Adhesive tape, preparation method, outer film layer material and battery

Abstract

The invention discloses an adhesive tape, a preparation method, an outer film layer material and a battery, the adhesive tape comprises an ultra-high molecular weight polyethylene layer and polyamide film layers attached to the two sides of the ultra-high molecular weight polyethylene layer through adhesive layers respectively, and at least two polyamide film layers are attached to the two sides of the ultra-high molecular weight polyethylene layer respectively; the single-layer breakdown voltage is greater than or equal to 10kV, and the puncture strength is greater than 12N The molecular weight MW of the ultra-high molecular weight polyethylene layer is 1.5 million to 2.5 million, the film thickness is 70 to 150 microns, the single-layer breakdown voltage is greater than or equal to 20 kV, and the puncture strength is greater than 80 N. The adhesive tape provided by the invention has good barrier property, can effectively prevent permeation of substances such as oxygen and water vapor, solves the problem of insufficient barrier property of an outer coating film in the prior art, and further improves the service life and safety of the battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery outer cover films, and particularly relates to a kind of adhesive tape, preparation method, outer cover film layer material and battery, especially a kind of anti-puncture, anti-breakdown voltage adhesive tape, preparation method, outer cover film layer material and battery. BACKGROUND

[0002] With the development of science and technology, lithium batteries have become the mainstream battery choice and are widely used in mobile phones, notebooks and other fields. In the manufacturing process of lithium batteries, the outer cover film plays a crucial role. Traditional lithium battery outer cover films have low strength and poor puncture resistance, which can easily cause damage to lithium batteries and reduce their service life. In addition, existing composite films are easily punctured by sharp stones, metals and other products with spikes, and lack puncture resistance.

[0003] In recent years, with the continuous development of lithium battery technology, the requirements for outer cover films are also becoming higher and higher. In particular, in terms of preventing sticking and high temperature resistance, traditional adhesive tapes have been unable to meet the needs of modern lithium battery manufacturing. Although some anti-sticking lithium battery high-temperature-resistant adhesive tapes have appeared on the market, there are still some problems, such as insufficient thermal stability, poor anti-sticking effect, and mechanical strength and adhesion still need to be improved.

[0004] At present, lithium battery outer cover films are mainly used to protect lithium batteries from damage. However, in actual use, the outer cover film also needs to have good electrolyte resistance, puncture resistance and combustion resistance, etc. In particular, after long-term use, soft packaging films are prone to blistering, causing cracks in the aluminum foil layer, which can cause electrolyte leakage and even explosion accidents. Therefore, the development of an outer cover film with excellent puncture resistance, breakdown voltage resistance and chemical corrosion resistance is of great significance to improve the safety and service life of lithium batteries.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a kind of adhesive tape, preparation method, outer cover film layer material and battery. SUMMARY

[0006] The purpose of the present application is to provide a kind of adhesive tape, preparation method, outer cover film layer material and battery.

[0007] In order to achieve the above-mentioned purpose, the technical scheme provided by a specific embodiment of the present application is as follows:

[0008] The adhesive tape comprises an ultrahigh molecular weight polyethylene layer and two polyamide film layers on both sides of the ultrahigh molecular weight polyethylene layer, and each side of the ultrahigh molecular weight polyethylene layer is attached to two polyamide film layers through an adhesive layer:

[0009] The film thickness of the polyamide film layer is controlled to be 15-50 μm, the single-layer breakdown voltage is ≥10 kV, and the puncture strength is greater than 12 N.

[0010] The molecular weight MW of the ultra-high molecular weight polyethylene layer is 1.5 million to 2.5 million, the film thickness is 70 to 150 μm, the single layer breakdown voltage is ≥ 20 kV, and the puncture strength is greater than 80N.

[0011] In one or more embodiments of the present invention, the raw materials of the polyamide film layer include, by weight:

[0012] Polyamide 66 resin: 90%-93%;

[0013] Toughening agent: 1%-3%;

[0014] First antioxidant: 0.5%-1%;

[0015] Weathering agent: 1%-2%;

[0016] Nano-montmorillonite residue.

[0017] In one or more embodiments of the present invention, the raw materials of the ultra-high molecular weight polyethylene layer include, by weight:

[0018] Ultra-high molecular weight polyethylene resin: 95%-97%;

[0019] Second antioxidant: 0.5%-1%;

[0020] Lubricant: 0.5%-1%;

[0021] Nanoenhancer balance.

[0022] In one or more embodiments of the present invention, the raw materials of the adhesive layer include, by weight:

[0023] Main resin: 60%-70%;

[0024] Curing agent: 2%-3%;

[0025] Diluent: 5%-10%;

[0026] Coupling agent: 1%-2%;

[0027] Nano insulation filler allowance.

[0028] In one or more embodiments of the present invention, the ultra-high molecular weight polyethylene layer is prepared as follows:

[0029] Mixing: Add ultra-high molecular weight polyethylene resin, second antioxidant, lubricant, and nano-enhancer according to the formula ratio into a high-speed mixer and mix at 80-100°C for 15-20 minutes to evenly disperse the components;

[0030] Melt extrusion: Add the mixed materials into the twin-screw extruder, control the extrusion temperature at 180-220℃, and the screw speed at 30-50r / min. The materials are melted and plasticized by the extruder and extruded into thick sheets;

[0031] Stretching: The extruded thick sheet is biaxially stretched on a stretching machine. The longitudinal stretching temperature is 110-120℃ and the stretching ratio is 3-5 times; the transverse stretching temperature is 120-130℃ and the stretching ratio is 3-4 times;

[0032] Cooling and shaping: The stretched film is cooled to room temperature via a cooling roller, and then rolled up after shaping to obtain an ultra-high molecular weight polyethylene layer with a thickness of 70-150 μm.

[0033] In one or more embodiments of the present invention, the polyamide film layer is prepared as follows:

[0034] Ingredients: Add polyamide 66 resin, toughening agent, first antioxidant, weathering agent and nano-montmorillonite into the mixing equipment according to the formula, and mix at 100-120℃ for 20-30 minutes;

[0035] Melt extrusion: add the mixed material into a single screw extruder, the extrusion temperature is 230-260℃, the screw speed is 40-60r / min, and the film is extruded;

[0036] Casting: The film blank is cooled by cooling casting rollers and formed into thick sheets;

[0037] Stretching: The thick film is subjected to biaxial stretching, with the longitudinal stretching temperature at 60-70°C and the stretching ratio at 2.5-3.5 times; the transverse stretching temperature at 120-140°C and the stretching ratio at 2.5-3 times, so that the film thickness reaches 15-50μm;

[0038] Heat setting: The stretched film is heat-set at 160-180°C for 10-20 seconds, then cooled and rolled up.

[0039] In one or more embodiments of the present invention, a method for preparing an adhesive tape includes:

[0040] Preparing slurry for coating the ultra-high molecular weight polyethylene layer, the polyamide film layer, and the adhesive layer;

[0041] Adhesive coating: The bonding surfaces of the ultra-high molecular weight polyethylene layer and the polyamide film layer are pre-treated by plasma treatment, and the prepared slurry is evenly coated on both sides of the ultra-high molecular weight polyethylene layer and the bonding surface of the polyamide film layer through a doctor blade coater. The coating thickness is controlled at 50-100 μm.

[0042] Laminating: firstly, laminating the first layer of polyamide film on one side of the ultra-high molecular weight polyethylene layer, aligning the ultra-high molecular weight polyethylene layer coated with adhesive with the polyamide film, and roll-combining; then laminating other polyamide films on the same side, the adjacent two layers are overlapped in a cross-over manner, and the hot-pressing parameters are the same as those of the first layer of lamination; according to the same method and parameters, laminating two layers of polyamide film on the other side of the ultra-high molecular weight polyethylene layer; after the lamination is completed, the adhesive tape is sent into a curing chamber for curing treatment, the curing temperature is 130-140 DEG C, and the curing time is 3-3.5 h.

[0043] In one or more embodiments of the present application, the cross-over is that the longitudinal stretching directions of the adjacent two layers of polyamide film are perpendicular or cross at an angle of 60 DEG or 45 DEG.

[0044] In one or more embodiments of the present application, the battery outer film layer material comprises an adhesive tape.

[0045] In one or more embodiments of the present application, the battery comprises a battery body and a battery outer film layer material wrapped outside the battery body.

[0046] Compared with the prior art, the adhesive tape, the preparation method, the outer film layer material and the battery of the present application significantly improve the puncture strength and the anti-piercing voltage of the adhesive tape by adopting a multi-layer composite structure design and by being equipped with multiple protective layers such as adhesive + PA film + ultra-high molecular weight polyethylene layer, solve the problems of low strength and poor puncture resistance of traditional outer films, effectively prevent the battery from being punctured and damaged, and prolong the service life of the battery.

[0047] The multi-layer composite structure design of the present application, especially the addition of the ultra-high molecular weight polyethylene layer, improves the puncture resistance of the adhesive tape, so that it can effectively resist the puncture of products with thorns such as stones and metals, and overcomes the disadvantage that the existing composite film is easily broken when facing stones, metals and other products with thorns.

[0048] The adhesive tape of the present application has excellent anti-piercing voltage performance, and the single-layer piercing voltage can reach more than 20KV, effectively preventing the battery from being pierced when leaking, and improving the safety and service life of the battery.

[0049] The multi-layer composite structure design of the present application significantly improves the thermal stability of the adhesive tape by multiple compounding of the adhesive and the PA film, effectively solves the problem of insufficient thermal stability of the traditional anti-sticking knife lithium battery resistant adhesive tape, and meets the requirements of modern lithium battery manufacturing on the thermal stability of the outer film.

[0050] The adhesive tape of the present application has good barrier performance, which can effectively prevent the penetration of oxygen, water vapor and other substances, solves the problem of insufficient barrier performance of the outer film in the prior art, and further improves the service life and safety of the battery. DETAILED DESCRIPTION

[0051] In order to better understand the technical solutions in the present disclosure for those skilled in the art, the technical solutions in the present disclosure will be clearly and completely described below in combination with the disclosed embodiments of the present disclosure. Obviously, the described embodiments are only some of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present disclosure.

[0052] The present application aims to overcome the shortcomings in the prior art and provide a tape with excellent puncture resistance and anti-breakdown voltage. The tape adopts a multi-layer composite structure design, which can specifically include a multi-layer structure formed by sequentially compositing an adhesive layer, a polyamide film layer, an adhesive layer, a polyamide film layer, an adhesive layer, an ultra-high molecular weight polyethylene layer, an adhesive layer, a polyamide film layer, an adhesive layer, and a polyamide film layer.

[0053] The polyamide film layer is made of polyamide 66 as the main material, with a film thickness controlled at 15-50 μm, a single-layer breakdown voltage ≥10 kV, and a puncture strength greater than 12 N. The ultra-high molecular weight polyethylene layer is made of ultra-high molecular weight polyethylene material, with a molecular weight MW of 1.5-2.5 million, a film thickness of 70-150 μm, a single-layer breakdown voltage ≥20 kV, and a puncture strength greater than 80 N.

[0054] The adhesive layer adopts polyurethane adhesive or high-performance acrylic adhesive, i.e., the main resin is polyurethane or polyacrylic acid, with good high-temperature resistance and adhesion.

[0055] In the multi-layer structure, the thickness of the adhesive layer is controlled at 50-100 μm, the thickness of the polyamide film layer is 2-3 times greater than that of the adhesive layer, and the thickness of the ultra-high molecular weight polyethylene layer is 2-3 times greater than that of the polyamide film layer. By reasonably designing the thickness ratio of each layer, the tape has good mechanical strength and electrical resistance.

[0056] By adjusting the thickness and width of the tape, it can be adjusted according to the specific application requirements. The puncture strength of the tape is ≥140 N, the breakdown voltage is ≥50 kV, and it has excellent puncture resistance and breakdown voltage resistance.

[0057] An anti-sticking texture structure can also be provided on the surface of the tape. By engraving grooves with a depth of 10-20 μm on the surface of the tape, the groove spacing is 1-2 mm, which can effectively improve the adhesion resistance of the tape and prevent it from falling off due to excessive adhesion during use.

[0058] I. Material composition

[0059] (I) Ultra-high molecular weight polyethylene layer formula

[0060] UHMWPE resin (molecular weight 1.5-2.5 million): 95-97%;

[0061] Second antioxidant (e.g. 1010): 0.5-1%, which can delay the oxidation aging of the material during processing and use, and maintain its mechanical and insulating properties;

[0062] Lubricant (e.g. calcium stearate): 0.5-1%, which improves the processing flowability of the material and ensures uniform molding;

[0063] Nanometer reinforcing agent (e.g. nano-silicon dioxide): the balance, which can be uniformly dispersed in the resin matrix, improve the puncture resistance and insulation strength of the material, and enhance the stability of the overall structure.

[0064] In the present application, the UHMWPE layer is subjected to special stretching treatment, so that the molecular chain arrangement is more regular, further improving its mechanical properties and insulating properties. At the same time, the impurity content (such as ash) in the material should be ≤0.01%, to avoid impurities becoming a weak point of breakdown.

[0065] (ii) Polyamide film layer formula

[0066] Polyamide 66 resin: 90-93%;

[0067] Toughening agent (e.g. ethylene-vinyl acetate copolymer): 1-3%, which improves the toughness of the film and reduces brittle fracture during puncture;

[0068] First antioxidant (e.g. 168): 0.5-1%, which prevents the material from oxidizing and aging;

[0069] Weathering agent (e.g. ultraviolet absorber UV-531): 1-2%, which enhances the weather resistance of the film and ensures stable performance in outdoor environments;

[0070] Nanometer montmorillonite: the balance, which can improve the barrier properties and mechanical properties of the film, and further enhance the puncture resistance and voltage breakdown effect.

[0071] The polyamide film in the present application has good chemical resistance and dimensional stability. When the temperature change range is -40°C to 120°C, its thermal shrinkage rate should be ≤1.5%, to ensure the performance stability of the adhesive tape in different environments. In addition, the surface roughness Ra of the film should be controlled in the range of 0.05-0.1 μm, to improve the bonding force with the adhesive layer.

[0072] (iii) Adhesive layer formula

[0073] Main resin (e.g. E-51): 60-70%;

[0074] Curing agent (such as polyamide 650): 2%-3%, which has a curing reaction with the main body resin to form a firm adhesive layer;

[0075] Diluent (such as propylene glycol methyl ether acetate): 5%-10%, which adjusts the viscosity of the adhesive for convenient coating;

[0076] Coupling agent (such as KH-550): 1%-2%, which enhances the interfacial bonding force of the adhesive with the ultra-high molecular weight polyethylene layer and the polyamide film layer;

[0077] Nanometer insulating filler (such as nanometer boron nitride) in excess, which improves the insulating performance and thermal conductivity of the adhesive to avoid local overheating affecting the breakdown performance.

[0078] In the present application, a main body resin adhesive with excellent insulating performance, high temperature resistance and aging resistance is selected. The adhesive should meet the requirements of volume resistivity ≥10 14 Ω·cm, dielectric constant ≤3.5 (1 MHz) to ensure that it does not have a negative impact on the overall insulating performance. At the same time, its peel strength should be ≥5 N / cm to ensure firm bonding between the layers and avoid performance degradation due to separation between the layers.

[0079] II. Layer preparation process

[0080] (I) Ultra-high molecular weight polyethylene layer preparation process

[0081] Mixing: The ultra-high molecular weight polyethylene resin, the second antioxidant, the lubricant and the nanometer reinforcing agent are added to a high-speed mixer in the proportion of the formula, and mixed at 80-100℃ for 15-20 minutes to make the components uniformly dispersed;

[0082] Melt extrusion: The mixed material is added to a double screw extruder, and the extrusion temperature is controlled at 180-220℃, and the screw rotation speed is 30-50 r / min. The material is melted and plasticized by the extruder and extruded into a thick sheet;

[0083] Stretching: The extruded thick sheet is stretched in a stretching machine, the longitudinal stretching temperature is 110-120℃, and the stretching multiple is 3-5 times; the transverse stretching temperature is 120-130℃, and the stretching multiple is 3-4 times. The molecular chain is oriented by stretching to improve the crystallinity and mechanical properties of the material, and the insulating performance is also enhanced;

[0084] Cooling and setting: The stretched film is cooled to room temperature by a cooling roller, and then wound after setting to obtain the ultra-high molecular weight polyethylene layer.

[0085] (II) Polyamide film layer preparation process

[0086] Ingredients: according to the formula, polyamide 66 resin, toughening agent, first antioxidant, weathering agent, nano montmorillonite are added into mixing equipment, mixed at 100-120℃ for 20-30 minutes;

[0087] Melt extrusion: the mixed material is added into a single screw extruder, the extrusion temperature is 230-260℃, the screw rotation speed is 40-60r / min, and the film blank is extruded;

[0088] Sheet casting: the film blank is cooled and formed into a thick sheet by a cooling sheet casting roller (temperature 20-30℃);

[0089] Stretching: the thick sheet is bidirectionally stretched, the longitudinal stretching temperature is 60-70℃, the stretching multiple is 2.5-3.5 times; the transverse stretching temperature is 120-140℃, the stretching multiple is 2.5-3 times, so that the thickness of the film reaches 15-50μm, and the mechanical properties and insulation properties are improved;

[0090] Heat setting: the film after stretching is heat set at 160-180℃ for 10-20 seconds to eliminate internal stress and improve dimensional stability, and then cooled and wound.

[0091] III. Layer bonding process

[0092] (1) Adhesive coating

[0093] The bonding surfaces of the ultra-high molecular weight polyethylene layer and the polyamide film layer are pretreated by plasma treatment (power 100-200W, treatment time 10-20 seconds) to improve surface activity and enhance the bonding force with the adhesive;

[0094] The prepared adhesive is uniformly coated on both sides of the ultra-high molecular weight polyethylene layer and the bonding surface of the polyamide film layer by a doctor blade coater, and the coating thickness is controlled at 5-10μm. During the coating process, ensure that the coating is uniform, without bubbles and missing coating.

[0095] (2) Multi-layer bonding (here taking two layers on each side as an example)

[0096] First, the first layer of polyamide film is bonded on one side of the ultra-high molecular weight polyethylene layer, and the ultra-high molecular weight polyethylene layer coated with adhesive is aligned with the polyamide film for roll pressing and compounding;

[0097] Then, the second layer of polyamide film is bonded on the same side, and the adjacent two layers are overlapped in a crosswise manner (such as the longitudinal stretching direction of the film adjacent to the first layer of polyamide film is perpendicular to the first layer or 60° crosswise or 45° crosswise, etc.), and the hot pressing parameters are the same as those of the first layer bonding;

[0098] According to the same method and parameters as above, two layers of polyamide film are bonded on the other side of the ultra-high molecular weight polyethylene layer.

[0099] After the lamination is completed, the tape is sent to the curing room for curing treatment. The curing temperature is 130-140℃ and the curing time is 3-3.5h to fully cure the adhesive and ensure that each layer is firmly bonded.

[0100] When compounding two layers of polyamide film, a hot pressing compounding process can be used, with the temperature controlled at 120-150°C and the pressure controlled at 0.5-1.0 MPa. When compounding a polyamide film layer on the outside of an ultra-high molecular weight polyethylene layer, a cold bonding compounding process can be used, with the pressure controlled at 0.8-1.2 MPa. The roller speed can be 5-10 m / min. When laminating the layers, the pressing parameters should be reasonably controlled to ensure that the adhesive can fully infiltrate the surface of each layer of material, improve the bonding strength between the layers, and reduce the generation of bubbles between the layers. The presence of bubbles will lead to electric field concentration, reduce the breakdown voltage, and also affect the puncture resistance.

[0101] Through a strict curing process, the adhesive is ensured to be fully cured and form stable chemical bonds, thereby ensuring the long-term stability of the mechanical properties and insulation properties of the tape.

[0102] Furthermore, the two polyamide film layers laminated on either side of the ultra-high molecular weight polyethylene layer are cross-stacked. This means that the molecules of the two adjacent polyamide film layers are arranged perpendicularly, or cross-stacked at 60° or 45°. This structure effectively disperses external forces and improves overall puncture resistance. Furthermore, this cross-stacked structure reduces electric field concentration, which helps improve voltage breakdown performance.

[0103] Furthermore, the edges of the tape can be rounded to avoid right angles or sharp corners. This is because electric field concentration tends to occur at right angles or sharp corners, resulting in a lower breakdown voltage. The radius of the rounded transition should be ≥0.5mm to ensure uniform electric field distribution at the edges.

[0104] Including but not limited to the following examples, the performance test of the samples adopts the following scheme:

[0105] (1) Puncture resistance test

[0106] The tape is punctured using a 1.0mm diameter steel needle at a speed of 100mm / min. Each sample is tested at five points and the average value is taken. The tape's puncture strength is required to be ≥100N to ensure it can withstand puncture from sharp objects during actual use.

[0107] (2) Voltage breakdown performance test

[0108] At 25°C and 50% relative humidity, the tapes were subjected to a breakdown test using an AC voltage (50Hz) at a ramp rate of 1kV / s. Each sample was tested three times, and the average value was taken. The tape's breakdown voltage was required to be ≥30kV to meet the requirements of high-voltage environments.

[0109] (3) Aging resistance test

[0110] The tape samples were placed in an environment with a temperature of 85°C and a relative humidity of 85% for 1000 hours, and then their puncture resistance and voltage breakdown performance were tested. The puncture resistance strength drop rate after aging was required to be ≤10%, and the breakdown voltage drop rate was required to be ≤15%, to ensure the stability of the tape's performance during long-term use.

[0111] The following additives are used in the following examples: the first antioxidant is 168; the weathering agent is the ultraviolet absorber UV-531; the toughening agent is ethylene-vinyl acetate copolymer; the nano-reinforcement agent is nano-silica with a particle size of 5 nm; the lubricant is calcium stearate; the second antioxidant is 1010; and the molecular weight of the ultra-high molecular weight polyethylene resin is 1.7 million.

[0112] Example 1:

[0113] The puncture-resistant and burst-resistant voltage tape of this embodiment includes a multilayer structure formed by compounding in sequence a first adhesive layer, a first polyamide film layer, a second adhesive layer, a second polyamide film layer, a third adhesive layer, an ultra-high molecular weight polyethylene layer, a fourth adhesive layer, a third polyamide film layer, a fifth adhesive layer and a fourth polyamide film layer.

[0114] Among them, each polyamide film layer is made of polyamide 66 as the main material, and its raw materials include, wt%: polyamide 66 resin: 90%; toughening agent: 1%; first antioxidant: 0.5%; weathering agent: 1%; nano-montmorillonite remainder, and the film thickness is controlled at 20μm. The preparation method is as follows: Ingredients: Add polyamide 66 resin, toughening agent, first antioxidant, weathering agent and nano-montmorillonite into a mixing device according to the formula, and mix at 100°C for 20 minutes; Melt extrusion: Add the mixed material into a single-screw extruder, the extrusion temperature is 230°C, the screw speed is 40r / min, and extrudes into a film blank; Casting: Cool the film blank through a cooling casting roller to form a thick sheet; Stretching: Biaxially stretch the thick sheet, the longitudinal stretching temperature is 60°C, and the stretching ratio is 2.5 times; the transverse stretching temperature is 120°C, and the stretching ratio is 2.5 times, so that the film thickness meets the requirements; Heat setting: The stretched film is heat-set at 160°C for 10 seconds, and then cooled and rolled up.

[0115] The ultra-high molecular weight polyethylene (UHMWPE) layer is made of UHMWPE material, comprising the following raw materials: 95% UHMWPE resin, 0.5% secondary antioxidant, 0.5% lubricant, and the balance nano-enhancer, with a film thickness of 80 μm. The preparation process includes: mixing: adding the UHMWPE resin, secondary antioxidant, lubricant, and nano-enhancer according to the formula ratio to a high-speed mixer and mixing at 80°C for 15 minutes to uniformly disperse the components; melt extrusion: adding the mixed materials to a twin-screw extruder, controlling the extrusion temperature at 180°C and the screw speed at 30 rpm, where the materials are melted, plasticized, and extruded into a thick sheet; stretching: biaxially stretching the extruded sheet on a stretching machine at a longitudinal stretching temperature of 110°C and a stretching ratio of 3x; and a transverse stretching temperature of 120°C and a stretching ratio of 3x. Cooling and shaping: cooling the stretched film to room temperature via cooling rollers, shaping it, and then winding it to obtain the UHMWPE layer.

[0116] Each adhesive layer uses polyurethane adhesive, and its raw materials include, wt%: main resin: 60%; curing agent: 2%; diluent: 5%; coupling agent: 1%; nano insulating filler as balance, solid content is 80-85%, melting temperature is 120-150℃, and adhesion is ≥0.5MPa.

[0117] The preparation of the tape is as follows: prepare a slurry for coating an ultra-high molecular weight polyethylene layer, a polyamide film layer and an adhesive layer; adhesive coating: pre-treat the bonding surfaces of the ultra-high molecular weight polyethylene layer and the polyamide film layer by plasma treatment, and evenly coat the prepared slurry on both sides of the ultra-high molecular weight polyethylene layer and the bonding surface of the polyamide film layer through a doctor blade coater, and the coating thickness is controlled at 5 μm; bonding: first bond the first layer of polyamide film on one side of the ultra-high molecular weight polyethylene layer, align the ultra-high molecular weight polyethylene layer coated with adhesive with the polyamide film, and perform roller pressing and compounding; then bond other polyamide films on the same side, and the adjacent two layers are vertically cross-stacked, and the hot pressing parameters are the same as those for the first layer; according to the same method and parameters as above, bond two layers of polyamide film on the other side of the ultra-high molecular weight polyethylene layer; after bonding, send the tape into the curing chamber for curing treatment, the curing temperature is 130°C, and the curing time is 3 hours. The polyamide film layers are bonded together using a hot-pressing process, with the temperature controlled at 130°C and the pressure controlled at 0.6 MPa. The ultra-high molecular weight polyethylene layer and the polyamide film layer are bonded together using a cold-adhesion process, with the pressure controlled at 1.0 MPa.

[0118] The tape is 15mm wide. By adjusting the thickness and width of the tape, it can be tailored to specific application requirements. The tape has a puncture strength of ≥150N and a breakdown voltage of ≥55kV, demonstrating excellent puncture resistance and breakdown voltage performance. After aging, the puncture strength decreases by ≤10%, and the breakdown voltage decreases by ≤15%.

[0119] An anti-sticking structure is set on the surface of the tape. By engraving grooves with a depth of 15μm and a groove spacing of 1.5mm on the surface of the tape, the tape's adhesion resistance can be effectively improved to prevent it from falling off due to excessive adhesion during use.

[0120] Example 2:

[0121] The puncture-resistant and burst-resistant voltage tape of this embodiment includes a multilayer structure formed by compounding in sequence a first adhesive layer, a first polyamide film layer, a second adhesive layer, a second polyamide film layer, a third adhesive layer, an ultra-high molecular weight polyethylene layer, a fourth adhesive layer, a third polyamide film layer, a fifth adhesive layer and a fourth polyamide film layer.

[0122] Among them, each polyamide film layer is made of polyamide 66 as the main material, and its raw materials include, wt%: polyamide 66 resin: 93%; toughening agent: 3%; first antioxidant: 1%; weathering agent: 2%; nano-montmorillonite balance, and the film thickness is controlled at 45μm. The preparation method is as follows: Ingredients: Add polyamide 66 resin, toughening agent, first antioxidant, weathering agent and nano-montmorillonite into a mixing device according to the formula, and mix at 120°C for 30 minutes; Melt extrusion: Add the mixed material into a single-screw extruder, the extrusion temperature is 260°C, the screw speed is 60r / min, and extrudes into a film blank; Casting: Cool the film blank through a cooling casting roller to form a thick sheet; Stretching: Biaxially stretch the thick sheet, the longitudinal stretching temperature is 70°C, the stretching ratio is 3.5 times; the transverse stretching temperature is 140°C, the stretching ratio is 3 times, so that the film thickness meets the requirements; Heat setting: The stretched film is heat-set at 180°C for 20 seconds, and then cooled and rolled up.

[0123] The ultra-high molecular weight polyethylene (UHMWPE) layer is made of UHMWPE material, comprising the following raw materials: 97% UHMWPE resin, 1% secondary antioxidant, 1% lubricant, and the balance nano-enhancer, with a film thickness of 130 μm. The preparation process includes: mixing: adding the UHMWPE resin, secondary antioxidant, lubricant, and nano-enhancer according to the formula ratio to a high-speed mixer and mixing at 100°C for 20 minutes to uniformly disperse the components; melt extrusion: adding the mixed materials to a twin-screw extruder, controlling the extrusion temperature at 220°C and the screw speed at 50 r / min, where the materials are melted, plasticized, and extruded into a thick sheet; stretching: biaxially stretching the extruded sheet on a stretching machine at a longitudinal stretching temperature of 120°C and a stretching ratio of 5; and a transverse stretching temperature of 130°C and a stretching ratio of 4; cooling and shaping: cooling the stretched film to room temperature via cooling rollers, shaping it, and then winding it to obtain the UHMWPE layer.

[0124] Each adhesive layer uses polyurethane adhesive, and its raw materials include, wt%: main resin: 70%; curing agent: 3%; diluent: 10%; coupling agent: 2%; nano insulating filler as balance, solid content is 82%, melting temperature is 125-145℃, and adhesion is ≥0.6MPa.

[0125] The preparation of the tape is as follows: prepare a slurry for coating an ultra-high molecular weight polyethylene layer, a polyamide film layer and an adhesive layer; adhesive coating: pre-treat the bonding surfaces of the ultra-high molecular weight polyethylene layer and the polyamide film layer by plasma treatment, and evenly coat the prepared slurry on both sides of the ultra-high molecular weight polyethylene layer and the bonding surface of the polyamide film layer through a doctor blade coater, and the coating thickness is controlled at 10 μm; bonding: first bond the first layer of polyamide film on one side of the ultra-high molecular weight polyethylene layer, align the ultra-high molecular weight polyethylene layer coated with adhesive with the polyamide film, and perform roller pressing and compounding; then bond other polyamide films on the same side, and the adjacent two layers are vertically cross-stacked, and the hot pressing parameters are the same as those for the first layer; according to the same method and parameters as above, bond two layers of polyamide film on the other side of the ultra-high molecular weight polyethylene layer; after bonding, send the tape into a curing chamber for curing treatment, the curing temperature is 140°C, and the curing time is 3.5 hours. The polyamide film layers are bonded together using a hot-pressing process, with the temperature controlled at 145°C and the pressure controlled at 0.8 MPa. The ultra-high molecular weight polyethylene layer and the polyamide film layer are bonded together using a cold-adhesion process, with the pressure controlled at 1.2 MPa.

[0126] The width of the adhesive tape is 28 mm. By adjusting the thickness and width of the adhesive tape, the specific application requirements can be adjusted. The puncture strength of the adhesive tape is ≥160 N, the breakdown voltage is ≥60 kV, and the adhesive tape has excellent puncture resistance and breakdown voltage resistance. The puncture strength of the sample after aging decreases by ≤10%, and the breakdown voltage decreases by ≤15%.

[0127] The anti-sticking structure is arranged on the surface of the adhesive tape. By engraving grooves with a depth of 18 μm on the surface of the adhesive tape, the groove spacing is 1.8 mm, which can effectively improve the anti-sticking performance of the adhesive tape, and prevent the adhesive tape from falling off due to excessive adhesion during use.

[0128] Example 3

[0129] The puncture-resistant and breakdown voltage-resistant adhesive tape of the embodiment comprises a first adhesive layer, a first polyamide film layer, a second adhesive layer, a second polyamide film layer, a third adhesive layer, an ultrahigh molecular weight polyethylene layer, a fourth adhesive layer, a third polyamide film layer, a fifth adhesive layer, and a fourth polyamide film layer, which are sequentially compounded to form a multilayer structure.

[0130] The polyamide film layers are made of polyamide 66 as the main material, and the raw materials include, wt%: polyamide 66 resin: 91%; toughening agent: 2%; first antioxidant: 0.75%; weathering agent: 1.5%; and the balance of nano-montmorillonite, and the film thickness is controlled at 30 μm. The preparation is as follows: batching: according to the formula, the polyamide 66 resin, the toughening agent, the first antioxidant, the weathering agent, and the nano-montmorillonite are added to the mixing equipment and mixed at 110℃ for 25 minutes; melt extrusion: the mixed material is added to a single screw extruder, the extrusion temperature is 245℃, the screw rotation speed is 50 r / min, and the extruded film blank is obtained; casting: the film blank is cooled and formed into a thick piece by a cooling casting roller; stretching: the thick piece is stretched in two directions, the longitudinal stretching temperature is 65℃, and the stretching multiple is 3 times; the transverse stretching temperature is 130℃, and the stretching multiple is 2.75 times, so that the thickness of the film meets the requirements; heat setting: the stretched film is heat set at 170℃ for 15 seconds, and then cooled and wound.

[0131] The ultra-high molecular weight polyethylene layer is made of ultra-high molecular weight polyethylene material, and the raw materials include, wt%: ultra-high molecular weight polyethylene resin: 96%; second antioxidant: 0.75%; lubricant: 0.75%; nano reinforcing agent: the rest; and the film thickness is 100 μm. The preparation is as follows: mixing: the ultra-high molecular weight polyethylene resin, the second antioxidant, the lubricant and the nano reinforcing agent are added into a high-speed mixer in the formula proportion, and mixed at 90°C for 17.5 minutes, so that the components are uniformly dispersed; melt extrusion: the mixed material is added into a double screw extruder, the extrusion temperature is controlled at 200°C, the screw rotation speed is 40 r / min, the material is melt plasticized and extruded into a thick sheet through the extruder; stretching: the extruded thick sheet is stretched on a stretching machine, the longitudinal stretching temperature is 115°C, and the stretching multiple is 4 times; the transverse stretching temperature is 125°C, and the stretching multiple is 3.5 times; cooling and setting: the stretched film is cooled to room temperature through a cooling roller, and is wound after setting, so that the ultra-high molecular weight polyethylene layer is obtained.

[0132] Each adhesive layer is made of polyurethane adhesive, and the raw materials include, wt%: main body resin: 65%; curing agent: 2.5%; diluent: 7%; coupling agent: 1.5%; nano insulating filler: the rest; the solid content is 82%, the melting temperature is 125-133°C, and the adhesion is ≥0.5 MPa.

[0133] The preparation of the adhesive tape is as follows: preparing the ultra-high molecular weight polyethylene layer, the polyamide film layer and the adhesive layer coating slurry; adhesive coating: the adhering surfaces of the ultra-high molecular weight polyethylene layer and the polyamide film layer are pretreated by plasma treatment, the prepared slurry is uniformly coated on the two sides of the ultra-high molecular weight polyethylene layer and the adhering surfaces of the polyamide film layer by a knife coating machine, and the coating thickness is controlled at 7 μm; adhering: first, the first layer of polyamide film is adhered on one side of the ultra-high molecular weight polyethylene layer, the ultra-high molecular weight polyethylene layer coated with adhesive is aligned with the polyamide film, and is roll-pressed and compounded; then, the other polyamide films are adhered on the same side, the adjacent two layers are overlapped in a vertical cross manner, and the hot pressing parameters are the same as those of the first layer adhering; the two layers of polyamide films are adhered on the other side of the ultra-high molecular weight polyethylene layer in the same way and with the same parameters; after the adhering is completed, the adhesive tape is sent into a curing chamber for curing treatment, the curing temperature is 135°C, and the curing time is 3.3 h. The polyamide film layers are adhered by hot pressing and compounding process, the temperature is controlled at 135°C, and the pressure is controlled at 0.8 MPa. The ultra-high molecular weight polyethylene layer and the polyamide film layer are adhered by cold adhesive compounding process, and the pressure is controlled at 1.05 MPa.

[0134] The tape width ranges from 15-25mm. By adjusting the thickness and width of the tape, it can be tailored to specific application requirements. The tape has a puncture strength of ≥153N and a breakdown voltage of ≥57kV, demonstrating excellent puncture resistance and breakdown voltage performance. After aging, the puncture strength decreases by ≤10%, and the breakdown voltage decreases by ≤15%.

[0135] An anti-sticking structure is set on the surface of the tape. By engraving grooves with a depth of 15μm and a groove spacing of 1.5mm on the surface of the tape, the tape's adhesion resistance can be effectively improved to prevent it from falling off due to excessive adhesion during use.

[0136] Example 4:

[0137] The only difference between this embodiment and embodiment 2 is that the thickness of each polyamide film layer is controlled at 15 μm.

[0138] The puncture strength of the sample in this embodiment is ≥155N, and the breakdown voltage is ≥58kV. After aging, the puncture strength decrease rate of the sample is ≤9%, and the breakdown voltage decrease rate is ≤15%.

[0139] Example 5:

[0140] The only difference between this embodiment and embodiment 2 is that the thickness of each polyamide film layer is controlled at 50 μm.

[0141] The puncture strength of the sample in this embodiment is ≥168N, and the breakdown voltage is ≥67kV. After aging, the puncture strength decrease rate of the sample is ≤10%, and the breakdown voltage decrease rate is ≤11%.

[0142] Example 6:

[0143] The only difference between this embodiment and embodiment 2 is that the ultra-high molecular weight polyethylene layer has a thickness of 150 μm.

[0144] The puncture strength of the sample in this embodiment is ≥172N, and the breakdown voltage is ≥69kV. After aging, the puncture strength decrease rate of the sample is ≤12%, and the breakdown voltage decrease rate is ≤13%.

[0145] Example 7:

[0146] The only difference between this embodiment and embodiment 2 is that the ultra-high molecular weight polyethylene layer has a thickness of 70 μm.

[0147] The puncture strength of the sample in this embodiment is ≥155N, and the breakdown voltage is ≥57kV. After aging, the puncture strength decrease rate of the sample is ≤11%, and the breakdown voltage decrease rate is ≤12%.

[0148] Example 8:

[0149] The only difference between this embodiment and embodiment 6 is that two adjacent polyamide films cross each other at 60 degrees.

[0150] The puncture strength of the sample in this embodiment is ≥175N, and the breakdown voltage is ≥74kV. After aging, the puncture strength decrease rate of the sample is ≤9%, and the breakdown voltage decrease rate is ≤10%.

[0151] Example 9:

[0152] The only difference between this embodiment and embodiment 6 is that two adjacent polyamide films cross at 45 degrees.

[0153] The puncture strength of the sample in this embodiment is ≥170N, and the breakdown voltage is ≥64kV. After aging, the puncture strength decrease rate of the sample is ≤13%, and the breakdown voltage decrease rate is ≤12%.

[0154] It will be apparent to those skilled in the art that the present disclosure is not limited to the details of the exemplary embodiments described above and that the present disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of the present disclosure. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present disclosure is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present disclosure. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0155] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An adhesive tape comprising an ultra-high molecular weight polyethylene layer and polyamide film layers bonded to both sides thereof via adhesive layers, wherein at least two polyamide film layers are bonded to each side of the ultra-high molecular weight polyethylene layer. The thickness of the polyamide film layer is controlled to be 15-50 μm, the single layer breakdown voltage is ≥10 kV, and the puncture strength is greater than 12N; The ultra-high molecular weight polyethylene layer has a molecular weight MW of 1.5 million to 2.5 million, a film thickness of 70 to 150 μm, a single layer breakdown voltage of ≥20 kV, and a puncture strength greater than 80N.

2. The adhesive tape according to claim 1, wherein The raw materials of the polyamide film layer include, by wt%: Polyamide 66 resin: 90%-93%; Toughening agent: 1%-3%; First antioxidant: 0.5%-1%; Weathering agent: 1%-2%; Nano-montmorillonite residue.

3. The adhesive tape according to claim 1, wherein The raw materials of the ultra-high molecular weight polyethylene layer include, by weight: Ultra-high molecular weight polyethylene resin: 95%-97%; Second antioxidant: 0.5%-1%; Lubricant: 0.5%-1%; Nanoenhancer balance.

4. The adhesive tape according to claim 1, wherein The raw materials of the adhesive layer include, by weight: Main resin: 60%-70%; Curing agent: 2%-3%; Diluent: 5%-10%; Coupling agent: 1%-2%; Nano insulation filler allowance.

5. The adhesive tape according to claim 1, wherein The preparation of the ultra-high molecular weight polyethylene layer is as follows: Mixing: Add ultra-high molecular weight polyethylene resin, second antioxidant, lubricant, and nano-enhancer according to the formula ratio into a high-speed mixer and mix at 80-100°C for 15-20 minutes to evenly disperse the components; Melt extrusion: Add the mixed materials into the twin-screw extruder, control the extrusion temperature at 180-220℃, and the screw speed at 30-50r / min. The materials are melted and plasticized by the extruder and extruded into thick sheets; Stretching: The extruded thick sheet is biaxially stretched on a stretching machine. The longitudinal stretching temperature is 110-120℃ and the stretching ratio is 3-5 times; the transverse stretching temperature is 120-130℃ and the stretching ratio is 3-4 times; Cooling and shaping: The stretched film is cooled to room temperature via a cooling roller, and then rolled up after shaping to obtain an ultra-high molecular weight polyethylene layer with a thickness of 70-150 μm.

6. The adhesive tape according to claim 1, wherein The preparation of the polyamide film layer is as follows: Ingredients: Add polyamide 66 resin, toughening agent, first antioxidant, weathering agent and nano-montmorillonite into the mixing equipment according to the formula, and mix at 100-120℃ for 20-30 minutes; Melt extrusion: add the mixed material into a single screw extruder, the extrusion temperature is 230-260℃, the screw speed is 40-60r / min, and the film is extruded; Casting: The film blank is cooled by cooling casting rollers and formed into thick sheets; Stretching: The thick film is subjected to biaxial stretching, with the longitudinal stretching temperature at 60-70°C and the stretching ratio at 2.5-3.5 times; the transverse stretching temperature at 120-140°C and the stretching ratio at 2.5-3 times, so that the film thickness reaches 15-50μm; Heat setting: The stretched film is heat-set at 160-180°C for 10-20 seconds, then cooled and rolled up.

7. The method for preparing the adhesive tape according to any one of claims 1 to 6, comprising: Preparing slurry for coating the ultra-high molecular weight polyethylene layer, the polyamide film layer, and the adhesive layer; Adhesive coating: The bonding surfaces of the ultra-high molecular weight polyethylene layer and the polyamide film layer are pre-treated by plasma treatment, and the prepared slurry is evenly coated on both sides of the ultra-high molecular weight polyethylene layer and the bonding surface of the polyamide film layer through a doctor blade coater. The coating thickness is controlled at 50-100 μm. Lamination: First, laminate the first layer of polyamide film onto one side of the UHMWPE layer. Align the adhesive-coated UHMWPE layer with the polyamide film and perform roll-combination. Next, laminate the other polyamide film onto the same side, with the adjacent layers stacked crosswise. The hot pressing parameters are the same as for the first layer. Following the same method and parameters, laminate two layers of polyamide film onto the other side of the UHMWPE layer. After the lamination is completed, the tape is sent to the curing room for curing. The curing temperature is 130-140℃ and the curing time is 3-3.5h.

8. The method for preparing the adhesive tape according to claim 7, wherein: The cross-over stacking is as follows: the longitudinal stretching directions of two adjacent layers of polyamide films are perpendicular, cross-over at 60 degrees, or cross-over at 45 degrees.

9. A battery outer coating layer material comprising the adhesive tape according to any one of claims 1 to 6.

10. A battery comprising a battery body and the battery outer coating layer material according to claim 9 coated on the outer side of the battery body.