Study On Preparation And Application In Coating Of Humidity-controlling Composite Material

Relative humidity is very important to human health, product manufacturing and goods conservations. A proper humidity controlling material according with environment protection can control the humidity of the air by its own characteristics without power consumption and machines. It could be made into coating for humidity control of building environment.A latex that had excellent waterproofness and adhesion was needed into hydrophilic humidity controlling coating, and silicone-acrylate copolymer latex would be proper for its high weather resistance, besmirchment resistance, air conductivity, rigidity, water resistance and adhesion.In this paper, that the preparation of a new humidity controlling composites and silicone-acrylate copolymer latex, and the application of their in humidity controlling coating were researched on the target of the humidity control in closed space.Firstly, poly(acrylamide/2-Acrylamido-2-Methylpropane Sulfonic Acid)-Montmorillonite (P(AM/AMPS)-MMT) humidity-controlling composites was synthesized by solution intercalation polymerization. Results of IR, XRD and SEM show that molecular chains of poly(AM/AMPS) have been intercalated into the galleries of MMT, and the composites have been exfoliated into nanocomposites which was best obvious when mP(AM/AMPS):mMMT = 10. TGA indicates that thermal stability of the composites is enhanced. The influence of temperature and humidity on composites'humidity controlling properties were studied, and the technological parameters based on the targets of the humidity controlling were as follows: reaction temperature 60℃, mP(AM/AMPS):mMMT=10, initiator based on monomer mass 0.5%.Secondly, silicone-acrylate copolymer latex was prepared by the seed semicontinuous emulsion polymerization with BA, MMA, HEMA, organosilicon KH-570. Optimized synthesis conditions of silicone-acrylate copolymer latex based on the targets of the emulsion polymerization stability and performance of the latex film were as follows:reaction temperature 80℃, agitation rate 190~200rpm, reaction system pH 6~7, by feeding manner of organosilicon monomer with acrylate monomer in reaction process. IR spectrum confirmed the copolymerization of silicone and acrylate. TGA confirmed the latex film had high thermal stability. The reaction system composing of mass ratio of MMA and BA 55:45, contents of initiator, emulsifier(mOP-10:mSDS=2), HEMA and silicon 0.4%, 4%, 4%, 12%(based on monomer mass) respectively,bad high polymerization stability and the latex film had excellent water resistance and adhesion.Thirdly, one kind of humidity controlling coating was developed with silicone-acrylate copolymer latex and humidity-controlling composite material synthesized in laboratory, pigments, aids, and so on. The coating'moisture adsorption and desorption performance were tested well when mpigments:mlatex 2.5:1 and humidity-controlling composites 17.6%(based on solid contents of coating). But its waterproofness and adhesion were worse than the silicone-acrylate copolymer latex film, which could be meliorated by the two-coating technics taking the latex film as the bottom coat.Finally, the humidity controlling coating can be used in closed space to achieve the humidity control of the environment. The results shew that the moisture is adsorbed from air during high humidity and desorbed from the coating during low humidity.