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Chapter 11 Dyeing and Printing - ppt video online download

By A Mystery Man Writer

Color Goal: Produce appealing, level, fast color on product at reasonable price with good performance and minimal environmental impact. History and background. Complex area: Difficult to get color on fabric in uniform appearance (level) that will not fade, bleed, or alter appearance.
Chapter 11 Dyeing and Printing
Colors must be cured. White and colored pigments.
Opacifiers: Produce good covering power; variety of lusters. Thickeners: Prevents migration of paste. Thinners: Keeps paste semi-fluid. Antibleeding agents: Eliminates halo effect. Pigments: Colored compound. Softeners: Maintain soft hand of fabric. Easier to match colors with pigments than with dyes.
Fiber specific: Fibers differ in chemical composition and restrict dyes that can be used. High color strength. Fastness varies with dye and dye class. Components. Chromophore: colored part of molecule. Auxochrome: alters color and provides bonding and solubility sites.
Acid (anionic): Wool, silk, nylon; some rayon, acrylic, and polyester; bright colors, poor wet fastness and may have poor light fastness. Azoic: Cotton; some polyester; bright shades, good fastness to light and water; poor crocking; water insoluble; solubility cycle dye. Cationic (basic): Acrylic, wool; some polyester and nylon; good fastness on synthetics, but poor on natural fibers; bright colors.
Direct: Cellulosic fibers; similar to above, but brighter colors; large, planar molecules; moderate wet fastness; most commercially important class at present. Disperse: Synthetics; good fastness; may fume fade; needs special equipment.
Fluorescent: Most fibers; dye absorbs energy at one wavelength and reemits at another wavelength; whitens yellowed fabric; used in finishing and home laundry. Mordant dyes [acid dye + metal (mordant)]: Wool, silk, nylon; some rayon, acrylic, and polyester; duller colors; excellent fastness. Natural dyes: Minor dye class; renewable and sustainable; from plant, animal, and mineral sources; applied to some apparel and furnishings; limited colors and availability.
Sulfur: Cotton; insoluble in water; solubility cycle dye; difficult process; dull colors; good fastness; may tender fabric; used for bottom weight goods. Vat: Cotton; insoluble in water; solubility cycle dye; difficult process; dull colors; good fastness; incomplete color range; used for bottom weight goods.
Mass pigmentation (solution dyeing, producer colored, spun or dope dyed): Add colored pigments to spinning solution; color integral part of fiber. Gel dyeing: Color incorporated before fiber coagulates.
Top dyeing: top is dyed; difficult to distinguish between top and stock dyeing.
Stripes, plaids, or structural design fabrics. More expensive than piece dyeing; solid colors usually piece or product dyed (not yarn or fiber dyed)
More likely to see stripe parallel to warp yarns in woven fabric (easier to dress loom) or parallel to course in knit fabric. Change color at yarn feed for circular or flat bed knits. Skein dyeing. Package dyeing. Beam dyeing.
Dyed in fabric stage: generally produces solid color.
(red: cotton; blue: wool). Union dyeing: Fibers of different dye receptivity (modification or generic class) for uniform color. (cotton/polyester blend).
Color added; product cut and sewn. Found in socks, hosiery, tee shirts, jackets, slacks, towels, etc. Problems with leveling, difference in components, poor penetration, dimensional changes; requires well prepared gray goods.
Jig dyeing: large runs of fabric passed through dyebath several times. Pad dyeing: in bath in open width; dye forced into fabric ( yd/min)
Methods of Dyeing Package dyeing: Dyebath forced through textile; usually yarns, but some fiber and fabric.
Jet dyeing: similar to beck dyeing; used for delicate fabrics; yd/min. Paddle machine, rotary drum, or tumbler: product dyeing; abrasive & chemical washes. Continuous machine or range: large lots of goods; one or two bath processes for union and cross dyeing; Thermosol process.
Wet print: Paste made of dyes, not pigments. Dry print: Paste made of pigments, uses adhesive (change fabric hand). Foam print: Uses less water and energy.
Block: hand process; carved wood block pressed in dye paste, stamped onto fabric; different block for each color.
Roller etched with design; picks up paste and presses it onto fabric as fabric passes between rollers; different roller for each color up to 16 colors; duplex print: printed on both sides of fabric.
Hand screen print. Flat screen: flat; slower; shorter yardages. Rotary screen: cylinder screen; faster; most common method to print yardage.
Blotch printing: both the background color and the design are printed on the fabric.
Requires dark ground. Discharged areas may be tender with poor aging resistance. Trace of dark ground may be visible on technical back in printed area.
Discharge Print Direct Print Lower left corner: back of fabric
Color prevented from entering fabric in specific areas when piece dyed or paste may be blocked from passing through certain areas during printing. Batik: hot wax on fabric; piece dyed; wax removed; price related to quality & colors present.
Ikat: Yarn tied to prevent dye penetration; dyed, woven; single or double ikat.
Resist print Stencil print: Precursor of screen print; paper or metal pattern; brush or spray color on.
Warp Print Warp yarns printed before weaving; hazy pattern.
Burn-out Printing Chemicals destroy certain fibers in a mixed fiber fabric to create a pattern
Digital (ink jet) print: Color applied using ink jet printer; carpets and textile samples. Heat transfer print: Design printed on paper with disperse sublimable dyes (with heat, dye evaporates); fabric and design on paper are placed in close contact, heated, and dye transfers. Electrostatic print: Powdered dye heat-fixed to fabric surface; dye location controlled by screens.
Heat Transfer Digital Printing Flocked
Differential print: Screen print on carpet with fibers of different dye affinity (cross dye). Foil print: Special adhesive applied to fabric; fabric dyed and partially cured; foil transferred by heat transfer press; bonds only where adhesive has been applied. Hand painting: silk painting.
Metal as dye. Microliquid crystals in surface coating; change color with temperature. Dye and print combinations. Shift to shorter runs. Computer applications: experiment with design; minimize seconds & environmental impact; stricter color control; decrease dead time; increased efficiency. Softer binders for pigment prints.
Bleeding: loss of color in water or other solutions; may color other fabrics present. Crocking: color transfer to another fabric from rubbing together. Migration: color movement to adjacent areas or fabrics. Fading: color loss due to perspiration, gas fumes, sunlight, etc.; dyes degraded.
Frosting: Colored portion of fabric lost by abrasion due to poor dye penetration. Out-of-register: Print color overlaps or misses desired areas.
Production matching problems: assessed with colorimeter or human eye. Side-to-side: Color does not match from selvage to selvage. Side-to-center: Color does not match from selvage to center. End-to-end, ending, or tailing: Color does not match between ends of roll/bolt.
Alternatives to colored textiles: Naturally colored fibers or use of natural dyes. Supercritical carbon dioxide or liquid carbon dioxide as alternatives to traditional water-based systems.