Polyurethane adhesive, its preparation method and application

Abstract

The application discloses a polyurethane adhesive as well as a preparation method and application thereof. The adhesive is a reaction product of at least the following substances: a) a mixture containing a polyester polyol, an epoxy resin, an auxiliary agent and a solvent as a main agent component; and b) an isocyanate polymer as a curing agent component; wherein the polyester polyol contains a first polyester polyol, a second polyester polyol and a third polyester polyol, the first polyester polyol has a hydroxyl value of 10-65 mgKOH / g, the second polyester polyol has a hydroxyl value of 70-200 mgKOH / g, and the third polyester polyol has a hydroxyl value of 2-12 mgKOH / g. The adhesive of the application is composed of three polyester polyols with flexible chain segments, rigid chain segments and high molecular weight chain segments respectively, so that the outer nylon film and the aluminum foil structure of the lithium battery aluminum plastic film composite have excellent bonding strength, punching performance and moisture resistance and heat resistance, and the problem of aging whitening or delamination of the outer layer of the existing polyurethane adhesive composite lithium battery aluminum plastic film is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesive preparation, in particular to a polyurethane adhesive, a preparation method and application thereof. BACKGROUND

[0002] In order to cope with global climate change, countries have begun to develop from traditional fossil energy to new energy. In recent years, with the rapid development of new energy vehicles, energy storage and other fields, lithium ion batteries have been widely used. There are two packaging forms of lithium ion batteries, one is aluminum shell and the other is soft package. The aluminum shell packaged lithium ion battery has the disadvantages of heavy weight, easy explosion by puncture and low energy density, while the soft package lithium battery has the advantages of high energy density, flexible appearance design and good safety; Therefore, the application of soft package lithium battery is more and more.

[0003] The soft package lithium battery is packaged by aluminum plastic film, which is composed of three or four layers of film. Taking the three-layer aluminum plastic film as an example, the polyamide film, aluminum foil and polypropylene film are sequentially arranged from the outside to the inside. Since the aluminum plastic film of the soft package lithium battery not only needs strict deep drawing mechanical properties, but also needs excellent moisture resistance and aging resistance, the adhesion between the polyamide film and the aluminum foil not only needs good adhesion strength, but also needs good flexibility.

[0004] Chinese patent CN109851763A synthesizes a polymer adhesive with a molecular weight of 10000-30000, which is used for outer layer compounding of aluminum plastic film. Although the aluminum plastic film compounded by using the adhesive can complete the double pit deep drawing and simple moisture resistance and aging test, the aluminum plastic film can only reach a depth of 5mm, and can only be aged for 7 days at 60℃ / 90% without delamination, which still cannot meet the market demand for deep drawing depth and aging.

[0005] Therefore, it is of great significance to develop an adhesive that can meet the high deep drawing performance and high moisture resistance and aging performance of the aluminum plastic film. SUMMARY

[0006] The main purpose of the present application is to provide a polyurethane adhesive, a preparation method and application thereof, which can meet the high deep drawing performance and high moisture resistance and aging performance of the aluminum plastic film when used.

[0007] In order to achieve one aspect of the above purpose, the present application adopts the following technical scheme: a polyurethane adhesive, which is a reaction product of at least the following substances:

[0008] a) a mixture comprising polyester polyol, epoxy resin, auxiliary agent and solvent as main agent component; and

[0009] b) isocyanate polymer as curing agent component;

[0010] The polyester polyol comprises a first polyester polyol, a second polyester polyol and a third polyester polyol, the first polyester polyol has a hydroxyl value of 10-65 mgKOH / g, the second polyester polyol has a hydroxyl value of 70-200 mgKOH / g, and the third polyester polyol has a hydroxyl value of 2-12 mgKOH / g.

[0011] In the present application, the first polyester polyol has a hydroxyl value of 10-65 mgKOH / g, for example, 10 mgKOH / g, 20 mgKOH / g, 30 mgKOH / g, 50 mgKOH / g, 65 mgKOH / g, etc.; preferably, the first polyester polyol has a hydroxyl value of 17-40 mgKOH / g.

[0012] In some specific embodiments, the first polyester polyol is obtained by high molecular condensation polymerization reaction of diacid and diol. The diacid for synthesizing the first polyester polyol includes one or more of adipic acid, sebacic acid, isophthalic acid, 1,3-isobenzofuranone; the diol includes one or more of 2-methyl-1,3-propanediol, 1,5-pentanediol, 2,2-oxo-diethanol, ethylene glycol, 1,6-hexanediol.

[0013] In the present application, the second polyester polyol has a hydroxyl value of 70-200 mgKOH / g; for example, 70 mgKOH / g, 90 mgKOH / g, 140 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, etc.; preferably, the hydroxyl value is 90-140 mgKOH / g.

[0014] In some specific embodiments, the second polyester polyol is obtained by high molecular condensation polymerization reaction of diacid and diol. The diacid for synthesizing the second polyester polyol includes one or more of adipic acid, terephthalic acid, isophthalic acid, 1,3-isobenzofuranone; the diol includes one or more of 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 1,2-propanediol, ethylene glycol.

[0015] In the present application, the third polyester polyol has a hydroxyl value of 2-12 mgKOH / g; for example, 2 mgKOH / g, 3 mgKOH / g, 5 mgKOH / g, 7 mgKOH / g, 12 mgKOH / g, etc.; preferably, the hydroxyl value is 3.2-7.5 mgKOH / g.

[0016] In some embodiments, the third polyester polyol is a polyester polyol synthesized from a diacid and a diol via high molecular condensation polymerization. The diacid used to synthesize the third polyester polyol includes one or more of adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, and 1,3- isobenzo furan dione; and the diol includes one or more of 2-methyl-2,4-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethylolbutanol, ethylene glycol, 1,4-cyclohexane dimethanol, and 2,2-oxo diethylene glycol.

[0017] In some embodiments, the first polyester polyol is added in an amount of 5-30% by weight based on the total weight of the main agent (100%); preferably, the first polyester polyol is added in an amount of 5-15% by weight; the second polyester polyol is added in an amount of 5-20% by weight; preferably, the second polyester polyol is added in an amount of 5-10% by weight; and the third polyester polyol is added in an amount of 50-80% by weight; preferably, the third polyester polyol is added in an amount of 69-79% by weight.

[0018] In some embodiments, the mass ratio of the main agent component to the curing agent component is 100:(20-50), such as 100:20, 100:25, 100:28, 100:31, 100:35, 100:38, 100:40, 100:45, 100:50, etc.; preferably, the mass ratio of the main agent component to the curing agent component is 100:(30-40).

[0019] In the present application, the curing agent component is an isocyanate polymer, such as an aromatic isocyanate curing agent or an aliphatic isocyanate curing agent, which can be selected from toluene diisocyanate polymers, diphenylmethane diisocyanate polymers, hexamethylene diisocyanate polymers, etc., such as Wanhua W6075, HT-100, but not limited thereto.

[0020] In some embodiments, the epoxy resin is one or more of bisphenol A, bisphenol S, and bisphenol F, and preferably, the epoxy resin is one or more of epoxy resin E20, epoxy resin E31, epoxy resin E44, epoxy resin E51, bisphenol S diglycidyl ether, and 4,4-dihydroxydiphenylmethane.

[0021] In some embodiments, the auxiliary agent is one or more of a siloxane coupling agent or a carbodiimide anti-hydrolysis agent, and preferably, the auxiliary agent is one or more of γ-mercaptopropyl trimethoxysilane, γ-glycidyl ether propyl trimethoxysilane, γ-aminopropyl triethoxysilane, N,N'-dicyclohexyl carbodiimide, N,N'-di(2,6-diisopropylphenyl) carbodiimide, and N,N'-di-2,6-dimethylphenyl carbodiimide.

[0022] In some specific embodiments, the solvent is one or more of ethyl acetate, butanone, acetone, dimethyl carbonate, toluene; preferably one or more of ethyl acetate, butanone, dimethyl carbonate.

[0023] Another aspect of the present application provides a method for preparing a polyurethane adhesive, comprising the following steps:

[0024] S1: dissolving the first polyester polyol, the second polyester polyol, the third polyester polyol, the epoxy resin and the auxiliary agent in a solvent, and stirring uniformly to obtain a main agent component;

[0025] S2: mixing the main agent component with an isocyanate polymer as a curing agent component, and reacting to obtain the polyurethane adhesive.

[0026] Another aspect of the present application also provides the application of the above-mentioned polyurethane adhesive or the polyurethane adhesive prepared by the above-mentioned method, and the adhesive is used in the field of soft-pack lithium battery aluminum-plastic film, preferably used in the nylon film composite aluminum foil structure and the polyester film composite nylon film structure in the lithium battery aluminum-plastic film.

[0027] Compared with the prior art, the present application has the following advantages: the raw materials for preparing the polyurethane adhesive of the present application comprise three polyester polyols with different hydroxyl values, by adjusting the types and contents of the hard segment units and the soft segment units of each polyester polyol, the three polyester polyols have flexibility, temperature resistance and high molecular weight characteristics respectively, so that the polyurethane adhesive has excellent deep drawability and moisture resistance, and the deep drawability of the soft-pack lithium battery aluminum-plastic film compounded by the polyurethane adhesive can reach 9 mm, and after aging at 85℃ / 85% for 15 days, the surface does not delaminate and does not turn white, which solves the requirements of the soft-pack lithium battery for the deep drawability and moisture resistance of the aluminum-plastic film.

[0028] Other features and advantages of the present application will be described in detail in the following specific embodiments. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are shown in the examples, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein.

[0030] Raw material information:

[0031] Curing agent component: TDI polymer 75wt%; Wanhua Chemical Group Co., Ltd.; brand: W6075.

[0032] γ-glycidoxypropyltrimethoxysilane: purity: 97%; Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0033] Epoxy resin E-51: epoxy equivalent weight: 180-200; Beijing Inokai Technology Co., Ltd.

[0034] Ethyl acetate: purity: 99%; Beijing Inokai Technology Co., Ltd.

[0035] Polyester polyol 1-1: In a polyester reaction device with a four-necked flask, 657 g of adipic acid, 101 g of sebacic acid, 59 g of 1,6-hexanediol, 31 g of ethylene glycol, and 636 g of 2,2-oxo-diethylene alcohol were put in, stirring was started, heating was started at 140°C, and the temperature was gradually increased to 235°C, and the reaction time was controlled for 12 h; then the temperature of the reaction liquid was reduced to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 240°C, vacuum reaction was performed, and when the hydroxyl value reached 20 mgKOH / g, the reaction was stopped, and polyester polyol 1-1 was obtained.

[0036] Polyester polyol 1-2: In a polyester reaction device with a four-necked flask, 657 g of adipic acid, 101 g of sebacic acid, 59 g of 1,6-hexanediol, 31 g of ethylene glycol, and 636 g of 2,2-oxo-diethylene alcohol were put in, stirring was started, heating was started at 140°C, and the temperature was gradually increased to 235°C, and the reaction time was controlled for 12 h; then the temperature of the reaction liquid was reduced to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 240°C, vacuum reaction was performed, and when the hydroxyl value reached 40 mgKOH / g, the reaction was stopped, and polyester polyol 1-2 was obtained.

[0037] Polyester polyol 1-3: In a polyester reaction device with a four-necked flask, 657 g of adipic acid, 101 g of sebacic acid, 59 g of 1,6-hexanediol, 31 g of ethylene glycol, and 636 g of 2,2-oxo-diethylene alcohol were put in, stirring was started, heating was started at 140°C, and the temperature was gradually increased to 235°C, and the reaction time was controlled for 12 h; then the temperature of the reaction liquid was reduced to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 240°C, vacuum reaction was performed, and when the hydroxyl value reached 80 mgKOH / g, the reaction was stopped, and polyester polyol 1-3 was obtained.

[0038] Polyester polyol 1-4: In a polyester reaction device with a four-necked flask, 584 g of adipic acid, 188 g of azelaic acid, 583 g of 2,2-oxobisethanol, 118 g of 1,6-hexanediol, and 52 g of 1,5-pentanediol were put in, stirring was started, heating was started at 140°C to start the reaction, the temperature was gradually increased to 235°C, and the reaction time was controlled for 12 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, the temperature was increased to 240°C, vacuum reaction was performed, and when the hydroxyl value reached 30 mgKOH / g, the reaction was stopped, and polyester polyol 1-4 was obtained.

[0039] Polyester polyol 2-1: In a polyester reaction device with a four-necked flask, 592 g of 1,3-isobenzo furandione, 166 g of isophthalic acid, 416 g of 2,2-dimethyl-1,3-propanediol, 135 g of 2-methyl-1,3-propanediol, 76 g of 1,2-propanediol, and 59 g of 2-methyl-2,4-pentanediol were put in, stirring was started, heating was started at 160°C to start the reaction, the temperature was gradually increased to 240°C, and the reaction time was controlled for 8 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, the temperature was increased to 240°C, and the reaction was continued, and when the hydroxyl value reached 100 mgKOH / g, the reaction was stopped, and polyester polyol 2-1 was obtained.

[0040] Polyester polyol 2-2: In a polyester reaction device with a four-necked flask, 592 g of 1,3-isobenzo furandione, 166 g of isophthalic acid, 416 g of 2,2-dimethyl-1,3-propanediol, 135 g of 2-methyl-1,3-propanediol, 76 g of 1,2-propanediol, and 59 g of 2-methyl-2,4-pentanediol were put in, stirring was started, heating was started at 160°C to start the reaction, the temperature was gradually increased to 240°C, and the reaction time was controlled for 8 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, the temperature was increased to 240°C, and the reaction was continued, and when the hydroxyl value reached 140 mgKOH / g, the reaction was stopped, and polyester polyol 2-2 was obtained.

[0041] Polyester polyol 2-3: In a polyester reaction device with a four-necked flask, 592 g of 1,3-isobenzo furandione, 166 g of isophthalic acid, 416 g of 2,2-dimethyl-1,3-propanediol, 135 g of 2-methyl-1,3-propanediol, 76 g of 1,2-propanediol, and 59 g of 2-methyl-2,4-pentanediol were put in, stirring was started, heating was started at 160°C to start the reaction, the temperature was gradually increased to 240°C, and the reaction time was controlled for 8 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, the temperature was increased to 240°C, and the reaction was continued, and when the hydroxyl value reached 50 mgKOH / g, the reaction was stopped, and polyester polyol 2-3 was obtained.

[0042] Polyester polyol 2-4: In a polyester reaction device with a four-necked flask, 592 g of 1,3-isobenzofuranedione, 166 g of terephthalic acid, 208 g of 2,2-dimethyl-1,3-propanediol, 270 g of 2-methyl-1,3-propanediol, 62 g of ethylene glycol, and 118 g of 2-methyl-2,4-pentanediol were put in, stirring was started, and heating was started at 160°C to start the reaction, and the temperature was gradually increased to 240°C, and the reaction time was controlled to be 8 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 240°C to continue the reaction, and when the hydroxyl value reached 120 mgKOH / g, the reaction was stopped, and polyester polyol 2-4 was obtained.

[0043] Polyester polyol 3-1: In a polyester reaction device with a four-necked flask, 282 g of azelaic acid, 73 g of adipic acid, 166 g of terephthalic acid, 332 g of isophthalic acid, 208 g of 2,2-dimethyl-1,3-propanediol, 45 g of 2-methyl-1,3-propanediol, 59 g of 2-methyl-2,4-pentanediol, 118 g of 1,6-hexanediol, and 186 g of ethylene glycol were put in, stirring was started, and heating was started at 150°C to start the reaction, and the temperature was gradually increased to 240°C, and the reaction time was controlled to be 10 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 250°C, and vacuum reaction was performed, and when the hydroxyl value reached 3.2 mgKOH / g, the reaction was stopped, and polyester polyol 3-1 was obtained.

[0044] Polyester polyol 3-2: In a polyester reaction device with a four-necked flask, 282 g of azelaic acid, 73 g of adipic acid, 166 g of terephthalic acid, 332 g of isophthalic acid, 208 g of 2,2-dimethyl-1,3-propanediol, 45 g of 2-methyl-1,3-propanediol, 59 g of 2-methyl-2,4-pentanediol, 118 g of 1,6-hexanediol, and 186 g of ethylene glycol were put in, stirring was started, and heating was started at 150°C to start the reaction, and the temperature was gradually increased to 240°C, and the reaction time was controlled to be 10 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 250°C, and vacuum reaction was performed, and when the hydroxyl value reached 7.5 mgKOH / g, the reaction was stopped, and polyester polyol 3-2 was obtained.

[0045] Polyester polyol 3-3: In a polyester reaction device with a four-necked flask, 282 g azelaic acid, 73 g adipic acid, 166 g terephthalic acid, 332 g isophthalic acid, 208 g 2,2-dimethyl-1,3-propanediol, 45 g 2-methyl-1,3-propanediol, 59 g 2-methyl-2,4-pentanediol, 118 g 1,6-hexanediol, and 186 g ethylene glycol were put in, stirring was started, and heating was started at 150°C to start the reaction, and the temperature was gradually increased to 240°C, and the reaction time was controlled for 10 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 250°C, vacuum reaction was performed, and when the hydroxyl value reached 15 mgKOH / g, the reaction was stopped, and polyester polyol 3-3 was obtained.

[0046] Polyester polyol 3-4: In a polyester reaction device with a four-necked flask, 146 g adipic acid, 202 g sebacic acid, 94 g azelaic acid, 415 g isophthalic acid, 236 g 1,6-hexanediol, 217 g ethylene glycol, and 156 g 2,2-dimethyl-1,3-propanediol were put in, stirring was started, and heating was started at 150°C to start the reaction, and the temperature was gradually increased to 240°C, and the reaction time was controlled for 10 h; then the temperature of the reaction liquid was decreased to 100°C, 50 ppm of a catalyst was added at this time, and then the temperature was increased to 250°C, vacuum reaction was performed, and when the hydroxyl value reached 5 mgKOH / g, the reaction was stopped, and polyester polyol 3-4 was obtained.

[0047] Example 1

[0048] In a reaction flask, 10 g of polyester polyol 1-2, 5 g of polyester polyol 2-2, 79 g of polyester polyol 3-1, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were added, and then stirring was performed at 60°C to obtain a main agent component.

[0049] The main agent component was mixed with a curing agent component W6075 was uniformly mixed at a mass ratio of 100:35, and then coating and film lamination were performed.

[0050] Example 2

[0051] In a reaction flask, 10 g of polyester polyol 1-1, 10 g of polyester polyol 2-1, 74 g of polyester polyol 3-2, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were added, and then stirring was performed at 60°C to obtain a main agent component.

[0052] The main agent component was mixed with a curing agent component W6075 was uniformly mixed at a mass ratio of 100:40, and then coating and film lamination were performed.

[0053] Example 3

[0054] In a reaction flask, 10 g of polyester polyol 1-1, 10 g of polyester polyol 2-1, 74 g of polyester polyol 3-1, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were mixed and stirred uniformly at 60°C to obtain a main agent component.

[0055] The main agent component was mixed with a curing agent component W6075 was uniformly mixed at a mass ratio of 100:30 and then coated and laminated for use.

[0056] Example 4

[0057] In a reaction flask, 10 g of polyester polyol 1-4, 10 g of polyester polyol 2-4, 74 g of polyester polyol 3-4, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were mixed and stirred uniformly at 60°C to obtain a main agent component.

[0058] The main agent component was mixed with a curing agent component W6075 was uniformly mixed at a mass ratio of 100:35 and then coated and laminated for use.

[0059] Comparative Example 1

[0060] In a reaction flask, 10 g of polyester polyol 2-2, 84 g of polyester polyol 3-1, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were mixed and stirred uniformly at 60°C to obtain a main agent component.

[0061] The main agent component was mixed with a curing agent component W6075 was uniformly mixed at a mass ratio of 100:35 and then coated and laminated for use.

[0062] Comparative Example 2

[0063] In a reaction flask, 10 g of polyester polyol 1-1, 84 g of polyester polyol 3-2, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were mixed and stirred uniformly at 60°C to obtain a main agent component.

[0064] The main agent component was mixed with a curing agent component W6075 was uniformly mixed at a mass ratio of 100:35 and then coated and laminated for use.

[0065] Comparative Example 3

[0066] In a reaction flask, 54 g of polyester polyol 1-1, 40 g of polyester polyol 2-2, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were added, and then stirred uniformly at 60°C to obtain the main agent component.

[0067] The main agent component was mixed with the curing agent component W6075 was uniformly mixed at a mass ratio of 100:35, and then coated and laminated for use.

[0068] Comparative Example 4

[0069] In a reaction flask, 35 g of polyester polyol 1-2, 15 g of polyester polyol 2-2, 45 g of polyester polyol 3-1, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were added, and then stirred uniformly at 60°C to obtain the main agent component.

[0070] The main agent component was mixed with the curing agent component W6075 was uniformly mixed at a mass ratio of 100:35, and then coated and laminated for use.

[0071] Comparative Example 5

[0072] In a reaction flask, 10 g of polyester polyol 1-3, 10 g of polyester polyol 2-3, 74 g of polyester polyol 3-3, 5 g of epoxy resin E51, 1 g of γ-glycidoxypropyltrimethoxysilane, and 67 g of ethyl acetate were added, and then stirred uniformly at 60°C to obtain the main agent component.

[0073] The main agent component was mixed with the curing agent component W6075 was uniformly mixed at a mass ratio of 100:35, and then coated and laminated for use.

[0074] The adhesives obtained in Examples 1-4 to 5 and Comparative Examples 1-5 were used to composite PA / AL / CPP structures, wherein PA / AL was composited using the adhesives obtained in Examples 1-4 to 5 and Comparative Examples 1-5, and AL / CPP was composited using the commercially available adhesive Mitsui 700S, and then performance tests were performed. The composited film material was subjected to a punch depth test on an aluminum plastic film forming machine, and a wet heat resistance test (85°C / 85%) in a constant temperature and humidity chamber. Table 1 is shown as follows:

[0075] Performance Test Control Table 1

[0076]

[0077] Explanation: (1) √ indicates good appearance; × indicates surface damage; (2) initial bonding strength refers to the bonding strength of the PA / AL interface; (3) the shell depth of this experiment is 9 mm.

[0078] By comparing examples 1-4 with comparative example 1, it can be found that when the flexible first polyester polyol in the main agent is reduced, the shell-punching performance is obviously decreased, but the wet-heat resistance is still good; by comparing examples 1-4 with comparative example 2, it can be found that when the temperature-resistant second polyester polyol in the main agent is reduced, the shell-punching performance is good, but the wet-heat resistance is obviously decreased; by comparing examples 1-4 with comparative example 3, it can be found that when the high-molecular-weight third polyester polyol is reduced, the bonding strength is obviously decreased, and the shell-punching performance and the wet-heat resistance are also obviously decreased. By comparative example 5, it can be found that when the design hydroxyl value of the three polyester polyols is not suitable, for example, the hydroxyl value of the first polyester polyol is not within the range of 10-65 mgKOH / g, the hydroxyl value of the second polyester polyol is not within the range of 70-200 mgKOH / g, and the hydroxyl value of the third polyester polyol is not within the range of 2-12 mgKOH / g, the shell-punching performance and the wet-heat resistance will be decreased; therefore, the three polyester polyols respectively having the properties of flexibility, temperature resistance, and high molecular weight synergistically make the adhesive of the present application have excellent shell-punching performance and wet-heat resistance.

[0079] Although the content of the present application has been described in detail by the above preferred examples, it should be recognized that the above description should not be considered as a limitation of the present application. Those skilled in the art can understand that some modifications or adjustments can be made to the present application under the teaching of the present specification. These modifications or adjustments should also be within the scope defined by the claims of the present application.

Claims

1. A polyurethane adhesive, characterized in that, It is a reaction product of at least the following substances: a) A mixture comprising polyester polyol, epoxy resin, additives, and solvent as the main component; and b) Isocyanate polymers are used as curing agent components; The polyester polyol comprises a first polyester polyol, a second polyester polyol, and a third polyester polyol. The first polyester polyol has a hydroxyl value of 20-65 mgKOH / g, the second polyester polyol has a hydroxyl value of 70-140 mgKOH / g, and the third polyester polyol has a hydroxyl value of 3.2-7.5 mgKOH / g. Based on the total solid mass of the main agent, the addition amount of the first polyester polyol is 5-30%; the addition amount of the second polyester polyol is 5-20%; and the addition amount of the third polyester polyol is 50-80%. The first polyester polyol is a polyester polyol obtained by polymer condensation polymerization of a diacid and a diol; the diacid used to synthesize the first polyester polyol includes one or more of adipic acid, sebacic acid, and isophthalic acid; the diol includes 2-methyl-1,3-propanediol, 1,5-pentanediol, 2,2-oxodiethanol, ethylene glycol, and 1,6-propanediol. One or more of hexanediol; The second polyester polyol is a polyester polyol obtained by polymer condensation polymerization of a diacid and a diol; the diacid used to synthesize the second polyester polyol includes one or more of adipic acid, terephthalic acid, isophthalic acid, and 1,3-isobenzofuran dione; the diol includes one or more of 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 1,2-propanediol, and ethylene glycol. The third polyester polyol is a polyester polyol obtained by polymer condensation polymerization of a diacid and a diol; the diacid used to synthesize the third polyester polyol includes one or more of adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, and 1,3-isobenzofuran dione; the diol includes 2-methyl-2,4-pentanediol, 1,6-diol, etc. One or more of hexanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dihydroxymethylbutanol, ethylene glycol, 1,4-cyclohexanediethanol, and 2,2-oxodiethanol.

2. The polyurethane adhesive according to claim 1, characterized in that, The first polyester polyol has a hydroxyl value of 20-40 mgKOH / g, and / or the second polyester polyol has a hydroxyl value of 90-140 mgKOH / g, and / or the third polyester polyol has a hydroxyl value of 3.2-7.5 mgKOH / g.

3. The polyurethane adhesive according to claim 1, characterized in that, Based on the total solid mass of the main agent, the amount of the first polyester polyol added is 5-15%; the amount of the second polyester polyol added is 5-10%; and the amount of the third polyester polyol added is 69-79%.

4. The polyurethane adhesive according to claim 1, characterized in that, The mass ratio of the main component to the curing agent component is 100:(20-50).

5. The polyurethane adhesive according to claim 4, characterized in that, The mass ratio of the main component to the curing agent component is 100:(30-40).

6. The polyurethane adhesive according to claim 1, characterized in that, The curing agent component is an aromatic isocyanate curing agent or an aliphatic isocyanate curing agent.

7. The polyurethane adhesive according to claim 6, characterized in that, The curing agent component is selected from one or more of toluene diisocyanate polymer, diphenylmethane diisocyanate polymer, and hexamethylene diisocyanate polymer.

8. The polyurethane adhesive according to claim 1, characterized in that, The epoxy resin is one or more of bisphenol A, bisphenol S, and bisphenol F.

9. The polyurethane adhesive according to claim 8, characterized in that, The epoxy resin is selected from one or more of epoxy resin E20, epoxy resin E31, epoxy resin E44, epoxy resin E51, and bisphenol S diglycidyl ether.

10. The polyurethane adhesive according to claim 1, characterized in that, The auxiliary agent is one or more of a siloxane coupling agent or a carbodiimide anti-hydrolysis agent; and / or The solvent is one or more of ethyl acetate, butanone, acetone, dimethyl carbonate, and toluene.

11. The polyurethane adhesive according to claim 10, characterized in that, The adjuvant is selected from one or more of γ-mercaptopropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N,N'-dicyclohexylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, and N,N'-bis-2,6-dimethylphenylcarbodiimide; and / or, The solvent is selected from one or more of ethyl acetate, butanone, and dimethyl carbonate.

12. A method for preparing the polyurethane adhesive according to any one of claims 1-11, characterized in that, Includes the following steps: S1: Dissolve the first polyester polyol, the second polyester polyol, the third polyester polyol, the epoxy resin and the additives in a solvent and stir until homogeneous to obtain the main component. S2: The main component is mixed with the isocyanate polymer, which is the curing agent component, and the reaction is carried out to obtain the polyurethane adhesive.

13. The application of the polyurethane adhesive according to any one of claims 1-11 or the polyurethane adhesive prepared by the method of claim 12, characterized in that, The adhesive is used in the field of aluminum-plastic film for soft-pack lithium batteries.

14. The application of the polyurethane adhesive according to claim 13, characterized in that, The adhesive is used in the nylon film composite aluminum foil structure or the polyester film composite nylon film structure in the lithium battery aluminum-plastic film.

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