High barrier composite film, preparation method and application in IBC storage and transportation ocean transportation

Abstract

The application relates to the technical field of high-molecular composite film materials, in particular to a high-barrier composite film capable of being photodegraded, and discloses a high-barrier composite film, a preparation method and application in IBC storage and transportation ocean transportation, the composite film is a PE / TIE / PA / TIE / PE five-layer co-extrusion structure; the PE layer contains an allylized photosensitizer, and the PA layer contains an epoxy propylated photosensitizer. The application provides a preparation method of a PE / PA multi-layer co-extrusion composite film with a photocatalytic degradation function; the composite film prepared through the method has excellent comprehensive performance during storage and use (under light-proof conditions), meets the service working condition requirements of IBC lining bags; and can be efficiently degraded after being discarded and exposed to an ultraviolet light environment, so that the degradation period of the composite film in a natural light environment is significantly shortened, and the problem of persistent white pollution caused by the existing PE / PA composite film after being discarded is solved.

Description

Technical Field

[0001] This invention relates to the field of polymer composite film materials technology, specifically to a photodegradable high-barrier composite film, and more specifically to a high-barrier composite film, its preparation method, and its application in IBC storage and transportation in ocean shipping. Background Technology

[0002] IBCs (Intermediate Bulk Containers) are widely used in the storage and transportation of liquid or slurry cargoes in industries such as chemicals, pharmaceuticals, food, and coatings. An IBC typically consists of a rigid outer frame and a disposable flexible inner liner, with a nominal volume usually between 275L and 1000L. The inner liner plays a crucial role in containing and isolating the cargo, and must possess excellent mechanical strength, chemical inertness, gas barrier properties, and heat-sealing performance to meet the demanding requirements of long-haul ocean shipping.

[0003] The inner lining bags are mostly made of multi-layer co-extruded composite film composed of polyethylene (PE) and polyamide (PA, nylon). PE is a non-polar semi-crystalline polymer (surface energy approximately 28-35 mJ / m²). 2 PA possesses excellent chemical inertness, heat-sealing properties, and overall mechanical strength; PA is a highly polar semi-crystalline polymer (surface energy approximately 40-46 mJ / m²). 2 (The specific properties may vary slightly depending on the PA grade). It exhibits excellent barrier properties against O2, CO2, and organic solvent vapors. However, due to the significant difference in surface energy between PE and PA, and the large Flory-Huggins interaction parameter χ, they are thermodynamically highly incompatible. During direct co-extrusion, the interface lacks effective chemical bonding and molecular chain entanglement, resulting in extremely low interlayer peel strength (typically <1.0 N / 15 mm). Under the combined stress of vibration, impact, and hydrostatic pressure during ocean shipping, interlayer delamination failure is highly likely to occur.

[0004] To address the interfacial compatibility issue between PE and PA, a symmetrical five-layer co-extrusion structure of PE / TIE / PA / TIE / PE is commonly used in industry. The TIE layer is a maleic anhydride-grafted polyethylene (MAH-g-PE) bonding resin, and its interfacial bonding mechanism can be divided into the following two levels:

[0005] Firstly, chemical bonding with the PA layer: the five-membered cyclic anhydride on the side group grafted with MAH undergoes nucleophilic addition and ring-opening with the primary amino group (-NH2) at the PA chain end at the co-extrusion processing temperature (usually 200-250℃). Initially, an amide acid intermediate containing amide bonds (-CO-NH-) and free carboxylic acid (-COOH) is generated. Under high temperature conditions, it undergoes further dehydration and cyclization, and finally anchors to the PA interface with imide bonds (-CO-N(R)-CO-) as the main covalent bonding form.

[0006] Secondly, physical compatibility with the PE layer: The polyethylene main chain skeleton of MAH-g-PE is thermodynamically compatible with the adjacent PE structural layer (Flory-Huggins parameter χ≈0). During the melt co-extrusion process, sufficient molecular chain diffusion and chain segment entanglement occur at the interface between the two, and a continuous physical anchoring network is formed after cooling and crystallization.

[0007] The aforementioned synergistic mechanism of chemical bonding and physical compatibility enables the interlayer peel strength of the five-layer co-extruded film to reach 4-8 N / 15 mm (depending on the MAH grafting rate, processing technology and testing conditions), meeting the structural integrity requirements of IBC inner liner bags under storage and transportation conditions.

[0008] However, while disposable flexible inner lining bags offer convenience for storage and transportation, they also place significant pressure on the ecological environment. PE's degradation cycle in the natural environment exceeds several hundred years, and PA is also a recalcitrant polymer. Furthermore, the tightly bonded interlayer structure of the PE / PA multilayer composite makes component separation and recycling extremely difficult, rendering existing mechanical recycling processes technically and economically inadequate. Therefore, large quantities of discarded inner lining bags have extremely long degradation cycles in the natural environment, and the complex composite structure makes separation and recycling challenging, easily causing persistent white pollution after single-use disposal. Summary of the Invention

[0009] The technical problem to be solved by this invention is to provide a PE / PA multilayer co-extruded composite film with photocatalytic degradation function and its preparation method. During storage and transportation (under light-protected conditions), the composite film maintains excellent mechanical properties, barrier properties, heat-sealing properties and interlayer adhesion strength, meeting the service conditions requirements of IBC inner liner bags. After being discarded and exposed to ultraviolet light, the anthraquinone / TiO2 composite photosensitizing system embedded in the film is activated. Through the synergistic effect of singlet oxygen generated by type II photosensitization and hydroxyl radicals and superoxide anion radicals generated by TiO2 photocatalysis, the oxidation chain of PE and PA matrix is ​​efficiently broken down and degraded, thereby significantly shortening the degradation cycle of the composite film in natural light environment and solving the problem of persistent white pollution caused by existing PE / PA composite films after disposal.

[0010] A high-barrier composite membrane, wherein the composite membrane is a five-layer co-extruded structure of PE / TIE / PA / TIE / PE;

[0011] The PE layer contains an allylated photosensitizer, which is covalently bonded to the PE molecular chain via a free radical grafting reaction.

[0012] The PA layer contains an epoxypropylated photosensitizer, which is covalently bonded to the PA molecular chain through a ring-opening reaction between the epoxy group and the end group of the PA molecular chain.

[0013] Both the allylated photosensitizer and the epoxypropylated photosensitizer are composite photosensitizers formed by anthraquinone silane coupling agent anchored to the surface of nano-TiO2 via Ti-O-Si covalent bonds;

[0014] The TIE layer is a maleic anhydride-grafted polyethylene adhesive resin layer.

[0015] The composite membrane maintains structural stability under light-protected conditions and achieves oxidative degradation under ultraviolet light irradiation through the synergistic effect of anthraquinone photosensitization and nano-TiO2 photocatalysis.

[0016] Preferably, the allylated photosensitizer is a composite photosensitizer formed by an allyl-type anthraquinone silane coupling agent anchored to the surface of nano-TiO2 via Ti-O-Si covalent bonds;

[0017] Preferably, the mass ratio of allyl anthraquinone silane coupling agent to nano-TiO2 in the allylated photosensitizer is (0.15-0.20):1;

[0018] Preferably, the epoxypropylated photosensitizer is a composite photosensitizer formed by an epoxypropylated anthraquinone silane coupling agent anchored to the surface of nano-TiO2 via Ti-O-Si covalent bonds;

[0019] Preferably, the mass ratio of the epioxypropyl-type anthraquinone silane coupling agent to nano-TiO2 in the epioxypropylated photosensitizer is (0.08-0.12):1;

[0020] Preferably, the formulation and dosage of each layer of the high-barrier composite membrane are as follows:

[0021] The PE layer is formulated with 40-80wt% LDPE, 19-59wt% PE masterbatch and 0.1-1.5wt% antioxidant 1010, with the sum of the three components being 100wt%; the amount of PE layer used is 20-25 parts by weight.

[0022] The PA layer formulation consists of 40-80wt% PA6 and 20-60wt% PA masterbatch, with the sum of the two components being 100wt%; the amount of PA layer used is 40-50 parts by weight.

[0023] The TIE layer is formulated with 100wt% MAH-g-PE; the amount of TIE layer used is 3-8 parts by weight.

[0024] Preferably, the formulation of the PE masterbatch is as follows:

[0025] LDPE: 850-950 parts by weight;

[0026] Allylated photosensitizer: 80-120 parts by weight;

[0027] DCP: 3-8 parts by weight;

[0028] White oil: 8-12 parts by weight.

[0029] Preferably, the formulation of the PA masterbatch is as follows:

[0030] PA6: 850-950 parts by weight;

[0031] Epi-propylene photosensitizer: 80-120 parts by weight;

[0032] Stearic acid dispersant: 1.5-2 parts by weight.

[0033] A method for preparing a high-barrier composite membrane includes the following steps:

[0034] Step 1: Using 2-aminoanthraquinone as the starting material, allyl and glycidyl anthraquinone silane coupling agents were prepared through N-alkylation, allylation and epoxidation reactions, respectively.

[0035] Step 2: The trimethoxysilyl group of the allyl anthraquinone silane coupling agent is hydrolyzed into silanol in an aqueous organic solvent, and then subjected to a dehydration condensation reaction with nano-titanium dioxide in the presence of an acidic catalyst. The allylated photosensitizer is obtained through Ti-O-Si covalent bonding.

[0036] The glycidyl-type anthraquinone silane coupling agent was treated in the same way to prepare the glycidylated photosensitizer.

[0037] Step 3: DCP dissolved in white oil is premixed with allylated photosensitizer and then melt-blended with LDPE resin through a co-rotating twin-screw extruder, granulated, and dried to obtain PE masterbatch;

[0038] 40-50 wt% of PA6 resin in the total formulation is premixed with a pre-treated stearic acid epoxypropylated photosensitizer, and then melt-blended and granulated in a co-rotating twin-screw extruder under a high-shear screw configuration to obtain a pre-dispersed masterbatch. The pre-dispersed masterbatch is then premixed with the remaining amount of PA6 resin in the formulation and then subjected to reactive melt-blended extrusion in a co-rotating twin-screw extruder, granulated, and dried to obtain PA masterbatch.

[0039] Step 4: According to the formula of the high-barrier composite film, the high-barrier composite film is prepared by five-layer co-extrusion blown film process.

[0040] Preferably, the preparation method of the allyl anthraquinone silane coupling agent is as follows:

[0041] Using 2.1-2.8 molar equivalents of 2-aminoanthraquinone and 1 molar equivalent of 3-bromopropyltrimethoxysilane as raw materials, and potassium carbonate as an acid-binding agent, an N-monoalkylation reaction was carried out in anhydrous DMF to introduce a 3-trimethoxysilylpropyl chain onto the amino nitrogen to generate a secondary amine intermediate.

[0042] The lone pair electrons on the secondary amine nitrogen of the secondary amine intermediate undergo SN2 nucleophilic substitution of allyl bromide to generate an allyl anthraquinone silane coupling agent.

[0043] Preferably, the preparation method of the epoxypropyl anthraquinone silane coupling agent is as follows: in a neutral to weakly acidic anhydrous environment of the m-chloroperoxybenzoic acid / dichloromethane system, the terminal olefin of the allyl anthraquinone silane coupling agent undergoes a specific epoxidation reaction to generate the epoxypropyl anthraquinone silane coupling agent.

[0044] A high-barrier composite membrane is used to manufacture IBC inner liner bags. The IBC inner liner bags maintain structural integrity in a light-protected environment during storage and transportation, and achieve photocatalytic oxidation degradation under natural light after disposal.

[0045] The beneficial effects of this invention are:

[0046] (1) Photoresponsive controllable degradation: By embedding the anthraquinone-TiO2 composite photosensitizer into the PE and PA layers respectively in a covalent bond manner, the membrane properties remain stable during storage and transportation (in a light-protected environment) (the longitudinal tensile strength change rate is only 1.0%-1.6% after 720h indoor placement); after disposal, under ultraviolet light irradiation, the type II photosensitization mechanism of the anthraquinone group and the photocatalytic mechanism of TiO2 produce a synergistic effect, which significantly accelerates the oxidative degradation of PE and PA (the longitudinal tensile strength decrease rate reaches 39.6%-62.4% after 168h of UV irradiation, which is much higher than the 4.1% of the pure membrane of comparative example D1 and the 28.6% of the comparative example D2 membrane containing only unmodified TiO2), giving the PE / PA composite membrane the cyclical characteristics of stability during use and degradation after disposal.

[0047] (2) Excellent barrier properties: The synergistic effect of the lamellar barrier effect of nano-TiO2 in the photosensitizer and the rigid filling effect of the anthraquinone aromatic ring reduces the oxygen permeability of the composite membrane to 1.5-2.6 cm. 3 / (m 2 (24h·0.1MPa), water vapor transmission rate decreased to 1.9-2.8 g / (m²). 2 (24h) Compared with pure PE / PA film, the oxygen content is reduced by about 32%-61% and 20%-46% respectively, which significantly improves the protection capability of IBC inner liner bags for oxygen-sensitive and moisture-sensitive goods.

[0048] (3) Good mechanical and heat-sealing properties: The longitudinal tensile strength of the composite film in the example is 34-41 MPa, the transverse tensile strength is 30-37 MPa, the heat-sealing strength is 30-37 N / 15 mm, and the interlayer peel strength is 5.0-6.2 N / 15 mm, all of which meet the structural integrity requirements of IBC inner liner bags under ocean shipping conditions.

[0049] (4) Strong process compatibility: The photosensitizer is introduced in the form of masterbatch, which can be directly processed on the existing five-layer co-extrusion blown film production line without the need to modify the equipment, and the feasibility of industrial scale-up is high.

[0050] The molecular design logic and mechanism of action of the above-mentioned technical solution of the present invention are as follows:

[0051] Starting with the primary amino group of 2-aminoanthraquinone, a 3-trimethoxysilylpropyl chain and an allyl group are introduced sequentially via N-alkylation to form an allyl-type anthraquinone silane coupling agent. The allyl group is further epoxidized to glycidyl group to form a glycidyl-type anthraquinone silane coupling agent. This bridging molecule has three functions: (a) an anthraquinone photosensitive core; (b) a trimethoxysilyl anchoring end, which forms a Ti-O-Si bond through hydrolysis-condensation and covalently bonds with the TiO2 surface; and (c) a reactive terminal functional group, with the allyl group used for radical grafting with PE and the glycidyl group used for ring-opening grafting with the PA end group.

[0052] Using 2-aminoanthraquinone as the photosensitizing core, its anthraquinone parent nucleus possesses a high triplet quantum yield. Upon ultraviolet light excitation, it undergoes intersystem crossing (ISC) to the triplet state, and then, through a Type II photosensitization mechanism, it converts the ground-state triplet oxygen (…) 3 O2) sensitized to singlet oxygen ( 1 O2), 1 O2 can attack the CH bonds on the main chain of PE and PA, triggering a hydrogen extraction reaction and generating peroxide intermediates, which in turn leads to main chain degradation through β-fracture.

[0053] Nano-TiO2 (anatase type) acts as a semiconductor photocatalyst, generating photogenerated electron-hole pairs under ultraviolet light excitation. Generate respectively free radicals and Superoxide anion radicals and the two can work synergistically. This further accelerates the oxidative breakage of polymer chains;

[0054] After the anthraquinone group is covalently anchored to the TiO2 surface through a silane coupling agent, photogenerated carrier transfer can occur between the two, inhibiting the recombination of photogenerated electron-hole pairs in TiO2, improving the photocatalytic quantum efficiency, and achieving synergistic enhancement of anthraquinone photosensitization and TiO2 photocatalysis.

[0055] Using dicumyl peroxide (DCP) as a free radical initiator, the free radicals generated by the thermal decomposition of DCP extract hydrogen atoms from the PE main chain to generate macromolecular free radicals (PE·). PE· undergoes a free radical addition reaction with the allyl double bond on the surface of the photosensitizer to form a C-C covalent bond, thus chemically grafting the photosensitizer onto the PE molecular chain. This ensures the uniform dispersion and anchoring of the photosensitizer in the PE matrix and avoids the aggregation and migration of nanoparticles.

[0056] During the reactive melt blending and extrusion process, the epoxy group of the epidermalized photosensitizer reacts with the terminal amino group (-NH2) of the PA6 molecular chain to form a β-hydroxy secondary amine structure, and reacts with the terminal carboxyl group (-COOH) to form a β-hydroxy ester structure, thus chemically bonding the photosensitizer to the end of the PA6 molecular chain, achieving chemical anchoring and uniform dispersion in the PA matrix;

[0057] During storage and transportation, the IBC inner liner is in a dark or low-light environment, and the photosensitization / photocatalytic reaction is in a dormant state due to the lack of ultraviolet light excitation, so the mechanical properties, barrier properties and interlayer adhesion strength of the composite film remain stable.

[0058] During the disposal phase, the inner liner bag is exposed to natural light, activating the anthraquinone / TiO2 composite photosensitizing system and continuously generating... , , Reactive oxygen species such as PE and PA trigger an auto-oxidative chain degradation reaction in the main chain of PE and PA, which is macroscopically manifested as a significant decrease in mechanical strength and embrittlement and fragmentation of the membrane, thus accelerating the degradation process of the composite membrane. Detailed Implementation

[0059] Experimental Example 1:

[0060] Synthesis of the secondary amine intermediate: Using 2-aminoanthraquinone (2.5 eq) and 3-bromopropyltrimethoxysilane (1.0 eq) as starting materials, and potassium carbonate as an acid-binding agent, an N-monoalkylation reaction was carried out in anhydrous DMF, introducing a 3-trimethoxysilylpropyl chain onto the amino nitrogen to generate a secondary amine intermediate. Its chemical structural formula is as follows:

[0061] ;

[0062] The experimental steps are as follows:

[0063] Place the 250mL three-necked flask in a 120℃ oven to dry for more than 4 hours. While it is still hot, install the reflux condenser, constant pressure dropping funnel and magnetic stir bar. Purge with nitrogen three times and keep the entire process under nitrogen protection.

[0064] 2-Aminoanthraquinone (12.45 g, 55.75 mmol, 2.5 eq), anhydrous potassium carbonate (6.16 g, 44.6 mmol, 2.0 eq), and anhydrous sodium iodide (0.67 g, 4.46 mmol, 0.2 eq) were added sequentially, followed by the addition of pre-dried anhydrous DMF (50 mL, moisture <30 ppm), and the mixture was stirred at room temperature.

[0065] 3-Bromopropyltrimethoxysilane (5.43 g, 22.3 mmol, 1.0 eq) diluted with anhydrous DMF (10 mL, water <30 ppm) was placed in a constant pressure dropping funnel and slowly added dropwise over a period of not less than 60 minutes.

[0066] After the addition is complete, the temperature is raised to 95°C, and the mixture is stirred under a closed system for 12 hours; TLC monitoring (ethyl acetate / petroleum ether = 1:5) is performed until the reaction is complete.

[0067] Cool to room temperature, filter under nitrogen protection to remove inorganic salts, and evaporate the DMF from the filtrate under reduced pressure (≤5 mmHg) below 40°C.

[0068] The crude product was directly dissolved in a small amount of petroleum ether and eluted with a gradient of ethyl acetate / petroleum ether (0:100 to 15:85) on a neutral alumina column. The solvent was removed by vacuum evaporation and the product was dried under vacuum to obtain a secondary amine intermediate.

[0069] The product was characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 0.49-0.54 (t, 2H), 1.55-1.63 (m, 2H), 3.27-3.33 (m, 2H), 3.58 (s, 9H), 5.90-5.92 (t, 1H), 6.79-6.81 (d, 1H), 7.40 (s, 1H), 7.85-7.92 (m, 3H), 8.06-8.10 (m, 2H).

[0070] Experimental Example 2:

[0071] Synthesis of allyl anthraquinone silane coupling agents: The lone pair electrons on the secondary amine nitrogen of the secondary amine intermediate undergo SN2 nucleophilic substitution of allyl bromide to generate a tertiary amine compound, namely the allyl anthraquinone silane coupling agent, whose chemical structural formula is as follows:

[0072] ;

[0073] The experimental steps are as follows:

[0074] Under nitrogen protection, the secondary amine intermediate (6.44 g, 16.7 mmol, 1.0 eq) and anhydrous potassium carbonate (4.62 g, 33.4 mmol, 2.0 eq) were added to a dry 100 mL round-bottom flask, and anhydrous DMF (30 mL) was injected. The mixture was stirred at room temperature.

[0075] Allyl bromide (2.42 g, 20.0 mmol, 1.2 eq) was slowly added using a syringe, and the mixture was heated to 60 °C and stirred at that temperature for 10 hours. The reaction was monitored by TLC (ethyl acetate / petroleum ether = 1:5) until the reaction was complete.

[0076] Cool to room temperature, filter under nitrogen protection to remove inorganic salts, and remove DMF from the filtrate under high vacuum below 40°C.

[0077] The crude product was purified by neutral alumina column chromatography (elution with ethyl acetate / petroleum ether = 1:8 to 1:4 gradient), the solvent was removed by vacuum evaporation and the product was dried under vacuum to obtain an allyl anthraquinone silane coupling agent.

[0078] The product was characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 0.49-0.55(t, 2H), 1.54-1.64(m, 2H), 3.57-3.61(t, 2H), 3.58(s, 9H), 3.97-3 .99(d,2H),5.15-5.18(d,2H),5.82-5.92(m,1H),7.03-7.05(d,1H),7.46(s,1H) , 7.77-7.79(d, 1H), 7.88-7.92(m, 2H), 8.06-8.10(m, 2H).

[0079] Experiment Example 3:

[0080] Synthesis of glycidyl anthraquinone silane coupling agents: Under a neutral to weakly acidic anhydrous environment in the m-chloroperoxybenzoic acid / dichloromethane system, the terminal olefin of the allyl anthraquinone silane coupling agent undergoes a specific epoxidation reaction to generate a glycidyl anthraquinone silane coupling agent with the following chemical structural formula:

[0081] ;

[0082] The experimental steps are as follows:

[0083] Under nitrogen protection, allyl anthraquinone silane coupling agent (6.47 g, 15.2 mmol, 1.0 eq) was dissolved in anhydrous dichloromethane (30 mL) and placed in a 100 mL three-necked flask, which was then cooled to 0 °C in an ice-salt bath.

[0084] mCPBA (3.15g, ≥98%, 18.2mmol, 1.2eq) was added in four batches, 10 minutes apart.

[0085] After stirring at 0°C for 30 minutes, remove the ice-salt bath, slowly raise the temperature to room temperature, and continue stirring for 4 hours. Monitor the reaction by TLC (ethyl acetate / petroleum ether = 1:4) until the reaction is complete.

[0086] m-chlorobenzoic acid (mCBA) was removed by direct filtration through a sand core funnel. The filtrate was concentrated to about 5 mL under reduced pressure at below 35 °C and immediately passed through a neutral alumina short column (eluting with dichloromethane). The product components were quickly collected and concentrated under reduced pressure, and dried under high vacuum to obtain an epoxide-type anthraquinone silane coupling agent.

[0087] The product was characterized as follows: 1H NMR (CDCl3, 400MHz) δ: 0.49-0.55(t, 2H), 1.54-1.64(m, 2H), 2.46-2.52(m, 1H), 2.82-2.97(m, 2H ), 3.31-3.36(t, 2H), 3.46-3.47(d, 2H), 3.56(s, 9H), 7.03-7.05(d, 1H), 7.46 (s, 1H), 7.77-7.79 (d, 1H), 7.88-7.92 (m, 2H), 8.06-8.10 (m, 2H).

[0088] Experiment Example 4:

[0089] Preparation method of photosensitizer: The trimethoxysilyl group of anthraquinone silane coupling agent is hydrolyzed into silanol in an aqueous organic solvent, and then subjected to dehydration condensation reaction with nano-titanium dioxide dispersed in an anhydrous organic solvent in the presence of an acidic catalyst. The photosensitizer is formed by Ti-O-Si covalent bonding.

[0090] Preparation of allylated photosensitizer: 17.0 g of allyl-type anthraquinone silane coupling agent was dissolved in 100 mL of anhydrous methanol, and 10 mL of deionized water and 0.5 mL of glacial acetic acid were added for catalysis. The mixture was stirred at room temperature for 4 h to hydrolyze the trimethoxysilyl group into silanol. Separately, 100.0 g of nano-TiO2 (anatase type, particle size 15-20 nm) was ultrasonically dispersed in 500 mL of anhydrous methanol for 30 min. The hydrolysate was slowly added to the TiO2 dispersion, and the mixture was stirred at 60 °C for 12 h. After centrifugation (10000 rpm, 15 min), the mixture was washed twice with methanol, once with deionized water, and once with methanol. The mixture was then vacuum dried at 50 °C for 12 h to obtain the allylated photosensitizer.

[0091] Preparation of glycidylated photosensitizer: Take 10.0g of glycidyl-type anthraquinone silane coupling agent, and carry out hydrolysis-condensation reaction with 100.0g of nano-TiO2 according to the preparation method of allyl-type anthraquinone silane coupling agent, centrifuge, wash, and dry to obtain glycidylated photosensitizer.

[0092] Experiment Example 5:

[0093] Preparation of PE masterbatch:

[0094] Weigh the following raw materials by weight:

[0095] Low-density polyethylene resin (LDPE, model LD150DW): 900 parts;

[0096] Allylated photosensitizer: 100 parts;

[0097] Dicumyl peroxide (DCP, purity ≥99%): 5 parts;

[0098] White oil (used to dissolve DCP): 10 parts;

[0099] The preparation steps are as follows: First, DCP dissolved in white oil and allylated photosensitizer are premixed evenly at room temperature, and then fully mixed with LDPE resin. The mixture is then fed into a co-rotating twin-screw extruder through a hopper for melt blending reaction extrusion. After the extruded material is cooled in a water tank, it is granulated by a pelletizer and then vacuum dried at 60°C for 4 hours to obtain PE masterbatch.

[0100] The temperature settings for each zone of the twin-screw extruder are as follows: Zone 1 150℃, Zone 2 155℃, Zone 3 160℃, Zone 4 165℃, Zone 5 170℃, Zone 6 175℃, Zone 7 (distillation head) 175℃; preheating temperature 150℃; screw speed 110r / min.

[0101] Experimental Example 6:

[0102] Preparation of PA Masterbatch

[0103] Weigh the following raw materials by weight:

[0104] Nylon 6 resin (PA6, model F136): 900 parts;

[0105] Epi-propylene photosensitizer: 100 parts;

[0106] Dispersant (stearic acid, SA, ≥98%): 1.8 parts (based on 2wt% of the mass of TiO2 in the epoxypropylated photosensitizer);

[0107] The preparation steps are as follows:

[0108] Step 1: Raw material pretreatment

[0109] PA6 resin (F136) was dried in a vacuum oven at 100℃ for 8 hours until the moisture content dropped to below 0.1%, and then set aside for later use.

[0110] Stearic acid (SA) and glycidyl photosensitizer were premixed in a high-speed mixer at 800 r / min for 10 min to uniformly coat the TiO2 surface with stearic acid, thereby reducing the surface energy of the nanoparticles.

[0111] Step 2: Preparation of pre-dispersed masterbatch (first stage extrusion)

[0112] Take approximately 450 parts of the total amount of dried PA6 resin and 100 parts of pretreated stearic acid epoxypropylated photosensitizer and mix thoroughly.

[0113] The above premixed material was fed into a co-rotating twin-screw extruder through the main feed port, and melt-blended under a high-shear screw configuration, then extruded and granulated to obtain TiO2 / PA6 predispersed masterbatch.

[0114] Step 3: Reactive melt blending extrusion (second stage extrusion)

[0115] After the TiO2 / PA6 pre-dispersed masterbatch obtained in the second step is fully premixed with the remaining dried PA6 resin, it is fed into a co-rotating twin-screw extruder through the main feed port for reactive melt blending extrusion.

[0116] During the extrusion process, the epoxy groups in the epoxypropylated photosensitizer undergo a ring-opening grafting reaction with the end groups (-NH2 / -COOH) of the PA6 molecular chain in the melt shear field, thereby achieving chemical bonding and uniform dispersion of the photosensitizer in the PA6 matrix;

[0117] After being cooled in a water tank, the extruded material is granulated by a pelletizer and then vacuum dried at 80°C for 4 hours to obtain PA masterbatch.

[0118] The temperature settings for each zone of the twin-screw extruder are as follows: Zone 1 200℃, Zone 2 220℃, Zone 3 235℃, Zone 4 250℃, Zone 5 260℃, Zone 6 265℃, Zone 7 (distillation head) 260℃; preheating temperature 200℃; screw speed 150r / min.

[0119] Example 1:

[0120] Preparation of composite membrane I: Composite membrane I was prepared using a five-layer co-extrusion blown film process according to the formulation shown in Table 1;

[0121] Table 1 Formulation of each layer of composite membrane I

[0122] membrane weight Raw material formula Outer PE layer 22.5 60wt% LDPE (LD150DW) + 39wt% PE masterbatch + 1wt% antioxidant 1010 outer TIE layer 5 100wt% MAH-g-PE (Model 4288) PA layer 45 60wt% PA6 (F136) + 40wt% PA Masterbatch Inner TIE layer 5 100wt% MAH-g-PE (Model 4288) Inner PE layer 22.5 60wt% LDPE (LD150DW) + 39wt% PE masterbatch + 1wt% antioxidant 1010

[0123] The process parameters for the five-layer co-extrusion blown film are as follows:

[0124] The PE extruder has a three-zone temperature setting of 120℃ / 150℃ / 175℃, and a screw speed of 35r / min.

[0125] The TIE extruder has a three-zone temperature setting of 115℃ / 145℃ / 165℃ and a screw speed of 20r / min.

[0126] The PA extruder temperature is set in three zones: 200℃ / 230℃ / 260℃, and the screw speed is 45r / min;

[0127] The die head temperature was 240℃; the blow-up ratio was 2.8; the traction speed was 6.0m / min; the cooling air temperature was 15℃; and the film was wound up to obtain a composite film I with a total thickness of 120μm.

[0128] Example 2:

[0129] Preparation of composite membrane II: Composite membrane II was prepared according to the formulation shown in Table 2;

[0130] Table 2 Formulation of each layer of composite membrane II

[0131] membrane weight Raw material formula Outer PE layer 22.5 80wt% LDPE (LD150DW) + 19wt% PE masterbatch + 1wt% antioxidant 1010 outer TIE layer 5 100wt%MAH-g-PE (4288) PA layer 45 80wt% PA6 (F136) + 20wt% PA Masterbatch Inner TIE layer 5 100wt%MAH-g-PE (4288) Inner PE layer 22.5 80wt% LDPE (LD150DW) + 19wt% PE masterbatch + 1wt% antioxidant 1010

[0132] The five-layer co-extrusion blown film process parameters are the same as in Example 1, resulting in composite film II with a total thickness of 120 μm.

[0133] Example 3:

[0134] Preparation of composite membrane III: Composite membrane III was prepared according to the formulation shown in Table 3;

[0135] Table 3 Formulation of each layer of composite membrane III

[0136] membrane weight Raw material formula Outer PE layer 22.5 40wt% LDPE (LD150DW) + 59wt% PE masterbatch + 1wt% antioxidant 1010 outer TIE layer 5 100wt%MAH-g-PE (4288) PA layer 45 40wt% PA6 (F136) + 60wt% PA Masterbatch Inner TIE layer 5 100wt%MAH-g-PE (4288) Inner PE layer 22.5 40wt% LDPE (LD150DW) + 59wt% PE masterbatch + 1wt% antioxidant 1010

[0137] The five-layer co-extrusion blown film process parameters are the same as in Example 1, resulting in a composite film III with a total thickness of 120 μm.

[0138] Comparative Example 1:

[0139] Preparation of composite membrane D1: Composite membrane D1 was prepared using a five-layer co-extrusion blown film process according to the formulation shown in Table 4;

[0140] Table 4 Formulation of each layer of composite membrane D1

[0141] membrane weight Raw material formula Outer PE layer 22.5 99wt% LDPE (LD150DW) + 1wt% Antioxidant 1010 outer TIE layer 5 100wt%MAH-g-PE (4288) PA layer 45 100wt% PA6 (F136) Inner TIE layer 5 100wt%MAH-g-PE (4288) Inner PE layer 22.5 99wt% LDPE (LD150DW) + 1wt% Antioxidant 1010

[0142] The five-layer co-extrusion blown film process parameters are the same as in Example 1, resulting in a composite film D1 with a total thickness of 120 μm.

[0143] Comparative Example 2:

[0144] Preparation of composite membrane D2: According to the formulation shown in Table 5, composite membrane D2 was prepared by a five-layer co-extrusion blown film process;

[0145] Table 5 Formulation of each layer of composite membrane D2

[0146] membrane weight Raw material formula Outer PE layer 22.5 <![CDATA[60 wt% LDPE (LD150DW) + 39 wt% PE-TiO2 masterbatch + 1 wt% antioxidant 1010]]> outer TIE layer 5 100wt%MAH-g-PE (4288) PA layer 45 <![CDATA[60 wt% PA6 (F136) + 40 wt% PA-TiO2 masterbatch]]> Inner TIE layer 5 100wt%MAH-g-PE (4288) Inner PE layer 22.5 <![CDATA[60wt% LDPE (LD150DW) + 39wt% PE-TiO₂ masterbatch + 1wt% antioxidant 1010]]>

[0147] The five-layer co-extrusion blown film process parameters are the same as in Example 1, resulting in a composite film D2 with a total thickness of 120 μm;

[0148] (1) Preparation of PE-TiO2 masterbatch

[0149] Weigh the following raw materials by weight:

[0150] Low-density polyethylene resin (LDPE, model LD150DW): 900 parts;

[0151] Unmodified nano-TiO2 (anatase type, particle size 15-20nm): 100 parts;

[0152] The preparation steps of PE-TiO2 masterbatch are the same as those of PE masterbatch; however, PE-TiO2 masterbatch does not contain DCP or white oil.

[0153] (2) Preparation of PA-TiO2 masterbatch

[0154] Weigh the following raw materials by weight:

[0155] Nylon 6 resin (PA6, model F136): 900 parts;

[0156] Unmodified nano-TiO2 (anatase type, particle size 15-20nm): 100 parts;

[0157] Dispersant (stearic acid, SA, ≥98%): 2.0 parts (based on 2 wt% of the mass of unmodified nano-TiO2);

[0158] The preparation steps of PA-TiO2 masterbatch are the same as those of PA masterbatch.

[0159] Comparative Example 3:

[0160] Preparation of composite membrane D3: Composite membrane D3 was prepared using a five-layer co-extrusion blown film process according to the formulation shown in Table 6;

[0161] Table 6 Formulation of each layer of composite membrane D3

[0162] membrane weight Raw material formula Outer PE layer 22.5 60wt% LDPE (LD150DW) + 39wt% PE mixed masterbatch + 1wt% antioxidant 1010 outer TIE layer 5 100wt%MAH-g-PE (4288) PA layer 45 60wt% PA6 (F136) + 40wt% PA mixed masterbatch Inner TIE layer 5 100wt%MAH-g-PE (4288) Inner PE layer 22.5 60wt% LDPE (LD150DW) + 39wt% PE mixed masterbatch + 1wt% antioxidant 1010

[0163] The five-layer co-extrusion blown film process parameters are the same as in Example 1, resulting in a composite film D3 with a total thickness of 120 μm;

[0164] (1) Preparation of PE-mixed masterbatch:

[0165] Weigh the following raw materials by weight:

[0166] Low-density polyethylene resin (LDPE, model LD150DW): 900 parts;

[0167] Unmodified nano-TiO2 (anatase type, particle size 15-20nm): 100 parts;

[0168] Allyl anthraquinone silane coupling agent (product of Experimental Example 2, free state, grafted onto TiO2 surface without hydrolysis and condensation): 17 parts;

[0169] Dicumyl peroxide (DCP, purity ≥99%): 5 parts;

[0170] White oil: 10 parts;

[0171] The amount of allyl anthraquinone silane coupling agent used was 17 parts, which was consistent with the ratio of coupling agent to 100 parts TiO2 used in the preparation of allylated photosensitizer in Example 1.

[0172] The preparation steps of PE-mixed masterbatch are the same as those of PE masterbatch.

[0173] (2) Preparation of PA-mixed masterbatch

[0174] Weigh the following raw materials by weight:

[0175] Nylon 6 resin (PA6, model F136): 900 parts;

[0176] Unmodified nano-TiO2 (anatase type, particle size 15-20nm): 100 parts;

[0177] glycidyl anthraquinone silane coupling agent (product of Experimental Example 3, free state, grafted onto TiO2 surface without hydrolysis and condensation): 10 parts;

[0178] Dispersant (stearic acid, SA, ≥98%): 2.0 parts;

[0179] The amount of glycidyl anthraquinone silane coupling agent used was 10 parts, which was consistent with the ratio of coupling agent to 100 parts TiO2 used in Example 1 when preparing the glycidylated photosensitizer.

[0180] The preparation steps of PA-mixed masterbatch are the same as those of PA masterbatch.

[0181] Comparative Example 4:

[0182] Preparation of composite membrane D4: Composite membrane D4 was prepared using a five-layer co-extrusion blown film process according to the formulation shown in Table 7.

[0183] Table 7 Formulation of each layer of composite membrane D4

[0184] membrane weight Raw material formula Outer PE layer 22.5 60wt% LDPE (LD150DW) + 39wt% PE-secondary amine masterbatch + 1wt% antioxidant 1010 outer TIE layer 5 100wt%MAH-g-PE (4288) PA layer 45 60wt% PA6 (F136) + 40wt% PA-secondary amine masterbatch Inner TIE layer 5 100wt%MAH-g-PE (4288) Inner PE layer 22.5 60wt% LDPE (LD150DW) + 39wt% PE-secondary amine masterbatch + 1wt% antioxidant 1010

[0185] The five-layer co-extrusion blown film process parameters are the same as in Example 1, resulting in a composite film D4 with a total thickness of 120 μm;

[0186] (1) Preparation of secondary amine photosensitizers

[0187] 17.0 g of the secondary amine intermediate obtained in Experiment Example 1 was dissolved in 100 mL of anhydrous methanol. 10 mL of deionized water and 0.5 mL of glacial acetic acid were added as catalysts, and the mixture was stirred at room temperature for 4 h to hydrolyze the trimethoxysilyl group into silanol groups. Separately, 100.0 g of nano-TiO2 (anatase type, particle size 15-20 nm) was ultrasonically dispersed in 500 mL of anhydrous methanol for 30 min. The hydrolysate was slowly added to the TiO2 dispersion, and the mixture was stirred at 60 °C for 12 h. After centrifugation (10000 rpm, 15 min), the mixture was washed twice with methanol, once with deionized water, and once with methanol. The mixture was then vacuum dried at 50 °C for 12 h to obtain the secondary amine photosensitizer.

[0188] The anthraquinone group of this secondary amine photosensitizer is anchored to the surface of nano-TiO2 via Ti-O-Si covalent bonds, but its linker arm ends with a secondary amine group (-NH-) and does not contain allyl or glycidyl functional groups that can chemically react with the polymer matrix.

[0189] (2) Preparation of PE-secondary amine masterbatch:

[0190] Weigh the following raw materials by weight:

[0191] Low-density polyethylene resin (LDPE, model LD150DW): 900 parts;

[0192] Secondary amine photosensitizer: 100 parts;

[0193] The preparation steps of PE-secondary amine masterbatch are the same as those of PE masterbatch; however, PE-secondary amine masterbatch does not contain DCP or white oil.

[0194] (3) Preparation of PA-secondary amine masterbatch

[0195] Weigh the following raw materials by weight:

[0196] Nylon 6 resin (PA6, model F136): 900 parts;

[0197] Secondary amine photosensitizer: 100 parts;

[0198] Dispersant (stearic acid, SA, ≥98%): 1.8 parts (based on 2wt% of the mass of TiO2 in the secondary amine photosensitizer);

[0199] The preparation steps of PA-secondary amine masterbatch are the same as those of PA masterbatch.

[0200] Performance testing:

[0201] I. Barrier Performance Test:

[0202] (1) Using a Y110 oxygen permeability tester, the oxygen barrier performance of the samples was tested according to GB / T1038.1-2022 "Test method for gas permeability of plastic products films and sheets - Part 1: Differential pressure method". The test temperature was 23℃ and the relative humidity was 50%RH. Three samples were tested in each group and the average value was taken. The oxygen permeability was recorded.

[0203] (2) Using a TC-03 water vapor transmission rate tester, the water resistance of the samples was tested according to the weight gain method in GB / T1037-2021 "Determination of Water Vapor Transmission Performance of Plastic Films and Sheets by Cup Weight Gain and Weight Loss Method". The test temperature was 38℃ and the relative humidity was 90%RH. Three samples were tested in each group and the average value was taken. The water vapor transmission rate was recorded.

[0204] II. Heat sealing performance test:

[0205] A heat-sealing test was conducted on the samples. The sealing area was 15cm × 1cm, the heat-sealing temperature was 110℃, the heat-sealing pressure was 0.2MPa, and the heat-sealing time was 2.0s. The heat-sealed samples were tested according to QB / T2358-1998 "Test Method for Heat Seal Strength of Plastic Film Packaging Bags". The test speed was 300mm / min, the clamp spacing was 50mm, and 5 samples were tested in each group. The average value was taken and the heat seal strength was recorded.

[0206] III. Mechanical property testing:

[0207] According to GB / T1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", 150mm×20mm samples were subjected to tensile tests in the longitudinal (MD) and transverse (TD) directions at a tensile rate of 500mm / min. Five samples were tested in each direction for each group and the average value was taken. The longitudinal tensile strength and transverse tensile strength were recorded respectively.

[0208] IV. Interlayer peel strength test:

[0209] Referring to GB / T8808-1988 "Peel Test Method for Flexible Composite Plastic Materials", the T-type peel method was adopted, the sample width was 15mm, the tensile speed was 300mm / min, 5 samples were tested in each group and the average value was taken. The peel strength of the PA / TIE interface was recorded.

[0210] V. Degradation performance test:

[0211] (1) Storage and transportation stability test: The film sample was placed in a light-proof room at normal temperature and pressure for 720 h (30 d). The longitudinal tensile strength was determined according to the mechanical property test method, and the tensile strength change rate was calculated according to the following formula:

[0212] (2) Ultraviolet degradation test: The sample was placed in an ultraviolet aging test chamber (with 3 built-in 20W ultraviolet high-pressure mercury lamps, wavelength 313nm), with a vertical distance of 14.5cm between the lamp tube and the sample. It was continuously irradiated at room temperature and pressure for 168h (7d). After taking it out, the longitudinal tensile strength was measured and the rate of change was calculated.

[0213] Wherein, the rate of change = (initial value - value after placement or value after UV irradiation) / initial value × 100%;

[0214] The test results are shown in Table 8 below;

[0215] Table 8. Comprehensive performance test results of each membrane sample

[0216] Performance indicators Membrane D1 membrane D2 membrane D3 Membrane D4 Membrane I Membrane II Membrane III <![CDATA[Oxygen permeability (cm 3 / m 2 ·24 h·0.1 MPa)]]> 3.8 2.5 2.4 2.6 1.8 2.6 1.5 <![CDATA[Water vapor transmission rate (g / m 2 ·24 h)]]> 3.5 2.8 2.7 2.9 2.2 2.8 1.9 Heat seal strength (N / 15mm) 38 32 31 33 35 37 30 Longitudinal tensile strength (MPa) 42 35 34 36 39 41 34 Transverse tensile strength (MPa) 38 31 30 32 35 37 30 Peel strength (N / 15mm) 6.5 4.8 4.5 5.0 5.8 6.2 5.0 Change rate - indoor 720h (%) 0.6 1.8 2.4 1.4 1.2 1.0 1.6 Change rate - UV168h (%) 4.1 28.6 30.3 33.8 52.1 39.6 62.4

[0217] The following conclusions can be drawn from the test data in Table 8:

[0218] I. The enhancing effect of photosensitizers on the barrier properties of composite films

[0219] Oxygen permeation of membranes I-III in Examples (1.5-2.6 cm) 3 / m 2 ·24h·0.1MPa) and water vapor transmission rate (g / m 2 The photosensitivity (24h) was significantly lower than that of the comparative film D1 without photosensitizer. This is attributed to the labyrinth effect formed by the nano-TiO2 particles in the polymer matrix, which prolongs the diffusion path of gas molecules. In addition, the rigid structure of the anthraquinone aromatic ring increases the packing density of polymer chain segments. The two work together to enhance the barrier performance. The higher the amount of photosensitizer added (film III > film I > film II), the better the barrier performance.

[0220] II. Effects of photosensitizers on mechanical properties, heat-sealing properties, and interlayer peel strength

[0221] In Example I, the longitudinal tensile strength was 39 MPa, the transverse tensile strength was 35 MPa, the heat seal strength was 35 N / 15 mm, and the peel strength was 5.8 N / 15 mm. Compared with the comparative example film D1 (42 / 38 / 38 / 6.5), these strengths decreased by approximately 7% / 8% / 8% / 11%, respectively, but still met the service requirements for IBC inner liners. The introduction of inorganic nanoparticles disrupted the continuity and crystalline structure of the polymer matrix to some extent, but due to the photosensitizer's covalent bonding with the matrix (free radical grafting in the PE layer and ring-opening grafting in the PA layer), the interfacial bonding was good, and the decrease in mechanical properties was limited. The higher the amount of photosensitizer added (film III), the more significant the decrease in mechanical properties, requiring a balance between degradation efficiency and mechanical properties.

[0222] III. The decisive role of covalent bonding in photocatalytic degradation efficiency

[0223] The degradation behavior of each membrane was compared as follows, with the change rate of longitudinal tensile strength after 168 hours of UV accelerated aging as the core evaluation index:

[0224] (a) Comparative film D1 (pure PE / PA film, without photosensitizer): the change rate was only 4.1%, indicating that PE and PA have extremely low degradation rates under short-term ultraviolet irradiation.

[0225] (b) Comparative film D2 (containing unmodified nano-TiO2): change rate 28.6%; the photocatalytic effect of TiO2 can accelerate degradation, but because unmodified TiO2 has no chemical bond with the polymer matrix, it has poor dispersibility and is easy to agglomerate, thus limiting the photocatalytic efficiency.

[0226] (c) Comparative film D3 (physical blend of TiO2 and anthraquinone silane coupling agent, bonded to the TiO2 surface without hydrolysis and condensation): the change rate was 30.3%, only slightly higher than that of film D2. The free coupling agent failed to form an effective covalent bond with TiO2, thus failing to achieve the synergistic effect of anthraquinone photosensitization and TiO2 photocatalysis. Furthermore, the free coupling agent may undergo thermal degradation or migration during melt processing.

[0227] (d) Comparative film D4 (secondary amine photosensitizer, anthraquinone is anchored to the TiO2 surface through Ti-O-Si bonds, but the linker arm ends with a secondary amine group, lacking functional groups that react with the polymer matrix): the change rate was 33.8%, higher than that of films D2 and D3, confirming that the covalent bond between anthraquinone and TiO2 did indeed produce a photosensitization-photocatalysis synergistic effect; however, since the photosensitizer did not form a covalent bond with the polymer matrix, the dispersion uniformity and interfacial binding force were poor, which limited the effective transfer of reactive oxygen species to the matrix segments.

[0228] (e) Example Film I (In this invention, the photosensitizer is both anchored to anthraquinone on the TiO2 surface via Ti-O-Si bonds and covalently grafted to the PE / PA matrix via allyl / epoxypropyl groups respectively): The change rate is as high as 52.1%, far superior to all comparative examples. This fully demonstrates the core value of the ternary covalent bond design: the photosensitizer is uniformly anchored to the polymer matrix molecular chain via covalent bonds, ensuring uniform nanoscale dispersion while allowing the reactive oxygen species generated by photocatalysis / photosensitization ( , , It can directly attack the polymer chain segments covalently linked to it at the molecular scale, greatly shortening the diffusion distance of reactive oxygen species and improving degradation efficiency.

[0229] IV. Positive Correlation Between Photosensitizer Dosage and Degradation Efficiency

[0230] The UV 168h change rate of membrane III (60wt% photosensitizer masterbatch) was as high as 62.4%, while that of membrane I (40wt%) was 52.1% and that of membrane II (20wt%) was 39.6%. This indicates that the photocatalytic degradation efficiency is significantly improved with the increase of photosensitizer content. However, the mechanical properties and interlayer peel strength of membrane III also decreased. In practical applications, the formulation should be optimized according to performance requirements.

[0231] V. Dark-state stability during storage and transportation

[0232] The longitudinal tensile strength change rate of all the membranes in the embodiments after being placed indoors in the dark for 720 hours was only 1.0%-1.6%, which is close to that of the comparative membrane D1 (0.6%), confirming that the photosensitive system is in a dormant state under dark conditions and does not affect the structural stability of the composite membrane during storage and transportation. This time-response characteristic of stable performance during use and degradation after disposal is an important technical advantage of the present invention.

[0233] VI. Conclusion

[0234] This invention, through the molecular design and covalent bonding anchoring strategy of anthraquinone / TiO2 composite photosensitizer, endows PE / PA composite films with significant UV-responsive degradation function while basically maintaining their mechanical properties, barrier properties, and heat-sealing properties. This provides a practical and feasible technical solution for solving the white pollution problem after the disposal of IBC inner lining bags.

Claims

1. A high-barrier composite membrane, characterized in that, The composite film has a five-layer co-extrusion structure of PE / TIE / PA / TIE / PE; The PE layer contains an allylated photosensitizer, which is covalently bonded to the PE molecular chain via a free radical grafting reaction. The PA layer contains an epoxypropylated photosensitizer, which is covalently bonded to the PA molecular chain through a ring-opening reaction between the epoxy group and the end group of the PA molecular chain. The TIE layer is a maleic anhydride-grafted polyethylene adhesive resin layer. The composite membrane maintains structural stability under light-protected conditions and achieves oxidative degradation under ultraviolet light irradiation through the synergistic effect of anthraquinone photosensitization and nano-TiO2 photocatalysis. The allylated photosensitizer is a composite photosensitizer formed by an allyl-type anthraquinone silane coupling agent anchored to the surface of nano-TiO2 via Ti-O-Si covalent bonds; The mass ratio of allyl anthraquinone silane coupling agent to nano-TiO2 in the allylated photosensitizer is (0.15-0.20):1; The chemical structural formula of the allyl anthraquinone silane coupling agent is as follows: ； The glycidylated photosensitizer is a composite photosensitizer formed by glycidyl anthraquinone silane coupling agent anchored to the surface of nano-TiO2 via Ti-O-Si covalent bonds; The mass ratio of the epoxypropyl-type anthraquinone silane coupling agent to nano-TiO2 in the epoxypropylated photosensitizer is (0.08-0.12):1; The chemical structural formula of the epioxypropyl anthraquinone silane coupling agent is as follows: 。 2. The high-barrier composite membrane according to claim 1, characterized in that, The formulation and dosage of each layer of the high-barrier composite membrane are as follows: The PE layer is formulated with 40-80wt% LDPE, 19-59wt% PE masterbatch and 0.1-1.5wt% antioxidant 1010, with the sum of the three components being 100wt%; the amount of PE layer used is 20-25 parts by weight. The PA layer formulation consists of 40-80wt% PA6 and 20-60wt% PA masterbatch, with the sum of the two components being 100wt%; the amount of PA layer used is 40-50 parts by weight. The TIE layer is formulated with 100wt% MAH-g-PE; the amount of TIE layer used is 3-8 parts by weight. The formulation of the PE masterbatch is as follows: LDPE: 850-950 parts by weight; Allylated photosensitizer: 80-120 parts by weight; DCP: 3-8 parts by weight; White oil: 8-12 parts by weight; The formulation of the PA masterbatch is as follows: PA6: 850-950 parts by weight; Epi-propylene photosensitizer: 80-120 parts by weight; Stearic acid dispersant: 1.5-2 parts by weight.

3. The method for preparing a high-barrier composite membrane according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Using 2-aminoanthraquinone as the starting material, allyl and glycidyl anthraquinone silane coupling agents were prepared through N-alkylation, allylation and epoxidation reactions, respectively. Step 2: The trimethoxysilyl group of the allyl anthraquinone silane coupling agent is hydrolyzed into silanol in an aqueous organic solvent, and then subjected to a dehydration condensation reaction with nano-titanium dioxide in the presence of an acidic catalyst. The allylated photosensitizer is obtained through Ti-O-Si covalent bonding. The glycidyl-type anthraquinone silane coupling agent was treated in the same way to prepare the glycidylated photosensitizer. Step 3: DCP dissolved in white oil is premixed with allylated photosensitizer and then melt-blended with LDPE resin through a co-rotating twin-screw extruder, granulated, and dried to obtain PE masterbatch; 40-50 wt% of PA6 resin in the total formulation is premixed with a pre-treated stearic acid epoxypropylated photosensitizer, and then melt-blended and granulated in a co-rotating twin-screw extruder under a high-shear screw configuration to obtain a pre-dispersed masterbatch. The pre-dispersed masterbatch is then premixed with the remaining amount of PA6 resin in the formulation and then subjected to reactive melt-blended extrusion in a co-rotating twin-screw extruder, granulated, and dried to obtain PA masterbatch. Step 4: According to the formula of the high-barrier composite film, the high-barrier composite film is prepared by five-layer co-extrusion blown film process.

4. The method for preparing a high-barrier composite membrane according to claim 3, characterized in that, The preparation method of the allyl anthraquinone silane coupling agent is as follows: Using 2.1-2.8 molar equivalents of 2-aminoanthraquinone and 1 molar equivalent of 3-bromopropyltrimethoxysilane as raw materials, and potassium carbonate as an acid-binding agent, an N-monoalkylation reaction was carried out in anhydrous DMF to introduce a 3-trimethoxysilylpropyl chain onto the amino nitrogen to generate a secondary amine intermediate. The lone pair electrons on the secondary amine nitrogen of the secondary amine intermediate undergo SN2 nucleophilic substitution of allyl bromide to generate an allyl anthraquinone silane coupling agent.

5. The method for preparing a high-barrier composite membrane according to claim 4, characterized in that, The preparation method of the glycidyl anthraquinone silane coupling agent is as follows: in a neutral to weakly acidic anhydrous environment of the m-chloroperoxybenzoic acid / dichloromethane system, the terminal olefin of the allyl anthraquinone silane coupling agent undergoes a specific epoxidation reaction to generate the glycidyl anthraquinone silane coupling agent.

6. The application of a high-barrier composite membrane according to any one of claims 1-2, characterized in that, The high-barrier composite membrane is used to manufacture IBC inner liner bags, which maintain structural integrity in a light-protected environment during storage and transportation, and undergo photocatalytic oxidation degradation under natural light after disposal.

Images