High reflectivity pi coverlay and method of making

Abstract

The application provides a high-reflectivity PI cover film and a preparation method, and relates to the technical field of white cover films.The high-reflectivity PI cover film is composed of a white ink layer, a polyimide film layer, an insulating layer and a release layer, wherein the white ink layer is prepared by compounding rutile titanium dioxide, an epoxy-modified polyester resin, sodium glutamate, an epoxy resin, an additive, butyl acetate, a diluent, melamine, polyurethane and the like.The application overcomes the shortcomings of the prior art, effectively improves the reflectivity of the surface of the PI cover film while guaranteeing the basic performance of the PI cover film, and comprehensively improves the market value of the PI cover film.

Description

Technical Field

[0001] This invention relates to the field of white cover film technology, specifically to a high-reflectivity PI cover film and its preparation method. Background Technology

[0002] PI cover film is a functional material that combines the excellent properties and characteristics of polyimide (PI) film. It has important application value in scenarios that require high temperature resistance, insulation, flexibility and high reflectivity at the same time. It is mainly used in the aerospace, electronics and new energy fields.

[0003] For various fields, the reflectivity of PI (polyimide) cover films is also one of the relevant testing standards. PI cover films can be used in the aerospace industry as thermal control or protective materials for spacecraft; high-reflectivity PI cover films help reflect sunlight and reduce the surface temperature of the spacecraft. In the electronics field, in flexible printed circuit boards (FPCs), PI cover films serve as a key layer for protecting circuitry, providing insulation, and offering bending resistance. High-reflectivity PI cover films can be used in electronic components or devices that require light reflection, such as optical sensors and reflective displays. In the new energy field, in solar cells, high-reflectivity PI cover films can serve as a back reflective layer, improving the light absorption efficiency of solar cells. Developing PI cover films with even higher reflectivity can better meet market demands and provide excellent materials for practical applications in various fields. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-reflectivity PI cover film and its preparation method, which effectively improves the reflectivity of the PI cover film surface while ensuring the basic performance of the PI cover film, thereby comprehensively enhancing the market value of the PI cover film.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A high-reflectivity PI cover film, wherein the cover film comprises, from top to bottom, a white ink layer, a polyimide film layer, an insulating layer, and a release layer; the white ink layer is composed of the following raw materials in parts by weight: 20-30 parts rutile titanium dioxide, 30-35 parts epoxy-modified polyester resin, 3-5 parts monosodium glutamate, 4-8 parts epoxy resin, 3-3.6 parts additives, 25-30 parts butyl acetate, 3-8 parts diluent, 1-2 parts melamine, and 2-2.4 parts polyurethane.

[0006] Preferably, the thickness of the white ink layer is 15-20 μm, the thickness of the polyimide film layer is 11-13 μm, and the thickness of the insulating layer is 8-12 μm.

[0007] Preferably, the insulating layer is an epoxy adhesive; the release layer is release paper or release film.

[0008] Preferably, the additives are equal masses of dispersant, leveling agent, and defoamer.

[0009] Preferably, the diluent is butanone.

[0010] The preparation method of the high-reflectivity PI coating film includes the following steps: (1) Place the epoxy resin in ethylene glycol monoethyl ether, heat it to 70-80℃, stir it thoroughly and then add sodium glutamate for heat preservation reaction treatment, then filter and remove the solvent by vacuum distillation to obtain modified epoxy resin. (2) After thoroughly mixing rutile titanium dioxide with epoxy modified polyester resin and butyl acetate, pressurize to 2-4 MPa and let stand for 30-40 minutes, then restore to normal pressure to obtain the mixture for later use. (3) Mix the mixture with the additives, diluents, melamine, polyurethane, and modified epoxy resin, and stir thoroughly to obtain white ink for later use; (4) After uniformly coating the white ink on the front side of the polyimide film, bake and cure to form a white ink layer; (5) Apply an epoxy adhesive to the reverse side of the polyimide film, bake it to semi-cur to form an insulating layer, and then apply a release layer to the outside of the insulating layer to obtain a high reflectivity PI cover film and then roll it up.

[0011] Preferably, the heat preservation reaction time in step (1) is 4-6 hours.

[0012] Preferably, the method for thoroughly mixing in step (3) is to mechanically stir at a speed of 800-1000 r / min for 15-20 min.

[0013] Preferably, the baking and curing temperature in step (4) is 130-180℃.

[0014] Preferably, the semi-curing temperature in step (5) is 80-120℃.

[0015] This invention provides a high-reflectivity PI coating film and its preparation method, which has the following advantages compared with the prior art: The high-reflectivity PI cover film of this invention comprises a halogen-free, high-reflectivity white ink layer, a polyimide film layer, an insulating layer, and a release layer. The halogen-free, high-reflectivity white ink layer is coated on the upper surface of the polyimide film layer. The white ink, prepared by composite of rutile titanium dioxide, epoxy-modified polyester resin, monosodium glutamate, epoxy resin, melamine, and polyurethane, can significantly improve the reflectivity of the cover film after curing, ensuring the application value of the PI cover film and having a high market prospect. Attached Figure Description

[0016] Figure 1 This is a schematic diagram comparing the reflectivity of each group of covering films in an embodiment of the present invention; Figure 2 This is a schematic diagram comparing the dimensional stability of the cover films (TD) prepared in each group in the embodiments of the present invention; Figure 3 This is a schematic diagram comparing the MD dimensional stability of the cover films prepared in each group in the embodiments of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The epoxy-modified polyester resin used in the following examples is epoxy-modified polyester resin SGR-3340, the dispersant is dispersant BYK-163, the leveling agent is leveling agent BYK-333, the defoamer is defoamer BYK-052, the epoxy resin is epoxy resin E51, and the epoxy adhesive is epoxy resin E44.

[0019] The release paper is 122g non-silicone release paper (515mm*1000m), purchased from Zhongshan Depu Adhesive Products Co., Ltd.

[0020] The polyimide film has a thickness of 13 μm.

[0021] Example 1: Preparation of the covering film: (1) Prepare materials according to the following parts by weight: 25 parts of rutile titanium dioxide, 32 parts of epoxy modified polyester resin, 4 parts of sodium glutamate, 6 parts of epoxy resin, 1 part of dispersant, 1 part of leveling agent, 1 part of defoamer, 28 parts of butyl acetate, 5 parts of methyl ethyl ketone, 1.5 parts of melamine, and 2.2 parts of polyurethane. (2) Place the epoxy resin in an excess of ethylene glycol monoethyl ether, heat it to 75°C, stir it thoroughly, add sodium glutamate and keep it at the temperature for 5 hours, then filter and remove the solvent by vacuum distillation to obtain the modified epoxy resin. (3) Mix rutile titanium dioxide with epoxy modified polyester resin and butyl acetate and mechanically stir at 800 r / min for 20 min, then pressurize to 3 MPa and let stand for 35 min, then restore to normal pressure to obtain the mixture for later use. (4) Mix the mixture with dispersant, leveling agent, defoamer, diluent, melamine, polyurethane and modified epoxy resin and stir thoroughly to obtain white ink for later use; (5) After uniformly coating the white ink on the front side of the polyimide film (thickness of 13μm), bake it at 150°C to form a white ink layer (thickness of 18μm). (6) Coat the reverse side of the polyimide film with an epoxy adhesive, bake at 100°C to semi-cur it to form an insulating layer (10μm thick), and then cover the insulating layer with a release paper to form a release layer, thus obtaining a PI cover film (wound as follows). Figure 1 (As shown).

[0022] Comparative Example 1: The preparation of the covering film was basically the same as in Example 1, except that the mass fraction of sodium glutamate was adjusted to 2 parts.

[0023] Comparative Example 2: The preparation of the covering film is basically the same as in Example 1, except that the mass of polyurethane is adjusted to 0.9 parts.

[0024] Comparative Example 3: The preparation of the covering film is basically the same as in Example 1, except that the mass fraction of sodium glutamate is adjusted to 2 parts and the mass fraction of polyurethane is adjusted to 0.9 parts.

[0025] Comparative Example 4: Preparation of the covering film: (1) Prepare materials according to the following parts by weight: 25 parts of rutile titanium dioxide, 32 parts of epoxy modified polyester resin, 6 parts of epoxy resin, 1 part of dispersant, 1 part of leveling agent, 1 part of defoamer, 28 parts of butyl acetate, 5 parts of methyl ethyl ketone, 1.5 parts of melamine, and 0.9 parts of polyurethane. (2) Mix rutile titanium dioxide with epoxy modified polyester resin and butyl acetate and mechanically stir at 800 r / min for 20 min, then pressurize to 3 MPa and let stand for 35 min, then restore to normal pressure to obtain the mixture for later use. (3) Mix the mixture with dispersant, leveling agent, defoamer, diluent, melamine, polyurethane and epoxy resin and stir thoroughly to obtain white ink for later use; (4) After uniformly coating the white ink on the front side of the polyimide film (thickness of 13μm), bake it at 150°C to form a white ink layer (thickness of 18μm). (5) Apply an epoxy adhesive to the reverse side of the polyimide film and bake it at 100°C to form an insulating layer (10μm thick). Then, cover the insulating layer with a release paper to form a release layer, thus obtaining a PI cover film.

[0026] Comparative Example 5: Preparation of the covering film: (1) Prepare materials according to the following weight parts: 25 parts of rutile titanium dioxide, 32 parts of epoxy modified polyester resin, 2 parts of sodium glutamate, 6 parts of epoxy resin, 1 part of dispersant, 1 part of leveling agent, 1 part of defoamer, 28 parts of butyl acetate, 5 parts of methyl ethyl ketone, and 1.5 parts of melamine. (2) Place the epoxy resin in an excess of ethylene glycol monoethyl ether, heat it to 75°C, stir it thoroughly, add sodium glutamate and keep it at the temperature for 5 hours, then filter and remove the solvent by vacuum distillation to obtain the modified epoxy resin. (3) Mix rutile titanium dioxide with epoxy modified polyester resin and butyl acetate and mechanically stir at 800 r / min for 20 min, then pressurize to 3 MPa and let stand for 35 min, then restore to normal pressure to obtain the mixture for later use. (4) Mix the mixture with dispersant, leveling agent, defoamer, diluent, melamine and modified epoxy resin and stir thoroughly to obtain white ink for later use; (5) After uniformly coating the white ink on the front side of the polyimide film (thickness of 13μm), bake it at 150°C to form a white ink layer (thickness of 18μm). (6) Apply an epoxy adhesive to the reverse side of the polyimide film and bake it at 100°C to form an insulating layer (10μm thick). Then, cover the insulating layer with a release paper to form a release layer, thus obtaining a PI cover film.

[0027] Comparative Example 6: Preparation of the covering film: (1) Prepare materials according to the following parts by weight: 25 parts of rutile titanium dioxide, 32 parts of epoxy modified polyester resin, 4 parts of sodium glutamate, 6 parts of epoxy resin, 1 part of dispersant, 1 part of leveling agent, 1 part of defoamer, 28 parts of butyl acetate, 5 parts of methyl ethyl ketone, 1.5 parts of melamine, and 2.2 parts of polyurethane. (2) Place the epoxy resin in an excess of ethylene glycol monoethyl ether, heat it to 75°C, stir it thoroughly, add sodium glutamate and keep it at the temperature for 5 hours, then filter and remove the solvent by vacuum distillation to obtain the modified epoxy resin. (3) Mix rutile titanium dioxide with epoxy modified polyester resin and butyl acetate and mechanically stir at 800 r / min for 20 min to obtain a mixture for later use. (4) Mix the mixture with dispersant, leveling agent, defoamer, diluent, melamine, polyurethane and modified epoxy resin and stir thoroughly to obtain white ink for later use; (5) After uniformly coating the white ink on the front side of the polyimide film (thickness of 13μm), bake it at 150°C to form a white ink layer (thickness of 18μm). (6) Apply an epoxy adhesive to the reverse side of the polyimide film and bake it at 100°C to form an insulating layer (10μm thick). Then, cover the insulating layer with a release paper to form a release layer, thus obtaining a PI cover film.

[0028] Detection: 1. The reflectance of the PI covering films prepared in Example 1 and Comparative Examples 1-3 was tested. Specifically, the reflectance of each group of PI covering films was tested using a C84-111 reflectance meter from Shanghai Pushen Chemical Machinery Co., Ltd. The specific test results are shown in Table 1 below. Figure 1 As shown: Table 1 As shown in the table above, the PI cover film in Example 1 has the highest reflectivity, and the addition of compounded sodium glutamate-modified epoxy resin and polyurethane can effectively improve the reflectivity of the white ink layer.

[0029] 2. The solder heat resistance (test method: IPC-TM-650 2.4.13, pass standard: 288℃ / 10s / 3 times) and dimensional stability (IPC-TM-650 2.2.4, pass standard: TD≤±0.15, MD≤±0.15) of each group of PI cover films were tested. The specific results are shown in Table 2 below: Table 2 The above tests show that the solder heat resistance and dimensional stability of the PI cover films in each group are basically qualified and the values ​​are similar, indicating that the changes in the white ink raw materials and processes have little impact on the basic performance of the PI cover films.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-reflectivity PI coating film, characterized in that, The cover film consists of a white ink layer, a polyimide film layer, an insulating layer, and a release layer from top to bottom. The white ink layer is composed of the following raw materials in parts by weight: 20-30 parts rutile titanium dioxide, 30-35 parts epoxy modified polyester resin, 3-5 parts monosodium glutamate, 4-8 parts epoxy resin, 3-3.6 parts additives, 25-30 parts butyl acetate, 3-8 parts diluent, 1-2 parts melamine, and 2-2.4 parts polyurethane.

2. The high-reflectivity PI coating film according to claim 1, characterized in that: The thickness of the white ink layer is 15-20 μm, the thickness of the polyimide film layer is 11-13 μm, and the thickness of the insulating layer is 8-12 μm.

3. The high-reflectivity PI coating film according to claim 1, characterized in that: The insulating layer is an epoxy adhesive; the release layer is release paper or release film.

4. The high-reflectivity PI coating film according to claim 1, characterized in that: The additives are equal masses of dispersant, leveling agent, and defoamer.

5. The high-reflectivity PI coating film according to claim 1, characterized in that: The diluent is butanone.

6. A method for preparing a high-reflectivity PI coating film as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Place the epoxy resin in ethylene glycol monoethyl ether, heat it to 70-80℃, stir it thoroughly and then add sodium glutamate for heat preservation reaction treatment, then filter and remove the solvent by vacuum distillation to obtain modified epoxy resin. (2) After thoroughly mixing rutile titanium dioxide with epoxy modified polyester resin and butyl acetate, pressurize to 2-4 MPa and let stand for 30-40 minutes, then restore to normal pressure to obtain the mixture for later use. (3) Mix the mixture with the additives, diluents, melamine, polyurethane, and modified epoxy resin, and stir thoroughly to obtain white ink for later use; (4) After uniformly coating the white ink on the front side of the polyimide film, bake and cure to form a white ink layer; (5) Apply an epoxy adhesive to the reverse side of the polyimide film, bake it to semi-cur to form an insulating layer, and then apply a release layer to the outside of the insulating layer to obtain a high reflectivity PI cover film and then roll it up.

7. The preparation method according to claim 6, characterized in that: The heat preservation reaction time in step (1) is 4-6 hours.

8. The preparation method according to claim 6, characterized in that: The method for thoroughly mixing in step (3) is to mechanically stir at a speed of 800-1000 r / min for 15-20 min.

9. The preparation method according to claim 6, characterized in that: The baking and curing temperature in step (4) is 130-180℃.

10. The preparation method according to claim 6, characterized in that: The semi-curing temperature in step (5) is 80-120℃.

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