R&D And Test Of The Nonwoven Material For Automobile Noise Reduce

With the development of the automotive industry,noise reduction material applied in automotive for noise control has become more and more popular.Currently, noise reduction materials in China has been left behind,which directly constrains further upgrading of noise reduction performance,because of the high cost of 3M Company noise material and the fact that Chinese enterprises cannot supply large-scale production of superior noise reduction materials at a moderate price, thereby affecting the development of domestic auto industry.Therefore,the development of a kind of noise reduction material with high performance,ease of large-scale production to meet domestic demand for middle and low scale cars, attaches much importance to grow China's automobile industry and to enhance the international competitiveness.Due to simple process,recyclable and good stability,the melt-blown nonwoven materials have been increasingly applied in the field of vehicle noise reduction.Three aspects of this study on vehicle noise reduction material by melt-blown have been done on the base of carrying out technical surveys,literature search and international exchanges.Firstly,following the traditional and 3M Company melt-blown process,the production line was effectively improved and new parts were increased,including staple fiber opening and delivering framework,as well as double-drum receiving composite forming equipment.Secondly,samples were made on the improved equipment,and thickness,density, fiber diameter and air flow resistance parameters of the physical structure were tested. Single factor,orthogonal and range & variance analyzing method were used to analyze the influence of hot stretching air pressure,volume of polymer extrusion, drum speed,and the gap of two drums in the process of Meltblown on physical structure parameters.Thirdly,noise reduction index(Absorption Coefficient,Sound Insulation Volume) were tested on a set of system which can be operated easily at a low cost,and drew the influencing curve of physical structure parameters on noise reduction index. Finally,noise reduction property of samples with approximately the same thickness and density were compared with those made by 3M Company.Through the study,we can draw the following conclusions about the subjects:Firstly,by the use of this melt-blowing technology issues the area density and thickness of the products can be controlled better than before,double roller's pace directly determines the thickness;the adoption of polymer extrusion and drum rotational speed determines the density;while the hot air pressure becomes bigger, melt-blown fiber diameter become smaller.Secondly,porosity and air flow resistance is an important indicator to measure sound absorption coefficient,porosity is determined by the density and thickness.Air flow resistance is related to the size of melt-blown fiber diameter and the distribution of internal pore size,fiber and pore distribution make the larger absorption coefficient. the thickness is the most important impact factor of the sample absorption coefficient, the thickness becomes larger makes the absorption coefficient of the sample become high;sample surface density of the absorption coefficient influential,with the increase of density,the sample absorption Sound coefficient also increases;the average melt-blown fiber diameter in 1.5 - 2μm has no obvious impact on absorption coefficient.thirdly,the area density of the sample is the most factor of its sound insulation,if other physical parameters is the same or close to,with the area density increases,the area density of noise will also increases;the thickness has little impact on sound insulation.Fourthly,in the low frequency band,the sample absorption and sound insulation performance is not good.Specimen has a good performance of noise reduction for sound waves which more than 2000Hz frequency,sound absorption coefficient is greater than 0.2,sound insulation is greater than 3.5 db noise.Fifthly,Analysis the specimen whose area density and thickness is very closer to 3M Company's products for noise reduction performance testing,the results show that the specimen have the same noise reduction ability and it can take the place of 3M Company's products.