Preparation And Study Of Scratch Resistant And Soft Touch Modified Polypropylene Plastics For Automotive Interior Decoration

With the development of the automotive industry,the demand for automotive interior decoration is getting higher.Polypropylene(PP)is widely used in automotive interiors,but the scratch resistance and tactility of automotive interiors are poor at present.Scraping not only affects the appearance,but leads to stress concentration and reduces the service life of the parts.Hard tactility can not bring comfortable ride experience,so it is necessary to modify PP for automobile interior to meet the increasing requirements.In this paper,the mechanical properties,scratch resistance and surface hardness of three different types of homogeneous copolymerization of polypropylene(PP-H),random copolymerization of polypropylene(PP-R)and block copolymerization of polypropylene(PP-B)were compared,to select appropriate PP as polymer matrix.The blending system of PP-H/POE/short glass fiber and PP-H/TPU/OMMT was established according to the PP-H as the matrix material.Mechanical properties,scratch resistance,surface tactility and rheological properties were studied.The main contents of the paper are as follows:1)Selection of Matrix Materials:PP-H,PP-R and PP-B were melt processing and characterized,and the best modified polypropylene matrix material was selected.Compared with PP-R and PP-B,PP-H has higher flexural modulus and tensile strength,it also has higher yield strength and crystallinity,and lower color difference after scraping.PP-H as matrix is easier to obtain automotive interior modified polypropylene plastics with good mechanical properties,scratch resistance and soft touch.Therefore,PP-H was chosen as the modified matrix material.2)The Preparation and Research of PP-H/POE/chopped glass fiber composites:On the basis of optimizing the selection of matrix materials,PP-H/POE/short glass fiber composites were prepared and characterized.It is found that the bending modulus and tensile strength of the composites can be greatly improved by 25 wt%short glass fiber,and the mechanical properties of the composites can be improved,the color difference after scraping can be reduced and the scratch resistance can be improved.POE can increase the storage modulus and improve the rheological properties of the composites.The notched impact strength and toughening effect of the composites can be significantly improved by adding POE;POE can reduce the surface hardness of the composites.With the increase of POE content,the surface hardness of the composites decreases gradually.When the content of POE reaches25wt%,the surface hardness of the composites is lower than 52D,showing a certain soft touch.At the same time,POE content over 25wt%will increase the surface hardness of the composites.In summary,when the content of short cut glass fiber is25 wt%and the content of POE is 30wt%,the composite material with certain scratch resistance and soft touch can be obtained.3)Preparation and Study of PP-H/TPU/OMMT Composites:The blend system of PP-H/TPU/OMMT was prepared and studied.The mechanical properties,scratch resistance and tactile properties of the composites were studied.The effects of OMMT on the compatibility and rheological properties of PP-H/TPU blends were discussed.The results showed that the exfoliation degree of OMMT in the prepared PP-H/TPU/OMMT composites was perfect.The notched impact strength and flexural modulus of the composites can be improved by OMMT.The maximum notched impact strength(6.14KJ/m~2)of the composites containing 2 wt%OMMT can be increased by 59%.The compatibility between PP-H and TPU can be effectively improved by dispersing OMMT at the interface of two phases,reducing the particle size of TPU and hindering the agglomeration of dispersed phase.The addition of OMMT can improve the storage modulus and viscosity of the composites,and improve the rheological properties of the composites.When the content of OMMT is2 wt%,the hard segment of TPU can resist the scratch stress,and its soft segment gradually exhibits high elasticity and flexibility,which reduces the surface hardness of the composites.The soft segment of TPU can also recover scratches,reduce scratch stress damage to material surface and improve scratch resistance of composites.TPU and OMMT can effectively reduce the surface hardness of the composites,the surface hardness is reduced to Shore 45D.The color difference?L*before and after scraping is reduced to 0.95,which improves the scrape resistance of the composites.From the comprehensive properties,when TPU content is 30wt%and OMMT content is 2wt%,the composites have better scratch resistance and tactile.