A multilayer recyclable ultra-high barrier composite film and a preparation process thereof

Abstract

The application relates to the technical field of research and development of recyclable high-barrier composite films, and discloses a multilayer recyclable ultrahigh-barrier composite film and a preparation process thereof, which comprises the following steps: preparing a carboxyl-functionalized ammonium bromide intercalation agent; through ion exchange reaction and electrostatic adsorption, the carboxyl-functionalized ammonium bromide intercalation agent is used to intercalate and modify montmorillonite nanosheets to prepare intercalation-modified montmorillonite; based on an esterification reaction mechanism, the intercalation-modified montmorillonite is used to modify and treat ethylene-vinyl alcohol copolymer to prepare montmorillonite-modified ethylene-vinyl alcohol copolymer; the montmorillonite-modified ethylene-vinyl alcohol copolymer is used as raw material to form a barrier layer; and a multilayer co-extrusion and flow casting process is adopted to prepare the composite film. The application provides a process for preparing a composite film, and a multilayer ultrahigh-barrier composite film with excellent barrier performance and mechanical properties is prepared, which has the characteristics of material integration and can realize recycling.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of research and development of recyclable high-barrier composite films, in particular to a multilayer recyclable ultrahigh-barrier composite film and a preparation process thereof. BACKGROUND

[0002] The barrier property of a material refers to the ability of the material to prevent small molecule gases such as oxygen, carbon dioxide, nitrogen, water vapor, fragrance and other organic solvent vapor from penetrating, and common barrier materials on the market mainly include polyvinylidene chloride, ethylene-vinyl alcohol copolymer, polyethylene naphthalate, nitrile-based resin, polyamide and the like. Among them, the ethylene-vinyl alcohol copolymer is widely used in the packaging field of food, medicine, chemicals and the like in the market due to excellent barrier property, convenient use and good mechanical property. However, a large number of hydroxyl groups exist in the traditional ethylene-vinyl alcohol copolymer, and the barrier property is reduced under high humidity, which limits the actual use of the ethylene-vinyl alcohol copolymer in the packaging field.

[0003] At present, the methods for improving the barrier property of a material mainly include biaxial orientation, surface coating modification, multilayer composite modification, blending modification and nanocomposite modification. The patent with the publication number CN102408624A discloses a montmorillonite-EVOH-PET composite material and a preparation method thereof, and the barrier property of the material can be improved through the interaction of the modified montmorillonite, ethylene-vinyl alcohol copolymer and polyethylene terephthalate.

[0004] It is found through retrieval that the montmorillonite nanosheet has good barrier property to small molecules, and the barrier property of the composite material can be significantly improved when the montmorillonite nanosheet is compounded with a polymer. However, the structure in which the montmorillonite nanosheet layers are closely packed through electrostatic interaction will lead to poor interfacial compatibility and weak interfacial force between the montmorillonite nanosheet and the polymer, and therefore the montmorillonite nanosheet is often modified by intercalation to improve the comprehensive performance of the composite material. SUMMARY

[0005] The application provides a multilayer recyclable ultrahigh-barrier composite film and a preparation process thereof. The montmorillonite nanosheet is modified by intercalation through ion exchange reaction and electrostatic adsorption, the ethylene-vinyl alcohol copolymer molecules are grafted onto the montmorillonite nanosheet layers through a chemical bonding method, the technical effect of improving the interfacial compatibility and interfacial force between the montmorillonite nanosheet and the ethylene-vinyl alcohol copolymer is achieved, and on this basis, a multilayer recyclable ultrahigh-barrier composite film is prepared through multilayer co-extrusion and flow casting process. The multilayer recyclable ultrahigh-barrier composite film has excellent barrier property and mechanical property, and can realize recycling function.

[0006] A preparation process of a multilayer recyclable ultrahigh-barrier composite film, comprising the following steps:

[0007] Step one: preparing a carboxyl functionalized ammonium bromide intercalation agent;

[0008] Step two: using ion exchange reaction and electrostatic adsorption, the carboxyl functional group of bromide ammonium intercalation agent is used to intercalate and modify the montmorillonite nanosheet, and an intercalation modified montmorillonite is prepared;

[0009] Step three: based on the esterification reaction mechanism, the intercalation modified montmorillonite is used to modify the ethylene-vinyl alcohol copolymer, and a montmorillonite modified ethylene-vinyl alcohol copolymer is prepared;

[0010] Step four: a composite film is prepared by using a multilayer co-extrusion and a flow casting process, and using the montmorillonite modified ethylene-vinyl alcohol copolymer and the ethylene-vinyl alcohol copolymer resin to form a barrier layer, using a low-density polyethylene resin as a raw material to form an intermediate layer, and using a maleic anhydride grafted low-density polyethylene resin as a raw material to form a bonding layer.

[0011] Preferably, the preparation method of the multilayer recyclable ultra-high barrier composite film is as follows:

[0012] Step S1-1: the composite film is set as an eleven-layer co-extrusion film, and the film structure is as follows:

[0013] The first layer: a low-density polyethylene resin layer, 20-40 parts by weight;

[0014] The second layer: a maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0015] The third layer: an ethylene-vinyl alcohol copolymer resin layer, 3-10 parts by weight;

[0016] The fourth layer: a maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0017] The fifth layer: a montmorillonite modified ethylene-vinyl alcohol copolymer layer, 3-10 parts by weight;

[0018] The sixth layer: a montmorillonite modified ethylene-vinyl alcohol copolymer layer, 8-15 parts by weight;

[0019] The seventh layer: a montmorillonite modified ethylene-vinyl alcohol copolymer layer, 3-10 parts by weight;

[0020] The eighth layer: a maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0021] The ninth layer: an ethylene-vinyl alcohol copolymer resin layer, 3-10 parts by weight;

[0022] The tenth layer: a maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0023] The eleventh layer: a low-density polyethylene resin layer, 20-40 parts by weight;

[0024] Step S1-2: Put each raw material into the hopper of the eleven screw extruders of the eleven-layer co-extrusion film casting machine group respectively, after mixing by stirring, the molten resin is converged at the die head through the flow divider, extruded through the die, cooled and wound to obtain a composite film with a thickness of 80-120 μm.

[0025] Preferably, the montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-I, and the preparation method of the montmorillonite modified EVOH-I is as follows:

[0026] Step S2-1: Based on the regioselectivity mechanism of olefin electrophilic addition orientation reaction (Markovnikov rule), strong acid catalyzes the addition of 1-hexene and 3-(dimethylamino) propionic acid to generate nonyl ester tertiary amine monomer;

[0027] Step S2-2: Using the nucleophilic substitution reaction mechanism, quaternary ammonium reaction occurs between the tertiary amine group of the nonyl ester tertiary amine monomer and the bromine functional group of 3-bromopropionic acid to generate nonyl ester carboxyl ammonium bromide intercalation agent I;

[0028] Step S2-3: The ammonium cation of the nonyl ester carboxyl ammonium bromide intercalation agent I undergoes ion exchange reaction with the interlayer sodium cation of the sodium-based montmorillonite nanosheet, and the nonyl ester carboxyl ammonium bromide intercalation agent I is adsorbed on the surface of the montmorillonite nanosheet by electrostatic attraction to prepare intercalation modified montmorillonite I;

[0029] Step S2-4: Based on the esterification reaction mechanism, ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite I to prepare the montmorillonite modified EVOH-I.

[0030] Preferably, the montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-I, and the preparation method of the montmorillonite modified EVOH-I is as follows:

[0031] Step S3-1: Using the nucleophilic substitution reaction mechanism, quaternary ammonium reaction occurs between the tertiary amine group of the N,N-dimethylcyclohexylamine and the bromine functional group of 3-bromopropionic acid to generate cyclohexyl carboxyl ammonium bromide intercalation agent II;

[0032] Step S3-2: The ammonium cation of the cyclohexyl carboxyl ammonium bromide intercalation agent II undergoes ion exchange reaction with the interlayer sodium cation of the sodium-based montmorillonite nanosheet, and the cyclohexyl carboxyl ammonium bromide intercalation agent II is adsorbed on the surface of the montmorillonite nanosheet by electrostatic attraction to prepare intercalation modified montmorillonite II;

[0033] Step S3-3: Based on the esterification reaction mechanism, ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite II to prepare the montmorillonite modified EVOH-II.

[0034] Preferably, the montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-III, and the preparation method of the montmorillonite modified EVOH-III is as follows:

[0035] Step S4-1: using the nucleophilic substitution reaction mechanism, the quaternary ammonium reaction of the tertiary amine group of N,N-dimethylaniline and the bromine functional group of 3-bromopropionic acid occurs to generate phenyl carboxyl ammonium bromide intercalation agent III;

[0036] Step S4-2: the ion exchange reaction of the ammonium cation of the phenyl carboxyl ammonium bromide intercalation agent III and the interlayer sodium cation of the sodium-based montmorillonite nanosheet occurs, and the phenyl carboxyl ammonium bromide intercalation agent III is adsorbed on the surface of the montmorillonite nanosheet by electrostatic interaction to prepare intercalation modified montmorillonite III;

[0037] Step S4-3: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite III to prepare the montmorillonite modified EVOH-III.

[0038] Preferably, the montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-IV, and the preparation method of the montmorillonite modified EVOH-IV is as follows:

[0039] Step S5-1: using the nucleophilic substitution reaction mechanism, the quaternary ammonium reaction of the tertiary amine group of N-methyldiphenylamine and the bromine functional group of 3-bromopropionic acid occurs to generate diphenyl carboxyl ammonium bromide intercalation agent IV;

[0040] Step S5-2: the ion exchange reaction of the ammonium cation of the diphenyl carboxyl ammonium bromide intercalation agent IV and the interlayer sodium cation of the sodium-based montmorillonite nanosheet occurs, and the diphenyl carboxyl ammonium bromide intercalation agent IV is adsorbed on the surface of the montmorillonite nanosheet by electrostatic interaction to prepare intercalation modified montmorillonite IV;

[0041] Step S5-3: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite IV to prepare the montmorillonite modified EVOH-IV.

[0042] Preferably, the montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-V, and the preparation method of the montmorillonite modified EVOH-V is as follows:

[0043] Step S6-1: using the nucleophilic substitution reaction mechanism, the quaternary ammonium reaction of the tertiary amine group of triphenylamine and the bromine functional group of 3-bromo-2-bromomethylpropionic acid occurs to generate hexaphenyl carboxyl ammonium bromide intercalation agent V;

[0044] Step S6-2: the ammonium cations of the hexaphenyl carboxylic ammonium bromide intercalation agent V and the interlayer sodium cations of the sodium-based montmorillonite nanosheet undergo ion exchange reaction, and the hexaphenyl carboxylic ammonium bromide intercalation agent V is adsorbed on the surface of the montmorillonite nanosheet by electrostatic action, to prepare the intercalation modified montmorillonite V;

[0045] Step S6-3: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite V, to prepare the montmorillonite modified EVOH-V.

[0046] The water vapor transmission rate of the multilayer recyclable ultrahigh barrier composite film prepared according to the above process is 0.17-0.45 g / (m 2 ·24h), the oxygen transmission rate is 0.11-0.39 cm 3 / (m 2 ·24h·0.1 MPa), the tensile strength is 31-69 MPa, and the tear strength is 41-73 kN / m.

[0047] Beneficial effects

[0048] The carboxyl functional quaternary ammonium salt intercalation agent is first synthesized, and then the ammonium cations of the quaternary ammonium salt intercalation agent and the interlayer sodium cations of the sodium-based montmorillonite nanosheet undergo ion exchange reaction and electrostatic adsorption, to intercalate and modify the montmorillonite nanosheet, and prepare the intercalation modified montmorillonite.

[0049] The intercalation modified montmorillonite is used to modify the ethylene-vinyl alcohol copolymer through the esterification reaction mechanism, to prepare the montmorillonite modified ethylene-vinyl alcohol copolymer, the montmorillonite modified ethylene-vinyl alcohol copolymer is used as a barrier layer, and a multilayer co-extrusion and flow casting process is used to prepare a composite film.

[0050] It is found through experiments that the composite film prepared by the application has the beneficial technical effects of significantly improved barrier performance and significantly enhanced overall mechanical performance.

[0051] The composite film prepared by the application has the feature of material integration and can realize recycling function. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The chemical reaction formula for synthesizing the nonyl ester-based tertiary amine monomer;

[0053] Figure 2 The chemical structural formula of the nonyl ester-based carboxylic ammonium bromide intercalation agent I;

[0054] Figure 3 The chemical structural formula of the cyclohexyl carboxylic ammonium bromide intercalation agent II;

[0055] Figure 4 Chemical structural formula of nonyl ester carboxyl ammonium bromide intercalation agent I;

[0056] Figure 5 Chemical structural formula of diphenyl carboxyl ammonium bromide intercalation agent IV;

[0057] Figure 6 Chemical structural formula of hexaphenyl carboxyl ammonium bromide intercalation agent V;

[0058] Figure 7 Barrier property test results of each composite film;

[0059] Figure 8 Mechanical property test results of each composite film. DETAILED DESCRIPTION

[0060] Experimental Example:

[0061] Experiment 1: Preparation of nonyl ester carboxyl ammonium bromide intercalation agent I, the synthesis process is as follows:

[0062] (1) Synthesis of nonyl ester tertiary amine monomer: based on the regioselectivity mechanism of olefin electrophilic addition orientation reaction (Markovnikov rule), strong acid catalyzes the addition of 1-hexene and 3-(dimethylamino) propionic acid to generate nonyl ester tertiary amine monomer, and the chemical reaction formula is as shown in Figure 1

[0063] Among them, the strong acid catalyst selects one of sulfuric acid, p-toluenesulfonic acid and fluoroboric acid; sulfuric acid is selected as the catalyst in this experimental example;

[0064] The specific reaction steps for synthesizing the nonyl ester tertiary amine monomer are as follows: 1.7 g of 1-hexene, 2.3 g of 3-(dimethylamino) propionic acid and 20 mL of toluene are added to a three-necked flask, under the action of nitrogen protection and mechanical stirring, the temperature is raised to 30°C and dissolved for 30 min, then 0.5 g of concentrated sulfuric acid is added to the three-necked flask, the temperature is raised to 80°C and stirred for 6 h, and then cooled and rotary evaporated to obtain the nonyl ester tertiary amine monomer;

[0065] (2) Synthesis of nonyl ester carboxyl ammonium bromide intercalation agent I: using the nucleophilic substitution reaction mechanism, the quaternary ammonium reaction of the tertiary amine group of the nonyl ester tertiary amine monomer with the bromine functional group of 3-bromopropionic acid is generated, and the chemical structural formula of the nonyl ester carboxyl ammonium bromide intercalation agent I is as shown in Figure 2

[0066] ​​The specific experimental steps for synthesizing the nonyl ester carboxyl ammonium bromide intercalator I are as follows: 2.0 g of nonyl ester tertiary amine monomer and 20 mL of toluene are added to a three-necked flask, under the protection of nitrogen and mechanical stirring, the temperature is raised to 40°C, after the temperature is stabilized, 10 mL of 3-bromopropionic acid solution (prepared from 1.5 g of 3-bromopropionic acid and 10 mL of toluene) is added dropwise to the three-necked flask, stirring is maintained at 40°C for 12 h of reaction, after cooling, rotary evaporation, washing with ethyl acetate, and vacuum drying, the nonyl ester carboxyl ammonium bromide intercalator I is obtained;

[0067] The nuclear magnetic resonance hydrogen spectrum of the nonyl ester carboxyl ammonium bromide intercalator I is characterized as follows: 1 H NMR (CDCl3, 400 MHz) δ: 0.85-0.88 (t, 3H), 1.24-1.42 (m, 7H), 1.64-1.75 (m, 2H), 2.66-2.78 (m, 4H), 3.32 (s, 6H), 3.74-3.78 (m, 4H, -N(CH2)2-)), 4.70-4.77 (m, 1H, -COO(CH)-); the active hydrogen in the carboxyl functional group of the nonyl ester carboxyl ammonium bromide intercalator I does not peak in the CDCl3 solvent.

[0068] Experiment two: preparing the cyclohexyl carboxyl ammonium bromide intercalator II, the synthesis method is as follows: using the nucleophilic substitution reaction mechanism, through the quaternary ammonium reaction of the tertiary amine group of N,N-dimethylcyclohexylamine and the bromine functional group of 3-bromopropionic acid, the cyclohexyl carboxyl ammonium bromide intercalator II is generated, the chemical structural formula is as shown in Figure 3 , the synthesis steps and synthesis reaction conditions are referred to the synthesis experiment of the nonyl ester carboxyl ammonium bromide intercalator I, and the difference between the synthesis experiment of the nonyl ester carboxyl ammonium bromide intercalator I and the synthesis experiment of the cyclohexyl carboxyl ammonium bromide intercalator II is that 1.3 g of N,N-dimethylcyclohexylamine is used to replace 2.0 g of nonyl ester tertiary amine monomer;

[0069] The nuclear magnetic resonance hydrogen spectrum of the cyclohexyl carboxyl ammonium bromide intercalator II is characterized as follows: 1 H NMR (CDCl3, 400 MHz) δ: 1.46-1.67 (m, 6H), 1.87-1.91 (m, 4H), 2.68-2.70 (t, 2H), 3.30 (s, 6H), 3.40-3.45 (m, 1H), 3.77-3.80 (t, 2H, -N(CH2)-); the active hydrogen in the carboxyl functional group of the cyclohexyl carboxyl ammonium bromide intercalator II does not peak in the CDCl3 solvent.

[0070] Experiment three: preparing the phenyl carboxyl ammonium bromide intercalator III, the synthesis method is as follows: using the nucleophilic substitution reaction mechanism, through the quaternary ammonium reaction of the tertiary amine group of N,N-dimethylphenylamine and the bromine functional group of 3-bromopropionic acid, the phenyl carboxyl ammonium bromide intercalator III is generated, the chemical structural formula is as shown in Figure 4The synthesis steps and synthesis reaction conditions thereof are shown in the synthesis experiment of nonyl ester carboxyl ammonium bromide intercalation agent I. The difference between the synthesis experiment of nonyl ester carboxyl ammonium bromide intercalation agent I and the synthesis experiment of the nonyl ester carboxyl ammonium bromide intercalation agent I is that 1.2 g of N,N-dimethylaniline is used to replace 2.0 g of nonyl ester tertiary amine monomer.

[0071] The nuclear magnetic resonance hydrogen spectrum of the phenyl carboxyl ammonium bromide intercalation agent III is characterized as follows: 1 H NMR (CDCI3, 400 MHz) δ: 2.76-2.79 (t, 2H), 3.74 (s, 6H), 4.21-4.24 (t, 2H, -N(CH2)-), 7.44-7.53 (m, 3H), 8.01-8.04 (m, 2H); the active hydrogen in the carboxyl functional group of the phenyl carboxyl ammonium bromide intercalation agent III does not peak in the CDCh solvent.

[0072] Experiment four: preparation of diphenyl carboxyl ammonium bromide intercalation agent IV, the synthesis method is: using the nucleophilic substitution reaction mechanism, through the tertiary amine group of N-methyl diphenylamine and the bromine functional group of 3-bromopropionic acid, quaternary ammonium reaction is generated, the chemical structural formula of diphenyl carboxyl ammonium bromide intercalation agent IV is as follows Figure 5 The synthesis steps and synthesis reaction conditions thereof are shown in the synthesis experiment of nonyl ester carboxyl ammonium bromide intercalation agent I. The difference between the synthesis experiment of nonyl ester carboxyl ammonium bromide intercalation agent I and the synthesis experiment of the nonyl ester carboxyl ammonium bromide intercalation agent I is that 1.2 g of N,N-dimethylaniline is used to replace 2.0 g of nonyl ester tertiary amine monomer;

[0073] The nuclear magnetic resonance hydrogen spectrum of the diphenyl carboxyl ammonium bromide intercalation agent IV is characterized as follows: 1 H NMR (CDCI3, 400 MHz) δ: 2.76-2.79 (t, 2H), 3.74 (s, 6H), 4.21-4.24 (t, 2H, -N(CH2)-), 7.44-7.53 (m, 3H), 8.01-8.04 (m, 2H); the active hydrogen in the carboxyl functional group of the phenyl carboxyl ammonium bromide intercalation agent III does not peak in the CDCh solvent.

[0074] Experiment five: preparation of hexaphenyl carboxyl ammonium bromide intercalation agent V, the synthesis method is: using the nucleophilic substitution reaction mechanism, through the tertiary amine group of triphenylamine and the bromine functional group of 3-bromo-2-bromomethyl propionic acid, quaternary ammonium reaction is generated, the chemical structural formula of hexaphenyl carboxyl ammonium bromide intercalation agent V is as follows Figure 6The specific experimental steps are shown as follows: 2.5 g of triphenylamine and 20 mL of toluene are added into a three-neck flask, under the protection of nitrogen and mechanical stirring, the temperature is raised to 40℃, after the temperature is stable, 10 mL of 3-bromo-2-bromomethyl propionic acid solution (prepared by 1.3 g of 3-bromo-2-bromomethyl propionic acid and 10 mL of toluene) is added dropwise into the three-neck flask, the stirring reaction is maintained at 40℃ for 20 h, after cooling, rotary evaporation, washing with ethyl acetate, and vacuum drying, hexaphenyl carboxyl ammonium bromide intercalation agent V is obtained;

[0075] The nuclear magnetic resonance hydrogen spectrum of hexaphenyl carboxyl ammonium bromide intercalation agent V is characterized as follows: 1 H NMR (CDCI3, 400 MHz) δ: 3.87-3.95 (m, 1H), 4.65-4.68 (dd, 4H, -N(CH2)-), 7.42-7.88 (m, 30H, Ar-H); the active hydrogen in the carboxyl functional group of hexaphenyl carboxyl ammonium bromide intercalation agent V does not peak in CDCl3 solvent.

[0076] Example 1:

[0077] Preparation of intercalation modified montmorillonite I: 10 g of sodium-based montmorillonite nanosheet and 50 mL of ethanol are added into a three-neck flask, ultrasonic is performed for 30 min, the temperature is raised to 70℃, and stirring and dispersion are performed for 2 h, then 50 mL of nonyl ester carboxyl ammonium bromide intercalation agent I solution (prepared by 3.5 g of nonyl ester carboxyl ammonium bromide intercalation agent I and 50 mL of ethanol, and the exchange capacity of ammonium cation is controlled to be 0.01 mol) is added dropwise into the three-neck flask, the stirring reaction is maintained at 70℃ for 4 h, hot filtration is performed, washing with ethanol is performed until no precipitate is detected in silver nitrate solution, vacuum drying and grinding are performed, and intercalation modified montmorillonite I is obtained;

[0078] Preparation of intercalation modified montmorillonite II: 2.8 g of cyclohexyl carboxyl ammonium bromide intercalation agent II is used to replace 3.5 g of nonyl ester carboxyl ammonium bromide intercalation agent I, and the preparation steps and experimental conditions of intercalation modified montmorillonite I are referred to, and intercalation modified montmorillonite II is prepared;

[0079] Preparation of intercalation modified montmorillonite III: 2.7 g of phenyl carboxyl ammonium bromide intercalation agent III is used to replace 3.5 g of nonyl ester carboxyl ammonium bromide intercalation agent I, and the preparation steps and experimental conditions of intercalation modified montmorillonite I are referred to, and intercalation modified montmorillonite III is prepared;

[0080] Preparation of intercalation modified montmorillonite IV: 3.4 g of diphenyl carboxyl ammonium bromide intercalation agent IV is used to replace 3.5 g of nonyl ester carboxyl ammonium bromide intercalation agent I, and the preparation steps and experimental conditions of intercalation modified montmorillonite I are referred to, and intercalation modified montmorillonite IV is prepared;

[0081] Preparation of intercalation modified montmorillonite V: 3.7 g of hexaphenyl carboxyl bromide ammonium intercalation agent V is used to replace 3.5 g of nonyl ester carboxyl bromide ammonium intercalation agent I, referring to the preparation steps and experimental conditions of intercalation modified montmorillonite I, intercalation modified montmorillonite V is prepared;

[0082] The sodium-based montmorillonite nanosheet is purchased from Zhejiang Fenghong Clay Co., Ltd., and its specifications are: purity 75%, cation exchange capacity 100 mmol / 100 g, and fineness 200 mesh.

[0083] Example 2:

[0084] Preparation of montmorillonite modified EVOH-I: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite I, and montmorillonite modified EVOH-I is prepared. The specific experimental steps are as follows: 25 g of ethylene-vinyl alcohol copolymer resin (EVOH) and 100 mL of N,N-dimethylformamide are added to a three-necked flask with a water separator, and under the action of mechanical stirring, the temperature is raised to 50°C and stirred for 2 h. Then 30 mL of intercalation modified montmorillonite I solution (prepared by 2 g of intercalation modified montmorillonite I and 30 mL of N,N-dimethylformamide) and 1.1 mL of concentrated sulfuric acid are added dropwise into the flask, and the temperature is raised to 80°C and stirred for 2 h. After cooling, it is poured into a polytetrafluoroethylene mold and dried in an oven at 60°C, 80°C and 100°C for 12 h to obtain montmorillonite modified EVOH-I;

[0085] Preparation of montmorillonite modified EVOH-II: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite II, and montmorillonite modified EVOH-II is prepared. The preparation method is: intercalation modified montmorillonite II is used to replace the above intercalation modified montmorillonite I, referring to the preparation steps and experimental conditions of montmorillonite modified EVOH-I, and montmorillonite modified EVOH-II is prepared.

[0086] Preparation of montmorillonite modified EVOH-III: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite III, and montmorillonite modified EVOH-III is prepared. The preparation method is: intercalation modified montmorillonite III is used to replace the above intercalation modified montmorillonite I, referring to the preparation steps and experimental conditions of montmorillonite modified EVOH-I, and montmorillonite modified EVOH-III is prepared.

[0087] Preparation of the montmorillonite modified EVOH-IV: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite IV to obtain the montmorillonite modified EVOH-IV, and the preparation method is as follows: the intercalation modified montmorillonite IV is used to replace the intercalation modified montmorillonite I described above, and the preparation steps and experimental conditions of the montmorillonite modified EVOH-I are referred to, so as to obtain the montmorillonite modified EVOH-IV;

[0088] Preparation of the montmorillonite modified EVOH-V: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite V to obtain the montmorillonite modified EVOH-V, and the preparation method is as follows: the intercalation modified montmorillonite V is used to replace the intercalation modified montmorillonite I described above, and the preparation steps and experimental conditions of the montmorillonite modified EVOH-I are referred to, so as to obtain the montmorillonite modified EVOH-V;

[0089] The ethylene-vinyl alcohol copolymer resin is purchased from Dongguan Kaisili Plastic Raw Material Co., Ltd., and its specifications are: E105B, Mn ~ 10000, and ethylene content 44%.

[0090] Example 3:

[0091] (1) Preparation of the composite film I, including the following steps:

[0092] Step one, the composite film I is set to be a eleven-layer co-extrusion film, and the film structure is as follows:

[0093] The first layer: a low-density polyethylene resin (LDPE) layer, 30 parts by weight;

[0094] The second layer: a maleic anhydride grafted low-density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0095] The third layer: an ethylene-vinyl alcohol copolymer resin (EVOH) layer, 5 parts by weight;

[0096] The fourth layer: a maleic anhydride grafted low-density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0097] The fifth layer: a montmorillonite modified EVOH-I layer, 5 parts by weight;

[0098] The sixth layer: a montmorillonite modified EVOH-I layer, 10 parts by weight;

[0099] The seventh layer: a montmorillonite modified EVOH-I layer, 5 parts by weight;

[0100] The eighth layer: a maleic anhydride grafted low-density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0101] The ninth layer: an ethylene-vinyl alcohol copolymer (EVOH) layer, 5 parts by weight;

[0102] The tenth layer: a maleic anhydride grafted low density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0103] The eleventh layer: a low density polyethylene resin (LDPE) layer, 30 parts by weight;

[0104] Step two: the raw materials in step one are respectively put into the hoppers of the eleven screw extruders of the eleven-layer co-extrusion film casting machine group, after mixing by stirring, the molten resins are converged at the die head through a flow divider, extruded through a die, cooled, and wound to obtain a composite film I with a thickness of 100 μm;

[0105] The process parameters of the screw extruder corresponding to the low density polyethylene resin (LDPE) layer are set as follows: the temperatures of the first to third zones are 110℃, 140℃, and 160℃ respectively, the flow channel temperature is 150℃, and the rotating speed is 30 r / min;

[0106] The process parameters of the screw extruder corresponding to the maleic anhydride grafted low density polyethylene resin (PE-g-MAH) layer are set as follows: the temperatures of the first to third zones are 115℃, 145℃, and 160℃ respectively, the flow channel temperature is 150℃, and the rotating speed is 15 r / min;

[0107] The process parameters of the screw extruder corresponding to the ethylene-vinyl alcohol copolymer (EVOH) layer are set as follows: the temperatures of the first to third zones are 180℃, 200℃, and 210℃ respectively, the flow channel temperature is 205℃, and the rotating speed is 40 r / min;

[0108] The process parameters of the screw extruder corresponding to the montmorillonite modified EVOH-I layer are set as follows: the temperatures of the first to third zones are 185℃, 205℃, and 220℃ respectively, the flow channel temperature is 210℃, and the rotating speed is 40 r / min;

[0109] The low density polyethylene resin is purchased from China Offshore Shell Petrochemical Co., Ltd., with a specification of 2420H, Mn ~ 180000, and MFR 2.0-2.5 g / 10 min; the maleic anhydride grafted low density polyethylene resin is purchased from Dongguan Tao Tao Plastic Raw Material Co., Ltd., with a specification of 4288, Mn ~ 130000, and a grafting rate of 4.5%.

[0110] (2) Preparation of composite film II: montmorillonite modified EVOH-II is used to replace the above montmorillonite modified EVOH-I, and the composite film II is prepared according to the preparation steps and experimental conditions of the composite film I.

[0111] (3) Preparation of composite film III: using montmorillonite modified EVOH-III instead of the above-mentioned montmorillonite modified EVOH-I, see the preparation steps and experimental conditions of composite film I, to prepare composite film III.

[0112] (4) Preparation of composite film IV: using montmorillonite modified EVOH-IV instead of the above-mentioned montmorillonite modified EVOH-I, see the preparation steps and experimental conditions of composite film I, to prepare composite film IV.

[0113] (5) Preparation of composite film V: using montmorillonite modified EVOH-V instead of the above-mentioned montmorillonite modified EVOH-I, see the preparation steps and experimental conditions of composite film I, to prepare composite film V.

[0114] (6) Preparation of basic composite film: see the preparation steps and experimental conditions of composite film I, and the difference between the preparation experiment of composite film I is that the montmorillonite modified EVOH-I is replaced by ethylene-vinyl alcohol copolymer resin, to prepare the basic composite film.

[0115] Performance test:

[0116] (1) The water vapor transmission amount of the film sample was tested according to GB / T 1037-2021, and the specific test steps were as follows: 30cm circular film sample was placed in a glass desiccator with environmental temperature of 25℃ and anhydrous calcium chloride as desiccant, and kept for 72h, then the barrier water vapor performance of the film sample was tested using W3 / 060 type water vapor transmission tester;

[0117] (2) The oxygen transmission amount of the film sample was tested according to GB / T 1038-2000, and the specific test steps were as follows: 30cm circular film sample was placed in a glass desiccator with environmental temperature of 25℃ and anhydrous calcium chloride as desiccant, and kept for 72h, then the barrier oxygen performance of the film sample was tested using Y110 type oxygen transmission tester;

[0118] (3) The tensile strength of the film sample was tested using Instron 5565 universal tensile testing machine, and the specific test steps were as follows: the film sample with a size of 150mm×20mm was fixed on the tensile testing machine, and the tensile test was carried out at a tensile rate of 5mm / min, the longitudinal and transverse tensile strength of the film sample was recorded, and the specific method was as follows:

[0119] Tensile strength (MPa) = tensile stress / (film sample width × film sample thickness)

[0120] (4) Selecting trousers-shaped tearing method, tear strength of the film sample is tested according to GB / T 16578.1-2008, and the specific test steps are as follows: a 75mm long straight incision is cut in the middle of a 150mm*50mm film sample in the 50mm size, and then the film sample is clamped on an Instron 5565 universal tensile testing machine, and the tear strength test item is selected to test, and the longitudinal and transverse tear strength of the film sample is recorded, and the specific method is as follows:

[0121] Tear strength (kN / m) = maximum tearing force / thickness of the film sample;

[0122] The experimental results are shown in Tables 1-2 below.

[0123] Table 1: Experimental results of barrier properties of each composite film

[0124]

[0125] Table 2: Experimental results of mechanical properties of each composite film

[0126]

[0127] According to the experimental data in Tables 1 and 2, the following figures are obtained: Figure 7 and Figure 8 By analyzing Figure 7 and Figure 8 the following conclusions can be drawn:

[0128] The composite film prepared by the application has achieved significant improvement in barrier properties and overall significant enhancement in mechanical properties.

Claims

1. A process for the preparation of a multilayer recyclable ultra-high barrier composite film, characterized in that, Comprise the following steps: Step one: preparation carboxyl functionalized ammonium bromide intercalation agent, the intercalation agent is one of intercalation agent I, intercalation agent II, intercalation agent III, intercalation agent IV, intercalation agent V; The chemical structure of intercalation agent I is as follows: ； The chemical structure of intercalation agent II is as follows: ； The chemical structure of intercalation agent III is as follows: ； The chemical structure of intercalation agent IV is as follows: ； The chemical structure of intercalation agent V is as follows: ； Step two: using ion exchange reaction and electrostatic adsorption, the carboxyl functionalized ammonium bromide intercalation agent is used to intercalate and modify sodium-based montmorillonite nanosheet, and intercalation modified montmorillonite is prepared; Step three: based on the esterification reaction mechanism, the intercalation modified montmorillonite is used to modify ethylene-vinyl alcohol copolymer, and montmorillonite modified ethylene-vinyl alcohol copolymer is prepared; Step four: eleven layer coextrusion film is set, and multilayer coextrusion and casting film process are used to prepare multilayer recyclable super high barrier composite film; The structure of eleven layer coextrusion film is: LDPE layer / PE-g-MAH layer / EVOH layer / PE-g-MAH layer / montmorillonite modified EVOH layer / montmorillonite modified EVOH layer / montmorillonite modified EVOH layer / PE-g-MAH layer / EVOH layer / PE-g-MAH layer / LDPE layer; The montmorillonite modified EVOH layer is prepared from montmorillonite modified ethylene-vinyl alcohol copolymer.

2. The process for the preparation of a multilayer recyclable ultra-high barrier composite film as claimed in claim 1, wherein, The preparation method of the multilayer recyclable super high barrier composite film is as follows: Step S2-1: the composite film is set as eleven layer coextrusion film, and the film structure is as follows: The first layer: low density polyethylene resin LDPE layer, 20-40 parts by weight; The second layer: maleic anhydride grafted low density polyethylene resin PE-g-MAH layer, 2-5 parts by weight; The third layer: ethylene-vinyl alcohol copolymer resin EVOH layer, 3-10 parts by weight; The fourth layer: maleic anhydride grafted low density polyethylene resin PE-g-MAH layer, 2-5 parts by weight; The fifth layer: montmorillonite modified EVOH layer, 3-10 parts by weight; The sixth layer: montmorillonite modified EVOH layer, 8-15 parts by weight; The seventh layer: montmorillonite modified EVOH layer, 3-10 parts by weight; The eighth layer: maleic anhydride grafted low density polyethylene resin PE-g-MAH layer, 2-5 parts by weight; The ninth layer: ethylene-vinyl alcohol copolymer resin EVOH layer, 3-10 parts by weight; The tenth layer: maleic anhydride grafted low density polyethylene resin PE-g-MAH layer, 2-5 parts by weight; The eleventh layer: low density polyethylene resin LDPE layer, 20-40 parts by weight; Step S2-2: each raw material in step S2-1 is respectively put into the hopper of the eleven screw extruders of eleven layer coextrusion film casting machine group, after stirring and mixing, the molten resin is converged at the die head through the flow divider, extruded, cooled and wound through the die head, and the composite film with a thickness of 80-120 μm is obtained.

3. The process for the preparation of a multilayer recyclable ultra-high barrier composite film as claimed in claim 1, wherein, The montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-I, and the preparation method of the montmorillonite modified EVOH-I is as follows: Step S3-1: Based on the regioselectivity mechanism of olefin electrophilic addition orientation reaction, which is Markovnikov rule, strong acid catalysis 1-hexene and 3-(dimethylamino) propionic acid addition to form nonyl ester tertiary amine monomer; Step S3-2: Using the mechanism of nucleophilic substitution reaction, quaternary ammonium reaction occurs between the tertiary amine group of nonyl ester tertiary amine monomer and the bromine function group of 3-bromopropionic acid, to generate nonyl ester carboxyl ammonium bromide intercalation agent I; Step S3-3: The ammonium cation of nonyl ester carboxyl ammonium bromide intercalation agent I and the interlayer sodium cation of sodium-based montmorillonite nanosheet occur ion exchange reaction, and nonyl ester carboxyl ammonium bromide intercalation agent I is adsorbed on the surface of montmorillonite nanosheet by electrostatic interaction, to prepare intercalation modified montmorillonite I; Step S3-4: Based on the esterification reaction mechanism, ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite I, to prepare montmorillonite modified EVOH-I.

4. The process for the preparation of a multilayer recyclable ultra-high barrier composite film as claimed in claim 1, wherein, The montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-II, and the preparation method of the montmorillonite modified EVOH-II is: Step S4-1: Using the mechanism of nucleophilic substitution reaction, quaternary ammonium reaction occurs between the tertiary amine group of N,N-dimethylcyclohexylamine and the bromine function group of 3-bromopropionic acid, to generate cyclohexyl carboxyl ammonium bromide intercalation agent II; Step S4-2: The ammonium cation of cyclohexyl carboxyl ammonium bromide intercalation agent II and the interlayer sodium cation of sodium-based montmorillonite nanosheet occur ion exchange reaction, and cyclohexyl carboxyl ammonium bromide intercalation agent II is adsorbed on the surface of montmorillonite nanosheet by electrostatic interaction, to prepare intercalation modified montmorillonite II; Step S4-3: Based on the esterification reaction mechanism, ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite II, to prepare montmorillonite modified EVOH-II.

5. The process for the preparation of a multilayer recyclable ultra-high barrier composite film as claimed in claim 1, wherein, The montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-III, and the preparation method of the montmorillonite modified EVOH-III is: Step S5-1: Using the mechanism of nucleophilic substitution reaction, quaternary ammonium reaction occurs between the tertiary amine group of N,N-dimethylphenylamine and the bromine function group of 3-bromopropionic acid, to generate phenyl carboxyl ammonium bromide intercalation agent III; Step S5-2: The ammonium cation of phenyl carboxyl ammonium bromide intercalation agent III and the interlayer sodium cation of sodium-based montmorillonite nanosheet occur ion exchange reaction, and phenyl carboxyl ammonium bromide intercalation agent III is adsorbed on the surface of montmorillonite nanosheet by electrostatic interaction, to prepare intercalation modified montmorillonite III; Step S5-3: Based on the esterification reaction mechanism, ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite III, to prepare montmorillonite modified EVOH-III.

6. The process for the preparation of a multilayer recyclable ultra-high barrier composite film as claimed in claim 1, wherein, The montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-IV, and the preparation method of the montmorillonite modified EVOH-IV is: Step S6-1: Using the mechanism of nucleophilic substitution reaction, quaternary ammonium reaction occurs between the tertiary amine group of N-methyl diphenylamine and the bromine function group of 3-bromopropionic acid, to generate diphenyl carboxyl ammonium bromide intercalation agent IV; Step S6-2: The ammonium cation of diphenyl carboxyl ammonium bromide intercalation agent IV and the interlayer sodium cation of sodium-based montmorillonite nanosheet occur ion exchange reaction, and diphenyl carboxyl ammonium bromide intercalation agent IV is adsorbed on the surface of montmorillonite nanosheet by electrostatic interaction, to prepare intercalation modified montmorillonite IV; Step S6-3: Based on the esterification reaction mechanism, ethylene-vinyl alcohol copolymer molecules are grafted on the surface of intercalation modified montmorillonite IV, to prepare montmorillonite modified EVOH-IV. Step S6-2: the ammonium cations of the diphenyl carboxy ammonium bromide intercalation agent IV and the sodium cations between the layers of the sodium-based montmorillonite nanosheets undergo ion exchange reaction, and the diphenyl carboxy ammonium bromide intercalation agent IV is adsorbed on the surface of the montmorillonite nanosheets by electrostatic interaction, to prepare the intercalation modified montmorillonite IV; Step S6-3: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite IV, to prepare the montmorillonite modified EVOH-IV.

7. The process for the preparation of a multilayer recyclable ultra-high barrier composite film as claimed in claim 1, wherein, The montmorillonite modified ethylene-vinyl alcohol copolymer is montmorillonite modified EVOH-V, and the preparation method of the montmorillonite modified EVOH-V is as follows: Step S7-1: using the nucleophilic substitution reaction mechanism, the quaternary ammonium reaction is generated between the tertiary amine group of triphenylamine and the bromine functional group of 3-bromo-2-bromomethyl propionic acid, to generate the hexaphenyl carboxy ammonium bromide intercalation agent V; Step S7-2: the ammonium cations of the hexaphenyl carboxy ammonium bromide intercalation agent V and the sodium cations between the layers of the sodium-based montmorillonite nanosheets undergo ion exchange reaction, and the hexaphenyl carboxy ammonium bromide intercalation agent V is adsorbed on the surface of the montmorillonite nanosheets by electrostatic interaction, to prepare the intercalation modified montmorillonite V; Step S7-3: based on the esterification reaction mechanism, the ethylene-vinyl alcohol copolymer molecules are grafted on the surface of the intercalation modified montmorillonite V, to prepare the montmorillonite modified EVOH-V.

8. A multilayer recyclable ultra-high barrier composite film prepared according to the process of any one of claims 1-7, characterized in that, said multilayer recyclable ultra-high barrier composite film has a water vapor transmission rate of 0.17-0.45 g / (m 2 •24h), an oxygen transmission rate of 0.11-0.39 cm 3 / (m 2 •24h•0.1 MPa), a tensile strength of 31-69 MPa, and a tear strength of 41-73 kN / m.

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