Processing Aid & Reinforcement for Rubber Compounds - SUPRA-MNV 102

Technical Memorandum

Description Processing Advantages Typical Properties Application Use with Natural Rubber/Synthetic Rubber Processing Use with Nitrile Rubbers

Description

SUPRA-MNV 102 is a cashew nut shell liquid modified phenolic novolac resin pre-mixed with Hexamine. It is developed for processing rubbers like natural nitrile, SBR etc.

Processing Advantages

MNV-102 improves the processability of rubber compounds, reducing the money viscosity at the processing temperature and after hardening improves the mechanical properties such as, tensile strength, tear strength, abrasion resistance and oil, petroleum, acid and water resistance.

MNV-102 lowers the mooney viscosity of the rubber compound during processing, large amounts of cheap fillers can be loaded in the compound to give optimum properties at low cost. This resin can partially replace carbon black. Since the resin has low specific gravity than carbon black, substitution of carbon black by the resin improves mechanical properties without increasing the specific gravity appreciably. MNV-102 can also partially replace sulphur as it has vulcanising properties.

Being a novolac resins MNV-102 has a fairly long shelf life at ambient conditions.

Typical Properties

Application

MNV-102 is a very versatile resin for rubber compounding. It finds use in rubber products such as: Tyre, Belts & Beltings, Hoses, Rice de-husking Rollers, Battery Boxes, Textile Cots and Aprons, Oil Seals, O-rings, Cables, Gaskets, Footwear, Rubberised Cork Sheets and a host of moulded and extruded products.

Use with Natural Rubber/Synthetic Rubber

This is readily dispersible in natural rubber at all loadings. They reinforce hardness according to the amount employed to give products, which may vary in nature from soft vulcanisation to hard ebonite-like material. Initially these are thermoplastic, but they cure during the vulcanisation process thereby forming an integral part of the system.

Processing

When processing on open rolls, this resin, preferably mixed with desired hillers, should be incorporated into the rubber after minimum mastication and the mix rendered homogenous to 90-100°C. Sulphur and accelerators may then be introduced after cooling. Alternatively the resin may be master batched at 90-100°C with an equal weight of rubber and the master batch subsequently blended with other desired ingredients. This resin may also be incorporated in the Banbary without the application of heat to either rotor or jacket.

Use with Nitrile Rubbers

When used in conjunction with nitrile rubbers, this rubber reinforcing resin functions both as reinforcing agent and a processing aid. Under normal circumstances the stiffness of nitrile stocks mitigates against high filler loadings in the absence of plasticizers. Consequently it is extremely difficult to obtain products of intermediate hardness since the conventional plasticizers are subject to the disadvantages of migration during ageing and of being removed by leaching.

But, this resin initially imparts plasticity and cure simultaneously with vulcanisation and becomes an integral part of the system. This considerably enhances the resistance of the product to ageing to chemical attack and to the action of solvent and oils. The effect of the resin on tensile, modulus and hardness is most marked. By varying the ratio of resin to nitrile rubber, all grades of hardness upto absolute rigidity may be obtained.

In general, the processing of this rubber reinforcing resin with nitrile rubbers should be as follows.

Masticate the rubber on a cold roll for five minutes. Add zinc oxide, turn off cooling water, cut and blend. Add resin or black and lubricant, while raising the temperature of the rolls to 90-100°C and maintain for 10 minutes, cutting and blending. Apply cooling, cut and blend. Add sulphur and accelerators, cut and blend. Sheet off.

When resin loadings of upto 1:1 are employed, the normal ratios of sulphur and accelerators are recommended. As the resin loading is increased the sulphur content may be progressively decreased and at loadings in excess of 1:1, the sulphur and accelerators may be eliminated entirely, if desired.

Note: Whilst the above information is based on the result of experimental work in our laboratories and is correct to the best of our knowledge, users are recommended to establish for themselves so that the process and materials are satisfactory for their requirements. Freedom from patent rights must not be assumed. No liability is accepted by us for any damage, injury or loss, resulting from the use of this information.