Preparation Of Anti-Mosquito Microcapsulesand Their Applications

As one of the insects,mosquito has great affinity to people’s life.They transmit several diseases through biting,which brings several diseases to human beings.As one kind of functional finishing methods,anti-mosquitoes finishing had three implementing methods,the first one was adding the anti-mosquitoes effective components into spinning fluid,then made anti-mosquitoes fibers;the second one was prepared finishing agent by virtue of carrier,then applied it on textiles directly;the third one was coated the anti-mosquitoes with some polymers to make microcapsules finishing liquid,then applied on textiles.In this paper,we selectedβ-cypermethrin and deltamethrin as anti-mosquito effective components,urea-formaldehyde resin and polyurethane as wall materials to form microcapsules with in situ polymerization and interfacial polymerization separately.This not only avoided direct contact with skin,but also ensured the persistent effect.In situ polymerization,method was employed to prepare urea-formaldehyde resin microcapsules using urea and formaldehyde as reaction monomers,the polymers produced could entrap core materialsβ-cypermethrin to form microcapsules.Interfacial polymerization method was employed to prepare polyurethane microcapsules using 2,4-toluene diisocyanate(TDI)and polyethylene glycols(PEG)as reaction monomers,dibutytin dilaurate(DBTDL)as the catalyst and ethylene diamine(EDA)as chain extender.The polymers produced could entrap core materials deltamethrin to form microcapsules.UV-M image analyzer and laser granularity tester were employed to investigate the shape,the mean particle size and distribution of the formed microcapsules.The structures of wall materials were characterized by IR-spectra.The percentage of the released core materials were measured by UV-absorbancy.The optimum conditions of preparingβ-cypermethrin microcapsules had been got as follows: emulsifier 0.9%(self-made),emulsification 9500 r/min for 3 min,core/wall ratio 1:3,stirring speed 1000r/min,and reaction at 30～50℃for 2h,during this time,adjusted pH value slowly with 1%hydrochloric Acid Solution,then heating gradually to 60～70℃,curing for 1h.Microcapsules manufactured under the optimum conditions had good morphology and uniform particle size distribution,the mean particle size was about 4μm,and loading ofβ-cypermethrin was over 70%. The optimum conditions of preparing deltamethrin microcapsules had been got as follows: emulsifier 0.9%(self-made),emulsifying 9500 r/min for 3 min,core/wall ratio 1:2.8,phase ratio of w/o 2:98,DBTDL 0.04g,stirring speed 1000r/min,and reaction at 25℃for 2h,curing 1h with 0.35g EDA.Microcapsules manufactured under the optimum conditions had good morphology and uniform particle size distribution,the mean particle size was about 1.2μm,and loading of deltamethrin was over 85%.No TDI residue was determined.Two kinds of microcapsules produced were applied on mosquito nets with impregnation method.Extract and UV-absorbancy were introduced to test the content on the fabrics.Mosquito repellent experiment was carried out referring to GB/T 17322.10-1998.The result showed that,the finished mosquito net had obvious mosquito repellent effect.β-cypermethrin or deltamethrin on the fabrics decreased with increasing washing times,but the content could keep up 60～70%of the whole content even after washing 5 times.The knocking and killing experiments were carried out according to GB 13917.8-1992.The knocking ratio increased with time,and the killing ratio in 24h all over 96%.The knocking ratio decreased with increasing washing times,while the killing ratio in 24h decreased relatively less.The anti-mosquito microcapsules with deltamethrin as core and polyurethane as wall were firstly investigated,also we compared their mosquito repellent and knocking and killing effect withβ-cypermethrin urea-formaldehyde resin microcapsules.In summary,the knocking and killing effect of deltamethrin microcapsules were much better thanβ-cypermethrin microcapsules.