Polyimide resin, polyimide film and preparation method and application thereof

Abstract

The invention relates to a polyimide resin, a polyimide film and a preparation method and application thereof, the polyimide resin has a structural general formula as shown in formula (I), in the formula, A is a dianhydride residue, and B is a diamine residue; a fluorine side group is introduced into an aromatic ring, so that the water absorption and moisture absorption of diamine can be greatly reduced, and the water absorption of the polyimide film is reduced; and a fluorine side group on fluorine-containing diamine directly replaces a hydrogen atom on a benzene ring, the heat resistance and the coefficient of thermal expansion (CTE) of polyimide cannot be affected, the prepared polyimide film is good in heat resistance and low in coefficient of thermal expansion, the application field of polyimide can be expanded through introduction of the fluorine-containing side group, the polyimide can be used in display substrates, solar cell substrates, and the like, the tensile strength of the prepared film is larger than or equal to 300 MPa, and the elastic modulus of the film is larger than or equal to 8 GPa.

Description

Technical field [0001] The present invention belongs to the technical field of polyimide film, and more particularly to a polyimide resin, a polyimide film, and a preparation method thereof. Background technique [0002] With the rapid development of the monitor, there are some new development trends, such as surface TV, foldable mobile phones, folding display of car equipment, etc., in these areas, traditional hard displays substrate glass The metal has been difficult to meet the applications of these emerging markets, and turn over to the flexible substrate to achieve a flexible and foldable, which is currently possible as a material of the flexible substrate comprising polycarbonate, polyethylene glycol ester, polyether sulfone. , Polyimide and other high molecular films. Among them, the polyimide substrate has received attention with its excellent high temperature resistance, chemical resistance, and high insulating properties. [0003] The preparation process of the flexible...

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Problems solved by technology

[0003] The preparation process of the flexible display substrate mainly uses glass as the substrate, and the polyimide resin or diluted solution is coated on the glass substrate, and then the polyimide film is obtained by curing at high temperature, and then the surface of the polyimide is processed. Evaporation of transparent conductive medium, shielding layer and encapsulation cover method, etc., and finally remove the glass substrate of the whole device by laser lift-off (LLO), so as to obtain a display with polyimide film as a flexible substrate, wherein the entire preparation process They are all carried out in a vacuum that isolates oxygen and moisture. This is mainly due to the performance of the light-emitting organic monomer. The light-emitting organic monomer is particularly sensitive to oxygen and water vapor. After encountering oxygen and water vapor, its use The lifespan is greatly shortened, which also seriously affects its luminous efficiency, which requires that the substrate used must have excellent low water absorption and air isolation capabilities.

[0004] In the application of polyimide, the most important performance is the CTE of the film. It is necessary to ensure that the thermal expansion coefficient of the polyimide film is consistent with or close to the CTE of the attached substrate. For example, LG Chemical Company KIM B et al. [US2007023874] PDA and ODA are used as diamine monomers to react with aromatic dianhydrides to prepare polyimide resins. The CTE of the film is controlled by adjusting the content of PDA. However, as the content of PDA increases, the water absorption of the film gradually increases. , which seriously affects the application of its resin in the field of flexible display

In the patent [US2009197068-A1] of Japanese UBE company HISANO et al., polyimide resin solution and its film are prepared by polycondensation of rigid dianhydride BPDA and rigid diamine PDA. The film has a very low coefficient of thermal expansion, but due to PDA The hygroscopicity of the prepared film leads to a high water absorption rate, which also seriously affects its application in the display field.

In the patent of Yang Shiyong et al. [CN105601923A] of the Institute of Chemistry, Chinese Academy of Sciences, problems such as water absorption and elongation at break of the film are reduced by adding fluorine-containing monomers and blocks, but the fluorine in the fluorine-containing diamine in this invention It exists in the form of trifluoromethyl, which has a great influence on CTE and heat resistance. The toughness of fluorine-containing monomers is too high, and the tensile strength and elastic modulus of the prepared film are low. The temperature performance is poor, which seriously affects the heat resistance and mechanical properties of the film, and its application range is also limited.

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