Waterproof finishes

Waterproof Finishes. Waterproofing results from coating a fabric and filling the pores with film-forming material such as varnish, mbber, nitroceUulose, wax, tar, or plastic. The materials may be appHed as hot melts, eg, waxes or some polymers, as solvent solutions, or as aqueous latexes. The continuity of the film provides the water resistance. Except for tents, tarpauHns, and covers, coated fabrics have been largely replaced by plastics, and by fabrics treated with water and oU repeUents that do not reduce permeabUity to air and water vapor. Eabrics are also commonly laminated to films, such that the total stmeture is waterproof (15), or in some cases water-resistant but breathable (16). 

Waterproof finishes are also obtained by depositing a surface-active cation on the fibre and then causing polymerization to take place by the application of heat. Velan PF is stearoamidomethyl pyridinium chloride. 

Picconol . [Hercules] Aliphatic hydrocarbon resin emulsions used in combination with other aq. thermoplasdc and/ or elastomoic systems to pr ce coatings, paints, and adhesives tackifiers for natural and syn. rubber systems waterproof finishes for paper, textiles, and textile backings. 

USE Meerwein-Ponndorf reactions alcoholysis and ester exchange synthesis of higher alkoxides. chelates, and acyl-aies formation of aluminum soaps, formulation of paints waterproofing finishes for textiles. 

It is used in a number of organic synthetic reactions and in the manufacture of many types of products, including aluminum soaps, paints, and waterproofing finishes. 

Products and Uses Added to exterior paints and varnishes. Derived from seeds of plant grown in the Orient. Used for waterproofing, finishes, and packaging materials. 

Chem. Descrip. Aliphatic hydrocarbon resin emulsions Uses Resin emulsion used in combination with other aq. thermoplastic and/or elastomeric systems to produce coatings, paints, and adhesives extender, tackifier for NR, SR waterproof finishes for paper, textiles esp. suitable for use in high-styrene SBR, EVA resin, and polyacrylic-based latex paints, and in adhesives for bonding films, fibers, and granular materials food-pkg. and processing operations Properties Gardner 9 (50% in toluene) liq. dens. 0.97 kg/l vise. 3000 cps soften, pt. (R B) 63 C pH 8.5 anionic 50% aq. disp. 

Tarpaulin tar- p6-bn [prob. fr. har -h -palling, -pauling fr. pall] (1605) n. A water-resistant fabric used to protect loads or materials from the elements. Tarpaulin may be a coated fabric, a fabric with waterproof finish, or a fabric that is tightly constructed to prevent water penetration. 

Uses Wetting agent for use in fluorochemical and other waterproofing finishing applies. 

Gel coats are pigmented polyester coatings appHed to the mold surface and are an integral part of the finished laminate. Gel coats are used widely on hand lay-up and spray-up parts to enhance surface aesthetics and coloration as weU as to provide an abrasion-resistant waterproof surface that protects the underlying glass-reinforced stmcture. 

Early waterproofing treatments consisted of coatings of a continuous layer impenetrable by water. Later water-repellent fabrics permitted air and moisture passage to improve the comfort of the wearer. Aluminum and zirconium salts of fatty acids, siUcone polymers, and perfluoro compounds are apphed to synthetic as well as natural fibers. An increase in the contact angle of water on the surface of the fiber results in an increase in water repeUency. Hydrophobic fibers exhibit higher contact angles than ceUulosics but may stiU require a finish (142). 

Water Repellency and Water Resistance. Water repeUency is defined as the abihty of a textile fiber, yam, or fabric to resist wetting, whereas water resistance is a general term appHed to a fabric s abiUty to resist wetting and penetration by water (2). A third term, waterproof, is appHed to those fabrics that do not allow any water penetration at all. Waterproof fabrics are generally coated with an impermeable surface layer that does not allow air permeabihty. Water-repellent finishes are hydrophobic compounds that are appHed to fabrics to inhibit water penetration while still allowing air permeabihty. 

Fabric Construction for Water RepeUency. Fabric constmction, including twist, ply, and coarseness of yams, affects the performance of water repeUents. Waterproof films can more easUy be formed on close weaves than on open-weave fabrics. Hydrophobic finishes, which make individual fibers repeUent without altering fabric porosity, are generaUy appUed to fabrics whose pores are smaU (37). The relation of rainwear fabric constmction to the performance of repeUents has been reviewed (38). Some reports indicate that fabric roughness reduces repeUency (28,37). Mechanical action on fabrics, even after treatment, can reduce repeUency if the action increases fiber roughness or exposes fibers that have Utfle repeUent treatment. 

A/-substituted, long-chain alkyl monomethylol cycHc ureas have also been used to waterproof cotton through etherification. Other water repellent finishes for cotton are produced by cross-linked siHcone films (56). In addition to the polymeri2ation of the phosphoms-containing polymers on cotton to impart flame retardancy and of siHcone to impart water repeUency, polyduorinated polymers have been successfuUy appHed to cotton to impart oil repeUency. Chemical attachment to the cotton is not necessary for durabUity oU repeUency occurs because of the low surface energy of the duorinated surface (57). 

Clothing - man-made fibres such as rayon and nylon, dyes, waterproofing and other surface finishing chemicals. 

Isocyanates (RNCO) are industrially relevant compounds which find application in several fields [9, 106]. Many isocyanates serve as the starting materials for the manufacture of plant protection agents, pesticides, dyes, resins and plastics, textile waterproofing agents, detergents, bleaches, and adhesives. They are also widely used in surface coatings such as paints, sealants and finishes, and in the manufacture of rubbery plastics such as those used to coat wires. Traditionally, diisocyanates are the primary feedstock for the production of polyurethanes. The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate (MDI), 34.1% was toluene diisocyanate... 

The addition of 0.02% of an aqueous emulsion of silicone liquid into sand fibre slate reduces its water absorption by two and noticeably increases its cold resistance. Silicone liquids can be also put on finished constructions in the form of a 5% aqueous solution, which penetrates to the depth of 3-6 mm and after drying forms a durable waterproof surface for 5-10 years. This treatment can be used on various works of art, famous architectural buildings, etc. Plastered facades can also be waterproofed with good results. Treated plaster does not absorb rain drops on the other hand, common plaster completely absorbs all rain drops after 30 seconds. 

The oldest repellent finish is to repel water. The purpose of this finish is self evident. Drops of water should not spread on the surface of the textile and should not wet the fabric. The drops should stay on the surface and easily drip off. Similarly, oil repellent finishes should prevent oily fluids from wetting treated textiles. In a similar manner, soil-repellent finishes should protect textiles from both dry and wet soils. In all cases, the air permeability of the finished fabric should not be significantly reduced. Waterproofing treatments will not be covered in depth. A waterproof textile should withstand the hydrostatic pressure exerted by a column of water from at least aim 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. 

Holme I, Water repellency and waterproofing , in Textile Finishing, Heywood D (ed.), Bradford, Society of Dyers and Colourists, 2003,135-213. 

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