Preparation method of black extinction polyimide film

Abstract

The invention relates to a preparation method of a black extinction polyimide film. The preparation method mainly comprises the following steps: (I) conventionally preparing a polyamide acid resin solution; (II) preparing black slurry, wherein the amount of a black pigment is 2wt%-20wt% of a solid content M of the polyamide acid resin solution; (III) preparing a black polyamide acid resin solution, blending and stirring the polyamide acid resin solution with the black pigment, and carrying out defoaming for later use; and (IV) salivating the black polyamide acid resin solution to a steel belt,carrying out high-temperature surface treatment at 300-400 DEG C for 5-90 seconds during drying, and carrying out stretching, imidization and formation, so as to obtain the black extinction polyimidefilm. An extinction agent dispersing solution containing 2wt%-20wt% of the weight M of an extinction agent can be added in the step (III). The black pigment and the extinction agent are moderate in average grain diameters, and high-temperature surface treatment is additionally carried out during the salivation formation of a resin solution, so that the light transmittance, glossiness and physicaland mechanical properties of the obtained film are obviously improved.

Description

technical field [0001] The invention relates to a polyimide film manufacturing technology, in particular to a method for preparing a black matte polyimide film. Background technique [0002] Flexible printed circuit board (FPC) is widely used in 3C products, optical lens modules, liquid crystal display (LCD) modules and solar cells and other products, and polyimide film (Polyimide Film, referred to as PI film) is often used as its substrate Or cover film material, due to the high surface flatness of the traditional PI film in the application process, the surface of the film reflects most of the incident light and produces high gloss. The high-gloss film surface has glare or astigmatism caused by light reflection, which causes visual discomfort and easily fatigues the eyes when watching for a long time. Especially for high-gloss PI film polyimide films with black, white, blue, red and other colors, the reflected light on the surface has a more significant impact on vision. ...

AI Technical Summary

Problems solved by technology

Since the chemical conversion temperature must exceed 250°C during the preparation of polyimide films, none of the above organic compounds can withstand temperatures of 250°C or higher.

When such organic compounds are added to the polyimide film as a matting agent, it will cause defects such as cracks or holes in the film, or uneven color spots due to uneven melting

[0009] At present, the main production technology of matte black PI film is divided into two categories: one is to add black pigment and matting agent filler to PI resin, and then undergo chemical imidization or thermal imidization to synthesize a film with low light transmittance and Low-gloss PI film, this method is easy to operate and the effect is obvious, but due to the addition of a large amount of fillers, the mechanical properties of the PI film are greatly reduced; the other is to coat one or both sides of the PI base film Coated with a PI film containing black pigment and matting effect

Though this kind of method can make polyimide film present desired black effect preferably, and can guarantee the certain mechanical performance of polyimide film, but the black resin of additional coating usually increases manufacturing process and cost, and Detrimental effect on the properties of polyimide film

In addition, polyimide films are prone to performance degradation when exposed to thermal stress due to the poor heat resistance of the resin coating layer

There are many patent applications related to the manufacture of low-gloss black polyimide films, but they are difficult to implement due to defects such as complex manufacturing processes, high production control precision requirements, and high manufacturing costs.

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