Coatings vinyl

Types of internal enamel for food containers include oleoresins, vinyl, acryflc, phenoHc, and epoxy—phenoHc. Historically can lacquers were based on oleoresinous products. PhenoHc resins have limited flexibiHty and high bake requirements, but are used on three-piece cans where flexibiHty is not required. Vinyl coatings are based on copolymers of vinyl chloride and vinyl acetate dissolved in ketonic solvents. These can be blended with alkyd, epoxy, and phenoHc resins to enhance performance. FlexibiHty allows them to be used for caps and closures as weU as drawn cans. Their principal disadvantage is high sensitivity to heat and retorting processes this restricts their appHcation to cans which are hot filled, and to beer and beverage products. 

Leather-like materials now important in the market are of three main classes (/) vinyl-coated fabrics, (2) urethane-coated (synthetic) fabrics, and (J) man-made leathers. To appreciate their leather-replacement capabiUties it is necessary to know the stmcture of natural leather. 

Vinyl-Coated Fabrics. Leather substitutes are designed to imitate the appearance of leather with its grain surface. This requirement has been accomphshed by coating substances that are capable of forming a uniform film, and was first met by plasticized poly(vinyl chloride) (PVC). A leather-like material termed vinyl-coated fabric was developed in the 1930s in the United States and Germany. Shortages of leather after World War 11 spurred the expansion of this material. 

The constmction of vinyl-coated fabrics varies according to its appHcation. A vinyl-coated fabric used for automobile seat covers is shown in Figure 3 a woven fabric is the substrate. The material is durable but stiff and heavy. Incorporating an expanded foam stmcture into the coating layer reduces the weight (Fig. 4), and replacing the woven substrate fabric with a soft knit fabric improves fiexibihty. 

Fig. 3. Cross-sectional view of vinyl-coated fabric with PVC coating layer.

Vinyl-coated fabrics exhibit high density, extremely low water vapor and air permeabiUty, cold touch, poor flex endurance, and plasticizer migration. However, they have good scratch resistance and colorabiUty and are inexpensive. 

Product is nylon in man-made leathers cotton in urethane- and vinyl-coated fabrics. 

Weight, Thickness, and Density. The thickness differs according to appHcation. Vinyl-coated fabrics are very heavy and dense. Urethane-coated fabrics and man-made leather are very light and two-thirds to one-half leather in density. 

Water-Vapor Permeability. Water-vapor permeabiUty depends on the polymer used for the coating layer and its stmcture. Vinyl-coated fabrics have Httie water-vapor permeabiUty due to the coating layer. Although polyurethane polymer is water-vapor permeable, urethane-coated fabrics also have low permeabiUty values due to their soHd layer stmcture. On the other hand, man-made leathers have good permeabiUty values as high as that of leather due to their porous layer stmcture. The permeabiUty of grain-type is lower than that of suede-type, influenced by finishing method. 

Other Properties. With respect to dry-cleanabiUty, vinyl-coated fabrics are worse than the others due to dissolution of plasticizer in the cleaning solvent. Only man-made leathers with poromeric nonwoven can be skived, spHt, and cut in the same manner as leather. 

Vinyl-Goated Fabrics. Manufacturing methods for vinyl-coated fabrics now available are calendering and extmsion for thicklayer, and paste coating for thin layer. Both soHd and foam vinyl-coating layers are used. 

In the calendering method, a PVC compound which contains plasticizers (qv) (60—120 phr), pigments (qv) (0—10 phr), fillers (qv) (20—60 phr), stabilizers (10—30 phr), and other additives, is kneaded with calender roUs at 150—200°C, followed by extmsion between clearance-adjusted roUs for bonding onto the substrate. This method is employed for products with thick PVC layers, ie, of 0.05—0.75 mm thickness. The main plasticizer used is di-2-ethylhexyl phthalate (DOP). For filler to reduce cost, calcium carbonate is mainly used. A woven or knit fabric made of cotton, rayon, nylon, polyester, and their blend fiber is used as substrate. For foamed vinyl-coated fabrics, the bonded materials are heated in an oven to decompose the foam-blowing... 

In the paste coating method, a PVC paste, which contains emulsion-polymerized PVC and additives, is appHed onto a substrate and heated to gelation before fusion to produce a coating layer. This method is employed for products with a thin layer, ie, of 0.007—0.05 mm thickness. For foamed vinyl-coated fabrics, a substrate is laminated onto a transfer paper on which a PVC paste containing a foam-blowing agent has been appHed and geUed. After removal of the transfer paper, the paste is blown. 

Excluding floor coverings, vinyl-coated fabrics, and textiles. Based on gross weight of pigment. 

Vinyls. Vinyl resins are thermoplastic polymers made principally from vinyl chloride other monomers such as vinyl acetate or maleic anhydride are copolymerized to add solubUity, adhesion, or other desirable properties (see Maleic anhydride, maleic acid, and fumaric acid). Because of the high, from 4,000 to 35,000, molecular weights large proportions of strong solvents are needed to achieve appHcation viscosities. Whereas vinyls are one of the finest high performance systems for steel, many vinyl coatings do not conform to VOC requirements (see Vinyl polymers). 

The wash primer is a special type of vinyl coating. This material contains a poly(vinyl butyral) resin, zinc chromate, and phosphoric acid in an alcohol-water solvent. The coating is so thin it is HteraUy washed onto a freshly blasted steel surface, where it passivates the metal surface by converting it to a thin iron phosphate-chromate coating. The alcohol solvent makes it possible to apply the coating over damp surfaces. The coating forms the first coat of... 

Vinyls Section 12.3.2. These have been used on concrete for a variety of situations. Thinned down, they have good penetration of the surface and provide a good base for subsequent applications of heavily bodied, thick viscous vinyl coatings. However, since they dry quickly but contain a high proportion of solvent, care must be taken to avoid solvent entrapment in the pores of the concrete. 

Rigid toom core sandwich with rigid plastics skin vinyl-coated glass Insect screening... 

Insulation—Perforated and solid metal instrument trays should be completely enclosed with 1 in (25 mm) minimum thickness insulating block or board. The insulation should be secured with stainless steel bands and should be weatherproofed with vinyl-coated galvanized steel sheet. The bands and sheet should be in conformance. The metal jacket should be secured with stainless steel, sheet metal screws or bands. 

A generalised model of electrical equivalent circuit for painted surfaces has been considered in many of the recent publications. Googan ( 2) used it to study vinyl coatings free of defects and coatings containing defects. Electrocoatings were also evaluated. Muslanl et al (27) in their investigation of mild steel... 

Vinyl coatings are used primarily on metal surfaces. They provide excellent protection by their strong cohesive forces, although their adhesion to the metal is not good. Used with a phosphoric acid-containing primer to etch the metal surface, this adhesion is markedly improved. The primer also contains poly(vinyl butyral) and is approximately 0.2-0.3 mil thick (1 mil = 1/1000th inch). Poly(vinyl butyral) is made from polymerized vinyl acetate by hydrolysis and reaction with butyraldehyde. 

Coverlight HTV Vinyl-coated nylon fabric Reeves Brothers... 

Isophorone is a solvent for a large number of natural and synthetic polymers, resins, waxes, fats, and oils. Specifically, it is used as a solvent for concentrated vinyl chloride/acetate-based coating systems for metal cans, other metal paints, nitrocellulose finishes, printing inks for plastics, some herbicide and pesticide formulations, and adhesives for plastics, poly(vinyl) chloride and polystyrene materials (Papa and Sherman 1981). Isophorone also is an intermediate in the synthesis of 3, 5-xylenol, 3, 3, 5-trimethylcyclohexanol (Papa and Sherman 1981), and plant growth retardants (Haruta et al. 1974). Of the total production, 45-65% is used in vinyl coatings and inks, 15-25% in agricultural formulations, 15-30% in miscellaneous uses and exports, and 10% as a chemical intermediate (CMA 1981). 

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