Deproteinised Natural
Rubber (DPNR) is a purified form of natural rubber (NR) from which
most of the ash and protein components have been removed. The rubber
is produced under very closely controlled conditions at the Rubber
Research Institute Experimental Station, Sungai Buloh, Selangor,
Malaysia. It contains about 96% rubber hydrocarbons compared to
about 93% for normal natural rubber grades. The removal of these
non-rubber components confers special attributes to the rubber which
enhance its value in certain specialized applications.
DPNR CV Production Process
DPNR is prepared by treating field latex with a
proteinase to hydrolyse the proteins in the latex which are then washed
away during processing. Ammonia, a non-ionic surfactant, a proteinase
and hydroxylamine Neutral Sulphate (HNS) are added into bulked field
latex and allowed to react for 72 hours in a stainless steel conical
bottom reaction tank. After the completion of the enzymatic hydrolysis
reaction, the reacted latex is neutralized with dilute formic acid
and coagulated by steam in a specially designed steam column coagulator.
The resultant coagula are then processed in a continuous fashion through
a series of crepers and finally chopped into small crumbs in a shredder.
The crumbs are pumped through a static screen before entering the
dryer boxes. The wet crumbs are then dried at about 85oC for about
6 - 8 hours in a hot air dryer. After cooling the crumbs are weighed,
pressed, baled and packed to SMR standards.
DPNR – Grades
Two principal grades of DPNR are available. They
are:
- DPNR CV – Viscosity stabilised at between 60 –
70 Mooney units.
- DPNR S – No viscosity stabilisation feature. The
initial viscosity is between 70 – 80 Mooney units. Owing to the
education on non-rubber content, the DPNR S has a very much less
storage hardening than the normal NR.
Characteristics Of DPNR
- Very low protein content
- Very low dirt and ash contents
- Low volatile matter content
- Light colour
- Negligible nitrosamines
- Very low antigen content
| Specifications |
|
|
|
| Property |
|
|
|
| Dirt retained on 44 aperture
sieve (% wt max) |
0.01 |
0.01 |
|
| Ash content (% wt max) |
0.15 |
0.15 |
|
| Nitrogen content (% wt
max) |
0.12 |
0.12 |
|
| Volatile Matter content
(% wt max) |
0.30 |
0.30 |
|
| Mooney viscosity [ML(1+4)@100ºC] |
60-70 |
- |
|
| AP(Max) |
8 |
- |
|
| Wallace Plasticity (min |
- |
35 |
|
| |
|
|
|
These raw rubber characteristics are reflected
in the following valuable attributes of DPNR vulcanisates particularly
when compounded using soluble vulcanising systems.
Lower creep and stress relaxation Lower water absorption Greater
consistency in modulus under conditions of variable humidity
|
| |
|
|
|
| Area of Application |
|
| Features |
Applications |
| Low stress relaxation & creep |
Seals, Joint rings, Hydro-mounts |
| Low water absorption |
Undersea applications |
| Good dynamic properties |
Anti-vibration mountings |
| Low protein |
Medical and food applications |
| |
|
| Packaging |
|
| The standard packaging for DPNR is
in 1.2 metric tonne wooden crates with the following specifications:- |
| No. of bales per crate |
36 |
| Bale weight (kg) |
33.3±0.5 |
| Bale nominal dimensions |
330 x 670 x 170 mm |
| Bale wrapper |
Thickness: 0.03-0.05 mm |
| |
Density: 0.92 g/cc |
| |
Melt point: 109ºC |
| |
Compatible with rubber @ 110ºC min |
Other forms of packaging/wrapping can be provided on request |
Deproteinised Natural Rubber (DPNR) 
