Common oil pipes on the market, such as automotive oil pipes, are generally processed with nitrile rubber as the main raw material in the production process. Nitrile reclaimed rubber has excellent oil resistance and wear resistance of nitrile rubber. It is the mainstream raw material for replacing nitrile rubber in the production of oil pipes, ensuring the quality of products and reducing the cost of a lot of raw materials. In actual production, when nitrile reclaimed rubber is used as the main raw material to produce tubing, the type and amount of plasticizer are the main factors that affect the oil resistance of tubing, and the rational selection of plasticizer is the key.
1. Reasons why plasticizers affect the oil resistance of tubing
When using nitrile reclaimed rubber to produce oil-resistant hoses, the effect of plasticizers on the oil resistance of nitrile rubber is related to the ease with which it is extracted by petroleum solvents in nitrile rubber or nitrile reclaimed rubber. The degree of extraction depends on the molecular structure of the plasticizer. It is easy to extract the linear structure of the alkyl group, and it is difficult to extract the plasticizer with high polarity such as phenyl and ester group. It should be noted that if there are more branches in the straight alkyl chain, the diffusion effect of plasticizer molecules can be reduced, and a better oil resistance effect can be exhibited.
When using nitrile reclaimed rubber to produce oil-resistant and cold-resistant hoses, the cold-resistant plasticizer is easily extracted in the oil, and the oil-resistant performance is reduced; it can be seen that the influence of plasticizer on the cold-resistant and oil-resistant of nitrile vulcanizate is contradictory. For example: when nitrile rubber/nitrile reclaimed rubber is used and DBP is used to plasticize the breather hose, DBP will affect the oil resistance of the rubber compound, and the dosage should be appropriately reduced.
2. Application of nitrile reclaimed rubber in several oil-resistant hoses
In actual production, nitrile reclaimed rubber can be used in ordinary oil-resistant rubber hoses, rubber-plastic blend fuel hoses, oil delivery hoses, ventilation hoses, etc. Polymers are used in combination. For example, ordinary oil-resistant rubber hoses can be produced using nitrile reclaimed rubber/nitrile rubber/chloroprene rubber, and the inner rubber and outer rubber of oil delivery hoses can be produced using nitrile reclaimed rubber/nitrile rubber/PVC blended materials.
3. Selection skills of plasticizer for nitrile reclaimed rubber oil-resistant hose
When using nitrile reclaimed rubber or nitrile rubber/reclaimed rubber as the main raw material to produce oil-resistant hoses, most of them use butyl benzyl phthalate (BBP), tricresyl phosphate and dinonyl phthalate (DNP) and other oil-resistant plasticizers. Polyester plasticizers have large molecular weight, very high temperature for solvent extraction, low volatility and low permeability, but are not ideal for cold resistance, plasticization and compatibility with rubber, so those with strict requirements on oil resistance are especially Polyester plasticizers should not be used for rubber pipes that require cold resistance.
When choosing plasticizers for nitrile reclaimed rubber oil-resistant hoses, it is not only necessary to pay attention to the influence of plasticizers on the oil resistance of rubber compounds, but also to comprehensively consider the effects of plasticizers on the processing properties of rubber compounds and the elasticity of vulcanized rubber.