Lamination Adhesives For Flexible Packaging

Lamination is a key process in the flexible packaging industry that involves bonding two or more layers of film together using adhesives. The choice of lamination adhesive is critical in determining the performance, durability and quality of the finished package. This article explores various types of lamination adhesives used in flexible packaging, their characteristics and applications.

Water-Based Lamination Adhesives For Flexible Packaging

Water-based adhesives have gained popularity in recent years as they offer environmental advantages over solvent-based alternatives. These adhesives utilize water as the carrier solvent instead of organic compounds. Being water-borne, they have very low or zero volatile organic compound (VOC) emissions during curing and use. Some common examples of water-based lamination adhesives include polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA) and acrylic emulsions.

Lamination Adhesives For Flexible Packaging  as PVA adhesives have good clarity and tensile strength but have limited tolerance to heat and moisture. They are suited for non-critical applications like grocery bags and pouches. EVA emulsions deliver improved heat resistance over PVA and work well for packaging fragile items like snacks and candies. Acrylic adhesives give high adhesion, clarity and resistance to heat, water and oils. They are favored for high-end applications such as blister packs. Overall, water-based options meet sustainability goals while ensuring adequate performance for basic packaging needs.

Solvent-Based Adhesives

Though having higher VOC footprints, solvent-based adhesives still find applications where performance demands are stringent. Rubber-based adhesives like styrene-isoprene-styrene (SIS) and styrene-ethylene/butylene-styrene (SEBS) offer high tack, flexibility and heat resistance up to 250°F. They can withstand retort sterilization processes. SIS adhesives work best for high-barrier applications such as meat trays and pouches.

Another excellent solvent-based category is polyurethane (PU) adhesives. Two-component PU systems deliver high bond strength even at elevated temperatures up to 300°F, making them suitable for heat-sealed packaging of hot-filled products. One-component PU hot-melt variants have good transparency along with adhesion and flexibility retention at higher temperatures. They serve applications like confectionery wrappers and pharmaceutical foils.

While posing greater environmental impact than water-based options, solvent-based adhesives offer performance advantages for demanding packaging applications involving heat, chemicals and extended shelf life. Efforts are underway to improve the sustainability of such adhesives.

Hot-Melt Adhesives

Hot-melt adhesives have gained prominence in flexible packaging due to their efficiency and clean production profile compared to solvent coatings. Being solvent-free, they eliminate drying steps and can be rapidly applied at line speeds. Hot-melts generally have EVA, SBC or polyolefin compositions and are supplied in pellet or stick form to be applied molten on the substrate.

EVA hot-melts deliver good adhesion, clarity and flexibility up to 200°F. They are used extensively in food and consumer packaging like bread bags, frozen food pouches and carton closing. SBC hot-melts possess high tack and shear strength for demanding applications like carton sealing at elevated temperatures up to 300°F. Polyolefin hot-melts like polyethylene and polypropylene provide water resistance for heavy-duty packaging.

Overall, hot-melt adhesives are very popular for flexible packaging due to their clean processing, high speed application capability and solvent-free construction. Recent innovations focus on expanding their heat resistance and sustainability.

Specialty Adhesives

For certain specialized needs, flexible packaging utilizes unique adhesive types:

- Repositionable adhesives like pressure-sensitive acrylics allow re-sealing of packaging and easy label application/removal e.g. on tapes and sticker labels.

- Microwave-safe adhesives containing polysterene resin withstand high temperatures up to 400°F during microwave heating without delaminating or emitting harmful fumes from package. They stick together sandwich packaging for microwavable meals.

- Oil and chemical-resistant adhesives made from thermoplastic polyurethanes offer robust bonding ability in presence of lipids, oils and solvents. Used in oil-containing food bags and solvent-absorption pouches.

- Antimicrobial adhesives incorporated with silver nanoparticles prevent microbial growth on package surface and increase shelf life of perishables like fresh produce, seafood and meat.

Such specialty lamination adhesives cater to very unique performance or functional needs for innovative packaging applications. Ongoing research further enhances their capabilities.

Sustainability Focus

With increasing sustainability awareness, the flexible packaging industry is working to develop eco-friendly adhesive solutions. Major thrust areas include:

- Designing 100% bio-based adhesives from renewable plant-derived sources like soy and corn instead of petroleum feedstocks.

- Engineering compostable adhesives that can fully degrade along with package into carbon dioxide, water and biomass in controlled composting facilities.

- Advancing recyclability by creating adhesive chemistries compatible with most waste management systems and not interfering with recycling of paper, plastic or aluminum substrates.

- Reducing VOCs, improving solvent recovery and eliminating use of hazardous chemicals in formulation to lower environmental footprint.

- Enhancing performance of existing adhesive types like water-based, hot-melt at higher processing speeds and temperatures to replace solvent-based systems.

 sustainable packaging requires holistic consideration including whole life-cycle impacts from raw materials to disposal. As adhesive technologies evolve rapidly, the future looks promising for wider adoption of eco-friendly lamination solutions.

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About Author:

Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. (https://www.linkedin.com/in/money-singh-590844163)