Research On Automotive Sealing Strips

Automotive sealing strips are an important accessory for determining the quality of a complete vehicle,and are critical to the sealing and comfort of the vehicle.At present,most automotive sealing strips are dense or foamed sealing strips made of EPDM.With the maturation of dynamic vulcanization technology,thermoplastic elastomers(TPV)with full dynamic vulcanization of ethylene-propylene rubber and polypropylene began to shine in the sealing strip industry.TPV material not only has excellent elasticity and aging resistance of EPDM rubber,but also has good processing performance of polypropylene(PP)plastics.What is more valuable is that TPV material can be recycled and utilized repeatedly,which conforms to the call of the current society for green environmental protection industry.With the deepening of economic globalization,in the face of the impact of foreign mature sealing strip industry,how to reduce the formula cost,optimize process parameters,improve production efficiency,is a difficult problem for domestic sealing strip enterprises.At the same time,the domestic industry should also accelerate the pace of research and development of the frontier material EPDM/PP-TPV of automobile sealing strips,catching up with the international level and achieving overtaking of corners.In this paper,the formulation and process of EPDM sealing strip and EPDM/PP-TPV sealing strip are studied.The formulation factors such as reinforcing system,foaming system,vulcanization system and modifier,as well as processing parameters such as processing temperature and time are discussed.The vulcanization properties,mechanical properties and thermal aging properties of the materials.The results show that in the formulation design of EPDM solid sealant,the reinforcement effect of white mud without surface treatment is equal to that of light calcium carbonate.The silane coupling agent Si69,silane coupling agent A-151 and titanate coupling agent 201 were used to modify the white mud.The white mud modified by Si69 has the best effect and can give the most vulcanized rubber.Good mechanical properties and anti-aging properties.As the amount of Si69 increases,the mechanical properties of the rubber compound reach a maximum value at a mass fraction of 2%.When the white clay and other mass components in the best modified state replace the white carbon black and light calcium carbonate,the performance indexes of the vulcanizates are improved,and the volume can be increased by 33.3% when equivalent replacement of light calcium carbonate,which can effectively reduce the formula cost.In the formulation and process design of EPDM foaming sealant,OBSH and Na HCO3 were 8 and 4 respectively in the foaming system.Vulcanization system and promote the TMTD was 0.7,andpromote BZ was 2.5,and the DM was 0.5,promote the DTDM was 1.0,the foaming temperature is 240 ℃,foaming time for 7 min conditions,vulcanization rate and foaming rate match well.Can produce foam density is small,bubble hole density uniform,uniform distribution,and a smooth skin closed-cell foam material,its tensile strength is 2.8 MPa,331% elongation at break,tear strength is 18.97 k N/m,foam density is 0.46 g/cm3,after all the performance in line with the national standard GB/T 21282-2007,and processed under high temperature 240 ℃,foaming and curing fast,can effectively improve production efficiency.In the formulation and process design of EPDM/PP-TPV sealing strip,the rubber/plastic ratio of EPDM/PP,the amount of DCP and paraffin oil,and the blend temperature will have a great impact on the performance of TPV,and the high proportion of PP will reduce the elasticity of TPV material.Too little DCP will lead to incomplete sulfide,too much DCP will cause the decomposition of PP,and reduce the mechanical properties.The addition of paraffin oil can reduce the tensile strength and compressive permanent deformation resistance,but the appropriate amount of paraffin oil can increase the elongation at break of the sample.Processing temperature is too low will cause uneven mixing,but the temperature is too high,especially after 180 ℃,and will cause the decomposition of the PP phase,resulting in product performance fell sharply.Therefore,when the PP/EPDM rubber-plastic ratio is 11:24,the DCP dosage is 1.25 parts,and the paraffin oil dosage is 12.5 parts,the tensile strength is 7.69 MPa when blended for 12 min at a temperature of 175 ° C and a rotation speed of 50 r/min.A dense TPV strip with an elongation at break of 336%,a compression set of 9.12%,and a Shore A hardness of 76.Its performance fully meets the requirements of rubber sealing strips for passenger cars.