoise H-A. Blue 71 MCT tometer. 24 Procion Yellow H-EXL MCT-MCT - Dye Selection the text, all dyes will be referred to by this code number. bVS = vinyl sulfone, MCT = monochlorotrtaztne. DCT = dichlorotriazine. DCC = dichloroquinoxaltne. DFCP = difluoro- All the reactive dyes were commercial chloropyrimidtne and MFT = monofluorotriaztne. samples used as received from the manu-

22 clfi, Vol. 23, NO. 11 -- facturers. Early in the project, some diffi- between the final exhaustion and the culties were encountered with dyes whose fixation yield. This was because the trans- extinction coefficients were found to vary fer of varying amounts of dyebath solution with change in the salt concentration or into the first wash bath was unavoidable in the pH of the solution. Such problems have order to avoid loss of dye. been observed before (5).Some dyes were also found to be unstable in boiling water. Washing Off Unfixed Dyes Dyes exhibiting the presence of two col- After dyeing, unfixed dye was extracted ored components, with different substan- fram the cotton in a series of six washings tivities based on paper chromatography with clean water: one wash at 30C for 5 tests, were avoided. Because of the need to min. and five 15-min. washes at 60C, 60C, have reliable exhaustion data as a measure lOOC, lOOC and 60C. The data on wash- of dye substantivity, most of the dyes ing off of the unfixed dyes are shown in the selected for study were those which passed histogram in Fig. 4. f a specially developed screening test. This Examination of Fig. 4 shows two trends 1 t isdescribed in another paper (4). Dyebath Exhaustion related to the substantivity of the dye. In 1 The list in Table I1 gives the commercial And Fixation Yields general, for the dyes of lower substantivity t names of the dyes used in this study, and, In the initial dyeing trials, the primary and for cotton (Dyes 1-5), large amounts of where known, the nature of the reactive unfixed dye were extracted in the first two S final dyebath exhaustion and the fixation 7 group and their Colour Index Name (6); yield were measured for a number of washing processes (30C/5min. and 60C/ 1 5 min.), very small amounts being "8.. C.1. Reactive Blue4. different reactive dyes using dyeing proce- removed in the final wash (60C/ 15 min.). Dyes 1 and 9 were found to be mixtures. dures derived from the dye manufactur- These dyes were included because of their For these dyes, each successive wash t er's literature. A resume of the dyeing 1 low and high substantivity for cotton, conditions is given in Table I and the removed less dye than the previous one. Although Dye 2 had a somewhat different e respectively. After completion of the dye- results are in Table 111. ing trials. solutions of Dye 8 were found to The wide range of primary exhaustion profile, it is a dye of low substantivity and the complete washing cycle resulted in a be unstable on heating at 9OC in the values showed that the dyes selected did presence of salt and alkali. Data for this have the desired range of substantivity for very small amount of residual unfixed dye in the fabric. For the other dyes (Dyes e dye are included but the fixation yield and cotton. Some of the fixation yields were \>.ashin$data will be less reliable than for 6-9), the washing profiles were quite dif- II disappointingly low, particularly for the d :he other dyes. dichloro- and monofluoro-triazine reac- ferent. Relatively less dye was extracted in the initial cold wash and higher washing I tive dyes. This was probably a conse- Paper Chromatography temperatures (60 and IOOC) were neces- quence of the loss of reactive capability Of Hydrolyzed Dyes sary to remove the bulk of the unfixed dye. due to extended storage. These results do * In the case of the most substantive dye The paper chromatography characteris- not indicate poor quality of certain prod- (Dye 9), the final wash at 60C still is tics of 50 reactive dyes were examined by ucts since the dyeing methods were not removed a considerable proportion of un- )f the ascending technique using the two optimized. fixed dye. It was tempting to consider that le different developing solvents. About 25% Thedata shown in Fig. 3 confirmed that this was a direct consequence of the high h of these dyes contained significant the primary exhaustion of the reactive substantivity of this dye for cotton fibers n :!mounts of a second colored component of dyes was directly related to the paper but other factors must be considered. E different Rfvalue. For 16 of the dyes. the chromatography RFvalues. High RFval- Firstly, it is always possible that some .h RFvalue was measured at least three times ues were obtained for dyes of low substan- color is being removed in washing because :S and the mean value calculated. The RF tivity. Unfortunately, Dyes 1 through 5 all of instability of the dye-fiber bond under :r value is the distance the dye spot travels gave low primary exhaustion values, with the washingconditions. This is not likely to id from the origin (I) divided by the distance little variation, despite fairly large differ- be too important in this case since by the traveled by the solvent front (y),as shown ences in RF values in the two different time the fabric has already been washed in Fig. 1. It was calculated as a percentage. developing solvents. five times in water, the pH would corre- RF=(100 X x)/y Despite the wide range of fixation yields obtained in the dyeing trials, and the The standard deviation of the three or rather low values for some dyes, all but two 80 7 four measurements was k 1.9%. Fig. 2 of the final dyeings contained about 10-12 shows the relationship between the RF mg (0.20-0.24% owf) of extractable un- values in the two solvents (aqueous pro- fixed dye compared to the initial amount of 5. panol/ammonia and aqueous propanol/ 50.0 mg (1 .OO% owf). These amounts were D x acetic acid) for the selected dyes. Both 10 larger than calculated from the difference >e solvents gave a wide range of RF values li- showing the considerable variations of the t- substantivities of the dyes examined. Pre- i vious studies (I) have shown that paper 6- chromatography RFvalues correlate well with the substantivity of various types of by dyes for cotton. This test therefore pro- h: vides a rapid and inexpensive means of lg assessing the relative substantivity of reac- 0 20 40 60 80 be tivedyes for cotton. In general, thevalueof R F PROPANOL - ACETIC ACID as RF in the propanol/ammonia solvent was I higher. This is probably a consequence of DYE SPOT DEVELOPMENT Fig. 2. Relation between the values of the AT ORIGIN WITH RISING RF 11 the lower substantivity of the anionic dyes SOLVENT hydrolyzed reactive dyes in the two different for cellulose in an alkaline environment developing solvents. Dyes are numbered using (7). Fig. 1. Paper chromatography. the codes in Table 11.

November 1991 crzl 23 Dye Substantivity of removal of the unfixed form of Dye 9 is a consequence of its high substantivity for Table 111. Measurements of Dyebath I cotton. This dye was, in fact, selected Exhaustion and Fixation Yield because of this. In order to examine the relation be- Primary Final Fixation tween the ease of removal of unfixed dye Dye Exhaustion Exhaustion Yield and the substantivity, as expressed by the paper chromatography values, the 1 5.7% 60.5% 45.7% RF 2 11.1 60.5 40.4 amount of dye removed in a particular 3 12.3 66.7 56.1 washing process was divided by the total 4 9.9 41.7 27.2 amount removed from the fabric in this 5 10.7 33.7 31.8 spond closely to that of maximum dye- and all subsequent washing steps. This 6 37.8 71.0 56.7 fiber bond stability (8). parameter was called the washing ratio. 7 26.5 53.7 23.1 8 47.6 88.9 72.5 Secondly, in this case, the analysis is less Washing ratio = 100 X Dye removed in 9 70.2 86.3 66.5 precise. Dye 9 contained two colored the nrhwash divided by Dye removed in the components of differing substantivity. nrhand subsequent washes. During the course of the washing cycle. the Thedata in Fig. 5 show some interesting IOOC, all the dyes were extracted with absorption spectra of the wash solution trends. As the temperature of the washing equal facility. Data presented later in the changed, the two absorption maxima at process increased. the value of the washing paper clearly illustrated that at the boil. in 510 and 540 nm shifting to 520 and 557 ratio increased, the effect being more the absence of salt, the hydrolyzed forms nm. The dye was found to be thermally pronounced for dyes of higher substantiv- of all the dyes studied, except Dye 7, have stable under the washing conditions and ity. At washing temperatures of 30 and very low substantivity for cotton. Thus. the the change in spectrum was attributed to 60C, there was a definite influence of the definitive method for removal of unfixed extraction of different proportions of the substantivityoftheunfixeddyeon theease reactive dyes from cotton is to wash at as two colored components. Despite the fact of its extraction from the cotton. The more high a temperature as possible. once the that this introduced some imprecision into substantive dyes. of low RF value, were salt has been rinsed from the fabric. This the analysis, it appears that the difficulty more difficult to wash out. For washings at of course increases production costs and it would be desirable to reach a compromise between the need for effective removal of -1 = 9 unfixed dye and the cost of the hot water to realize this. z ao -I \ Substantivity of Hydrolyzed Reactive Dyes 60 Additional data on the substantivity of the hydrolyzed forms of the dyes were ob- 40 tained in a series of dyeing trials carried 3 out at different temperatures and salt 49 concentrations. The baths contained 1% 20 owf of the dye and dyeing was carried out for 60 min. using a 20: 1 liquor ratio. After 3, 3, -2 , 4 0 dyeing. the exhaustion of the dyebath was determined. In Fig. 6, note that the upper 0 50 100 series of five graphs has a 0-20% exhaus- RF tion scale, while the lower series has a 0-803 scale. Fig. 3. Relations between the primary exhaustion of the reactive dyes and the paper chromatography The hydrolyzed forms of Dyes 1,3 and 4 RFvalues. A: developing solvent is propanol/ammonia. This'curve is displaced by +ZO% on they axis. were of low substantivity, had maximum B: developing solvent is propanol/acetic acid. exhaustion dyeing temperatures below

70 1052mg 1007mg i4aamg iO96mg 12.01 mg 11.17mg 2108mg 737mg 11 63mg 0e 60

a:6 50 I

DYE 1 DYE 3 DYE4 DYE5 DYE6 DYE:! DYE7 DYE8 DYE 9

Fig. 4. Amounts of unfixed dye removed in the six washings after dyeing. The total amount of extracted dye is given above the bars for each dye. For each dye, the heights of the bars from left to right indicate the amount of dye removed, relative to the total extracted dye, in each successive washing process at 30, 60,60,100, lOOand 60C.

24 CUI Vol. 23, No. 11 r .- I i "1 3OoC -:--.A..-

,;9 l0O0C 1000c 60 % > :of or. ht- 0 30 60 0 30 60 0 30 60 0 30 60 0 30 60 in- .el- RF RF RF RF RF ;of I in Fig. 5. Values of the washing ratio for the first five-washing process as a function of the RF value for the propanol/ammonia solvent. The washing ect temperature is given on each graph. The dyes are identified by their numbers in the second graph from the left. j in {et s is .:K, and were not particularly sensitive to was much higher and was much increased particular interest. Dye 7 is a copper 27 the addition of salt. Dyes 2 and 5 were also in the presence of salt. The temperature of phthalocyanine dye. These types are well UP. of low substantivity but, as the salt concen- maximum exhaustion was always above known to aggregate in solution (10) and H3, tration was increased, maximum dyebath 40C. The maxima in the profiles would be higher dyeing temperatures give more ect exhaustion occurred at higher tempera- explained by the opposing tendencies of monomolecular dye, which is free to dif- 1 in tures. Such behavior is more typical of salt, which promotes greater dye aggrega- fuse into the cotton fibers. For Dye 9 at are direct dyes and can be interpreted in terms tion in the fiber and thus higher substantiv- 30C, addition of salt initially increases the ssi- of the effect of salt in promoting dye ity, and of increasing temperature. which dyebath exhaustion, but further amounts ra- aggregation in the fiber. rather than in the causes deaggregation of the dye in both of salt suppress it. Dye 9 thus behaves like =- solution (9). The hydrolyzed forms of the phases, but less effectively in the fiber than a highly substantive direct dye, for which lue rzmainingdyes (Dyes 6-9) all behaved like in solution below 40-50C. addition of salt increases the substantivity Kill direct dyes. Their substantivity for cotton The profiles for Dyes 7 and 9 are of by promoting aggregation of the dye in the ind ieir

DYE 1 DYE 2 DYE 3 - DYE 4 DYE 5 s is 2o i ' of one tch 1 in ing .ich tics 8 her 5 \ and yes. 100 ing 50 100 50 100 z50 50 100 50 100 :ing TEMP. TEMP. TEMP. TEMP. TEMP. : is dng DYE 0 DYE 7 DYE 6 DYE 9 rely 80-/ I yes. B or I be Idi- lye- 4 re. r bn- 1s- rely /- rb- rin- dng rise 50 100 50 100 50 100 50 100 as TEMP. TEMP. TEMP. TEMP. 41 Fig. 6. Data on exhaustion of hydrolyzed reactive dyes at different salt concentrations and different temperatures. Salt concentrations are shown in g/L.

November 1991 a53 25 Dye Substantivity the same treatments. In general, the amount of dye removed in the first wash Table IV. Data for Dyeings Using was greater than indicated in Fig. 4 I Mixtures of Reactive Dyes 1 because, in this series of washing trials, the first wash was for 15 rather than 5 minutes. Combination Dyes Dye RFa This explains, for example, the difference in profile for Dye 6 between Figs. 4 and 7. A 18 0.73?'ob 42?& 19 0.18 51 After the washing test, each sample was B 18 0.82 42 air dried. Additional unfixed dye was then 17 0.15 94 extracted from the sample by treatment C 20 0.25 9 with boiling water for 15 min. using a 20: 1 21 0.16 4 liquor ratio. The mass of extracted dye was 22 0.62 6 D 9 0.17 3 cotton. At higher salt concentrations, the determined by absorption spectrophotom- 23 0.19 10 formation of larger dye aggregates in etry. The results are also given in Fig. 7. 24 0.52 22 solution gives less and less monomolecular For these samples, 0.5 mg of residual - aR~values in aqueous propanol/ammonia dye in the bath. Absorption of dye by unfixed dye in the cotton corresponds to bowf. diffusion thus becomes more and more 0.01% dye owf. If this were considered to restricted. be an acceptable maximum level to achieve the fastness properties consistent at 80C (Table I). Table IV gives the dye Washing Off of Hydrolyzed Dyes with customer satisfaction, it was easily recipes and the paper chromatography RF The objective of this part of the study was surpassed using the procedure for Wash values of the dyes selected. During the to examine the washing off characteristics $1 for Dye 1. For Dye 2, of higher dyeing process, after the addition of alkali of reactive dyes of quite different substan- substantivity, even Wash $2 was border- to initiate fixation, samples of the cotton tivity for cotton using conditions which line, and Wash $3 was necessary to leave were removed at 5 min. intervals over the would be classed as mild, medium and less than 0.5 mg unfixed dye in the cotton. course of 1 hr. These were washed in hot severe. It was hoped that dyes of low For the most substantive dye (Dye 9), even water, air dried, and then the CIELAB substantivity would be effectively elimi- Wash 33did not meet the requirement of color co-ordinates a* and b* were mea- nated from the fabric using a mild washing less than 0.5 mg residual dye and even sured. In the first trial, a mixture of Dyes procedure, those of medium substantivity more severe washing conditions would be 18 and 19 was used. The points for the by washing of medium severity and the required to meet this standard. values of a* and b*, corresponding to most highly substantive dyes by a rigorous Although time only permitted examina- different times after addition of the alk-ii washing procedure. ~ tion of three dyes, these preliminary re- to the bath. all clustered together (Fig. 8. The dyes chosen for this study were sults did show that it would be possible to A), presumably because of the high rate of Dyes 1, 6 and 9. A 1 .OO% owf dyeing of select more or less severe washing condi- fixation of these dyes under the dyeing each dye was submitted to each of the I tions based on an examination of dye conditions. three washing operations. of increasing , substantivity for cotton using either the When using Dyes 17 and 18, a similar severity, as described in the experimental I primary exhaustion or an RFvalue. shade was obtained, but in this case the section. The results are shown in Fig. 7. dyeing became gradually yellower during The results were similar to those shown ~ Dyeing with Mixtures of Dyes dyeing. This could be a consequence of the in Fig. 1. Increasing the severity of the Dyeing trials on cotton were carried out in higher reactivity of the less substantive washing operations from Wash =I to which dyes were pre-selected to have blue d>e (Dye 17). Also, it must b.: Wash ~3 increased the amount of unfixed either very similar or different substantiv- remembered that vinyl sulphone reactive dye removed from the cotton. The repro- ity for the cotton based on the measure- dyes present a special case. The substan- ducibility of the procedures was good, as ment of paper chromatography RFvalues. tivity of the hydrolyzed dye as measured shown by the constant amounts of dye All the dyeings were performed on a pilot by the RFvalue may not correspond to that removed for samples containing the same scale jet dyeing machine using the dyeing of the vinyl sulphone. For this mixture, the amount of unfixed dye and which received method starting at 5OC and adding alkali connection of the points for a* and b* gave

6 a .E 833mg 963mg 1104mg 971mg 1071mg lO68mg 570mg 872mg 939mg h -c I i i

a WASH1 WASH2 WASH3 WASH1 WASH2 WASH3 WASH1 WASH2 WASH3

DYE 1 DYE 6 DYE 9 n

Fig. 7. Amounts of unfixed dye removed from dyed cotton fabric using three washing procedures with different temperature regimes. The total amount of dye removed by each complete washing procedure is given above the bars for each dye. The last bar on the right for each dye is printed over the last bar. Each dyed sample was washed in clean water for 15 minutes using the multiples of temperatures designated as Wash $1. Z? and #3.

26 CW Vol. 23, No. 11 dyes, to be used in combination, which Textile Graduates Society. would dye cotton with little change in hue The group at Universite de Sherbrooke as the depth of the dyeing gradually acknowledges the support of the Natural develops. This would give the dyer much Sciences and Engineering Research more control in color matching. Future Council of Canada and the many support- studies should confirm these initial results. ers of the Industrial Chair in Textile - Engineering at Sherbrooke. cco Committee Members The paper was presented in Charlotte by References Michel Hehlen of Sandoz Canada Inc. > Other committee members included (I) Sramek, J., Analyrical Chemistry of Syn- of Camil Tremblay, chairman, Hoechst rheric Dves: Edited by K. Vankataraman; Wiley-ln- x, terscience, New York, 1977, p57. It- ,,I), I,!,, Canada Inc.; Christian Langlois, Intech (2) Sherma, J. and G.Zweig, Paper Chromaiogra- -8 -4 0 4 8 PEM Inc.; Arthur D. Broadbent, Yawen phy and Elecrrophoresis. Vol. II. Paper Chromarog- in- el- a' Qu, Siamak Jamshidi-Barzi and Mah- raphy, AcademicPress.New York, 1971. (3) Strobel, H. A. and W. R. Heineman, Chemical of moud Feiz of the Universite de Sher- Insrrunienrarion: A Sysremaric Approach. 3rd Edi- Fig. 8. Variation of CIELAB a* and b* values brooke. Mahmoud Feiz is on leave from in tion. Wiley-Interscience. New York. 1989. :ct during the course of dyeing with various combi- Isfahan Universityof Technology, Iran. (4) Qu. Y. and S. Jamshidi-Barzi. Book ofPapers: nations of reactive dyes on cotton. See Table IV AATCC Inrernarional Conference & Exhibirion. in for legend. Arrows indicate increase in dyeing Acknowledgements Charlotte. October 1991. p30. et (5) Garland. C. E., Analyrical Chemisrry ofSyn- itme. The lines are lines of constant hue. t is The committee would like to thank the rhetic D.lies; Edited by K. Venkataraman; Wiley- following for their contributions to this Interscience. Neu York. 1977; p149. 27 a line cutting across the line of constant project: (6) Colour Indes, Society of Dyers and Colourists !P. and the American Association OfTextiieChemistsand hue originating at a* = 0, b* = 0, as BASFCanada Inc., Bayer Canada Inc., 13. Colorists. Third Edition. I97 I. :ct shown in Fig. 8, B. If dyeing is to occur CATCC Section Quebec, Ciba-Geigy (7) Burkinshaw, S. M.. The Chemisiry and Appli- in with little change in hue, a plot of b* versus Ltd., Clough Chemical Inc., Comdye Inc.. mrionofDyes: Edited by D. R. Waring and G. Hallas: re a* should give a line from the origin out to Dominion Textile Inc., Dominion Textile Plenum Press, Neu York. 1990.0277. Senn. R. C. and H. Zollinger. Helverico Chim- si- the highest absolute values of a* and b*. Foundation, Eastern Townships Textile (8) ~a.4cta.V01.46, No.3. 1963.~781. a- This behavior is shown for the trial with Association. Hafner Fabrics of Canada (9) Giles. C. H.. The Theory of Colorarion of - Dyes 20.2 1 and 22. This combination gave Ltd., Hoechst Canada Inc.. Hubbard Dl- Tesrilrs: Edited b! C. 1. Bird and W. S. Boston: Dyers Compan! Publications Trust. Society of Dyers and ue 2i :an color which gradually became deeper ers Inc.. IC1 Canada Inc.. Imtex Machin- Colourisls. Bradrord. England. 1975. p86. ill ery, Sandoz Canada Inc., Texail Inc.. during dyeing but was always on shade (10) Datyner. A. and M. T. Pailthorpe. Journalof id Teinturiers MGS Inc.. Textiles Dionne. (Fig. 8. C). For a similar shade obtained Colloidal and Iiirerfaciol Science. Vol. 76. No. 3. :ir using Dyes 9,23 and 24, the initial dyeings Textile Federation of Canada and the August IYSO.pS57. were much too red because of the high substantivity and reactivity of Dye 9. During the operation, the dyeings gradu- is ally became deeper and yellower as the less of substantive components were absorbed, Miup Sizing Literame le but the line connecting the points for a* :h :.nd b* as dyeing proceeded were spread Two books containing up-to-date information on warp sizing are in out, curved and they cut across the line of now available from AATCC. The AATCC Warp Sizing Handbook is a *g constant hue in the color space (Fig. 8, D). :h This type of behavior would make accu- comprehensive compilation of papers by experts in the field. Pub- 3 rate color matching almost impossible. lished in April 1987, the 1 5 1 -page book covers sizing agents, siz- zr These initial dyeing trials with mixtures Id ofdyes indicated that paper chromatogra- ing equipment, chemical spot tests, laboratory desize procedures, phy could be valuable for selecting dyes of definitions and calculations, and analysis of blended warp sizes. S. comparable substantivity to obtain dye- Loose-leaf binder; $29 to AATCC members, 551 to nonmembers. 'g iggs which develop with constant hue. Of Order No. 8723. fg course. such control of the dyeing process is is aided if the dyes are also of comparable 'g reactivity towards the fiber. Copies of the Book of Papers from AATCC's Warp Sizing Symposium ty Conclusions held in 1987 are also available in limited supply. Sizing: The Total B. The substantivity of reactive dyes for Perspective contains 13 papers on the latest developments in )r 1 cotton influenced the ease with which the sizing equipment, size application, sizing agents and testing and E unfixed dye could be removed from the laboratory evaluation. Soft cover, 83 pages; $28 to AATCC fabric after dyeing, the lower substantivity !- dyes being removed in larger amounts members, $51 to nonmembers. Order No. 8906. I- under milder conditions. Although only a limited number of dyes have been exam- AATCC C i ined, it seems that washing temperatures P.O. Box 12215 r could be selected to be lower for less Research Triangle Park, NC 27709 c 7 substantive dyes, and higher for more Tel: 91 9i549-8141 g substantive dyes. In this respect, the paper C Fax: 91 91549-8933 chromatography test was most useful in 16 I providing a quick and inexpensive mea- ALL PUBLICATIONS MUST BE PREPAID VISA OR MASTERCARD ACCEPTED sure of the substantivity of the dye. This 1 test would also allow rapid selection of

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