Ultrathin aluminum-plastic film, preparation method thereof and lithium battery

Abstract

The invention belongs to the technical field of aluminum plastic films, and particularly relates to an ultrathin aluminum plastic film, a preparation method thereof and a lithium battery, the ultrathin aluminum plastic film sequentially comprises a nylon layer, an aluminum foil layer and a polypropylene layer from inside to outside; wherein the aluminum foil layer is formed by smelting the following materials in percentage by mass: 0.02 to 0.063 percent of Sb, 0.016 to 0.126 percent of Si, 1.0 to 1.5 percent of Fe, 0.006 to 0.011 percent of Cu, 0.005 to 0.01 percent of Mn, 0.006 to 0.009 percent of Zn, 0.004 to 0.008 percent of Ti, 0.004 to 0.008 percent of B, 0.0005 to 0.002 percent of Mg and the balance of Al; the polypropylene layer is a three-layer co-extrusion casting polypropylene layer and sequentially comprises a corona layer, a supporting layer and a heat sealing layer from outside to inside; the components of the supporting layer comprise silicon dioxide doped POE resin and hyperbranched polyamide; the silicon dioxide doped POE resin and hyperbranched polyamide are added into the supporting layer of the three-layer co-extrusion casting polypropylene layer, and the modified aluminum foil layer is matched, so that the flexibility of the aluminum-plastic film is improved, and the aluminum-plastic film has the effects of lightness, thinness and deep impact resistance at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum-plastic films, and in particular relates to an ultra-thin aluminum-plastic film and a preparation method thereof, and a lithium battery. Background Art

[0002] After long-term accumulation and development, lithium-ion batteries have been widely used in fields such as mobile electronic devices and new energy vehicles due to their comprehensive advantages such as high energy density, many cycles, small size and light weight, and green environmental protection.

[0003] However, as consumer electronic products such as mobile phones and tablets develop towards lighter and thinner directions, batteries are required to have better battery life and thinner thickness to bring consumers a better experience. The weight of the battery accounts for more than 1 / 3 of the weight of the product, and there is an urgent need to address the requirements for lighter and thinner batteries.

[0004] Most existing aluminum-plastic films are 113 microns thick, which cannot meet the market demand for lighter and higher-end applications, and it is difficult to achieve a breakthrough in the thickness of the final product.

[0005] Therefore, how to reduce the thickness while meeting the requirements of the punching performance of the aluminum-plastic film foundation is a technical problem that needs to be solved urgently in this field.

[0006] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of the prior art. Summary of the invention

[0007] The embodiments of the present disclosure at least provide an ultra-thin aluminum-plastic film and a preparation method thereof, and a lithium battery.

[0008] In the first aspect, an embodiment of the present disclosure provides an ultra-thin aluminum-plastic film, which includes, from the inside to the outside, a nylon layer, an aluminum foil layer and a polypropylene layer; wherein the aluminum foil layer is formed by melting materials including the following mass percentages: Sb 0.063%, Si 0.016-0.126%, Fe 1.5%, Cu 0.011%, Mn 0.005%, Zn 0.006%, Ti 0.004%, B 0.004%, Mg 0.0005%, and the balance is Al; the polypropylene layer is a three-layer co-extruded cast polypropylene layer, which includes, from the outside to the inside, a corona layer, a support layer and a heat-sealing layer; the components of the support layer include silica-doped POE resin and hyperbranched polyamide.

[0009] In an optional embodiment, the mass ratio of Sb to Si in the aluminum foil layer is 0.5-4.

[0010] In an optional embodiment, the thickness of the polypropylene layer is 15-25 μm; wherein the thickness ratio of the corona layer, the support layer and the heat-sealing layer is (0.8-1.2):(1.8-2.2):(0.8-1.2).

[0011] In an optional embodiment, the corona layer is composed of the following components in parts by weight: 50-60 parts of maleic anhydride grafted polypropylene, 35-50 parts of homopolypropylene resin, and 1-5 parts of lubricating masterbatch.

[0012] In an optional embodiment, the support layer is composed of the following components in parts by weight: 85-90 parts of silica-doped POE resin, 5-10 parts of hyperbranched polyamide, and 1-5 parts of lubricating masterbatch.

[0013] In an optional embodiment, the heat-sealing layer is composed of the following components in parts by weight: 95-99 parts of terpolymer polypropylene and 1-5 parts of lubricating masterbatch.

[0014] In an optional implementation, the ultra-thin aluminum-plastic film has a thickness of 55-75 μm.

[0015] In an optional embodiment, the thickness of the nylon layer is 15-20 μm; the thickness of the aluminum foil layer is 25-30 μm.

[0016] In a second aspect, the embodiment of the present disclosure also provides a method for preparing an ultra-thin aluminum-plastic film as described above, comprising the following steps: step S1, melting and rolling aluminum foil, adding each element into an aluminum melting furnace according to a mass ratio to obtain aluminum foil; step S2, coating the matte surface and the bright surface of the aluminum foil layer with a degreasing passivation liquid containing trivalent chromium, and obtaining an aluminum foil layer after oven drying; step S3, adding the components of the corona layer, the support layer and the heat sealing layer into an extruder according to a ratio, hot-melt extrusion and cooling to form, and obtaining a three-layer co-extruded cast polypropylene layer; step S4, thermally compounding the bright surface of the aluminum foil layer with the corona layer of the three-layer co-extruded cast polypropylene layer under an environment of 140-240°C; step S5, coating the matte surface of the aluminum foil layer with polyurethane glue and compounding it with the nylon layer after oven drying to obtain an aluminum-plastic film semi-finished product; step S6, smoothing the aluminum-plastic film semi-finished product to obtain an ultra-thin aluminum-plastic film.

[0017] In a third aspect, the embodiments of the present disclosure further provide a lithium battery, which uses the ultra-thin aluminum-plastic film as described above, wherein the thickness of the ultra-thin aluminum-plastic film is 55-75 μm.

[0018] The beneficial effects of the present invention are that the ultra-thin aluminum-plastic film, its preparation method, and lithium battery add rare earth elements Sb and Si during the aluminum foil smelting process, so that the aluminum foil substrate has good mechanical properties and ductility, and at the same time, silicon dioxide-doped POE resin and hyperbranched polyamide are added to the support layer of the three-layer co-extruded cast polypropylene layer to increase the flexibility of the aluminum-plastic film, so that the aluminum-plastic film has both the effects of lightness and thickness and deep impact resistance.

[0019] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic structural diagram of an ultra-thin aluminum-plastic film provided in an embodiment of the present disclosure.

[0023] In the figure:

[0024] 1. Nylon layer; 2. Aluminum foil layer; 31. Corona layer; 32. Support layer; 33. Heat sealing layer. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] As used herein, the phrases "in one embodiment," "according to one embodiment," "in some embodiments," and the like generally refer to the fact that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure. Therefore, a particular feature, structure, or characteristic may be included in more than one embodiment of the present disclosure, so that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example," "exemplary," and the like are used to "serve as an example, instance, or illustration." Any implementation, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. On the contrary, the use of the terms "example," "exemplary," and the like is intended to present concepts in a concrete manner.

[0027] Herein, example embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as "at least one of..." modify the entire list of elements when following a list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0028] The terms used herein are only used to describe specific exemplary configurations and are not intended to be limited. As used herein, the singular articles "one", "an" and "the" may also be intended to include plural forms, unless it is clearly indicated above that this is not the case. The terms "comprise", "include" and "have" are inclusive, and therefore specify the presence of features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or combinations thereof. The method steps, processes and operations described herein should not be interpreted as necessarily requiring them to be performed in the specific order discussed or shown, unless specifically identified as an execution order. Additional or alternative steps may be adopted.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0031] See also Figure 1The embodiment of the present disclosure provides an ultra-thin aluminum-plastic film, which includes a nylon layer, an aluminum foil layer and a polypropylene layer from the inside to the outside; wherein the aluminum foil layer is formed by melting materials including the following mass percentages: Sb 0.063%, Si 0.016-0.126%, Fe 1.5%, Cu 0.011%, Mn 0.005%, Zn 0.006%, Ti 0.004%, B 0.004%, Mg 0.0005%, and the balance is Al; the polypropylene layer is a three-layer co-extruded cast polypropylene layer, which includes a corona layer, a support layer and a heat-sealing layer from the outside to the inside; the components of the support layer include silica-doped POE resin and hyperbranched polyamide.

[0032] Specifically, Sb (antimony): Adding Sb to aluminum-plastic film can improve the ductility and corrosion resistance of the material. The Sb element can refine the grains and make the Al3Fe intermetallic compound finer, thereby enhancing the refining effect of the Fe element. In addition, Sb can also increase the self-corrosion potential of aluminum alloys, further improving corrosion resistance.

[0033] Specifically, Si (silicon): The role of Si in aluminum plastic film is mainly to lower the melting point and improve fluidity. Although the corrosion potential of Si is higher than that of the substrate, its effect on corrosion performance is minimal. In addition, Si is effective in fatigue properties.

[0034] Specifically, Fe (iron): The addition of Fe can enhance the strength and corrosion resistance of aluminum alloy, but excessive amount may lead to adverse effects. In the present aluminum-plastic film, the content of Fe must be controlled within 1%-1.5%, and the performance of the aluminum-plastic film can be improved together with the refinement of Sb.

[0035] Specifically, Cu (copper): the presence of Cu will reduce the corrosion resistance, but the Cu dissolved in the matrix is ​​beneficial to improving the corrosion resistance and impact toughness of the alloy. At the same time, the addition of Cu can also improve the hot working plasticity. Therefore, an appropriate amount of Cu can play a positive effect in the present aluminum-plastic film.

[0036] Specifically, Mn (manganese): Mn is used to improve the ultimate yield strength and fatigue toughness without affecting ductility. The addition of Mn can improve the strength, corrosion resistance and impact toughness of the alloy, but excessive Mn will reduce the strengthening effect, so it needs to be controlled within 0.005-0.01%.

[0037] Specifically, Zn (zinc): The addition of Zn can significantly improve the stress corrosion cracking resistance of aluminum alloys and can slow down the corrosion rate of materials at appropriate concentrations. However, excessive use of Zn may cause zinc powder to form on the surface, affecting material properties.

[0038] Specifically, Ti (titanium): Ti is used to refine grains, thereby improving the uniformity and extrudability of the material. The addition of Ti can significantly improve the toughness of the aluminum-plastic film.

[0039] Specifically, B (boron): the B element is used to refine the grains, thereby improving the uniformity and extrudability of the material.

[0040] Specifically, Mg (magnesium): Mg improves the strength of the aluminum-plastic film through solid solution strengthening and precipitation strengthening without affecting the corrosion resistance. The addition of Mg has a significant effect, especially in Al-Si alloys.

[0041] In some embodiments, specifically, the mass ratio of Sb to Si in the aluminum foil layer is 0.5-4.

[0042] In some embodiments, specifically, the thickness of the polypropylene layer is 15-25 μm; wherein the thickness ratio of the corona layer, the support layer and the heat-sealing layer is (0.8-1.2):(1.8-2.2):(0.8-1.2).

[0043] In some embodiments, specifically, the corona layer is composed of the following components in parts by weight: 50-60 parts of maleic anhydride grafted polypropylene, 35-50 parts of homopolypropylene resin, and 1-5 parts of lubricating masterbatch.

[0044] In some embodiments, specifically, the support layer is composed of the following components in parts by weight: 85-90 parts of silica-doped POE resin, 5-10 parts of hyperbranched polyamide, and 1-5 parts of slip masterbatch.

[0045] In some embodiments, specifically, the heat-sealing layer is composed of the following components in parts by weight: 95-99 parts of terpolymer polypropylene and 1-5 parts of lubricating masterbatch.

[0046] Specifically, silica-doped POE resin is a polyolefin elastomer with inorganic silica added to it, replacing the polypropylene component and improving the problem of poor low-temperature toughness of polypropylene. POE resin has excellent toughness. The doping of inorganic silica makes the material highly tough while increasing its hardness and strength.

[0047] Specifically, the addition of hyperbranched polyamide increases the flexibility of the POE resin group, reduces the intermolecular forces, improves processing adaptability, and makes the finished product easier to extend during punching and forming.

[0048] In some embodiments, specifically, the thickness of the ultra-thin aluminum-plastic film is 55-75 μm.

[0049] In some embodiments, specifically, the thickness of the nylon layer is 15-20 μm; the thickness of the aluminum foil layer is 25-30 μm.

[0050] The disclosed embodiment also provides a method for preparing the ultra-thin aluminum-plastic film as described above, comprising the following steps: step S1, melting and rolling aluminum foil, adding various elements into an aluminum melting furnace according to a mass ratio to obtain aluminum foil; step S2, coating the matte surface and the bright surface of the aluminum foil layer with a degreasing passivation liquid containing trivalent chromium, and obtaining an aluminum foil layer after oven drying; step S3, adding the components of the corona layer, the support layer and the heat sealing layer into an extruder according to a ratio, hot-melt extrusion and cooling to form, and obtaining a three-layer co-extruded cast polypropylene layer; step S4, thermally compounding the bright surface of the aluminum foil layer with the corona layer of the three-layer co-extruded cast polypropylene layer under an environment of 140-240° C.; step S5, coating the matte surface of the aluminum foil layer with polyurethane glue, and compounding it with the nylon layer after oven drying to obtain an aluminum-plastic film semi-finished product; step S6, smoothing the aluminum-plastic film semi-finished product to obtain an ultra-thin aluminum-plastic film.

[0051] The disclosed embodiment also provides a lithium battery, which uses the ultra-thin aluminum-plastic film as described above, and the thickness of the ultra-thin aluminum-plastic film is 55-75 μm.

[0052] The performance of the ultra-thin aluminum-plastic film provided by the present invention is tested according to the following method:

[0053] (1) Thickness

[0054] The measurement was performed using a Japanese Mitutoyo micrometer using the contact method.

[0055] (2) Deep drawing performance

[0056] The punching performance of ultra-thin aluminum-plastic film was measured using a semi-automatic punching machine mold model 6080. Measurement method: Set the punching depths to 6, 5.5, 5, and 4.5 mm, punch the aluminum-plastic film, and then observe whether the aluminum-plastic film is damaged or has pinholes.

[0057] (3) Heat sealability

[0058] The semi-automatic heat sealer model: TP-701B, Shimadzu universal tester model: AGX, measurement method: align the inner surfaces of two 100mmx100mm ultra-thin aluminum-plastic film samples, heat seal them with the upper / lower heat sealing head at 190 / 190℃ for 5s, let it stand, cut them into 15mm wide strips vertically along the heat sealing line, and test the peeling force on the universal tester.

[0059] Example 1

[0060] The invention provides an ultra-thin aluminum-plastic film and a preparation method thereof. The ultra-thin aluminum-plastic film comprises a nylon layer, an aluminum foil layer and a three-layer co-extruded cast polypropylene layer.

[0061] 0.063% Sb, 0.016% Si, 1.5% Fe, 0.011% Cu, 0.005% Mn, 0.0006% Zn, 0.004% Ti, 0.004% B, 0.0005% Mg and the balance Al are added to an aluminum smelting furnace, and after smelting, an ingot is formed by a casting machine, the pouring portion of the ingot is cut off, the upper and lower large surfaces of the ingot are milled, and the ingot is annealed at high temperature. After being taken out of the furnace, it is naturally cooled, and after preheating, it is rolled in multiple passes on a hot rolling mill, and after cold rough rolling and cold finishing rolling, three foil rolling processes of rough rolling, intermediate rolling and finishing rolling are performed, and after slitting and annealing, a high-strength, high-elongation, deep-drawing-resistant aluminum foil with a thickness of 25 μm is obtained;

[0062] The matte and bright surfaces of the aluminum foil were coated with a degreasing passivation liquid containing trivalent chromium, the ratio of the passivation liquid was acid-resistant agent: ethanol: water = 2:2:1, and dried in a 90°C suspension oven for 2 minutes;

[0063] 50 parts by weight of maleic anhydride grafted polypropylene, 49 parts by weight of homopolypropylene resin, and 1 part by weight of lubricating masterbatch were mixed and added to extruder A, 85 parts by weight of silica-doped POE resin Exxon 6502, 10 parts by weight of hyperbranched polyamide Kramar 114615, and 5 parts by weight of lubricating masterbatch were mixed and added to extruder B, 95 parts by weight of ternary copolymer polypropylene and 5 parts by weight of lubricating masterbatch were mixed and added to extruder C, and hot-melt extrusion was performed at 230° C. and cooling was performed to form a three-layer co-extruded cast polypropylene layer with a thickness of 12 μm;

[0064] The bright surface of the aluminum foil is heat-compounded with a three-layer co-extruded cast polypropylene layer at 140°C;

[0065] The aluminum foil matte coating is made of polyurethane glue A (model: Weikai VN930), with a ratio of main agent: curing agent: solvent = 5:1:3. After being dried in a suspension oven, a nylon layer with a thickness of 15 μm is formed, and the thickness of the adhesive layer is 3 μm.

[0066] The obtained aluminum-plastic film semi-finished product is smoothed to obtain an ultra-thin aluminum-plastic film with a total thickness of 55 μm.

[0067] Example 2

[0068] As the ultra-thin aluminum-plastic film provided in Example 1.

[0069] 0.063% Sb, 0.032% Si, 1.5% Fe, 0.011% Cu, 0.005% Mn, 0.0006% Zn, 0.004% Ti, 0.004% B, 0.0005% Mg and the balance Al are added to an aluminum smelting furnace, and after smelting, an ingot is formed by a casting machine, the pouring portion of the ingot is cut off, the upper and lower large surfaces of the ingot are milled, and the ingot is annealed at high temperature. After being taken out of the furnace, it is naturally cooled, and after preheating, it is rolled in multiple passes on a hot rolling mill, and then subjected to cold rough rolling and cold finishing rolling processes, and then three foil rolling processes of rough rolling, intermediate rolling and finishing rolling are performed, and after slitting and annealing, a high-strength, high-elongation, deep-drawing-resistant aluminum foil with a thickness of 30 μm is obtained;

[0070] The matte and bright surfaces of the aluminum foil were coated with a degreasing passivation liquid containing trivalent chromium, the ratio of the passivation liquid was acid-resistant agent: ethanol: water = 2:2:1, and dried in a suspension oven at 110°C for 2 minutes;

[0071] 55 parts by weight of maleic anhydride grafted polypropylene, 44 parts by weight of homopolypropylene resin, and 1 part by weight of lubricating masterbatch were mixed and added to extruder A, 90 parts by weight of silica-doped POE resin Exxon 6502, 5 parts by weight of hyperbranched polyamide Kramar 114615, and 5 parts by weight of lubricating masterbatch were mixed and added to extruder B, 97 parts by weight of ternary copolymer polypropylene and 3 parts by weight of lubricating masterbatch were mixed and added to extruder C, and hot-melt extrusion was performed at 240° C. and cooled to form a three-layer co-extruded cast polypropylene layer with a thickness of 17 μm;

[0072] The bright surface of the aluminum foil is thermally compounded with three layers of co-extruded cast polypropylene at 200°C;

[0073] The aluminum foil matte coating is made of polyurethane glue A (model: Weikai VN930), with a ratio of main agent: curing agent: solvent = 5:1:3. After being dried in a suspension oven, a nylon layer with a thickness of 15 μm is formed, and the thickness of the adhesive layer is 3 μm.

[0074] The obtained aluminum-plastic film semi-finished product is smoothed to obtain an ultra-thin aluminum-plastic film with a total thickness of 65 μm.

[0075] Example 3

[0076] 0.063% Sb, 0.126% Si, 1.5% Fe, 0.011% Cu, 0.005% Mn, 0.0006% Zn, 0.004% Ti, 0.004% B, 0.0005% Mg and the balance Al are added to an aluminum smelting furnace, and after smelting, an ingot is formed by a casting machine, the pouring portion of the ingot is cut off, the upper and lower large surfaces of the ingot are milled, and the ingot is annealed at high temperature. After being taken out of the furnace, it is naturally cooled, and after preheating, it is rolled in multiple passes on a hot rolling mill, and after cold rough rolling and cold finishing rolling, three foil rolling processes of rough rolling, intermediate rolling and finishing rolling are performed, and after slitting and annealing, a high-strength, high-elongation, deep-drawing-resistant aluminum foil with a thickness of 25 μm is obtained;

[0077] The matte and bright surfaces of the aluminum foil were coated with a degreasing passivation liquid containing trivalent chromium, the ratio of the passivation liquid was acid-resistant agent: ethanol: water = 2:2:1, and dried in a 120°C suspension oven for 2 minutes;

[0078] 60 parts by weight of maleic anhydride grafted polypropylene, 35 parts by weight of homopolypropylene resin, and 5 parts by weight of lubricating masterbatch were mixed and added to extruder A, 90 parts by weight of silica-doped POE resin Exxon 6502, 9 parts by weight of hyperbranched polyamide Kramar 114615, and 1 part by weight of lubricating masterbatch were mixed and added to extruder B, 99 parts by weight of ternary copolymer polypropylene and 1 part by weight of lubricating masterbatch were mixed and added to extruder C, and hot-melt extrusion was performed at 250° C. and cooled to form a three-layer co-extruded cast polypropylene layer with a thickness of 22 μm;

[0079] The bright surface of the aluminum foil is thermally compounded with a three-layer co-extruded cast polypropylene layer at 240°C;

[0080] The aluminum foil matte coating is made of polyurethane glue A (model: Weikai VN930), with a ratio of main agent: curing agent: solvent = 5:1:3. After being dried in a suspension oven, a nylon layer with a thickness of 20 μm is formed, and the thickness of the adhesive layer is 3 μm.

[0081] The obtained aluminum-plastic film semi-finished product is smoothed to obtain an ultra-thin aluminum-plastic film with a total thickness of 75 μm.

[0082] Comparative Example 1

[0083] 1.5% Fe, 0.011% Cu, 0.005% Mn, 0.0006% Zn, 0.004% Ti, 0.004% B, 0.0005% Mg and the balance Al are added to an aluminum smelting furnace, and after smelting, an ingot is formed by a casting machine, the pouring portion of the ingot is cut off, the upper and lower large surfaces of the ingot are milled, and the ingot is annealed at high temperature. After being taken out of the furnace, it is naturally cooled, and after preheating, it is rolled in multiple passes on a hot rolling mill, and then subjected to cold rough rolling and cold finishing rolling processes, and then subjected to three foil rolling processes of rough rolling, intermediate rolling and finishing rolling, and then slitting and annealing to obtain an aluminum foil with a thickness of 30 μm;

[0084] The matte and bright surfaces of the aluminum foil were coated with a degreasing passivation liquid containing trivalent chromium, the ratio of the passivation liquid was acid-resistant agent: ethanol: water = 2:2:1, and dried in a 90°C suspension oven for 2 minutes;

[0085] 55 parts by weight of maleic anhydride grafted polypropylene, 44 parts by weight of homopolymer polypropylene resin, and 1 part by weight of lubricating masterbatch were mixed and added to extruder A, 95 parts by weight of homopolymer polypropylene resin and 5 parts by weight of lubricating masterbatch were mixed and added to extruder B, 97 parts by weight of ternary copolymer polypropylene and 3 parts by weight of lubricating masterbatch were mixed and added to extruder C, and hot-melt extrusion was performed at 240°C and cooled to form a three-layer co-extruded cast polypropylene layer with a thickness of 17 μm;

[0086] The bright surface of the aluminum foil is thermally compounded with three layers of co-extruded cast polypropylene at 200°C;

[0087] The aluminum foil matte coating is made of polyurethane glue A (model: Weikai VN930), with a ratio of main agent: curing agent: solvent = 5:1:3. After being dried in a suspension oven, a nylon layer with a thickness of 15 μm is formed, and the thickness of the adhesive layer is 3 μm.

[0088] The obtained aluminum-plastic film semi-finished product is smoothed to obtain an ultra-thin aluminum-plastic film with a total thickness of 65 μm.

[0089] Comparative Example 2

[0090] The invention provides an aluminum-plastic film and a preparation method thereof. The ultra-thin aluminum-plastic film comprises a nylon layer, an aluminum foil layer and a three-layer co-extruded cast polypropylene layer.

[0091] 0.063% Sb, 0.016% Si, 1.5% Fe, 0.011% Cu, 0.005% Mn, 0.0006% Zn, 0.004% Ti, 0.004% B, 0.0005% Mg and the balance Al are added to an aluminum smelting furnace, and after smelting, an ingot is formed by a casting machine, the pouring portion of the ingot is cut off, the upper and lower large surfaces of the ingot are milled, and the ingot is annealed at high temperature. After being taken out of the furnace, it is naturally cooled, and after preheating, it is rolled in multiple passes on a hot rolling mill, and after cold rough rolling and cold finishing rolling, three foil rolling processes of rough rolling, intermediate rolling and finishing rolling are performed, and after slitting and annealing, a high-strength, high-elongation, deep-drawing-resistant aluminum foil with a thickness of 25 μm is obtained;

[0092] The matte and bright surfaces of the aluminum foil were coated with a degreasing passivation liquid containing trivalent chromium, the ratio of the passivation liquid was acid-resistant agent: ethanol: water = 2:2:1, and dried in a 90°C suspension oven for 2 minutes;

[0093] 55 parts by weight of maleic anhydride grafted polypropylene, 44 parts by weight of homopolymer polypropylene resin, and 1 part by weight of lubricating masterbatch were mixed and added to extruder A, 95 parts by weight of homopolymer polypropylene resin and 5 parts by weight of lubricating masterbatch were mixed and added to extruder B, 97 parts by weight of ternary copolymer polypropylene and 3 parts by weight of lubricating masterbatch were mixed and added to extruder C, and hot-melt extrusion was performed at 240°C and cooled to form a three-layer co-extruded cast polypropylene layer with a thickness of 17 μm;

[0094] The bright surface of the aluminum foil is heat-compounded with a three-layer co-extruded cast polypropylene layer at 140°C;

[0095] The aluminum foil matte coating is made of polyurethane glue A (model: Weikai VN930), with a ratio of main agent: curing agent: solvent = 5:1:3. After being dried in a suspension oven, a nylon layer with a thickness of 15 μm is formed, and the thickness of the adhesive layer is 3 μm.

[0096] The obtained aluminum-plastic film semi-finished product is smoothed to obtain an ultra-thin aluminum-plastic film with a total thickness of 60 μm.

[0097] Comparative Example 3

[0098] 1.5% Fe, 0.011% Cu, 0.005% Mn, 0.0006% Zn, 0.004% Ti, 0.004% B, 0.0005% Mg and the balance Al are added to an aluminum smelting furnace, and after smelting, an ingot is formed by a casting machine, the pouring portion of the ingot is cut off, the upper and lower large surfaces of the ingot are milled, and the ingot is annealed at high temperature. After being taken out of the furnace, it is naturally cooled, and after preheating, it is rolled in multiple passes on a hot rolling mill, and then subjected to cold rough rolling and cold finishing rolling processes, and then subjected to three foil rolling processes of rough rolling, intermediate rolling and finishing rolling, and then slitting and annealing to obtain an aluminum foil with a thickness of 30 μm;

[0099] The matte and bright surfaces of the aluminum foil were coated with a degreasing passivation liquid containing trivalent chromium, the ratio of the passivation liquid was acid-resistant agent: ethanol: water = 2:2:1, and dried in a 90°C suspension oven for 2 minutes;

[0100] 50 parts by weight of maleic anhydride grafted polypropylene, 49 parts by weight of homopolypropylene resin, and 1 part by weight of lubricating masterbatch were mixed and added to extruder A, 85 parts by weight of silica-doped POE resin Exxon 6502, 10 parts by weight of hyperbranched polyamide Kramar 114615, and 5 parts by weight of lubricating masterbatch were mixed and added to extruder B, 95 parts by weight of ternary copolymer polypropylene and 5 parts by weight of lubricating masterbatch were mixed and added to extruder C, and hot-melt extrusion was performed at 230° C. and cooling was performed to form a three-layer co-extruded cast polypropylene layer with a thickness of 12 μm;

[0101] The bright surface of the aluminum foil is heat-compounded with a three-layer co-extruded cast polypropylene layer at 140°C;

[0102] The aluminum foil matte coating is made of polyurethane glue A (model: Weikai VN930), with a ratio of main agent: curing agent: solvent = 5:1:3. After being dried in a suspension oven, a nylon layer with a thickness of 15 μm is formed, and the thickness of the adhesive layer is 3 μm.

[0103] The obtained aluminum-plastic film semi-finished product is smoothed to obtain an ultra-thin aluminum-plastic film with a total thickness of 65 μm.

[0104] Table 1 Performance test results of ultra-thin films provided by Examples 1-3 and Comparative Examples 1-3

[0105]

[0106] Compared with the technical solution provided by the present invention, the difference of Comparative Example 1 is that the aluminum foil does not contain rare earth elements Sb and Si, and the silica-doped POE resin and hyperbranched polyamide flexible resin are eliminated in the three-layer co-extruded cast polypropylene layer, resulting in insufficient ductility of the aluminum foil, greater rigidity of the inner layer, and easy damage under force during deep punching, resulting in poor deep punching performance and a corresponding reduction in heat sealing peeling force.

[0107] Furthermore, the difference of Comparative Example 2 is that the silica-doped POE resin and the hyperbranched polyamide flexible resin are eliminated in the three-layer co-extruded cast polypropylene layer of the aluminum foil, so the inner layer is more rigid and easily damaged by the force during deep punching, resulting in poor deep punching performance.

[0108] Furthermore, the difference of Comparative Example 3 is that the aluminum foil layer does not contain the rare earth elements Sb and Si, and the aluminum foil layer has insufficient ductility, resulting in poor tensile properties. When the punching force is applied, the aluminum foil is easily damaged, resulting in poor punching performance.

[0109] In summary, the ultra-thin aluminum-plastic film, its preparation method, and lithium battery add rare earth elements Sb and Si during the aluminum foil smelting process, so that the aluminum foil substrate has good mechanical properties and ductility. At the same time, silica-doped POE resin and hyperbranched polyamide are added to the support layer of the three-layer co-extruded cast polypropylene layer to increase the flexibility of the aluminum-plastic film, so that the aluminum-plastic film has both the effects of lightness and impact resistance.

[0110] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An ultra-thin aluminum-plastic film, characterized in that: From the inside to the outside, it includes a nylon layer, an aluminum foil layer and a polypropylene layer; wherein, The aluminum foil layer is formed by melting materials including the following mass percentages: Sb 0.02-0.063%, Si 0.016-0.126%, Fe 1.0-1.5%, Cu 0.006-0.011%, Mn 0.005-0.01%, Zn 0.006-0.009%, Ti 0.004-0.008%, B 0.004-0.008%, Mg 0.0005-0.002%, and the balance is Al; The polypropylene layer is a three-layer co-extruded cast polypropylene layer, which includes a corona layer, a support layer and a heat sealing layer from the outside to the inside; The components of the support layer include silicon dioxide doped POE resin and hyperbranched polyamide.

2. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The mass ratio of Sb to Si in the aluminum foil layer is 0.5-4.

3. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The thickness of the polypropylene layer is 15-25 μm; The thickness ratio of the corona layer, the support layer and the heat sealing layer is (0.8-1.2): (1.8-2.2): (0.8-1.2).

4. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The corona layer is composed of the following components in parts by weight: 50-60 parts of maleic anhydride grafted polypropylene, 35-50 parts of homopolypropylene resin, and 1-5 parts of lubricating masterbatch.

5. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The support layer is composed of the following components in parts by weight: 85-90 parts of silicon dioxide-doped POE resin, 5-10 parts of hyperbranched polyamide, and 1-5 parts of lubricating masterbatch.

6. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The heat sealing layer is composed of the following components in parts by weight: 95-99 parts of terpolymer polypropylene and 1-5 parts of lubricating masterbatch.

7. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The thickness of the ultra-thin aluminum-plastic film is 55-75 μm.

8. The ultra-thin aluminum-plastic film according to claim 1, characterized in that: The thickness of the nylon layer is 15-20 μm; The thickness of the aluminum foil layer is 25-30 μm.

9. A method for preparing an ultra-thin aluminum-plastic film according to any one of claims 1 to 8, characterized in that: The steps include: Step S1, aluminum foil smelting and rolling, adding each element into an aluminum smelting furnace according to the mass ratio to obtain aluminum foil; Step S2, coating the matte surface and the bright surface of the aluminum foil layer with a degreasing passivation liquid containing trivalent chromium respectively, and drying in an oven to obtain an aluminum foil layer; Step S3, adding the components of the corona layer, the support layer and the heat-sealing layer into an extruder according to a ratio, hot-melt extrusion and cooling to form, to obtain a three-layer co-extruded cast polypropylene layer; Step S4, thermally compounding the bright surface of the aluminum foil layer with the corona layer of the three-layer co-extruded cast polypropylene layer at 140-240° C.; Step S5, coating the matte surface of the aluminum foil layer with polyurethane glue and then compounding it with the nylon layer after drying in an oven to obtain an aluminum-plastic film semi-finished product; Step S6, smoothing the aluminum-plastic film semi-finished product to obtain an ultra-thin aluminum-plastic film.

10. A lithium battery, characterized in that: The ultra-thin aluminum-plastic film according to any one of claims 1 to 8 is used, wherein the thickness of the ultra-thin aluminum-plastic film is 55-75 μm.

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