Textile Printing, Dyeing and Finishing Dept, Faculty of Applied Arts, Helwan University, Giza, Egypt
Received Date: March 29, 2012; Accepted Date: April 16, 2012; Published Date: April 18, 2012
Citation: Ibrahim DF, Abd El-Salam SH (2012) Enzymatic Treatment of Polyester Fabrics Digitally Printed. J Textile Sci Eng 2:113. doi: 10.4172/2165-8064.1000113
Copyright: © 2012 Ibrahim DF, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Concerns regarding health, energy and environment drove the improvement of enzyme technology in textile industry. Enzymatic processing of natural fibers covers a wide-range of operations, from cleaning preparations to finishing. In addition to natural fibers, enzymatic hydrolysis on synthetic fibers has been explored to enhance their hydrophylicity using lipases, polyesterases and cutinases Figure 1. Among these enzymes, lipases have been reported as hydrolyzing ester linkages in polyethylene terepHthalate, thus producing hydroxyl and carboxylic groups .
On the other hand, total global production of printed textiles is widely covering a wide range 25-30 billion meters per annum. Around 97% is screen printed and the remaining 3% is digitally printed. Over the next 5-years, a large percentage of production will shift to digital printing applications. Analysts predict that within 5-years, 15% of globally printed textiles will be digitally produced.  This interest has been fulfilled by the rapid advantages of digital printing technology.
In spite of all these advantages, polyester fabric has a lower ability to hold water and inks due to the smooth morphology and chemical properties of polyester fibers .
In this present work polyester fabric was treated with lipase enzyme based on two different routes:
- First: In a separate bath before digital printing
- Second: In the pretreatment bath of ink jet printing mixed with the bath components.
Another aim of work is that both techniques were going in the same line for environmentally friendly technology. Meanwhile with respect to all which has been addressed before, this research aims to:
- Improves digitally printing of polyester fabrics using disperse dyes.
- Applies a new technique in textile wet processing.
- Save energy, time and money (representing in merging two processes).
- Green production by using green substrates and technology.
Materials and dyestuff
Throughout this research a 100% scoured and bleached polyester fabric, with fabric structure plain weave 1/1, 80 g/m2 weight, supplied by Happy Tex. for Spinning & Weaving Company- Egypt, was used.
A hydrophobic disperse dye was used in the present study, supplied as original ink jet dyes of printing (CMYK to obtain red color), produced by Ink Tec. Co. Ltd, Korea. Lipase MP Enzyme supplied from biomedical LLC France, sodium alginate thickener and formic acid, with commercial grade.
The two routes of treatment were sited in this work:
First: enzymatic treatment before ink jet pretreatment bath: Polyester samples were treated in a previous separate biotreatment bath of polyester fabrics using lipase enzyme with different concentrations:
X g/l lipase enzyme (0, 0.5, 0.9, 1.5 and 2 cm/l), at room temperature for 30 mins at pH level 7.
After enzymatic treatment, the temperature of the bath was raised to stop enzyme activity, and then the samples were rinsed with hot and cold water then dried. Polyester samples were then padded in ink jet pretreatment bath and finally digitally printed and fixed, as follows:
I. Pre-treatment bath: (Traditional pre-treatment bath of polyester)
100 gm/l sodium alginate 4%
Adjust pH level to 6.2 using formic acid and then, padding is done approximately to 70%. Allow the mixture to dry at room temperature .
Ink jet printing: The pretreated polyester samples, were digitally printed by ink jet technique machine using (Encad 1500 TX printer, produced by Encad Inc, USA) followed by air drying.
Fixation: After drying the printed samples were subjected to fixation at 180°C for 2 minutes, using thermo fixation machine, produced by (R.B. Electronic and Engineering PVT. LTD, India).
Washing off: Finally the fixed printed samples were washed off as follows:
- Rinsing with running cold water.
- Soaping at 60°C for 15 minutes using (4 gm/l soap)
- Rinsing with running cold water and finally the printed samples were dried at room temperature.
II. Second: Enzymatic treatment mixed with ink jet pretreatment bath: Polyester fabrics treated with different concentrations of lipase enzyme dispersed with the inkjet pretreatment bath components, including (sodium alginate and water, at different pH levels (4, 5, 7 and 8), accompanied with different storing time ( 1, 2, 3 and 4 hours ) using plastic bags, at room temperature.
X g/l lipase enzyme (0, 1, 2, 3 and 4 g/l)
100 g/l sodium alginate 4%
After storing time the samples were dried with hot air to insure enzyme inactivation, and then ink jet printed with traditional steps (2, 3, and 4).
Color fastness properties: The color fastness to washing, rubbing, and perspiration were determined according to AATCC test methods (61- 2010, 8- 2007, 15- 2009).
Color strength: K/S of the printed samples was evaluated by color reflectance technique at λ maximum (440). The used spectrophotometer was of model ICS-Texicon Ltd, Kennestside Park, Newbury, Berkshire RG 145TE, England.
Tensile strength: Tensile strength of control polyester fabrics and the biotretead ones based on optimum conditions were measured on Quant 5.37, tensile strength H5KT/130 – USA, according to ASTM: D 5034 - 2008 standards.
Separately previous polyester enzymatic treatment:
Effect of lipase enzyme concentration: Different concentrations of lipase enzyme were used (0, 0.5, 0.9, 1.5 and 2 g/l) in a separate bath for polyester fabrics biotreatment (before ink jet pretreatment and printing) in order to improve the fabric hydrophilicity and absorbance. As lipase catalyze the hydrolysis of ester bonds, regenerating water soluble glycerol and water insoluble fatty acid, which then can be converted to water soluble salts by the addition of the alkali .
The K/S values of the biotreated and printed fabrics are plotted in Figure 2. The results imply that the maximum color strength value was obtained using the enzyme concentration 0.5 g/l, since this concentration caused an increase in color strength for about 20%. As a result of this modification the fine structure of polyester fibers is opened leading to easier and greater dye penetration inside the fiber which is reflected on the color strength of the printed fabric. Then any increase in enzyme concentration will decrease K/S; according to the negative relation between disperse dye and the modified polyester surface which has a more hydrophylicity character Table 1.
|Enzyme concentration g/l||K\S Value|
Table 1: Effect of Enzyme concentration on color strength of digitally printed polyester fabrics with disperse dye.
Enzymatic treatment mixed in pretreatment bath of ink jet printing
Effect of enzyme concentration: For saving time and energy (conventional process stages), the enzymatic treatment was mixed in one bath with the pretreatment step of the ink jet printing.
Different concentrations of lipase enzyme were used with constant contents of pretreatment bath at pH 6.2. After treatment the polyester samples were stored in plastic bags for 1 hour. As the treatment bath contains:
X enzyme (0, 1, 2, 3 and 4 g/kg) + 100 g/kg sodium alginate thickener with 900 cm water
From Figure 3 it is clear that increasing enzyme concentration, increase the K/S gradually, till it reaches maximum at 2 g/L concentration. As an effect of lipase enzyme on fiber surface modification according to the hydrolysis of great number of ester links reaches its maximum degree .
By comparing between the role of enzyme in fabric modification in (Figure 2,3) we can observe that enzyme has a more freely effect in the aqueous solution rather than in a viscous paste. This addresses the difference between the effect of lipase enzyme in separate solution and within the pretreatment bath of ink jet Table 2.
|Enzyme concentration g/l||K\S Value|
Table 2: Effect of Enzyme concentration on color strength of digitally printed polyester fabrics with disperse dye.
Effect of pH level: pH level is considered to be a very effective factor, affecting both enzyme treatment and pretreatment of inkjet printer polyester fabrics. Generally the lipase optimum pH is in the range 7-9 according to the substrate, and the presence of the activators, but it is decomposed by acids. On the other hand the optimum pH level of pretreatment bath of the ink jet printed polyester fabrics was 6.2–6.8 as mentioned in literature . So the pH level in this experiment was adjusted at different pH levels (5, 6, 7 and 8) in order to reach the most suitable one for maximum color strength result.
From Figure 4, it obtained that changing the pH level from acidic to slightly alkaline medium made some gradually increasing in color strength of printed samples according to the presence of the suitable medium for enzyme activity and disperse dye fixation. pH level 6-7 could be the most suitable level in spite of the increasing color strength at pH 8, as reaching the alkaline medium may hydrolyze the polyester fibers due to alkali reweighing effect Table 3.
Table 3: Effect of pH level of pretreatment bath on color strength of digitally printed polyester fabrics with disperse dye.
Effect of storing time
For offering the lipase enzyme an interval of time to make its action of hydrolysis polyester chains, the polyester samples were carefully stored in plastic bags after treatment in a bath contains.
100 g/l sodium alginate
Different storage times were applied (1, 2, 3 and 4 hours) in order to study the effect of storing time on the fabric merging pretreatment process.
Figure 5 shows increasing in color strength by extending the samples storing time, as a result for enzymatic effect on polyester samples. Two hours storing time was the most suitable time, as increasing time in spite of its positive effect on fabrics; it has also a negative effect of weakening the fiber tensile strength Table 4.
|Storing time / hour||K\S|
Table 4: Effect of storing time on color strength of digitally printed polyester fabrics with disperse dye.
Color fastness properties
The results of fastness properties of the printed fabrics are listed in Table 5. The results show very good fastness to rubbing, from very good to excellent in case of perspiration and washing fastness properties, indicate that the prints have some improving after both enzymatic treatment .
|Color fastness||Fastness to rubbing||Fastness to perspiration||Fastness to washing|
|Separate Bio treatment||4-5||4-5||4-5||4-5||4-5|
Table 5: Fastness properties of polyester digitally printed fabrics.
Tensile strength: To insure limited tensile strength loss, the tensile strength of untreated polyester fabrics and both enzymatic treated polyester samples, were measured. It seems to be a minimal loss of fiber weight and strength (8–16%). As a result of fabric weight loss, according to enzyme modification and hydrolyze effect on polyester surface Table 6.
|Tensile strength kg/m2||Tenacity|
|Separate Bio treatment||210||26|
Table 6: Tensile strength of bio treated and digitally printed polyester fabrics.
Ink jet printing of polyester fabrics was improved using biotreatment process either before ink jet pretreatment or merging with it in one bath. This treatment was considered as a new technique at which saving time and energy via, improving digital printing of polyester fabric with disperse inks. As well, color fastness of treated printed samples was improved and tensile strength not affected for great extent.
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