Nylon was developed by the outstanding American scientist Carothers and a scientific research team under his leadership. It is the first synthetic fiber in the world. The emergence of nylon has given a new look to textiles. Its synthesis is a major breakthrough in the synthetic fiber industry and a very important milestone in polymer chemistry. Main Products As the process of miniaturization of automobiles, high performance of electronic and electrical equipment, and lightweight of mechanical equipment accelerates, the demand for nylon will be higher and greater. In particular, nylon, as a structural material, places high requirements on its strength, heat resistance, cold resistance, etc. The inherent shortcomings of nylon are also an important factor limiting its application. Especially for the two major varieties of PA6 and PA66, they have a strong price advantage compared with PA46, PAl2 and other varieties, although some properties cannot meet the development requirements of related industries. Therefore, it is necessary to target a certain application field and expand its application field through modification and improvement of certain properties. Due to the strong polarity of PA, it has strong hygroscopicity and poor dimensional stability, but it can be improved through modification. 1. Reinforce PA. Add 30% glass fiber to PA. The mechanical properties, dimensional stability, heat resistance, and aging resistance of PA are significantly improved. The fatigue-resistant nylon strength is 2.5 times that of unreinforced nylon. The molding process of glass fiber reinforced PA is roughly the same as that without reinforcement, but because the flow is worse than before reinforcement, the injection pressure and injection speed should be appropriately increased, and the barrel temperature should be increased by 10-40°C. Since glass fiber will be oriented along the flow direction during the injection molding process, the mechanical properties and shrinkage will be enhanced in the orientation direction, causing the product to deform and warp. Therefore, when designing the mold, the location and shape of the gate should be reasonable, and the process can be improved. After taking out the product, place it in hot water and let it cool slowly. In addition, the greater the proportion of glass fiber added, the greater the wear on the plasticizing components of the injection molding machine. It is best to use bimetallic screws and barrels. 2. Flame retardant PA. Since flame retardants are added to PA, most flame retardants are easy to decompose at high temperatures and release acidic substances, which have a corrosive effect on metals. Therefore, plasticizing components (screws, plastic heads, plastic presses, etc.) Rubber rings, rubber washers, flanges, etc.) need to be hard chromium plated. In terms of process, try to control the temperature of the barrel not to be too high and the injection speed not to be too fast to avoid discoloration of the product and a decrease in mechanical properties caused by decomposition of the rubber material due to excessive temperature. 3. Transparent PA has good tensile strength, impact strength, rigidity, wear resistance, chemical resistance, surface hardness and other properties. It has high light transmittance, similar to optical glass, and the processing temperature is 300--315℃. During processing, the barrel temperature needs to be strictly controlled. If the melt temperature is too high, it will cause discoloration of the product due to degradation. If the temperature is too low, the transparency of the product will be affected due to poor plasticization. The mold temperature should be as low as possible. High mold temperature will reduce the transparency of the product due to crystallization. 4. Weather-resistant PA adds UV-absorbing additives such as carbon black to PA. These greatly enhance the self-lubricating properties of PA and the wear on metal, which will affect cutting and wear of parts during molding and processing. Therefore, it is necessary to use a screw, barrel, rubber head, rubber ring, and rubber washer combination with strong feeding capacity and high wear resistance. The repeating structural unit on the polyamide molecular chain is an amide group. To sum up, modifications are mainly carried out in the following aspects: ① Improve the water absorption of nylon and improve the dimensional stability of the product. ② Improve the flame retardancy of nylon to meet the requirements of electronics, electrical, communications and other industries. Nylon ③ improves the mechanical strength of nylon to reach the strength of metal materials, replaces metal ④ and improves the low-temperature resistance of nylon and enhances its ability to withstand environmental strain. ⑤ Improve the wear resistance of nylon to adapt to occasions with high wear resistance requirements. ⑥Improve the antistatic properties of nylon to meet the requirements of mining and its mechanical applications. ⑦Improve the heat resistance of nylon to adapt to areas with high temperature resistance such as automobile engines. ⑧Reduce the cost of nylon and improve product competitiveness. In short, through the above improvements, the high performance and functionalization of nylon composite materials can be achieved, thereby promoting the development of products in related industries towards high performance and high quality.
5. Nano-nylon According to news from Japan's Toray Chemical Company, the company has successfully developed a new "nano-fiber" technology with a nano-scale single-filament structure that is two digits smaller than previous ultra-fine fibers. By controlling nano-structure technology, the fiber can be The limit of fineness. Toray Chemical Company said that using this new technology, the company has developed nano-nylon fibers composed of more than 1.4 million monofilaments with a diameter of 10 μm. Compared with previous products, the surface area of ??this fiber is about 1,000 times that of previous products, and it has high surface activity. [1] 6. Super strong nylon Triangle-Raleigh nylon fiber has many uses, from clothing, carpets to ropes to data cables for microcomputers, this fiber can be used. Researchers at the University of North Carolina's School of Textiles are working to improve the fiber and reportedly have developed the strongest aliphatic nylon fiber. Scientists Dr. Tonelli, Professor of Polymers, and Dr. Richard Cuttack, Assistant Professor of Textile Engineering, Chemistry and Natural Sciences, are working on a way to produce higher energy without expensive, complicated processes. Strong nylon fiber. They used aliphatic nylon or nylon to conduct research. The carbon aids of this nylon are connected by straight chains or open branched chains in the past, emphasizing that the chain is not large. Stronger aliphatic nylons could be used in ropes, loading belts, parachutes and car tires, or create synthetic materials suitable for high-temperature applications. The findings were presented at the American Chemical Sciences Annual Meeting in Philadelphia and published in the journal Polymers. The fibers are made from polymers, or long chains of molecules consisting of many units. When these polymer chains are neatly arranged, the polymer becomes crystalline. These coiled polymers need to be stretched, and their elasticity needs to be eliminated if they are to be made into stronger fibers. Adding hydrogen to nylon chains prevents stretching, so overcoming this bonding is a key factor in creating stronger nylon fibers. Super-strong fibers, such as Kevlar fiber, are made from aromatic nylon polymers. They are very stiff and have long chains containing rings. Aramid nylon is difficult to make and therefore very expensive. So Professor Tonelli and Dr Cuttack conducted their research using polyamide 66 (nylon 66), a commercial thermoplastic material that is easy to make but difficult to stretch and align. At the same time, it is also difficult to remove the elasticity of nylon 66. This discovery can solve the problem of nylon 66 dissolving in gallium trichloride and can effectively break the hydrogen bonding problem. Allows polymer chain extension. 7. PA The mechanical properties of nylon PA such as tensile and compressive strength change with temperature and moisture absorption, so water is relatively a plasticizer for PA. After adding glass fiber, its tensile and compressive strength can be increased by about 2 times. The temperature resistance is also improved accordingly. PA itself has very high wear resistance, so it can be operated continuously without lubrication. If you want to obtain special lubrication effect, you can add sulfide to PA. Suitable plastic products: various gears, turbines, racks, cams, bearings, propellers, drive belts. Others: Shrinkage rate 1-2. Please pay attention to the dimensional changes due to moisture absorption after molding. Water absorption rate: 8% can be absorbed when the relative moisture absorption is saturated. Suitable wall thickness: 2-3.5mm8.PA66 has high fatigue strength and rigidity, good heat resistance, low friction coefficient, and good wear resistance, but has high hygroscopicity and insufficient dimensional stability. Application: medium load, use temperature <100-120 degrees; wear-resistant and stressed transmission parts working under no or little lubrication conditions. PA6 fatigue strength is rigid and its heat resistance is lower than that of nylon 66, but it has good elasticity and good vibration absorption and noise reduction capabilities. White application: wear-resistant and stressed transmission parts working under light load, medium temperature (80-100), no lubrication or little lubrication, and low noise requirements. The strength, rigidity and heat resistance of PA610 are lower than those of nylon 66, but it has low hygroscopicity and good wear resistance. Application of earthy yellow: Same as nylon 6, suitable for parts requiring relatively precise gears and parts with large changes in working conditions and humidity. The strength and rigidity of PA1010 are lower than nylon 66, the hygroscopicity is lower than nylon 610, the molding process is good, and the wear resistance is good.
Application: Parts working under light load, low temperature, large humidity changes, no lubrication or little lubrication. MCPA strength, fatigue resistance, heat resistance and rigidity are better than PA6 and PA66, and have low hygroscopicity Compared with PA6 and PA66, it has good wear resistance and can be polymerized directly in the mold, so it is suitable for casting large parts. Application: High load, high operating temperature (below 120°C) without lubrication or little lubrication. Milky white cast nylon Cast nylon (MC nylon), also known as monomer cast nylon, is a rough part of the product obtained by directly polymerizing caprolactam monomer in a mold under the action of a strong alkali (such as NaoH) and some cocatalysts. The polymerization and molding processes are combined, so molding is convenient, equipment investment is low, and large machine parts are easy to manufacture. Its mechanical properties and physical properties are higher than nylon 6. It can manufacture gears, turbines, bearings, etc. weighing tens of kilograms. Nylon 1010 Nylon 1010 is an engineering plastic originally created in my country. It is made from castor oil as raw material, extracting sebacic diamine and sebacic acid and then condensing it. It has low cost, good economic effect, excellent self-lubrication and wear resistance, good oil resistance, low brittle transition temperature (about -60°C), high mechanical strength, and is widely used in mechanical parts, chemical industry, and electrical parts. Modified nylon Modified nylon is a type of engineering plastics. It is a granular product formed by using nylon raw materials as the base material and changing its physical properties. The output of such products is modified and produced according to the different needs of some manufacturers. Modified nylon generally includes: reinforced nylon, toughened nylon, wear-resistant nylon, halogen-free flame-retardant nylon, conductive nylon, flame-retardant nylon, etc. 1. Thermal properties: glass transition temperature (Tg) and melting point (Tm); high heat distortion temperature (HDT); high long-term use temperature (UL-746B); wide use temperature range; small thermal expansion coefficient. 2. Mechanical properties: high strength, high mechanical modulus, low latent degeneration, strong wear resistance and fatigue resistance. 3. Others: chemical resistance, electricity resistance, flame resistance, weather resistance, and good dimensional stability. The output of such products is modified according to the needs of some manufacturers. Modified nylon generally includes: reinforced nylon, toughened nylon, wear-resistant nylon, halogen-free flame-retardant nylon, conductive nylon, flame-retardant nylon etc. Modified nylon has many properties and is therefore widely used in automobiles, electrical equipment, mechanical parts, transportation equipment, textiles, and papermaking machinery [2]. Aromatic nylon Aromatic nylon, also known as polyaramid, is a new nylon variety that was first successfully developed by the American DuPont Company in the 1960s with high temperature resistance, radiation resistance, and corrosion resistance. All nylon molecules containing aromatic ring structures are aromatic nylons. If only the diamine or dibasic acid used to synthesize nylon is replaced by aromatic diamine or aromatic diacid respectively, the resulting nylon is semiaromatic nylon, and the nylon synthesized by using aromatic diacid and aromatic diamine is Fully aromatic nylon. The embrittlement temperature of aromatic nylon can reach -70°C, and the Vicat softening temperature can reach 270°C. It is resistant to high temperatures, radiation, corrosion, and wear. It is self-extinguishing and can maintain high electrical properties in a humid state. . Aromatic nylon can be extruded, molded, laminated, and impregnated, and can be used to make fibers, films, impregnated films, decorative laminates, fiberglass reinforced laminates, high-temperature resistant radiant pipes, firewalls, etc. The semi-aromatic nylons that have been commercially used mainly include MXD6, PA6T and PA9T. The fully aromatic nylons mainly include poly-paraphenylene terephthalamide (PPTA), poly-phenylene isophthalamide (MPIA) and poly(m-phenylene isophthalamide). p-Benzamide (PBA), etc. Fully aromatic nylon was successfully developed and industrialized by the American DuPont Company in the 1960s and 1970s. Fully aromatic nylon is widely used in the production of synthetic fibers due to its high melting point, high modulus, and high strength. PPTA is produced from p-phenylenediamine and terephthaloyl chloride using the low-temperature solution polymerization method developed by DuPont. PPTA has excellent properties such as high strength, high modulus, high temperature resistance, and low density. Mainly used as raw material for synthetic fiber spinning; PPTA fiber can also be used as rubber reinforcement and plastic reinforcement. However, PPTA has shortcomings in fatigue resistance and pressure resistance, and PPTA cannot yet achieve melt extrusion molding.
MXD6 MXD6 is a crystalline nylon resin synthesized by Lum et al. in the 1950s through polycondensation reaction using m-xylylenediamine and adipic acid as raw materials. Mitsubishi Gas Chemical Company of Japan used the direct polycondensation method and Toyobo Company used the nylon salt method to synthesize MXD6 respectively. The uses of MXD6 obtained by these two different polymerization methods are also different: MXD6 synthesized by direct polycondensation method can be used to make barrier materials or engineering structural materials; MXD6 synthesized by nylon salt method can be used to produce fiber-grade MXD6 resin. As a crystalline semi-aromatic nylon, MXD6 has the characteristics of low water absorption, high heat distortion temperature, high tensile strength and bending strength, small molding shrinkage, and good barrier properties to O2, CO2 and other gases. Due to its wide processing temperature, MXD6 can be extruded with polypropylene (PP) and extruded with high-density polyethylene (HDPE) for blow molding. In industry, MXD6 is mainly used as packaging materials and as engineering structural materials instead of metal. The former includes food and beverage packaging, instrument and equipment packaging (moisture-proof, vibration-absorbing cushions and foam materials); the latter includes high heat-resistant grade Reny, MXD6/PPO alloy, vibration-resistant grade Reny, etc. In addition, MXD6 is also used in magnetic plastics, transparent adhesives, etc. PA6TPA6T is a semi-aromatic nylon synthesized from aromatic diacid and aliphatic diamine. PA6T has excellent heat resistance and dimensional stability. Since PA6T has a high melting point, it can be prepared by solid-state polymerization or interfacial polymerization. It can be used in fiber manufacturing, mechanical parts and film products, etc. The modified PA6T developed by Japan's Mitsui Chemicals has the characteristics of high rigidity, high strength, and low water absorption. It is mainly used in automotive internal combustion engine components, heat-resistant electrical components, transmission components, and electronic assemblies. It is precisely because of the high melting point of PA6T that it cannot be injection molded like ordinary aliphatic nylon, which limits the application of PA6T. PA9TPA9T is obtained by the melt polycondensation of nonanediamine and terephthalic acid. It was first successfully developed by Japan's Kuraray Company. PA9T has good heat resistance and melt processability. The water absorption rate is only 0.17, which is 1/10 of PA46 (1.8). It has good dimensional stability and other characteristics. It has quickly gained popularity in electronic and electrical, information equipment, automotive parts, etc. a wide range of applications. When the number of carbon atoms of the diamine in the repeating unit chain is 6, the melting point of PA6T is 370°C, which exceeds its thermal decomposition temperature by about 350°C. Therefore, if the third or even fourth component is not added to lower the melting point, It is nylon that cannot be used in practical applications (the melting processing temperature of nylon is generally below 320°C), but if other components are added to lower the melting point, it will inevitably bring about PA6T properties such as crystallinity, dimensional stability and chemical resistance. of reduction. Therefore, increasing the number of carbon atoms of diamine has become another research focus. The structure of PA9T has become an ideal structure, which has both heat resistance and melt processability. However, the synthesis route of nonanediamine, the main raw material for the synthesis of PA9T, is relatively complicated: butadiene undergoes chemical reactions such as hydration, translocation, hydroxylation, and amination reduction to finally obtain nonanediamine. This results in the high production cost of PA9T, which limits the large-scale production and application of PA9T. Polyphenylenediamide Polyphenylenediamide (PPA) is a mixture of polymers formed by the polycondensation of isophthalic acid, terephthalic acid, adipic acid and hexamethylenediamine. It is a semi-crystalline Semi-aromatic nylon. PPA resin is generally produced in batches. PPA has good heat resistance, excellent mechanical properties and dimensional stability, low water absorption and excellent molding processability. It also has good electrical properties and chemical resistance. PPA can be processed using injection molding and extrusion molding. PPA is widely used in automobiles, electronic appliances and general industrial machinery. Poly(m-phenylene isophthalamide) Poly(m-phenylene isophthalamide) (MPIA) is a new type of polyaramid successfully developed by DuPont in the 1960s. It is based on m-phenylenediamine and Isophthaloyl chloride is used as raw material and can be synthesized by low-temperature solution polycondensation method and interfacial polymerization method.
The outstanding feature of MPIA is its long heat-resistant life. In addition, it also has the advantages of high modulus, wear resistance, flame retardancy, and high temperature dimensional stability. However, the light resistance of MPIA is slightly poor and requires the addition of anti-UV agents. MPIA is mainly used in work clothes, high temperature resistant industrial filter materials, parachutes, high temperature conveyor belts, electrical insulation materials, etc. in industrial and flammable and explosive high temperature environments. MPIA can also be processed into rods, plates and fibers. Due to its excellent heat resistance, sliding properties and radiation resistance, it is used in aerospace, atomic energy industry, electrical and automotive industries. Poly(p-benzamide, PBA for short) was successfully developed by DuPont in the United States in the 1970s. Its synthesis route is: p-nitrotoluene undergoes liquid phase air oxidation to obtain para-nitrotoluene. Nitroformic acid, p-nitroformic acid undergoes ammoniation reduction reaction to obtain p-aminocarbamic acid, and p-aminobenzoic acid is converted into p-aminobenzoyl chloride hydrochloride or p-sulfite benzoyl chloride, and finally PBA is obtained through polycondensation . PBA has high modulus, high strength and other properties, and can be used in rocket engine casings, high-pressure vessels, sporting goods and coated fabrics.