Multifunctional auxiliary agent, synthesis method thereof and application of multifunctional auxiliary agent in PVC (polyvinyl chloride) processing

Abstract

The invention belongs to the technical field of high polymer material additives, and particularly relates to a multifunctional additive, a synthesis method thereof and application of the multifunctional additive in PVC (polyvinyl chloride) processing. Modified mannitol and binary acid are used as raw materials for esterification reaction to obtain a product A, the product A and yttrium salt are mixed for reaction to obtain a product B, and the product B and cinnamyl ethyl methacrylate are mixed for free radical reaction to obtain the multifunctional additive. The multifunctional auxiliary agent can be used as a heat stabilizer to improve the thermal decomposition temperature of PVC, can also be used as a light stabilizer to reduce the influence of illumination on PVC, and can be well applied to PVC processing.

Description

Technical Field

[0001] This invention belongs to the technical field of polymer material additives, specifically relating to a multifunctional additive, its synthesis method, and its application in PVC processing. Background Technology

[0002] Polyvinyl chloride (PVC) is a synthetic resin with excellent comprehensive properties. It is polymerized from vinyl chloride monomer under specific conditions according to the free radical polymerization mechanism. It possesses advantages such as flame retardancy, electrical insulation, good airtightness, and corrosion resistance. Furthermore, its performance can be diversified by different additive formulations to meet the various needs of different fields for PVC materials, including transparency, flexibility, and flame retardancy. A major advantage of PVC materials is that by adjusting the formulation of heat stabilizers and other additives, transparent and performance-adjustable materials can be obtained, making it widely used in food packaging, pharmaceutical packaging, medical supplies, and many other fields.

[0003] However, PVC materials have poor light and heat stability. When the matrix is ​​exposed to sunlight for a long time, a decomposition reaction occurs. Chlorine atoms on the macromolecular chain combine with adjacent hydrogen atoms to form hydrogen chloride and carbon-carbon double bonds. The released hydrogen chloride catalyzes the decomposition of PVC, leading to a vicious cycle. As chlorine atoms are continuously released and conjugated double bonds are continuously formed, the color of the PVC material gradually darkens, and its mechanical properties decline rapidly. In addition, during the production and processing, PVC usually needs to be heated to a high temperature. Therefore, in practical applications, appropriate amounts of light stabilizers and heat stabilizers need to be added.

[0004] Chinese patent (publication number CN118955483B) discloses a method for preparing a PVC processing aid. Based on shellac acid, the method involves esterification of benzyl alcohol to introduce a rigid benzene ring structure, reaction with ethyl levulinate to introduce ketal and ester structures, esterification with palm oil to introduce double bonds, and cyclization with m-chlorobenzeneperoxyformic acid to form an epoxy structure. The resulting PVC processing aid exhibits high plasticity, low volatility, and low migration. However, this PVC processing aid requires the addition of a heat stabilizer during processing and use, and research on the light stability of PVC is lacking.

[0005] Therefore, how to synthesize multifunctional additives for PVC through molecular design, which can both act as heat stabilizers to increase the thermal decomposition temperature of PVC and as light stabilizers to reduce the impact of light on PVC, has become a research direction. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present application aims to provide a multifunctional auxiliary agent, a synthesis method thereof and application thereof in PVC processing; the multifunctional auxiliary agent of the present application is first prepared by esterification reaction of modified mannitol and fumaric acid, under the action of a catalyst p-toluenesulfonic acid, two carboxyl groups of one fumaric acid molecule are esterified with two modified mannitol molecules to form a product A with a chain structure; then product A and yttrium acetate are mixed for warming reaction, the lone pair electrons of oxygen atoms move to yttrium atoms and cause the decrease of yttrium binding energy, thereby forming a product B with an alkoxy-yttrium bond; meanwhile, the carbon-carbon double bond in product B can undergo a free radical reaction with the methacrylate group of cinnamyl methacryloyloxyethyl methacrylate, to obtain a multifunctional auxiliary agent capable of improving the thermal stability and light stability of PCV.

[0007] The technical scheme adopted by the present application to solve the above technical problems is as follows: In a first aspect of the present application, a synthesis method of a multifunctional auxiliary agent is provided, comprising the following steps: Esterification reaction is performed on modified mannitol and a dibasic acid to obtain product A, product A and a yttrium salt are mixed for reaction to obtain product B, and product B and cinnamyl methacryloyloxyethyl methacrylate are mixed for free radical reaction to obtain a multifunctional auxiliary agent.

[0008] As a preferred technical scheme of the present application, the preparation step of product A is as follows: 36-54 parts of modified mannitol, 10-15 parts of a dibasic acid and 0.2-0.4 parts of a catalyst are mixed uniformly, then 6-10 parts of a water-carrying agent is added, and esterification reaction is performed under nitrogen atmosphere at 150-160 DEG C for 120-150 min, followed by washing with anhydrous ethanol, reduced pressure distillation and vacuum drying to obtain product A.

[0009] As a preferred technical scheme of the present application, the weight fraction of the modified mannitol can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts or 40 parts, etc.

[0010] As a preferred technical scheme of the present application, the weight fraction of the dibasic acid can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts, etc.

[0011] As a preferred technical scheme of the present application, the weight fraction of the catalyst can be 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts or 0.4 parts, etc.

[0012] As a preferred technical scheme of the present application, the weight fraction of the water-carrying agent can be 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc.

[0013] Mannitol is a hexahydrol. Of its six hydroxyl groups, only the two primary hydroxyl groups at the ends may participate in esterification, while the four secondary hydroxyl groups in the middle are shielded due to steric hindrance and low activity. However, after one primary hydroxyl group of mannitol is amination, the modified mannitol only has one primary hydroxyl group left to undergo esterification, thus enabling the successful formation of product A.

[0014] As a preferred technical solution of the present invention, the modified mannitol is prepared by adding 9.0-9.6 parts by weight of mannitol and 3.0-3.6 parts by weight of glycine to 30-40 parts by weight of chloroform, then adding 1-2 drops of sulfuric acid, reacting at 80-90°C for 6-8 hours, and then rotary evaporating to obtain modified mannitol.

[0015] Mannitol molecules contain 6 hydroxyl groups that are highly symmetrically distributed in their straight-chain structure. One primary hydroxyl group first reacts with glycine to introduce an amino group, and another primary hydroxyl group then undergoes esterification with fumaric acid. The oxygen atoms of the remaining secondary hydroxyl groups coordinate with the empty orbitals of yttrium ions, replacing the weakly bound acetate ions in yttrium acetate. The yttrium ions are surrounded and coordinated by the secondary hydroxyl groups on multiple product A molecules to form metal alkoxy groups (alkoxy-yttrium bonds), thereby obtaining the complex product B.

[0016] As a preferred embodiment of the present invention, the dicarboxylic acid is selected from succinic acid, adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, and trans-butenedioic acid; more preferably, the dicarboxylic acid is trans-butenedioic acid.

[0017] The molecular structure of trans-butenedioic acid is a linear four-carbon chain with a carboxyl group (-COOH) at each end and a carbon-carbon double bond (C=C) in the middle. The carboxyl groups at both ends can form ester bonds with alcohol hydroxyl groups, while the carbon-carbon double bond in the middle can be grafted through free radical reactions. At the same time, its trans structure makes the molecule have a highly symmetrical linear structure, which is beneficial to thermal stability.

[0018] As a preferred embodiment of the present invention, the catalyst is p-toluenesulfonic acid and the dehydrating agent is cyclohexane.

[0019] As a preferred technical solution of the present invention, the preparation steps of product B are as follows: by weight, 20-30 parts of yttrium salt are added to 280-300 parts of anhydrous ethanol and ultrasonically dispersed evenly, transferred to a reaction vessel, and then 30-40 parts of product A are added. The mixture is reacted at 130-140°C for 4-6 hours and dried to obtain product B.

[0020] As a preferred embodiment of the present invention, the weight parts of the yttrium salt may be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, or 30 parts, etc.

[0021] As a preferred embodiment of the present invention, the yttrium salt is yttrium acetate.

[0022] Yttrium can efficiently and rapidly capture HCl produced by PVC degradation, interrupting the autocatalytic chain reaction. In addition, yttrium undergoes coordination or ion exchange reactions with allyl chloride or tertiary chloride on the PVC chain, replacing them with more stable structures. The combined effect reduces the degradation initiation sites and improves thermal stability.

[0023] As a preferred technical solution of the present invention, the preparation steps of the cinnamoyl oxyethyl methacrylate are as follows: by weight, 10-15 parts of hydroxyethyl methacrylate are added to 180-200 parts of dichloromethane under an argon atmosphere and dissolved completely, then 1.8-2.2 parts of triethylamine and 16-20 parts of cinnamoyl chloride are added, and the mixture is stirred overnight at 0-4°C. The filtrate is filtered, purified by rotary evaporation, and dried to obtain liquid cinnamoyl oxyethyl methacrylate.

[0024] As a preferred embodiment of the present invention, the weight parts of the hydroxyethyl methacrylate may be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, or 15 parts, etc.

[0025] As a preferred embodiment of the present invention, the triethylamine may be present in parts by weight of 1.8, 1.9, 2.0, 2.1, or 2.2, etc.

[0026] As a preferred embodiment of the present invention, the weight parts of the cinnamyl chloride may be 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc.

[0027] Cinnamyloxyethyl methacrylate is prepared by stirring overnight using hydroxyethyl methacrylate and cinnamyl chloride as raw materials and triethylamine as a catalyst. The methacrylate groups it contains have high reactivity and can undergo free radical reactions, while the cinnamyl groups are photosensitive and can absorb light and undergo cross-linking.

[0028] As a preferred embodiment of the present invention, the steps of the free radical reaction are as follows: by weight, 100-120 parts of anhydrous ethanol and 100-120 parts of N,N-dimethylformamide are mixed evenly, then 40-50 parts of product B and 10-20 parts of cinnamoyl oxyethyl methacrylate are added and stirred for 30-40 minutes. Under nitrogen protection, 0.4-0.8 parts of initiator are added, and the reaction is carried out at a temperature of 75-85°C for 150-160 minutes. The mixture is then rotary evaporated and dried to obtain a multifunctional auxiliary agent.

[0029] As a preferred embodiment of the present invention, the initiator is azobisisobutyronitrile or benzoyl peroxide.

[0030] A second aspect of the present invention provides a multifunctional auxiliary agent obtained by the synthesis method described in the first aspect.

[0031] A third aspect of the present invention provides the application of a multifunctional additive obtained by the synthesis method described in the first aspect in PVC processing.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The multifunctional additive of the present invention first uses modified mannitol and fumaric acid as raw materials to carry out esterification reaction to obtain product A with chain structure. Then, product A and yttrium acetate are mixed and heated to form product B with alkoxy-yttrium bond. Then, product B is reacted with cinnamoyl oxyethyl methacrylate to obtain multifunctional additive. This multifunctional additive can be used as a heat stabilizer to increase the thermal decomposition temperature of PVC, and can also act as a light stabilizer to reduce the influence of light on PVC.

[0033] (2) The thermal degradation of PVC is mainly a zipper-like process of deHCl and generating allyl chloride. In the multifunctional additive of this invention, yttrium has a high positive charge, while Cl- in HCl has a high negative charge. Therefore, it can effectively absorb the HCl formed during the thermal degradation process and slow down the degradation process. At the same time, the metal alkoxy group (alkoxy-yttrium bond) in the multifunctional additive has a highly electronegative oxygen atom, which is easy to undergo nucleophilic reaction. The carbon atom in allyl chloride has a high positive charge. Therefore, the carbon atom of allyl chloride on PVC will be attacked by the oxygen atom of the metal alkoxy group, thereby inhibiting the continuous and rapid degradation of PVC and effectively improving the thermal stability of PVC.

[0034] (3) After absorbing light, PVC undergoes a dehydrochlorination reaction, leading to chain degradation and yellowing. In this invention, cinnamoyl methacrylate is bound to the additive through methacrylate groups, and cinnamoyl groups are introduced into the additive molecular chain. Cinnamoyl groups have strong light absorption capabilities and highly overlap with the light-sensitive wavelength of PVC. The cinnamate groups excited by light will undergo a chemical reaction, and the two double bonds (C=C) will cyclize to form a four-membered ring structure, avoiding the degradation caused by the absorption of energy by the PVC molecular chain, thereby improving the light stability of PVC. In addition, cinnamoyl methacrylate contains a benzene ring structure, which, as a large-volume functional group, can improve the thermal stability of the material. Attached Figure Description

[0035] 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 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.

[0036] Figure 1 This is a schematic diagram illustrating the preparation of product A in Example 1 of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the preparation of product B in Example 1 of the present invention.

[0038] Figure 3 This is a schematic diagram illustrating the preparation of cinnamyloxyethyl methacrylate in Example 1 of the present invention.

[0039] Figure 4 This is a schematic diagram illustrating the preparation of the multifunctional auxiliary agent in Example 1 of the present invention.

[0040] Figure 5 This is a schematic diagram illustrating the preparation of modified mannitol in Example 1 of the present invention. Detailed Implementation

[0041] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0042] The sources of some components in the examples and comparative examples are as follows: Glycine, CAS No. 56-40-6, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Mannitol, CAS No. 87-78-5, was purchased from Nantong Runfeng Petrochemical Co., Ltd. Trans-butenedioic acid, CAS No. 110-17-8, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Maleic acid, CAS No. 110-16-7, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. p-Toluenesulfonic acid, CAS No. 104-15-4, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Cyclohexane, CAS No. 110-82-7, purchased from Sinopharm Chemical Reagent Co., Ltd. Yttrium acetate, CAS No. 23363-14-6, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Triethylamine, CAS No. 121-44-8, was purchased from Sinopharm Chemical Reagent Co., Ltd. Hydroxyethyl methacrylate, CAS No. 868-77-9, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Cinnamyl chloride, CAS No. 102-92-1, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Example

[0043] This embodiment provides a method for synthesizing a multifunctional auxiliary agent, including the following steps: By weight, 54 parts of modified mannitol, 15 parts of fumaric acid, and 0.4 parts of the catalyst p-toluenesulfonic acid were mixed evenly, and then 10 parts of the dehydrating agent cyclohexane were added. The mixture was heated to 160℃ under a nitrogen atmosphere for 120 min for esterification. The product was washed with anhydrous ethanol, distilled under reduced pressure, and dried under vacuum to obtain product A. 30 parts of yttrium acetate were added to 300 parts of anhydrous ethanol and ultrasonically dispersed evenly. The mixture was transferred to a reaction vessel, and then 40 parts of product A were added. The mixture was reacted at 140℃ for 4 h and dried to obtain product B. 120 parts of anhydrous ethanol and 120 parts of N,N-dimethylformamide were mixed evenly, and then 50 parts of product B and 20 parts of cinnamyloxyethyl methacrylate were added and stirred for 40 min. Under nitrogen protection, 0.8 parts of the initiator azobisisobutyronitrile were added, and the mixture was reacted at 75℃ for 160 min. The mixture was then rotary evaporated and dried to obtain a multifunctional auxiliary agent.

[0044] Preparation of the cinnamoyl oxyethyl methacrylate: 15 parts by weight of hydroxyethyl methacrylate were added to 200 parts of dichloromethane under an argon atmosphere and dissolved completely. Then, 2.2 parts of triethylamine and 20 parts of cinnamoyl chloride were added, and the mixture was stirred overnight at 4°C. The filtrate was filtered, purified by rotary evaporation, and dried to obtain liquid cinnamoyl oxyethyl methacrylate.

[0045] Preparation of the modified mannitol: 9.6 parts by weight of mannitol and 3.6 parts by weight of glycine were added to 40 parts by weight of chloroform, and then 2 drops of sulfuric acid were added. The mixture was reacted at 90°C for 6 hours and then rotary evaporated to obtain the modified mannitol. Example

[0046] This embodiment provides a method for synthesizing a multifunctional auxiliary agent, including the following steps: By weight, 36 parts of modified mannitol, 10 parts of fumaric acid, and 0.2 parts of the catalyst p-toluenesulfonic acid were mixed evenly, and then 6 parts of the dehydrating agent cyclohexane were added. The mixture was heated to 150℃ under a nitrogen atmosphere for 150 min for esterification. The product was washed with anhydrous ethanol, distilled under reduced pressure, and dried under vacuum to obtain product A. 20 parts of yttrium acetate were added to 280 parts of anhydrous ethanol and ultrasonically dispersed evenly. The mixture was transferred to a reaction vessel, and then 30 parts of product A were added. The mixture was reacted at 130℃ for 6 h and dried to obtain product B. 100 parts of anhydrous ethanol and 100 parts of N,N-dimethylformamide were mixed evenly, and then 40 parts of product B and 10 parts of cinnamoyl methacrylate were added and stirred for 30 min. Under nitrogen protection, 0.4 parts of the initiator benzoyl peroxide were added, and the reaction was carried out at 85℃ for 150 min. The mixture was then rotary evaporated and dried to obtain a multifunctional auxiliary agent.

[0047] Preparation of cinnamoyl oxyethyl methacrylate: By weight, 10 parts of hydroxyethyl methacrylate were added to 180 parts of dichloromethane under an argon atmosphere and dissolved completely. Then, 1.8 parts of triethylamine and 16 parts of cinnamoyl chloride were added, and the mixture was stirred overnight at 0°C. The filtrate was filtered, purified by rotary evaporation, and dried to obtain liquid cinnamoyl oxyethyl methacrylate.

[0048] Preparation of the modified mannitol: 9.0 parts by weight of mannitol and 3.0 parts by weight of glycine were added to 30 parts by weight of chloroform, and then 1 drop of sulfuric acid was added. The mixture was reacted at 80°C for 8 hours and then rotary evaporated to obtain the modified mannitol. Example

[0049] This embodiment provides a method for synthesizing a multifunctional auxiliary agent, including the following steps: By weight, 45 parts of modified mannitol, 12 parts of fumaric acid, and 0.3 parts of the catalyst p-toluenesulfonic acid were mixed evenly, and then 8 parts of the dehydrating agent cyclohexane were added. The mixture was heated to 155℃ under a nitrogen atmosphere for 140 min for esterification. The product was washed with anhydrous ethanol, distilled under reduced pressure, and dried under vacuum to obtain product A. 25 parts of yttrium acetate were added to 290 parts of anhydrous ethanol and ultrasonically dispersed evenly. The mixture was transferred to a reaction vessel, and then 35 parts of product A were added. The mixture was reacted at 135℃ for 5 h and dried to obtain product B. 110 parts of anhydrous ethanol and 110 parts of N,N-dimethylformamide were mixed evenly, and then 45 parts of product B and 15 parts of cinnamyloxyethyl methacrylate were added and stirred for 35 min. Under nitrogen protection, 0.6 parts of the initiator azobisisobutyronitrile were added, and the mixture was reacted at 80℃ for 155 min. The mixture was then rotary evaporated and dried to obtain a multifunctional auxiliary agent.

[0050] Preparation of cinnamoyl oxyethyl methacrylate: By weight, 12 parts of hydroxyethyl methacrylate were added to 190 parts of dichloromethane under an argon atmosphere and dissolved completely. Then, 1.9 parts of triethylamine and 18 parts of cinnamoyl chloride were added, and the mixture was stirred overnight at 2°C. The filtrate was filtered, purified by rotary evaporation, and dried to obtain liquid cinnamoyl oxyethyl methacrylate.

[0051] Preparation of the modified mannitol: 9.2 parts by weight of mannitol and 3.3 parts by weight of glycine were added to 30-40 parts by weight of chloroform, and then 1 drop of sulfuric acid was added. The mixture was reacted at 86°C for 7 hours and then rotary evaporated to obtain the modified mannitol.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that product A is used instead of the multifunctional additive in PVC processing.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that product B is used instead of the multifunctional additive in PVC processing.

[0054] Comparative Example 3 The difference between this comparative example and Example 1 is that maleic acid was used instead of trans-butenedioic acid in the preparation of product A.

[0055] PVC samples were prepared using the additives provided in the above embodiments and comparative examples: 100 parts of polyvinyl chloride, 8 parts of additives, 6 parts of calcium carbonate, 2 parts of zinc stearate, and 1 part of paraffin wax were added to a high-speed mixer and mixed evenly to obtain a masterbatch. The masterbatch was then placed in a tablet press and heated to 170°C to press it into PVC samples. The PVC samples were then subjected to performance testing, using the following methods: Thermal stability test: 10-30 mg of PVC sample was placed in a thermogravimetric analyzer (TGA55, TA, USA). Under a nitrogen atmosphere, the temperature was increased from room temperature to 700℃ at a rate of 10℃ / min. The thermal decomposition temperature T at which 10% mass loss was obtained from the TGA spectrum. d (10%).

[0056] Transmittance and haze testing: The test shall be conducted in accordance with the requirements of GB / T 2410-2008 Determination of transmittance and haze of transparent plastics.

[0057] Light stability test: The PVC sample was cut into rectangular specimens of 20mm×40mm and irradiated with a high-pressure mercury lamp for 60h. The weight loss of the PVC was measured and the weight loss rate after light irradiation was calculated.

[0058] The performance test data above are shown in Table 1.

[0059] Table 1 Performance Test Results

[0060] As can be seen from the above, the multifunctional additive of the present invention first undergoes an esterification reaction using modified mannitol and fumaric acid as raw materials to form product A with a chain structure; then product A is mixed with yttrium acetate and subjected to a heated reaction, causing the lone pair electrons of the oxygen atom to move towards the yttrium atom and resulting in a decrease in the yttrium binding energy, thereby forming product B with alkoxy-yttrium bonds; at the same time, product B contains carbon-carbon double bonds that can undergo free radical reactions with the methacrylate groups of cinnamyloxyethyl methacrylate to obtain a multifunctional additive that can improve the thermal and light stability of PCV (Examples 1 to 3), and its comprehensive performance, such as thermal decomposition temperature, transmittance, haze, and weight loss rate after light irradiation, is better.

[0061] Compared to Example 1, using product A instead of the multifunctional additive in PVC processing, the lack of yttrium and cinnamic yl groups resulted in decreased thermal stability and worse light stability of PVC (Comparative Example 1); compared to Example 1, using product B instead of the multifunctional additive in PVC processing, the lack of cinnamic yl groups resulted in decreased thermal stability and worse light stability of PVC (Comparative Example 2); compared to Example 1, using maleic acid instead of fumaric acid in the preparation of product A resulted in decreased thermal stability of PVC due to the non-symmetrical linear structure of maleic acid and its poor heat resistance (Comparative Example 3).

Claims

1. A method for synthesizing a multifunctional auxiliary agent, characterized in that, Includes the following steps: Esterification reaction of modified mannitol and dicarboxylic acid yields product A. Product A is mixed with yttrium salt and reacted to yield product B. Product B is mixed with cinnamoyl oxyethyl methacrylate and subjected to free radical reaction to obtain a multifunctional auxiliary agent.

2. The method for synthesizing a multifunctional auxiliary agent according to claim 1, characterized in that, The preparation steps of product A are as follows: by weight, 36-54 parts of modified mannitol, 10-15 parts of diacid and 0.2-0.4 parts of catalyst are mixed evenly, then 6-10 parts of dehydrating agent are added, and the mixture is heated to 150-160℃ under nitrogen atmosphere for esterification reaction for 120-150 min. The mixture is washed with anhydrous ethanol, distilled under reduced pressure and dried under vacuum to obtain product A.

3. The method for synthesizing a multifunctional auxiliary agent according to claim 2, characterized in that, The dicarboxylic acid is fumaric acid; The modified mannitol is prepared by adding 9.0-9.6 parts by weight of mannitol and 3.0-3.6 parts by weight of glycine to 30-40 parts by weight of chloroform, then adding 1-2 drops of sulfuric acid, reacting at 80-90°C for 6-8 hours, and then rotary evaporating to obtain modified mannitol.

4. The method for synthesizing a multifunctional auxiliary agent according to claim 1, characterized in that, The preparation steps of product B are as follows: by weight, 20-30 parts of yttrium salt are added to 280-300 parts of anhydrous ethanol and ultrasonically dispersed evenly. The mixture is then transferred to a reaction vessel and 30-40 parts of product A are added. The mixture is reacted at 130-140℃ for 4-6 hours and then dried to obtain product B.

5. The method for synthesizing a multifunctional auxiliary agent according to claim 4, characterized in that, The yttrium salt is yttrium acetate.

6. The method for synthesizing a multifunctional auxiliary agent according to claim 1, characterized in that, The preparation steps of the cinnamoyl oxyethyl methacrylate are as follows: by weight, 10-15 parts of hydroxyethyl methacrylate are added to 180-200 parts of dichloromethane under an argon atmosphere and dissolved completely. Then, 1.8-2.2 parts of triethylamine and 16-20 parts of cinnamoyl chloride are added, and the mixture is stirred overnight at 0-4°C. The filtrate is filtered, purified by rotary evaporation, and dried to obtain liquid cinnamoyl oxyethyl methacrylate.

7. The method for synthesizing a multifunctional auxiliary agent according to claim 1, characterized in that, The steps of the free radical reaction are as follows: by weight, 100-120 parts of anhydrous ethanol and 100-120 parts of N,N-dimethylformamide are mixed evenly, then 40-50 parts of product B and 10-20 parts of cinnamoyl oxyethyl methacrylate are added and stirred for 30-40 minutes. Under nitrogen protection, 0.4-0.8 parts of initiator are added, and the temperature is controlled at 75-85℃ for 150-160 minutes. The mixture is then rotary evaporated and dried to obtain a multifunctional auxiliary agent.

8. The method for synthesizing a multifunctional auxiliary agent according to claim 7, characterized in that, The initiator is azobisisobutyronitrile or benzoyl peroxide.

9. A multifunctional additive, characterized in that, Obtained by the synthesis method as described in any one of claims 1 to 8.

10. The application of the multifunctional additive obtained by the synthesis method according to any one of claims 1 to 8 in PVC processing.

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