Preparation Of Air-Filled Microcapsules By In-Situ Polymerization And Its Application In Paper

Microcapsules prepared by the in-situ polymerization method mostly use solid or liquid materials as the core material,bare of gases.In this investigation,air-filled microcapsules with melamine formaldehyde(MF)resin as wall material were prepared by in-situ polymerization method,and applied to paper to discuss its influence on the usability of bulky paper.In the process of air-filled microcapsules preparation,the effects of temperature,emulsifier concentration,stirring rate,pH value and wall material dosage on the synthesis of microcapsules were discussed.This study used sodium dodecyl sulfate(SDS)as emulsifier,and the optimum process conditions for the synthesis of air microcapsules were preliminarily determined by a single variable method:55? of polymerization temperature,0.2%SDS concentration,1400 r/min of stirring rate,4.0 of system pH value and 9 mL of MF resin prepolymer solution dosage;it were finalized as that the desired microcapsules were obtained at a temperature of 55?,an SDS concentration of 0.2%,a stirring rate of 1600 r/min,a pH of 4.0,and a MF resin prepolymer solution dosage of 9 mL by orthogonal experimentand.The obtained microcapsules have the best morphology,and the wall thickness and particle size were the most uniform.The average particle size of the obtained microcapsules measured by Nano Measure 1.2 software were 8.39?m.Properties of the air-filled microcapsules that prepared under the optimal conditions were characterized.The SEM images showed that the microcapsules were spherical hollow spherical structure.The IR analysis showed that the MF resin wall material was completely polymerized.The bulk density test shows the packing density of air-filled microcapsules is 0.05 g/cm3,far less than that of MF resin(0.57 g/cm3).Based on the analysis of SEM,infrared spectrum and bulk density test,the prepared air-filled microcapsules are hollow microsphere with MF resin shell.The compressive strength test shows that the air-filled microcapsules can withstand a pressure at least 0.52 MPa.All of these can prove that air-filled microcapsules could be used as a bulky agent for bulky paper.The obtained air-filled microcapsules were applied into a bulky paper of 80 g/m2 by adding them in pulp,and compared with the blank paper and diatomaceous earth added bulky paper with the same quantitative.The results of bulkness,whiteness,tensile strength.burst strength and opacity tests shows that the air-filled microcapsule added bulky paper meets the performance requirements.Furthermorc,the burning proterty test on the three kinds of bulky paper shows that the air-filled microcapsules added bulky paper has a certain flame retardant property.It suggests that the air-filled microcapsules with MF resin as wall material can be used as high quality bulky agent to prepare bulky paper with flame retardant properties and high thickness.