Composite film for heat sealing of plastic cup and preparation method

Abstract

The invention relates to the technical field of antioxidant active sealing films, and discloses a composite film for heat sealing of a plastic cup and a preparation method, and the composite film is specifically characterized in that an outer layer formula comprises 20-30 parts by weight of 60-80 wt% of high density polyethylene resin and 20-40 wt% of linear low density polyethylene resin; the formula of the middle layer comprises 70-90 wt% of high-density polyethylene resin and 10-30 wt% of linear low-density polyethylene resin, and the dosage is 40-60 parts by weight; the formula of the inner layer comprises 60-80 wt% of low-density polyethylene resin and 20-40 wt% of antioxidant active polyethylene master batch, and the dosage is 20-30 parts by weight. According to the prepared film product, under the condition that heat sealing is not conducted, the loaded antioxidant is almost not released, the heat sealing technology can trigger the antioxidant to be released, and therefore the prepared film product can provide the antioxidant protection effect for the cup fresh juice product obtained after heat sealing is completed.

Description

Technical Field

[0001] This invention relates to the field of antioxidant active sealing film technology, and in particular to a composite film for heat sealing plastic cups with antioxidant active sealing function and its preparation method. Background Technology

[0002] Currently, freshly squeezed juice products delivered to consumers through food delivery platforms are mainly packaged in disposable food-grade polypropylene (PP) plastic cups. To prevent leakage of juice products during delivery, a sealing film is usually added to the cup opening using a heat sealing machine.

[0003] Freshly squeezed juice products are rich in vitamins, polyphenols, chlorophyll, anthocyanins, and aromatic substances that are easily oxidized by oxygen. Especially for freshly squeezed juice products that emphasize zero additives and cannot use antioxidant additives, even if ordinary sealing films (such as PP / PE films) are used to seal the cup opening, they can act as a physical barrier to delay microbial and external contamination. However, they cannot effectively prevent the oxidation of freshly squeezed juice products by headspace oxygen inside the cup and by trace amounts of oxygen that seeps through the packaging. In other words, for oxidation-sensitive freshly squeezed juice products, simple physical sealing is far from enough. Actively equipping the cup opening with an antioxidant active sealing film can ensure the freshness, taste, and nutritional value of freshly squeezed juice products delivered to consumers. This not only extends the quality control of freshly squeezed juice products to the last step, but also provides a new and feasible solution to the core pain points of the freshly squeezed juice product distribution industry from a packaging technology perspective. Summary of the Invention

[0004] This invention independently developed a composite film for heat sealing plastic cups with antioxidant active sealing function, which is compatible with food-grade polypropylene plastic cups. The heat sealing process triggers the release of food-grade antioxidants loaded in the film into the sealed space between the sealing film and the cup mouth, so as to achieve the technical effect of providing antioxidant protection for cup-packaged fresh juice products.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A composite film for heat-sealing plastic cups, wherein the product structure of the composite film is as follows:

[0007] Outer layer: The formula consists of 60-80 wt% high-density polyethylene resin and 20-40 wt% linear low-density polyethylene resin, with a dosage of 20-30 parts by weight;

[0008] Intermediate layer: The formulation consists of 70-90 wt% high-density polyethylene resin and 10-30 wt% linear low-density polyethylene resin, with a dosage of 40-60 parts by weight;

[0009] Inner layer: The formula consists of 60-80wt% low-density polyethylene resin and 20-40wt% antioxidant active polyethylene masterbatch, with a dosage of 20-30 parts by weight;

[0010] The preparation method of the antioxidant active polyethylene masterbatch is as follows:

[0011] Based on the silanol condensation reaction mechanism, long-chain alkylphenyl silane coupling agents were modified onto silanol-rich diatomaceous earth to prepare long-chain alkylphenyl functionalized diatomaceous earth.

[0012] Long-chain alkylphenyl functionalized diatomaceous earth physically adsorbs phenyl-containing food-grade antioxidants through its rich internal pores and adsorbs the antioxidants through π-π stacking interactions with the antioxidants on its rich surface phenyl content, thus producing long-chain alkylated antioxidant diatomaceous earth.

[0013] During the melt blending process, the long-chain alkyl groups on the surface of the long-chain alkylated antioxidant diatomaceous earth diffuse and entangle with the molecular chains of linear low-density polyethylene resin, thereby achieving uniform dispersion and firm bonding of diatomaceous earth in the linear low-density polyethylene resin matrix and obtaining antioxidant active polyethylene masterbatch.

[0014] Preferably, the mass ratio of diatomite to long-chain alkylphenyl silane coupling agent in the long-chain alkylphenyl functionalized diatomite is 1:0.075-0.15.

[0015] Preferably, the mass ratio of long-chain alkylphenyl functionalized diatomaceous earth to phenyl-containing food-grade antioxidant in the long-chain alkylated antioxidant diatomaceous earth is 1:1.5-2.5.

[0016] Preferably, the mass ratio of linear low-density polyethylene resin to long-chain alkylated antioxidant diatomaceous earth in the antioxidant active polyethylene masterbatch is 1:0.05-0.15.

[0017] Preferably, the phenyl-containing food-grade antioxidant is one of carvacrol and α-tocopherol.

[0018] Preferably, the thickness of the composite film is 30-80 μm.

[0019] A method for preparing a composite film for heat sealing plastic cups includes the following steps:

[0020] According to the formula, the raw materials of each layer are fed into the hoppers of the three single-screw extruders of the three-layer co-extrusion film blow molding unit. The molten resin is combined at the die head through the distributor, extruded and blow molded through the die head, cooled, and wound up to obtain a composite film.

[0021] The temperatures of each zone of the single-screw extruder corresponding to the outer layer are: Zone 1 115-125℃, Zone 2 145-160℃, Zone 3 170-180℃, flow channel temperature 160-170℃, and screw speed 25-35r / min.

[0022] The temperatures of each zone of the single-screw extruder corresponding to the intermediate layer are: Zone 1 115-125℃, Zone 2 150-165℃, Zone 3 170-180℃, the flow channel temperature is 160-170℃, and the screw speed is 30-40r / min.

[0023] The temperatures of each zone of the single-screw extruder corresponding to the inner layer are: Zone 1 105-115℃, Zone 2 140-155℃, Zone 3 155-165℃, the flow channel temperature is 145-155℃, and the screw speed is 20-30 r / min.

[0024] Preferably, the preparation method of the long-chain alkylphenylsilane coupling agent is as follows:

[0025] Based on the Friedel-Crafts alkylation mechanism, under the catalysis of Lewis acids, using octaphenyl-POSS as a starting material, a long-chain alkylphenylsilane coupling agent is synthesized by first undergoing an electrophilic substitution reaction between the phenyl functional group and the alkenyl functional group of a long-chain α-olefin, and then undergoing an electrophilic substitution reaction between the remaining phenyl functional group and the alkenyl functional group of vinyltrimethoxysilane. The molar ratio of octaphenyl-POSS, long-chain α-olefin, and vinyltrimethoxysilane participating in the reaction is controlled to be 1:0.95-0.99:0.95-0.99. The long-chain α-olefin is one of 1-tetradecene, 1-hexadecene, and 1-octadecene.

[0026] Preferably, the Lewis acid is one of anhydrous AlCl3 or anhydrous FeCl3.

[0027] An application of a composite film for heat sealing plastic cups, wherein the composite film triggers the release of antioxidants into the sealed space of the plastic cup through a heat sealing process, providing antioxidant protection for cup-packaged freshly squeezed juice products.

[0028] The beneficial effects of this invention are as follows:

[0029] Long-chain alkylphenyl silane coupling agents were synthesized from octaphenyl-POSS via a stepwise Friedel-Crafts alkylation reaction under Lewis acid catalysis. The specific process is as follows:

[0030] First, a long-chain alkyl group is introduced by reacting the phenyl group in 1 molar equivalent of octaphenyl-POSS with a slightly insufficient amount (0.95-0.99 molar equivalent) of a long straight-chain α-olefin; then, the remaining phenyl group in 1 molar equivalent of octaphenyl-POSS is reacted with a slightly insufficient amount (0.95-0.99 molar equivalent) of vinyltrimethoxysilane to introduce a silane coupling group.

[0031] Long-chain alkylphenyl silane coupling agents were modified onto the surface of diatomaceous earth rich in silanol groups. The diatomaceous earth then physically adsorbed phenyl-containing food-grade antioxidants through its rich internal pores. Furthermore, the phenyl functional groups on the surface of the diatomaceous earth also adsorbed the phenyl-containing food-grade antioxidants through π-π stacking interactions, thus loading the phenyl-containing food-grade antioxidants. Finally, in the molten state, the nonpolar long-chain alkane structures in the diatomaceous earth, which are highly similar in chemical structure to the linear low-density polyethylene resin molecular chains, penetrated and diffused into the amorphous region of the linear low-density polyethylene resin through thermal motion, and intertwined and tightly bound with the linear low-density polyethylene resin molecular chains, achieving a physical anchoring effect, thus producing antioxidant active polyethylene masterbatch.

[0032] Antioxidant active polyethylene masterbatch is used as a functional modification raw material for polyethylene resin. It is introduced into a three-layer co-extruded PE film and a composite film for heat sealing plastic cups with antioxidant active sealing function is obtained through a three-layer co-extruded blown film forming process.

[0033] Experimental results demonstrate that the antioxidants loaded in the film product prepared by this invention are hardly released under non-heat-sealing conditions, while the heat-sealing process can trigger the release of antioxidants. Therefore, the film product prepared by this invention can provide antioxidant protection for heat-sealed cup-packaged fresh juice products. Furthermore, the heat-sealing performance of the film product prepared by this invention meets the technical requirements of GB / T281176-2011 "Multilayer Co-extruded Films and Bags for Food Packaging". Detailed Implementation

[0034] Example 1:

[0035] The synthetic mechanism of long-chain alkylphenylsilane coupling agents is as follows:

[0036] Based on the Friedel-Crafts alkylation reaction mechanism, under the catalysis of Lewis acid, using octaphenyl-POSS as a starting material, a long-chain alkylphenyl silane coupling agent is synthesized by first undergoing an electrophilic substitution reaction between the phenyl functional group and the alkenyl functional group of a long straight-chain α-olefin, and then undergoing an electrophilic substitution reaction between the remaining phenyl functional group and the alkenyl functional group of vinyltrimethoxysilane. The molar ratio of octaphenyl-POSS, long straight-chain α-olefin, and vinyltrimethoxysilane participating in the reaction is controlled to be 1:0.97:0.99.

[0037] Among them, the long straight-chain α-olefin is one of 1-tetradecene, 1-hexadecene, and 1-octadecene. The general chemical structural formula of the long-chain alkylphenylsilane coupling agent synthesized accordingly is:

[0038] ;

[0039] In this embodiment, the long straight-chain α-olefin is selected as 1-octadecene, and the long-chain alkylphenylsilane coupling agent synthesized accordingly is an octadecylphenylsilane coupling agent, the chemical structural formula of which is:

[0040] ;

[0041] Among them, the Lewis acid is one of anhydrous AlCl3 and anhydrous FeCl3; in this embodiment, anhydrous AlCl3 is selected as the Lewis acid.

[0042] The specific experimental steps for octadecylphenylsilane coupling agent are as follows:

[0043] 1 g of octaphenyl-POSS, 0.32 mL of 1-octadecene, and 0.26 g of anhydrous AlCl3 were added to 40 mL of dichloroethane. The mixture was magnetically stirred for 20 min under nitrogen protection. The temperature was adjusted to 40 °C and the reaction was maintained at this temperature for 8 h. Then, 0.15 mL of vinyltrimethoxysilane was added, the temperature was raised to 75 °C, and the reaction was maintained at this temperature for 10 h. The mixture was cooled to room temperature, filtered under reduced pressure, and the crude product was collected. The crude product was washed with deionized water and methanol, and then further extracted with methanol and dichloroethane using a Soxhlet extractor for 12 h each. Finally, the product was dried in a vacuum drying oven at 70 °C for 12 h to obtain the octadecylphenylsilane coupling agent.

[0044] The 1H NMR characterization results of the octadecylphenylsilane coupling agent are as follows:

[0045] 1 H NMR (400MHz, CDCl3, δ, ppm): 0.88-0.90 (t, 3H), 0.95-1.10 (m, 2H), 1.27-1.35 (m, 30H), 1.58-1.64 (m, 2H), 2. 53-2.66(m, 4H), 3.57(s, 9H), 7.10-7.15(m, 4H), 7.26-7.34(m, 18H), 7.43-7.45(d, 4H), 7.50-7.53(m, 12H);

[0046] The specific experimental steps for long-chain alkylphenyl functionalized diatomaceous earth are as follows:

[0047] Add 2g of diatomaceous earth that has passed through a 200-mesh standard sieve to a mixed solution of 40mL deionized water and 40mL anhydrous ethanol, and sonicate for 20min. Add 0.2g of octadecylphenylsilane coupling agent, heat to 50℃ and stir for 1h at 300r / min. Filter, wash with deionized water, dry in an 80℃ drying oven for 8h, and then pass through a 200-mesh standard sieve to obtain long-chain alkylphenyl functionalized diatomaceous earth.

[0048] The specific experimental steps for long-chain alkylated antioxidant diatomaceous earth are as follows:

[0049] Add 2g of long-chain alkylphenyl functionalized diatomaceous earth and 4.5mL of carvacrol to a vacuum filtration flask. Mix at 300r / min for 10min and then vacuum filter. Repeat the operation 10 times, 30s each time. After filtration, transfer the mixture to a centrifuge tube and centrifuge at 5000r / min for 5min. Collect the supernatant in a vacuum filtration flask and repeat the operation for a second centrifugation. Finally, dry in a vacuum drying oven at 60℃ for 10h to obtain long-chain alkylated antioxidant diatomaceous earth.

[0050] The specific experimental steps for antioxidant active polyethylene masterbatch are as follows:

[0051] Nine parts by weight of linear low-density polyethylene (model 7042) and one part by weight of long-chain alkylated antioxidant diatomaceous earth were mixed evenly in a high-speed mixer and then added to the hopper of a twin-screw extruder for melt extrusion granulation to obtain antioxidant active polyethylene masterbatch.

[0052] The process parameters for the twin-screw extruder are set as follows: heating section temperature 150℃, mixing section temperature 155℃, extrusion section temperature 160℃, and screw speed 30r / min.

[0053] Example 2:

[0054] A composite film I for heat-sealing plastic cups with antioxidant active sealing function, the product structure of which consists of the following layers arranged in sequence:

[0055] Outer layer: The formula is 70wt% high-density polyethylene resin (model DGDX-6095) and 30wt% linear low-density polyethylene resin (model 7042), with a dosage of 25 parts by weight;

[0056] Intermediate layer: The formulation consists of 80wt% high-density polyethylene resin (model DGDX-6095) and 20wt% linear low-density polyethylene resin (model 7042), with a dosage of 50 parts by weight.

[0057] Inner layer: The formula consists of 80wt% low-density polyethylene resin (model Q281) and 20wt% antioxidant active polyethylene masterbatch, with a dosage of 25 parts by weight.

[0058] The preparation method of composite film I for heat sealing of plastic cups includes the following specific steps:

[0059] The raw materials of each layer are fed into the hoppers of the three single-screw extruders in the three-layer co-extrusion film blow molding unit according to the formula dosage. The raw materials are stirred and mixed evenly. The molten resin is collected at the die head through the distributor and blow molded through the die head. After cooling and winding, a composite film I with a thickness of 60μm is obtained.

[0060] The temperatures of each zone of the single-screw extruder corresponding to the outer layer are: Zone 1 120℃, Zone 2 150℃, Zone 3 175℃, flow channel temperature 165℃, and screw speed 30r / min.

[0061] The temperatures of each zone of the single-screw extruder corresponding to the intermediate layer are: Zone 1 120℃, Zone 2 155℃, Zone 3 175℃, runner temperature 165℃, and screw speed 35r / min.

[0062] The temperatures of each zone of the single-screw extruder corresponding to the inner layer are: Zone 1 110℃, Zone 2 145℃, Zone 3 160℃, runner temperature 155℃, and screw speed 25r / min.

[0063] The conditions for the extrusion blow molding process are: traction speed of 5m / min, blown film die head diameter of 60mm, and blow-up ratio of 2.4.

[0064] Example 3:

[0065] The preparation method of composite membrane II differs from that of composite membrane I only in that the inner layer is composed of 70 wt% low-density polyethylene resin (model Q281) and 30 wt% antioxidant active polyethylene masterbatch, with a dosage of 25 parts by weight.

[0066] Example 4:

[0067] The preparation method of composite membrane III differs from that of composite membrane I only in that the inner layer is formulated with 60 wt% low-density polyethylene resin (model Q281) and 40 wt% antioxidant active polyethylene masterbatch, and the amount used is 25 parts by weight.

[0068] Performance testing:

[0069] I. Antioxidant Experiment:

[0070] Antioxidant experiment of the composite film produced on the same day: The composite film was sealed with a PP plastic cup using an HSG-C type heat sealer. The heat sealing temperature was 160℃, the heat sealing pressure was 0.1MPa, and the heat sealing time was 1s. 0.5g of the heat-sealed composite film was weighed, cut into small pieces, and added to 10mL of anhydrous ethanol for soaking. It was then stored in a 37℃ shaking incubator in the dark and sealed. 7.89mg of DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) was weighed and dissolved in 100mL of anhydrous ethanol. The solution was then transferred to a 200mL volumetric flask and diluted to volume to obtain a 0.1mmol / L DPPH ethanol solution. The supernatant of 1mL of the composite film anhydrous ethanol solution was added to 1mL of 0... The DPPH ethanol solution was mixed thoroughly in 0.1 mmol / L and allowed to stand in the dark for 1 hour. The absorbance at 517 nm was then measured using a UV spectrophotometer. The formula for the DPPH free radical scavenging rate is: Free radical scavenging rate (%) = (A0 - A1 / A0) × 100%, where A0 is the absorbance of the DPPH ethanol solution and A1 is the absorbance of the DPPH ethanol solution after adding the supernatant. The antioxidant performance of the heat-sealed composite film was evaluated using the DPPH free radical scavenging rate method. The DPPH ethanol solution was a purple solution with the highest absorbance at 517 nm. When the antioxidant reacted with DPPH, the purple solution would fade and the absorbance would decrease.

[0071] Antioxidant test of composite film placed indoors at room temperature for 90 days: Following the antioxidant test method for composite film produced on the same day, an antioxidant test was conducted on the composite film placed indoors at room temperature for 90 days. The test results are recorded in Table 1:

[0072] Table 1. Experimental results of the antioxidant properties of the composite membrane.

[0073] Product Number Free radical scavenging rate on day 0 (%) Free radical scavenging rate on day 90 (%) Composite membrane I 83.9 83.8 Composite membrane II 88.0 88.1 Composite membrane III 90.1 89.5

[0074] II. The heat-sealing performance of the composite film was tested according to QB / T 2358-1998 "Test Method for Heat Seal Strength of Plastic Film Packaging Bags". The composite film was sealed with a PP plastic cup using an HSG-C type heat sealer. The heat-sealing temperature was 160℃, the heat-sealing pressure was 0.1MPa, the heat-sealing time was 1s, the distance between the clamps was 50mm, and the test speed was 300mm / min. The peel strength of the composite film was tested according to GB / T 8808-1988 "Peel Strength Test Method for Flexible Composite Plastic Materials". The sample size was 15mm and the length was 200mm. The test speed was 300mm / min. The test results are recorded in Table 2.

[0075] Table 2. Experimental results of heat-sealing performance of composite films

[0076] Product Number Heat seal strength (N / 15mm) Peel strength (N / 15mm) Composite membrane I 16.3 7.2 Composite membrane II 15.1 8.1 Composite membrane III 13.9 7.7

[0077] The heat-sealing strength of the composite film prepared by this invention meets the technical requirements of GB / T 281176-2011 "Multilayer Co-extruded Films and Bags for Food Packaging" regarding a heat-sealing strength ≥10N / 15mm (material thickness R, 0.051mm≤R<0.1mm);

[0078] Furthermore, its peel strength also meets the technical requirements of GB / T 281176-2011 "Multilayer Co-extruded Films and Bags for Food Packaging" regarding peel strength ≥4N / 15mm (material thickness R, 0.051mm≤R<0.1mm).

Claims

1. A composite film for heat-sealing plastic cups, characterized in that, The product structure of the composite membrane is as follows: Outer layer: The formula consists of 60-80 wt% high-density polyethylene resin and 20-40 wt% linear low-density polyethylene resin, with a dosage of 20-30 parts by weight; Intermediate layer: The formulation consists of 70-90 wt% high-density polyethylene resin and 10-30 wt% linear low-density polyethylene resin, with a dosage of 40-60 parts by weight; Inner layer: The formula consists of 60-80wt% low-density polyethylene resin and 20-40wt% antioxidant active polyethylene masterbatch, with a dosage of 20-30 parts by weight; The preparation method of the antioxidant active polyethylene masterbatch is as follows: Based on the silanol condensation reaction mechanism, long-chain alkylphenyl silane coupling agents were modified onto silanol-rich diatomaceous earth to prepare long-chain alkylphenyl functionalized diatomaceous earth. Long-chain alkylphenyl functionalized diatomaceous earth physically adsorbs phenyl-containing food-grade antioxidants through its rich internal pores and adsorbs the antioxidants through π-π stacking interactions with the antioxidants on its rich surface phenyl content, thus producing long-chain alkylated antioxidant diatomaceous earth. During the melt blending process, the long-chain alkyl groups on the surface of the long-chain alkylated antioxidant diatomaceous earth diffuse and entangle with the molecular chains of linear low-density polyethylene resin, thereby achieving uniform dispersion and firm bonding of diatomaceous earth in the linear low-density polyethylene resin matrix and obtaining antioxidant active polyethylene masterbatch. The general chemical structural formula of the long-chain alkylphenylsilane coupling agent is: 。 2. The composite film for heat-sealing plastic cups according to claim 1, characterized in that, The mass ratio of diatomite to long-chain alkylphenyl silane coupling agent in the long-chain alkylphenyl functionalized diatomite is 1:0.075-0.

15.

3. The composite film for heat-sealing plastic cups according to claim 1, characterized in that, The mass ratio of long-chain alkylphenyl functionalized diatomaceous earth to phenyl-containing food-grade antioxidant in the long-chain alkylphenyl antioxidant diatomaceous earth is 1:1.5-2.

5.

4. The composite film for heat-sealing plastic cups according to claim 1, characterized in that, The mass ratio of linear low-density polyethylene resin to long-chain alkylated antioxidant diatomaceous earth in the antioxidant active polyethylene masterbatch is 1:0.05-0.

15.

5. The composite film for heat-sealing plastic cups according to claim 1, characterized in that, The phenyl-containing food-grade antioxidant is one of carvacrol and α-tocopherol.

6. The composite film for heat-sealing plastic cups according to claim 1, characterized in that, The thickness of the composite membrane is 30-80 μm.

7. The method for preparing the composite film for heat sealing of plastic cups according to any one of claims 1-6, characterized in that, Includes the following steps: According to the formula, the raw materials of each layer are fed into the hoppers of the three single-screw extruders of the three-layer co-extrusion film blow molding unit. The molten resin is combined at the die head through the distributor, extruded and blow molded through the die head, cooled, and wound up to obtain a composite film. The temperatures of each zone of the single-screw extruder corresponding to the outer layer are: Zone 1 115-125℃, Zone 2 145-160℃, Zone 3 170-180℃, flow channel temperature 160-170℃, and screw speed 25-35r / min. The temperatures of each zone of the single-screw extruder corresponding to the intermediate layer are: Zone 1 115-125℃, Zone 2 150-165℃, Zone 3 170-180℃, the flow channel temperature is 160-170℃, and the screw speed is 30-40r / min. The temperatures of each zone of the single-screw extruder corresponding to the inner layer are: Zone 1 105-115℃, Zone 2 140-155℃, Zone 3 155-165℃, the flow channel temperature is 145-155℃, and the screw speed is 20-30 r / min.

8. The method for preparing a composite film for heat sealing of a plastic cup according to claim 7, characterized in that, The preparation method of the long-chain alkylphenylsilane coupling agent is as follows: Based on the Friedel-Crafts alkylation mechanism, under the catalysis of Lewis acids, using octaphenyl-POSS as a starting material, a long-chain alkylphenylsilane coupling agent is synthesized by first undergoing an electrophilic substitution reaction between the phenyl functional group and the alkenyl functional group of a long-chain α-olefin, and then undergoing an electrophilic substitution reaction between the remaining phenyl functional group and the alkenyl functional group of vinyltrimethoxysilane. The molar ratio of octaphenyl-POSS, long-chain α-olefin, and vinyltrimethoxysilane participating in the reaction is controlled to be 1:0.95-0.99:0.95-0.

99. The long-chain α-olefin is one of 1-tetradecene, 1-hexadecene, and 1-octadecene.

9. The method for preparing a composite film for heat sealing of a plastic cup according to claim 8, characterized in that, The Lewis acid is one of anhydrous AlCl3 or anhydrous FeCl3.

10. The application of the composite film for heat-sealing plastic cups according to any one of claims 1-6, characterized in that, The composite film triggers the release of antioxidants into the sealed space of the plastic cup through a heat-sealing process, providing antioxidant protection for the cup-packaged fresh juice product.

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