Polyamide commonly known as nylon, dibasic acid and diamine or amino acid polycondensation derived, is a molecular chain containing repeated amide groups -NHCO- resin .Nylon is the five largest general-purpose engineering plastics in the largest output, the largest variety, The most widely used, excellent overall performance of the basic resin.
Nylon, as an important engineering plastic, is continuously being improved by physical and chemical modification.Now many areas have put forward new requirements for high temperature resistance of materials, and in order to meet these requirements, New high temperature nylon has done a lot of research.
The definition of high temperature nylon
High-temperature nylon (HTPA) is a heat-resistant polyamide that can be used for a long time in the environment of 150 ° C. It has good performance in heat, electricity, physics and chemical resistance, especially high temperature Steel and high strength and excellent dimensional accuracy and stability.
High temperature nylon properties
1, high temperature performance. Heat deflection temperature of 280 ℃ (1.8MPa), continuous use temperature of 180 ℃.
2. Creep properties HTPA's high crystallinity allows it to maintain excellent rigidity at elevated temperatures (> 120 ° C), aluminum-like strength, steel-like hardness and rubber-like flexibility, ductility and impact resistance.
3, excellent dimensional accuracy and stability. Molecular structure of HTPA molecular chain contains aromatic ring, the molecular structure is more regular, the chain is more difficult to exercise.
4, chemical resistance Polyamide material for most chemicals have good resistance.As with other polyamide materials, HTPA is no exception, especially in high temperature oil and grease is very good.
5, Hygroscopicity HTPA fiber reinforced products have low moisture absorption, the water absorption rate is only half of the same amount of glass fiber reinforced PA46 products. This low moisture absorption can save customers more drying costs, and the size of products Stability is better.
6, toughness. HTPA excellent impact toughness makes it a high demand for the production of choice of materials.
Traditional high temperature nylon types and properties
PA46
PA46 is an aliphatic polyamide polycondensed from butanediamine and adipic acid. The number of amides per chain of a given length of PA46 is more than that of PA6 and PA66, and the chain structure is more symmetrical, rendering its crystallinity Degrees can be as high as 70%, and gives it very fast crystallization speed.
PA46 has a melting point of 295 ° C. The unmodified PA46 has an HDT (heat distortion temperature) of 160 ° C. After glass fiber reinforcement, the HDT can reach 290 ° C and the long-term use temperature is 163 ° C.
PA46 unique structure gives unique properties that other materials can not be achieved as the owner of the PA46 property, DSM companies are gradually its excellent performance through continuous modification and put into commercialization. In ensuring its high temperature performance , A variety of special applications such as super wear-resistant, ultra-high rigidity, ultra-high liquidity, etc. have been continuously developed.
In terms of heat resistance, DSM introduced its new high-performance STAN YL Diablo at Chinaplas 2008, which has long-term thermal stability and can operate normally for more than 3000 hours at a high temperature of 230 ° C, with less than 15% reduction in mechanical properties %.
PA6T
PA6T is a typical representative of semi-aromatic nylon, is the condensation of hexamethylenediamine and terephthalic acid from pure PA6T melting point up to 370 ℃, at this temperature nylon has been degraded, can not be thermoformed, so the market Circulating PA6T are copolymers or complexes that decrease the melting point after copolymerization with other monomers.
PA6T introduced a large number of benzene rings on the basis of the aliphatic chain, PA6T has higher Tg, lower water absorption, dimensional stability and high heat resistance compared with the traditional PA6 and PA66, etc. Since the PA6T needs to introduce other monomers To copolymerization to reduce the melt processing temperature, different monomer ratio becomes the key PA6T modification, it can be said that the PA6T high temperature modification has a great room for development.
Shanghai Jie Jie company has also successfully issued a PA6T series of high temperature nylon, and has been put into production.
PA9T
PA9T is developed by Japan's Kuraray Co., Ltd. It is made of nonanediamine and terephthalic acid polycondensation.Although PA9T is the same semi-aromatic nylon, PA9T does not need to be copolymerized to reduce the melting point like PA6T before processing, The pure PA9T has a melting point of 306 ° C. The high glass transition temperature (125 ° C) and high crystallinity of PA9T give it good toughness at elevated temperatures.
At the same time, it also has the incomparable chemical properties of other PA materials, second only to PPS, and its water absorption rate of only 0.17%, which is the lowest among all PA PA9T overall performance is undoubtedly the better heat-resistant nylon one However, with the continuous expansion of production scale, the cost of PA9T will be close to the cost of ordinary PA, so PA9T is a product with great potential for development.
The latest high-temperature nylon
PA66
Although PA66 has a relatively low Tm and Tg compared to conventional high-temperature nylon and appears to limit its use in high-temperature applications, Rhodia France considers it as a high-end application material. In 2007 K At the show, Rhodia introduced the TECHNYL Heat Performance (HP), a PPA alternative for high-temperature environments, which meets the performance requirements of automotive hoods at elevated temperatures.
Allegedly, the material also maintains the processing properties of nylon 66 at the cost of nylon 66. This technology has given PA66 a new development in the field of high temperature resistance, but only Rhodia is currently in possession of the technology.
PA4T
DSM, the world's leading producer of high-temperature nylon (PA46), has the world's only commercial solution of butane diamine, a key feedstock for the synthesis of PA46, which has led DSM to pioneer the use of this as a feedstock PA4T products.
The first new polymer of the 21st century, with excellent spatial stability, lead-free solder compatibility, high melting point, high hardness and mechanical strength in the event of a temperature increase, Of the PA46 product, or even PA9T, it shows the ultra-low water absorption.
PA4T comprehensive and excellent performance, it will make it in the future, high-temperature applications such as electrical and automotive applications occupy an important part of the PA4T invention is also the market miniaturization and electronic products to the performance of the material higher requirements of the embodiment.
PA10T
The results show that pure PA10T with a high melting point of 319.1 ℃, its excellent heat resistance PA10T showed a potential commercial value.
Domestic plastic modification leading enterprises - Blonde technology commercialization of this technology, its grade is PA10T Vicnyl products, it has excellent heat resistance, ultra-low water absorption, better dimensional stability, resistance to lead-free solder Temperature up to 280 ℃, excellent chemical resistance and injection molding processability.
Allegedly, PA10T resin nearly half of raw materials from castor, is a bio-based environmentally friendly materials, excellent overall performance, showing a strong market competitiveness. PA10T product commercialization, to fill our country in high temperature nylon new material Independent research and development on the blank, and Blonde Company has also become the following Shanghai Jie Jie company, the country has the second high temperature nylon industrialization technology unit.
Other PPA materials
PPA (semi-aromatic nylon) is made by polycondensation of aliphatic diamines or diacids with diacids or diamines with aromatic rings.In addition to the materials PA4T, PA6T, PA9T and PA10T as described above, PAMXD6, PA12T and many other PPA varieties.These nylon materials have the aromatic ring structure in the chemical structure, to varying degrees, to increase the heat distortion temperature.While DuPont company with dimethyl terephthalate (DMT) and dodecylamine (DDMD ) Synthetic PA12T, melting point of 296.6 ℃, with strong application value.
High temperature nylon applications
HTPA is an ideal engineering plastic for heat-resistant parts in the automotive, mechanical, electrical / electronic industries because HTPA offers a heat distortion temperature of over 270 ° C. In the meantime, for systems that must maintain structural integrity at short-term high temperatures Pieces, HTPA is also the ideal choice. Common products in the following table:
