Special engineering plastics refer to a type of engineering plastics with high comprehensive performance and long-term use temperature above 150°C. They mainly include polyphenylene sulfide (PPS), polyimide (PI), polyether ether ketone (PEEK), liquid crystal polymer (LCP) and polysulfone (PSF). Special engineering plastics have unique and excellent physical properties and are mainly used in high-tech fields such as electronics and electrical, special industries, etc.

Basic introduction

Special engineering plastics mainly include polyphenylene sulfide (PPS), polysulfone (PSF), polyimide (PI), polyarylate (PAR), liquid crystal polymer (LCP), polyether ether ketone (PEEK), including Fluoropolymers (PTFE, PVDF, PCTFE, PFA), etc., there are many types of special engineering plastics with excellent performance and high prices.

Polyphenylene sulfide

Basic features

The full name of polyphenylene sulfide is polyphenylene sulfide, which is a thermoplastic resin with phenylthio groups in the main chain of the molecule. The English name is polyphenylene snlfide (PPS for short).

PPS is a crystalline (crystallinity 55%-65%) highly rigid white powder polymer with high heat resistance (continuous use temperature up to 240°C), mechanical strength, rigidity, flame retardancy, chemical resistance, and electrical properties., resin with excellent dimensional stability, excellent wear resistance, creep resistance, and excellent flame retardancy. Self-extinguishing. It reaches UL94V-0 level and still maintains good electrical properties under high temperature and high humidity. It has good fluidity and is easy to form. There are almost no shrinkage holes during molding. It has good affinity with various inorganic fillers. After reinforcement modification, its physical and mechanical properties and heat resistance (thermal deformation temperature) can be improved. Reinforcement materials include glass fiber, carbon fiber, polyaramid fiber, metal fiber, etc., with glass fiber being the main one. Inorganic fillers include talc, kaolin, calcium carbonate, silica, molybdenum disulfide, etc.

PPS/PTFE, PPS/PA, PPS/PPO and other alloys have been commercialized. PPS/PTFE alloy improves the brittleness, lubricity and corrosion resistance of PPS. PPS/PA alloy is a high toughness alloy.

Glass fiber reinforced PPS has excellent thermal stability, wear resistance, creep resistance, excellent mechanical and electrical properties in a wide range (temperature, humidity, frequency), small dielectric quantity and low dielectric loss. Low. As a high-temperature resistant and anti-corrosion coating, the coating can be used for a long time at 180°C; in the electronic and electrical industry, it is used as connectors, insulating partitions, terminals, and switches; in machinery and adhesive machinery, it is used in pumps, gears, piston ring storage tanks, and blades Valve parts, watch parts, camera parts; carburetors in the automobile industry. Distributor components, electronic and electrical components, gas valves, sensor components; home appliance components include tape recorder structural components, body diodes, and various parts; the other is also used in the aerospace and aviation industries. PPS/PTFE can Make anti-stick, wear-resistant parts and transmission parts, such as shaft pumps.

Development history

In 1973, the U.S. Phillips Petroleum Company successfully developed the synthesis technology of PPS and was the first to realize industrial production and launched a PPS resin product with the trade name “Ryton”. After the patent protection of Phillips Company expired in 1985, Japan’s Tosoh Corporation, Kureha Chemical Industry Company, and Germany’s Bayer Company all built commercial PPS production devices. Sichuan Deyang Company took the lead in building the country’s first thousand-ton PPS resin production line in 2002, filling the gap in China’s PPS industrial production and making China the fourth country in the world to realize PPS industrialization after the United States, Japan and Germany.. In 2007, the company invested in a new PPS resin production line with an annual output of 24,000 tons and a PPS spinning production line with an annual output of 5,000 tons, achieving localization of the entire process from PPS resin to PPS fiber. The global production capacity of PPS resin has exceeded 70,000 tons/year, becoming the largest variety of special engineering plastics.

Uses

PPS has a small specific gravity, high strength and corrosion resistance. It can be used to replace metal materials and make structural components required for military equipment. Such as: engine radiator, body door, electric pump, etc., trans-sea and land-based tank turret base, corrosion-resistant rotating gear, sealing ring, piston ring, sealing gasket, EFI engine rotor impeller, etc., which can effectively reduce the tank’s weight, improving its mobility, reliability, damage safety and riding comfort; self-lubricating bearings, sliding gaskets and other products made of PPS are very suitable for use in weapons and armored combat vehicles under various harsh natural conditions, improve equipment reliability and wartime attendance.

Polysulfone

Introduce

Polysulfone is a thermoplastic engineering plastic prepared through polycondensation reaction using bisphenol A and 4, 4′-dichlorodiphenyl sulfone as raw materials. The English name Polysalfone (referred to as PSF or PSU) has two types: ordinary bisphenol A-type PSF (commonly known as PSF), polyarylsulfone and polyethersulfone. Polysulfone is a slightly amber-colored amorphous transparent or translucent polymer with excellent mechanical properties, high rigidity, wear resistance, and high strength. Its operating temperature range is -100~150℃, the long-term use temperature is 160℃, and the short-term use temperature can reach 190℃. Maintaining excellent mechanical properties even at high temperatures is its outstanding advantage.

Development history

Polysulfone material was first successfully developed and put into production by Union Carbide Corporation (UCC). In 1986, the company transferred its polysulfone production and sales rights to Amoco. In addition, major polysulfone manufacturers include BASF of Germany, ICI of the United Kingdom, and Shevchink of Russia. Global polysulfone production has exceeded 40,000 tons, and China’s production capacity is 1,500 tons.

Characteristics

PSF is a slightly amber amorphous transparent or translucent polymer with excellent mechanical properties, high rigidity, wear resistance, and high strength. Its outstanding advantages are that it maintains excellent mechanical properties even at high temperatures, and its range is – 100~150℃, long-term use temperature is 160℃, short-term use temperature is 190℃, high thermal stability, hydrolysis resistance, good dimensional stability, small molding shrinkage, non-toxic, radiation-resistant, flame-resistant, and extinguishing property. Excellent electrical properties over a wide temperature and frequency range. It has good chemical stability. In addition to concentrated nitric acid, concentrated sulfuric acid, and halogenated hydrocarbons, it can withstand general acids, alkalis, salts, and swelling in ketones and esters. Poor UV and weather resistance. Poor fatigue strength is the main disadvantage. PSF must be pre-dried to a moisture content of less than 0.05% before molding. PSF can be processed by injection molding, molding, extrusion, thermoforming, blow molding, etc. The melt viscosity is high, and controlling the viscosity is the key to processing. It should be heat treated after processing to eliminate internal stress. Can be made into precision size products.

Uses

PSF is mainly used in electronic and electrical, food and daily necessities, automotive, aviation, medical and general industry sectors to produce various contactors, connectors, transformer insulation parts, thyristor caps, insulating sleeves, coil bobbins, and terminal posts., printed circuit boards, bushings, covers, TV system parts, capacitor films, brush holders, alkaline battery boxes, wire and cable coatings. PSF can also be used as protective cover components, electric gears, battery covers, aircraft internal and external parts, spacecraft external protective covers, camera baffles, lighting components, and sensors. Replace glass and stainless steel to make steam dishes, coffee containers, microwave cookers, milk containers, milking machine parts, beverage and food dispensers. In terms of health and medical equipment, there are surgical trays, sprayers, humidifiers, dental equipment, flow controllers, groovers and laboratory equipment. They can also be used for dental implants, with high bonding strength, and can also be used for chemical equipment (pump covers, towers Outer protective layer, acid-resistant nozzles, pipes, valves and containers), food processing equipment, dairy processing equipment, environmental protection and infection control equipment.

Applications in the electrical and electronics industry mainly include coil bobbins, contactors, printed circuit boards with two-dimensional and three-dimensional spatial structures, switch parts, lamp stand bases, batteries and battery covers, capacitor thin molds, etc. Since PES products have a long-term use temperature of 180°C and are UL94V-0 grade materials, they have high dimensional stability and good electrical insulation properties, making them the first choice for electrical engineering structural materials.

For applications in the machinery industry, glass fiber reinforced grades are mainly used, and the parts have characteristics such as creep resistance, hardness, and dimensional stability. Suitable for making bearing brackets and shells of mechanical parts, etc.

For applications in the aviation field, it has passed Federal Aviation Regulation Clause 25·853 and Passenger Aircraft Technical Standard Clause 1000·001, and is used for aircraft interior decoration parts including brackets, doors, windows, etc. to improve safety. Polyethersulfone has excellent transmittance to radar rays, and has been used in radar radomes to replace epoxy parts in the past.

Applications of kitchen appliances, including coffee makers, egg cookers, microwaves, hot water pumps, etc.

The development of polyethersulfone is mainly based on copolymerization modification, with the purpose of improving its comprehensive performance and processing performance to meet market demand. Bu Nemen Company has developed polyethersulfone/polysulfone copolymers with different component percentages and different resin properties. The copolymer has a higher heat distortion temperature than polysulfone, lower water absorption than polyethersulfone, better flow processing properties, and can be reinforced with GF.

Polyarylsulfone

Name

Polyarylsulfone (PASF) and polyethersulfone (PES) have better heat resistance and maintain excellent mechanical properties at high temperatures.

Scientific name: polyarylsulfone, polyphenylene ether sulfone

English name: Polyarylsulfone, referred to as PAS

Development history

Polyarylsulfone was developed by the American 3M Company in 1967 and sold under the brand name Astrel360. The production and sales rights were later transferred to Carborundum Company, which still produces and sells it under the brand name Astrel360 around the world.

Production method

Astrel 360 polyarylsulfone is prepared by the Friedel-Crafts polymerization of 4,4′-dicarbonyl dichloride diphenyl ether and biphenyl.

Physical and chemical properties

The typical characteristics of Astrel 360 polyarylsulfone are heat resistance and can be aged for a long time at an air temperature of 260°C.

Processing and shaping

Polyarylsulfone can be processed into products using injection, extrusion or compression molding technology. However, polyarylsulfone has a high melt viscosity, so it has special requirements for processing equipment. Special processing equipment is generally used to meet the processing temperature of 400 to 425°C. The pressure requirement is 140~210MPa (20300~30450psi), and the mold temperature is 230~280℃.

Application areas

Polyarylsulfone is mainly used in the electrical and electronic industries, mostly in multi-plug contactors, printed circuit board substrates and sockets for military products. These parts require good mechanical properties, thermal properties and chemical resistance.

In the US market, in addition to the Astrel brand, there is also a Radel model polyarylsulfone product.

Polyethersulfone

Name

Scientific name: polyethersulfone, polyarylethersulfone

English name: polyethersulfone, referred to as PES

Development history

Polyethersulfone was developed by ICI in 1972 and sold worldwide under the trade name Victrex. The German company BASF produces and sells it under the brand name Ultrason E. In recent years, the production and sales of engineering thermoplastic resins in various countries around the world have been at a low level, among which polyethersulfone is particularly prominent. Bu Nemen Company shut down its polyethersulfone unit with a production capacity of 5,000 tons/year in 1991. Currently the largest manufacturer is BASF. China Jilin University pilot chemical plant, Changchun Institute of Applied Chemistry and Xuzhou Engineering Plastics Factory have a small number of trial products.

Production method

There are two production routes for PES, namely the bisphenol route and the monophenol route. Both routes are nucleophilic high-temperature displacement reactions, adding strong bases during the polymerization reaction, and using high-boiling point inert solvents.

Physical and chemical properties

Since there are no ester structural units in the molecular structure of polyethersulfone, polyethersulfone has excellent thermal properties and oxidative stability. UL has confirmed that the continuous use temperature of polyethersulfone is 180°C and meets the UL94V-0 level flame retardant requirements (thickness is 0.51mm). Polyethersulfone is resistant to stress cracking and is insoluble in polar solvents such as ketones and some halogen-containing hydrocarbons. Resistant to hydrolysis and most acids, alkalis, lipid hydrocarbons, alcohols, oils and lipids. The performance of the polymer can be improved by controlling its molecular weight or adding various reinforcing materials and fibers. This resin meets the requirements of the US FDA and can be used in parts that come into contact with food.

Processing and shaping

Although polyethersulfone is a high-temperature engineering thermoplastic resin, it can still be processed according to conventional thermoplastic processing techniques. Injection molding, extrusion molding, blow molding, compression molding or vacuum molding can be used. High mold temperatures aid molding and reduce molding-induced stresses. Generally, the injection molding temperature is 310~390℃, and the mold temperature is 140~180℃. PES is an amorphous resin with very small mold shrinkage and can be processed into products with high tolerance requirements and thin walls.

Modified products

Typical modified polyethersulfone varieties include glass fiber reinforced and carbon fiber modified conductive resins.

Application areas

Polyethersulfone has unique design properties, including: high mechanical properties within a wide temperature range (-100~200℃); high thermal deformation temperature and good heat aging resistance; long-term use temperature up to 180℃; good weather resistance of products; flame retardant And low smoke density; good electrical properties; transparency, etc. Therefore, PES products are widely used in electrical, electronic, mechanical, medical, food and aerospace fields.

Applications in the automobile manufacturing industry mainly include reflective parts for lighting lamps, with a peak temperature of 200°C, and can be made into aluminum alloy reflective devices. There are also automotive electrical connectors, electronics, electro-mechanical control components, mounts, windows, masks, water pumps and oil pumps, etc.

Applications in the medical and health field. Polyethersulfone parts are resistant to hydrolysis and disinfectant solvents. Products include forceps, covers, operating room lighting components, centrifugal pump surgical device handles, water heaters, hot water pipes, thermometers, etc.

Applications of kitchen appliances, including coffee makers, egg cookers, microwaves, hot water pumps, etc.

Applications in lighting and optics, including reflectors and signal lights. Polyethersulfone parts are transparent in color, stable to UV, and can be used in outdoor environments for a long time.

Polyethersulfone can be prepared through solvent technology into various ultrafiltration membranes, permeability membranes, reverse osmosis membranes and mesoporous fibers with high mechanical strength. Its products are used in energy saving, water treatment and other fields.

Since polyethersulfone belongs to the category of amorphous resin, it can be used as a coating material for coating metal surfaces.

Development trends

Bu Nemen Company has developed a polyethersulfone coating with the brand name Super-Shield. Can be used with Fluon-one-Coat on kitchen utensils to form a non-stick composite coating.

BASF has developed polyethersulfone thermoplastic rigid foam. The material has the characteristics of high heat distortion temperature, heat aging resistance, low smoke evaporation density, low toxicity, hydrolysis resistance, acid and alkali resistance, etc. Composite materials of this rigid foam material with polyethersulfone resin have great potential in the aerospace sector. Because the material is hard and lightweight, it can also be used in shipbuilding, trains, medical and sporting goods.

Germany’s BASF has newly launched a specially formulated polyethersulfone Ultrason grade for the production of food utensils that are required to withstand high temperatures such as microwave heating and boiling. This product uses a new anti-ultraviolet (UV) stabilizer to improve the transparency of the PES grade. This UV stabilizer can ensure that the material does not discolor for 30 years and is heat-resistant and anti-aging. The operating temperature range is – 14 ℃ ~ 220 ℃. The prepared dishes can be taken directly from the refrigerator and placed in the microwave.

Aromatic polyamide (Polyamide Aromatic, referred to as PARA) fibers and their composite materials have the characteristics of high tensile strength, high modulus, low elongation, resistance to combustion, high temperature resistance, resistance to organic solvents, fuels, and lubricants. Therefore, It has a wide range of uses in engineering, and PPTA, MPIA, PBA, etc. have been developed for industrial application.

Polyparaben

Name

Scientific name polyparabenzamide

English name Poly(p-benzamide), abbreviated as PBA

Development history

DuPont of the United States first introduced aramid-polyphenylene isophthalamide (Nomex) fiber in 1916, polyparaben (Fibre B or PRD-49) in 1970, and then in 1972 The tougher poly1,4-phenylene terephthalamide (Kevlar 49) fiber, analysis shows that Kevlar fiber is the representative.

China began to develop polyparaben in 1977, and in 1990 the Shanghai Synthetic Resin Research Institute completed a pilot test with an annual output of 3 tons.

Production method

1. Resin production

Using para-aminobenzoic acid as the unit and N-methylpyrrolidone as the solvent, the reaction was carried out for 3 hours in the presence of a catalyst, a cocatalyst and a temperature of 80 to 90°C. Then, the material is precipitated into alcohol, the resin is washed with water, and dried to obtain the resin for spinning. The intrinsic viscosity of the resin is controlled within the range of 1.8 to 2.2.

2. Preparation of liquid crystal slurry

Dissolve aramid-I resin in an organic solvent (dimethylacetamide or N-methylpyrrolidone) containing 4 to 6% co-solvent, and control the polymer concentration at about 9 to 10% to obtain optically diverse Anisotropic liquid crystal slurry.

3. Wet spinning

Filter the above-mentioned liquid crystal slurry and place it in a storage barrel for deaeration for 24 hours. After the spinning liquid is measured by the spinning metering pump, it is then sent to the spinneret through the filter and passes through the spinning cap with Φ0.05~0.08×500~1000 holes., sprayed into the coagulation bath from the spinneret at a speed of 10 to 20 meters per minute. The coagulation bath is a 20-40% organic solvent aqueous solution with a temperature of 40-50°C. After the coagulated fibers are fully washed with water and dried, aramid-I raw filaments are obtained. The raw silk is heat treated in an inert gas (3 to 5 liters/min, 500 to 550°C) for 3 to 5 seconds to obtain aramid-I fiber.

Physical and chemical properties

1.Physical properties

Fiber color: light yellow

Relative density: 1.4655g/cm3

Multifilament denier: 1000～1500 denier

Fineness: 1.0～1.5 denier

Multifilament strength: 2337～2585Mpa

Elongation: 1.5～2.5%

Elastic modulus:>147Gpa

The performance of Aramid-I is close to that of Kevlar-149. The comparison between the two is as shown in the table

2.Thermal performance

The thermal stability of Aramid-I and Kevlar-49 after impregnated with epoxy resin is similar. When not coated with epoxy resin, the thermal stability of Aramid-I is better than that of Kevlar-49.

Aramid-I was aged at a constant temperature of 280°C for 100 hours, and its performance basically remained unchanged.

The constant temperature thermal aging properties of aramid-I at 320°C are shown in the table.

Application areas

Polyparaben fiber is a high-strength, high-modulus, low-density aramid fiber. Its fiber density (1.42~1.46g/cm3 is 60% of glass fiber and 80% of carbon fiber, tensile strength is 3.4~4.1Gpa, tensile modulus is 82.7~137.9Gpa, and compressive strength is only 20% of tensile strength, displays ductility, can be compressed and bent, and can absorb energy. It is widely used in the reinforcement of thermoplastics and thermoset plastics and is an efficient reinforcing agent for cutting-edge composite materials. Typical applications include:

1. Military composite materials such as missiles, nuclear weapons, and aerospace. It can significantly reduce its own weight and improve its range and load capacity.

2. Utilize its ultra-rigid and low-density properties to use its composite materials as radome and antenna frames.

3. Use its composite materials to make aircraft floor materials, fairings, body doors and windows, interior decoration and other structural materials.

4. Utilize its high strength and low elongation properties as reinforced skeleton materials for optical cables, electrical cables, marine cables, etc.

5.Sports equipment. Successfully used to make rowing boats, oars, badminton rackets, etc.

6. Various high temperature and wear-resistant packings, brake pads, etc.

7. Rubber products. Used to make ultra-high pressure pipes, toothed belts, V-belts, etc.

Poly(p-phenylene terephthalamide)

Name

Scientific name : poly(p-phenylene terephthalamide)

English name Poly (P-Phenylene terephthalamide), abbreviated as PPTA

Development history

DuPont in the United States was the first to develop polyisophthalamide (Nomex) fiber. In 1972, it successfully developed polyparaphenylene amide (Kevlar-29) and polyparaphenylene terephthalamide (Kevlar-29). 49) Fiber. In 1979, the amount of aramid consumed in the United States was 7,000 tons. DuPont in the United States has three major Kevlar fiber manufacturers, namely: the United States’ Reimand factory with an annual production capacity of 20,000 tons; the British Mei Tang factory with an annual production capacity of 7,000 tons; Toray DuPont’s Japan Tokai factory with an annual production capacity of 25,000 tons.

After the patent dispute between the Dutch company Akzo and DuPont was resolved, Akzo actively developed aramid Twaron fiber and built a 5,000-ton production device. It is planned to expand to 7,000 tons in 1992. The company also plans to build an aromatic polyamide factory in Japan in cooperation with Sumitomo Chemical Company. Teijin Corporation of Japan produces Technora aramid fiber at its Matsuyama factory. The company is preparing to cooperate with the German company Hoechst to produce aramid fiber in Germany. The world’s production of poly(p-phenylene terephthalamide) fiber is about 60,000 tons.

Production method

1. Resin production

In the polymerization kettle equipped with N-methylpyrrolidone, add aluminum chloride (1.2~1.8% of the input amount) and pyrrole (pyrrole/p-phenylenediamine = 0.6~1.2 mol ), then add p-phenylenediamine, After dissolution, add terephthaloyl chloride powder in two steps (concentration of p-phenylenediamine is 0.20~0.45 mol/L, acid chloride excess is 0.30~2.5%), stir and react under nitrogen protection and normal pressure, and the reaction temperature is maintained at – 5℃～80℃, polymer intrinsic viscosity is 5.5～6.0.

2. Spinning

Kevlar fiber is made from polyparaphenylene terephthalamide (PPTA) paint. PPTA is the product of the condensation reaction of p-phthalamide and -phthaloyl chloride. Dissolve PPTA in hot concentrated sulfuric acid until the liquid crystal solid concentration reaches 20% by weight. The PPTA-sulfuric acid solution is sprayed into the coagulation bath through dry spinning (dry spray-wet spinning). Then, the fiber is neutralized with a sodium hydroxide aqueous solution, followed by washing with water and drying to make Kevlar fiber.

Physical and chemical properties

1. Resin properties

Intrinsic viscosity ≥4.5

Ash content≤500ppm

Light yellow color

2. Fiber properties

Raw yarn heat treated yarn

Tensile strength 2.8Gpa 2.8GPa

Elongation 5.76% 3.5%

Elastic modulus 51～64Gpa ≥96GPa

Relative density 1.44 1.45

3. Thermal performance

Poly(p-phenylene terephthalamide) has the characteristics of ultra-high strength, ultra-high modulus, high temperature resistance and low density. The thermal weight loss of its original yarn and heat-treated yarn is shown in the table.

Application areas

Polyphenylene terephthalamide fiber can be used as tethering ropes for ships and balloons, fishing gear and traction ropes for collecting resources, yacht canvas, gliding recovery spacecraft, bulletproof suit vests, horse racing suits and other protective clothing. It can also be used as reinforcing fiber for composite materials, such as tire cord and belt cord. In addition, it can also be used in aircraft, automobiles, sporting goods, etc. Polyphenylene terephthalamide fiber produced in China has been successfully used in missiles, aircraft, automobiles, optical cable reinforcements, rowing boats, bows and arrows, badminton and other sports equipment.

Development trends

High-strength, high-modulus, and low-density aramid fibers will continue to develop in the direction of ultra-high strength, ultra-high modulus, and low density in the future. As far as polymer preparation is concerned, continuous extrusion polymerization is the development direction, but the problem of molecular weight control needs to be solved. How to make polymers with uniform molecular weight distribution is still a problem that needs to be solved. In addition, reducing raw material costs and fiber prices are also top priorities. Only by lowering prices and improving quality can we become more competitive.

A comparison of product performance of China’s Aramid Type II, Kevlar from DuPont in the United States, Twaron from Akzo in the Netherlands, and Technora from Teijin in Japan is shown in the table.

Polyimide

Introduce

Polyimide is an aromatic heterocyclic polymer compound with an imide chain link in its molecular structure. The English name is Polyimide (PI for short). It can be divided into iso-phenylene PI, soluble PI, and polyamide-imide (PAI). and polyetherimide (PEI) four categories.

PI is currently one of the best heat-resistant varieties among engineering plastics. Some varieties can withstand high temperatures of 290°C for a long time and 490°C for a short time. They are also resistant to extremely low temperatures. For example, they will not be brittle in liquid helium at -269°C. crack. In addition, the mechanical properties, fatigue resistance, flame retardancy, dimensional stability, and electrical properties are all good. The molding shrinkage is small. It is resistant to oil, general acids and organic solvents, not alkali resistant, and has excellent friction resistance and wear properties. And PI has no poison, can be used to make tableware and medical utensils, and can withstand thousands of sterilizations.

PI molding methods include compression molding, dipping, injection molding, extrusion, die casting, coating, casting, lamination, foaming, and transfer molding.

Development history

Polyimide (PI) first appeared in the patent of Edwards and Robison in 1955. In 1961, DuPont produced polypyromellitic acid imide film and sold it on the market under the trade name Kapton. In 1972, the American General Company began to research and develop polyetherimide (PEI). In 1982, it built a 10,000-ton production unit with the trade name Ultem. After that, Japan’s Ube Industrial Co., Ltd., Mitsui Chemicals Co., Ltd. and some European countries successively realized the commercial production of polyimide. So far, there are more than 20 major varieties of polyimide, and there are more than 40 manufacturers in the United States, Europe and Japan. South Korea, Malaysia, Russia and China all have a small number of manufacturers producing and applying polyimide. In 2005, global production capacity reached 60,000 tons, of which China accounted for approximately 5,000 tons.

Applications

PI is used in aviation, automobiles, electronic 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 connectors. It can also be used as Automobile engine parts, bearings, piston sleeves, timing gears, printed circuit boards, insulating materials, heat-resistant cables, terminals, sockets in the electronics industry, high-temperature self-lubricating bearings, compressor blades and piston machines in the mechanical industry. Seals, equipment heat shields, thrust washers, bushings, etc.

Polyetherimide has excellent mechanical properties, electrical insulation properties, radiation resistance, high and low temperature resistance and wear resistance. It is self-extinguishing, has good melt fluidity, and has a molding shrinkage rate of only 0.5% to 0.7%. Injection and extrusion molding can be used, and post-processing is easy. Adhesives or various welding methods can be used to join other materials. PEI is widely used in electronic appliances, aviation, automobiles, medical equipment and other industries. The American GE Company is the world’s largest PEI manufacturer, and there are also some engineering plastics modification companies that provide modified products such as PEI alloys. The development trend is to introduce p-phenylenediamine structure or form an alloy with other special engineering plastics to improve its heat resistance; or form an alloy with engineering plastics such as PC and PA to improve its mechanical strength.

The strength of polyamide-imide is the highest among current non-reinforced plastics. The tensile strength of this material is 190MPa and the bending strength is 250MPa. The heat deformation temperature reaches 274°C under a load of 1.8MPa. PAI has good ablation resistance and electromagnetic properties under high temperature and high frequency, and has good bonding properties to metals and other materials. It is mainly used in gears, rollers, bearings and copier separation claws, etc. It can also be used as ablation materials, magnetic permeable materials and structural materials for aircraft. PAI was first developed and commercialized by Amoco Company. In addition to Amoco, Japan’s Toray Company also provides molding compounds. Its development direction is to enhance modification and alloying with other plastics.

Polypyromellitimide

Polypyromellitimide, PMMI for short

Development history

Aromatic polyimide was successfully synthesized for the first time in 1980, and high molecular weight aromatic polyimide was prepared in the late 1950s. In 1961, DuPont produced polypyromellitimide film (Kapton). Developed and produced polypyromellitimide film plastics (Vespels) in 1964. Films and molding compounds of this polymer were publicly reported in 1965. Since then, adhesives, coatings, foams and fibers have been developed. In the mid-1960s, a large amount of literature covered various aspects of this polymer. From 1977 to 1979, more than 1,000 relevant manuscripts were published in American chemical literature, and more than 100 documents were registered with the US National Technical Service. As electrical appliances and electronic equipment become smaller and lighter, there is an increasing demand for polyimide with excellent heat resistance and excellent electrical properties. In 1979, the United States consumed 2,200 tons of polyimide. As far as films are concerned, Toray DuPont’s Kapton has an annual production capacity of 565 tons, Jongyon Chemical’s Apical production capacity in Japan is 170 tons, and the company cooperates with Allied-signal to have an annual production capacity of 150 tons Apical in the United States. production equipment, and is also preparing to build a 100-ton production equipment in Switzerland. Reports in Russia are unknown, but it is learned from technical exchanges that the country has production equipment with an annual output of more than 200 tons. The annual production capacity in the United States is nearly 2,000 tons. The world has an annual production capacity of polypyromellitimide films of nearly 4,000 tons. Japan’s annual demand for film plastics is 20 tons, and the United States’ annual demand is estimated to be more than 200 tons. The total demand in the world is more than 300 tons per year, and it is predicted that it will increase at an annual rate of 10% in the future.

China’s research on polypyromellitic imide began in 1962 and was used in enameled wires in 1963. After 1966, films, molding compounds, and adhesives were introduced one after another, and the output has reached more than 200 tons.

Production method

Add a certain amount of dimethylacetamide into the reaction kettle, and then add 4,4′-diaminodiphenyl ether. After it is basically dissolved, add pyromellitic dianhydride and control the reaction temperature at about 50°C to obtain Transparent polyamic acid atopmer solution. After removing the solvent from the prepolymer, it undergoes dehydration and cyclization at 300°C or the addition of acetic anhydride (dehydrating agent) and triethylamine (neutralizing agent) to form a salt and precipitate, and the polyimide is separated.

Physical and chemical properties

The properties of molding powder and molding plastic are as follows:

Molding powder

Appearance: light yellow powder

Fineness: ≤250μm

Apparent density: ≥0.35 (g/cm3)

(0.5% o-cresol solution, measured at 35°C)

Molded plastic

Appearance: Amber translucent

Surface resistivity: ≥1015Ω

Volume resistivity: ≥1016Ω·cm

Compression strength: ≥160MPa

Bending strength: ≥180MPa

Impact strength: ≥100kJ/m2

Dielectric loss tangent (106 Hz) 1×10-3～5×10-3

Dielectric constant (106 Hz) 3.0～3.5

Application areas

Polypyromide films can be used as insulation layers and insulating slot linings for motors and transformer coils. Films compounded with fluororesin can be used as encapsulation materials for aviation cables, flat flexible cables and electrical conductors. Copper laminates combined with copper foil can be used as flexible printed cables, single-layer boards and multi-layer boards, soft tapes on computer print heads, binding posts on strain gauges, etc.

Molding compounds can be used for valve parts in contact with liquid ammonia and parts for jet engine fuel supply systems.

Polyimide adhesives can be used to bond rockets, jet wings, and emery grinding wheels.

Lightweight flame-resistant elastic foam can be used for aircraft seat cushions.

The fibers can be made into hollow fibers for separating mixed gases.

The thermal deformation temperature of polypyromellitide reaches 360°C under a load of 1.8MPa. Its electrical properties, such as dielectric constant and dielectric loss tangent, are better than PAI, but its strength is not as good as the latter. PMMI compressor piston rings, seals, blower impellers, etc. can also be used for valve parts in contact with liquid ammonia and jet engine fuel supply system parts. DuPont of the United States is a major supplier of PMMI films and film plastics.

Development trends

Polypyromide films account for 75% of its uses. In the future, it will not only be used as insulating films, but also functional membranes, especially gas separation membranes, will have great development. Composite copper foil is also becoming more and more widely used, and the application proportion will gradually increase.

Membrane plastics will further improve high-temperature strength, elongation and impact strength to meet application requirements in harsh environments.

Polyamide-imide

Poly (amide-Imide), abbreviated as PAI

Development history

In 1964, Amoco Company developed varnish (AI) for electrical insulation. In 1967, Hitachi Chemical Company developed HI-400 series varnish. In 1972, Amoco Company developed molding materials (Torlon). In 1976, Torlon was commercialized. In 1979, the consumption of polyamide-imide in the United States was 1,000 tons, and in 1988, the demand in the United States was 2,000 tons. There are six companies in the world that develop and produce polyamide-imide. The products of these companies: Torlon molding compound from Amoco of the United States, TI-5000 molding compound from Toray of Japan, TI-1000 molding compound (thermosetting), Torlon from Amoco/Mitsubishi Chemical Company, AI cable from Amoco/GE Coatings, Hitachi Chemical Company’s HI-400 series cable coatings, Amoco Company’s AmocoA-I paint, French Rhone-Poulenc Company’s Kermel fiber.

China’s Shanghai Synthetic Resin Research Institute, Changchun Institute of Applied Chemistry, Shanghai Electromagnetic Wire Factory, Harbin Paint and Pigment Factory and Tianjin Insulating Materials Factory began research and development on polyamide-imide in the mid-1970s. Films and paints are all sold.

Production method

1. Acid chloride method
2. Isocyanate method
3. Direct polymerization method
4. Imine dicarbonate method

The reaction of acid chloride of trimellitic anhydride with aromatic diamine to prepare polyamide-imide is an important method. The process is as follows:

Add a certain amount of 4,4′-diaminodiphenyl ether, dimethylacetamide, and xylene into the reaction kettle, and start stirring. After all the materials are dissolved, add 1,2,4-trimellitic acid chloride. The reaction temperature is controlled at 25-35°C. When the viscosity reaches maximum, dilute with dimethylacetamide and xylene. Then, the hydrochloric acid produced by the reaction is neutralized with ethylene oxide to obtain a soluble polyamide-amic acid prepolymer. If this prepolymer is dehydrated and cyclized at high temperature, infusible and insoluble polyamide-imide can be produced.

Physical and chemical properties

The strength of polyamide-imide is unmatched by any industrial unreinforced plastic in the world today. Its tensile strength exceeds 172MPa and its heat deformation temperature is 274°C under a load of 1.8MPa.

Torlon polymers may also be solid-state polymerized after manufacturing, post-curing to increase molecular weight to provide better properties. Post-curing occurs at 260°C, and the time and temperature required for curing depend primarily on the thickness and shape of the part.

It can be used for a long time at 220℃, does not lose weight at 300℃, and begins to decompose around 450℃. It has better adhesion, flexibility and alkali resistance, can be mixed with epoxy resin for cross-linking and curing, and has good wear resistance.

Processing and shaping

Molding

The material should be pre-dried before injection molding. Drying conditions are 150°C and 8 hours. The upper limit of barrel temperature is 360℃, and the mold processing temperature is 200℃. The injection pressure should be as high as possible. After turning off the booster pump, the injection pressure should be reduced to 14-28MPa, and the back pressure should be 0.3MPa. The post-curing time is about three days at 170~260℃.

Film

Polyamide-imide films were prepared using a continuous dipping method. Use 400mm wide and 0.05mm thick aluminum foil as a continuous carrier. The aluminum foil soaked in the prepolymer solution enters a vertical oven and is dried at 190°C to remove the solvent. Then, it is treated at 200 to 210° C. for 2 to 4 hours to dehydrate and cyclize the prepolymer membrane. After cooling, peel the film off the aluminum foil.

Enameled wire

Generally, large-sized enameled round wires and enameled flat wires are coated on vertical enameling machines, while thin wires are coated on horizontal enameling machines, both using the felt coating method. The furnace temperature and dipping speed vary with the specifications of the enameled wire. For example, for 1mm enameled wire, the furnace temperature is controlled at 200~300℃, and the dipping speed is 4~6 meters per minute.

Application areas

Polyamide-imide has excellent mechanical properties, and the tensile strength of this color material is 190MPa. Molded plastics are mainly used in gears, rollers, bearings and copier separation claws. It has good ablation resistance and electromagnetic properties under high temperature and high frequency, and can be used as ablation materials, magnetic permeable materials and structural materials for aircraft. It has good bonding properties to metals and other materials and is suitable as enameled wire paint, impregnating paint, films, laminates, coatings and adhesives. For example: enameled wires made with it have been used in H-class deep-water submersible motors; laminates are used in printed circuit boards and sockets; films are used as insulation wrapping materials.

Development trends

Compared with polypyromellitimide, amide-imide has lower softening point and thermal deformation temperature, higher water absorption, relative dielectric constant and dielectric loss tangent properties. The future development direction is to enhance modification and alloy it with other plastics to improve its unfavorable properties and meet the needs of more uses.

Polyamino bismaleimide

Polyamino-bis-mieimide, PABM for short

Development history

In 1969, the French company Rhone-Poulenc first successfully developed Kerimid 601 bismaleimide prepolymer. The polymer does not produce by-product gas when solidified, is easy to shape and process, and the product has no pores. It is an ideal matrix resin for advanced composites and laminate resins (Kerimid). Based on this resin, the company prepares materials (Kinel) for compression and transfer molding. Polyaminobismaleimide has good comprehensive balance properties. It has high heat resistance and does not decompose at 350°C. In addition, it has wide sources of raw materials and is cheap, so many varieties have been developed. Cross-linked materials are being developed, modified with acrylic tougheners to improve mechanical strength, and bismaleimide acid is dealcoholized and cyclized to prepare bismaleimide monomers to improve the process, reduce costs, and accelerate polyamide Development of bismaleimides. It is predicted that by the end of the 20th century, the demand for this resin will increase at an annual rate of 15%. China’s research and development of polyaminobismaleimide began in the mid-1970s and is still in the trial production and development stage.

Production method

There are two production methods for polyamino bismaleimide : one is to synthesize the bismaleimide intermediate by reacting maleic anhydride with aromatic diamine, and then react with aromatic diamine to prepare it., this method is generally called the indirect synthesis method; the second method is prepared by the one-step reaction of maleic anhydride and aromatic diamine, which is generally called the direct method to prepare polyaminobismaleimide.

The process of preparing polyaminobismaleimide by indirect method is as follows:

Maleic acid reacts with 4,4′-diaminodiphenylmethane (MDA) in the presence of chloroform and dimethylformamide (DMF) to form bismaleimide, which can be dehydrated or removed by heating or chemical conversion. Acetic acid cyclization produces bismaleimide (MBI). Then, polyaminobismaleimide is prepared by the addition reaction of MBI and MDA.

Since 1970, the use of direct methods to synthesize polyaminobismaleimides has gradually increased. West Germany and Japan have successively published many documents in this area. To sum up, there are roughly three methods.

(1) Amino acid method:

Maleic anhydride reacts with aromatic diamine to form polyaminobismaleimic acid, and then reacts with the carboxyl group and amide group on the polyaminobismaleimic acid molecule. Under heating, through the hydrogenation with the amino group Polyaminoamic acid is produced through ion displacement addition reaction, and then heated to dehydrate and close the ring to form polyaminobismaleimide.

(2) Esteramine salt method:

Maleic anhydride reacts with methanol to produce maleic acid monomethyl ester, and then reacts with aromatic diamine to form an amino ester ammonium salt. It is heated and dehydrated to form a monomethyl ester ammonium salt. Then, hydrogen ion displacement addition Reaction to generate polymonomethyl ester amide, deacetic acid cyclization, and finally polyamino bismaleimide is obtained.

(3) Acetic acid catalysis method:

This method uses acetic acid as the catalyst and reaction medium to directly react maleic anhydride and aromatic diamine to prepare polyaminobismaleimide.

Physical and chemical properties

Mixtures and laminates prepared with this polymer have high heat resistance and can be used for a long time at 200°C. They can still maintain more than half of their mechanical properties after aging at 200°C for one year. They are indeed good H-class insulation materials. Its electrical properties are good and its dielectric loss tangent does not change over a wide temperature range and at various frequencies. The wear and friction coefficient are small, the friction coefficient is 0.1~0.25, and the wear amount is 0.002~0.04mm (low PV value). It has excellent chemical resistance and radiation performance, can withstand 108 Gray irradiation, and its combustion performance can reach UL94 V-0 level.

Processing and shaping

Kinel molding materials can be roughly divided into two categories: structural blends and sliding parts blends. The former is mixed with glass fibers of different lengths; the latter is mixed with graphite or graphite and molybdenum disulfide or polytetrafluoroethylene powder.

The molding processability and molding conditions of the structural compound are as follows:

Kinel5504 contains glass fiber with a length of 6mm, and its volume factor is as high as 8.3 (density 0.25g/cm3). Molded products with excellent mechanical properties can be obtained through compression molding. The granulation conditions are 120~130℃ and 20~40MPa, the molding conditions are the processing temperature 230~250℃, the pressure 10~30MPa, the curing time 1mm thick/2 minutes, the preheating temperature during molding is about 200℃, and the molded product is placed Post-cure in a drying oven at 250°C for 24 hours.

In order to improve its releasability, the mold can be carefully coated with silicone oil or polytetrafluoroethylene aerosol, and the surface of the model requires chrome plating.

Kinel5514 contains a slightly lower amount of glass fiber, the length of the glass fiber is 3mm, the volume factor is 4.7 (density 0.25g/cm3), and it can be compressed to make small precision parts. The molding conditions are the same as Kinel5504.

Kinel5515 has good fluidity and fast curing speed, and can be processed by transfer molding. The granulation and preheating conditions are the same as the previous varieties. The molding temperature, curing time and injection pressure of transfer molding are 200℃, 1mm thickness/1 minute, and 30~60MPa respectively. The suitable post-curing conditions are 200℃ and 24 hours.

The molding conditions of blends for sliding parts vary depending on the type, but are generally the same.

Kinel5505 and Kinel5508, the former contains 25% powdered graphite and the latter contains 40% powdered graphite, are both compression molding materials. The volume factors are 4.0 (density 0.36g/cm3) and 4.6 (density 0.34g/cm3) respectively. The granulation and preheating conditions are the same as other varieties, but cold compression or granulator can be used during granulation, and the granulation pressure is 10~40MPa. The molding temperature, molding pressure and curing time are 220~260℃, 10~30MPa, 1mm thickness/2~4 minutes respectively, and the post-curing conditions are 250℃, 24hr.

Kinel5518 is a micro-powder compression molding material containing polytetrafluoroethylene powder, which can be used for foam sheets. The molding conditions are the same as those with graphite added. The final curing temperature is 200℃.

Kinel5517 is a variety containing graphite and molybdenum disulfide, which can be used to reduce friction parts. It can be compressed and sintered. The volume factor is 5.0 (density 0.3g/cm3). The compression molding conditions are the same as those for other sliding parts materials.

During sintering molding, the powder molding material is first added into the cold mold and high-pressure molding is performed at a pressure of 100 to 200MPa. Open the mold, take out the molded product, move it into the heating furnace, and heat the product at 180~250℃ under program control (for example, 180~185℃, 30min, 185~200℃/1hr, 200℃, 4hr, 200~250℃, 1hr, 250℃, 4hr, about 11 hours in total). The molded product is cooled to room temperature, and the molded product is taken out of the furnace. No post-cure is necessary.

Application areas

Polyaminobismaleimide (PAMB) has good mechanical properties, heat resistance, electrical insulation, radiation resistance and hot alkali aqueous solubility. As a structural material, it is suitable for use in motors, aircraft, automotive parts and radiation resistant materials. Photo materials, etc. The main uses of Kinel materials for sliding parts are thrust bearings, journal bearings, piston rings, thrust washers, guides, sleeves and valve plates, etc.

In the automotive field, it can be used in engine parts, gearboxes, wheels, engine components, suspension dry bushings, axles, hydraulic circulation lines and electrical parts, etc.

In the field of electrical appliances, it can be used for electronic computer printed circuit boards, heat-resistant instrument panels, diodes, semiconductor switching element housings, base plates and connectors, etc.

In the aerospace field, it can be used in jet engine sleeves, missile casings, etc.

In the mechanical field, it can be used to make gears, bearings, bearing cages, sockets, propellers, compression rings and gaskets, etc.

In other fields, it can be used to make atomic machine parts, grinding wheel adhesives, etc.

Development trends

Compared with other polyimide resin materials, Kinel molding materials are easier to mold and process, but their performance is equivalent. However, its molding processability is worse than that of general thermosetting resins. In the future, we should focus on developing varieties with better molding performance to meet the needs of users.

Polyetherimide

Polyetherimide, PEI for short

Development history

In 1972, the American GE Company began to research and develop PEI. After 10 years of trial production and trials, it built a 5,000-ton production device in 1982 and officially sold it on the market as the product Ultem. The annual demand worldwide is about 10,000 tons. Later, in order to improve the heat resistance of the product, GE also developed ULtemⅡ. Since ULtemⅡ contains a p-phenylenediamine structure, the glass transition temperature (tg) increases from 215° to 227°, thus adapting to the needs of ultra-small tube surface pasting technology (SMT) for electronic parts. The company has developed chemical-resistant grade CRS5000 and wire coating grade silicone copolymer D9000. In order to further improve heat resistance, chemical resistance and fluidity, the company has also developed special plastic alloys, such as PEI/PPS alloy JD8901, PEI/PC alloy D8001, D8007 and SPEI/PA alloy.

The Shanghai Synthetic Resin Research Institute’s research and development work on polyetherimide began in the early 1980s. It currently has a 10t/aPEI device, which is currently in short supply. The institute is preparing to build a 100t/a PEI production device to meet the needs of the national defense industry. The institute’s polyetherimide YS30 contains diphenyl ether diamine in its structure, and its product has better hydrolysis resistance.

Production method

Polyetherimide is composed of 4,4′-diaminodiphenyl ether or meta (or p-phenylenediamine) and 2,2′-bis[4-(3,4-dicarboxyphenoxy)phenyl] Propane dianhydride is prepared by heating and polycondensation in dimethylacetamide solvent, powdering, and imidization.

Among the above methods, it can be divided into polynitro substitution method and polycyclic condensation polymerization process. The former first undergoes a cyclization reaction to generate an imide ring, and then undergoes an aromatic nucleophilic nitro substitution reaction to form a flexible ether “hinge”. The latter performs a cyclization reaction first and then a cyclization reaction. The polymer generation process is a polycyclic condensation polymerization process.

PEI can be prepared by melt polycondensation. This approach is promising from an economic, ecological and technological point of view. Since this method does not use solvents, the polymer will not contain solvents, which is of great significance for processing and use.

PEI can also be manufactured directly in the extruder using a continuous method. The operation steps of this method are: the mixture of starting compounds passes through areas with different temperatures in the extruder in sequence, moving from the low-temperature area where the monomers are mixed to the high-temperature area where the final product is melted. The water generated by the cyclization reaction is continuously discharged from the extruder through appropriate orifices, and is usually extracted with the help of vacuum reduction in the last area of ​​the extruder. Polymer pellets or sheets can be obtained from the outlet of the extruder. PEI and various fillers can also be mixed directly in the extruder to produce a PEI-based compound.

Among these methods, solution polymerization is an industrial production method. However, the extruder continuous extrusion polymerization method has been successfully developed on a small device by the Shanghai Synthetic Resin Research Institute and can be promoted to industrial production.

Physical and chemical properties

Polyetherimide has excellent mechanical properties, electrical insulation properties, radiation resistance, high and low temperature resistance and wear resistance, and can transmit microwaves. Adding glass fiber, carbon fiber or other fillers can achieve the purpose of enhanced modification. It can also be combined with other engineering plastics to form a heat-resistant polymer alloy, which can be used at -160~180℃. Shanghai Synthetic Resin Research Institute’s corporate standard SR-7001-86 “YS30 Injection Molding Polyetherimide Plastic”, the main performance indicators are shown in Table 3-47.

Processing and shaping

Polyetherimide can be injection molded and extruded, and is easy to post-process and join with other materials using adhesives and various welding methods. Due to the good melt fluidity, parts with complex shapes can be produced through injection molding. It must be fully dried at 150°C for 4 hours before processing, the injection temperature is 337~427°C, and the mold temperature is 65~117°C. The injection molding conditions of YS30 are as follows:

Preheat 150℃, 4 hours

Barrel temperature:

Front section 300~320℃

Rear section 330~410℃

Injection molding pressure 60~100MPa

Holding time 5~30 seconds

Cooling time 5~30 seconds.

Application areas

Polyetherimide has excellent comprehensive balance properties and is effectively used in industrial sectors such as electronics, motors, and aviation, and is used as a metal substitute material for traditional products and cultural and daily necessities.

In the electrical and electronic industry sectors, components made of polyetherimide materials have been widely used, including high-strength and dimensionally stable connectors, ordinary and micro relay housings, circuit boards, coils, flexible circuits, and reflectors., High-precision dense optical fiber components. What is particularly striking is that using it to replace metal in manufacturing fiber optic connectors can optimize the component structure, simplify its manufacturing and assembly steps, and maintain more precise dimensions, thereby ensuring that the cost of the final product is reduced by about 40%.

Impact-resistant sheet Ultem 1613 is used to manufacture various parts of aircraft, such as side windows, nose parts, seat backs, inner wall panels, door coverings and various items for passengers. Composite materials composed of PEI and carbon fiber have been used in the structure of various parts of the latest helicopters.

Taking advantage of its excellent mechanical properties, heat resistance and chemical resistance, PEI is used in the automotive field, such as manufacturing high-temperature connectors, high-power car lights and indicators, and sensors that control the external temperature of the car cabin (air conditioning temperature sensors). ) and a sensor that controls the temperature of the air and fuel mixture (effective combustion temperature sensor). In addition, PEI can also be used as vacuum pump impellers that are resistant to high-temperature lubricating oil erosion, ground glass joints (socket interfaces) for distillers operating at 180°C, and reflectors for non-illuminated anti-fog lamps.

Polyetherimide foam is used as thermal and sound insulation materials for transport machinery, aircraft, etc.

PEI has excellent hydrolysis resistance, so it is used as handles, trays, clamps, prostheses, medical light reflectors and dental appliances for medical surgical instruments.

In the food industry, used as product packaging and as trays for microwave ovens.

PEI has excellent high-temperature mechanical properties and wear resistance, so it can be used to manufacture valve parts for water pipeline steering valves. Due to its high strength, flexibility and heat resistance, PEI is an excellent coating and film-forming material. It can form coatings and films suitable for the electronics industry, and can be used to manufacture pore sizes < 0.1μm and high permeability. of microporous membrane. It can also be used as high temperature resistant adhesive and high strength fiber.

Development trends

Polyetherimide is mainly produced and sold by General Electric Company of the United States. The development trend is to improve heat resistance. For this reason, p-phenylenediamine structure is introduced and alloyed with other special engineering plastics. In order to improve the mechanical strength of PEI, PC, PA and other engineering plastics are used to form alloys. In terms of polymerization technology, twin-screw continuous extrusion polymerization reaction technology is being developed, and industrial production is expected to be achieved soon.

Polyetheretherketone

Polyether ether ketone, or PEEK for short.

Introduction

Polyetheretherketone (PEEK) resin is a crystalline, super heat-resistant thermoplastic polymer. It has physical and chemical properties such as high temperature resistance and chemical corrosion resistance, and can be used as high temperature resistant structural materials and electrical insulation materials. Through modification, PEEK can achieve higher physical properties. For example, it can be blended with polytetrafluoroethylene (PTFE), polyethersulfone (PESU), etc. to meet different usage requirements. J.Denault and Lin SH respectively use glass fiber (GF), carbon fiber (CF) and other composite-reinforced PEEK resins to improve the material’s service temperature, rigidity, dimensional stability and impact performance; nanomaterial-filled PEEK composite materials have better hardness, tensile strength and The elongation strength and tensile modulus are increased by 20%-50% compared with pure PEEK, thus further expanding its application scope.

Development history

In 1977, the British company ICI successfully synthesized polyetheretherketone PEEK, which was sold on the market in 1978 and has been sold under the brand name Victrex since 1982. Due to its military background, the PEEK market has been monopolized by this company for a long time. In addition to the British ICI Company, manufacturers include Japan’s Mitsubishi Chemical Company, Sumitomo Chemical Company, American DuPont Company and India’s Gharda Company, etc. As soon as PEEK resin came out, it was regarded as an important strategic military material by relevant manufacturers, and exports were restricted to many countries. In order to meet the urgent needs of the development of China’s national defense industry and civilian use, the Special Engineering Plastics Research Center of Jilin University developed PEEK resin synthesis technology with independent intellectual property rights. Changchun Jida High-tech Materials Co., Ltd. used this technology to build a 500t/a production device.

Application areas

Advanced thermoplastic composite materials based on PEEK have become one of the most practical composite materials in the aerospace field. Carbon fiber/polyetheretherketone composite materials have been successfully used in the manufacturing of F117A aircraft fully automatic tail fins, C-130 aircraft fuselage belly panels, Rafale aircraft fuselage skins, and V-22 aircraft nose landing gear. Special carbon fiber-reinforced PEEK wave-absorbing composite material has excellent wave-absorbing properties and can significantly attenuate pulses with a frequency of 0.1MHZ-50GHZ. This type of composite material, model APC, has been used in the fuselage and wings of advanced fighter aircraft.. In addition, the APC-2 type PEEK composite material developed by ICI is a unidirectional reinforced composite material of CelionG40-700 carbon fiber and PEEK multifilament mixed yarn. It is particularly suitable for manufacturing helicopter rotors and missile casings. The American stealth helicopter LHX has already adopted this composite material.. CL Ong et al. developed a PEEK/graphite fiber composite material and solidified it into a landing device for the nose of a fighter jet. It has the characteristics of a short manufacturing cycle and excellent environmental adaptability. Due to its excellent flame retardancy, it is also often used to prepare internal parts of aircraft to reduce the hazards of aircraft fires.

PEEK has the characteristics of flame retardancy, good coating processability (can be melted and extruded without solvent), good peeling resistance, good abrasion resistance and strong radiation resistance. It has been used as insulation or insulation of cables and wires. Protective layer, widely used in atomic energy, aircraft, ships and other fields. PEEK can also be used to manufacture connectors and valve parts for atomic power stations, battery tanks for rockets, and rocket engine parts. Containers for nuclear waste can also be made using blow molding.

Processing and shaping

Film

There are currently two molding methods in China, namely the continuous dipping method and the casting method. First, prepare a polyamic acid solution with a concentration of 15% to 16% and a reduced viscosity of 20 to 50 seconds in a dimethylacetamide solution. Then, a multi-pass dipping machine is used to perform the dipping operation, using 0.05mm thick aluminum foil as a continuous carrier. Each dip is baked and dried (below 180°C) to remove the solvent. The dipping speed is 3.5~6.5m/min. Then, it is treated at 350° C. for 30 to 60 minutes to dehydrate and cyclize the polyamic acid film. After cooling, peel the polyimide film from the aluminum foil to obtain the finished product. If the polyamic acid solution is cast on a continuously running stainless steel base belt, a polyimide film can be produced through baking and high-temperature dehydration and cyclization.

Molded plastic

A 15-20% high viscosity polyamic acid solution prepared by the equimolar reaction of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, then added a tertiary amine catalyst, heated to precipitate, removed the solvent, and then treated at 300°C high temperature, made into molding powder with high specific surface area. Finally, using a similar powder metallurgy method, polyimide powder is added to the mold and maintained at 300°C for 10 minutes, then pressurized (275MPa) for 2 minutes, and cooled by blowing air while maintaining the pressure. When the temperature is lower than 200°C, release the Pressure, just release the mold.

Fiber

Polypyromellitimide fiber is made from its masterbatch polyamic acid DMAC (dimethylacetamide) solution, which is dry-spun into polyamic acid fiber in a gaseous environment and transformed under full stretching. It is formed into polyimide fiber, and the fiber drawing is completed at 550°C after thermal conversion. The fiber made in this way has a tensile strength of 0.45GPa, an elongation of 11.7%, and a modulus of 6.4GPa.

Paint

Polyamic acid can be used as coating material. It’s applied to wires and thermally converted into polyimide, creating an important cable coating. The aforementioned Pyre ML and Pyralin belong to this type of polypyromellitimide coating.