The Synthesis Of Styrene-acrylic Emulsion With Organosilico Ne Modification And Its Applications In Gypsum Waterproof

The gypsum resource in our country is abundant, low cost, and gypsum products have a lot of advantages. Especially, gypsum thermal insulation materials attracted wide attention in construction industry for its merits of light weight, thermal insulation, heat and sound insulation, seismic and recycling. However, the utilization of gypsum resource is very low. Most of gypsum resource can only be converted into low value-added products, like gypsum block and cement retarder. It leaded to the waste of resource and the secondary environmental pollution. The application of gypsum products, particularly gypsum thermal insulation materials, is limited greatly, because of poor water resistance and low strength. In this thesis, according to these disadvantages of gypsum, organic silicon modified styrene acrylic emulsion was synthesized and applied to gypsum products. A gypsum thermal insulation materials that can be used in exterior walls and in damp environment were attempted to be developed.This article is based on gypsum heat preservation material of poor water resistance and the defect of low intensity, the design chain, organic silicon modified styrene acrylic emulsion was synthesized, and its application to the plaster on the thermal insulation material, looking forward to resolve the bubble gypsum heat preservation material cannot be used in the exterior walls and damp environment problems.Firstly, we synthesized organic silicon modified styrene acrylic emulsion, and infrared radiation (IR) testing showed the organic silicon took part in the polymerization reaction successfully. In addition, we also studied the influence of polymerization methods, the dosage of monomer, reaction temperature, emulsifier and the ratio of soft monomer and hard monomer on the properties of emulsion. The formula and technological conditions of the silicone modified styrene acrylic emulsion were finally determined:the dosage of organic silicon is3.5%, the polymerization method is prepolymerization, reaction temperature is80-85℃, composite emulsifier (m (OP-10)/m (SDS)) is4/1～3/1and its content is4%, soft and hard segment monomer’s ratio (BA/St) is1/1. Compared with ordinary styrene acrylic emulsion, the calcium ion stability, dilution stability, freeze-thaw stability, thermal stability and other performance of the organic silicone modified styrene acrylic emulsion were improved greatly, and the water absorption of coating reduced significantly. The organic silicone modified styrene acrylic emulsion can be used as the high-grade architectural coatings of external walls.We also used the Alpha high-strength gypsum, foaming agent and organic silicone modified acrylic emulsion as raw materials, and prepared foam waterproof gypsum board sample.Furthermore, we investigated the effect of the content of organic silicone modified styrene acrylic emulsion and drying temperature on the strength, unit weight and water resistance of the insulation gypsum board. When the adding amount of the waterproof agent of organic silicone modified acrylic emulsion is5.5%and the drying temperature is55℃, we can obtain the tight dihydrate gypsum crystal from the hydrolysis of alpha half water gypsum. And the surface hydrophobic organic film make the water absorption in24h of plasterboard reduce to3.1%and the intensity of plasterboard enhance to4.2MPa. This kind of foam gypsum is lightweight, insulated, waterproof and stiff and can be applied to building exterior wall and humid environment. Besides, we further explained the waterproof and enhanced mechanism of foamed plaster from the point of the crystal morphology and contact angle of gypsum sample.