Coatings and Coating Processes

Brendley, W. H. Haag, T. H. Nonpol luting Coatings and Coating Processes" Plenum New York, 1973. 

J.N. Undady, ed. Coatings and Coatings Processes for Metals. NY, ASM Pubk,... 

Nonpolluting Coatings and Coating Processes, edited by J. L. Gardon and J. W. Prane (Plenum Press, New York). Chapters on most of the newer developments. 

Selection of the most promising coatings and coating processes will be made after the charcicterization task. Criteria for selection will include not only performance (i.e., wear, adhesion, friction coefficient, thermal shock resistance and thermal stability) but manufacturability/cost factors as well. Using these criteria, a coating system having acceptable cost/benefit relationships will be selected. 

Non-Polluting Coatings and Coating Processes Transport Through Polymer Films Polymers and Ecological Problems Water Soluble Polymers Thermomechanical Analysis of Polymer Solids... 

To prevent rejects, retouching and to reduce cost of conservatively more than enough applied powder in powder coating processes a handy measurement system allowing to determine the... 

Fig. 26. SEM micrographs illustratiag the effects of airborne basic chemical contamination, (a) This image was formed when a positive-tone CA resist was processed without any delay after coating, (b) This image was formed when an identical film was stored after coating for 15 minutes in an atmosphere containing 10 parts per billion on A/-methylpyrrohdone, and then processed identically to the first film.

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. 

Two basic methods are used for the appHcation of protective coatings to metal containers, ie, roUer coating and spraying. RoUer coating is used if physical contact is possible, eg, coating of metal in sheet and coil form. Spraying techniques are used if physical contact is not possible, eg, to coat the inside surface of two-piece drawn and ironed can bodies (see Coating processes). 

Each type of metallic coating process has some sort of hazard, whether it is thermal energy, the reactivity of molten salt or metal baths, particulates in the air from spray processes, poisonous gases from pack cementation and diffusion, or electrical hazards associated with arc spray or ion implantation. 

The appHcation of this type of conversion coating can be by spray or immersion and is easily tailored to the needs of the user (see Coating processes). The number of stages may vary from two, ie, clean and phosphate then rinse, to as many as five, ie, clean, rinse, phosphate, rinse, and post-treat. The performance requirements dictate the number of operation stages as well as the need for a post-treatment. 

The bath components for a nitrite—nitrate accelerated bath basic to this conversion coating process are (/) 2inc metal or 2inc oxide dissolved in acid (2) phosphate ions added as phosphoric acid (J) addition of an oxidant such as sodium nitrite and (4) addition of nitric acid. Other oxidants such as peroxide, chlorate, chlorate in combination with nitrate, or an organic nitro compound may also be used. 

When selecting a particular paster adhesive, coating material, and coating process for sohd fiber packaging, the fact that sohd fiberboard lacks the open-flute stmcture (to facihtate exit of moisture from internal phes of paperboard) should be considered. It is generally desirable to minimize the amount of process water added with the adhesive or coating with sohd fiber products. Moisture trapped in the filler phes can result in pin holes or bhsters in the coating and/or warp of the sheet (15). 

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