Cold forming aluminum-plastic composite film adhesive as well as preparation method and application thereof

Abstract

The invention provides a cold-formed aluminum-plastic composite film adhesive as well as a preparation method and application thereof, and belongs to the technical field of aluminum-plastic composite films. The cold-formed aluminum-plastic composite film adhesive comprises a main agent, a curing agent and a first solvent, wherein the main agent comprises polyester polyol, an auxiliary agent and a second solvent; the preparation method of the polyester polyol comprises the following steps: mixing first dibasic acid, second dibasic acid, first dihydric alcohol and second dihydric alcohol, and carrying out esterification polycondensation reaction to obtain the polyester polyol, the obtained adhesive has excellent cold forming performance and humidity and heat resistance, and can be used for preparing an aluminum-plastic composite film.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum-plastic films, in particular to a cold-formed aluminum-plastic composite film adhesive and a preparation method and application thereof. Background Art

[0002] Cold-formed aluminum-plastic composite films can be used in pharmaceutical, food, and lithium battery packaging. Different applications place varying emphasis on the performance requirements of the film and adhesive. For example, pharmaceutical packaging requires the composite film to have excellent cold-forming properties and heat resistance, while food packaging has lower requirements for cold-forming properties but higher requirements for moisture and heat resistance. Lithium battery packaging also places high demands on both cold-forming and moisture and heat resistance.

[0003] Generally speaking, the structural design of cold-formed aluminum-plastic composite film adhesives needs to consider multiple application properties at the same time to meet the application requirements of different scenarios. When polyester polyurethane adhesives are used for cold forming applications, benzene-ring-containing diacids (terephthalic acid, isophthalic acid, phthalic acid) and short-chain multi-side chain diols (ethylene glycol, 2,2-dimethyl-1,3-propylene glycol) are used as the base structure to prepare high glass transition temperature resins. They are inexpensive and take into account both adhesion and moisture and heat resistance, and are widely used by various adhesive products. When considering cold forming performance, flexible monomers that improve elasticity, rheological properties and lower the glass transition temperature need to be added to the above structure. Among the existing products on the market, manufacturers mainly choose long-chain diacids such as 1,9-nonanediic acid and 1,10-decanedioic acid, but long-chain diacids are generally more expensive, which limits some application scenarios. Summary of the Invention

[0004] The purpose of the present invention is to provide a cold-formed aluminum-plastic composite film adhesive and a preparation method and application thereof, wherein the adhesive has excellent cold-formability and moisture-heat resistance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A cold-formed aluminum-plastic composite film adhesive comprises a main agent, a curing agent and a first solvent, wherein the main agent comprises polyester polyol, an auxiliary agent and a second solvent;

[0007] The preparation method of the polyester polyol comprises the following steps:

[0008] Mixing the first dibasic acid, the second dibasic acid, the first diol and the second diol, and performing an esterification-polycondensation reaction to obtain a polyester polyol;

[0009] The first dibasic acid is composed of terephthalic acid and isophthalic acid in a molar ratio of 1.7 to 2.3:1;

[0010] The second dibasic acid includes one or more of 1,4-butanedioic acid, 1,5-glutaric acid, and 1,6-hexanedioic acid;

[0011] The first diol is composed of 2,2-dimethyl-1,3-propylene glycol and ethylene glycol in a molar ratio of 1.3 to 1.7:1;

[0012] The second diol includes one or more of 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and 2-ethyl-1,3-hexanediol.

[0013] Preferably, the molar ratio of the hydroxyl group in the main agent to the isocyanate group in the curing agent is 1:1.2-1.6.

[0014] Preferably, the ratio of the total molar amount of the first dibasic acid and the second dibasic acid to the total molar amount of the first diol and the second diol is 1:1.1-1.3;

[0015] The molar ratio of the first dibasic acid to the second dibasic acid is 2.5 to 3.5:1;

[0016] The molar ratio of the first glycol to the second glycol is 2 to 3:1.

[0017] Preferably, the number average molecular weight of the polyester polyol is 15,000 to 50,000.

[0018] Preferably, the curing agent includes one or more of toluene diisocyanate and diphenylmethane diisocyanate; the first solvent includes one or more of ethyl acetate and 2-butanone, and the mass ratio of the first solvent to the main agent is 5 to 15:15;

[0019] The auxiliary agent includes bisphenol A epoxy resin, a silane coupling agent and an anti-hydrolysis agent; the second solvent includes one or more of ethyl acetate and 2-butanone, and the mass ratio of the second solvent to the polyester polyol is 35 to 60:50.

[0020] Preferably, the bisphenol A epoxy resin includes epoxy resin E51, epoxy resin E44 or epoxy resin E35, and the epoxy value of the bisphenol A epoxy resin is 0.35 to 0.58; the mass of the bisphenol A epoxy resin accounts for 1 to 6 wt% of the mass of the main agent;

[0021] The silane coupling agent includes one or more of vinyl tris(β-methoxyethoxy)silane, vinyl trimethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-(meth)acryloxypropyl trimethoxysilane, γ-(meth)acryloxypropyl triethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl triethoxysilane, N-β-(aminoethyl)-γ-aminopropyl methyl diethoxysilane, γ-aminopropyl triethoxysilane, N-phenyl-γ-aminopropyl trimethoxysilane, γ-mercaptopropyl trimethoxysilane and γ-mercaptopropyl triethoxysilane; the mass of the silane coupling agent accounts for 0.1 to 1.5 wt% of the mass of the main agent;

[0022] The anti-hydrolysis agent includes one or more of 1,3-dicyclohexylcarbodiimide and 1,3-diisopropylcarbodiimide; the mass of the anti-hydrolysis agent accounts for 0.1-1.5 wt % of the mass of the main agent.

[0023] Preferably, the temperature of the esterification-polycondensation reaction is 220-240° C., the time is 1-4 hours, and the vacuum degree is an absolute pressure ≤ 100 Pa.

[0024] The present invention provides a method for preparing the above-mentioned cold-formed aluminum-plastic composite film adhesive, comprising the following preparation steps:

[0025] The polyester polyol, the auxiliary agent and the curing agent are mixed to obtain the cold-formed aluminum-plastic composite film adhesive.

[0026] The present invention provides the application of the above-mentioned cold-formed aluminum-plastic composite film adhesive or the cold-formed aluminum-plastic composite film adhesive prepared by the above-mentioned preparation method in aluminum-plastic composite film. The application method comprises the following steps: coating the cold-formed aluminum-plastic composite film adhesive on a first film substrate and then compounding it with a second film substrate.

[0027] Preferably, the first film substrate and the second film substrate independently include one or more of polyolefin films, fluorinated polyolefin films, polyester films, polyamide films, polyimide films and metal foils;

[0028] The thickness of the composite film is 3-5 μm.

[0029] Beneficial effects of the present invention:

[0030] The present invention uses a short-chain acid and a short-chain alcohol in combination on the basis of a polyester polyol structure of terephthalic acid, isophthalic acid, neopentyl glycol and ethylene glycol, avoiding the use of long-chain diacid monomers. While improving the economy, the prepared adhesive has excellent cold forming performance and moisture and heat resistance, and is suitable for medicine, food and lithium battery packaging. DETAILED DESCRIPTION

[0031] The present invention provides a cold-formed aluminum-plastic composite film adhesive, comprising a main agent, a curing agent and a first solvent, wherein the main agent comprises polyester polyol, an auxiliary agent and a second solvent;

[0032] The preparation method of the polyester polyol comprises the following steps:

[0033] The first dibasic acid, the second dibasic acid, the first diol and the second diol are mixed and subjected to an esterification-polycondensation reaction to obtain a polyester polyol;

[0034] The first dibasic acid is composed of terephthalic acid and isophthalic acid in a molar ratio of 1.7 to 2.3:1;

[0035] The second dibasic acid includes one or more of 1,4-butanedioic acid, 1,5-glutaric acid, and 1,6-hexanedioic acid;

[0036] The first diol is composed of 2,2-dimethyl-1,3-propylene glycol and ethylene glycol in a molar ratio of 1.3 to 1.7:1;

[0037] The second diol includes one or more of 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and 2-ethyl-1,3-hexanediol.

[0038] In the present invention, unless otherwise specified, the raw materials required for preparation are all commercially available products well known to those skilled in the art.

[0039] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the preparation method of the polyester polyol preferably includes the following steps: adding a first dibasic acid, a second dibasic acid, a first diol and a second diol into a reaction kettle, replacing the air in the reaction kettle with nitrogen after the addition, and performing an esterification-polycondensation reaction to obtain the polyester polyol.

[0040] In the present invention, the temperature of the esterification-polycondensation reaction is preferably 220-240° C., more preferably 230-240° C., the time is preferably 1-4 h, more preferably 4 h, and the vacuum degree is preferably absolute pressure ≤ 100 Pa.

[0041] In the present invention, the first dibasic acid is preferably composed of terephthalic acid and isophthalic acid in a molar ratio of 1.7 to 2.3:1, and more preferably composed of terephthalic acid and isophthalic acid in a molar ratio of 2:1.

[0042] In the present invention, the second dibasic acid preferably includes one or more of 1,4-butanedioic acid, 1,5-glutaric acid, and 1,6-hexanedioic acid, and more preferably includes 1,5-glutaric acid or 1,6-hexanedioic acid.

[0043] In the present invention, the first diol is preferably composed of 2,2-dimethyl-1,3-propanediol and ethylene glycol in a molar ratio of 1.3 to 1.7:1, and more preferably composed of 2,2-dimethyl-1,3-propanediol and ethylene glycol in a molar ratio of 1.5 to 1.7:1.

[0044] In the present invention, the second diol preferably includes one or more of 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and 2-ethyl-1,3-hexanediol, and further preferably includes 2,2-dimethyl-1,3-propanediol and 3-methyl-1,5-pentanediol.

[0045] In the present invention, the ratio of the total molar amount of the first dibasic acid and the second dibasic acid to the total molar amount of the first diol and the second diol is preferably 1:1.1 to 1.3, more preferably 1:1.2 to 1.3;

[0046] The molar ratio of the first dibasic acid to the second dibasic acid is preferably 2.5 to 3.5:1, more preferably 3 to 3.5:1;

[0047] The molar ratio of the first glycol to the second glycol is preferably 2 to 3:1, more preferably 2.5 to 3:1.

[0048] In the present invention, the number average molecular weight of the polyester polyol is preferably 15,000 to 50,000, more preferably 20,000 to 25,000.

[0049] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the curing agent preferably includes one or more of toluene diisocyanate and diphenylmethane diisocyanate.

[0050] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the first solvent preferably includes one or more of ethyl acetate and 2-butanone, and is more preferably 2-butanone. When the first solvent is ethyl acetate and 2-butanone, the present invention does not specifically limit the volume ratio between the ethyl acetate and 2-butanone; the mass ratio of the first solvent to the main agent is preferably 5 to 15:15, and is more preferably 10:15.

[0051] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the auxiliary agent preferably includes bisphenol A epoxy resin, a silane coupling agent and an anti-hydrolysis agent, wherein the bisphenol A epoxy resin preferably includes epoxy resin E51, epoxy resin E44 or epoxy resin E35, and is further preferably epoxy resin E51; the epoxy value of the bisphenol A epoxy resin is preferably 0.35-0.58; the mass of the bisphenol A epoxy resin preferably accounts for 1-6wt% of the mass of the main agent, and is further preferably 1.5wt% of the mass of the main agent.

[0052] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the silane coupling agent preferably includes vinyl tris (β-methoxyethoxy) silane, vinyl trimethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-(meth)acryloxypropyl trimethoxy silane, γ-(meth)acryloxypropyl triethoxy silane, β-(3,4-epoxycyclohexyl)ethyl trimethoxy silane, β-(3,4-epoxycyclohexyl)ethyl triethoxy silane, N -β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane, and further preferably includes γ-glycidoxypropyltrimethoxysilane; the mass of the silane coupling agent preferably accounts for 0.1 to 1.5wt% of the mass of the main agent, and further preferably accounts for 1.5wt% of the mass of the main agent.

[0053] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the anti-hydrolysis agent preferably includes one or more of 1,3-dicyclohexylcarbodiimide and 1,3-diisopropylcarbodiimide, and is further preferably 1,3-dicyclohexylcarbodiimide or 1,3-diisopropylcarbodiimide; the mass of the anti-hydrolysis agent preferably accounts for 0.1 to 1.5 wt% of the mass of the main agent, and is further preferably 0.5 wt% of the mass of the main agent.

[0054] In the cold-formed aluminum-plastic composite film adhesive provided by the present invention, the second solvent preferably includes one or more of ethyl acetate and 2-butanone. When the second solvent is ethyl acetate and 2-butanone, the present invention does not specifically limit the volume ratio between the ethyl acetate and 2-butanone; the mass ratio of the second solvent to the polyester polyol is preferably 35 to 60:50, and more preferably 46.5:50.

[0055] The present invention provides a method for preparing a cold-formed aluminum-plastic composite film adhesive, comprising the following steps:

[0056] The polyester polyol, the auxiliary agent and the curing agent are mixed to obtain a cold-formed aluminum-plastic composite film adhesive;

[0057] In the present invention, the polyester polyol, the auxiliary agent and the first solvent are preferably mixed evenly to obtain a main agent; and the main agent, the curing agent and the second solvent are mixed to obtain a cold-formed aluminum-plastic composite film adhesive.

[0058] In the present invention, the mass ratio of the main agent, the curing agent and the second solvent is preferably 10:1.7 to 3:10 to 20, and more preferably 10:2.5:15.

[0059] The present invention provides the application of the cold-formed aluminum-plastic composite film adhesive or the cold-formed aluminum-plastic composite film adhesive prepared by the above-mentioned preparation method in film lamination.

[0060] In the present invention, the application method preferably comprises the following steps: coating the cold-formed aluminum-plastic composite film adhesive on a film substrate, and then laminating it with another film substrate.

[0061] In the present invention, the film substrate preferably includes one or more of polyolefin films, fluorinated polyolefin films, polyester films, polyamide films, polyimide films and metal foils, and more preferably polyamide films, aluminum foils and polyolefin films.

[0062] In the present invention, the thickness of the composite film is preferably 3 to 5 μm.

[0063] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0064] The acid value is determined in accordance with HG-T 2708-95 Determination of Acid Value in Polyester Polyols; and the viscosity is measured using a rotational viscometer at 25°C and a No. 7 rotor.

[0065] Example 1

[0066] 373.79 g of terephthalic acid, 186.90 g of isophthalic acid, 164.41 g of 1,6-hexanediol, 95.77 g of ethylene glycol, 241.03 g of 2,2-dimethyl-1,3-propylene glycol, and 182.32 g of 3-methyl-1,5-pentanediol were added to a reactor. After the addition of the materials, the air in the reactor was replaced with nitrogen. The temperature was raised to 230° C. for esterification-polycondensation reaction. After reacting for 3 hours, the vacuum degree was gradually increased to an absolute pressure of ≤100 Pa within 1 hour, and the vacuum degree was maintained for about 2.5 hours to obtain a polyester polyol. The acid value of the polyester polyol was determined to be 0.31 mgKOH / g, and the number average molecular weight was 23639.

[0067] 46.5 g of the polyester polyol prepared above, 1.5 g of epoxy resin E51, 1.5 g of γ-glycidyloxypropyltrimethoxysilane, 0.5 g of 1,3-diisopropylcarbodiimide, 25 g of ethyl acetate, and 25 g of 2-butanone were mixed to obtain a main agent; the viscosity of the main agent was measured to be 1551 mPa·s;

[0068] The main agent and toluene diisocyanate were preheated to 60° C., and the main agent, toluene diisocyanate and 2-butanone were uniformly stirred in a mass ratio of 10:2.5:15. The molar ratio of the hydroxyl group in the main agent to the isocyanate group in the curing agent was 1:1.5 to obtain an adhesive.

[0069] Example 2

[0070] 373.79 g of terephthalic acid, 186.90 g of isophthalic acid, 149.16 g of 1,5-pentanedioic acid, 95.77 g of ethylene glycol, 241.03 g of 2,2-dimethyl-1,3-propylene glycol, and 182.32 g of 1,6-hexanediol were added to a reactor. After the addition of the materials, the air in the reactor was replaced with nitrogen. The temperature was raised to 230° C. for esterification reaction. After the reaction for 3 hours, the vacuum degree was gradually increased to an absolute pressure of ≤100 Pa within 1 hour, and the vacuum degree was maintained for about 2.5 hours for polycondensation reaction to obtain polyester polyol-2. The acid value of polyester polyol-2 was determined to be 0.40 mgKOH / g, and the number average molecular weight was 22977.

[0071] 46.5 g of the polyester polyol prepared above, 1.5 g of epoxy resin E51, 1.5 g of γ-glycidyloxypropyltrimethoxysilane, 0.5 g of 1,3-dicyclohexylcarbodiimide, 25 g of ethyl acetate, and 25 g of 2-butanone were mixed to obtain a main agent; the viscosity of the main agent was measured to be 1685 mPa·s;

[0072] The main agent and toluene diisocyanate were preheated to 60° C., and the main agent, curing agent and 2-butanone were uniformly stirred in a mass ratio of 10:2.5:15. The molar ratio of the hydroxyl group in the main agent to the isocyanate group in the curing agent was 1:1.5 to obtain an adhesive.

[0073] Comparative Example 1

[0074] The only difference from Example 1 is:

[0075] The original polyester polyol structure design was used, and 1,9-zelaic acid was used as a viscosity-reducing and elastic monomer for comparison. Specifically:

[0076] 373.79 g of terephthalic acid, 186.90 g of isophthalic acid, 212.44 g of 1,9-nonanediol, 143.65 g of ethylene glycol, and 321.37 g of 2,2-dimethyl-1,3-propanediol were added to a reactor. After the addition of the materials, the air in the reactor was replaced with nitrogen. The temperature was raised to 230° C. for esterification reaction. After the reaction for 3 hours, the vacuum degree was gradually increased to an absolute pressure of ≤100 Pa within 1 hour, and the vacuum degree was maintained for 2.5 hours to carry out polycondensation reaction to obtain polyester polyol. The acid value of the polyester polyol was determined to be 0.36 mgKOH / g, and the number average molecular weight was 23495.

[0077] 46.5 g of the polyester polyol prepared above, 1.5 g of epoxy resin E51, 1.5 g of γ-glycidyloxypropyltrimethoxysilane, 0.5 g of 1,3-diisopropylcarbodiimide, 25 g of ethyl acetate, and 25 g of 2-butanone were mixed to obtain a main agent; the viscosity of the adhesive main agent was measured to be 1764 mPa·s;

[0078] Preheat the main agent and curing agent to 60° C., and mix the main agent, curing agent and 2-butanone in a mass ratio of 10:2.5:15 to obtain an adhesive.

[0079] Application and performance testing

[0080] The adhesives obtained in Examples 1 to 2 and Comparative Example 1 were applied to film composites according to the following method, and normal and high temperature peel strength tests, cold forming performance tests, heat resistance tests, and wet heat resistance tests were performed. The results are shown in Tables 1 and 2.

[0081] 1. Application method:

[0082] The aluminum foil was cut into a rectangle of 15 cm × 27 cm, the adhesive was applied to the aluminum foil, and the film was dried at 95°C for 1 min. The laminating machine was preheated to 60°C, and the polyamide film, aluminum foil and PP film were compounded using a pressure of 0.5 MPa. The film was aged at 60°C for 120 h to form a film. After aging, the film thickness was measured to be in the range of 3 to 5 μm, thereby obtaining a polyamide-aluminum foil matte composite film.

[0083] 2. Performance Testing

[0084] (1) Normal and high temperature peel strength test

[0085] According to GB-T 2790-1995 Adhesives - 180° Peel Strength Test Method - Flexible Material to Rigid Material Standard Determination, composite film samples were cut into 15mm x 200mm strips. The unbonded ends of the materials on both sides of the adhesive layer to be tested were symmetrically clamped in the upper and lower clamps of a universal testing machine, ensuring that the clamping parts did not slip and that the applied tension was evenly distributed across the width of the specimen. The testing machine was then operated, with the upper and lower clamps separated at a rate of 300mm / min. The interlayer peel strength of the corresponding material was measured by the testing machine. The results are shown in Table 1.

[0086] In the normal peel strength test, peel strength ≥ 6N / cm is level 1, 6N / cm>peel strength ≥ 4N / cm is level 2, 4 / cm>peel strength ≥ 3N / cm is level 3, and peel strength ≤ 3N / cm is level 4;

[0087] In the high-temperature peel strength test, peel strength ≥3N / cm is level 1, 3N / cm>peel strength ≥2N / cm is level 2, 2 / cm>peel strength ≥1.5N / cm is level 3, and peel strength ≤1.5N / cm is level 4.

[0088] (2) Cold forming performance test

[0089] The composite film was tested using a punching machine. The composite film was cut into 7 cm × 11 cm rectangles and punched to a depth of 65 mm using a 33 mm × 37 mm double-pit die to obtain a double-pit film. The appearance was observed to determine the cold forming performance. The results are recorded in Table 1.

[0090] (3) Heat resistance test

[0091] The test was conducted using a heat sealer. A cold-formed 33 mm × 37 mm double-corrugated film was heat-sealed at 185°C for 4 seconds. The appearance was observed to determine the heat resistance. The results are recorded in Table 1.

[0092] Table 1 Test data of composite membranes prepared in Examples 1-2 and Comparative Example 1

[0093] Normal peel strength 120℃ peel strength Cold forming properties Heat resistance Example 1 Level 1 Level 1 good good Example 2 Level 1 Level 1 good good Comparative Example 1 Level 1 Level 1 good good

[0094] As can be seen from Table 1, the cold-formed aluminum-plastic composite film adhesive prepared after the structure change of the present invention has the same good bonding performance, cold forming performance and heat resistance as the adhesive prepared with the existing mature structure in Comparative Example 1.

[0095] (4) Moisture and heat resistance test

[0096] Testing was conducted using a constant temperature and humidity chamber and a constant temperature water bath. Cold-formed, 33mm x 37mm, double-corrugated films were placed in a constant temperature and humidity chamber at 85°C and 85% RH, and in a constant temperature water bath at 60°C. The films were observed for appearance after 7, 21, and 42 days to determine their resistance to moisture and heat. The results are shown in Table 2.

[0097] Table 2 Test data of moisture and heat resistance of composite films prepared in Examples 1-2 and Comparative Example 1

[0098]

[0099] As shown in Table 2, in the moisture and heat resistance test, the cold-formed aluminum-plastic composite film adhesive prepared by the present invention has a slight white line visible under strong light after aging at 85°C and 85% RH for 42 days, which is comparable to the performance of existing mature structures.

[0100] It can be seen from the above embodiments that the present invention provides a cold-formed aluminum-plastic composite film adhesive and its preparation method and application. The obtained cold-formed aluminum-plastic composite film adhesive has good bonding properties to both metal films and plastic films, and its cold forming performance, heat resistance and moisture and heat resistance are comparable to existing mature products, with lower preparation cost, and is suitable for use as a cold-formed aluminum-plastic composite adhesive.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A cold-formed aluminum-plastic composite film adhesive, characterized in that: The method comprises a main agent, a curing agent and a first solvent, wherein the main agent comprises polyester polyol, an auxiliary agent and a second solvent; The preparation method of the polyester polyol comprises the following steps: Mixing the first dibasic acid, the second dibasic acid, the first diol and the second diol, and performing an esterification-polycondensation reaction to obtain a polyester polyol; The first dibasic acid is composed of terephthalic acid and isophthalic acid in a molar ratio of 1.7 to 2.3:1; The second dibasic acid includes one or more of 1,4-butanedioic acid, 1,5-glutaric acid, and 1,6-hexanedioic acid; The first diol is composed of 2,2-dimethyl-1,3-propanediol and ethylene glycol in a molar ratio of 1.3 to 1.7:1; The second diol includes one or more of 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and 2-ethyl-1,3-hexanediol.

2. The cold-formed aluminum-plastic composite film adhesive according to claim 1, characterized in that: The molar ratio of the hydroxyl group in the main agent to the isocyanate group in the curing agent is 1:1.2-1.

6.

3. The cold-formed aluminum-plastic composite film adhesive according to claim 1, characterized in that: The ratio of the total molar amount of the first dibasic acid and the second dibasic acid to the total molar amount of the first diol and the second diol is 1:1.1 to 1.3; The molar ratio of the first dibasic acid to the second dibasic acid is 2.5 to 3.5:1; The molar ratio of the first glycol to the second glycol is 2 to 3:

1.

4. The cold-formed aluminum-plastic composite film adhesive according to claim 1, characterized in that: The number average molecular weight of the polyester polyol is 15,000 to 50,000.

5. The cold-formed aluminum-plastic composite film adhesive according to claim 1, characterized in that: The curing agent includes one or more of toluene diisocyanate and diphenylmethane diisocyanate; the first solvent includes one or more of ethyl acetate and 2-butanone, and the mass ratio of the first solvent to the main agent is 5 to 15:15; The auxiliary agent includes bisphenol A epoxy resin, a silane coupling agent and an anti-hydrolysis agent; the second solvent includes one or more of ethyl acetate and 2-butanone, and the mass ratio of the second solvent to the polyester polyol is 35 to 60:

50.

6. The cold-formed aluminum-plastic composite film adhesive according to claim 1, characterized in that: The bisphenol A epoxy resin includes epoxy resin E51, epoxy resin E44 or epoxy resin E35, and the epoxy value of the bisphenol A epoxy resin is 0.35-0.58; the mass of the bisphenol A epoxy resin accounts for 1-6wt% of the mass of the main agent; The silane coupling agent includes one or more of vinyl tris(β-methoxyethoxy)silane, vinyl trimethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-(meth)acryloxypropyl trimethoxysilane, γ-(meth)acryloxypropyl triethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl triethoxysilane, N-β-(aminoethyl)-γ-aminopropyl methyl diethoxysilane, γ-aminopropyl triethoxysilane, N-phenyl-γ-aminopropyl trimethoxysilane, γ-mercaptopropyl trimethoxysilane and γ-mercaptopropyl triethoxysilane; the mass of the silane coupling agent accounts for 0.1 to 1.5 wt% of the mass of the main agent; The anti-hydrolysis agent includes one or more of 1,3-dicyclohexylcarbodiimide and 1,3-diisopropylcarbodiimide; the mass of the anti-hydrolysis agent accounts for 0.1-1.5 wt % of the mass of the main agent.

7. The cold-formed aluminum-plastic composite film adhesive according to claim 1, characterized in that: The temperature of the esterification-polycondensation reaction is 220-240° C., the time is 1-4 hours, and the vacuum degree is an absolute pressure ≤ 100 Pa.

8. The method for preparing the cold-formed aluminum-plastic composite film adhesive according to any one of claims 1 to 7, characterized in that: The method comprises the following preparation steps: The polyester polyol, the auxiliary agent and the curing agent are mixed to obtain the cold-formed aluminum-plastic composite film adhesive.

9. Use of the cold-formed aluminum-plastic composite film adhesive according to any one of claims 1 to 7 or the cold-formed aluminum-plastic composite film adhesive prepared by the preparation method according to claim 8 in aluminum-plastic composite films, characterized in that: The application method comprises the following steps: coating the cold-formed aluminum-plastic composite film adhesive on a first film substrate, and then laminating the adhesive with a second film substrate.

10. The use according to claim 9, characterized in that The first film substrate and the second film substrate independently include one or more of a polyolefin film, a fluorinated polyolefin film, a polyester film, a polyamide film, a polyimide film and a metal foil; The thickness of the composite film is 3-5 μm.

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