A method for preparing a bio-based plasticizer

Abstract

This invention belongs to the field of plasticizer technology, specifically relating to a method for preparing a bio-based plasticizer. The invention provides a method for preparing a bio-based plasticizer, comprising the following steps: esterifying a diacid, oleic acid, and a diol under the action of a catalyst to obtain a diacid-oleic acid diol ester; and epoxidizing the diacid-oleic acid diol ester and hydrogen peroxide under the action of a weak acid and a catalyst to obtain the bio-based plasticizer. This invention uses diacid, oleic acid, and a diol as raw materials to synthesize a bio-based plasticizer through esterification and epoxidation reactions. When applied to PVC, this plasticizer can significantly increase the processing time of PVC products on a two-roll mill to over 120 minutes. Furthermore, it exhibits excellent pull-out resistance and good aging resistance in various liquids, making it a high-quality, non-toxic plasticizer.

Description

Technical Field

[0001] This invention belongs to the field of plasticizer technology, and specifically relates to a method for preparing a bio-based plasticizer. Background Technology

[0002] Plasticizers, as the most widely used additives in the modern plastics industry, improve the processability, plasticity, and flexibility of polymer resins, and are applied in aerospace, medical and health, automobile manufacturing, food packaging, coatings, and electrical insulation. For a long time, plasticizers have mainly been phthalates. However, it has been found that these plasticizers have certain toxic side effects on the human body. Therefore, the European Union's food safety agency has set limits on the concentrations of dioctyl phthalate (DOP) and dioctyl adipate (DOA). Thus, non-toxic and environmentally friendly plasticizers have become a key focus of global plasticizer research.

[0003] Trioctyl trimellitate (TOTM), a non-toxic and environmentally friendly plasticizer, is widely used as a heat-resistant plasticizer for PVC, a primary plasticizer in 90e and 105e grade heat-resistant cable formulations, and a complementary plasticizer for 6kV and 10kV high-voltage cables. It can also be used as an impregnating agent and high-temperature insulating varnish, and is widely used in the coating materials for electrical internal components, automotive wiring, semiconductors, etc. It has been fully recognized and developed in the plasticizer industry. In particular, the stricter environmental standards imposed by the EU RoHS directive and REACH regulations have confirmed that TOTM will gradually replace the currently commonly used DOP in the plasticizer industry. TOTM has good aging resistance, corrosion resistance, low volatility, cold resistance, and electrical insulation, but its oil resistance is not as good as polyester plasticizers, and it is not resistant to polar solvents such as ethanol. Furthermore, its processing time on an open mill is relatively short, with sticking to the rollers after about 30 minutes. TOTM is also entirely a petroleum-based plasticizer, and since petroleum is a non-renewable product, the ultimate price of TOTM is expected to continue to rise.

[0004] Bio-based plasticizers can be categorized into non-vegetable oil plasticizers (such as citric acid, succinic acid, and lactic acid) and vegetable oil plasticizers based on their raw material source. Non-vegetable oil plasticizers can reduce frictional resistance between polymer chains and improve polymer plasticity; however, their limited raw material sources, high production costs, low relative molecular mass, and tendency to migrate restrict their ability to replace petroleum-based phthalate plasticizers. In contrast, plasticizers prepared from natural vegetable oils possess excellent characteristics such as abundant raw material sources, superior plasticizing performance, controllable structure, and being green, non-toxic, and biodegradable. They are considered one of the most ideal bio-based plasticizers for completely replacing traditional petroleum-based phthalates.

[0005] Existing technology discloses a novel, non-toxic plasticizer, diacetylepoxy vegetable oleate glycerol ester, which exhibits better stability, flowability, and molecular weight than epoxidized soybean oil, and better compatibility with PVC plastic. Its synthesis method involves first transesterifying vegetable oil with glycerol under a catalyst to obtain vegetable oleate monoglyceride, then acetylifying it to synthesize diacetyl vegetable oleate glycerol ester, and finally epoxidizing it in formic acid and hydrogen peroxide to obtain diacetylepoxy vegetable oleate glycerol ester. Existing technology also discloses a non-toxic plasticizer, epoxy oleate neopentyl glycol ester, whose synthesis steps include first esterifying oleic acid with neopentyl glycol to synthesize neopentyl glycol oleate, and then epoxidizing the neopentyl glycol oleate with hydrogen peroxide to synthesize epoxy oleate neopentyl glycol ester. This method has a simple preparation process, produces plastic products with excellent processing performance, high UV blocking rate, and good solvent exudation resistance; especially when applied to wire and cable materials, it results in products with good aging resistance and good low-temperature impact embrittlement resistance.

[0006] However, while the two types of bio-based plasticizers mentioned above have a longer processing time on an open mill than petroleum-based plasticizers, they still cannot meet the needs of certain special industries, and their oil resistance is slightly inferior and needs improvement. Therefore, developing an environmentally friendly bio-based plasticizer with good heat resistance, long processing time, and superior resistance to precipitation in various types of liquids has broad market prospects. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a bio-based plasticizer. The bio-based plasticizer prepared by the method provided by this invention has good heat resistance, long processing time, and superior resistance to precipitation in various types of liquids.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention provides a method for preparing a bio-based plasticizer, comprising the following steps:

[0010] Dicarboxylic acid, oleic acid and diol are esterified in the presence of a catalyst to obtain oleic acid diol ester.

[0011] The bio-based plasticizer is obtained by epoxidizing the dicarboxylic acid oleic acid diol ester and hydrogen peroxide under the action of a weak acid and a catalyst.

[0012] Preferably, the diol includes at least one selected from neopentyl glycol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and diethylene glycol.

[0013] Preferably, the dicarboxylic acid includes at least one of adipic acid, terephthalic acid, and sebacic acid;

[0014] When the dicarboxylic acid is two kinds and includes terephthalic acid, the amount of terephthalic acid is 0-80% of the remaining dicarboxylic acid, and not 0%.

[0015] When the dicarboxylic acid is adipic acid, terephthalic acid, and sebacic acid, the molar ratio of adipic acid, terephthalic acid, and sebacic acid is 10-20:60-80:10-20.

[0016] Preferably, the molar ratio of the dicarboxylic acid to oleic acid is 1:2;

[0017] The amount of hydroxyl groups in the diol is 1 to 1.2 times the total amount of carboxyl groups in the diacid and oleic acid.

[0018] Preferably, the catalyst in the esterification reaction includes at least one of tetrabutyl titanate, phosphoric acid, and sodium phosphate, and the mass of the catalyst is 0.1 to 0.3% of the total mass of the diacid, oleic acid, and diol.

[0019] Preferably, the esterification reaction is carried out at a temperature of 130–250°C for 10–22 hours.

[0020] Preferably, when the dicarboxylic acid does not include terephthalic acid, the esterification reaction process is a temperature-programmed process, which includes: holding at 130-140℃, 141-150℃ and 151-160℃ for 1-2 hours respectively, holding at 161-170℃, 180-190℃ and 200-210℃ for 1-2 hours respectively, and holding at 220-230℃ for 6-10 hours;

[0021] When the dicarboxylic acid includes terephthalic acid, the esterification reaction process is as follows: the diol and terephthalic acid undergo a first esterification reaction under the action of a catalyst to obtain a terephthalic acid diol ester system.

[0022] The remaining raw materials were added to the diol terephthalate system to carry out a second esterification reaction;

[0023] The temperature of the first esterification reaction is 180–210°C, and the holding time is 12–17 h;

[0024] The second esterification reaction is a programmed temperature process, which includes: holding at 130-140℃, 141-150℃ and 151-160℃ for 1-2 hours respectively, holding at 161-170℃, 180-190℃ and 200-210℃ for 1-2 hours respectively, and holding at 220-230℃ for 6-10 hours.

[0025] Preferably, the catalyst in the epoxidation reaction includes sulfuric acid or phosphoric acid; the weak acid in the epoxidation reaction includes formic acid and / or acetic acid.

[0026] Preferably, the mass ratio of the dicarboxylic acid oleic acid diol ester to hydrogen peroxide is 1:0.3 to 0.6;

[0027] The mass ratio of the dicarboxylic acid oleic acid diol ester to the weak acid is 1:0.03-0.06;

[0028] The mass ratio of the dicarboxylic acid oleic acid diol ester to the catalyst is 1:0.001 to 0.003.

[0029] Preferably, the epoxidation reaction is carried out at a temperature of 60–80°C for 6–12 hours.

[0030] This invention provides a method for preparing a bio-based plasticizer, comprising the following steps: esterifying a diacid, oleic acid, and a diol under the action of a catalyst to obtain a diacid-oleic acid diol ester; and epoxidizing the diacid-oleic acid diol ester and hydrogen peroxide under the action of a weak acid and a catalyst to obtain the bio-based plasticizer.

[0031] This invention uses diacids, oleic acid, and diols as raw materials to synthesize bio-based plasticizers through esterification and epoxidation reactions. The bio-based plasticizers obtained by this invention are similar to polyester plasticizers, but have a lower degree of polymerization due to the absence of condensation polymerization; they also possess an epoxy structure and belong to the epoxy plasticizer category. Polyester plasticizers exhibit superior extraction resistance compared to traditional phthalate monomer-based plasticizers, primarily because they have a larger molecular weight, resulting in better compatibility with PVC polymers. Another reason is their higher polarity and longer molecular chains, leading to better resistance to extraction by both polar and non-polar solvents. Epoxy plasticizers, on the other hand, possess highly active epoxy groups that can absorb hydrogen chloride released during the decomposition of PVC resin. They exhibit good stabilizing effects against light and heat, and are non-toxic, odorless PVC plasticizers and heat stabilizers. Furthermore, they have good compatibility with PVC resins, low volatility, and low migration. The plasticizer provided by this invention, when applied to PVC, can significantly increase the processing time of PVC products on an open mill to over 120 minutes. Moreover, it exhibits excellent extraction resistance and good aging resistance in various liquids, making it a high-quality, non-toxic plasticizer. Attached Figure Description

[0032] Figure 1 The 1H NMR spectrum of neopentyl terephthalate in Example 7;

[0033] Figure 2 The 1H NMR spectrum of adipic acid-terephthalic acid-neopentyl oleate in Example 7;

[0034] Figure 3 This is the 1H NMR spectrum of adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester in Example 7;

[0035] Figure 4 The infrared spectrum of neopentyl terephthalate in Example 7;

[0036] Figure 5 The infrared spectrum of adipic acid-terephthalic acid-neopentyl oleate in Example 7;

[0037] Figure 6 The infrared spectrum of adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester in Example 7 is shown. Detailed Implementation

[0038] This invention provides a method for preparing a bio-based plasticizer, comprising the following steps:

[0039] Dicarboxylic acid, oleic acid and diol are esterified in the presence of a catalyst to obtain oleic acid diol ester.

[0040] The bio-based plasticizer is obtained by epoxidizing the dicarboxylic acid oleic acid diol ester and hydrogen peroxide under the action of a weak acid and a catalyst.

[0041] This invention involves esterifying a dicarboxylic acid, oleic acid, and a diol under the action of a catalyst to obtain a dicarboxylic acid-oleic acid diol ester.

[0042] In this invention, the diol preferably includes at least one selected from neopentyl glycol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and diethylene glycol. In this invention, the diacid preferably includes at least one selected from adipic acid, terephthalic acid, and sebacic acid; when there are two diacids and terephthalic acid is included, the amount of terephthalic acid is 0-80% of the remaining diacids, and not 0%; when the diacids are adipic acid, terephthalic acid, and sebacic acid, the molar ratio of adipic acid, terephthalic acid, and sebacic acid is 10-20:60-80:10-20.

[0043] In this invention, the molar ratio of the diacid to oleic acid is preferably 1:2; the molar amount of the hydroxyl group in the diol is preferably 1 to 1.2 times the total molar amount of the carboxyl groups in the diacid and oleic acid.

[0044] In this invention, the catalyst in the esterification reaction preferably includes at least one of tetrabutyl titanate, phosphoric acid, and sodium phosphate, and the mass of the catalyst is preferably 0.1 to 0.3% of the total mass of the dicarboxylic acid, oleic acid, and diol.

[0045] In this invention, the preferred temperature for the esterification reaction is 130–250°C, and the preferred holding time is 10–22 h. In this invention, the esterification reaction is preferably carried out under a nitrogen atmosphere. In this invention, the esterification reaction is preferably carried out under reflux conditions.

[0046] In this invention, when the dicarboxylic acid does not include terephthalic acid, the esterification reaction process is preferably a programmed temperature rise process, which preferably includes: holding at 130-140℃, 141-150℃ and 151-160℃ for 1-2 hours respectively, holding at 161-170℃, 180-190℃ and 200-210℃ for 1-2 hours respectively, and holding at 220-230℃ for 6-10 hours.

[0047] In this invention, when the dicarboxylic acid includes terephthalic acid, the preferred esterification reaction process is as follows: a first esterification reaction is carried out between the diol and terephthalic acid under the action of a catalyst to obtain a terephthalic acid diol ester system; the remaining raw materials are added to the terephthalic acid diol ester system to carry out a second esterification reaction; the preferred temperature of the first esterification reaction is 180–210°C, and the preferred holding time is 12–17 h; the preferred process of the second esterification reaction is a programmed temperature rise process, which preferably includes: holding at 130–140°C, 141–150°C, and 151–160°C for 1–2 h respectively, holding at 161–170°C, 180–190°C, and 200–210°C for 1–2 h respectively, and holding at 220–230°C for 6–10 h.

[0048] In this invention, the esterification reaction process preferably includes intermittent sampling and detection of the acid value of the product. When the acid value is less than 2.0 mg KOH / g, the esterification reaction is considered to be complete.

[0049] In this invention, the dicarboxylic acid oleic acid diol ester is preferably an oily substance, and the acid value of the dicarboxylic acid oleic acid diol ester is preferably ≤2.0mgKOH / g, and the iodine value is preferably 65~85I2 / 100g.

[0050] After obtaining the dicarboxylic acid oleic acid diol ester, the present invention performs an epoxidation reaction on the dicarboxylic acid oleic acid diol ester and hydrogen peroxide under the action of a weak acid and a catalyst to obtain the bio-based plasticizer.

[0051] In this invention, the mass concentration of hydrogen peroxide is preferably 50%. In this invention, the catalyst in the epoxidation reaction preferably includes sulfuric acid or phosphoric acid; the weak acid in the epoxidation reaction preferably includes formic acid and / or acetic acid. In this invention, the mass ratio of the diacid oleic acid diol ester to hydrogen peroxide is preferably 1:0.3–0.6; the mass ratio of the diacid oleic acid diol ester to the weak acid is preferably 1:0.03–0.06; and the mass ratio of the diacid oleic acid diol ester to the catalyst is preferably 1:0.001–0.003.

[0052] In this invention, the preferred epoxidation process is as follows: a dicarboxylic acid oleic acid diol ester, a weak acid, and a catalyst are mixed to obtain a mixed system; the mixed system is preheated under stirring, and then hydrogen peroxide is added dropwise to the mixed system to carry out the epoxidation reaction. In this invention, the preheating temperature is preferably 55°C.

[0053] In this invention, the preferred temperature for the epoxidation reaction is 60–80°C, and the preferred holding time is 6–12 hours. In this invention, the epoxidation reaction is preferably carried out under conditions of stirring and reflux heating.

[0054] In this invention, after the epoxidation reaction, it is preferable to further include post-treatment of the obtained reaction system. The post-treatment preferably includes: separating the reaction system to obtain an oil phase; washing the oil phase with water until neutral; and then sequentially performing vacuum distillation and filtration to obtain the bio-based plasticizer. In this invention, the bio-based plasticizer is preferably an oily substance, and the preferred acid value of the bio-based plasticizer is ≤3.0 mgKOH / g, the preferred iodine value is ≤3.0 I2 / 100g, and the preferred epoxy value is ≥3.2%.

[0055] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0056] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0057] Example 1

[0058] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 146 g of adipic acid, 564 g of oleic acid, 229 g of neopentyl glycol, and 2.76 g of phosphoric acid catalyst were added sequentially. Nitrogen gas was introduced and the mixture was stirred and heated to 140℃, 150℃, and 160℃ for 1 hour each, 170℃, 190℃, and 210℃ for 2 hours each, and 230℃ for 8 hours. The reaction was stopped intermittently when the acid value of the product was less than 2.0 mg KOH / g, yielding a light yellow oily substance, neopentyl glycol adipic acid oleate. Testing showed an acid value of 1.88 mg KOH / g and an iodine value of 80.93 I2 / 100g.

[0059] 800g of the obtained adipic acid oleate neopentyl glycol ester, 35g of formic acid, and 1.0g of phosphoric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 55°C. 370g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 60°C for 10 hours. The lower layer of acidic water was separated, and the upper layer of oil ester was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a light yellow oily substance, adipic acid epoxy oleate neopentyl glycol ester. The test results showed that its acid value was 2.12mgKOH / g, epoxy value was 3.86%, and iodine value was 1.69I2 / 100g.

[0060] Example 2

[0061] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 202 g of sebacic acid, 564 g of oleic acid, 218 g of neopentyl glycol, and 1.8 g of phosphoric acid catalyst were added sequentially. Nitrogen gas was introduced and the mixture was stirred and heated to 135℃, 145℃, and 160℃ for 1 hour each, 165℃, 185℃, and 210℃ for 2 hours each, and 220℃ for 10 hours. The reaction was stopped intermittently when the acid value of the product was less than 2.0 mg KOH / g, yielding a light yellow oily substance, sebacic acid oleic acid neopentyl glycol ester. Testing showed its acid value to be 1.82 mg KOH / g and its iodine value to be 77.52 I₂ / 100g.

[0062] 800g of the obtained sebacic acid oleate neopentyl glycol ester, 32g of formic acid, and 0.8g of phosphoric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 50°C. 320g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 80°C for 6 hours. The lower layer of acidic water was separated, and the upper layer of oil ester was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a light yellow oily substance, sebacic acid epoxy oleate neopentyl glycol ester. The test results showed that its acid value was 2.40mgKOH / g, epoxy value was 3.58%, and iodine value was 2.63I2 / 100g.

[0063] Example 3

[0064] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 146 g of adipic acid, 564 g of oleic acid, 164.2 g of 1,2-propanediol, and 1.0 g of phosphoric acid catalyst were added sequentially. Nitrogen gas was introduced and the mixture was stirred and heated to 140℃, 150℃, and 160℃ for 1.5 h each, then to 170℃, 190℃, and 210℃ for 1.5 h each, and finally to 230℃ for 8 h. The reaction was intermittently sampled, and stopped when the acid value of the product was less than 2.0 mg KOH / g, yielding a light yellow oily substance, propylene glycol adipic acid oleate. Testing showed its acid value to be 1.75 mg KOH / g and its iodine value to be 83.21 I₂ / 100g.

[0065] 800g of the obtained adipic acid oleate propylene glycol ester, 39g of formic acid, and 1.0g of concentrated sulfuric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 55°C. 390g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 70°C for 10 hours. The lower layer of acidic water was separated, and the upper layer of oil ester was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a light yellow oily substance, adipic acid epoxy oleate propylene glycol ester. The test results showed that its acid value was 2.34mgKOH / g, epoxy value was 3.92%, and iodine value was 2.61I2 / 100g.

[0066] Example 4

[0067] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 332 g of terephthalic acid, 364 g of 1,2-propanediol, and 2.8 g of phosphoric acid catalyst were added sequentially. The mixture was stirred and heated to 180°C and maintained at this temperature for 17 hours. The product was intermittently sampled, and the reaction was stopped when the acid value of the product was less than 3.0 mg KOH / g, yielding a colorless and transparent liquid, propylene glycol terephthalate, with an acid value of 2.91 mg KOH / g.

[0068] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 600 g of the propylene glycol terephthalate obtained above and 1128 g of oleic acid were added. Nitrogen gas was introduced and the mixture was stirred and heated to 135℃, 145℃, and 155℃ respectively, and kept at these temperatures for 1.5 h; 165℃, 185℃, and 205℃ respectively, and kept at these temperatures for 2 h; and finally, kept at 220℃ for 9 h. The product was intermittently sampled, and the reaction was stopped when the acid value of the product was less than 2.0 mg KOH / g, yielding a light yellow oily substance, propylene glycol terephthalate oleate. Testing showed that its acid value was 1.86 mg KOH / g and its iodine value was 70.82 I2 / 100g.

[0069] 1000g of the obtained terephthalic acid oleate propylene glycol ester, 36g of formic acid, and 1.0g of phosphoric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 55°C. 380g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 70°C for 12 hours. The lower layer of acidic water was separated, and the upper layer of oil ester was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a light yellow oily substance, terephthalic acid epoxy oleate propylene glycol ester. The test results showed that its acid value was 2.56mgKOH / g, its epoxy value was 3.27%, and its iodine value was 2.63I2 / 100g.

[0070] Example 5

[0071] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 332 g of terephthalic acid, 500 g of diethylene glycol, and 3.2 g of phosphoric acid catalyst were added sequentially. The mixture was stirred and heated to 190 °C and maintained at this temperature for 15 h. The product was intermittently sampled, and the reaction was stopped when the acid value of the product was less than 3.0 mg KOH / g, yielding a light yellow transparent liquid, diethylene glycol terephthalate, with an acid value of 2.96 mg KOH / g.

[0072] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 737 g of the diethylene glycol terephthalate and 1128 g of oleic acid obtained above were added. Nitrogen gas was introduced and the mixture was stirred and heated to 140℃, 150℃, and 160℃ for 1 h, 170℃, 190℃, and 210℃ for 2 h, and 230℃ for 8 h. The product was intermittently sampled, and the reaction was stopped when the acid value of the product was less than 2.0 mg KOH / g, yielding a yellow oily substance, diethylene glycol terephthalate oleate. Its acid value was measured to be 1.94 mg KOH / g, and its iodine value was 72.35 I2 / 100g.

[0073] 1000g of the obtained diethylene glycol oleate terephthalate, 41g of formic acid, and 1.0g of phosphoric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 50°C. 410g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 65°C for 11 hours. The lower layer of acidic water was separated, and the upper layer of oil ester was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a yellow oily substance, epoxy oleate diethylene glycol terephthalate. The test results showed that its acid value was 2.80mgKOH / g, its epoxy value was 3.31%, and its iodine value was 2.48I2 / 100g.

[0074] Example 6

[0075] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 121.3 g of terephthalic acid, 418.3 g of neopentyl glycol, and 2.5 g of phosphoric acid catalyst were added sequentially. The mixture was stirred and heated to 195 °C and maintained at this temperature for 14 h. The product was intermittently sampled, and the reaction was stopped when the acid value of the product was less than 3.0 mg KOH / g, yielding a colorless and transparent liquid, neopentyl glycol terephthalate, with an acid value of 2.90 mg KOH / g.

[0076] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 508 g of the neopentyl terephthalate prepared above, 160 g of adipic acid, and 1032.1 g of oleic acid were added sequentially. Nitrogen gas was introduced and the mixture was stirred and heated to 135℃, 145℃, and 155℃ for 1.5 h, 170℃, 190℃, and 210℃ for 2 h, and 230℃ for 6 h. The reaction was carried out intermittently, and the reaction was stopped when the acid value of the product was less than 2.0 mg KOH / g, yielding a light yellow oily substance, adipic acid-terephthalic acid-oleic acid neopentyl terephthalate, with an acid value of 1.92 mg KOH / g and an iodine value of 65.75 I2 / 100g.

[0077] 1000g of the adipic acid-terephthalic acid-oleic acid neopentyl glycol ester obtained above, 31g of formic acid, and 1.0g of concentrated sulfuric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 55°C. 310g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 65°C for 12 hours. The lower layer of acidic water was separated, and the upper layer of oil ester was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a light yellow oily substance, adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester. The test results showed that its acid value was 2.05mgKOH / g, its epoxy value was 3.34%, and its iodine value was 1.39I2 / 100g.

[0078] Example 7

[0079] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 227.7 g of terephthalic acid, 418.3 g of neopentyl glycol, and 3 g of phosphoric acid catalyst were added sequentially. The mixture was stirred and heated to 205 °C and maintained at this temperature for 12 hours. The product was intermittently sampled, and the reaction was stopped when the acid value of the product was less than 3.0 mg KOH / g, yielding a colorless and transparent liquid, neopentyl glycol terephthalate, with an acid value of 2.92 mg KOH / g.

[0080] In a three-necked round-bottom flask equipped with a stirrer, thermometer, water separator, and reflux condenser, 567 g of the neopentyl terephthalate obtained above, 66.7 g of adipic acid, and 1032.1 g of oleic acid were added sequentially. Nitrogen gas was introduced and the mixture was stirred and heated to 135℃, 145℃, and 155℃ for 1.5 h each, 165℃, 185℃, and 205℃ for 1.5 h each, and 230℃ for 10 h. The reaction was stopped intermittently when the acid value of the product was less than 2.0 mg KOH / g, yielding a light yellow oily substance, adipic acid-terephthalic acid-oleic acid neopentyl terephthalate, with an acid value of 1.88 mg KOH / g and an iodine value of 65.12 I2 / 100g.

[0081] 1000g of the adipic acid-terephthalic acid-oleic acid neopentyl glycol ester obtained above, 33g of formic acid, and 1.0g of concentrated sulfuric acid catalyst were added to a four-necked round-bottom flask equipped with a stirrer, thermometer, separatory funnel, and reflux condenser. The mixture was stirred and heated to 50°C. 330g of 50% hydrogen peroxide was slowly added dropwise while stirring. After the addition was complete, the mixture was reacted at 70°C for 10 hours. The lower layer of acidic water was separated, and the upper layer of oil was washed with water until neutral. The mixture was then distilled under reduced pressure to remove water and filtered to obtain a light yellow oily substance, adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester. The test results showed that its acid value was 2.31mgKOH / g, its epoxy value was 3.41%, and its iodine value was 1.56I2 / 100g.

[0082] Performance testing

[0083] Test Example 1

[0084] Figures 1-3 The following are the 1H NMR spectra of the intermediate and final products obtained in Example 7.

[0085] in, Figure 1 The 1H NMR spectrum of neopentyl terephthalate is shown below. Figure 1 As shown, the peak at δ = 7.28 ppm is caused by the solvent; the peaks at δ = 0.90–1.19 ppm represent methyl groups; and the peak at δ = 2.65 ppm represents unreacted hydroxyl hydrogen (-OH) in neopentyl glycol. * The peak at δ = 3.42–3.50 ppm indicates the methylene-CH group linked to the hydroxyl group. * The peak at δ = 4.21–4.28 ppm represents the methylene group (-CH) attached to the carbonyl group in the neopentyl glycol group. * The peak at δ = 8.07–8.11 ppm represents the H atom on the aromatic ring of the terephthalic acid fragment. It can be seen that the hydroxyl group in neopentyl glycol undergoes an esterification reaction with the carboxyl group in terephthalic acid to synthesize neopentyl glycol terephthalate. Simultaneously, some excess hydroxyl groups in the neopentyl glycol fragment remain unreacted, and neopentyl glycol is in excess.

[0086] Figure 2 This is the 1H NMR spectrum of adipic acid-terephthalic acid-neopentyl oleate. (Reference) Figure 1 It can be seen that, Figure 2 Many new characteristic peaks appeared, including: the peak at δ = 1.27 ppm representing the intrinsic methylene group on the backbone of oleic acid and adipic acid; the peak at δ = 1.63 ppm representing the methylene group attached to a methyl group in the oleic acid chain; the peak at δ = 2.01 ppm representing the methylene group attached to an alkene bond in the oleic acid chain; the peak at δ = 2.77 ppm representing the methylene group between two alkene bonds; and the peak at δ = 5.34 ppm representing the carbon-carbon double bond -CH in the oleic acid chain. * =CH * -

[0087] Figure 1 The value at δ = 2.65 ppm represents the unreacted hydroxyl hydrogen (-OH) in neopentyl glycol. * The peak at Figure 2 The value disappears from the original δ = 3.31–3.44 ppm, which represents the methylene group (-CH) bonded to the hydroxyl group. * The peak of 2-OH is at Figure 2 The middle part was significantly weakened, while Figure 2 New characteristic peaks appeared at 2.31, 3.89, 4.01, and 4.17 ppm. Specifically: the peak at 2.31 ppm represents the methylene group attached to the carbonyl group in oleic acid and adipic acid; the peak at 3.89 ppm represents the methylene group of the neopentyl glycol fragment linked to the ester bond formed between oleic acid and neopentyl glycol; and the peaks at 4.01–4.17 ppm represent the methylene group of the neopentyl glycol fragment linked to the ester bond formed between adipic acid and neopentyl glycol. This indicates that in the second esterification reaction, the excess hydroxyl group of neopentyl glycol esterified with the carboxyl group in oleic acid and adipic acid to form adipic acid-terephthalic acid-oleic acid neopentyl glycol ester.

[0088] Figure 3 This is the 1H NMR spectrum of adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester. (See reference spectrum.) Figure 2 It can be seen that, Figure 2 The value at δ = 5.34 ppm indicates the -CH double bond in the oleic acid chain. * =CH * - The peak disappeared, and Figure 3 The presence of a chemical shift signal representing the methylene hydrogen at δ = 2.90 ppm indicates that the carbon-carbon double bond in the adipic acid-terephthalic acid-oleic acid neopentyl glycol ester obtained by the second esterification reaction was epoxidized to synthesize adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester.

[0089] Test Example 2

[0090] Figures 4-6 Infrared spectra of the intermediate and final products obtained in Example 7;

[0091] in, Figure 4 The infrared spectrum of neopentyl terephthalate; as shown. Figure 4 As shown, 3334cm -1 The absorption peak is attributed to the -OH stretching vibration, at 1050 cm⁻¹. -1 The stretching vibration absorption peaks attributed to C-OH (primary alcohol) both indicate that there is an excess of unreacted hydroxyl groups in neopentyl glycol and that neopentyl glycol is in excess; 2973 cm⁻¹ -1 The absorption peak at 2865 cm⁻¹ is attributed to the CH asymmetric stretching vibration of -CH₃ and -CH₂-. -1 Absorption peak attributable to the CH symmetric stretching vibrations of -CH3 and -CH2-; 1715 cm⁻¹ -1 The absorption peak attributable to the C=O stretching vibration of the ester carbonyl group is 1250 cm⁻¹. -1 The absorption peak is attributed to the asymmetric stretching vibration of the ester single bond COC, at 1106 cm⁻¹. -1 The absorption peak attributed to the COC symmetric stretching vibration of the ester single bond indicates the presence of numerous ester bonds in the intermediate product. Specifically, the hydroxyl group in neopentyl glycol underwent an esterification reaction with the carboxyl group in terephthalic acid to synthesize neopentyl glycol terephthalate. (1503 cm⁻¹) -1 This is the absorption peak of the stretching vibration of the benzene ring C=C; 1467 cm⁻¹ -1 The absorption peak at 1364 cm⁻¹ is attributed to the CH asymmetric bending vibration of -CH₃ and -CH₂-. -1 Absorption peak attributable to the CH symmetric bending vibrations of -CH3 and -CH2-; 10¹³ cm⁻¹ -1 and 956cm -1 All absorption peaks are attributed to the in-plane bending vibration of the benzene ring CH, at 874 cm⁻¹. -1 Absorption peak attributable to the out-of-plane bending vibration of the benzene ring (CH); 719 cm⁻¹ -1 The absorption peak is attributed to the planar rocking vibration of the methylene group.

[0092] Figure 5 The infrared spectrum of adipic acid-terephthalic acid-neopentyl oleate is shown in the reference image. Figure 4 It can be seen that, Figure 4 Central Plains 3334cm -1 The absorption peak attributable to the -OH stretching vibration is in Figure 5 It disappeared from the middle, originally 1050cm -1 The stretching vibration absorption peak attributable to C-OH (primary alcohol) is in Figure 5 The decrease is negligible, while Figure 5 1158cm -1A new absorption peak appears, which is attributed to the COC symmetric stretching vibration absorption peak of the ester single bond formed by the reaction of neopentyl glycol with oleic acid and adipic acid. This indicates that in the second esterification reaction, the excess hydroxyl group of neopentyl glycol reacted with the carboxyl group in oleic acid and adipic acid to form adipic acid-terephthalic acid-oleic acid neopentyl glycol ester. Figure 5 3008cm -1 A new absorption peak also appears, which is attributed to the CH stretching vibration absorption peak of the unsaturated hydrocarbon CH=CH in the oleic acid chain.

[0093] Figure 6 This is the infrared spectrum of adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester. (Reference) Figure 5 It can be seen that, Figure 5 Central Plains 3008cm -1 The absorption peak of the CH stretching vibration belonging to unsaturated hydrocarbons CH=CH is located at Figure 6 It disappeared from the middle, and Figure 6 840cm -1 A new absorption peak appears, which is attributed to the asymmetric stretching vibration absorption peak of the three-membered ring ether (epoxy bond). This indicates that the carbon-carbon double bond in the intermediate product adipic acid-terephthalic acid-oleic acid neopentyl glycol ester synthesized by the second esterification reaction was epoxidized to synthesize adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester.

[0094] Through the Figures 1-6 The detailed analysis fully demonstrates that a bio-based plasticizer can be synthesized using the method provided by this invention.

[0095] Test Example 3

[0096] The bio-based plasticizers prepared in Examples 1, 4 and 7 were compared with commonly used commercial plasticizers DOTP and TOTM in the prior art, as well as our existing bio-based plasticizers diacetyl epoxide glyceryl ester (Example 1 of CN102285946A) and neopentyl glycol epoxide oleate (Example 3 of CN112898235A) in application performance comparison experiments.

[0097] Experimental formulation: 100 parts PVC, 46 parts plasticizer, and 1.5 parts heat stabilizer.

[0098] The test items and results are as follows:

[0099] (1) Processing time on the open mill, open mill temperature 180℃:

[0100] Table 1 shows the time it takes for several different plasticized PVC mixtures to start sticking to the rollers and failing to be drawn into sheets during the plasticizing and molding process on an open mill:

[0101] Table 1 Processing time of different plasticized PVC blends

[0102] Example 1 (Adipic acid epoxy oleate neopentyl glycol ester) 120min Example 4 (Epoxy oleate propylene glycol terephthalate) 180min Example 7 (Adipic acid-terephthalic acid-epoxyoleic acid neopentyl glycol ester) 130min DOTP 35min TOTM 35min Diacetylepoxyvegetal oleic acid glyceride 85min Neopentyl oleate 70min

[0103] As shown in Table 1, the PVC mixtures plasticized by the bio-based plasticizers prepared in Examples 1, 4 and 7 have a much longer processing time than commonly used petroleum-based plasticizers such as DOTP and TOTM, and also longer than some of our existing bio-based plasticizers, exhibiting more durable heat resistance during processing.

[0104] (2) Pull-out resistance of different plasticized PVC products:

[0105] Plastic products may come into contact with water, oil, or organic solvents during use. If the plasticizer used has poor pull-out resistance, it may be extracted from the plastic during use, thus accelerating the aging of the plastic products. Pull-out resistance is an important indicator of plasticizer performance.

[0106] Common and representative non-polar solvents such as n-hexane, polar solvents such as anhydrous ethanol, olive oil, and 902# test oil were selected for testing. The immersion temperatures and times of several different plasticized PVC products in various liquids are as follows:

[0107] (1) The soaking temperature in hexane and anhydrous ethanol was 25°C and the soaking time was 72h;

[0108] (2) The soaking temperature in olive oil is 40℃ and the soaking time is 240h;

[0109] (3) The immersion temperature in 902# test oil was 100℃ and the immersion time was 96h.

[0110] After soaking, the liquid on the different plasticized PVC products was cleaned off, dried at 90℃ for 2 hours, and then placed at room temperature for 24 hours before testing. The test results are shown in Tables 2 and 3.

[0111] Table 2. Extraction resistance of different plasticized PVC products in olive oil

[0112]

[0113]

[0114] As shown in Table 2, the total migration of PVC products plasticized by the bio-based plasticizers prepared in Examples 1, 4 and 7 in olive oil is greater than that of TOTM, but much less than that of other plasticizers. That is, the bio-based plasticizers prepared in this invention have slightly worse extraction resistance in olive oil than TOTM, but much better than other commonly used plasticizers.

[0115] Table 3. Extraction resistance of different plasticized PVC products in hexane, anhydrous ethanol, and 902# test oil.

[0116]

[0117]

[0118] As shown in Table 3, in the hexane extraction resistance test, the residual elongation at break of different plasticized PVC products, from largest to smallest, is as follows: Example 7 > Example 4 > Example 1 ≈ Neopentyl oleate > Diacetyl epoxy vegetable oleate > DOTP > TOTM. Among them, the residual elongation at break of the PVC product plasticized by the bio-based plasticizer prepared in Example 7 of this invention is 91.63%, while TOTM has almost no residue, only 1.41%, the difference is very large; the mass loss of different plasticized PVC products in hexane, from smallest to largest, is as follows: Example 1 ≈ Example 4 ≈ Example 7 < Diacetyl epoxy vegetable oleate < DOTP < Neopentyl oleate < TOTM.

[0119] As shown in Table 3, in the extraction resistance test of anhydrous ethanol, the residual elongation at break of different plasticized PVC products, from largest to smallest, is as follows: neopentyl oleate > Example 7 > Example 4 > Example 1 > diacetyl epoxy glycerol vegetable oleate > TOTM > DOTP. Among them, the residual elongation at break of the PVC product plasticized by the bio-based plasticizer prepared in Example 7 of this invention is 91.54%, while DOTP has almost no residue, only 1.24%, which is a very large difference. Moreover, during the test, it was observed that the PVC product plasticized by DOTP eventually hardened, whitened and shrank. The mass loss of different plasticized PVC products in anhydrous ethanol, from smallest to largest, is as follows: Example 7 < Example 4 < Example 1 < diacetyl epoxy glycerol vegetable oleate < TOTM < neopentyl oleate < DOTP.

[0120] As shown in Table 3, in the extraction resistance test of 902# test oil, the residual elongation at break of different plasticized PVC products, from largest to smallest, is as follows: diacetylepoxy glyceryl vegetable oil > Example 4 > Example 1 > Example 7 > TOTM > DOTP > neopentyl glycol epoxy oleate. Among them, the residual elongation at break of the PVC product plasticized by the bio-based plasticizer prepared in Example 4 of this invention is 63.76%, which is less than the 75.13% of diacetylepoxy glyceryl vegetable oil, but greater than the other plasticizers. The mass loss of different plasticized PVC products in anhydrous ethanol, from smallest to largest, is as follows: diacetylepoxy glyceryl vegetable oil < Example 4 < Example 1 < Example 7 < TOTM < DOTP < neopentyl glycol epoxy oleate.

[0121] In summary, the extraction resistance of several bio-based plasticizers is better than that of petroleum-based plasticizers. The bio-based plasticizers prepared by Examples 1, 4 and 7 of this invention all showed excellent extraction resistance in the selected test liquids.

[0122] (3) Aging resistance of different plasticized PVC products:

[0123] Thermal aging test conditions: 136℃, 168h. The aging resistance of different plasticized PVC products is shown in Table 4.

[0124] Table 4. Aging resistance properties of different plasticized PVC products

[0125]

[0126] In the 136℃ aging resistance test of wires and cables, the change rate of elongation at break and the change rate of tensile strength should be ≤±20%, and the smaller the change rate, the better. During the test, it was found that although DOTP-plasticized PVC products did not exude oil after aging, they became blacker, smaller, and harder. As shown in Table 4, the change rates of elongation at break and tensile strength of DOTP-plasticized PVC products after aging were -96.05% and 108.55%, respectively. After aging, there was almost no elongation at break, meaning the plasticizing properties were lost. Due to the hardening of the sample sheets, the tensile strength increased significantly, from the original 29.95 MPa to 62.46 MPa. Therefore, DOTP is not suitable for use alone in 136℃ wire and cable materials; in practical applications, it is often used in combination with other plasticizers.

[0127] As shown in Table 4, the changes in elongation at break and tensile strength of PVC products plasticized by the bio-based plasticizers prepared in Examples 1 and 7 of this invention after aging are both less than ±20%, and their aging resistance is better than that of other plasticizers.

[0128] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a bio-based plasticizer, characterized in that, Includes the following steps: An esterification reaction is carried out on a diacid, oleic acid, and a diol under the action of a catalyst to obtain a diacid-oleic acid diol ester; wherein the diol includes at least one selected from neopentyl glycol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and diethylene glycol; wherein the diacid includes at least one selected from adipic acid, terephthalic acid, and sebacic acid; when the diacid is two and includes terephthalic acid, the amount of terephthalic acid is 0-80% of the remaining diacid, and not 0%; when the diacid is adipic acid... When the diol contains terephthalic acid and sebacic acid, the molar ratio of the terephthalic acid, sebacic acid, and sebacic acid is 10~20:60~80:10~20; the molar ratio of the diacid and oleic acid is 1:2; the amount of hydroxyl groups in the diol is 1~1.2 times the total amount of carboxyl groups in the diacid and oleic acid; the temperature of the esterification reaction is 130~250℃, and the holding time is 10~22h; when the diacid does not include terephthalic acid, the esterification reaction process is a programmed temperature rise process. The programmed temperature rise process includes: holding at 130~140℃, 141~150℃, and 151~160℃ for 1~2 hours respectively, holding at 161~170℃, 180~190℃, and 200~210℃ for 1~2 hours respectively, and holding at 220~230℃ for 6~10 hours; when the dicarboxylic acid includes terephthalic acid, the esterification reaction process is as follows: the diol and terephthalic acid undergo a first esterification reaction under the action of a catalyst to obtain a terephthalic acid diol ester system; in the terephthalic acid... The remaining raw materials are added to the acid diol ester system to carry out a second esterification reaction; the temperature of the first esterification reaction is 180~210℃, and the holding time is 12~17h; the process of the second esterification reaction is a programmed temperature rise process, which includes: holding at 130~140℃, 141~150℃ and 151~160℃ for 1~2h respectively, holding at 161~170℃, 180~190℃ and 200~210℃ for 1~2h respectively, and holding at 220~230℃ for 6~10h; The bio-based plasticizer is obtained by epoxidizing the dicarboxylic acid oleic acid diol ester and hydrogen peroxide under the action of a weak acid and a catalyst. The catalyst in the epoxidation reaction includes sulfuric acid or phosphoric acid; The mass ratio of the dicarboxylic acid oleic acid diol ester to the weak acid is 1:0.03~0.06; The epoxy value of the bio-based plasticizer is ≥3.2%.

2. The preparation method according to claim 1, characterized in that, The catalyst in the esterification reaction includes at least one of tetrabutyl titanate, phosphoric acid, and sodium phosphate, and the mass of the catalyst is 0.1 to 0.3% of the total mass of the dicarboxylic acid, oleic acid, and diol.

3. The preparation method according to claim 1, characterized in that, The weak acids in the epoxidation reaction include formic acid and / or acetic acid.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the dicarboxylic acid oleic acid diol ester to hydrogen peroxide is 1:0.3~0.6; The mass ratio of the dicarboxylic acid oleic acid diol ester to the catalyst is 1:0.001~0.

003.

5. The preparation method according to claim 1 or 4, characterized in that, The epoxidation reaction is carried out at a temperature of 60-80℃ for 6-12 hours.

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