TE-424 Textile Printing Lecture Notes PDF

TE-424 Textile Printing Department of Textile Engineering | NEDUET TE-424 Engr. Danyal Rashid Khan Lecturer...

TE-424 Textile Printing Department of Textile Engineering | NEDUET TE-424 Engr. Danyal Rashid Khan Lecturer Department of Textile Engineering Complied by: Engr. Danyal Rashid Khan 1 TE-424 Textile Printing Department of Textile Engineering | NEDUET Link to previous courses TE- 326 Textile Dyeing is the most relevant course. Printing is essentially “localized dyeing”. Concepts acquired in TE 205 – Pretreatment of Textiles are directly applicable. To a lesser extent, TE-111 Textile Chemistry is also helpful. Complied by: Engr. Danyal Rashid Khan 2 TE-424 Textile Printing Department of Textile Engineering | NEDUET All the topics listed are not of equal weightage. Some topics will be covered as sub-topics of others. The sequence will vary The course is not textile designing. Complied by: Engr. Danyal Rashid Khan 3 TE-424 Textile Printing Department of Textile Engineering | NEDUET Course Learning Outcomes Programme CLO # CLO’s objectives Taxonomy level Learning Outcome (PLO) Demonstrate a thorough knowledge of the pre-treatment & post 1. treatment processes & machine working, control, and technical C3 PLO 1 aspects of textile printing machines. Identify the causes of various printing faults & Synthesize solution 2. (s) for the same bases of logical application of the acquired C5 PLO 2 understanding of processes and the machines. Execute screen printing of a woven fabric while achieving even 3. distribution of ink, correct registration and uniformity of the shade P3 PLO 4 being printed. Complied by: Engr. Danyal Rashid Khan 4 TE-424 Textile Printing Department of Textile Engineering | NEDUET Course Structure Theory & Practical Practical will be performed in the Dyeing & Finishing Lab, TXD. Assessment of Theory Part – 40 Marks (Sessional) + 60 Marks (Final Exam) Midterm : 20 marks. Complex Engineering Problem (CEP) – 10 marks. 03 Sessional Tests, each 05 marks. Best of two will be considered for 10 marks in sessional. Assessments for Practical Part – 50 Marks Psychomotor Analysis : 25 Marks Open Ended Lab - 10 marks. Timely submission of lab manual + Attendance – 05 marks. Practical Vivas – 20 marks. Complied by: Engr. Danyal Rashid Khan 5 TE-424 Textile Printing Department of Textile Engineering | NEDUET Reference Materials Other material provided during the course 2nd or 3rd Edition 2006 Complied by: Engr. Danyal Rashid Khan 6 TE-424 Textile Printing Department of Textile Engineering | NEDUET Course Delivery 1. Introductory lecture series General overview of printing; factors to be considered Overview of textile printing; fabric characteristics in the context of printing Fabric requirements for printing; how to prepare a fabric for printing 2. Fabric Preparation of Printing In-depth study of the important preparatory processes in the context of printing; covering the principle & the machinery that is used 3. Methods of Textile Printing Block and roller printing in detail An overview of different Screen-Printing processes and Inkjet Printing 4. Fully automatic flat screen-printing machine 5. Rotary screen-printing machine Characteristics of rotary screens, rotary printing machine Complied by: Engr. Danyal Rashid Khan 7 TE-424 Textile Printing Department of Textile Engineering | NEDUET Course Delivery 6. Design & Screen preparation for printing Types of designs, preparation of design for screen making (engraving), design engraving methods for rotary and flat screens 7. Screen printing inks Formulation (binders, thickeners, auxiliaries, etc.) and application aspects for pigment and dyestuff printing inks 8. Inkjet printing Pre-treatment for inkjet printing, printing inks for inkjet, printing machine and print quality 9. Different styles of printing Direct, discharge and resist. 10. Fixation of prints Fixation processes, fixation machines. Complied by: Engr. Danyal Rashid Khan 8 TE-424 Textile Printing Department of Textile Engineering | NEDUET Important Dates – Fall 2025 S.No. Tasks Expected Timeline Marks Allocation 1 Quiz # 1 (MCQ’s) Week # 5 05 Marks 2 Mid Term Week # 8 20 Marks Complex Engineering 3 Week # 10 10 Marks Problem (CEP) submission 4 Quiz # 2 (MCQ’s) Week # 12 05 Marks Complied by: Engr. Danyal Rashid Khan 9 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1 - Introduction a) General overview of printing; factors to be considered b) Overview of textile printing; fabric characteristics in the context of printing c) Fabric requirements for printing; how to prepare a fabric for printing Complied by: Engr. Danyal Rashid Khan 10 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; Factors to be considered Learning Outcomes Develop an understanding of; Printing in general Various factors and their significance in printing a substrate Complied by: Engr. Danyal Rashid Khan 11 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Printing in general – Paper Printing in general – Plastic Complied by: Engr. Danyal Rashid Khan 12 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Printing in general – Metal Printing in general – Glass Complied by: Engr. Danyal Rashid Khan 13 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Printing in general – Fabric (of course) Complied by: Engr. Danyal Rashid Khan 14 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered Substrate Speed of printing Printing equipment and Cost of printing printing inks are selected according to Color brilliancy these factors Resolution of printing (dots per inch) Retention of the print (fastness properties) Complied by: Engr. Danyal Rashid Khan 15 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Substrate Surface Roughness Absorbency Porosity Flexibility Stability Complied by: Engr. Danyal Rashid Khan 16 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Printing speed Newspapers – Millions of copies printed in a matter of few hours. Soft drink cans –Printed at high speeds due to large production rate of soft drinks Fabric – Printer wants to print at high speed. However, the print quality must be maintained in any case. Complied by: Engr. Danyal Rashid Khan 17 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Cost How much you are willing to pay for a newspaper? Do you want to pay a lot for the packaging of your crisps or biscuits? Would you compromise on the cost of printing a circuit? Complied by: Engr. Danyal Rashid Khan 18 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Color brilliancy Even very low-cost confectionery items are wrapped up in brilliantly colored packaging. Why? Does the color of a solar cell on a sheet of plastic matter much to you? Complied by: Engr. Danyal Rashid Khan 19 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Task Find a printed textile fabric and compare its print brilliancy and sharpness with that on a pack of crisps or biscuits. On a textile, is it possible to achieve color brilliancy comparable to that on a plastic (pack of crisps)? Complied by: Engr. Danyal Rashid Khan 20 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Resolution Defined as DPI (dots per inch) for printed images Affects the ‘appearance’ of an image. Complied by: Engr. Danyal Rashid Khan 21 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Resolution In case of textile printing, resolution requirements vary from low to very high. Complied by: Engr. Danyal Rashid Khan 22 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Factors to be considered – Retention Print retention on a substrate is technically known as print fastness. Do you want the print on a newspaper to last for a long time or withstand washing? What will be your perception of the quality of a printed textile article that fades after only few washes? Complied by: Engr. Danyal Rashid Khan 23 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Activity Try rubbing a printed area of a newspaper with your index finger. Do the same with a printed textile fabric Complied by: Engr. Danyal Rashid Khan 24 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Summary Printing is the application of one or more colorants on specific areas of a substrate to create a pattern/design. Many different materials in our daily use are printed; paper, glass, metal, fabric, etc. These materials differ in their properties and thus the printing processes for each are designed accordingly. When printing something, the factors to be considered include the substrate characteristics, cost, required color brilliancy, sharpness and the fastness of the print. An optimal trade-off between these factors is to be targeted. Complied by: Engr. Danyal Rashid Khan 25 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1a General overview of printing; factors to be considered Additional references Currency note printing https://www.youtube.com/watch?v=JKYHeXxsg6g Printing on plastic https://www.youtube.com/watch?v=_hk-ioQOHaw Newspaper printing https://www.youtube.com/watch?v=__u2ei6-M-U Tin can printing https://www.youtube.com/watch?v=V4TVDSWuR5E Textile printing Comprehensively covered in the next lecture Complied by: Engr. Danyal Rashid Khan 26 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1b Textile Printing and textile substrate characteristics Learning Outcomes An in-depth understanding of the characteristics of textile substrates in the context of printing and the factors affecting these characteristics. Complied by: Engr. Danyal Rashid Khan 27 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1b Textile printing and textile substrate characteristics Te x t i l e P r i n t i n g Te x t i l e D y e i n g Localized Coloration Bulk coloration of a material Usually, multiple colors A single color Well-defined boundaries for each color Bulk coloration so no boundary definition Colorant is applied in the form of a thick paste* Colorant is applied in the form of a solution *except inkjet printing which should be uniformly absorbed into the substrate Complied by: Engr. Danyal Rashid Khan 28 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1b Textile printing and textile substrate characteristics Te x t i l e P r i n t i n g Traditionally, textile printing is for decorating a fabric. It can be used to make a textile “functional” Electrically conductive Thermally conductive/insulative Affect appearance against a background Others. Complied by: Engr. Danyal Rashid Khan 29 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1b Textile printing and textile substrate characteristics Te x t i l e P r i n t i n g Aesthetic Functionality A difference in patterns (motifs), type of colorant and color combination determines the end-product characteristics Complied by: Engr. Danyal Rashid Khan 30 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1b Textile printing and textile substrate characteristics Te x t i l e s u b s t r a t e s c h a r a c t e r i s t i c s i n t h e c o n t e x t o f p r i n t i n g Recall substrate properties that were discussed in the previous lecture (Lecture 1A); Surface roughness Absorbency Porosity Flexibility Stability These are important to be considered while printing a textile substrate. Complied by: Engr. Danyal Rashid Khan 31 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing Learning Outcomes An in-depth understanding on the requirements textile fabric for printing. Complied by: Engr. Danyal Rashid Khan 32 TE-424 Textile Printing Department of Textile Engineering | NEDUET In Lecture 1B, we studied how Woven, various properties Knitted, & Weave Type of a textile fabric Non-woven are significant in the context of Yarn Type Fabric printing. Filament Construction Staple Yarn Textile Fiber Type Properties Pretreatment Hydrophilic Surface Hydrophobic Absorbency; of fabric Porosity; Stability, etc. Complied by: Engr. Danyal Rashid Khan 33 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing Te x t i l e s u b s t r a t e s c h a r a c t e r i s t i c s i n t h e c o n t e x t o f p r i n t i n g Specific requirements for preparation of a fabric for printing. These are; 1. Free from surface or sub-surface impurities 2. Correct layout of wefts 3. Controlled fabric shrinkage and dimensional stability 4. Crease free 5. Special requirements (as in inkjet printing) Complied by: Engr. Danyal Rashid Khan 34 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 1. Free from surface or sub-surface impurities Desizing and scouring remove hydrophobic materials (waxes, sizing chemical, etc) that will otherwise interfere in printing ink absorption and penetration Bleaching results in whiteness and optimal absorption Mercerization improves whiteness, dimensional stability, reduces hairiness, etc. Complied by: Engr. Danyal Rashid Khan 35 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 2. Correct layout of wefts In weaving, the weft yarn is inserted perpendicular to the warp yarn. A lot of ‘pulling forces’ (stresses) are applied on a fabric right after fabric formation. Most of the stresses are applied during wet processing of a fabric Processes such as bleaching can exert a lot of stress on the fabric Complied by: Engr. Danyal Rashid Khan 36 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 2. Correct layout of wefts These stresses can disturb the ideal lay of weft Weft acquires a curved profile – A ‘Bow’ distortion Weft is straight but not at 90º to warp - A ‘skew’ distortion Complied by: Engr. Danyal Rashid Khan 37 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 2. Correct layout of wefts There are other types of weft distortions but the more common ones are ‘bow’ and ‘skew’. Simple bow and skew (and their combinations) can be removed. Compound distortions can not be removed*. Complied by: Engr. Danyal Rashid Khan 38 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 2. Correct layout of wefts If weft distortions are not removed, deviation in the printed design can occur later on. Complied by: Engr. Danyal Rashid Khan 39 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 2. Correct layout of wefts If weft distortions occur after printing, the design will also distort. Complied by: Engr. Danyal Rashid Khan 40 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 3. Controlled fabric shrinkage and dimensional stability It is important to control fabric shrinkage before printing. excessive shrinkage of fabric during printing causes printing faults Complied by: Engr. Danyal Rashid Khan 41 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 3. Controlled fabric shrinkage and dimensional stability Heat setting: The process carried out to achieve shrinkage control and dimensional stability in fabric. Raise the fabric temperature to a point where the strained secondary bonds are broken. Give ample time for the polymer chains to settle in new ‘stress-free’ positions. Reduce the temperature to form new secondary bonds in “relaxed state” Complied by: Engr. Danyal Rashid Khan 42 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 4. Crease free If creases are present in fabric, then the area under the crease will not be printed There are chances of excessive creasing in bleaching (due to machine faults). Such creases can become rather permanent and cause problems in subsequent processes There are arrangements on the printing machine to remove creases before the fabric is printed. Just as on any other open-width continuous processing machine Complied by: Engr. Danyal Rashid Khan 43 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing 5. Special Requirements Inkjet printing process requires application of certain chemicals/auxiliaries prior to printing. Further discussion in the lecture of Inkjet printing Complied by: Engr. Danyal Rashid Khan 44 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing Quality Control (QC) Checks Some common QC checks before printing are as follows. Absorbency Shrinkage AATCC Test Method 79-2018 AATCC 135 ISO 20158:2018 AATCC 150 Other methods. ISO 6330 Complied by: Engr. Danyal Rashid Khan 45 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing Quality Control (QC) Checks Some common QC checks before printing are as follows. Bow & Skew Whiteness ASTM D3882-08 More important in case of low coverage designs Complied by: Engr. Danyal Rashid Khan 46 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing Quality Control (QC) Checks 1. pH Fabric should be neutral before printing. Any alkali left over from bleaching could hinder subsequent fixation of pigment print. 2. Conductivity Conductivity is due to presence of electrolyte (salt) on the fabric. This could interact with printing ink and reduce its viscosity thus causing issues such as excessive penetration and/or spreading of ink after printing. Complied by: Engr. Danyal Rashid Khan 47 TE-424 Textile Printing Department of Textile Engineering | NEDUET Lecture # 1c Fabric requirements for printing Summary Preparation of a fabric for printing starts with the usual pre-treatment operations to; clean the fabric achieve the desired degree of whiteness and absorbency In addition; Weft distortions have to be removed prior to printing to avoid deviation of printed design later on Fabric should be dimensionally set and its shrinkage should be controlled prior to printing During printing; The fabric should be free from dust, lint and loose threads Complied by: Engr. Danyal Rashid Khan 48 TE-424 Textile Printing Department of Textile Engineering | NEDUET Thank You Complied by: Engr. Danyal Rashid Khan 49