Diisononyl phthalate (DINP) is a widely used plasticizer, mainly used in polyvinyl chloride (PVC) plastic products to increase their flexibility. The following is the manufacturing method of diisononyl phthalate:
**Raw materials**
1. Phthalic anhydride (PA): this is the main raw material of DINP, which is usually produced by the reaction of benzene, coke and air.
2. Isononanol (INA): This is a primary alcohol with nine carbon atoms, usually made by tetramerization of propylene.
**Manufacturing Steps**
1. Esterification: Phthalic anhydride is esterified with isononanol in the presence of a catalyst. Commonly used catalysts are sulfuric acid, phosphoric acid or p-toluenesulfonic acid. The reaction is usually carried out at atmospheric pressure or under slight pressure, and the reaction temperature is usually between 180-220°C. The reaction is carried out at atmospheric pressure or under slight pressure. The reaction produces diisononyl phthalate and water.
2. Dehydration: The water produced by the esterification reaction needs to be removed by distillation to facilitate the reaction. This step usually needs to be done under vacuum to lower the boiling point of the water.
3. Purification: Unreacted raw materials, by-products, and impurities are removed from the product by distillation or rectification to obtain pure diisononyl phthalate.
4. Cooling and Packaging: The pure Diisononyl Phthalate is cooled to room temperature and then packaged.
**Precautions**
1. During the whole manufacturing process, the reaction temperature and pressure need to be strictly controlled to ensure the smooth progress of the reaction.
2. The selection and dosage of catalyst have a great influence on the reaction and need to be optimized according to the actual situation.
3. In the dehydration process, care needs to be taken to avoid decomposition and side reactions at high temperatures.
4. In the purification process, it is necessary to ensure that the purity of the product meets the requirements.
In general, the manufacturing process of diisononyl phthalate involves several steps such as chemical reaction, substance separation and purification, and requires precise control of each parameter to ensure the quality and yield of the product. At the same time, factors such as environmental protection and safe production need to be taken into account, as the disposal of chemical substances and the discharge of waste are involved.
