In 2018, Rouyu technology and Samsung respectively released mobile phones with foldable screens. Unlike the ordinary "hard" smart phones, the foldable mobile phone uses a flexible display touch screen, so consumers can easily bend and twist!
An analysis report points out that the flexible display screen mainly uses polyimide (PI) instead of glass as the substrate, which makes the screen flexible and turns the hard screen into soft screen.
Polyimide (PI) is a kind of polymer containing cyclic imide group in molecular chain. It has the advantages of high temperature resistance, low temperature resistance, high strength and high modulus, high creep resistance, high dimensional stability, low coefficient of thermal expansion, high electrical insulation, low dielectric constant, low loss, radiation resistance and corrosion resistance.
At the same time, it has the characteristics of low vacuum volatilization, less volatile condensate and other space materials. It can be processed into polyimide film, high temperature engineering plastics, matrix materials for composite materials, high temperature resistant adhesives, fiber and foam materials .
Polyimide products are mainly composed of thin films, coatings, fibers, engineering plastics, composite materials, adhesives, foam plastics, separation membranes, liquid crystal aligning agents, photoresists and so on. They can be applied to aerospace, electrical insulation, liquid crystal display , automotive medical, atomic energy, satellites, nuclear submarine, microelectronics, precision machinery packaging, etc.
Among them, polyimide film is the earliest and most mature product in polyimide series. Polyimide films of electronic grade and below have achieved self-sufficiency in China, and the market of polyimide films of electronic grade and above is still mainly divided up by overseas companies .
The development of technology cannot be separated from the progress of materials. How to adjust the material properties to meet the needs of folding mobile phone screen performance? How to develop high quality polyimide film to promote the popularity of folding mobile phone?
As early as a long time ago, scientists have studied zirconium phosphate materials used in fuel cell proton exchange membrane. The thermal stability, chemical stability, mechanical properties and proton conductivity of pi / ZRP composite membrane were improved by preparing pi / ZRP composite membrane.
The results show that the residual amount of the composite film increases with the increase of doping amount at 600 ℃. The thermal stability of the composite film can be improved by adding 5% ZRP.
Based on the same principle, zirconium phosphate has been applied in polyimide film of engineering plastics in some scientific research institutions. The high temperature resistance and flame retardancy of the film can be improved by compound experiment. Zirconium organophosphate was prepared by simple intercalation reaction. The tensile strength and wear resistance of the film were improved by adding 3% zirconium organophosphate.
But at present, this technology has not been able to meet the demand of mass production. But we have reason to believe that before the widespread popularity of folding mobile phones, before the arrival of 5g, this technology will get a breakthrough.
We have reason to believe that through the efforts of many researchers, China will definitely break through the blockade of technical barriers and complete the counter attack of high-performance polyimide film production!http://www.china-polyimide.com