Protective film for camera foam and preparation method thereof

Abstract

The invention relates to the field of protective films, in particular to a protective film for camera foam and a preparation method of the protective film. A protective film for camera foam at least structurally comprises a film base layer, an antistatic layer located on the upper surface of the film base layer, an antistatic adhesive layer located on the lower surface of the film base layer and a fluoroplastic release layer located on the bottom surface of the antistatic adhesive layer. The finally prepared protective film for the camera foam not only can effectively balance the adhesive force and avoid the problem of adhesive residue, but also can further obtain excellent exhaust property, stability and antistatic property, and greatly reduces the performance contradiction faced by the existing protective film for the foam; therefore, the high comprehensive performance requirement of the protective film in the existing rapidly-developed electronic product industry is met.

Description

Technical Field

[0001] The present application relates to the field of protective films, and more specifically mentions a protective film for camera foam and a preparation method thereof. Background Art

[0002] The camera module is a critical, highly sophisticated and vulnerable component in the manufacturing, assembly, transportation, and use of electronic products, particularly smartphones, tablets, and automotive camera systems. Its lens surface and surrounding structures are susceptible to scratches, collisions, dust contamination, liquid infiltration, and static electricity, which can affect image quality and even cause functional failure. To prevent this damage, a temporary protective layer is applied to the lens surface and necessary peripheral structures before the camera leaves the factory, is assembled, transported, and is used.

[0003] Foam substrates, due to their unique properties, are becoming one of the preferred base materials for this protective structure. The foam protective film used with them provides excellent camera and lens protection. Commonly used foams include polyurethane (PU), polyethylene (PE), polyester (PET), and other materials. The soft foam formed by these foams offers excellent cushioning and shock absorption properties, effectively absorbing external impact and friction, and protecting the lens from scratches and crushing. This softness allows it to conform well to complex or irregular surfaces of camera components, ensuring a tight seal. The open-cell structure of the foam provides a certain degree of air permeability, which facilitates degassing during bonding, reduces air bubbles, and improves adhesion.

[0004] Foam protective films are usually composed of several composite layers, which may also include multiple functional layers. However, despite the widespread use of foam protective films, the current mainstream technical solutions still face some significant challenges and limitations. For example, the balance between adhesion and residual adhesive is required. The protective film needs sufficient adhesion to ensure that it is firmly attached during assembly and transportation and will not fall off accidentally. However, when removing the protective film after assembly, it must be able to be peeled off cleanly and neatly. There is also the contradiction between degassing and bonding stability. Thicker protective films have poor degassing properties and cannot quickly degas to avoid bubbles, but they have better bonding stability. Thinner protective films cannot effectively achieve strong bonding effects, which is more limited in practical applications, but the overall anti-bubble performance is excellent. The electrostatic protection performance of the protective film is weak or absent. Modern camera modules are highly sophisticated and sensitive to charge, but static electricity is easily generated and accumulated during the bonding and peeling process, causing damage to the lens. Summary of the Invention

[0005] In summary, existing foam protective films still have certain obvious defects in performance, and how to effectively improve the above performance has become an important topic that technicians in this field need to study. Through in-depth research in this field, the applicant proposes a camera foam protective film and a preparation method thereof in this application. The camera foam protective film finally prepared by this application can not only effectively balance the problems of adhesion and no residual glue, but also further obtain excellent air discharge, bonding stability and antistatic properties, greatly reducing the performance contradictions faced by existing foam protective films, thereby responding to the high comprehensive performance requirements of the current rapidly developing electronic products industry for such protective films.

[0006] A protective film for camera foam, the structure of which at least includes: a film base, an antistatic layer located on the upper surface of the film base, an antistatic adhesive layer located on the lower surface of the film base, and a fluoroplastic release layer located on the bottom surface of the antistatic adhesive layer.

[0007] In a preferred embodiment, the film base layer is a PET-based film layer.

[0008] In a preferred embodiment, the membrane base layer is surface-coated, and the coating agent is anthraquinone blue.

[0009] In a preferred embodiment, the surface coating thickness is 4 to 8 μm.

[0010] In a more preferred embodiment, the surface coating thickness is 5 to 6 μm.

[0011] In a preferred embodiment, the thickness of the membrane base layer is 35-50 μm.

[0012] In a more preferred embodiment, the thickness of the membrane base layer is 40-45 μm.

[0013] In a preferred embodiment, the antistatic layer has a thickness of 8 to 16 μm.

[0014] In a more preferred embodiment, the antistatic layer has a thickness of 10 to 15 μm.

[0015] In a preferred embodiment, the thickness of the antistatic adhesive layer is 20-30 μm.

[0016] In a more preferred embodiment, the thickness of the antistatic adhesive layer is 22-25 μm.

[0017] In a preferred embodiment, the thickness of the fluoroplastic release layer is 50-55 μm.

[0018] In a preferred embodiment, the antistatic layer comprises, by weight, 90-120 parts of base resin, 15-30 parts of modified acrylic copolymer resin, 6-12 parts of antistatic agent, 2-4 parts of leveling agent, and 20-40 parts of deionized water.

[0019] In a preferred embodiment, the base resin is a water-based polyurethane acrylate resin.

[0020] In a preferred embodiment, the mass ratio of the base resin, the modified acrylic copolymer resin and the antistatic agent is (10-11): (2-2.5): (0.8-1.1).

[0021] In a more preferred embodiment, the mass ratio of the base resin, the modified acrylic copolymer resin and the antistatic agent is (10-10.5): (2.2-2.5): (0.9-1).

[0022] In a preferred embodiment, the method for preparing the modified acrylic copolymer resin comprises the following steps: S1: mixing methyl methacrylate, butyl acrylate, 2-(4-thiophenyl)pyridine acrylate and glycidyl methacrylate, and then adding an organic solvent for emulsification to obtain a pre-emulsion; S2: after heating, dropwise adding an organic solvent containing an initiator to the pre-emulsion, controlling the dropping time and the subsequent insulation reaction time; S3: after the insulation reaction is completed, adding an initiator to continue the reaction, cooling, adding 2,6-di-tert-butyl-p-cresol, insulation and filtering to obtain the product.

[0023] A more preferred embodiment is a method for preparing the modified acrylic copolymer resin, comprising the following steps: S1: mixing methyl methacrylate, butyl acrylate, 2-(4-thiophenyl)pyridine acrylate and glycidyl methacrylate, adding propylene glycol methyl ether acetate, and emulsifying at 400-600 rpm for 30-40 minutes to obtain a pre-emulsion; S2: heating to 80-85°C, adding propylene glycol methyl ether acetate solution containing azobisisoheptanenitrile dropwise to the pre-emulsion, the addition time being 1.5-2 hours, and keeping warm for reaction for 2-2.5 hours after the addition is completed; S3: after the insulation reaction is completed, adding azobisisoheptanenitrile and continuing the reaction for 1.5-2 hours, then cooling to 40-45°C, adding 2,6-di-tert-butyl-p-cresol and keeping warm for 30-45 minutes, and filtering to obtain the product.

[0024] In a preferred embodiment, the mass ratio of methyl methacrylate, butyl acrylate, 2-(4-thiophenyl)pyridine acrylate and glycidyl methacrylate is (4-5): (3-4): (1-1.5): (1-1.5).

[0025] In a more preferred embodiment, the mass ratio of methyl methacrylate, butyl acrylate, 2-(4-thiophenyl)pyridine acrylate and glycidyl methacrylate is (4-4.5): (3.2-3.5): (1.3-1.5): (1.1-1.2).

[0026] In a preferred embodiment, the antistatic agent is at least one of nano-indium tin oxide, nano-indium tin oxide and nano-aluminum-doped zinc oxide.

[0027] In a preferred embodiment, the antistatic agent is nano-indium tin oxide.

[0028] In a preferred embodiment, the average particle size of the nano-indium tin oxide is 30-40 nm.

[0029] In a preferred embodiment, the leveling agent is polyether-modified polydimethylsiloxane, acrylated polysiloxane or perfluoropolyether-modified silicone oil.

[0030] In a preferred embodiment, the leveling agent is acrylated polysiloxane.

[0031] In a preferred embodiment, the antistatic adhesive layer comprises, by weight, 80-100 parts of base adhesive, 20-30 parts of modified auxiliary adhesive, 2-6 parts of ionic liquid, 2-4 parts of coupling agent, and 10-20 parts of tackifier.

[0032] In a preferred embodiment, the base adhesive is an acrylic pressure-sensitive adhesive.

[0033] In a preferred embodiment, the mass ratio of the base glue, the modified auxiliary glue and the ionic liquid is (9-10): (2.2-2.6): (0.3-0.5).

[0034] In a more preferred embodiment, the mass ratio of the base glue, the modified auxiliary glue and the ionic liquid is (9.5-10): (2.4-2.6): (0.3-0.4).

[0035] In a preferred embodiment, the method for preparing the modified auxiliary glue comprises the following steps: S1: after heating, adding polydichlorophosphazene to NMP (1-methyl-2-pyrrolidone) solvent in a reaction vessel, followed by sequentially adding hydroxyethyl acrylate and N-acryloyloxyethyl phosphaphenanthridone, and maintaining the temperature for reaction; S2: adding tetrabutylammonium fluoride for catalytic conversion, then cooling and adding triethylamine for maintenance; S3: after the reaction is completed, adding sufficient methanol until precipitation is complete, and then vacuum drying to obtain the product.

[0036] In a more preferred embodiment, the method for preparing the modified auxiliary glue comprises the following steps: S1: heating to 80-90°C, adding polydichlorophosphazene to an NMP (1-methyl-2-pyrrolidone) solvent in a reaction vessel, and then sequentially adding hydroxyethyl acrylate and N-acryloyloxyethyl phosphaphenanthridone, and maintaining the reaction for 6-8 hours; S2: adding tetrabutylammonium fluoride for catalytic conversion for 2-3 hours, then cooling to 60-65°C and adding triethylamine, maintaining the reaction for 5-6 hours; S3: after the reaction is completed, adding sufficient methanol until precipitation is complete, and then drying under vacuum at 70-75°C for 40-48 hours to obtain the product.

[0037] In a preferred embodiment, the number average molecular weight of the polydichlorophosphazene is 25,000 to 40,000 Da.

[0038] In a preferred embodiment, the mass ratio of the polydichlorophosphazene, hydroxyethyl acrylate and N-acryloyloxyethyl phosphaphenanthridone is (5-6): (2-3): (1.2-1.8).

[0039] In a more preferred embodiment, the mass ratio of the polydichlorophosphazene, hydroxyethyl acrylate and N-acryloyloxyethyl phosphaphenanthridone is (5.5-6): (2-2.5): (1.3-1.5).

[0040] In a preferred embodiment, the ionic liquid is at least one of EMIM-BF4, BMIM-PF6 and BMP-TFSI.

[0041] In a more preferred embodiment, the ionic liquid is BMP-TFSI.

[0042] In a preferred embodiment, the coupling agent is at least one titanate coupling agent.

[0043] In a more preferred embodiment, the coupling agent is isopropyl bis(dioctylphosphite)titanate.

[0044] In a preferred embodiment, the tackifier is at least one of hydrogenated rosin glycerol ester, terpene phenolic, C5 petroleum resin and C9 petroleum resin.

[0045] In a more preferred embodiment, the tackifier is hydrogenated rosin glycerol ester.

[0046] In a preferred embodiment, the fluoroplastic release layer comprises a 40-45 μm PET film and a 5-15 μm fluoroplastic release layer.

[0047] In a preferred embodiment, the raw materials of the fluoroplastic release layer include, by weight: 10-15 parts of perfluoropolyether, 1-1.5 parts of curing agent, 0.5-1 parts of nanoparticles, and 70-90 parts of ethyl acetate.

[0048] In a preferred embodiment, the mass ratio of the perfluoropolyether, curing agent and nanoparticles is (12-15): (1.2-1.5): (0.8-1).

[0049] In a preferred embodiment, the curing agent is at least one isocyanate curing agent.

[0050] In a preferred embodiment, the nanoparticles are at least one of nano-silicon dioxide, nano-titanium dioxide, nano-zinc oxide and nano-antimony oxide.

[0051] In a preferred embodiment, the nanoparticles are nano-silicon dioxide.

[0052] In a preferred embodiment, the average particle size of the nanoparticles is 25-50 nm.

[0053] A method for preparing a protective film for camera foam, specifically comprising the following steps: S1: coating the upper and lower surfaces of the film base with anthraquinone blue at a coating speed of 2.5-3 m / min, and then drying with hot air at 80-90°C at a wind speed of 10-15 m / s for 3-5 min; S2: mixing the raw materials for the antistatic layer at a high speed of 400-600 rpm for 40-50 min, adding the raw materials to an extrusion coater and coating them on the upper surface of the film base, controlling the thickness of the wet film, and then drying with hot air at 80-90°C at a wind speed of 10-15 m / s for 2-3 min, and then IR curing at 110-120°C for 3-5 min to obtain an antistatic layer; S3: mixing the raw materials for the antistatic adhesive layer with a Stir at a high speed of 1000~1200rpm for 15~20min, and then apply it to the lower surface of the film base layer, dry it with hot air at 70~75℃, with a wind speed of 10~15m / s for 3~4min, and then perform a hot pressing roller at 100~110℃ and 0.4~0.5MPa for 10~15s to obtain an antistatic adhesive layer; S4: Mix the raw materials of the fluoroplastic release layer and apply it to the lower surface of the PET film. The curing conditions are 120~130℃ for 4~5min. After completion, it is laminated with the antistatic adhesive layer through a precision roller pressing machine with a pressure of 0.2~0.3MPa, a temperature of 25~30℃, and a speed of 2~2.5m / min. Then, it is aged at 40~45℃ for 46~48h.

[0054] This application has practical beneficial effects:

[0055] 1. The camera foam protective film prepared in this application can not only effectively balance the problems of adhesion and no residual glue, but also further obtain excellent air discharge, stability and antistatic properties, greatly reducing the performance contradictions faced by existing foam protective films, thereby responding to the current rapidly developing electronic products industry's high comprehensive performance requirements for such protective films.

[0056] 2. The antistatic layer of the foam protective film of the present application is compounded with a modified acrylic copolymer resin and a base resin, which can not only greatly enhance the antistatic performance of the foam protective film itself, actively protect the camera module from the influence of static electricity accumulation, but also enhance the speed of charge dissipation during the bonding and peeling process, avoid the damage to the camera caused by static electricity accumulation, and the overall surface performance is excellent, and it can also have good surface waterproofing and exhaust effects, effectively improving the overall comprehensive performance.

[0057] 3. Furthermore, the present application greatly improves the overall comprehensive performance of the foam protective film by combining the base glue and the modified auxiliary glue in the anti-static glue layer. In particular, it can balance the performance issues of adhesion and no residual glue, and can also greatly improve the bonding reliability and stability at the same time, always maintaining good bonding strength. In terms of electrostatic protection, it can avoid the accumulation of electrostatic charges in the glue layer, reduce the performance contradiction between the interlayer structure and the raw materials of the foam protective film, and thus obtain excellent use quality and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a product photo of the protective film for camera foam prepared in Example 1 of this application.

[0059] Figure 2 Schematic diagram of product sampling and testing of the camera foam protective film prepared in Example 1 of the present application.

[0060] Figure 3 Schematic diagram of the application of the protective film for camera foam prepared in Example 1 of the present application in camera foam.

[0061] Figure 4 This is a graph showing the adhesion-peel strength test results of the camera foam protective film prepared in Example 1 of the present application.

[0062] Figure 5 Graph showing the spectroscopic data test results of the camera foam protective film prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0063] Example 1

[0064] The protective film for camera foam comprises: a film base, an antistatic layer located on the upper surface of the film base, an antistatic adhesive layer located on the lower surface of the film base, and a fluoroplastic release layer located on the bottom surface of the antistatic adhesive layer.

[0065] The membrane base layer is a PET base film layer, model HSB50, from Dongguan Hesheng Plastic Products Co., Ltd., with a thickness of 40 μm; the PET base film layer is surface coated, the coating agent is anthraquinone blue, and the coating thickness is 5 μm; the total thickness of the membrane base layer is 45 μm.

[0066] The thickness of the antistatic layer is 12 μm; the thickness of the antistatic adhesive layer is 24 μm; and the thickness of the fluoroplastic release layer is 50 μm.

[0067] The antistatic layer comprises, by weight, 100 parts of base resin, 24 parts of modified acrylic copolymer resin, 9 parts of antistatic agent, 2.6 parts of leveling agent, and 25 parts of deionized water.

[0068] The base resin is a waterborne polyurethane acrylate resin, Bayhydrol® UH 2590, from Covestro, Germany.

[0069] The preparation method of the modified acrylic copolymer resin comprises the following steps, calculated by mass: S1: 45 parts of methyl methacrylate, 33 parts of butyl acrylate, 13 parts of 2-(4-thiophenyl)pyridine acrylate and 12 parts of glycidyl methacrylate are mixed, and then 120 parts of propylene glycol methyl ether acetate are added, and the mixture is emulsified at 500 rpm for 40 minutes to obtain a pre-emulsion; S2: the temperature is raised to 80°C, and a propylene glycol methyl ether acetate solution containing 1.2 parts of azobisisoheptanenitrile (20 parts in total) is dropwise added to the pre-emulsion for 2 hours. After the dropwise addition is completed, the mixture is kept warm for reaction for 2 hours; S3: after the heat preservation reaction is completed, 0.3 parts of azobisisoheptanenitrile is added, and the reaction is continued for 2 hours. Then, the temperature is lowered to 40°C, 0.1 parts of 2,6-di-tert-butyl-p-cresol is added, and the mixture is kept warm for 40 minutes. The mixture is filtered to obtain the product.

[0070] The antistatic agent is nano-indium tin oxide with an average particle size of 30nm.

[0071] The leveling agent is acrylated polysiloxane, L-7001, from Momentive, USA.

[0072] The antistatic adhesive layer comprises, by weight, 95 parts of base adhesive, 25 parts of modified auxiliary adhesive, 3.5 parts of ionic liquid, 2.6 parts of coupling agent, and 12 parts of tackifier.

[0073] The base adhesive is acrylic pressure-sensitive adhesive, PS8699, from Henkel, Germany.

[0074] The preparation method of the modified auxiliary glue, calculated by mass, includes the following steps: S1: heating to 90°C, adding 58 parts of polydichlorophosphazene to 200 parts of NMP (1-methyl-2-pyrrolidone) solvent in a reaction container, and then adding 22 parts of hydroxyethyl acrylate and 14 parts of N-acryloyloxyethyl phosphatidone in sequence, and keeping the temperature for reaction for 8 hours; S2: adding 0.8 parts of tetrabutylammonium fluoride for catalytic conversion for 2 hours, then cooling to 60°C and adding 18 parts of triethylamine and keeping the temperature for 6 hours; S3: after the reaction is completed, adding sufficient methanol until precipitation is complete, and then drying in a vacuum at 70°C for 42 hours to obtain the product.

[0075] The number average molecular weight of polydichlorophosphazene is 30,000 Da, PNC-100, and is from Solvay Chemicals.

[0076] The ionic liquid is BMP-TFSI; the coupling agent is bis(dioctylphosphite) isopropyl titanate.

[0077] The tackifier is hydrogenated rosin glycerol ester, industrial grade, from Hubei Xinghengye Technology Co., Ltd. in China.

[0078] The fluoroplastic release layer includes a 40 μm PET film and a 10 μm fluoroplastic release layer.

[0079] The raw materials of the fluoroplastic release layer include, by weight: 14.5 parts of perfluoropolyether, 1.3 parts of curing agent, 0.8 parts of nanoparticles, and 80.5 parts of ethyl acetate.

[0080] The curing agent is an isocyanate curing agent, N3300, from Covestro, Germany.

[0081] The nanoparticles are nano-silicon dioxide with an average particle size of 40nm.

[0082] The preparation method of the protective film for camera foam specifically includes the following steps: S1: coating the upper and lower surfaces of the film base with anthraquinone blue at a coating speed of 3m / min, and then drying with hot air at 85°C at a wind speed of 10m / s for 5min; S2: mixing the raw materials of the antistatic layer at a high speed of 500rpm for 45min, adding them to the extrusion coating machine and coating them on the upper surface of the film base, controlling the thickness of the wet film, and then drying with hot air at 85°C at a wind speed of 10m / s for 3min, and then IR curing at 120°C for 4min to obtain the antistatic layer; S3: mixing the raw materials of the antistatic adhesive layer After mixing, stir at a high speed of 1200rpm for 18min, and then apply it to the lower surface of the membrane base layer, dry it with hot air at 70℃, wind speed 10m / s, 4min, and then perform hot pressing on a roller at 100℃, 0.5MPa for 12s to obtain an antistatic adhesive layer; S4: Mix the raw materials of the fluoroplastic release layer and apply it to the lower surface of the PET film. The curing conditions are 4.5min at 120℃. After completion, it is laminated with the antistatic adhesive layer through a precision roller pressing machine with a pressure of 0.3MPa, a temperature of 30℃, and a speed of 2.2m / min. Then, it is matured at 40℃ for 48h.

[0083] The product pictures and sampling pictures of the protective film for camera foam prepared in this embodiment are as follows: Figure 1 and Figure 2 shown.

[0084] The schematic diagram of the application of the protective film for camera foam prepared in this embodiment in camera foam is as follows Figure 3 shown.

[0085] Example 2

[0086] The only difference between this embodiment and embodiment 1 is as follows: the raw materials of the antistatic layer, calculated by mass, include: 110 parts of base resin, 20 parts of modified acrylic copolymer resin, 0.8 parts of antistatic agent, 2.4 parts of leveling agent, and 22.5 parts of deionized water.

[0087] The other embodiments are the same.

[0088] Example 3

[0089] The only difference between this embodiment and embodiment 1 is as follows: the raw materials of the antistatic adhesive layer, calculated by mass, include: 100 parts of base adhesive, 22 parts of modified auxiliary adhesive, 3 parts of ionic liquid, 2.5 parts of coupling agent, and 12 parts of tackifier.

[0090] The other embodiments are the same.

[0091] Comparative Example 1

[0092] The only difference between this comparative example and Example 1 is as follows: the raw materials of the antistatic layer, calculated by mass, include: 125 parts of base resin, 5 parts of modified acrylic copolymer resin, 0.8 parts of antistatic agent, 2.4 parts of leveling agent, and 22.5 parts of deionized water.

[0093] The other embodiments are the same.

[0094] Comparative Example 2

[0095] The only difference between this comparative example and Example 1 is as follows: the raw materials of the antistatic layer, calculated by mass, include: 70 parts of base resin, 40 parts of modified acrylic copolymer resin, 9 parts of antistatic agent, 2.6 parts of leveling agent, and 25 parts of deionized water.

[0096] The other embodiments are the same.

[0097] Comparative Example 3

[0098] The only difference between this comparative example and Example 1 is as follows: the raw materials of the antistatic adhesive layer, calculated by mass, include: 110 parts of base adhesive, 12 parts of modified auxiliary adhesive, 3.2 parts of ionic liquid, 2.8 parts of coupling agent, and 12 parts of tackifier.

[0099] The other embodiments are the same.

[0100] Comparative Example 4

[0101] The only difference between this comparative example and Example 1 is as follows: the preparation method of the modified acrylic copolymer resin, calculated in parts by mass, comprises the following steps: S1: 45 parts of methyl methacrylate, 33 parts of butyl acrylate, 5 parts of 2-(4-thiophenyl)pyridine acrylate and 3 parts of glycidyl methacrylate are mixed, 120 parts of propylene glycol methyl ether acetate are added, and the mixture is emulsified at 500 rpm for 40 minutes to obtain a pre-emulsion; S2: the temperature is raised to 80°C, and a propylene glycol methyl ether acetate solution containing 1.2 parts of azobisisoheptanenitrile (20 parts in total) is added dropwise to the pre-emulsion for 2 hours. After the addition is completed, the mixture is kept warm for reaction for 2 hours; S3: after the reaction is completed, 0.3 parts of azobisisoheptanenitrile is added and the reaction is continued for 2 hours, then the temperature is lowered to 40°C, 0.1 parts of 2,6-di-tert-butyl-p-cresol is added, the mixture is kept warm for 40 minutes, and the mixture is filtered to obtain the product.

[0102] The other embodiments are the same.

[0103] Comparative Example 5

[0104] The only difference between this comparative example and Example 1 is as follows: the preparation method of the modified acrylic copolymer resin, calculated in parts by mass, comprises the following steps: S1: 45 parts of methyl methacrylate, 10 parts of butyl acrylate, 18 parts of 2-(4-thiophenyl)pyridine acrylate and 28 parts of glycidyl methacrylate are mixed, 120 parts of propylene glycol methyl ether acetate are added, and the mixture is emulsified at 500 rpm for 40 minutes to obtain a pre-emulsion; S2: the temperature is raised to 80°C, and a propylene glycol methyl ether acetate solution containing 1.2 parts of azobisisoheptanenitrile (20 parts in total) is added dropwise to the pre-emulsion for 2 hours. After the addition is completed, the mixture is kept warm for reaction for 2 hours; S3: after the reaction is completed, 0.3 parts of azobisisoheptanenitrile is added and the reaction is continued for 2 hours, then the temperature is lowered to 40°C, 0.1 parts of 2,6-di-tert-butyl-p-cresol is added, the mixture is kept warm for 40 minutes, and the mixture is filtered to obtain the product.

[0105] The other embodiments are the same.

[0106] Comparative Example 6

[0107] The only difference between this comparative example and Example 1 is as follows: the preparation method of the modified auxiliary glue, calculated by mass, comprises the following steps: S1: heating to 90°C, adding 70 parts of polydichlorophosphazene to 200 parts of NMP (1-methyl-2-pyrrolidone) solvent in a reaction vessel, and then adding 15 parts of hydroxyethyl acrylate and 5 parts of N-acryloyloxyethyl phosphaphenanthridone in sequence, and keeping the temperature for reaction for 8 hours; S2: adding 0.8 parts of tetrabutylammonium fluoride for catalytic conversion for 2 hours, then cooling to 60°C and adding 18 parts of triethylamine and keeping the temperature for 6 hours; S3: after the reaction is completed, adding sufficient methanol until precipitation is complete, and then drying in a vacuum at 70°C for 42 hours to obtain the product.

[0108] The other embodiments are the same.

[0109] Performance Testing

[0110] 1. Adhesion test: The protective films prepared in the examples and comparative examples were made into 60mm×25mm samples, and the fluoroplastic release layer was peeled off and attached to the steel plate. The samples were rolled back and forth 6 times with a 2Kg rolling roller. After standing for 30 minutes, the peeling test was performed on a tensile testing machine. The adhesion-peeling test results of Example 1 are shown in FIG. Figure 4 As shown, the results of all embodiments and comparative examples are recorded in Table 1 by taking the average value of 10 tests.

[0111] 2. Spectral data test: The protective films prepared in the examples and comparative examples were tested for spectral data using a transmittance tester. The spectral data test results of Example 1 are as follows: Figure 5As shown, the results of all embodiments and comparative examples are recorded in Table 1 by taking the average value of 10 tests.

[0112] 3. Impedance test: An impedance tester was used to test the protective films prepared in the embodiments and comparative examples. 100 mm × 100 mm samples were prepared. The antistatic layer on the surface of the protective film was tested at 5 different locations, and the average value of the 5 locations was taken. The results of all the embodiments and comparative examples were taken as the average value of 10 tests and recorded in Table 1.

[0113] 4. Hardness Test: Use a TECLOCK GS-754G hardness tester. Place the sample to be tested on a flat surface and ensure it is level. Ensure the hardness tester pointer is normal (black needle is at zero) before testing. Use your hands to secure the hardness tester from both sides of the hardness tester dial. Press the hardness tester vertically from above onto the plane of the material to be tested. When the bottom pressure surface of the hardness tester comes into close contact with the plane of the material to be tested, immediately read the value indicated by the black needle, which is the hardness. The results of all Examples and Comparative Examples are the average of 10 tests and are reported in Table 1.

[0114] Table 1 Performance test results

[0115]

[0116] Judging from the final performance test results of the embodiments and comparative examples, compared with embodiments 1 to 3, comparative examples 1 to 3 adopt raw material ratios that are not within the technical solutions specified in this application, resulting in weakened interactions between the raw materials, and thus a significant decrease in corresponding performance occurs in the antistatic layer and the antistatic adhesive layer, respectively. This further verifies the importance of the ratio between the corresponding raw materials in this application for the technical effect.

[0117] However, because Comparative Examples 4 to 6 did not adopt the optimal technical solution specified in this application to prepare the modified acrylic copolymer resin of the antistatic layer and the modified auxiliary glue of the antistatic adhesive layer, their own performance effects showed obvious differences, and further showed poor synergy in the overall system of the protective film, which ultimately led to a significant decline in the corresponding performance.

Claims

1. A protective film for camera foam, characterized by: Its structure at least includes: a film base, an antistatic layer located on the upper surface of the film base, an antistatic adhesive layer located on the lower surface of the film base, and a fluoroplastic release layer located on the bottom surface of the antistatic adhesive layer; The membrane base layer is surface coated, and the coating agent is anthraquinone blue; The antistatic layer comprises, by weight, 90 to 120 parts of base resin, 15 to 30 parts of modified acrylic copolymer resin, 6 to 12 parts of antistatic agent, 2 to 4 parts of leveling agent, and 20 to 40 parts of deionized water. The preparation method of the modified acrylic copolymer resin comprises the following steps: S1: mixing methyl methacrylate, butyl acrylate, 2-(4-thiophenyl)pyridine acrylate and glycidyl methacrylate, and then adding an organic solvent for emulsification to obtain a pre-emulsion; S2: adding an organic solvent containing an initiator dropwise to the pre-emulsion after heating, and controlling the dropping time and the subsequent heat preservation reaction time; S3: after the heat preservation reaction is completed, adding an initiator to continue the reaction, cooling, adding 2,6-di-tert-butyl-p-cresol, heat preservation, and filtering to obtain the product.

2. The camera foam protective film according to claim 1, characterized in that: The mass ratio of the methyl methacrylate, butyl acrylate, 2-(4-thiophenyl)pyridine acrylate and glycidyl methacrylate is (4-5): (3-4): (1-1.5): (1-1.5).

3. The camera foam protective film according to claim 2, characterized in that: The mass ratio of the base resin, modified acrylic copolymer resin and antistatic agent is (10-10.5): (2.2-2.5): (0.9-1); the antistatic agent is at least one of nano-indium tin oxide, nano-indium tin oxide and nano-aluminum-doped zinc oxide.

4. The camera foam protective film according to claim 3, characterized in that: The film base layer is a PET base film layer.

5. The camera foam protective film according to claim 4, characterized in that: The antistatic adhesive layer comprises, by weight, 80-100 parts of base adhesive, 20-30 parts of modified auxiliary adhesive, 2-6 parts of ionic liquid, 2-4 parts of coupling agent, and 10-20 parts of tackifier.

6. The camera foam protective film according to claim 5, characterized in that: The base adhesive is an acrylic pressure-sensitive adhesive; the mass ratio of the base adhesive, the modified auxiliary adhesive and the ionic liquid is (9-10): (2.2-2.6): (0.3-0.5).

7. The camera foam protective film according to claim 6, characterized in that: The preparation method of the modified auxiliary glue comprises the following steps: S1: after heating, adding polydichlorophosphazene to an NMP solvent in a reaction container, then sequentially adding hydroxyethyl acrylate and N-acryloyloxyethyl phosphaphenanthridone, and keeping the temperature for reaction; S2: adding tetrabutylammonium fluoride for catalytic conversion, then cooling and adding triethylamine for keeping the temperature; S3: after the reaction is completed, adding sufficient methanol until precipitation is complete, and then completing vacuum drying to obtain the modified auxiliary glue.

8. The camera foam protective film according to claim 7, characterized in that: The mass ratio of the polydichlorophosphazene, hydroxyethyl acrylate and N-acryloyloxyethyl phosphaphenanthridone is (5-6): (2-3): (1.2-1.8).

9. The camera foam protective film according to claim 8, characterized in that: The fluoroplastic release layer comprises a 40-45 μm PET film and a 5-15 μm fluoroplastic release layer; The raw materials of the fluoroplastic release layer include, by weight, 10 to 15 parts of perfluoropolyether, 1 to 1.5 parts of curing agent, 0.5 to 1 part of nanoparticles, and 70 to 90 parts of ethyl acetate.

10. A method for preparing a protective film for camera foam according to claim 9, characterized in that: The specific steps include: S1: The anthraquinone blue coating is applied to both the upper and lower surfaces of the membrane base layer at a coating speed of 2.5-3 m / min. After completion, it is dried with hot air at 80-90°C at a wind speed of 10-15 m / s for 3-5 min. S2: After the raw materials for the antistatic layer are mixed at a high speed of 400-600 rpm for 40-50 min, they are added to the extrusion coating machine and coated on the upper surface of the membrane base layer to control the thickness of the wet film. After completion, it is dried with hot air at 80-90°C at a wind speed of 10-15 m / s for 2-3 min, and then IR cured at 110-120°C for 3-5 min to obtain the antistatic layer. S3: After the raw materials for the antistatic adhesive layer are mixed, the extrusion coating machine is rotated at 1000-1200 rpm to obtain the antistatic layer. Stir at high speed for 15~20min, and then apply it to the lower surface of the film base layer, dry it with hot air at 70~75℃, wind speed 10~15m / s, 3~4min, and then perform hot pressing on a roller at 100~110℃ and 0.4~0.5MPa for 10~15s to obtain an antistatic adhesive layer; S4: Mix the raw materials of the fluoroplastic release layer and apply it to the lower surface of the PET film. The curing conditions are 120~130℃ for 4~5min. After completion, it is laminated with the antistatic adhesive layer through a precision roller pressing machine with a pressure of 0.2~0.3MPa, a temperature of 25~30℃, and a speed of 2~2.5m / min. Then, it is aged at 40~45℃ for 46~48h.

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