Polyester nucleating agent and preparation method thereof

Abstract

The present application belongs to the technical field of polyester nucleating agent, and particularly relates to a kind of universally applicable polyester nucleating agent and its preparation method. A series of furan diacyl hydrazine thermoplastic polyester nucleating agents are prepared by using furfuryl chloride, a derivative of furfural, and on this basis, a heat-resistant polyester composition is prepared by melt blending according to the mass ratio of 100 parts of polyester, 0.3-1 parts of nucleating agent, which can significantly improve the heat resistance and transparency of polyester plastic products. The nucleating agent has a wide source of raw materials, a simple preparation process, can effectively improve the crystallization rate of polyester, and has good industrialization prospect.

Description

Technical Field

[0001] This invention belongs to the field of polyester nucleating agent technology, specifically relating to a class of nucleating agents applicable to various polyesters and their preparation methods. Background Technology

[0002] Polyesters are a class of high-performance, widely used engineering plastics. As human production and daily life increasingly demand high-molecular materials, primarily plastics, the accumulation of waste plastics in nature and the resulting white pollution are also intensifying. Polyester categories include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), furan-based polyesters such as polyethylene furanate and propylene furanate, as well as biodegradable polybutylene succinate and poly(butylene terephthalate-adipate-coated) esters. Polylactic acid is also a member of the polyester family.

[0003] The C=O groups on the polyethylene terephthalate (PET) molecular chain reduce the symmetry of the molecular chain, and the benzene rings on the main chain greatly increase its rigidity. This makes molecular chain segment movement difficult, resulting in a slow crystallization rate for PET. This leads to drawbacks such as high mold temperatures, long molding cycles, and easy product sticking and warping during injection molding. Therefore, improving the crystallization rate of PET is a hot research topic in industry and academia. Polybutylene terephthalate (PBT) has poor mechanical properties and heat resistance, so the crystallization control of PBT also needs in-depth research. Due to the low molecular symmetry, high rigidity, and large intermolecular dipole interactions of the monomer 2,5-furandicarboxylic acid, the movement of chain segments in furan-based polyesters is hindered during crystallization, resulting in a slow crystallization rate and long molding cycles, limiting the application of PEF in production and daily life. Most biodegradable polyesters have weak crystallization ability or their crystallization process cannot be controlled. Polylactic acid (PLA) is a semi-crystalline polymer material with poor crystallization ability and slow crystallization rate. Under conventional processing conditions, it can only produce amorphous products and cannot withstand temperatures above 60°C, which severely limits the application range of PLA materials.

[0004] Adding nucleating agents during polymer processing is a common method to improve polymer crystallization. It is simple to operate and can shorten the nucleation induction cycle, increase nucleation density, and accelerate the crystallization rate. However, nucleating agents used in general production often have poor compatibility with the matrix, are prone to agglomeration, resulting in insignificant improvements in crystallization performance, low heat resistance, and limited application scenarios. Some nucleating agents are derived from petrochemical resources and may even contain heavy metal particles, negatively impacting the environment and limiting their applicability in the food and pharmaceutical fields. Therefore, developing a universally applicable nucleating agent that can improve polyester crystallization rate and heat resistance, while also being compatible with polymers and environmentally friendly, is an urgent technical problem to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a class of polyester nucleating agents and their preparation methods. These nucleating agents are bio-based, exhibiting excellent nucleation effects and significantly improving the crystallinity, heat resistance, and polymer compatibility of various polyester materials, thus possessing wide applicability.

[0006] In a first aspect, the present invention provides a type of nucleating agent for polyesters, the structural formula of which is:

[0007]

[0008] Where n is a natural number, and its value ranges from 2 to 6.

[0009] Further, the polyester is selected from at least one of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); or from at least one of polybutylene succinate and polybutylene terephthalate-adipate; or from at least one of polyethylene furanate and propylene furanate; or polylactic acid.

[0010] Secondly, the present invention provides a method for preparing a type of nucleating agent for polyesters, comprising the following steps:

[0011] S1. Add alkyl dicarboxylic acid dimethyl ester, hydrazine hydrate, and alcohol solvent to the reactor and reflux at 70-100℃ to generate the corresponding alkyl dihydrazide;

[0012] S2. The alkyl dihydrazide and acid-binding agent prepared in step S1 are added to a high-boiling-point solvent. Furfuryl chloride is added dropwise to the solvent at a temperature of -10℃ to -25℃. The temperature is then raised to 60-100℃ to react and obtain alkyl dicarboxylic acid difuran carboxylic acid hydrazide. After separation and purification, the nucleating agent is obtained.

[0013] The alkyl dicarboxylic acid dimethyl ester has 6-12 carbon atoms.

[0014] Furthermore, the alkyl dicarboxylic acid dimethyl ester used is selected from at least one of dimethyl adipate, dimethyl octanoate, and dimethyl sebacate.

[0015] Furthermore, the molar ratio of the alkyl dihydrazide to furfuryl chloride is 1:2-2.5.

[0016] Furthermore, the molar ratio of the alkyl dicarboxylic acid dimethyl ester and hydrazine hydrate in step S1 is 1:8-12.

[0017] Further, the molar ratio of the acid-binding agent to furoyl chloride in step S2 is 1-1.5:1.

[0018] Furthermore, the alcohol solvent used is at least one of methanol, ethanol, isopropanol, and n-butanol.

[0019] Furthermore, the high-boiling-point solvent used is at least one of toluene, xylene, acetonitrile, dimethyl sulfoxide, N,N'-dimethylformamide, and N,N'-dimethylacetamide.

[0020] Furthermore, the acid-binding agent used is triethylamine or pyridine.

[0021] Thirdly, the present invention provides a method for preparing another type of nucleating agent for polyesters, comprising the following steps:

[0022] R1. Methyl furoate is refluxed in an alcohol solvent and reacted with hydrazine hydrate to produce furoyl hydrazine;

[0023] R2. Add furfuryl hydrazine and an acid-binding agent to a high-boiling-point solvent, add alkyl diacyl chloride dropwise at -10℃ to room temperature, and then react at 60-100℃ to obtain alkyl dicarboxylic acid difuran carboxyl hydrazine, which is then separated and purified to obtain the nucleating agent.

[0024] The molar ratio of the alkyl diacyl chloride to furfuryl hydrazine is 1:2-2.5;

[0025] The alkyl diacyl chloride has 6-12 carbon atoms.

[0026] Furthermore, the molar ratio of methyl furoate to hydrazine hydrate is 1:4-6.

[0027] Furthermore, the molar ratio of the acid-binding agent to the alkyl diacyl chloride is 2-3:1.

[0028] Furthermore, the alkyl diacyl chloride used is 1,6-adiacyl chloride, 1,8-octanoyl chloride, or 1,10-sebacyl chloride.

[0029] Furthermore, the alcohol solvent used is at least one of methanol, ethanol, isopropanol, and n-butanol.

[0030] Furthermore, the high-boiling-point solvent used is at least one of toluene, xylene, acetonitrile, dimethyl sulfoxide, N,N'-dimethylformamide, and N,N'-dimethylacetamide.

[0031] Furthermore, the acid-binding agent used is triethylamine or pyridine.

[0032] Fourthly, the present invention provides a type of heat-resistant polyester composition, comprising, by weight, 100 parts polyester and 0.1-3 parts nucleating agent alkyl dicarboxylic acid difuran carboxylhydrazine;

[0033] The nucleating agent, alkyl dicarboxylic acid difuran carboxylhydrazine, has the following structural formula:

[0034]

[0035] Where n is a natural number, and its value ranges from 2 to 6.

[0036] Furthermore, in the heat-resistant polyester composition, the mass ratio of the nucleating agent to the polyester is preferably 0.3-1:100.

[0037] Further, the polyester is selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polybutylene succinate, polybutylene terephthalate-adipate-butylene glycol, and polylactic acid.

[0038] The heat-resistant polylactic acid composition is prepared by the following method, including the following steps:

[0039] T1. Dry polylactic acid and nucleating agent in a vacuum oven at 50-80℃ for 12-24 hours, and then mix them in advance.

[0040] T2. Place the mixed material in an internal mixer and mix for no less than 10 minutes at a rotor speed of 15-30 rpm to obtain the heat-resistant polylactic acid composition.

[0041] Furthermore, when the polyester is polylactic acid, the mixing temperature is 175-200℃;

[0042] When the polyester is polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), the mixing temperature is 270-29℃.

[0043] When the polyester is butylene succinate or polybutylene terephthalate, the mixing temperature is 165-200℃.

[0044] Beneficial effects:

[0045] The novel nucleating agent provided by this invention belongs to the acylhydrazine class of compounds. It is soluble in various polyester matrices and promotes polymer crystallization through its unique self-assembly behavior, exhibiting a significant nucleation effect and greatly improving the crystallization rate of polyester. It has good compatibility with the matrix, disperses uniformly within the matrix, and only a small amount is needed to promote polymer crystallization. Furthermore, compared to inorganic minerals, it better prevents the degradation of the mechanical properties of polymer products. The heat-resistant polyester composition of this invention produces products with good transparency, is simple to prepare, and is easy to scale up for industrial production, demonstrating good implementation value and market prospects. Attached Figure Description

[0046] Figure 1 This is a synthetic route diagram for sebacatehydrazide in Example 1;

[0047] Figure 2 This is a synthetic route diagram of sebacate difuran carbamate in Example 1;

[0048] Figure 3 The image shows the 1H-NMR spectrum of sebacate difuran carbamate hydrazine in Example 1;

[0049] Figure 4 The following are DSC curves of samples from Examples 3, 4, and 5 cooled at 10°C / min.

[0050] Figure 5 This is a heat flow curve of the samples in Examples 3, 4 and 5 undergoing isothermal crystallization at 120°C;

[0051] Figure 6 This is a graph showing the relative crystallinity versus crystallization time of the samples in Examples 3, 4, and 5 during isothermal crystallization at 120°C. Detailed Implementation

[0052] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0053] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0054] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0055] Test instrument models: The nuclear magnetic resonance spectrometer used was a Vaian DLG400 (Varian, USA), and the differential scanning calorimeter used was a DSC25 (TA, USA).

[0056] Example 1 (Preparation of nucleating agent, sebacate difuranoyl hydrazine, n=6)

[0057] (1) Preparation of sebacate hydrazide: 11.52 g of dimethyl sebacate, 12.52 g of hydrazine hydrate (80%) and 30 mL of anhydrous ethanol were placed in a reaction flask. The reaction was refluxed at 80 °C for 8 h. During the reaction, a large amount of white solid precipitated out. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol. After drying, 10.48 g of white solid with a metallic luster was obtained, with a yield of 91%. The synthetic route is shown in [reference needed]. Figure 1 .

[0058] (2) Preparation of sebacate difuranyl hydrazine: 4.61 g sebacate hydrazine, 4.45 g triethylamine, and 50 mL anhydrous acetonitrile were placed in a reaction flask. 5.74 g furfuryl chloride was added dropwise to the reaction system at 0 °C. After the addition was complete, the temperature was raised to 80 °C and reacted for 8 h. After the reaction was complete, the mixture was cooled to room temperature, and the filter cake was washed once with water and once with anhydrous ethanol. After drying, 5.44 g of white powder, i.e., polylactic acid nucleating agent, was obtained, with a yield of 65%. The synthetic route is shown in [reference needed]. Figure 2 .

[0059] The product was characterized by 1H NMR spectroscopy, and the results are shown in the figure. Figure 3 .

[0060] Example 2 (Preparation of nucleating agent: adipyldifuran carbazone, n=2)

[0061] (1) Preparation of adipic acid hydrazide: 17.42 g of dimethyl adipate, 31.29 g of hydrazine hydrate (80%) and 50 mL of anhydrous ethanol were placed in a reaction flask. The reaction was refluxed at 90 °C for 8 h. During the reaction, a large amount of white solid precipitated out. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol. After drying, 15.68 g of white solid with a metallic luster was obtained, with a yield of 95%. The synthetic route is shown in [reference needed]. Figure 1 .

[0062] (2) Preparation of adipyl difuran carbamate: 17.42 g adipyl hydrazide, 20.24 g triethylamine and 100 mL anhydrous acetonitrile were placed in a reaction flask. 26.11 g furoyl chloride was added dropwise to the reaction system at 0 °C. After the addition was completed, the temperature was raised to 80 °C and reacted for 10 h. After the reaction was completed, the mixture was cooled to room temperature. The filter cake was washed once with water and once with anhydrous ethanol. After drying, 21.38 g of white powder, namely polylactic acid nucleating agent, was obtained with a yield of 59%.

[0063] Example 3 (Lactic Acid Bacteria Blend)

[0064] The nucleating agent prepared in Example 1 and polylactic acid (number average molecular weight of 103,000) were dried in a vacuum oven at 60°C for 12 hours. 60g of polylactic acid and 0.18g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the internal mixer were set to 180°C, 179°C, 178°C, and 175°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed a crystallization temperature of 124°C.

[0065] Example 4 (Comparative Example)

[0066] Commercial nucleating agent sebacatedibenzoyl hydrazine (trade name TMC300) and polylactic acid (number average molecular weight 103,000) were dried in a vacuum oven at 60°C for 12 hours. 60g of polylactic acid and 0.18g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the mixer were set to 180°C, 179°C, 178°C, and 175°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed a crystallization temperature of 96°C.

[0067] Example 5 (Comparative Example)

[0068] Pure polylactic acid (number average molecular weight 103,000) was dried in a vacuum oven at 60°C for 12 hours. 60g of polylactic acid was then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the mixer were set to 180°C, 179°C, 178°C, and 175°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed no crystallization peaks in the cooling curve.

[0069] Example 6 (Blending)

[0070] The nucleating agent and polylactic acid prepared in Example 2 were dried in a vacuum oven at 60°C for 12 hours. 60g of polylactic acid and 0.18g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the internal mixer were set to 180°C, 179°C, 178°C, and 175°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed a crystallization temperature of 118°C.

[0071] Example 7 (Polybutylene succinate blend)

[0072] The nucleating agent and polybutylene succinate prepared in Example 2 were dried in a vacuum oven at 60°C for 12 hours. 60g of polybutylene succinate and 0.18g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the internal mixer were set to 170°C, 169°C, 168°C, and 165°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed a crystallization temperature of 83°C.

[0073] Example 8 (Comparative Example)

[0074] Commercial nucleating agent sebacate dibenzoyl hydrazine (trade name TMC300) and polybutylene succinate were dried in a vacuum oven at 60°C for 12 hours. 60g of polybutylene succinate and 0.18g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the internal mixer were set to 170°C, 169°C, 168°C, and 165°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed a crystallization temperature of 82°C.

[0075] Example 9 (Polybutylene terephthalate blend)

[0076] The nucleating agent and polybutylene terephthalate prepared in Example 1 were dried in a vacuum oven at 60°C for 12 hours. 75g of polybutylene terephthalate and 0.23g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the internal mixer were set to 270°C, 269°C, 268°C, and 265°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed that the crystallization temperature was 192°C.

[0077] Example 10 (Blending)

[0078] The nucleating agent and polybutylene terephthalate prepared in Example 2 were dried in a vacuum oven at 60°C for 12 hours. 75g of polybutylene terephthalate and 0.23g of the nucleating agent were pre-mixed in a self-sealing bag and then placed in a SU-70B micro internal mixer for melt mixing. The melt temperature and the three temperature control zones of the internal mixer were set to 270°C, 269°C, 268°C, and 265°C, respectively, and the rotor speed was set to 15 rpm. DSC non-isothermal crystallization testing showed that the crystallization temperature was 188°C.

[0079] Example 11 (Polyethylene furanate blend)

[0080] The nucleating agent and polyethylene furanate prepared in Example 1 were dried in a vacuum oven at 60°C for 12 hours. 1 kg of polyethylene furanate and 5 g of nucleating agent were pre-mixed in a self-sealing bag and then placed in an SHJ-20 twin-screw extruder for melt mixing. The temperatures of the five temperature control zones and the die head of the extruder were set to 190°C, 220°C, 230°C, 245°C, 250°C, and 248°C, respectively, and the screw speed was 150 rpm. DSC non-isothermal crystallization testing showed that during the secondary heating process, the melting temperature was 209.5°C and the enthalpy of melting was 19.3 J / g.

[0081] Example 12 (Comparative Example)

[0082] Commercial nucleating agent sebacate dibenzoyl hydrazine (trade name TMC300) and polyethylene furanate were dried in a vacuum oven at 60°C for 12 hours. 1 kg of polyethylene furanate and 5 g of TMC300 were pre-mixed in a self-sealing bag and then placed in an SHJ-20 twin-screw extruder for melt mixing. The extruder's five temperature control zones and die head temperature were set to 190°C, 220°C, 230°C, 245°C, 250°C, and 248°C, respectively, with a screw speed of 150 rpm. DSC non-isothermal crystallization testing showed that during the secondary heating process, the melting temperature was 207.5°C and the enthalpy of melting was 2.1 J / g.

[0083] As can be seen from the above embodiments and comparative examples, the nucleating agent of this application has a good nucleating effect on various polyesters. Specifically, it outperforms existing nucleating agents for traditional polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). For furan-based polyesters, the crystallization temperature is slightly better than similar nucleating agents, and the melting enthalpy is significantly increased, indicating a significant improvement in crystallinity compared to similar nucleating agents. For biodegradable polybutylene succinate and polybutylene terephthalate-adipate-butylene glycol, the crystallization temperature is slightly better than existing nucleating agents; for polylactic acid, its nucleating effect is far superior to other similar nucleating agents. Therefore, this nucleating agent has a good nucleating effect on the above-mentioned polyesters. Furthermore, the nucleating agent in this embodiment is bio-based, will not cause environmental pollution or affect human health, and has good application prospects and promotional value.

[0084] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a type of nucleating agent for polyesters, characterized in that, Includes the following steps: S1. Dimethyl sebacate, hydrazine hydrate, and alcohol solvent are added to the reactor and refluxed at 70-100℃ to generate sebacate dihydrazide. S2. Add the sebacic dihydrazide and acid-binding agent prepared in step S1 to a high-boiling-point solvent. Add furfuryl chloride dropwise to the solvent at a temperature of -10℃ to -25℃. Then, heat the solvent to 60-100℃ to react and obtain sebacic difurandicarboxyhydrazide. After separation and purification, the nucleating agent is obtained. The molar ratio of sebacic acid dihydrazide to furfural chloride is 1:2-2.5; The molar ratio of dimethyl sebacate and hydrazine hydrate in step S1 is 1:8-12; The molar ratio of the acid-binding agent to furfuryl chloride in step S2 is 1-1.5:

1.

2. A method for preparing a nucleating agent for heat-resistant polyesters, characterized in that, Includes the following steps: R1. Methyl furoate is refluxed in an alcohol solvent and reacted with hydrazine hydrate to produce furoyl hydrazine; R2. Add furfurylhydrazine and an acid-binding agent to a high-boiling-point solvent, add 1,10-sebaconyl chloride dropwise at -10℃ to room temperature, and then react at 60-100℃ to obtain sebaconyl difurandicarboxyhydrazine, which is then separated and purified to obtain the nucleating agent. The molar ratio of 1,10-sebacyl chloride to furfural hydrazine is 1:2-2.5; The molar ratio of methyl furoate and hydrazine hydrate in step R1 is 1:4-6; The molar ratio of the acid-binding agent to 1,10-sebacol chloride in step R2 is 2-3:

1.

3. The method for preparing the nucleating agent for polyester according to claim 1 or 2, characterized in that, The structural formula of the nucleating agent is: Where n takes the value 6; The nucleating agent is suitable for a polyester selected from at least one of polyethylene terephthalate and polybutylene terephthalate; or selected from at least one of polybutylene succinate and polybutylene terephthalate-adipate-butylene glycol; or selected from at least one of polyethylene furanate and propylene furanate; or polylactic acid.

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