Indian Journal o f Fibre & Textile Research Vol. 26, December 2001 , pp. 425-431

Improving the dyeability of natural colorants on cotton by cationization

Seong-il Eorn" Text ile Division, Korean Agency for Technology and Standards, 2 Joong-ang dong, Kwa-cheon City, Kyeong-gi Do, Korea, 427 716

and

Dong-yoon Shin & Kee-jong Yoon Divi sion of Textile and Pol ymer Engineering, Dankook Univers ity, San 8, Han-nam Dong, Yong-san Gu , Seoul , Korea, 140 2 10

Received 19 No vember 1999; revised received 14 March 2000; accepted 3 May 2000

Cotton fabric was cat ionized wi th several cationizing reagents before dyeing with natura l colorants (Redwood. Gromwell, Cochineal, Goldthread and Amur cork tree) for improving its dyeability. The KlS value of cation ized cotton fab ric dyed with Redwood and Cochineal was higher than that of untreated one. In case of Gromwell , though the KlS value of the ca tioni zed fabric was higher than that of untreated one, the fabric showed poor levelness. Cati oni zation of cotton had no effect on the dyeability of Goldthread and Amur cork tree. It is observed that when the concentration of NaOH exceeds beyond a certain level, NaOH hydrolyzes the cationizing agent and the KlS values of dyed materials decrease. The optimum concentrations of NaOH in cationization have been determined for dyeings with different natural colorants.

Keywords: Cationi zation, Cotton, Dyeing, Natural colorants

1 Introduction Natural dyes are deep and soft in colour shades

compared to synthetic dyes . Besides, with the increase of the worldwide concern for the environment, the possibility of using natural dyes is being studied because natural dyes may overcome the defects of synthetic dyes such as harmfulness to human body, pollution and waste water. Accordingly, there have been active researches for the natural dyeingl.s. But it has been known that the natural dyes show very low dye exhaustion on cotton fibre compared to silk or wool, and that the satisfying results have not been obtained till now even though repeat dyeing or mordant treatment have been done to overcome this problem.

Several studies have been made on the cationi zation of cotton fibre because cationi zation enables the dyeability with acid dyes, improves the dyeing efficiency between direct dyes and acid dyes. and endows the anti-microbial propertl-II . But cationi zation has not been applied to natural dyeing. Generally, the commercial cati oni zing agents contain quaternary ammonium salts, so they have the functional groups to react with cotton fibres to cationi ze the surface.

"To whom all the correspondence should be addressed . Phone: 82-2-509-7405; Fax: 82-2-507-1924; E-mail: siul1l97@hanmail.net

In thi s study, natural dyes such as Redwood, Gromwell , Cochineal, Goldthread (Berberine) and Amur cork tree (Berberine) were used to dye cotton fabric. Cotton fabric was cationized by the commercial cationizing agents and dyed with these natural dyes to compare the dyeability of untreated and cationized fabrics. Also, the effect of the concentration of cationizing agent and sodiu m hydroxide on dyeability was studied. The structure of dye colorants which were used in this study are shown in Fig. 1.

Ji~ OH~O/

(\)

OH 0 OH

CH20H

- 0

OH OH lO?50H ? CH3)0 OH r ~ ........ OH

I \ OH '" '" OH

OH 0 ( tt)

)Yr(-....../~,P3 [~ CH3

OH 0

(ttt )

Fig. I-Chemi cal structures of natural colourants : I- Braziline (Redwood), II-Carminic acid(Cochineal), 111-Shikonin(Gromwell) and IV-Berberi ne(Amur cork tree and Goldthread)

426 INDIAN 1. FIBRE TEXT. RES., DECEMBER 2001

2 Materials and Methods

2.1 Materials Plain weave cotton fabrics having the following

specifications were used warp density, 28 threads/em; weft density, 27 threads/cm; weight 105 g/m2

; warp count, 30s; and weft count 36s. Redwood, Gromwell, Goldthread, Amur cork tree and Cochineal of commercial grade were used. Two cationizing agents, CA U (Shinyoung Chern. Ltd, Korea) and CAs (Oaeyoung Chern. Ltd, Korea), of commercial grade were used. Triton X-lOO, methanol, sodium hydroxide and other reagents used were of first grade.

2.2 Methods

2.2.1 Extraction of Colorants Each of the dyeing materials (I OOg) and methanol

(700ml) were put in a one-liter round-bottom flask fitted with a reflux condenser, refluxed for I h at 67°C, and then filtered to yield colorant extracts. This procedure was repeated 2-3 times and the extracts thus received were mixed together to be experimented. Gromwell was different in colour at this extraction temperature and, therefore, it was extracted at 40°C also. Cochineal was used in the powder state.

2.2.2 Treatment with Cationizing Agent and Dyeing Procedure

Colorant extracts and Cochineal were dyed on cotton fabric with the vanatlon of colorant concentration, dyeing temperature(40-70°C) and dyeing period(20-120 min).

Cationization of cotton fabric was done as shown in Scheme 1 by the dipping method using both cationizing agents (CA U and CAs) and NaOH. The chemical constitutions of the two commercial products from different companies are not completely known. However, it is known that these products have -CH(OH)CH2C1 and quarternary ammonium salt groups and the difference between the two products is assumed to be the number of the methylene linkages. For CA u, the cationizing conditions were 80°C & 40 min and for CAS, 60°C & 40 min and 80°C & 10 min. When CA U was used as a cationizing agent, Triton X-100 was also added as a penetrating agent. Cotton fabric treated by cationizing agent was succeedingly dyed by Redwood, Gromwell(high temp. extract! low temp. extract), Cochineal, Goldthread and Amur cork tree. At this state, dyeing was carried out at 60°C for 60min.

i Cotton 2g Triton X·IOO 2- 5g11

N.OH 30glt CAu IOOgil

i Cotton 2& NaOH 2Q--50gll CAS 3Q--IOOgll

4flmin 80°C

Wash

10 min

Wash

Scheme I-Profile of cationizing cotton fabric with CA U and CAs

2.2.3 Measurement of Dye Adsorption and Colour Spectrophotometer (Colour Eye 3000, Macbeth,

U.S.A.) was used to measure the reflectance and adsorption concentration at surface (K/S) of dyed cotton fabrics, and'cie to munsell ' program was applied for the achievement of H, V/ C and ISCC­NBS colour name.

3 Results and Discussion 3.1 Dyeability According to Colorant Concentration, Dyeing

Temperature and Dyeing Time Fig. 2 shows the K/S values of cotton fabrics dyed

by the extracts of Redwood, Gromwell, Goldthread and Amur cork tree and by the powder of Cochineal according to Table 1. With the increase in the concentration of dyes, the K/S value increased gradually, and in cases of Amur cork tree and Redwood, higher K/S values were obtained compared to those for other dyes. But all K/S values were very low « 1.5) and this phenomenon seems to be caused by the weak interaction force between natural dyes and cotton fibre. Conferring these results , the concentration of each dye for the test of the dyeability according to dyeing time and dyeing temperature was defined as 10, 8, 25 and 30ml extracts for Redwood, Goldthread, Amur cork tree and Gromwell, and as 5% o. w.f for Cochineal.

SEONG-IL EOM el al.: DYEABILITY OF NATURAL COLORANTS ON COTTON 427

Figs 3 and 4 show the KlS values of the cotton fabrics dyed by Redwood and Gromwell extracts (70°C) with the variation in dyeing temperature and dyeing time. In case of Redwood, the fabrics dyed at 400 e and 500 e showed higher KlS values than those dyed at 600 e and 70oe, and no more improvement in KlS value took place after the dyeing time of 40 min. But as a whole, the KlS showed low values below 2. Gromwell showed higher KlS value at higher dyeing temperature like Redwood, and the influence of

2.0 r----=:---------~

1.5

~ 1.0

0.5

234 5 S Concentration No.

Fig.2-KlS values of colton fabric dyed with natural dyes at various concentrations (Dye concentration level is in accordance with Table I)

3.0

-- 40 'C 2.5 -- 50 'C

-&- 60 'c 2.0 --?- 70 'C

(f) 1.5 ~ ~

1.0

~ 0.5

OL--L_L-_L_~~_~~

o 20 40 SO 80 100 120 140

Time, min

Fig. 3- KlS values (at 500nm) of colton fabric dyed wi th Redwood according to dyeing time at various temperatures

dyeing time was not so great. The KlS values were also very low « 1).

Fig. 5 shows the KlS values of the cotton fabrics dyed by Gromwell extacts (40°C) with the variation in dyeing temperature and dyeing time. With the increase in concentration of dyes and dyeing temperature, the KlS value tends to increase. But as a whole, the KlS values were very low « I) which implies that the dyeability of Gromwell extact (40°C) to cotton is very poor like Gromwell extract (70°C).

1.5 r----------~

-40 'C

-- 50'C -/';- so'c

1.0 __ 70'C

0.5 t--

OL-_L_~~ _ _L_L__L~

o 20 40 SO 80 100 120 140

Time . min

Fig. 4-- KlS values (at 600nm) of colton fabric dyed with Gromwell according to dyeing time at various temperatures

1.0 r----------~

- 40°C

0 .8 -- 50°C -A- 60°C --?- 70°C

O.S (f)

~ 0.4

0.2

OL--L-~~_~~ _ _L~

o 5 10 15 20 25 30 35

Concentration. mIt

Fig. 5-KlS values (at 520nm) of cotton fabric dyed with Gromwell ex tract (40°C) at various concentrat ion levels and temperatures

Table I- The condition of natural dye extracts for dyeing

Dye Redwood Goldthread Amur cork tree Gromwell Cochineal cone. no. ml ml ml ml (o.w .f)

I I I 2.5 5 0.5

2 2 2 5 10

3 4 4 10 15 2

4 6 6 15 20 3

5 8 8 20 25 4

6 JO 10 25 30 5

428 INDIAN 1. FIBRE T EXT . RES. , DECEMBER 2001

Figs 6 and 7 show the K/S values of cotton fabrics dyed by the extracts of Goldthread and Amur cork tree with the variation in dyeing temperature and dyeing time. In these cases, unlike for Redwood and Gromwell, it was more effective to dye at lower temperature because the KIS values of fabrics dyed above 60°C were lower than those of fabrics dyed at 40-50°C. Dyeing time was not a key factor for K/S values. But as a whole, the dyeability was very low, showing K/S values below ] .5 (Goldthread) and below 1 (Amur cork tree).

Fig. 8 shows the K/S values of cotton fabrics dyed by Cochineal with the variation in dyeing temperature and dyeing time. No evident tendencies were acquired with the variation in dyeing temperature and the dyeing time, and the dyeability was very low, showing K/S values generally below 0.5.

3.2 Treatment by Cationizing Agents Among natural dyes, Redwood (colorantbrazilin),

Gromwell (colorant shikonin) and Cochineal (colorantcarminic acid) are dyes for red and purple

2.5,------------,

----- 40 'c -- 5O 'C

2.0 -6- 60 ' C - y- 70 ' C

~ 1.5

1.0

o. 5 '-----'--_.L..-~ _ _'____'__ _ _'_---1

o 20 40 60 80 100 120 140

Time. min

Fig. 6- KJS values (at 440nm) of cotton fabric dyed with Goldthread according to dyei ng time at vari ous temperatures

1.5 ,------------,

- - 40 ' C -- 50 ' C -6- 60'C

1.0 -T- 70 ' C

0. 5

O'___L~'___L~L_~~_~

o 20 40 60 80 100 120 140

Time, min

Fig. 7-KJS values (at 440nm) of cotton fabri c dyed with Amur cork tree according to dyeing time at various temperatures

colours and they contain in their structure not only carboxy groups but also aromatic hydroxy groups to function as water-soluble groups. These are hydrolyzed in water to anions and because the surface of cotton is also anionic in water, repulsive force can react between dyes and fibres and consequently dyes cannot easily be adsorbed to cotton fi bre. But, if the surface of cotton fibre is cationized, then the ionic attraction can occur between dyes (an ions) and fibres (cations) and dyeability will surely increase.

Fig. 9 and Table 2 show the K/S values, H, Y, C and ISCC-NBS colour names for the cotton fabrics treated with cationizing agent (CA u) and then dyed by Redwood, Gromwell (high temp. and low temp extracts), Cochineal, Amur cork tree and Goldthread.

In cases of Redwood and Cochineal, the cationized cotton fabrics showed drastic increase in KIS values

1.5 ,-------------,

----- 40 ' C -- 50 ' C ---Ir- 60 'C

1.0 -T- 70 ' C

0.5

O~~--'--~-~~-~~

o 20 40 60 80 100 120 140

Time. min

Fig. 8-KJS values (at 500nm) of cotton fabric dyed with Cochineal according to dye ing time at various temperatures

12r----------------------,

10

8

~ 6

4

A B

c::J Untreated _ Treated

C 0 E F

Fig. 9- KJS values of cotton fabrics dyed with natural colorants after treatment wi th cati oni zing agen t CA U [A: Redwood. B: Cochineal. C: Gromwell (70DC), D: Gromwell (40DC). E: Amllr cork tree, F: Goldthreadl . (Dyeing condi ti on: 6Q°C x 60min . Dye concentration : 10, 8, 25 and 30 ml extrac ts for Redwood , Goldthread, Amur cork tree, Gromwe ll and 5 % o . w.f for cochineal)

SEONG-IL EOM et al.: DYEABILITY OF NATURAL COLORANTS ON COTTON 429

Table 2-ISCC-NBS colour names for the cotton fabrics cationized (CA") and dyed by natural dyes

Dye Cationizing K/S H agent (Hue)

Redwood Nil 0.7 5.80R CA" 4.9 7.84R

Gromwell Nil 0.2 6.43RP (70°C) CA" 3.4 2.90PB

Gromwell Nil 0.5 0.34R (40°C) CA" 1.6 7.12RP

Amur cork tree Nil 0.5 8.05Y CA" 0.5 0.06Y

Goldthread Nil 0.9 4.04Y CA" 0.5 3.04Y

Cochineal Nil 0.3 0.66R CA" 10.2 I.76R

compared to that of untreated cottons and the coloured products showed more uniform dyeing property. The K/S values of Cochineal, especially, were increased more than 30 times to be the first in cationizing effect among the natural dyes examined. Generally , cotton fibres are known to make anionic appearance in aqueous medium. When the cationizing agent is treated to cotton fibre, it reacts with cotton fibre (Scheme 2) to make quarternary ammonium salt on the surface of fibre and enables union of cationized cotton fibre with anionic dye by ionic bondage. In case of Cochineal, the carboxylic groups (-COOH) contained in the colorant carminic acid hydrolyze to carboxylic acid ion (-COO-) to figure out anions. As a result, the cationized cotton fibres bond with dye anions by ionic bonds to increase the dye adsorption and the K/S values.

In case of Redwood, the colorant braziline contains aromatic hydroxy groups, which are weak acid in its structure. It can possibly become anionic in aqueous solution, like in the case of Cochineal. So more dyes are thought to adsorb to cationized cotton fibres than untreated fibres. But the acidity of the carboxylic acid which exists in Cochineal is bigger than the acidity of the carboxylic acid which exists in aromatic hydroxylic acids of Redwood. Therefore, the ionic bonding strength of Cochineal to cationized cotton fibre is more stronger than that of Redwood and that the increase in K/S values seem to be bigger.

In case of the dyeing by the extracts of Gromwell at both higher and lower temperatures, the K/S values of the cationized/dyed fabrics increased when compared with untreated fabrics, but such a fault as uneven dyeing or dyeing defects tended to take place. On the other hand, the dyed fabrics by the extracts of Amor

V C Colour name (Value) (Chroma)

7.24 5.28 Moderate pink 5.29 8.77 Moderate reddish orange

7.76 1.07 Light purpli sh gray 4.08 1.13 Dark bluish gray

6.96 2.43 Grayish pink 5.23 2.76 Grayish purple

8.74 3.21 Pale greenish yellow 8.02 2.53 Pale orange yellow

8.45 5.04 Light yellow 8.24 2.67 Pale yellow

7.68 3.95 Moderate pink 3.35 6.08 Dark red

Cen-OH + NaOH +

Cat ionizing reagent

+ NaCI

Cationozed Cotton Fabric

Scheme 2-Probable reaction of cationizi ng reagent with cotton fabric

cork tree and Golcl,thread showed no change in KlS values, verifying the no positive effect of cationizing agents. This phenomenon seems to occur because of the repulsice forces between the cationized cotton fibres and the cationic dye of berberine of the colorants of Amur cork tree and Goldthread operate to make dyes difficult to penerate into fibre structure.

Fig. 10 and Table 3 show the KlS values, H, VI C and ISCC-NBS colour names of cotton fabrics cationized by cationizing agent (CAs) at various concentrations and then dyed by Redwood, Gromwell (high temp. and low temp. extracts) and Cochineal. In case of Redwood and Cochineal, with the increase in concentration of the cationizing agent the KlS values of the dyed fabrics increased greatly, and the coloured fabrics showed the even colours, proving that the improvement in dyeability by cationization is very good. In case of Gromwell , with the increase in the concentration of the cationizing agent the KlS values of the dyed fabrics tend to increase but the defects of uneven dyeing and dye-defects show the same tendencies as the fabrics treated by CA u. It seems that

430 INDIAN J. FIBRE TEXT. RES ., DECEMBER 2001

Table 3-ISCC-NBS colour names for the cotton fabrics cationized (CAs) and dyed by natural dyes

Dye CAs K/S H Cone., gil (Hue)

Redwood 0 0.9 6.88R 30 4.5 4.40R 50 4.8 9.14R 80 8.6 9.36R 100 10.1 9.85R

Gromwell 0 0.1 8.14R (70°C) 30 1.3 9.23PB

50 2.0 0.32P 80 3.2 3.82P 100 3.4 6.12P

Gromwell 0 0.3 1.69R (40°C) 30 1.2 5.4IRP

50 1.7 6.58RP 80 2.7 7.22RP 100 3.1 8.81RP

Cochineal 0 0.3 3.0 1R 30 3.2 1.8 1R 50 5.8 2.61R 80 7.0 8.50RP 100 8.0 9.82RP

12

A 10

8

(f)

~ 6

4

2

20 40 60 80 100

Cationizing Agent ,gil

Fig. 10-- K/S values of cotton fabric dyed with natural colorants after treatment with various cationizing agent (CN) contents [A: Redwood, B: Gromwell (70°C), C: Gromwell (40°C), D: Cochineal]

with the increase in concentration of cationizing agent, more dye-adsorption sites are formed on the surface of the cotton fibres to increase the K/S values of dyed fabrics.

Fig. I I shows the K/S values of the cotton fabrics first cationized by cationizing agent (CAs) with the variation of NaOH concentrations and then dyed by Redwood, Gromwell (high temp . extracts/low temp. extrac ts) and Cochineal. As a whole, with the increase in the concentration of NaOH used in cationization, the K/S values of dyed products tend to increase, but in case of Redwood and Cochineal at above 20 gil

V C Colour name (Value) (Chroma)

7.02 5.70 Moderate yellowish pink 4.53 6.01 Grayish red 4.95 6.87 Grayish reddish orange 4.27 7.09 Dark reddish orange 4.01 6.64 Moderate reddish brown

8.26 0.78 Pinksh gray 5.46 1.12 ·Purplish gray 4.89 1.42 Purpli sh gray 4.28 1.50 Dark purpli sh gray 4.20 1.52 Grayish purple

7.37 2.30 Grayish pink 5.56 2.14 Pale purple 5.14 2.41 Grayish purple 4.49 2.57 Grayish purple 4.32 2.86 Grayish purple

7.79 3.63 Moderate pink 4.92 6.00 Grayish red 4.24 7.03 Moderate red 3.58 6.09 Grayish purplish red 3.50 6.59 Dark purplish red

10

8

6 (/)

~ 4

2

10 20 30 40 50 60

NaOH ,g/l

Fig. 11- K/S values of cotton fabric dyed with natural colorants after treatment with CAs according to NaOH concentration [A: Redwood, B: Gromwell (70°C), C: Gromwell (40°C), D: Cochineal]

concentration of NaOH, the K/S decreased again , showing that the optimum concentration of NaOH for cationization is 20 gil. Gromwell also showed similar phenomena to verify the optimum concentrations of NaOH (30 gil) for higher temp. extracts and for lower temp extracts (20 g/l) . Generally speaking, when the cationizing agents with the functiona l groups of 3-chloro-2-hydroxy propyl groups react with cotton fibres, it is said that these agents tend to form the oxyran rings in the presence of alkalis like NaOH and the rings of these oxyrans are broken by NaOH to form the hydroxy groups of cotton fibres I2

-14

.

SEONG-IL EOM et al.: DYEABILITY OF NATURAL COLORANTS ON COTTON 431

Accordingly, there exists the optimum concentration of NaOH and above that concentration it hydrolyzes the cationizing agent to decrease the K/S values of dyed fabrics.

4 Conclusions 4.1 Redwood and Gromwell showed higher K/S

values with higher dyeing temperature and Amur cork tree and Goldthread conversely showed higher K/S values with lower dyeing temperature, but Cochineal was not influenced by dyeing temperature.

4.2 All the K/S values of the products dyed by natural dyes were below 1.5, showing the poor dyeability of natural dyes to cotton fabrics.

4.3 In case of Redwood and Cochineal, the K/S values of cationized and dyed fabrics increased drasticly when compared with those of the non­cationized and dyed fabrics and the coloured fabrics showed the uniform colours to represent the improvement in the dyeability of cotton fibres by cationization. In case of Gromwell, the dyeability was not sufficient because uneven dyeing took place even though K/S values by cationization increased. Amur cork tree and Goldthread showed no effect of cationizing agents.

4.4 With the increase in the concentration of cationizing agent used, the K/S values of dyed

products increased and the optimum concentrations of NaOH were 20 gil for Redwood, Cochineal and Gromwell (low temp. extract) and 30 gil for Gromwell (high temp. extract).

Acknowledgement This study was accomplished by the 1997 fund of

Korean Ministry of Commerce, Industry and Energy .

References I Smith R & Wagner S, Arn Dyest Rep, 23 (1991) 32.

2 Padhye R N & Raphi 0, Text Dyer Printer, (1990) 27.

3 Garg A & Shinde S, Colourage, (1991) 50. 4 Sayeed M A, Islam N & Hossain I, Indiall Text J, (1990)

114.

5 Miyamatsu H, Kawai 0, Morita K & Kubo M, US Par 5,221,289 (to Hamamatsu, Japan), June 1993.

6 Burkinshaw S M, Lei X P & Lewis 0 M. J Soc Dyers Colour, 105 (1989) 391.

7 Lewis 0 M & ·Lei X P, J Soc Dyers Colour, 107 (1991 ) 102. 8 Wu T S & Chen K M, J Soc Dyers Colour, 108 (1992) 388. 9 Lewis 0 M, J Soc Dyers Colour, 109 (1993) 357.

10 Wu T S & Chen K M, J Soc Dyers Colour, 109 (1993) 365.

II Kamel M, Kamel M M, Youssef B M & Shokry G M, J Soc Dyers Colour, 114 (1998) 101.

12 Rupin M, Text Chern Color, 8 (1976) 139. 13 Fukuoka S, Sen-i Gakkaishi, 42 (1986) 312. 14 Kim Y J, Song K G & Ko S W, J Korean Fiber Soc , 32

(1995) 562.