Textiles: Secret Life of Fabrics

Transcription

1 Instructed by Jade Carlin Textiles: Secret Life of Fabrics Week Five: Non-Wovens, Composites, Dyeing & Finishing, Testing

2 Non-wovens Fibers are joined by mechanical or chemical means No distinct pattern Generally stiff and somewhat scratchy Felting, Bonding, & Laminating are common ways of forming non-wovens Common Fabrics: Pelon, Felt, Insulation Household Uses: Bedding, backing for quilts, dust cloths for box springs, carpet backing, and upholstered furniture

3 Felt Felting is a quick and cheap method of producing fabric. A combination of pressure, moisture and heat is used to form the fibers into fabric. Agitation of the fibers causes them to interlock permanently. Felt is not very strong but will not fray when cut. It can be formed (steamed) into shapes without the need for seams. Soft, non-woven, can pull apart

4 Film Plastic-like material, repels liquid, stiff Mildews, rots, tears Inexpensive, fairly durable Method of Construction: Made from synthetic solutions formed into thin sheets Common Fabrics: Vinyl Household Uses: Tablecloths, shower curtains, draperies, upholstery, and wall coverings

5 Foam Soft, air holes, absorbent, resilient Method of Construction: Rubber or polyurethane substance with air incorporated causing foaming, quite inexpensive, rots Common Fabrics: Sponges Household Uses: Carpet backing, padding, pillows and cushions, laminates to other fabrics

6 Composites Woven, knitted, felted or bonded fabrics can be combined to produce a fabric with a mixture of properties. Bonding and Laminating are two of the most common ways to form a composite. Materials are bonded together by using stitching or adhesive. Laminating is when a number of fabrics are bonded together.

7 Final Steps Finishes Dyeing Printing Treatments

8 Dyeing Some of the most important dyeing methods are: Producer, used for man-made fibers still in the solution. Stock, loose fibers before yarn processing. Yarn, used to dye certain woven patterns before weaving or knitting. Piece, dyeing a piece of fabric after weaving or knitting. Cross, an inexpensive way to achieve two color patterns. Garment, after the entire garment has been made.

9 Dyeing The most commonly used processes for imparting color to cotton are piece dyeing and yarn dyeing. In piece dyeing, which is used primarily for fabrics that are to be a solid color, a continuous length of dry cloth is passed full-width through a trough of hot dye solution. The cloth then goes between padded rollers that squeeze in the color evenly and remove the excess liquid. In one variation of this basic method, the fabric, in a rope-like coil, is processed on a reel that passes in and out of a dye beck or vat. Yarn dyeing, which occurs before the cloth is woven or knitted, is used to produce gingham checks, plaids, woven stripes and other special effects. Blue dyed warp yarns, for example, are combined with white filling yarns in denim construction.

10 Pigments and Dyes A dye is a colorant that goes into solution or dissolves. Dye particles break apart into single molecules Pigment particles remain clustered together in suspension Dyes have a chemical affinity for fiber but pigments do not Pigment particles Dye molecules

11 Acid Dyes Used mainly on wool, silk, and nylon* They have acid chemical groups in their dye molecules They use an acid dye bath to produce the chemical reaction Reaction involves acid, salt, heat, agitation, and time Amount of acid and rate at which it is added affects the rate at which the dye bonds Salt slows the bonding process, helping the dye color the fiber evenly. It attaches to the dye first.

12 The structural orientation of the polymers within a fiber varies, It affects dye results and other fiber properties

13 Printing Applies design to fabrics via either wet or dry techniques. Wet, where dyestuffs are applied wet for optimum color penetration. Engraved roller printing Screen printing Flatbed Rotary screen Dry, where either heat transfer or paper printing techniques are used.

14 Roller / Rotary Printing This process involves a print paste (like a thick paint) that is applied to an engraved roller, and the fabric is guided between it and a central cylinder. The pressure of the roller and central cylinder forces the print paste into the fabric. Because of the high quality it can achieve, roller printing is the most appealing method of printing designer and fashion apparel fabrics. Long runs of the same fabric design are produced on a roller print cylinder machine operating at speeds between 50 and 100 yards a minute. As many as 10 different colors can be printed in one continuous operation, but each color must have a separate roller. The design is cut into the surface of copper rollers; by varying the depth of the engraving on the roller the shade depth can be altered. Sharpness of line and fine detail can be achieved this way. A typical printing machine has a large padded drum or cylinder, which is surrounded by a series of copper rollers, each with its own dye trough and doctor blade that scrapes away excess dye.

15 Flat (Silk) Screen Printing In flat screen printing, a screen on which print paste has been applied is lowered onto a section of fabric. A squeegee then moves across the screen, forcing the print paste through the screen and into the fabric. The screen is the image carrier made from a porous mesh stretched tightly over a metal frame.

16 Heat Transfer Printing This is essentially transferring an image to fabric from a paper carrier. When heat and pressure are applied to this paper the inks are transferred. Some transfers are topical, and the image sits on the surface of the fabric. Other transfers are absorbed into the fibers of the fabric. Heat transfer printing is clean and environmentally safe. The only by-product is the paper carrier. It is the perfect print method for short run and sample production, but can also be used for batch production as well.

17 Dye Sublimination Printing Dye sublimation allows photo lab quality picture printing. During the dye sublimation printing process, an image is digitally printed in reverse with dye sublimation toners or inks onto media. That image is then placed on top of a fabric and subjected to high heat and pressure to form a heat press. The dye sublimation toners or inks sublimate the inks go from a solid state to a gaseous state without becoming liquid in between and flow into the fabric, dyeing the threads. This creates a gentle gradation of color and does not distort or fade over time.

18 Resist Printing Discharge printing is one method of resist printing and involves using a chemical paste called a disperse dye. It must be used with a reactive dye as a ground color for the process to work. It also has to be cured or fixed with steam so the dye reacts with the fabric and causes a color reaction. Discharge printing produces the brightest, lightest prints on dark-colored garments and can be very striking. This method can only be used on natural fibers and fabrics that will discharge color. Another method of resist printing is Batik. Natural materials such as cotton or silk are used as they absorb the wax that is applied in the dye resisting process. The fabrics must be of a high thread count (densely woven) for best results.

19 Environmental Issues Printing techniques are renowned for their damage to the environment and the health of the workforce producing them. There is a lot of washing preparation done to the fabric before it can be printed on and this sends chemicals into the air and water and pollutes the outside environment. A typical process will often include sequestrates, alkalis, bleaching agents, stabilizers, catalysts, crease-resisting agents, acid dyes, exhausting agents, soaping agents and softeners. Probably chemicals per process. Harsh and hazardous chemicals are used in the dyeing and printing methods of fabrics and toxins like carbon monoxide, carbon dioxide, sulphur dioxide and zinc oxides carcinogenic are commonly found in these processes. Transfer printing is the most environmentally friendly form of printing onto fabric and also the most cost effective. As a result it is fast becoming the textile manufacturer s choice for the future.

20 Finishing The process used to enhance a fabric, usually after dyeing or printing They can be Physical or Chemical

21 Finishing Finishing, as the term implies, is the final step in fabric production. Hundreds of finishes can be applied to textiles, and the methods of application are as varied as the finishes. Cotton fabrics are probably finished in more different ways than any other type of fabrics. Some finishes change the look and feel of the fabric, while others add special characteristics such as durable press, water repellency, flame resistance, shrinkage control and others. Several different finishes may be applied to a single fabric.

22 Physical Finishing Calendaring, the passing of fabric between heavy rollers for various effects Heat setting, to stabilize man-made fabrics Napping, to raise surfaces Shearing, to create uniform surface Sanding or sueding, to create a soft surface Shrink control, or preshrinking

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24 Chemical Finishing Caustic reduction to give polyester a silk like feel Durable press, or permanent press Mercerizing to give cotton a lustrous silk like finish Water repellency

25 Environmental Concerns Encouraging Environmental Excellence, or E3, is a program urging producers to protect the environment. Decreased water use and chemical waste is the goal American and European textile companies have difficulty competing against Asian mills where producers do not pay to clean up the environment. Domestic manufacturers want to require imported textile products to be made under the same environmental standards to ensure fair competition and ensure a clean environment worldwide.

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27 Industry Standards & Testing Click on icons to be taken to their websites