What to Specify When Sourcing a Laminating Adhesive

Most adhesive enquiries are too short. "Two-component PU adhesive for PET//PE, please quote" cannot be answered properly, because several different grades fit that description and only one of them will survive the application.

1. The structure, layer by layer

PET//PE is not enough. State the thickness of each web, whether the PET is treated or metallised, and which side is printed. A 12 µm PET behaves differently from a 23 µm one on the same laminator.

2. The fill

Retort at 121 °C, pasteurisation at 85 °C, hot fill, or ambient. This single answer changes the grade more than any other. A standard laminating adhesive in a retort pouch will fail, and it will fail after the pouches are filled.

3. Coat weight and line speed

The adhesive has to wet out at the speed the line runs. If the supplier does not know the target coat weight, the working viscosity cannot be matched and the first trial is wasted.

4. The food-contact requirement

Which regulation does the finished pack have to satisfy, and does the buyer require a specific migration statement? Ask for it in writing at quotation stage, not after the order.

5. Documentation

Technical data sheet, mix ratio, pot life, cure schedule, batch number and certificate of analysis. If a supplier cannot issue these, the material is being sold without a specification and every future batch is a gamble.

6. What happens when something goes wrong

Ask what support is available if a trial delaminates. A supplier who can explain the failure mode — ratio, wet-out, cure, substrate treatment — is worth more than a lower price per kilogram.

An enquiry that gets a useful answer

Structure: PET 12 µm // PE 60 µm, PET printed, PE treated
Fill: ambient dry food
Coat weight: 2.5 g/m² dry
Line speed: 150 m/min
Food contact: EU 10/2011, migration statement required
Volume: trial 200 kg, then quarterly

With that, a grade can be selected, a data sheet issued and a sample sized for the trial.