Switzerland-based OEM Bobst has released its AluBond process for high metal adhesion through vacuum metallization. Traditional metallization, said the company, even with plasma treatment, can result in poor metal-to-polymer substrate bonding. This produces de-lamination that can lead to packaging failure and results in product rejects and loss of brand reputation. Part of the problem is low surface energy on the metal side that also contributes to poor lamination bonding. There’s increasing demand in the industry, said Bobst, for higher levels of metal adhesion on metallized film due to the need for more complex packaging structures that require a lamination peel strength suitable for maximum functional.
Bobst has now developed a new approach to address this common issue in the packaging industry through its vacuum metallizers, eliminating the need for chemically treated films. High bonding strength is achieved on any substrate with the Bobst AluBond unique metallizing process. This is an advanced metal adhesion technology where metal adhesion valuesof up to 5N/15mm can be achieved. The process is an inline hybrid coating technology that promotes chemical anchoring (chelation) of the first aluminum particles, creating a ‘metallizing seeding layer’ that provides superior bond strength properties. Very high adhesion is achieved when there are direct chemical bonds between the aluminum coating and the polymer surface. Increased chemical bonding by the creation of the seeding layer increases lamination bond strength and leads to high performance during lamination, extrusion and coating processes – hence preventing failure of the packaging.
The process been shown to greatly increase metal bond strength and metal adhesion on the most commonly used substrates (PET, BOPP, CPP and PE) during aluminum vacuum metallization. In addition, Bobst AluBond has also been shown to significantly increase dyne level retention which translates in improved ink wettability during printing, and enhances structure stability during lamination. It also generates added value by extending surface energy stability on metallized films over a long period of time, and may eliminate the need for an additional surface-treatment boost – i.e. corona refresh prior to converting.