|
Molecular formula : C10H10O4
MW : 194.19
CAS No. :120-61-6
nature : rhomboidal colorless crystals. 140.6 ° C melting point, boiling point of 283 ° C, heated to 230 ° C or higher level, the relative density of liquid 1.084 (150 / 4 ° C), the refractive index of 1.4752, viscosity (150 ° C) 0.965mPa s, fire point of 155 ° C. Soluble in hot ethanol, methanol, ether, chloroform, do not dissolve in water.
Preparation : terephthalic acid esterification with methanol derived. The earliest use of sulfuric acid catalyst, the reaction temperature is 65-100 ° C, the reaction time was 10-16h. Using this method, methanol consumption, low productivity. Increased pressure, the 0.39 - 0.49MPa under esterification, the reaction time can be shortened to 1-2h, methanol loss than reducing atmospheric law. In recent years, high-temperature high-pressure liquid esterification, 250-300 ° C reaction temperature, pressure 2-2.5MPa, use tin, zinc, antimony compounds as catalysts, it is not necessary catalyst. To terephthalate yield of up to 96-98% or higher. Another DMT production methods through Granville Dayton-Hegelishi (Witten - Hercules) Act manufacture, or use of sub-xylene oxidation esterification of this Act in relation to the two methyl-p-xylene oxidation process, the first oxidation carboxyl methyl conducted, in order to avoid the next step occurred when oxidation reaction . To simplify the process, the two-step oxidation can be combined in an oxidation reaction was carried out by two steps are combined in esterification an esterification reactor for. Raw materials for the cycle xylene and methyl methacrylate acid in a tower reactor simultaneously oxidation reaction temperature of 140-170 ° C, pressure 0.4-0.7MPa, cobalt salt or cobalt, manganese salts as catalysts for oxidation with air to form methyl benzoate and right monomethyl phthalate. The resultant oxidative 200-280 ° C, 2-2.5 MPa and excessive alcohol esterification reactions. Esterification reactor from the top of distillate methanol, distilled recycled after use; Esterification reactor from the bottom of the rough ester, separated by distillation of benzoic acid methyl methacrylate (cycle of oxidation) and coarse DMT. The rough will be dissolved with dimethyl terephthalate methanol solution and then sent to mold crystalline precipitation, centrifugal separation, will be two of dimethyl terephthalate further purification distillation, that is, fiber-class products and the purity was 99.9%. The consumption of raw materials fixed : 630kg of p-xylene / t, 440kg methanol / t. The DMT of industrial production, the sub-xylene oxidation esterification method developed rapidly. This law during oxidation reaction when no solvents, is not required for reactor Titanium products easily purified, 1950 after he adopted in many countries. Xylene shortcoming is the total yield of low (87%).
purposes : DMT mainly used in the manufacture of polyester resin, thus creating a film and fiber, and high-intensity polyester insulation paint. Polyester film is mainly used for electrical insulation materials and film production (such as film as a film, X-ray film, photographic film and audio tapes, video tapes, computer tapes and other electronic substrate). Polyester resin most common use is to create fibers for fabrics, fishing nets, carpets, tire cord and so on. Also used in the production of plasticizer right DOTP.
Notice:Each item can have many explanations from different angels. If you want grasp the item comprehensively,please see below "more details data". |
Home Products Search Properties Search 中文版