Lesser the Solvents, More the Benefits!

Depending on the solvents, adhesives are classified in one of the following ways:

• Water-based adhesives: water-based adhesives use water as a carrier for the adhesive. They are usually non-hazardous and environmentally friendly, containing no VOCs. These adhesives also have high solids, deliver a consistent bond, are non-flammable, and dry slower than solvent-based adhesives

• Solvent-based adhesives: Solvent-based adhesives use solvents as a carrier for the adhesive. They are used for long-term applications and are ideal in industries where speed of application and production is required. Solvent-based adhesives are more chemical-resistant than water-based ones, can withstand a wide range of temperatures, and provide strong bond strength.

What are solvents?

Solvents are the thinners used in the adhesive industry to provide the beneficial properties necessary to make adhesives function efficiently, especially when it comes to maintaining the coatability. Across the globe, the chemical industry, especially the coating industry, spends an excessive amount on solvents. Appropriate solvents are required to get an even and consistent coating in paint or adhesives.

What are the types of solvents used in the adhesive industry?

Toluene

Toluene, an aromatic hydrocarbon that is composed of a benzene ring linked to a methyl group, is an exceptionally good solvent. Unlike water, toluene can dissolve several organic compounds, and due to its low toxicity levels, it is used as an alternative solvent to benzene

Isopropyl alcohol

An alcohol, such as isopropyl alcohol, is the preferred choice of solvent for plastic substrates. Isopropyl alcohol dissolves a wide range of non-polar compounds, evaporates quickly, leaves little oil traces as compared to ethanol, and is relatively non-toxic when compared to alternative solvents.

Methyl Ethyl Ketone

Methyl ethyl ketone also known as butanone, is an organic solvent that is a great degreaser for heavy manufacturing oils and lubricants and can also be used to clean up certain adhesives, lacquer and latex paints. It has a fast evaporation rate, although not as fast as acetone.

Xylene

Xylene is a colourless mixture of chemically related hydrocarbons, that is often used as a solvent for paints, adhesive, and printing inks. It is extremely efficient at dissolving compounds that dissolve poorly in water.

Ethanol

Ethanol mixes easily with water and many organic compounds, and is an effective solvent for use in paints and coatings.  

Due to the numerous advantageous properties of solvents, many industries, especially the chemical industry, require a large quantity of solvents for their productions. This has a direct impact on the environment, in recent years there have been many studies and discussions about the adverse effect of solvents on the environment. The main outcome of these discussions has been that the usage of solvents needs to be reduced.

These findings motivated the R&D team at Adhesive Specialities to conduct a study on comparing adhesives containing different solvents ratio. They tested rubber adhesives with different percentages of toluene solvent and found the following results:

The results clearly indicate that by reducing the quantity of Toluene, they were able to improve the quality of the product as well as make it more economical.

Some of the other benefits found during the study are as follows:

1. The machine speed would increase by 25% because if the solvents are less, then they evaporate faster, and the adhesive drying time also reduces.
2. Shear strength or the holding time of the rubber adhesive increased by 2 hours, clearly indicating that by decreasing the amount of the solvent Toluene, the strength of the adhesive increased
3. By reducing the quantity of solvents in the adhesive, the amount of evaporation loss in the environment also reduces. This will reduce the adverse impact on the environment
4. The tape with the less solvent had almost no residual content thereby creating a better and shorter curing cycle.
5. By decreasing the toluene, the rubber was able to grind and mix all the additives and resins in the formulation more effectively.
6. Overall aesthetic value of the tape is better when the solvents are less.

Without a doubt, one can see that the lesser the toluene the better the properties of rubber adhesives became. By reducing the amount of solvent, the productive is more effective, economical, achieves faster production, better aesthetics and most importantly, it maintains environment sustainability.

Thus lesser the solvents, better the benefits.