Coating/dispensing Spraying

Coating/dispensing Brush, trowel Spraying, extrusion Roll application (manual or automatic) Hot melt equipment Stencil, dip coating Film adhesives Pressure sensitive adhesives Preformed adhesives and sealants (in solid form)... 

For bottles, there are special bottle dispensers in use like simple hand pumps or volumetric dispenser. Adhesive dispenser controllers are used to offer a high accuracy to meet customer requirements for multivalve dosing or coating or spray operations. O Figure 37.11 below shows typical dispensing equipment for one and two-part adhesive formulations. It contains a cartridge gun, cartridges, and a nozzle. 

The rise time for airless-sprayed urethane foam is about 30 s. It can be refoamed for additional thickness after this period. The foam can be walked on after 3 to 4 minutes and reaches its full properties in 24 h. The airless spray gun is held about 30 in. (76 cm) from the surface and moved steadily over it. Dispensing rates of 4 to 6 lb (1.8 to 3.6 kg) per minute are generally considered optimum for most spray applications. The surface on which the foam is sprayed must be free of loose scale or grease. The adhesion of urethane foam to steel is essentially equal to the tensile strength of the foam, provided the surface is clean. Aluminum surfaces, on the other hand, do not provide a good bond unless a primer coat, such as vinyl wash, is used prior to spray foaming. 

Apack s Canadian subsidiary is promoting use of its composite in hot- and cold-drink disposable cups to replace EPS. Apack Canada s cups are foamed to 0.2 g/cc density, reportedly providing better insulation than paper cups. A co-polyester coating prevents moisture penetration, permits quality printing, and provides enough insulation (in hot cups) to dispense with costly paper sleeves. The sprayed-on coating uses a blend of an Eastman co-polyester and a second biodegradable resin to get a balanced viscosity. 

Teflon self-lubricating plastic bearings can be used in situations where a lubricant might contaminate the system. There are also a variety of nonoily lubricants such as silicone lubricant (usually dispensed as a spray) and molybdenum disulfide (suspended in petroleum distillates that evaporate to leave a dry coating). Molybdenum disulfide is an excellent alternative to graphite for lubrication of moving parts in a high-vacuum system. 

A very promising new field of application for ASA and ASA-PC blends is automotive body panels. Until now, these have been made almost exclusively from painted metal. Since painting is costly, automotive companies are attempting to save costs by developing technologies that dispense with this operation. As in the case of the smart car, bulk coloured thermoplastics (e.g. PBT -PC blends) may be used to make body panels. However, such parts must still be sprayed with a top coat in order to achieve the desired scratch resistance and UV stability. 

At the other extreme are aerosols, where neither the product nor the pack can exist without the other. Aerosols can be used to dispense powders, liquids, sprays, gels, true aerosol clouds, etc., either as a continuous delivery or as a controlled or metered dose. The main container component can be fabricated from metal (aluminium or tinplate), glass or plastic coated glass, or plastic (e.g. polyester), and the valve components from combinations of plastic, metal and rubber. Depending on the product usage, the majority of the tests listed earlier may have to be involved in the clearance of an aerosol, particularly if it is a metered dose aerosol for administration of a product to the lungs (a critical administration route). 

To offer more flexibility in coating applications, one equipment supplier has developed a coating applicator capable of a wide range of viscosities (30-3,500 cps) and three dispense options atomized spray, nonatomized bead, or nonatomized monofilament (Figure 10-6). 

A new two-part, sprayable ceramic coating designed to protect metal surfaces on industrial equipment from wear, abrasion and corrosion is now available. Packaged in a reusable dualcartridge dispenser, Loctite Nordbak 7255 sprayable ceramic coating can be sprayed onto metal components to create smooth, low-friction surfaces that improve equipment efficiency. 

Adhesives can be applied manually or automatically by brushing, spreading, spraying, roll coating, placed using a backing strip or dispensed from a nozzle. 

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