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The unsaturated polyester resin refers to a polyester polymer having an unsaturated bond (e.g., a double bond) in a molecular chain. An unsaturated dibasic acid (or anhydride), a saturated dibasic acid (or anhydride), and a diol (or polyol) are subjected to polycondensation under certain conditions to form an unsaturated polyester, and the unsaturated polyester is dissolved in a certain amount. In the crosslinking monomer (such as styrene), the liquid resin is formed into an unsaturated polyester resin. The unsaturated polyester resin is added to the initiation system and can react to form a three-dimensional network structure of insoluble and infusible polymer material, so it is a typical thermosetting resin. According to experts, unsaturated polyester resins have unique advantages over many other thermosetting resins. The unsaturated polyester resin has good processing characteristics and can be solidified at room temperature (not less than 15 to 20 ° C) under normal pressure without releasing any by-products. Moreover, the viscosity of the resin is suitable, and various processing methods such as hand lay-up, spray forming, pultrusion, injection molding, and winding forming can be employed. Unsaturated polyester resins are known in the industry as contact molding, or low pressure molding thermosetting resins. The properties of the commonly used thermosetting resin after curing show that the cured thermosetting resin has a low comprehensive performance, so it is usually prepared by using fibers or fillers to form a composite material, and the performance is improved to meet the use requirements. For example, glass fiber reinforced thermosetting resin has many excellent properties such as light weight, high strength, electric edge, corrosion resistance and microwave penetration; polymer concrete has the advantages of high early strength, high compressive strength and good impermeability. The method of material compounding can make the polyester resin exert its excellent characteristics and make up for its lack of specific modulus. Unsaturated polyester resin has been widely used in glass fiber reinforced materials (ie, FRP), casted products, wood coatings, sanitary wares and handicrafts, etc. in construction, chemical anti-corrosion, transportation, shipbuilding industry, electrical industry materials, entertainment tools. , craft sculptures, cultural and sports supplies, aerospace tools and other industries have played their due role.
Initiator effect
B-UPR was added with 1 wt% benzoin ethyl ether and 1 wt%/1 wt% benzophenone/triethylamine for ultraviolet light irradiation. The results were as follows: the resin added with benzoin ethyl ether was gelled for 1 min, and added to the second. The benzophenone/triethylamine resin was not gelled after 20 min of illumination. According to experts, benzoin-based initiators can directly initiate the polymerization of monomers through photochemical reactions. The benzophenones and triethylamines generate effective free radicals through the hydrogen abstraction reaction in the excited state. It has been reported that styrene can degrade the excited state of the ketone and the efficiency of the initiator is greatly reduced. Therefore, such a styrene-containing resin does not work well with a benzophenone/triethylamine initiator. The benzoin ether has a short excited life and is not easily quenched by styrene, so it can be used for the polymerization of styrene-containing resins.
The benzoin ethyl ether was added to the B-UPR in an amount of 2.0%, 1.5%, 1.0%, 0.8%, and 0.5%, respectively. According to experts, the film was coated on glass slides and irradiated with ultraviolet light for 1 h. The results showed that (Table 1) the addition of benzoin ethyl ether was 1.0% to 1.5%.