Printing cotton fabrics with creative designs using printing pastes of different rheological properties

The main idea of the present study is to investigate the role of rheology in the printing process and how it affects the design lines and areas through applying two different thickeners, Sodiume alginate and Carboxymethyl cellulose, which have different rheological properties to cotton fabrics using two classes of reactive dyes. Different concentrations of these thickeners were prepared and applied to cotton fabrics using manual silk screen printing. (4%) Sodiume alginate was the best concentration to obtain high levels of K/S. Sodiume alginate has a pseudoplastic behaviour while CMC has a thixotropic one. Some Creative designs were printed using 4% Sodiume alginate through manual silk screen printing. صخلملا عابطلا نئاجعل ةيجولويرلا صاوخلا ربتعت نع ةلوئسملا اهرابتعاب ةعابطلا ةيممع يف رثؤت يتلا لماوعلا مهأ نم ة نم يسيئرلا فدهلا نإف يلاتلابو ةداح ةيعابط طوطخو ةسناجتم ةعابط يمع لوصحمل ةمزلالا ةجوزملا ةنيجعلا حنم ةيجولويرلا صاوخلا ةسا رد وه ثحبلا يجلا لثم ةعابطلا ةنيجع يف ةمدختسملا تانختملا عاونأ ضعبل مويدوصلا تان يمع يوتحت ةعابط نئاجع ريضحت مت .ةفمتخملا ميمصتلا طوطخو تاحاسم يمع اهريثاتو زوميمسلا ليثيم يسكوبركو نيعون مادختساب ةينطق ةشمقأ يمع ةعابطلا يف اهمادختساو ةفمتخم تا زيكرتب زوميمسلا ليثيم يسكوبركو مويدوصلا تانيجلا قيرط نع ةطشنلا تاغبصلا نم نيفمتخم زيكرت لضفأ نأ ىلإ يلاحلا ثحبلا جئاتن ريشت .ةيوديلا تانومباشلاب ةعابطلا ( وه ةينطق ةشمقأ يمع ينول قمع لضفأ يمع لوصحمل مويدوصلا تانيجللأ 4 ةسا ردب ةصاخلا جئاتنلا ريشت امك .)% يتوين ريغلا ةيكيتسلابوديسبلا عئاوملا عون نم مويدوصلا تانيجلا نأ يلإ ةيجولويرلا صاوخلا زوميمسلا ليثيم يسكوبرك امأ ةين ةعابطلا قيرط نع مويدوصلا تانيجلا مادختساب ةركتبم تاميمصت ةعابط مت .كيبورتوسكسلا عئاوملا عون نم وهف .ةيوديلا تانومباشلاب ثحبلا فادهأ ف ةمدختسملا ةينيتوين ريغلا تانختملا ضعبل ةيجولويرلا صاوخلا ةسا رد وه ثحبلا نم يسيئرلا فدهلا ةعابطلا نئاجع ي تانومباشلا مادختساب ةطشنلا تاغبصلاب ةينطق ةشمقأ يمع اهتعابطو زوميمسلا ليثيم يسكوبركو مويدوصلا تانيجلا لثم نونفلاو ةرامعلا ةمجم رشاعلا ددعلا 47 ربتعي مويدوصلا تانيجلا مادختساب ةيجسن تاقمعمك اهمادختسلا ةينطق ةشمقأ يمع ةركتبم تاميمصت ةعابط اضيأ .ةيوديلا .ثحبمل رخا فده بلا ةيجهنم ثح يبيرجتلا جهنملا يمع ثحبلا دمتعي ثحبلا جئاتن ةينيتوين ريغلا ةيكيتسلاب وديسبلا ةعابطلا نئاجع نم مويدوصلا تانيجلا نأ يلإ يلاحلا ثحبمل ةيلاحلا جئاتنلا ريشت لا عون نم وهف زوميمسلا ليثيم يسكويرك امأ ةقيقدلا طوطخلاو سملاملا ةعابط يف جئاتن لضفأ يطعت يلاتلابو وسكس مويدوصلا تانيجللأ زيكرت لضفأ . تاحاسملا ةعابط يف اهمادختسا دنع ةديج ةيعابط جئاتن يطعت يلاتلابو كيبورت ( وه ةينطقلا ةشمقلأا يمع ةعابطمل 4 .)% 1Introduction Textile printing is the most versatile and important of the methods used for introducing color and design to textile fabrics. Considered analytically it is a process of bringing together a design idea, one or more colorants, and a textile substrate, using a technique for applying the colorants with some precision. (1) This is usually achieved by applying thickened pastes containing dyes or pigments onto a fabric surface according to a given color design. (2) Reactive dyes were initially introduced commercially for application to cellulosic fibers, and this is still their most important use. (3) Reactive dyes are commonly used for cotton printing because of their high wash fastness, brilliant color and variety of hue. (4) The rheological behaviour of the printing paste plays a great role in the process of textile printing because it affects the amount of printing paste applied on the textile surface and consequently on the quality of the printed substrate. (5) Namely during the printing process (the action of the squeegee) the printing paste is exposed to deformation forces that change the arrangement of polymer chains in their primary cross-linked structure and thus cause a drop of viscosity and increased elasticity. (6) The rheological properties of the printing paste are closely related to the chemical structure of the thickener used, its concentration and the physico-chemical interactions with other paste components. (7) In roller printing, it recognized that, for fine line work a thickening agent, somewhat with short flow, is required to achieve good definition and thickening agent with long flow will tend to print lines. On the other hand, when printing designs containing large areas of color, a thickener with short flow tends to give unlevel printing areas instead of spreading out uniformly over the surface of the fabric. (8) The operation in roller printing subjects the thickening agents at the moment of transfer from engraved roller to fabric to very high shearing stresses. Immediately after passage through the printing nip, these shearing stresses are greatly reduced. (9) It will be obvious therefore; that, the flow properties of the thickening agents under both high and low shearing stresses are likely to be significant in obtaining a level and well defined printed marks. (10) نونفلاو ةرامعلا ةمجم رشاعلا ددعلا 48 The main idea of the present research is to study the rheological properties of some non-Newtonian printing thickeners as Sodiume alginate and CMC and apply different concentrations of these thickeners to cotton fabrics via flat screen printing technique using two classes of reactive dyes to study their viscosity effect on design blotches and fine lines. Printing creative designs through manual silk screen printing using Sodiume alginate thickening agent is also another objective of the present work.


1-Introduction
Textile printing is the most versatile and important of the methods used for introducing color and design to textile fabrics.Considered analytically it is a process of bringing together a design idea, one or more colorants, and a textile substrate, using a technique for applying the colorants with some precision. (1)This is usually achieved by applying thickened pastes containing dyes or pigments onto a fabric surface according to a given color design. (2)eactive dyes were initially introduced commercially for application to cellulosic fibers, and this is still their most important use. (3)Reactive dyes are commonly used for cotton printing because of their high wash fastness, brilliant color and variety of hue. (4)he rheological behaviour of the printing paste plays a great role in the process of textile printing because it affects the amount of printing paste applied on the textile surface and consequently on the quality of the printed substrate. (5)Namely during the printing process (the action of the squeegee) the printing paste is exposed to deformation forces that change the arrangement of polymer chains in their primary cross-linked structure and thus cause a drop of viscosity and increased elasticity. (6)The rheological properties of the printing paste are closely related to the chemical structure of the thickener used, its concentration and the physico-chemical interactions with other paste components. (7)n roller printing, it recognized that, for fine line work a thickening agent, somewhat with short flow, is required to achieve good definition and thickening agent with long flow will tend to print lines.On the other hand, when printing designs containing large areas of color, a thickener with short flow tends to give unlevel printing areas instead of spreading out uniformly over the surface of the fabric. (8)The operation in roller printing subjects the thickening agents at the moment of transfer from engraved roller to fabric to very high shearing stresses.Immediately after passage through the printing nip, these shearing stresses are greatly reduced. (9)It will be obvious therefore; that, the flow properties of the thickening agents under both high and low shearing stresses are likely to be significant in obtaining a level and well defined printed marks. (10)he main idea of the present research is to study the rheological properties of some non-Newtonian printing thickeners as Sodiume alginate and CMC and apply different concentrations of these thickeners to cotton fabrics via flat screen printing technique using two classes of reactive dyes to study their viscosity effect on design blotches and fine lines.Printing creative designs through manual silk screen printing using Sodiume alginate thickening agent is also another objective of the present work.

2-1-1 Fabric
Cotton fabric produced by Domiattex Co., Egypt.The weaving structure is plain 1/1.The weight of the square meter is 96 gm.

2-1-3 Thickening agents
Two different types of thickeners were used, Sodiume alginate is the first one and CMC was the second.Both of thickeners brought by Oxford Co, India.

2-2 Technical Procedures
The process of printing can be summarized as follows:

2-2-1 Preparation of the printing paste
Cotton samples were printed according to the following formulations:

2-2-2 Printing Technique
The prepared printing pastes were applied on cotton fabrics with reactive dye via flat screen printing technique.

2-2-3 Fixation
After drying the printed samples at room temperature, they are subjected to steam at 105 ⁰ c for 10 minutes.

2-2-4 Washing-off
Washing off the fixed printed samples is carried out as follows: -Rinsing with running cold water -Soaping at 100⁰c for 10 minutes using a non-ionic detergent.
-Rinsing with running cold water and finally air-drying.

2-3-1 Color Strength measurement
The color yields of the printed samples were determined by using the light reflectance technique performed on a Perkin-Elmer (Lambda 3B) UV/VIS Spectrophotometer at Textile Printing, Dyeing and Finishing department, Faculty of Applied Arts, Damietta University.The color strengths, expressed as K/S values, were determined by applying the Kubelka-Mink equation as follows: Where R = decimal fraction of the reflectance of the dyed fabric; Ro = decimal fraction of the reflectance of the undyed fabric; K = absorption coefficient; S = scattering coefficient. (11)

2-3-2 Rheological Measurements
Rheological measurements were carried out in the laboratory of department of textile printing, dyeing and finishing at Faculty of Applied Arts (FAA), Helwan University using a rotary viscometer (Rheomat-15), Zurish, Switzerland).

2-3-3 Color Fastness
Fastness properties to light, washing, perspiration and rubbing were carried out at National Institute for Standards (NIS-Egypt).

3-Results and Discussion
The researcher will discuss the role of various concentrations of chemical constituents by showing their effect on K/S of printed cotton samples, the effect of printing process on tensile strength of the fabric, the rheological properties of the printing pastes and finally the color fastness properties of the printed samples.

3-1 Effect of thickener concentration
The cotton samples were printed by both Remazol and procion reactive dyes using printing pastes with different concentrations (2, 4, 6 and 8%) of two thickeners, one of them was Sodiume alginate and the other was CMC, to get different density of films.The color strength of the printed samples were measured and the results are illustrated in table (1) and figure (1) as shown: From the previous figure it is clear that the K/S of cotton samples printed with procion Blue PX-5R is increased by increasing both of the thickeners concentrations from 2% to 4% and 2% to 6% Sodiume alginate and CMC respectively.K/S of cotton samples printed with Remazol Brilliant Yellow reaches its maximum at 4% concentration for both thickeners.By increasing the concentration of both thickeners to 8% a gradual decrease in K/S was observed.The increase in color strength at 4% Sodiume alginate concentration for both reactive dyes, 4% and 6% CMC concentration for Remazol Brilliant Yellow and Procion Blue PX-5R respectively can be explained on the fact that: at these concentrations, the thickener is helped by other auxiliaries as (urea and carbonate) offers a suitable film on the surface of cotton fabrics, thus during steaming process maximum fixation of reactive dyes could occur. (11)

3-2 Effect of different additives 3-2-1 Effect of Urea concentration
To investigate the role of urea in printing process, Cotton samples were printed using printing pastes of 4% Sodiume Alginate for both reactive dyes, 4% CMC for Remazol Brilliant Yellow and 6% CMC for Procion Blue PX-5R with different concentrations of urea.K/S of printed samples was measured and illustrated in table (2) and Fig (2), table (3) and fig (3) for Remazol Brilliant Yellow and Procion Blue PX-5R respectively.It is clear from the previous table and figure that the increase in color strength of the prints when using Remazol brilliant yellow is directly proportional to the increase in urea concentrations until K/S reaches a maximum value at 125 g/Kg for both thickeners.After which K/S is inversely proportional to the increase of urea concentration.
In case of using procion blue PX-5R, the next results were obtained:  The previous results shows that there is a slight increase in K/S values of the prints for both thickeners until it reaches the maximum value at 125 g/L.After this value, there is a sharp decrease in K/S values at 150 and 175 g/L.The increase in color strength at 125 g/L for both thickeners can be explained on the fact that: at this concentration, urea can provide the humidity required for fixing during steaming process.As a result, urea increase water content in it is medium, which comprises both printing film and cotton fabric.Increasing water content in the printing film will increase dye solubility and its ability to transfer into cotton fabrics.It will decrease the aggregation of the dye molecules.On the other hand, increasing water content in cotton fabric will cause the swelling of the fabrics, which will accelerate the dye molecules diffusion. (11)

3-2-2 Effect of Sodium carbonate concentration
To investigate the suitable concentration of Sodiume carbonate needed to attain maximum fixation of reactive dyes on cotton fabrics, different concentrations of Sodiume carbonate were included in the printing paste.Cotton samples were printed using printing pastes of (4%) Sodiume Alginate for both reactive dyes, (4%) and (6%) CMC for Remazol Brilliant Yellow and Procion Blue PX-5R respectively with different concentrations of Sodiume carbonate.K/S of printed samples was measured and illustrated in table (4) and Fig ( 4).

Fig (4) Effect of Sodiume carbonate concentration of Sodiume alginate and CMC printing paste on K/S for both reactive dyes
The previous results shows that there is a clear increase in K/S values of the prints until it reaches a maximum value at 10 g/Kg and 30 g/Kg for Remazol Brilliant yellow and Procion blue PX-5R respectively with both of the two thickeners.After these values, there is a slight decrease in K/S values at 40 g/Kg.The increase of K/S values at 10 g/Kg and 30 g/Kg Sodiume carbonate for both thickeners can be explained on the fact that at these concentration Sodiume carbonate could produce ionization of accessible cellulose hydroxyl groups, which can then react with reactive dyes.By Increasing Sodiume carbonate concentration gradually after these values, both the rate and the degree of dye hydrolysis will increase. (11)

3-4 Effect of Steaming temperature
Cotton samples printed with the two types of dyes and thickeners were subjected to steaming at different degrees of temperatures for fixed duration i.e. 10 min.The obtained results of K/S are showed in table (5) and Fig (5).The previous results leads to the indication that, maximum dye fixation and higher color strength was achieved at a temperature of 95⁰c and 100°c for Remazol Brilliant yellow with Sodiume alginate and CMC respectively while it was 110⁰c for Procion blue PX-5R with the two types of thickeners.

3-5 Effect of Steaming Time
To determine the suitable steaming duration within which complete reaction and maximum dye fixation may be attained, printed cotton samples were subjected to steaming at the optimum temperatures for different durations.Printed cotton samples with Remazol Brilliant Yellow were steamed at 95⁰c and 100⁰c for Sodiume alginate and CMC respectively while samples printed with Procion Blue PX-5R were steamed at 110°c for the two thickeners for different periods of minutes.K/S of printed samples was measured and illustrated in table (6) and Fig (6).The previous results show that, by increasing the duration of steaming, the dye fixation gradually increases until it reaches its maximum value after 20 min for Remazol Brilliant yellow with the two types of thickeners.For Procion blue PX-5R, K/S value reaches its maximum after 5 min, after that period there is a clear decrease in K/S values.

3-6 Rheological Measurements
Different concentrations of Sodiume alginate and CMC thickeners were prepared (2%, 4%, 6% and 8%) by soaking in water over night in room temperature.The two thickeners had the same weight which was 250 gm.The rheological properties of all concentrations of the two thickeners were measured.Table (7) and fig (7) show only the results of measuring 4% Sodiume alginate while results of measuring 4% CMC can be illustrated at table (8) and fig (8)   It is clear from the rheograms shown in fig (7) that irrespective of the nature of the Sodiume alginate; the examined paste are characterized by non-Newtonian pseudoplastic behaviour.The up and down flow curves are not coincident, which indicate that if this paste subjected to a force, it is viscosity decreases as the applied forces increases from the minimum to the maximum.On the removal of the applied force, the paste retains its original viscosity immediately, i.e. it does not need a time to rebuild its structure and retain their original viscosity soon.This property, i.e. pseudoplasticity has an important role in the field of textile printing to obtain levelness and sharp outlines. (12)he rheograms represented in fig (8) show that irrespective of the nature of the thickening agent used; the examined CMC paste is characterized by non-Newtonian thixotropic behaviour.The up and down flow curves show that this paste undergoes decrease in viscosity with time under constant strain rate.On the removal of the applied force, the paste need much time to retain its original viscosity and rebuild its structure.Depending upon the system, the time necessary for structure build up may range from a few seconds to several days. (13)

Color Fastness Properties
The fastness properties of the printed samples were tested and their results are illustrated in table (9) for Sodiume alginate and CMC.

Table (9) Color fastness of samples printed with Sodiume alginate and CMC printing paste
The previous table show that the two types of thickeners nearly had the same results.
Washing fastness assessment of obtained colors have shown very good levels for both reactive dyes.The results obtained also showed that printed cotton samples have excellent light fastness for both reactive dyes.
The rubbing fastness results are good and acceptable showing little fading in wet rubbing shades while dry rubbing fastness results are excellent.For perspiration fastness the results are acceptable for Procion Blue PX-5R and very good for Remazol Brilliant yellow.

Conclusion
It can be concluded from the previous study that Sodiume alginate thickener is the best one to be applied in the cotton printing process with an optimum concentration 4% for both reactive dyes.The Results of the rheological measurements of both thickeners indicate that Sodiume alginate is characterized by non-Newtonian pseudoplastic behaviour which provide the required viscosity to obtain sharp outlines while CMC has a thixotropic one and as a result can be applied to large areas to have levelling prints.

Fig ( 2 )
Fig (2) Effect of Urea concentration of Sodiume alginate and CMC printing paste on K/S of Remazol Brilliant yellow

Fig ( 3 )
Fig (3) Effect of Urea concentration of Sodiume alginate and CMC printing paste on K/S of Procion Blue PX-5R

Fig ( 5 )
Fig (5) Effect of Steaming temperature of Sodiume alginate and CMC printing paste on K/S for both reactive dyes