Bis (2-propylheptyl) sebacate as well as preparation method and application thereof

Abstract

The invention relates to di (2-propylheptyl) sebacate as well as a preparation method and application thereof, and relates to the technical field of plasticizers. Aiming at the environment-friendly defect of the traditional plasticizer, the performance limitation of the existing sebacate and the technical bottleneck of branched alcohol modification in the prior art, the invention provides a novel preparation process. According to the method, sebacic acid and 2-propyl heptanol are used as raw materials, and the plasticizer with excellent performance is prepared through specific esterification reaction conditions including the steps of staged heating, catalyst adding, vacuum dehydration and the like. The product has the characteristics of low acid value, low alcohol content, high cold resistance, low mobility and the like, is suitable for polyvinyl chloride products, and particularly has excellent performance in cold-resistant scenes. Compared with the traditional method, the preparation process provided by the invention avoids the problems of equipment corrosion and environmental pollution caused by concentrated sulfuric acid catalysis, improves the reaction efficiency and the product yield, and realizes green and efficient industrial production.

Description

Technical Field

[0001] This invention relates to the field of plasticizer technology, specifically to di(2-propylheptyl) sebacate, its preparation method, and its application. Background Technology

[0002] Traditional plasticizers have significant environmental drawbacks, and phthalates, such as DEHP and DINP, remain the mainstream plasticizers in the industry. These plasticizers pose reproductive toxicity and carcinogenic risks, and are subject to strict restrictions under regulations such as REACH. Furthermore, they are prone to migration and leaching into PVC products, facing significant regulatory pressure in areas such as food packaging and medical devices. Although environmentally friendly alternatives (such as epoxy vegetable oils and polyesters) have been introduced, their low-temperature resistance and plasticizing efficiency are insufficient, making it difficult to meet the needs of cold-resistant applications such as automotive sealing strips and refrigeration equipment parts.

[0003] Existing sebacic acid esters have limitations in performance. While sebacic acid esters (such as dioctyl sebate, DOS) possess excellent cold resistance (embrittlement temperature ≤ -60℃), their straight-chain alcohol structure leads to high volatility (loss >5% at 100℃ / 24h) and rapid migration rate (migration >8% at 70℃ / 24h). After long-term use, the hardness of the products increases while their toughness decreases. Furthermore, their synthesis processes generally employ concentrated sulfuric acid catalysis, resulting in equipment corrosion, large amounts of waste, and the need for multiple water washing and purification processes, leading to high energy consumption and a yield of less than 85%.

[0004] The modification of branched alcohols faces technical bottlenecks. Although attempts have been made in recent years to improve the migration stability of sebacic acid esters using branched alcohols (such as 2-ethylhexanol), the short-chain structure (C8 alcohols) leads to an increased glass transition temperature (Tg > -50℃), significantly deteriorating cold resistance. Meanwhile, long-chain branched alcohols (such as 2-propylheptanol) face challenges in conventional esterification processes due to steric hindrance, resulting in low reactivity and conversion rates below 90%, and there is a lack of efficient dehydration and catalyst recovery processes suitable for their high boiling point characteristics. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, the present invention aims to provide a di(2-propylheptane) sebacate, its preparation method and application, which effectively solves the problem that existing plasticizers cannot simultaneously achieve environmental protection, cold resistance and migration.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] In a first aspect, a method for preparing di(2-propylheptyl) sebacate includes the following preparation steps:

[0008] S1: Sebacic acid and 2-propylheptanol are added to the reactor in sequence, the reactor is closed, the vacuum pump is started to evacuate the reactor until the target vacuum level is reached, the vacuum pump is turned off and the nitrogen valve is opened to purge nitrogen until the pressure inside the reactor reaches atmospheric pressure, the stirring is started and the stirring speed is controlled at 280-320 rpm, heating is started and the condenser system circulating water is turned on.

[0009] S2: Heat to 140℃-160℃, maintain at normal pressure for 2.5h-3.5h, then heat to 176℃-185℃, open the alcohol recovery pipeline, adjust the valve to allow the recovered alcohol to slowly flow back into the reactor, and heat to 186℃.

[0010] Add catalyst from the catalyst feeding pipe at -190℃, continue heating to 225-228℃, maintain positive pressure and constant temperature reaction, and take samples for analysis at regular intervals. The reaction is terminated when the acid value is ≤0.1mg KOH / g.

[0011] S3: After cooling to 85℃-90℃, add liquid alkali and distilled water. After the liquid alkali and distilled water are replenished, stir for 20-40 minutes and let stand for 30-40 minutes. The water layer and ester layer will be fully separated. Discard the lower water phase and then drain the water. The residual water is then dehydrated by vacuum evaporation. When the acid value is ≤0.07mg KOH / g and the alcohol content is ≤500ppm, the dehydration and purification are completed, and di(2-propylheptane) sebacate is obtained.

[0012] Preferably, the vacuum degree in S1 is -0.095MPa to -0.098MPa, and the nitrogen purging is repeated 2-3 times.

[0013] Preferably, the mass ratio of sebacic acid and 2-propylheptanol in S1 is 1:1.9-2.3.

[0014] Preferably, the catalyst in S2 is tetrabutyl titanate, and the amount added is 0.1%-0.3% of the total feed mass.

[0015] Preferably, the positive pressure reaction pressure in S2 is 0.05MPa-0.15MPa.

[0016] Preferably, the timed sampling analysis in S2 is performed every 0.5 hours.

[0017] Preferably, the liquid alkali in S3 is a NaOH solution with a volume fraction of 30%-32%, and the amount of liquid alkali added is: The amount of distilled water added is 9%-12%.

[0018] Preferably, the vacuum evaporation and dehydration conditions in step S3 are: temperature 90℃-100℃, vacuum degree ≤-0.095MPa.

[0019] Secondly, a di(2-propylheptane) sebacate is prepared by the above-mentioned method for preparing di(2-propylheptane) sebacate, and satisfies the following conditions: acid value ≤ 0.07 mg KOH / g, alcohol content ≤ 500 ppm, and 2-propylheptane is a C10 branched alkyl group.

[0020] Thirdly, the application of di(2-propylheptane) sebacate as a plasticizer in polyvinyl chloride products.

[0021] Preferably, the amount of di(2-propylheptane) sebacate added to the PVC formulation is 30-70 phr.

[0022] The beneficial effects of this invention are:

[0023] 1. The di(2-propylheptyl) sebacate plasticizer prepared by this invention has significantly reduced toxicity compared to traditional plasticizers, meets increasingly stringent environmental regulations, and can be widely used in fields with high safety requirements such as food packaging and medical devices, helping to reduce environmental pollution and potential harm to human health.

[0024] 2. The plasticizer prepared by the di(2-propylheptyl) sebacate plasticizer of the present invention exhibits excellent performance in terms of low temperature resistance, low migration and low volatility. It can effectively improve the service life and performance of polyvinyl chloride products, meet the application requirements of various cold-resistant scenarios such as automotive sealing strips and refrigeration equipment parts, and enable the products to maintain good flexibility and strength in low temperature environments.

[0025] 3. This invention employs a unique esterification process. By precisely controlling reaction conditions, such as using tetrabutyl titanate as a catalyst and optimizing reaction temperature and pressure, it not only improves reaction efficiency and product yield but also solves the problem of low reactivity of long-chain branched alcohols. This enables green and efficient industrial production and reduces production costs and energy consumption.

[0026] 4. The preparation method of this invention has high production efficiency and product quality, enabling large-scale stable production and bringing good economic benefits to related enterprises. Furthermore, due to the product's high performance and environmentally friendly characteristics, it helps enterprises gain a competitive advantage and expand their market share. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing di(2-propylheptyl) sebacate, comprising the following preparation steps:

[0030] S1: Add 10.0 kg of sebacic acid and 19.0 kg of 2-propylheptanol to the reactor in sequence, close the reactor, start the vacuum pump to evacuate to -0.098 MPa, turn off the vacuum pump and open the nitrogen valve to purge nitrogen until the pressure inside the reactor reaches atmospheric pressure. Replace the nitrogen twice, start stirring, and control the stirring speed at 300 rpm. Start heating and turn on the condenser system to circulate water.

[0031] S2: Heat to 140℃, maintain at ambient pressure for 3.1h, heat to 176℃, open the alcohol recovery pipeline, adjust the valve to allow the alcohol recovery to slowly flow back into the reactor, heat to 186℃, add 0.087kg of tetrabutyl titanate through the catalyst feeding pipeline, continue heating to 225℃, maintain a positive pressure of 0.05MPa, react at a constant temperature, and take samples every 0.5h. The reaction is terminated when the acid value reaches 0.08mg KOH / g.

[0032] S3: After cooling to 85℃, add 5.1kg of 30% NaOH solution and 2.15kg of distilled water. After the alkali and distilled water are replenished, stir for 20min and let stand for 30min. The water layer and ester layer will be fully separated. Discard the lower water phase and then drain the water. Vacuum evaporate and dehydrate at 90℃ and -0.098MPa. When the acid value is 0.05mg KOH / g and the alcohol content is 402ppm, the dehydration and purification is completed, and di(2-propylheptane) sebacate is obtained. It is a colorless and transparent liquid with a yield of 96.2% and a viscosity (25℃) of 41mPa˙s.

[0033] Example 2

[0034] A method for preparing di(2-propylheptyl) sebacate, comprising the following preparation steps:

[0035] S1: Add 10.0 kg of sebacic acid and 21.2 kg of 2-propylheptanol to the reactor in sequence, close the reactor, start the vacuum pump to evacuate to -0.096 MPa, turn off the vacuum pump and open the nitrogen valve to purge nitrogen until the pressure inside the reactor reaches atmospheric pressure. Replace the nitrogen twice, start stirring, and control the stirring speed at 300 rpm. Start heating and turn on the condenser system to circulate water.

[0036] S2: Heat to 150℃, maintain at normal pressure for 3 hours, heat to 180℃, open the alcohol recovery pipeline, adjust the valve to allow the alcohol recovery to slowly flow back into the reactor, heat to 188℃, add 0.093 kg of tetrabutyl titanate through the catalyst feeding pipeline, continue to heat to 227℃, maintain a positive pressure of 0.1 MPa, react at a constant temperature, and take samples every 0.5 hours. The reaction is terminated when the acid value reaches 0.06 mg KOH / g.

[0037] S3: After cooling to 87℃, add 4.38 kg of 31% NaOH solution and 2.51 kg of distilled water. After the alkali and distilled water are replenished, stir for 30 min and let stand for 35 min. The water layer and ester layer will be fully separated. Discard the lower water phase and then drain the water. Vacuum evaporate and dehydrate at 95℃ and -0.096 MPa. When the acid value is 0.06 mg KOH / g and the alcohol content is 450 ppm, the dehydration and purification is completed, and di(2-propylheptane) sebacate is obtained. It is a colorless and transparent liquid with a yield of 95.3% and a viscosity (25℃) of 42 mPa·s.

[0038] Example 3

[0039] A method for preparing di(2-propylheptyl) sebacate, comprising the following preparation steps:

[0040] S1: Add 10.0 kg of sebacic acid and 23.0 kg of 2-propylheptanol to the reactor in sequence, close the reactor, start the vacuum pump to evacuate to -0.095 MPa, turn off the vacuum pump and open the nitrogen valve to purge nitrogen until the pressure inside the reactor reaches atmospheric pressure. Replace the nitrogen three times, start stirring, and control the stirring speed at 320 rpm. Start heating and turn on the condenser system to circulate water.

[0041] S2: Heat to 160℃, maintain at ambient pressure for 3.5h, heat to 185℃, open the alcohol recovery pipeline, adjust the valve to allow the alcohol recovery to slowly flow back into the reactor, heat to 190℃, add 0.144kg of tetrabutyl titanate through the catalyst feeding pipeline, continue to heat to 228℃, maintain a positive pressure of 0.15MPa, react at a constant temperature, and take samples every 0.5h. The reaction is terminated when the acid value reaches 0.07mg KOH / g.

[0042] S3: After cooling to 90℃, add 3.72 kg of 32% NaOH solution and 2.86 kg of distilled water. After the alkali and distilled water are replenished, stir for 40 min and let stand for 40 min. The water layer and ester layer will be fully separated. Discard the lower water phase and then drain the water. Vacuum evaporate and dehydrate at 100℃ and -0.095 MPa. When the acid value is 0.06 mg KOH / g and the alcohol content is 480 ppm, the dehydration and purification is completed, and di(2-propylheptane) sebacate is obtained. It is a colorless and transparent liquid with a yield of 94.8% and a viscosity (25℃) of 43 mPa·s.

[0043] Comparative Example 1

[0044] Compared with Example 1, this comparative example replaces "tetrabutyl titanate" with the same molar amount of "98% concentrated sulfuric acid". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is di(2-propylheptyl) sebacate, a pale yellow liquid with an acid value of 0.25 mg KOH / g, an alcohol content of 1202 ppm, and a yield of 84.5%.

[0045] Comparative Example 2

[0046] Compared with Example 1, this comparative example replaces "2-propylheptanol" with the same molar amount of "2-ethylhexanol". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is di(2-propylheptan) sebacate, a pale yellow liquid with an acid value of 0.08 mg KOH / g, an alcohol content of 2313 ppm, and a yield of 95.0%.

[0047] Comparative Example 3

[0048] Compared with Example 1, this comparative example directly reacted with catalyst at 220°C for 4 hours without stepwise heating or alcohol reflux. All other steps and parameters were the same, and will not be repeated here. The final product was di(2-propylheptane) sebacate, a pale yellow liquid with an acid value of 0.35 mg KOH / g, an alcohol content of 6200 ppm, and a yield of 79.6%.

[0049] Application Example 1

[0050] S1: Add 100g of PVC resin, 50g of di(2-propylheptyl) sebacate prepared in Example 1, 2g of calcium-zinc stabilizer, and 0.5g of stearic acid to a high-speed mixer; mix at 800rpm for 5min until the powder is uniform; feed the premix into a two-roll mill, roll temperature 170℃, adjust the roll gap to 1.0mm, and repeatedly turn the material for 10min until a uniform transparent sheet is formed; for the last 3min, adjust the roll gap to 2.0mm to expel the sheet, take 15g of the sheet and put it into a mold (150×150×2mm); preheat the flat vulcanizing machine to 180℃, pre-press 1MPa / 1min, press 10MPa / 5min, hold the pressure and cool to 60℃ to demold and obtain the PVC sheet.

[0051] Application Example 2

[0052] S1: Add 100g of PVC resin, 50g of di(2-propylheptyl) sebacate prepared in Example 2, 2g of calcium-zinc stabilizer, and 0.5g of stearic acid to a high-speed mixer; mix at 800rpm for 5min until the powder is uniform; feed the premix into a two-roll mill, roll temperature 170℃, adjust the roll gap to 1.0mm, and repeatedly turn the material for 10min until a uniform transparent sheet is formed; for the last 3min, adjust the roll gap to 2.0mm to expel the sheet, take 15g of the sheet and put it into a mold (150×150×2mm); preheat the flat vulcanizing machine to 180℃, pre-press 1MPa / 1min, press 10MPa / 5min, hold the pressure and cool to 60℃ to demold to obtain a PVC sheet.

[0053] Application Example 3

[0054] S1: Add 100g of PVC resin, 50g of di(2-propylheptyl) sebacate prepared in Example 3, 2g of calcium-zinc stabilizer, and 0.5g of stearic acid to a high-speed mixer; mix at 800rpm for 5min until the powder is uniform; feed the premix into a two-roll mill, roll temperature 170℃, adjust the roll gap to 1.0mm, and repeatedly turn the material for 10min until a uniform transparent sheet is formed; for the last 3min, adjust the roll gap to 2.0mm to expel the sheet, take 15g of the sheet and put it into a mold (150×150×2mm); preheat the flat vulcanizing machine to 180℃, pre-press 1MPa / 1min, press 10MPa / 5min, hold the pressure and cool to 60℃ to demold to obtain a PVC sheet.

[0055] Application Example 4

[0056] S1: Add 100g of PVC resin, 50g of di(2-propylheptyl) sebacate prepared in Comparative Example 1, 2g of calcium-zinc stabilizer, and 0.5g of stearic acid to a high-speed mixer; mix at 800rpm for 5min until the powder is uniform; feed the premix into a two-roll mill, roll temperature 170℃, adjust the roll gap to 1.0mm, and repeatedly turn the material for 10min until a uniform transparent sheet is formed; for the last 3min, adjust the roll gap to 2.0mm to expel the sheet, take 15g of the sheet and put it into a mold (150×150×2mm); preheat the flat vulcanizing machine to 180℃, pre-press 1MPa / 1min, press 10MPa / 5min, hold the pressure and cool to 60℃ to demold to obtain a PVC sheet.

[0057] Application Example 5

[0058] S1: Add 100g of PVC resin, 50g of di(2-propylheptyl) sebacate prepared in Comparative Example 2, 2g of calcium-zinc stabilizer, and 0.5g of stearic acid to a high-speed mixer; mix at 800rpm for 5min until the powder is uniform. Feed the premix into a two-roll mill, roll temperature 170℃, adjust the roll gap to 1.0mm, and repeatedly turn the material for 10min until a uniform transparent sheet is formed; for the last 3min, adjust the roll gap to 2.0mm to expel the sheet, take 15g of the sheet and put it into a mold (150×150×2mm); preheat the flat vulcanizing machine to 180℃, pre-press 1MPa / 1min, press 10MPa / 5min, hold the pressure and cool to 60℃ to demold to obtain a PVC sheet.

[0059] Application Example 6

[0060] S1: Add 100g of PVC resin, 50g of di(2-propylheptyl) sebacate prepared in Comparative Example 3, 2g of calcium-zinc stabilizer, and 0.5g of stearic acid to a high-speed mixer; mix at 800rpm for 5min until the powder is uniform; feed the premix into a two-roll mill, roll temperature 170℃, adjust the roll gap to 1.0mm, and repeatedly turn the material for 10min until a uniform transparent sheet is formed; for the last 3min, adjust the roll gap to 2.0mm to expel the sheet, take 15g of the sheet and put it into a mold (150×150×2mm); preheat the flat vulcanizing machine to 180℃, pre-press 1MPa / 1min, press 10MPa / 5min, hold the pressure and cool to 60℃ to demold to obtain a PVC sheet.

[0061] The PVC samples prepared using Examples 1-6 were tested using the following methods:

[0062] 1. Volatilization loss: Determine the percentage of mass loss according to GB / T1671-2008, 100℃×24h.

[0063] 2. Migration loss: According to GB / T33318-2016, the sample was bonded to an ABS board and the mass percentage of plasticizer that migrated to the ABS board was determined at 70℃ for 24 hours.

[0064] 3. Embrittlement temperature: The low-temperature embrittlement temperature shall be determined in accordance with GB / T5470-2008.

[0065] 4. Tensile strength and elongation at break: in accordance with GB / T1040.3-2006, tensile speed 50 mm / min.

[0066] 5. Thermal aging performance: After aging in a 70℃ oven for 168 hours, the elongation at break retention rate was tested.

[0067] Table 1: Test Results

[0068]

[0069] According to the data in Table 1, the di(2-propylheptyl) sebacate plasticizer of the present invention (Examples 1-3) is significantly superior to the comparative examples in terms of volatility loss, migration loss, and heat aging resistance. In particular, compared with Comparative Example 2 (conventional DOS), while maintaining similar cold resistance (embrittlement temperature above -55°C), the migration loss is reduced by more than 75%. The product of Comparative Example 1 (concentrated sulfuric acid method) has poor performance, and the product of Comparative Example 3 (one-step method) has the worst performance due to insufficient reaction, resulting in more residual acid and alcohol in the product.

[0070] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing di(2-propylheptyl) sebacate, characterized in that, The preparation steps include the following: S1: Sebacic acid and 2-propylheptanol are added to the reactor in sequence, the reactor is closed, the vacuum pump is started to evacuate the reactor until the target vacuum level is reached, the vacuum pump is turned off and the nitrogen valve is opened to purge nitrogen until the pressure inside the reactor reaches atmospheric pressure, the stirring is started and the stirring speed is controlled at 280-320 rpm, heating is started and the condenser system circulating water is turned on. S2: Heat to 140℃-160℃, maintain the temperature at normal pressure for 2.5h-3.5h, heat to 176℃-185℃, open the alcohol recovery pipeline, adjust the valve to allow the alcohol recovery to flow back into the reactor, heat to 186℃-190℃, add the catalyst through the catalyst feeding pipeline, continue to heat to 225-228℃, maintain positive pressure and constant temperature reaction, and take samples for analysis at regular intervals. The reaction is terminated when the acid value is ≤0.1mg KOH / g. S3: After cooling to 85℃-90℃, add liquid alkali and distilled water. After the liquid alkali and distilled water are replenished, stir for 20-40 minutes and let stand for 30-40 minutes. The water layer and ester layer will be fully separated. Discard the lower water phase and then drain the water. The residual water is then dehydrated by vacuum evaporation. When the acid value is ≤0.07mg KOH / g and the alcohol content is ≤500ppm, the dehydration and purification are completed, and di(2-propylheptane) sebacate is obtained.

2. The method for preparing di(2-propylheptyl) sebacate according to claim 1, characterized in that, The target vacuum level in S1 is -0.095MPa to -0.098MPa, and nitrogen purging is repeated 2-3 times.

3. The method for preparing di(2-propylheptyl) sebacate according to claim 1, characterized in that, The mass ratio of sebacic acid and 2-propylheptanol in S1 is 1:1.9-2.

3.

4. The method for preparing di(2-propylheptyl) sebacate according to claim 1, characterized in that, The catalyst in S2 is tetrabutyl titanate, and the amount added is 0.1%-0.3% of the total feed mass.

5. The method for preparing di(2-propylheptyl) sebacate according to claim 1, characterized in that, The positive pressure reaction pressure in S2 is 0.05MPa-0.15MPa.

6. The method for preparing di(2-propylheptyl) sebacate according to claim 1, characterized in that, The liquid alkali in S3 is a NaOH solution with a volume fraction of 30%-32%, and the amount of liquid alkali added is: The amount of distilled water added is 9%-12%.

7. The method for preparing di(2-propylheptyl) sebacate according to claim 1, characterized in that, The vacuum evaporation and dehydration conditions in step S3 are: temperature 90℃-100℃, vacuum degree ≤-0.095MPa.

8. A di(2-propylheptyl) sebacate, characterized in that, It is prepared by any of the preparation methods of di(2-propylheptyl) sebacate according to claims 1-7, and satisfies the following conditions: acid value ≤ 0.07 mg KOH / g, alcohol content ≤ 500 ppm, and 2-propylheptyl is a C10 branched alkyl group.

9. The application of di(2-propylheptyl) sebacate as described in claim 8, characterized in that, The di(2-propylheptane) sebacate is used as a plasticizer in polyvinyl chloride products.

10. The application of di(2-propylheptyl) sebacate according to claim 9, characterized in that, The amount of di(2-propylheptane) sebacate added to the PVC formulation is 30-70 phr.

Images