PA66 (polyamide 66 or nylon 66) is a thermoplastic resin, generally made by polycondensation of adipic acid and adipic diamine. It is insoluble in general solvents, and only soluble in m-cresol and so on. It has high mechanical strength and hardness, and is very rigid. Can be used as engineering plastics, mechanical accessories such as gears, lubricated bearings, instead of non-ferrous metal materials to do machine shells, automobile engine blades, etc., as well as other needs to have impact resistance and high strength requirements of the product. Can also be used to make synthetic fibers.
General information
It is a thermoplastic resin containing an amide group (-CONH-) in the repeating structural unit of the main chain of the molecule. It is often made into cylindrical pellets, and the molecular weight of polyamides used for plastics is generally 15,000 to 20,000 tons. The common characteristics of various polyamides are flame retardant, high tensile strength (up to 104kPa), wear-resistant, good electrical insulation, heat-resistant (in 455kPa under the heat distortion temperature of 150 ℃ or more), the melting point of 150 ~ 250 ℃, molten state of the resin's mobility is high, the relative density of 1.05 ~ 1.15 (filler can be added to increase the number to 1.6), most of the non-toxic. However, when the monomer content in the resin is too high, it is not suitable for long-term contact with skin or food, and there are often food hygiene regulations in various countries.
Nylon products
History The earliest industrial production of polyamide varieties is polyamide 66 (i.e., nylon 66), the United States of America DuPont W.H. Carothers published the first patent in 1937, the production of polyamide fibers (nylon filament) samples, the establishment of a pilot plant in 1938, 1939 industrial production units into operation. At that time, polyamides were mainly used for the production of fibers, ropes and coverings. The military use of these materials developed considerably during the Second World War, and films and plastics were produced after the war. 1941 saw the start of production of polyamide 6 in Germany, followed by the development of polyamide 610. 1950 saw the development of polyamide 11 in France. 1958 saw the successful trial production of polyamide 1010 in China, and co-polyamide in the USSR. 1966 saw large-scale production of polyamide 12 at the Hess Chemical Company in the Federal Republic of Germany. In 1972, the U.S. DuPont realized the industrial production of aromatic polyamides. 70 years later, the modification of polyamides has aroused great interest, especially the development of petrochemical industry, polyamide raw material routes to oil, the cost decreases year by year, the output increases year by year, so that polyamide has developed into a class of varieties, can be adapted to a variety of uses of the Polymer materials.
Performance
PA66 Polyamide 66 or nylon 66 chemical and physical properties PA66 has a high melting point in polyamide materials. It is a semi-crystalline-crystalline material.PA66 maintains its strength and stiffness at higher temperatures. The effect of hygroscopicity on geometrical stability must be taken into account during product design. To improve the mechanical properties of PA66, a variety of modifiers are often added. Glass is the most common additive, and sometimes synthetic rubbers such as EPDM and SBR are added to improve impact resistance. PA66 has low viscosity and therefore good flow (but not as good as
Pa6). This property can be used to machine very thin components. Its viscosity is sensitive to temperature changes.PA66 shrinkage is between 1% and 2%, and the addition of glass fiber additives can reduce the shrinkage to 0.2% to 1% . Shrinkage in the direction of the process and the direction perpendicular to the direction of the process is greater. PA66 is solvent resistant to many solvents, but is less resistant to acids and some other chlorinated agents.
Physical and chemical properties
PA66 plastic raw materials for translucent or opaque opalescent package or with yellow granular crystalline polymer, with plasticity. Density (g/cm3) 1.10-1.14; tensile strength (MPa) 60.0-80.0; Rockwell hardness 118; melting point 252 ° C; embrittlement temperature -30 ° C; thermal decomposition temperature of more than 350 ° C; continuous heat resistance 80-120 ° C; impact strength (kJ/m2) 60-100; static bending strength (MPa) 1 00-120; Martin heat resistance (° C) 50-60; Flexural modulus of elasticity (MPa) 2000-3000; Volume resistivity (Ωcm) 1.83×1015; Equilibrium water absorption 2.5%; Dielectric constant 1.63.
Chemical formula: [-NH (CH2) 6-NHCO (CH2) 4CO] n - can be resistant to acids, alkalis, most inorganic salts, aqueous solutions, halogenated alkanes, hydrocarbons, esters, ketones, and other corrosive
PA66 has a high melting point in polyamide materials. In product design, a PA66 shrinkage between 1% and 2%.
Now circulating on the market with a lot of disposable water through the modification, the same can achieve the physical properties of the original material, while the price is relatively cheaper than the raw material, so that the majority of customers to save a large amount of cost.
Polyamide modification
The main method is to add the appropriate amount of additives in the polymerization process or processing, in order to give the resin a variety of different characteristics, so that it is suitable for a variety of different occasions. Commonly used additives are: ① stabilizers. Including heat stabilizers and light stabilizers, which can respectively improve the oxidation resistance and light resistance of polyamide to produce anti-aging nylon. If you add finely dispersed carbon black 2% (quality), polyamide can be used outdoors for a long time. ② Commonly used glass fiber reinforced materials. Made of reinforced nylon to improve rigidity, reduce creep, and make the molding of the product shrinkage becomes smaller, better dimensional stability. Enhanced with metal fibers, not only high modulus, but also conductive. With minerals also have a good effect of enhancement, and make the processing and molding easy, cost reduction. Molybdenum disulfide and
Polytetrafluoroethylene are also polyamide reinforcing materials, and can improve wear resistance. ③ nucleation additives. Used to produce microcrystalline nylon, can speed up the time of demolding, so that the molding cycle is shortened by 20% to 30%. In addition, depending on the application, plasticizers and lubricants can be added.
Another method of modification is copolymerization, copolymerization of nylon is a good wrapping material and gasket sealing material; polyamide and polyolefin block graft copolymerization, can substantially improve the impact strength and dimensional stability, reduce moisture absorption, and even can be made into easy to process, low-cost plastic products. This effective way to solve the defects of polyamide is one of the directions for the development of modified varieties in recent years.
Uses
Polyamide plastic products are widely used as a variety of mechanical and electrical parts, including bearings, gears, pulley pump impellers, blades, high-pressure seals,
gaskets, valve seats, bushings, oil pipelines, oil reservoirs, ropes, drive belts, wheel adhesive, battery boxes, electrical coils, cable connectors and so on. There are also packaging tape, food film (cooked food high-temperature film and cool drinks with low-temperature film) production is also quite large. Monsanto Company in the United States to develop polyamide plastics for reaction injection molding, also known as RIM nylon, is very much in the spotlight by countries, some countries made of glass reinforced RIM nylon large automotive shell parts, so that the polyamide in the competition with the metal materials, in the automotive manufacturing industry to reduce weight, energy saving and cost reduction has found another way.
The main varieties of polyamide fibers (aliphatic) are nylon 66 and nylon 6, the latter is also known as nylon. They have high strength, good resilience, the highest abrasion resistance in textile fibers, resistance to multiple deformation and fatigue resistance close to polyester, higher than other fibers. They have good temperature absorption, but poor light and heat resistance. Polyamide fiber filament can be made into socks, underwear, shirts, sweatshirts, ski shirts, raincoats, etc.; staple fibers can be blended with cotton, wool and viscose fibers, so that the fabric has good abrasion resistance and strength. It can also be used as Velcro, carpets, decorative fabrics and so on. Industrially it is mainly used to make cord fabric, conveyor belt, fishing net, cable and so on.
