1

福島大学理科報告47号 (1991) g

Temperature Effect on the Dyeing of Cotton Fabricswith Reactive Dyes.

Hitoshi KANAZAWA and Yukari YASHIMA

Department of Fiber Saence, Facttlty of Educatiort, Uniυerstty OfFtdmshima,Stigumtchi, Matsukaωa-machi,

Fldatshima 960-12(0000)

Abstract

cotton fabrics were dyed with ten reactive dyes having dich1orotriazine rings in the temperature range of 20℃to90℃.Maximum dye uptakes were obtained at40℃or30℃fo「 each dye On the other hand,when sodium carbonate was used,the affinity of reactive dyes on fabrics were almost constant in the range of 20℃to 30℃and decreased with a rise in temperature after that. lt was observed that the hydrolysis of C.I. Reactive Ree l Was accelerated by sodium carbonate and a rise in temperature.However,hydrolyzed Orange 1 gave a large physical affinity for fabrics and the temperature dependence of the affinity seemed similar to that of non_hydrolyzed dyes.Therefore,the reactive dyes are considered to have poor affinity at higher temperature because of their molecular structures;bulky triazinerings and smaller molecular sizes with non-coplanary compared to direct dyes.The hydroly- sis of reactive dyes seemed to have some effect on a decrease in the affinity for fabrics.It wasconcluded that the dye uptake on fabrics was not only due to the amount of dye adsorbed onfabrics but also the reactivity of the adsorbed dye and cotton cellulose,which were affectedby temperature and molecular structure of dyes.

1.lNTRODUCTION

Generally,a rise in temperature has a large effect on an increase in the diffusion rate ofdyes into fabrics;most of dyes such as direct dyes,acid dyes,disperse dyes,cationic dyes andvegetable dyes are used at the boiling point of their solutions to get high adsorption rates.0nthe other hand,reactive dyes with dich1orotriazine rings have been extensively used since thefirst preparation by lei Co_Ltd。in1956,'because they can be used at around room tempera-ture,2 the dyeing methods are very easy and fastness of dyed fabrics is high.In addition,thedyeing mechanism for reactive dyes has been extensively investigated.3

We consider that some fundamental investigations are necessary to carry out effectivelythe dyeing with the reactive dyes.When the reactive dyes with dich1orotriazine rings are usedfor the dyeing of cotton fabrics at room temperature,the reactivities between the dyes andcellulose seem dependent on the kinds of dyes.Although appropriate conditions for use wereproposed for each reactive dye by dye manufactures,no explanation was given for the reasonwhy a maximum dye uptake was obtained at a certain temperature lower than the boilingpoint of the dye solution.4In the present article,we investigated the temperature dependenceof the dyeing of cotton fabrics with ten reactive dyes_

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10 金浮・八島:反応染料による綿布の染色における温度効果

2. EXPERIMENTAL

2.1 MaterialsFollowing ten reactive dyes(produced by Mitsubishi Chemical Co_Ltd.)were used after

drying m vacuo without further purification;C.I_Reactive Red5(Red5),C.I.Reactive Red 8(Red8),C.I.Reactive Blue32(Blue32),C.I.Reactive Blue9(Blue9),C.I.Reactive Violet 9(Violet 9),C.I.ReactiveOrange1(Orange 1),C.I.Reactive Green6(Green6),C.I.Reactive Yellow 4(Yellow 4),C.I.Reactive Yellow 22(Yellow22)and C.I.Reactive Green7(Green7). Molecular structures of the dyes are given in Fig.1.

Commercial reagent grade sodium chloride(Nacl),sodium carbonate(Na2C03),sodium hydroxide (NaOH)and sodium lauryl benzene sulfonate (ABS、were used after drying tn moue without further purification.

Commercial cotton fabrics (plain weave:36's warp and30's weft;yarn density 72/inch warp and 69/inch weft)were dried at about 100℃for ever six hr after the desizing with ammonium perchlorate;NaOH and ABS in the same manner as described previously_5

2.2 Method of DyeingTwo cotton fabrics with dimension of 5cmX5cm were put in an aqueous solution of each

dye in an Erlenmeyer flask;the dye concentration and the bath ratio were3% owf and 1:50, respectively.The flask was quickly set in a thermo-controlled shaker in the temperature range of 20℃to80℃and shaked for2 min at a rate of 85 times/min. Subsequently,Nacl was put into the flask and shaked for i8 min.Then,Na2C03was added in the flask and it was shaked for 30 min:the concentrations of Nacl and Na2C03were 40g/l and 15% owf, respectivety.After the dyeing,the fabrics were washed with about 500m1of water at room temperature for 2-3 min.,aqueous ABS solution(conc,2.5g/1 and a bath ratio of 1:100)at 90℃for 10 min and1000m1of water for 2-3 min.Physically adsorbed dyes on fabrics were regarded to be removed through the washing process The resulting fabrics were dried and ironed.2.3 Estimation of Dye Uptake on Fabrics and Dye Concentration in the Residual Solution

after DyeingVisible light reflection spectra were observed for dyed fabrics by use of a Hitachi 340

spectrophotometer equiped with a Hitachi R-teA integrating sphere.Dye uptake on a fabric was estimated as a Kubelka-Munk value (K/S value)which was calculated from the minimum reflectance in a spectrum.Minimum reflectancesof fabrics dyed with each dye are given at;Red5:520nm.,Red8:510nm.,Blue32:620nm,Blue9:580nm,Violet9 :550nm, Orange 1:625nm,Green6:630nm,Yellow 4:390nm,Yellow22:410nm and Green7:640nm. Relative dye uptake was estimated as a ratio of K/S value for a fabric dyed at a temperature to that at20℃.On the other hand,dye concentration of the residual solution after the dyeing was estimated from the maximum absorbance in the absorption spectrum using the above spectrophotometer.

4 Preparation of a Hydrolyzed Dye Solution and Dyeing of Cotton Fabrics with theSolutionA hydrolyzedOrange l solution was prepared as follows:Orange 1(the weight lg)was

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福島大字理科報告47号(1991) 11

djsso]vcd jn 100m1of lN-NaOH aqueous solution.Subsequently,the solution was refluxed at the boiling point for 3hr_It was regarded that the dye was completely hydrolyzed in this process because the resulting dye adsorbed on the fabrics was removed easily by washing with hot water.Dyeing experiments with the hydro]yzed dye were carried out in the same way as those with the reactive dyes in the absence of Na2C03.

Ct

Nae3S

Green 7

NH

Anthraquinone derivative

Fig.1 Molecular structures of the used reactive dyes.

3.RESULTS AND DISCUSSION

3.1 Temperature Dependence of Dye Uptake on FabricsFigs 2(a)_(j)give the relation between relative dye uptake on cotton fabrics and dyeing

temperature.In this paper,dye uptake means the amount of dye chemically bounded to fabrjcs.Relative dye uptake was estimated by the manner described above.The following facts are remarkable:Blue32 and Green7 gave the maximum dye uptake at 30℃(see Figs.

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12 金澤‘八島:反応染料による綿布の染色における温度効果

20 40 60 80Temperature('C)

100

0

5

0

5

2

1

1

0

o一一一-一一a'n

o>、P

o>一一o一og

20 40 60 80Tetnpera ture('C)

100

20

0

5

1'

0

o・一一D一et-

20

40 60 80To・mperature('C)

(d)Violet9

i.0 60 80Temptraturt (C)

100

100

20 i.0 60 801ernperature('C)

Figs.2 (a)-(f)_Relation between relative dye uptake on cotton fabrics and temper-ature in the dyeing with (ai Red 5,(b)Red 8.(c)Orange 1,(d)Violet 9,(e1Yellow 4 and (h)Yellow22:[Dye]= 3% owf;「Nac l」=40g/1,「Na2C03」= 15%owf;bath ratio=1:50;dyeing time=50 min_Na2C03was added at 20 minafter the starting of the dyeing1pHof the deying solution was about 10.;:).

100

2(h)and(j)),on the other hand,the other eight dyes gave it at40C_The dye uptake of Orange 1 was largely dependent on temperature,compared with the other dyes_These differences may be based on their molecular structures.However,it is not easy to discuss them systemat- ically from the differences in the molecular structures of dyes.For instance,the molecular structures of Red8andOrangel seem very similar to each other,however,the latter gave ]arger temperature dependence than the former.In addition,although Blue 32,Green6 and

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福島大学理科報告47号(1991) l3

Green7areof hydroquinone derivatives,only Blue 32 gave the maximum dye uptake at 30' C_Nevertheless,it can be said that the overall temperature dependence for these ten dyes are 、cry similar to each other;it is remarkable that the dye uptake for all the dyes decreased extremely at over50℃.This may be due to the ana]ogy among the molecular structures;all the dyes have dich1orotriazine rings which react with hydroxyl groups of ce1lu]oseor water.6

20

20

40 60 80Tempera ture・('C)

40 60 80Tempera tur e,('C)

100

100 20 40 60 80Tempo・rature('C)

100

Figs.2 (g)_(j).Relation between relative dye uptake on cotton fabrics and temper-ature in the dyeing with(g)Blue 9,(h)Blue32,(i)Green 6 and (j)Green 7:dyeing conditions were the same as those in Figs.2(a)-(f).

3.2 Spectral Changes of Red5 Aqueous Solution after the Addtt1onof Na・C0・we discuss the reasons for the existence of maximum dye uptake and the decrease in dye

upkake at high temperature.It is not necessary to investigate all the dyes to know Some properties of triazine rings.When triazine rings of a reactive dye are hydrolyzed in a solution, jt may cause some changes in the electron distribution in the dye molecule.This may be Seen by a spectrophotometric method.Thus,we observed changes in visible light spectra of a Red 5 solution before and after the addition of Na2C03,Fig.3 gives the spectral changes with time at 20℃;two peaks are seen at 507nm and at around400nm.The absorbance at the forme「 peak increased with time after the addition of Na2C03,on the other hand,that of the latte「 peak decreased and gave a red shift slighay.As a result,an equi-absorption point isobse「vcd at 490nm.The rate of the spectral changes became very small after 3hr.It was confi「med that the spectrum of a Red5 solution did not change after6hr at 20℃in the absence of Na2 C03.When similar experiments were carried out at 50℃,it was observed that the spoof「a]

6

14

1.0

0.8

.6

4

0

0

guoq」osqvt

0.2

0.0

金澤・八島:反応染料による綿布の染色における温度効果

300 400 500 600Wave Length(nm)

Fig,3 Changes of absorption spectra of Red 5 aqueous solutiorl with time afterthe addition of Na2C03at20℃:[Dye]=1.52x10-5 met/i;[Na2C03l =9.43 X10-3 met/1・the numbers in the figure give the elapsed time after the additionof Na2C03、

0

0

9

8

0

0

Euトos--o

・ouuoq」osqv(

0.70 0 40 80 120

Time(min)

Fig。4 Time changes of the absorbance at -1)07nm in absorption spectra of Red5aqueous solution at20℃and at 50℃:[Dyel and [Na2C03]are the same asthose in Fig.3.

changes were much faster than those at 20℃.Values of absorbance at 507nm after the addition of Na2C03are plotted against the time in Fig.4 for both temperatures.It is apparent

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福島大学理科報告47号 (1991) l5

that the rate of the decrease in absorbance is larger at50℃than at20℃.It was pointed out that reactive dyes with imino groups bonded to triazine rings were deprotonated at high PH and this formed dye anions with no affinty for fabrics.7,8 However,Orange l treated with alkali at high temperature gave a high affinity for cotton fabrics as shown later.Therefore, it can be considered that the amount of the dye anion mentioned above is negligible in the case of Red5.Thus,the abovespectralchangesseemtobedue tohydrolysisof thedyecaused by Na2C03,which is accelerated at highertemperature.There isa possibility that the low dye uptake at high temperature is caused by such a hydrolysis of the dye_

It was pointed out that Na2C03accelerates the reaction of the dye adsorbed on the fabrics with cellulose and as a result,the dye in the solution adsorbes furthennore on the fabrics.6 Sumner et a1.observed that the diffusion coefficient of a reactive dye with diclh1oro triazine ring into viscose film increased with an increase in pHot the dyeing bath,although its affinity for the fiber decreased gradually with an increase in the PH.9Inorder to know the effect of Na2C03furthermore,total amount of dye adsorbed on cotton fabrics physically or chemically was estimated from the dye concentration in the solution after the deying with Orange l and Nacl in the presence or absence of Na2C03.The results are given in Fig.5. When only the dye and Nacl were used,the amount of dye adsorbed on fabrics seem almost similarly between20℃and 40℃and increased extremely with a rise in temperature after that.The addition of Na2C03in the

Orange 1dyemg system caused anmcrease m

the amount of dyeadsorbed on fab- ・

rios but gave very similar tempera_ ●Dye' NaCt+Na2C03ture dependence to that with only the _dye and NaC1.This suggests that 120Na2C03increases the affinity of thedye for the fabrics similarly to Nacl. 100It is known that the affinity of direct ^dyes for cotton fabrics can be in- -j go ocreased largely by the addition of E、-' ●

neutral salts such as sodium sulfate 建 60. ●

and Nacl,because they are consld- 二ered to have effects on a decrease in - 40surface potential of the fabrics or on

a decrease in the so]ubility of the 20dyes in the dyeing bath.9・'°It is con-sidered that Na'ions in both Na2C03 0 and Nacl should increase the affin-ity of the reactive dyes for cotton fabrics similarly to the neutral salts for the direct dyes.It is noteworthy that an adsorption maximum could not be seen in Fig_ 5,although a maximum dye uptake was obtained clearly at 40℃(see Fig.2(c)).

Similar experiments were car-

20 30 40 50 60 70 80

Temperature ('C )

Fig.5 Temperature dependence of the dye concentra-tion in the residual solution([D]・,)after the dyeingof cotton fabrics with Orange l:painted circlesrepresent the results obtained in the dyeing with thedye, Nacl and Na,C03 and open circles thoseobtained in the dyeing with the dye and Nacl.Dyeing conditions were similar to those in Fig.2_

8

16

ried out with Blue 32 and Green 6. Both results given in Figs.6 and 7 resemble that of Orangel.However, Blus 32 gave the adsorption maxi_ mum at 40℃and Green6 gave it at 30℃,although the former gave the maximum dye uptake at 30℃and the latter at 40℃.These results sug- gest that the affinity of the reactive dyes for the fabrics is larger in the range of 20℃to40℃;compared with the temperature higher than that. This temperature dependence is considered to be mainly based on the molecular structures of the dyes. The reactive dye molecules examined have smaller molecular weight and no coplanary as compared with direct dyes,in addi- tion,they have bulky triazine rings, which makes difficult for their ad- sorption on fabrics at high tempera_ ture_Sumner et at. also observed that the affinity of some Procion reactive dyes for cellulose fabrics decreased simply with a rise in tom_ perature.l2In the case of direct dyes, a rise in temperature also decreases their chemical affinity for fabrics, but on the other hand it increases extremly the diffusion rate of dyes into fabrics。As a result,in the dye- ing with direct dyes,large amount of adsorption is attained in short time at the boiling point of the dyeing solution.0n the other hand,a rise in temperature is not considered to have large effects on an increase in diffusion rate of the reactive dyes.

In Figs.5,6and7,it is seen that the [D]Rs values obtained using Na2 C03at 60℃and75℃came closer to those without Na2C03at high tom_ peratures.As most of the dyes are

20 30 40 50 60 70 80

Temperature ('C )

Fig.6 Temperature dependence of the dye concen-tration intheresidualsolution(1Dj .s)after thedyeing of cotton fabrics with Green6:the nota・tion of the figure and the experimental condi・tlons are the same as those m Fig.')

60

50

40

30

20

(一/6E)SCM-0-

0

0

B[ue32

20 30 40 50 60 70 80

Temperoture('C)Fig.7 Temperature dependence of the dye concen

trationln the residual solution([D].s)after thedyeing of cotton fabrics with Blue 321 the nota_t1on of the figure and the experimental condi.tions are the same as those in Fig.5.

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福島大学理科報告47号 (1991) 17

hydrolyzed at this temperature range,it can be considered that the hydrolyzed dyes decrease the affinity for the fabrics to some extent.

3_4 Temperature Dependence of Amount of Hydrolyzed Dye Adsorbed on FabricsIn order to know the dyeability of a reactive dye with a hydrolyzed triazine ring for

cotton cellulose,the solution of hydrolyzedOrange l was prepared in the manner described in the experimental section.As NaOH was used to hydrolyze the dye,the solution of the hydrolyzed dye was alkaline_The dyeing experiments were carried out at PH=12.4 using the hydrolyzedOrange l solution and NaC].Fig.8 gives the results.The concentration of the hydrolyzed dye in the residual solution after the dyeing experiment was estimated from the absorbance at a peak 476nm in the spectra of the solution.lt is observed that the concentra- tion of the hydrolyzed dye in the residual solution increased with a rise in temperature.The hydrolyzed dye adsorbed on the fabrics were removed easily by washing with hot water. Thus,the hydrolyzed dye having no reactivity with cellulose has a physical affinity fo「 cellulose which decreases with a rise in temperature.This fact supports the above considera- tion that low dye uptake at high temperature is mainly due to the molecular structu「at properties of the reactive dyes.

On the other hand,Franlisek et a1.reported that reactive dyes bonded tocenulose are removed by the hydrolysis at high temperature.'3 This may have some influence on the temperature dependence of dye uptake,However,we can not make sure their suggestion at present.

After at],the above results show that the dyes adsorb well on the fabrics in the tempera- ture range of 20℃to40℃.Zollinger explained that the adsorbed dye can react with hydroxyl groups in cellulose more than water using the theory of SN2 reaction in organic chemistry.'3 However,our results show that cach et the dyes gave the maximum dye uptake at a definite temperature in this temperture range_Therefore,the following two factors should be considered to determine the maximum dye uptake in addition to the affinity of a dye for fabrics;the depth of the diffusion layer of a dye in fabrics and the reactivity of the dye with cellulose, which are affected by temperature and the difference in the molecular structures of dyes.

4・ CONCLUSION

The dye uptake onto cotton fabrics for the above reactive dyes gave the maxima at 40 Cor 30℃ and decreased extremly with a rise in temperature。On the other hand,the amount of

120

0

0

10

8

,,)cr[0

]

60 20 40 60 80

Temperature(°C) 100

Fig.8 Relation between the dyeing temperature and theconcentration of the dye in the residual solution(l[D].s) after the dyeing of cotton fabrics withhydrolyzed Orange 1:the initial concentration of thehydrolyzedOrange l solution=119mg/1;pHot thesolution=12_4;bath ratio:二1; 50: 「Nacl]=40g/1;dyeing time=90 min

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18 金澤・八島:反応染料による編布の染色における温度効果

the dyes adsorbed on the fabrics physically or chemically seemed almost constant in thetemperature range of 20℃to40℃and decreased at higher temperature.As the amount of ahydrolyzed reactive dye adsorbed physically on the fabrics decreased with a rise in tempera-ture,jt is concluded that the affinity of the reactive dyes with triazine rings for cotton fabricsdecreases with a rise in temperature because of smal]or molecular weight and non-coplanaryof the dyes in comparison with direct dyes.In addition,bulky triazine rings are considered to .decrease the affinity of the reactive dyes for fabrics.The maximum dye uptake is consideredto be due to the amount of dyes adsorbed on fabrics and the reactivity of dyes adsorbed onfabrics and ce11u]ose which is affected by temperature and molecular structure of dyes.Further investigations are necessary to consider the effect of the molecular structures exceptdichlorotriazine rings on the reactivity of the dyes and col]u1ose.

REFERENCES

1. H_Zollinger Review of Textile Progress,11,215(1960).2_ A.Yabe and M.Hayashi,'Senryou Gaisetu'',Kouseikan,Tokyo,1979,p.l21.3_ S.Abeta and K.1mada,Dyeing Industry,32,pp.93 183,242,303.401,461,552,605(1984).4. Mitsubishi_Kasei Co_Ltd. and Nihon_Kayaku Co、Ltd, Kaisetsu-syo,Mikacion Dyes 4th Ed,''

1975、5_ H.Kanazawa,M_Watanabe,T.Nogi,and Y.0htaki,Sci.Rep.Fukushima Univ_38,45(198616. K.Kondo, Sensyoku noKagaku'',Kenpakusya,Tokyo,1977,p.119.7 W.Ingamells,H.H.Sumner and G.WiMams,J.Soc.Dyers Col.,78,274(1962).8. S_Horrabin,J.Chem.Soc.,4130(1963).9_ H.H.Sumner,B.Taylor,J.Soc_Dyers Col.,83,445(1967).10. A.Yabe and M.Hayashi,'Senryou Gaisetu'',Kouseikan,Tokyo,i979,p.99.11. N_Kuroki. Sensyoku Riron Kagaku'',Maki-syoten,Tokyo,1966,p,454_12_ H.H_Sumner and T.Vickerstaff,Me11iand Textileber.,42,1167(1961)_13. S.Abeta and K.Imada,Dyeing Industry,32,49(1984).14. H.Zo11inger,℃hflmie der Azofarbstoffe'',Basel,1958,p.280_