Why Can't We Make Very Thin NR Gloves?

Manufacturer: Most glove manufacturers today are making medical examination gloves based on NBR latex. In fact, the NBR gloves are now very light and thin. Why can't we make NR gloves with similar weight and thickness? We were encountering many problems when we tried to do this.

John Woon (Senior Latex Consultant): Yes, Nitrile examination gloves are getting thinner from approximately 7 to 9 grams to 3 to 5 grams per glove (i.e. from about 0.15 mm to 0.05mm). This is to ensure "softness" of the gloves.

While the physical properties (i.e. tensile strength, modulus and elongation at break) of the glove remain unchanged, the thinner the glove, the "softer" would be the glove to the touch. As a result, the dexterity and tactility improve. Likewise, a rubber film always feels "softer" than a rubber sheet although both are made using the same rubber compound, with no change in the inherent modulus.

But why can't we make similar thin gloves with NR latex?

The answer is quite simple, really. It has a lot to do with the modulus of the base rubber. Compared to Nitrile rubber, natural rubber has quite a low modulus. Therefore, a thinner NR examination glove would be too soft to handle or process, not to mention the possible higher degree of tackiness.

The solution to this "problem" is obvious - Increasing the modulus of the NR gloves.

This can be done in either one or a combination of the following steps:

1) Re-design of the curative recipe e.g. increasing sulphur level, use of ZDEC/ZMBT blend (Note: a curative for maximum tensile strength would also help)

2) Addition of high-styrene SBR latex

3) Addition of Methyl Methacrylate-grafted NR latex