polyamide
DATE：2022/7/27 9:14:44 / READ： / SOURCE：This station
polyamide
Polyamide (a) is a thermoplastic polymer compound with acylamine group (HNCO) repeating structural units on the main chain, which is usually called nylon. PA is the abbreviation of polyamide. Polyamide is an engineering plastic with a large amount of applications and a wide range of uses. There are many varieties of polyamides, which are mainly classified and named according to the number of carbon atoms of synthetic monomers, including a6pa11, PA12, pa13, PA66, PA610, pa612, PA1010, etc. Polyamide varieties used more in plastic products are PA6, PA66, PA610 and PA1010. (1) Properties and characteristics polyamide is a light yellow to amber transparent solid, non-toxic and tasteless. Most polyamides can burn slowly in the fire source, and can self extinguish after leaving the fire source. When burning, they bubble, giving off a kind of burnt wool smell; It has high water absorption, which reduces the strength of products and affects the dimensional stability; It has excellent mechanical properties, good impact strength and tensile strength, good friction resistance and wear resistance; Due to the poor thermal stability of products, they can only be used below 80~100 ℃; Resistant to a variety of chemicals, not affected by weak acids, weak bases, alcohols, esters, hydrocarbons, lubricants, gasoline and grease; Soluble in ethylene glycol, glacial acetic acid and chloroethanol at room temperature; The electrical performance is relatively poor, which is only suitable for power frequency insulation materials. (2) Molding method and application polyamide can be used to mold products by injection molding, extrusion, extrusion blow molding, pouring, molding, rotary molding, foaming, coating, welding, bonding and other methods. The main products are accessories on machinery, instruments and meters, automobiles, textile machinery and other equipment, such as bearings, gears, oil pipes, oil tanks, chemical engineering products, electronic and electrical products, cams, turbines, parts for pumps and valves, gaskets, cable wrapping, automotive parts, fan blades, films for medical supplies and food packaging, etc. (3) Key points of molding process raw materials should be dried before the production of molded products to make their water content less than 0.06%; In order to prevent the products from being oxidized and brittle at high temperature, carbon black and ultraviolet absorbent can be added to the molding raw materials to improve the aging resistance; Plasticizers such as aliphatic diols and aromatic chlorosulfonates should be added to the raw materials when forming hose and cable connector products; In order to improve the mold filling of melt and the demoulding of finished products, a small amount of paraffin or metal soap lubricants can be added to the raw materials. Adding a certain proportion of glass fiber or mineral fillers and reinforcing modifiers to the raw materials can increase the rigidity of products, reduce high-temperature creep and shrinkage, reduce water absorption, and improve the dimensional stability, impact strength, wear resistance and flame retardancy of products.2.4.1 polyamide
Polyamide 6, also known as polycaprolactam or nylon 6, is a milky white or yellowish transparent or opaque crystalline polymer. Excellent wear resistance and self lubrication, good colorability and toughness, small rigidity, low temperature resistance, bacteria resistance, slow burning and slow quenching after leaving the fire source; The molding processability is very good, and the products can be molded by injection, extrusion blow molding, pouring, spraying, powder molding, machining, welding, bonding and other methods. The injection molding temperature is 215 ℃, and the mold temperature is about 90 ℃; High water absorption, poor dimensional stability of products, shrinkage between 1%~1.5%, and affect electrical properties; The maximum operating temperature can reach 180 ℃. The pouring temperature of monomer is 160~170 ℃, and polymerization lasts for 20~30min.
2.4.2 polyamide
Polyamide 66 is also called polyhexamethylene hexamethylene diamine or nylon 66. It is prepared by condensation polymerization of adipic acid and hexanediamine. Polyamide 66 is a translucent or opaque milky crystalline polymer. When exposed to ultraviolet light, it will emit purple white or blue white light, and the product quality of PA66 is higher than that of other polyamide products; Environmental stress cracking resistance, heat resistance and low temperature resistance are good (decomposition temperature is 350 ℃, embrittlement temperature is -30 ℃); Good chemical resistance and flour preparation, but easily soluble in polar solvents such as phenol and formic acid; The water absorption is about 2.5%, and the dimensional stability is poor, but the molding processability is good. Many kinds of human molding products such as injection, extrusion and blow molding can be used. The temperature of injection melt is about 275~295 ℃.
2.4.3 Polyamide 1010
Polyamide 1010 is also called polydecadienyl decanediamine or nylon 1010. Sebacic acid and sebacate were prepared from castor oil by polycondensation. PA1010 is a translucent, light and hard crystalline white or yellowish particle with bright surface; The density and water absorption are lower than those of PA6 and PA66; Non toxic, low temperature resistant, mold resistant, embrittlement temperature -60 ℃; High mechanical strength, impact toughness, wear resistance, self lubrication, dielectric, chemical stability, cold resistance is better than PA6; During molding, the melt has good fluidity and is easy to form, but the contact between the melt and oxygen is very easy to cause thermal oxidation degradation; Products exposed to oxygen at 100 ℃ for a long time will gradually appear yellowish brown, and the mechanical strength will decrease; It is insoluble in hydrocarbons, lipids and lower alcohols, but soluble in polar solvents such as phenol, concentrated sulfuric acid and formic acid.
2.4.4 polyamide 610
Polyamide 610 is also called poly (Decanoyl hexamethylene diamine) or nylon 610. PA610 is an extrusion molding process of hexamethylene plasticIt is formed by condensation polymerization of the salt formed by neutralization of the amine and sebacic acid; It is a translucent, milky white thermoplastic polymer, and its properties are shown in table 2-99; Compared with PA6 and PA66, it is small, water absorption is small, the dimensional stability of the product is better, and the molding and processing is easier. Alkali is more resistant to weak acids and general solvents than PA6 and PA66, but it is soluble in phenols and Tanaka, and it is a self extinguishing material. When injection molding products, the melt temperature is 230~260 ℃, 70~140mpa, and the mold temperature is 60~90 ℃. The melt temperature of extrusion molding is 23270 ℃.
2.4.5 monomer pouring nylon
Monomer cast nylon, also known as monomer cast caprolactam or MC nylon, is a component material. The molding process is similar to the metal pouring molding process. The raw materials are directly injected into the preheated mold for rapid polymerization reaction and solidification molding to make MCPA cast nylon. It is mainly used for pouring large parts, such as gears, valve seats, guide rails, bearings, electrolytic cells and support frames, which are machined and formed. The products have the characteristics of high strength, good rigidity, wear resistance, oil resistance, corrosion resistance, easy forming and light weight.
2.4.7 copolymer nylon
The chemical name of copolymerized nylon is polyamide copolymer, which is a copolymer of two or more nylon monomers. Copolymerized nylon has low melting point and knot degree and is elastic. Its component properties vary with the type and ratio of monomers. See table 2-102 to table 2-105 for performance. Injection, extrusion, casting and other methods can be used to shape products, which are similar to general nylon, such as injection molding industrial parts, extruded plates, cast films and other products.
2.4.8 other polyamide resins
(1) Polynonylamide is commonly known as nylon 9. PA9 has smaller water absorption than PA6, outstanding aging resistance, low melting point, and dimensional stability than PA11 and PA12. It is generally used for engineering products such as machinery and automobiles, and wire and cable sheaths. (2) Polyundecylamide is commonly known as nylon 11. It is generally used for extrusion film, casing film, oil pipe, injection molding machinery, construction equipment and other parts. The products have the characteristics of low density, low water absorption, dimensional stability, flexibility and good low-temperature impact resistance. Due to its low melting point and wide processing temperature range, it is often used by tape casting and powder forming methods, as well as surface electrostatic powder coating and flame spraying. (3) Poly (laurolactam) is also called polyamide 12 or nylon 12. Its products have good dimensional stability, cold resistance, softness, low density, low water absorption, and can adhere to the metal surface. The forming method and products are the same as those of PA6. (4) Polyamide modified resin ① glass fiber reinforced polyamide cuts the glass fiber through the twin-screw extruder, and can be blended with any PA resin and melt extruded to form pellets. Generally, it can be divided into long glass fiber method and short glass fiber method (the long glass fiber method is to plasticize and melt PA resin in the extruder, and simultaneously send the treated glass fiber melt resin into the extruder for mixing. After cutting and kneading in the extruder, the glass fiber is reeled and evenly dispersed in PA resin, and then extruded and diced. After the glass fiber with short glass fiber dimension surface treatment is chopped, it is added into the extruder at the same time with the resin to melt the appearance and package, and then extruded and diced). This kind of granular material can be molded by injection and extrusion. The properties of impurities and products in hygroscopicity, mechanical properties, thermal properties, dimensional stability and thermal deformation moisture content are significantly improved compared with those of basic PA materials. Relative tensile strength 2 filled polyamide filled polyamide is also called filled nylon. According to different filler materials, it can improve the wear resistance, self lubrication, flame retardancy and aging resistance of PA products, improve heat resistance, rigidity, toughness and dimensional stability, and reduce the production cost of products. If carbon black is added to polyamide, aging resistant nylon products can be made; If graphite or molybdenum disulfide is added to polyamide, it can be made into wear-resistant nylon products.
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