Methyltetrahydrophthalic anhydride (MTHPA) is a light yellow transparent thick liquid. It is a key chemical intermediate for electronic information technology raw materials, pharmaceuticals, epoxy resins, and national defense technology. It can also be used in manufacturing industries such as architectural coatings and fertilizers.

Methyltetrahydrophthalic anhydride is mainly prepared by Diels-Alder reaction of mixed C5 and maleic anhydride. The main components of mixed C5 are piperylene and isoprene (about 50% by mass), pentene-1, pentene-2, n-pentane, and isopentane. The main reactions of mixing C5 and maleic anhydride are the reaction of piperylene and maleic anhydride and the reaction of isoprene and maleic anhydride.

Domestic production of methyltetrahydrophthalic anhydride adopts a batch production process, which has many shortcomings, such as time-consuming and labor-intensive operation, instability of the system, and slower reaction when the concentration of reactants in the later stage of the reaction decreases, thereby increasing the reaction time. Different batches of products have differences, for example, insufficient production capacity. In recent years, with the continuous improvement of insulation performance and reliability requirements in the electrical, electronic, and electrical industries, the application has developed rapidly, and the market demand is increasing. The inadequacy of intermittent production technology lies in this background is obvious.

Methyltetrahydrophthalic anhydride is an important intermediate in electronic information materials, medicines, pesticides, resins, and defense industries. It has the characteristics of low melting point, low toxicity, low volatility, etc., is convenient to use, has high reactivity with epoxy resin and good miscibility. The epoxy resin cured product using this curing agent has excellent electrical insulation and mechanical properties.

Using methyltetrahydrophthalic anhydride production waste liquid to prepare C5 petroleum resin, including (1) Separating and removing the colloidal cis-piperylene material A from methyltetrahydrophthalic anhydride production waste liquid, and separating the C5 fraction by cracking Removal of dicyclopentadiene to obtain decyclic C5 material B; (2) Feed materials A and B at a weight ratio of 1:0.1-5, catalyzed by aluminum trichloride catalyst, in a batch mode in C5 light oil solvent Cationic polymerization reaction; (3) After the polymerization reaction, the catalyst is removed by three-stage continuous water washing to obtain C5 petroleum resin. The C5 petroleum resin paint prepared by the invention has light color, high softening point, stable quality index, and is specially used for road marking. The method uses methyltetrahydrophthalic anhydride production waste liquid, improves the utilization value of waste liquid, and adopts continuous water washing The process is automated, which improves the washing efficiency and reduces the loss of water and materials.