Water based adhesives and sealants for sustainability
The market share of water based adhesives and sealants is becoming ever greater since the development has taken a shift towards more and more sustainable solutions which support health and safety as well as reduce environmental impact. Water based adhesives and sealants are a great alternative for solvent based systems, as they do not contain any Volatile Organic Compounds (VOC), are lighter in weight and often require less product for forming durable bonds and seals.
Being environmentally friendly and low VOC, water based adhesive and sealant systems are also user freinlier compared to alternative solutions. Applying waterborne adhesives and sealants does not require as many safety measures as systems that contain solvents, which can impropve efficiency depending on the nature of the project. Additonally, the finished products that are bonded or sealed using water based glue or sealant are user friendly: waterborne adhesive or sealant does not bring along great health risk, nor does it release toxic or odorous fumes.
Types of water based adhesive and sealant systems
Water based sealants are more scarce than waterborne adhesives due to the differences in formulations. Several waterborne sealants exist for interior applications, although the sustainability of sealants is usually enhanced by increasing the solid share, which decreases the amount of solvent in the product. These systems are regarded as solvent free.
The trend in adhesives for its part is strongly water based. In Europe and America water-based adhesives are preferred systems, whereas in markets such as China they only cover about 20% of the market. Water based adhesive systems can be roughly divided into two groups: emulsion and dispersion adhesives and solution adhesives.
Type 1 waterborne adhesives: emulsions and dispersion adhesives
The water based emulsions and dispersion systems are heterogenous mixtures which consist of dispersed liquid or solid polymer phase in an aqueous phase. These waterborne adhesives can be made by using a wide range of polymers including PVA (vinyl acetate polymers), PVAC (vinyl acetate copolymers) and acrylic as well as synthetic elastomers such as PUR (polyurethane).
As with other water based adhesive systems, also dispersion adhesives and emulsions can be cleaned with water. However, after the water-based adhesive glue has dried, it is no longer water dispersible and cleaning residue may require use of solvents and detergents. More information on waterborne adhesives is available by contacting us.
Application methods: spray, brush, roller or beads.
Bonding: wet bonding or dry bonding (contact adhesive)
Examples: vinyl acetate adhesives for bonding paper, wood and cardboard, rubber latex waterborne adhesives for fabric and wood, polyacrylate emulsions as construction adhesives, laminating adhesives, pressure sensitive water-based adhesives, and water based polyurethane adhesive as dispersions and emulsions for packaging and shoe making industries.
Type 2 water based glue: solution adhesives
Solution adhesives are the most traditional form of water based adhesive systems. They use water as the carrier substance and cure as the water evaporates. These waterborne adhesive systems are created using natural and synthetic polymers which dissolve in water. The uses of these water based glue systems include paper bonding and moistable glues such as those found in envelopes, stamps and labels.
Application methods: roller, spray and beads
Bonding: wet bonding
Examples: starch/dextrin adhesives for paper applications such as bookbinding, and protein/casein adhesives for food packaging industry.
Waterborne adhesive bonding in 2 ways
Another way to categorize water based adhesives is by the manner in which they form bonds. The two groups are wet bonding and dry bonding (contact adhesives).
1. Wet bonding waterborne adhesives
Wet bonding waterborne adhesives are those that cure through water evaporation, and include both dispersion and emulsion adhesives, and water based solution adhesives which are predominantly wet bonding. In this bonding process the waterborne adhesive is applied either to one adherent or both of them. The adherents meet each other while the adhesive is not dry, hence the name wet bonding. As curing takes place as a result of evaporation, it is extremely important that at least one of the adherents is porous, absorbing the water, and allowing it to leave the water-borne adhesive system faster. If none the adherents is porous, curing and hardening may take a long time. Wet bonding water based adhesive systems are used mainly in the paper and packaging laminating processes as well as furniture and mattress industries.
2. Waterborne contact adhesives
Contact adhesives, also known as dry bonding waterborne adhesives, are predominantly emulsions and dispersion adhesives. Similar to solvent based dispersions, the water based adhesives are applied to both adherents, hence the substrates that require bonding, and the water is allowed to evaporate before the bond between the adherents is formed. When the parts coated with the water based glue come into contact with each other, the bonding takes place.
Waterborne contact adhesives are used more widely than the wet bonding systems since they are generally stronger, allow for greater variety of substrates and have better heat resistance. In these waterborne adhesive mixtures, ingredients can be added to enhance and create properties including fire resistance, chemical resistance and anti static properties.
Tailored advice – best waterborne adhesives and sealants
Moving towards more sustainable products is a trend that has reached the adhesives and sealants market. Water based adhesives and sealants not only are environmentally friendly but also contribute to the safety of finished products and possible improve process efficiency. In case you are curious for water-based adhesives for your production, contact us and let our experts guide you through the sustainable, greener possibilities.