Flexible packaging plays a vital role in the food, consumer goods, healthcare and industrial industries by keeping products fresh and extending shelf life. Lamination adhesives form a strong bond between different substrate layers such as plastic films, aluminum foils and papers to produce flexible packaging laminates. They provide strength, heat resistance and protection from external elements while allowing the packaging to be easily printed, converted and sealed.

Types of Lamination Adhesives For Flexible Packaging

Water-Based Adhesives

Water-based adhesives are the most widely used type for flexible packaging lamination due to their low VOC emissions and solubility in water which allows for fast and easy cleanup. They form strong bonds between a variety of substrates like paper, plastic and foil layers. However, water-based adhesives have relatively low heat resistance and are susceptible to breakdown in humid conditions.

Solvent-Based Adhesives

Solvent adhesives have superior heat resistance compared to water-based ones, making them suitable for applications that require heat sealing or sterilization processing. They can withstand the high temperatures involved in packaging fabrication processes like oven baking without delaminating. However, solvent adhesives release more VOCs and hazardous air pollutants during manufacture and curing. Many countries have strict regulations around their use.

Hot Melt Adhesives

Hot melt adhesives are 100% solid without any solvents, making them environment-friendly and safe for food contact. Flexible packaging are applied in a molten state directly from a melt tank onto the substrate and bond instantly upon cooling and solidification. Hot melt adhesives cure faster than other types but have relatively low heat resistance. They are suitable for producings like bags, pouches and wrappers.

Key Properties of Lamination Adhesives

The primary requirement of a lamination adhesive is to form a strong bond between substrate layers that does not fail even when the package is stressed, stretched, bent or exposed to external elements. Proper adhesion allows the laminate to maintain its physical integrity throughout processing, filling, distribution and usage.

Coatability

Lamination adhesives must flow out smoothly and evenly during application onto substrates to avoid defects, thin spots or voids in bonding. Good coatability ensures uniform adhesive coverage for consistent performance across the packaging laminate.

Heat Resistance

Flexible packaging often undergoes high temperature processes like sealing, sterilization or retorting that require the adhesive bond to remain intact. Adhesives with superior heat resistance prevent delamination from occurring at elevated temperatures.

Moisture Resistance

Packaged products are frequently exposed to humidity during storage and distribution. Lamination adhesives need to have strong resistance to moisture absorption to prevent the bonded layers from separating in wet conditions.

Applications in Flexible Packaging Production

Pouches

Stand-up pouches, flat bottom pouches and other single-use pouches commonly found in snacks, coffee, pet food etc are produced using lamination adhesives. They securely bond layers of plastic films, foil and paper used to construct the pouch structure.

Bags

Grocery bags, shopping bags, food storage bags — lamination adhesives play a key role in manufacturing blown and cast film bags by joining multiple substrate webs into a strong laminated film.

Wrappers

Crisp packets, candy wrappers, condiment pouches — these flexible packaging formats often involve laminating a printed film to an aluminum or paper layer using specialized adhesives.

Lidding Films

Lamination adhesives are applied to bond lidding stock like plastic or laminated films onto trays, tubs or other rigid containers to produce sealed food packages.

Labels

Self-adhesive labels used in variable data printing are fabricated by bonding a top plastic or paper layer to a pressure-sensitive adhesive backing using lamination techniques.

Quality Assurance Testing for Lamination Adhesives

Adhesion Testing

Peel strength, shear strength and tensile strength tests accurately measure the bonding capability of laminating adhesives on real packaging substrates under different conditions.

Heat Resistance Testing

Tests like dry heat aging, wet heat aging and seal strength measurement after autoclave exposure verify adhesive performance at high temperatures.

Chemical Resistance

Swell tests and lamination evaluations after solvent or acid/base exposure confirm the adhesive’s stability against cleaning chemicals.

Moisture Resistance

Conditioning laminates in humidity chambers followed by adhesion quantification determines the ability to withstand wet storage and distribution.

With rising demand for single-serve and on-the-go packaged foods, the flexible packaging industry continues to grow globally. Adhesive technologies play a vital role by enabling the fabrication of innovative package formats through effective lamination. Ongoing R&D is expanding the efficiency, sustainability and performance capabilities of lamination adhesives to support market demand. Proper adhesive selection and QA ensures flexible packages can protect product quality while meeting regulatory requirements.

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