Epoxy binder capable of being used for bonding PA6 and PP films and preparation method of epoxy binder

Abstract

The invention discloses an epoxy binder capable of being used for bonding PA6 and PP films and a preparation method of the epoxy binder. Polar group amido bonds are introduced into molecules of the epoxy binder, and the epoxy binder and a PA material generate high bonding strength through intermolecular acting force (hydrogen bonds); according to the present invention, the wettability of the binder matrix on the PA polar material is improved, and a large number of hydrogen bonds can be formed between the binder and the PA polar material so as to achieve the adhesion enhancing purpose; meanwhile, the epoxy adhesive is non-polar, non-polar groups have good compatibility with polypropylene in the curing process, and good adhesion to the PP film is achieved through molecular chain entanglement; the epoxy adhesive disclosed by the invention can remarkably improve the bonding strength between the PA6 film and the PP film, so that the performance of the composite film is improved; # imgabs0 #

Description

Technical Field

[0001] The invention relates to the field of adhesives for polymer materials, in particular to an epoxy adhesive and a preparation method thereof, and application of the epoxy adhesive in bonding PA6 and PP films. Background Art

[0002] Polymer materials are increasingly used in agriculture, industry and other fields. Especially in the current highly developed logistics, polymer packaging materials have become a hot field. In order to achieve good packaging performance, it is necessary to compound a variety of polymer film, or polymer and metal film together to give the polymer material a variety of excellent properties such as puncture resistance, barrier, high strength, etc. The compounding of multi-layer films is inseparable from adhesives, especially when two films with large polarity differences are compounded together, it is difficult to achieve good bonding through the polymer's own bonding at high temperature, and usually requires additional coating of adhesives.

[0003] Polypropylene (PP) is a thermoplastic synthetic resin with excellent performance. It has chemical resistance, heat resistance, electrical insulation and good wear resistance. It can resist the corrosion of acid, alkali, salt solution and various organic solvents below 80°C. It is widely used in the production of fiber products, medical equipment, chemical containers, etc. However, the mechanical strength and high temperature heat resistance of polypropylene cannot meet the requirements of industrial use, so other materials are needed to supplement the performance of polypropylene to meet industrial needs.

[0004] Polyamide (PA) is the earliest thermoplastic that can withstand heavy loads. It is also the variety with the largest output, the most varieties, and the widest application among the five general engineering plastics. PA materials have excellent heat resistance, low temperature resistance, impact resistance, good chemical stability, and fatigue resistance in applications, making polyamide an important packaging material, especially industrial packaging materials. Polyamide mainly plays a role in improving the mechanical properties and heat resistance of the film in packaging materials, which can effectively improve the application range and service life of packaging materials.

[0005] Therefore, PP film is compounded with PA to prepare packaging bags with high mechanical strength, heat resistance, solvent resistance and electrical insulation. However, the polarity of PP and PA materials is quite different, and the adhesion between the two is poor, which greatly affects the performance and service life of the composite packaging bags. Therefore, an adhesive is usually used to bond PA and PP films. Epoxy adhesive is the most widely used adhesive in the world. Epoxy resin is a thermosetting resin with good bonding strength, chemical resistance and electrical insulation, and the processing technology used is also very flexible.

[0006] This project provides a new epoxy adhesive that can be used to bond PA6 and PP films, which greatly improves the bonding strength between PA6 and PP films and gives the composite packaging bags excellent mechanical properties and service life. Summary of the invention

[0007] The present invention provides an epoxy adhesive and a preparation method and application thereof. The epoxy adhesive of the present invention can improve the bonding strength between PA6 and PP films, thereby improving the performance of the composite film.

[0008] The technical solution of the present invention is as follows:

[0009] An epoxy adhesive, named: N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide, with the structural formula as shown below:

[0010]

[0011] The preparation method of the epoxy adhesive of the present invention comprises the following steps:

[0012] (1) dissolving p-aminophenol and triethylamine in N,N-dimethylformamide to obtain a p-aminophenol-triethylamine mixed solution; dissolving adipoyl chloride in N,N-dimethylformamide to obtain adipoyl chloride solution; dropping the adipoyl chloride solution into the p-aminophenol-triethylamine mixed solution, stirring and reacting at 0 to 25° C. (preferably 15° C.) for 20 minutes to 1 hour (preferably 30 minutes), then filtering, collecting the filtrate and removing the solvent by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide;

[0013] The molar ratio of p-aminophenol, adipoyl chloride and triethylamine is 1:0.4:0.9 to 1:0.6:1.1, preferably 1:0.51:1.01;

[0014] During the reaction, the rotor stirring speed is 200-500 rpm, preferably 300 rpm;

[0015] The reaction formula is as follows:

[0016]

[0017] (2) mixing the N,N-bis(4-hydroxyphenyl)adipamide obtained in step (1) with epichlorohydrin, adding tetrabutylammonium bromide, and stirring the mixture at 70 to 100° C. (preferably 80° C.) for 2.5 to 4 h (preferably 3 h) to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixture is directly used in the next step without post-treatment.

[0018] The molar ratio of N,N-bis(4-hydroxyphenyl)adipamide to epichlorohydrin is 1:6 to 1:14, preferably 1:10;

[0019] The mass ratio of N,N-bis(4-hydroxyphenyl)adipamide to tetrabutylammonium bromide is 1:0.1 to 1:0.4, preferably 1:0.3;

[0020] During the reaction, the stirring speed is 200-350 rpm, preferably 300 rpm;

[0021] The reaction formula is as follows:

[0022]

[0023] (3) adding an aqueous sodium hydroxide solution to the mixed system of N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide in step (2), stirring and reacting at 50 to 80° C. (preferably 60° C.) for 2.5 to 4 hours (preferably 3 hours), and then post-treating to obtain an epoxy adhesive N,N-bis(4-(oxirane-2-methoxy)phenyl)adipamide;

[0024] The molar ratio of N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide to sodium hydroxide is 1:2 to 1:5, preferably 1:3;

[0025] The mass fraction of sodium hydroxide aqueous solution is 3-7%, preferably 5%;

[0026] During the reaction, the stirring speed is 200-350 rpm, preferably 300 rpm;

[0027] The post-treatment method is as follows: after the reaction is completed, the reaction solution is cooled to room temperature, a mixed solution of deionized water and epichlorohydrin in a volume ratio of 1:0.8 to 1:2 is added, stirred and washed, filtered, the filtrate is extracted with toluene, the extract is washed with deionized water, the solvent is removed by rotary evaporation and dried to obtain a product epoxy adhesive;

[0028] The reaction formula is as follows:

[0029]

[0030] The epoxy adhesive of the present invention can be used for bonding PA6 film and PP film, and the specific application method is as follows:

[0031] The epoxy adhesive of the present invention and bisphenol A type diglycidyl ether with an epoxy value of 0.51 mol / 100 g are uniformly mixed, and diethylenetriamine is added as a curing agent to obtain a mixed adhesive; the obtained mixed adhesive is uniformly coated on the film to bond the PP film and the PA6 film, and then placed in a hot press at 110° C. and pressurized at 2 MPa for 3 minutes to obtain a PP / PA composite film;

[0032] Preferably, the molar ratio of epoxy binder to bisphenol A diglycidyl ether is 1:5.5;

[0033] Preferably, the molar ratio of the curing agent diethylenetriamine to the epoxy groups in the mixed binder is 1:2;

[0034] After coating and tableting, the thickness of the glue layer is preferably 0.08 mm.

[0035] The advantages of the present invention are:

[0036] The present invention synthesizes a novel epoxy adhesive with amide bonds. On the basis of traditional non-polar epoxy resin, a polar group, amide bond, is introduced into the molecule, so that the epoxy adhesive and PA material have a stronger bonding strength through intermolecular forces (hydrogen bonds).

[0037] The present invention not only improves the wettability of the adhesive matrix to the PA polar material, but also can form a large number of hydrogen bonds between the adhesive and the polar material such as PA to achieve the purpose of enhancing the bonding. At the same time, the epoxy adhesive itself is non-polar, and the non-polar group has good compatibility with polypropylene during the curing process, and achieves good bonding to the PP film through molecular chain entanglement.

[0038] In summary, the epoxy adhesive provided by the present invention can significantly improve the bonding strength between PA6 and PP films. DETAILED DESCRIPTION

[0039] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0040] Example 1

[0041] Preparation of epoxy adhesive:

[0042] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0043] (2) 13.12 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 100° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0044] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 80°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 10.21 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0045] Application of epoxy adhesive bonding PA6 film and PP film:

[0046] 0.10g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.90g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0047] Example 2

[0048] Preparation of epoxy adhesive:

[0049] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0050] (2) 12.85 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 90° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0051] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 70°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 12.32 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0052] Application of epoxy adhesive bonding PA6 film and PP film:

[0053] 0.10g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.90g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0054] Example 3

[0055] Preparation of epoxy adhesive:

[0056] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0057] (2) 13.02 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 80° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0058] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 60°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 15.11 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0059] Application of epoxy adhesive bonding PA6 film and PP film:

[0060] 0.10g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.90g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0061] Example 4

[0062] Preparation of epoxy adhesive:

[0063] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0064] (2) 12.95 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 80° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0065] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 60°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 14.63 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0066] Application of epoxy adhesive bonding PA6 film and PP film:

[0067] 0.20g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.80g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0068] Example 5

[0069] Preparation of epoxy adhesive:

[0070] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0071] (2) 12.56 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 80° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0072] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 60°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 14.46 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0073] Application of epoxy adhesive bonding PA6 film and PP film:

[0074] 0.40g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.60g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0075] Example 6

[0076] Preparation of epoxy adhesive:

[0077] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0078] (2) 13.01 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 80° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0079] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 60°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 15.03 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0080] Application of epoxy adhesive bonding PA6 film and PP film:

[0081] 0.60g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.40g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0082] Example 7

[0083] Preparation of epoxy adhesive:

[0084] (1) 8.72 g of p-aminophenol and 7.32 g of adipoyl chloride were dissolved in 100 mL of N,N-dimethylformamide, and 8.08 g of triethylamine was added to the p-aminophenol-N,N-dimethylformamide solution and stirred evenly. The adipoyl chloride solution was slowly dripped into the p-aminophenol-triethylamine mixed solution, and the mixture was slowly stirred at 15° C. for 30 min. The filtrate was filtered to obtain the filtrate, and the excess solvent was removed by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide.

[0085] (2) 12.72 g of N,N-bis(4-hydroxyphenyl)adipamide prepared in step (1) was added to 31 mL of epichlorohydrin, and then transferred to a three-necked flask for reaction. 1.50 g of tetrabutylammonium bromide was added to the mixed solution, and the mixture was reacted at 80° C. for 3 h to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixed system was directly used in the next step without post-treatment.

[0086] (3) Add 7 g of 5% by mass sodium hydroxide aqueous solution to the N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide mixture in step (2), cool to 60°C for reaction for 3 h, stir, filter, extract, wash, and dry to finally obtain 14.71 g of epoxy adhesive N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide.

[0087] Application of epoxy adhesive bonding PA6 film and PP film:

[0088] 0.80g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.20g bisphenol A diglycidyl ether with an epoxy value of 0.51mol / 100g were mixed evenly, and then 0.12g diethylenetriamine was added as a curing agent to make a binder. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of binder was evenly coated on the 150mm*150mm area at the other end. Then, the PP and PA films were combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0089] Comparative Example 1

[0090] 1.00g N,N-bis(4-(ethylene oxide-2-methoxy)phenyl) adipamide and 0.12g diethylenetriamine were mixed evenly to prepare an adhesive. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of adhesive was evenly coated on the 150mm*150mm area at the other end. The PP and PA films were then combined into one, placed in a hot press at 110°C, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0091] Comparative Example 2

[0092] 1.00g of bisphenol A type diglycidyl ether with an epoxy value of 0.51mol / 100g and 0.12g of diethylenetriamine were mixed evenly to prepare an adhesive. 200mm*150mm PP and PA6 films were cut, and the 50mm*150mm area at one end was used as a blank area, and 1.12g of adhesive was evenly coated on the other end of 150mm*150mm. The PP and PA films were then combined into one, put into a hot press at 110℃, and pressurized at 2MPa for 3min to obtain a PP / PA composite film.

[0093] Example performance test results

[0094] Performance test: The peel strength of the composite materials prepared in the examples and comparative examples was tested with reference to GB / T 2791-1995 Adhesive T peel strength test method - flexible material to flexible material. The results are shown in Table 1.

[0095] Table 1. Performance test results of PA / PP composites bonded by adhesive

[0096]

Claims

1. An epoxy adhesive, named: N,N-bis(4-(ethylene oxide-2-methoxy)phenyl)adipamide, with the structural formula as shown below:

2. The method for preparing the epoxy adhesive according to claim 1, wherein: The steps include: (1) dissolving p-aminophenol and triethylamine in N,N-dimethylformamide to obtain a p-aminophenol-triethylamine mixed solution; dissolving adipoyl chloride in N,N-dimethylformamide to obtain adipoyl chloride solution; dropping the adipoyl chloride solution into the p-aminophenol-triethylamine mixed solution, stirring and reacting at 0-25° C. for 20 min-1 h, then filtering, collecting the filtrate and removing the solvent by rotary evaporation to obtain N,N-bis(4-hydroxyphenyl)adipamide; The reaction formula is as follows: (2) mixing the N,N-bis(4-hydroxyphenyl)adipamide obtained in step (1) with epichlorohydrin, adding tetrabutylammonium bromide, and stirring the mixture at 70-100° C. for 2.5-4 hours to obtain N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide. The mixture is directly used in the next step without post-treatment. The reaction formula is as follows: (3) adding an aqueous sodium hydroxide solution to the mixed system of N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide in step (2), stirring and reacting at 50-80° C. for 2.5-4 hours, and then post-treating to obtain an epoxy adhesive N,N-bis(4-(oxirane-2-methoxy)phenyl)adipamide; The reaction formula is as follows:

3. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of p-aminophenol, adipoyl chloride and triethylamine is 1:0.4:0.9 to 1:0.6:1.

1.

4. The preparation method according to claim 2, characterized in that: In step (2), the molar ratio of N,N-bis(4-hydroxyphenyl)adipamide to epichlorohydrin is 1:6 to 1:

14.

5. The preparation method according to claim 2, characterized in that: In step (2), the mass ratio of N,N-bis(4-hydroxyphenyl)adipamide to tetrabutylammonium bromide is 1:0.1 to 1:0.

4.

6. The preparation method according to claim 2, characterized in that: In step (3), the molar ratio of N,N-bis(4-(2-chloro-2-hydroxyethoxy)phenyl)adipamide to sodium hydroxide is 1:2 to 1:

5.

7. The preparation method according to claim 2, characterized in that: In step (3), the mass fraction of the sodium hydroxide aqueous solution is 3 to 7%.

8. The preparation method according to claim 2, characterized in that: In step (3), the post-treatment method is as follows: after the reaction is completed, the reaction solution is cooled to room temperature, a mixed solution of deionized water and epichlorohydrin in a volume ratio of 1:0.8 to 1:2 is added, stirred and washed, filtered, the filtrate is extracted with toluene, the extract is washed with deionized water, the solvent is removed by rotary evaporation and dried to obtain the product epoxy adhesive.

9. Use of the epoxy adhesive as claimed in claim 1 in bonding PA6 film and PP film.

10. The use according to claim 9, characterized in that The application method is as follows: The epoxy adhesive and bisphenol A type diglycidyl ether with an epoxy value of 0.51 mol / 100 g are uniformly mixed, and diethylenetriamine is added as a curing agent to obtain a mixed adhesive; the obtained mixed adhesive is uniformly coated on the film to bond the PP film and the PA6 film, and then placed in a hot press at 110° C. and pressurized at 2 MPa for 3 minutes to obtain a PP / PA composite film; The molar ratio of epoxy binder to bisphenol A diglycidyl ether is 1:5.5; The molar ratio of the curing agent diethylenetriamine to the epoxy group in the mixed binder is 1:2; After coating and tableting, the thickness of the glue layer is 0.08mm.

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