Preparation Of Acrylate Emulsion Waterproof Agent Containing Fluorine And Silicone And Its Application In Gypsum Building Materials

For the problem that gypsum has poor waterproof performance while fluorosiliconepolymers have excellent hydrophobic property, an acrylate emulsion waterproof agentcontaining fluorine and silicone (SFA waterproof agent) with excellent hydrophobic property isprepared. Its effects on gypsum properties are inspected and combining with other gypsumwaterproof measures, its application effects in gypsum block, polyphenyl granule-foaminggypsum insulation materials are studied. The structure and performance of SFA waterproofagent, modified gypsum and gypsum building materials are analyzed by several modernmaterials testing means and the action mechanism is also researched.The effects of technique parameters including the synthetic methods, synthesistemperature, stirring rate, emulsifier types, emulsifier ratio and dosage, initiator dosage, heatpreservation reaction time on waterproof agent water resistance and stability are studied inthis paper. The results show that when the stirring rate is200-210rpm, heat preservationreaction time is120min, the amount of SDS, OP-10, PFOA and APS is1.2%,1.8%,1.0%and0.7%respectively, the stability, film forming characteristics and hydrophobicity of SFAwaterproof agent are good at reaction temperature of80℃by the method of gradient droppingemulsion polymerization with2.0%organ-silicon monomer,3.0%HFMA,6.0%DFHMA,5.7%BA,22.7%MMA,3.0%AA and52.9%water. FTIR analysis shows that theorgan-silicon and organ-fluorine monomers added are introduced into the molecular structureof SFA waterproof agent successfully. The results of particle size analysis indicate that theaverage particle diameter is96nm, and the SFA waterproof agent with narrow particle sizedistribution and a single dispersion belongs to the nanometer micro emulsion. Based on theSEM analysis, the latex particle morphology is more regular and round and particle sizedistribution is relatively uniform, which illustrate that the SFA waterproofing agent has goodfilm-forming ability. The water contact angle test result of the film is110.8°, indicating itsoptimum hydrophobic properties.The gypsum cementitious materials and its building materials products are modified bySFA waterproof agent. From the research, it knows that the gypsum samples strength are the highest and the water resistance is optimal with9%SFA waterproof agent. Compared with theblank samples, the2h,24h absorption rate decreases by60.8%and59.8%respectively whilethe24h flexural, compressive softening coefficient increases by50%and74.2%respectively.The micro pores are blocked by formed SFA waterproof agent film; meanwhile it can alsochange the inner surface of macro pores from hydrophilic to hydrophobic, thus changing thecontact angle between macro pores and water. The water molecules will come together toform droplets due to the large contact angle when gypsum absorbs water, and in this way thewater further infiltration is hampered and the water resistance is improved.The synergistic modification effects of SFA waterproof agent with fly ash activityadmixture on FGD gypsum block are studied, and the optimal amount of fly ash admixturedetermined is30%. Gypsum block water requirement of standard consistency is50%and theinitial, final setting time is8min and11.5min respectively under optimal comprehensiveeffect. Compared with the gypsum block only modified by9%SFA waterproof agent, the28dflexural, compressive strength of synergistic modification samples is increased by47.9%,30.1%with the24h compressive softening coefficient increasing by59.3%.Doping SFA waterproof agent and spraying methyl-sodium are used to modifypolyphenyl granule-foaming gypsum insulation materials water resistance. The experimentalresults show that the insulation material density is252kg/m3and the coefficient of thermalconductivity is0.045W/(m·k) under doping16%SFA waterproof agent, with the dry flexural,compressive strength being0.42MPa and0.51MPa. Compared with the unmodified samples,the2h,24h absorption rate decrease by44.2%,38.5%while the24h compressive softeningcoefficient increases by88%. Based on doping16%SFA waterproof agent, the2h,24habsorption rate of insulation material samples almost changes no longer after sprayingmethyl-sodium more than3times. Compared with the thermal insulation material onlymodified with16%SFA waterproof agent, the2h,24h absorption rate of the samples withspraying methyl-sodium3times decreases by19.5%,27.3%and the24h compressivesoftening coefficient increases by29.8%.