Development Of Micro-capsule With Fluorine-containing Monomer As Core Materials And Its Application In Coatings

Materials with low surface energy are widely used in many aspects,such as:printing,medicine,anti-corrosion and stain-resistance,etc.due to their good amphiphobic and non-stick properties.However,these kinds of materials have bad compatibility with coatings.This limits applications of materials with low surface energy in coatings.In order to solve this problem,materials with low surface energy are encapsulated before adding into coatings.In this way,materials’ low surface energy property is preserved before using.And their low surface energy property also can be brought into effect as released.Four different special kinds of materials with low surface energy,i.e.containing hydrogen silicone oil,fluorine-containing monomer,two kinds of self-made fluoroalkylsiloxane polymers,are first compared and analyzed in this paper.Fluorine-containing monomer with very low surface energy,average cost and good performances is finally selected as core material.After the core material is selected,micro-capsules are synthesized using two-step methods according to in-situ polymerization.In the process of the first step,pre-polymer is prepared through the reaction between urea and formaldehyde.In the second step,microcapsules are prepared using urea-formaldehyde pre-polymer as wall material and fluorine-containing monomer as core material.During the process of synthesis of urea-formaldehyde pre-polymer,optimum conditions for reactions are discussed and decided as follows:temperature:60℃;reaction time:40min～50min;pH=8～9,The pre-polymers prepared under this condition is a kind of transparent,clear and sticky liquid with good stability.During the process of synthesis of microcapsules,conditions for micro-capsule with the thinnest wall are explored.Temperature,reaction time,as well as emulsifier’s species and dosage are decided.The micro-capsules are well distributed and of complete shape,uniform sphere as well as the thinnest wall when mass ratio between core material and wall material is(1.5:1.0).Urea-formaldehyde resin microcapsules with the thinnest wall are added to the fluorocarbon coatings.Different ratios of micro-capsules’ influences on coatings’ contact angle,glossiness and cleaning rate are discussed.The results show that:The water contact angle of coatings can reach the maximum of 105°when the ratio of micro-capsule is 40%;The glossiness of coating is falling with the constant addition of micro-capsule;The cleaning rate of coating can reach the highest level when the ratio of micro-capsule is 36%.Due to that water contact angle and cleaning rate are the direct reflect of coatings’ surface energy,films with low surface energy can be produced by adding micro-capsules.