Knife spread coating

The use of the vinyl polymer in fluid form offers distinct advantages to the manufacturer of vinyl products. The most important obvious advantage is the relatively lower cost of liquid processing equipment and accessories as compared to those required for processing of solid or powder thermoplastics. For example, a spread coating line, for example, knife or roll coater, even with appropriate unwind and takeup accessories, is less expensive than a banbury-mixer-mill calender configuration. 

Powder is blended with the paste at an addition level of 1 wt%. The paste is spread coated at a thickness of 2 mm by knife over roller over bed on to a non-woven support. Particles of silicon carbide and colored quartz are each scattered on the surface at the rate of 100 g/m. The paste is then gelled for 3 minutes at 170°C. Powder at the rate of 50 g/m is applied and further silicon carbide is applied at the rate of 100 g/m. The product is then fused at 190°C for 3 minutes and embossed. 

Spread coating n. A process for coating fabrics, sheet metals, etc., with fluid dispersions such as vinyl plastisols. The substrate is supported on a carrier, and the fluid material is applied to it just ahead of a blade or doctor knife that regulates the thickness of the coating. The deposit is then heated to fuse the coating to the substrate, often followed by embossing to impart texture. 

Spreader . (1) See torpedo. (2) Any device, such as a knife or roller, a part of spread-coating equipment that helps to produce an evenly thick coating. 

Plastisols have a variety of uses. They are ideally suited for spread coatings on continuous webs of fabric or paper by conventional knife or roller coating equipment. They may also be molded or cast into flexible shapes. 

Applications. Vinyl plastisols can be applied by spread coating, knife coating, roll coating, molding, dipping, and spraying the most widely used application is coating. 

Air-Knife Coating n A coating technique especially suitable for thin coatings such as adhesives, wherein a high-pressure jet of air is forced through orifices in a knife to meter and control the thickness of the coating. See also Spread Coating. 

Knife Coating n A method of coating a substrate in which the substrate, in the form of a continuous moving web, is coated with a plastic whose thickness is controlled by an adjustable knife or bar set at a suitable angle to the substrate. Spread Coating and... 

The coatings were applied to one side of a steel substrate by means of a spray gun for the lower viscosity coatings, or by doctor blading with an adjustable Gardner knife for the higher viscosity materials. A casting technique was also used in which a known volume of the coating material was poured into a known area defined by heavy tape and was allowed to spread while on a level surface. 

PVPyrH Poly-4-vinylpyridine (PVPyr) prepared by conventional persulfate catalyzed polymerization was dissolved in ethyl alcohol or methyl Cellosolve (2 to 3% solution) for application to polyester film substances. These films adsorb heparin from solutions of sodium heparin to produce anticoagulant surfaces (PVPyrH). Films were painted on, or spread by knife coating. 

Figure 4 shows the relatively even adsorption on polyvinylpyridine surfaces spread by knife coating and dipped into radioactive heparin solution (500 fig./ml.) for 6 minutes. Six discs each 1 inch in diameter were die cut from each of two duplicate preparations which were similar in visual evenness to the ones shown. Planchet counts gave the results shown below ... 

With respect to application methods, blood glues can be spread on wood surfaces by most conventional means. These include roller, knife, and extrusion but do not include curtain coating or spray, for which the glues must be thinned below practical film retention levels. The major advantage of alkaline-dispersed blood glues over all other wood glues except resorcinol-based synthetic resin adhesives is their sensitivity to heat, resulting in extremely... 

Ion plating was used by Yoshida and co-workers [183] to make carbon fiber reinforced Al. A typical ion plating procedure is to spread the carbon fiber with an air knife, feed into a vacuum chamber at about 2 Pa in Ar, apply a potential of 0.5 kV to form an Ar plasma. The Al wire fed is into a crucible where it is evaporated onto the moving fiber. The coated fiber formed by ion plating can be processed by hot pressing/diffusion bonding. 

An air knife can be used to spread a carbon fiber tow and form a thin veil of carbon fiber or tissue, which can be used to hold a resin rich gel coat on the surface of a fiberglass laminate construction to give a high surface finish concurrent with added microcrack suppression, as well as provide additional chemical resistance. It will give better performance than a glass tissue due to the absence of wicking. 

Coiling soup n. In coating or spreading operations, a defect caused by the curling or turning motion of a bank of lacquer or other soup compound in front of a doctor knife, or similar application device, wherein streaks are formed on the surface of the coated fabric due to uneven application of the soup. 

Direct coating n. The simplest method of coating, this procedure involves spreading the coating with a knife. The moving fabric substrate is usually supported by a roller or a sleeve. The gap between the knife and the fabric determines coating thickness. 

Drawout n. A method of application in which the coating is applied, usually on paper, by spreading the pigment-vehicle mass evenly with a broad knife. Useful for examination of masstone, undertone, opacity, printing strength, and in some cases, fadeometer ratings of pigments. 

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