At present, the common production method of nitrile rubber products is to use nitrile rubber and nitrile reclaimed rubber together to achieve a win-win quality and cost under a reasonable formula; when the nitrile rubber and the nitrile reclaimed rubber are used together, the amount of the nitrile reclaimed rubber is used. The increase will lead to a slight decrease in the strength of the rubber compound, so the reinforcement is required. Magnesium oxide is the most commonly used reinforcing agent in the nitrile rubber product except for carbon black and white carbon black. So how much is the effect of magnesium oxide in NBR products, and how much is appropriate?
Magnesium oxide is an oxide of magnesium, which is a white solid at room temperature. The rubber product industry uses magnesium oxide white powder. In general, the addition of magnesium oxide can effectively improve the heat resistance, oil resistance and flexural resistance of the nitrile rubber/recycled rubber and the rubber compound, especially the high-purity calcined magnesia, and the reinforcing effect is more obvious.
In theory, the amount of magnesium oxide can be increased to about 100 parts during the production of NBR products; however, studies have shown that excessive magnesium oxide can increase the tensile strength of the rubber, but at the same time it will compress the nitrile vulcanizate. Increased permanent deformation, low elongation at break, poor flex resistance, especially surface treated active magnesium oxide; therefore, a low sulfur system should be selected in the formula of nitrile rubber containing active magnesium oxide, and It is used together with an anti-aging agent with obvious anti-flexibility cracking effect to improve the properties of the nitrile rubber/recycled rubber and the rubber compound.
In the actual production process, although active magnesium oxide has a certain influence on the tensile strength and flexural strength of the rubber compound, the addition of active magnesium oxide will also affect the processing performance of the nitrile rubber compound, making the nitrile rubber and the reclaimed rubber Mooney. Increased; but the surface activity, dispersibility and compatibility of active magnesium oxide in nitrile rubber compound is better, and it can also improve the heat aging resistance of rubber compound to a certain extent, so more rubber products manufacturers are willing to Use active magnesium oxide.
Magnesium oxide can be divided into ordinary magnesia and active magnesia according to surface activity. Different types of magnesia have different reinforcing effects in nitrile rubber products. Rubber products manufacturers need to select suitable kinds of magnesia according to actual needs, and reasonable. Control the amount of magnesium oxide in order to achieve the best results.
In order to further improve the mechanical strength and heat resistance of the nitrile rubber/recycled rubber and the rubber compound, a thermosetting phenolic resin, a polyvinyl chloride resin, a polyamide resin or a polyphenylene may also be used in the formulation of the nitrile rubber product containing magnesium oxide. The vinyl resin improves the tensile strength, tear strength and hardness of the nitrile rubber product, and further improves the heat resistance, oil resistance and ozone resistance of the nitrile rubber product.