In the preparation of silicone pressure-sensitive adhesives, we must first understand the relevant preparation mechanism. What is the preparation mechanism of silicone pressure-sensitive adhesives? Many people don't know very well. Next, the silicone pressure-sensitive adhesive manufacturers will introduce to you the knowledge about this, and let's take a look together.
Silicone pressure-sensitive adhesives are mainly made by mixing silicone rubber with incompletely miscible silicone resins, adding crosslinkers and other additives. Silicone rubber consists of one or more polydiorganosiloxanes, which are basically composed of hydroxyl or vinyl terminated R1R2SiO chains, and usually contain Me2SiO units, PhMeSiO units, and Ph2SiO units, or both units. The silicon-oxygen bond in the silicon rubber molecule is easy to rotate freely, and the molecular chain is easy to bend, forming a spiral structure with 6-8 silicon-oxygen bonds as repeating units [but the basic component of the silicone pressure-sensitive adhesive is a continuous phase It can form a film to provide strength and impart necessary cohesion to the pressure-sensitive adhesive. Silicone resin is a dispersed phase, used to improve the viscosity of the adhesive, as a tackifier and to adjust the physical properties of the pressure-sensitive adhesive. Silicone rubber and resin are connected by light-based condensation.
Silicone rubber, as the matrix component 4 of the silicone pressure-sensitive adhesive, is a linear polysiloxane in which silicon-oxygen atoms alternately form a main chain. The structure of the silicone rubber for pressure-sensitive adhesive is shown in Figure 1.1. At room temperature, it is generally a colorless and transparent extremely viscous liquid or semi-solid. The average molecular weight is between 15 and 500,000, and the bulk viscosity is about 10 * -10. 'Pas, the glass transition temperature Tg is about -120C.'
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