Synthesis, Properties Of The Water-Based Silicone Rubber And Use Thereof

With excellent performances silicone rubber has been widely used in various aspects. Silicone rubber usually requires the large amounts of organic solvents during the process of synthesis and use, which will harm people and the environment. The solvent of water-based silicone rubber is water instead of organic solvents dispersing silicone rubber particles. When the water evaporates, particles irreversibly coalesce, finally forming the silicone rubber elastomer. Water-based silicone rubber making up for the shortcomings of traditional solvent-based silicone rubber will be more convenient and environmentally friendly. With the implementation of water-based technology development and environmental regulations, the research and application of water-based silicone rubber has enormous potential.The first part of this paper studied the emulsion polymerization of hydroxyl-terminated polysiloxane, that is, octamethyl cyclotetrasiloxane(D4) polymerizes into polysiloxane emulsion by means of ring-expansion under emulsion and acid conditions. Emulsifiers are the mixture of sodium dodecylbenzenesulfonate (SDBS) and AEO-3, and the catalyst is dodecylbenzene sulfonic acid. The hydroxyl-terminated polysiloxane emulsion as the gum base of water-based silicone rubber can provide the reactive group for cross-linking reaction. Researching the effects of various synthesis conditions on the properties of the emulsion get the optimum synthetic methods. When the ratio of SDBS and AEO-3is1:4, the dosage of the emulsifier and catalyst DBSA respectively reach3weight percent and5weight percent of D4, and the emulsion polymerization react4hours at85℃, the latex has the pan-blue light and good stability, and particle size can reach105.6nm, the conversion rate can reach88.7%.The second part of this paper studied the synthesis and film-forming properties of water-based silicone rubber. Vinyl triethoxy siloxane as the crosslinker of water-based silicone rubber has three reactive groups when the ethoxy hydrolyze andturn into hydroxyl. As the catalyst of the crosslinking reaction dibutyl tin dilaurate can catalyze the dehydration condensation reaction of the silanols of the crosslinker and hydroxyl-terminated polysiloxane, so that linear polysiloxane cross-link into a three-dimensional network structure. Ludox which has a good compatibility with the emulsion be selected as reinforcing agent to increase the strength of rubber. After several components of silicone rubber are mixed, placed into the teflon mold and dried at a predetermined temperature and time, silicone rubber film formed. The dosage of different components can affect the performance of silicone rubber film. With the amount of crosslinker and ludox increasing, the strength and elongation of film gradually increase, but more than a certain amount they began to drop because of the excessive cross-linking. The best amount of the crosslinker and ludox respectively are12.5weight percent and25weight percent of hydroxy-terminated silicone emulsion. This paper found the catalyst has no effect on the mechanical properties of silicone rubber film, because the catalyst can reduces the response time and don’t change the internal structure of the film. For ease of application, the amount of catalyst is selected as0.067weight percent. The silicone rubber latex is placed at room temperature for a period of time, when the latex become viscous, baking latex and forming silicone rubber film, and the formed film have the similar mechanical properties with the and the film that not be dried at high temperature only placed at room temperature for seven days. The result shows that the silicone rubber latex has completed the cross-linking reaction and the the internal structure of film have been stabilized when the silicone rubber latex become enough viscous, and barking don’t affect the performance of the film and only accelerate the evaporation of water. The amount of catalyst selected as0.067%, the water-based silicone latex placed at room temperature about30min can be dried to achieve optimum film performance.As viscous water-based silicone latex can become thin film after coating and barking, the third part of this paper researched its impact on the performance of the fabric when water-based silicone rubber use as the coating finishing agent of the fabric. The drying coated polyester fabric can be wetted with water quickly because of a large number of emulsifier. With the increase in the number of water washing, the water contact angle increases, and after washing10times a water contact angle can reach132°, showing the original water repellency of silicone rubber. By comparing the impact of different baking temperatures and different curing time on the tear strength and water contact angle of the coated fabric after washed10times, the best curing conditions were160℃baking3min. In addition, finishing polyester fabric can maintain good water vapor permeability, anti-adhesive and a soft feeling.