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Preparation and dispersion properties of water-soluble polyethylene glycol-dimethyl 5-sulfoisophthalate sodium salt polyester surfactants
Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178 www.elsevier.com/locate/colsurfa
Preparation and dispersion properties of water-soluble polyethylene glycol-dimethyl 5-sulfoisophthalate sodium salt polyester surfactants Li-Huei Lin, Hsin-Jiant Liu *, Jiunn-Jer Hwang Department of Chemical Engineering, Van Nung Institute of Technology, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City 320, Taiwan, ROC Received 25 January 2002; accepted 31 May 2002
Abstract ¯ n /400 /2000) and dimethyl 5The reaction of polyethylene glycol (PEG, number-average molecular weights M sulfoisophthalate sodium salt (SIPM) produced a series of water-soluble polymeric surfactants. The structure of these surfactants was confirmed by IR, 1H-NMR and elemental analysis. These polymeric surfactants have been found to exhibit excellent pH buffer capacity and dispersant properties in disperse dye system. The experimental results indicated that these surfactants could retard the rate of polyester dyeing with disperse dyes and may be used as leveling agents. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Polymeric surfactant; Buffer capacity; Dispersion; Leveling agent
1. Introduction Surfactants are widely used as dispersing and leveling agents in the disperse dyeing process [1,2]. A few surfactants have aliphatic double chains that aggregate themselves in aqueous solution to form bilayer structures. These aggregates, generally referred as vesicles, have high entrapping efficiency for small molecules and are being studied as drug carriers.
* Corresponding author. Tel.: /886-3-4515811x328; fax: / 886-3-4531300 E-mail address: [email protected] (H.-J. Liu).
Disperse dyeing of polyester is usually carried out in the presence of dispersants. These dispersants are added to increase the dispersion stability, solubility, leveling and fastness properties of the dyes [3,4]. However, they may cause staining on the fabric and have a reductive effect on dyes, they are also discharged as effluent with the residual dyeing liquor, increasing the COD and BOD values of the effluent and causing environmental problems. Surfactants added to a disperse dye bath affect the dyeing process because of their dispersing, emulsifying and solubilizing ability. Various surfactants have been studied in the dyeing of polyester from both scientific and commercial
0927-7757/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 7 7 5 7 ( 0 2 ) 0 0 2 7 5 - 3
174
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
points of view. Recently, various compounds such as gemini surfactant with one head and two tail groups on dye sorption have been studied [5,6]. It is concluded that gemini surfactants can be used to improve uptake of disperse dyes on to polyester. In the present study, a novel series of watersoluble polyester surfactants are prepared by the reaction of polyethylene glycol (PEG) and dimethyl 5-sulfoisophthalate sodium salt (SIPM), and the dispersion properties for disperse dyes as well as the influence on the dyeing of polyester with disperse dyes are discussed.
2. Experimental 2.1. Materials
the KBr. Nuclear magnetic resonance (1H-NMR) spectra were obtained with a Varian 360 L NMR, the solvent was used CDCl3. 2.4. Measurement Buffer capacity was determined at room temperature with a Solar pH meter. Dispersant properties of PEG /SIPM polyesters for disperse dyes were determined by the measurement of particle size of dye/surfactant particle in aqueous solutions. A 100 ml solution containing 20 mg of commercial disperse dye and 50 mg of surfactant was adjusted to pH 4.5 by adding appropriate amount of acetic acid. Then the solution was heated to 130 8C by a computer controlled dyeing system and maintained at this temperature for 1 h.
Commercial grade SIPM was supplied by Sanyo Chemistry. Reagent grade titanium isopropoxide ¯ n) and PEG (number-average molecular weight (M from 400 to 2000) were purchased from Hayashi Pure Chemical Co. and used without further purification. Two disperse dyes used were Dispersol Red B-2B (C.I. Disperse Red 60), and Dispersol Blue B-R (C.I. Disperse Blue 56). These dyes were supplied by BASF Co [7]. 2.2. Preparation of PEG /SIPM polyesters Fig. 1 illustrates the three steps for preparing the PEG /SIPM polyesters. In step 1, 1 mol PEG and 0.5 mol SIPM were mixed evenly and polymerized with 1 g catalyst of titanium isopropyl oxide at 200 /220 8C for 2 h. In step 2, 0.5 mol SIPM was added and stirred evenly at 250 8C for 4 h. In step 3, the reaction temperature was cooled down to room temperature. Finally, the reaction solution was adjusted to pH 7 via adding NaOH solution to yield the water-soluble polyesters. 2.3. Analysis Standard methods were employed to determine the acid and hydroxyl values that provided the molecular weight of the polyesters was calculated [8]. Infrared (IR) were obtained with a FT/IR-3 spectrophotometer, the compound was scribble on
Fig. 1. Preparation of PEG /SIPM polyesters.
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
After this, the solution was cooled to room temperature (25 8C), and the dye /surfactant particle size in the solution was determined by light scattering method with MALVERN 4700. Dyeing of polyester fabric with disperse dyes was performed with the following method. A rapid laboratory dyeing machine was used, with 1% on the weight of the fabric, surfactant 0.5 g l 1, liquor ratio 30:1, pH 4.5, temperature and times of 115 8C and 5, 10, 20, 40, 70, 120 and 60 min under 130 8C. The uptake of the dye by the polyester fabric was measured by an Applied Color System. The K /S values are the indirect measurement of dye depth based on reflectance values for color depth of fabric.
3. Results and discussion 3.1. Preparation Table 1 lists the characterization of the PEG / SIPM polyesters that contained different polyoxyethylene chain lengths. Table 2 lists the result of IR spectrum and 1H-NMR spectrum. A typical IR spectrum of the synthesized PEG /SIPM polyesters displayed bands at 2830 cm 1 (CH3, stretchTable 1 Characterization of anionic derivatives of PEG /SIPM polyesters Compound
Appearance Acid value OH value Mn
PEG400 /SIPM PEG600 /SIPM PEG1000 /SIPM PEG2000 /SIPM
Liquid Liquid Liquid Solid
17.10 11.66 9.88 9.30
17.69 11.90 10.32 9.78
3225 4762 5555 5882
ing), 3221/3628 cm 1 (R /OH, stretching), 1044 / 1099 cm 1 (S /O, stretching) and 1553 /1718 cm 1 (C/O, stretching). These bands were characteristic of the desired compounds. The compound structure was further supported by the 1HNMR spectrum. It signals at d 8.4 ppm ( /SO3Na), d 4.4 ppm ( /OH) and d 3.2 /3.8 ppm (/CH2CH2O /). 3.2. pH buffer capacity In textile dyeing processes, acid or base agents are usually added to improve the softness, handle and color properties of the fabrics. However, these auxiliaries cause a pH change effect on dyes. Surfactants are used for improving the pH buffer capacity and providing a better stability under dyeing conditions. Fig. 2 illustrates the buffer capacity of solutions containing different PEG /SIPM polyester surfactants. In each solution the concentration of the surfactant is 10 g l 1. This figure shows that for pure water, the pH changed slowly from 3.0 to 5.0 as the NaOH concentration was raised from 0.1 to 0.3% by the addition of 2.19 N NaOH stock solution. Further increase the NaOH concentration from 0.4 to 0.5% increases dramatically the pH from 6.0 to 12.0. Apparently, the buffer capacity of pure water is at about 0.5% NaOH. On the other hand, the results in Fig. 2 indicate that the addition of the PEG /SIPM polyester surfactants resulted in solutions that have larger buffer capacities than pure water. An increase in the length of polyethylene chain of nonionic segment clearly increased the buffer capacity, especially PEG1000 /SIPM, PEG2000 /SIPM have significantly greater buffer capacity.
Table 2 Analysis of IR spectrum and 1H-NMR spectrum IR
NMR 1
Function group
Vibration mode
cm
/CH3 R/OH C /O
Stretching Stretching Stretching
2830 3221 /3628 1553 /1718
175
Function group
Chemical Shift d (PPM)
/CH2CH2O / /OH /SO3Na
3.2 /3.8 4.4 8.4
176
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178 Table 3 Average diameter of disperse dye systems in the presence of PEG /SIPM polyesters Compound
Particle size (nm) 130 8Ca
25 8C
Blank PEG400 /SIPM PEG600 /SIPM PEG1000 /SIPM PEG2000 /SIPM
Red 60
Blue 56
Red 60
Blue 56
178.0 188.5 185.6 172.0 165.0
147.8 139.2 137.5 137.0 133.1
252.4 252.4 243.3 223.0 220.0
249.8 249.8 239.5 237.6 229.1
Particle size distribution relative to the mean values. a Dye/surfactant dispersion heated at 130 8C for 1 h and then cooled to 25 8C prior to measuring particle size.
Fig. 2. pH buffer capacity PEG /SIPM polyesters.
3.3. Disperse stability The purified disperse dyes are almost insoluble in water. To prevent any aggregation or precipitation of dye particles during application, certain surfactants are often incorporated during production of the final dye powder or liquid [9 /11]. However, in some practical dyeing processes, such as dyeing of polyester fibers at high temperature, the re-aggregation of dye particles may occur at elevated temperatures when the heat stability of the dispersant system is insufficient. To prevent this, an additional dispersing agent, having high stability, may be introduced into the dye bath initially or during the course of dyeing [12 /14]. The water-soluble PEG /SIPM polyesters prepared in this study is observed having a good heatstability and can be properly employed for preventing the re-aggregation of dye particles in dyeing system. The average diameter of disperse dye particles in the presence of PEG /SIPM polyesters at room temperature (25 8C) and after elevated temperature (130 8C) treatment are collected in Table 3. It is clear from this table that the dispersions in the presence of auxiliaries consist of particles whose average diameter is smaller than the dyes present alone. Moreover, the average diameter of the particles after the elevated tem-
perature treatment is large than at room temperature treatment. These results indicate the formation of complexes between disperse dye and water-soluble PEG /SIPM polyester. At elevated temperature, the desorption of the novel dispersing agent from dye particles is minimized due to strong association between the dispersing agent and dye particles, thus resulting in high stability of these dispersant systems. In this process, the dispersing agent secures the stability of the dye-bath dispersion, and equilibrium between the aqueous and solid phase of the dye is established. In contrast, with temporarily solubilised disperse dye, hydrophobic interactions cause the converted insoluble form to aggregate readily and hence promote the growth of dye particles. 3.4. Effect of surfactants on polyester dyeing The conventional disperse dyeing process comprises four stages: (1) some of the dye are stabilized by the dispersing agent that dissolves in the dyebath, (2) dye molecules are transferred from solution to the surface of the fibre, (3) the solution in the dyebath is replenished by the dissolution of more solid material from the dispersion, (4) single molecule of the adsorbed dye diffuses into fibre. The rates of polyester dyeing with the two disperse dyes in the presence of the PEG /SIPM polyesters are shown in Fig. 3. This figure shows
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
177
Fig. 3. (a) Rates of dyeing with C.I. Disperse Red 60 expressed in terms of colour yield (K /S ). (b) Rates of dyeing with C.I. Disperse Blue 56 expressed in terms of colour yield (K /S ).
that the presence of the surfactants retarded the dyeing rates, indicating that the formation of dye/ surfactant complexes in the dye bath has an important influence on the dyeing rate. The PEG /SIPM polyesters would enhance the dyeing rate in a disperse dyeing system if they could form dye /surfactant complexes that have a lower solubility than the dye itself. In contrary, the results observed in Fig. 3 can be explained by the fact that our surfactant molecules contain hydrophilic polyoxyethylenated chains. These hydrophilic chains facilitate the formation of soluble dye /surfactant complexes, and reduce the dyeing rate. Decreasing the number of polyoxyethylene units in the surfactant molecule improves the retarding effect, probably due to the increase in the surfactant’s hydrophobic qualities, which favours complex formation. Slower dyeing is generally accepted to favour good leveling.
4. Conclusions A novel series of PEG /SIPM polyesters with water-soluble properties were prepared by the reaction of PEG and SIPM. These novel com-
pounds were found to exhibit good pH buffer capacity and disperse stability. The presence of these surfactants was found to retard the rate of polyester dyeing with the disperse dyes. This could be due to the hydrophilic polyoxyehtylenated chains in the surfactant molecules that help the formation of dye/surfactant complexes with greater solubility than the dye itself, decrease the dye’s substantivity for the fibre, and lower the rate of the dyeing. Slower dyeing is generally accepted to favour good leveling.
References [1] I.K. Soo, K. Kono, T. Takagishi, Textile Res. J. 67 (1997) 767. [2] W.A. Haile, H.W. Somers, Textile Chemist Colorist 10 (1978) 70. [3] W.J. Lee, J.P. Kim, J. Soc. Dyers Colour 115 (1999) 370. [4] L. Needles, Howard, R.S. Berns, J. Appl. Poly. Sci. 25 (1980) 1737. [5] T.S. Choi, Y. Shimizu, Dyes Pigments 45 (2000) 145. [6] T.S. Choi, Y. Shimizu, H. Shirai, Dyes Pigments 50 (2001) 55. [7] American association of textile chemists and colorists, Colour Index, Vol. 4.
178
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
[8] W.R. Sorenson, T.W. Campbell, Preparative Methods of Polymer Chemistry, Interscience Publishers, New York, 1968, p. 154. [9] F.J. Jones, J. Soc. Dyers Colour 100 (1984) 68. [10] J.O. Dvarka, H. Scheibalova, J. Soc. Dyers Colour 110 (1994) 30.
[11] T.V. Chambers, J. Soc. Dyers Colour 105 (1989) 214. [12] M.H. Zohdy, Polymer Int. 47 (1998) 165. [13] I.S. Kim, K. Kono, T. Takagishi, Textile Res. J. 67 (1997) 555. [14] H. Schejbalova, J. Odvarka, J. Soc. Dyers Colour 114 (1998) 279.
Preparation and dispersion properties of water-soluble polyethylene glycol-dimethyl 5-sulfoisophthalate sodium salt polyester surfactants Li-Huei Lin, Hsin-Jiant Liu *, Jiunn-Jer Hwang Department of Chemical Engineering, Van Nung Institute of Technology, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City 320, Taiwan, ROC Received 25 January 2002; accepted 31 May 2002
Abstract ¯ n /400 /2000) and dimethyl 5The reaction of polyethylene glycol (PEG, number-average molecular weights M sulfoisophthalate sodium salt (SIPM) produced a series of water-soluble polymeric surfactants. The structure of these surfactants was confirmed by IR, 1H-NMR and elemental analysis. These polymeric surfactants have been found to exhibit excellent pH buffer capacity and dispersant properties in disperse dye system. The experimental results indicated that these surfactants could retard the rate of polyester dyeing with disperse dyes and may be used as leveling agents. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Polymeric surfactant; Buffer capacity; Dispersion; Leveling agent
1. Introduction Surfactants are widely used as dispersing and leveling agents in the disperse dyeing process [1,2]. A few surfactants have aliphatic double chains that aggregate themselves in aqueous solution to form bilayer structures. These aggregates, generally referred as vesicles, have high entrapping efficiency for small molecules and are being studied as drug carriers.
* Corresponding author. Tel.: /886-3-4515811x328; fax: / 886-3-4531300 E-mail address: [email protected] (H.-J. Liu).
Disperse dyeing of polyester is usually carried out in the presence of dispersants. These dispersants are added to increase the dispersion stability, solubility, leveling and fastness properties of the dyes [3,4]. However, they may cause staining on the fabric and have a reductive effect on dyes, they are also discharged as effluent with the residual dyeing liquor, increasing the COD and BOD values of the effluent and causing environmental problems. Surfactants added to a disperse dye bath affect the dyeing process because of their dispersing, emulsifying and solubilizing ability. Various surfactants have been studied in the dyeing of polyester from both scientific and commercial
0927-7757/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 7 7 5 7 ( 0 2 ) 0 0 2 7 5 - 3
174
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
points of view. Recently, various compounds such as gemini surfactant with one head and two tail groups on dye sorption have been studied [5,6]. It is concluded that gemini surfactants can be used to improve uptake of disperse dyes on to polyester. In the present study, a novel series of watersoluble polyester surfactants are prepared by the reaction of polyethylene glycol (PEG) and dimethyl 5-sulfoisophthalate sodium salt (SIPM), and the dispersion properties for disperse dyes as well as the influence on the dyeing of polyester with disperse dyes are discussed.
2. Experimental 2.1. Materials
the KBr. Nuclear magnetic resonance (1H-NMR) spectra were obtained with a Varian 360 L NMR, the solvent was used CDCl3. 2.4. Measurement Buffer capacity was determined at room temperature with a Solar pH meter. Dispersant properties of PEG /SIPM polyesters for disperse dyes were determined by the measurement of particle size of dye/surfactant particle in aqueous solutions. A 100 ml solution containing 20 mg of commercial disperse dye and 50 mg of surfactant was adjusted to pH 4.5 by adding appropriate amount of acetic acid. Then the solution was heated to 130 8C by a computer controlled dyeing system and maintained at this temperature for 1 h.
Commercial grade SIPM was supplied by Sanyo Chemistry. Reagent grade titanium isopropoxide ¯ n) and PEG (number-average molecular weight (M from 400 to 2000) were purchased from Hayashi Pure Chemical Co. and used without further purification. Two disperse dyes used were Dispersol Red B-2B (C.I. Disperse Red 60), and Dispersol Blue B-R (C.I. Disperse Blue 56). These dyes were supplied by BASF Co [7]. 2.2. Preparation of PEG /SIPM polyesters Fig. 1 illustrates the three steps for preparing the PEG /SIPM polyesters. In step 1, 1 mol PEG and 0.5 mol SIPM were mixed evenly and polymerized with 1 g catalyst of titanium isopropyl oxide at 200 /220 8C for 2 h. In step 2, 0.5 mol SIPM was added and stirred evenly at 250 8C for 4 h. In step 3, the reaction temperature was cooled down to room temperature. Finally, the reaction solution was adjusted to pH 7 via adding NaOH solution to yield the water-soluble polyesters. 2.3. Analysis Standard methods were employed to determine the acid and hydroxyl values that provided the molecular weight of the polyesters was calculated [8]. Infrared (IR) were obtained with a FT/IR-3 spectrophotometer, the compound was scribble on
Fig. 1. Preparation of PEG /SIPM polyesters.
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
After this, the solution was cooled to room temperature (25 8C), and the dye /surfactant particle size in the solution was determined by light scattering method with MALVERN 4700. Dyeing of polyester fabric with disperse dyes was performed with the following method. A rapid laboratory dyeing machine was used, with 1% on the weight of the fabric, surfactant 0.5 g l 1, liquor ratio 30:1, pH 4.5, temperature and times of 115 8C and 5, 10, 20, 40, 70, 120 and 60 min under 130 8C. The uptake of the dye by the polyester fabric was measured by an Applied Color System. The K /S values are the indirect measurement of dye depth based on reflectance values for color depth of fabric.
3. Results and discussion 3.1. Preparation Table 1 lists the characterization of the PEG / SIPM polyesters that contained different polyoxyethylene chain lengths. Table 2 lists the result of IR spectrum and 1H-NMR spectrum. A typical IR spectrum of the synthesized PEG /SIPM polyesters displayed bands at 2830 cm 1 (CH3, stretchTable 1 Characterization of anionic derivatives of PEG /SIPM polyesters Compound
Appearance Acid value OH value Mn
PEG400 /SIPM PEG600 /SIPM PEG1000 /SIPM PEG2000 /SIPM
Liquid Liquid Liquid Solid
17.10 11.66 9.88 9.30
17.69 11.90 10.32 9.78
3225 4762 5555 5882
ing), 3221/3628 cm 1 (R /OH, stretching), 1044 / 1099 cm 1 (S /O, stretching) and 1553 /1718 cm 1 (C/O, stretching). These bands were characteristic of the desired compounds. The compound structure was further supported by the 1HNMR spectrum. It signals at d 8.4 ppm ( /SO3Na), d 4.4 ppm ( /OH) and d 3.2 /3.8 ppm (/CH2CH2O /). 3.2. pH buffer capacity In textile dyeing processes, acid or base agents are usually added to improve the softness, handle and color properties of the fabrics. However, these auxiliaries cause a pH change effect on dyes. Surfactants are used for improving the pH buffer capacity and providing a better stability under dyeing conditions. Fig. 2 illustrates the buffer capacity of solutions containing different PEG /SIPM polyester surfactants. In each solution the concentration of the surfactant is 10 g l 1. This figure shows that for pure water, the pH changed slowly from 3.0 to 5.0 as the NaOH concentration was raised from 0.1 to 0.3% by the addition of 2.19 N NaOH stock solution. Further increase the NaOH concentration from 0.4 to 0.5% increases dramatically the pH from 6.0 to 12.0. Apparently, the buffer capacity of pure water is at about 0.5% NaOH. On the other hand, the results in Fig. 2 indicate that the addition of the PEG /SIPM polyester surfactants resulted in solutions that have larger buffer capacities than pure water. An increase in the length of polyethylene chain of nonionic segment clearly increased the buffer capacity, especially PEG1000 /SIPM, PEG2000 /SIPM have significantly greater buffer capacity.
Table 2 Analysis of IR spectrum and 1H-NMR spectrum IR
NMR 1
Function group
Vibration mode
cm
/CH3 R/OH C /O
Stretching Stretching Stretching
2830 3221 /3628 1553 /1718
175
Function group
Chemical Shift d (PPM)
/CH2CH2O / /OH /SO3Na
3.2 /3.8 4.4 8.4
176
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178 Table 3 Average diameter of disperse dye systems in the presence of PEG /SIPM polyesters Compound
Particle size (nm) 130 8Ca
25 8C
Blank PEG400 /SIPM PEG600 /SIPM PEG1000 /SIPM PEG2000 /SIPM
Red 60
Blue 56
Red 60
Blue 56
178.0 188.5 185.6 172.0 165.0
147.8 139.2 137.5 137.0 133.1
252.4 252.4 243.3 223.0 220.0
249.8 249.8 239.5 237.6 229.1
Particle size distribution relative to the mean values. a Dye/surfactant dispersion heated at 130 8C for 1 h and then cooled to 25 8C prior to measuring particle size.
Fig. 2. pH buffer capacity PEG /SIPM polyesters.
3.3. Disperse stability The purified disperse dyes are almost insoluble in water. To prevent any aggregation or precipitation of dye particles during application, certain surfactants are often incorporated during production of the final dye powder or liquid [9 /11]. However, in some practical dyeing processes, such as dyeing of polyester fibers at high temperature, the re-aggregation of dye particles may occur at elevated temperatures when the heat stability of the dispersant system is insufficient. To prevent this, an additional dispersing agent, having high stability, may be introduced into the dye bath initially or during the course of dyeing [12 /14]. The water-soluble PEG /SIPM polyesters prepared in this study is observed having a good heatstability and can be properly employed for preventing the re-aggregation of dye particles in dyeing system. The average diameter of disperse dye particles in the presence of PEG /SIPM polyesters at room temperature (25 8C) and after elevated temperature (130 8C) treatment are collected in Table 3. It is clear from this table that the dispersions in the presence of auxiliaries consist of particles whose average diameter is smaller than the dyes present alone. Moreover, the average diameter of the particles after the elevated tem-
perature treatment is large than at room temperature treatment. These results indicate the formation of complexes between disperse dye and water-soluble PEG /SIPM polyester. At elevated temperature, the desorption of the novel dispersing agent from dye particles is minimized due to strong association between the dispersing agent and dye particles, thus resulting in high stability of these dispersant systems. In this process, the dispersing agent secures the stability of the dye-bath dispersion, and equilibrium between the aqueous and solid phase of the dye is established. In contrast, with temporarily solubilised disperse dye, hydrophobic interactions cause the converted insoluble form to aggregate readily and hence promote the growth of dye particles. 3.4. Effect of surfactants on polyester dyeing The conventional disperse dyeing process comprises four stages: (1) some of the dye are stabilized by the dispersing agent that dissolves in the dyebath, (2) dye molecules are transferred from solution to the surface of the fibre, (3) the solution in the dyebath is replenished by the dissolution of more solid material from the dispersion, (4) single molecule of the adsorbed dye diffuses into fibre. The rates of polyester dyeing with the two disperse dyes in the presence of the PEG /SIPM polyesters are shown in Fig. 3. This figure shows
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
177
Fig. 3. (a) Rates of dyeing with C.I. Disperse Red 60 expressed in terms of colour yield (K /S ). (b) Rates of dyeing with C.I. Disperse Blue 56 expressed in terms of colour yield (K /S ).
that the presence of the surfactants retarded the dyeing rates, indicating that the formation of dye/ surfactant complexes in the dye bath has an important influence on the dyeing rate. The PEG /SIPM polyesters would enhance the dyeing rate in a disperse dyeing system if they could form dye /surfactant complexes that have a lower solubility than the dye itself. In contrary, the results observed in Fig. 3 can be explained by the fact that our surfactant molecules contain hydrophilic polyoxyethylenated chains. These hydrophilic chains facilitate the formation of soluble dye /surfactant complexes, and reduce the dyeing rate. Decreasing the number of polyoxyethylene units in the surfactant molecule improves the retarding effect, probably due to the increase in the surfactant’s hydrophobic qualities, which favours complex formation. Slower dyeing is generally accepted to favour good leveling.
4. Conclusions A novel series of PEG /SIPM polyesters with water-soluble properties were prepared by the reaction of PEG and SIPM. These novel com-
pounds were found to exhibit good pH buffer capacity and disperse stability. The presence of these surfactants was found to retard the rate of polyester dyeing with the disperse dyes. This could be due to the hydrophilic polyoxyehtylenated chains in the surfactant molecules that help the formation of dye/surfactant complexes with greater solubility than the dye itself, decrease the dye’s substantivity for the fibre, and lower the rate of the dyeing. Slower dyeing is generally accepted to favour good leveling.
References [1] I.K. Soo, K. Kono, T. Takagishi, Textile Res. J. 67 (1997) 767. [2] W.A. Haile, H.W. Somers, Textile Chemist Colorist 10 (1978) 70. [3] W.J. Lee, J.P. Kim, J. Soc. Dyers Colour 115 (1999) 370. [4] L. Needles, Howard, R.S. Berns, J. Appl. Poly. Sci. 25 (1980) 1737. [5] T.S. Choi, Y. Shimizu, Dyes Pigments 45 (2000) 145. [6] T.S. Choi, Y. Shimizu, H. Shirai, Dyes Pigments 50 (2001) 55. [7] American association of textile chemists and colorists, Colour Index, Vol. 4.
178
L.-H. Lin et al. / Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002) 173 /178
[8] W.R. Sorenson, T.W. Campbell, Preparative Methods of Polymer Chemistry, Interscience Publishers, New York, 1968, p. 154. [9] F.J. Jones, J. Soc. Dyers Colour 100 (1984) 68. [10] J.O. Dvarka, H. Scheibalova, J. Soc. Dyers Colour 110 (1994) 30.
[11] T.V. Chambers, J. Soc. Dyers Colour 105 (1989) 214. [12] M.H. Zohdy, Polymer Int. 47 (1998) 165. [13] I.S. Kim, K. Kono, T. Takagishi, Textile Res. J. 67 (1997) 555. [14] H. Schejbalova, J. Odvarka, J. Soc. Dyers Colour 114 (1998) 279.