Epoxy phenohc

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. 

Epoxy phenoHc coatings either are made by blending of a soHd epoxy resin with a phenoHc resin or are the products of the precondensation of a mixture of two resins. A three-dimensional stmcture is formed during curing which combines the good adhesion properties of the epoxy resin with the high chemical resistance properties of the phenoHc resin. The balanced properties of epoxy phenoHc coatings have made them almost universal in their appHcation on food cans. 

Vinyl organosol coatings, which incorporate a high molecular weight thermoplastic PVC organosol dispersion resin, are extremely flexible. Soluble thermosetting resins, including epoxy, phenoHc, and polyesters, are added to enhance the film s product resistance and adhesion. 

Shipment and Storage, Specifications. A/-Vinyl-2-pyrrohdinone is available in tank cars and tank trailers and in dmms of various sizes. Shipping containers are normally steel or stainless steel. Tank cars are provided with heating coils to facihtate unloading in cold weather. Rubber, epoxy, and epoxy—phenohc coatings are attacked and must be avoided. Carbon steel has been successfully used for storage tanks, but stainless steel preserves product quahty better. Aluminum and certain phenohc coatings are also satisfactory. 

Chelating agents are commonly used in epoxy-phenohc adhesives to stabilize the metal interface. In the epoxy-phenohc formulations given above, quinolinate and gahate are used... 

Vacuum impregnating n. The process of impregnating electrical components by subjecting the parts to a moderate vacuum to remove air and other volatiles, introducing the impregnant to penetrate the parts, then releasing the vacuum and curing. Epoxy, phenohc, and polyester resins are often used. 

Polyphenylene sulfide, epoxy, phenohc (glass), nylon (glass) pol5dmide, diallyl phthalate, polyphthalamide, TP polyester... 

The epoxy conversion for the 2.00 stoichiometry should be 50% if only the primary epoxy-phenohc reaction occurs, due to exhaustion of the phenohc limiting reagent. For TPP concentrations up to 1.0 phr, the total conversion is very near to that which corresponds to 50% conversion of the epoxy. Thus, for ramp cures in this concentration range, the reaction appears to consist solely of the epoxy-phenohc addition. 

PI adhesives require higher cure temperatures than epoxy-phenohc adhesives. Curing at 250 °C is usually adequate when service temperatures do not exceed the cure temperature. Volatiles are released during the cure of PI adhesives. The best results are, therefore, obtained when the volatiles can freely escape (e.g., honeycomb or perforated-core structures). For long-term aging at temperatures in the range of 204—316 °C, Pis are superior to PBI and epoxy-phenolic adhesives. 

Suggested adhesives include modified acrylics, epoxies, polyesters, resorcinol-formaldehyde, fiirane, phenol-formaldehyde, poljrvinyl formal-phenohc, polyvinyl butyral, nitrile rubber-phenohc, polyisobutylene rubber, polyurethane rubber, reclaimed rubber, melamine-formaldehyde, epoxy-phenohc, and cyanoacrylates. For maximum adhesion, primers should be used. Nitrile-phenohcs give excellent bonds if cured under pressure at temperatures of 149 °C. Lower-strength bonds are obtained with most rubber-based adhesives. 

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