Functional bio-based plasticizer modified cellulose diacetate colloidal particles and preparation method thereof

Abstract

The invention discloses functional bio-based plasticizer modified cellulose diacetate colloidal particles and a preparation method thereof, and relates to the technical field of high polymer materials, the functional bio-based plasticizer modified cellulose diacetate colloidal particles comprise cellulose diacetate, a functional bio-based plasticizer and a stabilizer; wherein the cellulose diacetate accounts for 45-84.8 parts by weight; 15 to 35 parts of a functionalized bio-based plasticizer; 0.2 to 2 parts of a stabilizer; the functionalized bio-based plasticizer is prepared from a compatilizer and a bio-based plasticizer through a ring-opening esterification reaction, and is prepared based on the formula. According to the invention, a functionalized bio-based plasticizer is introduced into a cellulose diacetate system, so that bio-based plasticizer molecules and cellulose diacetate molecules form a good interfacial compatible structure through side chain active functional groups while keeping a flexible long-chain structure to provide a plasticizing effect; therefore, the compatibility stability and the structural uniformity of a material system are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a functionalized bio-based plasticizer-modified cellulose diacetate granules and its preparation method. Background Technology

[0002] Cellulose diacetate, as an organic ester-based bioplastic polymer, not only possesses biodegradability but also exhibits excellent Young's modulus and tensile strength, making it widely used in eyewear materials, food packaging, electronics, and pharmaceuticals. Due to the strong intermolecular forces of cellulose diacetate, plasticizers are needed to lower its glass transition temperature; otherwise, it will begin to decompose before the melt processing temperature. Plasticization of cellulose diacetate is mainly divided into two methods: external plasticization and internal plasticization. External plasticization involves directly mixing and extruding the plasticizer with the resin. Its disadvantages include poor compatibility and problems such as oiliness and high haze. Internal plasticization involves grafting the plasticizer onto the cellulose acetate molecular chain, improving plasticization efficiency and compatibility, but the complexity of the reaction hinders industrial production.

[0003] Phthalate plasticizers are the most commonly used plasticizers, but due to their developmental and reproductive toxicity, they are facing increasing restrictions. Therefore, the demand for environmentally friendly plasticizers is growing rapidly. These plasticizers require cellulose diacetate materials to achieve a relative biodegradability rate of ≥90% within 60-120 days under industrial or household composting conditions, with degradation products having no adverse effects on compost quality or the ecological environment. In industrial production, environmentally friendly cellulose diacetate plasticizing treatment typically uses glycerides and citrates. However, these low-molecular-weight plasticizers, being external plasticizers, not only volatilize during processing but also significantly weaken the material's mechanical properties. Furthermore, cellulose diacetate is easily decomposed by temperature and shear stress during high-temperature processing, forming yellowing substances. Simultaneously, stabilizers cannot effectively exert their antioxidant effects, resulting in high yellowness values ​​in the produced granules, thus limiting its potential applications. Therefore, it is necessary to link cellulose diacetate molecules with bio-based plasticizers possessing antioxidant effects to improve its processing performance and thermal stability.

[0004] For example, Chinese patent (CN108059734A) discloses an environmentally friendly cellulose diacetate material, which involves the co-addition of two environmentally friendly plasticizers. However, these external plasticizers tend to migrate out during high-temperature processing and subsequent product use, leading to a decline in material performance. Furthermore, repeated high-temperature processing can deactivate the added antioxidants, significantly increasing the material's yellowness and affecting its normal use. Therefore, plasticizers need to lower the glass transition temperature of cellulose diacetate while simultaneously improving the material's toughness and antioxidant properties. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a functionalized bio-based plasticizer-modified cellulose diacetate granules and its preparation method, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides functionalized bio-based plasticizer-modified cellulose diacetate particles, comprising cellulose diacetate, a functionalized bio-based plasticizer, and a stabilizer; By weight: Cellulose diacetate content: 45–84.8 parts; The functionalized bio-based plasticizer is 15–35 parts; The stabilizer is 0.2–2 parts; The functionalized bio-based plasticizer is prepared by ring-opening esterification reaction between a compatibilizer and a bio-based plasticizer.

[0007] To further optimize this technical solution, in the functionalized bio-based plasticizer, The compatibilizer is at least one of maleic anhydride, itaconic anhydride, glycidyl methacrylate, and methyl acrylate. The bio-based plasticizer is one or more of epoxidized soybean oil, epoxidized fatty acid methyl ester, epoxidized tall oleate, and epoxidized castor oil.

[0008] To further optimize this technical solution, the cellulose diacetate is prepared from wood pulp or cotton pulp as raw material, and the bound acid of the cellulose diacetate is 52.0%–56.0%.

[0009] To further optimize this technical solution, the stabilizer is at least one or a mixture of hindered phenolic antioxidants and phosphite antioxidants.

[0010] To further optimize this technical solution, the stabilizer is a mixture of hindered phenolic antioxidants and phosphite antioxidants, with each of the hindered phenolic antioxidants and phosphite antioxidants accounting for 50%.

[0011] A method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles, based on the above-mentioned functionalized bio-based plasticizer-modified cellulose diacetate particles, includes the following specific preparation steps: S1, Preparation of functionalized bio-based plasticizers by reaction; S2, purification treatment of functionalized bio-based plasticizers; S3, drying pretreatment of cellulose diacetate; S4, cellulose diacetate gum powder mixing and curing treatment; S5, melt blending extrusion granulation.

[0012] To further optimize this technical solution, in step S1, the bio-based plasticizer and compatibilizer are added to a reaction vessel and mixed. The molar ratio of the anhydride group in the compatibilizer to the epoxy group in the bio-based plasticizer is controlled to be 0.8:1. Triethylamine, accounting for about 0.5% of the total material mass, is added to the system as a catalyst. The reaction is carried out under nitrogen protection. The reaction system is stirred to make it fully homogeneous. The temperature is gradually raised to 110-130°C and maintained for 2-4 hours to allow the anhydride group and epoxy group to undergo a ring-opening esterification reaction, thereby obtaining a functionalized bio-based plasticizer intermediate product with active functional group structure on the side chain.

[0013] To further optimize this technical solution, in step S2, after the reaction in step S1 is completed, the reaction system is subjected to vacuum distillation. By reducing the system pressure and maintaining the temperature, the low molecular weight monomers and volatile byproducts that did not participate in the reaction are effectively removed, thereby obtaining a functionalized bio-based plasticizer.

[0014] To further optimize this technical solution, in step S4, the cellulose diacetate powder treated in step S3 is mixed with the functionalized bio-based plasticizer obtained in step S2 at a mass ratio of 7:3. The mixture is mechanically stirred at room temperature for 30 minutes to allow the functionalized bio-based plasticizer to form a uniform distribution on the surface of the cellulose diacetate particles. Subsequently, the mixture is placed in a sealed environment for curing treatment for 12 to 36 hours to allow the plasticizer to gradually diffuse into the interior of the cellulose diacetate particles and form a stable and compatible system. After curing, a stabilizer is added and the mixture is stirred again to obtain the powder mixture.

[0015] To further optimize this technical solution, in step S5, the rubber powder mixture obtained in step S4 is added to the hopper of a twin-screw extruder for melt blending. The twin-screw shearing action causes cellulose diacetate and functionalized bio-based plasticizer to be uniformly dispersed and form a stable composite system. During the processing, the temperature of each temperature zone of the extruder is controlled from the feeding section to the die section as follows: 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃ and 230℃. Under this temperature gradient, the material gradually plasticizes and completes melt blending. Strips are extruded from the die, and after cooling and pelletizing, uniform and stable functionalized bio-based plasticizer modified cellulose diacetate granules are obtained.

[0016] Compared with the prior art, the present invention provides a functionalized bio-based plasticizer-modified cellulose diacetate granules and its preparation method, which has the following beneficial effects: This invention relates to a functionalized bio-based plasticizer-modified cellulose diacetate (CDE) particles and its preparation method. By introducing a functionalized bio-based plasticizer into the CDE system, the bio-based plasticizer molecules maintain a flexible long-chain structure to provide plasticizing effects while forming a good interfacial compatibility structure with CDE molecules through side-chain active functional groups. This significantly improves the compatibility stability and structural uniformity of the material system. During high-temperature processing, the functionalized plasticizer effectively reduces the migration and precipitation tendency of the plasticizer, reduces oil seepage on the material surface, and captures active free radicals generated during the thermal degradation of CDE through its residual epoxy active groups, inhibiting chain degradation reactions, thereby reducing initial yellowing and improving long-term thermal stability. Simultaneously, the flexible aliphatic chain structure and high molecular weight of the plasticizer can form a stable energy dissipation structure inside the material, allowing external stress to be uniformly transmitted and released at the microscale. This significantly improves the toughness, impact resistance, and processing stability of the CDE material, achieving a comprehensive performance of low migration, high stability, and high toughness while maintaining good processing fluidity. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles proposed in this invention. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0022] Functionalized bio-based plasticizer-modified cellulose diacetate granules, characterized in that they comprise cellulose diacetate, a functionalized bio-based plasticizer, and a stabilizer. Specifically, by weight: cellulose diacetate comprises 45–84.8 parts; the functionalized bio-based plasticizer comprises 15–35 parts; and the stabilizer comprises 0.2–2 parts.

[0023] The cellulose diacetate is prepared from wood pulp or cotton pulp as raw material, and the bound acid of the cellulose diacetate is 52.0%–56.0%.

[0024] The stabilizer is at least one or a mixture of hindered phenolic antioxidants and phosphite antioxidants. When the stabilizer is a mixture of hindered phenolic antioxidants and phosphite antioxidants, the proportion of each is 50% to improve the antioxidant stability after multiple high-temperature processing and reduce the increase in yellowness.

[0025] The functionalized bio-based plasticizer is prepared by a ring-opening esterification reaction between a compatibilizer and a bio-based plasticizer. The compatibilizer is at least one of maleic anhydride, itaconic anhydride, glycidyl methacrylate, and methyl acrylate. The bio-based plasticizer is one or a mixture of epoxidized soybean oil, epoxidized fatty acid methyl ester, epoxidized tall oleate, and epoxidized castor oil. This functionalized bio-based plasticizer belongs to the category of plasticizers with active functional groups on the side chains. It can act as an internal and external plasticizer for cellulose diacetate, reducing plasticizer migration under high-temperature and high-shear processing conditions, inhibiting oil seepage from the material surface, and simultaneously capturing the active free radicals generated by the thermal decomposition of cellulose diacetate using its retained active epoxy functional groups, terminating the chain degradation reaction, reducing initial yellowing, and improving long-term thermal stability. Furthermore, relying on its high molecular weight and flexible long fatty chain structure, as well as the strong compatibility interface formed with cellulose diacetate, it achieves effective stress transfer and energy dissipation, thereby improving material toughness and reducing the risk of brittle fracture.

[0026] Reference Figure 1 A method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles, based on the above-mentioned functionalized bio-based plasticizer-modified cellulose diacetate particles, includes the following specific preparation steps: S1, preparation of functionalized bio-based plasticizers by reaction.

[0027] Specifically, the bio-based plasticizer and compatibilizer are added to a reaction vessel and mixed. The molar ratio of the anhydride groups in the compatibilizer to the epoxy groups in the bio-based plasticizer is controlled at 0.8:1. Triethylamine, accounting for about 0.5% of the total material mass, is added to the system as a catalyst. The reaction is carried out under nitrogen protection. The reaction system is stirred to make it fully homogeneous. The temperature is gradually raised to 110-130℃ and maintained for 2-4 hours to allow the anhydride groups and epoxy groups to undergo a ring-opening esterification reaction, thereby obtaining a functionalized bio-based plasticizer intermediate with active functional group structures on the side chain.

[0028] S2, purification treatment of functionalized bio-based plasticizers.

[0029] Specifically, after the reaction in step S1 is completed, the reaction system is subjected to vacuum distillation. By reducing the system pressure and maintaining the temperature, the low molecular weight monomers and volatile byproducts that did not participate in the reaction are effectively removed, thereby obtaining a high-purity functionalized bio-based plasticizer. During the purification process, the distillation temperature and vacuum level are controlled to avoid side reactions or degradation of the epoxy functional groups caused by high temperature. At the same time, it ensures that the obtained functionalized plasticizer has a stable molecular structure and high reactivity, providing a good compatibility basis for subsequent blending modification with cellulose diacetate.

[0030] S3, drying pretreatment of cellulose diacetate.

[0031] Specifically, the cellulose diacetate powder is placed in a drying device for pre-drying treatment to remove the moisture adsorbed by the raw material during storage and transportation, and to prevent degradation or bubble defects caused by the presence of moisture during subsequent melt processing. It is preferable to dry at about 80°C for about 12 hours to reduce the internal moisture content of cellulose diacetate to a suitable range, thereby ensuring stable material flow during subsequent melt blending and avoiding thermal decomposition reaction caused by moisture under high temperature processing conditions.

[0032] S4, cellulose diacetate gum powder is mixed and cured.

[0033] Specifically, the cellulose diacetate powder treated in step S3 is mixed with the functionalized bio-based plasticizer obtained in step S2 at a mass ratio of 7:3. The mixture is mechanically stirred at room temperature for 30 minutes to allow the functionalized bio-based plasticizer to form a uniform distribution on the surface of the cellulose diacetate particles. The mixture is then placed in a sealed environment for curing for 12 to 36 hours to allow the plasticizer to gradually diffuse into the interior of the cellulose diacetate particles and form a stable and compatible structure. After curing, a stabilizer is added and the mixture is stirred again to obtain the powder mixture.

[0034] S5, melt blending extrusion granulation.

[0035] Specifically, the rubber powder mixture obtained in step S4 is added to the hopper of a twin-screw extruder for melt blending. The shearing action of the twin screws causes cellulose diacetate and functionalized bio-based plasticizer to be uniformly dispersed and form a stable composite structure. During the processing, the temperature of each zone of the extruder is controlled from the feeding section to the die section as follows: 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃ and 230℃. Under this temperature gradient, the material gradually plasticizes and completes melt blending. Strips are extruded from the die, and after cooling and pelletizing, uniform and stable functionalized bio-based plasticizer modified cellulose diacetate granules are obtained.

[0036] Based on the above formulation and preparation process, the following specific examples are given using different raw materials, and a set of comparative examples are provided as a reference for the performance testing of the granules.

[0037] Example 1: Maleic anhydride and epoxidized soybean oil were mixed at a molar ratio of 0.8:1 (an anhydride to an epoxy group). Then, 0.5% triethylamine catalyst (by mass of the total materials) was added. The mixture was stirred and reacted in an oil bath at 110–130°C under nitrogen protection for 2–4 hours. After the reaction was complete, unreacted maleic anhydride monomer was removed by vacuum distillation to obtain the maleic anhydride-epoxidized soybean oil reactant.

[0038] Cellulose diacetate powder is dried at 80℃ for 12 hours. Then, cellulose diacetate and maleic anhydride-epoxidized soybean oil are mixed at a mass ratio of 70:30 for 30 minutes. After standing and maturing for 12-36 hours, a stabilizer is added and stirred to obtain a powder mixture. This mixture is then fed into the hopper of a twin-screw extruder and extruded at 150-230℃. After drying, the resulting granules are obtained. The temperatures of each section of the twin-screw extruder are set to 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, and 230℃ (from the feed section to the die section).

[0039] Example 2: Maleic anhydride and epoxidized fatty acid methyl ester were mixed at a molar ratio of anhydride to epoxy groups of 0.8:1, and then 0.5% triethylamine catalyst (by mass of the total materials) was added. The mixture was stirred and reacted in an oil bath at 110–130°C under nitrogen protection for 2–4 hours. After the reaction was completed, unreacted maleic anhydride monomer was removed by vacuum distillation to obtain the maleic anhydride-epoxidized soybean oil reactant.

[0040] Cellulose diacetate powder is dried at 80℃ for 12 hours. Then, cellulose diacetate and maleic anhydride-epoxy fatty acid methyl ester are mixed at a mass ratio of 70:30 for 30 minutes. After standing and maturing for 12-36 hours, a stabilizer is added and stirred to obtain a powder mixture. This mixture is then fed into the hopper of a twin-screw extruder and extruded and dried at 150-230℃ to obtain granules. The temperature of each section of the twin-screw extruder is set to 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, and 230℃ (from the feed section to the die section).

[0041] Example 3: Maleic anhydride and epoxy tall oleate were mixed at a molar ratio of 0.8:1, and then 0.5% triethylamine catalyst (by mass of total materials) was added. The mixture was stirred in an oil bath at 110–130°C under nitrogen protection for 2–4 hours. After the reaction was complete, unreacted maleic anhydride monomer was removed by vacuum distillation to obtain the maleic anhydride-epoxidized soybean oil reactant.

[0042] Cellulose diacetate powder is dried at 80℃ for 12 hours. Then, cellulose diacetate and maleic anhydride-epoxy tall oleate are mixed at a mass ratio of 70:30 for 30 minutes. After standing and maturing for 12-36 hours, a stabilizer is added and stirred to obtain a powder mixture. This mixture is then fed into the hopper of a twin-screw extruder and extruded and dried at 150-230℃ to obtain granules. The temperature of each section of the twin-screw extruder is set to 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, and 230℃ (from the feed section to the die section).

[0043] Example 4: Maleic anhydride and epoxidized castor oil were mixed at a molar ratio of anhydride to epoxy groups of 0.8:1, and then 0.5% triethylamine catalyst (by mass of the total materials) was added. The mixture was stirred and reacted in an oil bath at 110–130°C under nitrogen protection for 2–4 hours. After the reaction was completed, unreacted maleic anhydride monomer was removed by vacuum distillation to obtain the maleic anhydride-epoxidized soybean oil reactant.

[0044] Cellulose diacetate powder is dried at 80℃ for 12 hours. Then, cellulose diacetate and maleic anhydride-epoxidized castor oil are mixed at a mass ratio of 70:30 for 30 minutes. After standing and maturing for 12-36 hours, a stabilizer is added and stirred to obtain a powder mixture. This mixture is then fed into the hopper of a twin-screw extruder and extruded and dried at 150-230℃ to obtain granules. The temperature of each section of the twin-screw extruder is set to 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, and 230℃ (from the feed section to the die section).

[0045] Comparative Example 1: Maleic anhydride was mixed with polyethylene glycol (PEG), an environmentally friendly plasticizer with a molecular weight of 1000 g / mol, at a molar ratio of 0.8:1 (an anhydride to fatty alcohol groups). Then, 0.5% triethylamine catalyst (by mass of the total materials) was added. The mixture was stirred and reacted in an oil bath at 110–130°C under nitrogen protection for 2–4 hours. After the reaction was complete, unreacted maleic anhydride monomer was removed by vacuum distillation to obtain the maleic anhydride-PEG reactant.

[0046] Cellulose diacetate powder is dried at 80℃ for 12 hours. Then, cellulose diacetate and maleic anhydride-epoxidized soybean oil are mixed at a mass ratio of 70:30 for 30 minutes. After standing and maturing for 12-36 hours, a stabilizer is added and stirred to obtain a powder mixture. This mixture is then fed into the hopper of a twin-screw extruder and extruded at 150-230℃. After drying, the resulting granules are obtained. The temperatures of each section of the twin-screw extruder are set to 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, and 230℃ (from the feed section to the die section).

[0047] Based on Examples 1-4 and Comparative Example 1, the performance parameters of functionalized bio-based plasticizer-modified cellulose diacetate particles are shown in Table 1.

[0048] Table 1 Performance parameters of cellulose diacetate particles with different functionalized bio-based plasticizers As shown in Table 1, the functionalized bio-based plasticizer-modified cellulose diacetate particles prepared in Examples 1 to 4 exhibited excellent comprehensive performance in terms of color stability, mechanical properties, and plasticizer migration stability. Specifically, the initial yellowness of Examples 1 to 4 were 9.8, 9.5, 9.6, and 10.0, respectively, significantly lower than the 15.2 of Comparative Example 1. This indicates that the bio-based plasticizer obtained through the functionalization reaction can effectively inhibit the thermal degradation reaction of the material during processing, thereby reducing the initial yellowing of the material. In terms of yellowness after secondary processing, Examples 1 to 4 were 11.9, 13.4, 12.7, and 12.3, respectively, while Comparative Example 1 reached 20.8, indicating that the functionalized plasticizer can play a role in capturing free radicals in the system, thereby significantly improving the long-term thermal stability of the material.

[0049] Regarding processing performance, the melt flow indices of Examples 1 to 4 were 1.4 g / 10 min, 1.8 g / 10 min, 1.7 g / 10 min, and 1.5 g / 10 min, respectively, all within a suitable processing flow range. In contrast, Comparative Example 1 had a melt flow index of 2.1 g / 10 min, indicating that the functionalized plasticizer not only maintained a good plasticizing effect but also stabilized the melt flow properties of the system. Regarding optical properties, the haze of Examples 1 to 4 were 0.98%, 1.11%, 0.88%, and 1.02%, respectively, which were generally at a low level. Compared with the 1.12% of Comparative Example 1, the haze showed better transparency, indicating that the functionalized plasticizer had better compatibility with cellulose diacetate.

[0050] In terms of mechanical properties, the elongation at break of Examples 1 to 4 were 43.5%, 37.6%, 39.2%, and 42.2%, respectively, and the impact strengths were 29.1 KJ / m², 24.4 KJ / m², 26.2 KJ / m², and 28.5 KJ / m², respectively, all exhibiting good toughness and impact resistance. Although the elongation at break of Comparative Example 1 reached 50.1%, its impact strength was only 26.9 KJ / m² and its overall color stability was poor, indicating that although the traditional system has a certain degree of flexibility, the material structure stability is insufficient. More significantly, in terms of plasticizer migration and water absorption, the migration rates of Examples 1 to 4 were all approximately 1.1% to 1.2%, while that of Comparative Example 1 was 1.3%. At the same time, the water absorption rates of Examples 1 to 4 were 1.5% to 1.8%, significantly lower than that of Comparative Example 1 (4.2%). This indicates that by functionalizing the plasticizer to form a more stable and compatible structure with the cellulose diacetate system, the migration of plasticizer can be effectively inhibited and the hygroscopicity of the material can be reduced.

[0051] The test results above show that the functionalized bio-based plasticizer-modified cellulose diacetate particles prepared in Examples 1 to 4 exhibit excellent and balanced performance in terms of thermal stability, processing stability, transparency, and mechanical properties. At the same time, they significantly reduce the migration rate of plasticizers and the water absorption rate of materials. Compared with Comparative Example 1, they have obvious comprehensive performance advantages, which verifies the effectiveness of the functionalized bio-based plasticizer modification system in improving the comprehensive performance of cellulose diacetate materials.

[0052] It should be noted that 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 scope of the claims of the present invention.

Claims

1. Functionalized bio-based plasticizer-modified cellulose diacetate granules, characterized in that, Including cellulose diacetate, functionalized bio-based plasticizers, and stabilizers; By weight: Cellulose diacetate content: 45–84.8 parts; The functionalized bio-based plasticizer is 15–35 parts; The stabilizer is 0.2–2 parts; The functionalized bio-based plasticizer is prepared by ring-opening esterification reaction between a compatibilizer and a bio-based plasticizer.

2. The functionalized bio-based plasticizer-modified cellulose diacetate granules according to claim 1, characterized in that, In the functionalized bio-based plasticizer The compatibilizer is at least one of maleic anhydride, itaconic anhydride, glycidyl methacrylate, and methyl acrylate. The bio-based plasticizer is one or more of epoxidized soybean oil, epoxidized fatty acid methyl ester, epoxidized tall oleate, and epoxidized castor oil.

3. The functionalized bio-based plasticizer-modified cellulose diacetate granules according to claim 1, characterized in that, The cellulose diacetate is prepared from wood pulp or cotton pulp as raw material, and the bound acid of the cellulose diacetate is 52.0%–56.0%.

4. The functionalized bio-based plasticizer-modified cellulose diacetate granules according to claim 1, characterized in that, The stabilizer is at least one or a mixture of hindered phenolic antioxidants and phosphite antioxidants.

5. The functionalized bio-based plasticizer-modified cellulose diacetate granules according to claim 4, characterized in that, The stabilizer is a mixture of hindered phenolic antioxidants and phosphite antioxidants, with each comprising 50%.

6. A method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles, comprising preparation based on the functionalized bio-based plasticizer-modified cellulose diacetate particles according to any one of claims 1-5, characterized in that, The specific preparation steps include the following: S1, Preparation of functionalized bio-based plasticizers by reaction; S2, purification treatment of functionalized bio-based plasticizers; S3, drying pretreatment of cellulose diacetate; S4, cellulose diacetate gum powder mixing and curing treatment; S5, melt blending extrusion granulation.

7. The method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles according to claim 6, characterized in that, In step S1, the bio-based plasticizer and compatibilizer are added to a reaction vessel and mixed. The molar ratio of the anhydride group in the compatibilizer to the epoxy group in the bio-based plasticizer is controlled to be 0.8:

1. Triethylamine, accounting for about 0.5% of the total material mass, is added to the system as a catalyst. The reaction is carried out under nitrogen protection. The reaction system is stirred to make it fully homogeneous. The temperature is gradually raised to 110-130°C and maintained for 2-4 hours to allow the anhydride group and epoxy group to undergo a ring-opening esterification reaction, thereby obtaining a functionalized bio-based plasticizer intermediate with active functional group structure on the side chain.

8. The method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles according to claim 6, characterized in that, In step S2, after the reaction in step S1 is completed, the reaction system is subjected to vacuum distillation. By reducing the system pressure and maintaining the temperature, the low molecular weight monomers and volatile byproducts that did not participate in the reaction are effectively removed, thereby obtaining a functionalized bio-based plasticizer.

9. The method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles according to claim 6, characterized in that, In step S4, the cellulose diacetate powder treated in step S3 is mixed with the functionalized bio-based plasticizer obtained in step S2 at a mass ratio of 7:3, and mechanically stirred at room temperature for 30 minutes to make the functionalized bio-based plasticizer uniformly distributed on the surface of the cellulose diacetate particles. The mixture was then placed in a sealed environment for curing for 12 to 36 hours, allowing the plasticizer to gradually diffuse into the cellulose diacetate particles and form a stable and compatible system. After curing, a stabilizer was added and the mixture was stirred again to obtain a rubber powder mixture.

10. The method for preparing functionalized bio-based plasticizer-modified cellulose diacetate particles according to claim 6, characterized in that, In step S5, the rubber powder mixture obtained in step S4 is added to the hopper of a twin-screw extruder for melt blending. The twin-screw shearing action allows cellulose diacetate and functionalized bio-based plasticizer to be uniformly dispersed and form a stable composite system. During processing, the temperatures of each zone of the extruder are controlled sequentially from the feeding section to the die section as follows: 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, and 230℃. Under this temperature gradient, the material gradually plasticizes and completes melt mixing. Strips are extruded from the die, and after cooling and pelletizing, uniform and stable functionalized bio-based plasticizer-modified cellulose diacetate granules are obtained.

Images