A method for synthesizing a plasticizer

Abstract

The present invention relates to the technical field of plasticizer synthesis, and specifically to a method for synthesizing a plasticizer. In the present invention, cardanol is esterified with an organic acid to generate cardanol ester, the cardanol ester is epoxidized to obtain epoxy cardanol ester, and then further reacts with a phosphorus-containing compound through ring-opening of the epoxy group to obtain phosphated cardanol ester. The present invention synthesizes three types of plasticizers, namely cardanol ester, epoxy cardanol ester, and phosphated cardanol ester. The introduction of a rigid aromatic group improves the heat resistance of cardanol ester for plasticizing PVC; the epoxy cardanol ester is obtained by epoxidizing cardanol ester, and the epoxy value is 2.11 - 3.39, which improves the mechanical tensile properties of the material after being used to plasticize PVC; the phosphorus element is introduced through ring-opening of the epoxy group, and the obtained plasticizer is used to plasticize PVC, and the LOI value of the material in the combustion test is 26.12 - 27.89%, which improves the flame retardancy; the MIL-100(Fe) supported quaternary ammonium salt catalyst has high catalytic efficiency, and the catalytic effect value after 10 uses is 81.0 - 87.1%, and it has good recyclability; the phosphated cardanol ester is used for plasticizing PVC materials, and has good solvent resistance to migration and good plasticizing effect.

Description

Technical Field

[0001] The present invention relates to the technical field of plasticizer synthesis, and specifically to a method for synthesizing a plasticizer. Background Art

[0002] Plasticizers, also known as plasticizing agents, are additives that can improve the plasticity, processability, and flexibility of polymer resins. They are widely used in fields such as aerospace, healthcare, food packaging, and coatings. However, these phthalate plasticizers belong to environmental hormones and have hazards such as genetic toxicity and endocrine disruption. They are prone to volatilization or migration, causing the product to lose its flexibility. Therefore, their widespread use has been restricted in China, the European Union, and other countries.

[0003] Meeting the requirements of green environmental protection, economy, and health, bio-based plasticizers are ideal substitutes for petroleum-based plasticizers. Bio-based plasticizers such as citrate plasticizers, lactate plasticizers, and succinate plasticizers meet the requirements of ecological environmental protection. However, their raw material sources are limited, production costs are high, relative molecular weights are low, and they are prone to migration. Vegetable oil-based plasticizers have a wide range of raw material sources. Tung oil, castor oil, palm oil, etc. are non-edible oils with high yields. Vegetable oil-based plasticizers have excellent plasticizing properties, are green, non-toxic, and biodegradable. However, vegetable oil-based plasticizers have poor compatibility with polymers and cannot be retained in polymers for a long time. Generally, they can only be used as auxiliary plasticizers and cannot be applied alone to plasticize materials. In addition, vegetable oil-based plasticizers have a single function and cannot achieve multiple purposes simultaneously, further restricting their widespread application.

[0004] Chinese Patent 201910146287.1 discloses "a method for preparing an environmentally friendly plasticizer", which combines epoxidized soybean oil with a polyester plasticizer, increasing the compatibility of the plasticizer with polyvinyl chloride (PVC), improving the plasticizing efficiency and excellent durability, but having poor heat resistance. To improve the thermal stability of vegetable oil-based plasticizers, Yang Y, Zhang C, Han Y, et al. Plasticizing and thermal stabilizing effect of bio-based epoxidized cardanol esters on PVC [J]. Polym. Advan. Technol., 2022, 34(1): 181-194. Synthesized epoxidized cardanol ester (ECE) plasticizer using cardanol and three fatty acids as raw materials and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling agent. The resulting plasticizer improved the thermal stability of plasticized PVC.

[0005] Chinese Patent 202210184684.X, "Preparation Method of a High Plasticizing and Anti-Migration Cardanol-Based Plasticizer", uses cardanol, ethylene oxide, and fatty acid as raw materials to prepare a cardanol-based polyoxyethylene ether fatty acid ester containing a large number of ether bond groups, endowing PVC products with excellent properties such as extension and anti-migration; 202110040624.6 provides "An Epoxidized Dica rdanyl Carbonate Plasticizer", in which two molecules of cardanol are coupled through the form of carbonate and then epoxidized to obtain an epoxidized dica rdanyl carbonate plasticizer, enabling the matrix polymer to have good tensile strength and impact strength; the epoxidized cardanol ether ester plasticizer obtained in Chinese Patent 202010091031.8, "An Epoxidized Cardanol Ether Ester Plasticizer and Its Preparation Method and Application", is used to plasticize PVC, increasing the flexibility of PVC products while also extending the service life of PVC products.

[0006] Although certain research results have been achieved for cardanol-based plasticizers, there are still the following problems: the effects of cardanol-based plasticizers are single, and they cannot simultaneously possess characteristics such as heat resistance, flame retardancy, migration resistance, and good mechanical properties; in addition, during the process of modifying and synthesizing epoxidized vegetable oil-based plasticizers including cardanol-based ones, catalysts are inevitably used, but inorganic acid catalysts have the problem of corroding equipment, and new catalysts each have their own disadvantages: such as poor repeatability, low selectivity, and difficult recovery and treatment.

[0007] There is an urgent need for a method to prepare high-quality, multifunctional (with compatibilization, good thermal stability, strong flame retardancy, good migration resistance, and good mechanical properties) vegetable oil-based plasticizers to achieve the wide industrial application of vegetable oil-based plasticizers.

[0008] For this reason, a synthesis method of a plasticizer is proposed. Summary of the Invention

[0009] The purpose of the present invention is to provide a synthesis method of a plasticizer. Through the direct esterification reaction of cardanol with organic acid to generate cardanol ester, the cardanol ester is oxidized by H 2 O 2 solution under the catalysis of a catalyst to obtain epoxidized cardanol ester, and the epoxidized cardanol ester further reacts with a phosphorus-containing compound through the ring-opening of the epoxy group to obtain phosphorylated cardanol ester; the catalyst has high catalytic efficiency for the epoxidation reaction and good recyclability; the obtained cardanol-based ester plasticizer is used to plasticize PVC materials, improving the heat resistance, tensile properties, flame retardancy, and migration resistance of PVC materials.

[0010] To achieve the above purpose, the present invention provides the following technical solutions:

[0011] A synthesis method of a plasticizer, characterized in that: the synthesis method of the plasticizer includes the following steps:

[0012]

[0013] S1 is the synthesis step of cashew ester: Cardanol, an organic acid, and 0.001 - 0.003 mol of tetrabutyl titanate are dissolved in chloroform to form a mixed solution; the mixed solution reacts in a three-necked flask at 50 - 130 °C for 1.5 - 8.5 h, and then cools down, is washed with water, and rotary evaporated to obtain the cashew ester;

[0014] S2 is the synthesis step of epoxy cashew ester: Take the cashew ester, acetic acid, and phosphoric acid and mix them in a four-necked round-bottom flask to obtain a cashew ester solution; 0.30 - 1.4 parts of a catalyst are added to the cashew ester solution to obtain a mixture; 21 parts of 30% H 2 O 2 solution is dropped into the mixture within 15 - 45 min, and the mixture is stirred and reacted at 50 - 70 °C for 2 - 4 h to complete the epoxidation reaction, and then through separation, washing with water, and drying steps to obtain the epoxy cashew ester;

[0015] The preparation steps of the catalyst are as follows: Phosphotungstic acid is dissolved in 20 mL of 30% H 2 O 2 solution and stirred to obtain a light yellow solution; 0.08 mol of cetyltrimethylammonium chloride is dissolved in ethanol and added to the light yellow solution, and after reacting for 2 h, it is cooled, rinsed, and dried to obtain quaternary ammonium peroxophosphotungstate; 14 - 42 parts of the quaternary ammonium peroxophosphotungstate are added to 57 - 86 parts of MIL-100(Fe) aqueous dispersion, and reacted at room temperature for 12 h to obtain the catalyst;

[0016] S3 is the synthesis step of phosphated cashew ester: Take 50 parts of the epoxy cashew ester and dissolve it in 40 parts of toluene in a three-necked round-bottom flask to obtain a pre-reactant; Take 9 - 20 parts of a phosphorus-containing compound, 40 parts of toluene, and 0.05 part of a phosphorus-containing ligand and mix them evenly to obtain a mixture; The mixture is dropped into the pre-reactant in 3 portions, and reacted at 38 - 120 °C for 30 - 100 min to obtain a product; After the product is cooled, its pH is adjusted to 7, and then it is washed with water and rotary evaporated to obtain the phosphated cashew ester.

[0017] Preferably, the organic acid in S1 is one or more of p-hydroxybenzoic acid, (ALPHAS,BETAS)-BETA-[[fluorenylmethoxycarbonyl]amino]-ALPHA-hydroxybutyric acid, acetic acid, and citric acid.

[0018] Preferably, the mixed solution in S1 reacts in a three-necked flask at 50 - 120 °C for 2 - 8 h, and then cools down, is washed with water, and rotary evaporated to obtain the cashew ester.

[0019] Preferably, the addition amount of the catalyst in S2 is 0.31 - 1.2 parts.

[0020] Preferably, 15 - 40 parts of the quaternary ammonium salt of peroxophosphotungstic acid are added to 60 - 85 parts of the MIL - 100(Fe) aqueous dispersion, and the reaction is carried out for 12 h to obtain the catalyst; the catalyst is MIL - 100(Fe)@quaternary ammonium salt of peroxophosphotungstic acid.

[0021] Preferably, the phosphorus - containing compound in S3 is one or more of diethyl phosphate, triethyl phosphate, and 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide.

[0022] Preferably, the phosphorus - containing ligand in S3 is one or more of triphenylphosphine and tributylphosphine.

[0023] A plasticizer, characterized in that it comprises a compound of the following formula:

[0024]

[0025] Among them, R 1 is selected from

[0026]

[0027]

[0028] any one of the structural formulas in; R 2 is selected from any one of the structural formulas in; R 3 is selected from

[0029]

[0030] any one of the structural formulas in; R 4 is selected from

[0031]

[0032]

[0033] any one of the structural formulas in; the plasticizer is obtained by any one of the above synthesis methods.

[0034] Application of a plasticizer, characterized in that: the application of the plasticizer in the plasticization of PVC materials; the PVC masterbatch is melt-treated by a rheometer at 165 °C, 50 rpm, and 5 min to obtain a PVC melt; 10 - 40 parts of the plasticizer, 0 - 30 parts of dioctyl phthalate, 1 part of calcium stearate, and 1 part of zinc stearate are mixed with the 100 parts of the PVC melt to obtain a mixture; the mixture is subjected to high-speed stirring, internal mixing by a torque rheometer, and injection molding steps to obtain a plasticized PVC material.

[0035] Preferably, the plasticizer is directly synthesized from cardanol and organic acid to obtain cardanol ester; the cardanol ester is oxidized by an H 2 O 2 solution to obtain epoxidized cardanol ester under the catalysis of a catalyst; the epoxidized cardanol ester reacts with a phosphorus-containing compound through ring-opening of the epoxy group to obtain phosphated cardanol ester; the structure of the plasticizer is as shown above; the application of the plasticizer in the plasticization of PVC materials; the cardanol ester plasticizer contains a rigid aromatic group, and the thermal weight loss of the plasticized PVC material is less than 2.0 in the range of 0 - 220 °C, the thermal weight loss range is 55.64 - 61.58 in the range of 220 - 300 °C, and the thermal weight loss range is 20.99 - 26.37 in the range of 300 - 600 °C; the epoxy value of the epoxidized cardanol ester plasticizer is in the range of 2.11 - 3.39, and when used to plasticize PVC, the elongation at break of the material is in the range of 630.54 - 691.52%, and the tensile strength is in the range of 24.91 - 27.50 Mpa; the phosphated cardanol ester plasticizer introduces a phosphorus element, and the LOI value range of the PVC material plasticized by the phosphated cardanol ester is 26.12 - 27.89%; the catalyst is used to catalyze the synthesis of the epoxidized cardanol ester, the epoxy value of the epoxidized cardanol ester is between 3.19 and 3.41, and the catalytic effect value of the catalyst after 10 uses is between 81.0 - 87.1%; the phosphated cardanol ester is used for PVC plasticization, and the migration rate of the plasticized PVC material after soaking in a n-hexane solution for 40 h is between 4.5 - 13.4%.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. A cardanol ester plasticizer containing a rigid aromatic group is obtained by reacting cardanol with organic acids, and the organic acids include p-hydroxybenzoic acid and (αS,βS)-β-[[(9H-fluoren-9-yl)methoxycarbonyl]amino]-α-hydroxybenzenebutanoic acid, etc.; the obtained cardanol ester is used to plasticize PVC materials, so that the thermal weight loss of the PVC materials is less than 1.0 and 1.5 in the range of 0-220 °C, the thermal weight loss range is 55.64-61.58 in the range of 220-300 °C, and the thermal weight loss range is 20.99-26.37 in the range of 300-600 °C, improving the stability of the PVC materials. Therefore, it can be used as a heat-resistant plasticizer for PVC materials.

[0038] 2. The obtained cardanol ester containing a rigid aromatic group is epoxidized. Acetic acid and phosphoric acid are added to provide an acidic reaction environment, and H 2 O 2 solution is added to oxidize the unsaturated bonds in the long-chain structure, and the catalyst synthesized in the present invention is added for catalytic oxidation to generate epoxy groups; the epoxy value of the obtained epoxidized cardanol ester is in the range of 2.11-3.39, and when used to plasticize PVC, the elongation at break is in the range of 630.54-691.52%, and the tensile strength is in the range of 24.91-27.50 Mpa, with good mechanical tensile properties. The epoxidized cardanol ester improves the mechanical properties of the PVC materials.

[0039] 3. Diethyl phosphate, triethyl phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide react with the epoxidized cardanol ester respectively, and the epoxy groups in the epoxidized cardanol ester undergo ring-opening reaction to introduce phosphorus-containing groups to obtain phosphated cardanol ester, and the phosphated cardanol ester is further used for plasticizing PVC; the test results of the combustion test of the plasticized PVC show that the LOI value range is 26.12-27.89%, with good flame retardant performance. By introducing phosphorus elements into the structure of the cardanol ester to plasticize PVC, the flame retardancy of the PVC materials is improved.

[0040] 4. A quaternary ammonium peroxophosphotungstate is prepared from sodium tungstate, phosphoric acid, hydrogen peroxide (H 2 0 2 ) and cetyltrimethylammonium chloride as raw materials, and further loaded with MIL-100(Fe) to obtain a MIL-100(Fe)@quaternary ammonium peroxophosphotungstate catalyst; the catalyst is used for catalyzing the epoxidation reaction of cardanol ester, and the epoxy value of the obtained epoxidized cardanol ester is between 3.19 and 3.41. The catalytic effect value of the catalyst of the present invention after 10 uses is between 81.0-87.1%, with high catalytic efficiency, and it can be recycled multiple times with good recyclability.

[0041] 5. In the present invention, taking cardanol as the raw material, cardanol ester is first directly reacted with an organic acid to obtain cardanol ester, and then catalytically oxidized to obtain epoxidized cardanol ester. Phosphorus element is introduced by ring-opening of the epoxy group in the epoxidized cardanol ester to obtain phosphated cardanol ester. The phosphated cardanol ester is used alone to plasticize PVC. The migration rate of the obtained PVC plasticized material is between 4.5 - 13.4% after being soaked in n-hexane solution for 40 h, and it has good solvent resistance to migration and can be used as the main plasticizer for PVC materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the synthesis method of the plasticizer of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0044] Please refer to Figure 1 , the present invention provides a synthesis method of a plasticizer, and the technical solution is as follows:

[0045] Example 1

[0046] 0.12 mol of cardanol, 0.002 mol of tetrabutyl titanate and 0.10 mol of p-hydroxybenzoic acid are dissolved in 80 mL of chloroform to form a mixed solution. The mixed solution reacts in a three-necked flask at 60 °C for 8 h; after the reaction is completed, it is cooled to room temperature. The filtrate obtained by filtration is evaporated to remove the solvent using a rotary evaporator, and then washed three times with deionized water. After vacuum rotary evaporation under reduced pressure, p-hydroxybenzoic acid cardanol ester is obtained, and the yield of p-hydroxybenzoic acid cardanol ester is 95.3%.

[0047] The PVC masterbatch is melt-treated using a rheometer under the conditions of 165 °C, 50 rpm, and 5 min. 15 parts of p-hydroxybenzoic acid cardanol ester are pretreated by drying at 60 °C for 2 hours to remove the moisture that may be absorbed on the surface of the particles. Further, it is mixed with 100 parts of molten PVC, 25 parts of dioctyl phthalate (DOTP), 1 part of calcium stearate and 1 part of zinc stearate to obtain a mixture. After being stirred evenly at high speed, dumbbell-shaped samples of the mixture are prepared by a MiniJetII micro-injection molding machine (Hakke Instrument Company, Germany). The injection molding conditions are set at 165 °C, 550 bar, and 5 min. The preparation of the injection molded samples refers to GB / T17037.1 - 1997.

[0048] The steps of the synthesis method of the plasticizer in the present invention are asFigure 1 As shown in the figure. The reaction raw material cardanol was provided by Cardolite Corporation (Zhuhai, China): light yellow liquid, composed of 41% triene, 36% diene, 20% monoene and 3% saturated compounds; p-hydroxybenzoic acid CAS 99-96-7; (Alphas,Betas)-Beta-[[fluorenylmethoxycarbonyl]amino]-Alpha-hydroxybenzenebutanoic acid CAS 210754-59-9; acetic acid CAS 64-19-7; citric acid CAS 77-92-9. Other chemical reagents are of analytical grade unless otherwise specified.

[0049] Example 2

[0050] Differing from Example 1, except that the preparation conditions of the cardanol ester were changed, other conditions remained unchanged, as specifically shown in Table 1.

[0051] Table 1 Preparation conditions of cardanol ester

[0052]

[0053] The number-average molecular weights Mn of the four kinds of p-hydroxybenzoic acid cardanol esters obtained in the examples of the present invention were 425 g / mol, 423 g / mol, 421 g / mol and 419 g / mol in sequence; the number-average molecular weights Mn of the four kinds of (Alphas,Betas)-Beta-[[fluorenylmethoxycarbonyl]amino]-Alpha-hydroxybenzenebutanoic acid cardanol esters were 704 g / mol, 702 g / mol, 700 g / mol and 698 g / mol in sequence.

[0054] Comparative Example 1

[0055] The PVC product was plasticized with DOTP plasticizer, and other conditions were the same.

[0056] Comparative Example 2

[0057] The PVC product was plasticized with DINP plasticizer, and other conditions were the same.

[0058] Example 11

[0059] The plasticized PVCs prepared in Examples 1-10, Comparative Example 1 and Comparative Example 2 were subjected to thermal stability tests, and the thermal stability was tested by thermogravimetric analysis (TGA). Thermogravimetric analysis refers to a method of testing the mass of a substance under certain temperature or time conditions during temperature control, and the thermal stability of the substance can be judged through a thermogravimetric test.

[0060] Using a TGA / 1100SF thermogravimetric analyzer, the following parameters were set: nitrogen was used as the carrier gas with a flow rate of 50 mL / min, the test temperature range was 0 - 600 °C, the heating rate was 20 °C / min, and the mass of the plasticized PVC sample tested was 5 - 10 mg. The test results are shown in Table 2.

[0061] Table 2 Thermal property data of the samples obtained in different examples

[0062]

[0063] The test results show that compared with Comparative Example 1 and Comparative Example 2, when the plasticizers prepared in Examples 1 - 10 of the present invention are used to plasticize PVC, the thermal stability of the material is improved, the thermal weight loss is less than 1.0 and 1.5 in the range of 0 - 220 °C, the thermal weight loss range is 55.64 - 61.58 in the range of 220 - 300 °C, and the thermal weight loss range is 20.99 - 26.37 in the range of 300 - 600 °C, with good thermal stability. Among them, the thermal stability of the materials obtained in Examples 1 - 8 is higher than that of the materials obtained in Examples 9 and 10. This is because a rigid aromatic group benzene ring is introduced on the basis of the raw material cardanol in Examples 1 - 8, so that the final cardanol ester plasticizer contains a double benzene ring, which improves the thermal stability of the plasticizer, thereby improving the thermal stability of its plasticized product PVC; among them, Example 8 has the lowest mass loss in the range of 220 - 300 °C, which is 55.32; while Examples 9 and 10 do not introduce rigid groups, so the thermal stability is lower than that of Examples 1 - 8, but higher than that of the PVC products obtained in Comparative Example 1 and Comparative Example 2.

[0064] Example 12

[0065] 0.12 mol of cardanol, 0.003 mol of tetrabutyl titanate and 0.10 mol of p-hydroxybenzoic acid were dissolved in 80 mL of chloroform to form a mixed solution. The mixed solution was reacted in a three-necked flask at 60 °C for 5 h; after the reaction, it was cooled to room temperature, and the solvent in the filtrate obtained by filtration was removed using a rotary evaporator, and then washed three times with deionized water. After vacuum rotary evaporation under reduced pressure, p-hydroxybenzoic acid cardanol ester CBE was obtained, and the yield of p-hydroxybenzoic acid cardanol ester was 95.5%.

[0066] 30 parts of p-hydroxybenzoic acid cardanol ester, 30 parts of acetic acid and 3 parts of phosphoric acid were taken and stirred and mixed evenly in a four-necked round-bottom flask to obtain a reactant. The four-necked round-bottom flask was equipped with a mechanical stirrer, a condenser, a thermometer and a constant pressure funnel; when the system temperature reached 50 °C, 0.64 parts of a catalyst (3% of the mass of the hydrogen peroxide solution) was added, and when the temperature was further raised to 60 °C, 21 parts of 30% H 2 O 2 solution was added dropwise, H 2 O 2The solution was added to the reactants within 30 min, and the epoxidation reaction was completed by reacting at 60 °C and 800 rpm for 3 h to obtain a mixture; the mixture was separated using a separatory funnel and washed 3 times with distilled water. After the lower layer solution was neutral, the water was removed at 60 °C using a rotary evaporator to obtain epoxidized cashew nut ester of p-hydroxybenzoic acid. The catalyst was removed using a magnet after the reaction ended, washed with water, dried, and reserved for later use.

[0067] The PVC masterbatch was melt-processed using a rheometer under the conditions of 165 °C, 50 rpm, and 5 min. Based on the total mass of the system being 142 parts, 15 parts of the plasticizer were pretreated by drying at 60 °C for 2 h to eliminate the moisture that might be absorbed on the surface of the particles, and further mixed with 100 parts of molten PVC, 25 parts of dioctyl phthalate (DOTP), 1 part of calcium stearate, and 1 part of zinc stearate to obtain a mixture. After being stirred evenly at high speed, dumbbell-shaped samples of the mixture were prepared using a MiniJetII micro-injection molding machine. The injection molding conditions were set at 165 °C, 550 bar, and 5 min. The preparation of the injection molded samples was carried out with reference to GB / T17037.1-1997.

[0068] Example 13

[0069] Different from Example 12, during the preparation of epoxidized cashew nut ester of p-hydroxybenzoic acid, 0.31 part of the catalyst (accounting for 1.5% of the mass of the hydrogen peroxide solution) was added to the reactants within 15 min, and the epoxidation reaction was completed by reacting at 70 °C and 800 rpm for 2.5 h to obtain a mixture, with other conditions remaining unchanged.

[0070] Example 14

[0071] Different from Example 12, during the preparation of epoxidized cashew nut ester of p-hydroxybenzoic acid, 0.48 part of the catalyst (accounting for 2% of the mass of the hydrogen peroxide solution) was added to the reactants within 20 min, and the epoxidation reaction was completed by reacting at 60 °C and 800 rpm for 2 h to obtain a mixture, with other conditions remaining unchanged.

[0072] Example 15

[0073] Different from Example 12, during the preparation of epoxidized cashew nut ester of p-hydroxybenzoic acid, 1.2 parts of the catalyst (accounting for 6% of the amount of the hydrogen peroxide solution added) was added to the reactants within 45 min, and the epoxidation reaction was completed by reacting at 50 °C and 800 rpm for 4 h to obtain a mixture, with other conditions remaining unchanged.

[0074] The number-average molecular weights Mn of the three kinds of epoxidized cashew nut esters of p-hydroxybenzoic acid obtained in the present invention were 439 g / mol, 453 g / mol, and 467 g / mol in sequence.

[0075] Example 16

[0076] Different from Example 12, during the preparation of epoxidized cashew ester of p-hydroxybenzoic acid, the epoxidation reaction was completed at 70 °C and 800 rpm for 2 h to obtain a mixture. The PVC masterbatch was melt-treated using a rheometer at 165 °C, 50 rpm, and 5 min. Based on the total mass of the system being 142 parts, 5 parts of the plasticizer were pretreated by drying at 60 °C for 2 h to remove the moisture that might be absorbed on the particle surface, and then further mixed with 100 parts of molten PVC, 35 parts of dioctyl phthalate (DOTP), 1 part of calcium stearate, and 1 part of zinc stearate to obtain a mixture. After high-speed stirring evenly, dumbbell-shaped samples of the mixture were prepared by a MiniJetII micro-injection molding machine, and the injection molding conditions were set at 165 °C, 550 bar, and 5 min. The preparation of the injection molded samples was referred to GB / T17037.1-1997.

[0077] Example 17

[0078] The epoxy values of the epoxidized cashew ester of p-hydroxybenzoic acid prepared in Examples 12-16 were tested; the tensile properties of the plasticized PVC obtained in Examples 12-16 were tested. The epoxy value was determined according to GB / T 1677-2008 "Determination of Epoxy Value of Plasticizers", where the epoxy value refers to the amount of substance of epoxy groups contained in 100 g of epoxy resin and is the most important index for identifying epoxy groups in vegetable oil-based plasticizer products; a double-column bench-top testing machine was used to test the tensile properties of the examples, carried out in accordance with ISO 527-5:2009. Dumbbell-shaped test samples were cut from the plasticized PVC specimens using a specific mold. The test length of each specimen was 10 mm, the width was 2 mm, and the thickness was 1 mm. The tensile rate of the instrument was 50 mm / min, and the average value of 3 test results of each PVC specimen was taken as the final result. The test results of the epoxy value and tensile properties are shown in Table 3.

[0079] Table 3 Test of Epoxy Value and Tensile Properties

[0080] Example Epoxy value Elongation at break (%) Tensile strength (Mpa) Example 12 3.39 691.52±9.33 27.50±1.24 Example 13 2.11 630.54±8.62 24.91±2.27 Example 14 2.26 648.81±7.76 25.64±2.70 Example 15 3.35 682.16±8.04 27.13±2.25 Example 16 3.37 671.96±7.91 26.75±1.88

[0081] The test results of the epoxy value showed that, as shown in Examples 12-15, as the catalyst addition amount increased from 20% to 60%, the epoxy value first increased and then gradually leveled off. This was because as the catalytic oxidant was gradually added, the double bonds in the cashew ester of p-hydroxybenzoic acid were gradually oxidized to epoxy groups, and the epoxy value gradually increased; the conditions for preparing the epoxidized cashew ester of p-hydroxybenzoic acid in Example 16 were reacting at 70 °C and 800 rpm for 2 h, and other conditions were the same as those in Example 12. The epoxy value measured in Example 12 was 3.39, and the epoxy value measured in Example 12 was 3.37.

[0082] The elongation at break of the plasticized PVC material obtained in Example 12 was 691.52%, and the tensile strength was 27.50 Mpa. Compared with Examples 14 - 16, it had the best tensile properties. In Example 16, the mass of the raw materials used to prepare epoxidized cashew nut ester of p-hydroxybenzoic acid was the same as that in Example 12, but when plasticizing PVC, the addition amount of epoxidized cashew nut ester of p-hydroxybenzoic acid decreased from 15% (Example 12) to 5% (Example 16), so the final tensile properties decreased. The epoxidized cashew nut ester of p-hydroxybenzoic acid obtained from Examples 12 - 16 of the present invention was used to plasticize PVC, and the elongation at break was between 630.54 - 691.52%, and the tensile strength was between 24.91 - 27.50 Mpa, with good mechanical tensile properties.

[0083] Example 18

[0084] Take 50 parts of the epoxidized cashew nut ester of p-hydroxybenzoic acid obtained in Example 12 and 40 parts of toluene and place them in a three-necked round-bottom flask and mix evenly to obtain a pre-reactant. The flask is equipped with a polytetrafluoroethylene stirrer, a thermometer and a condenser; take 15 parts of triethyl phosphate, 40 parts of toluene and 0.05 parts of triphenylphosphine and mix evenly to obtain a mixture. The mixture is added dropwise to the pre-reactant in 3 portions and reacted at 40 °C for 30 min to obtain a product. The product is cooled to room temperature, washed with sodium hydroxide solution until the pH is 7, then washed 3 times with distilled water, and the water is removed at 60 °C using a rotary evaporator to obtain phosphorus-containing cashew nut ester of p-hydroxybenzoic acid.

[0085] The PVC masterbatch was melt-treated using a rheometer under the conditions of 165 °C, 50 rpm, and 5 min. 15 parts of the phosphorus-containing cashew nut ester of p-hydroxybenzoic acid were pretreated by drying at 60 °C for 2 hours to remove the moisture that might be absorbed on the particle surface, and then further mixed with 100 parts of molten PVC, 25 parts of dioctyl phthalate (DOTP), 1 part of calcium stearate and 1 part of zinc stearate to obtain a mixture. After high-speed stirring evenly, dumbbell-shaped samples of the mixture were prepared using a MiniJetII micro-injection molding machine. The injection conditions were set at 165 °C, 550 bar, and 5 min. The preparation of the injection samples was carried out with reference to GB / T 17037.1 - 1997.

[0086] Different from Example 18, the following reaction parameters changed, as shown in Table 4 specifically.

[0087] Table 4 Changes in reaction parameters and conditions

[0088]

[0089]

[0090] The number-average molecular weights Mn of the three phosphorus-containing cashew esters of p-hydroxybenzoic acid obtained by adding diethyl phosphate in the embodiments of the present invention are 593 g / mol, 761 g / mol, and 929 g / mol in sequence; the number-average molecular weights Mn of the three phosphorus-containing cashew esters of p-hydroxybenzoic acid obtained by adding triethyl phosphate are 595 g / mol, 765 g / mol, and 935 g / mol in sequence; the number-average molecular weights Mn of the three phosphorus-containing cashew esters of p-hydroxybenzoic acid obtained by adding DOPO are 641 g / mol, 857 g / mol, and 1115 g / mol in sequence.

[0091] Diethyl phosphate CAS 598-02-7; Triethyl phosphate (78-40-0); 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) CAS 35948-25-5.

[0092] Example 28

[0093] Except that the parameter conditions shown in Table 4 change, the content of PVC is correspondingly increased to 115 parts.

[0094] Example 29

[0095] The flame retardant properties of the plasticized PVC prepared in Examples 18-28 and Comparative Examples 3-5 and the PVC material without plasticizer were tested. The specific combustion test was carried out according to the standard of GB / T 2406.1-2008 "Plastics - Determination of flammability by oxygen index". The preparation size of the sample was 4×10×80 mm 3 . The test was carried out using a JF-3 type oxygen index measuring instrument (Nanjing Lei Instrument Co., Ltd., China). The LOI value of the flame retardant property of the PVC material without plasticizer was 24.19%. The other test results are shown in Table 5.

[0096] Table 5 Test results of combustion test

[0097] Example Example 18 Example 19 Example 20 Example 21 Example 22 Example 23 Example 24 LOI value (%) 26.54 27.16 26.97 27.35 26.12 26.30 26.53 Example Example 25 Example 26 Example 27 Example 28 Comparative example 3 Comparative example 4 Comparative example 5 LOI value (%) 26.58 27.80 27.73 27.89 23.51 23.76 23.89

[0098] The results show that in Examples 22 - 25 and Example 18, when the addition amount of triethyl phosphate is increased from 9 parts to 20 parts, the LOI value of the obtained phosphorus-containing cashew phenol for plasticizing PVC materials is increased from 26.12% to 26.58%. Among them, in Example 25, the addition amount of triethyl phosphate is 20 parts, tributylphosphine is used as the phosphorus-containing ligand, and the phosphorus-containing cashew phenol is obtained by reacting at 40 °C for 30 min. The LOI value of 15 parts of the phosphorus-containing cashew phenol and 25 parts of DOTP plasticizing PVC is 26.58%. This is because as the addition amount of triethyl phosphate increases, the epoxy groups in the cashew phenol ring open and react with more phosphorus-containing groups, and the higher the phosphorus element content in the obtained phosphorus-containing cashew phenol, the better its flame retardant effect. Usually, polymer materials with an LOI value greater than 26% will exhibit self-extinguishing behavior and are considered to have good flame retardancy. The LOI values of the plasticized PVC obtained by adding diethyl phosphate in Examples 18 - 21 are between 26.54 - 27.16%, and the LOI values are higher than those of the groups adding triethyl phosphate in Examples 22 - 25 and Example 18. This may be because the plasticizer prepared from triethyl phosphate is added to the PVC material by physical means and mixed with it, while the phosphorus in diethyl phosphate is incorporated into the molecular chain of PVC through chemical reactions, so the flame retardant effect is better. In Examples 26 - 28, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added. Compared with Examples 18 - 25, the obtained phosphorus-containing cashew phenol has more aromatic structures. Flame retardant bio-based epoxy monomers with more aromatic structures in the chemical structure are beneficial to improving the char yield. A higher char yield represents good flame retardant performance of the polymer. Therefore, the materials obtained in Examples 26 - 27 have good flame retardancy. Among them, in Example 28, the addition amount of DOPO is 20 parts, tributylphosphine is used as the phosphorus-containing ligand, and the phosphorus-containing cashew phenol is obtained by reacting at 100 °C for 90 min. The LOI value of 25 parts of the phosphorus-containing cashew phenol and 15 parts of DOTP plasticizing PVC is 27.89%, and the flame retardant performance is the best.

[0099] The test results of Comparative Examples 3 - 5 show that the LOI values are between 23.51 - 23.89%, and the flame retardant effect is poor. The obtained phosphorus-containing cashew phenol of the present invention cannot be used alone as a flame retardant for PVC, that is, it cannot be used as the main flame retardant. However, when used with DOTP, zinc stearate, and calcium stearate, the flame retardant performance of PVC materials can be significantly improved.

[0100] Example 30

[0101] 0.02 mol of phosphotungstic acid is dissolved in 20 mL of 30% H 2 O 2In a solution, stir at 50 °C for 30 min to obtain a pale yellow solution; dissolve 0.08 mol of cetyltrimethylammonium chloride in 20 mL of absolute ethanol to obtain a cetyltrimethylammonium chloride solution, and add the cetyltrimethylammonium chloride solution dropwise to the pale yellow solution. Continue to stir at 50 °C for 2 h, filter after cooling to room temperature, wash with distilled water and absolute ethanol, and dry in an oven to obtain a quaternary ammonium peroxophosphotungstate with a yield of 73.5%; take 74 parts of MIL-100(Fe) and disperse it in 30 mL of distilled water, then add 26 parts of quaternary ammonium peroxophosphotungstate, stir at 600 rpm at room temperature for 12 h, and then obtain the MIL-100(Fe)@quaternary ammonium peroxophosphotungstate catalyst through the steps of washing with water and vacuum drying.

[0102] Take 30 parts of cashew ester p-hydroxybenzoate, 30 parts of acetic acid, and 3 parts of phosphoric acid and stir and mix them evenly in a four-necked round-bottom flask to obtain a reactant. The four-necked round-bottom flask is equipped with a mechanical stirrer, a condenser, a thermometer, and a constant pressure funnel; when the system temperature reaches 50 °C, add 0.64 parts of a catalyst (3% of the mass of the hydrogen peroxide solution), continue to heat up to 60 °C and then drop in 21 parts of 30% H 2 O 2 solution, add the reactant within 30 min, and react at 60 °C and 800 rpm for 3 h to complete the epoxidation reaction to obtain a mixture; use a separating funnel to separate the mixture, wash it 3 times with distilled water, and remove the water at 60 °C with a rotary evaporator after the lower layer solution is neutral to obtain epoxidized cashew ester p-hydroxybenzoate. The MIL-100(Fe)@quaternary ammonium peroxophosphotungstate catalyst is removed using a magnet after the reaction, washed with water and dried for later use.

[0103] The information of the substances used is as follows: MIL-100(Fe) CAS 1195763-37-1; cetyltrimethylammonium chloride CAS 112-02-7.

[0104] Examples 31 - 40

[0105] Different from Example 30, the following conditions change, as shown in Table 6 specifically.

[0106] Table 6

[0107]

[0108] Example 41

[0109] The epoxy value of the epoxidized cashew ester of p-hydroxybenzoic acid obtained in Examples 30-40 was determined, and the recycling performance of the catalyst was tested. The method for determining the epoxy value was referred to Example 17; the recycling performance test index was represented by the catalytic effect obtained by epoxidation catalysis with MIL-100(Fe)@quaternary ammonium peroxytungstophosphate catalyst for 1-10 times. The calculation formula for the catalytic effect was as follows: Catalytic effect (%) = epoxy value obtained from the nth catalysis / epoxy value obtained from the first catalysis × 100%, where n was any integer from 1 to 10. The epoxy value measured each time later was compared with it. After recycling 10 times, the test results were recorded in Table 7.

[0110] Table 7 Test results of epoxidation catalytic effect and recyclability of MIL-100(Fe)@quaternary ammonium peroxytungstophosphate catalyst

[0111]

[0112]

[0113] The MIL-100(Fe)@quaternary ammonium peroxytungstophosphate catalyst obtained in Examples 30-40 was used for catalysis. The epoxy value of the obtained cashew ester of p-hydroxybenzoic acid was between 3.19 and 3.41. The catalytic effect value after 10 times of use was between 81.0% and 87.1%. MIL-100(Fe) was loaded with quaternary ammonium peroxide. The MIL-100(Fe) material had a large specific surface area and rich pore diameters, which improved the catalytic effect of quaternary ammonium peroxide; in Examples 30-33, with the increase of the addition amount of 30% H 2 O 2 solution, the epoxy value gradually increased. This was because as the oxygen source, H 2 O 2The increase leads to an increase in the peroxy groups of the quaternary ammonium salt of peroxytungstophosphoric acid, and finally the peroxy group content of the catalyst is increased, enhancing the catalytic oxidation effect of epoxidation; the catalytic effect values of Examples 30 - 33 after 10 uses are between 85.4 - 87.0%; in Examples 35 - 36, as the addition amount increases, the final epoxy value also increases from 3.27 to 3.38. This is because the generation amount of cetyltrimethylammonium peroxytungstophosphate gradually increases, and as a phase transfer catalyst in the catalytic system, it promotes the smooth progress of the epoxidation reaction; the catalytic effect values of Examples 35 - 37 after 10 uses are between 85.1 - 87.0%; the highest epoxy value obtained in Example 38 is 3.41, and the catalytic effect value after 10 uses is 87.1%; the catalytic oxidation effects and the cyclic catalytic use effects obtained in Examples 39 and 40 are the worst. This is because in Example 39, the addition amount of cetyltrimethylammonium peroxytungstophosphate is 40 parts, the addition amount of MIL-100(Fe) is 60 parts, and the addition amount of the quaternary ammonium peroxide exceeds the loading range of MIL-100(Fe), resulting in a decrease in the surface area of the composite catalyst and thus a decline in the catalytic effect. In Example 40, the addition amount of cetyltrimethylammonium peroxytungstophosphate is reduced to 15 parts, and the loading degree of MIL-100(Fe) decreases, unable to achieve a good catalytic oxidation effect for epoxidation.

[0114] Example 42

[0115] Take the cardanol p-hydroxybenzoate prepared in Example 3, and prepare epoxidized cardanol p-hydroxybenzoate according to the method of Example 12, and further prepare phosphorus-containing cardanol p-hydroxybenzoate according to the method of Example 26.

[0116] Example 43

[0117] Different from Example 42, the obtained epoxidized cardanol p-hydroxybenzoate is further prepared into phosphorus-containing cardanol p-hydroxybenzoate according to the method of Example 21.

[0118] Example 44

[0119] Different from Example 42, the obtained epoxidized cardanol p-hydroxybenzoate is further prepared into phosphorus-containing cardanol p-hydroxybenzoate according to the method of Example 25.

[0120] Example 45

[0121] Different from Example 42, (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester prepared in Example 8 was taken, and epoxidized (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester was prepared according to the method of Example 12, and further phosphorous-containing (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester was prepared according to the method of Example 26.

[0122] The number-average molecular weights Mn of the three obtained epoxidized (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew esters were 718 g / mol, 732 g / mol, and 746 g / mol in sequence; the number-average molecular weights Mn of the three obtained phosphorous-containing (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew esters were 920 g / mol, 1150 g / mol, and 1380 g / mol in sequence.

[0123] Example 46

[0124] Different from Example 45, the obtained epoxidized (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester was further prepared into phosphorous-containing (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester according to the method of Example 21.

[0125] The number-average molecular weights Mn of the three obtained phosphorous-containing (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew esters were 872 g / mol, 1040 g / mol, and 1208 g / mol in sequence.

[0126] Example 47

[0127] Different from Example 45, the obtained epoxidized (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester was further prepared into phosphorous-containing (ALPHAS,BETAS)-BETA-[[fluorenylmethyloxycarbonyl]amino]-ALPHA-hydroxybenzene butyric acid cashew ester according to the method of Example 25.

[0128] The number-average molecular weights Mn of the three obtained phosphorus-containing (ALPHAS,BETAS)-BETA-[[Fmoc]amino]-ALPHA-hydroxybenzene butyric acid cashew esters are 875 g / mol, 1044 g / mol, and 1214 g / mol, respectively.

[0129] Example 48

[0130] The phosphated cashew esters obtained in Examples 42-47 were used for PVC plasticization, and their migration resistance was tested. The PVC masterbatch was melt-treated using a rheometer under the conditions of 165 °C, 50 rpm, and 5 min. 40 parts of phosphorus-containing p-hydroxybenzoic acid cashew ester were pretreated by drying at 60 °C for 2 hours to eliminate the moisture that might be absorbed on the particle surface, and then further mixed with 100 parts of molten PVC, 1 part of calcium stearate, and 1 part of zinc stearate to obtain a mixture. After being stirred evenly at high speed, dumbbell-shaped samples of the mixture were prepared by a MiniJetII micro-injection molding machine, and the injection molding conditions were set as 165 °C, 550 bar, and 5 min. The preparation of the injection-molded samples was carried out with reference to GB / T17037.1-1997.

[0131] The plasticized PVC material was immersed in a n-hexane solution, and after standing at room temperature for 40 h, the change in its migration rate was investigated; the migration rate was calculated according to the following formula: Migration rate = (m 1 -m 2 ) / m 1 ×0.28×100%, where m 1 is the mass of the PVC material before being immersed in the n-hexane solution, and m 2 is the mass of the PVC material after being immersed in the n-hexane solution for 40 h. The test results are shown in Table 8.

[0132] Table 8 Migration rate test results

[0133] Example Example 42 Example 43 Example 44 Example 45 Example 46 Example 47 Migration rate (%) 4.5 5.8 10.9 4.8 8.5 13.4

[0134] The migration test results show that the migration rate of the phosphated cashew esters obtained in Examples 42-47 of the present invention ranges from 4.5% to 13.4% after being compounded with PVC; the migration rate of the phosphated p-hydroxybenzoic acid cashew ester obtained in Example 42 is the lowest, which is 4.5%; the migration rate of the phosphated m-chloroperbenzoic acid cashew ester obtained in Example 47 is the highest, which is 13.4%. On the one hand, compared with cardanol, the proportion of the non-polar long-chain alkyl group in the structure of the phosphated cardanol-based ester decreases, and the balance between the non-polar group and the polar group is good, so its compatibility with the PVC resin improves, and thus the migration rate decreases. On the other hand, a rigid aromatic group and a compatibilizing group are introduced, and the molecular weight of the modified cardanol-based plasticizer increases significantly. The better compatibility of the larger molecular weight, more branches and functional groups with the material makes the plasticized PVC material have high migration resistance, and the phosphated cashew ester is not easy to migrate out of the PVC material, thus prolonging its service life.

[0135] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing a plasticizer, characterized in that: The synthetic method of the plasticizer comprises the following steps: ； S1 is a synthesis step of cashew ester: cardanol, organic acid and 0.001-0.003 mol of tetrabutyl titanate are dissolved in chloroform to form a mixed solution; the mixed solution is reacted in a three-necked flask at 50-130° C. for 1.5-8.5 h, cooled, washed with water, and rotary evaporated to obtain the cashew ester; the organic acid is one of p-hydroxybenzoic acid and (ALPHAS,BETAS)-BETA-[[fluorenylmethoxycarbonyl]amino]-ALPHA-hydroxyphenylbutyric acid; S2 is a synthesis step of epoxy cashew ester: the cashew ester, the organic acid and phosphoric acid are mixed in a four-necked round-bottom flask to obtain a cashew ester solution; 0.30-1.4 parts of a catalyst are added to the cashew ester solution to obtain a mixture; 21 parts of a 30% H2O2 solution are dripped into the mixture within 15-45 minutes, and the reaction is stirred at 50-70°C for 2-4 hours to complete the epoxidation reaction, and the epoxy cashew ester is obtained through separation, water washing and drying steps; The catalyst is prepared as follows: phosphotungstic acid is dissolved in 20 mL of 30% H2O2 solution and stirred to obtain a light yellow solution; 0.08 mol of hexadecyltrimethylammonium chloride is dissolved in ethanol and added to the light yellow solution, and after reacting for 2 hours, cooling, rinsing and drying steps are performed to obtain peroxyphosphotungstate quaternary ammonium salt; 14-42 parts of the peroxyphosphotungstate quaternary ammonium salt are added to 57-86 parts of MIL-100 (Fe) aqueous dispersion, and reacted at room temperature for 12 hours to obtain the catalyst; S3 is a synthesis step of phosphated cashew ester: 50 parts of the epoxy cashew ester are dissolved in 40 parts of toluene in a three-necked round-bottom flask to obtain a pre-reactant; 9-20 parts of a phosphorus-containing compound, 40 parts of toluene and 0.05 parts of a phosphorus-containing ligand are mixed evenly to obtain a mixture; the mixture is dripped into the pre-reactant three times, and the reaction is carried out at a temperature of 38-120° C. for 30-100 minutes to obtain a product; After the product is cooled, the pH value thereof is adjusted to 7, and then washed with water and rotary evaporated to obtain the phosphated cashew nut ester, i.e., the plasticizer; In the synthesis method, R1 is selected from 、 、 or Any one of the structural formulas of ; The structural formula of R2 is selected from ; R3 is selected from 、 or Any one of the structural formulas of ; R4 is selected from 、 、 、 、 、 、 、 or Any one of the structural formulas.

2. The method for synthesizing a plasticizer according to claim 1, characterized in that: The mixed solution in S1 is reacted in a three-necked flask at 50-120° C. for 2-8 hours, cooled, washed with water, and rotary evaporated to obtain the cashew ester.

3. The method for synthesizing a plasticizer according to claim 1, characterized in that: The amount of the catalyst added in S2 is 0.31-1.2 parts.

4. The method for synthesizing a plasticizer according to claim 1, characterized in that: 15-40 parts of the quaternary ammonium peroxyphosphotungstate salt in S2 are added to 60-85 parts of MIL-100 (Fe) aqueous dispersion, and the mixture is reacted for 12 hours to obtain the catalyst; the catalyst is MIL-100 (Fe) @ quaternary ammonium peroxyphosphotungstate salt.

5. The method for synthesizing a plasticizer according to claim 1, characterized in that: The phosphorus-containing compound in S3 is one of diethyl phosphate, triethyl phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

6. The method for synthesizing a plasticizer according to claim 1, characterized in that: The phosphorus-containing ligand in S3 is one of triphenylphosphine and tributylphosphine.

7. A plasticizer, characterized in that: Including the following compounds: 、 、 ； Wherein R1 is selected from 、 、 or Any one of the structural formulas of ; The structural formula of R2 is selected from ; R3 is selected from 、 or Any one of the structural formulas of ; R4 is selected from 、 、 、 、 、 、 、 or Any one of the structural formulas of; the plasticizer is obtained by any synthesis method according to claim 1-6.

8. An application of a plasticizer, characterized in that: The use of the plasticizer in plasticizing PVC materials; the plasticizer is any one of the compounds in claim 7; the PVC masterbatch is melt-treated using a rheometer at 165°C, 50rpm, 5min to obtain a PVC melt; 10-40 parts of plasticizer, 0-30 parts of dioctyl phthalate, 1 part of calcium stearate and 1 part of zinc stearate are mixed with 100 parts of the PVC melt to obtain a mixture; the mixture is subjected to high-speed stirring, torque rheometer kneading and injection molding steps to obtain a plasticized PVC material.

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