Flexible packaging adhesive is a key bonding agent used for laminating flexible materials such as plastic films and aluminum foil, and is widely applied in packaging production in industries such as food, medicine, and daily chemicals. Its performance directly affects the sealing, weather resistance and safety of the packaging, and it needs to meet special requirements such as being odorless, non-toxic, heat-resistant and resistant to media.
1. Main types
According to the chemical system, it can be classified into types such as polyurethane, acrylate, and epoxy resin. Among them,
Polyurethane Glue accounts for the highest proportion. Due to its strong adhesive force and good flexibility, it is suitable for multi-layer composites (such as BOPP/PE, PET/AL and other structures). Acrylate glue has excellent weather resistance and is widely used for outdoor packaging. Epoxy resin glue stands out in high-barrier packaging. According to the curing method, they can be further classified into solvent-based, solvent-free and water-based adhesives. Under the trend of environmental protection, the latter two have become the focus of research and development.
2. Core performance requirements
Hygiene and safety: It must comply with food contact material standards such as FDA and EU 10/2011 to avoid solvent residue or migration.
Adaptability: It can form a uniform film under high-speed coating (200-400m/min) and has good wettability with the substrate.
Durability: Resistant to erosion by contents (acids, oils, alcohol), and does not delaminate after high-temperature steaming (above 121℃) or freezing (-18℃).
Environmental friendliness: The VOC content of solvent-free adhesives should be less than 1%, while water-based adhesives require low-energy consumption drying.
3. Technical difficulties
The bonding of high-barrier materials (such as EVOH) needs to address the issue of polarity differences.
Recyclable packaging requires the development of peelable adhesives to facilitate material sorting.
The cost and performance balance of bio-based adhesives (such as polylactic acid modified ones).
4. Development Trends
With the advancement of the circular economy, degradable adhesives (such as starch-modified ones) and UV-curable adhesives have become research hotspots. Meanwhile, intelligent production lines have put forward higher requirements for the rapid curing (< 3 seconds) of adhesives. In the future, adhesives will pay more attention to the combination of environmental friendliness throughout their life cycle and multi-functionality (such as antibacterial and anti-counterfeiting).
The technological progress of flexible packaging adhesives continuously promotes the lightweighting and sustainable development of packaging, which is an important subfield of materials science.
