Dry Lamination Process

This article focuses on the dry laminating process known as dry bond laminating. In this process, a liquid adhesive, normally using ethyl acetate as a solvent, is applied on the substrate to be laminated by means of a gravure cylinder. The gravure cylinder has a doctor blade attached to it to ensure that a uniform amount of adhesive is applied on the substrate.

Once the adhesive is applied on the substrate, it is passed through three ovens each of varying temperature and all consisting of fans. The heat and airflow in the oven evaporates the solvent while the remaining solid compounds of the adhesive is left on the substrate.

The substrate is then joined with the second substrate with the help of a heated compression nip roller. The high temperature and pressure causes the adhesive to flow freely and create an instantaneous bond between the two substrates once it cools.

The Dry Lamination Process

The stress applied by the laminator throughout the whole process needs to be under the right amount of tension (hence the use of many idler rolls) in order to prevent the films from tearing or creasing (or tunnelling) after the completion of the lamination process.

The correct adhesive will have to be selected as well, in order for effective lamination, an adhesive with a surface tension lower than the critical surface tension of the substrate that is to be coated by it. Some preparation processes such as corona treatment or plasma treatment increase the surface tension of substrates, this allows for more efficient lamination.

However, the bonding ability of the adhesive isn't the only factor that needs to be taken into account. If the adhesive could increase the performance of the final product such as improving its barrier properties, that may go a long way.