Precipitation-resistant chlorinated fatty acid methyl ester composite environment-friendly plasticizer and preparation process thereof

Abstract

The invention relates to the technical field of environment-friendly plasticizers, in particular to a precipitation-resistant chlorinated fatty acid methyl ester composite environment-friendly plasticizer and a preparation process thereof. The invention relates to a preparation process of a precipitation-resistant chlorinated fatty acid methyl ester composite environment-friendly plasticizer. The preparation process comprises the following steps: preparing modified chlorinated fatty acid methyl ester; preparing a polyester intermediate; and preparing the composite environment-friendly plasticizer. The preparation method comprises the following steps: firstly, generating monoglyceride from palm oil and glycerol under the catalysis of calcium oxide, then reacting monoglyceride with maleic anhydride and butanol under the catalysis of tetrabutyl titanate to generate a polyester intermediate, and enabling the polyester intermediate to be subjected to cross-linking reaction with active sites of modified chlorinated fatty acid methyl ester, so that the modified chlorinated fatty acid methyl ester is obtained. Meanwhile, the polyurethane curing agent is further crosslinked with the polyether polyol, the polyester intermediate, the modified chlorinated fatty acid methyl ester and the like, and the modified chlorinated fatty acid methyl ester, the tri-n-butyl citrate and other components are locked in a network, so that the migration resistance of the composite environment-friendly plasticizer can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly plasticizers, specifically to a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters and its preparation process. Background Technology

[0002] Polyvinyl chloride (PVC), as a top-volume general-purpose plastic, has become a fundamental polymer material widely used in electric vehicles due to its low cost and excellent processing performance. It is essential for meeting the special requirements of electric vehicles, such as high-voltage insulation and sealing protection, and its applications cover core components of the vehicle, including electrical systems, battery systems, body sealing, interior trim, and cooling pipes. However, PVC molecules are rigid and have strong intermolecular forces, necessitating the addition of plasticizers to improve its flexibility, processing flow, and performance. The performance of the plasticizers directly determines the quality and application range of PVC products.

[0003] Traditional PVC plasticizers are mainly phthalates, which, while possessing advantages such as high plasticizing efficiency and good compatibility, are prone to migrating and leaching from the PVC matrix during use. This not only reduces the flexibility and shortens the lifespan of products but also poses potential hazards to human health and the environment. Consequently, their use has been restricted in food contact and children's products by many countries and regions. Against this backdrop, chloroform fatty acid methyl esters, as bio-based environmentally friendly plasticizers, are gradually gaining attention due to their reliance on renewable oils and their low toxicity.

[0004] However, the molecular weight of ordinary chlorinated fatty acid methyl esters is usually around 300-400. According to the free volume theory, small molecules have more free space to move in the polymer matrix, resulting in a higher diffusion coefficient. Furthermore, since they are based on straight-chain fatty acid methyl esters, the backbone remains flexible straight-chain alkanes after chlorination, lacking a rigid structure. These linear "short stick"-shaped molecules have a high degree of freedom of movement in the amorphous region of PVC and are prone to sliding and diffusing along the chain segment direction, thus making them easy to migrate and precipitate.

[0005] Furthermore, the flame retardant properties of existing chlorinated fatty acid methyl ester plasticizers rely solely on chlorine. During combustion, they only exert their gas-phase flame retardant effect by releasing hydrogen chloride gas, resulting in limited flame retardant efficiency. This makes it difficult to meet the high flame retardant requirements of high-end applications. Moreover, their thermal stability is insufficient, and the ordinary ester bonds in their molecular structure are easily decomposed at high temperatures during PVC processing. The released hydrogen chloride can also trigger autocatalytic degradation of PVC, affecting the processing quality and safety of the products. In addition, the molecular chain of single chlorinated fatty acid methyl esters lacks flexibility, making PVC products prone to brittleness at low temperatures, which limits their application in cold regions or low-temperature conditions.

[0006] Therefore, it is necessary to propose a composite environmentally friendly plasticizer with good flame retardancy, thermal stability and cold resistance, and its preparation process, so as to broaden its application scenarios and extend its service life. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters and its preparation process.

[0008] This invention provides a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters. By weight, its raw material composition is as follows: 20-30 parts epoxy fatty acid methyl ester, 20-25 parts polyester intermediate, 5-10 parts cellulose acetate butyrate, 16-20 parts modified chlorinated fatty acid methyl ester, 6-8 parts polyether polyol, 3-5 parts polyurethane curing agent, 3-5 parts polycaprolactone diol, 8-10 parts tri-n-butyl citrate, 20-30 parts chlorinated fatty acid methyl ester, and 30-35 parts solvent. The preparation steps of polyester intermediates are as follows: Step 1: Under nitrogen protection, glycerol is kept at 230-240℃ for 1.5-2.5h, then palm oil and calcium oxide are added, and the mixture is kept at the temperature and stirred for 3-4h. Then it is placed in an ice-salt mixture and rapidly cooled to room temperature. After standing and separating, the glycerol is removed to obtain crude monoglyceride. Step 2: Add maleic anhydride, butanol and tetrabutyl titanate to the above crude monoglyceride. Under nitrogen protection, heat and stir at 230-240℃ for 6-8 hours. Then continue polycondensation at 220℃ under vacuum for 2-3 hours. After cooling, dissolve in acetone and recrystallize in water. Repeat 3 times. Then dry under vacuum to obtain polyester intermediate.

[0009] Furthermore, the polyether polyol is polyoxypropylene triol, the polyurethane curing agent is isophorone diisocyanate, and the solvent is propylene glycol methyl ether acetate.

[0010] Furthermore, the mass ratio of palm oil to glycerin is (4.8-5):1, and the amount of calcium oxide added is 0.1% of the total mass of glycerin and palm oil.

[0011] Furthermore, the amount of maleic anhydride added is 16-17% of the mass of palm oil, the amount of butanol added is 4.1-4.3% of the mass of palm oil, and the amount of tetrabutyl titanate added is 0.02-0.03% of the mass of palm oil.

[0012] Furthermore, the preparation steps of the modified chlorinated fatty acid methyl ester are as follows: Step 1: Add tris(2-hydroxyethyl) isocyanurate to chloro fatty acid methyl ester at a mass ratio of 1:(3.1-3.3). Under nitrogen protection, heat and stir at 80-85℃. Then add tetrabutyl titanate, raise the temperature to 100-110℃, and keep it at this temperature while stirring for 4-5 hours. Remove methanol by vacuum distillation to obtain the crude product. Step 2: Add glacial acetic acid and disodium ethylenediaminetetraacetate to the crude product above, heat to 60°C while stirring, then add 30% hydrogen peroxide solution, and keep the mixture at 60-65°C with stirring for 5-6 hours. After cooling, add saturated sodium carbonate solution to neutralize to pH 7-8, then separate the liquid and liquid phases. Wash the organic phase with distilled water until neutral, and remove residual water and solvent by vacuum distillation to obtain modified chlorinated fatty acid methyl ester.

[0013] Furthermore, the amount of tetrabutyl titanate added is 0.045% of the mass of chlorofatty acid methyl ester.

[0014] Furthermore, the amount of glacial acetic acid added is 12-13% of the crude product mass, the amount of disodium ethylenediaminetetraacetate added is 0.04-0.05% of the crude product mass, and the amount of hydrogen peroxide solution added is 37-38% of the crude product mass.

[0015] Furthermore, a preparation process for a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters includes the following steps: Step 1: Add polyester intermediate and 1 / 2 part by weight of epoxy fatty acid methyl ester to solvent, heat and stir at 90-100℃ for 30-40 min, then add cellulose acetate butyrate, continue to heat and stir for 2-3 h, and when the temperature drops to 75℃, add modified chlorinated fatty acid methyl ester, polyether polyol and polyurethane curing agent, continue to heat and react for 30-40 min to obtain a mixture; Step 2: Add polycaprolactone diol, tributyl citrate, chloro fatty acid methyl ester and the remaining epoxy fatty acid methyl ester to the above mixture, stir and mix evenly to obtain a composite environmentally friendly plasticizer.

[0016] The present invention has the following advantages: 1. In this invention, palm oil and glycerol are first reacted with calcium oxide to generate monoglycerides, and then the monoglycerides are reacted with maleic anhydride and butanol with tetrabutyl titanate to generate polyester intermediates. The terminal hydroxyl groups of the polyester intermediates can undergo cross-linking reactions with the active sites of the epoxy groups of modified chlorinated fatty acid methyl esters. At the same time, the polyurethane curing agent undergoes nucleophilic addition reactions with the hydroxyl groups of the polyether polyol, the terminal hydroxyl groups of the polyester intermediates, and the hydroxyl groups generated by the epoxy ring-opening of modified chlorinated fatty acid methyl esters, further cross-linking and strengthening the network structure. The modified chlorinated fatty acid methyl esters, tributyl citrate, and other components are "locked" in the network, hindering their free diffusion and migration, thereby effectively improving the migration resistance of the composite environmentally friendly plasticizer.

[0017] 2. In this invention, a crude product is prepared by reacting chloro fatty acid methyl ester with tris(2-hydroxyethyl) isocyanurate, and then the crude product is epoxidized to obtain modified chloro fatty acid methyl ester. Since the introduced isocyanurate ring can decompose to produce non-flammable gas during combustion, it forms a "chlorine-nitrogen synergistic flame retardant effect" with the hydrogen chloride gas produced by the decomposition of chloro fatty acid methyl ester itself, diluting the concentration of combustible gas and oxygen, and interfering with the free chain reaction of combustion in the gas phase, thereby improving the flame retardant performance of the plasticizer. Furthermore, since the isocyanurate ring has high resonance stability similar to benzene ring, its decomposition temperature is much higher than that of ordinary ester bonds. At the same time, the epoxy group introduced on the modified molecular chain is a highly active group, which can react rapidly with the hydrogen chloride released in the early stage, cut off the autocatalytic cycle, and can provide an internal auxiliary heat stabilizer for PVC. Therefore, introducing the isocyanurate ring into the chloro fatty acid methyl ester molecule and then epoxidizing it can significantly improve the thermal stability of the plasticizer molecule itself at the PVC processing temperature.

[0018] 3. In this invention, after adding polycaprolactone diol and tributyl citrate to the composite environmentally friendly plasticizer, polycaprolactone diol can deeply entangle with PVC molecular chains and modified chlorinated fatty acid methyl esters, weakening the van der Waals forces between PVC molecules, allowing PVC chain segments to still move freely at low temperatures, avoiding brittleness caused by molecular chain stiffness. The short-chain ester groups of tributyl citrate can quickly insert into the gaps between PVC molecular chains, destroying the hydrogen bonding between PVC molecules, reducing the intermolecular forces, and improving the flexibility of PVC at medium and low temperatures. When the two are used together, the long chain of polycaprolactone diol forms a strong entanglement network with PVC and modified chlorinated fatty acid methyl esters, providing long-term cold resistance stability. The short-chain branches of tributyl citrate fill the gaps in the entanglement network, reducing friction between molecular chains and improving the efficiency of chain segment movement at low temperatures, thereby achieving a synergistic effect of improving the cold resistance of the composite environmentally friendly plasticizer. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the environmentally friendly composite plasticizer with resistance to precipitation of chlorinated fatty acid methyl esters used in embodiments of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0021] Example 1: A preparation process for a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters, as follows... Figure 1 As shown, it includes the following steps: Preparation of modified chlorinated fatty acid methyl esters: Step 1: Tris(2-hydroxyethyl) isocyanurate was added to chlorofatty acid methyl ester at a mass ratio of 1:3.1. The mixture was heated and stirred at 80°C under nitrogen protection. Then, tetrabutyl titanate was added, the temperature was raised to 100°C, and the mixture was stirred and kept at this temperature for 4 hours. Methanol was removed by vacuum distillation to obtain the crude product. The amount of tetrabutyl titanate added was 0.045% of the mass of chlorofatty acid methyl ester. Step 2: Add glacial acetic acid and disodium ethylenediaminetetraacetate to the crude product, heat to 60°C while stirring, then add a 30% hydrogen peroxide solution and maintain the temperature at 60°C with stirring for 5 hours. After cooling, add saturated sodium carbonate solution to neutralize to pH 7, then separate the liquid and liquid phases. Wash the organic phase with distilled water until neutral, and remove residual water and solvent by vacuum distillation to obtain modified chlorinated fatty acid methyl esters. The amount of glacial acetic acid added is 12% of the crude product mass, the amount of disodium ethylenediaminetetraacetate added is 0.04% of the crude product mass, and the amount of hydrogen peroxide solution added is 37% of the crude product mass. Preparation of polyester intermediates: Step 1: Under nitrogen protection, glycerol was kept at 230℃ for 1.5 hours, then palm oil and calcium oxide were added, and the mixture was stirred and kept at this temperature for 3 hours. The mixture was then placed in an ice-salt mixture and rapidly cooled to room temperature. After standing and separating the layers, the glycerol was removed to obtain crude monoglyceride. The mass ratio of palm oil to glycerol was 4.8:1, and the amount of calcium oxide added was 0.1% of the total mass of glycerol and palm oil. Step 2: Maleic anhydride, butanol, and tetrabutyl titanate were added to the above crude monoglyceride. Under nitrogen protection, the mixture was heated and stirred at 230°C for 6 hours, and then polycondensed under vacuum at 220°C for 2 hours. After cooling, the mixture was dissolved in acetone and redeposited in water. This process was repeated 3 times. The mixture was then dried under vacuum to obtain a polyester intermediate. The amount of maleic anhydride added was 16% of the mass of palm oil, the amount of butanol added was 4.1% of the mass of palm oil, and the amount of tetrabutyl titanate added was 0.02% of the mass of palm oil. Preparation of composite environmentally friendly plasticizers: Step 1: Add 10 parts by weight of epoxy fatty acid methyl ester and 20 parts by weight of the above polyester intermediate to 30 parts by weight of propylene glycol methyl ether acetate. Heat and stir at 90°C for 30 min, then add 5 parts by weight of cellulose acetate butyrate. Continue to heat and stir for 2 h. When the temperature drops to 75°C, add 16 parts by weight of the above modified chlorinated fatty acid methyl ester, 6 parts by weight of polyoxypropylene triol, and 3 parts by weight of isophorone diisocyanate. Continue to heat and react for 30 min to obtain a mixture. Step 2: Add 3 parts by weight of polycaprolactone diol, 8 parts by weight of tri-n-butyl citrate, 20 parts by weight of chlorinated fatty acid methyl ester and 10 parts by weight of epoxy fatty acid methyl ester to the above mixture, stir and mix evenly to obtain a composite environmentally friendly plasticizer.

[0022] Example 2: A preparation process for a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters, as follows... Figure 1 As shown, it includes the following steps: Preparation of modified chlorinated fatty acid methyl esters: Step 1: Tris(2-hydroxyethyl) isocyanurate was added to chlorofatty acid methyl ester at a mass ratio of 1:3.2. The mixture was heated and stirred at 83°C under nitrogen protection. Then, tetrabutyl titanate was added, the temperature was raised to 105°C, and the mixture was stirred and kept at this temperature for 4.5 hours. Methanol was removed by vacuum distillation to obtain the crude product. The amount of tetrabutyl titanate added was 0.045% of the mass of chlorofatty acid methyl ester. Step 2: Add glacial acetic acid and disodium ethylenediaminetetraacetate to the crude product, heat to 60°C while stirring, then add a 30% hydrogen peroxide solution and maintain the temperature at 63°C with stirring for 5.5 hours. After cooling, add saturated sodium carbonate solution to neutralize to pH 7.5, then separate the liquid and liquid phases. Wash the organic phase with distilled water until neutral, and remove residual water and solvent by vacuum distillation to obtain modified chlorinated fatty acid methyl esters. The amount of glacial acetic acid added is 12.5% ​​of the crude product mass, the amount of disodium ethylenediaminetetraacetate added is 0.045% of the crude product mass, and the amount of hydrogen peroxide solution added is 37.5% of the crude product mass. Preparation of polyester intermediates: Step 1: Under nitrogen protection, glycerol was kept at 235℃ for 2 hours, then palm oil and calcium oxide were added, and the mixture was kept at this temperature and stirred for 3.5 hours. The mixture was then placed in an ice-salt mixture and rapidly cooled to room temperature. After standing and separating the layers, the glycerol was removed to obtain crude monoglyceride. The mass ratio of palm oil to glycerol was 4.9:1, and the amount of calcium oxide added was 0.1% of the total mass of glycerol and palm oil. Step 2: Maleic anhydride, butanol, and tetrabutyl titanate were added to the above crude monoglyceride. Under nitrogen protection, the mixture was heated and stirred at 235°C for 7 hours, and then polycondensed under vacuum at 220°C for 2.5 hours. After cooling, the mixture was dissolved in acetone and redeposited in water. This process was repeated three times. The mixture was then dried under vacuum to obtain a polyester intermediate. The amount of maleic anhydride added was 16.5% of the mass of palm oil, the amount of butanol added was 4.2% of the mass of palm oil, and the amount of tetrabutyl titanate added was 0.025% of the mass of palm oil. Preparation of composite environmentally friendly plasticizers: Step 1: Add 12.5 parts by weight of epoxy fatty acid methyl ester and 22.5 parts by weight of the above polyester intermediate to 32.5 parts by weight of propylene glycol methyl ether acetate. Heat and stir at 95°C for 35 min, then add 7.5 parts by weight of cellulose acetate butyrate. Continue to heat and stir for 2.5 h. When the temperature drops to 75°C, add 18 parts by weight of the above modified chlorinated fatty acid methyl ester, 7 parts by weight of polyoxypropylene triol, and 4 parts by weight of isophorone diisocyanate. Continue to heat and react for 35 min to obtain a mixture. Step 2: Add 4 parts by mass of polycaprolactone diol, 9 parts by mass of tri-n-butyl citrate, 25 parts by mass of chlorinated fatty acid methyl ester and 12.5 parts by mass of epoxy fatty acid methyl ester to the above mixture, stir and mix evenly to obtain a composite environmentally friendly plasticizer.

[0023] Example 3: A preparation process for a composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters, as follows: Figure 1 As shown, it includes the following steps: Preparation of modified chlorinated fatty acid methyl esters: Step 1: Tris(2-hydroxyethyl) isocyanurate was added to chlorofatty acid methyl ester at a mass ratio of 1:3.3. The mixture was heated and stirred at 85°C under nitrogen protection. Then, tetrabutyl titanate was added, the temperature was raised to 110°C, and the mixture was stirred and kept at this temperature for 5 hours. Methanol was removed by vacuum distillation to obtain the crude product. The amount of tetrabutyl titanate added was 0.045% of the mass of chlorofatty acid methyl ester. Step 2: Add glacial acetic acid and disodium ethylenediaminetetraacetate to the crude product, heat to 60°C while stirring, then add a 30% hydrogen peroxide solution and maintain the temperature at 65°C with stirring for 6 hours. After cooling, add saturated sodium carbonate solution to neutralize to pH 8, then separate the liquid and liquid phases. Wash the organic phase with distilled water until neutral, and remove residual water and solvent by vacuum distillation to obtain modified chlorinated fatty acid methyl esters. The amount of glacial acetic acid added is 13% of the crude product mass, the amount of disodium ethylenediaminetetraacetate added is 0.05% of the crude product mass, and the amount of hydrogen peroxide solution added is 38% of the crude product mass. Preparation of polyester intermediates: Step 1: Under nitrogen protection, glycerol was kept at 240℃ for 2.5 hours, then palm oil and calcium oxide were added, and the mixture was stirred and kept at this temperature for 4 hours. The mixture was then placed in an ice-salt mixture and rapidly cooled to room temperature. After standing and separating the layers, the glycerol was removed to obtain crude monoglyceride. The mass ratio of palm oil to glycerol was 5:1, and the amount of calcium oxide added was 0.1% of the total mass of glycerol and palm oil. Step 2: Maleic anhydride, butanol, and tetrabutyl titanate were added to the above crude monoglyceride. Under nitrogen protection, the mixture was heated and stirred at 240°C for 8 hours, and then polycondensed under vacuum at 220°C for 3 hours. After cooling, the mixture was dissolved in acetone and redeposited in water. This process was repeated 3 times. The mixture was then dried under vacuum to obtain a polyester intermediate. The amount of maleic anhydride added was 17% of the mass of palm oil, the amount of butanol added was 4.3% of the mass of palm oil, and the amount of tetrabutyl titanate added was 0.03% of the mass of palm oil. Preparation of composite environmentally friendly plasticizers: Step 1: Add 15 parts by weight of epoxy fatty acid methyl ester and 25 parts by weight of the above polyester intermediate to 35 parts by weight of propylene glycol methyl ether acetate. Heat and stir at 100°C for 40 min, then add 10 parts by weight of cellulose acetate butyrate. Continue to heat and stir for 3 h. When the temperature drops to 75°C, add 20 parts by weight of the above modified chlorinated fatty acid methyl ester, 8 parts by weight of polyoxypropylene triol, and 5 parts by weight of isophorone diisocyanate. Continue to heat and react for 40 min to obtain a mixture. Step 2: Add 5 parts by weight of polycaprolactone diol, 10 parts by weight of tri-n-butyl citrate, 30 parts by weight of chlorinated fatty acid methyl ester and 15 parts by weight of epoxy fatty acid methyl ester to the above mixture, stir and mix evenly to obtain a composite environmentally friendly plasticizer.

[0024] Comparative Example 1 differs from Example 1 in that the polyester intermediate in step one of preparing the composite environmentally friendly plasticizer is removed.

[0025] Comparative Example 2 differs from Example 1 in that the modified chlorinated fatty acid methyl ester in step one of the preparation of the composite environmentally friendly plasticizer is replaced with an equal amount of chlorinated fatty acid methyl ester.

[0026] Comparative Example 3 differs from Example 1 in that polycaprolactone diol in step two of preparing the composite environmentally friendly plasticizer is replaced with an equal amount of tributyl citrate.

[0027] Comparative Example 4 differs from Example 1 in that tributyl citrate in step two of preparing the composite environmentally friendly plasticizer is replaced with an equal amount of polycaprolactone diol.

[0028] Test example: Test 1: Using a twin-screw extruder, the composite environmentally friendly plasticizers prepared in Examples 1-3 and Comparative Example 1 were mixed with PVC resin powder and calcium-zinc stabilizer at a mass ratio of 100:50:3 to form PVC films. The PVC films were then cut into 20mm × 20mm samples and dried in a 40℃ constant temperature drying oven for 12 hours. The samples were then weighed on an analytical balance, and the initial mass of the sample was recorded as m0. Pour the dry activated carbon powder into a 100 mL beaker until the 20 mL mark is reached. Place the sample flat in the beaker, then pour an equal amount of activated carbon to cover its surface. Place the beaker in a constant temperature drying oven at 100℃ and dry it for 3 hours. After that, take out the sample, rinse its surface with anhydrous ethanol, and wipe it dry with clean filter paper. Finally, weigh the sample and record it as m1. The migration resistance of the composite environmentally friendly plasticizers prepared in Examples 1-3 and Comparative Example 1 is expressed by the mass loss rate. Repeat the experiment 3 times and take the average value of the 3 experimental data. The migration rate is calculated as follows: Migration rate = (m0-m1) / m0×100%. The results are shown in Table 1.

[0029] Table 1: Test Results of the Exudation Resistance of Composite Environmentally Friendly Plasticizers

[0030] As shown in Table 1, the precipitation resistance of the composite environmentally friendly plasticizer prepared in Comparative Example 1 without the addition of polyester intermediates was significantly lower than that in Example 1. This indicates that by first generating monoglycerides from palm oil and glycerol under the catalysis of calcium oxide, and then reacting the monoglycerides with maleic anhydride and butanol under the catalysis of tetrabutyl titanate to generate polyester intermediates, the terminal hydroxyl groups of the polyester intermediates can undergo cross-linking reactions with the active sites of the epoxy groups of modified chlorinated fatty acid methyl esters. At the same time, the polyurethane curing agent further cross-links with polyether polyols, polyester intermediates, and modified chlorinated fatty acid methyl esters, strengthening the network structure and "locking" components such as modified chlorinated fatty acid methyl esters and tributyl citrate in the network, hindering their free diffusion and migration, thereby effectively improving the migration resistance of the composite environmentally friendly plasticizer.

[0031] Test 2: Using a twin-screw extruder, the composite environmentally friendly plasticizers prepared in Examples 1-3 and Comparative Example 2 were mixed with PVC resin powder and calcium-zinc stabilizer at a mass ratio of 100:50:3 to form 80mm×10mm×4mm specimens. The limiting oxygen index was then tested according to GB / T2406.2-2009 standard. The experiment was repeated 3 times, and the average value of the 3 experimental data was taken. The results are shown in Table 2.

[0032] Test 3: Referring to GB / T 33047.1-2016 standard, the thermal decomposition temperature of the composite environmentally friendly plasticizers prepared in Examples 1-3 and Comparative Example 2 was tested. The heating rate was 10℃ / min. The test was repeated 3 times, and the average value of the 3 test data was taken. The results are shown in Table 2.

[0033] Table 2: Test Results of Flame Retardant Properties and Thermal Decomposition Temperature of Composite Environmentally Friendly Plasticizers

[0034] As shown in Table 2, the limiting oxygen index and thermal decomposition temperature of the composite environmentally friendly plasticizer prepared in Comparative Example 2 without modification of chloro fatty acid methyl ester were both lower than those in Example 1. This shows that by first reacting chloro fatty acid methyl ester with tris(2-hydroxyethyl) isocyanurate to prepare a crude product, and then epoxidizing the crude product to obtain modified chloro fatty acid methyl ester, the flame retardant properties and thermal stability of the plasticizer can be effectively improved.

[0035] Test 4: Using a twin-screw extruder, the composite environmentally friendly plasticizers prepared in Examples 1-3 and Comparative Examples 3-4 were mixed with PVC resin powder and calcium-zinc stabilizer at a mass ratio of 100:50:3 to form 10mm×10mm×1mm samples. Then, according to GB / T5470-2008 standard, the low-temperature embrittlement temperature of the samples was tested. The test was repeated 3 times, and the average value of the 3 test data was taken. The results are shown in Table 3.

[0036] Table 3: Low-temperature embrittlement temperature test results of composite environmentally friendly plasticizers

[0037] As shown in Table 3, when only one of tributyl citrate or polycaprolactone diol was added in Comparative Examples 3 and 4, the low-temperature embrittlement temperature of the resulting composite environmentally friendly plasticizers was higher than that of Example 1. This shows that after adding polycaprolactone diol and tributyl citrate to the composite environmentally friendly plasticizer, the long chain of polycaprolactone diol can form a strong entanglement network with PVC and modified chlorinated fatty acid methyl esters, providing long-term cold resistance stability. The short branched chain of tributyl citrate can fill the gaps in the entanglement network, reduce the friction between molecular chains, and improve the chain segment movement efficiency at low temperatures, thereby achieving a synergistic effect of improving the cold resistance of the composite environmentally friendly plasticizer.

[0038] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A composite environmentally friendly plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters, characterized in that, By weight, its raw material composition is as follows: 20-30 parts epoxy fatty acid methyl ester, 20-25 parts polyester intermediate, 5-10 parts cellulose acetate butyrate, 16-20 parts modified chlorinated fatty acid methyl ester, 6-8 parts polyether polyol, 3-5 parts polyurethane curing agent, 3-5 parts polycaprolactone diol, 8-10 parts tri-n-butyl citrate, 20-30 parts chlorinated fatty acid methyl ester, and 30-35 parts solvent. The preparation steps of polyester intermediates are as follows: Step 1: Under nitrogen protection, glycerol is kept at 230-240℃ for 1.5-2.5h, then palm oil and calcium oxide are added, and the mixture is kept at the temperature and stirred for 3-4h. Then it is placed in an ice-salt mixture and rapidly cooled to room temperature. After standing and separating, the glycerol is removed to obtain crude monoglyceride. Step 2: Add maleic anhydride, butanol and tetrabutyl titanate to the above crude monoglyceride. Under nitrogen protection, heat and stir at 230-240℃ for 6-8 hours. Then continue polycondensation at 220℃ under vacuum for 2-3 hours. After cooling, dissolve in acetone and recrystallize in water. Repeat 3 times. Then dry under vacuum to obtain polyester intermediate.

2. The environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters according to claim 1, characterized in that, The polyether polyol is polyoxypropylene triol, the polyurethane curing agent is isophorone diisocyanate, and the solvent is propylene glycol methyl ether acetate.

3. The environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters according to claim 1, characterized in that, The mass ratio of palm oil to glycerin is (4.8-5):1, and the amount of calcium oxide added is 0.1% of the total mass of glycerin and palm oil.

4. The environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters according to claim 1, characterized in that, The amount of maleic anhydride added is 16-17% of the mass of palm oil, the amount of butanol added is 4.1-4.3% of the mass of palm oil, and the amount of tetrabutyl titanate added is 0.02-0.03% of the mass of palm oil.

5. The environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters according to claim 1, characterized in that, The preparation steps for modified chlorinated fatty acid methyl esters are as follows: Step 1: Add tris(2-hydroxyethyl) isocyanurate to chloro fatty acid methyl ester at a mass ratio of 1:(3.1-3.3). Under nitrogen protection, heat and stir at 80-85℃. Then add tetrabutyl titanate, raise the temperature to 100-110℃, and keep it at this temperature while stirring for 4-5 hours. Remove methanol by vacuum distillation to obtain the crude product. Step 2: Add glacial acetic acid and disodium ethylenediaminetetraacetate to the crude product above, heat to 60°C while stirring, then add 30% hydrogen peroxide solution, and keep the mixture at 60-65°C with stirring for 5-6 hours. After cooling, add saturated sodium carbonate solution to neutralize to pH 7-8, then separate the liquid and liquid phases. Wash the organic phase with distilled water until neutral, and remove residual water and solvent by vacuum distillation to obtain modified chlorinated fatty acid methyl ester.

6. The environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters according to claim 5, characterized in that, The amount of tetrabutyl titanate added is 0.045% of the mass of chlorofatty acid methyl ester.

7. The environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters according to claim 5, characterized in that, The amount of glacial acetic acid added is 12-13% of the crude product mass, the amount of disodium ethylenediaminetetraacetate added is 0.04-0.05% of the crude product mass, and the amount of hydrogen peroxide solution added is 37-38% of the crude product mass.

8. A preparation process for the environmentally friendly composite plasticizer resistant to the precipitation of chlorinated fatty acid methyl esters as described in claim 1, characterized in that, Includes the following steps: Step 1: Add polyester intermediate and 1 / 2 part by weight of epoxy fatty acid methyl ester to solvent, heat and stir at 90-100℃ for 30-40 min, then add cellulose acetate butyrate, continue to heat and stir for 2-3 h, and when the temperature drops to 75℃, add modified chlorinated fatty acid methyl ester, polyether polyol and polyurethane curing agent, continue to heat and react for 30-40 min to obtain a mixture; Step 2: Add polycaprolactone diol, tributyl citrate, chloro fatty acid methyl ester and the remaining epoxy fatty acid methyl ester to the above mixture, stir and mix evenly to obtain a composite environmentally friendly plasticizer.

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