Laminating adhesives regulation

FDA regulations only allow the use of aliphatic isocyanates in laminating adhesives for high-temperature applications. (Cured aromatic systems can decompose to regenerate isocyanate and thus form aromatic amines at retortable or boiling water temperatures.) Discussions with a number of UK packaging producers revealed that they are aware of the need to use adhesive systems... 

A second generation of phenolic dispersions, patented by J. S. Fry (33). involved the post dispersion of phenolic resins in a mixture of water and water-miscible solvents. To conform with air pollution regulations, the solvent was held to 20 volume %, or less, of the volatiles. A heat-reactive phenolic resin dispersion (34) and a phenolic-epoxy codispersion have become commercially available based on the above technology. Supplied at 40-45% solids, these products, which have a small particle size (0.75-1.0 ym), are better film formers than the earlier dispersions. Used alone or in blends with other waterborne materials, corrosion-resistant baking coatings may be formulated for coil coating primers, dip primers, spray primer-surfacers, and chemically resistant one-coat systems. Products of this type are also tackifiers for acrylic latexes, and such systems have been employed as contact, heat seal, and laminating adhesives for diverse substrates. 

While converters endeavour to reduce their manufacturing costs, there is increased awareness of food regulations, which are becoming increasingly demanding, while analytical methods improve. The use of radiation-curable laminating adhesives can help converters meet these market requirements. 

Common laminating adhesives include solvent containing and solvent free, crosslinking polyurethanes, and two-componenf water-based polyurethanes - the latter have been increasing in importance in recent years because of environmental pressures. The choice of adhesive depends on the type of film to be bonded and on the end use application. In food packaging, for example, food regulations and the resistance of the adhesive (e.g. to boiling water) are also important. 

Current usage is almost entirely associated with the good adhesion to aluminium. Specific applications include the bonding of aluminium foil to plastics films, as the adhesive layer between aluminium foil and polyethylene in multilayer extrusion-laminated non-lead toothpaste tubes and in coated aluminium foil pouches. Grades have more recently become available for manufacture by blown film processes designed for use in skin packaging applications. Such materials are said to comply with FDA regulations. 

The chemicals used for coating and laminating are polymeric materials, either naturally occurring or produced synthetically. These include natural and synthetic rubbers, polyvinyl chloride, polyvinyl alcohol, acrylic, phenohc resins, polyurethanes, silicones, fluorochemicals, epoxy resins and polyesters." Coating formulations typically include auxiliaries such as plasticizers, adhesion promoters, viscosity regulators, pigments, fillers, flame retardants, catalysts and the like. ... 

Films of EAA are also used in flexible packaging of meat, cheese, snack foods, and medical products in skin packaging and in adhesive lamination. Extrusion coating applications include condiment and food packages, coated paperboard, aseptic cartons, composite cans, and toothpaste tubes. FDA regulations permit use of up to 25% acrylic acid for copolymers of ethylene in direct food contact. 

Example 2 Identification of Relevant Regulations for Fabrication of an Adhesive-Laminated Plastic Bag... 

The product can be used in adhesives to form flat or shaped laminated parts. The nature of the resin imparts the necessary performance to withstand bond stresses in the laminate along bends in the formed components. In addition, it exhibits good water and fatigue resistance properties. The product meets the standards of major flat-pack supplier regulations regarding formaldehyde-free and wood furniture construction performance. 

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