Growing awareness about the environmental impacts of using petrochemical solvents and Volatile Organic Compounds (VOC) in adhesives, combined with new legislative requirements, is continuing to drive the development of ‘green’ adhesives.
While sustainable adhesives is not a new concept, Diane Montgomery, Marketing Manager at Henkel Australia, says increased customer demand for environmental solutions and OHS is seeing a number of improvements and innovation in various adhesive technologies.
“People are now more aware about the impact that products have on the environment,” Montgomery told Manufacturers’ Monthly.
“A key driver for the development of low VOC or solvent-free adhesives in the flexible packaging industry is the growing number of legislative requirements.
“For example there are guidelines to ensure that all food packaging material must fulfil a basic requirement that under the conditions of use, residual amine levels must drop below the approved threshold limits specified for use in food packaging,” she said.
According to Montgomery, low VOC or water-based solutions can be just as good as traditional solvent based adhesives and in some instances are superior in application, cost and performance.
“Another reason for choosing solvent-free adhesives by converters in the food sector is the increased lamination production efficiency and decreased curing times for polyurethane adhesives.
“We have been looking into ways to develop both environmentally friendly and cost effective polyurethane adhesives to help drive greater economic benefits and environmental sustainability,” Montgomery said.
For food and packaging case and carton sealing applications, Henkel has released the Coolmelt product range which Montgomery says utilises innovative raw materials to combine low viscosity with high strength.
“This unique combination allows the use of low application temperatures without any compromise in properties like adhesion, bond strength, and temperature resistance.
“Because these adhesives are lower viscosity by the nature of their design, they don’t require heating to high temperatures to reach operating viscosity. These products are typically applied at just 130°C, 30 – 50°C lower than their conventional counterparts,” she explained.
“This saves energy in two ways: one, because when we manufacture them we don’t use so much energy to produce them, plus at the customer level, the energy required to melt and maintain the adhesives at operating temperature is significantly lower than the energy expended to do the same job with conventional hot melts. This, along with its reduced volatile emissions into the atmosphere, makes it an environmentally attractive option too,” she said.
Because these adhesives melt at a lower temperature, there have been some concerns about their heat resistance but as Montgomery points out, the adhesive has been designed specifically for food and packaging applications.
“You wouldn’t use these products in automotive environments for example. Substrates are so different and people’s processes vary to such a large degree, so I advise that manufacturers evaluate the adhesives in their own factories, on their on substrates, to better ensure they get the required results.
“Also it goes without saying, before implementing any new technology into your manufacturing processes it’s important to seek professional advice.”
Montgomery also recommends customers buy their adhesives in bulk, using returnable containers.
“With automatic unloading equipment available as part of our adhesive package, it’s now easier for customers to reduce their environmental impact while boosting production efficiencies,” she said.
Green building
Another industry undergoing a green revolution and embracing sustainable adhesives is the building and construction sector.
With the introduction of the ‘green building’ requirements of the Green Star environmental rating system, set out by the Green Building Council of Australia, companies are now actively looking for products and services that have less impact on the environment.
Green Star certified projects (including shopping centres, public buildings and industrial facilities) are said to show an average reduction in energy use up to 85%.
Gavin Williams from 3M Australia, says there are many additional benefits for builders and manufacturers who decide to ‘go green’ and purchase low VOC/high solids and Hazardous Air Pollutants (HAPs) free adhesives.
“Incorporating Green adhesives into your manufacturing processes can help you and your customers pursue LEED® (Leadership in Energy and Environmental Design) rated projects, as well as meet legislative requirements,” Williams explained.
As well as a better image in the community, Williams says choosing green adhesives (water-based adhesives) also offers safety and productivity benefits.
“By switching to water-based adhesives, benefits include fewer controlled substances to manage, fewer transportation restrictions associated with using water-based adhesives and improved worker safety,” Williams said.
Recent technological developments for green adhesives for building applications has mainly been in contact adhesives, which are predominantly used in laminating and bonding materials for the use in furniture construction or bonding insulation to walls etc.
Traditionally contact adhesives contain solvents and are high in VOCs.
“However,” Williams says, “we have developed a range of adhesives which are Greenguard Indoor Air Quality Certified, which are high solid, low VOC adhesives that still offer the same bonding advantages as conventional adhesives with all the benefits of a safer, more environmentally friendly formulation,” he explained.
Low VOC , more environmentally friendly adhesives can also give users a competitive/marketing advantage, but as Williams points out, “only if their customers demand use of more environmentally friendly materials, then there will be an advantage over traditional high VOC solvent based contact adhesive users.”
“Adhesives are just one component in a larger process for many manufacturers. While it is just one step towards being green, if manufacturers need to produce goods which need to meet certain standards, then using sustainable adhesives will make a significant contribution to achieving green goals,” he said.