A preparation method of low-shrinkage, high-hardness, high-wear-resistant transparent polyimide hardened film

Abstract

The invention belongs to the technical field of transparent polyimide hardened films, and in particular relates to a method for preparing a transparent polyimide hardened film with low shrinkage, high hardness and high wear resistance, comprising the following steps: (1) uniformly coating a hardening liquid on On the transparent polyimide substrate, thermal drying and thermal curing are performed; (2) UV curing is performed, and then annealing treatment is performed. After the hardened film is cooled, the protective film can be attached and cut. The present invention adopts a dual-curing method, firstly by thermally initiating free radical prepolymerization, since thermal curing is to prepolymerize monomers and oligomers first, most of the shrinkage stress will be generated, and there is still solvent in the system after thermal curing , which can effectively eliminate the shrinkage stress generated by polymerization, thereby effectively avoiding shrinkage during thermal curing. In addition, since there is still solvent in the system after thermal curing, thermal curing will not warp, and then UV curing at a lower temperature can be carried out. Effectively reduces volume shrinkage and warpage that occurs during curing.

Description

technical field [0001] The invention belongs to the technical field of transparent polyimide cured film, and in particular relates to a preparation method of a low-shrinkage, high-hardness and high-wear-resistant transparent polyimide cured film. Background technique [0002] Curved screen technology has been widely valued and sought after by consumers and the industry in recent years. In the future, with the continuous development and improvement of fixed-curvature curved screen technology, flexible touch screens that can be bent arbitrarily will become an important development direction. Although the flexible screen can be bent, if it is bent frequently, it will have the same fatigue problem as metal paper. If it is bent multiple times and used for a long time, the flexible screen may be damaged by creases in the middle of the screen after being subjected to multiple compression and tensile stresses. In addition, circuit boards, components, after being subjected to a lot...

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Problems solved by technology

If it is bent multiple times and used for a long time, after the flexible screen is subjected to multiple compression and tensile stresses, crease damage may appear in the middle of the screen

In addition, circuit boards, components, after being subjected to a lot of bending and non-bending, may also cause damage or other failures during folding

The existing glass panel cannot meet its high frequency requirements, and the transparent polyimide (CPI) film is used to replace the existing glass cover plate because of its good foldability, but polyimide (PI ) The material cannot meet the hardness requirements, and it is necessary to add a hardened film on the surface of the PI film to enhance the hardness

[0003] At present, there are two main problems in the research and development of flexible screen hardening film: one is the contradiction between high hardness and low warpage. Linkage, while conventional vinyl monomers will cause volume shrinkage during the UV curing process, the greater the degree of crosslinking, the more serious the volume shrinkage; the second is the contradiction between high hardness and bendability, through a large number of high-functionality monomers After increasing the cross-linking density to obtain high hardness, the hardened film is usually brittle, and it needs to be properly matched with flexible monomers to improve toughness, and the structure and quantity of flexible monomers will affect whether the hardened film can finally have good bendability. very important

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