The history of emulsion polymerization has been more than 80 years. At present, in addition to conventional emulsion polymerization, there are seed emulsion polymerization, core-shell emulsion polymerization, soap-free emulsion polymerization, microemulsion polymerization, supermicroemulsion polymerization, inverse emulsion polymerization, reverse microemulsion polymerization, ultra-concentration emulsion polymerization, dispersion Aggregation and other technologies. The application of emulsion polymerization has been very extensive. It is mainly divided into three aspects: one is the separation of colloidal or powdery solid products after polymerization, the second is emulsion coatings and adhesives, and the third is the use of microparticles as pigments, particle standards, and immunological reagents. Carriers, etc. Among them, emulsion paint has become one of the most important components of emulsion products. Acrylic polymers have become outstanding in many polymer emulsion products due to their excellent film formation, good oil and weather resistance, and excellent adhesion. The introduction of hard monomer styrene acrylic emulsion system, referred to as styrene-acrylic emulsion for short, has high weatherability, color retention, stain resistance, etc. The cost is lower than that of pure acrylic emulsion, so it becomes the most common and common The variety of emulsions. Styrene-acrylic emulsions are mainly used as adhesives. As an adhesive, it has high hardness and good water resistance. In addition, it can also be widely used as exterior wall, interior wall paint, floor polish, color sand paint, concave and convex primer, real stone paint and so on. China began to develop styrene-acrylic emulsion systems in the 1970s and was formally put into use in the 1980s. With the research progress of core-shell technology, interpenetrating polymer networks and soap-free emulsion polymerization, a series of achievements have been made in the research of styrene-acrylic emulsions. Environment and health are one of the most important themes of humanity in the 21st century. In order to create a clean and comfortable living environment and a sustainable economic environment, the control of pollution in various countries has been gradually tightened. Solvent-based paints are prone to contamination of the air due to the inevitable volatility of solvents, making their application increasingly limited, which in turn has led to major changes in the variety of structures in the coatings sector. The water-based paint is non-polluting, and the production process and equipment are similar to the traditional solvent-based paint. In addition, the water-based paint also has advantages such as electrophoretic coating and high reactivity, thus becoming the fastest-growing paint variety in developed countries. The key technology of emulsion paints to replace solvent-based paints is the challenge of coating film hardness and weatherability, which is a difficult target for ordinary emulsion products. Scientific and technical workers in this field have conducted more in-depth and extensive research and achieved breakthroughs. Among them, representative systems include room-temperature crosslinking curing emulsion system, double-crosslinked core-shell structure emulsion system, and nanoparticle/polymer composite emulsion system. The development of cross-linking technology at room temperature has brought new life to the development of emulsion coatings. Compared with the cross-linking reaction at higher temperature, the cross-linked emulsion system at room temperature has obvious advantages. The film-forming material not only has a stable cross-linked structure, but also has good water resistance, acid and alkali resistance, anti-pollution and excellent mechanical properties, and does not require heating during construction, saves energy, and greatly expands its application range. The disadvantage is that the functional monomer is more expensive and its cost is higher than that of a conventional emulsion paint. For this reason, the research of silicone-modified acrylic polymers has become a hot topic. Silicone is mainly a synthetic polymer material composed of alternating silicon atoms and oxygen atoms. It also has mechanical and inorganic properties. It has excellent resistance to high and low temperature, ultraviolet and infrared radiation resistance, resistance to oxidation degradation, and electrical insulation and elasticity. . They can be low or high viscosity liquids, solid resins or rubber bodies. With the continuous research, development and improvement of new coatings, silicones have been widely used and developed as weather-resistant coatings, heat-resistant coatings, heat-resistant electrical insulating coatings, waterborne coatings, and barrier coatings and as coating additives. There are two methods of physical modification: physical blending and chemical modification. Chemically modified products are better than pure physical blending. The chemical modification mainly introduces active functional groups on the ends or side groups of the silicone flexible siloxane chain, and combines with other polymers to form block, graft or interpenetrating network copolymers. The double cross-linked core-shell structure emulsion system is a novel core-shell structure product with micro-cross-linked core bodies and room-temperature diplomatic links. By adjusting the degree of micro-crosslinking of the core body and the ratio of core to shell size, the characteristics of the compositional structure are changed, and the product performance is further improved, especially the hardness of the coating film. It has laid a more solid theoretical and applied basis for the development of a series of excellent emulsion coating products. Nano-polymer composite materials are a very new area of ​​rapid development in polymer materials science in recent years, and are one of the important technologies for obtaining high-performance composite materials. The nanoparticle/polymer composite emulsion system is also a hot research field in the new emulsion system. The new composite emulsion system can perfectly combine the rigidity, dimensional stability and thermal stability of inorganic materials with the toughness of polymer materials, and lays a foundation for the preparation of various functional new coating products such as flame retardant, weather resistance and radiation protection. And the application foundation opens up a new era of composite emulsion products. The technical difficulty faced by the nanoparticle/polymer composite emulsion system is how to ensure that the inorganic particles are dispersed in the polymer in nanometer size. At present, the preparation method of nanoparticle/polymer composite emulsion system is mainly based on existing nanopowders as raw materials, and true nanoparticle monodispersity has not yet been realized. Tsinghua University has chosen a brand-new process and ideas for chemical modification of its surface in the preparation of inorganic particles, taking the molecular design ideas as a starting point and incorporating inorganic nanoparticles, surface chemical modifiers and polymer monomers in the preparation process. By combining organically, from the preparation of inorganic dispersed particles, to the chemical modification of the surface of the nanoparticles, to in-situ polymerization, forming a composite material, an inorganic nano-dispersed particle that is truly required for a polymer composite material can be effectively produced. Avoid problems in the collection and storage of nanoparticles. In the preparation process of nanoparticles, the surface conditions of fresh particles are increased by controlling the reaction conditions so as to facilitate the chemical modification of the surface, which lays a material basis for the effective binding between the nanoparticles and the organic phase. The study has now achieved preliminary results and successfully synthesized a stable nano-magnesium hydroxide / styrene-acrylic polymer emulsion system. Compounding a small amount of nano-magnesium hydroxide, on the basis of keeping other properties basically unchanged, the calcium ion stability of the coating and the coating film hardness are greatly improved, which lays the foundation for improving the performance of the emulsion product and expanding its application fields. Excellent emulsion paint is an inevitable trend in the field of coatings.