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.
Types of water based adhesives and sealants
Water based sealants are more scarce than 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 sealants.
The trend in adhesives for its part is strongly water based. In Europe and America these 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 to two groups: emulsion and dispersion adhesives and solution adhesives.
Waterborne emulsion 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 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 adhesive 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 adhesives for fabric and wood, polyacrylate emulsions as construction adhesives, laminating adhesives, and pressure sensitive adhesives, and polyurethane dispersions and emulsions for packaging and shoe making industries.
Water based 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 systems are created using natural and synthetic polymers which dissolve in water. The uses of water based solution adhesives 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.
Water based 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 water based adhesives
Wet bonding 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 adhesive is applied wither 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 poros, absorbing the water, and allowing it to leave the system faster. If none the adherents is poros, curing and hardening may take a long time. Wet bonding water based adhesive systems are used mainly in the paper, packaging and furniture as well as mattress industries.
2. Waterborne contact adhesives
Contact adhesives, also known as dry bonding 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 adhesive 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 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. In case you are curious for water based alternatives for your production, contact us and let our experts guide you through the durable possibilities.