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Dioctyl phthalate (Dioctyl Phthalate, referred to as DOP) is a widely used plasticizer, mainly used in PVC and other plastic products. The following is a manufacturing method of dioctyl phthalate, which uses phthalic anhydride and octanol as raw materials and undergoes an esterification reaction to obtain a product.
1. raw material preparation
1. Phthalic anhydride: Phthalic anhydride is one of the main raw materials of dioctyl phthalate. It should be white or slightly yellow crystalline powder with a content of more than 99%.
2. Octanol: Octanol is another raw material of dioctyl phthalate. It should be a colorless transparent liquid with a content of more than 99%.
2. Esterification Reaction
adding phthalic anhydride and octanol into an esterification reactor according to a certain molar ratio, generally the molar ratio of phthalic anhydride to octanol is 1:2.1-2.2. The temperature was heated to 180 to 200 ° C., and the esterification reaction was carried out under stirring. Water and by-products will be produced during the reaction and need to be discharged in time.
3. Dehydration Operation
When the esterification reaction proceeds to a certain extent, it is necessary to perform a dehydration operation to remove moisture in the system. Generally, the method of vacuum distillation is used to evaporate the water and some low boiling point by-products in the system.
4. esterification is completed
dehydration operation is completed, continue to heat up to 220~240 DEG C, and maintain a certain period of time, so that the esterification reaction is complete. At the same time, vacuum distillation is also required at this stage to further remove moisture and by-products in the system.
5. cooling crystallization
After the esterification is completed, the reaction system is cooled to room temperature, and crystals precipitate. At this time, a filtration operation is required to separate the crystals from the mother liquor.
6. Washing and Drying
, the crystals obtained by filtration are washed with an organic solvent such as ethanol to remove impurities attached to the surface. After washing, the crystals were dried to constant weight by vacuum drying.
7. Product Packaging and Storage
The dried dioctyl phthalate is packaged, usually in cardboard drums or iron drums lined with plastic bags. After the packaging is completed, it should be stored in a dry, cool and ventilated place, avoiding direct sunlight and high temperature.
The above is a manufacturing method of dioctyl phthalate. It is necessary to pay attention to safety during the specific operation to avoid accidents such as fire and explosion. At the same time, quality inspection and control of raw materials, intermediates and products are also required in the production process to ensure product quality and stability.