The commonly used silicone oil is polydimethylsiloxane and polymethylphenylsiloxane. Polydimethylsiloxane is used in coatings and inks. Although polymethylphenylsiloxane has good compatibility, it does not have the ability to control the surface state, so it is not used in leveling agent, and is mostly used in high temperature resistance. Although polydimethylsiloxane has a good surface state control ability, it has many disadvantages, such as poor compatibility, affecting the gloss of the coating, shrinkage cavity, interlayer adhesion and so on. Polydimethylsiloxane with different molecular weight has different compatibility and application. Compared with silicone oil, organic modified polydimethylsiloxane has obvious advantages. It not only retains the advantages of siloxane, but also overcomes its disadvantages by using the modifier, and plays many special functions. The key to the performance and application of modified siloxane is its molecular weight, type, category and position in the molecule. There are many ways to modify it. Polyether polyester modified organosiloxane belongs to comb like organopolysiloxane. N + m is about 50-250, and the molecular weight is controlled between 1000-150000. The compatibility is adjusted by polyether and polyester. The longer the chain, the better the compatibility. Polyether is the most modified one, usually ethylene oxide and propylene oxide. With the increase of ethoxyl content, its compatibility with water is also improved. Therefore, water-soluble siloxane leveling agent can be synthesized. Ethylene oxide and propylene oxide can be used alone or mixed to control hydrophilicity and lipophilicity. If it contains ethoxy and propoxy at the same time, it can be used as a leveling agent of siloxane for water and oil, for example, 1080 and 1090 series products of molyne chemical industry. The larger the molecular weight is, the stronger the surface state control ability is, and the better the skid and adhesion resistance are. For example, 1070 and 1071 series products of friction chemical industry. There are two ways to join the modified polyester or polyether with siloxane: one is the silicon oxygen bond; the other is the silicon carbon chain. Generally speaking, the thermal stability and water resistance of the former are not as good as those of the latter. The compatibility of polysiloxane modified by polyether and polyester with resin has been greatly improved, the surface tension has been reduced, the ability to control the surface flow, the skid resistance, the anti shrinkage cavity and the anti adhesion effect are also very good, and the interlayer adhesion of some products is also a problem. In particular, polyether modified polysiloxane has poor thermal stability and is easy to foam. Pay attention to the negative effects of these products when applying. As mentioned before, polysiloxane modified by polyether has some shortcomings, and polysiloxane modified by alkyl just has these advantages. This series of polysiloxane products also belong to comb structure. The molecular weight of this kind of products is relatively small, about 10000, N + m is about 30-50. The purpose of modification with alkyl is mainly to improve the thermal stability, compatibility and instability of foam, and even has the function of defoaming. However, with the increase of the modified alkyl chain, its ability to reduce the surface tension also decreased. The relationship between the length of alkyl chain and surface tension is shown in Table 1-1. The modified alkyl chain - CH3 - CH2 - CH3 - (CH2) 9 CH3 surface tension / (Mn / M) 20.6 26.231.4 generally, the carbon chain is controlled between c1-c14, so the molecular weight is not too large. Three modification methods of polydimethylsiloxane are introduced above. Different modification methods, different amount and structure of modifier, and different product performance. The heat resistance of leveling agent produced by three different modification methods are also different. The 1060 silicone modified polysiloxane of molecularly chemical industry has good heat resistance, which can be used in the temperature range of 200-220 ℃. In order to give the film a good smoothness, molenergy chemical has introduced some terminal modified organosilicon. Reactive leveling agent in radiation curing paint, ink system, there are substrate wetting, not smooth, easy to scratch, poor leveling defects. In view of these problems, monen chemical company has provided a series of reactive organic modified polysiloxane acrylic leveling agents, including 1073 and 1074 products of monen chemical. The former has good compatibility and poor smoothness. The latter has poor compatibility and good smoothness. It can be seen from the structural formula that the modified organic compound is acrylate, which is used to adjust its fluidity and compatibility. Its smoothness is determined by siloxane. The double bond of acrylic group can participate in the polymerization reaction of free radicals, forming a film firmly anchored on the surface of the film together with the resin. Resin based surface flow control agents are mostly linear resin polymers, mainly including acrylic resin, urea formaldehyde resin and melamine formaldehyde resin. In the general system, the compatibility of these resins is limited. They will accumulate on the surface to form a new resin film, which makes the surface tension of the film tend to balance, but they will not reduce the surface tension, so they do not affect the flow of the coating, which is often called flow accelerator. Acrylic resin is the main part of this kind of leveling agent. Acrylate leveling agent can not only promote the flow and leveling of the film, but also can not affect the adhesion between layers of the film, and also has the effect of defoaming. Leveling principle the compatibility of acrylate leveling agent is an important index of its ability to control the surface state of film. The compatibility is too good to form a new interface on the film surface and provide no leveling effect