A high-barrier packaging bag and its preparation method

Abstract

This invention relates to the field of packaging bag technology and discloses a high-barrier packaging bag and its preparation method, comprising a base layer, a barrier layer, and a heat-sealing layer; the base layer is located on the outermost layer, the barrier layer is located inside the base layer, and the heat-sealing layer is located on the innermost layer; the base layer comprises the following weight components: 70-80 parts by weight of polylactic acid; the barrier layer comprises the following weight components: 70-75 parts by weight of polylactic acid, 2-4 parts by weight of polyurethane, and 2-3 parts by weight of aminocalcium carbonate; the barrier layer is prepared by adding polylactic acid, polyurethane, and aminocalcium carbonate into a twin-screw extruder and melt-blending at a temperature of 175-180°C to obtain the barrier layer material; the heat-sealing layer comprises the following weight component: 90-100 parts by weight of linear low-density polyethylene. The high-barrier packaging bag and its preparation method proposed in this invention have good tensile strength, flame retardancy, and high barrier effect.

Description

Technical Field

[0001] This invention relates to the field of packaging bag technology, specifically to a high-barrier packaging bag and its preparation method. Background Technology

[0002] With the market's increasing demands for product shelf life and quality, the demand for high-barrier packaging bags is growing. Traditional packaging bags have limitations in their barrier properties, failing to effectively prevent the intrusion of substances such as oxygen, water vapor, and odors. This leads to problems such as oxidation, moisture absorption, and spoilage of the packaged product, affecting its quality and shelf life. For example, in the food packaging field, the entry of oxygen and water vapor accelerates food oxidation and mold growth, reducing its taste and nutritional value. While patent CN106566045A discloses a packaging bag and its preparation method, this invention's bag has good stretchability, but its barrier effect is not improved. Therefore, developing a packaging bag with excellent barrier properties and its preparation method is of significant practical importance. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a high-barrier packaging bag and its preparation method, which has good tensile, flame-retardant, and high-barrier effects.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-barrier packaging bag, comprising a base layer, a barrier layer, and a heat-sealing layer; the base layer is located on the outermost layer, the barrier layer is located on the inner side of the base layer, and the heat-sealing layer is located on the innermost layer;

[0007] The base layer comprises the following components by weight: 70-80 parts by weight of polylactic acid;

[0008] The barrier layer comprises the following weight components: 70-75 parts by weight of polylactic acid, 8-10 parts by weight of polyurethane, and 2-3 parts by weight of aminocalcium carbonate; the barrier layer is prepared by adding polylactic acid, polyurethane, and aminocalcium carbonate into a twin-screw extruder and melt-blending at a temperature of 175-180°C to obtain the barrier layer material.

[0009] The heat-sealing layer comprises the following weight components: 90-100 parts by weight of linear low-density polyethylene.

[0010] Furthermore, the method for preparing the polyurethane is as follows:

[0011] S1. Add 9.5-10.1 g of 2-amino-1,3,4-thiadiazole and 140-150 mL of anhydrous ethanol to a stirrer and stir at 260-300 r / min. Then add 9.3-9.62 g of p-hydroxybenzaldehyde and heat to 76-80℃ for 7-10 h. Then add 18.5-21.61 g of DOPO and continue to react at 75-80℃ for 10-12 h. After cooling to room temperature, filter, wash with anhydrous ethanol, and dry the product under vacuum to obtain phenolylthiazol.

[0012] S2. Add 1.4-1.6 g of allylamine and an aqueous solution containing 1.42-1.63 g of formaldehyde to 50-60 mL of 1,4-dioxane solvent, stir for 20-30 min, then add 8.4-9.3 g of phenolthiazole, stir at 85-90 °C to carry out the cyclization reaction, distill under reduced pressure after the reaction, and recrystallize in ethanol to obtain alkenylthiazole;

[0013] S3. Add alkenylthiazole to N,N-dimethylformamide solvent, stir and disperse, then add 3-mercapto-1,2-propanediol and benzoin dimethyl ether photoinitiator, irradiate with 365nm ultraviolet light at 20-40℃ for 2-4 hours, centrifuge, wash and dry to obtain thiazole chain extender;

[0014] S4. Add 0.8-1 mmol of poly1,3-propanediol to the reactor and stir to remove water at 110℃ and -0.05 MPa. After water removal, cool to 60-65℃, add 1.57-1.62 mmol of 1,5-pentanediisocyanate and 0.01-0.02 mmol of dibutyltin dilaurate catalyst for prepolymerization. After the reaction temperature stabilizes, adjust the temperature to 76-80℃ and continue the reaction for 1.5-2 h. Then add 0.2-0.3 mmol of isosorbide and 0.3-0.5 mmol of thiazole chain extender preheated to 85-90℃, increase the stirring speed to 550-600 r / min and stir for 3-5 min. Remove and place at 95-100℃ for 10-12 h to obtain polyurethane.

[0015] Furthermore, the stirring time in S1 is 3-5 minutes.

[0016] Furthermore, the cyclization reaction time in S2 is 10-12 h.

[0017] Furthermore, the ratio of N,N-dimethylformamide, alkenylthiazole, 3-mercapto-1,2-propanediol, and benzoin dimethyl ether photoinitiator in S3 is 55-60 mL: 8-10 mmol: 8.3-11 mmol: 0.1-0.2 mmol.

[0018] Furthermore, the stirring and dehydration time in S4 is 1.2-1.5 hours.

[0019] Furthermore, the method for preparing the aminocalcium carbonate is as follows:

[0020] 4-5 g of CaCO3 was ultrasonically dispersed in 130-150 mL of xylene, 8-10 g of KH-792 was added, and the mixture was refluxed at 80-90 °C for 8-10 h. After the reaction was completed, the filter cake was obtained by vacuum filtration. The filter cake was repeatedly washed with anhydrous ethanol to remove the adsorbed KH-792. The filter cake was then vacuum dried at 45-50 °C for 22-24 h to obtain aminocalcium carbonate.

[0021] Furthermore, the preparation method of the high-barrier packaging bag is as follows: the prepared barrier layer material, base layer material and heat-sealing layer material are respectively added to the three hoppers of a three-layer co-extrusion blow molding machine, and a composite film is formed by co-extrusion blow molding process. During the co-extrusion blow molding process, the temperature is controlled at 180-190℃, the pressure is 8-10MPa and the extrusion speed is 25-30kg / h to obtain the composite film. The composite film is cut into the required size, and then heat-sealed at a heat-sealing temperature of 180-185℃ and a heat-sealing time of 1-1.5s to obtain a packaging bag with high barrier performance.

[0022] (iii) Beneficial technical effects

[0023] In the above reaction process, the amino group in 2-amino-1,3,4-thiadiazole and the aldehyde group in p-hydroxybenzaldehyde undergo a condensation reaction to generate a Schiff base, which then undergoes an addition reaction with the phosphorus-hydrogen bond in DOPO, introducing a phenolic group to obtain phenolic thiazole; allylamine, an aqueous solution of formaldehyde, and phenolic thiazole undergo a cyclization reaction to generate benzoxazine, while simultaneously introducing an alkenyl group to obtain alkenyl thiazole; the alkenyl group in alkenyl thiazole and the mercapto group in 3-mercapto-1,2-propanediol undergo a click reaction to introduce a hydroxyl group, thus obtaining a thiazole chain extender.

[0024] The barrier layer uses polylactic acid as the main material, combined with polyurethane and calcium aminocarbonate. The three components form a dense structure that effectively blocks the penetration of oxygen, water vapor, and other substances, significantly extending the shelf life of the packaged product. Through a unique preparation process, the polyurethane incorporates thiazole groups and phosphorus and sulfur elements, giving the material excellent flame-retardant properties. After modification with KH-792, the amino groups on the surface of the calcium aminocarbonate can form chemical bonds with other components, further densifying the structure, reducing its oxygen permeability, and further improving its barrier effect. During the preparation of the polyurethane, benzoxazine is generated through condensation and cyclization reactions, exhibiting good flame-retardant properties. Hydrogen bonding between the polyurethane and the amino functional groups in the calcium aminocarbonate not only enhances the intermolecular forces but also forms a complex cross-linked network within the material, effectively blocking the penetration paths of gas and liquid molecules while enhancing the material's tensile properties. Simultaneously, the calcium carbonate in the calcium aminocarbonate itself also possesses good flame-retardant properties. Attached Figure Description

[0025] Figure 1 It is the reaction formula for phenol-thiazolium. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0028] β-(aminoethyl)γ-aminopropyltrimethoxysilane (KH-792), mass fraction ≥97%, Anhui Sibao Organosilicon New Materials Co., Ltd. DOPO, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0029] The aqueous solution of formaldehyde has a mass fraction of 36%. Poly(1,3-propanediol) has a purity of ≥99% and Mn = 1000 g / mol.

[0030] CaCO3, particle size 0.5 μm, Foshan Jinlinda Chemical Co., Ltd. Example 1

[0031] A high-barrier packaging bag includes a base layer, a barrier layer, and a heat-sealing layer; the base layer is located on the outermost layer, the barrier layer is located inside the base layer, and the heat-sealing layer is located on the innermost layer.

[0032] The base layer comprises the following components by weight: 70 parts by weight of polylactic acid;

[0033] The barrier layer comprises the following weight components: 70 parts by weight of polylactic acid, 8 parts by weight of polyurethane, and 2 parts by weight of amino calcium carbonate; the barrier layer is prepared by adding polylactic acid, polyurethane, and amino calcium carbonate into a twin-screw extruder and melt-blending them at a temperature of 175°C to obtain the barrier layer material.

[0034] The heat-sealing layer comprises the following weight components: 90 parts by weight of linear low-density polyethylene.

[0035] The polyurethane is prepared by:

[0036] S1. Add 9.5 g of 2-amino-1,3,4-thiadiazole and 140 mL of anhydrous ethanol to a stirrer and stir at 260 r / min for 3 min. Then add 9.3 g of p-hydroxybenzaldehyde and heat to 76 °C for 7 h. Then add 18.5 g of DOPO and continue to react at 75 °C for 10 h. After cooling to room temperature, filter, wash with anhydrous ethanol, and vacuum dry the product to obtain phenolylthiazol.

[0037] S2. Add 1.4 g of allylamine and an aqueous solution containing 1.42 g of formaldehyde to 50 mL of 1,4-dioxane solvent, stir for 20 min, then add 8.4 g of phenolthiazole, stir at 85 °C to carry out cyclization reaction for 10 h, after reaction by vacuum distillation, recrystallize in ethanol to obtain alkenylthiazole.

[0038] S3. Add 8 mmol of alkenylthiazole to 55 mL of N,N-dimethylformamide solvent, stir and disperse, then add 8.3 mmol of 3-mercapto-1,2-propanediol and 0.1 mmol of benzoin dimethyl ether photoinitiator, irradiate with 365 nm ultraviolet light at 20 °C for 2 h, centrifuge, wash and dry to obtain thiazole chain extender;

[0039] S4. Add 0.8 mmol of poly1,3-propanediol to the reactor and stir to remove water at 110 °C and -0.05 MPa for 1.2 h. After water removal, cool to 60 °C, add 1.57 mmol of 1,5-pentanediisocyanate and 0.01 mmol of dibutyltin dilaurate catalyst for prepolymerization. After the reaction temperature stabilizes, adjust the temperature to 76 °C and continue the reaction for 1.5 h. Then add 0.2 mmol of isosorbide and 0.3 mmol of thiazole chain extender preheated to 85 °C, increase the stirring speed to 550 r / min and stir for 3 min. Remove and place at 95 °C for 10 h to obtain polyurethane.

[0040] 4 g of CaCO3 was ultrasonically dispersed in 130 mL of xylene, 8 g of KH-792 was added, and the mixture was refluxed at 80 °C for 8 h. After the reaction was completed, the filter cake was obtained by vacuum filtration. The filter cake was repeatedly washed with anhydrous ethanol to remove the adsorbed KH-792. The filter cake was then vacuum dried at 45 °C for 22 h to obtain aminocalcium carbonate.

[0041] The method for preparing the high-barrier packaging bag is as follows: the prepared barrier layer material, base layer material and heat-sealing layer material are respectively added to the three hoppers of a three-layer co-extrusion blow molding machine, and a composite film is formed by co-extrusion blow molding process. During the co-extrusion blow molding process, the temperature is controlled at 180℃, the pressure is 8MPa and the extrusion speed is 25kg / h to obtain the composite film. The composite film is cut into the required size, and then heat-sealed to make bags under the conditions of heat-sealing temperature of 180℃ and heat-sealing time of 1s to obtain a packaging bag with high barrier performance. Example 2

[0042] A high-barrier packaging bag includes a base layer, a barrier layer, and a heat-sealing layer; the base layer is located on the outermost layer, the barrier layer is located inside the base layer, and the heat-sealing layer is located on the innermost layer.

[0043] The base layer comprises the following components by weight: 80 parts by weight of polylactic acid;

[0044] The barrier layer comprises the following weight components: 75 parts by weight of polylactic acid, 10 parts by weight of polyurethane, and 3 parts by weight of amino calcium carbonate; the barrier layer is prepared by adding polylactic acid, polyurethane, and amino calcium carbonate into a twin-screw extruder and melt-blending them at a temperature of 180°C to obtain the barrier layer material.

[0045] The heat-sealing layer comprises the following weight components: 100 parts by weight of linear low-density polyethylene.

[0046] The polyurethane is prepared by:

[0047] S1. 10.1 g of 2-amino-1,3,4-thiadiazole and 150 mL of anhydrous ethanol were added to a stirrer and stirred at 300 r / min for 5 min. Then 9.62 g of p-hydroxybenzaldehyde was added, and the mixture was heated to 80 °C and reacted for 10 h. Then 21.61 g of DOPO was added, and the mixture was reacted at 80 °C for 12 h. After cooling to room temperature, the mixture was filtered, washed with anhydrous ethanol, and the product was dried under vacuum to obtain phenolylthiazol.

[0048] S2. Add 1.6 g of allylamine and an aqueous solution containing 1.63 g of formaldehyde to 60 mL of 1,4-dioxane solvent, stir for 30 min, then add 9.3 g of phenolylthiazole, stir at 90 °C to carry out cyclization reaction for 12 h, after reaction by vacuum distillation, recrystallize in ethanol to obtain alkenylthiazole.

[0049] S3. Add 10 mmol of alkenylthiazole to 60 mL of N,N-dimethylformamide solvent, stir and disperse, then add 11 mmol of 3-mercapto-1,2-propanediol and 0.2 mmol of benzoin dimethyl ether photoinitiator, irradiate with 365 nm ultraviolet light at 40 °C for 4 h, centrifuge after the irradiation, wash and dry to obtain thiazole chain extender;

[0050] S4. 1 mmol of poly(1,3-propanediol) was added to the reactor and stirred at 110 °C and -0.05 MPa for 1.5 h to remove water. After water removal, the temperature was lowered to 65 °C, and 1.62 mmol of 1,5-pentanediisocyanate and 0.02 mmol of dibutyltin dilaurate catalyst were added for prepolymerization. After the reaction temperature stabilized, the temperature was adjusted to 80 °C and the reaction was continued for 2 h. Then, 0.3 mmol of isosorbide and 0.5 mmol of thiazole chain extender preheated to 90 °C were added, the stirring speed was increased to 600 r / min and stirred for 5 min. The mixture was then placed at 100 °C and reacted for 12 h to obtain polyurethane.

[0051] 5g CaCO3 was ultrasonically dispersed in 150 mL xylene, 10g KH-792 was added, and the mixture was refluxed at 90℃ for 10 h. After the reaction was completed, the filter cake was obtained by vacuum filtration. The filter cake was repeatedly washed with anhydrous ethanol to remove the adsorbed KH-792. The filter cake was then vacuum dried at 50 ℃ for 24 h to obtain aminocalcium carbonate.

[0052] The method for preparing the high-barrier packaging bag is as follows: the prepared barrier layer material, base layer material and heat-sealing layer material are respectively added to the three hoppers of a three-layer co-extrusion blow molding machine, and a composite film is formed by co-extrusion blow molding process. During the co-extrusion blow molding process, the temperature is controlled at 190℃, the pressure is 10MPa and the extrusion speed is 30kg / h to obtain the composite film. The composite film is cut into the required size, and then heat-sealed to make bags under the conditions of heat-sealing temperature of 185℃ and heat-sealing time of 1.5s to obtain a packaging bag with high barrier performance. Example 3

[0053] A high-barrier packaging bag includes a base layer, a barrier layer, and a heat-sealing layer; the base layer is located on the outermost layer, the barrier layer is located inside the base layer, and the heat-sealing layer is located on the innermost layer.

[0054] The base layer comprises the following components by weight: 75 parts by weight of polylactic acid;

[0055] The barrier layer comprises the following weight components: 73 parts by weight of polylactic acid, 9 parts by weight of polyurethane, and 2.5 parts by weight of aminocalcium carbonate; the barrier layer is prepared by adding polylactic acid, polyurethane, and aminocalcium carbonate into a twin-screw extruder and melt-blending at a temperature of 178°C to obtain the barrier layer material.

[0056] The heat-sealing layer comprises the following weight components: 95 parts by weight of linear low-density polyethylene.

[0057] The polyurethane is prepared by:

[0058] S1. 9.8 g of 2-amino-1,3,4-thiadiazole and 145 mL of anhydrous ethanol were added to a stirrer and stirred at 270 r / min for 4 min. Then 9.51 g of p-hydroxybenzaldehyde was added, and the mixture was heated to 78 °C and reacted for 8 h. Then 19.5 g of DOPO was added, and the mixture was reacted at 78 °C for 11 h. After cooling to room temperature, the mixture was filtered, washed with anhydrous ethanol, and the product was dried under vacuum to obtain phenol-thiazolium.

[0059] S2. Add 1.5 g of allylamine and an aqueous solution containing 1.54 g of formaldehyde to 55 mL of 1,4-dioxane solvent, stir for 26 min, then add 8.7 g of phenolylthiazole, stir at 87 °C to carry out cyclization reaction for 11 h, after reaction by vacuum distillation, recrystallize in ethanol to obtain alkenylthiazole.

[0060] S3. Add 9 mmol of alkenylthiazole to 58 mL of N,N-dimethylformamide solvent, stir and disperse, then add 9.2 mmol of 3-mercapto-1,2-propanediol and 0.1 mmol of benzoin dimethyl ether photoinitiator, irradiate with 365 nm ultraviolet light at 30 °C for 3 h, centrifuge after the irradiation, wash and dry to obtain thiazole chain extender;

[0061] S4. Add 0.9 mmol of poly1,3-propanediol to the reactor and stir at 110 °C and -0.05 MPa to remove water for 1.2-1.5 h. After water removal, cool to 63 °C, add 1.60 mmol of 1,5-pentanediisocyanate and 0.02 mmol of dibutyltin dilaurate catalyst for prepolymerization. After the reaction temperature stabilizes, adjust the temperature to 78 °C and continue the reaction for 1.6 h. Then add 0.26 mmol of isosorbide and 0.4 mmol of thiazole chain extender preheated to 88 °C, increase the stirring speed to 570 r / min and stir for 4 min. Remove and place at 97 °C for 11 h to obtain polyurethane.

[0062] 4.5 g CaCO3 was ultrasonically dispersed in 140 mL xylene, 9 g KH-792 was added, and the mixture was refluxed at 85 °C for 9 h. After the reaction was completed, the filter cake was obtained by vacuum filtration. The filter cake was repeatedly washed with anhydrous ethanol to remove the adsorbed KH-792. The filter cake was then vacuum dried at 47 °C for 23 h to obtain aminocalcium carbonate.

[0063] The method for preparing the high-barrier packaging bag is as follows: the prepared barrier layer material, base layer material and heat-sealing layer material are respectively added to the three hoppers of a three-layer co-extrusion blow molding machine, and a composite film is formed by co-extrusion blow molding process. During the co-extrusion blow molding process, the temperature is controlled at 185℃, the pressure is 9MPa and the extrusion speed is 27kg / h to obtain the composite film. The composite film is cut into the required size, and then heat-sealed to make bags under the conditions of heat-sealing temperature of 182℃ and heat-sealing time of 1.3s to obtain a packaging bag with high barrier performance.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 3 is that phenol-thiazole is used instead of polyurethane.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 3 is that no calcium aminocarbonate was added.

[0068] Performance testing

[0069] Barrier performance test: The oxygen permeability of the high barrier performance packaging bags obtained in Examples 1-3 and Comparative Examples 1-2 was tested according to the method specified in GB / T 1038-2000 "Gas permeability test method for plastic films and sheets - differential pressure method". The test gas used was oxygen with a purity of 99%.

[0070] Table 1: Barrier Test

[0071] project <![CDATA[Oxygen transmission rate (cm 3 / m 2 ·24h·0.1MPa)]]> Example 1 2.09 Example 2 2.05 Example 3 2.10 Comparative Example 1 4.27 Comparative Example 2 4.02

[0072] As shown in Table 1, Examples 1-3 of the present invention have better barrier properties than Comparative Examples 1-2.

[0073] Tensile strength was tested according to GB / T1040.1-2006; flame retardancy test: UL94-2013 Rev.14-2022 Section 11 Vertical burning results are shown in Table 2.

[0074] Table 2: Flame retardancy and tensile tests

[0075] project Tensile strength (MPa) Vertical combustion Example 1 51.6 V-0 Example 2 55.9 V-0 Example 3 53.1 V-0 Comparative Example 1 40.2 V-1 Comparative Example 2 44.7 V-1

[0076] As shown in Table 2, Examples 1-3 of the present invention have better flame retardant and tensile properties compared with Comparative Examples 1-2.

[0077] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0079] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A high-barrier packaging bag, characterized in that, It includes a base layer, a barrier layer, and a heat seal layer; the base layer is located on the outermost layer, the barrier layer is located inside the base layer, and the heat seal layer is located on the innermost layer. The base layer comprises the following components by weight: 70-80 parts by weight of polylactic acid; The barrier layer comprises the following weight components: 70-75 parts by weight of polylactic acid, 8-10 parts by weight of polyurethane, and 2-3 parts by weight of aminocalcium carbonate; the barrier layer is prepared by adding polylactic acid, polyurethane, and aminocalcium carbonate into a twin-screw extruder and melt-blending at a temperature of 175-180°C to obtain the barrier layer material. The heat-sealing layer comprises the following weight components: 90-100 parts by weight of linear low-density polyethylene; The polyurethane is prepared by: S1. Add 9.5-10.1 g of 2-amino-1,3,4-thiadiazole and 140-150 mL of anhydrous ethanol to a stirrer and stir at 260-300 r / min. Then add 9.3-9.62 g of p-hydroxybenzaldehyde and heat to 76-80℃ for 7-10 h. Then add 18.5-21.61 g of DOPO and continue to react at 75-80℃ for 10-12 h. After cooling to room temperature, filter, wash with anhydrous ethanol, and dry the product under vacuum to obtain phenolylthiazol. S2. Add 1.4-1.6 g of allylamine and an aqueous solution containing 1.42-1.63 g of formaldehyde to 50-60 mL of 1,4-dioxane solvent, stir for 20-30 min, then add 8.4-9.3 g of phenolthiazole, stir at 85-90 °C to carry out the cyclization reaction, distill under reduced pressure after the reaction, and recrystallize in ethanol to obtain alkenylthiazole; S3. Add alkenylthiazole to N,N-dimethylformamide solvent, stir and disperse, then add 3-mercapto-1,2-propanediol and benzoin dimethyl ether photoinitiator, irradiate with 365nm ultraviolet light at 20-40℃ for 2-4 hours, centrifuge, wash and dry to obtain thiazole chain extender; S4. Add 0.8-1 mmol of poly1,3-propanediol to the reactor and stir to remove water at 110℃ and -0.05 MPa. After water removal, cool to 60-65℃, add 1.57-1.62 mmol of 1,5-pentanediisocyanate and 0.01-0.02 mmol of dibutyltin dilaurate catalyst for prepolymerization. After the reaction temperature stabilizes, adjust the temperature to 76-80℃ and continue the reaction for 1.5-2 h. Then add 0.2-0.3 mmol of isosorbide and 0.3-0.5 mmol of thiazole chain extender preheated to 85-90℃, increase the stirring speed to 550-600 r / min and stir for 3-5 min. Remove and place at 95-100℃ for 10-12 h to obtain polyurethane. The ratio of N,N-dimethylformamide, alkenylthiazole, 3-mercapto-1,2-propanediol, and benzoin dimethyl ether photoinitiator in S3 is 55-60 mL: 8-10 mmol: 8.3-11 mmol: 0.1-0.2 mmol.

2. The high-barrier packaging bag according to claim 1, characterized in that, The stirring time in S1 is 3-5 minutes.

3. The high-barrier packaging bag according to claim 1, characterized in that, The cyclization reaction time in S2 is 10-12 hours.

4. The high-barrier packaging bag according to claim 1, characterized in that, The stirring and dehydration time in S4 is 1.2-1.5 hours.

5. The high-barrier packaging bag according to claim 1, characterized in that, The preparation method of the aminocalcium carbonate is as follows: 4-5 g of CaCO3 was ultrasonically dispersed in 130-150 mL of xylene, 8-10 g of KH-792 was added, and the mixture was refluxed at 80-90 °C for 8-10 h. After the reaction was completed, the filter cake was obtained by vacuum filtration. The filter cake was repeatedly washed with anhydrous ethanol to remove the adsorbed KH-792. The filter cake was then vacuum dried at 45-50 °C for 22-24 h to obtain aminocalcium carbonate.

6. A method for preparing a high-barrier packaging bag as described in any one of claims 1-5, characterized in that, The method for preparing the high-barrier packaging bag is as follows: the prepared barrier layer material, base layer material, and heat-sealing layer material are respectively added to the three hoppers of a three-layer co-extrusion blow molding machine, and a composite film is formed through co-extrusion blow molding process. During the co-extrusion blow molding process, the temperature is controlled at 180-190℃, the pressure at 8-10MPa, and the extrusion speed at 25-30kg / h to obtain the composite film. The composite film is then cut into the required size, and then heat-sealed at a heat-sealing temperature of 180-185℃ and a heat-sealing time of 1-1.5s to obtain a packaging bag with high barrier performance.

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