Composite foil and process for its production

Abstract

The application discloses a kind of composite foil and its preparation process, it is related to lithium ion battery technical field.A kind of composite foil, including polymer layer, primer layer, metal layer and protective layer;The upper surface or / and lower surface of the polymer layer is provided with primer layer, the metal layer is set to primer layer side away from polymer layer;The protective layer is set to the outer surface of metal layer.The polymer layer is modified PET, the application is modified to polymer layer, so that the epoxy group of multielement epoxy chain extender and the ring-opening reaction of PET end carboxyl group, improve the molecular weight of PET, improve the mechanical strength of PET, improve the overall mechanical properties of material;The primer layer is modified fluorosilicone resin, resin contains organic fluorine, polarity is strong, easy to agglomerate when heat curing, inorganic hybrid particle agglomerate that forms C-F bond is wrapped, thereby causing resin coating shrinkage, form protrusion, give coating excellent anti-sticking property.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a composite foil and its preparation process. Background Technology

[0002] With the pursuit of high specific energy in lithium-ion batteries, lightweighting has become a key research focus. Using polymer materials instead of metal in the intermediate layer of functional current collectors reduces weight by 50%-80% compared to pure metal current collectors, which can increase the battery's specific energy by 5%-10%. To integrate functional current collectors into batteries, an adapter welding process is required, where an adapter is welded to the functional current collector using an ultrasonic welding machine to achieve circuit conductivity. Further increasing the specific energy requires reducing the thickness of the adapter by using thinner metal foil. Summary of the Invention

[0003] The purpose of this invention is to provide a composite foil and its preparation process to solve the problems raised in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a composite foil material, comprising a polymer layer, a base layer, a metal layer, and a protective layer; the base layer is disposed on the upper surface and / or lower surface of the polymer layer, the metal layer is disposed on the side of the base layer opposite to the polymer layer; and the protective layer is disposed on the outer surface of the metal layer.

[0005] Furthermore, the polymer layer is one or more of the following: polypropylene, polyethylene, polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene ether, polystyrene, and polyamide.

[0006] The thickness of the polymer layer is 1-8 μm.

[0007] Furthermore, the metal layer material is one or a mixture of copper and aluminum;

[0008] The thickness of the metal layer is 1-3 μm.

[0009] Furthermore, the number of layers in the bottom layer is 1-2;

[0010] The thickness of the base layer is 2-5 μm.

[0011] Furthermore, the protective layer slurry comprises inorganic particles and a binder;

[0012] The inorganic particles are one or more of aluminum oxide, tin oxide, and silicon nitride;

[0013] The adhesive is a polyvinyl alcohol solution;

[0014] The protective layer has a thickness of 2-4 μm.

[0015] Further, the volume ratio of the inorganic particles to the binder is (7-9):(1-3).

[0016] A preparation process of the composite foil comprises the following steps:

[0017] A polymer layer is taken, a primer slurry is evenly applied on the upper surface and / or the lower surface of the polymer layer, a metal layer is arranged on the side of the primer slurry away from the polymer layer, and drying is performed to form a primer layer; then, a protective layer slurry is sprayed on the outer surface of the metal layer, and drying is performed to form a protective layer, thereby obtaining the composite foil.

[0018] Further, the process conditions of the drying are as follows: temperature 80-120℃, and time 3-5 min.

[0019] Further, the process conditions of the spraying are as follows: feeding rate 10-20 g / min.

[0020] Further, the polymer layer is modified PET, and the specific preparation process is as follows:

[0021] PET, a chain extender, and a polyester elastomer are blended, and melt extrusion is performed to obtain modified PET, which is drawn and shaped to form the polymer layer.

[0022] Further, the mass ratio of the PET, the chain extender, and the polyester elastomer is 100:(0.2-0.6):(2-7).

[0023] Further, the process conditions of the melt extrusion are as follows: temperature 170-210℃, and rotation speed 80-100 r / min.

[0024] Further, the chain extender is ADR-4400, which can be purchased from Shanghai Kaijin Chemical Co., Ltd.

[0025] The polyester elastomer is G5544, which can be purchased from Suzhou Laurenwiss Plasticizing Co., Ltd.

[0026] The PET is RE5329, which can be purchased from Dongguan Xingshengli Plastic New Material Technology Co., Ltd.

[0027] In the above technical solution, the chain extender is a polybasic epoxy chain extender, the epoxy groups of which can undergo ring-opening reaction with the terminal carboxyl groups of PET, thereby increasing the molecular weight of PET, improving the mechanical strength of PET, and improving the dispersibility of PET molecules during processing, reducing degradation and improving the overall mechanical properties of the material; the blending of the polyester elastomer with PET can improve the overall toughness of the material, and when subjected to impact load, the elastomer particles dispersed in the PET matrix can absorb part of the impact energy through elastic deformation, thereby reducing the impact energy on the PET matrix, and the polyester elastomer and PET have good compatibility, so that effective fusion of the two phases can be achieved without the need for additional compatibilizers.

[0028] Further, the primer layer is a modified fluorosilicon resin, and the specific preparation process is as follows:

[0029] Step (1): Mix trifluoropropyltrimethylcyclotrisiloxane and hexamethylcyclotrisiloxane, heat to 35-45℃, add concentrated sulfuric acid, react for 0.5-1h, then add tetramethyldihydrodisiloxane, react for 3-5h, adjust the pH to neutral, filter, and obtain fluorine-containing hydrogen-containing silicone oil;

[0030] Step (2): Mix the fluorine-containing hydrogen-containing silicone oil obtained in step (1) with vinyltriethoxysilane, heat and stir to react, add chloroplatinic acid, and constant-temperature react for 2-4h to obtain alkoxy-modified fluorine-containing hydrogen-containing silicone oil;

[0031] Step (3): Mix the alkoxy-modified fluorine-containing hydrogen-containing silicone oil obtained in step (2) with tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol, adjust the pH to 3-4, heat to react, slowly add distilled water, and react for 5-6h to obtain modified fluorosilicon resin.

[0032] Further, the mass ratio of trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, concentrated sulfuric acid and tetramethyldihydrodisiloxane in step (1) is (1-3):(1-5):(0.1-0.2):(2-4).

[0033] Further, the trifluoropropyltrimethylcyclotrisiloxane in step (1) has a CAS number of 2374-14-3 and can be purchased from Jiangsu Puleisi Biological Technology Co., Ltd.

[0034] The hexamethylcyclotrisiloxane has a CAS number of 541-05-9 and can be purchased from Wuhan Lalanbai Pharmaceutical and Chemical Co., Ltd.

[0035] The concentrated sulfuric acid has a CAS number of 7664-93-9 and can be purchased from Nanjing Shengqinghe Chemical Co., Ltd.

[0036] The tetramethyldihydrodisiloxane has a CAS number of 3277-26-7 and can be purchased from Wuhan Chengtian Fine Chemical Co., Ltd.

[0037] Further, the mass ratio of fluorine-containing hydrogen-containing silicone oil, vinyl triethoxysilane and chloroplatinic acid in step (2) is (0.9-1.1):1:(0.001-0.003).

[0038] Further, the process conditions for heating and stirring reaction in step (2) are: temperature 70-80℃, time 10-20min, and rotation speed 30-40r / min.

[0039] Further, the CAS number of vinyl triethoxysilane in step (2) is 1067-53-4, which can be purchased from Shandong Huachen New Material Co., Ltd.

[0040] The CAS number of chloroplatinic acid is 16941-12-1, which can be purchased from Nantong Runfeng Petroleum Chemical Co., Ltd.

[0041] Further, the molar ratio of alkoxyl-modified fluorine-containing hydrogen-containing silicone oil, tetraethyl orthosilicate, octyl triethoxysilane and anhydrous ethanol in step (3) is (4-6):(2-4):(1-3):(3-5).

[0042] Further, the process conditions for heating and stirring reaction in step (3) are: temperature 40-50℃, time 20-30min.

[0043] Further, the speed of adding distilled water dropwise in step (3) is 3-5s / drop.

[0044] Further, the CAS number of tetraethyl orthosilicate in step (3) is 78-10-4, which can be purchased from Shandong Yuanjin New Material Co., Ltd.

[0045] The CAS number of octyl triethoxysilane is 2943-75-1, which can be purchased from Guangzhou Zhongjie New Material Co., Ltd.

[0046] The CAS number of anhydrous ethanol is 64-17-5, which can be purchased from Merck.

[0047] In the above technical solution, the fluorine-containing hydrogen-containing silicone oil is generated by using trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane and tetramethyldihydrodisiloxane as raw materials, and performing ring-opening polycondensation reaction under the action of an acid catalyst; the silicon-oxygen bond in the trifluoropropyltrimethylcyclotrisiloxane is broken to form a linear siloxane chain; the terminal hydrogen group of the tetramethyldihydrodisiloxane participates in chain growth as an end-capping agent; the silicon-hydrogen bond in the fluorine-containing hydrogen-containing silicone oil has high activity, and a silicon-hydrogen addition reaction occurs between the silicon-hydrogen bond and the vinyl group of the vinyltriethoxysilane to form a silicon-carbon bond and introduce an ethoxy group, thereby generating the alkoxy-modified fluorine-containing hydrogen-containing silicone oil; the hydrolysis reaction of the ethyl silicate and the octyltriethoxysilane generates a silanol bond, and the alkoxy group in the alkoxy-modified fluorine-containing hydrogen-containing silicone oil participates in the hydrolysis to generate a fluorine-containing hydrogen-containing silanol, and the silanols generated undergo polycondensation reaction to generate a silicon-oxygen bond and form a network structure of the silicone resin, thereby obtaining the modified fluorosilicone resin; the resin contains organic fluorine, has strong polarity, and the ethyl silicate generates silica nanoparticles through hydrolysis and polycondensation, which are easy to agglomerate when being cured under heat to form an agglomerate of inorganic hybrid particles wrapped by C-F bonds, thereby causing the resin coating to shrink and form protrusions, and imparting excellent anti-sticking properties to the coating; in addition, the fluorine-containing group has strong polarity and migrates to the surface of the coating when being heated, and the organic and inorganic groups jointly reduce the surface energy of the coating; in addition, the long-chain alkyl group in the octyltriethoxysilane has good hydrophobicity, and further improves the hydrophobicity of the coating.

[0048] Compared with the prior art, the present application has the following beneficial effects:

[0049] 1. The epoxy groups of the multi-epoxy chain extender can undergo ring-opening reaction with the terminal carboxyl groups of PET, thereby increasing the molecular weight of PET, improving the mechanical strength of PET, improving the dispersibility of PET molecules during processing, reducing degradation, and improving the overall mechanical properties of the material; the blending of the polyester elastomer and PET can improve the overall toughness of the material, and when subjected to impact load, the elastomer particles dispersed in the PET matrix can absorb part of the impact energy through elastic deformation, thereby reducing the impact energy on the PET matrix, and the polyester elastomer and PET have good compatibility, so that effective fusion of the two phases can be achieved without additional compatibilizers.

[0050] 2. Modified fluorosilicone resin was prepared by using trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, and tetramethyldihydrodisiloxane as raw materials through ring-opening polycondensation, hydrosilylation, and hydrolysis polycondensation reactions. The resin contains organic fluorine, which is highly polar. Tetraethyl orthosilicate is hydrolyzed and polycondensed to generate silica nanoparticles, which are prone to agglomeration during heat curing, forming aggregates of inorganic hybrid particles wrapped with CF bonds. This causes the resin coating to shrink and form protrusions, giving the coating excellent anti-stick properties. In addition, the fluorine-containing groups have strong polarity and migrate to the coating surface when heated. Under the combined action of organic and inorganic substances, the surface energy of the coating is reduced and the hydrophobic properties are improved. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0052] In the following specific implementation,

[0053] Trifluoropropyltrimethylcyclotrisiloxane: CAS No. 2374-14-3, available from Jiangsu Pulesi Biotechnology Co., Ltd.;

[0054] Hexamethylcyclotrisiloxane: CAS No. 541-05-9, available from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.;

[0055] Concentrated sulfuric acid: CAS No. 7664-93-9, available from Nanjing Shengqinghe Chemical Co., Ltd.

[0056] Tetramethyldihydrodisiloxane: CAS No. 3277-26-7, available from Wuhan Chengtian Fine Chemical Co., Ltd.

[0057] Vinyltriethoxysilane: CAS No. 1067-53-4, available from Shandong Huachen New Materials Co., Ltd.;

[0058] Chloroplatinic acid: CAS No. 16941-12-1, available from Nantong Runfeng Petrochemical Co., Ltd.

[0059] Ethyl orthosilicate: CAS No. 78-10-4, available from Shandong Yuanjin New Materials Co., Ltd.;

[0060] Octyltriethoxysilane: CAS No. 2943-75-1, available from Guangzhou Zhongjie New Materials Co., Ltd.

[0061] Anhydrous ethanol: CAS No. 64-17-5, available from Merck Reagents;

[0062] The chain extender is ADR-4400, which can be purchased from Shanghai Kaijin Chemical Co., Ltd.

[0063] Polyester elastomer: brand G5544, which can be purchased from Suzhou Laurenwiss Plastic Co., Ltd.

[0064] PET: brand RE5329, which can be purchased from Dongguan Xingshengli Plastic New Material Technology Co., Ltd.

[0065] Preparation of the protective layer slurry: mix the inorganic particles with the binder with a concentration of 10%, stir uniformly, add polyvinyl alcohol, adjust the solid content to 50%, and stir uniformly.

[0066] The inorganic particles are alumina, CAS No. 1344-28-1, which can be purchased from Yangzhou Zhongtianli New Material Co., Ltd.

[0067] The binder is a polyvinyl alcohol solution, CAS No. 14-55-63, which can be purchased from Shandong Shoucheng Chemical Co., Ltd.

[0068] Example 1: A preparation process of a composite foil, comprising the following steps:

[0069] 1. Preparation of the polymer layer:

[0070] Blend PET, chain extender, and polyester elastomer, melt extrude to obtain modified PET, draw, shape, and form the polymer layer; the mass ratio of PET, chain extender, and polyester elastomer is 100:0.2:2; the process conditions for melt extrusion are: temperature 170℃, rotation speed 80r / min; the thickness of the polymer layer is 1μm;

[0071] 2. Preparation of the modified fluorosilicon resin:

[0072] Step (1): trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane are mixed, heated to 35 DEG C, concentrated sulfuric acid is added, and the reaction is carried out for 0.5 h, then tetramethyldihydrodisiloxane is added, and the reaction is carried out for 3 h, the pH is adjusted to neutral, and filtration is carried out to obtain fluorine-containing hydrogen-containing silicone oil; step (2): the fluorine-containing hydrogen-containing silicone oil obtained in step (1) is mixed with vinyltriethoxysilane, heated and stirred to react, chloroplatinic acid is added, and constant temperature reaction is carried out for 2 h to obtain alkoxy modified fluorine-containing hydrogen-containing silicone oil; step (3): the alkoxy modified fluorine-containing hydrogen-containing silicone oil obtained in step (2) is mixed with tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol, the pH is adjusted to 3, and the reaction is carried out by heating, and distilled water is slowly added dropwise, and the reaction is carried out for 5 h to obtain modified fluorosilicon resin; the mass ratio of trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, concentrated sulfuric acid and tetramethyldihydrodisiloxane in step (1) is 1:1:0.1:2; the mass ratio of fluorine-containing hydrogen-containing silicone oil, vinyltriethoxysilane and chloroplatinic acid in step (2) is 0.9:1:0.001; the process conditions of heating and stirring reaction in step (2) are: temperature 70 DEG C, time 10 min, rotation speed 30 r / min; the molar ratio of alkoxy modified fluorine-containing hydrogen-containing silicone oil, tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol in step (3) is 4:2:1:3; the process conditions of heating reaction in step (3) are: temperature 40 DEG C, time 20 min; the speed of adding distilled water dropwise in step (3) is 3 s / drop;

[0073] 3. Preparation of the composite foil:

[0074] Take the polymer layer, evenly smear the primer layer slurry on the upper surface or / and the lower surface of the polymer layer, set the metal layer on the side of the primer layer slurry away from the polymer layer, dry to form the primer layer, then spray the protective layer slurry on the outer surface of the metal layer, dry to form the protective layer, and obtain the composite foil; the drying process conditions are: temperature 80 DEG C, time 3 min; the thickness of the primer layer is 2 μm; the thickness of the metal layer is 1 μm; the spraying process conditions are: feeding rate 10 g / min; the thickness of the protective layer is 2 μm; the protective layer slurry comprises inorganic particles and a binder; the volume ratio of the inorganic particles to the binder is 7:3.

[0075] Example 2: a preparation process of a composite foil, comprising the following steps:

[0076] 1. Preparation of the polymer layer:

[0077] PET, chain extender and polyester elastomer are blended, melt extruded to obtain modified PET, drawn, shaped to form a polymer layer; the mass ratio of PET, chain extender and polyester elastomer is 100:0.4:5; the process conditions of melt extrusion are: temperature 190 DEG C, rotation speed 90 r / min; the thickness of the polymer layer is 4 μm;

[0078] 2. Preparation of modified fluorosilicon resin:

[0079] Step (1): Mix trifluoropropyltrimethylcyclotrisiloxane and hexamethylcyclotrisiloxane, heat to 40℃, add concentrated sulfuric acid, react for 0.7h, then add tetramethyldihydrodisiloxane, react for 4h, adjust pH to neutral, filter to obtain fluorine-containing hydrogen-containing silicone oil; Step (2): Mix the fluorine-containing hydrogen-containing silicone oil obtained in step (1) with vinyltriethoxysilane, heat and stir to react, add chloroplatinic acid, constant temperature reaction for 3h to obtain alkoxy-modified fluorine-containing hydrogen-containing silicone oil; Step (3): Mix the alkoxy-modified fluorine-containing hydrogen-containing silicone oil obtained in step (2) with tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol, adjust pH to 3, heat to react, slowly add distilled water, react for 5.5h to obtain modified fluorosilicon resin; The mass ratio of trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, concentrated sulfuric acid and tetramethyldihydrodisiloxane in step (1) is 2:3:0.1:3; The mass ratio of fluorine-containing hydrogen-containing silicone oil, vinyltriethoxysilane and chloroplatinic acid in step (2) is 1:1:0.002; The process conditions for heating and stirring reaction in step (2) are: temperature 75℃, time 15min, rotation speed 35r / min; The molar ratio of alkoxy-modified fluorine-containing hydrogen-containing silicone oil, tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol in step (3) is 5:3:2:4; The process conditions for heating to react in step (3) are: temperature 45℃, time 25min; The speed of adding distilled water in step (3) is 4s / drop;

[0080] 3. Preparation of composite foil:

[0081] Take the polymer layer, evenly smear the primer layer slurry on the upper surface or / and the lower surface of the polymer layer, set the metal layer on the side of the primer layer slurry away from the polymer layer, dry to form the primer layer, then spray the protective layer slurry on the outer surface of the metal layer, dry to form the protective layer, and obtain the composite foil; The process conditions for drying are: temperature 100℃, time 4min; The thickness of the primer layer is 4μm; The thickness of the metal layer is 2μm; The process conditions for spraying are: feeding rate 15g / min; The thickness of the protective layer is 3μm; The protective layer slurry comprises inorganic particles and a binder; The volume ratio of inorganic particles to binder is 8:2.

[0082] Example 3: A preparation process of a composite foil, comprising the following steps:

[0083] 1. Preparation of polymer layer:

[0084] Blending PET, chain extender, polyester elastomer, melt extrusion, to obtain modified PET, traction, shaping, forming a polymer layer; the mass ratio of PET, chain extender, polyester elastomer is 100:0.6:7; the process conditions of melt extrusion are: temperature 210℃, rotation speed 100r / min; the thickness of the polymer layer is 8μm;

[0085] 2, modified fluorosilicon resin preparation:

[0086] Step (1): mix trifluoropropyl trimethyl cyclotrisiloxane and hexamethyl cyclotrisiloxane, heat to 45℃, add concentrated sulfuric acid, react for 1h, then add tetramethyl dihydro disiloxane, react for 5h, adjust pH to neutral, filter to obtain fluorine-containing hydrogen-containing silicone oil; step (2): mix the fluorine-containing hydrogen-containing silicone oil obtained in step (1) with vinyl triethoxysilane, heat and stir to react, add chloroplatinic acid, constant temperature reaction for 4h to obtain alkoxy modified fluorine-containing hydrogen-containing silicone oil; step (3): mix the alkoxy modified fluorine-containing hydrogen-containing silicone oil obtained in step (2) with tetraethyl orthosilicate, octyl triethoxysilane and anhydrous ethanol, adjust pH to 4, heat to react, slowly add distilled water, react for 6h to obtain modified fluorosilicon resin; the mass ratio of trifluoropropyl trimethyl cyclotrisiloxane, hexamethyl cyclotrisiloxane, concentrated sulfuric acid and tetramethyl dihydro disiloxane in step (1) is 3:5:0.2:4; the mass ratio of fluorine-containing hydrogen-containing silicone oil, vinyl triethoxysilane and chloroplatinic acid in step (2) is 1.1:1:0.003; the process conditions of heat and stir reaction in step (2) are: temperature 80℃, time 20min, rotation speed 40r / min; the molar ratio of alkoxy modified fluorine-containing hydrogen-containing silicone oil, tetraethyl orthosilicate, octyl triethoxysilane and anhydrous ethanol in step (3) is 6:4:3:5; the process conditions of heating reaction in step (3) are: temperature 50℃, time 30min; the speed of adding distilled water in step (3) is 5s / drop;

[0087] 3, preparation of composite foil:

[0088] Take the polymer layer, evenly smear the primer layer slurry on the upper surface or / and the lower surface of the polymer layer, set the metal layer on the side of the primer layer slurry away from the polymer layer, dry to form the primer layer, then spray the protective layer slurry on the outer surface of the metal layer, dry to form the protective layer, to obtain the composite foil; the process conditions of drying are: temperature 120℃, time 5min; the thickness of the primer layer is 5μm; the thickness of the metal layer is 3μm; the process conditions of spraying are: feeding rate 20g / min; the thickness of the protective layer is 4μm; the protective layer slurry includes inorganic particles and adhesive; the volume ratio of inorganic particles and adhesive is 9:1.

[0089] Comparative Example 1: use Example 1 as a comparison, do not modify PET, the rest of the process conditions remain the same, the specific process is as follows:

[0090] 1. Preparation of modified fluorosilicon resin:

[0091] Step (1): Mix trifluoropropyltrimethylcyclotrisiloxane and hexamethylcyclotrisiloxane, heat to 35℃, add concentrated sulfuric acid, react for 0.5h, then add tetramethyldihydrodisiloxane, react for 3h, adjust pH to neutral, filter to obtain fluorine-containing hydrogen-containing silicone oil; Step (2): Mix the fluorine-containing hydrogen-containing silicone oil obtained in step (1) with vinyltriethoxysilane, heat and stir to react, add chloroplatinic acid, constant temperature reaction for 2h to obtain alkoxy-modified fluorine-containing hydrogen-containing silicone oil; Step (3): Mix the alkoxy-modified fluorine-containing hydrogen-containing silicone oil obtained in step (2) with tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol, adjust pH to 3, heat to react, slowly add distilled water dropwise, react for 5h to obtain modified fluorosilicon resin; The mass ratio of trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, concentrated sulfuric acid and tetramethyldihydrodisiloxane in step (1) is 1:1:0.1:2; The mass ratio of fluorine-containing hydrogen-containing silicone oil, vinyltriethoxysilane and chloroplatinic acid in step (2) is 0.9:1:0.001; The process conditions for heat and stirring reaction in step (2) are: temperature 70℃, time 10min, rotation speed 30r / min; The molar ratio of alkoxy-modified fluorine-containing hydrogen-containing silicone oil, tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol in step (3) is 4:2:1:3; The process conditions for heating reaction in step (3) are: temperature 40℃, time 20min; The speed of adding distilled water dropwise in step (3) is 3s / drop;

[0092] 2. Preparation of composite foil:

[0093] Take the polymer layer, evenly smear the primer layer slurry on the upper surface or / and the lower surface of the polymer layer, set the metal layer on the side of the primer layer slurry away from the polymer layer, dry to form the primer layer, then spray the protective layer slurry on the outer surface of the metal layer, dry to form the protective layer, and obtain the composite foil; The process conditions for drying are: temperature 80℃, time 3min; The thickness of the PET base layer is 1μm; The thickness of the primer layer is 2μm; The thickness of the metal layer is 1μm; The process conditions for spraying are: feeding rate 10g / min; The thickness of the protective layer is 2μm; The protective layer slurry comprises inorganic particles and a binder; The volume ratio of inorganic particles to binder is 7:3.

[0094] Comparative Example 2: Take Example 1 as a comparison, replace the primer layer with ordinary fluorosilicon resin, and the rest of the process conditions remain unchanged.

[0095] Comparative Example 3: Take Example 1 as a comparison, replace the primer layer with polyurethane adhesive, and the rest of the conditions remain unchanged.

[0096] Experiment: Take the composite foils obtained in Examples 1-3 and Comparative Examples 1-3 to detect their respective properties;

[0097] Swelling and shrinkage performance test: the composite foil is made into a sample with a length of 15 cm and a width of 2 cm, one end of which is welded with a tab, sealed and immersed in an electrolyte (LiPF6) for 24 h, and then placed in an oven at 50℃, 100℃, 150℃, 200℃, 220℃, 250℃ for 30 min. The degree of pulling of the metal layer after shrinkage of the base film of the composite foil is observed, and the swelling coefficient and shrinkage rate are measured.

[0098] Peeling strength test: the prepared sample is tested for peeling strength according to GB / T 2792-2014.

[0099] Tensile strength: the prepared sample is tested according to GB / T13022-1991.

[0100] Table 1 Swelling coefficient and thermal shrinkage rate test results of the composite foil in Example 1

[0101]

[0102] Table 2 Swelling coefficient and thermal shrinkage rate test results of the composite foil in Example 2

[0103]

[0104] Table 3 Swelling coefficient and thermal shrinkage rate test results of the composite foil in Example 3

[0105]

[0106] Table 4 Swelling coefficient and thermal shrinkage rate test results of the composite foil in Comparative Example 1

[0107]

[0108] Table 5 Swelling coefficient and thermal shrinkage rate test results of the composite foil in Comparative Example 2

[0109]

[0110] Table 6 Swelling coefficient and thermal shrinkage rate test results of the composite foil in Comparative Example 3

[0111]

[0112] Table 7 Peeling strength and tensile strength test results of the composite foil

[0113]

[0114] From Tables 1-6, the following conclusions can be drawn: when the test temperature is 50℃, the polymer layer does not expand or shrink, when the test temperature is 100℃, the polymer layer expands due to heat and does not shrink basically, when the test temperature is 150℃, the expansion coefficient of the polymer layer decreases and does not shrink basically, when the test temperature is 200-250℃, the polymer layer starts to shrink and the shrinkage rate increases with the increase of temperature.

[0115] From Table 7, the following conclusions can be drawn: the composite foil in Examples 1-3 has lower peeling strength than the composite foil in Comparative Examples 1-3, when the temperature starts to rise, the polymer layer starts to expand and is more likely to separate from the metal layer, and the tensile strength of the polymer layer is higher and is not easy to be broken, so the safety factor is higher; which fully shows that the setting of the materials of the product prepared in the present application can promote the increase of the tensile strength of the composite foil and the decrease of the peeling strength.

[0116] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application should be defined by the appended claims rather than the above description, and it is intended to include all changes falling within the meaning and scope of equivalents of the claims.

Claims

1. A composite foil, characterized by: It comprises a polymer layer, a primer layer, a metal layer and a protective layer; the upper surface and / or the lower surface of the polymer layer is provided with the primer layer, the metal layer is arranged on the side of the primer layer away from the polymer layer; and the protective layer is arranged on the outer surface of the metal layer; The preparation process of the polymer layer is as follows: PET, chain extender and polyester elastomer are blended, melt-extruded, drawn, and shaped to form the polymer layer; The primer layer is a modified fluorosilicon resin; The modified fluorosilicon resin is prepared by the following process: Step (1): mix trifluoropropyltrimethylcyclotrisiloxane and hexamethylcyclotrisiloxane, heat to 35-45℃, add concentrated sulfuric acid, react for 0.5-1h, then add tetramethyldihydrodisiloxane, react for 3-5h, adjust pH to neutral, filter to obtain fluorine-containing hydrogen-containing silicone oil; Step (2): mix the fluorine-containing hydrogen-containing silicone oil obtained in step (1) with vinyltriethoxysilane, heat and stir to react, add chloroplatinic acid, constant temperature reaction for 2-4h to obtain alkoxy-modified fluorine-containing hydrogen-containing silicone oil; Step (3): mix the alkoxy-modified fluorine-containing hydrogen-containing silicone oil obtained in step (2) with tetraethyl orthosilicate, octyltriethoxysilane and anhydrous ethanol, adjust pH to 3-4, heat to react, slowly add distilled water, react for 5-6h to obtain modified fluorosilicon resin.

2. The composite foil of claim 1, wherein: The metal layer material is copper or aluminum.

3. The composite foil of claim 1, wherein: The primer layer has 1-2 layers.

4. The process according to any one of claims 1 to 3, characterized in that: It comprises the following steps: Take the polymer layer, evenly apply the primer layer slurry on the upper surface and / or the lower surface of the polymer layer, arrange the metal layer on the side of the primer layer slurry away from the polymer layer, dry to form the primer layer and the metal layer, then spray the protective layer slurry on the outer surface of the metal layer, dry to form the protective layer, and obtain the composite foil.

5. The process for producing a composite foil according to claim 4, wherein: The mass ratio of PET, chain extender and polyester elastomer is 100: (0.2-0.6): (2-7).

6. The process of claim 4, wherein: In step (1), the mass ratio of trifluoropropyltrimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, concentrated sulfuric acid and tetramethyldihydrodisiloxane is (1-3):(1-5):(0.1-0.2):(2-4).

7. The process of claim 4, wherein: In step (2), the mass ratio of fluorine-containing hydrogen-containing silicone oil, vinyltriethoxysilane and chloroplatinic acid is (0.9-1.1):1:(0.001-0.003).

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