Dioctyl Phthalate (DOP) is a widely used plasticizer, mainly used in plastic products such as polyvinyl chloride. 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 the product.
I. Preparation of raw materials
1. Phthalic anhydride: Phthalic anhydride is one of the main raw materials of dioctyl phthalate, it should be white or slightly yellow crystalline powder, the content is above 99%.
2. Octanol: octanol is another raw material of dioctyl phthalate, it should be colorless transparent liquid, the content is above 99%.
2. Esterification reaction
Phthalic anhydride and octanol are added into the esterification reactor according to a certain molar ratio, generally the molar ratio of phthalic anhydride to octanol is 1:2.1~2.2. Heating is increased to 180~200℃, and the esterification reaction is carried out under stirring condition. Water and by-products will be produced during the reaction, which need to be discharged in time.
Three, dehydration operation
When the esterification reaction is carried out to a certain extent, dehydration operation is needed to remove the water in the system. Generally the method of vacuum distillation is used to vaporize the water in the system and some by-products with low boiling point.
Four, esterification is completed
After the dehydration operation is completed, continue to heat up the temperature to 220~240 ℃ and keep it for 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 water and by-products from the system.
V. Cooling and crystallization
After the esterification is completed, the reaction system is cooled to room temperature, and crystals will be precipitated. At this time, filtration is required to separate the crystals from the mother liquor. Washing and drying
The crystals obtained by filtration are washed with organic solvents such as ethanol to remove the impurities adhering to the surface. After washing, the crystals are dried to constant weight by vacuum drying.
VII. Product packaging and storage
The dried dioctyl phthalate is packed, usually in cardboard drums or iron drums lined with plastic bags. After packing, it should be stored in dry, cool and ventilated place, avoiding direct sunlight and high temperature.
Above is a manufacturing method of dioctyl phthalate, the specific operation process needs to pay attention to safety, to avoid fire and explosion and other accidents. Meanwhile, quality inspection and control of raw materials, intermediates and products are also needed during the manufacturing process to ensure the quality and stability of the products.
