The m-benzene type unsaturated polyester resin is one of the main varieties of corrosion-resistant unsaturated polyester resin, and is a relatively common medium corrosion-resistant resin because of its ease of manufacture, low cost, resistance to weak acid and various solvents. The basic raw materials of the isophthalic unsaturated polyester resin are isophthalic acid, maleic anhydride, and propylene glycol. The change of the ratio of the three raw materials has a certain change in corrosion resistance, and the use of neopentyl alcohol instead of propylene glycol has Better weatherability and water resistance.
The main chain of the m-phenylene unsaturated polyester resin is separated by two ester groups, has small spatial effect, and has excellent physical and chemical properties. They are high strength, good toughness, water resistant, weather resistant and corrosion resistant. They are commonly used in high performance FRP/composites. At present, in the international market, isophthalic unsaturated polyester resin has become a general-purpose resin, such as American EASTMAN, REICHOLD, British SCOT BADER, Dutch DSM, and Japan Catalyst, which have produced isophthalic polyester. It accounts for 1/4 of the total amount of polyester. Nanjing Insulation Materials Factory introduced resin grades from the United States, among which the chemically resistant polyester grades accounted for 80% of the benzene type, and the gel coat resin, the meta-benzene type accounted for 50%.
The unsaturated polyester resin produced by various manufacturers in China is mainly o-phenyl type polyester, and the amount of meta-benzene is less. One of the reasons is that the synthesis time of the meta-benzene type polyester is long, and the raw material isophthalic acid contains a certain amount of terephthalic acid, and the terephthalic acid is extremely difficult to react under the condition of no catalyst. Tang Siding et al. Synthesize an iso-benzene type unsaturated polyester resin in a short time by using an organic metal salt mixed with an organometallic compound catalyst. The resin has good boiling water resistance, chemical resistance and physical and mechanical properties.
The isophthalic unsaturated polyester resin is widely used in ships, sanitary ware, urban water supply facilities and sewage treatment equipment. In some special industries, the application of benzoic unsaturated polyester resin is also under study.