Water repellent finish.

Textile Engineering

1. Water Repellen t Finish

2. Md. Shahjalal Lecturer Dept. of Textile Engineering Northern University Bangladesh(NUB) Shah Md. Maruf Hasan Lecturer Dept. of Apparel Engineering Bangladesh University of Textiles(BUTEX)

3. Water Repellency:A Short History In the early 1800's, people could only keep themselves dry by wearing oiled fabrics like cotton. They were heavy, water repellent and smelled pretty bad . In 1823, Scotsman Charles MacIntosh (pictured) was granted a patent on the first 'waterproof' fabric. It was made by squeezing liquid rubber in between two pieces of fabric, then pressing them together . This first range had it's unique problems though - when the weather heated up, the rubber would become sticky, and when it got cold it became too stiff. The 1839 invention of Vulcanization by Charles Goodyear (of the tyres fame) changed the game. Vulcanized rubber rested temperature changes, and made 'Mackintosh' Coats a perfect rainwear solution . Initially, it had success for horse riders, then became adopted for use in the British Army. More recently, The Mackintosh brand has been resurrected as a luxury raincoat manufacturer, and is hugely popular in Japan . Our Mac in a Sac raincoats are manufactured with Polyester; these fabrics are both fully waterproof and breathable, as well as lightweight. Seam sealing ensures that no rain can seep in though stitching holes.    Charles MacIntosh

4. Intro d ucti o n Finishes that repel water, oil and dry dirt are important in all parts of the textile market – for clothing, home and technical textiles. A waterproof textile should withstand the hydrostatic pressure exerted by a column of water from at least a 1 m height before the first drops of water penetrate through the fabric. In practice this is mostly achieved with coatings which have the disadvantages of stiff handle, lack of air and vapour permeability and consequently poor wear comfort

5. Water repellency of fabric water repellent fabrics are those which resist being wetted by water, water drops will roll off the fabric A fabric’s resistance to water will depend on the nature of the fiber surface, the porosity of the fabric the dynamic force behind the impacting water spray.

6. WATER PROOFING “Water proofing is nothing but preventing the passage of both air and water through a fabric”

7. Distinguish between water-repellent and water-proof fabrics water-repellent fabrics water-proof fabrics i. Water Repellent Fabrics have open pores and are permeable to air and water vapour. i. Water-Proof Fabrics have fewer open pores and are less permeable to the passage of air and water vapour. ii. Water-repellent fabrics will permit the passage of liquid water once hydro-static pressure is high. ii. Water-Proof Fabrics are resistant to the penetration of water under much higher hydrostatic pressure. iii. A fabric is made water-repellent by depositing a hydrophobic material on the fibre’s surface. iii. however. Waterproofing requires filling the pores as well as depositing a hydrophobic material on the fibre’s surface.

8. P U R P O SE of Water Repellency For certain uses such as Tarpaulin, Umbrella cloth, Rain coat fabric etc., It is required to give this type of finish as these type of fabrics are generally used against the air and water in the normal life. This finish makes the wearer feel uneasy and uncomfortable as the air circulation is not there.

9. MECHANISIM OF REPELLENCY

10. MECHANISIM OF REPELLENCY If we consider a droplet of a liquid resting on a solid surface at equilibrium then from young’s equation we can say repellency is obtained by reducing the free energy of a fiber surface by using various chemicals which have lower surface energies. These lower surface energy bodies have lower adhesive interactions between the fiber and the liquid then the internal cohesive interactions within the liquid. This prevents spreading of liquid droplets on the solid surface of the textile fabric.

11. CRITICAL SURFACE TENSION For a given homologous series of liquids , the contact angle  is measured on a low surface energy solid . the plot of cosine of the contact angle measured vs the surface tension of the liquid gives a straight line . The intercept of this line at cos =1 (contact angle 0 ) is defines as critical surface tension . the critical surface tension of the solid surface must be lower than the surface tension of the liquid to repel the liquid. Surface tension of water is 72 dynes/cm so to produce a water repellent solid surface it’s surface energy must be lower than water surface tension.

12. WATER REPELLENT FINISH:

13. Non-durable finishes

14. Semi-durable finishes

15. Durable finishes There are several types of durable water repellents, such as 1. Pyridinium compounds    It is Applied to cotton, linen & viscose rayon fabrics. It also endures repeated washings as well as dry- cleaning. It improves the fabric’s appearance. 2. Melamine resins & stearamides compounds It is used on cotton, rayon etc. These have excellent repellency and good tolerance to laundering. 3. Silicone compounds  These are excellent water repellents.  The finish is usually more resistance to dry cleaning than to laundering. Examples: Aerotex, Hydro-Pruf, Zelan, Zepel etc.

16. Durable finishes REQUIREMENTS : The fabric should not become unnecessarily stiff and harsh. It is a Chemical and Property giving finish. Condition: The finish should not affect the fastness properties of dyed goods and feel, strength etc. of the fabric.

17. WATER REPELLENT FINISH: METHODS: A) USING METALLIC SALTS : PROCESS : Pad the fabric with metal salts like Aluminium Acetate or Lead Acetate. Passing the padded fabric through Soap solution like Sodium Stearate. If necessary a little quantity of wax may be added. This method is not permanent.

18. WATER REPELLENT FINISH: B) USING SILICONE EMULSION: They impart not only water repellency but also soft handle and improved draping qualities. PROCESS: Pad – Dry – Cure. If necessary, Resin maybe added in conjunction with silicone. C a t a l y s t s h o u l d b e a d d e d f o r p e r m ane n t d u r ab le f i n i s h . E g . , for catalyst, organo­Metallic salts. They are added just before the application. The pad bath contains Silicone, Resin, Emulsifier and a Catalyst.

19. WATER REPELLENT FINISH: C) THE VELAN PF PROCESS : It imparts water repellency and a soft attractive finish. It is fast to washing, boiling soap solution, dry cleaning etc., It is a compound of Quaternary Ammonium Salt with Pyridine Base and a compound is formed with cellulose in the presence of Sodium acetate. PROCESS: Pad – Dry – Cure – Soaping – Rinse, Padding : 6% Velan PF + 3% Sodium acetate at 35 C, Drying : 60 – 70 C, Curing : 120 C for 2 – 3 mins. Soaping : Soap – 0.2%, Soda – 0.1%, Temp – 35 C, Time – 1 to 2 min. Any soap or other detergent left in the material will reduce its apparent Water repellency.

20. WATER REPELLENT FINISH: D ) USING WAX EMULSIONS : It gives a soft handle and gloss to the fabric. PROCESS : Pad – Dry, Preparation of Pad bath: Take wax emulsion + 3 to 4 times of water Temperature 40 – 50 C Stir Dilute to desired concentration. It can be used along with stiffening or binding agents.

21. DURABLE WATER REPELLENT FINISH: Stearoxy – Methyl Pyridium Chloride is popularly used for durable water repellent finish. Methylol Stearamide, Methylated Methylol Melamine can also be used. A catalyst should also be added. They chemically react with the fibres and produce durable repellent finish. PROCESS: Pad – Dry – Cure For synthetics the following chemicals are added; Zirconium type pyridinium compounds Silicones, Fluro carbons.

22. Applications Areas

23. Application Areas

24. Repellent chemistry Paraffin repellents Stearic acid–melamine repellents Silicone water repellents Fluorocarbon-based repellents

25. Paraffin repellents These were one of the earliest water repellents used,but do not repel oil Typically the products are emulsions that contain Aluminium or zirconium salts of fatty acids (usually stearic acid). These materials increase the finish’s adhesion to polar fibre surfaces by forming polar–non-polar junctions as shown in Figure.

26. continued…….. The paraffinic portion of the repellent mixture is attracted to the hydrophobic regions, while the polar ends of the fatty acid are attracted to the metal salts at the fibre surface. These finishes can be applied by both exhaustion and padding. They are compatible with most kinds of finishes but they increase flammability. Although they are available at relatively low cost and generate uniform waterproof effects, T he lack of durability to laundering and dry cleaning A nd their low air and vapour permeability limits the use of paraffin-based repellents.

27. Stearic acid–melamine repellents Compounds formed by reacting stearic acid and formaldehyde with melamine constitute another class of water- repellent materials. An example is shown in Figure The hydrophobic character of the stearic acid groups provide the water repellency, while the remaining N- methylol groups can react with cellulose or with each other (crosslinking) to generate permanent effects. Advantages of the stearic acid–melamine repellents include increased durability to laundering and a full hand imparted to treated fabrics.

28. Silicone water repellents Poly-di-methyl-siloxane products that are useful as water repellents can form a hydrophobic layer around fibres . The unique structure of the poly-di-methyl- siloxanes provides the ability to form hydrogen bonds with fibres as well as display a hydrophobic outer surface

29. Continued….. In order to gain some measure of durability, silicones designed as water-repellent treatments usually consist of three components, a silanol , a silane and a catalyst such as tin octoate The catalyst enables not only moderate condensation conditions but also promotes the orientation of the silicone film on the fibre surface. The outward oriented methyl groups generate the water repellency.

30. Continued….. During the drying step after pad application,the silanol and silane components can react to form A three-dimensional crosslinked sheath around the fibre . This reaction is often completed after storage of about one day, then providing full repellency. The Si–H groups of the silane are the reactive links in the silicone chain, generating crosslinks or being oxidised by air or hydrolysed by water to hydroxyl groups. These hydroxyl groups may cause further crosslinking, but if too many of them stay unreacted, their hydrophilicity will decrease the repellency.

31. Continued….

32. FLUROCHEMICALS Fluorocarbons (FC) provide fibre surfaces with the lowest surface energies of all the repellent finishes in use. Both oil and water repellency can be achieved. Most FC products are padded, dried and cured. Heat treatment causes an orientation of the perfluoro side chains to almost crystalline structures. This is crucial for optimal repellency. Washing and dry cleaning disturb this orientation and reduce performance. The orientation must be regenerated by a new heat treatment (ironing, pressing or tumble drying).

33. SYNTHESIS OF FLUROCARBONS FC repellents are synthesized by P erfluoro alkyl groups into acrylic U rethane monomers that can then be polymerized to form fabric finishes .

34. The final polymer, when applied to a fibre,should form a structure that presents 1) A dense CF outer surface for maximum repellency. 2) A typical structure is shown

35. RECENT DEVELOPMENT IN FLUROCARBON BASED WATER REPELLENT CHEMICALS 1.Bio-nic finish 2.C6 technology 3.Dual action FC 4.Flurocarbon with boosters

36. BIO-NIC FINISH A novel FC development is inspired by nature and therefore called Bio- nic finishes. Fluorocarbon polymers are applied together with Dendrimers that causing self orientation where the fluorocarbon chains are enriched on the surface and cocrystalline with the Dendrimers and Obtain same result as conventional FCs without decompose persistent & bio accumulative compounds. .

37. Continued…..

38. C6 technology Many flurocarbon originated water repellent products are based on 8-carbon chain structure (C8) but in manufacturing a trace amount of Perfluorooctanoic acid (PFOA) & Perfluorooctane Sulfonate (PFOS) generated as a byproduct. There are potential health & safety concerns with both PFOS and PFOA. Both are toxic , persistent & bio accumulating. To overcome this problem 6-carbon chain structure (C6) based water repellent chemicals are introduced which is free from PFOA & PFOS

39. DUAL ACTION FLUROCARBON Naturally, water repellency impedes the access of the washing liquor during laundering. Therefore, so-called dual-action fluorocarbon block copolymers were developed, which combine repellency in the dry state and soil-release effects in an aqueous environment Dual active fluorocarbons enable a better removal of oily stains and dirt in domestic washing or laundering. With conventional FC products, the wash water is hindered from wetting and penetrating the fabric. Dual action fluorocarbons are called Hybrid fluoro -chemicals because they are block copolymers containing hydrophobic (like the usual FCs) and highly hydrophilic segments

40. Continued….. In air the per-fluorinated side chains are, as usual, outwardly oriented and develop high repellency, but in water the double face surface structure. and the hydrophilic segments turn outwards to promote the wash effect as an oily soil release finish. During heat drying or ironing the sandwich-like surface again to generate water, oil and soil repellency.

41. FLUROCARBON WITH BOOSTERS S ome new FC products, drying in air is sufficient (laundry–air–dry or LAD products). Tailored FCs and blocked isocyanates, the so-called boosters, are used for this effect. Depending on the kind of blocking group, T he isocyanate is activated at different temperatures and then reacts with the functional groups of the FC, and with the fibre or with itself (crosslinking). This fixation on the fibre surface provides durability to washing, dry cleaning and rubbing as a second important effect. film formation and thereby higher repellency effects.

42. Rapid and simple tests for water repellency 1. The water drop test 2. The spray test

43. TESTING PARAMETERS 1. 2. 3. static drop tests, spray tests and hydrostatic pressure tests. If there is insufficient differentiation, even with a higher distance between sample and nozzle, the water resistance with the hydrostatic pressure test should be checked. Some of the most important quantitative test methods are given in Table 6.3. For fabrics that require durable repellency performance, the test methods in Table 6.3 can be applied to fabrics that have been laundered or dry cleaned by standard methods (as AATCC TM 124 and TM 86) in order to determine the durability of the repellency properties. Three groups of corresponding test methods may be distinguished,

44. TESTING PARAMETERS

45. TESTING PARAMETERS \\

46. TESTING PARAMETERS 3

47. TESTING PARAMETERS

48. N ature of repellent finishes to reduce adhesion Silicones and fluorocarbon polymers cannot easily be stripped off, Especially when they are crosslinked. As it is the nature of repellent finishes to reduce adhesion, there are problems with backcoating and laminating of fabrics finished by padding fluorochemicals . One solution is the one side application of the repellents by nip-padding, spray, foam or squeegee techniques.

49. Environmentally critical products Long-life by-products of the fluorocarbon synthesis by electro-chemical fluorination are the per- fluoro octansulfonic acid and their corresponding salts (per- fluoro - octyl sulfonate, PFOS). These environmentally critical products with concerns about persistence, bio-accumulation and potential toxicity.

50. Global Market Share of Repellent Textiles and Apparel

51. Global Water Proof Breathable Market

52. Global Market About the market research The market is segmented by Raw Material (Polyurethane, Polytetrafluoroethylene (PTFE), Polyvinylidene Fluoride (PVDF), Polyester Microfilament Yarns, Fluoropolymers , and Other Raw Materials), Textile (Densely Woven, Membrane, and Coated), End-user Industry (Garments, Footwear, Gloves, and Other End-user Industries), and Geography (Asia- Pacififc , North America, Europe, South America, and Middle East & Africa)

53. Market Overview The global waterproof breathable textiles market is expected to record a CAGR of around 6% during the forecast period, owing to the upsurge in preference toward high-performance and comfortable fabrics, growing fitness awareness, and increasing the use of recycled PET bottles to manufacture waterproof breathable fabrics. The increasing involvement in outdoor activities and the changing fashion trends are expected to hinder the growth of the market studied. Advancement in plasma and silicon-based technology is likely to act as an opportunity in the forecast period. 

54. Global Market Major Players * W . L. Gore & Associates Inc. * General Electric ( eVent FABRICS) * Sympatex Technologies GmbH( SympaTex ) * Mitsui & Co. Ltd ( pertex ) * Clariant

55. References Physical Testing of Textiles; B P Saville, Page:228-242 https :// www.macinasac.com/blogs/news/7569384-who-invented-the-waterproof-coat https:// www.slideshare.net/Tanveer_ned/repellent-finishes-oil-and-water https:// www.slideshare.net/SaddamJuewel/flame-retardant-finish-water-repellent-finish https:// atslab.com/environmental-testing/waterproof-testing https://www.mordorintelligence.com/industry-reports/waterproof-breathable-textiles-market https://www.academia.edu/16036522/Effect_of_different_types_of_water_repellent_agent_used_in_cotton_fabric_finishing_and_their_quality_and_cost_analysis