Black shading cover film and preparation method thereof

Abstract

The invention provides a black shading cover film and a preparation method thereof, and relates to the field of shading parts of electronic products. The black shading cover film comprises a PI film, a release film and a black epoxy glue layer coated between the PI film and the release film, and the black epoxy glue layer is composed of nitrile rubber, composite epoxy resin, a reinforcing filler, carbon black, a flame retardant, a curing agent, a catalyst and an antioxidant. Wherein the composite epoxy resin is obtained by mixing DCPD epoxy resin and NPES-901 epoxy resin in a mass ratio of (2-3): 1; the reinforcing filler is obtained by mixing graded-particle-size aluminum hydroxide modified by a titanate coupling agent and zeolite according to a mass ratio of (1-3): 1. According to the shading film, the defects in the prior art are overcome, the shading property of the shading film is ensured while the adhesion effect of the base material layer and the release layer is effectively ensured, meanwhile, the mechanical property of the whole shading film is further improved, and the application value of a product is comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the field of light-shielding components for electronic products, and particularly to a black light-shielding covering film and a preparation method thereof. Background Art

[0002] An electronic product light-shielding film is a material used for packaging electronic products that cannot be exposed to light, precision instruments, or other products that require light shielding. Its main function is to prevent the product from changing its properties when exposed to light. The light-shielding film is widely used in the light shielding and light reflection of products such as mobile phones, tablet computers, laptop computers, PDAs, LEDs, and LCDs, and is also used in products such as illuminated keyboards, ultra-thin advertising light boxes, and backlight plates (films).

[0003] Traditional light-shielding films mostly use black and white light-shielding tapes as light-shielding films. However, with the popularization and replacement of electronic products, the demand for light-shielding films is also increasing. At present, light-shielding films are mostly prepared by coating glue between a base material layer and a release film, which can effectively improve the stability and durability of the light-shielding film.

[0004] The durability and reliability of general light-shielding films in actual applications are mainly reflected in indicators such as the tensile strength and elongation at break of mechanical properties. Therefore, on the basis of the existing technology, while ensuring the basic performance of the light-shielding film, improving its mechanical properties is the main research and development direction at present. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a black light-shielding covering film and a preparation method thereof, which can effectively ensure the adhesion effect between the base material layer and the release layer, ensure the light-shielding property of the light-shielding film, and further improve the mechanical properties of the overall light-shielding film, comprehensively improving the application value of the product.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A black light-shielding covering film, the black light-shielding covering film includes a PI film and a release film, and a black epoxy glue layer coated between the PI film and the release film. The black epoxy glue layer is made of the following raw materials in parts by weight: 20-25 parts of nitrile rubber, 32-38 parts of composite epoxy resin, 12-16 parts of reinforcing filler, 12-17 parts of carbon black, 6-8 parts of flame retardant, 2-3 parts of curing agent, 0.2-0.4 parts of catalyst, 0.5-0.8 parts of antioxidant; the composite epoxy resin is a mixture of DCPD epoxy resin (dicyclopentadiene phenol epoxy resin) and NPES-901 epoxy resin (low molecular solid bisphenol A epoxy resin) in a mass ratio of 2-3∶1; the reinforcing filler is a mixture of aluminum hydroxide with a graded particle size and zeolite modified by a titanate coupling agent in a mass ratio of 1-3∶1.

[0007] Preferably, the specific preparation method of the reinforcing filler includes the following steps: S1-1. Mix aluminum hydroxide with particle sizes of 1 - 10 nm, 0.2 - 0.5 μm, and 5 - 15 μm evenly according to a mass ratio of 1∶5∶2 to obtain graded particle size aluminum hydroxide for standby; S1-2. Dissolve a titanate coupling agent accounting for 3% - 5% of the total mass of the graded particle size aluminum hydroxide in an ethanol solution to prepare a coupling agent solution for standby; S1-3. Pour the graded particle size aluminum hydroxide into the coupling agent solution, continuously stir for 2 h in an 80°C oil bath, then centrifuge, and vacuum dry the precipitate to obtain modified aluminum hydroxide for standby; S1-4. Grind and mix the modified aluminum hydroxide and zeolite evenly according to a mass ratio of 1 - 3∶1 to obtain a reinforcing filler.

[0008] Preferably, the flame retardant is at least one of zinc borate or barium metaborate.

[0009] Preferably, the curing agent is at least one of 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl methane, and 3,3'-diethyl-4,4'-diaminodiphenyl methane.

[0010] Preferably, the catalyst is dicyandiamide.

[0011] Preferably, the antioxidant is at least one of antioxidant B215, antioxidant 1076, and antioxidant 1010.

[0012] The preparation method of the black light-shielding covering film includes the following steps: (1) Mix acrylonitrile-butadiene rubber and methyl ethyl ketone according to a mass ratio of 1∶4 and dissolve them to make a rubber solution; (2) Take 1 / 2 of the rubber solution prepared in the above step (1), add the reinforcing filler and the flame retardant together to methyl ethyl ketone, stir for 2 - 4 h, and then grind to obtain a mother liquor for standby; (3) Mix the mother liquor, the remaining rubber solution, carbon black, composite epoxy resin, curing agent, catalyst, and antioxidant evenly to prepare a black epoxy glue for standby; (4) Coat the black epoxy glue on the surface of the PI film, cure it by high-temperature baking in a tunnel furnace, then cover and attach a release film above the black epoxy glue, and wind it up after the lamination process to obtain the black light-shielding covering film.

[0013] Preferably, the stirring speed in step (2) is 400 - 700 r / min, and the grinding treatment method is to place it in a sand mill and use 1.0 MM structured beads for sanding 2 - 3 times.

[0014] Preferably, the parameters for high-temperature baking and curing in the tunnel furnace in step (4) are as follows: the first temperature zone is set at 90°C, the second temperature zone is set at 110°C, the third temperature zone is set at 130°C, the fourth temperature zone is set at 150°C, the fifth temperature zone is set at 160°C, and the baking time is 80 - 120 s.

[0015] The present invention provides a black light-shielding covering film and a preparation method thereof. Compared with the prior art, the advantages are as follows: The light-shielding film of the present invention adopts an epoxy environmental protection system. It mainly uses two epoxy resins, namely DCPD epoxy resin and NPES-901 epoxy resin, which are compounded in a certain proportion and combined with nitrile rubber to form the main system, ensuring the basic mechanical properties of the material. At the same time, it combines aluminum hydroxide and zeolite with graded particle sizes modified by titanate coupling agent as reinforcing fillers to further improve the mechanical properties of the material, and at the same time improve the thermal oxygen aging resistance of the material, preventing the material from accelerating aging due to heat dissipation during the use of electronic products, which affects its service life, and can meet the requirements of modern electronic products for high reliability and long life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the black light-shielding covering film prepared in Example 2 of the present invention; Figure 2 It is a physical picture of the black epoxy glue obtained during the preparation process of Experimental Group 1 in the embodiments of the present invention; Figure 3 It is a physical picture of the black light-shielding covering films obtained from Experimental Group 1 to Experimental Group 7 in the embodiments of the present invention; Figure 1 In it, 1 is a PI film; 2 is a black epoxy glue layer; 3 is a release film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in 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 some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] Example 1: Configuration of basic materials: 1. The nitrile rubber is NANCAR® 1072CG nitrile rubber produced by Southern Dynatech Industries Co., Ltd. 2. Composite epoxy resin: Composite epoxy resin 1: Obtained by mixing DCPD epoxy resin and NPES-901 epoxy resin in a mass ratio of 2.5∶1; Composite epoxy resin 2: Obtained by mixing DCPD epoxy resin and NPES-901 epoxy resin in a mass ratio of 4:1; Composite epoxy resin 3: Obtained by mixing DCPD epoxy resin and NPES-901 epoxy resin in a mass ratio of 1:1; 3. Reinforcing filler: 3.1 Reinforcing filler 1: (1) Mix aluminum hydroxide with particle sizes of 1-10 nm, 0.2-0.5 μm, and 5-15 μm evenly according to a mass ratio of 1:5:2 to obtain graded particle size aluminum hydroxide for standby; (2) Dissolve 4% of the total mass of the graded particle size aluminum hydroxide of titanate coupling agent HY-311W in an ethanol solution to prepare a coupling agent solution for standby; (3) Pour the graded particle size aluminum hydroxide into the coupling agent solution, continuously stir for 2 h in an 80 °C oil bath, then centrifuge, and vacuum dry the precipitate to obtain modified aluminum hydroxide for standby; (4) Mix the modified aluminum hydroxide and zeolite evenly by grinding according to a mass ratio of 2:1 to obtain reinforcing filler 1.

[0019] 3.2 Reinforcing filler 2: (1) Dissolve 4% of the total mass of aluminum hydroxide of titanate coupling agent HY-311W in an ethanol solution to prepare a coupling agent solution for standby; (2) Pour aluminum hydroxide (particle size of 1-10 nm) into the coupling agent solution, continuously stir for 2 h in an 80 °C oil bath, then centrifuge, and vacuum dry the precipitate to obtain modified aluminum hydroxide for standby; (3) Mix the modified aluminum hydroxide and zeolite evenly by grinding according to a mass ratio of 2:1 to obtain reinforcing filler 2.

[0020] 3.3 Reinforcing filler 3: (1) Dissolve 4% of the total mass of aluminum hydroxide of titanate coupling agent HY-311W in an ethanol solution to prepare a coupling agent solution for standby; (2) Pour aluminum hydroxide (particle size of: 0.2-0.5 μm) into the coupling agent solution, continuously stir for 2 h in an 80 °C oil bath, then centrifuge, and vacuum dry the precipitate to obtain modified aluminum hydroxide for standby; (3) Mix the modified aluminum hydroxide and zeolite evenly by grinding according to a mass ratio of 2:1 to obtain reinforcing filler 3.

[0021] 3.4 Reinforcing filler 4: (1) Dissolve 4% of the total mass of aluminum hydroxide of titanate coupling agent HY-311W in an ethanol solution to prepare a coupling agent solution for standby; (2) Pour aluminum hydroxide (particle size: 5 - 15 μm) into the coupling agent solution, continuously stir it in an 80°C oil bath for 2 h, then centrifuge, and vacuum dry the precipitate to obtain modified aluminum hydroxide for later use; (3) Mix the modified aluminum hydroxide and zeolite in a mass ratio of 2:1, and then grind and mix them evenly to obtain reinforcing filler 4.

[0022] 3.5. Reinforcing filler 5: (1) Mix aluminum hydroxide with particle sizes of 1 - 10 nm, 0.2 - 0.5 μm, and 5 - 15 μm evenly in a mass ratio of 1:5:2 to obtain graded particle size aluminum hydroxide for later use; (2) Mix the graded particle size aluminum hydroxide and zeolite in a mass ratio of 2:1, and then grind and mix them evenly to obtain reinforcing filler 5.

[0023] 4. The PI film is a black polyimide film with a thickness of 25 μm; 5. The release film is purchased from Zhongshan Depu Adhesive Products Co., Ltd., with the model JAPEW122 - 1, and the relevant parameters are: basis weight: 122 ± 5 g / m 2 ; thickness: 135 ± 10 μm.

[0024] Example 2: Refer to the raw materials of the above - mentioned example to prepare a black light - shielding covering film: (1) Prepare materials according to the following parts by weight: 23 parts of nitrile rubber, 35 parts of composite epoxy resin, 14 parts of reinforcing filler, 15 parts of carbon black, 7 parts of zinc borate, 2.5 parts of 4,4'-diaminodiphenyl sulfone, 0.3 part of dicyandiamide, and 0.6 part of antioxidant B215; (2) Mix nitrile rubber and methyl ethyl ketone in a mass ratio of 1:4 and dissolve them to prepare a rubber solution for later use; (3) Take 1 / 2 of the rubber solution prepared in the above step (2), and add the reinforcing filler and zinc borate to methyl ethyl ketone (the amount of methyl ethyl ketone is 1 / 2 of the total volume of the rubber solution), stir at a speed of 500 r / min for 3 h, then place it in a sand mill, set the inner cavity of the mill to 1.0 MM beads, and grind it 3 times to obtain a mother liquor for later use; (4) Mix the mother liquor, the remaining rubber solution, carbon black, composite epoxy resin, 4,4'-diaminodiphenyl sulfone, dicyandiamide, and antioxidant B215 evenly to prepare a black epoxy glue. (5) Coat black epoxy glue on the surface of the PI film (coating thickness is 25 um), and cure it by high-temperature baking in a tunnel furnace (parameters are set as follows: the first temperature zone is set at 90 °C, the second temperature zone is set at 110 °C, the third temperature zone is set at 130 °C, the fourth temperature zone is set at 150 °C, the fifth temperature zone is set at 160 °C, and the baking time is 90 s) to form a black epoxy glue layer. Then, laminate a release film above the black epoxy glue layer, and wind it up after the lamination process to obtain a black light-shielding covering film.

[0025] Referring to the above preparation method, different black light-shielding covering films are prepared by selecting different composite epoxy resins and reinforcing fillers, as shown in Table 1 below: Table 1

[0026] And the finished products of each group of light-shielding covering films are as Figure 3 described. Visually observed, the differences are small, and all have good light-shielding effects.

[0027] Detection: 1. Detect the mechanical properties of the black light-shielding covering films prepared in each experimental group in Example 2 above: Use an SMD carrier tape tensile tester (Shenzhen Kexing Precision Instruments Co., Ltd.) to detect the mechanical properties of the black light-shielding covering films of each group according to the operation instructions. The specific results are shown in Table 2 below: Table 2

[0028] 2. Conduct artificial thermal oxygen aging experiments on each group of black light-shielding covering films respectively. Control the temperature at 90 °C, the oxygen concentration at 95%, and the humidity at 50%. After treating each group of black light-shielding covering films for 24 h, 72 h, and 168 h, detect their mechanical properties. The specific results are shown in Tables 3, 4, and 5 below: Table 3 Mechanical properties of each group after 24 h of artificial thermal oxygen aging treatment

[0029] Table 4 Mechanical properties of each group after 72 h of artificial thermal oxygen aging treatment

[0030] Table 5 Mechanical properties of each group after 168 h of artificial thermal oxygen aging treatment

[0031] Calculate the loss rates of the tensile strength and elongation at break of each group of materials after 168 h of artificial aging. The specific results are shown in Table 6 below: Table 6

[0032] As can be seen from the above tests, the mechanical properties and aging resistance of the black light-shielding covering film in Experimental Group 4 are the best. For Experimental Groups 1 and 2, where the ratio of DCPD epoxy resin and NPES-901 epoxy resin in the composite epoxy resin is adjusted, the initial mechanical properties are relatively high, but the subsequent aging resistance effect is poor. In Experimental Group 3, unmodified hierarchical particle size aluminum hydroxide is compounded with zeolite. Although the initial mechanical properties are high, the subsequent anti-aging effect is poor. In addition, in Experimental Group 5, nano-level aluminum hydroxide is used as a filler, resulting in poor subsequent initial mechanical properties and aging resistance effect. This may be due to the reduction of interfacial action, uneven dispersion, and poor mixing uniformity with other raw materials caused by nano-particles. In Experimental Group 6, coarser particle size aluminum hydroxide is used as a filler, resulting in relatively weak initial mechanical properties and poor overall aging resistance effect.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A black light-shielding covering film, characterized in that, The black light-shielding covering film includes a PI film, a release film, and a black epoxy glue layer coated between the PI film and the release film. The black epoxy glue layer is made of the following raw materials in parts by weight: 20-25 parts of nitrile rubber, 32-38 parts of composite epoxy resin, 12-16 parts of reinforcing filler, 12-17 parts of carbon black, 6-8 parts of flame retardant, 2-3 parts of curing agent, 0.2-0.4 parts of catalyst, and 0.5-0.8 parts of antioxidant; The composite epoxy resin is obtained by mixing DCPD epoxy resin and NPES-901 epoxy resin in a mass ratio of 2-3:1; The reinforcing filler is obtained by mixing graded particle size aluminum hydroxide modified with titanate coupling agent and zeolite in a mass ratio of 1-3:

1.

2. The black light-shielding covering film according to claim 1, wherein The specific preparation method of the reinforcing filler includes the following steps: S1-1. Mix aluminum hydroxide with particle sizes of 1-10 nm, 0.2-0.5 μm, and 5-15 μm evenly according to the mass ratio of 1:5:2 to obtain graded particle size aluminum hydroxide for standby; S1-2. Dissolve 3%-5% of the total mass of the graded particle size aluminum hydroxide of titanate coupling agent in an ethanol solution to prepare a coupling agent solution for standby; S1-3. Pour the graded particle size aluminum hydroxide into the coupling agent solution, continuously stir for 2 h under an 80 °C oil bath, then centrifuge, and vacuum dry the precipitate to obtain modified aluminum hydroxide for standby; S1-4. Mix the modified aluminum hydroxide and zeolite in a mass ratio of 1-3:1 and grind and mix evenly to obtain the reinforcing filler.

3. The black light-shielding covering film according to claim 1, characterized in that: The flame retardant is at least one of zinc borate or barium metaborate.

4. The black light-shielding covering film according to claim 1, wherein: The curing agent is at least one of 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl methane, and 3,3'-diethyl-4,4'-diaminodiphenyl methane.

5. The black light-shielding covering film according to claim 1, wherein: The catalyst is dicyandiamide.

6. The black light-shielding covering film according to claim 1, wherein: The antioxidant is at least one of antioxidant B215, antioxidant 1076, and antioxidant 1010.

7. A method for preparing the black light-shielding cover film according to any one of claims 1 to 6, characterized in that: The preparation method includes the following steps: (1) Mix nitrile rubber and methyl ethyl ketone in a mass ratio of 1:4 and dissolve to make a rubber solution; (2) Take 1 / 2 of the rubber solution prepared in the above step (1), add the reinforcing filler and the flame retardant together to methyl ethyl ketone, stir for 2-4 h and then grind to obtain a mother liquor for standby; (3) Mix the mother liquor, the remaining rubber solution, carbon black, composite epoxy resin, curing agent, catalyst, and antioxidant evenly to make black epoxy glue for standby; (4) Coat the black epoxy glue on the surface of the PI film, cure it by high-temperature baking in a tunnel furnace, then cover and paste a release film above the black epoxy glue, and wind it up after the lamination process to obtain the black light-shielding covering film.

8. The preparation method according to claim 7, characterized in that: In the step (2), the stirring speed is 400-700 r / min, and the grinding treatment method is to place it in a sand mill and use 1.0 MM structured beads for sanding 2-3 times.

9. The preparation method according to claim 7, wherein: In the step (4), the parameters for high-temperature baking and curing in the tunnel furnace are set as follows: the first temperature zone is set at 90 °C, the second temperature zone is set at 110 °C, the third temperature zone is set at 130 °C, the fourth temperature zone is set at 150 °C, the fifth temperature zone is set at 160 °C, and the baking time is 80-120 s.

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