An anti-fouling environment-friendly composite packaging material and a preparation method thereof

Abstract

The application discloses an anti-fouling environment-friendly composite packaging material and a preparation method thereof, and aims to solve the technical problems of easy fouling and environmental unfriendliness of the packaging material. The polyurethane chain structure is formed by using isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol and hexamethylene diisocyanate, and the anti-fouling environment-friendly composite packaging material polymer matrix is jointly constituted by the polyurethane chain structure and grafted PDMS side chains. The poly(methyl hydroxyethyl methacrylate)-lignin is used as a reinforcing filler and is dispersed in the polymer matrix to form the anti-fouling environment-friendly composite packaging material.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to a stain-resistant and environmentally friendly composite packaging material and its preparation method. Background Technology

[0002] With the development of modern industrial technology, plastic packaging has gradually replaced traditional packaging materials such as paper and leather due to its significant advantages such as light weight, durability, and low cost. However, its large-scale use has also brought increasingly serious environmental problems. Traditional plastic packaging materials are mostly derived from petroleum, which is difficult to degrade in the natural environment, leading to long-term environmental pollution after disposal. Furthermore, the surface stain resistance of existing packaging materials is generally insufficient, making them susceptible to adhesion and penetration of pollutants such as oil and dust. This not only affects the cleanliness of the packaging appearance and label identification but may also contaminate the interior, causing the product inside to spoil. This deficiency limits its application in the food, pharmaceutical, and other fields.

[0003] In conclusion, using green and environmentally friendly packaging materials while addressing the problem of insufficient stain resistance in packaging materials is crucial for promoting the development of packaging materials and alleviating the environmental problems caused by the accumulation of traditional plastics. Summary of the Invention

[0004] This invention provides a stain-resistant and environmentally friendly composite packaging material and its preparation method to improve the environmental friendliness and stain resistance of packaging materials.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: A method for preparing a stain-resistant and environmentally friendly composite packaging material, specifically comprising: Step 1: Mix castor oil, 1,6-hexanediol and sebacic acid to react and obtain castor oil polyester polyol; Step 2: Mix dimethyl succinate, 1,4-butanediol and isosorbide to react and obtain isosorbide-terminated hydroxyl polybutylene succinate; Step 3: Mix and react the single-hydroxyl-terminated polydimethylsiloxane, pyridine, and thionyl chloride to obtain chlorinated polydimethylsiloxane; Step 4: After modifying the lignin nanoparticles with silane coupling agent KH-570, they are mixed and reacted with hydroxyethyl methacrylate to obtain polyhydroxyethyl methacrylate-lignin. Step 5: Mix isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol, hexamethylene diisocyanate, chlorinated polydimethylsiloxane, and potassium tert-butoxide to obtain polydimethylsiloxane-polyurethane. Then, mix polydimethylsiloxane-polyurethane and polyhydroxyethyl methacrylate-lignin evenly, melt them, and extrude and cast them into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

[0006] Furthermore, the method for preparing the castor oil polyester polyol is as follows: Under nitrogen protection, castor oil and 1,6-hexanediol were mixed and stirred until homogeneous. The mixture was heated to 180-190°C, and tetrabutyl titanate was added as a catalyst. The mixture was stirred at 180-190°C and 300-400 rpm for 2-3 hours. Sebacic acid was then added and stirred until homogeneous. The mixture was heated to 210-220°C while simultaneously applying a vacuum of 100-500 Pa. The mixture was stirred at 210-220°C and 300-400 rpm for 1-2 hours. After the reaction was completed, the mixture was cooled, dissolved in tetrahydrofuran, and then transferred to ice-cold methanol to precipitate. The precipitate was filtered, washed with methanol, and dried under vacuum at 60-70°C for 8-10 hours to obtain castor oil polyester polyol.

[0007] Further, the mass ratio of castor oil, 1,6-butanediol, sebacic acid, magnesium acetate catalyst, and tetrabutyl titanate catalyst is (100-120):(30-40):(40-50):(0.05-0.1).

[0008] Under the catalysis of a catalyst, castor oil first undergoes an alcoholysis reaction with 1,6-hexanediol. Subsequently, the hydroxyl groups of the alcoholysis product undergo a polycondensation reaction with the carboxyl groups of sebacic acid to form castor oil-based polyester polyol. Alcohololysis of castor oil is beneficial for forming linear polyester polyols with a uniform molecular weight distribution. The selected 1,6-hexanediol and sebacic acid are both long-chain aliphatic monomers, which lower the glass transition temperature of the polyester polyol and enhance its toughness and elasticity. Using them as the soft segment of polyurethane helps improve the toughness, elasticity, hydrophobicity, and stain resistance of polyurethane materials.

[0009] Furthermore, the preparation method of the isosorbide-terminated hydroxyl polybutylene succinate is as follows: Under nitrogen protection, dimethyl succinate, 1,4-butanediol, and isosorbide were mixed and stirred until homogeneous. The mixture was heated to 180-190°C, and magnesium acetate catalyst was added. The mixture was stirred at 180-190°C and 300-400 rpm for 2-3 hours. Then, tetrabutyl titanate catalyst was added and stirred until homogeneous. The mixture was heated to 210-220°C while simultaneously evacuating to 100-500 Pa. The mixture was stirred at 210-220°C and 300-400 rpm for 1-2 hours. After the reaction was completed, the mixture was cooled, dissolved in tetrahydrofuran, and transferred to ice-cold methanol to precipitate. The precipitate was filtered, washed with methanol, and dried under vacuum at 60-70°C for 8-10 hours to obtain isosorbide-terminated hydroxyl polybutylene succinate.

[0010] Further, the mass ratio of dimethyl succinate, 1,4-butanediol, isosorbide, magnesium acetate catalyst, and tetrabutyl titanate catalyst is (100-120):(65-75):(10-20):(0.1-0.2):(0.1-0.2).

[0011] Catalyzed by magnesium acetate and tetrabutyl titanate, the ester bonds of dimethyl succinate undergo transesterification with the hydroxyl groups of 1,4-butanediol and isosorbide, generating oligomers with terminal hydroxyl or methyl ester groups and small-molecule methanol. Subsequently, condensation polymerization occurs between the oligomers, further removing methanol and generating a macromolecular structure of polybutylene succinate with terminal hydroxyl groups containing isosorbide. Isosorbide, as a rigid cyclic diol derived from biomass, restricts the free movement of polybutylene succinate molecular chains due to its rigid ring structure, thereby increasing the glass transition temperature, modulus, and heat distortion temperature of the rigid segment of polyurethane, and enhancing the rigidity and mechanical properties of the rigid segment.

[0012] Furthermore, the preparation method of the chlorinated polydimethylsiloxane is as follows: Under nitrogen protection, hydroxyl-terminated polydimethylsiloxane and pyridine were added to toluene and stirred until homogeneous. Thionyl chloride was then added, and the mixture was stirred at 40-50°C and 300-400 rpm for 8-10 hours. After the reaction was completed, the reaction was terminated with ice-cold deionized water. The mixture was separated into liquid and liquid phases, and the aqueous phase was extracted with toluene. The organic phase was washed successively with dilute hydrochloric acid, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution. The mixture was dried over anhydrous sodium sulfate, filtered, and toluene was removed by rotary evaporation. The mixture was then vacuum dried at 60-70°C for 8-10 hours to obtain chloropolydimethylsiloxane.

[0013] Preferably, the mass ratio of the single-hydroxyl-terminated polydimethylsiloxane, pyridine, and thionyl chloride is (10-14):(5-7):(7-9).

[0014] Under alkaline conditions formed by pyridine, thionyl chloride is activated and reacts with the terminal hydroxyl groups of monohydroxyl-terminated polydimethylsiloxane to generate chloropolydimethylsiloxane and release sulfur dioxide.

[0015] Furthermore, the preparation method of the poly(hydroxyethyl methacrylate)-lignin is as follows: Lignin nanoparticles were added to an ethanol aqueous solution, stirred evenly, and ultrasonically dispersed for 10-20 min. Silane coupling agent KH-570 was added, and the pH was adjusted to 4-5. The mixture was stirred at 70-80℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was centrifuged, washed with ethanol and deionized water, and vacuum dried at 70-80℃ for 6-8 h to obtain KH-570 modified lignin. Under nitrogen protection, KH-570 modified lignin was added to N,N-dimethylformamide, stirred until homogeneous, and ultrasonically dispersed for 10-20 min. Hydroxyethyl methacrylate and azobisisobutyronitrile (AIOPT) catalyst were then added, and the mixture was stirred at 70-80℃ and 300-400 rpm for 8-10 h. After the reaction was completed, the mixture was cooled, transferred to a methanol aqueous solution to precipitate, filtered, washed with methanol and deionized water, and vacuum dried at 70-80℃ for 6-8 h to obtain poly(hydroxyethyl methacrylate)-lignin.

[0016] Preferably, the mass ratio of the lignin nanoparticles to the silane coupling agent KH-570 is (10-12):(0.8-1.0); the mass ratio of KH-570 modified lignin, hydroxyethyl methacrylate, and the catalyst azobisisobutyronitrile is (5-7):(5-9):(0.05-0.1).

[0017] Under acidic conditions, the silanol groups generated by the hydrolysis of the silane coupling agent KH-570 undergo dehydration condensation with the hydroxyl groups on the surface of lignin nanoparticles. KH-570 molecules are chemically bonded to the surface of the lignin nanoparticles. Subsequently, under the initiation of azobisisobutyronitrile (AIB), the double bonds at the ends of KH-570 participate in the polymerization reaction of hydroxyethyl methacrylate monomers, forming a polyhydroxyethyl methacrylate polymer shell on the surface of the lignin nanoparticles. KH-570-modified lignin nanoparticles help reduce the surface energy of lignin, improve its hydrophobicity, enhance its compatibility with the hydrophobic polymer matrix, and improve the dispersibility of lignin nanoparticles in composite materials, avoiding performance degradation caused by agglomeration. The polymer shell helps alleviate interfacial stress concentration between rigid lignin particles and the flexible polymer matrix, improving the toughness of the packaging material. Simultaneously, the polymer shell facilitates stress transfer from the flexible matrix to the rigid lignin particles, thereby fully utilizing the reinforcing effect of the lignin nanoparticles and improving the strength and mechanical properties of the packaging material.

[0018] Furthermore, the preparation method of the anti-fouling and environmentally friendly composite packaging material is as follows: Potassium tert-butoxide was added to dimethyl ethylene glycol and stirred until homogeneous to obtain a potassium tert-butoxide dispersion. Under nitrogen protection, isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol, and hexamethylene diisocyanate were mixed and stirred until homogeneous. Dibutyltin dilaurate catalyst was added, and the mixture was stirred at 80-90℃ and 300-400 rpm for 2-3 hours. After the reaction was completed, dimethyl ethylene glycol was added and stirred until homogeneous. The potassium tert-butoxide dispersion was added under ice-water bath conditions, and the mixture was stirred at 300-400 rpm for 0.5-1 hours. Chlorinated polydimethylsiloxane was then added, and the mixture was stirred at 300-400 rpm for 2-3 hours under ice-water bath conditions. After the reaction was completed, the mixture was allowed to return to room temperature, and the reaction was terminated with a saturated ammonium chloride aqueous solution. After rotary evaporation, the mixture was washed with deionized water and dried under vacuum at 60-70℃ for 6-8 hours to obtain polydimethylsiloxane-polyurethane. Polydimethylsiloxane-polyurethane and poly(hydroxyethyl methacrylate)-lignin are mixed, stirred evenly, and then transferred to a twin-screw extruder for extrusion and casting into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

[0019] Further, by weight, the polydimethylsiloxane-polyurethane comprises 60-70 parts isosorbide-terminated hydroxyl polybutylene succinate, 40-50 parts castor oil polyester polyol, 15-20 parts hexamethylene diisocyanate, 8-10 parts isocyanate-PDMS, 1.5-2 parts potassium tert-butoxide, and 13-15 parts chlorinated polydimethylsiloxane; the mass ratio of polydimethylsiloxane-polyurethane to polyhydroxyethyl methacrylate-lignin is (86-90):(10-14); the twin-screw extrusion process conditions include a screw speed of 100-200 rpm, a zone 1 temperature of 170-180℃, a zone 2 temperature of 180-190℃, a zone 3 temperature of 190-200℃, and a zone 4 temperature of 190-200℃.

[0020] Under the catalysis of dibutyltin dilaurate, the isocyanate groups of hexamethylene diisocyanate react with the hydroxyl groups of isosorbide-terminated hydroxyl polybutylene succinate and castor oil polyester polyol to form chemical bonds, thus forming a polyurethane elastomer structure. Subsequently, under the catalysis of potassium tert-butoxide, the chlorine of chlorinated polydimethylsiloxane reacts with the amino groups on the urethane bonds in the polyurethane molecular chain, and PDMS is grafted onto the polyurethane elastomer molecular chain and dechlorinates, forming polydimethylsiloxane-polyurethane. Isosorbide-terminated hydroxyl polybutylene succinate, as the hard segment of the polyurethane, provides good rigidity, strength, and heat resistance; castor oil polyester polyol, as the soft segment of the polyurethane, provides good toughness, impact resistance, hydrophobicity, and stain resistance. During the molding process of the packaging material, the grafted PDMS spontaneously migrates and accumulates on the material surface to form a stable low surface energy hydrophobic layer structure, which helps to enhance the hydrophobicity and stain resistance of the packaging material. By grafting PDMS segments onto polyurethane molecular chains, the migration and loss of PDMS are prevented, which helps to enhance the hydrophobic stability and long-term anti-fouling properties of the packaging material. The core-shell structured lignin nanoparticles serve as reinforcing fillers, further improving the strength, abrasion resistance, and other properties of the packaging material.

[0021] A stain-resistant and environmentally friendly composite packaging material is prepared using any of the above-described preparation methods.

[0022] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol, and hexamethylene diisocyanate to form a polyurethane chain structure, which, together with grafted PDMS side chains, constitutes the polymer matrix of an anti-fouling and environmentally friendly composite packaging material. Hydroxyethyl methacrylate-lignin, as a reinforcing filler, is dispersed within the polymer matrix, forming the anti-fouling and environmentally friendly composite packaging material. The isosorbide-terminated hydroxyl polybutylene succinate, as the hard segment of the polyurethane, provides excellent rigidity, strength, and heat resistance; the castor oil polyester polyol, as the soft segment of the polyurethane, provides excellent toughness, impact resistance, hydrophobicity, and anti-fouling properties; the grafted PDMS segments migrate and accumulate on the surface of the packaging material, forming a low surface energy hydrophobic layer, enhancing the hydrophobicity and anti-fouling properties of the packaging material; and the core-shell structured lignin nanoparticles, as a reinforcing filler, further improve the strength, abrasion resistance, and other properties of the packaging material. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention are described in detail below. It is understood that the described embodiments are only a part of the embodiments of the present invention, and not all of them. The dosages in the embodiments are all small-scale laboratory tests and can be scaled up proportionally. Based on the embodiments disclosed in this invention, all other equivalent embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0024] In the following examples and comparative examples, the molecular weight of the single-hydroxyl-terminated polydimethylsiloxane is 1000; the particle size of the lignin nanoparticles is 50 nm; and all raw materials in the examples and comparative examples were dried at 110°C for 2 hours before being added.

[0025] Example 1: A method for preparing a stain-resistant and environmentally friendly composite packaging material, specifically as follows: Step 1: Under nitrogen protection, 100g castor oil and 30g 1,6-hexanediol were mixed and stirred evenly. The mixture was heated to 190℃, and 0.05g tetrabutyl titanate catalyst was added. The mixture was stirred at 190℃ and 400rpm for 3h. Then, 40g sebacic acid was added and stirred evenly. The mixture was heated to 220℃ and vacuumed to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2h. After the reaction was completed, the mixture was cooled, dissolved in tetrahydrofuran, transferred to ice-cold methanol to precipitate, filtered, washed with methanol, and dried under vacuum at 70℃ for 8h to obtain castor oil polyester polyol. Step 2: Under nitrogen protection, 100g of dimethyl succinate, 65g of 1,4-butanediol and 10g of isosorbide were mixed and stirred evenly. The mixture was heated to 180℃, and 0.1g of magnesium acetate catalyst was added. The mixture was stirred at 180℃ and 400rpm for 2h. Then, 0.2g of tetrabutyl titanate catalyst was added and stirred evenly. The mixture was heated to 220℃ and evacuated to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2h. After the reaction was completed, the mixture was cooled, dissolved in tetrahydrofuran, transferred to ice-cold methanol to precipitate, filtered, washed with methanol, and dried under vacuum at 70℃ for 8h to obtain isosorbide-terminated hydroxyl polybutylene succinate. Step 3: Under nitrogen protection, 10g of hydroxyl-terminated polydimethylsiloxane and 5g of pyridine were added to 100mL of toluene and stirred until homogeneous. 7g of thionyl chloride was added, and the mixture was stirred at 40℃ and 400rpm for 10h. After the reaction was completed, the reaction was terminated with ice-cold deionized water. The mixture was separated into liquid and liquid phases. The aqueous phase was extracted with toluene, and the organic phase was washed successively with dilute hydrochloric acid, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution. The mixture was dried over anhydrous sodium sulfate, filtered, and toluene was removed by rotary evaporation. The mixture was then dried under vacuum at 60℃ for 10h to obtain chlorinated polydimethylsiloxane. Step 4: Add 10g of lignin nanoparticles to a mixed solution of 180mL anhydrous ethanol and 20mL deionized water, stir evenly, ultrasonically disperse for 20min, add 0.8g of silane coupling agent KH-570, adjust the pH to 4, and react at 70℃ and 400rpm for 6h. After the reaction is complete, centrifuge, wash with ethanol and deionized water, and vacuum dry at 70℃ for 8h to obtain KH-570 modified lignin. Step 5: Under nitrogen protection, 5g of KH-570 modified lignin was added to 100mL of N,N-dimethylformamide, stirred evenly, and ultrasonically dispersed for 10min. Then, 5g of hydroxyethyl methacrylate and 0.05g of azobisisobutyronitrile catalyst were added, and the mixture was stirred at 75℃ and 400rpm for 10h. After the reaction was completed, the mixture was cooled, transferred to a methanol aqueous solution to precipitate, filtered, washed with methanol and deionized water, and vacuum dried at 70-80℃ for 6-8h to obtain polyhydroxyethyl methacrylate-lignin. Step 6: Add 1.5g of potassium tert-butoxide to 50mL of p-ethylene glycol dimethyl ether and stir until homogeneous to obtain a potassium tert-butoxide dispersion. Under nitrogen protection, mix 60g of isosorbide-terminated hydroxyl polybutylene succinate, 40g of castor oil polyester polyol and 15g of hexamethylene diisocyanate and stir until homogeneous. Add 0.03g of dibutyltin dilaurate catalyst and stir at 90℃ and 400rpm for 2h. After the reaction is complete, add 500mL of p-ethylene glycol dimethyl ether and stir until homogeneous. Add the potassium tert-butoxide dispersion under ice-water bath conditions and stir at 400rpm for 1h. Add 13g of chloropolydimethylsiloxane and stir at 400rpm for 2h under ice-water bath conditions. After the reaction is complete, return to room temperature and terminate the reaction with saturated ammonium chloride aqueous solution. After rotary evaporation, wash with deionized water and vacuum dry at 70℃ for 6h to obtain polydimethylsiloxane-polyurethane. Step 7: Mix 90g of polydimethylsiloxane-polyurethane with 10g of poly(hydroxyethyl methacrylate)-lignin, stir evenly, and then transfer to a twin-screw extruder. Set the temperature of zone 1 to 170℃, zone 2 to 180℃, zone 3 to 190℃, and zone 4 to 195℃. Extrude and cast the mixture into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

[0026] test: The tensile properties of the stain-resistant and environmentally friendly composite packaging material were tested in accordance with the "Determination of Tensile Properties of Plastics" (GB / T1040.1-2025). A universal testing machine was used, and the tensile rate was set to 50 mm / min to test the tensile strength and elongation at break. The water contact angle test for antifouling and environmentally friendly composite packaging materials refers to the "Measurement of Contact Angle between Plastic Film and Water" (GB / T30693-2014). Using a contact angle measuring instrument, 1 μL of ultrapure water is dropped onto the sample surface to test the water contact angle. The stain resistance test of the stain-resistant and environmentally friendly composite packaging material was conducted by using water-based markers and oil-based markers to draw 2.5 cm long and 0.4 cm wide marks on the sample surface. After marking, the sample was left to stand for 5 seconds. Image J software was used to analyze the area of ​​the marks and the area after ink shrinkage after standing, and the ratio of the residual area after ink shrinkage was calculated. Test results: Tensile strength was 35.2 MPa, elongation at break was 456%, water contact angle was 112°, shrinkage area ratio of water-based marker ink was 95%, and shrinkage area ratio of oil-based marker ink was 85%.

[0027] Example 2: A method for preparing a stain-resistant and environmentally friendly composite packaging material, specifically as follows: Step 1: Under nitrogen protection, 110g castor oil and 35g 1,6-hexanediol were mixed and stirred evenly. The mixture was heated to 190℃, and 0.07g tetrabutyl titanate catalyst was added. The mixture was stirred at 190℃ and 400rpm for 3 hours. Then, 45g sebacic acid was added and stirred evenly. The mixture was heated to 220℃ and vacuumed to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2 hours. After the reaction was completed, the mixture was cooled and post-processed to obtain castor oil polyester polyol. Step 2: Under nitrogen protection, 110g of dimethyl succinate, 70g of 1,4-butanediol and 15g of isosorbide were mixed and stirred evenly. The mixture was heated to 180℃, and 0.15g of magnesium acetate catalyst was added. The mixture was stirred at 180℃ and 400rpm for 2 hours. Then, 0.2g of tetrabutyl titanate catalyst was added and stirred evenly. The mixture was heated to 220℃ and evacuated to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2 hours. After the reaction was completed, the mixture was cooled and post-processed to obtain isosorbide-terminated hydroxyl polybutylene succinate. Step 3: Under nitrogen protection, 12g of single-hydroxyl-terminated polydimethylsiloxane and 6g of pyridine were added to 100mL of toluene and stirred until homogeneous. 8g of thionyl chloride was added, and the mixture was stirred at 40℃ and 400rpm for 10h. After the reaction was completed, the reaction was terminated with ice-cold deionized water. The mixture was separated into liquid and liquid phases. The aqueous phase was extracted with toluene, and the organic phase was washed successively with dilute hydrochloric acid, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution. The mixture was dried over anhydrous sodium sulfate, filtered, and toluene was removed by rotary evaporation. The mixture was then dried under vacuum at 60℃ for 10h to obtain chlorinated polydimethylsiloxane. Step 4: Add 11g of lignin nanoparticles to a mixed solution of 180mL anhydrous ethanol and 20mL deionized water, stir evenly, ultrasonically disperse for 20min, add 0.9g of silane coupling agent KH-570, adjust the pH to 4, and react at 70℃ and 400rpm for 6h. After the reaction is completed, centrifuge, wash with ethanol and deionized water, and vacuum dry at 70℃ for 8h to obtain KH-570 modified lignin. Step 5: Under nitrogen protection, 6g of KH-570 modified lignin was added to 100mL of N,N-dimethylformamide, stirred evenly, and ultrasonically dispersed for 10min. Then, 7g of hydroxyethyl methacrylate and 0.07g of azobisisobutyronitrile catalyst were added, and the mixture was stirred at 75℃ and 400rpm for 10h. After the reaction was completed, the mixture was cooled, transferred to a methanol aqueous solution to precipitate, filtered, washed with methanol and deionized water, and vacuum dried at 70-80℃ for 6-8h to obtain polyhydroxyethyl methacrylate-lignin. Step 6: Add 1.7g of potassium tert-butoxide to 50mL of p-ethylene glycol dimethyl ether and stir until homogeneous to obtain a potassium tert-butoxide dispersion. Under nitrogen protection, mix 65g of isosorbide-terminated hydroxyl polybutylene succinate, 45g of castor oil polyester polyol and 17g of hexamethylene diisocyanate and stir until homogeneous. Add 0.03g of catalyst dibutyltin dilaurate and stir at 90℃ and 400rpm for 2h. After the reaction is complete, add 500mL of p-ethylene glycol dimethyl ether and stir until homogeneous. Add the potassium tert-butoxide dispersion under ice-water bath conditions and stir at 400rpm for 1h. Add 14g of chloropolydimethylsiloxane and stir at 400rpm for 2h under ice-water bath conditions. After the reaction is complete, return to room temperature and terminate the reaction with saturated ammonium chloride aqueous solution. After rotary evaporation, wash with deionized water and vacuum dry at 70℃ for 6h to obtain polydimethylsiloxane-polyurethane. Step 7: Mix 88g of polydimethylsiloxane-polyurethane with 12g of poly(hydroxyethyl methacrylate)-lignin, stir evenly, and then transfer to a twin-screw extruder. Set the temperature of zone 1 to 170℃, zone 2 to 180℃, zone 3 to 190℃, and zone 4 to 195℃. Extrude and cast the mixture into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

[0028] Experiment: The testing method for the stain-resistant and environmentally friendly composite packaging material is the same as that in Example 1.

[0029] The test results are as follows: tensile strength is 36.4 MPa, elongation at break is 450%, water contact angle is 114°, shrinkage area ratio of water-based marker ink is 95%, and shrinkage area ratio of oil-based marker ink is 86%.

[0030] Example 3: A method for preparing a stain-resistant and environmentally friendly composite packaging material, specifically as follows: Step 1: Under nitrogen protection, 120g castor oil and 40g 1,6-hexanediol were mixed and stirred evenly. The mixture was heated to 190℃, and 0.1g tetrabutyl titanate catalyst was added. The mixture was stirred at 190℃ and 400rpm for 3 hours. Then, 50g sebacic acid was added and stirred evenly. The mixture was heated to 220℃ and evacuated to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2 hours. After the reaction was completed, the mixture was cooled and post-processed to obtain castor oil polyester polyol. Step 2: Under nitrogen protection, 120g of dimethyl succinate, 75g of 1,4-butanediol and 20g of isosorbide were mixed and stirred evenly. The mixture was heated to 180℃, and 0.2g of magnesium acetate catalyst was added. The mixture was stirred at 180℃ and 400rpm for 2 hours. Then, 0.2g of tetrabutyl titanate catalyst was added and stirred evenly. The mixture was heated to 220℃ and evacuated to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2 hours. After the reaction was completed, the mixture was cooled and post-processed to obtain isosorbide-terminated hydroxyl polybutylene succinate. Step 3: Under nitrogen protection, 14g of hydroxyl-terminated polydimethylsiloxane and 7g of pyridine were added to 100mL of toluene and stirred until homogeneous. 9g of thionyl chloride was added, and the mixture was stirred at 40℃ and 400rpm for 10h. After the reaction was completed, the reaction was terminated with ice-cold deionized water. The mixture was separated into liquid and liquid phases. The aqueous phase was extracted with toluene, and the organic phase was washed successively with dilute hydrochloric acid, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution. The mixture was dried over anhydrous sodium sulfate, filtered, and toluene was removed by rotary evaporation. The mixture was then dried under vacuum at 60℃ for 10h to obtain chlorinated polydimethylsiloxane. Step 4: Add 12g of lignin nanoparticles to a mixed solution of 180mL anhydrous ethanol and 20mL deionized water, stir evenly, ultrasonically disperse for 20min, add 1g of silane coupling agent KH-570, adjust the pH to 4, and react at 70℃ and 400rpm for 6h. After the reaction is completed, centrifuge, wash with ethanol and deionized water, and vacuum dry at 70℃ for 8h to obtain KH-570 modified lignin. Step 5: Under nitrogen protection, 7g of KH-570 modified lignin was added to 100mL of N,N-dimethylformamide, stirred evenly, and ultrasonically dispersed for 10min. Then, 9g of hydroxyethyl methacrylate and 0.1g of azobisisobutyronitrile catalyst were added, and the mixture was stirred at 75℃ and 400rpm for 10h. After the reaction was completed, the mixture was cooled, transferred to a methanol aqueous solution to precipitate, filtered, washed with methanol and deionized water, and vacuum dried at 70-80℃ for 6-8h to obtain polyhydroxyethyl methacrylate-lignin. Step 6: Add 2g of potassium tert-butoxide to 50mL of p-ethylene glycol dimethyl ether and stir until homogeneous to obtain a potassium tert-butoxide dispersion. Under nitrogen protection, mix 70g of isosorbide-terminated hydroxyl polybutylene succinate, 50g of castor oil polyester polyol and 20g of hexamethylene diisocyanate and stir until homogeneous. Add 0.03g of catalyst dibutyltin dilaurate and stir at 90℃ and 400rpm for 2h. After the reaction is complete, add 500mL of p-ethylene glycol dimethyl ether and stir until homogeneous. Add the potassium tert-butoxide dispersion under ice-water bath conditions and stir at 400rpm for 1h. Add 15g of chlorinated polydimethylsiloxane and stir at 400rpm for 2h under ice-water bath conditions. After the reaction is complete, return to room temperature and terminate the reaction with saturated ammonium chloride aqueous solution. After rotary evaporation, wash with deionized water and vacuum dry at 70℃ for 6h to obtain polydimethylsiloxane-polyurethane. Step 7: Mix 86g of polydimethylsiloxane-polyurethane with 14g of poly(hydroxyethyl methacrylate)-lignin, stir evenly, and then transfer to a twin-screw extruder. Set the temperature of zone 1 to 170℃, zone 2 to 180℃, zone 3 to 190℃, and zone 4 to 195℃. Extrude and cast the mixture into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

[0031] Experiment: The testing method for the stain-resistant and environmentally friendly composite packaging material is the same as that in Example 1.

[0032] The test results are as follows: tensile strength is 37.2 MPa, elongation at break is 441%, water contact angle is 116°, shrinkage area ratio of water-based marker ink is 96%, and shrinkage area ratio of oil-based marker ink is 87%.

[0033] Comparative Examples 1 to 3 are technical solutions based on Example 1, as detailed below: Comparative Example 1: This comparative example relates to a method for preparing a stain-resistant and environmentally friendly composite packaging material. The difference from Example 1 is that polyhexanediol sebate is used instead of castor oil polyester polyol in the stain-resistant and environmentally friendly composite packaging material. Specifically: Step 1: Under nitrogen protection, 30g of 1,6-hexanediol and 40g of sebacic acid were mixed and stirred evenly. 0.05g of tetrabutyl titanate catalyst was added, and the vacuum was simultaneously drawn to 100Pa. The mixture was stirred at 220℃ and 400rpm for 2h. After the reaction was completed, it was cooled and post-processed to obtain polyhexanediol sebacic acid. Step 2: Add 1.5g of potassium tert-butoxide to 50mL of p-ethylene glycol dimethyl ether and stir until homogeneous to obtain a potassium tert-butoxide dispersion. Under nitrogen protection, mix 60g of isosorbide-terminated hydroxyl polybutylene succinate, 40g of polyhexanediol sebacate and 15g of hexamethylene diisocyanate and stir until homogeneous. Add 0.03g of dibutyltin dilaurate catalyst and stir at 90℃ and 400rpm for 2h. After the reaction is complete, add 500mL of p-ethylene glycol dimethyl ether and stir until homogeneous. Under ice-water bath conditions, add the potassium tert-butoxide dispersion and stir at 400rpm for 1h. Then add 13g of chloropolydimethylsiloxane and stir at 400rpm for 2h under ice-water bath conditions. After the reaction is complete, return to room temperature and terminate the reaction with saturated ammonium chloride aqueous solution. After rotary evaporation, wash with deionized water and vacuum dry at 70℃ for 6h to obtain polydimethylsiloxane-polyurethane. Step 3: Mix 90g of polydimethylsiloxane-polyurethane with 10g of poly(hydroxyethyl methacrylate)-lignin, stir evenly, and then transfer to a twin-screw extruder. Set the temperature of zone 1 to 170℃, zone 2 to 180℃, zone 3 to 190℃, and zone 4 to 195℃. Extrude and cast the mixture into a film to obtain a stain-resistant and environmentally friendly composite packaging material. The preparation methods of isosorbide-terminated hydroxyl polybutylene succinate and polyhydroxyethyl methacrylate-lignin are the same as in Example 1.

[0034] Experiment: The testing method for the stain-resistant and environmentally friendly composite packaging material is the same as that in Example 1.

[0035] The test results are as follows: tensile strength is 38.8 MPa, elongation at break is 422%, water contact angle is 105°, shrinkage area ratio of water-based marker ink is 90%, and shrinkage area ratio of oil-based marker ink is 80%.

[0036] Comparative Example 2: This comparative example relates to a method for preparing a stain-resistant and environmentally friendly composite packaging material. The difference from Example 1 is that chlorinated polydimethylsiloxane is not added to the stain-resistant and environmentally friendly composite packaging material. Specifically: Step 1: Under nitrogen protection, 60g of isosorbide-terminated hydroxyl polybutylene succinate, 40g of hydroxyl-terminated ethylene sebacate and 15g of hexamethylene diisocyanate were mixed and stirred evenly. 0.03g of dibutyltin dilaurate catalyst was added, and the mixture was stirred at 90℃ and 400rpm for 2h. After the reaction was completed, the mixture was cooled to obtain polyurethane. Step 2: Mix 90g of polyurethane with 10g of poly(hydroxyethyl methacrylate)-lignin, stir evenly, and then transfer to a twin-screw extruder. Set the temperature of zone 1 to 170℃, zone 2 to 180℃, zone 3 to 190℃, and zone 4 to 195℃. Extrude and cast the mixture into a film to obtain a stain-resistant and environmentally friendly composite packaging material. The preparation methods of isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol and poly(hydroxyethyl methacrylate)-lignin are the same as in Example 1.

[0037] Experiment: The testing method for the stain-resistant and environmentally friendly composite packaging material is the same as that in Example 1.

[0038] Test results: Tensile strength was 33.6 MPa, elongation at break was 462%, water contact angle was 95°, shrinkage area ratio of water-based marker ink was 65%, and shrinkage area ratio of oil-based marker ink was 55%.

[0039] Comparative Example 3: This comparative example relates to a method for preparing a stain-resistant and environmentally friendly composite packaging material. The difference from Example 1 is that KH-570 modified lignin is used instead of poly(hydroxyethyl methacrylate)-lignin in the stain-resistant and environmentally friendly composite packaging material. Specifically: 90g of polydimethylsiloxane-polyurethane was mixed with 10g of KH-570 modified lignin. After stirring evenly, the mixture was transferred to a twin-screw extruder. The temperature of zone 1 was set to 170℃, zone 2 to 180℃, zone 3 to 190℃, and zone 4 to 195℃. The mixture was then extruded and cast into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

[0040] The preparation methods of polydimethylsiloxane-polyurethane and KH-570 modified lignin are the same as in Example 1.

[0041] Experiment: The testing method for the stain-resistant and environmentally friendly composite packaging material is the same as that in Example 1.

[0042] Test results: Tensile strength was 32.9 MPa, elongation at break was 426%, water contact angle was 104°, shrinkage area ratio of water-based marker ink was 85%, and shrinkage area ratio of oil-based marker ink was 70%.

[0043] Conclusion: The test results show that, compared with Example 1, Comparative Example 1 used hexanediol sebacate instead of castor oil polyester polyol in the synthesis of polyurethane; the polyurethane molecular chain of Comparative Example 2 did not have PDMS segments grafted on it; and Comparative Example 3 used KH-570 modified lignin instead of poly(hydroxyethyl methacrylate)-lignin as filler. The water contact angle and water-based / oil-based marker ink shrinkage area ratio of the antifouling and environmentally friendly packaging composite materials prepared in each comparative example were lower than those in Example 1. This indicates that the antifouling and environmentally friendly packaging composite materials of the comparative examples are not as hydrophobic and antifouling as those in Example 1. In addition, this invention introduces two bio-based raw materials, castor oil and isosorbide, into the composite material system, which enhances the green and environmentally friendly properties of the composite material. The prepared antifouling and environmentally friendly composite packaging material has both excellent hydrophobicity and antifouling properties, as well as good environmental performance.

[0044] Those skilled in the art should understand that the present invention is not limited to the details of the exemplary embodiments described above. Other specific embodiments may be adopted without departing from the spirit and essential characteristics of the invention. Therefore, the above embodiments should be considered exemplary only and not restrictive, and the scope of protection of the present invention is defined by the appended claims, not by the foregoing description. All changes within the meaning and scope of the claims and their equivalents should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an anti-fouling, environmentally friendly composite packaging material, characterized by: Specifically: Step 1: Mix castor oil, 1,6-hexanediol and sebacic acid and react to obtain castor oil polyester polyol; Step 2: Mix dimethyl succinate, 1,4-butanediol and isosorbide to react and obtain isosorbide-terminated hydroxyl polybutylene succinate; Step 3: Mix and react the single-hydroxyl-terminated polydimethylsiloxane, pyridine, and thionyl chloride to obtain chlorinated polydimethylsiloxane; Step 4: After modifying the lignin nanoparticles with silane coupling agent KH-570, they are mixed and reacted with hydroxyethyl methacrylate to obtain polyhydroxyethyl methacrylate-lignin. Step 5: Mix isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol, hexamethylene diisocyanate, chlorinated polydimethylsiloxane, and potassium tert-butoxide to obtain polydimethylsiloxane-polyurethane. Then, mix polydimethylsiloxane-polyurethane and polyhydroxyethyl methacrylate-lignin evenly, melt them, and extrude and cast them into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

2. A process for the preparation of an anti-fouling, environmentally friendly composite packaging material as claimed in claim 1, characterized in that: The preparation method of castor oil polyester polyol is as follows: Under nitrogen protection, castor oil and 1,6-hexanediol were mixed and stirred until homogeneous. The mixture was heated to 180-190°C, and tetrabutyl titanate was added as a catalyst. The mixture was stirred at 180-190°C and 300-400 rpm for 2-3 hours. Sebacic acid was then added and stirred until homogeneous. The mixture was heated to 210-220°C while simultaneously applying a vacuum of 100-500 Pa. The mixture was stirred at 210-220°C and 300-400 rpm for 1-2 hours. After the reaction was completed, the mixture was cooled, dissolved in tetrahydrofuran, and then transferred to ice-cold methanol to precipitate. The precipitate was filtered, washed with methanol, and dried under vacuum at 60-70°C for 8-10 hours to obtain castor oil polyester polyol.

3. A method of preparing an anti-fouling, environmentally friendly composite packaging material according to claim 2, characterized in that: The mass ratio of castor oil, 1,6-butanediol, sebacic acid, and tetrabutyl titanate catalyst is (100-120):(30-40):(40-50):(0.05-0.1).

4. A method of preparing an anti-fouling, environmentally friendly composite packaging material according to claim 1, characterized in that: The preparation method of isosorbide-terminated hydroxyl polybutylene succinate is as follows: Under nitrogen protection, dimethyl succinate, 1,4-butanediol, and isosorbide were mixed and stirred until homogeneous. The mixture was heated to 180-190°C, and magnesium acetate catalyst was added. The mixture was stirred at 180-190°C and 300-400 rpm for 2-3 hours. Then, tetrabutyl titanate catalyst was added and stirred until homogeneous. The mixture was heated to 210-220°C while simultaneously evacuating to 100-500 Pa. The mixture was stirred at 210-220°C and 300-400 rpm for 1-2 hours. After the reaction was completed, the mixture was cooled, dissolved in tetrahydrofuran, and transferred to ice-cold methanol to precipitate. The precipitate was filtered, washed with methanol, and dried under vacuum at 60-70°C for 8-10 hours to obtain isosorbide-terminated hydroxyl polybutylene succinate.

5. The method for preparing a stain-resistant and environmentally friendly composite packaging material according to claim 4, characterized in that: The mass ratio of dimethyl succinate, 1,4-butanediol, isosorbide, magnesium acetate catalyst, and tetrabutyl titanate catalyst is (100-120):(65-75):(10-20):(0.1-0.2):(0.1-0.2).

6. The method for preparing a stain-resistant and environmentally friendly composite packaging material according to claim 1, characterized in that: The preparation method of chlorinated polydimethylsiloxane is as follows: Under nitrogen protection, hydroxyl-terminated polydimethylsiloxane and pyridine were added to toluene and stirred until homogeneous. Thionyl chloride was then added, and the mixture was stirred at 40-50°C and 300-400 rpm for 8-10 hours. After the reaction was completed, the reaction was terminated with ice-cold deionized water. The mixture was separated into liquid and liquid phases, and the aqueous phase was extracted with toluene. The organic phase was washed successively with dilute hydrochloric acid, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution. The mixture was dried over anhydrous sodium sulfate, filtered, and toluene was removed by rotary evaporation. The mixture was then vacuum dried at 60-70°C for 8-10 hours to obtain chloropolydimethylsiloxane.

7. The method for preparing a stain-resistant and environmentally friendly composite packaging material according to claim 1, characterized in that: The preparation method of poly(hydroxyethyl methacrylate)-lignin is as follows: Lignin nanoparticles were added to an ethanol aqueous solution, stirred evenly, and ultrasonically dispersed for 10-20 min. Silane coupling agent KH-570 was added, and the pH was adjusted to 4-5. The mixture was stirred at 70-80℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was centrifuged, washed with ethanol and deionized water, and vacuum dried at 70-80℃ for 6-8 h to obtain KH-570 modified lignin. Under nitrogen protection, KH-570 modified lignin was added to N,N-dimethylformamide, stirred until homogeneous, and ultrasonically dispersed for 10-20 min. Hydroxyethyl methacrylate and azobisisobutyronitrile (AIOPT) catalyst were then added, and the mixture was stirred at 70-80℃ and 300-400 rpm for 8-10 h. After the reaction was completed, the mixture was cooled, transferred to a methanol aqueous solution to precipitate, filtered, washed with methanol and deionized water, and vacuum dried at 70-80℃ for 6-8 h to obtain poly(hydroxyethyl methacrylate)-lignin.

8. A process for the preparation of an anti-fouling, eco-friendly composite packaging material as claimed in claim 1, wherein: The preparation method of stain-resistant and environmentally friendly composite packaging material is as follows: Potassium tert-butoxide was added to dimethyl ethylene glycol and stirred until homogeneous to obtain a potassium tert-butoxide dispersion. Under nitrogen protection, isosorbide-terminated hydroxyl polybutylene succinate, castor oil polyester polyol, and hexamethylene diisocyanate were mixed and stirred until homogeneous. Dibutyltin dilaurate catalyst was added, and the mixture was stirred at 80-90℃ and 300-400 rpm for 2-3 hours. After the reaction was completed, dimethyl ethylene glycol was added and stirred until homogeneous. The potassium tert-butoxide dispersion was added under ice-water bath conditions, and the mixture was stirred at 300-400 rpm for 0.5-1 hours. Chlorinated polydimethylsiloxane was then added, and the mixture was stirred at 300-400 rpm for 2-3 hours under ice-water bath conditions. After the reaction was completed, the mixture was allowed to return to room temperature, and the reaction was terminated with a saturated ammonium chloride aqueous solution. After rotary evaporation, the mixture was washed with deionized water and dried under vacuum at 60-70℃ for 6-8 hours to obtain polydimethylsiloxane-polyurethane. Polydimethylsiloxane-polyurethane and poly(hydroxyethyl methacrylate)-lignin are mixed, stirred evenly, and then transferred to a twin-screw extruder for extrusion and casting into a film to obtain a stain-resistant and environmentally friendly composite packaging material.

9. A process for the preparation of an anti-fouling, environmentally friendly composite packaging material as claimed in claim 8, characterized in that: By weight, the polydimethylsiloxane-polyurethane comprises 60-70 parts isosorbide-terminated hydroxyl polybutylene succinate, 40-50 parts castor oil polyester polyol, 15-20 parts hexamethylene diisocyanate, 1.5-2 parts potassium tert-butoxide, and 13-15 parts chlorinated polydimethylsiloxane; the mass ratio of polydimethylsiloxane-polyurethane to polyhydroxyethyl methacrylate-lignin is (86-90):(10-14); the twin-screw extrusion process conditions include a screw speed of 100-200 rpm, a zone 1 temperature of 170-180℃, a zone 2 temperature of 180-190℃, a zone 3 temperature of 190-200℃, and a zone 4 temperature of 190-200℃.

10. An anti-fouling, environmentally friendly composite packaging material, characterized by: It is prepared by any one of the preparation methods according to claims 1-9.