A corrosion-resistant metal-plastic composite film

Abstract

The present invention provides a corrosion-resistant metal-plastic composite film, in which an anti-corrosion layer is formed on at least one side of a metal layer, and the content of each element in the anti-corrosion layer is in a gradient distribution. The content of each element in the anti-corrosion layer is controlled to improve the initial peeling strength and corrosion resistance between the metal layer and the first resin layer of the metal-plastic composite film, and the moisture intruding into the anti-corrosion layer can react with the anti-corrosion layer to generate hydrogen fluoride, so that the anti-corrosion layer is further inhibited from being dissolved, and a bridging agent can be added to the anti-corrosion layer to improve the crosslinking density of the anti-corrosion layer, so that the tolerance of the anti-corrosion layer to an electrolyte as a content and hydrogen fluoride generated by the reaction of the electrolyte and water is stabilized.

Description

Technical Field

[0001] The invention relates to the technical field of metal-plastic film production, in particular to a corrosion-resistant metal-plastic composite film. Background Art

[0002] Currently, lithium-ion batteries are mainly divided into three categories: square, cylindrical, and soft-pack. The outer shells of square and cylindrical batteries are mainly made of hard shells such as aluminum alloy and stainless steel. The aluminum alloy outer shell can be made of aluminum, while the soft-pack outer shell made of metal and resin laminated is made of metal-plastic composite film, which greatly improves the problem of inflexible appearance design of hard-mounted batteries.

[0003] As a battery outer packaging material, the metal-plastic composite film must have the performance of being resistant to electrolyte corrosion, so as to prevent problems such as leakage of the battery shell and ensure the service life of the battery. Generally speaking, the metal in the metal-plastic composite film for lithium-ion battery outer packaging needs to be treated with corrosion protection. If the corrosion protection effect is not ideal, if water is mixed into the battery manufacturing process, it will react with the lithium salt in the electrolyte to generate corrosive hydrogen fluoride (HF). The hydrogen fluoride will pass through the heat-welding resin layer and its adhesive layer to reach the surface of the metal layer, thereby corroding the metal and causing the metal and the heat-welding resin layer to separate. For this reason, the possibility of electrolyte leakage from the battery is increased. Therefore, the corrosion protection treatment of the metal layer has a great influence on the metal-plastic composite film.

[0004] At present, the main components of the anti-corrosion liquid of metal-plastic composite film are trivalent chromium compounds, fluorides, aminophenol resins and phosphoric acid. After the metal layer is treated with the anti-corrosion liquid, the corrosion resistance of the metal-plastic composite film can be improved in some common electrolyte environments. However, during long-term use of the battery, moisture may penetrate the battery outer packaging, causing the electrolyte to produce hydrogen fluoride. At this time, the anti-corrosion treatment effect of the anti-corrosion liquid will be unsatisfactory, and it is easy to cause interlayer separation of the metal-plastic composite film for lithium-ion batteries, affecting the promotion and use of the metal-plastic composite film in the field of lithium-ion batteries. Summary of the invention

[0005] The object of the present invention is to provide a corrosion-resistant metal-plastic composite film, which has an anti-corrosion layer containing carbon elements, metal elements and fluorine elements, and the distribution of the various elements presents a gradient distribution from the side away from the metal layer to the side close to the metal layer, thereby achieving high corrosion resistance and greatly reducing the possibility of electrolyte leakage from the battery.

[0006] Another object of the present invention is to provide a corrosion-resistant metal-plastic composite film, which adds a bridging agent to the anti-corrosion layer to increase the crosslinking density of the anti-corrosion layer and stabilize the tolerance of the anti-corrosion layer to the electrolyte as the content and the hydrogen fluoride generated by the reaction of the electrolyte and water.

[0007] To achieve the above-mentioned object, the present invention provides a corrosion-resistant metal-plastic composite film, comprising:

[0008] a metal layer; and

[0009] An anti-corrosion layer is arranged on at least one side of the metal layer, the anti-corrosion layer contains a carbon element, a metal element and a fluorine element, and the carbon element, the metal element and the fluorine element are distributed in a gradient from the side of the anti-corrosion layer away from the metal layer to the side close to the metal layer.

[0010] Preferably, the anti-corrosion layer comprises a first anti-corrosion region, a second anti-corrosion region and a third anti-corrosion region, the first anti-corrosion region is the side of the anti-corrosion layer away from the metal layer, the second anti-corrosion region is located between the first anti-corrosion region and the third anti-corrosion region, and the third anti-corrosion region is the side of the anti-corrosion layer close to the metal layer, wherein in the first anti-corrosion region, the content ratio of the carbon element is 40%-100%, and the content ratio of the metal element is not more than 5%, in the second anti-corrosion region, the content ratio of the metal element is 10%-70%, and in the third anti-corrosion region, the content ratio of the metal element is 20%-100%.

[0011] Preferably, in the second anti-corrosion zone, the content ratio of the fluorine element is not greater than 30%, and the ratio of the fluorine element to the metal element is not greater than 2. In the third anti-corrosion zone, the content ratio of the fluorine element is not greater than 20%, and the ratio of the fluorine element to the metal element is not greater than 1.

[0012] Preferably, the material of the metal layer is at least one of aluminum alloy, stainless steel, titanium steel or nickel plating.

[0013] Preferably, the anti-corrosion layer is formed by an anti-corrosion liquid, and the anti-corrosion liquid is formed by mixing a trivalent chromium compound, an inorganic acid and an organic resin with water or an organic solvent, the proportion of the trivalent chromium compound in the anti-corrosion liquid is 1.9-6%, the proportion of the inorganic acid in the anti-corrosion liquid is 0.3-6%, the proportion of the organic resin in the anti-corrosion liquid is 0.6-6%, and the proportion of water or organic solvent in the anti-corrosion liquid is 78.6-97.2%.

[0014] Preferably, the trivalent chromium compound is at least one of chromium nitrate or chromium fluoride.

[0015] Preferably, the inorganic acid is composed of at least one of phosphoric acid, nitric acid or hydrofluoric acid.

[0016] Preferably, the organic resin is composed of at least one of acrylic resin, methacrylic resin, hydroxy acrylic resin, polyvinyl alcohol resin, olefin resin or phenolic resin.

[0017] Preferably, the organic solvent is at least one of isopropanol, ethanol and ethylene glycol butyl ether.

[0018] Preferably, the components of the anti-corrosion layer include a bridging agent, wherein the bridging agent is composed of at least one of an amino resin, a melamine resin, a phenolic resin, an epoxy compound, a blocked isocyanate compound, an oxazoline compound, a carbodiimide compound, a condensate of formaldehyde and an alkyl monool having 1 to 4 carbon atoms, and a condensate of carbolic acid or formaldehyde.

[0019] Preferably, the proportion of the bridging agent content in the solid components of the anti-corrosion liquid is 0.05%-15%, or the proportion of the bridging agent content in the solid components of the anti-corrosion layer is 0.01%-30%.

[0020] Preferably, the anti-corrosion layer comprises a titanium (Ti) compound and a zirconium (Zr) compound, the content ratio of the titanium (Ti) compound is not greater than 0.6%, and the content ratio of the zirconium (Zr) compound is not greater than 2.8%.

[0021] Preferably, the titanium (Ti) compound is at least one of titanium fluoride and titanium nitrate, and the zirconium (Zr) compound is at least one of zirconium fluoride and zirconium nitrate.

[0022] Preferably, it further comprises a first resin layer and a second resin layer, wherein the first resin layer is disposed on one side of the metal layer, and the second resin layer is disposed on the other side of the metal layer.

[0023] Preferably, the first resin layer is bonded to the metal layer with a first adhesive.

[0024] Preferably, the material of the first adhesive is at least one of block copolymer polypropylene resin (B-PP), random copolymer polypropylene resin (R-PP) or homopolymer polypropylene resin (H-PP), and the polypropylene (PP) content in the block copolymer polypropylene resin (B-PP), random copolymer polypropylene resin (R-PP) or homopolymer polypropylene resin (H-PP) is not less than 50%.

[0025] Preferably, the second resin layer is bonded to the metal layer with a second adhesive.

[0026] Preferably, the first resin layer is a heat-welding resin layer, wherein the material of the first resin layer is composed of at least one of polyolefin, cyclic polyolefin or modified polyolefin resin.

[0027] Preferably, the modified polyolefin tree is composed of at least one of aliphatic carboxylic acid modified polyolefin, carboxylic acid modified cyclic polyolefin, methacrylic acid modified polyolefin, acrylic acid modified polyolefin, crotonic acid modified polyolefin or imide modified polyolefin.

[0028] Preferably, the side of the metal layer bonded to the first resin layer forms the anti-corrosion layer.

[0029] To achieve the above-mentioned another object, the present invention provides a method for forming a corrosion-resistant metal-plastic composite film, characterized in that it comprises the steps of:

[0030] a metal layer; and

[0031] An anti-corrosion layer is arranged on at least one side of the metal layer, the anti-corrosion layer comprises a carbon element, a metal element, a fluorine element and a bridging agent, and the carbon element, the metal element and the fluorine element are distributed in a gradient manner from a side of the anti-corrosion layer away from the metal layer to a side close to the metal layer.

[0032] Preferably, the anti-corrosion layer comprises a first anti-corrosion region, a second anti-corrosion region and a third anti-corrosion region, the first anti-corrosion region is the side of the anti-corrosion layer away from the metal layer, the second anti-corrosion region is located between the first anti-corrosion region and the third anti-corrosion region, and the third anti-corrosion region is the side of the anti-corrosion layer close to the metal layer, wherein in the first anti-corrosion region, the content ratio of the carbon element is 40%-100%, and the content ratio of the metal element is not more than 5%, in the second anti-corrosion region, the content ratio of the metal element is 10%-70%, and in the third anti-corrosion region, the content ratio of the metal element is 20%-100%.

[0033] Preferably, in the second anti-corrosion zone, the content ratio of the fluorine element is not greater than 30%, and the ratio of the fluorine element to the metal element is not greater than 2. In the third anti-corrosion zone, the content ratio of the fluorine element is not greater than 20%, and the ratio of the fluorine element to the metal element is not greater than 1.

[0034] Preferably, the material of the metal layer is at least one of aluminum alloy, stainless steel, titanium steel or nickel-plated steel plate.

[0035] Preferably, the anti-corrosion layer is formed by an anti-corrosion liquid, and the anti-corrosion liquid is formed by mixing a trivalent chromium compound, an inorganic acid and an organic resin with water or an organic solvent, the proportion of the trivalent chromium compound in the anti-corrosion liquid is 1.9-6%, the proportion of the inorganic acid in the anti-corrosion liquid is 0.3-6%, the proportion of the organic resin in the anti-corrosion liquid is 0.6-6%, and the proportion of water or organic solvent in the anti-corrosion liquid is 78.6-97.2%.

[0036] Preferably, the trivalent chromium compound is at least one of chromium nitrate or chromium fluoride, the inorganic acid is at least one of phosphoric acid, nitric acid or hydrofluoric acid, the organic resin is at least one of acrylic resin, methacrylic resin, hydroxy acrylic resin, polyvinyl alcohol resin, olefin resin or phenolic resin, and the organic solvent is at least one of isopropyl alcohol, ethanol and ethylene glycol butyl ether.

[0037] Preferably, the bridging agent is composed of at least one of amino resin, melamine resin, phenolic resin, epoxy compound, blocked isocyanate compound, oxazoline compound, carbodiimide compound, condensate of formaldehyde and alkyl monoalcohol having 1-4 carbon atoms, condensate of carbolic acid and formaldehyde, and derivatives of the above substances.

[0038] Preferably, the bridging agent comprises at least one inorganic bridging agent selected from the group consisting of silicon compounds, zirconium compounds, metal chelates and metal salts.

[0039] Preferably, the silicon compound is silicon dioxide.

[0040] Preferably, the zirconium compound is at least one of ammonium zirconium fluoride or ammonium zirconium carbonate.

[0041] Preferably, the metal chelate is a titanium chelate.

[0042] Preferably, the metal salt is composed of at least one of calcium (Ca), aluminum (Al), magnesium (Mg), iron (Fe), and zinc (Zn).

[0043] Preferably, the proportion of the bridging agent content in the solid components of the anti-corrosion liquid is 0.05%-15%, or the proportion of the bridging agent content in the solid components of the anti-corrosion layer is 0.01%-30%.

[0044] Preferably, the anti-corrosion layer comprises a titanium (Ti) compound and a zirconium (Zr) compound, the content ratio of the titanium (Ti) compound is not greater than 0.6%, and the content ratio of the zirconium (Zr) compound is not greater than 2.8%.

[0045] Preferably, the titanium (Ti) compound is at least one of titanium fluoride or titanium nitrate, and the zirconium (Zr) compound is at least one of zirconium fluoride or zirconium nitrate.

[0046] Preferably, it further comprises a first resin layer and a second resin layer, wherein the first resin layer is disposed on one side of the metal layer, and the second resin layer is disposed on the other side of the metal layer.

[0047] Preferably, the first resin layer is bonded to the metal layer with a first adhesive.

[0048] Preferably, the material of the first adhesive is at least one of block copolymer polypropylene resin (B-PP), random copolymer polypropylene resin (R-PP) or homopolymer polypropylene resin (H-PP), and the polypropylene (PP) content in the block copolymer polypropylene resin (B-PP), random copolymer polypropylene resin (R-PP) or homopolymer polypropylene resin (H-PP) is not less than 50%.

[0049] Preferably, the second resin layer is bonded to the metal layer with a second adhesive.

[0050] Preferably, the first resin layer is a heat-melting resin layer, wherein the material of the first resin layer is composed of at least one of polyolefin, cyclic polyolefin or modified polyolefin.

[0051] Preferably, the modified polyolefin is at least one of aliphatic carboxylic acid modified polyolefin, carboxylic acid modified cyclic polyolefin, methacrylic acid modified polyolefin, acrylic acid modified polyolefin, crotonic acid modified polyolefin or imide modified polyolefin.

[0052] Preferably, the side of the metal layer bonded to the first resin layer forms the anti-corrosion layer.

[0053] The beneficial effect of the present invention is that an anti-corrosion layer with gradient distribution of various elements is formed on the metal layer, which can improve the initial peel strength and corrosion resistance between the metal layer and the first resin layer of the metal-plastic composite film, and make the moisture intruding into the anti-corrosion layer react with the anti-corrosion layer to generate hydrogen fluoride, so that the anti-corrosion layer is further inhibited from being dissolved, thereby ensuring the bonding stability of the metal layer and the first resin layer, and a bridging agent can be further added to increase the crosslinking density of the anti-corrosion layer, so that the tolerance of the anti-corrosion layer to the electrolyte as the content and the hydrogen fluoride generated by the reaction of the electrolyte and water is stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic structural diagram of the metal-plastic composite film according to the first embodiment of the present invention;

[0055] Figure 2is a schematic structural diagram of a metal-plastic composite film according to a second embodiment of the present invention; and

[0056] Figure 3 The figure is a flow chart of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the above and / or other purposes, effects, and features of the present invention more clearly understood, preferred embodiments are specifically described below in detail:

[0058] See also Figure 1-2 , which is a schematic diagram of the structure of the metal-plastic composite film of the first embodiment to the second embodiment of the present invention. As shown in the figure, the structural differences are different embodiments of the present invention. The corrosion-resistant metal-plastic composite film 1 of the present invention includes a metal layer 11 and an anti-corrosion layer 12, and, further, the metal-plastic composite film 1 further includes a first resin layer 13 and a second resin layer 14, wherein the anti-corrosion layer 12 is disposed on at least one side of the metal layer, the first resin layer 13 is disposed on one side of the metal layer 11, and the second resin layer 14 is disposed on the other side of the metal layer 11, and is described in detail as follows:

[0059] The material of the metal layer 11 is at least one of aluminum alloy, stainless steel, titanium steel or nickel plating. In one embodiment, the metal layer 11 can be a metal plate type or a metal foil type, but is not limited thereto. When an aluminum alloy foil is used, a soft aluminum alloy foil composed of annealed aluminum alloy or the like can be preferably used to further improve the formability, or an aluminum alloy foil containing an iron component can be preferably used. In addition, according to the needs of electrolyte resistance, silicon dioxide, magnesium, etc. can also be added. When a stainless steel foil is used, an austenitic, ferritic, austenitic ferritic, martensitic, or precipitation hardened stainless steel foil can be used. Austenitic stainless steel, such as SUS304, SUS301 or SUS316L, can be more preferably used. Preferably, SUS304 is preferred.

[0060] In one embodiment, when the metal layer 11 is in the form of a metal foil, its thickness is 9μm-200μm. More preferably, the thickness of the metal layer 11 is preferably 9μm-100μm. More preferably, the thickness of the metal layer 11 is preferably 9μm-50μm, but not limited thereto. The thickness can be any thickness as long as the metal layer 11 can function to inhibit moisture intrusion.

[0061] In another embodiment, when the metal layer 11 is in the form of a metal plate, preferably, a nickel-plated layer can be formed on one side of the metal layer 11, so that the metal layer 11 can further increase its anti-rust and other anti-corrosion effects, and at the same time, the surface cleanliness of the metal layer 11 is also improved, wherein the thickness of the nickel-plated layer is not greater than 10μm, and more preferably, the thickness of the metal layer 11 is preferably 1μm-5μm to avoid cracking when the thickness is too high under external pressure load, but it is not limited thereto.

[0062] For this reason, in the past, when the metal layer 11 has an alloy component, the alloy component will be precipitated on the surface of the metal layer 11, or the volatility of the rolling oil will be affected during the annealing process in the rolling process. Therefore, in the adjustment of the alloy component, the management of the surface cleanliness of the metal layer 11 becomes very important. The surface cleanliness can be managed by a method using a wetting reagent to test wettability as an indicator, or by a method using a contact angle as an indicator. Among them, the wettability indicator is A-D, preferably B, and the contact angle indicator is when tested with pure water, the contact angle is The degree is not greater than 25°, preferably not greater than 20°, and more preferably not greater than 15°. In one embodiment, the surface wettability test method of the metal layer 11 may adopt "National Standard of the People's Republic of China GB / T225638.5-2016, Metal Test Methods, Part 5: Detection of Wettability", and the contact angle test method of the metal layer 11 may adopt "National Standard of the People's Republic of China GB / T22638.9-2008, Metal Test Methods Part 9: Determination of Hydrophilicity", but is not limited thereto.

[0063] When the wettability is lower than grade D, or the contact angle exceeds 25°, the reactivity or initial adhesion of the anticorrosion layer 12 will deteriorate. If the reactivity deteriorates, the reaction between the anticorrosion layer 12 and the metal layer 11 will become insufficient, and the resistance to the penetration of the electrolyte of the battery and the resistance to hydrogen fluoride produced by the reaction of the electrolyte and water will be reduced. Therefore, as time goes by, the adhesion of the anticorrosion layer 12 to the metal layer 11 will significantly decrease, causing the anticorrosion layer 12 to dissolve, and the metal layer 11 and the anticorrosion layer 12 will peel off, thereby shortening the life of the battery. In addition, the same situation will occur when the initial adhesion between the anticorrosion layer 12 and the metal layer 11 deteriorates. The present invention adjusts the alloy composition so that the proportion of the alloy is within a certain range, thereby inhibiting the precipitation of the alloy from the metal layer 11, and in the annealing process during the rolling process, it makes it easy to manage the temperature and time conditions.

[0064] The anti-corrosion layer 12 includes carbon elements, metal elements and fluorine elements, and the distribution of each element in the anti-corrosion layer 12 from the side away from the metal layer 11 to the side close to the metal layer 11 presents a gradient distribution. In one embodiment, the anti-corrosion layer includes a first anti-corrosion region, a second anti-corrosion region and a third anti-corrosion region, the first anti-corrosion region is the side of the anti-corrosion layer away from the metal layer, the second anti-corrosion region is located between the first anti-corrosion region and the third anti-corrosion region, and the third anti-corrosion region is the side of the anti-corrosion layer close to the metal layer. Therefore, in the first anti-corrosion region, the content ratio of carbon elements is 40%-100%, and the content ratio of metal elements is not more than 5%; in the second anti-corrosion region, the content ratio of metal elements is 10%-70%, and the content ratio of fluorine elements is not more than 30%, and the ratio of fluorine elements to metal elements is not more than 2; and in the third anti-corrosion region, the content ratio of metal elements is 20%-100%, the content ratio of fluorine elements is not more than 20%, and the ratio of fluorine elements to metal elements is not more than 1, but not limited thereto.

[0065] In one embodiment, after the anti-corrosion layer 12 is immersed in an electrolyte with 1000PPM of water for 5 days, the fluorine content of the anti-corrosion layer 12 in the second anti-corrosion area is controlled to be no more than 30%, and the ratio of fluorine to metal elements is no more than 2; in the third anti-corrosion area, the fluorine content ratio is no more than 20%, and the ratio of fluorine to metal elements is no more than 1. In one embodiment, the electrolyte contains a mixed solvent of EC, DEC and DMC containing 1 mol / L LiPF6, wherein the mass ratio of EC:DEC:DMC is 1:1:1, and is immersed for 5 days, but not limited to this.

[0066] The gradient distribution of each element in the anti-corrosion layer 12 has the following functions:

[0067] In the first anti-corrosion area, when the carbon content is less than 40% or the metal content is greater than 5%, the bonding strength between the anti-corrosion layer 12 and the first adhesive 131 will be unstable and affected by the electrolyte. At the same time, the peel strength will decrease during the storage process, or the internal insulation will decrease due to the increase in the metal content, resulting in a shortened battery life, or the electrolyte will leak due to an electrical short circuit between the outer packaging material and the inside of the battery.

[0068] When the content ratio of the fluorine element in the second anti-corrosion area is greater than 30%, the resin component is relatively reduced due to the inclined distribution in the anti-corrosion layer 12, so that the bonding strength of the first adhesive 131 tends to be unstable. Moreover, when the ratio of the fluorine element to the metal element is greater than 2, the corrosion effect of the hydrogen fluoride generated by the electrolyte will be reduced, and in the long run, the peel strength between the first adhesive 131 and the metal layer 11 may be greatly reduced; and

[0069] When the content ratio of fluorine element in the third anti-corrosion zone is greater than 20%, the reaction products of the anti-corrosion layer 12 and the metal layer 11 become less. In the long run, the peel strength between the first adhesive 131 and the metal layer 11 may be greatly reduced. Moreover, when the ratio of fluorine element to metal element here is greater than 1, the corrosion effect of hydrogen fluoride generated by the electrolyte will be reduced. In the long run, the peel strength between the first adhesive 131 and the metal layer 11 may be greatly reduced. At the same time, in the first anti-corrosion zone, the carbon element content increases the carbon component of the first resin layer 13 in contact with the anti-corrosion layer 12, thereby ensuring the bonding stability between the first resin layer 13 and the metal layer 11 with the first adhesive 131. On the contrary, when the adhesion of the first adhesive 131 is unstable, when the electrolyte penetrates, the adhesion force decreases and the peel strength is unstable.

[0070] In summary, the carbon content in the first anti-corrosion area is relatively high, and the metal element gradually increases as it approaches the metal layer 11 side. Thus, while maintaining the adhesion with the first resin layer 13, even if it comes into contact with the electrolyte and the electrolyte penetrates or the electrolyte reacts with water, the penetration of hydrogen fluoride that corrodes the metal layer 11 can be suppressed. In order to suppress the penetration of hydrogen fluoride and the electrolyte, the inclined structure is a cross-linked structure.

[0071] In one embodiment, when the aluminum content in the anti-corrosion layer 12 increases, the adhesion between the anti-corrosion layer 12 and the metal layer 12 increases. Therefore, when the soft-packaged lithium battery is used for a long time, the intruded moisture will react with the electrolyte to generate hydrogen fluoride. At this time, the dissolution of the anti-corrosion layer 12 on the metal layer 11 will be inhibited, and the peel strength stability between the first adhesive 131 and the metal layer 11 will be guaranteed. Moreover, this effect is improved with the increase of the fluoride content in the anti-corrosion layer 12.

[0072] In one embodiment, the anti-corrosion layer 12 is formed by an anti-corrosion liquid, and the anti-corrosion liquid is formed by mixing a trivalent chromium compound, an inorganic acid, an organic resin, and water or an organic solvent, wherein the proportion of the trivalent chromium compound in the anti-corrosion liquid is 1.9-6%, the proportion of the inorganic acid in the anti-corrosion liquid is 0.3-6%, the proportion of the organic resin in the anti-corrosion liquid is 0.6-6%, and the proportion of water or the organic solvent in the anti-corrosion liquid is 78.6-97.2%. The role of the organic solvent is to reduce the surface tension of the anti-corrosion liquid to increase the leveling property of the anti-corrosion liquid on the surface of the metal layer 11, but this is not limited to this.

[0073] In one embodiment, the trivalent chromium compound is at least one of chromium nitrate or chromium fluoride, and the function of the trivalent chromium compound is to form a coordinated cross-linked structure centered on chromium (Cr) atoms on the surface of the metal layer 11. At this time, the trivalent chromium compound plays a role in increasing the cross-linking degree of the anti-corrosion film on the surface of the metal layer 11; the inorganic acid is at least one of phosphoric acid, nitric acid or hydrofluoric acid; the organic resin is at least one of acrylic resin, methacrylic resin, hydroxy acrylic resin, polyvinyl alcohol resin, olefin resin or phenolic resin; and the organic solvent is at least one of isopropyl alcohol, ethanol, and ethylene glycol butyl ether, but is not limited thereto.

[0074] In one embodiment, the anti-corrosion liquid further comprises a titanium (Ti) compound or a zirconium (Zr) compound, and the titanium (Ti) compound or the zirconium (Zr) compound is used as a secondary central cross-linking point to enhance the corrosion resistance of the surface of the metal layer 11, wherein the proportion of the titanium (Ti) compound in the anti-corrosion liquid is not greater than 0.6%, and the proportion of the zirconium (Zr) compound in the anti-corrosion liquid is not greater than 2.8%, and the titanium (Ti) compound is at least one of titanium fluoride and titanium nitrate, and the zirconium (Zr) compound is at least one of zirconium fluoride and zirconium nitrate, but is not limited thereto.

[0075] In addition, it can be inferred that the effective ingredients in the anti-corrosion liquid will react with the metal layer 11 to produce reaction products, such as reaction products of the resin component in the anti-corrosion layer 12 with chromium (Cr), titanium (Ti), zirconium (Zr), reaction products of inorganic acids with chromium (Cr), and reaction products of fluorides or inorganic acids in the metal layer 11 and the anti-corrosion layer 12.

[0076] In one embodiment, the anti-corrosion liquid further includes a bridging agent. By adding the bridging agent, the crosslinking density of the anti-corrosion layer 12 can be increased, so that the anti-corrosion layer 12 has a more stable tolerance to hydrogen fluoride generated by the reaction between the electrolyte and water. The bridging agent is divided into an organic bridging agent and an inorganic bridging agent. The inorganic bridging agent includes at least one of silicon dioxide compounds such as silicon dioxide, zirconium compounds such as ammonium zirconium fluoride and ammonium zirconium carbonate, metal chelates such as titanium chelates, and metal salts such as Ca, Al, Mg, Fe, and Zn, but is not limited thereto. The organic bridging agent includes at least one of amino resins, melamine resins, phenolic resins, epoxy compounds, blocked isocyanate compounds, oxazoline compounds, carbodiimide compounds, condensates of formaldehyde and alkyl monohydric alcohols having 1 to 4 carbon atoms, and condensates of carbolic acid and formaldehyde, but is not limited thereto.

[0077] In one embodiment, the bridging agent is composed of at least one of a compound having any functional chemical group of isocyanate chemical group, glycidyl chemical group, carboxyl chemical group, oxazoline chemical group and a silane coupling agent, but is not limited thereto.

[0078] In one embodiment, the proportion of the bridging agent content in the solid components of the anti-corrosion liquid is 0.05%-15%, or the proportion of the bridging agent content in the solid components of the anti-corrosion layer 12 is 0.01%-30%, but not limited thereto. When the proportion of the bridging agent in the anti-corrosion liquid is less than 0.05%, the corrosion resistance of the anti-corrosion layer 12 cannot be improved by adding the bridging agent. On the contrary, when the proportion of the bridging agent in the anti-corrosion liquid exceeds 15%, the cross-linking density of the anti-corrosion layer 12 increases, resulting in the anti-corrosion layer 12 being too hard. Therefore, in the molding process, the anti-corrosion layer 12 is easily broken or peeled off, thereby reducing its corrosion resistance.

[0079] In addition, the anti-corrosion layer 12 can also use a variety of existing anti-corrosion liquids, which contain phosphates, nitric acid, chromates, fluorides and rare earth oxides, etc. Among them, when phosphates or chromates are used, it is necessary to perform, for example, chromium chromate treatment, chromium phosphate treatment, phosphate-chromate treatment or chromate treatment, and the chromium compound used for treatment is, for example, chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium heavy phosphate, chromium acetate, chromium chloride or chromium sulfate. At the same time, in the chromate treatment method, it is mainly etching chromate treatment, electrolytic chromate treatment or coating chromate treatment, etc. Preferably, coating chromate treatment is preferred.

[0080] The coating type chromate treatment further includes a degreasing treatment, which uses a treatment liquid composed of at least one of a phosphate metal salt or a phosphate non-metal salt such as a chromium (Cr) phosphate salt, a titanium (Ti) phosphate salt, a zirconium (Zr) phosphate salt, a metalloid lead (Zn) phosphate salt, etc. as a main component, which can also be mixed with a synthetic resin as a treatment liquid, such as a water-soluble polymer such as an aminophenol or a polyacrylic acid resin, and is applied and dried by a well-known coating method such as a roller coating method, a gravure printing method, a dipping method, etc., wherein the treatment liquid can use various solvents such as water, an alcohol solvent, a hydrocarbon solvent, a ketone solvent, an ester compound solvent or an ether solvent, preferably water.

[0081] In one embodiment, the anti-corrosion layer 12 can be a thin film obtained by a coating-type anti-corrosion treatment, wherein the coating-type anti-corrosion treatment can be selected from at least one component of an oxide sol including rare earth elements, an anionic polymer or a cationic polymer, but is not limited thereto.

[0082] When a cationic polymer is used, it includes at least one component of polyethylene imine, a complex ion polymer complex formed by a polymer having polyethylene imine and a carboxylic acid, a primary amine Graf To acrylic resin grafted with a primary amine on an acrylic main chain, polyacetic acid or its derivatives or aminophenol, but is not limited thereto.

[0083] When an anionic polymer is used, it includes at least one component of a copolymer with poly(meth)acrylic acid or its salt, or (meth)acrylic acid and its salt as the main component, but is not limited thereto.

[0084] In one embodiment, the coating agent may include at least one combination of phosphoric acid, phosphate or bridging agent. When rare earth element oxide sol is used, rare earth element oxide particles, such as particles with an average particle size of less than 100 nm, are dispersed in a liquid dispersion medium, and the liquid dispersion medium is, for example, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester compound solvents or ether solvents, preferably water. When rare earth element oxides are used, they include at least one combination of cerium oxide, yttrium oxide, neodymium oxide or lanthanum oxide, preferably cerium oxide. In the anti-corrosion layer 12, the rare earth element oxides contained therein can be used alone or in combination, but are not limited thereto.

[0085] In one embodiment, the anti-corrosion liquid is coated on at least one side of the surface of the metal layer 11 to form an anti-corrosion layer 12, but it is not limited to this. More preferably, the anti-corrosion layer 12 can be formed on both sides of the surface of the metal layer 11. The function of the anti-corrosion layer 12 is to prevent the hydrogen fluoride generated by the reaction of the electrolyte and water from corroding the surface of the metal layer 11. At the same time, the uniformity of the surface of the metal layer 11 is maintained so that the adhesion, that is, the wettability, changes little. For this reason, the anti-corrosion layer 12 can enable the metal layer 11 to be preserved for a long time in a high temperature and high humidity environment. For this reason, the thickness of the anti-corrosion layer 12 is not particularly limited. In one embodiment, the thickness of the anti-corrosion layer 12 is 1nm-3.0μm, and the preferred thickness is 1nm-1.5μm, but it is not limited to this.

[0086] Furthermore, the metal-plastic composite film 1 of the present invention further includes a first resin layer 13 and a second resin layer 14, the first resin layer 13 is arranged on one side of the metal layer 11, and the second resin layer 14 is arranged on the other side of the metal layer 11. In one embodiment, the first resin layer 13 is bonded to one side of the metal layer 11 with a first adhesive 131, but not limited thereto, or the first adhesive 131 may not be used, and at the same time, the second resin layer 14 may also be bonded to the other side of the metal layer 11 with a second adhesive 141, or the second adhesive 141 may not be used, wherein the first resin layer 13 is mainly heat-weldable, and the material of the first resin layer 13 is composed of at least one of polyolefin, cyclic polyolefin or acid-modified polyolefin, but not limited thereto.

[0087] The polyolefin material can be at least one of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, etc. polyethylene ethylene-α-olefin copolymers, homopolypropylene, polypropylene block copolymers (such as block copolymers of propylene and ethylene), random copolymers of polypropylene (such as random copolymers of propylene and ethylene), propylene-α-olefin copolymers or ethylene-butene-propylene terpolymers, among which polypropylene is preferred. When a copolymer is used, the polyolefin can be a block copolymer or a random copolymer, and these polyolefin materials can be used alone or in combination.

[0088] The acid-modified polyolefin may be composed of at least one of aliphatic carboxylic acid-modified polyolefin, carboxylic acid-modified cyclic polyolefin, methacrylic acid-modified polyolefin, acrylic acid-modified polyolefin, crotonic acid-modified polyolefin or imide-modified polyolefin, wherein the acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization with an acid component and polyolefin. For this purpose, the acid-modified polyolefin may also be formed by copolymerizing a polar molecule such as polyacrylic acid or methacrylic acid with the polyolefin. In addition, the acid component used in the acid modification may be a carboxylic acid, sulfonic acid or anhydride such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, etc. Preferably, acrylic acid, maleic acid or anhydride may be used, but not limited thereto.

[0089] In one embodiment, the first resin layer 13 further includes a lubricant, which has the effect of improving the moldability of the outer packaging material for lithium-ion batteries. The total type of the lubricant is not particularly limited and can be selected and used within a known range. Moreover, the lubricant can be used alone or in combination. Preferably, an amide-based lubricant can be used, but not limited thereto.

[0090] When a lubricant is present on the surface of the first resin layer 13, the content thereof is not particularly limited. From the viewpoint of improving the moldability of the electronic packaging material, the lubricant content is preferably 10 mg / m 2 -50mg / m 2 , preferably 15mg / m 2 -40mg / m2, at the same time, the lubricant can seep out from the resin of the heat-welding resin layer and can also be coated on the surface of the first resin layer 13.

[0091] In one embodiment, the first resin layer 13 further includes an antioxidant, which can inhibit thermal degradation during the manufacturing process. The type of the antioxidant is not particularly limited and can be selected within a known range. Furthermore, the antioxidant can be used alone or in combination.

[0092] In one embodiment, the first resin layer 13 functions as a heat-fusible resin layer when assembling the battery, and seals the battery assembly by heat welding. The first resin layer 13 can be composed of a single resin or multiple resins, and the first resin layer 13 can be composed of a single layer or multiple layers of resins. Furthermore, it can be composed of the same or different resins.

[0093] In one embodiment, the thickness of the first resin layer 13 needs to satisfy the function of sealing the battery assembly after the first resin layer 13 is heat-welded. To this end, its thickness ranges from 20μm to 120μm, and the preferred thickness range is 25μm to 80μm. If the thickness of the first resin layer 13 is less than 20μm, it will not be able to fully cover the deviations of mechanical processing dimensions and conditions such as the heat sealing device, and it will be difficult to obtain a uniform heat-welded part, resulting in unstable sealing. On the contrary, if the thickness of the first resin layer 13 exceeds 120μm, the water vapor permeability will increase, resulting in an increase in moisture inside the battery, which reacts with the electrolyte to produce gas, so it is easy to cause the risk of expansion, rupture or leakage, and the battery life is reduced accordingly.

[0094] At the same time, the first resin layer 13 has a melting point range of 120°C-162°C, and preferably has a melting point range of 130°C-162°C, for example, MFR (230°C) is 2-15g / 10 minutes, more preferably MFR (230°C) is 3-12g / 10 minutes, and is a single layer or a composite layer composed of at least one mixture thereof, but not limited thereto.

[0095] In one embodiment, when the first resin layer 13 is a composite layer, the thickness of the side not in contact with the metal layer 11 is not less than 2 μm, and the melting point ranges from 130°C to 152°C. Therefore, when the melting point is below 120°C, heating will increase the fluidity of the resin, and when pressurized and heat-sealed, its thickness will become thinner, and the adhesion to the metal layer 11 will decrease. At the same time, pressurization will cause the resin to flow from the squeezed part inside the battery to the unsqueezed edge. At this time, the expansion and contraction of the battery and the external force of the bending process will cause cracks, so that the electrolyte will penetrate into the metal layer 11 through the cracks, causing the insulation resistance of the first resin layer 13 to decrease, and then leakage will occur, shortening the battery life.

[0096] On the contrary, when the melting point exceeds 162℃, the crystallinity of the resin increases, so that when the pressure is applied and heat-sealed, the resin fluidity becomes relatively low, and the heat resistance increases, forming a hard and brittle resin layer. Therefore, the expansion and contraction of the battery and the external force of the bending process will cause cracks, and stable sealing cannot be obtained. Similarly, when the MFR (230℃) is lower than 2g / 10 minutes or when the MFR (230℃) of the resin exceeds 15g / 10 minutes, the same problem will occur. In addition, the pressure causes the squeezed part of the resin inside the battery to flow to the edge part that is not squeezed. The expansion and contraction of the battery and the external force of the bending process cause cracks. The electrolyte will penetrate into the middle metal layer through the cracks, causing the insulation resistance of the heat-welded resin layer to decrease, leakage occurs, and the battery life will be shortened.

[0097] The first adhesive 131 mainly functions to bond the metal layer 11 and the first resin layer 13. To this end, the thickness of the first adhesive 131 only needs to have the function of serving as an adhesive layer, and the thickness ranges from 1 μm to 80 μm, and the preferred thickness range is about 1 μm to 50 μm. In one embodiment, the material of the first adhesive 131 is a resin, and the resin may or may not contain a polyolefin backbone chain, preferably a polyolefin backbone chain, wherein the polyolefin and its modified resin used in the first adhesive 131 are the same as the resin used in the first resin layer 13, which is a polypropylene resin, a propylene or ethylene copolymer, but not limited thereto.

[0098] In one embodiment, the first adhesive 131 may be a resin combination containing an acid-modified polyolefin and a curing agent. When an acid-modified polyolefin is used, it is preferably a polyolefin modified with maleic anhydride or acrylic acid, and the curing agent used is only required to cure the acid-modified polyolefin, and there is no particular limitation. Preferably, a curing agent of at least one combination of an epoxy curing agent, a multifunctional isocyanate curing agent, a carbodiimide curing agent or an oxazoline curing agent can be used, but it is not limited thereto.

[0099] When the curing agent is an epoxy curing agent, it can be a compound having at least one epoxy group, such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerol polyglycidyl ether or polyglycerol polyglycidyl ether. When the curing agent is a multifunctional isocyanate curing agent, it only needs to be a compound having at least two isocyanate groups, such as isophorone diisocyanate (PDI), hexamethylene diisocyanate (HDI), toluene diisocyanate ( The invention relates to a polymerized or added component of the above substances such as TDI) and diphenylmethane diisocyanate (MDI), or a reactant of such a mixture with other polymers; when a carbodiimide curing agent is used as a curing agent, it only needs to have a compound with at least one carbodiimide group (-N=C=N-), such as a polycarbodiimide compound with at least two or more carbodiimide groups; and when an oxazoline curing agent is used as a curing agent, it only needs to have a compound with an oxazoline skeleton. Of course, the curing agent can also be composed of two or more compounds.

[0100] In one embodiment, the material of the first adhesive 131 is a mixture of at least one of modified polyolefin resin, polyolefin resin, block copolymer polypropylene resin (B-PP) with a polypropylene (PP) content exceeding 50%, random copolymer polypropylene resin (R-PP) or homopolymer polypropylene resin (H-PP), and the structure is single-layer or multi-layer, but not limited thereto.

[0101] When the first adhesive 131 is used to compound the metal layer 11 and the first resin layer 13, a solution-type first adhesive 131 method or a hot-melt-type first adhesive 131 method can be used, wherein the solution-type first adhesive 131 is based on an acid-modified polyolefin resin, and uses at least one combination of isocyanate, epoxy resin or oxazoline as a hardener, or an amine compound such as triethylamine, N,N-dimethylethanolamine as a hardener, and is dissolved in at least one combination of water, ethanol, isopropanol, ethyl acetate, methyl ethyl ketone, toluene, and methylcyclohexane, and then evenly coated on the surface of the metal layer 11, and heated to volatilize the solvent, so that the thickness of the first adhesive 131 reaches the desired effect, preferably about 1-10μm, and more preferably 1-5μm.

[0102] When the thickness of the first adhesive 131 is less than 1 μm, the bonding force between the metal layer 11 and the first resin layer 13 will be reduced, making the bonding property a problem. When the thickness of the first adhesive 131 exceeds 10 μm, a hard resin layer will be formed under the reaction of the curing agent. At this time, the bending resistance will deteriorate, the flexibility of the metal-plastic composite film 1 will be reduced, and there is a risk of cracks due to bending.

[0103] The melting point of the acid-modified polyolefin resin in the solution-type first adhesive 131 is 60°C-155°C, the weight-average molecular weight is in the range of 10000-150000, and the acid value of the solution-type first adhesive 131 is in the range of 0.5-200 mgKOH / g. In the absence of a curing agent, the solution-type first adhesive 131 is mainly composed of acid-modified polyolefin and amine compounds as hardeners, wherein the ratio of acid-modified polyolefin to amine compound is 10-125:1, preferably 15-50:1, and the acid used to modify the polyolefin is maleic acid, fumaric acid, methacrylic acid, etc., the amine compound is at least one combination of triethylamine or N, N-2 methylethanolamine, the acid-modified polyolefin is polypropylene with a melting point above 110°C, and the content of polypropylene is above 50%.

[0104] When the melting point of the acid-modified polyolefin is below 60°C, its heat resistance is low. At this time, the metal layer 11 and the first resin layer 13 may peel off at high temperatures. In addition, when the melting point of the acid-modified polyolefin exceeds 155°C, its heat resistance is relatively good, but when it reacts with the curing agent, a hard resin layer is formed, which has poor bending properties. Therefore, the flexibility of the metal-plastic composite film 1 decreases, or cracks are generated when bent, and the metal layer 11 and the first resin layer 13 may peel off.

[0105] When the weight average molecular weight of the acid-modified polyolefin resin is below 10,000, the resin has high fluidity when heated, and during heat sealing, the thickness of the first adhesive 131 will be seriously thinned, and the adhesion strength between the metal layer 11 and the first resin layer 13 will be reduced when a curing agent is added to react, resulting in sealing problems. Conversely, when the weight average molecular weight of the acid-modified polyolefin resin exceeds 150,000, the metal layer 11 and the first resin layer 13 will form a hard resin layer when a curing agent is added to react, and the bending resistance will be poor, thereby reducing the flexibility of the metal-plastic composite film 1, or cracks will be generated when bent, and the metal layer 11 and the first resin layer 13 may be peeled off.

[0106] When the acid value of the acid-modified polyolefin resin is less than 0.5 mgKOH / g, the curing reaction points between the acid-modified polyolefin resin and the curing agent are small. At this time, the adhesion between the metal layer 11 and the first resin layer 13 is unstable. When the acid value of the acid-modified polyolefin resin exceeds 200 mgKOH / g, the curing reaction between the curing agent and the acid-modified polyolefin resin is too intense, forming a hard resin layer, and the bending resistance is deteriorated, so that the flexibility of the metal-plastic composite film 1 decreases, or cracks are generated when bending, and the metal layer 11 and the first resin layer 13 may be peeled off.

[0107] The resin used in the hot-melt first adhesive 131 is an acid-modified polyolefin resin with a melting point of 135-165°C and an MFR (230°C) of 3-15g / 10 minutes. The thickness of the formed first adhesive 131 is 2-80μm, preferably 5-50μm. The modification degree of the acid-modified polyolefin resin used in the hot-melt first adhesive 131 is 1%-15%, preferably 3%-12%. When the melting point of the acid-modified polyolefin resin is below 135°C, heating will cause the resin fluidity to increase. When pressurized heat sealing is performed, the thickness will become seriously thinner, the adhesion strength between the metal layer 11 and the first resin layer 13 will become low, and there will be sealing problems.

[0108] When the melting point of the acid-modified polyolefin resin is above 165°C, the fluidity during pressurized heat sealing is relatively low, and the heat resistance is improved. However, when compounded with the metal layer 11, the amount of heat shrinkage increases, which increases the internal stress and reduces the adhesion between the hot-melt type first adhesive 131 and the metal layer 11. Therefore, if it is left for a long time, it may peel off from the metal layer 11. In addition, due to the heating during heat sealing, further heat shrinkage will occur, the adhesion between the metal layer 11 will decrease, and the sealing strength will decrease. If the MFR (230°C) of the acid-modified polyolefin resin is lower than 3g / 10 minutes, when it is extruded onto the metal layer 11 for compounding after hot melting, the extrusion film forming property is unstable. On the contrary, if the MFR (230°C) of the acid-modified polyolefin resin is higher than 15g / 10 minutes, heating will cause the resin fluidity to increase, and the thickness will become seriously thinner during pressurized heat sealing. The adhesion strength between the metal layer 11 and the first resin layer 13 will decrease, and there will be sealing problems.

[0109] Furthermore, when the thickness of the hot-melt type first adhesive 131 is less than 2 μm, when compounded with the metal layer 11, the heat shrinkage is too much and therefore cannot be absorbed. Therefore, due to the increase in internal stress, the adhesion with the metal layer 11 is reduced. Therefore, if left for a long time, it may peel off from the metal layer 11. Moreover, when the thickness of the hot-melt type first adhesive 131 exceeds 80 μm, there will be no physical property problems, but it will lead to an increase in production prices. When the modification degree of the hot-melt type first adhesive 131 is less than 1%, the adhesion with the metal layer 11 will be unstable. If the modification degree of the hot-melt type first adhesive 131 exceeds 15%, although there will be no physical property problems, it will also lead to an increase in production prices.

[0110] The second resin layer 14 is a base material for lithium-ion battery packaging material, and is limited to having at least insulation properties. Therefore, there is no particular limitation on the thickness of the second resin layer 14 as long as it can function as a base material. In one embodiment, the resin of the second resin layer 14 is, for example, polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, phenolic resin, or a modified product of these resins. At the same time, the resin forming the second resin layer 14 can be a copolymer of these resins, a modified product of the copolymer, or a modified product of these resins. A mixture of some resins, preferably at least one of polyester or polyamide, preferably containing at least one of stretched polyester film, stretched polyamide film and stretched polyolefin film, preferably containing at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film and stretched polypropylene film, preferably containing at least one of biaxially stretched polyethylene terephthalate film, biaxially stretched polybutylene terephthalate film, biaxially stretched nylon film and biaxially stretched polypropylene film, and the second resin layer 14 can be a single layer or a multilayer, but is not limited thereto.

[0111] When the second resin layer 14 is composed of multiple layers, the second resin layer 14 can be a composite film formed by the action of the second adhesive 141, or a multi-layer resin composite film formed by co-extruding resins, or a multi-layer resin composite film formed by co-extruded resins and used as the second resin layer 14 in an unstretched state, or after uniaxial stretching or biaxial stretching. When the second resin layer 14 is a multi-layer resin composite film, the thickness of the resin films constituting each layer is preferably in the range of 2μm-30μm, and the total thickness of the second resin layer 14 is in the range of 5μm-35μm. When the thickness is less than 5μm, the formability and insulation properties are relatively poor. On the contrary, if it exceeds 35μm, the softness will deteriorate.

[0112] In one embodiment, the second resin layer 14 may be a single-layer or multi-layer composite film formed by at least one of the following polymer materials: blown nylon, synchronous or asynchronous biaxially oriented nylon, synchronous or asynchronous biaxially oriented polyethylene terephthalate (PET), synchronous or asynchronous biaxially oriented polybutylene terephthalate (PBT), polyimide (PI), etc., and may be bonded to the metal layer 11 by at least one combination of coextrusion, coating, compounding and heat bonding, but is not limited thereto.

[0113] Among them, the multi-layer resin composite film is a composite film of a polyester film and a nylon film, a multi-layer nylon composite film, and at least one combination of a multi-layer polyester composite film, preferably a stretched nylon film and a stretched polyester film laminate, a multi-layer stretched nylon composite film, and a multi-layer stretched polyester composite film. When the outer substrate resin layer is a multi-layer resin composite film, it is preferably a composite film of a polyester resin film and a polyester resin film, a composite film of a polyamide resin film and a polyamide resin film, or a composite film of a polyester resin film and a polyamide resin film. Preferably, it is preferably a polyethylene terephthalate film and a polyethylene terephthalate film. A composite film of ethylene glycol film, a composite film of polybutylene terephthalate film and polybutylene terephthalate film, a composite film of nylon film and nylon film, or a composite film of polyethylene terephthalate film and nylon film. In addition, since polyester resin is difficult to change color when the electrolyte adheres to the surface, when the second resin layer 14 is a multi-layer resin composite film, it is preferred that the polyester resin film is used as the outermost layer of the second resin layer 14, wherein the multi-layer resin film can also be composited by an adhesive, and the preferred adhesive can use an adhesive with the same composition as the second adhesive 141.

[0114] In one embodiment, the polyester used in the second resin layer 14 can be at least one combination of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate or copolyesters, wherein the copolyester can be a copolyester with ethylene terephthalate as the main body of the repeating unit, specifically, a copolymer polyester formed by polymerizing ethylene terephthalate as the main body of the repeating unit with ethylene isophthalate, that is, copolyester (terephthalate / isophthalate), copolyester (terephthalate / adipate), copolyester (terephthalate / sodium isophthalate), copolyester (terephthalate / phenyl-dicarboxylate), copolyester (terephthalate / decane dicarboxylate), these polyesters can be used alone or in combination of multiple types, but are not limited to this.

[0115] In one embodiment, the polyamide used in the second resin layer 14 can be at least one combination of aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, nylon 6 and nylon 66 copolymers, hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, t represents terephthalic acid) containing structural units from terephthalic acid and / or isophthalic acid, and aromatic polyamides such as polyamide MXD6 (polyamide PACM6 (polybis(4-aminocyclohexyl)methane azideamide)). These polyamides can be used alone or in combination of multiple types, but are not limited to this.

[0116] In one embodiment, one or more additives such as lubricants, flame retardants, anti-adhesive agents, antioxidants, light stabilizers, tackifiers, antistatic agents, etc. can be added to the surface and interior of the second resin layer 14. For example, a lubricant is coated on the surface of the second resin layer 14, preferably an amide lubricant, and the coating content of the lubricant is not less than 3 mg / m2, preferably in the range of 4-30 mg / m2. In addition, the lubricant present on the surface of the second resin layer 14 can be a lubricant that seeps out of the second resin layer 14 containing the lubricant, or a lubricant coated on the surface of the second resin layer 14. Among them, the amide lubricant includes at least one combination of saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, hydroxymethyl amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid amides and aromatic bisamides, but is not limited thereto.

[0117] In one embodiment, when the lubricant uses saturated fatty acid amide, it includes at least one combination of lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; when the lubricant uses unsaturated fatty acid amide, it includes oleic acid amide, erucic acid amide, etc. The substituted amide includes at least one combination of N-oleopalmitic acid amide, N-stearic acid amide, N-stearic acid amide, N-oleostearic acid amide, and N-stearic acid amide; when the lubricant uses hydroxymethylamide, it includes at least one combination of hydroxymethylstearic acid amide; when the lubricant uses saturated fatty acid bisamide, it includes methylene bisstearic acid amide, ethylene bisoctanoic acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic 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. The unsaturated fatty acid bisamides include at least one combination of ethylene bisoleamide, ethylene biserucamide, hexamethylene bisoleamide, n,n'-dioleyl adipic acid amide and n,n'-dioleyl sebacic acid amide; when the lubricant uses fatty acid ester amides, it includes at least one combination of stearylamide ethyl stearate; and when the lubricant uses aromatic bisamides, it includes at least any one combination of isophthalic acid bisstearamide, isophthalic acid bishydroxystearamide, and n,n'-distearyl isophthalic acid amide, but is not limited thereto.

[0118] There are many methods for making the second resin layer 14, such as directly forming a resin film from resin, or coating the resin, wherein the resin film is an unstretched film or a stretched film, and the stretched film is a uniaxial stretched film or a biaxial stretched film, preferably a biaxial stretched film, and as a method for making a biaxial stretched film, for example, a step-by-step biaxial stretching method, a blown film method or a synchronous stretching method, and a method for coating the resin, for example, a roller coating method, a micro-concave coating method or an extrusion coating method, etc., but not limited to these.

[0119] The function of the second adhesive 141 is to improve the adhesion between the second resin layer 14 and the metal layer 11. To this end, the thickness of the second adhesive 141 ranges from 1μm to 10μm, preferably from 2μm to 5μm, and the second adhesive 141 is, for example, a two-component curing adhesive, or a single-component curing adhesive, wherein the second adhesive 141 may be at least any combination of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressing type, etc., and the second adhesive 141 may be a single layer or a multi-layer, but is not limited thereto.

[0120] In one embodiment, the second adhesive 141 is a two-component polyurethane adhesive formed by using polyester polyol and polyurethane modified polyol as diol main agent and aromatic or aliphatic isocyanate as curing agent, wherein the curing agent can be selected according to the functional groups of the adhesive components, such as at least any one of multifunctional epoxy resin, polymer containing methanesulfonic acid, polyamide resin and inorganic acid, but not limited thereto.

[0121] In one embodiment, the second adhesive 141 further includes polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, copolymerized polyesters, polyether resins, polyurethane resins, epoxy resins, phenolic resins, nylon 6, nylon 66, nylon 12, copolymerized polyamides, polyamide resins, polyolefins, cyclic polyolefins, acid-modified polyolefins, acid-modified cyclic polyolefins, polyolefin-based resins, polyvinyl acetate, cellulose, (meth)acrylic resins, polyimide resins, polycarbonates, urea resins, amino resins such as melamine resins, At least any combination of chloroprene rubber, nitrile rubber, styrene-butadiene rubber and other rubbers, silicone resins, etc., but not limited thereto. The preferred second adhesive 141 combination is any combination of binary or multi-component polyesters, polyurethane-modified polyesters or isocyanates, and the isocyanate is not particularly defined as a compound having multiple isocyanate groups in the molecule, for example, at least any mixture of polymers such as isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HDI).

[0122] In addition, the second adhesive 141 may further include at least one of a colorant, a thermoplastic elastomer, a tackifier or a filler. The second adhesive 141 contains a colorant, so that the lithium ion battery packaging material can be colored. When the colorant is used, at least one combination of a pigment and a dye can be used. When the pigment is an organic pigment, for example, at least one of an azo series, a phthalocyanine series, a quinacridone series, an anthraquinone series, a dioxazine series, an indigothioindigo series, a perylene series, and an isoindoline series can be used. If it is an inorganic pigment, for example, at least one of a carbon black series, a titanium oxide series, a cadmium series, a lead series, and an isoindoline series can be used. The average particle size range of the pigment is 0.05μm-5μm, and the preferred average particle size range is 0.08μm-2μm. At the same time, since the lithium ion battery packaging material only needs to be colored, the pigment content ranges from 5% to 60%, and preferably from 10% to 40%.

[0123] In one embodiment, a coloring layer 15 may be further provided between the second resin layer 14 and the second adhesive 141, for example, by coating ink containing a coloring agent on the surface of the second resin layer 14, the surface of the second adhesive 141 or the surface of the metal layer 11, and the coloring agent used in the coloring layer 15 is the same as that mentioned above, so it will not be repeated.

[0124] See also Figure 3 , which is a flow chart of a method for preparing a metal-plastic composite film according to an embodiment of the present invention. As shown in the figure, the method for forming a corrosion-resistant metal-plastic composite film according to the present invention comprises the following steps:

[0125] Step S1: Mixing a trivalent chromium compound, an inorganic acid, and an organic resin with water or an organic solvent to form an anti-corrosion liquid;

[0126] Step S2: coating the anti-corrosion liquid on at least one side of a metal layer surface, and generating an anti-corrosion layer on at least one side of the metal layer surface through heat treatment to form a metal-plastic composite film, wherein the anti-corrosion layer comprises a carbon element, a metal element and a fluorine element; and

[0127] Step S3: Disposing a first resin layer on one side of the corrosion layer of the anti-metal-plastic composite film.

[0128] As shown in step S1, a trivalent chromium compound, an inorganic acid, an organic resin, and water or an organic solvent are mixed to form an anti-corrosion liquid. In one embodiment, a bridging agent may be added. The examples of the trivalent chromium compound, the inorganic acid, the organic resin, the water or the organic solvent, and the bridging agent are the same as those described above, and thus will not be described in detail herein.

[0129] As shown in step S2, an anti-corrosion liquid is applied to at least one side of the surface of the metal layer 11, and an anti-corrosion layer 12 is generated on at least one side of the surface of the metal layer 11 through heat treatment to form a metal-plastic composite film 1, and the anti-corrosion layer 12 contains carbon elements, metal elements and fluorine elements. The anti-corrosion liquid coating method can adopt an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an oxygen activation method, a heat treatment (annealing treatment) during rolling, and the like.

[0130] Before applying the anticorrosion liquid, the metal layer 11 needs to be deoiled on the coating side. The surface wettability of the metal layer 11 is 65 dyn / cm, preferably not less than 70 dyn / cm, or the contact angle of distilled water is not more than 15 degrees, preferably not more than 10 degrees. If the wettability of the metal layer 11 or the surface water contact angle exceeds the given range, it means that the rolling oil in the manufacturing stage may still remain on the metal, so that the interface formed between the anticorrosion layer 12, the metal layer 11 and the first resin layer 13 is attached. The battery capacity is deteriorated, and when the battery is placed for a long time, there is a risk of the metal layer 11 and the first resin layer 13 falling off, and the battery leakage is likely to occur. As a preventive measure, it can be annealed at not less than 150°C. At the same time, it can be deoiled by plasma, corona method, and alkali solution. Among them, the alkali deoiling method is to immerse the metal layer 11 in alkali solution at 50°C-65°C. After a certain period of treatment, it is washed twice with deionized water and then dried to obtain the deoiled metal layer 11, but not limited to this.

[0131] After the metal layer 11 is deoiled, the anti-corrosion liquid can be applied by rod coating, roller coating, gravure coating, dipping, etc. The coating wet film amount of the anti-corrosion liquid on the metal layer 11 is in the range of 1.6-3.2 g / m 2 After the anti-corrosion liquid is applied, heat treatment is performed at a high temperature of 130°C-200°C for 0.5 minutes to 5 minutes to form an anti-corrosion layer 12. In one embodiment, metal oxides such as aluminum oxide, titanium oxide, cerium oxide, tin oxide, etc. dispersed in phosphoric acid and particulate matter of precipitated barium sulfate can be applied to the surface of the metal layer 11 and sintered at not less than 150°C to form the anti-corrosion layer 12, but this is not limited to this.

[0132] As shown in step S3, the first resin layer 13 is disposed on one side of the anticorrosion layer 12 of the metal-plastic composite film 1. In one embodiment, the first resin layer 13 is bonded to one side of the anticorrosion layer 12 by a first adhesive 131, but the present invention is not limited thereto. The first resin layer 13 may be laminated to the metal layer 11 by heating and pressurizing without using the first adhesive 131, and the first resin layer 13 may be laminated to the metal layer 11 by heating treatment, ultraviolet treatment or electron beam treatment, etc. to form a film, so as to obtain a composite film composed of the first resin layer 13 and the metal layer 11. Among them, if the first adhesive 131 is used for lamination, the lamination method can be roughly divided into the following four methods:

[0133] 1. Dry lamination method: A solution-type first adhesive 131 is coated on the metal layer 11, and a drying process is performed. After thermal lamination with the bonding surface of the first resin layer 13 at a certain temperature and pressure, a aging treatment is performed to form a composite of the metal layer 11 / first adhesive 131 / first resin layer 13. Preferably, the bonding surface of the first resin layer 13 in contact with the first adhesive 131 is pre-corona treated. In addition, an aging treatment at a temperature not exceeding 60°C of the melting point of the first adhesive 131 can be performed.

[0134] 2. Melt extrusion method: The hot-melt first adhesive 131 is formed on the metal layer 11 by melt extrusion of the resin to form a hot-melt first adhesive 13 of a certain thickness, and the surface of the first adhesive 131 and the bonding surface of the first resin layer 13 are thermally compounded to form a composite of the metal layer 11 / the first adhesive 131 / the first resin layer 13. In addition, in order to increase the peeling force between the metal layer 11 and the first resin layer 13, a heat treatment of not more than 60°C of the melting point of the first adhesive 131 can be performed.

[0135] 3. Melt extrusion method: The hot melt type first adhesive 131 and the first resin layer 13 are co-extruded to form a composite of the metal layer 11 / first adhesive 131 / first resin layer 13. In addition, in order to increase the peeling force between the metal layer 11 and the first resin layer 13, a heat treatment of not more than 60°C of the melting point of the first adhesive 131 can be performed.

[0136] 4. Thermal bonding method: The first adhesive 131 of aqueous solution type is coated on the metal layer 11, and a drying procedure is performed, and then thermally compounded with the bonding surface of the first resin layer 13 at a certain temperature and pressure to form a composite of the metal layer 11 / first adhesive 131 / first resin layer 13. In addition, in order to improve the peeling force between the metal layer 11 and the first resin layer 13, a heat treatment of not more than 60°C of the melting point of the first adhesive 131 can be performed, wherein the first resin layer 13 can also be formed by extrusion, or a film can be used. When a film is used, preferably, the bonding surface of the first resin layer 13 in contact with the first adhesive 131 is pre-corona treated.

[0137] In one embodiment, it further comprises:

[0138] Step S4: Dispose a second resin layer on the other side of the metal-plastic composite film, and the second resin layer is opposite to the first resin layer.

[0139] As shown in step S4, the second resin layer 14 is disposed on the other side of the metal layer 11, and the side is opposite to the first resin layer 131. In one embodiment, a second adhesive 141 can be coated between the metal layer 11 and the second resin layer 14 and heated at a certain temperature for a certain time, so that the organic solvent evaporates, and then the second resin layer 14 is further compounded with the metal layer 11 according to the second adhesive 141 at a certain temperature and pressure, and after being stored at a certain temperature for a certain time, the second resin layer 14 undergoes a curing reaction to obtain a composite film composed of the second resin layer 14 / the second adhesive 141 / the metal layer 11. When the second resin layer 14 and the metal layer 11 are compounded without using the second adhesive 141, the metal layer 11 and the second resin layer 14 are compounded by heating and pressurizing, and the second resin layer 14 is filmized by heating treatment, ultraviolet treatment or electron beam treatment, so that a composite film composed of the second resin layer 14 and the metal layer 11 can be obtained, but it is not limited thereto.

[0140] In one embodiment, the second resin layer 14 film in contact with the second adhesive 141 can be corona treated. Specifically, a non-crystalline polyester polyol with a weight average molecular weight of 5000, Tg of 50°C, and a hydroxyl value of 25 mg KOH / g and a non-crystalline polyester polyol with a weight average molecular weight of 20000, Tg of -17°C, and a hydroxyl value of 8 mg KOH / g are mixed in a weight ratio of 3:2, and toluene diisocyanate (TDI) is added to form an outer layer adhesive liquid with an NCO / OH ratio of 6.2, which is coated on the metal layer 11, and the second adhesive 141 on the metal layer 11 is thermally compounded with the second resin layer 14 film, and then aged at 80°C for 3 days to form the second resin layer 14 / second adhesive 141 (3 μm) / metal layer 11, wherein the metal layer 11 can be subjected to anti-corrosion treatment on both sides of the surface.

[0141] The peel strength test between the metal layer 11 and the first resin layer 13 of the metal-plastic composite film 1 is as follows:

[0142] Initial peel strength test: The metal-plastic composite film 1 is prepared into a straight strip with a strip size of 100 mm*15 mm. A tensile test device is used to perform a peel test between the metal layer 11 and the first resin layer 13. The peeled first resin layer 13 film is placed on the upper clamping plate of the telescopic test device, and the metal layer 11 is placed on the lower clamping plate. When the telescopic speed is 50 mm / min, a T-shaped peeling with a peeling surface of 180° is performed to start measuring the peel strength between the metal layer 11 and the first resin layer 13. The peel strength is read in a manner that the moving distance between the metal layer 11 and the first resin layer 13 is 50 mm, and the average value of the peel strength between the moving distance of 10 mm and 40 mm is selected, and 5 pieces / group are tested in parallel.

[0143] The anhydrous electrolyte resistance test of the metal-plastic composite film 1 is as follows:

[0144] The metal-plastic composite film 1 sample is directly immersed in a mixed solvent of dimethyl carbonate (DMC): diethyl carbonate (DEC): ethylene carbonate (EC) with a molar ratio of 1:1:1 containing 1 mol / L LiPF6, and immersed at 85°C for 3 days. After being taken out, it is washed with water for 15 minutes, the moisture on the surface of the sample is wiped off, and the peel strength between the metal layer 11 and the first resin layer 13 is measured according to the initial peel strength test method of the finished product.

[0145] The aqueous electrolyte resistance test of the metal-plastic composite film 1 is as follows:

[0146] The metal-plastic composite film 1 is cut into strips with a width of 15 mm and a length of 100 mm. After 20 mm of the metal layer 11 and the first resin layer 13 are peeled off, the strips are immersed in a solvent containing 1 mol / L LiPF6 and a ratio of dimethyl carbonate (DMC): diethyl carbonate (DEC): ethylene carbonate (EC) of 1:1:1. Then, 1000 PPM of water accounting for the total mass of the electrolyte is added. After being immersed at a temperature of 85° C. for 3 days, the strips are taken out and washed with water for 15 minutes without wiping off the water. In the state where there is residual water between the pre-peeled metal layer 11 and the first resin layer 13, the peel strength between the intermediate metal layer 11 and the first resin layer 13 is measured from the pre-peeled position according to the initial peel strength test method of the finished product.

[0147] The determination method is as follows:

[0148] 1. Water contact angle measurement

[0149] Use the German KRUSSDSA25 contact angle meter to measure the water contact angle of the metal surface. Place the metal flat on the instrument workbench, control the water output of the syringe at 2μml each time, and the liquid addition speed at 2.67μmL / s. Record the contact angle value when the water drop just falls on the metal surface.

[0150] 2. Determination of dyne value

[0151] Use the German Arcotest dyne pen to draw two 10 cm long straight lines on the metal surface. If the straight lines shrink by more than 10% within 3 seconds, it means that the dyne value of the metal surface does not reach the dyne value of the dyne pen at this time. Select a dyne pen with a lower dyne value for re-measurement.

[0152] 3. Determination of 12 elements in the anti-corrosion layer

[0153] XPS (Axis supra, Shimadzu, UK) was used to measure the element distribution of the anti-corrosion layer 12 by the ESCA method. The metal surface of the sample was sputtered by Ar ions, the ion beam diameter was 800 μm, the voltage was 15 KV, the ion beam sputtering depth was 5 nm, the sputtering rate was 3 nm / min, the number of sputterings was 7 times, the signal source detection depth was 5 nm, the detection limit was 1‰, and the number of detections was 8 times.

[0154] Among them, the method for making liquid-resistant samples is as follows: the metal forming the anti-corrosion layer 12 is cut into strips with a width of 20 mm and a length of 100 mm, and the strips are immersed in a solvent containing 1 mol / L LiPF6 in a ratio of 1:1:1 of dimethyl carbonate (DMC): diethyl carbonate (DEC): ethylene carbonate (EC), and then 1000 PPM of water accounting for the total mass of the electrolyte is added, and the strips are immersed at a temperature of 85°C for 3 days, then taken out, washed with water for 15 minutes, and the moisture is wiped off.

[0155] In both Examples 1-2 and Comparative Example 1, the anti-corrosion liquid was evenly coated on both sides of the surface of the metal layer 11 by a coating roller, and then heat-dried at 190°C for 2 minutes. The wet film coating amount of the anti-corrosion layer 12 treatment liquid was 5g / m2.

[0156] The last method is to compound the first adhesive 131 and the first resin layer 13 on the metal surface of the semi-finished product: the second resin layer 14 / the second adhesive 141 (3 μm) / the metal layer 11 .

[0157] Molten type first adhesive 131 compounding method:

[0158] The melt-type resin used in the first adhesive 131 is anhydrous maleic anhydride modified polypropylene, and an adhesive layer with a thickness of 15 μm is formed on the metal layer 11 in contact with the first resin layer 13. Further, the adhesive layer is compounded with the first resin layer 13 with a thickness of 30 μm. The first adhesive 131 and the first resin layer 13 are compounded on the metal layer 11 in contact with the first resin layer 13 by melt coextrusion. The first adhesive 131 used is 60% (by weight) of anhydrous maleic anhydride modified random copolymer polypropylene with a melting point of 140°C and an MFR (230°C) of 5g / 10min. The modification degree of random copolymer polypropylene by anhydrous maleic anhydride is 10%, and the mixture consists of 24% (by weight) of a copolymer elastomer of propylene and butene with a melting point of 160°C, an MFR (230°C) of 2.6 g / 10 min and a density of 0.87 g / cm3, 8% (by weight) of a crystalline copolymer elastomer of ethylene and propylene with a melting point of 130°C, an MFR (230°C) of 9.5 g / 10 min and a density of 0.91 g / cm3, and 8% (by weight) of a low-density polyethylene with a melting point of 105°C and an MFR (230°C) of 12 g / 10 min.

[0159] The first resin layer 13 is composed of two layers, and its structure is as follows:

[0160] The first resin layer 13 in contact with the first adhesive 131: a mixture layer composed of 62% by weight of random copolymer polypropylene with a melting point of 155°C and an MFR (230°C) of 4 g / 10 min, 33% of a non-crystalline propylene elastomer and 5% of a low-density polyethylene with a melting point of 110°C and an MFR (230°C) of 7.5 g / 10 min; and

[0161] The innermost first resin layer 13 is composed of random copolymer polypropylene with a melting point of 155°C and an MFR (230°C) of 15g / 10min, wherein the thickness ratio of the first resin layer 13 in contact with the first adhesive 131 to the innermost first resin layer 13 is 8:2.

[0162] After the metal layer 11 is compounded with the first adhesive 131 and the first resin layer 13, heat treatment is performed at 180°C for 2 seconds. At this time, a composite film of second resin layer 14 / second adhesive 141 (3μm) / metal layer 11 / first adhesive 131 (15μm) / first resin layer 13 (30μm) is formed.

[0163] Another method is to compound the first adhesive 131 and the first resin layer 13 on the metal surface of the semi-finished product: the second resin layer 14 / the second adhesive 141 (3 μm) / the metal layer 11 .

[0164] Solution type first adhesive 131 compounding method:

[0165] Anhydrous maleic anhydride modified polypropylene solution with a weight average molecular weight of 80,000, a melting point of 80°C and an acid value of 2 mg KOH / g and an aromatic isocyanate (HDI series, hexamethylene diisocyanate) solution are coated on the metal surface 11 in a solid ratio of 20:1 to form a solution mixture, and after drying, a bonding layer with a thickness of 4 μm is formed. Thereafter, at a temperature of 80°C, it is thermally compounded with the bonding surface of the first resin layer 13 with a thickness of 25 μm, and aged at a temperature of 60°C for 7 days to form a composite film of second resin layer 14 / second adhesive 141 (3 μm) / metal layer 11 / first adhesive 131 / first resin layer 13 (25 μm). The bonding surface of the first resin layer 13 in contact with the first adhesive 131 will be pre-corona treated.

[0166] The first resin layer 13 is composed of three layers, and its structure is as follows:

[0167] The first resin layer 13 in contact with the first adhesive 131 is composed of random copolymer polypropylene with a melting point of 145° C. and an MFR (230° C.) of 7.5 g / 10 min.

[0168] The first resin layer 13 in the middle is composed of a mixture of 40% of a block copolymer polypropylene having a melting point of 162°C and an MFR (230°C) of 2 g / 10 min, 40% of a block copolymer polypropylene having a melting point of 160°C and an MFR (230°C) of 5 g / 10 min, and 20% of a crystalline polymer elastomer composed of ethylene-propylene having a melting point of 130°C, an MFR (230°C) of 9.5 g / 10 min, and a density of 0.91 g / cm3, by weight ratio; and

[0169] The innermost first resin layer 13 is composed of random copolymer polypropylene with a melting point of 145° C. and an MFR (230° C.) of 7.5 g / 10 min. The thickness ratio of the first resin layer 13 from the contact with the first adhesive 131 to the innermost layer is 1:8:1.

[0170] Example 1

[0171] The metal layer 11 is made of aluminum foil, the thickness of the metal layer 11 used is 40 μm, and the 8021 series annealed metal with a dyne value of 75 dyn / cm2 is used. Both sides of the surface of the metal layer 11 are treated with corrosion protection. The proportions of various elements in the corrosion protection layer 12 on both sides of the surface of the metal layer 11 are as shown in Table 1. The content ratio of chromium fluoride, hydrofluoric acid, polyvinyl alcohol resin, and titanium fluoride on the surface of the metal layer 11 is 15:1:3:2. The chromium (Cr) content of the metal layer 11 surface coating is 15 mg / m2. 2 , wherein the first adhesive 131 is compounded with the first resin layer 13 using a molten first adhesive 131 compounding method.

[0172] Example 2

[0173] The metal layer 11 is made of aluminum foil, the thickness of the metal layer 11 used is 40 μm, and the water contact angle is 10°. The two sides of the metal layer 11 are treated with corrosion protection. The proportions of various elements in the corrosion protection layer 12 on both sides of the metal layer 11 are as shown in Table 1. The content ratio of chromium phosphate and chromium fluoride, phosphoric acid, and phenolic resin on the surface of the metal layer 11 is 5:2:1, and the content of chromium (Cr) coated on the surface of the metal layer 11 is 12 mg / m 2 , wherein the first adhesive 131 is compounded with the first resin layer 13 using a molten first adhesive 131 compounding method.

[0174] Comparative Example 1

[0175] The metal layer 11 used has a thickness of 40 μm and is an 8021 annealed metal with a water contact angle of 15°. Both sides of the metal layer 11 are treated with anti-corrosion. The proportions of the elements in the anti-corrosion layer 12 on both sides of the metal layer 11 are as shown in Table 1. The content ratio of chromium fluoride, hydrofluoric acid, and polyvinyl alcohol resin in the obtained metal layer 11 is 2:1:5. The chromium (Cr) content of the metal layer 11 surface coating is 5 mg / m 2 , wherein the first adhesive 131 is compounded with the first resin layer 13 using a molten first adhesive 131 compounding method.

[0176] In Example 1-2, the initial peel strength of the metal-plastic composite film is above 10.0 N / 15 mm, and the peel strength maintenance rates after being placed in anhydrous and aqueous electrolyte environments for 5 days reach 88.0% and 70.0%, respectively.

[0177] In the first anti-corrosion zone, the carbon element content is 67% and the metal element content is 2.0%; in the second anti-corrosion zone, i.e., 20nm from the anti-corrosion layer 12 to the metal layer 11 side, the metal element content is 8%; in the third anti-corrosion zone, i.e., 40nm from the anti-corrosion layer 12 to the metal layer 11 side, the metal element content is 15%, and, after 5 days of immersion in the electrolyte, at 20nm, the ratio of fluorine element to metal element is as high as 3.0, and the fluorine element content is as high as 32%, and, at 40nm, the ratio of fluorine element to metal element is as high as 1.5, and the fluorine element content is as high as 25%.

[0178] At this time, the initial strength was 9.5 N / 15 mm, and the maintenance rate in the electrolyte resistance test was 65% without adding water and 24% with adding water, both of which were lower than those in the examples.

[0179] Table 1 Statistics of various data of metal-plastic composite films

[0180]

[0181]

[0182] Note: The maintenance rate refers to the ratio of the peel strength between the metal layer 11 and the first resin layer 13 measured after electrolyte resistance to the initial strength.

[0183] In summary, compared with the prior art, the present invention has the positive effect that the elements in the anti-corrosion layer 12 on the surface of the metal layer 11 are distributed in a gradient, and the carbon element and metal element content in the first anti-corrosion region and the fluorine element and metal element content in the second anti-corrosion region and the third anti-corrosion region in the anti-corrosion layer 12 can be controlled. The initial peel strength between the metal layer 11 and the first resin layer 13 of the metal-plastic composite film 1 can be improved, that is, the corrosion resistance in an electrolyte environment with a large amount of water added. It can be seen from Table 1 that in the peel strength test, Examples 1-2 are many times higher than that of Comparative Example 1, and the maintenance rate is also quite good.

[0184] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art may make several improvements and modifications without departing from the concept of the present invention, and these improvements and modifications should also be regarded as within the scope of the present invention.

Claims

1. A corrosion-resistant metal-plastic composite film, characterized in that: include: a metal layer; and An anti-corrosion layer is arranged on at least one side of the metal layer, the anti-corrosion layer comprises a carbon element, a metal element and a fluorine element, and the carbon element, the metal element and the fluorine element are distributed in a gradient from the side of the anti-corrosion layer away from the metal layer to the side close to the metal layer, the anti-corrosion layer comprises a first anti-corrosion region, a second anti-corrosion region and a third anti-corrosion region, the first anti-corrosion region is the side of the anti-corrosion layer away from the metal layer, the second anti-corrosion region is located between the first anti-corrosion region and the third anti-corrosion region, and the third anti-corrosion region is the side of the anti-corrosion layer close to the metal layer, wherein in the first anti-corrosion region, the content ratio of the carbon element is 50 %, and the content ratio of the metal element is 2%, in the second anti-corrosion area, the content ratio of the metal element is 45%, the content ratio of the fluorine element is 10%, and the ratio of the fluorine element to the metal element is 0.2, and in the third anti-corrosion area, the content ratio of the metal element is 80%, the content ratio of the fluorine element is 2%, and the ratio of the fluorine element to the metal element is 0.025, wherein the fluorine element comes from chromium fluoride, hydrofluoric acid and titanium fluoride, the carbon element comes from polyvinyl alcohol resin, the metal element comes from chromium, and the content ratio of chromium fluoride, hydrofluoric acid, polyvinyl alcohol resin and titanium fluoride is 15:1:3:2, and the coating chromium (Cr) content is 15mg / m 2 .

2. The corrosion-resistant metal-plastic composite film according to claim 1, characterized in that: The material of the metal layer is at least one of aluminum alloy, stainless steel, titanium steel or nickel-plated steel plate.

3. The corrosion-resistant metal-plastic composite film according to claim 1, characterized in that: The anti-corrosion layer is formed by an anti-corrosion liquid, and the anti-corrosion liquid is formed by mixing a trivalent chromium compound, an inorganic acid, an organic resin and water or an organic solvent. The proportion of the trivalent chromium compound in the anti-corrosion liquid is 1.9-6%, the proportion of the inorganic acid in the anti-corrosion liquid is 0.3-6%, the proportion of the organic resin in the anti-corrosion liquid is 0.6-6%, and the proportion of water or the organic solvent in the anti-corrosion liquid is 78.6-97.2%, wherein the trivalent chromium compound is chromium fluoride, the inorganic acid is hydrofluoric acid, the organic resin is polyvinyl alcohol resin, and the organic solvent is at least one of isopropyl alcohol, ethanol, and ethylene glycol butyl ether.

4. The corrosion-resistant metal-plastic composite film according to claim 3, characterized in that: The anti-corrosion liquid contains a bridging agent, wherein the bridging agent is composed of at least one of amino resin, melamine resin, phenolic resin, epoxy compound, blocked isocyanate compound, oxazoline compound, carbodiimide compound, condensate of formaldehyde and alkyl monoalcohol with 1-4 carbon atoms, and condensate of carbolic acid and formaldehyde.

5. The corrosion-resistant metal-plastic composite film according to claim 4, characterized in that: The proportion of the bridging agent content in the solid components of the anti-corrosion liquid is 0.05%-15%, or the proportion of the bridging agent content in the solid components of the anti-corrosion layer is 0.01%-30%.

6. The corrosion-resistant metal-plastic composite film according to claim 1, characterized in that: The anti-corrosion layer comprises a titanium (Ti) compound and a zirconium (Zr) compound, wherein the content ratio of the titanium (Ti) compound is not greater than 0.6%, and the content ratio of the zirconium (Zr) compound is not greater than 2.8%.

7. The corrosion-resistant metal-plastic composite film according to claim 6, characterized in that: The titanium (Ti) compound is titanium fluoride, and the zirconium (Zr) compound is at least one of zirconium fluoride and zirconium nitrate.

8. The corrosion-resistant metal-plastic composite film according to claim 1, characterized in that: The invention further comprises a first resin layer and a second resin layer, wherein the first resin layer is arranged on one side of the metal layer, and the second resin layer is arranged on the other side of the metal layer.

9. The corrosion-resistant metal-plastic composite film according to claim 8, characterized in that: The first resin layer is bonded to the metal layer by a first adhesive.

10. The corrosion-resistant metal-plastic composite film according to claim 9, characterized in that: The material of the first adhesive is at least one of a block copolymer polypropylene resin (B-PP), a random copolymer polypropylene resin (R-PP) or a homopolymer polypropylene resin (H-PP), and the polypropylene (PP) content in the block copolymer polypropylene resin (B-PP), the random copolymer polypropylene resin (R-PP) or the homopolymer polypropylene resin (H-PP) is not less than 50%.

11. The corrosion-resistant metal-plastic composite film according to claim 8, characterized in that: The second resin layer is bonded to the metal layer by a second adhesive.

12. The corrosion-resistant metal-plastic composite film according to claim 8, characterized in that: The first resin layer is a heat-welding resin layer, wherein the material of the first resin layer is at least one of polyolefin, cyclic polyolefin or modified polyolefin.

13. The corrosion-resistant metal-plastic composite film according to claim 12, characterized in that: The modified polyolefin is at least one of aliphatic carboxylic acid modified polyolefin, carboxylic acid modified cyclic polyolefin, methacrylic acid modified polyolefin, acrylic acid modified polyolefin, crotonic acid modified polyolefin or imide modified polyolefin.

14. The corrosion-resistant metal-plastic composite film according to claim 8, characterized in that: The side of the metal layer bonded to the first resin layer forms the anticorrosion layer.

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