526456617-Coated-and-Laminated-Textiles1 (1).pptx

Coating and lamination

1. 1 Coated and Laminated Textiles )

2. Syllabus: 2 Coated and Laminated Textiles : Coating types , polymeric materials and fabric substrates for coating, methods of coating, micro porous coating, hydrophilic coating . Reference Books: Coated and Laminated Textiles – Walter Fung Smart Textile Coatings and Laminates - W.C. Smith Chemistry of the Textiles Industry - M. A. Wilding, Dr. C. M. Carr And from numerous online journals and information.

3. Introduction: 3 Coating and laminating are textile finishing processes designed to add or improve function and to add value to a material and/or to create a material with specific properties .

4. Introduction: 4 Coating: Polymer or elastomer, usually in viscous form , is applied directly onto the fabric and cured. A variety of techniques are used. A bond-coat (adhesive) may or may not be used . Coating is a process in which one or several layers of material are deposited on the surface of a substrate .

5. Introduction: 5 Laminating: A pre-made or extruded film is bonded onto the substrate, generally with thermal or adhesive bonding. Curing is generally not required. Laminating is a process that combines multiple substrates together. The goal of lamination is to produce a stable, multilayer structure with properties that cannot be achieved by a single substrate ( Woodruff, 2002b ). Substrates used in textile laminating processes are textile fabrics, pre-prepared polymer films, membranes, foam , and fibers.

6. Introduction: 6 Coating Vs Laminating: Coatings and laminates will interact differently with the fabric; this is due to the way in which they affix to the textile surface. Figure A demonstrates how a coating covers the surface of the fabric, as applied in liquid form, it is able to penetrate the fabric structure, filling the air pockets and bridging the interstices . T he polymer is applied directly as a viscous liquid

7. Introduction: 7 Coating Vs Laminating: Figure B depicts how a laminate sits on the fabric surface, the fabric retains its air pockets and the laminate has fewer points of contact.  Consists of one or more textile substrates which are combined with a pre-prepared polymer film or membrane by adhesives or heat and pressure.

8. General usage : 8 Coated and laminated fabrics have certain advantages over unsupported films or sheets. They have much higher tensile and tear strengths, better puncture resistance and better handle. Coated and laminated fabrics are used for the following purposes . To maintain liquid- and gas-resistant properties on flexible textile fabrics. (b) To provide a soil-resistant, easily cleaned surface. ( c) To provide materials having the appearance and wearing qualities of leather, or other animal skins, at a much lower cost, and to satisfy the ethical conscience of those who dislike the exploitation of animals .

9. Bonded Fabric : 9 A layer of fabric structure where a face fabric is joined to a back fabric with an adhesive that does not significantly add to the thickness of combined fabric . Methods of Laminating: Sewing or Stitching. Bonding by an adhesive. Welding with high frequency electric current. Welding by flame.

10. 10 Difference between Laminated and Bonded fabric Laminated Bonded fabric 1. Fabric is attached with a continuous sheet 1. Two fabrics are joined together 2. Good wrinkle resistance 2. Poor wrinkle resistance 3. Tailoring property not so good 3. Good tailoring property 4. Good insulation property with light weight 4. Insulation property is not so good 5. Less Breathable. 5. More breathable. 6. Not so hygienic for wearing 6. Hygienic & good for wearing 7. Comparatively heavier than bonded fabric s 7. Relatively light weight.

11. Methods of Laminating : 11 Sewing or Stitching : In this method, a fabric is combined with polyurethane, polyester, foam etc . or another fabric by sewing or stitching. The sewing causes pores in the fabric which causes air permeability & hence heat may pass out easily, lowering the insulation property . The pore causes appearance at outside, however the air circulation can be achieved good due to the pores. The weight of the fabric may increase and beside will not be so smooth. The thread may break at the point where holes are made by needles.

12. Methods of Laminating : 12 2. Bonding by an adhesive : An adhesive is used to combine the sheet of foam with the fabric . The use of adhesive may increase the weight and thickness of fabric.   The main advantage is that due to use of adhesive the open-end is sealed the air permeability is decreased. There may be separation of the sheet and the fabric, if the fabric is handled roughly. If the adhesive used is water soluble, the stability of the fabric will be low, which may give separation of the sheet and the fabric while washing.

13. Methods of Laminating : 13 3. Welding with high frequency electrical current : The polyurethane sheet or polyester foam is combined with fabric by high frequency electrical current welding and no other material is used. If the fabric is placed at rough surface, then it may get separated.

14. Methods of Laminating : 14 4. Welding by flame : The film sheet is used to combine the fabric and the foam sheet. Before passing the three sheets of foam layer, film of adhesive and the fabric through a calendar roller, the film is heated by using a flame below and after calendaring the combined sheet of laminated fabric is obtained.

15. Methods of Laminating : 15 4. Welding by flame : This technique is mainly used to attach foam to a textile fabric, which is widely used in automotive. As displayed in figure below the foam is presented to the flame, which encourages melting; as it then dries it bonds the textiles. This technique has associated health and safety risks due to the release of gases when melting takes place.  

16. Methods of Laminating : 16 4. Welding by flame :   Polyurethane (P.U.) foam from a supply roller is passed over a gas flame at around 950⁰C and combined with the textile material from a second roller in the first nip. The foam-laminated textile material is then passed through the second nip and wound up on a third roller. Three-ply laminates are possible by the addition of a second burner to the machine. The major disadvantage is the high capital cost of equipment-for in-stance, carbon filter absorbers are needed to clean up the gaseous emissions so that they comply with legislative requirements . Flame lamination has been widely used for automotive fabrics.

17. Methods of Laminating : 17 4. Welding by flame :   D oes not require drying or a curing oven. Processing variables are gas type, flame height and spread , foam burn-off, line speed, and nip pressure. The line speed should be held constant, and flame intensity should be optimally adjusted to ensure sufficient melting while preventing burning and preserving the thickness of the adhesive layer.

18. Methods of Laminating : 18 5 . Adhesive Lamination aqueous Based: Wet adhesives used in the laminating process are either water-based or solvent-based. They are applied to one substrate surface in liquid form by conventional coating methods, such as gravure roll coating, spraying , roll coating, and knife coating. Then, the adhesive coated web is bonded with other substrates under pressure, and dried or cured in an oven.

19. Methods of Laminating : 19 5 . Adhesive Lamination aqueous Based Adhesive lamination can be used to laminate two fabrics by applying an aqueous-based pressure-sensitive adhesive by knife-over-roller spreading. Alternatively , the pressure-sensitive adhesive can be spread on a release paper and then transfer coated to the textile material, which can then be combined with a second fabric by bringing these into contact under heat and pressure to remove the water. Typical of the adhesives used are natural and synthetic rubber, styrene-butadiene resins (SBRs), polyvinyl alcohol and acrylic polymers.

20. Methods of Laminating : 20 6 . Film Lamination Laminate film is generally categorized into these five categories ● Standard thermal laminating films ● Low-temperature thermal laminating films ● Heat-set (or heat-assisted) laminating films ● Pressure-sensitive films ● Liquid laminates