Modified PVC particles and preparation method thereof

Abstract

The invention discloses a modified PVC (polyvinyl chloride) particle and a preparation method thereof in the field of high polymer material modification, the modified PVC particle takes PVC resin as a matrix, and two brand new modifiers, namely a silicon-boron-nitrogen hybrid epoxy nanosphere and epoxidized soybean oil-maleic anhydride-2-ethylhexyl acrylate random copolymer, and other auxiliaries are added. The silicon-boron-nitrogen hybrid epoxy nanospheres are prepared by the following steps: hydrolyzing tetraethoxysilane and triethyl borate in absolute ethyl alcohol to generate a silicon-boron alcohol intermediate, then carrying out sol-gel reaction on the silicon-boron alcohol intermediate and glycidyl methacrylate to form a hybrid network containing an epoxy group, and finally carrying out ultrasonic dispersion. The epoxidized soybean oil-maleic anhydride-2-ethylhexyl acrylate random copolymer is prepared by carrying out ring opening on epoxidized soybean oil and peracetic acid to generate epoxidized soybean oil acrylate, and then carrying out free radical copolymerization reaction on the epoxidized soybean oil acrylate, maleic anhydride and 2-ethylhexyl acrylate. The method is suitable for the fields of high-end building materials, automotive interiors and the like.

Description

Technical Field

[0001] This invention relates to the field of polymer material modification technology, specifically to a modified PVC particle and its preparation method. Background Technology

[0002] Polyvinyl chloride (PVC), as one of the most widely used general-purpose plastics globally, holds an important position in building profiles, automotive parts, and electronic appliance housings due to its low cost and excellent processing performance. However, its inherent performance defects have consistently limited its application in high-end scenarios: PVC is significantly brittle, with typically low notched impact strength, making it difficult to meet requirements for drop and collision resistance; its glass transition temperature is insufficient, resulting in a low long-term operating temperature and easy softening and deformation under high-temperature environments; simultaneously, its molecular chains are sensitive to ultraviolet light, easily undergoing photo-oxidative degradation under light conditions, leading to yellowing, embrittlement, and a significantly shortened outdoor lifespan. These performance shortcomings limit the application of PVC in high-end building materials, automotive interiors, and other fields with high comprehensive performance requirements.

[0003] Despite multi-dimensional explorations of traditional modification methods to address the performance deficiencies of PVC, significant shortcomings remain. Early methods commonly used plasticizers (such as phthalates) to improve toughness, but these significantly reduced the material's heat resistance. Inorganic fillers (such as calcium carbonate and talc) could enhance rigidity, but required large quantities and exhibited poor dispersibility, easily leading to increased processing viscosity and rough product surfaces. Single-function modifiers (such as epoxidized soybean oil) could only improve weather resistance or compatibility, failing to achieve synergistic improvements in multiple properties. In recent years, methods such as organic-inorganic hybrid modification and bio-based polymer modification have been attempted, but existing hybrid materials generally suffer from uneven inorganic phase dispersion and poor compatibility with PVC. Preparation processes often require high temperature and pressure or solvent assistance, making the processes complex. Bio-based modifiers, due to low reactivity (insufficient grafting rate with PVC) and limited improvement in heat resistance, are insufficient to meet industrial requirements.

[0004] With the increasing demands for comprehensive material performance in high-end manufacturing, there is an urgent need to develop novel modification solutions that can enhance the toughness, heat resistance, and weather resistance of PVC while also being process-friendly. The limitations of traditional modification technologies have prompted those skilled in the art to seek breakthroughs: by designing novel modifier structures to address the issues of single-function and poor compatibility of traditional materials; by optimizing preparation processes to reduce energy consumption and complexity; and by simultaneously considering environmental protection and sustainability to promote the expansion of PVC into high-end applications. This invention, based on this need, proposes a synergistic modification strategy using two novel modifying compounds, providing a new technical path for upgrading the performance of PVC. Summary of the Invention

[0005] The purpose of this invention is to provide a modified PVC granule and its preparation method, which solves the technical problems of existing PVC such as high brittleness, poor heat resistance, insufficient weather resistance, and traditional modification with single function, poor compatibility, and complex process.

[0006] The present invention achieves the above objectives through the following technical solutions: A modified PVC granule, comprising the following raw materials in parts by weight: PVC resin: 900-1100 parts by weight; Silicon-boron-nitrogen hybrid epoxy nanospheres: 30-80 parts by weight; Epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer: 50-120 parts by weight; Heat stabilizer: 20-40 parts by weight; Lubricant: 5-15 parts by weight; Antioxidant: 2-5 parts by weight; The preparation method of the silicon-boron-nitrogen hybrid epoxy nanospheres includes: A1, adding tetraethyl orthosilicate and triethyl borate to anhydrous ethanol, adding hydrochloric acid, and stirring and hydrolyzing at 60-62℃ to generate a siliborol intermediate; then adding glycidyl methacrylate and ammonia, heating to 80-82℃ and refluxing, and then the reaction product forming an epoxy-containing silicon-boron-nitrogen hybrid network by sol-gel method; A2, adding hexadecyltrimethylammonium bromide and ultrasonically dispersing.

[0007] In this invention, the preparation process of silicon-boron-nitrogen hybrid epoxy nanospheres involves multiple chemical reactions and structural regulation. First, tetraethyl orthosilicate and triethyl borate undergo hydrolysis in anhydrous ethanol under hydrochloric acid catalysis: the ethoxy group (-OCH2CH3) of tetraethyl orthosilicate reacts with water to generate silanol (-Si-OH), while the ethoxy group of triethyl borate generates boronol (-B-OH). This process involves acid-catalyzed cleavage of alkoxy bonds, releasing ethanol and forming a hydroxyl-containing intermediate. Subsequently, glycidyl methacrylate (containing epoxy groups) and ammonia are added to the system. The epoxy groups are activated in the weakly alkaline environment of ammonia, undergoing condensation reactions with the hydroxyl groups of silanol and boronol to form covalent bonds of silicon-oxygen-carbon and boron-oxygen-carbon. Simultaneously, ammonia acts as a catalyst to promote the deprotonation of hydroxyl groups, accelerating the reaction process. When refluxed at 80-82℃, these covalent bonds further crosslink, forming a three-dimensional network structure via the sol-gel method. Silicon, boron, and nitrogen elements (from tetraethyl orthosilicate, triethyl borate, and possibly a small amount of nitrogen source) are uniformly distributed within the network framework, while epoxy groups are fixed to the network surface by chemical bonds. Finally, hexadecyltrimethylammonium bromide is added and ultrasonically dispersed. The surfactant adsorbs onto the nanosphere surface, reducing interfacial tension. The cavitation effect of ultrasound disrupts the aggregation of the nanospheres, resulting in a uniformly dispersed, stable colloid with controllable particle size, laying the foundation for subsequent interfacial bonding with PVC.

[0008] According to a preferred embodiment of the present invention, the PVC resin is purchased from Xinjiang Tianye (Group) Co., Ltd., and is of type SG-5.

[0009] According to a preferred embodiment of the present invention, the tetraethyl orthosilicate was purchased from Hubei Xingfa Chemical Group Co., Ltd., and was of industrial grade (purity ≥99%).

[0010] According to a preferred embodiment of the present invention, the triethyl borate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and was of analytical grade (purity ≥99.5%).

[0011] According to a preferred embodiment of the present invention, the anhydrous ethanol was purchased from Anhui Anada Group Copper Crown Copper Foil Co., Ltd., and the product was industrial grade (purity ≥99.7%).

[0012] According to a preferred embodiment of the present invention, the hydrochloric acid was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., and was of 36% industrial grade (mass fraction).

[0013] According to a preferred embodiment of the present invention, the glycidyl methacrylate was purchased from Wanhua Chemical Group Co., Ltd., and is of industrial grade (purity ≥98%).

[0014] According to a preferred embodiment of the present invention, the ammonia water is purchased from Shandong Hualu Hengsheng Chemical Co., Ltd., and is of 25-28% industrial grade (mass fraction).

[0015] According to a preferred embodiment of the present invention, the cetyltrimethylammonium bromide was purchased from Jiangsu Haian Petrochemical Plant and is of industrial grade (purity ≥98%).

[0016] According to a preferred embodiment of the present invention, the heat stabilizer is purchased from Guangdong Yinxing Technology Co., Ltd., and is a calcium-zinc composite type (compound ratio calcium:zinc = 3:1).

[0017] According to a preferred embodiment of the present invention, the lubricant is purchased from Shanghai Jinzhao Plastics Co., Ltd., and is a PE wax (melting point 105-115℃).

[0018] According to a preferred embodiment of the present invention, the antioxidant is purchased from Kingfa Science & Technology Co., Ltd., and is model 1010 / 168 compound type (mass ratio 1:2).

[0019] According to a preferred embodiment of the present invention, in step A1, the molar ratio of tetraethyl orthosilicate to triethyl borate is 1:(0.2-0.3); the stirring hydrolysis time is 2-4 h; and the reflux reaction time is 6-8 h.

[0020] According to a preferred embodiment of the present invention, in step A2, the frequency of ultrasonic dispersion is 40-60 kHz and the time is 30-40 min.

[0021] According to a preferred embodiment of the present invention, the preparation method of the epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer includes: B1, reacting epoxidized soybean oil with peracetic acid at 60-62°C to generate epoxidized soybean oil acrylate through ring opening; B2, adding epoxidized soybean oil acrylate, maleic anhydride, and isooctyl acrylate to toluene, adding azobisisobutyronitrile, and purging with nitrogen for protection, and performing a free radical copolymerization reaction at 75-76°C; after the reaction is completed, removing toluene by vacuum distillation.

[0022] In this invention, the preparation of the random copolymer of epoxidized soybean oil, maleic anhydride, and isooctyl acrylate involves two steps: ring-opening and copolymerization. The epoxy group (three-membered ring ether structure) in the epoxidized soybean oil molecule undergoes a ring-opening reaction under the action of peracetic acid: the peroxy bond (-OO-) of peracetic acid acts as an oxidant, attacking one carbon atom of the epoxy group, causing the ring to break and generating epoxidized soybean oil acrylate. During this process, the two carbon atoms of the epoxy group combine with the carbonyl carbon of peracetic acid, forming a new structure containing an ester group (-COO-) and a double bond (-C=C-), providing active sites for subsequent polymerization. Subsequently, the epoxidized soybean oil acrylate undergoes free radical copolymerization with maleic anhydride and isooctyl acrylate under the action of azobisisobutyronitrile (a free radical initiator): the azobisisobutyronitrile decomposes to generate free radicals (such as R·), which attack the double bonds of the monomers (such as the C=C of the acrylate or the C=C of the maleic anhydride), initiating a chain growth reaction. The random arrangement of the three monomers (epoxidized soybean oil acrylate, maleic anhydride, and isooctyl acrylate) stems from the low selectivity of the free radical reaction. Free radicals can attack the double bonds of any monomer, resulting in a random distribution of monomer units on the macromolecular chain. After the reaction, unreacted toluene solvent was removed by vacuum distillation, yielding a random copolymer with a narrow molecular weight distribution. The carboxyl group (-COOH) of maleic anhydride and the long alkyl chain of isooctyl acrylate provide functional groups for subsequent compatibility enhancement with PVC.

[0023] According to a preferred embodiment of the present invention, the epoxidized soybean oil was purchased from Wuhan Organic Industry Co., Ltd., and is of industrial grade (epoxidation value ≥ 6.0%).

[0024] According to a preferred embodiment of the present invention, the peracetic acid was purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd., and was of industrial grade (concentration ≥18%).

[0025] According to a preferred embodiment of the present invention, the maleic anhydride was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and was of analytical grade (purity ≥ 99%).

[0026] According to a preferred embodiment of the present invention, the isooctyl acrylate was purchased from Wanhua Chemical Group Co., Ltd., and is of industrial grade (purity ≥99%).

[0027] According to a preferred embodiment of the present invention, the toluene was purchased from Sinopec Yangzi Petrochemical Co., Ltd., and was of industrial grade (purity ≥99.5%).

[0028] According to a preferred embodiment of the present invention, the azobisisobutyronitrile was purchased from Nanjing Reagent Co., Ltd., and was of analytical grade (purity ≥ 99%).

[0029] According to a preferred embodiment of the present invention, the nitrogen gas is purchased from Air Liquide (China) Investment Co., Ltd. Shanghai Branch, and is of industrial grade (purity ≥99.99%).

[0030] According to a preferred embodiment of the present invention, the high-speed mixer was purchased from Zhangjiagang Lanhang Machinery Co., Ltd., and the model is LHM-500 (500L volume).

[0031] According to a preferred embodiment of the present invention, the twin-screw extruder was purchased from Nanjing Coperon Keya Machinery Co., Ltd., and is model CET-40 (length-to-diameter ratio 40:1).

[0032] According to a preferred embodiment of the present invention, in step B1, the molar ratio of epoxidized soybean oil to peracetic acid is 1:(0.1-0.2); the reaction time is 4-6 h at 60-62°C.

[0033] According to a preferred embodiment of the present invention, in step B2, the free radical copolymerization reaction takes 10-12 hours.

[0034] The present invention also provides a method for preparing the modified PVC granules described above, characterized in that the steps include: S1. Add PVC resin, silicon boron nitrogen hybrid epoxy nanospheres, epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer, heat stabilizer, lubricant, and antioxidant to a high-speed mixer, mix at low speed first, then mix at high speed until uniform. S2. Add the mixture to the twin-screw extruder and set the temperature of each zone as follows: feeding zone 155℃, compression zone 165-175℃, metering zone 180-185℃. S3. The extrudate is subjected to water-cooled traction, pelleting and drying.

[0035] According to a preferred embodiment of the present invention, in step S1, the rotation speed of low-speed mixing is 200-400 rpm and the time is 1-2 min; the rotation speed of high-speed mixing is 1000-1200 rpm and the mixing time is 5-10 min.

[0036] In this invention, the high-speed mixing process is a key step in the initial bonding of the modifier and PVC resin. When the raw materials are added to the high-speed mixer, the mechanical shear force (generated by the rotation of the stirring paddle) causes the material particles to break up and move violently, creating a localized high temperature (approximately 80-100°C) and high shear environment. Under shearing, the epoxy groups (from the network structure prepared by the sol-gel method) on the surface of the silicon-boron-nitrogen hybrid epoxy nanospheres, along with the carboxyl groups (-COOH) and double bonds (-C=C-) of the random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate, undergo physical adsorption or weak chemical interaction with the chlorine atoms (-Cl) on the surface of the PVC resin: the oxygen atom of the epoxy group can form hydrogen bonds (-O…Cl-) with the chlorine atoms of the PVC; the hydroxyl groups (-OH) of the carboxyl groups can bind with the methylene groups (-CH2-) of the PVC through van der Waals forces; and the double bonds may undergo π-π stacking with the unsaturated structure of the PVC (a small amount of residual double bonds). These interfacial interactions weaken the van der Waals forces between PVC resin particles, promoting their dispersion. Simultaneously, the long alkyl chains of the modifier insert into the PVC molecular chains, reducing the packing density and improving the system's flowability. Furthermore, heat stabilizers (such as calcium zinc soap) migrate to the PVC surface during mixing, combining with residual chlorine atoms to inhibit the initial deHCl reaction; lubricants (such as PETS) adsorb onto the particle surface, reducing frictional resistance during mixing and ensuring uniform distribution of all components. The mixing effect at this stage directly affects the compatibility of the modifier with PVC during subsequent extrusion, making it a crucial pretreatment step that determines the final material properties.

[0037] According to a preferred embodiment of the present invention, in step S2, the screw speed is 250-300 rpm and the residence time is 3-5 min.

[0038] According to a preferred embodiment of the present invention, in step S3, the water temperature for water-cooled traction is 24-26°C; the diameter of the pellets is 2.5 mm; the drying temperature is 60-62°C, and the drying time is 2-4 h.

[0039] In this invention, the twin-screw extrusion process achieves deep integration of the modifier and PVC through melt blending. After entering the extruder, the material is first conveyed in the feeding section (155°C) and compacted by the rotation of the screw. The temperature gradually rises to the compression section (165-175°C), where the PVC resin begins to melt. The modifier (silicon boron nitrogen hybrid epoxy nanospheres and random copolymer) melts first due to its lower melting point (or glass transition temperature), forming a continuous phase that encapsulates the PVC particles. Upon entering the metering section (180-185°C), the material is completely melted. Under the shearing, compression, and mixing action of the screw, it undergoes both distribution mixing (homogenization of component spatial positions) and dispersion mixing (refinement and uniform distribution of modifier particles). In this process, the three-dimensional network structure of the silicon-boron-nitrogen hybrid epoxy nanospheres forms physical entanglement with the PVC molecular chains through chemical bonding of epoxy groups (-Si-O-CH2-CH(Cl)-), enhancing the interfacial bonding force. The carboxyl groups (-COOH) of the random copolymer react with the chlorine atoms (-Cl) of PVC (-COOH +-Cl→ -COO-Cl + H2O), or form chemical interactions through hydrogen bonds (-COOH…Cl-), further anchoring the PVC molecular chains to the long alkyl chain network of the copolymer. This multi-action (chemical bonding, physical entanglement, hydrogen bonding) restricts the mobility of the PVC molecular chains, while the introduction of flexible segments (such as the long alkyl groups of isooctyl acrylate) alleviates internal stress concentration, ultimately forming a composite structure of "PVC matrix + modifier network". The material is rapidly cooled by water cooling (24-26℃), the melt solidifies into strips, and after pelleting and drying (60-62℃), modified PVC granules with smooth surface and uniform internal structure are obtained. Their mechanical properties, heat resistance and weather resistance are significantly improved compared with pure PVC.

[0040] The beneficial effects of this invention are as follows: Polyvinyl chloride (PVC) has long been limited in high-end applications due to its inherent defects such as high brittleness, insufficient heat resistance, and poor weather resistance. This invention significantly improves the overall performance of PVC through the synergistic effect of two novel modifiers. Specifically, the silicon-boron-nitrogen hybrid epoxy nanospheres, with their three-dimensional network structure and chemical bonding ability with epoxy groups, effectively enhance the interaction between PVC molecular chains, enabling the material to more efficiently disperse stress under external impact and significantly improve impact resistance. The epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer, through its polar carboxyl groups and long-chain alkyl structures, not only improves compatibility with PVC but also alleviates internal stress concentration in the molecular chains through flexible segments, further enhancing the material's toughness. The combined effect of these two modifiers results in a more significant improvement in the notched impact strength of PVC compared to traditional modification systems, meeting practical application requirements such as drop resistance and impact resistance.

[0041] Insufficient heat resistance is a major obstacle to the application of PVC in high-temperature environments. This invention effectively overcomes this limitation through the structural design of the modifier. The silicon-boron-nitrogen hybrid network in the silicon-boron-nitrogen hybrid epoxy nanospheres has high bond energy characteristics, and its stable chemical structure can inhibit the thermal decomposition of PVC molecular chains at high temperatures. The epoxy groups and maleic anhydride groups in the epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer delay the softening process of the material at high temperatures through chemical bonding with PVC. The synergistic effect of the two modifiers significantly increases the heat distortion temperature of PVC, enabling it to maintain shape stability at higher temperatures and expanding its application possibilities in high-temperature scenarios (such as automotive interiors and industrial components).

[0042] Weather resistance is a key indicator for measuring the outdoor service life of materials. This invention significantly improves the weather resistance of PVC through the optimization of modifier composition. The epoxy groups on the surface of the silicon boron nitrogen hybrid epoxy nanospheres can form chemical bonds with the PVC molecular chains, reducing molecular chain breakage caused by ultraviolet radiation. The bio-based epoxidized soybean oil component in the epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer delays the yellowing and embrittlement process by reducing the material's sensitivity to photo-oxidative aging. In addition, the synergistic effect of the two modifiers enhances the material's resistance to environmental factors such as oxidation and humid heat, enabling PVC to maintain good mechanical properties and appearance integrity even after long-term outdoor use. Meanwhile, the modified PVC preparation method, through optimized processes of high-speed mixing and twin-screw extrusion, ensures uniform dispersion of each component, further improving the material's processing fluidity and finished product consistency, providing a reliable guarantee for industrial production. Detailed Implementation

[0043] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0044] I. Example: Example 1: Preparation of silicon-boron-nitrogen hybrid epoxy nanospheres: 120g of tetraethyl orthosilicate and 36g of triethyl borate were added to 500g of anhydrous ethanol. The mixture was stirred at 300rpm using a magnetic stirrer while 10g of 36% hydrochloric acid (mass fraction) was slowly added. The mixture was kept at a constant temperature of 60°C in a water bath and stirred continuously for 3 hours. During this time, the solution was observed to gradually change from clear to light blue turbidity, forming a siliboronic alcohol intermediate. Subsequently, the reaction system was transferred to a round-bottom flask equipped with a reflux condenser, and 40g of methyl... Glycidyl acrylate and 15g of 25% ammonia solution (mass fraction) were mixed, and the condenser was circulated while the temperature was gradually increased to 80°C. The mixture was kept under reflux for 7 hours. During the reaction, the solution gradually became a translucent viscous state, forming a silicon boron nitrogen hybrid network containing epoxy groups. The mixture was cooled to room temperature, and 5g of cetyltrimethylammonium bromide was added as a dispersant. The mixture was then transferred to an ultrasonic cleaner and ultrasonically dispersed at a frequency of 40kHz for 35 minutes to obtain a uniform silicon boron nitrogen hybrid epoxy nanosphere dispersion. The supernatant was collected after centrifugation for later use.

[0045] Preparation of random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate: 100g of epoxidized soybean oil and 15g of 18% peracetic acid (mass fraction) were added to a three-necked flask equipped with a stirrer. The mixture was stirred at 200rpm in a water bath at 60℃ for 5 hours, with samples taken every 30 minutes. The reaction was stopped when the epoxy groups of the epoxidized soybean oil were completely opened (detected by the disappearance of the epoxy absorption peak by infrared spectroscopy), producing epoxidized soybean oil acrylate. The reacted liquid was transferred to a four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet, and 150g of epoxidized soybean oil acrylate was added. The system was prepared by mixing ester, 30g maleic anhydride, 40g isooctyl acrylate, and 0.5g azobisisobutyronitrile (AIBN). High-purity nitrogen gas (flow rate 200mL / min) was introduced to purge the oxygen from the system. The mixture was stirred at 300rpm in an oil bath at 75℃, while the remaining monomer was slowly added dropwise using a syringe pump (ensuring monomer conversion >95%). The free radical copolymerization reaction was continued for 11 hours. After the reaction was completed, the system was cooled to room temperature and the unreacted toluene solvent was removed by vacuum distillation (vacuum degree -0.09MPa, temperature 60℃) to obtain a viscous random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate.

[0046] Preparation of modified PVC particles: 1000g SG-5 type PVC resin, 50g of the above-prepared silicon boron nitrogen hybrid epoxy nanosphere dispersion (solid content calculated as 30%, actual solid mass 15g), 80g epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer, 30g calcium-zinc composite heat stabilizer (calcium:zinc = 3:1), 10g PE wax lubricant, 3g... The 1010 / 168 compound antioxidant (mass ratio 1:2) was added to a high-speed mixer and mixed at a low speed of 300 rpm for 1.5 minutes to initially disperse the components. Then, it was mixed at a high speed of 1100 rpm for 7.5 minutes. During this period, the material was observed to gradually change from a loose state to a uniform clump, indicating that the mixing was complete. The mixture was then transferred to a twin-screw extruder. The feeding section temperature was set to 155℃ (to ensure that the PVC resin initially melts), the compression section temperature to 170℃ (to promote the entanglement of the modifier and PVC molecular chains), and the metering section temperature to 182℃ (to ensure that the material is fully melted and mixed). The screw speed was set to 280 rpm, and the material was allowed to remain in the extruder for 4 minutes. The extrudate was then water-cooled and tractioned (water temperature 25℃, traction speed matched with extrusion speed) to form strips. These strips were then cut into 2.5 mm diameter granules by a pelletizer (blade speed 1500 rpm). Finally, the granules were transferred to a vacuum drying oven at 60℃ and dried for 3 hours to remove surface moisture, resulting in modified PVC granules.

[0047] Example 2: The specific implementation method is the same as that of Example 1, except that the silicon boron nitrogen hybrid epoxy nanospheres are prepared as follows: 100g of tetraethyl orthosilicate and 25g of triethyl borate are added to 400g of anhydrous ethanol and 8g of 36% hydrochloric acid. The mixture is stirred and hydrolyzed at 61°C for 2.5h to generate a siliboronic alcohol intermediate. Subsequently, 30g of glycidyl methacrylate and 12g of 25% ammonia are added, and the mixture is heated to 81°C and refluxed for 6.5h. The reaction product forms an epoxy-containing silicon boron nitrogen hybrid network through the sol-gel method. 4g of hexadecyltrimethylammonium bromide is added and ultrasonically dispersed (frequency 50kHz) for 32min to obtain silicon boron nitrogen hybrid epoxy nanospheres. Preparation of random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate: 90g of epoxidized soybean oil and 13g of peracetic acid were reacted at 61℃ for 4.5h to generate epoxidized soybean oil acrylate through ring opening; 135g of epoxidized soybean oil acrylate, 25g of maleic anhydride, and 35g of isooctyl acrylate were added to 90g of toluene and 0.4g of azobisisobutyronitrile (AIBN), and the mixture was subjected to nitrogen protection and subjected to free radical copolymerization at 76℃ for 10.5h; after the reaction was completed, toluene was removed by vacuum distillation to obtain the random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate. Preparation of modified PVC granules: 950g of PVC resin, 45g of silicon boron nitrogen hybrid epoxy nanospheres, 75g of epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer, 28g of heat stabilizer, 9g of lubricant, and 2.5g of antioxidant were added to a high-speed mixer. The mixture was first mixed at low speed (250rpm) for 1.2min, and then at high speed (1050rpm) for 6.5min until homogeneous. The mixture was then added to a twin-screw extruder, and the temperatures of each zone were set as follows: feeding section 155℃, compression section 168℃, metering section 180℃, screw speed 260rpm, and residence time 3.5min. The extrudate was then subjected to water-cooled traction (water temperature 25℃), pelletized (diameter 2.5mm), and dried (61℃ for 2.5h) to obtain modified PVC granules.

[0048] Example 3: The specific implementation method is the same as that of Example 1, except that the silicon boron nitrogen hybrid epoxy nanospheres are prepared as follows: 140g of tetraethyl orthosilicate and 42g of triethyl borate are added to 600g of anhydrous ethanol and 12g of 36% hydrochloric acid. The mixture is stirred and hydrolyzed at 62°C for 4h to generate a siliboronic alcohol intermediate. Subsequently, 50g of glycidyl methacrylate and 18g of 25% ammonia are added, and the mixture is heated to 82°C and refluxed for 8h. The reaction product forms an epoxy-containing silicon boron nitrogen hybrid network by the sol-gel method. 6g of hexadecyltrimethylammonium bromide is added and ultrasonically dispersed (frequency 60kHz) for 40min to obtain silicon boron nitrogen hybrid epoxy nanospheres. Preparation of random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate: 110g of epoxidized soybean oil and 17g of peracetic acid were reacted at 62℃ for 6h to generate epoxidized soybean oil acrylate; 165g of epoxidized soybean oil acrylate, 35g of maleic anhydride, and 45g of isooctyl acrylate were added to 110g of toluene and 0.6g of azobisisobutyronitrile (AIBN), and the mixture was subjected to nitrogen protection and subjected to free radical copolymerization at 75.5℃ for 11.5h; after the reaction was completed, toluene was removed by vacuum distillation to obtain the random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate. Preparation of modified PVC granules: 1050g of PVC resin, 60g of silicon boron nitrogen hybrid epoxy nanospheres, 90g of epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer, 32g of heat stabilizer, 12g of lubricant, and 3.5g of antioxidant were added to a high-speed mixer. The mixture was first mixed at low speed (350rpm) for 1.8min, and then at high speed (1150rpm) for 8min until homogeneous. The mixture was then added to a twin-screw extruder, and the temperatures of each zone were set as follows: feeding section 155℃, compression section 172℃, metering section 184℃, screw speed 300rpm, and residence time 4.5min. The extrudate was then subjected to water-cooled traction (water temperature 25℃), pelletized (diameter 2.5mm), and dried (62℃ for 3.5h) to obtain modified PVC granules.

[0049] Comparative Example 1: The specific implementation method is the same as Example 1, except that the preparation of modified PVC particles (without silicon boron nitrogen hybrid epoxy nanospheres): The preparation of the epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer is the same as in Example 1. Preparation of modified PVC particles: 1000g of PVC resin, 80g of epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer, 30g of heat stabilizer, 10g of lubricant, and 3g of antioxidant are added to a high-speed mixer. The mixture is first mixed at low speed (300rpm) for 1.5min, and then at high speed (1100rpm) for 7.5min until uniform. The mixture is added to a twin-screw extruder, and the temperatures of each zone are set as follows: feeding section 155℃, compression section 170℃, metering section 182℃, screw speed 280rpm, residence time 4min. The extrudate is then subjected to water-cooled traction (water temperature 25℃), pelletized (diameter 2.5mm), and dried (60℃ for 3h) to obtain modified PVC particles.

[0050] Comparative Example 2: The specific implementation method is the same as Example 1, except that the preparation of modified PVC particles (without epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer): the preparation of silicon boron nitrogen hybrid epoxy nanospheres is the same as in Example 1. Preparation of modified PVC particles: 1000g of PVC resin, 50g of silicon boron nitrogen hybrid epoxy nanospheres, 30g of heat stabilizer, 10g of lubricant, and 3g of antioxidant are added to a high-speed mixer. The mixture is first mixed at low speed (300rpm) for 1.5min, and then at high speed (1100rpm) for 7.5min until uniform. The mixture is added to a twin-screw extruder, and the temperatures of each zone are set as follows: feeding section 155℃, compression section 170℃, metering section 182℃, screw speed 280rpm, residence time 4min. The extrudate is then subjected to water-cooled traction (water temperature 25℃), pelletized (diameter 2.5mm), and dried (60℃ for 3h) to obtain modified PVC particles.

[0051] Comparative Example 3: The specific implementation method is the same as Example 1, except that the modified PVC granules are prepared without the two modifiers: Preparation of modified PVC granules: 1000g of PVC resin, 30g of heat stabilizer, 10g of lubricant, and 3g of antioxidant are added to a high-speed mixer. The mixture is first mixed at low speed (300rpm) for 1.5min, and then at high speed (1100rpm) for 7.5min until uniform. The mixture is added to a twin-screw extruder, and the temperatures of each zone are set as follows: feeding section 155℃, compression section 170℃, metering section 182℃, screw speed 280rpm, residence time 4min. The extrudate is then subjected to water-cooled traction (water temperature 25℃), pelletized (diameter 2.5mm), and dried (60℃ for 3h) to obtain modified PVC granules.

[0052] II. Performance Testing The modified PVC particles prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following methods: 1. Notched Impact Strength: Tested according to GB / T 1043.1-2008 "Determination of Impact Properties of Simply Supported Beams of Plastics - Part 1: Non-Instrumental Impact Testing". Modified PVC granules were pretreated at 23℃ and 50%RH for 48 hours, then injection molded into standard notched specimens (thickness 4mm, notch depth 1mm, notch base radius 0.25mm). The specimens were tested using a pendulum impact testing machine (impact energy 50J) at 23℃. Five specimens were taken from each group, and the average value was recorded.

[0053] 2. Tensile strength and elongation at break: Tested according to GB / T 1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics". The specimen size is 150mm × 10mm × 4mm, the tensile rate is 50mm / min, and a universal testing machine is used. Five specimens are taken for each group, and the average value is taken.

[0054] 3. Heat distortion temperature (HDT): Tested according to GB / T 1634.2-2019 "Determination of load distortion temperature of plastics - Part 2: Plastics and hard rubber". The sample size is 80mm×10mm×4mm. A bending stress of 1.82MPa is applied, the heating rate is 2℃ / min, and the temperature when the sample bends by 0.2mm is recorded.

[0055] 4. UV Aging Performance: Tested according to GB / T 14522-2008 "Artificial Climate Aging Test Method for Plastics, Coatings and Rubber Materials for Mechanical Industry Products - Fluorescent Ultraviolet Lamp". The sample was placed in an ultraviolet aging chamber (wavelength 340nm, irradiance 0.89W / (m²·nm), black panel temperature 60℃, condensation cycle 4h / 4h). After aging for 500h, the color change (ΔE, using a colorimeter) and tensile strength retention rate (tensile strength after aging / tensile strength before aging × 100%) were tested.

[0056] 5. Performance test results: Table 1: Performance test results of each embodiment and comparative example

[0057] As shown in Table 1, this invention effectively solves the technical problems of existing PVC materials, such as high brittleness, poor heat resistance, insufficient weather resistance, and the limitations of traditional modification methods, including single function, poor compatibility, and complex processes, through the synergistic effect of two novel modifiers and an optimized preparation process. Specifically, the notched impact strength of Examples 1-3 is 8.2-8.8 kJ / m². 2 The efficiency was significantly higher than that of Comparative Example 1 (silicon-boron-nitrogen hybrid epoxy nanospheres, 4.2 kJ / m³). 2 Comparative Example 2 (random copolymer of non-epoxidized soybean oil-maleic anhydride-isooctyl acrylate, 5.1 kJ / m³) 2 Comparative Example 3 (without modifier, 4.5 kJ / m) and Comparative Example 4 (without modifier, 4.5 kJ / m) 2The results indicate that the combination of the two modifiers significantly improved the toughness of the material. The tensile strength (73-78 MPa) and elongation at break (115-125%) were both superior to those of the comparative examples, indicating that the modifiers improved the interaction between molecular chains and enhanced impact resistance and tensile properties. Regarding heat resistance, the heat distortion temperature (103-107℃) of the examples was much higher than that of Comparative Example 1 (78℃), Comparative Example 2 (82℃), and Comparative Example 3 (75℃), verifying the synergistic heat resistance effect of the high bond energy structure of the silicon boron nitrogen hybrid epoxy nanospheres and the epoxy copolymer. In terms of weather resistance, after 500 hours of UV aging, the ΔE (1.1-1.3) of the examples was significantly lower than that of Comparative Example 1 (3.8) and Comparative Example 2 (3.2), and the tensile strength retention rate (86-90%) was higher than that of Comparative Example 1 (65%) and Comparative Example 2 (72%), indicating that the bio-based structure and polar groups of the epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer effectively inhibited photo-oxidative aging degradation. In traditional modification methods, plasticizers improve toughness but reduce heat resistance, inorganic fillers have poor dispersion and require high filler content, and single modifiers only improve a single property. This invention solves the problems of single function, poor compatibility and complex process by using a dual-modifier synergy (silicon-boron-nitrogen hybrid epoxy nanospheres to improve toughness / heat resistance, and epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer to improve compatibility / weather resistance) and a twin-screw blending process (simplifying the process and reducing energy consumption), thus achieving a multi-performance synergistic improvement of PVC materials.

[0058] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A modified PVC granule, characterized in that, Including the following parts by weight of raw materials: PVC resin: 900-1100 parts by weight; Silicon-boron-nitrogen hybrid epoxy nanospheres: 30-80 parts by weight; Epoxidized soybean oil-maleic anhydride-isooctyl acrylate random copolymer: 50-120 parts by weight; Heat stabilizer: 20-40 parts by weight; Lubricant: 5-15 parts by weight; Antioxidant: 2-5 parts by weight; The preparation method of the silicon-boron-nitrogen hybrid epoxy nanospheres includes: A1, adding tetraethyl orthosilicate and triethyl borate to anhydrous ethanol, adding hydrochloric acid, and stirring and hydrolyzing at 60-62℃ to generate a siliborol intermediate; then adding glycidyl methacrylate and ammonia, heating to 80-82℃ and refluxing, and then the reaction product forming an epoxy-containing silicon-boron-nitrogen hybrid network by sol-gel method; A2, adding hexadecyltrimethylammonium bromide and ultrasonically dispersing.

2. The modified PVC granules according to claim 1, characterized in that, In step A1, the molar ratio of tetraethyl orthosilicate to triethyl borate is 1:(0.2-0.3); the stirring hydrolysis time is 2-4 hours; and the reflux reaction time is 6-8 hours.

3. The modified PVC granules according to claim 1, characterized in that, In step A2, the ultrasonic dispersion frequency is 40-60kHz and the time is 30-40min.

4. The modified PVC granules according to claim 1, characterized in that, The preparation method of the random copolymer of epoxidized soybean oil-maleic anhydride-isooctyl acrylate includes: B1, reacting epoxidized soybean oil with peracetic acid at 60-62℃ to generate epoxidized soybean oil acrylate through ring opening; B2, adding epoxidized soybean oil acrylate, maleic anhydride, and isooctyl acrylate to toluene, adding azobisisobutyronitrile, and purging with nitrogen for protection, and performing a free radical copolymerization reaction at 75-76℃; after the reaction is completed, removing toluene by vacuum distillation.

5. The modified PVC granules according to claim 4, characterized in that, In step B1, the molar ratio of epoxidized soybean oil to peracetic acid is 1:(0.1-0.2); the reaction time is 4-6 hours at 60-62℃.

6. The modified PVC granules according to claim 4, characterized in that, In step B2, the free radical copolymerization reaction takes 10-12 hours.

7. A method for preparing modified PVC granules according to any one of claims 1-6, characterized in that, step... include: S1. Add PVC resin, silicon boron nitrogen hybrid epoxy nanospheres, epoxy soybean oil-maleic anhydride-isooctyl acrylate random copolymer, heat stabilizer, lubricant, and antioxidant to a high-speed mixer, mix at low speed first, then mix at high speed until uniform. S2. Add the mixture to the twin-screw extruder and set the temperature of each zone as follows: feeding zone 155℃, compression zone 165-175℃, metering zone 180-185℃. S3. The extrudate is subjected to water-cooled traction, pelleting and drying.

8. The preparation method according to claim 7, characterized in that, In step S1, the speed of low-speed mixing is 200-400 rpm and the time is 1-2 min; the speed of high-speed mixing is 1000-1200 rpm and the mixing time is 5-10 min.

9. The preparation method according to claim 7, characterized in that, In step S2, the screw speed is 250-300 rpm and the residence time is 3-5 min.

10. The preparation method according to claim 7, characterized in that, In step S3, the water temperature for water-cooled traction is 24-26℃; the diameter of the pellets is 2.5mm; the drying temperature is 60-62℃, and the drying time is 2-4h.

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