High temperature resistant nylon makes full screen mobile phones stand up
Looking at the current mobile advertising, you will find that "full screen" and "no border" have become the key promotional content of all well-known mobile phone manufacturers.
The full screen is not just to increase the screen. On the back of the invisible mobile phone screen, the high temperature resistant nylon provides a stronger middle frame structure for the full screen mobile phone, bringing both the grip and the visual comfort, while also ensuring The strength of the signal transmission is not affected.
Excellent rigidity, support for the screen
The full screen can make the phone look more cool and more visually immersive, providing users with the ultimate user experience. When playing games, full-screen mobile phones have a broader view than ordinary mobile phones; when watching movies, they can bring a better visual experience; when browsing web pages or swiping microblogs, full-screen mobile phones can display more web content.
With the popularity of large-screen mobile phones, the portability of mobile phones has always been criticized. The development of a full-screen mobile phone can improve the portability of a large-screen mobile phone without reducing the user experience, and make the mobile phone's grip feel better.
The screen of the mobile phone is getting bigger and bigger, satisfying the visual enjoyment of people, but it adds to the burden of the hand. In order to reduce the weight, a circle around the screen of the mobile phone needs to adopt a narrow border or even a borderless design. Without the support of a circle around the screen, the phone must have a stronger middle frame structure to ensure the stability of the screen. This requires the plastic parts behind the screen to provide support for superior rigidity to meet the screen's need for support.
In addition, the post-processing processing temperature of the middle frame of the mobile phone can reach 180 ° C, which requires the nano-injection material used in the middle frame to withstand high temperatures. At this point, high temperature nylon can show its strength.
High temperature resistant nylon is a high temperature resistant nylon made by polycondensation of terephthalic acid and hexamethylene diamine. It has low water absorption, excellent heat resistance, good processing fluidity, low expansion coefficient, excellent chemical resistance, and metal. High bonding strength, etc., is the best choice for making mobile phone frames. The high temperature resistant nylon has a heat distortion temperature of over 270 ° C, and its high crystallinity allows it to maintain excellent rigidity at high temperatures, ensuring adequate support for the screen.
Good extensibility, making mobile phone design diverse
Polycarbonate (PC) plus glass fiber has been widely used in mobile phone frames. With the rise of borderless large-screen mobile phones, the frame of the mobile phone has higher requirements on dimensional accuracy, dimensional stability and low warpage, while the glass fiber reinforced PC has insufficient rigidity, is prone to distortion or tensile deformation, and the mobile phone. The lack of bonding strength of the metal part is insufficient to meet the demand for a borderless mobile phone.
According to Dr. Cao Yanxia from Shenzhen Hualixing New Materials Co., Ltd., compared with ordinary nylon 66 and nylon 6, the high-temperature resistant nylon has a low water absorption of 2/3, and the dimensional change caused by moisture absorption is small. At the same time, due to its excellent temperature resistance, the coefficient of thermal expansion is comparable to that of metal or aluminum, and the rigidity is good. The change of high and low temperature causes little warpage and dimensional deformation, and has excellent dimensional stability and low warpage. Therefore, the high temperature resistant nylon is fully capable of functioning as a structural member of a full screen mobile phone to provide the support force required for the mobile phone.
Cao Yanxia said that high temperature resistant nylon is suitable for nano-injection molding, which can achieve integrated molding, so that the appearance of the product not only balances the metal texture, but also ensures the overall structural strength and makes the product details more perfect. The same strength as high temperature resistant nylon aluminum, the same hardness as steel, and the same flexibility, ductility and impact resistance of rubber make the design space of mobile phones even larger.
In addition, PC plus fiber is sensitive to stress, it is easy to crack when tested for glacial acetic acid before spraying, and it is not resistant to acid and alkali. The high temperature resistant nylon has excellent chemical resistance and excellent resistance to chemical solvents due to its tight crystal arrangement and high permeation performance, and is resistant to corrosion by chemicals such as acid and alkali. High temperature resistant nylon plus glass fiber suspension fiber with little or no floating fiber, can be sprayed or plated without affecting surface quality.
Cao Yanxia believes that in the comprehensive screen plastic material, high temperature resistant nylon can make up for the shortcomings and defects of glass fiber reinforced PC performance, and it is cost-effective, especially suitable for high-precision mobile phone middle frame structure materials.
Copolymerization modification communication signal is not affected
The design of mobile phones is getting thinner and thinner, and the popularity of full-screen screens makes the space inside the mobile phone parts smaller, and the signal transmission of mobile phones is increasingly restricted. The influence of the dielectric constant of the middle frame material on the signal of the mobile phone is much more obvious than before. Only materials with a dielectric constant below 3.5 can meet the requirements of mobile phone signal transmission.
Wang Aiguo, general manager of Jiangmen Dezhongtai Engineering Plastic Technology Co., Ltd. introduced that the dielectric constant of high temperature resistant nylon is between 3.3 and 3.8. In order to simplify the process and save manufacturing costs, some mobile phone middle frames adopt a steel-free structure, which puts higher requirements on the strength of plastic materials. The high-temperature nylon copolymerized with a small amount of PA12T semi-aromatic nylon can be used to produce a steel-free middle frame. While ensuring the rigidity of the middle frame, the antenna signal is not weakened, and normal communication is not affected.
Ordinary mobile phones are generally built-in antennas, while full-screen mobile phones use LDS antennas that are printed directly on the phone case. LDS is a technology that uses a digitally controlled laser to directly print a circuit pattern on a plastic surface. It has the advantages of short processing time, high precision, and the circuit pattern is not limited by the geometry of the physical device. In order to use the LDS antenna, the mobile phone must consider the processing requirements of LDS, such as thermal expansion coefficient, water absorption, etc., to ensure that the plastic casing can meet the processing conditions of the LDS antenna.
Xue Xiaoping, application development manager of Aimans (Suzhou) Engineering Plastics Co., Ltd., said that high temperature nylon has high melting temperature, high stiffness and strength at high temperature, low creep, good dimensional stability and high flame retardant performance. It still maintains a good appearance at low mold temperatures. This feature is ideal for LDS processing needs and is suitable for lead-free soldering SMT processes.
According to reports, the high temperature resistant nylon has no foaming, low warpage, etc. after lead-free soldering, and the radio signal loss is very low. High temperature resistant nylon can also be used in the smart watch LDS three-dimensional circuit laser laser engraving antenna and plastic shell material to ensure the antenna signal functions of GSM, WIFI, GPS, Bluetooth, etc., so that the smart watch is not only fashionable and diverse, but also soft, feel good and comfortable to wear. .
Article link: China Plastic Online http://info.21cp.com/Gaixing/Zixun/201810/1468575.htm