Polyimide PI machining part

Polyimide is the molecular structure contains an aromatic heterocyclic polymer compounds of imide-based chain links, the English name Polyimide (PI for short), can be divided into benzene-type PI, soluble PI, polyamide-imide (PAI) and polyetherimide (PEI) four categories.

 

PI is currently one of the best varieties of engineering plastics heat resistance, some varieties can withstand long-term 290 ℃ high temperature for a short period of time to withstand a high temperature of 490 ℃, but also very low temperature, such as in the -269 ℃ liquid helium will not be brittle. In addition, mechanical properties, fatigue resistance, flame retardant, dimensional stability, electrical properties are good, molding shrinkage is small, resistant to oil, general acids and organic solvents, not alkali, has excellent friction resistance, abrasion properties. And PI is non-toxic, can be used to manufacture tableware and medical equipment, and withstand thousands of times sterilization.

 

PI molding methods include compression molding, impregnation, injection molding, extrusion, die casting, coating, casting, laminating, foaming, and transfer molding.

 

History of Development

Polyimide (PI), first appeared in 1955 Edwards and Robison's patent, in 1961 DuPont produced poly(tetramethylene tetracarboxylic acid) imide film, and sold on the market under the trade name of Kapton. 1972 General Motors began research and development of polyetherimide (PEI) in the United States, and in 1982, 10,000 tons of production units were built under the trade name of Ultem. After that, Japan UBE Industries, Mitsui Chemical Company and some European countries have realized the commercial production of polyimide. So far, polyimide has more than 20 varieties, the United States, Europe and Japan, more than 40 manufacturers. South Korea, Malaysia, Russia and China have a small number of manufacturers in the production and application of polyimide. 2005, the global production capacity of 60,000 tons, of which, China accounted for about 5,000 tons. 

 

Application

PI has applications in aviation, automobile, electronic and electrical appliances, industrial machinery, etc. It can be used as engine combustion system parts, jet engine components, compressor and generator parts, fasteners, spline joints and electronic contacts, and can also be used as automobile engine parts, bearings, piston bushings, timing gears, printed circuit boards, insulating materials, heat-resistant cables, terminal blocks, sockets in the electronics industry, high temperature self-lubricating bearings, high temperature self-lubricating bearings, and timing gears in the machinery industry, and can also be used in the automotive industry. High temperature self-lubricating bearings, compressor blades and piston machine, sealing rings, equipment heat shield, thrust washers, bushings, etc..

Polyetherimide has excellent mechanical properties, electrical insulation properties, irradiation resistance, high and low temperature resistance and abrasion resistance, self-extinguishing, good melt flow, molding shrinkage of only 0.5 % ~ 0.7 %. PEI can be injection and extrusion molding, post-processing is easier, can be adhesive or a variety of welding methods and other materials, PEI in the electronics and electrical appliances, aerospace, automotive, medical equipment and other industries are widely used. GE is the world's largest producer of PEI, and some foreign engineering plastics modification company to provide PEI alloys and other modified products. The trend of development is the introduction of p-phenylenediamine structure or with other special engineering plastics alloy to improve its heat resistance; or with PC, PA and other engineering plastics alloy to improve its mechanical strength.

Polyamide-imide strength is currently the highest non-reinforced plastics, this color material tensile strength of 190MPa, bending strength of 250MPa. 1.8MPa load heat distortion temperature of 274 ℃. PAI has good ablation resistance and high temperature, high frequency under the electromagnetic properties of metals and other materials have good adhesive properties. It is mainly used for gears, rollers, bearings and separating claws of copiers, etc. It can also be used as ablative material, permeable material and structural material of aircraft.