Adhesion and Cohesion of Nitrile Latex Adhesives

Manufacturer:  We are making adhesives from Nitrile latex for bonding vinyl materials, paper and aluminum foils to be used in applications where oil resistance is required. Our formulation contains fillers and our problems are weak adhesion and bond strength. Any ideas how to overcome this problem bearing in mind the cost constrain.

John Woon (Senior Latex Consultant): You did not mention whether you were using tackifiers. Unlike Natural Rubber and polychloroprene, Nitrile rubber has poor inherent tackiness. Hence the addition of a good tackifier is a must for Nitrile.

However you should bear in mind that over addition of tackifiers might lead to poor film strength (i.e. cohesive strength).


Therefore a balance should be optimized and reached between good adhesion (tackiness) and cohesive strength (film strength). Some describe "tackiness" as "dry wetting property" which is essential for building adhesive strength between the adhesive and the two surfaces being bonded.

I appreciate your concern about cost and believe that you are adding to fillers to reduce your compound cost. However, the filler would kill both the adhesive and cohesive strength.

Unfortunately, tackifiers could be expensive. Among the tackifying resins, you could use the following types:

1) Hydrocarbon
2) Coumarone indene
3) Hydrogenated esters
4) Terpene resin

To improve the cohesive strength, you could try adding reinforcing agents such as phenolics and terpene-phenolics or other derivatives. Please discuss with your suppliers to decide on the right choice for your purpose. However I must warn that this might not work if there is too much filler in your compound.