A pi reinforcing film and a method for manufacturing the same

Abstract

The application provides a PI reinforcing film and a preparation method thereof, and relates to the technical field of polyimide (PI) films for electronic products. The PI reinforcing film is composed of rubber liquid, rubber mother liquor, colorant, halogen-free epoxy resin, dicyclopentadiene-phenol epoxy resin, antioxidant, curing agent and ethylhexyl glycerol, wherein the rubber liquid is composed of butyronitrile rubber and solvent; and the rubber mother liquor is composed of rubber liquid, solvent, aluminum hydroxide, flame retardant, diethylaminoethyl cellulose and dextran. The application overcomes the defects of the prior art, realizes the overlapping of the multi-layer PI film by coating the reinforcing glue on the PI film, realizes the adjustment function of the hardness and strength of the PI film, and reduces the production cost of the PI films with different performances as a whole.

Description

Technical Field

[0001] This invention relates to the field of polyimide (PI) film technology for electronic products, specifically to a PI reinforcing film and its preparation method. Background Technology

[0002] Polyimide (PI) films have been widely used in aerospace, electrical insulation, microelectronic device manufacturing, new energy, and rail transportation due to their excellent mechanical properties, high temperature resistance, low coefficient of thermal expansion, high insulation and chemical stability. At present, there are certain differences in the requirements of PI films for different fields, such as differences in key properties such as hardness and strength.

[0003] To meet the requirements of PI film under different conditions, different PI film production lines are often required, which generally results in high costs. Therefore, achieving adjustment of hardness and strength based on existing PI films is a major research direction in PI film production at present. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a PI reinforcing film and its preparation method. By applying a reinforcing adhesive to the PI film, multiple PI films can be overlapped, thereby achieving the function of adjusting the hardness and strength of the PI film and reducing the overall production cost of PI films with different properties.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A PI reinforcing film, wherein the PI reinforcing film is composed of the following raw materials in parts by weight: 20-25 parts rubber liquid, 30-40 parts rubber masterbatch, 1-3 parts colorant, 30-40 parts halogen-free epoxy resin, 4-8 parts dicyclopentadiene-phenol epoxy resin, 0.5-1 part antioxidant, 1-3 parts curing agent, and 2-4 parts ethylhexylglycerin; and the ratio of halogen-free epoxy resin to dicyclopentadiene-phenol epoxy resin is ≥5; wherein the rubber liquid is composed of the following substances in parts by weight: 20-25 parts nitrile rubber and 75-80 parts solvent; wherein the rubber masterbatch is composed of the following substances in parts by weight: 45-55 parts rubber liquid, 15-20 parts solvent, 8-14 parts aluminum hydroxide, 8-10 parts flame retardant, 0.6-1.2 parts diethylaminoethyl cellulose, and 0.5-1.0 parts dextran.

[0006] Preferably, the antioxidant is a mixture of hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 3:1.

[0007] Preferably, the curing agent is at least one selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, isophorone diamine, and 4,4'-diaminodicyclohexylmethane.

[0008] Preferably, the solvent is butanone.

[0009] Preferably, the flame retardant is obtained by mixing ammonium polyphosphate, melamine, and zinc borate / barium borate in a mass ratio of 1:1:2.

[0010] Preferably, the specific preparation method of the rubber liquid includes the following steps: placing nitrile rubber in a solvent, letting it stand for 30-40 minutes at a water bath temperature of 40-50°C, and then stirring at a speed of 400-600 r / min until the solution is clear and transparent, without particles or gel, to obtain the rubber liquid.

[0011] Preferably, the preparation method of the rubber mother liquor includes the following steps: mixing the rubber liquid and solvent, then adding aluminum hydroxide, flame retardant, diethylaminoethyl cellulose and dextran, stirring for 2-4 hours, and then grinding in a grinder 2-3 times to obtain the rubber mother liquor.

[0012] The preparation method of PI reinforcing film is as follows: rubber liquid and rubber mother liquor are mixed and stirred evenly, and then pigment, halogen-free epoxy resin, dicyclopentadiene-phenol epoxy resin, antioxidant, curing agent and ethylhexylglycerin are added and stirred evenly to obtain reinforcing adhesive. The reinforcing adhesive is coated on the surface of PI film and semi-cured. Then another PI film is laminated, pressed and cured at high temperature to form PI reinforcing film between the two PI films.

[0013] Preferably, the semi-curing temperature is 60°C and the baking time is 8-10 hours.

[0014] Preferably, the high-temperature curing method is to first treat at 60°C for 1-3 hours, then at 100°C for 2-3 hours, then at 160°C for 1 hour, then at 180°C for 0.5 hours, and finally cool down to 60°C for 1 hour.

[0015] This invention provides a PI reinforcing film and its preparation method, which has the following advantages compared with the prior art: This invention uses a variety of materials to prepare an adhesive solution to form a PI reinforcing film between two PI films. The PI film and the PI reinforcing film are stacked alternately, and the number of PI film layers can be set according to the requirements to adjust the strength and hardness of the PI film. At the same time, it ensures the flatness of the PI film after lamination, effectively guarantees high temperature stability, reduces the investment in the production line, and comprehensively improves the economic benefits of PI film production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of membrane A flatness detection in an embodiment 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 nitrile rubber used below was purchased from Dongguan Zhengxian Electronic Materials Co., Ltd., model number 072CGL (domestic); the halogen-free epoxy resin was bisphenol A epoxy resin, purchased from Dongguan Zhengxian Electronic Materials Co., Ltd., model number NPEs-901; the dicyclopentadiene-phenol epoxy resin was purchased from Dongguan Zhengxian Electronic Materials Co., Ltd., model number DCPD-EL; the colorant was red powder, purchased from Guangzhou Keyi Chemical Raw Materials Co., Ltd., model number K-H201. The antioxidant is obtained by mixing antioxidant 1010 and antioxidant Y-180 in a mass ratio of 3:1; The curing agent is a mixture of ethylenediamine and phoronediamine in equal mass. The solvent is butanone; The flame retardant is prepared by mixing ammonium polyphosphate, melamine and zinc borate in a mass ratio of 1:1:2.

[0019] The polyimide film (PI film) was purchased from Guangxi Feimate Technology Co., Ltd., with specifications of 50μm×514mm (thickness×width).

[0020] Example 1: Raw material pretreatment: 1. Preparation of rubber liquid: Add 23 parts by weight of nitrile rubber to 78 parts by weight of solvent, let stand at 45°C for 35 minutes, and then stir at 500 r / min until the solution is clear, transparent, free of particles and gel, to obtain rubber liquid.

[0021] 2. Preparation of rubber mother liquor: 2.1 Preparation of Mother Liquor A: (1) Prepare the materials according to the following weight proportions: 50 parts rubber liquid, 18 parts solvent, 11 parts aluminum hydroxide, 9 parts flame retardant, 0.9 parts diethylaminoethyl cellulose, and 0.8 parts dextran; (2) After mixing the rubber liquid and solvent, add aluminum hydroxide, flame retardant, diethylaminoethyl cellulose and dextran, stir at 200 r / min for 3 h, then place in a grinder (use 1.0 mm beads in the inner cavity of the grinder), adjust the speed to 600 r / min for alkaline grinding, each grinding time is 10 min, grind for a total of 3 times to obtain mother liquor A.

[0022] 2.2 Preparation of Mother Liquor B: (1) Prepare the materials according to the following weight proportions: 50 parts rubber liquid, 18 parts solvent, 11 parts aluminum hydroxide, 9 parts flame retardant, and 0.8 parts dextran; (2) After mixing the rubber liquid and solvent, add aluminum hydroxide, flame retardant and dextran, stir at 200 r / min for 3 h, then place in a grinder (use 1.0 mm beads in the inner cavity of the grinder), adjust the speed to 600 r / min for alkaline grinding, each grinding time is 10 min, grind for a total of 3 times to obtain mother liquid B.

[0023] 2.3 Preparation of Mother Liquor C: (1) Prepare the materials according to the following weight proportions: 50 parts rubber liquid, 18 parts solvent, 11 parts aluminum hydroxide, 9 parts flame retardant, and 0.9 parts diethylaminoethyl cellulose; (2) After mixing the rubber liquid and solvent, add aluminum hydroxide, flame retardant and diethylaminoethyl cellulose, stir at 200 r / min for 3 h, then place in a grinder (use 1.0 mm beads in the inner cavity of the grinder), adjust the speed to 600 r / min for alkaline grinding, each grinding time is 10 min, grind for a total of 3 times to obtain mother liquor C.

[0024] 3. Preparation of reinforcing adhesive: 3.1 Preparation of Adhesive A: (1) Prepare the materials according to the following weight proportions: 23 parts rubber liquid, 35 parts mother liquor A, 2 parts colorant, 35 parts halogen-free epoxy resin, 6 parts dicyclopentadiene-phenol epoxy resin, 0.8 parts antioxidant, 2 parts curing agent, and 3 parts ethylhexylglycerin; (2) Mix the rubber liquid and mother liquor A and stir at 400 r / min for 40 min. Then add the colorant, halogen-free epoxy resin, dicyclopentadiene-phenol epoxy resin, antioxidant, curing agent and ethylhexylglycerin. Continue stirring at 400 r / min for 2 h to obtain glue A.

[0025] 3.2 Preparation of Adhesive B: The preparation method of glue B is basically the same as that of glue A, except that the mother liquor A is replaced with mother liquor B.

[0026] 3.3 Preparation of Adhesive C: The preparation method of glue C is basically the same as that of glue A, except that the mother liquor A is replaced with mother liquor C.

[0027] 3.4 Preparation of Adhesive D: (1) Prepare the materials according to the following weight proportions: 23 parts rubber liquid, 35 parts mother liquor A, 2 parts colorant, 30 parts halogen-free epoxy resin, 7 parts dicyclopentadiene-phenol epoxy resin, 0.8 parts antioxidant, 2 parts curing agent, and 3 parts ethylhexylglycerin; (2) Mix the rubber liquid and mother liquor A and stir at 400 r / min for 40 min. Then add the colorant, halogen-free epoxy resin, dicyclopentadiene-phenol epoxy resin, antioxidant, curing agent and ethylhexylglycerin. Continue stirring at 400 r / min for 2 h to obtain glue D.

[0028] 3.5 Preparation of Adhesive E: (1) Prepare the materials according to the following weight proportions: 23 parts rubber liquid, 35 parts mother liquor A, 2 parts colorant, 41 parts halogen-free epoxy resin, 0.8 parts antioxidant, 2 parts curing agent, and 3 parts ethylhexylglycerin; (2) Mix the rubber liquid and mother liquor A and stir at 400 r / min for 40 min. Then add the colorant, halogen-free epoxy resin, antioxidant, curing agent and ethylhexylglycerin. Continue stirring at 400 r / min for 2 h to obtain glue E.

[0029] 3.6 Preparation of Adhesive F: (1) Prepare the materials according to the following weight proportions: 23 parts rubber liquid, 35 parts mother liquor A, 2 parts colorant, 35 parts halogen-free epoxy resin, 6 parts dicyclopentadiene-phenol epoxy resin, 0.8 parts antioxidant, and 2 parts curing agent; (2) Mix the rubber liquid and mother liquor A and stir at 400 r / min for 40 min. Then add the colorant, halogen-free epoxy resin, dicyclopentadiene-phenol epoxy resin, antioxidant and curing agent. Continue stirring at 400 r / min for 2 h to obtain glue F.

[0030] 4. Formation of PI reinforcing film: After applying the reinforcing adhesive to the surface of a PI film, the temperature is raised to 60°C and baked for 9 hours for semi-curing. Then, a new PI film is placed on top of the semi-cured reinforcing adhesive and hot-rolled at 60°C for 2 hours. The temperature is then raised to 100°C for 2.5 hours, then raised to 160°C for 1 hour, then raised to 180°C for 0.5 hours, and finally cooled to 60°C for 1 hour. The PI reinforcing film formed between the two PI films is the PI reinforcing film.

[0031] The composite films obtained by laminating two PI films with the above-mentioned adhesive AF to form different PI reinforcing films are shown in Table 1 below: Table 1 5. Testing: 1. The thickness, hardness (directly measured using a Shore hardness tester), and flatness of each composite membrane were tested. (25cm × 28cm samples were cut from the composite membranes obtained from each group, laid flat for 72 hours, and then the transverse and longitudinal directions were marked. The samples were then placed on a vertical plane, and the height of the two raised corners in the same direction was measured and recorded using a steel ruler. The same method was used to measure and record the values ​​in the other direction. The average value of the two directions was calculated, and the sum of the four corner heights divided by 2 was the flatness value.) The specific test results are shown in Table 2 below: Table 2 As shown in Table 1 above, the overall hardness of membrane AF treated with reinforcing adhesive is significantly improved compared to a single PI membrane. The hardness varies depending on the type of adhesive used. Among them, the adhesive used in membrane A has the best effect on the PI membrane lamination and the highest overall flatness.

[0032] 2. The peel strength (refer to IPC-TM-650 2.4.9) and solder heat resistance (refer to IPC-TM-650 2.4.13) of each composite film were tested. The solder heat resistance test conditions were 288℃ for 10 seconds as one treatment, and the test was repeated 3, 10, and 20 times (no bulging, no delamination, and no blistering were considered as passing). The specific results are shown in Table 3 below: Table 3 In the table above, "√" indicates pass and "×" indicates fail.

[0033] As shown in Table 3 above, membranes A and D have the best peel strength and solder heat resistance, but considering both hardness and flatness, membrane A has the best overall performance.

[0034] Based on the above experiments, it can be seen that using a PI reinforcing film to connect two PI films can effectively improve hardness and strength. In other words, multiple PI films can be connected according to actual needs to achieve the purpose of controlling the PI film.

[0035] 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 PI reinforcing film, characterized in that, The PI reinforcing film is composed of the following raw materials in parts by weight: 20-25 parts rubber liquid, 30-40 parts rubber masterbatch, 1-3 parts colorant, 30-40 parts halogen-free epoxy resin, 4-8 parts dicyclopentadiene-phenol epoxy resin, 0.5-1 part antioxidant, 1-3 parts curing agent, and 2-4 parts ethylhexylglycerin; and the ratio of halogen-free epoxy resin to dicyclopentadiene-phenol epoxy resin is ≥5; The rubber liquid is composed of the following parts by weight: 20-25 parts of nitrile rubber and 75-80 parts of solvent; The rubber mother liquor is composed of the following components by weight: 45-55 parts rubber liquid, 15-20 parts solvent, 8-14 parts aluminum hydroxide, 8-10 parts flame retardant, 0.6-1.2 parts diethylaminoethyl cellulose, and 0.5-1.0 parts dextran.

2. The reinforcing membrane according to claim 1, characterized in that: The antioxidant is obtained by mixing hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 3:

1.

3. The reinforcing membrane according to claim 1, characterized in that: The curing agent is at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, isophorone diamine, and 4,4'-diaminodicyclohexylmethane.

4. The reinforcing membrane according to claim 1, characterized in that: The solvent is butanone.

5. The reinforcing membrane according to claim 1, characterized in that: The flame retardant is obtained by mixing ammonium polyphosphate, melamine, and zinc borate / barium borate in a mass ratio of 1:1:

2.

6. The reinforcing membrane according to claim 1, characterized in that: The specific preparation method of the rubber liquid includes the following steps: Nitrile rubber is placed in a solvent and allowed to stand for 30-40 minutes in a water bath at 40-50°C. Then, it is stirred at 400-600 r / min until the solution is clear, transparent, free of particles and gel, thus obtaining the rubber solution.

7. The reinforcing membrane according to claim 1, characterized in that: The method for preparing the rubber mother liquor includes the following steps: After mixing the rubber liquid and solvent, aluminum hydroxide, flame retardant, diethylaminoethyl cellulose, and dextran are added. The mixture is stirred for 2-4 hours and then ground 2-3 times in a grinder to obtain the rubber mother liquor.

8. A method for preparing a PI reinforcing film as described in any one of claims 1-7, characterized in that: The preparation method involves mixing and stirring rubber liquid and rubber mother liquor evenly, then adding colorant, halogen-free epoxy resin, dicyclopentadiene-phenol epoxy resin, antioxidant, curing agent, and ethylhexylglycerin and stirring evenly to obtain reinforcing adhesive. The reinforcing adhesive is then coated on the surface of a PI film, semi-cured, and then another PI film is laminated, pressed together, and then cured at high temperature to form a PI reinforcing film between the two PI films.

9. The method according to claim 8, characterized in that: The semi-curing temperature is 60℃, and the baking time is 8-10h.

10. The method according to claim 8, characterized in that: The high-temperature curing process involves first treating at 60°C for 1-3 hours, then at 100°C for 2-3 hours, then at 160°C for 1 hour, then at 180°C for 0.5 hours, and finally cooling down to 60°C for 1 hour.

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