Preparation Of Stainless Steel Reinforced Foamed NBR By Hollow Polymer Microsphere For Sealing Plate

With the continuous improvement of the industrialization process,the vigorous development of the metal sealing industry is conducive to the improvement of national strength and the advancement of science and technology.As the highest-yield product in the metal seal manufacturing industry,NBR-Metal Composite Sealing Plate combines the high elasticity of rubber,excellent compressibility and oil resistance,and the excellent mechanical strength and hardness of sheet metal.At present,it has become the most used sealing product for automobile engines and oil pumps.Although China is also developing foamed rubber sealing materials,the preparation method of high expansion ratio NBR-metal composite board has been monopolized by foreign countries for a long time.Therefore,the preparation of high expansion ratio NBR-metal composite sealing materials can break down technical barriers and increase the competitiveness of related industries in China.The polymer foaming microsphere is a foaming agent having a core-shell structure,and has a low-boiling alkane liquid in the core,and foams the microspheres after being heated and vaporized.The outer acrylic shell has good elasticity and can withstand the pressure generated by the expansion of the microspheres.The expanded microspheres have a stable volume,and have the advantages of large expansion ratio and low opening ratio.The microsphere foaming agent has good compatibility with the nitrile rubber vulcanization system,and can be perfectly combined with rubber to replace the traditional gas foaming agent to prepare NBR-metal composite sealing material.In this paper,the microsphere foaming agent is applied to the preparation of NBR-metal composite sealing plate,and a high foaming ratio product is obtained,which fills the gap in China.(1)The polymer foamed microspheres have the advantages of low foaming temperature and high expansion ratio,and the particle diameter after foaming can reach 200 μm or more.The NBR-metal composite sealing material prepared by using the microsphere foaming agent can be controlled by the original size and expansion ratio of the microsphere foaming agent.The foaming microspheres and the nitrile rubber vulcanization system have better compatibility with traditional foaming agents.When the NBR foaming material is prepared by wet coating and free foaming process,the process conditions have a greater influence on the sealing material.When the polymer foamed microsphere A in the formulation is 3 phr,the viscosity of the rubber is 1200 cP,the vulcanization temperature is 160 °C,and the vulcanization time is 30 minutes,the NBR-metal composite sealing material has the best performance.The foaming ratio is 4.40 times,and the average cell size is 149.74 μm.The Kemrock adhesive primer treatment can increase the adhesion of the NBR compound on the metal sheet.The top coating treatment can improve the appearance and surface properties of the NBR-metal composite sealing material,which is beneficial to the long-term storage of the sealed product.(2)In the nitrile rubber formula used to prepare NBR-metal composite sealing material,the amount of sulfur and the amount of carbon black N330 can improve the degree of rubber crosslinking,and the vulcanization system and the promotion system can effectively improve the vulcanization performance of the rubber.This is the best formula when the amount of sulfur is 1 phr,N330 40 phr,using CZ+DM+TMTD vulcanization system,the accelerator ratio DM: TMTD is 50:50.Under this formula,the vulcanization of nitrile vulcanizate is 2 minutes and 5 seconds,and there is no vulcanization and reversion.The vulcanizate has excellent mechanical properties,tensile strength of 18.03 MPa,elongation at break of 558.58%,tear strength of 49.43 KN/m,and Shore A hardness of 64.Vulcanized rubber air aging test was 16.09 MPa after 168 hours,a decrease of 1.97 MPa.The results show that the nitrile rubber has good vulcanization speed,good mechanical strength and aging resistance under this formula.(3)According to the above formula and process,the produced NBR-metal composite sealing plate has excellent solvent resistance.The thickness of the metal sealing plate can be changed according to the number of coatings,and the double-layer coating or the surface coating treatment can completely coat the foaming agent in the rubber matrix.The storage temperature of the rubber is preferably 15-25 °C,and the storage time should not exceed 30 days.