Aconitic acid-based polyester plasticizer and preparation method thereof

Abstract

The invention discloses an aconitic acid-based polyester plasticizer and a preparation method thereof, and relates to the technical field of plasticizer composite materials, the molecular structure of the plasticizer is as follows: # imgabs0 #, R1 and R2 are independently selected from alkyl groups containing 1-4 carbon atoms, and the number n of structural units is 1-20. The aconitic acid-based polyester plasticizer provided by the technical scheme of the invention avoids the cross-linking phenomenon in the process of preparing a polyester material from tricarboxylic acid, so that the aconitic acid-based polyester plasticizer has good flowability and plastification performance when plastifying a plastic matrix, meanwhile, the reaction raw materials are derived from biomass, the preparation process conditions are mild, the equipment requirement is low, and the yield is high.

Description

Technical Field

[0001] The present application relates to an aconitic acid-based polyester plasticizer and a preparation method thereof, and belongs to the technical field of plasticizer composite materials. Background Art

[0002] Plasticizer is a substance that can be added to polymer materials to improve the processability and plasticity of the materials. It is one of the most widely used and largest amount of polymer material additives. It is widely used in plastic products in construction, medical treatment, electronics, toys, etc.

[0003] The development of bio-based materials and auxiliary agents has become an effective way to replace traditional toxic petroleum-based products, especially in the plasticizer industry. Bio-based plasticizers not only have the characteristics of non-toxic and environmentally friendly, but their raw materials are derived from biomass, which reduces the dependence on oil and accelerates the cycle of carbon cycle. Therefore, several bio-based environmentally friendly plasticizers such as citrate esters and epoxy vegetable oil esters are developed one after another, but the molecular weight of most plasticizers is relatively small, and it is easy to migrate from the matrix material to the outside world, and the use of materials cannot be long-term and stable. Therefore, a kind of bio-based and plasticizer with a certain molecular weight is developed to become an urgent demand of the polar plastic industry. Chinese patent CN112126070B discloses a hyperbranched polymerized glyceride bio-based plasticizer and its preparation method and application, with bio-based glycerol as raw material, through the preparation of polymerized glycerol, the preparation of hyperbranched polymerized glycerol and the preparation reaction of hyperbranched polymerized glyceride, a hyperbranched polymerized glyceride plasticizer is obtained. But the plasticizer provided by the invention is a branched cross-linked molecular structure, poor fluidity in the composite with the material, and it is difficult to achieve the effect of efficient plasticization. In addition, Chinese patent CN113801484B discloses a low-odor, non-toxic, non-benzene environmentally friendly composite plasticizer, which achieves the integrated effect of plasticization and stabilization by adding winterized epoxy oil and epoxy fatty acid methyl ester to the plasticizer system, and the composite oxidant and deodorizer, thereby improving the application value. However, the composite plasticizers are all small molecules and still have a certain degree of outward migration.

[0004] Therefore, the difficulty in balancing plasticizing performance and safety performance is one of the main pain points in the bio-based plasticizer market. How to reduce the external migration of plasticizers while ensuring the biocarbon content and efficient plasticization is an issue that needs to be solved urgently. Summary of the invention

[0005] To solve the above problems, the present application provides an aconitic acid-based polyester plasticizer and a preparation method thereof. The plasticizer is prepared by a two-step method of cyclization and esterification. The polar ester group and carbonyl part in the structure provide it with good compatibility with polar materials. The linear structure gives it good molecular mobility. At the same time, the higher molecular weight makes it different from traditional small molecule plasticizers, making it more difficult to migrate to the outside world, effectively improving the biocarbon content of the plasticizer and the long-term stability.

[0006] One of the purposes of the present application is to provide an aconitic acid-based polyester plasticizer, the molecular structure of the plasticizer is as follows:

[0007]

[0008] Wherein, R1 and R2 are independently selected from alkyl groups containing 1 to 4 carbon atoms, and the number of structural units n is 1 to 20.

[0009] Preferably, R1 is an alkyl group with 1 to 3 carbon atoms, R2 is an alkyl group with 2 to 4 carbon atoms, and the number of structural units n is 5 to 10.

[0010] Optionally, the plasticizer has a number average molecular weight range of 300 to 3000 g / mol and a molecular weight distribution of 1 to 2.

[0011] Preferably, the number average molecular weight of the plasticizer is in the range of 500 to 2000 g / mol, more preferably 1000 g / mol.

[0012] The molecular weight of the plasticizer is an important factor in balancing the plasticizing efficiency and stability. When the plasticizer is a small molecule, the friction between the molecular chain of the matrix material is small and the molecular mobility is strong. As long as the compatibility with the matrix material is good, it can effectively plasticize. However, the strong mobility of small molecules makes it easier to migrate from the material to the outside, resulting in the inability to use the material stably for a long time. When the plasticizer is a long-chain macromolecule, the friction between the molecular chain of the matrix material is large and the molecular mobility decreases. Although it can maintain good stability, the agglomeration of the plasticizer macromolecules and the "phase separation" with the matrix material are likely to lead to poor plasticizing effect of the material. According to previous experience with polyester plasticizers, when the number average molecular weight of the plasticizer is between 300 and 3000 g / mol, the plasticizer molecules can not only evenly disperse and effectively plasticize the matrix material, but also maintain good migration resistance.

[0013] The second object of the present application is to provide a method for preparing an aconitic acid-based polyester plasticizer, wherein the process for preparing the plasticizer comprises a cyclization step and an esterification step;

[0014] The cyclization reaction steps are as follows:

[0015] (1) Mix and stir 1 equivalent of aconitic acid and 1 equivalent of amino acid according to the equivalent ratio;

[0016] (2) After adding the above raw materials, the reaction temperature is raised to 150° C. and stirred during the heating process until the two materials are melted;

[0017] (3) After the reaction temperature rises to 150°C, melt stirring is performed for 4 to 5 hours;

[0018] (4) After the reaction, vacuum was applied at 150°C and 0.05 mbar for 5 h to remove all the water generated by the reaction;

[0019] (5) Cooling to room temperature to obtain a cyclic dicarboxylic acid product.

[0020] The cyclization process is a step in preparing polyester plasticizer precursors, and its purity has a great influence on the subsequent esterification step. The inventors found that when the equivalent of aconitic acid and amino acid is 1:1, the purity deviation caused by excessive amount of a certain raw material can be effectively avoided. At the same time, the cyclization reaction is carried out at 150°C, which is a relatively high cyclization temperature, which can ensure that aconitic acid and amino acids react fully. The reaction temperature, reaction time, feed equivalent and other conditions involved in the cyclization reaction are all selected to ensure the stable development of the next step of esterification. Random adjustment can easily lead to poor subsequent esterification reaction or reduced purity and performance of the final product.

[0021] The esterification reaction steps are as follows:

[0022] (1) mixing a cyclic dicarboxylic acid, a diol and a catalyst, wherein the molar ratio of acid to alcohol is 1:(1-1.5) and the amount of the catalyst is 0.1-1 mol%;

[0023] (2) prepolymerization is carried out at a reaction temperature of 150-180° C. for 2 to 4 hours;

[0024] (3) carrying out polycondensation at a reaction temperature of 180-250° C. for 1 to 4 hours;

[0025] (4) then adding acetic acid to perform end-capping at a reaction temperature of 140-180° C. for 2-4 hours;

[0026] (5) After the reaction is completed, the mixture is cooled to room temperature to obtain the final product.

[0027] The esterification process is intended to dehydrate and condense cyclic dicarboxylic acid and diol, and is an important step in controlling the molecular weight of the final product. Therefore, its temperature and polymerization time must be within the above conditions to achieve a molecular weight range of 300-3000 g / mol. When the reaction conditions exceed the range, although the esterification product can still be obtained, its molecular weight and product purity are difficult to guarantee, which has a great impact on the final plasticizing performance and migration resistance. Therefore, in order to keep the molecular weight within this range, the prepolymerization and polycondensation time are shorter than the melt polycondensation time of general materials.

[0028] Optionally, in the cyclization reaction step, the amino acids include one or more of glycine, β-alanine, and γ-aminobutyric acid.

[0029] Preferably, the amino acids include one or more of glycine and β-alanine.

[0030] The raw materials involved in the cyclization reaction are aconitic acid and amino acids, both of which are extracted from biological fermentation or biomass and are green and environmentally friendly bio-based raw materials. The cyclic dicarboxylic acid after the cyclization is used as the main structure of the plasticizer. In addition to giving the plasticizer the function of green and environmentally friendly high biocarbon content, its own polarity is also further enhanced. When aconitic acid is used as the main structure, it only has three polar ester groups, while the cyclic dicarboxylic acid has two polar ester groups and two polar carbonyl groups at the same time. The higher polarity gives it better compatibility with polar materials and higher plasticization efficiency.

[0031] Optionally, the diol is one or more of ethylene glycol, 1,3-propylene glycol, and 1,4-butanediol.

[0032] This type of diol can be obtained through biological fermentation and is a green and environmentally friendly bio-based raw material. At the same time, the inventors found that the above diols are all straight-chain structures. In the final polyester plasticizer structure, the straight-chain structure of the diol effectively reduces the steric hindrance of the molecular chain side group, so that the polyester plasticizer has good mobility and provides a "lubricating" function between the main materials, further improving the plasticization of the material. Good chain mobility and compatibility jointly improve the plasticization efficiency of the plasticizer. The two are not simply added, but a synergistic effect.

[0033] Optionally, the catalyst is one or more of zinc acetate, antimony trioxide, p-toluenesulfonic acid, concentrated sulfuric acid, stannous octoate, disodium hydrogen phosphate, potassium carbonate, and tetrabutyl titanate.

[0034] Optionally, in the esterification reaction step, the end-capping agent includes one or more of acetic acid and acetic anhydride.

[0035] Preferably, the capping agent is acetic acid.

[0036] The inventors found that by deliberately increasing the equivalent of the diol in the esterification step, the polyester molecules can be capped with the diol and the molecular weight can be controlled not to increase further. At the same time, the introduction of acetic acid for the final capping can further introduce polar carbonyl groups into the molecular structure. If alcohols are used for capping, the polarity will not be significantly improved. The increase in polarity can better promote the compatibility of polyester with the matrix material. This capping link is a unique design based on the application direction of the polyester material (plasticizer).

[0037] All raw materials of the aconitic acid-based polyester plasticizer except the catalyst are derived from biomass, and the biocarbon content of the plasticizer product finally prepared is 100%.

[0038] Biochar content is gradually guiding the direction of material development. The biochar content in the product includes the sum of the biochar of the base and the additive. The aconitic acid-based polyester plasticizer in this application has 100% biochar, which reduces the biochar content pressure of the main material.

[0039] The third purpose of the present application is to provide an application of aconitate ester, wherein the aconitate-based polyester has good compatibility with polar materials such as PVC, PLA, nitrile rubber, chloroprene rubber, etc., and can be used as a plasticizer thereof.

[0040] Optionally, the plasticizer can effectively reduce the glass transition temperature (T g ), hardness and difficult to migrate out of the material.

[0041] The fourth object of the present application is to provide a method for preparing the aconitic acid-based polyester plasticized polar material described in any one of the above items, comprising the following steps:

[0042] S1: mixing the base material, the aconitic acid-based polyester plasticizer, and the additive to obtain a premix;

[0043] S2: adding the premix to a mixer or a screw extruder for mixing to obtain a mixed material or mixed pellets;

[0044] S3: placing the mixed material or mixed pellets in a vulcanizer for molding.

[0045] The beneficial effects of this application include but are not limited to:

[0046] 1. The aconitic acid-based polyester plasticizer of the present application has strong structural adjustability. The ratio of linear alkyl groups to polar groups can be adjusted through amino acids and diols. The adjustable polarity can meet the plasticization requirements of most polar materials.

[0047] 2. The raw materials of the aconitic acid-based polyester plasticizer of the present application are all from biomass, obtained through synthetic biology technology, and are non-toxic and environmentally friendly. At the same time, its biocarbon content is 100%.

[0048] 3. The aconitic acid-based polyester plasticizer of the present application is an oligoester. Compared with traditional small molecule plasticizers, the long chain increases the intermolecular friction and has the property of migration resistance; compared with ordinary linear polyester plasticizers, the structural rigidity after ring formation can effectively reduce the interaction between the molecular chains of the main material and improve the plasticizing effect; compared with branched polyester plasticizers, the linear structure has stronger mobility, which prevents the plasticizing performance from decreasing due to plasticizer agglomeration.

[0049] 4. During the preparation process of the aconitic acid-based polyester plasticizer of the present application, the experimental conditions are adjusted according to the target structure, and through the targeted design of conditions such as reaction temperature, reaction time, and feed equivalent, a high-purity polyester plasticizer product is finally obtained. DETAILED DESCRIPTION

[0050] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0051] The raw materials in the examples of this application are all prepared by synthetic biology technology.

[0052] Example 1

[0053] This embodiment provides an aconitic acid-based polyester plasticizer, the structure of which is as follows:

[0054]

[0055] The number average molecular weight was determined by gel permeation chromatography to be 1300 g / mol.

[0056] The preparation method comprises the following steps:

[0057] (1) According to the equivalent ratio, 1 equivalent of aconitic acid and 1 equivalent of amino acid are mixed and stirred in a reactor, and then the reaction temperature is raised to 150° C. and melt-stirred for 4 hours. After the reaction is completed, vacuum is drawn at 150° C. and a vacuum degree of 0.05 mbar for 5 hours to remove all the water generated by the reaction. The mixture is cooled to room temperature to obtain a cyclic dicarboxylic acid product.

[0058] (2) Mix cyclic dicarboxylic acid, diol and tetrabutyl titanate, with the acid-alcohol molar ratio of 1:1.1 and the amount of tetrabutyl titanate being 0.1 mol%; carry out prepolymerization at a reaction temperature of 150°C for 2 hours, and then carry out condensation polymerization at a reaction temperature of 180°C for 1 hour; then add acetic acid for end-capping at a reaction temperature of 180°C for 2 hours; after the reaction is completed, cool to room temperature to obtain the final product.

[0059] Wherein, the amino acid in step (1) is glycine, the diol in step (2) is ethylene glycol,

[0060] Example 2

[0061] The difference between this embodiment and embodiment 1 is that the amino acid in step (1) is β-alanine, the diol in step (2) is 1,3-propylene glycol, and the remaining experimental conditions and steps are the same as those in embodiment 1. The structure of aconitic acid polylactic acid ester prepared in this embodiment is as follows:

[0062]

[0063] The number average molecular weight was determined by gel permeation chromatography to be 1500 g / mol.

[0064] Example 3

[0065] The difference between this embodiment and embodiment 1 is that the amino acid in step (1) is γ-aminobutyric acid, the diol in step (2) is 1,4-butanediol, and the remaining experimental conditions and steps are the same as those in embodiment 1. The structure of aconitic acid polylactic acid ester prepared in this embodiment is as follows:

[0066]

[0067] The number average molecular weight was determined by gel permeation chromatography to be 2100 g / mol.

[0068] Example 4

[0069] The difference between this embodiment and embodiment 1 is that the amino acid in step (1) is glycine, the diol in step (2) is 1,3-propylene glycol, the acid-alcohol molar ratio in the esterification step is 1:1, and the other experimental conditions and steps are the same as those in embodiment 1. The structure of aconitic acid polylactic acid ester prepared in this embodiment is as follows:

[0070]

[0071] The number average molecular weight was determined by gel permeation chromatography to be 3000 g / mol.

[0072] Example 5

[0073] The difference between this embodiment and embodiment 1 is that the amino acid in step (1) is glycine, the diol in step (2) is 1,4-butanediol, and the acid-alcohol molar ratio in the esterification step is 1:1.5. The remaining experimental conditions and steps are the same as those in embodiment 1. The structure of aconitic acid polylactic acid ester prepared in this embodiment is as follows:

[0074]

[0075] The number average molecular weight was determined by gel permeation chromatography to be 300 g / mol.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 1 is that the molar ratio of acid to alcohol in the esterification step is 1:2. The other experimental conditions and steps are the same as those in Example 1. The structure of aconitic acid polylactic acid ester prepared in this example is as follows:

[0078]

[0079] The number average molecular weight was determined by gel permeation chromatography to be 30,000 g / mol.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the acid-alcohol molar ratio is 1.5:1, the end-capping agent is ethanol, and the remaining experimental conditions and steps are the same as those in Example 1. The structure of the aconitic acid polylactic acid ester prepared in this example is as follows:

[0082]

[0083] The number average molecular weight was determined by gel permeation chromatography to be 1300 g / mol.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 1 is that the amino acid is valine containing a side group, and the other experimental conditions and steps are the same as those of Example 1. The structure of aconitic acid polylactic acid ester prepared in this example is as follows:

[0086]

[0087] The number average molecular weight was determined by gel permeation chromatography to be 1300 g / mol.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 1 is that the cyclization reaction temperature is 130° C., and the other experimental conditions and steps are the same as those in Example 1. The structure of aconitic acid polylactic acid ester prepared in this example is as follows:

[0090]

[0091] The number average molecular weight was determined by gel permeation chromatography to be 1300 g / mol.

[0092] Comparative Example 5

[0093] The difference between this comparative example and Example 1 is that the cyclization reaction temperature is 170° C., and the other experimental conditions and steps are the same as those in Example 1. The structure of aconitic acid polylactic acid ester prepared in this example is as follows:

[0094]

[0095] The number average molecular weight was determined by gel permeation chromatography to be 1300 g / mol.

[0096] Comparative Example 6

[0097] The difference between this comparative example and Example 1 is that the prepolymerization temperature in the esterification reaction is 120° C. and the polycondensation temperature is 150° C., and the other experimental conditions and steps are the same as those in Example 1. The structure of the aconitic acid polylactic acid ester prepared in this example is as follows:

[0098]

[0099] The number average molecular weight was determined by gel permeation chromatography to be 1100 g / mol.

[0100] Comparative Example 7

[0101] The difference between this comparative example and Example 1 is that the prepolymerization temperature in the esterification reaction is 200° C. and the polycondensation temperature is 270° C. The other experimental conditions and steps are the same as those in Example 1. The structure of the aconitic acid polylactic acid ester prepared in this example is as follows:

[0102]

[0103] The number average molecular weight was determined by gel permeation chromatography to be 1700 g / mol.

[0104] Test Example 1

[0105] The purity, chromaticity, yield and triester conversion rate of the aconitic acid-based polyester plasticizer prepared in the above examples and the comparative examples were tested. The specific test results are shown in Table 1 below. The test method is as follows:

[0106] 1. Molecular weight test: Prepare samples and test according to GB / T 27843 "Gel Permeation Chromatography (GPC) for Determination of Low Molecular Weight Component Content in Polymers".

[0107] 2. Purity: Use high performance liquid chromatography, and the instrument sensitivity and stability of the detector should comply with the provisions of GB / T16631-2008. Chromatographic column: C18 column; Injector: 10μL micro-syringe; Solvent: acetonitrile (HPLC grade); Collection time: 15min; Mobile phase: 80% acetonitrile (HPLC grade), 20% deionized water; Injection volume: 1μL; Wavelength: 230nm.

[0108] Test: Adjust the instrument as specified above. After the baseline is stable, inject 0.2 μL of sample with a microsyringe. Simultaneously start the integrator or chromatography workstation. The instrument will automatically give the area percentage of each component.

[0109] Purity calculation formula: Purity = (integral area of ​​aconitic acid polylactic acid ester / total integrated area) × 100%.

[0110] 3. Chroma: According to GB / T 1664-1995 "Determination of Appearance Chroma of Plasticizers", prepare solutions of different standard colors and compare them with the samples in colorimetric tubes.

[0111] 4. Yield: The efficiency of the reaction synthesis route is characterized by the yield, and the yield calculation formula is: Yield = (mass of the final product obtained / theoretical mass of aconitic acid polylactic acid ester) × 100%.

[0112] Table 1

[0113] Sample No. Molecular weight (g / mol) purity(%) Chromaticity(Pt-Co) Yield (%) Example 1 1300 99.3 25 97.8 Example 2 1500 99.5 25 98.1 Example 3 2100 99.2 25 98.3 Example 4 3000 99.7 25 97.7 Example 5 300 99.3 25 98.6 Comparative Example 1 30000 92.4 140 89.5 Comparative Example 2 1300 99.1 30 96.6 Comparative Example 3 1300 99.0 30 88.6 Comparative Example 4 1300 79.7 50 75.1 Comparative Example 5 1300 74.2 260 69.3 Comparative Example 6 1100 86.7 40 83.2 Comparative Example 7 1700 87.4 430 83.5

[0114] According to the contents of Table 1, by adjusting the acid-alcohol ratio, the esterification reaction temperature, and the structure of the amino acid and the diol, the number average molecular weight of the aconitic acid-based polyester plasticizer can be effectively controlled within 300-3000 g / mol. Within this range, the plasticizer can effectively take into account both plasticizing performance and stability performance. At the same time, according to the comparative examples, after exceeding the reaction conditions protected by the present application, there will be problems such as increased molecular weight, darker product color, reduced product purity and yield. In addition to reducing the quality and production efficiency of the product, the above phenomenon will also have an adverse effect on the subsequent use of the product.

[0115] The aconitic acid-based polyester prepared in the above examples and comparative examples was added as a plasticizer to the polar material, wherein the formula for preparing PVC plastic included 100 parts of PVC resin, 35 parts of plasticizer, and 2 parts of heat stabilizer, and the formula for preparing PLA plastic included 100 parts of PLA resin and 20 parts of plasticizer.

[0116] The formula for preparing chloroprene rubber includes 100 parts of chloroprene rubber, 15 parts of plasticizer, 5 parts of zinc oxide, 4 parts of magnesium oxide and 0.5 parts of stearic acid, and is processed according to GBT 21462-2008 standard.

[0117] The processing method is as follows

[0118] S1: Mixing the raw materials to obtain a premix;

[0119] S2: adding the premix into a mixer and mixing to obtain a mixed material;

[0120] S3: placing the mixed material in a flat vulcanizing machine for molding.

[0121] Application Examples 1 to 5:

[0122] Application Examples 1 to 5 are prepared using the above PVC formulation and processing method. The difference between the application examples is that the plasticizers used correspond to the products in Examples 1 to 5, respectively, and the other components and preparation methods are the same.

[0123] Application Example 6:

[0124] In this application example, the above PLA formula and processing method are used for preparation, and the plasticizer used corresponds to the product in Example 1.

[0125] Application Example 7:

[0126] This application example is prepared using the above-mentioned chloroprene rubber formula and processing method, and the plasticizer used corresponds to the product in Example 1.

[0127] Application Comparative Examples 1 to 7

[0128] The difference between application comparative examples 1 to 7 and application example 1 is that the plasticizers used correspond to the products in comparative examples 1 to 7 respectively, and the other components and preparation methods are the same.

[0129] Application Comparative Example 8

[0130] The difference between this comparative application example and application example 1 is that the plasticizer used is dioctyl phthalate (DOP), and the other components and preparation methods are the same.

[0131] Application Comparative Example 9

[0132] The difference between this comparative application example and application example 1 is that the plasticizer used is acetyl tributyl citrate (ATBC), and the other components and preparation methods are the same.

[0133] Application Comparative Example 10

[0134] The difference between this comparative application example and application example 1 is that the plasticizer used is tributyl aconitate (TBA), and the other components and preparation methods are the same.

[0135] Application Comparative Example 11

[0136] The difference between this comparative application example and application example 1 is that the plasticizer used is polybutylene adipate (PBGA) with a number average molecular weight of 1300 g / mol, and the other components and preparation methods are the same.

[0137] Application Comparative Example 12

[0138] The difference between this comparative application example and application example 6 is that the plasticizer used is dioctyl phthalate (DOP), and the other components and preparation methods are the same.

[0139] Application Comparative Example 13

[0140] The difference between this comparative application example and application example 7 is that the plasticizer used is dioctyl phthalate (DOP), and the other components and preparation methods are the same.

[0141] Test Example 2

[0142] The specific test results of the properties of the plasticized composite material are shown in Tables 2 and 3 below, and the test method is as follows:

[0143] 1. Biocarbon content: Samples are made and tested in accordance with GB / T 39715.2-2021 "Plastics Biobased Content Part 2: Determination of Biobased Carbon Content". Each group of samples is tested according to the oxalic acid standard reference substance, and the test time is 4-8 hours.

[0144] 2. Hardness: According to GB / T531-2008 "Indentation hardness test method, Shore hardness tester method" standard, make specimens and test them. Select 3 points for each group of specimens, measure each point once, and take the median value.

[0145] 3.100% tensile stress and elongation at break: in accordance with GB / T1040-2006 "Plastic Tensile Properties Test", the tensile speed is 50mm / min and the temperature is 25℃.

[0146] 4. Glass transition temperature (Tg): The glass transition temperature was tested by a dynamic mechanical analyzer. The test conditions were: nitrogen as the carrier gas, the test temperature range was -40-80°C, the heating rate was 3°C / min, and the frequency was 1 Hz.

[0147] 5. Volatilization loss rate: The test is carried out in accordance with HG / T 4458-2012 "Determination of plasticizer loss in plastics - Activated carbon method", the test temperature is 70°C, and the test time is 24h.

[0148] 6. Water extraction rate: The test is carried out in accordance with the standard "ISO 175-2011 Plastics - Experimental method for determination of the effects of immersion of liquid chemicals". The test temperature is room temperature, the test time is 72h, and the extraction solvent is deionized water.

[0149] 7. Ethanol extraction rate: The test is carried out in accordance with the standard "ISO 175-2011 Plastics - Experimental method for determination of the effects of immersion of liquid chemicals". The test temperature is room temperature, the test time is 72h, and the extraction solvent is ethanol.

[0150] 8.Petroleum ether extraction rate: The test is carried out in accordance with the standard "ISO 175-2011 Plastics - Experimental method for determination of the effects of immersion of liquid chemicals". The test temperature is room temperature, the test time is 72h, and the extraction solvent is petroleum ether.

[0151] 9. Migration rate: The test is conducted in accordance with HG / T 4458-2012 “Determination of Migration of Plasticizers in Plastics”. The test temperature is 50°C, the test time is 48 hours, and the absorbent sheet is made of polyethylene (PE) without additives.

[0152] Table 2

[0153]

[0154] Table 3

[0155]

[0156] The test in Table 2 is mainly used to evaluate the plasticizing performance of the plasticizer. According to its content, the aconitic acid-based polyester plasticizer involved in this application has a biocarbon content of 100% because its raw materials are all from biomass, which is much higher than the traditional petroleum-based plasticizer DOP (0%), bio-based environmentally friendly plasticizer ATBC / TBA (30% / 33%) and other polyester plasticizers PBGA (40%) with equivalent molecular weight. In terms of plasticizing performance, according to the comparison of application examples 1 to 5 and application comparative example 1, it is found that with the increase of the molecular weight of the plasticizer, the plasticizing efficiency decreases slightly with the increase of the molecular weight within 3000g / mol, and with the further increase of the molecular weight, its plasticizing efficiency decreases significantly (hardness, 100% tensile stress and glass transition temperature become higher, and elongation at break becomes lower).

[0157] According to the comparison between Application Comparative Examples 2 to 3 and Application Example 1, it can be found that if the end capping is carried out by hydroxyl group, the number of polar "carbonyl groups" will be reduced, and the plasticizing properties of the material will be reduced; similarly, after the side group is introduced into the amino acid, the flexibility of the alkyl group will be reduced, and the overall mobility of the molecular chain will be reduced, resulting in a decrease in the plasticizing properties of the material. Therefore, the amino acid containing straight-chain alkyl groups and the synthesis method using acetic acid end capping involved in this application can effectively improve the plasticizing efficiency of the material.

[0158] According to the comparison between Application Example 1 and Application Comparative Examples 8 to 11, and Application Examples 6 to 7 and Application Comparative Examples 12 to 13, it is found that, whether in PVC, PLA or chloroprene rubber, the aconitic acid-based polyester plasticizer has a comparable or better plasticizing effect than traditional petroleum-based plasticizers, bio-based environmentally friendly plasticizers and polyester plasticizers with equivalent molecular weight.

[0159] The test in Table 3 is mainly used to evaluate the stability of the plasticizer. According to the application examples 1 to 7 and the application comparison examples 1 to 3, it can be seen that the aconitic acid-based polyester plasticizer has good stability, and when the molecular weight of the plasticizer exceeds 1000 g / mol, it is difficult to migrate to the outside.

[0160] According to the comparison between Application Example 1 and Application Comparative Examples 4 to 7, it was found that in the preparation process of aconitic acid-based polyester, the problem of low product purity due to reaction conditions will greatly affect the stability of the product. The main reason is that most impurities are small molecules that are unreacted or side-reacted, and are very easy to migrate to the outside.

[0161] According to the comparison between Application Example 1 and Application Comparative Examples 8 to 11, and Application Examples 6 to 7 and Application Comparative Examples 12 to 13, it is found that compared with commercial plasticizers, whether in PVC, PLA or chloroprene rubber, aconitic acid-based polyester plasticizers can well balance plasticizing efficiency and stability. Small molecule plasticizers are easy to migrate to the outside, while polyester plasticizers with acyclic structures of equivalent molecular weight are easier to migrate to liquid and solid environments because of their smaller interaction force with the molecular chains of the main material.

[0162] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A polyester plasticizer based on aconitic acid, characterized in that: The molecular structure of the plasticizer is as follows: Wherein, R1 and R2 are independently selected from alkyl groups containing 1 to 4 carbon atoms, and the number of structural units n is 1 to 20.

2. An aconitic acid based polyester plasticizer as claimed in claim 1, characterized in that: The number average molecular weight of the plasticizer ranges from 300 to 3000 g / mol, and the molecular weight distribution is 1 to 2.

3. A method for preparing an aconitic acid-based polyester plasticizer as claimed in any one of claims 1 to 2, characterized in that: The method comprises a cyclization reaction step and an esterification reaction step; The cyclization reaction steps are as follows: (1) Mix and stir 1 equivalent of aconitic acid and 1 equivalent of amino acid according to the equivalent ratio; (2) After adding the above raw materials, the reaction temperature is raised to 150° C. and stirred during the heating process until the two materials are melted; (3) After the reaction temperature rises to 150°C, melt stirring is performed for 4 to 5 hours; (4) After the reaction, vacuum was applied at 150°C and 0.05 mbar for 5 h to remove all the water generated by the reaction; (5) Cooling to room temperature to obtain a cyclic dicarboxylic acid product. The esterification reaction steps are as follows: (1) mixing a cyclic dicarboxylic acid, a diol and a catalyst, wherein the molar ratio of acid to alcohol is 1:(1-1.5) and the amount of the catalyst is 0.1-1 mol%; (2) prepolymerization is carried out at a reaction temperature of 150-180° C. for 2 to 4 hours; (3) carrying out polycondensation at a reaction temperature of 180-250° C. for 1 to 4 hours; (4) then adding a capping agent to perform capping at a reaction temperature of 140-180°C for 2-4 hours; (5) After the reaction is completed, the mixture is cooled to room temperature to obtain a plasticizer product.

4. A method for preparing an aconitic acid-based polyester plasticizer as claimed in claim 3, characterized in that: The amino acids include one or more of glycine, β-alanine, and γ-aminobutyric acid.

5. A method for preparing an aconitic acid-based polyester plasticizer as claimed in claim 3, characterized in that: The diol is one or more of ethylene glycol, 1,3-propylene glycol, and 1,4-butanediol.

6. A method for preparing an aconitic acid-based polyester plasticizer as claimed in claim 3, characterized in that: The end-capping agent is one or more of acetic acid and acetic anhydride.

7. A method for preparing an aconitic acid-based polyester plasticizer as claimed in claim 3, characterized in that: The catalyst is one or more of zinc acetate, antimony trioxide, p-toluenesulfonic acid, concentrated sulfuric acid, stannous octoate, disodium hydrogen phosphate, potassium carbonate, and tetrabutyl titanate.

8. A method for preparing an aconitic acid-based polyester plasticizer as claimed in claim 3, characterized in that: The plasticizer product has a biochar content of 100%.

9. Use of an aconitic acid-based polyester plasticizer as claimed in any one of claims 1 to 2, characterized in that: The invention is applied to the modification of polar materials, wherein the polar materials at least include PVC, PLA, nitrile rubber and chloroprene rubber.

10. A method for preparing an aconitic acid-based polyester plasticized polar material, characterized in that: The steps include: S1: mixing the base material, the aconitic acid-based polyester plasticizer, and the additive to obtain a premix; S2: adding the premix to a mixer or a screw extruder for mixing to obtain a mixed material or mixed pellets; S3: placing the mixed material or mixed granules in a flat vulcanizing machine for molding.

Images