Preparation method of degradable polyethylene packaging material
By introducing branched polylactic acid grafted modified bamboo fiber into polyethylene packaging materials to enhance the interface performance, and combining it with ultraviolet light irradiation, the problem of poor degradation performance of polyethylene packaging materials was solved, biodegradation and photodegradation were achieved, and the mechanical properties of the material were improved.
Patent Information
- Application Number
- CN202510978832.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-10-10
AI Technical Summary
The degradation performance of polyethylene packaging materials is poor, which limits their further application and development in environmentally friendly fields.
By introducing branched polylactic acid grafted modified bamboo fiber into the polyethylene matrix, a degradable component is formed, which is mixed with polyethylene to enhance the interface performance and achieve photodegradation in combination with ultraviolet light irradiation.
The biodegradability and mechanical properties of polyethylene packaging materials are significantly improved. It can gradually degrade under natural conditions and accelerate degradation through ultraviolet light irradiation to protect the internal items.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of degradable polyethylene packaging materials, in particular to a method for preparing a degradable polyethylene packaging material. Background Art
[0002] Polyethylene is a common plastic with the advantages of low cost, large adjustable processing temperature range, high film-forming properties and plasticity. It has been widely used in the field of packaging materials. However, polyethylene has relatively stable chemical properties and self-degrades under natural conditions, which poses a serious threat to the environment. Therefore, the development and application of degradable polyethylene packaging materials has great social value.
[0003] Research has found that the degradation properties of polyethylene packaging materials can be effectively improved through the method of blending and modification. Patent publication number CN112646253B discloses a polyethylene packaging material. By blending, fillers and functional additives with degradable properties are added to the matrix, and the material has good compatibility with polyethylene resin. It not only has the advantages of the polyethylene packaging material itself, but also can improve the degradation properties of the polyethylene packaging material. The overall performance is excellent, making the polyethylene packaging material easy to degrade. In addition, the mechanical properties of polyethylene packaging materials are poor, which limits its further development in the current era of continuous technological development. Based on this, by adding optimized components to the matrix in a targeted manner, polyethylene packaging materials with excellent performance can be prepared, promoting its further development and application.
[0004] The present invention cites the following references: Tianjin University's master's thesis "Synthesis of Hyperbranched Star-Shaped Amphiphilic SPLA-b-PMPC Polymers and Preparation and Characterization of Their Nanoparticles" discloses the chemical structure and preparation method of polylactic acid containing azide groups. Summary of the Invention
[0005] The present invention provides a method for preparing a degradable polyethylene packaging material. The method comprises the following steps: grafting a ferrocene structure and a branched polylactic acid onto the surface of bamboo fiber to prepare a degradable component, and mixing the component with polyethylene. This method enhances the interfacial properties between the bamboo fiber and the polyethylene matrix, and helps the bamboo fiber to be evenly dispersed in the polyethylene matrix. The polyethylene packaging material can not only be biodegraded, but can also be photodegraded by ultraviolet light irradiation.
[0006] A method for preparing a degradable polyethylene packaging material comprises the following steps: Step 1, preparing branched polylactic acid; Step 2: Modify bamboo fiber with 1,1'-ferrocenedicarboxylic acid chloride and branched polylactic acid to prepare a degradable component; Step three, polyethylene, degradable component, dispersant, antioxidant and plasticizer are added into a high-speed mixer in sequence, mixed uniformly, and extruded into polyethylene packaging material by a double screw extruder.
[0007] Further, the preparation method of the branched polylactic acid is: Under the action of cuprous halide, the azido group in the polylactic acid structure containing the azido group and the alkyne group in the 1,9-decadiyne structure undergo a continuous "click" reaction, and then a branched polylactic acid with a branched structure is formed.
[0008] Further, the cuprous halide is one of cuprous bromide, cuprous chloride or cuprous iodide.
[0009] Further, the preparation method of the degradable component is: Step S1: the sodium hydroxide solution is used to treat the bamboo fiber to improve the reaction activity of the bamboo fiber, and the hydroxylated bamboo fiber is obtained; Step S2: under the action of the organic base, the hydroxyl group on the surface of the hydroxylated bamboo fiber reacts with the acyl chloride group in the 1,1'-ferrocene dicarboxylic acid chloride structure to obtain the acyl chloride bamboo fiber; Step S3: under the action of triethylamine, the acyl chloride group on the surface of the acyl chloride bamboo fiber reacts with the hydroxyl group in the branched polylactic acid structure to obtain the degradable component.
[0010] Further, the mass fraction of the sodium hydroxide solution is 10-30%.
[0011] Further, the organic base is one of triethylamine or pyridine.
[0012] Further, the preparation method of the polyethylene packaging material in step three is: Step SS1: 50-70 parts by weight of polyethylene, 4-8 parts by weight of degradable component, 1-3 parts by weight of dispersant, 1-2 parts by weight of antioxidant and 2-3 parts by weight of plasticizer are added into a high-speed mixer in sequence, the rotation speed is set to 200-400 r / min, and after mixing for 1-2 h, a premix is obtained; Step SS2: the premix is transferred to a double screw extruder for extrusion molding to obtain the polyethylene packaging material.
[0013] Further, in the double screw extruder, the temperature of the extruder feeding section is set to 160-170℃, the die head temperature is set to 190-200℃, the compression section temperature is set to 180-190℃, and the die temperature is set to 200-210℃.
[0014] Furthermore, the dispersant is one of polyethylene wax, zinc stearate or liquid paraffin.
[0015] Furthermore, the antioxidant is one of antioxidant 168, antioxidant 1076 or antioxidant 1010.
[0016] Furthermore, the plasticizer is one of dibutyl phthalate, dioctyl phthalate, dibutyl sebacate or dioctyl sebacate.
[0017] Beneficial effects of the present invention: The present invention prepares a degradable component by grafting a ferrocene structure and a branched polylactic acid onto the surface of bamboo fiber, and then adds the degradable component to a polyethylene matrix, mixes, and extrudes to prepare a polyethylene packaging material. If the bamboo fiber is directly added to the polyethylene matrix, the compatibility is poor. After the bamboo fiber is organically modified, it has good interface properties with the polyethylene matrix and can be relatively evenly dispersed in the polyethylene matrix to form a good filling effect.
[0018] The bamboo fiber in the degradable component is a natural plant fiber with good biodegradability. It can be gradually degraded by the action of microorganisms under natural conditions. The branched polylactic acid on the surface of the bamboo fiber is a new type of biodegradable material that can be degraded into water and carbon dioxide in the environment. It has good biodegradability and biocompatibility. According to tests, the mass loss rate of the polyethylene packaging material after 320 days of landfill is 34.7%, which proves that the polyethylene packaging material prepared by the present invention has excellent biodegradability.
[0019] Ferrocene contained in the degradable component can be used as a photosensitizer. According to the number average molecular weight of polyethylene packaging materials before and after UV degradation tested by gel permeation chromatography (GPC), after 5 days of UV irradiation, the number average molecular weight M n，GPC The large decrease proves that the polyethylene packaging material prepared by the present invention can be photodegraded by ultraviolet light irradiation.
[0020] Bamboo fiber has the characteristics of high strength and high modulus, which plays a good role in dispersing stress and transferring load in the matrix, effectively enhancing the mechanical properties of polyethylene packaging materials. Secondly, the rigid ferrocene and branched structure on the surface of bamboo fiber further enhance the mechanical properties of polyethylene packaging materials, making polyethylene packaging materials better able to resist deformation or damage when subjected to external impact or extrusion, thereby protecting the internal items and significantly improving the durability of polyethylene packaging materials. DETAILED DESCRIPTION
[0021] The degradation performance of polyethylene packaging material is poor, therefore, the degradation performance of polyethylene packaging material is improved by blending modification method, and accordingly, a degradable component containing biodegradation and photodegradation is developed to improve the degradation performance of polyethylene packaging material. Example one
[0022] I. Preparation of branched polylactic acid Under the action of cuprous bromide, the azido group in the azido group-containing polylactic acid structure reacts with the alkyne group in the 1,9-decadiyne structure through a continuous "click" reaction, and then a branched polylactic acid with a branched structure is formed, i.e. branched polylactic acid; The specific experimental steps for synthesizing branched polylactic acid are as follows: 0.25 g of azido group-containing polylactic acid, 0.4 g of 1,9-decadiyne, 16 mg of cuprous bromide, 35 mg of 2,2-bipyridine and a stirring rod are added to a 5 mL sealed tube, the sealed tube is vacuumed and purged with nitrogen three times, then 4 mL of anhydrous methanol protected by nitrogen and 3 mL of N,N-dimethylformamide are added, dissolved, then liquid nitrogen is frozen for 10 min, vacuumed for 15 min, and purged with nitrogen, and at the same time, the frozen water is thawed, and the above steps are repeated three times, then the vacuum sealed tube is transferred to a 150℃ oil bath for reaction for 3 h, then the sealed tube is opened, and tetrahydrofuran is used as the solvent, and the obtained solution is concentrated by rotary evaporation, then precipitated in cold ether, and the precipitate is collected and vacuum dried to obtain branched polylactic acid.
[0023] II. Preparation of degradable component Step S1: The bamboo fiber is treated with sodium hydroxide solution to improve the reaction activity of the bamboo fiber, and hydroxylated bamboo fiber is obtained; The specific experimental steps for synthesizing hydroxylated bamboo fiber are as follows: 5 g of bamboo fiber is added to 50 mL of 10% sodium hydroxide solution, ultrasonic treatment for 30 min, then placed in an environment of 80℃ and stirred for 3 h, filtered, then washed with purified water until the pH value of the solution is 7, and dried at 80℃ for 12 h to obtain hydroxylated bamboo fiber; The bamboo fiber is purchased from Fujian Haibo Ses Chemical Technology Co., Ltd., and its specifications are: average length 5.99 cm, average diameter 0.11 mm; Step S2: Under the action of triethylamine, the hydroxyl group on the surface of the hydroxylated bamboo fiber reacts with the acyl chloride group in the 1,1'-ferrocene dicarboxylic acid chloride structure to obtain acyl chloride bamboo fiber; The specific experimental steps for synthesizing chlorinated bamboo fiber are as follows: 1.4 g of 1,1'-ferrocenedicarboxylic acid chloride and 10 mL of tetrahydrofuran are added to a reactor and mixed evenly. Then, 3 g of hydroxylated bamboo fiber is dissolved in 10 mL of tetrahydrofuran and added to the reactor at 0°C. 0.8 g of triethylamine is then added. After the addition is complete, the system temperature is controlled at 10°C. The reaction is carried out for 10 hours. The product is then filtered, collected, washed, and dried to obtain chlorinated bamboo fiber. Step S3: Under the action of triethylamine, the acyl chloride groups on the surface of the chlorinated bamboo fiber react with the hydroxyl groups in the branched polylactic acid structure to produce a degradable component; The specific experimental steps for synthesizing the biodegradable component are as follows: 3 g of chlorinated bamboo fiber and 50 mL of dimethyl sulfoxide are stirred to form a uniform liquid material, 1.8 g of branched polylactic acid is added to the liquid material, mixed evenly, and then 1 g of triethylamine is added. The mixture is stirred at room temperature for 8 hours, and the solid material is separated. After washing and drying, the biodegradable component can be obtained. Example 2
[0024] Preparation of polyethylene packaging materials Step SS1: 60 g of polyethylene, 6 g of a degradable component, 2 g of zinc stearate, 1.5 g of antioxidant 168, and 2.5 g of dioctyl phthalate were added to a high-speed blender at a speed of 300 r / min and mixed for 1.5 h to obtain a premix; Step SS2: The premix is transferred to a twin-screw extruder, and the temperature of the feed section of the extruder is set to 165°C, the head temperature is set to 195°C, the compression section temperature is set to 185°C, and the die temperature is set to 205°C. Extrusion molding is performed to obtain a polyethylene packaging material.
[0025] Among them, polyethylene was purchased from Dongguan Mingyuan Plastic Co., Ltd. with the brand name FB3000.
[0026] Comparative Example 1 Preparation of polyethylene packaging materials Step SS1: 60 g of polyethylene, 2 g of zinc stearate, 1.5 g of antioxidant 168, and 2.5 g of dioctyl phthalate were added to a high-speed blender in sequence, the speed was set to 300 r / min, and the mixture was mixed for 1.5 h to obtain a premix; Step SS2: The premix is transferred to a twin-screw extruder, and the temperature of the feed section of the extruder is set to 165°C, the head temperature is set to 195°C, the compression section temperature is set to 185°C, and the die temperature is set to 205°C. Extrusion molding is performed to obtain a polyethylene packaging material.
[0027] Performance testing ① The polyethylene packaging materials prepared in Example 2 of the present invention and Comparative Example 1 were prepared into samples that met the test specifications. Mechanical properties were tested on a WDS-100M universal tensile testing machine produced by Jinan Chenda Testing Machine Manufacturing Co., Ltd. The tensile strength of the samples was tested in accordance with GB / T 1040.3-2006 "Determination of Tensile Properties of Plastics - Part 3: Test Conditions for Film and Sheeting". The specific test results are shown in Table 1. ② The UV degradation test method is as follows: The polyethylene packaging materials prepared in Example 2 of the present invention and Comparative Example 1 were cut into 5 cm × 5 cm samples, and irradiated from one side with a UV lamp having a wavelength of 254 nm and an intensity of 40 W at a distance of 15 cm from the sample for 5 days. The number average molecular weight of the samples before and after UV degradation was measured by gel permeation chromatography (GPC). The specific test results are shown in Table 1; ③ The biodegradation experimental method is as follows: the soil burial method is used. After weighing the polyethylene packaging materials prepared in Example 2 of the present invention and Comparative Example 1, 3 parallel samples are set up in each group and buried in the soil at a burial depth of 20 cm. The temperature and relative humidity are controlled at 25°C and 75%, respectively. The polyethylene packaging material degrading microorganisms are derived from the soil microbial community. The samples are taken out after 320 days. After being taken out, the soil on the polyethylene packaging material sample is first removed with a brush. Then, the surface of the sample is gently wiped with anhydrous ethanol to further remove impurities on the surface. The sample is then placed at 60°C and vacuum-dried for 24 hours. The mass of the polyethylene packaging material sample before and after degradation is accurately weighed using an electronic balance (0.0001g). The mass is averaged and the mass loss rate of the polyethylene packaging material is calculated according to the following formula: P = (M1-M2) / M1×100%, where M1 is the mass of the polyethylene packaging material before degradation and M2 is the mass of the polyethylene packaging material after degradation. The specific test results are shown in Table 1: Table 1 Performance test
[0028] From the data in Table 1, it can be concluded that the polyethylene packaging material prepared in Example 2 of the present invention contains a degradable component. Compared with Comparative Example 1, the longitudinal and transverse tensile strengths of the sample are significantly enhanced. Therefore, the polyethylene packaging material prepared in the present invention has excellent mechanical properties. After 5 days of ultraviolet irradiation, the molecular weight of the polyethylene packaging material prepared in Example 2 of the present invention decreased from 23400 to 3800, a decrease of 83.8%. Therefore, the polyethylene packaging material prepared in the present invention can be photodegraded by ultraviolet irradiation. The polyethylene packaging material prepared in Example 2 of the present invention has a mass loss rate of 34.7% after 320 days of landfilling compared to that in Comparative Example 1. Therefore, the polyethylene packaging material prepared in the present invention can be biodegraded.
Claims
1. A method for preparing a degradable polyethylene packaging material, characterized in that: The following steps are involved: Step 1: prepare branched polylactic acid, the preparation method of which is as follows: Under the action of cuprous halide, a click reaction occurs between the azide group in the azide-containing polylactic acid structure and the alkynyl functional group in the 1,9-decadiyne structure, thereby forming polylactic acid with a branched structure, namely branched polylactic acid; Step 2: Modify bamboo fiber with 1,1'-ferrocenedicarboxylic acid chloride and branched polylactic acid to prepare a degradable component; The preparation method of the degradable component is: Step S1: treating bamboo fibers with a sodium hydroxide solution to obtain hydroxylated bamboo fibers; Step S2: Under the action of an organic base, the hydroxyl groups on the surface of the hydroxylated bamboo fiber react with the acyl chloride groups in the 1,1'-ferrocenedicarboxylic acid chloride structure to obtain acyl chloride bamboo fiber; Step S3: Under the action of triethylamine, the acyl chloride groups on the surface of the chlorinated bamboo fiber react with the hydroxyl groups in the branched polylactic acid structure to produce a degradable component; Step three: adding polyethylene, degradable components, dispersants, antioxidants and plasticizers into a high-speed mixer and mixing them evenly, and then extruding them through a twin-screw extruder to obtain polyethylene packaging materials.
2. The method for preparing a degradable polyethylene packaging material according to claim 1, characterized in that: The cuprous halide is one of cuprous bromide, cuprous chloride or cuprous iodide.
3. The method for preparing a degradable polyethylene packaging material according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution is 10-30%.
4. The method for preparing a degradable polyethylene packaging material according to claim 1, characterized in that: The organic base is one of triethylamine or pyridine.
5. The method for preparing a degradable polyethylene packaging material according to claim 1, characterized in that: The preparation method of the polyethylene packaging material in step 3 is: Step SS1: adding 50-70 parts by weight of polyethylene, 4-8 parts by weight of a degradable component, 1-3 parts by weight of a dispersant, 1-2 parts by weight of an antioxidant, and 2-3 parts by weight of a plasticizer to a high-speed mixer, setting the speed to 200-400 r / min, and mixing for 1-2 hours to obtain a premix; Step SS2: transferring the premix to a twin-screw extruder and extruding the premix to obtain a polyethylene packaging material.
6. The method for preparing a degradable polyethylene packaging material according to claim 5, characterized in that: In the twin-screw extruder, the temperature of the extruder feeding section is set to 160-170°C, the head temperature is set to 190-200°C, the compression section temperature is set to 180-190°C, and the die temperature is set to 200-210°C.
7. The method for preparing a degradable polyethylene packaging material according to claim 1 or 5, characterized in that: The dispersant is one of polyethylene wax, zinc stearate or liquid paraffin.
8. The method for preparing a degradable polyethylene packaging material according to claim 1 or 5, characterized in that: The antioxidant is one of antioxidant 168, antioxidant 1076 or antioxidant 1010.
9. The method for preparing a degradable polyethylene packaging material according to claim 1 or 5, characterized in that: The plasticizer is one of dibutyl phthalate, dioctyl phthalate, dibutyl sebacate or dioctyl sebacate.
Citation Information
Patent Citations
Polyethylene packaging materials
CN112646253B