Laminated plastic pouches have proliferated in grocery store aisles thanks to their durability and light weight. The pouches are made of multiple polymer layers engineered to protect foods against the incursion of light, gases, and microbes.
But one component of the adhesives used to stick those layers together—[3-(2,3-epoxypropoxy)propyl]trimethoxysilane, an epoxy silane commonly called glymo—should no longer be used because of its potential to alter genes or gene expression, according to FEICA, the European adhesive association.
For several years, European Union plastic regulations have limited glymo’s use in food applications. In July, FEICA recommended adhesive firms replace it altogether by the end of 2020 due to the possible genotoxicity.
In its notice, the trade group asked members not to circulate the advice widely to avoid alarming consumers. Already, however, two leading adhesive manufacturers are highlighting that they offer laminating adhesives that do not contain glymo or similar epoxy silanes.
Bostik, the adhesive business of Arkema, is touting its line of glymo-free polyurethane adhesives for food contact packaging. It says the products also omit bisphenol A, epoxy resins, phthalate plasticizers, o-phthalic acid, and tin compounds, all considered substances of concern for food packaging. Bostik says the adhesives include one- and two-component products, those with and without solvents, and aromatic as well as aliphatic systems.
Meanwhile, Germany’s Henkel has introduced a modular line of glymo-free adhesive components that can be mixed and matched to meet high-performance packaging needs. For example, some foods are sterilized inside the package using high heat, while other foods are added to pouches while very hot. Some foods may be microwaved by the consumer. Pouches made with the new adhesives work well for a range of pet food, medical supply, and convenience food applications, Henkel says.
Helga Garmann, Henkel’s manager of polyurethane product development, points out that glymo may still be used under EU regulations, but food packaging producers must test and verify that migration falls below specific limits. “As testing is complex, we recommend the use of adhesives that do not contain any glymo,” she says in a statement.