Main applications of trimellitic anhydride_Kain Industrial Additives

Background and overview^[1]

White powder or flakes. Melting point 168℃. Soluble in water and general organic solvents such as ethanol and acetone. Pseudocumene (the main component is 1,2,4-trimethylbenzene) in the C9 fraction of aromatic hydrocarbons in coal tar fractions, cracked gasoline, catalytically reformed gasoline, etc. can be processed through liquid phase nitric acid oxidation and air using a cobalt or manganese catalyst. In the oxidation method, benzenetricarboxylic acid is first produced and then dehydrated. Trimellitic anhydride is mainly used in the production of plasticizers for PVC resins, polyimide resin paints, water-soluble alkyd resins, epoxy resin curing agents, impregnating agents for low-voltage and pulse power vessels, film films, water treatment agents, and surfactants. wait. In recent years, due to the popular market, domestic and foreign manufacturers have developed and produced this product to meet the demand. In recent years, with the continuous development of my country’s petroleum industry, the output of heavy aromatics and cracked gasoline from reforming units has continued to increase. The total output of reformed C9 aromatics can reach nearly 400kt per year, and trimethylbenzene accounts for about 35% of C9 aromatics. ~40%, which is the key to comprehensive utilization of heavy aromatics. Therefore, using trimellitic anhydride to produce trimellitic anhydride can not only make full use of my country’s abundant heavy aromatic hydrocarbon resources, but also greatly alleviate the tight supply of trimellitic anhydride in my country and promote the development of my country’s chemical industry.

Apply^[2]

Trimellitic anhydride is an important organic chemical raw material for modern new materials. It has high reactivity and can be used to produce a series of fine chemicals with high added value. It is mainly used in high-quality plasticizers, high-temperature resistant insulating paint, and advanced coatings. , engineering plastics and other industries. Because the resin materials prepared with it have excellent electrical insulation, high temperature resistance and mechanical properties, they are also widely used in electromechanical, electronic and aerospace fields.

1. Plasticizers my country’s wire and cable industry is in line with international standards, and there is an urgent need for high-performance plasticizers to meet the requirements for the production of 90°C, 105°C, and 125°C heat-resistant cables and high-voltage cable plastic sheaths. , traditional plasticizers diisooctyl phthalate (DOP) and dibutyl phthalate (DBP) cannot meet the above requirements due to their high volatility, low flash point and small volume resistivity. The esterification reaction of trimellitic anhydride and 2-ethylhexanol is used to produce triisooctyl trimellitate (TOTM) plasticizer, which has the advantages of heat resistance, low volatility and high electrical properties. The chemical reaction formula is as follows:

TOTM, as a plasticizer, has many advantages such as large relative molecular weight, good fluidity, high flash point, low volatility, resistance to extraction by various solvents, and low migration resistance. In addition, benzene polyacid plasticizers have good compatibility with polymer materials, especially PVC materials, in polymer processing, and their processability, low-temperature performance and other characteristics are similar to those of monomeric phthalate esters, so they are compatible with It has the advantages of both monomer plasticizers and polyester plasticizers. It can not only be used as a general main plasticizer in civilian products, but also can be more widely used as 105℃, 125℃ grade cable materials, automobile decoration Materials, advanced spinning oils, impregnated oil for pulse low-voltage power capacitors, electronic chemicals and high-tech military products.

2. Coatings and epoxy resin curing agents

The coating industry is developing in the direction of non-toxic and flame retardant. Using water-soluble resin coatings, such as the reaction of trimellitic anhydride with glycol monoglycerides, hexylene glycol, propylene glycol, neopentyl glycol and other glycols, a new type of water-soluble alkyd resin coating can be obtained, which can be used in automobiles, refrigerators, Electrocoat primer for washing machines. Trimellitic anhydride can cure epoxy resin in a short time and has excellent physical and chemical properties. It is an ideal epoxy resin curing agent. Triphtalate can also be used as a curing agent. For example, trimellitic anhydride reacts with ethylene glycol diacetate to produce ethylene glycol bis(trimellitic acid) ester. This compound reacts with epoxy resin to form heat-resistant trimellitic anhydride. Good adhesives and coatings. The solid resin obtained by the equimolar reaction of trimellitic anhydride and glycerol is dissolved in the solvent and has good adhesion to glass, aluminum, etc.

3. Polymer materials and surfactants

General Electric Company of the United States uses trimellitic anhydride as raw material to prepare a co-condensation polymer of butanediol, polyoxypropylenediamine and trimellitic anhydride, and then combines the co-condensation product with polydimethyl terephthalate at 250°C. The esters are heated together to obtain a block polymer rubber that has good flexibility, aging resistance and light resistance. Trimellitic anhydride and higher fatty alcohols such as lauryl alcohol and stearyl alcohol are used to control the molar ratio for mono- and double-esterification reactions, and then the free carboxyl groups on trimellitic anhydride are neutralized with NaOH to prepare the sodium salt anion of diphenyl ester with excellent surface activity. Surfactant.

4. Insulating paint

Polyamide-imide resin made by the reaction of trimellitic anhydride and benzene aromatic diamines and polyamide-imide resin made by the reaction of trimellitic anhydride and 4,4-arylaminodiphenyl ether have good resistance to Thermal properties (can be used for a long time above 200℃), wear resistance, damage resistance, electrical insulation resistance (breakdown voltage can reach 11.5kV) and mechanical properties, can be used as laminated resin for impregnating glass cloth, resistance to Electrical equipment materials such as high-temperature covering materials, wire insulation paint, and slot insulators for motors. Used as F-class and H-class resistant insulation materials required for electrodes, household appliances and power tools, as enameled wire varnish, impregnating varnish, silicon steel sheet varnish and films, etc. Prepared by the reaction of trimellitic anhydride and N, N-diphenyl aromatic diamineFinally, it enters the dehydration reactor. The filtrate is mainly an acetic acid aqueous solution containing a considerable amount of catalyst. After the acetic acid is recovered through distillation, the catalyst in the residue is extracted and recovered.

3) Dehydration, distillation and tableting: Dehydration conditions are 220~230℃ and 39.96kPa. The dehydrated crude anhydride is evaporated and refined using a thin film evaporator at 239°C and 1.33kPa, and is flaked into trimellitic anhydride in a flaking device. The crude acetic acid evaporated from each part or the acetic acid water absorbed by water can be recovered and recycled through distillation.

Main reference materials

[1] Dictionary of Chemical Substances

[2] Trimellitic anhydride production technology and application

[3] Production, application and market prospects of trimellitic anhydride