Preparation method of nucleating agent based on coulomb force and application thereof in synthesis of high-crystalline polyester

Abstract

This invention discloses a method for preparing a nucleating agent based on Coulomb interaction. The method includes: S1: dissolving a nitrogen-containing cyclic compound in a solvent to form a homogeneous and stable solution system; S2: reacting the solution system obtained in S1 with a sulfur-containing compound at a constant temperature for 1-72 h, followed by filtration, washing, and drying to obtain an inner salt monomer; S3: under the action of an initiator, free radically polymerizing the inner salt monomer obtained in S2 with various acrylic monomers in a solvent at a molar ratio of 0.5:9.5-5:5 for 1-48 h to obtain a novel nucleating agent based on Coulomb interaction for the synthesis of highly crystalline polyesters. This method offers high yield, low cost, and mild reaction conditions, effectively improving the cooling crystallization temperature, crystallization rate, and mechanical properties of polyesters.

Description

Technical Field

[0001] This invention relates to the field of nucleating agents and polyester synthesis technology, specifically to a method for preparing a nucleating agent based on Coulomb forces and its application in the synthesis of highly crystalline polyesters. Background Technology

[0002] Polyester is a semi-crystalline polymer widely used in the production of synthetic fibers, films, and beverage bottles. However, due to the relatively rigid molecular structure of some polyesters, such as PET (polyethylene terephthalate), the movement of molecular chains is somewhat hindered, resulting in a low intrinsic polymer crystallization rate. In fact, a certain degree of crystallinity is a prerequisite for ensuring good mechanical properties in polyester materials. Therefore, due to its relatively slow crystallization rate and low crystallinity, PET cannot be used on a large scale in some potential applications, such as engineering plastics. The application of polyester materials in these fields is crucial for the healthy and sustainable development of the entire industry.

[0003] Therefore, improving the crystallinity of PET in a simple and efficient way is a scientific issue of great concern to the entire industry. To date, both academia and industry have conducted extensive theoretical research and experimental trials, generally agreeing that adding nucleating agents may be a relatively cost-effective technical route. Based on current research and technological foundations, three main categories of crystallization nucleating agents have been extensively studied. Inorganic and organic nucleating agents mainly promote polyester crystallization through heterogeneous and homogeneous nucleation mechanisms by adding inorganic additives and small molecule additives, respectively, thereby increasing the degree of polyester crystallinity under the same thermal history conditions. However, relatively speaking, the third category of crystallization nucleating agents—polymer nucleating agents—offers the greatest adaptability and performance adjustment margin due to their higher degree of freedom in molecular structure design, wider selection of functional groups, and the ability to vary chemical composition within a large range. Currently commonly used polymer nucleating agents are mainly composed of ionic polymers. The ionic functional groups provide polar interactions, promoting nucleation. Simultaneously, by appropriately increasing the free volume of molecular chains through blending with specific molecular structure designs, the mobility of the molecular chains is enhanced, improving the crystallinity of polyester.

[0004] Generally, when selecting and designing nucleating agents, it is necessary to ensure that they do not melt below the melting point of the polymer and have a similar structure to the polymer to guarantee good compatibility with the polymer matrix. Based on meeting the above conditions, this invention aims to synthesize a novel nucleating agent based on Coulomb forces. This agent can rapidly form crystal nuclei through intramolecular / intermolecular positive and negative charge Coulomb forces, thereby increasing the crystallization rate of polyester. This has significant implications for shortening the molding cycle and improving the mechanical properties of polyester. Summary of the Invention

[0005] In order to solve one or more technical problems existing in the prior art, one of the objectives of this application is to provide a method for preparing nucleating agents based on Coulomb forces, which has high yield, low cost, mild reaction conditions, and can effectively improve the crystallization temperature, crystallization rate and mechanical properties of polyester.

[0006] The second objective of this application is to provide an application of a nucleating agent based on Coulomb forces in the synthesis of highly crystalline polyesters. By changing the molecular structure design and the composition of polymer monomers (the molar ratio of various acrylic monomers), the nucleating promoting ability of the nucleating agent can be controlled, thereby increasing the crystallization rate of the polyester, shortening the molding cycle, and improving the mechanical properties of the polyester.

[0007] To address the aforementioned technical problems, one of the objectives of this application is achieved through the following technical solution:

[0008] A method for preparing a nucleating agent based on Coulomb interaction and its application, the preparation method comprising:

[0009] S1: Dissolve the nitrogen-containing cyclic compound in solvent A to form a homogeneous and stable solution system;

[0010] S2: The solution system obtained in S1 is reacted with a sulfur-containing compound at a constant temperature for 1-72 hours, and then filtered, washed, and dried to obtain an inner salt monomer;

[0011] S3: Under the action of an initiator, the inner salt monomer obtained in S2 is radically polymerized with various acrylic monomers in solvent B at a molar ratio of 0.5:9.5 to 5:5 for 1 to 48 hours to obtain a novel nucleating agent based on Coulomb interaction for the synthesis of highly crystalline polyesters. Specifically, the inner salt monomer, various acrylic monomers, and initiator are first dissolved in solvent B, and then added dropwise to the continuously stirred polymerization reaction substrate for polymerization. The reaction temperature is 10 to 150°C, and the reaction time is 2 to 48 hours.

[0012] Preferably, in step S2, the molar ratio of the solution system to the sulfur-containing compound is 1:1.15 to 1.15:1, the constant temperature is between 10 and 100°C, and the washing step involves washing three times with ethyl acetate.

[0013] Preferably, the solvent reaction temperature in step S3 is 10–150°C, and the reaction time is 2–48 h.

[0014] Preferably, the nitrogen-containing cyclic compound in step S1 is vinylimidazole or a derivative thereof, and the sulfur-containing compound in step S2 is sulfonyl lactone or a derivative thereof.

[0015] Preferably, the sulfonyl lactone is 1,3-propanesulfonyl lactone.

[0016] Preferably, the initiator is an azo initiator or a peroxide initiator, including but not limited to at least one of cyclohexanone peroxide, tert-butyl hydroperoxide, azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), ditert-pentyl peroxide (DTAP), and azobisisoheptanenitrile (DIHHN). The amount of the initiator is 0.2% to 2% of the total mass of the monomer.

[0017] Preferably, the solvent is any one of ethanol, ethylene glycol, acetonitrile, ethyl acetate, dimethyl sulfoxide, butanediol, propylene glycol, butanol, propanol, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; more preferably, it is a polar solvent.

[0018] Preferably, the acrylic monomer is at least one selected from acrylic acid, butenoic acid, 3-methyl-3-butenoic acid, 2-methyl-2-acrylic acid, 3-ethyl-3-butenoic acid, phosphate methacrylate, polyethylene glycol phosphate methacrylate, 2-hydroxyethyl methacrylate phosphate ester, n-butyl acrylate, n-butyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, isobutyl acrylate, cyclohexyl acrylate, lauryl acrylate, styrene, isobornyl methacrylate, acrylonitrile, n-octyl methacrylate, and ethyl acrylate.

[0019] The second objective of this application is achieved through the following technical solution:

[0020] The application of a nucleating agent based on Coulomb forces in the synthesis of highly crystalline polyesters, wherein the nucleating agent is used in the synthesis of highly crystalline polyesters, and the amount of the nucleating agent added accounts for 0.1 wt% to 5 wt% of the total mass of the polyester.

[0021] Preferably, the synthesized highly crystalline polyester is prepared by reacting diols and diacids in the polyester under the action of the nucleating agent. The reaction temperature of the highly crystalline polyester is 220-300°C, the reaction pressure is 30Pa-0.4MPa, and the reaction time is 3.5-10.0h.

[0022] Preferably, the esterification temperature in the esterification reaction is 220–280°C, the esterification pressure is atmospheric pressure to 0.4 MPa, and the esterification time is 1.5–3.0 h; the pre-condensation temperature in the pre-condensation reaction is 260–300°C, the vacuum degree is 30–3000 Pa, and the reaction time is 1.0–3.5 h; and the final condensation temperature in the final condensation reaction is 270–300°C, the vacuum degree is 30–240 Pa, and the reaction time is 1.0–3.5 h.

[0023] Preferably, the diacid is at least one selected from terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, biphenyl dicarboxylic acid, cyclohexanedicarboxylic acid, and succinic acid; the diol is a diol having 2 to 10 carbon atoms, including at least one selected from ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, and cyclohexanediethanol; the molar ratio of the diacid to the diol is 1:1.2 to 2.0.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention promotes crystal nucleus formation through a newly designed positive and negative charge Coulomb interaction force, effectively improving the crystallization nucleation efficiency of polyester even with a small addition amount. Simultaneously, it further optimizes and controls nucleation efficiency and crystallization rate by altering the polymer molecular structure design and monomer molar ratio.

[0026] 2. The internal salt nucleating agent synthesized by this method has virtually no effect on the intrinsic viscosity of polyester after addition, overcoming the trend of traditional organic nucleating agents significantly reducing the intrinsic viscosity of polyester, and improving tensile and bending properties.

[0027] 3. The internal salt nucleating agent synthesized by this method has mild reaction conditions, low toxicity and environmental friendliness, and low price. Compared with traditional nucleating agents, its dispersibility and compatibility are improved. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples, but these should not be construed as limiting the present patent.

[0029] Unless otherwise specified, the experimental and testing methods described in the following examples are conventional methods; the reagents and materials described are obtained from conventional commercial sources or prepared using conventional methods, unless otherwise specified.

[0030] A method for preparing a nucleating agent based on Coulomb interaction, the method comprising:

[0031] S1: Dissolve a nitrogen-containing cyclic compound in solvent A to form a homogeneous and stable solution system, wherein the nitrogen-containing cyclic compound is vinylimidazole or its derivative, and solvent A is any one or a combination of ethanol, ethylene glycol, acetonitrile, ethyl acetate, dimethyl sulfoxide, butanediol, propylene glycol, butanol, propanol, acetone, and N-methylpyrrolidone.

[0032] S2: The solution system obtained in S1 is reacted with the sulfur-containing compound at a constant temperature for 1 to 72 hours and then filtered, washed and dried to obtain the inner salt monomer; the sulfur-containing compound is a sulfonate lactone or its derivative, and the sulfonate lactone is 1,3-propanesulfonate lactone.

[0033] S3: Under the action of an initiator, the inner salt monomer obtained in S2 is subjected to free radical polymerization with various acrylic monomers in solvent B at a molar ratio of 0.5:9.5 to 5:5 for 1 to 24 hours to obtain a novel nucleating agent based on coulombic forces for the synthesis of highly crystalline polyesters; the initiator is an azo initiator or a peroxide initiator, including but not limited to at least one of cyclohexanone peroxide, tert-butyl hydroperoxide, azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), ditert-pentyl peroxide (DTAP), and azobisisoheptanenitrile (DIHeptanenitrile); the amount of the initiator is 0.2% to 2% of the total mass of the monomers.

[0034] In practice, the internal salt monomer, various acrylic monomers, and the initiator are first dissolved in solvent B, and then added dropwise to a continuously stirred polymerization reaction substrate for polymerization. The reaction temperature is 10–150°C, and the reaction time is 2–48 h, yielding a novel nucleating agent based on Coulomb interaction. The reaction temperature is 10–150°C, and the reaction time is 2–48 h. Solvent B is any one of ethanol, ethylene glycol, acetonitrile, ethyl acetate, dimethyl sulfoxide, butanediol, propylene glycol, butanol, propanol, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; more preferably, it is a polar solvent.

[0035] The various acrylic monomers are at least one selected from acrylic acid, butenoic acid, 3-methyl-3-butenoic acid, 2-methyl-2-acrylic acid, 3-ethyl-3-butenoic acid, phosphate methacrylate, polyethylene glycol phosphate methacrylate, 2-hydroxyethyl methacrylate phosphate ester, n-butyl acrylate, n-butyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, isobutyl acrylate, cyclohexyl acrylate, lauryl acrylate, styrene, isobornyl methacrylate, acrylonitrile, n-octyl methacrylate, and ethyl acrylate.

[0036] The internal salt nucleating agent synthesized in this invention is a high molecular weight polymer, and the polymer chain includes nitrogen-containing heterocycles. The nitrogen-containing heterocycle (quaternary ammonium imidazole salt) part has positive and negative functional groups, which promote crystal nucleus formation and improve nucleation efficiency through positive and negative charge Coulomb interactions.

[0037] Research has shown that the molar ratio of internal salt monomers to acrylic monomers needs to be strictly controlled to optimize the nucleation efficiency and compatibility of the nucleating agent. Therefore, the molar ratio of internal salt monomers to acrylic monomers is 1-3:8-4, which improves the crystallization temperature of polyester.

[0038] An application of a nucleating agent based on Coulomb forces in the synthesis of highly crystalline polyesters is disclosed. During polyester synthesis, a diacid, a diol, and an internal salt nucleating agent are added to a reactor. The reactor is then evacuated and purged with nitrogen. Under nitrogen protection, esterification, pre-condensation, and final condensation reactions are carried out sequentially to obtain the highly crystalline polyester. The amount of the internal salt nucleating agent added is 0.1 wt% to 2 wt% of the total polyester mass. The esterification temperature is 220–280 °C, the pressure is atmospheric pressure to 0.4 MPa, and the esterification time is 1.0–3.0 h. The pre-condensation temperature is controlled at 260–300 °C, the vacuum degree is 30–40 Pa, and the reaction time is 1.0–3.5 h. The final condensation temperature is controlled at 270–300 °C, the vacuum degree is 30–40 Pa, and the reaction time is 1.0–3.5 h.

[0039] Wherein, the diacid is at least one selected from terephthalic acid, isophthalic acid, naphthalene-dicarboxylic acid, adipic acid, biphenyl dicarboxylic acid, cyclohexanedicarboxylic acid, and succinic acid; the diol is a diol having 2 to 10 carbon atoms, including at least one selected from ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, and cyclohexanediethanol; the molar ratio of the diacid to the diol is 1:1.2 to 2.0; the diacid includes, but is not limited to, at least one selected from terephthalic acid, isophthalic acid, naphthalene-dicarboxylic acid, adipic acid, biphenyl dicarboxylic acid, cyclohexanedicarboxylic acid, and succinic acid; the diol includes, but is not limited to, at least one selected from ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, and cyclohexanediethanol; the molar ratio of the diacid to the diol is 1:1.2 to 2.

[0040] The specific preparation method of the internal salt nucleating agent and specific examples of applying the prepared internal salt nucleating agent to the synthesis of polyester are as follows:

[0041] Example 1:

[0042] Preparation of internal salt nucleating agents:

[0043] 10 g (0.11 mol) of vinylimidazole was dissolved in 150 ml of acetone and stirred to form a homogeneous and stable solution. Then, 12.98 g (0.11 mol) of 1,3-propanesulfonic acid lactone was gradually added dropwise to the solution and reacted at 50 °C for 24 h. A white solid precipitated during the reaction. The obtained solid was filtered and washed three times with ethyl acetate, and dried to obtain the inner salt monomer. Under a nitrogen atmosphere and with the initiator of azobisisobutyronitrile, the obtained inner salt monomer was subjected to free radical polymerization with acrylic acid, methacrylic acid, and hydroxyethyl methacrylate in a molar ratio of 1:2:3:3 to obtain a nucleating agent. Specifically, 10g (0.046mol) of inner salt monomer, 9.94g (0.138mol) of acrylic acid, 3.96g (0.046mol) of methacrylic acid, 17.96g (0.138mol) of hydroxyethyl methacrylate and 0.15g of azobisisobutyronitrile are first dissolved in 100ml of ethylene glycol. Then, the mixed solution is added dropwise over 2 hours to the polymerization reaction substrate at 80℃. After the addition is complete, the reaction continues for 3 hours. After cooling to room temperature, the inner salt nucleating agent for polyester synthesis is obtained.

[0044] Polyester synthesis:

[0045] 333.3g of purified terephthalic acid, 160g of ethylene glycol, 0.13g (170ppm) of antimony glycolate catalyst, and 4.9g (1%wt) of nucleating agent were added to a 1L reactor, and esterification, pre-condensation, and final condensation reactions were carried out sequentially under nitrogen protection. The esterification temperature was 240℃, the pressure was atmospheric pressure to 0.4MPa, and the esterification time was 2.5h. The pre-condensation temperature was 270℃, the vacuum degree was 30 to 1000Pa, and the reaction time was 1.5h. The final condensation temperature was 280℃, the vacuum degree was 30 to 240Pa, and the reaction time was 1.5h, finally yielding a polyester product.

[0046] Example 2:

[0047] Preparation of internal salt nucleating agents:

[0048] 10 g (0.11 mol) of vinylimidazole was dissolved in 150 ml of acetone and stirred to form a homogeneous and stable solution. Then, 12.98 g (0.11 mol) of 1,3-propanesulfonic acid lactone was gradually added dropwise to the solution and reacted at 50 °C for 24 h. A white solid precipitated during the reaction. The obtained solid was filtered and washed three times with ethyl acetate, and dried to obtain the inner salt monomer. Under a nitrogen atmosphere and with the initiator of azobisisobutyronitrile, the obtained inner salt monomer was subjected to free radical polymerization with acrylic acid at a molar ratio of 1:2 to obtain a nucleating agent. Specifically, 10g (0.046mol) of inner salt monomer, 6.63g (0.092mol) of acrylic acid, 7.92g (0.092mol) of methacrylic acid, 17.96g (0.138mol) of hydroxyethyl methacrylate and 0.15g of azobisisobutyronitrile are first dissolved in 100ml of ethylene glycol. Then, the mixed solution is added dropwise over 2 hours to the polymerization reaction substrate at 80℃. After the addition is complete, the reaction continues for 3 hours. After cooling to room temperature, the inner salt nucleating agent for polyester synthesis is obtained.

[0049] Polyester synthesis:

[0050] 333.3g of purified terephthalic acid, 160g of ethylene glycol, 0.13g (170ppm) of antimony glycolate catalyst, and 4.9g (1%wt) of internal salt nucleating agent were added to a 1L reactor, and esterification, pre-condensation, and final condensation reactions were carried out sequentially under nitrogen protection. The esterification temperature was 240℃, the pressure was atmospheric pressure to 0.4MPa, and the esterification time was 2.5h. The pre-condensation temperature was 270℃, the vacuum degree was 30 to 2000Pa, and the reaction time was 1.5h. The final condensation temperature was 280℃, the vacuum degree was 30 to 240Pa, and the reaction time was 1.5h, finally yielding a polyester product.

[0051] Example 3:

[0052] Preparation of internal salt nucleating agents:

[0053] 10 g (0.11 mol) of vinylimidazole was dissolved in 150 ml of acetone and stirred to form a homogeneous and stable solution. Then, 12.98 g (0.11 mol) of 1,3-propanesulfonic acid lactone was gradually added dropwise to the solution and reacted at 50 °C for 24 h. A white solid precipitated during the reaction. The obtained solid was filtered and washed three times with ethyl acetate, and dried to obtain the inner salt monomer. Under a nitrogen atmosphere and with azobisisobutyronitrile initiator, the obtained inner salt monomer was subjected to free radical polymerization with acrylic acid at a molar ratio of 2:1 to obtain a nucleating agent. Specifically, 10g (0.046mol) of inner salt monomer, 3.31g (0.046mol) of acrylic acid, 11.88g (0.138mol) of methacrylic acid, 17.96g (0.138mol) of hydroxyethyl methacrylate and 0.15g of azobisisobutyronitrile are first dissolved in 100ml of ethylene glycol. Then, the mixed solution is added dropwise over 2 hours to the polymerization reaction substrate at 80℃. After the addition is complete, the reaction continues for 3 hours. The mixture is then cooled to room temperature to obtain the inner salt nucleating agent for polyester synthesis.

[0054] Polyester synthesis:

[0055] 333.3g of purified terephthalic acid, 160g of ethylene glycol, 0.13g (170ppm) of antimony glycolate catalyst, and 4.9g (1%wt) of internal salt nucleating agent were added to a 1L reactor, and esterification, pre-condensation, and final condensation reactions were carried out sequentially under nitrogen protection. The esterification temperature was 240℃, the pressure was atmospheric pressure to 0.4MPa, and the esterification time was 2.5h. The pre-condensation temperature was 270℃, the vacuum degree was 30 to 2000Pa, and the reaction time was 1.5h. The final condensation temperature was 280℃, the vacuum degree was 30 to 240Pa, and the reaction time was 1.5h, finally yielding a polyester product.

[0056] Example 4:

[0057] Preparation of internal salt nucleating agents:

[0058] 10 g (0.11 mol) of vinylimidazole was dissolved in 150 ml of acetone and stirred to form a homogeneous and stable solution. Then, 12.98 g (0.11 mol) of 1,3-propanesulfonic acid lactone was gradually added dropwise to the solution and reacted at 50 °C for 24 h. A white solid precipitated during the reaction. The obtained solid was filtered and washed three times with ethyl acetate, and dried to obtain the inner salt monomer. Under a nitrogen atmosphere and with the initiator of azobisisobutyronitrile, the obtained inner salt monomer was subjected to free radical polymerization with acrylic acid at a molar ratio of 2:3 to obtain a nucleating agent. Specifically, 10g (0.046mol) of inner salt monomer, 9.94g (0.138mol) of acrylic acid, 3.96g (0.046mol) of methacrylic acid, 23.95g (0.184mol) of hydroxyethyl methacrylate and 0.15g of azobisisobutyronitrile are first dissolved in 100ml of ethylene glycol. Then, the mixed solution is added dropwise over 2 hours to the polymerization reaction substrate at 80℃. After the addition is complete, the reaction continues for 3 hours. The mixture is then cooled to room temperature to obtain the inner salt nucleating agent for polyester synthesis.

[0059] Polyester synthesis:

[0060] 333.3g of purified terephthalic acid, 160g of ethylene glycol, 0.13g (170ppm) of antimony glycolate catalyst, and 4.9g (1%wt) of internal salt nucleating agent were added to a 1L reactor, and esterification, pre-condensation, and final condensation reactions were carried out sequentially under nitrogen protection. The esterification temperature was 240℃, the pressure was atmospheric pressure to 0.4MPa, and the esterification time was 2.5h. The pre-condensation temperature was 270℃, the vacuum degree was 30 to 2000Pa, and the reaction time was 1.5h. The final condensation temperature was 280℃, the vacuum degree was 30 to 240Pa, and the reaction time was 1.5h, finally yielding a polyester product.

[0061] Comparative Example 1

[0062] Polyester synthesis:

[0063] 333.3g purified terephthalic acid, 160g ethylene glycol, 0.13g antimony glycolate (170ppm), and 4.9g (1%wt) sodium benzoate nucleating agent were added to a 1L reactor, and esterification, pre-condensation, and final condensation reactions were carried out sequentially under nitrogen protection. The esterification temperature was 240℃, the esterification pressure was atmospheric pressure to 0.4MPa, and the esterification time was 2.5h. The pre-condensation temperature was 270℃, the vacuum degree was 30 to 2000Pa, and the reaction time was 1.5h. The final condensation temperature was 280℃, the vacuum degree was 30 to 240Pa, and the reaction time was 1.5h, finally yielding a polyester product.

[0064] Comparative Example 2

[0065] 333.3g of purified terephthalic acid, 160g of ethylene glycol, and 0.13g of antimony glycol (170ppm) were added to a 1L reactor, and esterification, pre-polymerization, and final polymerization reactions were carried out sequentially under nitrogen protection. The esterification temperature was 240℃, the esterification pressure was atmospheric pressure to 0.4MPa, and the esterification time was 2.5h. The pre-polymerization temperature was 270℃, the vacuum degree was 30 to 2000Pa, and the reaction time was 1.5h. The final polymerization temperature was 280℃, the vacuum degree was 30 to 240Pa, and the reaction time was 1.5h, finally yielding a polyester product.

[0066] The relevant polyester product indicators of Examples 1-4 and Comparative Examples 1-2 were tested:

[0067] Thermal crystallization peak temperature (Tmc): The PET sample was placed in a differential scanning calorimeter (DSC) and heated to 300°C at a rate of 20°C / min. After being held at this temperature for 5 min to eliminate thermal history, the sample was cooled to room temperature at a rate of 20°C / min.

[0068] Intrinsic viscosity: The PET sample was dissolved in a phenol-tetrachloroethane mixed solution with a mass ratio of 1:1, with a concentration of approximately 5 mg / mL, and measured using an Ubbelohde viscometer at 25 °C.

[0069] Tensile strength was tested according to GB / T 1040-2006 standard; flexural strength was tested according to GB / T 9341-2008 standard. The test results are shown in the table below:

[0070]

[0071] By comparing the examples and Comparative Example 1, it was found that the intrinsic viscosity of PET was not affected by the present invention compared with traditional organic nucleating agents, and the mechanical properties were improved. By comparing the examples and Comparative Example 2, it was found that the nucleating agent of the present invention improved the nucleation efficiency and crystallization temperature of polyester compared with pure PET.

[0072] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a nucleating agent based on Coulomb forces, characterized in that: The preparation method includes: S1: Dissolve the nitrogen-containing cyclic compound in solvent A to form a homogeneous and stable solution system; S2: The solution system obtained in S1 is reacted with a sulfur-containing compound at a constant temperature for 1–72 h, and then filtered, washed, and dried to obtain an inner salt monomer; S3: Under the action of an initiator, the inner salt monomer obtained in S2 is subjected to free radical polymerization with various acrylic monomers in solvent B at a molar ratio of 1-3:8-4 for 1-48 hours to obtain a novel nucleating agent based on coulombic forces for the synthesis of highly crystalline polyesters. The nitrogen-containing cyclic compound is vinylimidazole, the sulfur-containing compound is sulfonyl lactone, and the acrylic monomers are acrylic acid, methacrylic acid, and hydroxyethyl methacrylate.

2. The method for preparing a nucleating agent based on Coulomb interaction according to claim 1, characterized in that: In step S2, the molar ratio of the solution system to the sulfur-containing compound is 1:1.2 to 1.2:1, the constant temperature is between 10 and 120°C, and the washing step involves washing three times with ethyl acetate.

3. The method for preparing a nucleating agent based on Coulomb interaction according to claim 1, characterized in that: The solvent A in step S1 is any one or a combination of ethanol, ethylene glycol, acetonitrile, ethyl acetate, dimethyl sulfoxide, butanediol, propylene glycol, butanol, propanol, acetone, and N-methylpyrrolidone.

4. The method for preparing a nucleating agent based on Coulomb interaction according to claim 1, characterized in that: The initiator in step S3 includes at least one of cyclohexanone peroxide, tert-butyl hydroperoxide, azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), ditert-pentyl peroxide (DTAP), and azobisisoheptanenitrile (AIBN), and the amount of the initiator is 0.2% to 2% of the total mass of the monomer.

5. The method for preparing a nucleating agent based on Coulomb interaction according to claim 1, characterized in that: The solvent B in step S3 is any one or a combination of ethanol, ethylene glycol, acetonitrile, ethyl acetate, dimethyl sulfoxide, butanediol, propylene glycol, butanol, propanol, and N-methylpyrrolidone.

6. The application of a nucleating agent based on Coulomb forces in the synthesis of highly crystalline polyesters, characterized in that: The nucleating agent prepared by the method of preparing a nucleating agent based on coulombic force as described in any one of claims 1 to 5 during the synthesis of highly crystalline polyester is added in an amount of 0.1 wt to 5 wt% of the total mass of polyester.

7. The application of the nucleating agent based on Coulomb interaction as described in claim 6 in the synthesis of highly crystalline polyesters, characterized in that: The synthesized highly crystalline polyester is prepared by reacting diols and diacids as raw materials under the action of the nucleating agent. The reaction temperature of the highly crystalline polyester is 220-300℃, the reaction pressure is 30Pa-0.4MPa, and the reaction time is 3.5-10.0h.

8. The application of the nucleating agent based on Coulomb interaction according to claim 7 in the synthesis of highly crystalline polyesters, characterized in that: The highly crystalline polyester undergoes esterification, pre-polymerization, and final polymerization sequentially during the reaction process. The esterification reaction is carried out at a temperature of 220–280°C, an esterification pressure of atmospheric pressure to 0.4 MPa, and an esterification time of 1.5–3.0 h. The pre-polymerization reaction is carried out at a temperature of 260–300°C, a vacuum degree of 30–3000 Pa, and a reaction time of 1.0–3.5 h. The final polymerization reaction is carried out at a temperature of 270–300°C, a vacuum degree of 30–240 Pa, and a reaction time of 1.0–3.5 h.

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