Synthesis Of SMA And Its Effect On The Preparation Of Melamine Formaldehyde Essential Oil Microcapsules

Protective colloids play a vital role in the preparation of microcapsules.Among them,styrene-maleic anhydride copolymer(SMA)as a protective colloid is widely used in the preparation of melamine-formaldehyde(MF)essential oil microcapsules However,so far,the work reported in the literature has basically used SMA imported from the United States to directly prepare microcapsules and study related properties There is no systematic work to study the effect of the structure of SMA on the preparation of MF essential oil microcapsules.In addition,although MF essential oil microcapsules have been widely reported,MF wall materials will release free formaldehyde during use,which is not conducive to environmental protection and health.Therefore,systematic research on the structure of SMA have important significance for the preparation of essential oil microcapsules and how to reduce the content of formaldehyde in MF essential oil microcapsules for the development of MF essence microcapsules.In this paper,a series of SMAs with different structures were first synthesized by solution polymerization,and then lily essence oil was dispersed by using salified SMA sodium salt solution as protective colloid,and lily essence microcapsules with MF and low formaldehyde content were prepared by in-situ polymerization.The effects of the molecular weight and structure of SMA on the dispersion of flavors and the preparation of MF flavor microcapsules were mainly explored.Then,using glutaraldehyde to replace part of the formaldehyde to prepare low formaldehyde content essential oil microcapsules,the preparation process of using in situ polymerization to prepare low formaldehyde content essence microcapsules was explored.the result shows:1)The molecular weight of SMA is related to the preparation conditions and structure.For the SMA composed of equimolar ratio,the increase in the amount of initiator and the amount of solvent will lead to a decrease in the molecular weight of SMA,and the addition time of styrene shows a random change in the molecular weight of SMA.For SMAs composed of non-equimolar ratios,increasing the molar ratio of any component will cause the molecular weight of SMA to decrease.For the SMA introduced with the third monomer,the molecular weight of AA is the largest,the molecular weight of MMA and BA is similar,and the molecular weight of AM is the smallest.2)The molecular weight and structure of SMA will affect its dispersion of essential oils.For SMA fed in equimolar ratio,the decrease of SMA molecular weight will lead to better dispersion stability of fragrance and smaller droplet size of essential oil.For non-equimolar SMA feeding,increasing the molar ratio of any component will lead to poor dispersion stability of essential oils and the particle size of essential oil droplets tends to increase,and a certain component The higher the molar ratio,the worse the dispersion stability of the fragrance.For the SMA introduced with the third monomer,the particle size of the essential oil droplets dispersed by introducing AM is larger than that of AA,MMA,and BA,and the dispersion stability of the essential oil by introducing AA is more than that of introducing AM,MMA,and BA.it is good3)The molecular weight and structure of SMA will affect the process of preparing essential oil microcapsules and the performance of microcapsules.When the SMA monomer feed is n(st)?n(Mal),the addition of MF prepolymer will cause the particle size of the essential oil droplets to become smaller,and the decrease in the molecular weight of the SMA with the same feed ratio will cause the microcapsules to become worse The surface of the capsule shell becomes rough and sparse,and the higher the molar ratio of maleic anhydride,the denser the microcapsule shell prepared.When the SMA monomer feed is n(st)>n(Mal),after adding the MF prepolymer,the particle size of the essential oil droplets first becomes larger and then the particle type becomes worse until it is difficult to form microcapsules.Within a certain range,microcapsules with better spherical and shell properties can be prepared.When SMA introduces the third monomer,it is difficult to prepare spherical microcapsules with regular shapes4)The greater the molar ratio of glutaraldehyde,the faster the prepolymer reaction and the worse the water solubility;the higher the molar ratio of formaldehyde glutaraldehyde,the faster the prepolymer reaction and the better the water solubility.When using SMA with a feed ratio of Mal:St=1.5:1 as the protective colloid,the feed ratio of the prepolymer is n(melamine):n(glutaraldehyde):n(formaldehyde)=1:0.9:2.1,the reaction pH=4.2 and when the reaction time reaches 6h,spherical microcapsules with regular surface and smooth surface can be prepared.