Environment-friendly high polymer material additive as well as preparation method and application thereof

Abstract

The invention provides an environment-friendly high polymer material additive as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials, the preparation method comprises the following steps: dissolving beta-cyclodextrin into an anhydrous solvent, adding methacryloyl chloride, controlling the molar ratio of methacryloyl chloride to beta-cyclodextrin to be 1: 1, carrying out substitution reaction, then adding excessive acetic anhydride, and carrying out heat preservation reaction to obtain the environment-friendly high polymer material additive. Carrying out acetylation reaction, and purifying to obtain modified beta-cyclodextrin; adding glycidyl methacrylate, ethylene and modified beta-cyclodextrin into a reaction kettle, and carrying out high-pressure free radical polymerization in the presence of an initiator and a chain transfer agent to obtain the environment-friendly high polymer material additive, wherein the mass ratio of the glycidyl methacrylate to the ethylene to the modified beta-cyclodextrin is (4-8): (88-94): (2-4). According to the prepared additive, the processing rheological property and mechanical toughness of a PCR material are improved, meanwhile, the release characteristic of low-volatility organic compounds is considered, and the application requirements of the fields of automobile interiors and high-end packaging are easily met.

Description

An environmentally friendly polymer material additive, its preparation method, and its application. Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an environmentally friendly polymer material additive, its preparation method, and its application. Background Technology

[0002] With increasing global emphasis on the circular economy and plastic pollution control, the high-value utilization of post-consumer recycled plastics (PCR), especially recycled polypropylene and recycled polyethylene, has become a research hotspot in the field of polymer materials. However, due to their history of multiple thermal processing and complex usage environments, PCR polyolefin materials generally face two major technical challenges: first, the decrease in melt strength and mechanical property due to polymer chain breakage; and second, the deterioration of sensory quality (i.e., severe odor problems) due to residual degradation molecules, additive degradation, and environmental pollution. This has limited the application of PCR materials to low-value, odor-insensitive fields such as underground pipelines and logistics pallets, making it difficult to enter high-value-added markets such as automotive interiors and high-end daily chemical packaging.

[0003] To address the degradation of mechanical properties in PCR materials, the industry typically uses ethylene-glycidyl methacrylate (E-GMA) copolymers as reactive compatibilizers or chain extenders. The mechanism involves the reaction of epoxy groups with the hydroxyl or carboxyl groups at the polymer chain ends, reconnecting broken molecular chains and restoring melt flow rate and toughness. However, existing E-GMA technologies have significant drawbacks in odor control, and can even produce negative effects. Because the reactivity of E-GMA requires activation through high-shear and high-temperature (typically above 220°C) extrusion processes, this harsh thermal history leads to secondary degradation of residual fatty acids and additives in the PCR matrix, generating odor-causing substances with extremely low thresholds, such as nonanal and hexanal. This results in the technical paradox of "repairing while producing odor," meaning that while improving mechanical properties, it exacerbates the odor problem.

[0004] Regarding odor control, existing solutions mostly employ physical mixing strategies, namely adding porous adsorbents (such as modified zeolite, activated carbon, diatomaceous earth, etc.) to PCR. While these adsorbents have a certain odor-capturing ability, they face insurmountable bottlenecks in practical applications: First, molten polymer chains easily cover the surface of porous materials, blocking the pores and causing a significant decrease in adsorption efficiency; second, hydrophilic inorganic adsorbent particles easily aggregate in hydrophobic polyolefin matrices, becoming stress concentration points, thus significantly reducing the notched impact strength of the material and offsetting the toughening effect brought by chain extenders; more importantly, physical adsorption is usually reversible. In high-temperature enclosed environments such as automotive interiors (e.g., summer sun exposure, with interior temperatures exceeding 60°C), adsorbed volatile organic compounds (VOCs) are easily desorbed and re-released, causing the material to fail odor testing standards.

[0005] In summary, existing single-technology approaches cannot simultaneously solve the two major challenges of chain break repair and odor removal in PCR polyolefins. Therefore, a multifunctional additive is needed that can permanently lock odor molecules through covalent bonding, possess chemical chain extension capabilities, and not migrate or desorb during processing, in order to achieve a dual upgrade in the mechanical properties and sensory quality of PCR materials. Summary of the Invention

[0006] In view of the above situation and to overcome the defects of the prior art, the purpose of this invention is to provide an environmentally friendly polymer material additive, its preparation method and application, so as to at least partially solve the problems mentioned in the background art.

[0007] The technical solution adopted by this invention is as follows: The first aspect of this invention proposes a method for preparing an environmentally friendly polymer material additive, comprising: dissolving β-cyclodextrin in an anhydrous solvent, adding methacryloyl chloride, wherein the molar ratio of methacryloyl chloride to β-cyclodextrin is 1:1, performing a substitution reaction, subsequently adding excess acetic anhydride, performing an acetylation reaction, and purifying to obtain modified β-cyclodextrin; adding glycidyl methacrylate, ethylene and the modified β-cyclodextrin into a reaction vessel, and performing high-pressure free radical polymerization in the presence of an initiator and a chain transfer agent to obtain an environmentally friendly polymer material additive; wherein the mass ratio of glycidyl methacrylate, ethylene and modified β-cyclodextrin is (4-8):(88-94):(2-4).

[0008] In some embodiments of the present invention, the anhydrous solvent is a mixture of N,N-dimethylformamide and pyridine.

[0009] In some embodiments of the present invention, the conditions for the substitution reaction include: reacting at 0-5°C for 1-2 hours under a nitrogen atmosphere, and then reacting at 20-25°C for 12-24 hours.

[0010] In some embodiments of the present invention, the conditions for the acetylation reaction include reacting at 60-80°C for 6-12 hours.

[0011] In some embodiments of the present invention, the purification includes precipitating the reaction product in ice water, filtering, washing successively with water and ethanol, and separating by silica gel column chromatography.

[0012] In some embodiments of the present invention, the initiator is tert-butyl peroxypentanoate or di-tert-butyl peroxypentanoate, and the amount of the initiator added is 100-500 ppm of the total mass of the monomer.

[0013] In some embodiments of the present invention, the chain transfer agent is propionaldehyde or propylene, and the amount of the chain transfer agent added is 0.1-2.0% of the total mass of the monomer.

[0014] In some embodiments of the present invention, the conditions for the high-pressure free radical polymerization include: a pressure of 1800-2400 bar, a temperature of 210-250°C, and a time of 1-5 minutes.

[0015] The second aspect of this invention provides an environmentally friendly polymer material additive, which is prepared by the above-described preparation method.

[0016] A third aspect of this invention provides an environmentally friendly polymer material additive, comprising a polyolefin matrix and the aforementioned environmentally friendly polymer material additive; wherein the polyolefin matrix is ​​polypropylene or polyethylene; and the amount of the environmentally friendly polymer material additive added is 3-5% of the mass of the polyolefin matrix.

[0017] The beneficial effects achieved by this invention are as follows: By introducing an ethylene-glycidyl methacrylate terpolymer containing vinyl-modified β-cyclodextrin side groups, this invention improves the overall performance of regenerated polyolefin (PCR) materials. The highly reactive epoxy groups of the glycidyl methacrylate unit, through chemical reaction with the polymer chain ends, reconstruct a long-branched structure, increasing melt viscosity and molecular weight, thereby improving the melt strength and mechanical properties of the regenerated material. The hydrophobic cavity structure and main-chain anchoring effect of the modified β-cyclodextrin unit adsorb small molecule volatiles through host-guest inclusion, and restrict the migration and desorption of adsorbates through covalent bonding, reducing the odor level of the material. The synergistic effect of both allows this additive to improve the processing rheology and mechanical toughness of PCR materials while also taking into account the low volatile organic compound release characteristics, which helps to meet the application requirements of automotive interiors and high-end packaging. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this invention.

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] To address the problems raised in the background art, the first aspect of this invention provides a method for preparing an environmentally friendly polymer material additive, comprising: dissolving β-cyclodextrin in an anhydrous solvent, adding methacryloyl chloride, controlling the molar ratio of methacryloyl chloride to β-cyclodextrin to be 1:1, carrying out a substitution reaction, subsequently adding excess acetic anhydride, carrying out an acetylation reaction, and purifying to obtain modified β-cyclodextrin; adding glycidyl methacrylate, ethylene, and modified β-cyclodextrin to a reaction vessel, and carrying out high-pressure free radical polymerization in the presence of an initiator and a chain transfer agent to obtain the environmentally friendly polymer material additive; wherein the mass ratio of glycidyl methacrylate, ethylene, and modified β-cyclodextrin is (4-8):(88-94):(2-4).

[0022] In the environmentally friendly polymer additive prepared by this invention, ethylene, glycidyl methacrylate, and modified β-cyclodextrin jointly form a random terpolymer molecular chain structure through high-pressure free radical polymerization. In this polymerization system, ethylene, as a backbone monomer, provides compatibility and crystallinity with the polyolefin matrix; glycidyl methacrylate, as a reactive monomer, provides chemical repair sites; and modified β-cyclodextrin, as a functional monomer, has methacryloyl groups introduced into its molecule that endow it with polymerization activity. Under free radical initiation, the double bonds of the three monomers open and connect randomly, so that the large cyclodextrin cavity and highly reactive epoxy groups are uniformly anchored on the polyethylene backbone, forming a polymer structure with both chemical repair and physical inclusion functions.

[0023] Compared to traditional physical blending chain extenders, the copolymer of this invention utilizes the epoxy groups of glycidyl methacrylate on its side chains to achieve highly efficient repair of PCR chain breaks. During the melt processing of PCR materials, the highly reactive epoxy groups can rapidly capture and degrade the hydroxyl or carboxyl groups at the polymer chain ends, resulting in ring-opening addition reactions. This in-situ chemical reaction reconnects the originally broken short chains into long chains or branched structures bound by covalent bonds, significantly increasing the molecular weight and viscosity of the melt, repairing molecular chain damage caused by multiple processing steps, thereby restoring the melt strength and tensile toughness of the PCR material, and solving the problem of mechanical property degradation in recycled materials.

[0024] Modified β-cyclodextrin with copolymer side chains was used to construct a molecular-level odor-trapping trap. The fully acetylated cyclodextrin eliminated its surface hydrophilic hydroxyl groups, significantly reducing surface energy and allowing it to disperse uniformly in nonpolar polyolefin melts without agglomeration. Its unique hydrophobic cavity structure strongly adsorbs residual odor-causing small molecules such as aldehydes and ketones in the melt. More importantly, because the cyclodextrin is permanently anchored to the polymer backbone via covalent bonds, this chemical bonding provides strong spatial confinement, effectively preventing the adsorbent from migrating and desorbing at high temperatures (such as in automotive interiors) or during prolonged use, thus completely solving the secondary pollution problem of traditional physical adsorbents.

[0025] In summary, this invention improves the overall performance of regenerated polyolefin (PCR) materials by introducing an ethylene-glycidyl methacrylate terpolymer containing vinyl-modified β-cyclodextrin side groups. The highly reactive epoxy groups of the glycidyl methacrylate units, through chemical reaction with the polymer chain ends, reconstruct a long-branched structure, increasing melt viscosity and molecular weight, thereby improving the melt strength and mechanical properties of the regenerated material. The hydrophobic cavity structure and main-chain anchoring effect of the modified β-cyclodextrin units adsorb small volatile molecules through host-guest inclusion, and restrict the migration and desorption of adsorbates through covalent bonding, reducing the odor level of the material. The synergistic effect of these two factors allows the additive to improve the processing rheology and mechanical toughness of PCR materials while maintaining low volatile organic compound release characteristics, helping to meet the application requirements of automotive interiors and high-end packaging.

[0026] In some embodiments, the anhydrous solvent is a mixture of N,N-dimethylformamide (DMF) and pyridine. Using a mixed solvent system of N,N-dimethylformamide (DMF) and pyridine as the reaction medium has significant technical advantages. First, DMF, as a strongly polar aprotic solvent, can effectively dissolve β-cyclodextrin containing a large number of hydroxyl groups, constructing a homogeneous reaction system and ensuring the uniformity of modification. Second, pyridine not only acts as a co-solvent in this reaction but, more importantly, serves as an acid-binding agent. It can promptly neutralize the hydrogen chloride byproduct released during the reaction of methacryloyl chloride and hydroxyl groups, effectively preventing the hydrolytic breakage of cyclodextrin glycosidic bonds or premature self-polymerization of vinyl monomers due to acid accumulation. This solvent combination synergistically ensures high selectivity of the modification reaction and the integrity of the product structure, thereby improving the synthesis yield of functional monomers.

[0027] In some embodiments, the substitution reaction conditions include: reacting at 0-5°C for 1-2 hours under a nitrogen atmosphere, followed by reacting at 20-25°C for 12-24 hours. First, the nitrogen atmosphere effectively eliminates oxygen and ambient moisture from the system, preventing hydrolysis and degradation of the highly reactive methacryloyl chloride, and inhibiting the potential oxidation or polymerization inhibition of the vinyl double bonds in the product by oxygen. Second, the initial low-temperature control at 0-5°C effectively manages the exothermic effect during the esterification process of the acyl chloride, preventing side reactions caused by local overheating. Simultaneously, the low-temperature environment facilitates improved regioselectivity through kinetic control, guiding the substitution reaction to preferentially occur at the sterically less hindered C6 primary hydroxyl group, reducing the probability of non-target site substitution or multi-substitution byproduct formation. The subsequent reaction at 20-25°C promotes a higher conversion rate, and this mild condition avoids the risk of double bond thermal self-polymerization induced by high temperatures, thus facilitating the acquisition of high-purity monofunctional modified monomers.

[0028] In some embodiments, the acetylation reaction conditions include reacting at 60-80°C for 6-12 hours. This acetylation process condition of reacting at 60-80°C for 6-12 hours achieves a balance between reaction conversion and functional group stability. First, this temperature and time range provides sufficient thermodynamic conditions to overcome the steric hindrance between the numerous hydroxyl groups in the cyclodextrin molecule, promoting the complete conversion of the remaining hydroxyl groups to acetoxy groups. This complete hydrophobic modification eliminates the hydrophilicity of cyclodextrin, significantly improving its solubility and compatibility in nonpolar polyolefin matrices and preventing the aggregation or precipitation of functional monomers in the matrix. Second, this mild heating condition effectively avoids the risk of thermal polymerization or crosslinking of the methacryloyl double bonds that may be induced by excessively high temperatures, thereby maximizing the preservation of the double bond activity of the modified monomers and ensuring their efficient integration into the polymer backbone in subsequent high-pressure polymerization steps.

[0029] In some embodiments, purification includes precipitating the reaction product in ice water, filtering, washing successively with water and ethanol, and separating by silica gel column chromatography. The purification process combining ice water precipitation, gradient washing, and column chromatography can improve the chemical purity and polymerization safety of the modified monomer.

[0030] In some embodiments, the initiator is tert-butyl peroxypentanoate or di-tert-butyl peroxypentanoate, and the amount of initiator added is 100-500 ppm of the total monomer mass. Using tert-butyl peroxypentanoate or di-tert-butyl peroxypentanoate as the initiator, and taking advantage of the good match between its decomposition temperature and the polymerization temperature of this invention (210-250°C), ensures the smooth progress of the polymerization reaction. Simultaneously, controlling the initiator dosage at a low level of 100-500 ppm effectively suppresses the violent exothermic reaction, preventing premature cross-linking of GMA epoxy groups or the formation of gel points due to localized overheating, thereby ensuring the structural uniformity and processing flowability of the copolymer product.

[0031] In some embodiments, the chain transfer agent is propionaldehyde or propylene, and the amount of chain transfer agent added is 0.1-2.0% of the total monomer mass. Using propionaldehyde or propylene as the chain transfer agent and controlling the addition amount to 0.1-2.0% effectively regulates the molecular weight and melt flow rate of the terpolymer. This specific amount of chain transfer agent terminates the growth of active chains through the chain transfer reaction, preventing the formation of ultra-high molecular weight components and gel points within the reactor, ensuring that the copolymer has a suitable melt viscosity. This not only imparts good thermal processing fluidity to the additive, allowing it to be more uniformly dispersed in the PCR matrix, but also balances the toughness and processing properties of the material, meeting the requirements of subsequent injection molding or extrusion processes.

[0032] In some embodiments, the conditions for high-pressure free radical polymerization include: a pressure of 1800-2400 bar, a temperature of 210-250°C, and a time of 1-5 minutes. Using a reaction pressure of 1800-2400 bar and a reaction temperature of 210-250°C allows for precise control of polymerization kinetics and product structure. The high reaction pressure significantly increases the density of the ethylene monomer, promoting effective copolymerization of ethylene with sterically hindered modified β-cyclodextrin monomers, ensuring uniform integration of functional monomers into the polymer chain and a high molecular weight. Simultaneously, the specific temperature window (210-250°C) combined with a short residence time (1-5 minutes) effectively prevents ring-opening self-crosslinking of the epoxy groups in glycidyl methacrylate due to high temperature or prolonged heating time, while ensuring a sufficient polymerization rate. This prevents the formation of gel points within the reactor, ensuring that the resulting terpolymer exhibits excellent melt processing properties and structural stability.

[0033] The second aspect of this invention provides an environmentally friendly polymer material additive, which is prepared by the above-described preparation method.

[0034] The third aspect of this invention provides an environmentally friendly polymer material additive, comprising a polyolefin matrix and the aforementioned environmentally friendly polymer material additive; the polyolefin matrix is ​​polypropylene or polyethylene; the amount of the environmentally friendly polymer material additive added is 3-5% of the mass of the polyolefin matrix.

[0035] The present invention will be described below through specific embodiments. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0036] Example 1: 11.35 g (0.01 mol) of dried β-cyclodextrin was dissolved in a mixed solvent of anhydrous N,N-dimethylformamide (DMF) and pyridine (volume ratio 3:1). Under nitrogen protection, the reaction system was cooled to 0-5 °C, and 1.05 g (0.01 mol) of methacryloyl chloride was slowly added dropwise. The reaction was stirred at 0-5 °C for 2 hours, and then the temperature was raised to 25 °C and the reaction was continued for 18 hours. Excess acetic anhydride (20.4 g) was added to the above reaction solution, the temperature was raised to 70 °C, and the reaction was maintained at this temperature for 8 hours. The reaction mixture was poured into ice water to precipitate, and the solid was collected by filtration. The solid was washed three times each with deionized water and ethanol, and finally purified by silica gel column chromatography. After vacuum drying, fully acetylated monomethacryloyl-6-O-β-cyclodextrin (i.e., modified β-cyclodextrin) was obtained.

[0037] In a high-pressure autoclave, ethylene, glycidyl methacrylate, and the modified β-cyclodextrin prepared above were continuously injected, with the monomer feed ratio controlled at ethylene:glycidyl methacrylate:modified β-cyclodextrin = 92:5:3. The reaction pressure was controlled at 2000 bar, the reaction temperature at 230℃, and the average residence time was 3 minutes. Tert-butyl peroxypentanoate was selected as the initiator, added at 300 ppm of the total monomer mass; propionaldehyde was selected as the chain transfer agent, added at 0.5% of the total monomer mass. After unreacted monomers were separated by a high- and low-pressure separator, the polymer melt was granulated by a pelletizer to obtain an environmentally friendly polymer additive.

[0038] By weight, 96 parts of cleaned and crushed recycled polypropylene (PCR-PP) fragments were mixed evenly with 4 parts of the environmentally friendly polymer material additive prepared above and 0.2 parts of antioxidant (1010 / 168). The mixture was added to a co-rotating twin-screw extruder, and the extruded strip was cooled, pelletized, and injection molded into standard test strips for performance testing.

[0039] Example 2: Consistent with Example 1, except that the monomer feed ratio was adjusted to ethylene: glycidyl methacrylate: modified β-cyclodextrin = 94:4:2. The reaction pressure was 1800 bar, the reaction temperature was 210°C, and the residence time was 5 minutes. The initiator tert-butyl peroxypentanoate was added at 100 ppm, and the chain transfer agent (propylene) was added at 0.1%.

[0040] Three parts of the additive were added to 97 parts of PCR-PP for extrusion granulation.

[0041] Example 3: Same as Example 1, except that the monomer feed ratio was adjusted to ethylene:glycidyl methacrylate:modified β-cyclodextrin = 88:8:4. The reaction pressure was 2400 bar, the reaction temperature was 250°C, and the residence time was 1 minute. The initiator di-tert-butyl peroxide was added at 500 ppm, and the chain transfer agent (propionaldehyde) was added at 2.0%. Five parts of this additive were added to 95 parts of PCR-PP for extrusion granulation.

[0042] Example 4: Same as Example 1, except that the acetylation reaction temperature was 60°C and the reaction time was 12 hours. The monomer feed ratio was adjusted to ethylene: glycidyl methacrylate: modified β-cyclodextrin = 90:6:4. The reaction pressure was 2200 bar and the reaction temperature was 220°C. Four parts of this additive were added to 96 parts of PCR-PP for extrusion granulation.

[0043] Example 5: Consistent with Example 1, except that the substitution reaction was carried out at 0°C for 1 hour, followed by a reaction at 20°C for 24 hours. The monomer feed ratio was adjusted to ethylene:glycidyl methacrylate:modified β-cyclodextrin = 91:7:2. The reaction pressure was 2100 bar, and the reaction temperature was 240°C. Five parts of this additive were added to 95 parts of PCR-PP for extrusion granulation.

[0044] Example 6: Same as Example 1, except that 4 parts of additive were added to 96 parts of recycled polyethylene (PCR-PE) matrix and extruded and granulated.

[0045] Comparative Example 1: The PCR-PP crushed material was directly granulated by twin-screw extrusion without the addition of any chain extender or odor adsorbent. All other conditions were the same as in Example 1.

[0046] Comparative Example 2: A commercially available ordinary ethylene-glycidyl methacrylate copolymer (E-GMA, GMA content 8%) was used instead of the additive of the present invention. The remaining conditions were the same as in Example 1.

[0047] Comparative Example 3: The additives of the present invention were replaced by physically mixing ethylene-glycidyl methacrylate copolymer with unmodified β-cyclodextrin. All other conditions were the same as in Example 1.

[0048] Comparative Example 4: This comparative example provides pure recycled polyethylene as a blank control group. 100 parts by weight of cleaned and crushed recycled polyethylene (PCR-PE) fragments were mixed thoroughly with 0.2 parts by weight of antioxidant (1010 / 168). The mixture was fed into a co-rotating twin-screw extruder and extruded and granulated under the same temperature (190-210°C) and speed conditions as in Example 6. The extruded strips were cooled, granulated, and injection molded into standard test specimens for performance testing.

[0049] Test methods: 1. Melt flow rate (MFR): Tested according to GB / T3682.1-2018 "Plastics - Determination of melt flow rate and melt volumetric flow rate of thermoplastics - Part 1: Standard methods". Polypropylene (PP) matrix (Examples 1-5 and Comparative Examples 1-3): Test conditions were 230℃ and 2.16 kg. Polyethylene (PE) matrix (Example 6): Test conditions were 190℃ and 2.16 kg.

[0050] 2. Tensile properties: Tested according to GB / T1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics". The tensile rate was set to 50 mm / min. The tensile yield strength was recorded in MPa.

[0051] 3. Notched impact strength: Tested according to GB / T1043.1-2008 "Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact testing". Type A notch was used, and the test temperature was 23℃.

[0052] 4. Odor Rating Test: The test was conducted according to the "bottle method" in GB / T35773-2017 "Determination of Odor Characteristics of Automotive Interior Materials and Components". 10g of granules was placed in a sealed glass jar and heated at 80℃±2℃ for 2 hours. A blind evaluation was conducted by three professionally trained odor assessors, and the average value was recorded. A 6-level scoring system was used: Level 1 (no odor) to Level 6 (unbearable). The target value was ≤3.0 (distinct odor, but not intrusive).

[0053] 5. Volatile Organic Compounds (VOCs) Test: Odor-causing substance residues (aldehydes): determined by headspace sampling-gas chromatography-mass spectrometry (HS-GC-MS). The peak areas of characteristic odor-causing substances such as nonanal and hexanal were quantitatively analyzed, and the removal rate relative to Comparative Example 1 was calculated.

[0054] Total volatile organic compounds (TVOC): Tested according to GB / T29786-2013 "Determination of volatile organic compounds in electronic and electrical products by gas chromatography-mass spectrometry" or with reference to the matching test method of GB / T27630 (thermal desorption-gas chromatography-mass spectrometry) commonly used in the automotive industry.

[0055] The data from the above tests were analyzed, and the results are shown in Table 1.

[0056] Table 1

[0057] Analysis of the test results in Table 1 shows that, in the PP system, compared with the untreated Comparative Example 1 (MFR 22.4 g / 10 min, impact strength 2.8 kJ / m²), Examples 1-5 with the additive of this invention significantly reduced their MFR to the injection molding grade range of 6.0-8.5 g / 10 min, while the notched impact strength increased by more than 100% (reaching 6.2-7.1 kJ / m²). In the PE system, Comparative Example 4 (pure PCR-PE) showed an increased MFR (2.2 g / 10 min) and insufficient toughness (5.5 kJ / m²) due to degradation and chain scission. However, in Example 6, after the addition of the additive, the MFR decreased to 1.2 g / 10 min, indicating that an effective chain extension reaction occurred, the melt strength was restored, and it was suitable for processing processes such as blow molding that require high melt strength; at the same time, its notched impact strength increased significantly to 12.5 kJ / m², showing excellent toughening effect. This demonstrates that the glycidyl methacrylate unit in the copolymer effectively underwent a chemical chain extension reaction with the end groups generated by PCR chain scission, reconstructing the molecular weight and introducing a long branched structure, thereby restoring the mechanical properties.

[0058] Comparative Example 2 used commercially available E-GMA chain extender. Although the mechanical properties were restored according to national standard tests, its odor rating (GB / T35773) deteriorated to level 5.0, and the TVOC and nonanal content increased instead of decreasing. This is because the high-temperature shear reaction of E-GMA induced secondary degradation of the matrix. In contrast, Examples 1-6 of this invention achieved the same or even better chain extension effect while reducing the odor rating to level 2.5-3.0 and TVOC to below 100 µg / g. This indicates that the modified β-cyclodextrin side group anchored on the molecular chain played an in-situ capture role, locking in the small molecule aldehydes and ketones produced during degradation simultaneously with the chain extension reaction, effectively solving the odor side effects caused by traditional chemical chain extension.

[0059] Comparative Example 3 employed a physical mixing method with E-GMA and β-cyclodextrin. The results showed that its impact strength (3.2 kJ / m²) was significantly lower than that of Example 1 (6.8 kJ / m²), and the improvement in odor was limited (grade 4.0). This is because physically mixed cyclodextrin exhibits poor dispersibility in the hydrophobic polyolefin matrix, with agglomerates becoming stress concentration points; simultaneously, the melt easily clogs the cyclodextrin channels. In contrast, this invention uses copolymerization to chemically bond cyclodextrin to the polymer backbone, achieving not only molecular-level dispersion but also preventing pore blockage by external macromolecules, significantly improving odor capture efficiency.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A method for preparing an environmentally friendly polymer material additive, characterized in that, include: β-Cyclodextrin was dissolved in an anhydrous solvent, and methacryloyl chloride was added at a molar ratio of 1:1 to β-cyclodextrin for a substitution reaction. Then, excess acetic anhydride was added for acetylation. After purification, modified β-cyclodextrin was obtained. Glycidyl methacrylate, ethylene, and the modified β-cyclodextrin were added to a reactor and subjected to high-pressure free radical polymerization in the presence of an initiator and a chain transfer agent to obtain an environmentally friendly polymer additive. The mass ratio of glycidyl methacrylate, ethylene, and modified β-cyclodextrin was (4-8):(88-94):(2-4).

2. The preparation method according to claim 1, characterized in that, The anhydrous solvent is a mixture of N,N-dimethylformamide and pyridine.

3. The preparation method according to claim 1, characterized in that, The conditions for the substitution reaction include: reacting at 0-5°C for 1-2 hours under a nitrogen atmosphere, and then reacting at 20-25°C for 12-24 hours.

4. The preparation method according to claim 1, characterized in that, The conditions for the acetylation reaction include reacting at 60-80°C for 6-12 hours.

5. The preparation method according to claim 1, characterized in that, The purification process includes precipitating the reaction product in ice water, filtering, washing successively with water and ethanol, and separating by silica gel column chromatography.

6. The preparation method according to claim 1, characterized in that, The initiator is tert-butyl peroxypentanoate or di-tert-butyl peroxypentanoate, and the amount of the initiator added is 100-500 ppm of the total mass of the monomer.

7. The preparation method according to claim 1, characterized in that, The chain transfer agent is propionaldehyde or propylene, and the amount of the chain transfer agent added is 0.1-2.0% of the total mass of the monomer.

8. The preparation method according to claim 1, characterized in that, The conditions for the high-pressure free radical polymerization include: a pressure of 1800-2400 bar, a temperature of 210-250°C, and a time of 1-5 minutes.

9. An environmentally friendly polymer material additive, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. A polyolefin material, characterized in that, It includes a polyolefin matrix and the environmentally friendly polymer material additive as described in claim 9; the polyolefin matrix is ​​polypropylene or polyethylene; the amount of the environmentally friendly polymer material additive added is 3-5% of the mass of the polyolefin matrix.

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