There are many types of commercially available adhesive. Two of the most common are those that are solvent based and those that are water based. All things being equal, how do you make a decision between the two, when both are often reported to share the same performance characteristics? Here is a brief summary of the advantages and disadvantages of both types of adhesive, followed by our recommendations.
Solvent Based Adhesives
Solvent based adhesives are the most commonly used type of adhesive in some sectors, owing to their fast bonding and drying properties. Using a solvent based adhesive gives manufacturers’ peace of mind that the substance will remain firmly attached to the film during the manufacturing process. However, there are financial, environmental, and health & safety reasons why solvent based adhesives are not always the best choice, especially for food contact products. Here is a summary of the advantages and disadvantages:
- Bond strength
- Versatility – solvent based adhesives can be applied to a variety of situations.
- Temperature range – solvent based adhesives are not liable to freeze at low temperatures and can withstand high temperatures well (although are not food safe for use in ovens).
- Cost – solvent based adhesives are more expensive than water-based adhesives.
- Environmental damage – All stages of the manufacturing and application process for solvent-based adhesives, including formulation, drying and curing, release volatile organic compounds (VOCs) into the atmosphere. These atmospheric pollutants are linked to a number of serious health problems in people, as well as to the formation of ground-level ozone, which contributes to global warming.
- Health & Safety in the workplace: The regulation of solvents in manufacturing products has become tighter over recent years – a trend that is likely to continue. Limitations on solvents have been driven by two factors: environmental legislation coming from the government, and self-regulation from market factors, due to end users opting out of solvent-based products.
- Consumer Safety: The presence of solvents in an adhesive makes it unsuitable for use in food packaging or clothing products.
- Cleaning: Residues from solvent-adhesive spillages will not come off with water. You will need a special solvent-based cleaning solution to remove spills and dried on deposits.
Water Based Adhesives
At this point it is only fair to say that at Formulated Polymers we deal exclusively with water-based, or wet bond adhesives. We do not produce solvent-based products.
Here are the advantages and disadvantages...
- Application: Historically solvent based adhesives were the preferred choice of many businesses because of their perceived application advantages when compared with water-based products. However, this is not the case with modern wet bond adhesives, which are extremely quick and easy to apply. Water-based adhesives can be applied through rollers, spray guns or immersion, far more easily than a solvent-based product, without risk of rollers becoming clogged as the product dries.
- Cost: Solvents cost more to produce than water, meaning that a solvent based adhesive will always be more expensive than a water-based equivalent.
- Bond stability: Water-based adhesives have been shown to maintain a stable bond over time equal to or greater to solvent alternatives.
- Consistency: It is easier to maintain a uniform consistency with a wet bond adhesive, giving an even spread. Being water-based also means the adhesive is easier to remove from equipment, reducing the risk of blockages.
- Eco-friendly: Being low in VOC content, a water-based formulation is safer and more environmentally friendly. There are fewer environmental regulations to worry about, and less safety concerns about use in consumer products.
- Versatility: Wet bond adhesives can be successfully used on a range of substrates, including natural and synthetic textiles, plastics, metallic films, paper and cardboard.
- Low Odour: Water based adhesives have very little odour.
- Slower drying than solvent based adhesives
- Susceptible to freezing at low temperatures.
- Some water-based glues include dextrin, starch and casein, although ours do not. These and other ingredients are potential allergens, and should be avoided by food packaging manufacturers.
- Lower water resistance than solvent-based products.
Having worked extensively with both solvent and water-based products over the years, we are firmly of the opinion that water-based glues are the best option in almost all circumstances. This is why we only work with water-based products now – they really are no significant downsides to using wet bond adhesives.
To find out more about the benefits of using a wet bond adhesive, or to discuss our bespoke formulation service, please get in touch with one of our team today. Call us on 01706 828208, or send us a message through our online contact form.