Core–Shell Polymer Adhesive for Aluminized Coatings: From Improved Barrier Properties to Commercial Formulation

Abstract

The development and formulation of core–shell latex‐based adhesives to improve the adhesion of aluminium to poly(ethylene terephthalate) (PET) films and enhance the permeability of the final laminate to oxygen and water is described. All particles have a soft acrylic component (the shell in core–shell particles) to improve adhesion, and occasionally a hydrophobic core to enhance the permeability. The performance of the different latexes is compared to that of a commercially available reference material. The coatings formed by core–shell nanoparticles present a lower permeability to water than the particles synthesized in the absence of the seed, while the permeability to oxygen is found to be mainly related to the correct deposition of the metallic layer. In terms of the industrial formulation, it is found that a limited amount of a wetting agent (WA) is needed to ensure the correct spreading of the latex onto the PET substrate because of the low levels of surfactant used for the latex production. This compound has a positive effect on the adhesive strength of the coating. A curing agent also improves barrier properties, but the optimal level of this compound is dependent on the degree of crosslinker used in the base latex.

The Effect of Different Soft Core/Hard Shell Ratios on the Coating Performance of Acrylic Copolymer Latexes

“…The composite polymeric latexes with two or more distinct phases may have various compositions that lead to different properties, such as high and low glass transition temperatures, hydrophobicity, reactivity, etc., which affect the properties of the final polymer. Several studies were reported on the preparation of composite latexes for various purposes [22][23][24][25][26][27][28][29][30][31][32][33][34]. Among these studies Limousin et al [22] synthesized hybrid latex particles containing a hard, high T g seed (styrene(S)/acrylamide (AM), T g = 101 degrees C) and a low T g (methyl methacrylate (MMA)/butyl acrylate (BA)/styrene(S), T g = 13 degrees C) second phase polymer.…”

“…They showed that the morphology of hybrid latex particles influenced the mechanical strength of polymer films. Lara et al [26] also prepared core-shell latexbased adhesives to improve the adhesion of aluminum to poly (ethylene terephthalate) (PET) films and enhance the permeability of the final laminate to oxygen and water by using a soft acrylic component (the shell in core-shell particles) to improve adhesion, and occasionally a hydrophobic core to enhance the permeability. Zhang et al [29] prepared PVAc-based inverted core/shell (ICS) structured latex adhesive with improved water-and heat-resistance by a copolymerizing-grafting sequential reaction approach for wood bonding.…”