Polyphenylene ether is a high-strength engineering plastic developed in the 1960s. Its chemical name is poly 2,6-dimethyl-1,4-phenylene ether, abbreviated as PPO (Polyphenylene Oxide) or PPE (Polypheylene ether), also known as polyphenylene oxide or polyphenylene ether.
Basic Information
Polyoxyxylene was produced by General Electric Ashay in 1956 by using cuprous chloride as a catalyst to oxidatively couple 2,6-dimethylphenol to produce polyoxyxylene. It was published in 1964 and named PPO.
Polyoxyl is one of the cheap high temperature resistant plastics, but it is difficult to manufacture, and its impact and heat resistance will decrease over time. Mixing polyoxyl and polystyrene can improve this disadvantage. In the 1960s, the adjusted polyoxyl came into being, and the trade name was Noryl. The main common ones on the market are modified polyphenylene oxide (MPPO), or MPPE (Modified Polypheylene ether).
Basic properties of polyphenylene ether
- It is white granules. It has good comprehensive performance and can be used in 120-degree steam. It has good electrical insulation and low water absorption, but it has a tendency to stress cracking. Modified polyphenylene ether can eliminate stress cracking.
- It has outstanding electrical insulation and water resistance, good wear resistance and electrical properties, and good dimensional stability. Its dielectric properties rank first among plastics.
- MPPO is a modified material made by blending PPO and HIPS, and all materials on the market are of this type.
- It has high heat resistance, with a glass transition temperature of 211 degrees and a melting point of 268 degrees. It tends to decompose when heated to 330 degrees. The higher the PPO content, the better the heat resistance. The heat deformation temperature can reach 190 degrees.
- Good flame retardancy, self-extinguishing, and moderately flammable when mixed with HIPS. Lightweight, non-toxic, and can be used in the food and pharmaceutical industries. Poor light resistance, and will discolor if used in the sun for a long time.
- It can be blended and modified with ABS, HDPE, PPS, PA, HIPS, glass fiber, etc. Characteristics of PPO plastic raw materials
- PPO plastic raw materials are non-toxic, transparent, and have a low relative density. They have excellent mechanical strength, stress relaxation resistance, creep resistance, heat resistance, water resistance, water vapor resistance, and dimensional stability.
- Good electrical properties in a wide temperature and frequency range, no hydrolysis, The shrinkage rate is small, it is flame-retardant and self-extinguishing, but it has poor resistance to inorganic acids, alkalis, aromatic hydrocarbons, halogenated hydrocarbons, oils, etc., and it is easy to swell or stress crack.
- It has the advantages of high rigidity, high heat resistance, flame retardancy, high strength and excellent electrical properties.
- Polyether also has the advantages of wear resistance, non-toxicity and pollution resistance.
- The dielectric constant and dielectric loss of PPO plastic raw materials are among the smallest among engineering plastics. It is almost unaffected by temperature and humidity and can be used in low, medium and high frequency electric fields.
- The load deformation temperature of PPO can reach above 190℃, and the brittle temperature is -170℃.
- The main disadvantage is poor melt fluidity and difficulty in processing and molding.
Physical properties
PPO is non-toxic, transparent, and has a low relative density. It has excellent mechanical strength, stress relaxation resistance, creep resistance, heat resistance, water resistance, water vapor resistance, and dimensional stability. It has good electrical properties in a wide range of temperature and frequency. Its main disadvantages are poor melt fluidity and difficulty in processing and molding. Most of the practical applications are MPPO (PPO blends or alloys). If PPO is modified with PS, it can greatly improve the processing performance, stress cracking resistance and impact performance, and reduce costs, but the heat resistance and gloss are slightly reduced. Modified polymers include PS (including HIPS), PA, PTFE, PBT, PPS and various elastomers, polysiloxanes. PS-modified PPO has a long history and a large product volume. MPPO is the most widely used general engineering plastic alloy variety. The larger MPPO varieties include PPO/PS, PPO/PA/elastomer and PPO/PBT/elastomer alloy. PPO and MPPO can be processed by various methods such as injection molding, extrusion, blow molding, molding, foaming and electroplating, vacuum coating, and printing machine processing. Due to the high melt viscosity, the processing temperature is relatively high.
PPO and MPPO are mainly used in electronic appliances, automobiles, household appliances, office equipment and industrial machinery. MPPO is used to make automobile dashboards, radiator grids, speaker grilles, consoles, fuse boxes, relay boxes, connectors, and wheel covers due to its heat resistance, impact resistance, dimensional stability, scratch resistance, peeling resistance, paintability and electrical properties. It is widely used in the manufacture of connectors, coil bobbins, switch relays, tuning equipment, large electronic displays, variable capacitors, battery accessories, microphones and other parts in the electronic appliance industry. It is used in household appliances for parts such as televisions, cameras, videotapes, tape recorders, air conditioners, heaters, and rice cookers. It can be used as external parts and components for copiers, computer systems, printers, fax machines, etc. In addition, it can be used to make the housings and parts of cameras, timers, water pumps, blowers, silent gears, pipes, valve bodies, surgical instruments, sterilizers and other medical equipment parts. Large blow molding can be used to make large automotive parts such as spoilers and bumpers. Low foaming molding is suitable for making large products with high rigidity, dimensional stability, excellent sound absorption, and complex internal structures, such as various machine housings, bases, and internal brackets. It has a large degree of design freedom and lightweight products.
Chemical properties
The chemical formula is abbreviated as PPO. It is a thermoplastic resin formed by oxidative coupling polymerization of 2,6-disubstituted phenol, generally in the form of khaki powder. The commonly used one is polyphenylene ether synthesized from 2,6-dimethylphenol, which has excellent comprehensive properties. The biggest feature is that it has excellent dimensional stability and outstanding electrical insulation under long-term load. It has a wide operating temperature range and can be used for a long time in the range of -127 to 121°C. It has excellent water resistance and steam resistance, and the products have high tensile strength and impact strength, and good creep resistance. In addition, it has good wear resistance and electrical properties. It is mainly used to replace stainless steel to manufacture surgical medical equipment. In the electromechanical industry, it can be used to make gears, blower blades, pipes, valves, screws and other fasteners and connectors, etc. It is also used to make parts in the electronics and electrical industries, such as coil skeletons and printed circuit boards. In 1964, General Electric Company of the United States first used 2,6-dimethylphenol as a raw material to realize the industrial production of polyphenylene ether. In 1966, General Electric Company produced modified polyphenylene ether (MPPO). In 1984, the world consumption of polyphenylene ether was 163kt.
Preparation method
A method for preparing polyphenylene ether comprises: contacting a polyphenylene ether solution obtained by polymerization in the presence of a water-insoluble polymerization solvent and a catalyst with a chelating agent aqueous solution to terminate the polymerization reaction and deactivate the catalyst; then adding a water-soluble solvent that hardly dissolves the polyphenylene ether to precipitate the polyphenylene ether, and separating and recovering the precipitated polyphenylene ether;
wherein (a) the polyphenylene ether solution and the chelating agent aqueous solution are mixed and contacted and maintained at 50 to 120° C. for 10 to 180 minutes;
The mixture after (b) separating and recovering the polyphenylene ether contains a water-insoluble polymerization solvent and a water-soluble solvent for the poorly soluble polyphenylene ether, and the mixture is added with water to extract the water-soluble solvent for the poorly soluble polyphenylene ether, so that the water-soluble solvent for the poorly soluble polyphenylene ether is extracted into the aqueous phase and separated from the polymerization solvent;
wherein (c) the water-soluble poorly soluble polyphenylene ether solvent is separated and removed from the aqueous phase by distillation, all or part of the remaining water is recycled for contact with the filtrate after separation of the polyphenylene ether, and the content of high-boiling organic matter in the remaining aqueous phase is 1 wt % or less.
Industrial production methods
The process includes two parts: polymerization and post-treatment. A quantitative amount of copper-ammonia complex catalyst is first added to the polymerization reactor, oxygen is bubbled in, and then 2,6-dimethylphenol and ethanol solution are gradually added to perform oxidative coupling polymerization to obtain a polymer. The post-treatment is to centrifuge the polymer, wash it with ethanol solution containing 30% sulfuric acid, and then soak it with a dilute alkali solution, wash it with water, dry it, and granulate it to obtain a granular resin of polyphenylene ether.
2,6-diphenylphenol can also be used as a monomer. The resulting polyphenylene ether has better thermal stability and has been used to manufacture high-temperature resistant films and insulating products.
In order to improve molding performance and reduce costs, polyphenylene ether can be modified by blending. Modified polyphenylene ether has low cost and its market price can compete with ABS resin. It is widely used to replace bronze or brass to make various mechanical parts and pipes.
Safety Information
- R36 Irritating to eyes.
- R37 Irritating to respiratory system.
- R38 Irritating to skin.
Molding process
- Non-crystalline material, low moisture absorption, PPO has a very low water absorption rate, but moisture will cause defects such as silver threads and bubbles to appear on the surface of the product. For this reason, the raw material can be placed in an oven at 80~1OOC and dried for 1-2 hours before use.
- PPO has high molecular bond rigidity, high glass transition temperature, and is not easy to orient, but it is difficult to relax after forced orientation. Therefore, the residual internal stress in the product is high and generally requires post-processing.
- PPO is an amorphous material, and its rheological properties in the molten state are close to those of a Newtonian fluid, but the degree of deviation from a Newtonian fluid increases with increasing temperature.
- The viscosity of PPO melt is high, so the temperature should be increased during processing and the injection pressure should be appropriately increased to improve the mold filling capacity.
- The recycled PPO can be reused, generally 3 times, without significant reduction in performance.
- PPO melt should be molded by screw injection molding machine, and the nozzle should be straight-through type with a hole diameter of 3-6mm.
- During PPO injection molding, high pressure and high speed injection should be adopted, and the pressure holding and cooling time should not be too long.
- The main runner of the mold should have a larger taper or a pull hook, and the runner should be short and thick.
- The gate should be direct, fan-shaped or flat. When using a needle-shaped gate, the diameter should be appropriately increased. For long runners, a hot runner structure can be used.
- The molding shrinkage of PPO is relatively small, generally 0.2% to 0.7%, so the product has excellent dimensional stability.
- Poor fluidity, similar to Newtonian fluid, viscosity is sensitive to temperature, and product thickness is generally above 0.8 mm. It is very easy to decompose, and corrosive gas is produced during decomposition. The molding temperature should be strictly controlled, the mold should be heated, and the gating system should have little resistance to material flow.
- The water absorption rate of polyphenylene ether is very low, about 0.06%, but a small amount of water will cause silver threads and other roughness on the surface of the product. It is best to dry it and the temperature should not exceed 150 degrees, otherwise the color will change.
- The molding temperature of polyphenylene ether is 280-330 degrees, and the molding temperature of modified polyphenylene ether is 260-285 degrees. PPO plastic raw material injection molding process melt temperature: 270-290℃
Barrel constant temperature: PPO has high heat resistance, with a thermal decomposition temperature of 350°C and no obvious thermal degradation within 300°C. Usually, the barrel temperature is controlled at 260~290°C, and the nozzle temperature is about 10°C lower than the barrel temperature.
Mold temperature: Due to the high viscosity of PPO melt, a higher mold temperature should be used during injection molding. Usually, the mold temperature is controlled at 100~15OC. When the mold temperature is lower than 1OOC, thin-walled plastic parts are prone to insufficient filling and delamination; when it is higher than 15OC, defects such as bubbles, silver wire, and warping are prone to occur.
Injection pressure: Increasing the injection pressure is beneficial to the filling of the molten material into the mold. Generally, the injection pressure is controlled at 100-140MPa.
Holding pressure: 40%-60% of injection pressure
Back pressure: 3-10 MPa (30-100 bar)
Injection speed: Products with long flow channels require fast injection; but in this case, ensure that the membrane has sufficient air permeability.
Screw speed: medium screw speed, equivalent to linear speed of 0.6m/s
Measuring stroke: 0.5-3.5D
Residue volume: 3-6mm, depending on the metering stroke and screw diameter.
Pre-drying: Dry at 110℃ for 2h.
Recyclability: Materials can be recycled as long as the recycled material has not been thermally degraded.
Shrinkage rate: 0.8%-1.5%
Gate system: Use point or latent gate for small products, otherwise use straight gate or disc gate; the heating system can be turned off during the hot runner machine downtime; under the back pressure state of the bottom screw, operate several metering cycles to empty the barrel like operating an extruder.
Barrel equipment: standard screw, check ring, straight nozzle.
Application Areas
Pure PPO material has the disadvantages of poor melt fluidity and high price. The products sold on the market are all improved products with excellent comprehensive properties. They are widely used in:
Electronics and Electrical
It can meet the requirements of excellent electrical insulation under conditions of moisture, load and high temperature, and is used to prepare TV tuners, coil cores, microwave insulation parts, shielding sleeves, high-frequency printed circuit boards, various high-voltage electronic components, TV, computer, fax machine, copier casings, etc.
Auto Industry
Suitable for instrument panels, window frames, shock absorbers, pump filters, etc.
Mechanical Engineering
Used as gears, bearings, pump impellers, blower impeller blades, etc.
Chemical Industry
Used to make corrosion-resistant parts such as pipes, valves, filters and submersible pumps.
The properties of PPO determine its application areas and scope of use:
- MPPO has low density and is easy to process. Its heat deformation temperature is between 90 and 175°C. It has products of different specifications and good dimensional stability. It is suitable for manufacturing cabinets, chassis and precision parts of office equipment, household appliances, computers, etc.
- The dielectric constant and dielectric loss tangent of MPPO are the lowest among the five general engineering plastics, that is, it has the best insulation and good heat resistance, and is suitable for the electrical industry. It is suitable for making electrical insulation parts used in humid and loaded conditions, such as coil skeletons, tube sockets, control shafts, transformer shielding sleeves, relay boxes, insulating pillars, etc.
- MPPO has good water resistance and hot water resistance, and is suitable for making water meters and water pumps. The yarn tubes used in textile factories need to be resistant to boiling, and the yarn tubes made of MPPO have a long service life.
- The dielectric constant and dielectric loss tangent of MPPO are unaffected by temperature and frequency among engineering plastics, and it has good heat resistance and dimensional stability, making it suitable for the electronics industry.
- Due to the development of the electronics industry and the communications industry, mobile phones, portable computers, high-performance cameras, camcorders, etc. all require lithium-ion batteries, so the lithium-ion battery market has great development prospects. In the past, the packaging materials for organic electrolytes used in lithium-ion batteries used ABS or PC. In 2013, some countries developed MPPO for batteries, which has better performance than the previous two.
- MPPO is widely used in the automotive industry, such as instrument panels, bumpers, etc. PPO and PA alloys, especially those with high impact resistance, are rapidly used in exterior parts.
- In the chemical industry, modified polyphenylene ether can be used to manufacture corrosion-resistant equipment. It has particularly good hydrolysis resistance, and is also resistant to acids and alkalis, and is soluble in aromatic hydrocarbons and chlorinated hydrocarbons.
- Used in medical equipment, it can replace stainless steel and other metals in hot water storage tanks and exhaust fan mixed filler valves.
Development process
In 1915, Hunter of the United States first used unsubstituted phenol monomers as the main material to produce PPO polymers with low molecular weight. In 1957, Hay of GE of the United States used the oxidative coupling method to produce high molecular weight polymers with 2,6 substituents. In 1961, Pricl used potassium ferrocyanide as a catalyst and carried out polymerization reaction with halogenated phenol to obtain products with high shrinkage and high molecular weight. In 1965, GE of the United States used Hay’s technology to first realize industrial production by the oxidative coupling synthesis method. Although PPO has many advantages, it also has many defects, mainly in terms of high melting temperature, high melt viscosity, poor thermoplastic formability, etc., which limit its application. Therefore, GE successfully modified PPO by blending polystyrene (PS) or high-impact polystyrene (HIPS), thereby improving PPO’s resistance to stress cracking. In 1967, GE realized the production of modified engineering plastic polyphenylene ether. The world’s PPO production technology has been monopolized by GE in the United States. In 1979, Japan developed polystyrene grafted PPO resin. During this period, MPPO (engineering plastic alloy formed by blending and modifying PPO with other plastics) developed the fastest, and maintained a relatively fast development speed in the first half of the 1990s. By the end of the 1990s, there was almost no growth. In 2013, almost all the products consumed on the market were PPO alloy products, of which 30%-70% were blended resins and the average PPO content was 45%. MPPO has developed rapidly as a general engineering plastic with its excellent comprehensive performance and numerous grades. It has become the world’s fifth largest general engineering plastic after engineering plastics polyamide (PA), engineering plastics polycarbonate (PC), engineering plastics polyoxymethylene (POM), engineering plastics polybutylene terephthalate (PBT) and engineering plastics polybutylene terephthalate (PET).
In the 1960s, the research work on the synthesis of 2,6-dimethylphenol and the preparation of engineering plastic polyphenylene ether was carried out in Shanghai, Tianjin and other places. In the late 1960s, the Shanghai Institute of Synthetic Resins completed laboratory research and carried out expanded experiments. In the early 1970s, a 100-ton device was established in Shanghai for trial production, and in the 1980s, the pilot technology appraisal was passed. During this period, the Shanghai Institute of Synthetic Resins did a lot of basic research work, systematically studied the polymerization reaction mechanism, the influence of copper content on the thermal aging performance of MPPO, explored the selection of catalysts, successfully studied the intermittent polymerization technology, and developed and produced general MPPO such as flame retardant, heat-resistant grade, and glass fiber (GF) reinforced grade. The Beijing Institute of Chemical Industry has also accumulated experience in the synthesis of 2,6-dimethylphenol monomers, polymerization processes, and modification technologies, and built a thousand-ton production device, but it was eventually terminated due to technical failure. In addition, the Guangzhou Institute of Chemistry of the Chinese Academy of Sciences conducted laboratory research on the chemical modification of engineering plastic polyphenylene ether, and the Changchun Institute of Applied Chemistry of the Chinese Academy of Sciences conducted in-depth research on the gas permeation behavior of modified engineering plastic polyphenylene ether membranes. In 2013, the main companies engaged in the production and research of MPPO included Shanghai Pacific Chemical Group Synthetic Resin Research Institute, Beijing Chemical Research Institute, Fujian Duoling Engineering Plastics Co., Ltd., etc. Guangdong Dongguan Shengyi Copper Clad Laminate Co., Ltd. and Shaanxi State-owned 704 Factory also began laboratory research on thermosetting engineering plastic polyphenylene ether resin.
Bluestar New Chemical Materials Co., Ltd. Ruicheng Branch is a subsidiary of Bluestar (Group) Co., Ltd. under China National Chemical Corporation. It is a state-owned enterprise mainly engaged in chemical new materials and phenol series products. Since its establishment in 2006, Bluestar New Chemical Materials Co., Ltd. Ruicheng Branch has achieved rapid development by relying on high-tech polyphenylene ether projects, continuous improvement and innovation, and has become the only polyphenylene ether manufacturer in China. The company has 5 workshops and 1 R&D institution, with an annual output of 10,000 tons of polyphenylene ether and phenol series products.
Polyphenylene ether (PPO or PPE), a polymer of 2,6-dimethylphenol, is also known as polyphenylene oxide. It improves the mechanical properties, water resistance and heat resistance of polymers. It is easily dispersed in elastomers and has good flexibility. The company’s products have passed ISO 9001 quality system certification. It was awarded the title of “National Key New Product” in 2008. It is widely used in the automotive industry, electronic and electrical industry, pump housings, impellers, valves, water meter housings, filter materials for water treatment, etc. In order to comply with the trend of e-commerce development, realize sales transformation and improve sales performance, Bluestar Ruicheng Branch has opened stores on Alibaba, Zhongsu, Huicong and other websites, and can trade online, providing buyers with convenient purchasing channels and improving efficiency.
