Preparation And Performance Study Of Modified Polypropylene Sheath-core Meltblown Filter Material

Air is an important basic condition for human survival,with the development of industry,air pollution gradually deepened,in addition,with the frequent occurrence of new crown epidemic at home and abroad,people's demand for air filtration products for personal protection increased,and its filtration performance requirements are higher.Polypropylene(PP)meltblown cloth is the most common air filtration material,the main way to improve its filtration performance is the electret treatment of the material,however,its effect is affected by the ambient temperature and humidity and the storage time of the material.In order to improve the electret stability of meltblown materials,electret materials can be added to electret modify PP,but according to previous studies,the influence of electret materials on the apparent morphology and handfeel of nonwoven fabrics is very large.Based on this,this project adopts the sheath-core meltblown technology to prepare PP/PP+ electret masterbatch sheath-core meltblown material by adding electret masterbatch to the fiber core layer to solve the problem of poor homogeneity of meltblown material fiber network after electret modification.In ordert to solve the problem of unstable electret effect,in this project,electret masterbatch was chosen as the electret material and mixed with PP chips to prepare electret modified meltblown material.Through the preparation of monocomponent meltblown filter material,we found that the spinnability of the electret masterbatch was not good.We found that the filtration performance of the meltblown material was best when the electret content was 4 % and the surface density was 30g/m2.After electret treatment,the filtration efficiency of meltblown cloth increased,but the resistance of single-component meltblown material increased with the increase of electret content,indicating that the addition of electret masterbatch did not achieve the expected effect of enhancing the filtration performance of the material.The sheath-core meltblown filter material was prepared by a biocomponent meltblown production line,and the electret masterbatch was mixed into the core layer.It was found that the surface of the electret-modified sheath-core meltblown material was smooth and soft to the touch,and its fiber network uniformity was less affected.By investigating the influence of process parameters on the material's apparent morphology,air permeability and filtration effect,using the CV value of fiber diameter and filtration performance as indicators,the optimal process parameters of the sheath-core meltblown material were determined as follows: melt flow rate of 100 cc/min,hot air pressure of 119.3 k Pa,receiving distance of 320 mm,under-net suction speed of 3000 r/min and hot air temperature of 270 ?.The filtration efficiency and resistance of the material were tested after changing the electret content and treated with double-sided electret,and it was found that the filtration resistance of the sheath-core meltblown material decreased with the increase of the electret masterbatch content.Comparing the surface morphology and air permeability of the monocomponent and sheathcore meltblown materials,it was found that the sheath-core meltblown materials have more uniform fiber network and greater air permeability.The main reason is that in monocomponent material,the electret masterbatch is dispersed in the whole fiber,while in sheath-core material,the electret masterbatch exists only in the fiber core layer,and the sheath structure is pure of PP,so the spinning effect of sheath-core fiber is less affected than monocomponent meltblown material.The filtration efficiency of the electret-treated material was higher than 85 %.The more the content of electret masterbatch,the greater the increase of filtration efficiency of meltblown material.After 60 days,the surface electrostatic potential and filtration performance of the meltblown material were measured again,and it was found that the surface electrostatic potential of the electret-treated material was higher than that of the non-electreted material.It was discovered that the addition of the electret masterbatch really increase the electret effect of the meltblown material.The filtration efficiency of the meltblown material was highest at 6 % electret masterbatch,and the filtration efficiency decay was lowest when the cotent of electret masterbatch is 8%.