Our Products
Indian Standard Natural Rubber (ISNR) / Block Rubber
Processing of natural rubber into blocks similar to synthetic rubbers adopting cost effective and modern processing methods is a notable improvement in the presentation of dry natural rubber from India. This is in line with the consumer preference in the world rubber market for Technically Specified Rubber, which has the following advantages:
- Technically certified rather than visually graded as in the case of RSS and crepe grades of natural rubber.
- Consistency in quality
- Compact packaging
- Low contamination in handling and transportation
Bureau of Indian Standards formulated specifications for ISNR in 1969 (IS 4588).IS 4588 prescribes 6 grades viz., ISNR 3 CV, ISNR 3 L, ISNR 5, ISNR 10, ISNR 20 and ISNR 50. Its specification details are given below.
| Characteristic | ISNR 3CV | ISNR 3L | ISNR 5 | ISNR 10 | ISNR 20 | ISNR 50 |
|---|---|---|---|---|---|---|
| Dirt Percent by Mass (Max) | 0.03 | 0.03 | 0.05 | 0.10 | 0.20 | 0.50 |
| Volatile Matter, Percent by Mass (Max) | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 |
| Ash, Percent by Mass (Max) | 0.50 | 0.50 | 0.60 | 0.75 | 1.00 | 1.50 |
| Nitrogen, Percent by Mass, Max | 0.60 | 0.60 | 0.60 | 0.60 | >0.60 | >0.60 |
| Initial Plasticity Po (Min) | As Agreed to Between the Purchaser and the Supplier | 30.00(Min) | >30.00 (Min) | 30.00 (Min) | 30.00(Min) | 30.00(Min) |
| Plasticity Retention Index, PRI (Min) | 60.00 | 60.00 | 60.00 | 50.00 | 40.00 | 30.00 |
| Colour (Livibond Scale) | - | 6.0 | - | - | - | - |
| Mooney Viscosity (1+4) at 100 C | 60+5- | - | - | - | - | - |
| Accelerated Storage Hardening Po (max) | 8.00 | - | - | - | - | - |
| Colour Code | Black | Black | Green | Brown | Red | Yellow |
Applications of ISNR grades
- ISNR 3 CV: High quality products with superior dynamic properties.
- ISNR 3 L: Colored products like injection bottle caps, syringe heads, transparent items.
- ISNR 5: Moulded and extruded items like auto components, bridge bearings,rubber linings etc.
- ISNR 10: Inner tubes, conveyor belts, footwear, water proofing materials, hoses and tubes.
Packing Standards of ISNR (Block Rubber)
The material will be wrapped in low density polythene sheets and shall be further wrapped as per buyer’s requirement. The block rubber will be further packed in pallets or crates. Material of pallet/crate is wood, steel or any other material as per buyer’s requirements. Net mass of rubber is 1MT/1.2MT/1.26MT. Polythene sheets which are easily dispersible in rubber having thickness 0.030 to 0.038 mm, relative density 0.92 and melting point 109 C max are generally found suitable for wrapping raw rubber blocks.
