Unsaturated polyester resin is a kind of chemical raw material. It is often used to thicken and solidify the surface of an object. When it is used, it is like painting, layer by layer, and the curing process releases harmful gases such as styrene.
Unsaturated polyester resin is one of the most commonly used thermosetting resins. It is a linear polymer formed by polycondensation of saturated dibasic acid, unsaturated dibasic acid and diol, which is diluted by crosslinking monomer or active solvent. The resin solution with a certain viscosity, referred to as UP.
Unsaturated polyester resin composition
Raw material name quality (%)
Propylene glycol: 167.40
Maleic anhydride: 98.60
Phthalic anhydride: 148.11
Theoretical water output: 36.04
Polyester output: 377.53
It can be seen from the table. The total molar ratio of diol to dibasic acid is 2.2:2.0, and the diol excess is 10%, which is necessary to control the relative molecular mass of the polyester.
Preparation of unsaturated polyester resin: Add diol, dibasic acid, and hydroquinone into the reaction kettle according to a certain formula, heat up with nitrogen and start stirring after the materials are melted, reflux for 1 h, and then heat up to 190 ℃ for esterification When the acid value is less than 40 mgKOH/g, the temperature is lowered to 60 ℃, and TDI is added dropwise at a constant rate within 1 h. After the temperature does not rise, the reaction is maintained at about 75 ℃. Measure the -NCO value after 1 h. When the -NCO value reaches the specified value, add styrene to dilute to obtain a polyurethane-modified unsaturated polyester resin with a solid content of 75%.