Metal-plastic composite film

Abstract

The invention relates to the field of battery packaging materials, in particular to a metal-plastic composite film which comprises an outer base material layer, a middle metal layer and an inner welding layer which are sequentially connected, and the outer base material layer comprises a polyester film layer and a polyamide resin film layer; the tensile strength of the outer base material layer is AET in the longitudinal direction and AQT in the transverse direction, and the thickness is Y; the strength of the polyester film layer is QM1 in the longitudinal direction and QT1 in the transverse direction, and the thickness of the polyester film layer is Y1; the strength of the polyamide resin film layer is QM2 in the longitudinal direction and QT2 in the transverse direction; the thickness is Y2; aET = [QM1 * (Y1 / Y) + QM2 * (Y2 / Y)] * Z, and AQT = [QT1 * (Y1 / Y) + QT2 * (Y2 / Y)] * Z. The strength and thickness selection of the polyester film layer and the polyamide resin film layer is guided by adjusting coefficients, so that the metal-plastic composite film is used as a battery packaging material, has good tensile strength, and can be ensured not to be easily damaged when a battery is vibrated and influenced by foreign matters, and the service life of the metal-plastic composite film is prolonged. And better durability and longer service life are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal-plastic film production, and specifically, to a metal-plastic composite film for battery packaging. Background Art

[0002] At present, lithium-ion batteries are mainly divided into three categories: square, cylindrical, and soft-pack. Among them, the outer casings of square and cylindrical batteries mainly use hard casings made of materials such as aluminum, iron, and their alloys, while the outer casing of soft-pack batteries uses a metal composite film formed by laminating a metal foil material and a resin material, which can greatly improve the problem of inflexible shape design of hard-shell batteries. Among them, the structure of the metal composite film from the outside to the inside is successively an outer substrate layer, an outer adhesive layer, an intermediate metal layer, an inner adhesive layer, and an inner welding resin layer.

[0003] During the use of power lithium-ion batteries, the use environment of the batteries is more severe than that of 3C batteries. Moreover, most power lithium-ion batteries are composed of multiple lithium battery monomers, and the safety management of the batteries during use is particularly important.

[0004] During the use of a power battery pack, the battery packaging material may be damaged due to reasons such as vibration and foreign objects. When the intermediate metal layer comes into contact with air and the internal materials of the battery core, the battery deteriorates rapidly. Even worse, due to a short circuit in the battery, a thermal runaway of the battery may occur, leading to serious accidents and personnel losses. Summary of the Invention

[0005] In order to overcome the problem that the battery packaging material may be damaged due to reasons such as vibration and foreign objects during the use of the battery in the above-mentioned prior art, the present invention provides a metal-plastic composite film, which improves the strength of the metal composite film to ensure the tolerance of the battery to vibration and foreign objects during use, and makes the battery packaging material not easily damaged.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a metal-plastic composite film, including an outer substrate layer, an intermediate metal layer, and an inner welding layer connected in sequence. The outer substrate layer includes a polyester film layer and a polyamide resin film layer; the tensile strength of the outer substrate layer is AET in the longitudinal direction and AQT in the transverse direction, and the thickness is Y; the strength of the polyester film layer is QM 1 , in the transverse direction is QT 1 , and the thickness is Y 1 ; the strength of the polyamide resin film layer is QM 2 , in the transverse direction is QT 2 ; the thickness is Y 2 ;

[0007] AET = [QM 1 *(Y 1 / Y)+QM 2 *(Y 2 / Y)]*Z

[0008] AQT = [QT 1 *(Y 1 / Y) + QT 2 *(Y 2 / Y)]*Z

[0009] In the formula, (Y 1 / Y) + (Y 2 / Y) = 1; Z is an adjustment coefficient, and the range is 0.7 - 1.1.

[0010] The adjustment coefficient can be used to guide the selection of the original film material to obtain a product with better corrosion resistance and strength. If it is lower than 0.7, the product strength will be too low, and it is easy for the battery packaging material to be damaged due to vibration and foreign objects during the use of the battery; if it is higher than 1.1, the forming limit will become lower, which is not conducive to processing and it is easy for the battery packaging material to be damaged due to vibration and foreign objects during the use of the battery.

[0011] The strength of the raw material and the data of the material thickness can be adjusted through the above formula to obtain the desired product. When the outer substrate layer of the metal-plastic composite film meets the above formula, the tensile strength and puncture resistance of the metal-plastic composite film are significantly improved, ensuring the tolerance of the battery to vibration and foreign objects during use and not being easily damaged.

[0012] Furthermore, the ratio of the thickness Y 1 to the thickness Y 2 is 1:(0.9 - 3).

[0013] Furthermore, under the condition of the same thickness as the outer substrate layer, the tensile strength of the polyester film layer is 220 - 240 MPa both longitudinally and transversely; the tensile strength of the polyamide resin film layer is 220 - 270 MPa longitudinally and 240 - 300 MPa transversely.

[0014] The tensile strength of the outer substrate layer is 200 - 230 MPa longitudinally and 210 - 240 MPa transversely. The thickness of the polyester film layer is Y 1 , the thickness of the polyamide resin film layer is Y 2 , the thickness of the combined outer substrate layer is Y, and the thickness of the outer substrate layer is the superposition of the thicknesses of the polyester film layer and the polyamide resin film layer. Due to the limitation of the respective thickness ratios during superposition, if the superposed outer substrate layer is compared with the polyester film layer and the polyamide resin film layer at the same thickness, the strength will appear lower.

[0015] Among them, the material of the polyester film layer can be selected from one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and copolyester. The material of the polyamide resin film layer can be selected from one of aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and the copolymer of nylon 6 and nylon 66. The polyester film layer and the polyamide resin film layer are connected by an adhesive. The material of the intermediate metal layer can be one of aluminum alloy, stainless steel, titanium steel, and nickel-plated iron sheet. The inner fusion layer can be a resin containing a polyolefin main chain such as polyolefin, such as polyethylene including low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene, homopolypropylene, and polypropylene. The thickness of the outer substrate layer is 4-50 μm, and the thicknesses of the polyester film layer and the polyamide resin film layer are 2-30 μm respectively. The outer substrate layer is connected to the intermediate metal layer through an outer adhesive layer, and the thickness of the outer adhesive layer is 1-10 μm. The thickness of the intermediate metal layer is 9-200 μm, preferably 30-100 μm, and more preferably 40-60 μm. The thickness of the inner heat-sealing layer is 20-120 μm, and more preferably 25-80 μm.

[0016] Furthermore, the material of the polyester film layer is polyethylene terephthalate, and the melting temperature of the polyethylene terephthalate is 248-258 °C; the material of the polyamide resin film layer is nylon, and the melting temperature of the nylon is 215-225 °C. When the polyester film layer and the polyamide resin film layer adopt the corresponding materials and within the corresponding melting temperature range, the outer substrate layer has relatively stable welding strength and maintains good performance at a relatively high temperature during use.

[0017] Furthermore, the polyamide resin film layer is connected to the intermediate metal layer. The polyester film layer is located on the outermost layer of the outer substrate layer, which can prevent the outer substrate layer from being easily discolored when the electrolyte adheres to the surface.

[0018] Furthermore, a first slip agent layer is coated on the outer surface of the outer substrate layer. The first slip agent layer can improve the formability of the metal-plastic composite film. The outer surface of the outer substrate layer refers to the side away from the intermediate metal layer.

[0019] Furthermore, the inner fusion layer includes an inner adhesive resin layer and a heat-sealing layer connected in sequence, and the inner adhesive resin layer is connected to the intermediate metal layer; the melting temperature of the heat-sealing layer is 150-160 °C. Within this melting temperature range of the heat-sealing layer, the fluidity during heating is more suitable, and it will not cause the thickness to become thinner during heat sealing and reduce the adhesion to the intermediate metal layer. At the same time, it has good crystallinity and will not become hard and brittle when heat-sealed, and there will be no problem of easily generating cracks and resulting in a lack of long-term stable sealing performance.

[0020] Further, the materials of the inner adhesive resin layer and the heat-sealing layer are polyolefins, such as polypropylene; the melt flow rate of the inner adhesive resin layer is 6-10 g / 10 min. When the melt flow rate of the resin is less than 2 g / 10 min, the fluidity of the resin during pressure heat-sealing is low, and it is difficult to obtain stable sealing performance. When the melt flow rate of the resin exceeds 15 g / 10 min, the fluidity of the resin during pressure heat-sealing becomes high, the thickness of the resin becomes thin, and the sealing performance also becomes unstable. In addition, through pressure, the resin at the pressed part inside the battery flows to the unpressed edge part, and cracks are generated due to external forces such as the expansion and contraction of the battery and bending processing. The electrolyte penetrates through the cracks into the intermediate metal layer, the insulation resistance of the internal heat-sealed resin layer decreases, leakage occurs, and the battery life becomes short. The melt flow rate is the data at a temperature of 230 degrees.

[0021] Further, a second slip agent layer is coated on the surface of the heat-sealing layer away from the intermediate metal layer. The second slip agent layer can improve the formability of the metal-plastic composite film.

[0022] Further, a coloring layer is provided on the outer surface of the outer substrate layer or between the outer substrate layer and the intermediate metal layer. By providing the coloring layer, the packaging material for lithium-ion batteries can be colored.

[0023] Further, the tensile strength of the intermediate metal layer is 90 MPa - 110 MPa.

[0024] Further, an anti-corrosion layer is provided on at least one side of the surface of the intermediate metal layer. The anti-corrosion layer prevents hydrogen fluoride generated by the reaction of the electrolyte with moisture from corroding the surface of the intermediate metal layer, prevents the separation of the intermediate metal layer from the inner welded layer, and at the same time maintains the uniformity of the surface of the intermediate metal layer, resulting in small changes in adhesiveness (wettability), and has the effect of preventing delamination between the intermediate metal layer and the inner welded layer. Considering the thermal sealing force between the intermediate metal layer and the inner welded layer, the thickness of the anti-corrosion layer is 1 nm - 3.0 μm.

[0025] Compared with the prior art, the beneficial effects of the present invention are: by adjusting the coefficients to guide the selection of the strength and thickness of the polyester film layer and the polyamide resin film layer, the metal-plastic composite film is used as a battery packaging material, which has good tensile strength, and can ensure that the metal-plastic composite film itself is not easily damaged due to reasons such as the battery being vibrated and affected by foreign objects, and has better durability and longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of a metal-plastic composite film of the present invention;

[0027] Figure 2 is a schematic diagram of another structure of a metal-plastic composite film of the present invention;

[0028] Figure 3 This is a schematic diagram of another structure of the metal-plastic composite film of the present invention. Description of the drawings:

[0030] 100 - Outer substrate layer; 110 - Polyester film layer; 120 - Polyamide resin film layer; 130 - First slip agent layer; 200 - Intermediate metal layer; 210 - Anti-corrosion layer; 300 - Inner fusion layer; 310 - Inner adhesive resin layer; 320 - Heat-sealing layer; 330 - Second slip agent layer; 400 - Outer adhesive layer; 500 - Coloring layer. Detailed implementation manners

[0031] The drawings are only for illustrative purposes and should not be construed as a limitation of this patent; for better illustration of this embodiment, some components in the drawings are omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationships described in the drawings are only for illustrative purposes and should not be construed as a limitation of this patent.

[0032] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationships in the drawings are only for illustrative purposes and should not be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] The technical solutions of the present invention will be further specifically described below through specific embodiments in conjunction with the drawings:

[0034] Embodiment 1

[0035] As Figure 1 shown in Embodiment 1 of a metal-plastic composite film, it includes an outer substrate layer 100, an intermediate metal layer 200, and an inner fusion layer 300 connected in sequence. The outer substrate layer 100 includes a polyester film layer 110 and a polyamide resin film layer 120. The tensile strength of the outer substrate layer is AET in the longitudinal direction and AQT in the transverse direction, and the thickness is Y; the strength of the polyester film layer 110 is QM 1 in the longitudinal direction and QT 1 in the transverse direction, and the thickness is Y 1 ; the strength of the polyamide resin film layer 120 is QM 2 in the longitudinal direction and QT2 ; with a thickness of Y 2 ;

[0036] AET = [QM 1 *(Y 1 / Y) + QM 2 *(Y 2 / Y)]*Z

[0037] AQT = [QT 1 *(Y 1 / Y) + QT 2 *(Y 2 / Y)]*Z

[0038] wherein, (Y 1 / Y) + (Y 2 / Y) = 1; Z is an adjustment coefficient, and the range is 0.7 - 1.1.

[0039] Specifically, when the thickness is the same as that of the outer substrate layer, the tensile strength of the polyester film layer 110 is 224 MPa in the longitudinal direction and 231 MPa in the transverse direction; the tensile strength of the polyamide resin film layer 120 is 230 MPa in the longitudinal direction and 247 MPa in the transverse direction.

[0040] The tensile strength of the outer substrate layer 100 is 213 MPa in the longitudinal direction and 225 MPa in the transverse direction. In this embodiment, Y = 40 μm, Y 1 = 15 μm, Y 2 = 25 μm. By substituting the above parameters into the formula, the obtained adjustment coefficient is within the range of 0.7 - 1.1.

[0041] The polyamide resin film layer 120 is connected to the intermediate metal layer 200. The polyester film layer 110 is located on the outermost layer of the outer substrate layer 100, which can prevent the outer substrate layer 100 from being discolored when the electrolyte adheres to its surface. The polyamide resin film layer 120 is connected to the intermediate metal layer 200.

[0042] Specifically, the surface of the outer substrate layer 100 away from the intermediate metal layer 200 is coated with a first slip agent layer 130. The first slip agent layer 130 can improve the formability of the metal-plastic composite film. The first slip agent layer 130 preferably uses an amide-based slip agent. Amide slip agents include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, hydroxymethyl amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides, etc. Taking saturated fatty acid amides as an example, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, etc. can be used. Taking unsaturated fatty acid amides as an example, oleic acid amide, erucic acid amide, etc. can be cited. Substituted amides include N-oleopalmitic acid amide, N-stearamide, N-stearamide, N-oleostearamide, and N-stearamide. In addition, hydroxymethyl amides include hydroxymethyl stearic acid amide, etc. Saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscaprylic acid amide, ethylene dilauric acid amide, ethylene bisstearic acid amide, ethylene bis-hydroxystearic acid amide, ethylene bisbehenic acid amide, and hexamethylene bisstearic acid hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, n,n'-distearyl adipic acid amide, n,n'-distearyl sebacic acid amide, etc. Unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, n,n'-dioleyl adipic acid amide, and n,n'-dioleyl sebacic acid amide. Fatty acid ester amides include stearamide ethyl stearate, etc. In addition, aromatic bisamides include m-phenylene dimethyl bisstearic acid amide, m-phenylene dimethyl bis-hydroxystearic acid amide, n,n'-distearyl isophthalic acid amide, etc. The coating amount of the slip agent is 0.3 - 30 mg / m 2 .

[0043] In this embodiment, the material of the polyester film layer 110 is polyethylene terephthalate glycol, with a thickness of 12 μm and a melting temperature of 250 °C. The material of the polyamide resin film layer 120 is nylon, with a thickness of 25 μm and a melting temperature of 220 °C. The polyester film layer 110 is connected to the polyamide resin film layer 120 through an adhesive, and the thickness of the adhesive coating can be 2 - 5 μm. The outer substrate layer 100 is connected to the intermediate metal layer 200 through an outer adhesive layer 400, and the thickness of the outer adhesive layer is 1 - 10 μm.

[0044] As Figure 2 shown, the inner fusion layer 300 includes an inner adhesive resin layer 310 and a heat-sealing layer 320 connected in sequence, and the inner adhesive resin layer 310 is connected to the intermediate metal layer 200.

[0045] The materials of the inner bonding resin layer 310 and the heat-sealing layer 320 are polyolefins, which are two different polypropylenes (PP). Among them, the melting temperature of the polypropylene forming the heat-sealing layer 320 is 150 °C. In this melting temperature range, the heat-sealing layer 320 has a more suitable fluidity during heating, which will not cause the thickness to become thinner during heat-sealing and reduce the adhesion to the intermediate metal layer 200. At the same time, it has good crystallinity and will not become hard and brittle when heat-sealed, and there will be no problem of cracks being easily generated and resulting in a lack of long-term stable sealing performance.

[0046] In this embodiment, the thickness of the inner fusion layer 300 is 80 μm, the melt flow rate of the inner bonding resin layer 310 is 3.3 g / 10 min, the melt flow rate of the heat-sealing layer 320 is 13.5 g / 10 min, and the thickness ratio of the inner bonding resin layer 310 to the heat-sealing layer 320 is 1:1. When the thickness of the heat-sealing layer 320 is less than 20 μm, the thickness cannot fully cover the deviations in machining dimensions such as heat fusion devices and condition deviations, so it is difficult to obtain a uniform heat-fused part and a stable sealing performance cannot be obtained. In addition, by pressing, the resin in the pressed part inside the battery flows to the non-pressed edge part, the thickness of the inner heat-fusion layer becomes thinner, and external forces such as the expansion, contraction, and bending processing of the battery are likely to cause cracks. The electrolyte penetrates through the cracks into the intermediate metal layer 200, the insulation resistance of the inner heat-sealing layer 320 decreases, and leakage occurs, shortening the battery life. When the thickness of the inner heat-sealing layer 320 exceeds 120 μm, the water vapor permeability increases, there is more moisture inside the battery, gas is generated by reacting with the electrolyte, and there is a risk of expansion, rupture, and liquid leakage, reducing the battery life. The excessive hydrogen fluoride corrodes and reduces the adhesion strength between the corrosion-prevented metal layer, the intermediate metal layer 200, and the inner heat-fusion layer, and problems such as electrolyte leakage are likely to occur. When the melt flow rate of the resin is less than 2 g / 10 min, the fluidity of the resin during pressure heat-sealing is low, and it is difficult to obtain a stable sealing performance. When the melt flow rate of the resin exceeds 15 g / 10 min, the fluidity of the resin during pressure heat-sealing becomes high, the thickness of the resin becomes thinner, and the sealing performance also becomes unstable. In addition, by pressing, the resin in the pressed part inside the battery flows to the non-pressed edge part, and cracks are generated due to external forces such as the expansion, contraction, and bending processing of the battery. The electrolyte penetrates through the cracks into the intermediate metal layer 200, the insulation resistance of the inner heat-fusion resin layer decreases, leakage occurs, and the battery life becomes shorter.

[0047] The surface of the heat-sealing layer 320 away from the intermediate metal 200 is coated with a second slip agent layer 330. In this embodiment, the second slip agent layer 330 is located between the inner bonding resin layer 310 and the heat-sealing layer 320, and the second slip agent layer 330 can improve the formability of the metal-plastic composite film. The material of the second slip agent layer 330 is the same as that of the first slip agent layer 130.

[0048] As Figure 3As shown, the intermediate metal layer 200 is made of aluminum foil. The intermediate metal layer 200 and the outer substrate layer 100 are connected through the outer adhesive layer 400. The tensile strength of the intermediate metal layer 200 is 100 MPa, and the thickness is 60 μm. Anti-corrosion layers 210 are provided on the surfaces of the intermediate metal layer 200. The anti-corrosion layers 210 prevent hydrogen fluoride generated by the reaction of the electrolyte with moisture from corroding the surface of the intermediate metal layer 200, prevent the separation of the intermediate metal layer 200 from the inner bonding layer 300, and at the same time maintain the uniformity of the surface of the intermediate metal layer 200, resulting in small changes in adhesiveness (wettability), and having the effect of preventing delamination between the intermediate metal layer 200 and the inner bonding layer 300. Considering the thermal bonding force between the intermediate metal layer 200 and the inner bonding layer 300, the thickness of the anti-corrosion layer 210 is 1 nm. The anti-corrosion layer 210 is formed by coating an anti-corrosion liquid on the intermediate metal layer 200 and performing heat treatment at a high temperature of 130 - 200 °C for 0.5 - 5 min.

[0049] In addition, a coloring layer 500 is provided on the outer surface of the outer substrate layer 100 or between the outer substrate layer 100 and the intermediate metal layer 200. In this embodiment, the coloring layer 500 is provided between the outer substrate layer 100 and the intermediate metal layer 200. Specifically, the coloring layer 500 is located between the outer substrate layer 100 and the outer adhesive layer 400. By providing the coloring layer 500, the packaging material for lithium-ion batteries can be colored.

[0050] The working principle or working process of this embodiment: The adjustment coefficient can be used to guide the selection of the original film material to obtain a product with good corrosion resistance and strength. If it is lower than 0.7, the strength of the product will be too low, and it is easy for the battery packaging material to be damaged due to vibration and foreign objects during battery use; if it is higher than 1.1, the forming limit will be low, which is not conducive to processing and it is easy for the battery packaging material to be damaged due to vibration and foreign objects during battery use.

[0051] The raw material strength and material thickness data can be adjusted through the above formula to obtain the desired product. When the outer substrate layer of the metal-plastic composite film meets the above formula, the tensile strength and puncture resistance of the metal-plastic composite film are significantly improved, ensuring the tolerance of the battery to vibration and foreign objects during use and not being easily damaged.

[0052] The beneficial effects of this embodiment: By using the adjustment coefficient to guide the selection of the strength and thickness of the polyester film layer and the polyamide resin film layer, the metal-plastic composite film used as a battery packaging material has good tensile strength, and can ensure that the metal-plastic composite film itself is not easily damaged under the influence of vibration and foreign objects during battery use, and has better durability and a longer service life.

[0053] In addition, an intermediate resin layer can also be provided between the inner bonding resin layer 310 and the heat-sealing layer 320.

[0054] Example 2

[0055] As Figure 2 shown in Figure 2 is an Example 2 of a metal-plastic composite film. Based on Example 1, the difference from Example 1 is that the tensile strength of the polyester film layer 110 is 224 MPa in the longitudinal direction and 231 MPa in the transverse direction; the tensile strength of the polyamide resin film layer 120 is 230 MPa in the longitudinal direction and 247 MPa in the transverse direction. The polyester film layer 110 and the polyamide layer 120 are bonded by an adhesive; the tensile strength of the outer substrate layer 100 is 213 MPa in the longitudinal direction and 225 MPa in the transverse direction. The melt flow rate of the inner adhesive resin layer 310 is 7.9 g / 10 min, and the melt flow rate of the heat-sealing layer 320 is 7.9 g / 10 min. The tensile strength of the intermediate metal layer 200 is 100 MPa.

[0056] The remaining features and working principles of this example are the same as those of any of the above examples.

[0057] Example 3

[0058] An Example 3 of a metal-plastic composite film. Based on Example 1, the difference from Example 1 is that the tensile strength of the polyester film layer 110 is 224 MPa in the longitudinal direction and 231 MPa in the transverse direction; the tensile strength of the polyamide resin film layer 120 is 230 MPa in the longitudinal direction and 247 MPa in the transverse direction. The polyester film layer 110 and the polyamide layer 120 are bonded by an adhesive; the tensile strength of the outer substrate layer 100 is 213 MPa in the longitudinal direction and 225 MPa in the transverse direction. The melt flow rate of the inner adhesive resin layer 310 is 7.9 g / 10 min, and the melt flow rate of the heat-sealing layer 320 is 18.5 g / 10 min. The tensile strength of the intermediate metal layer 200 is 100 MPa.

[0059] The remaining features and working principles of this example are the same as those of any of the above examples.

[0060] Example 4

[0061] An Example 4 of a metal-plastic composite film. Based on Example 1, the difference from Example 1 is that the tensile strength of the polyester film layer 110 is 224 MPa in the longitudinal direction and 231 MPa in the transverse direction; the tensile strength of the polyamide resin film layer 120 is 225 MPa in the longitudinal direction and 285 MPa in the transverse direction. The tensile strength of the outer substrate layer 100 is 198 MPa in the longitudinal direction and 248 MPa in the transverse direction. The melt flow rate of the inner adhesive resin layer 310 is 7.9 g / 10 min, and the melt flow rate of the heat-sealing layer 320 is 13.5 g / 10 min. The tensile strength of the intermediate metal layer 200 is 88 MPa.

[0062] Example 5

[0063] Example 5 of a metal-plastic composite film. Based on Example 1, the difference from Example 1 is that the tensile strength of the polyester film layer 110 is 224 MPa longitudinally and 231 MPa transversely; the tensile strength of the polyamide resin film layer 120 is 230 MPa longitudinally and 247 MPa transversely. The tensile strength of the outer substrate layer 100 is 213 MPa longitudinally and 225 MPa transversely. The melt flow rate of the inner adhesive resin layer 310 is 7.9 g / 10 min, and the melt flow rate of the heat-sealing layer 320 is 13.5 g / 10 min. The tensile strength of the intermediate metal layer 200 is 100 MPa.

[0064] The remaining features and working principles of this example are the same as those of any of the above examples.

[0065] The test results of the tensile strength, heat-sealing strength, peel strength, and forming limit of the metal-plastic composite films corresponding to the above examples are shown in the following table. Three comparative examples are also provided in the table. In the table, MD represents the longitudinal direction and TD represents the transverse direction.

[0066]

[0067]

[0068] Among them, all the test methods used are national standards: Tensile strength test: Conducted in accordance with the provisions of GB / T 1040.3-2006, and the specimen type is Type 2 specimen. The test uses a long strip with a length ≥ 150 mm and a width of (15 ± 0.1) mm, a gauge length of 50 mm, and a test speed of 50 mm / min.

[0069] Peel strength test: Conducted in accordance with the provisions of GB / T 8808-1988, using a long strip with a specimen width of 15 mm, an inner layer peel speed of 50 mm / min, and an outer layer speed of 10 mm / min.

[0070] Heat-sealing strength test: Cut a long strip with a width of 15 mm and conduct the test in accordance with the provisions of QB / T 2358-1998, with a test speed of 5 mm / min.

[0071] The forming limit test is a known method, including but not limited to:

[0072] Using a stamping machine with adjustable pressure formability manufactured by Shenzhen Hongbao Machinery, the mold is set as follows: a rectangular parallelepiped shape (with rounded corners) with depths of 98 mm (TD) * 57 mm (MD); the clearance between the male and female molds is 0.3 mm, the corner R = 1.5 mm, the edge R = 1.0 mm, the surface roughness Ra = 0.8, the forming surface pressure is 5 Mpa, the core mold r = 1.5 mm, the mold r = 2 mm, and the sample size is 58 mm * 97 mm.

[0073] The test starts from a depth of 5 mm. In the range up to a depth of 11 mm, the forming depth is increased by 0.25 mm each time. After forming at each forming depth, check whether pinholes or cracks occur at the four corners of the formed product. Furthermore, confirm that no pinholes or cracks occur at each forming depth, and confirm the ultimate forming height.

[0074] The formability is evaluated based on the following judgment criteria. It should be noted that whether pinholes or cracks occur is investigated using the light transmission method in a dark room.

[0075] For example, in Example 5, when testing up to a forming depth of 10.5 mm, no damage or pinholes appeared at the four corners, so the forming depth was 10.5 mm.

[0076] According to the content of the above table, among Examples 1 to 5, Example 5 is the best choice. It can be seen from Comparative Example 1 that the tensile strength of the polyamide resin film layer in the transverse direction exceeds the scope of this application. The product parameters of the finally obtained metal-plastic composite film are worse than those of Example 4 or other examples of this application, and are lower than the corresponding tensile strength range of this application. The parameters of the finally obtained metal-plastic composite film are also not as good as those of the examples of this application.

[0077] Obviously, the above-mentioned embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A metal-plastic composite film, comprising an outer substrate layer (100), an intermediate metal layer (200) and an inner welding layer (300) connected in sequence, characterized in that: The outer substrate layer (100) comprises a polyester film layer (110) and a polyamide resin film layer (120); the tensile strength of the outer substrate layer in the longitudinal direction is AET, in the transverse direction is AQT, and the thickness is Y; the strength of the polyester film layer (110) in the longitudinal direction is QM1, in the transverse direction is QT1, and the thickness is Y1; the strength of the polyamide resin film layer (120) in the longitudinal direction is QM2, in the transverse direction is QT2, and the thickness is Y2; AET=[QM1*(Y1 / Y)+QM2*(Y2 / Y)]*Z AQT=[QT1*(Y1 / Y)+QT2*(Y2 / Y)]*Z Wherein, (Y1 / Y)+(Y2 / Y)=1; Z is the adjustment coefficient, ranging from 0.7 to 1.

1.

2. A metal-plastic composite film according to claim 1, characterized in that: The ratio of thickness Y1 to thickness Y2 is 1:(0.9-3).

3. The metal-plastic composite film according to claim 1, characterized in that: When the thickness is the same as that of the outer substrate layer, the tensile strength of the polyester film layer (110) is 220-240 MPa in both the longitudinal and transverse directions; the tensile strength of the polyamide resin film layer (120) is 220-270 MPa in the longitudinal direction and 240-300 MPa in the transverse direction.

4. A metal-plastic composite film according to claim 3, characterized in that: The tensile strength of the outer base material layer is 200 to 230 MPa in the longitudinal direction and 210 to 240 MPa in the transverse direction.

5. The metal-plastic composite film according to claim 1, characterized in that: The polyamide resin film layer (120) is connected to the intermediate metal layer (200).

6. The metal-plastic composite film according to claim 1, characterized in that: The outer surface of the outer substrate layer (100) is coated with a first lubricant layer (130).

7. The metal-plastic composite film according to claim 1, characterized in that: The inner welding layer (300) comprises an inner bonding resin layer (310) and a heat sealing layer (320) which are connected in sequence, and the inner bonding resin layer (310) is connected to the intermediate metal layer (200); the melting temperature of the heat sealing layer (320) is 150-160°C.

8. The metal-plastic composite film according to claim 8, characterized in that: The materials of the inner adhesive resin layer (310) and the heat sealing layer (320) are polyolefin; the melt flow rate of the inner adhesive resin layer (310) is 6 to 10 g / 10 min.

9. The metal-plastic composite film according to claim 1, characterized in that: At least one surface of the heat sealing layer (320) is coated with a second lubricant layer (330). If the second lubricant layer (330) is located on the surface of the heat sealing layer (320) close to the inner adhesive resin layer (310), the second lubricant layer (330) is connected to the inner adhesive resin layer (310).

10. A metal-plastic composite film according to any one of claims 1 to 9, characterized in that: The outer substrate layer (100) and the intermediate metal layer (200) are connected via an outer adhesive layer (400); a coloring layer (500) is provided on the outer surface of the outer substrate layer (100) or between the outer substrate layer (100) and the intermediate metal layer (200).

11. The metal-plastic composite film according to claim 10, characterized in that: The tensile strength of the intermediate metal layer (200) is between 90 MPa and 110 MPa; and an anti-corrosion layer (210) is provided on at least one side of the surface of the intermediate metal layer (200).

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