Textile Printing
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Textile Printing Textile printing is used to signify the production, by various means of colored patterns on designs upon all sorts of textile fiber. Textile printing is the most important and versatile of the techniques used to add design, color, and specialty to textile fabrics. Steps of Printing The basic steps in the printing process are as follows: 1. Preparation of the fabric 2. Preparation of the print paste. 3. Printing the fabric. 4. Drying the printed fabric. 5. Fixation of the printed dye or pigment. 6. Afterwashing. Print paste and its ingredients Print paste is a viscous solution of printing ingredients referred below that is used for textile printing. The main three printing ingredients are: 1. Dyestuff or pigments 2. Thickeners: Thickener can be defined as a substance used to increase the viscosity of a print paste or other fluid, in order to control its flow properties. 3. Chemicals and waters: The main types of chemicals used for textile printing are wetting agents, solvents, solution acids, dispersing agents, hygroscopic agents, oxidizing & reducing agents, defoamers, acids, alkalis, catalyst & carriers, swelling agents etc. Plastisol vs. Water-based Ink for textile printing There are two main types of ink that are used for textile printing. Water-based ink utilizes either dyes or pigments in a suspension with water as the solvent. The evaporation of the water is necessary to set or cure the ink. Plastisol ink is a PVC based system that essentially contains no solvent at all. Usage Recommendations Plastisol Water-base T-Shirts/light colors Excellent Excellent T-Shirts/dark colored Good Poor Nylon Jackets Good Poor Towels Poor Excellent November 26, 2007 Page 1 of 7 Textile Printing Yard goods Poor Excellent Sporting Goods Excellent Poor Styles of Printing Styles of printing refer to the manner in which a printed effect is produced. 1. Direct style 2. Discharge: white and colored 3. Resist style 4. Flock style 5. crimp/ crepon style Direct style of printing: A style of printing in one or several colors where the dyes are applied and then fixed by ageing or other appropriate means. The fabric is usually initially white but may sometimes have previously dyed. Metal style of printing: In the metal style of printing fabric is printed with silver or gold solution or non-removable resins. Resist Printing: In this method, the fabric is first printed in a design with a chemical that resists dye. The fabric is then dyed. The resist will leave the fabric white or some other color in the print areas. One of the advantages of this method is that dyes with very high colorfastness can be used. Discharge Printing: ‘Discharge’ means removal and ‘Discharge style’ refers process which can produce a white or colored effects on a dyed ground by printing paste containing a chemical capable of removing the ground color called ‘discharging agents.’ It could be of two types White Discharge: the printed part remains white after destroying the dyed color Color Discharge: With a dye incorporated in the print paste which is resistant to discharging agents. When printed the discharging agents removes the ground color and at the same time deposit color on the dyed ground. Flock Printing: Flock printing is a process in which a ‘flock’ is fixed on to a cloth by means of adhesive to form printed pattern. It produces a pile or velvety effect on the fabric similar to form a printed pattern. November 26, 2007 Page 2 of 7 Textile Printing Crepon/ crimp styles of printing: This style is characterized by the appearance of alternate plain and crinkle stripes in the fabric itself. This effect can be brought about by localized fabric shrinkage with appropiate swelling agent. Methods of Printing Methods of printing involve the means by which the printed pattern is produced. Depending on the means applied, the methods employed are as follows: 1. Block printing 2. Stencil printing 3. Roller printing 4. Screen Printing: Hand screen, Semi automatic flat screen, Rotary screen 5. Transfer printing Block printing: Block printing is the oldest and the simplest method of printing. In this method the wooden or metal block with a negative and raised design (i.e. in relief) is first stamped on the print paste and then on the cloth and an impression of positive design is made on the cloth. For producing multi colored prints, many blocks (as many as the number of colors used) are employed, each of them providing a part of the final design. Stencil printing: In this method a stencil is prepared by cutting out a design from a flat sheet of cartridge paper, metal or plastic, with a sharp pointed knife. Then the stencil is laid perfectly flat on the fabric to be printed and the color print paste is brushed through its perforations with a brush. Screen printing: A design reproduction process, developed from stenciling, in which print paste is forced through unblocked areas of a mesh, in contact with the substrate. The mesh may be a woven fabric or a fine screen, flat or cylindrical (rotary screen). Pressure is applied to the paste by a squeegee (blade roller). In hand screen printing the fabric is stretched out on a long table. The screens are moved methodically along the fabric. When a screen is in position the dye paste is pressed through the open mesh with a squeegee blade. The screen is moved to each pattern area and the process repeated. Roller printing: For roller printing an industrial printing machine having a large central rotating roller is use, around which the fabric is wound. As the cylinder rotates the fabric is passed between a series of smaller rollers and the large cylinder. Each small roller has etched on to it the pattern November 26, 2007 Page 3 of 7 Textile Printing appropriate to a specific color to be used. If a design of four colors is required, four small rollers must be used. For each color printing roller there is a color feed roller, which dips in a container holding the color print paste. This paste is transferred to the print roller during the printing. Transfer printing: Transfer printing is defined as any process by which a design is transferred from paper to another substrate. Several techniques have been used, viz melt-transfer, film-release, and wet-transfer, but vapor transfer (sublimation transfer) is the most important. Selected disperse dyes transfer in vapor form to thermoplastic fibers when the printed paper and fabric are brought into close contact in a transfer press at 170°-220°C. Pigment printing In pigment printing, insoluble pigments, which have no affinity for the fiber, are fixed on to the textile with binding agents in the pattern required. Importance of pigment printing Pigments, of course, are used for the production of plain-colored fabrics, but are of much greater importance in printing. 1. The pigment can be applied to all fibers potentially and it is the only coloration to glass fiber, fabric and polyester 2. No wet treatment is required, so drying and curing is applicable to all fiber. 3. Extensive color range of highly light fast colors 4. Possible to produce good combination shades on blended fiber in one padding operation 5. Application procedure is simple 6. Less expensive November 26, 2007 Page 4 of 7 Textile Printing Foil printing This printing method is based on the use of metallic foil paper of aluminum or copper one. A foil layer is affixed to a certain material by a heating process. Water based gel print A rapidly drying aqueous printing ink containing a gel forming polymer soluble in the ink but which rapidly gels upon application of the ink to a substrate during a printing process. Gel ink gives high gloss ‘wet looking’ prints that have a three-dimensional feel to them Spray Printing A spray gun forces the color through a screen November 26, 2007 Page 5 of 7 Textile Printing Puff printing In this method when the paste is printed and dries it look like normal printing garments but once it is cured the prints gets raised from the surface of fabric. Puff ink raises or foams in all directions when heated. It is made by adding a puffing or foaming agent to a regular plastisol. Most ink companies offer it premixed or as an additive. Puff needs a thick deposit of ink for it to puff up Suede (Leather Effect print) It prints like a puff ink and has a real suede (leather) feel to it. Suede is a milky colored additive that will work in a regular plastisol. High density printing High Density printing is the process of printing a specially formulated ink through a very thick stencil to achieve a raised, glossy smooth print with very sharp edges. Unlike Puff inks which have a flat, rounded and somewhat dull appearance, High Density prints result in bright, glossy distinct colors. The result is an applique effect High Density printing is done using basically standard textile screen printing procedures and equipment, with some variations. November 26, 2007 Page 6 of 7 Textile Printing Glitter Printing Glitter ink is made up of small Mylar flakes that are suspended in a clear plastisol base. It is printed through a very coarse mesh as low as 10 to 12 (cm) monofilament. Most ink companies offer glitter ink pre-mixed in a variety of "sparkles" with the most common obviously being silver and gold. Embossed Printing Embossing involves raising areas of a card surface above the level of the rest. The diagram below shows a coat of arms that has been embossed on green card.