Natural rubber latex (NRL) is one of nature's most versatile materials and the polymer of choice for medical devices. It is a cost-effective material that provides good barrier properties, durability and comfort. However, the emergence of latex protein allergy has generated adverse publicity on the acceptability of NRL in the health care sector by anti-latex lobby. This has prompted extensive R & D efforts to reduce the incidence of allergy and ensure that NRL medical gloves are of minimum health risk.

One of the solutions to address the latex protein allergy is to use low protein NR latex (LOPROL). This type of latex can be prepared by treating latex with proteolytic enzyme or a suitable surfactant and purification process by dilution, centrifugation or membrane separation. The reaction mechanism for breakdown of polypeptide chain by enzyme is shown below.

Enzyme Reaction on Protein Molecule

Manufacturing Process

A. Enzyme Treatment
The MRB has developed several processes of producing low protein NR latices using proteolytic enzymes such as Alcalase or Savinase. The flowchart below shows one of the processes of producing low protein NR latex.


B. Non-enzymatic process
The MRB has also developed several processes of producing low protein NR lattices using non-enzymatic process. The flowchart below shows a typical non-enzymatic processes of producing low protein NR latex.


Properties

The nitrogen content of low protein latex prepared using enzymatic and non-enzymatic process is in the range 0.05% - 0.09% and 0.02% - 0.06% respectively. The extractable protein content of wet-gel leached plus post dry-leached films prepared from these two type of latices is less than 100 g/g. The physical properties of sulphur vulcanised films prepared from these latices are comparable to those prepared from normal NR latex concentrate.