Food can coatings

Use Metal primers, bottle cap coatings, food can coatings, appliance coatings. 

Uses for dispersion polymers include surface coatings for metal coatings, particularly for the automotive industry, food can coating, chromatographic medium, electrophotographic toners, and pressure sensitive adhesives. 

Chem. Descrip. Phenolic resin sol n. in n-butanol Uses Crosslinking agent for hydroxyl-contg. polymers such as epoxy, polyester, vinyls, acrylics for drum and pall coatings, low-VOC applies., coli/food can coatings Features Max. chem. resist. 

Uses Pigment dispersant, wetting agent for trade sales and industrial solv.-based coatings, in food can coatings... 

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. 

Phenolic resins are useful surface coating materials. Resols are useful for stoving lacquers for coating chemical plant, textile equipment, razor blades, brassware cuid food cans. Phenolic resins are used with poly(vinyl formal) as a flexible, tough and solvent-resistant wire enamel. Oil-soluble resins based on synthetic phenols form the basis of some gloss paints. 

Two-piece food cans may be made by a draw-redraw process, in which lacquer is first applied to and cured on sheet. Blanks are then cut from the sheet and the can is drawn from the blank in two or three stages. The lacquer deforms with the drawing process and lubricates the draw. It then becomes the interior protective coating. Although epoxy-phenolic solvent-borne lacquers are used, even better drawing properties are obtained from organosols. These are dispersions of colloidal polyvinyl chloride powder in solutions of other mixed resins in solvent, e.g. chosen from epoxy, polyester, vinyl and phenolic. 

To appreciate the potential changes in food cans, it is necessary to describe briefly the steel-based materials used in modern can manufacturing operations. The tin can is made from a special grade of thin gage, low carbon, cold-rolled steel, which is generally referred to as a tin mill product. The base steel is coated with either tin, a chromium-chromium oxide system, or it is just cleaned and oiled. It may also be coated with organic coatings. 

Cemented and Welded Cans. Beer and carbonated beverage cans, made by the now familiar cementing (22) and welding (20) processes, are shown in Figure 8. These processes could also be used for sanitary processed food cans. Enameled TFS materials are used for these cans. Corrosion performance of the enameled, cemented, and welded cans is similar to that of enameled soldered cans for products which do not require the cathodic protection usually supplied by the tin coating. 

Brotons, J.A., Oleaserrano, M.P., and Villalobos, M. et al. (1995). Xenoestrogens released from lacquer coatings in food cans. Environmental Health Perspectives 103, 608-612. 

Certain areas of pigment application in the printing ink industry challenge the performance of a pigment more severely than others. To be useful in inks for food cans, for instance, the inside coatings must be capable of being sterilized with steam without degradation. For bank notes, currency, and cheques, special security properties are needed. 

Bisphenols is a broad term that includes many chemicals with the common chemical structure of two phenolic rings joined together by a bridging carbon. Bisphenol A is a monomer widely used in the manufacture of epoxy and phenolic resins, polycarbonates, polyacrylates and corrosion-resistant unsaturated polyester-styrene resins. It can be found in a diverse range of products, including the interior coatings of food cans and filters, water containers, dental composites and sealants. [4]. BPA and BP-5 were selected for testing by the whole... 

Grob, K., Spinner C.H., Brunner, M. and Etter R. (1999). The migration from the internal coatings of food cans summary of the findings and call for more effective regulation of pol5miers in contact with foods a review. Food Add. Cont., 16, 579-590. 

Bisphenol A (BPA) (Figure 14.1a) is a starting substance utilized in the manufacture of most types of epoxy resins, which are then crosslinked and used to coat food cans. Another application of BPA is in the manufacture of plastic materials, in particular polycarbonates. BPA serves also as an antioxidant or stabilizing material for many types of plastics, e.g., polyvinyl chloride (PVC). 

Smoked and grilled foods are coated with nitrosamines, which can alkylate any of the bases of DNA but particularly guanine to cause cancers of the digestive tract and other organs. 

Cans for food can be made from steel coated with tin. The tin is deposited on to the steel used to make food cans by dipping the steel into molten tin. 

Although dietary lead intakes in the UK are currently well within recommended intakes, it is the UK Government s policy to ensure that exposure to lead is reduced wherever practicable and, more specifically, to reduce blood lead levels in children to below 10 pg/dl. Food is one of the major sources of lead exposure in the UK the others are air (mainly lead dust originating from petrol) and drinking water. Exposure from all of these sources has been reduced, as demonstrated by the reduction in blood levels over the past 15 years.10 The decrease in dietary exposure reflects the success of the measures taken to reduce lead exposure and contamination of food, such as the use of lead-free petrol, welded food cans, and the banning of tin-coated lead capsules for wine bottles. 

A tremendous range and variety of chemicals are used to make modem packaging materials. The European inventory list of chemicals used to make plastics intended for food contact numbered more than 1500 listed substances and inventory lists of a similar length exist for chemicals used to make paper, can coatings, inks and adhesives. The chemicals on the plastics inventory list mn literally from A (acetic acid) to X (xylene) with more than 1500 chemicals in between. Substances needed to make effective plastics packaging materials include ... 

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