超声波染3

The clearing of poly(lactic acid)ﬁbres dyed with disperse dyes

using ultrasound:Part 3

S.M.Burkinshaw *,D.S.Jeong

The University of Leeds,Leeds,LS29JT,United Kingdom

Received 29August 2006;accepted 22June 2007

Available online 6July 2007

Abstract

The effectiveness of an ultrasound-assisted,ECE detergent-based aftertreatment was found to be little improved by the use of temperatures higher than 60 C,durations longer than 5min and detergent concentrations greater than 2g l À1.As little difference was found between the effectiveness of the detergent aftertreatment and that of the traditional reduction clearing process,it appears that,in terms of fastness and colour,the Na 2CO 3and Na 2S 2O 4used in the reduction clearing of disperse dyed PLA ﬁbre can be replaced with a treatment using 2g l À1ECE detergent in the presence of ultrasound.This a

lternative aftertreatment of dyed PLA may offer a reduced risk of hydrolytic damage to the ﬁbre as well as reduced chemical consumption and also generate a more environmentally acceptable efﬂuent than reduction clearing.Ó2007Elsevier Ltd.All rights reserved.

Keywords:Ultrasound;Disperse dyes;PLA ﬁbre;Dyeing;Fastness

1.Introduction

A reduction clearing treatment is needed to remove surplus dye and auxiliaries from poly(lactic acid)(PLA)which has been dyed with disperse dyes.Owing to the hydrolytic sensi-tivity and T g of PLA,reduction clearing comprises,typically,of submitting the rinsed,dyed material to treatment for 15min at 60 C in an aqueous bath containing 1.5e 2g l À1Na 2CO 3and 2g l À1Na 2S 2O 4[1,2].However,the use of sodium di-thionite produces environmentally unfriendly efﬂuent which,in the case of azo disperse dyes,may also contain aromatic amines [3].In this latter context,together with the susceptibil-ity of PLA to hydrolysis,it was decided to establish whether or not a clearing treatment could be developed for dyed PLA which offered a low risk of hydrolytic damage and which con-stituted a more environmentally friendly approach as well as reduced chemical usage.To this end,the decision was made to determine if the well-known abilities of ultrasound (process

acceleration and the attainment of similar/improved results un-der less extreme conditions)would enable both the Na 2CO 3and Na 2S 2O 4used in reduction clearing to be replaced by an aftertreatment with a common detergent formulation.

In the ﬁrst part of this paper [4],three types of clearing pro-cess namely water,reduction clearing and ECE detergent,were used to aftertreat six disperse dyes on PLA ﬁbre.Al-though reduction clearing imparted the greatest changes to both the colour strength and colour of the dyeings,treatment with ECE detergent also removed surplus dye and improved the chroma of the dyeings;treatment with water had very little effect on the colour strength and colour of dyeings,even in the presence of ultrasound.It was found that both depth of shade reduction and colour change were greater when aftertreatment was carried out at 60 C rather than at 50 C and that ultra-sound neither impaired nor overly enhanced the effectiveness of either the ECE detergent or the reduction clearing pro-cesses.The second part of the paper [5]revealed that reduction clearing was slightly more effective than ECE detergent in im-proving wash fastness whilst ECE detergent imparted higher level of rub fastness;water had little effect on fastness to both rubbing and repeated washing.Both wash and rub

*Corresponding author.Tel.:þ441133433722;fax:þ441133433740.E-mail burkinshaw@leeds.ac.uk (S.M.Burkinshaw).0143-7208/$-see front matter Ó2007Elsevi

doi:10.1016/j.dyepig.2007.06.006

Dyes and Pigments 77(2008)387e

394

www.elsevier/locate/dyepig

fastness were higher when aftertreatment had been carried out at60 C rather than at50 C.Ultrasound enhanced the effec-tiveness of both reduction clearing and ECE detergent in terms

of rub fastness and enabled a modiﬁed reduction clearing pro-cess to be used that employed lower amounts of alkali and reducing agent.

Thisﬁnal part of the paper concerns the effects of varying the amount of ECE detergent used as well as different times and temperatures of aftertreatment on the fastness of three disperse dyes to both rubbing and repeated washing.

2.Experimental

2.1.Materials

Scoured,poly(lactic acid)knitted fabric(which was ob-tained from NatureWorks LLC)described earlier[1]was used.Commercial samples of the three disperse dyes shown in Table1were generously

supplied by Clariant and were used without puriﬁcation;the three dyes were selected for use on the basis that they were representative of contemporary disperse dyes.ECE detergent was obtained from the Society of Dyers and Colourists;all other chemicals were of general laboratory grade supplied by Aldrich.

2.2.Dyeing

Dyeings of1%and2%omf were produced,using the equipment described earlier[1]following the method shown in Fig.1;the pH was adjusted using acetic acid/sodium acetate buffer.The dyeings were rinsed thoroughly in tap water and allowed to dry in the open air.2.3.Aftertreatments

2.3.1.Reduction clearing

Dyeings were reduction cleared,in the absence of ultra-sound,using the equipment described earlier[2]following the method shown in Fig.2.

2.3.2.ECE detergent

Dyeings were treated using2,4and8g lÀ1ECE detergent, at60,70and80 C for5,15and30min,using the method shown in Fig.3,employing the equipment described before [2]in the presence of ultrasound p

rovided by a Grant MXB22.

2.4.Colour measurement

All measurements were carried out using the equipment and procedures described earlier[1].

2.5.Wash fastness

改革开放30年纪实The wash fastness of the dyed samples was determined us-ing the ISO CO6/B2S(50 C)test method but was modiﬁed such that dyeings were subjected toﬁve,consecutive wash tests and,at the end of each wash test,the washed sample was rinsed thoroughly in tap water(but was not dried)and a fresh sample of SDC multiﬁbre strip was used to assess the extent of staining for each of theﬁve wash tests[2].

2.6.Rub fastness

The dry and wet rub fastness of the dyed PLA samples were determined using the ISO105:X12test method[2].

30'

50ºC

fabric

pH 4.5

2% omf dye

1 gl-1Levegal DLP

2 gl-1湖南大学学报

Ludigol AR

Fig.1.Dyeing method.

15'

1.5 gl-1 Na2CO3

2 gl-1 Na2S2O4

50ºC

60ºC

2ºC min-1

Fig.2.Reduction clearing method. Table1

Dyes used

Commercial name ic name Energy level Supplier

Foron Brilliant

Red E-2BL200

Disperse Red60Low Clariant

Foron Blue E-BL200Disperse

Blue56Low

Foron Yellow SE-FL Disperse Yellow42Medium

5', 15' or 30'

60ºC, 70ºC or 80ºC

2, 4 or 8 gl-1 ECE detergent

50ºC

2ºC min-1

Fig.3.Aftertreatment using detergent.

388S.M.Burkinshaw,D.S.Jeong/Dyes and Pigments77(2008)387e394

3.Results and discussion

Dyeings of 2%omf were aftertreated with three concentra-tions (2,4and 8g l À1)of ECE detergent for three different times (5,15and 30min)and at three temperatures (60,70and 80 C)and the effects of these treatments on the colour,rub fastness and fastness to repeated washing at 50 C were assessed.

Table 2shows the extent of staining,by vagrant dye,of multiﬁbre strip that occurred during the ﬁve,consecutive wash tests as well as the shade change obtained during repeated washing in the cases of the three disperse dyes.It is evident that each of the three dyes displayed different levels of fastness to repeated washing at 50 C,as measured in terms of the levels of staining of the adjacent multiﬁbre strip im-parted by dye which had been removed from the dyeing during washing.In this context,lowest fastness was obtained for 2%omf dyeings of C.I.Disperse Blue 56,as shown by the high extent of staining obtained for the adjacent nylon 6,6ﬁbre and the moderate staining of the diacetate,polyester and cot-ton components;such staining can be attributed to the higher substantivit

y of the dye towards these ﬁbre types while the lower extent of staining observed for the adjacent acrylic and wool components arises from the inherent low substantiv-ity of the disperse dye towards such ﬁbre types.It is apparent that the extent of staining achieved at the end of the ﬁrst wash test was much worse than that obtained at the end of the ﬁfth wash test.In view of the well-known,progressive nature of the removal of dye and the redeposition of vagrant dye that com-monly occurs during washing,these ﬁndings were expected and can be attributed to the detergent aftertreatment having not removed all surplus dye,which was then removed during successive washing.

In terms of the effect of the temperature used for aftertreat-ment on wash fastness,it is clear that for each of the three dyes used,there was very little difference in the fastness of the dye-ings after the ﬁrst wash test.Furthermore,it is clear that the level of fastness achieved after the ﬁfth wash test,for each of the three dyes used (as judged by the staining of adjacent ﬁbres),was unaffected by the temperature at which aftertreat-ment with the detergent had been carried out.Table 3reveals that the rub fastness of the C.I.Disperse Blue 56and C.I.Dis-perse Yellow 42dyeings were very slightly lower when after-treatment had been carried out at 60 C and that there was no difference between the results obtained for aftertreatments at 70and 80 C.The corresponding colorimetric data for the dyein

gs (Table 4)which had been subjected to ﬁve wash tests in the presence of ultrasound using 2g l À1ECE detergent,shows that repeated washing lowered the depth of shade of each of the dyeings,as shown by the lower f (k )values of the ﬁve times washed samples;this is attributable to the wash tests having removed surface dye from the dyeings.Also,it is

Table 2

Effect of temperature on wash fastness of 2%omf dyeings (15min;2g l À1ECE detergent)Dye Temp.( C)No.of washes Change in shade Diacetate Cotton Nylon Polyester Acrylic Wool C.I.Disperse Red 60

60154534e 555555555557015453e 44e 5555555555580

153e 4534e 55555555555C.I.Disperse Blue 56

60153e 44e 52e 34e 55555554e 555570153e 44e 52e 34e 55555554e 555580

153e 44e 524e 55555554e 5555C.I.Disperse Yellow 42

6015553e 4555555555557015553e 45555555555580

155535555

Table 3

Effect of temperature on rub fastness of 2%omf dyeings (15min;2g l À1ECE detergent)Temp.( C)Dry

Wet

Dry

Wet

Dry

Wet

Staining Shade change Staining Shade change Staining Shade change Staining Shade change Staining Shade change Staining Shade change

C.I.Disperse Red 60

C.I.Disperse Blue 56 C.I.Disperse Yellow 42603e 44e 5553e 44e 55544e 54e 54e 5703e 44e 55544e 5554e 555580

3e 4

4e 5

389

S.M.Burkinshaw,D.S.Jeong /Dyes and Pigments 77(2008)387e 394

Table4

Effect of temperature on colorimetric data for2%omf dyeings(15min;2g lÀ1ECE detergent)

Temp.( C)No.of washes L*a*b*C*h f(k)L*a*b*C*h f(k)L*a*b*C*h f(k)

C.I.Disperse Red60 C.I.Disperse Blue56 C.I.Disperse Yellow42

60055.459.612.560.911.933.740.57.5À40.441.1280.547.267.531.956.164.160.633.1 555.760.012.660.811.733.240.87.8À40.741.5280.946.268.231.656.164.460.631.9 70055.458.712.360.011.933.941.17.3À40.240.9280.245.168.530.655.062.960.930.3 555.558.812.260.111.733.641.57.4À40.140.8280.443.768.331.355.964.160.730.1 80055.859.212.460.511.833.241.07.4À40.341.0280.445.468.630.755.063.660.929.7 556.159.012.360.311.732.341.47.7À40.541.2280.444.168.930.855.463.460.929.5 Table5

Effect of time on wash fastness of2%omf dyeings(60 C;2g lÀ1ECE detergent)

Dye Time(min)No.of washes Change in shade Diacetate Cotton Nylon Polyester Acrylic Wool

C.I.Disperse Red605153e452e34e555 55555555 15154534e555 55555555 30154534e555 55555555

C.I.Disperse Blue56515342455 55555555 15153e44e52e34e555 55554e5555 30153e44e52e34e555 55554e5555

倾慕系列

C.I.Disperse Yellow42515553e4555 55555555 1515553e4555 55555555 3015553e4555 55555555

Table6

Effect of time on rub fastness of2%omf dyeings(60 C;2g lÀ1ECE detergent)

矩阵键盘Time(min)Dry Wet Dry Wet Dry Wet Staining Shade change Staining Shade change Staining Shade change Staining Shade change Staining Shade change Staining Shade change

C.I.Disperse Red60 C.I.Disperse Blue56 C.I.Disperse Yellow42

534553e44e55544e54e54e5

153e44e5553e44e55544e54e54e5

303e44e55544e55544e54e55

Table7

Effect of time on colorimetric data for2%omf dyeings(60 C;2g lÀ1ECE detergent)

Time(min)No.of washes L*a*b*C*h f(k)L*a*b*C*h f(k)L*a*b*C*h f(k)

农民频道自娱自乐C.I.Disperse Red60 C.I.Disperse Blue56 C.I.Disperse Yellow42

5055.558.512.159.711.633.340.37.2À39.940.6280.347.768.030.754.762.760.630.6 555.459.112.560.912.234.340.48.0À40.641.4281.647.268.231.656.264.560.732.0 15055.459.612.560.911.933.740.57.5À40.441.1280.547.267.531.956.164.160.633.1 555.760.012.660.811.733.240.87.8À40.741.5280.946.268.231.656.164.460.631.9 30055.158.712.360.011.834.741.17.3À40.341.0280.245.168.230.855.063.160.730.6 555.459.212.460.612.034.440.87.8À40.641.3280.845.968.331.455.964.160.931.4 390S.M.Burkinshaw,D.S.Jeong/Dyes and Pigments77(2008)387e394

evident that repeated washing had little,if any effect on the colour (hue and chroma)of the dyeings.In terms of the effect of temperature of aftertreatment on the dyeings before wash testing,the data in Table 4show that generally,colour strength decreased with increasing temperature,the colour of the dye-ings was largely unaffected by a change in temperature at which the aftertreatment had been carried out.

In the context of the effects of the duration of the aftertreat-ment upon fastness,Table 5shows that in the cases of C.I.Dis-perse Red 60and C.I.Disperse Yellow 42,the staining of adjacent materials was the greatest when aftertreatment had been carried out for 5min although identical levels of staining were obtained in the cases of 15and 30min treatment.Table 5also shows that the level of fastness achieved after the ﬁfth wash test,for each of the three dyes used (as judged by the staining of adjacent ﬁbres),was unaffected by the duration of the aftertreatment.Table 6reveals that the rub fastness of the C.I.Disperse Red 60dyeing was slightly lower when after-treatment had been carried out for 5min but,signiﬁcantly,there was no difference between the results obtained when aftertreatment had been carried out for 15and 30min,for each of the three dyes used.The corresponding colorimetric data for the dyeings (Table 7)show that the duration of after-treatment had little,if any,effect on the depth of shade and colour of the dyeings,both before and after repeated wash test-ing in the cases of C.I.Disperse Red 60and C.I.Disperse Yel-low 42.The colour strength of dyeings of C.I.Disperse Blue 56were reduced to a small extent by aftertreatment for 30min,although the colour of the dyeings was unaffected by the duration of aftertreatment.

Increasing the concentration of ECE detergent from 2to 4g l À1slightly reduced the level of staining of adjacent mate-rials achieved after the ﬁrst wash test,for each of the three dyes used,but had no ef

fect on the fastness of the ﬁve times washed dyeings (Table 8);further increase in detergent con-centration to 8g l À1had no effect on the fastness of either the ﬁrst or ﬁfth washed dyeings.Although an increase in the amount of detergent had no effect on rub fastness (Table 9),increased amounts of detergent lowered the colour strength of dyeings achieved for C.I.Disperse Yellow 42,both before and after repeated washing (Table 10).

As mentioned,because of the hydrolytic sensitivity and T g of PLA,disperse dyeings on the ﬁbre are reduction cleared for 15min at 60 C in an aqueous bath containing Na 2CO 3and Na 2S 2O 4.The aims of this work were to establish whether or not an alternative aftertreatment to reduction clearing could be developed for dyed PLA which offered a low risk of hydro-lytic damage,consumed few chemicals and which generated a more environmentally acceptable efﬂuent.The colour and fastness results described thus far indicate that the effective-ness of the detergent-based aftertreatment was little improved,if at all,through the use of temperatures above 60 C,times in excess of 15min and detergent concentrations greater than 2g l À1;furthermore,in the context of the aims of this work,

Table 8

Effect of detergent concentration on wash fastness of 2%omf dyeings (60 C;15min)Dye ECE deterge

nt (g l À1)No.of washes Change in shade Diacetate Cotton Nylon Polyester Acrylic Wool C.I.Disperse Red 60

2154534e 555555555554154e 5534e 555555555558

154e 553e 44e 55555555555C.I.Disperse Blue 56

2153e 44e 52e 34e 55555554e 555541544e 52e 34e 55555554e 55558

1544e 52e 34e 55555554e 5555C.I.Disperse Yellow 42

215553e 455555555555415554555555555558

155545555

kis2009Table 9

Effect of detergent concentration on rub fastness of 2%omf dyeings (60 C;15min)ECE detergent (g l À1)Dry

Wet

Dry

Wet

Dry

Wet

Staining Shade change Staining Shade change Staining Shade change Staining Shade change Staining Shade change Staining Shade change

C.I.Disperse Red 60

C.I.Disperse Blue 56 C.I.Disperse Yellow 4223e 44e 5553e 44e 55544e 54e 54e 543e 44e 5553e 44e 55544e 54e 558

3e 4

4e 5

3e 4

4e 5

391

S.M.Burkinshaw,D.S.Jeong /Dyes and Pigments 77(2008)387e 394

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