Everyone wants to live in a sustainable world. This includes being environmentally responsible in our work every day.
In the flexible packaging industry, most of the sustainability efforts tend to focus on materials. Designers and researchers are always searching for materials that come from renewable sources, are reusable in some way, can be easily recycled, or are compostable and/or biodegradable. A great deal of effort is also concentrated on reducing the overall amount of packaging by down gauging as well as eliminating layers and environmentally unfavorable materials.
While these efforts are all beneficial, an often overlooked opportunity for sustainability in flexible packaging is the manufacturing process itself. To manufacture flexible packaging in the most sustainable manner possible, one can utilize solvent-free adhesive lamination technology, also known as solventless lamination. The laminating adhesive used in this process is a two-component polyurethane. These two components must be mixed together in the appropriate way to form a useful adhesive that will bond the material layers to each other, forming a flexible packaging substrate. The manufacturers of these adhesive components control the viscosity properties of the final product in such a way that solvents are not required to maintain the material as a liquid; hence, solvent-free.
How It Works
Solventless lamination technology utilizes a computer controlled Meter, Mix, Dispense Unit (MMDU) that continuously measures a precise amount of each component, then mixes and dispenses small amounts of the solvent-free adhesive into the laminating equipment. This differs from the traditional lamination method in which large batches, up to 55 gallons at a time, of adhesives are premixed for the manufacturing process; this can lead to excess waste.
The MMDU dispenses the adhesive into a laminating machine specifically designed to run this type of adhesive. The laminator applies the adhesive and combines the two layers of materials to form the flexible packaging lamination. Since there’s no solvent to drive out of the adhesive, no overhead ovens are required for drying the adhesive. The two materials are combined, wound into a roll, and the adhesive is allowed to crosslink (or cure) for a specified amount of time before moving to the next manufacturing stage.
This lamination technology is far more sustainable than the traditional adhesive lamination methods for three very important reasons:
- Reduced Waste. Only the amount of adhesive needed at the time of lamination is mixed and dispensed. Since the adhesive is mixed continuously, there’s no excess and very little waste. When the lamination equipment is stopped, the adhesive mixing also stops thus, drastically reducing adhesive waste.
- Energy Savings. Since there’s no solvent that needs to be driven out of the adhesive there’s no need for an overhead drying oven. The result is a significant energy savings in natural gas. Additional energy savings include reduced electricity usage since there’s no need for large blower motors to circulate the hot air inside drying ovens. There are further natural gas savings because the solvent-laden air doesn’t need be passed through a secondary thermal oxidation process to destroy the solvents before the air is released to the atmosphere.
- Lower Material Usage. Solvent-free adhesives tend to use lower coating weights when compared to other adhesive lamination techniques, again resulting in fewer pounds of materials used for the same amount of packaging.
The solvent-free adhesive lamination technology is a highly sustainable manufacturing method due the benefits of drastically reduced waste, lower material usage, and large energy savings. The large reductions in energy usage can be related directly to significant reductions in the release of carbon compounds to the atmosphere.
This is an example of just one of the many technologies that are available in the manufacturing process to improve sustainability, while still producing useful and safe flexible packaging structures. To learn more, contact your local AWT Representative at http://www.awtlabelpack.com/contact/