A benzimidazole derivative, its preparation method and use

Abstract

The application belongs to the technical field of plastic additives, and particularly relates to a benzimidazole derivative, a preparation method and application thereof. The application specifically discloses a structure of a benzimidazole derivative. The derivative is prepared by reacting o-phenylenediamine and corresponding dicarboxylic acid under catalysis of a phosphoric acid / polyphosphoric acid composite solvent system. The nucleating agent of the application can be processed into a PET composition by extrusion or injection molding after being mixed with polyethylene terephthalate (PET). In the processing, the nucleating agent can provide excellent nucleation efficiency for PET, significantly accelerate the crystallization rate of PET by virtue of the high-efficiency and stable heterogeneous nucleation effect, and improve the mechanical properties of the product. The application effectively solves the problems of low efficiency and many by-products in the synthesis of the benzimidazole derivative, and the obtained product is high in purity and stable in performance, and is suitable for high-performance crystallization modification of PET engineering plastics.

Description

Technical Field

[0001] This invention belongs to the field of plastic additives technology, and specifically relates to a benzimidazole derivative, its preparation method, and its application. Background Technology

[0002] Polyethylene terephthalate (PET) is a commonly used polyester thermoplastic. It has a semi-crystalline structure and good transparency, and also has the advantages of being lightweight, recyclable, easy to process, and food-grade certified. It is widely used in the fields of fiber, packaging and electronic devices.

[0003] However, the rigidity of PET molecular chains and the slow crystallization rate lead to a longer processing and molding cycle and a tendency for warping and deformation of the finished products, which severely limits its application in high-speed injection molding and film stretching.

[0004] In industry, nucleating agent modification technology is widely used to improve the crystallinity of PET, thereby improving its processability and the properties of the final product. However, commonly used inorganic nucleating agents (such as talc and silica) have poor compatibility with the PET matrix and are prone to agglomeration during melt processing, resulting in decreased crystallinity uniformity. Furthermore, excessive addition can impair the toughness of the material. Traditional organic nucleating agents (such as carboxylates and sorbitol derivatives) improve dispersibility, but still require relatively high addition levels (≥0.5 wt.%) to significantly improve crystallinity and may trigger thermal degradation side reactions.

[0005] Therefore, existing PET materials lack a nucleating agent that can achieve efficient nucleation and high performance retention even with low addition amounts. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems and provide a benzimidazole derivative nucleating agent that is added in PET with low dosage, high efficiency in nucleation, and high performance retention.

[0007] Another object of the present invention is to provide a preparation process for the above-mentioned benzimidazole derivative.

[0008] Another object of the present invention is to provide applications of the above-mentioned benzimidazole derivatives.

[0009] Another object of the present invention is to provide a PET composition containing the above-mentioned benzimidazole derivative.

[0010] This invention is achieved through the following technical solution:

[0011] A benzimidazole derivative having the following structure:

[0012]

[0013] Where n is a constant, n = 0, 1, 2, 3, 4, 5.

[0014] The benzimidazole derivative of the present invention contains a benzimidazole group, wherein the benzimidazole group is a core structure formed by coupling a benzene ring and an imidazole ring.

[0015] When n = 0, the benzimidazole derivative is 2,2′-dibenzimidazole, with the following structure:

[0016]

[0017] The two benzimidazole groups in this molecule are connected through its The segments are directly connected to form a completely coplanar rigid structure. This structure can efficiently bind with PET segments through π-π stacking, inducing heterogeneous nucleation.

[0018] When n = 1, the benzimidazole derivative is 2-(1H-benzimidazole-2-ylmethyl)-1H-benzimidazole, with the following structure:

[0019]

[0020] The two benzimidazole groups in this molecule are bridged by a methylene group. In its The units are interconnected to form a flexible chain that can rotate freely.

[0021] When n = 2, the benzimidazole derivative is 2,2′-(1,2-ethylidene)bis(1H-benzimidazole), with the following structure:

[0022]

[0023] The molecule contains two benzimidazole groups linked by an ethane-1,2-dimethyl chain. The two benzimidazole planes are interconnected. This linkage exhibits significant conformational flexibility, allowing for large spatial angles and relative motion between the two benzimidazole planes, resulting in a non-coplanar molecular structure.

[0024] When n = 3, the benzimidazole derivative is 1,3-bis(2-benzimidazole)propane, with the following structure:

[0025]

[0026] The molecule contains two benzimidazole groups linked by a propane-1,3-dimethyl chain. The two aromatic ring units are interconnected. This flexible alkane chain further increases the conformational freedom of the molecule, making the spatial distance and orientation between the two aromatic ring units highly tunable.

[0027] When n = 4, the benzimidazole derivative PET organic nucleating agent is 2-[4-(1H-benzimidazole-2-yl)butyl]-1H-benzimidazole, with the following structure:

[0028]

[0029] The molecule contains two benzimidazole groups linked by a butane-1,4-dimethyl chain. The two aromatic rings are interconnected. The flexible spacer group of this length provides the two aromatic rings with maximum spatial separation and conformational freedom, resulting in a non-planar structure with random coils or stretches.

[0030] When n = 5, the benzimidazole derivative PET organic nucleating agent is 2,2′-(1,5-pentylene)bis(1H-benzimidazole), with the following structure:

[0031]

[0032] The molecule contains two benzimidazole groups linked by a pentane-1,5-dimethyl chain. The two benzimidazole groups are interconnected. This long-chain alkane linker gives the molecule extremely high flexibility. The two benzimidazole groups can be regarded as being separated by a flexible spacer of predetermined length, with no conjugation between them and non-coplanarity.

[0033] The benzimidazole derivatives provided by this invention, when n = 1, 2, 3, 4 or 5, possess flexible chains that endow them with moderate molecular conformation adjustment capabilities, enabling them to be uniformly dispersed in PET melt while maintaining strong interactions between the benzimidazole ring and the PET chain segments.

[0034] This invention provides a method for preparing the above-mentioned benzimidazole derivative, comprising the following steps:

[0035] S1: A condensation reaction is carried out using o-phenylenediamine and dicarboxylic acid as raw materials in an acidic solvent;

[0036] S2: Adjust the pH of the mixed solution obtained from the reaction in S1 to 7-8 using an alkaline solution, add water to make up the volume, and then filter.

[0037] S3: Wash the solid obtained from filtering S2 and dry it to obtain the target product.

[0038] Preferably, the molar ratio of o-phenylenediamine to dicarboxylic acid in S1 is (1-3):(1-2), and the dicarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, or pimelic acid.

[0039] Preferably, the acidic solvent in S1 is selected from a composite acidic solvent composed of phosphoric acid solution and polyphosphoric acid; the volume ratio of the phosphoric acid solution to the polyphosphoric acid is (1-3):(1-4), the concentration of the phosphoric acid solution is 80-90 wt%, and the concentration of the polyphosphoric acid is ≥85 wt%.

[0040] The total content of all forms of phosphoric acid in the polyphosphoric acid described in this invention, including but not limited to orthophosphoric acid and pyrophosphoric acid, is converted into phosphorus pentoxide (P2O5) with a mass percentage ≥85%.

[0041] Preferably, the dicarboxylic acid in S1 is added dropwise to the reaction system in batches by dissolving it in 85wt% phosphoric acid solvent, and the concentration of the dicarboxylic acid in the phosphoric acid solution after dissolution is 5-20 mol / L; the dropping time is controlled at 30-60 minutes.

[0042] Preferably, the condensation reaction described in S1 is carried out under a nitrogen atmosphere at a temperature of 180-200°C for a condensation time of 5-7 hours.

[0043] Preferably, the alkaline solution in S2 is selected from a 1-2 mol / L NaOH solution.

[0044] Preferably, in S3, the product is washed 2-5 times with anhydrous ethanol heated to 50-70°C.

[0045] This invention provides the application of the above-mentioned benzimidazole derivative in the preparation of PET compositions.

[0046] This invention provides the application of the above-mentioned benzimidazole derivative as an additive for PET.

[0047] This invention provides the application of the above-mentioned benzimidazole derivative as a nucleating agent for PET.

[0048] The present invention provides a PET composition comprising any one of the benzimidazole derivatives described above.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] (1) Excellent nucleation performance: The benzimidazole derivative provided by the present invention, with low addition, significantly accelerates the crystallization rate of PET by means of efficient and stable heterogeneous nucleation, and greatly improves the crystallization peak temperature and crystallinity of PET; the strong π-π interaction between the benzimidazole derivative provided by the present invention and the PET chain segment endows the material with a high crystallization rate while improving the heat resistance and mechanical properties of PET material.

[0051] (2) The synthesis process is efficient and controllable: The present invention preferably uses a phosphoric acid / polyphosphoric acid composite solvent system, which has the functions of dehydration, acid catalysis and solvation, replacing the traditional strong corrosive media such as concentrated sulfuric acid, effectively solving the problem of low efficiency in the synthesis of such benzimidazole derivatives and significantly reducing side reactions; the dicarboxylic acid pre-dissolved in phosphoric acid solution is added to the reaction system step by step, and nitrogen gas is introduced for protection, which effectively inhibits the generation of oxidation byproducts.

[0052] (3) Innovative purification process: The purification process, which involves neutralization and volume adjustment followed by several cycles of ethanol heating and washing, effectively reduces the amount of residual impurities, showing significant advantages over the traditional water washing process. The resulting product has high yield, high purity, and stable performance. The prepared benzimidazole derivative fully meets the high-temperature processing requirements of PET materials and is suitable for high-performance crystallization modification of PET engineering plastics.

[0053] (4) The reaction does not require high pressure or special equipment, and it is easy to achieve industrial scale-up production; the benzimidazole derivative has good compatibility with the PET matrix and can be directly processed by conventional extrusion or injection molding without additional modification steps. Attached Figure Description

[0054] Figure 1 The reaction formula for 2,2′-dibenzimidazole.

[0055] Figure 2 The image shows the 1H NMR spectrum of 2,2′-dibenzimidazole in the range of 0-12 ppm.

[0056] Figure 3 The image shows the 1H NMR spectrum of 2,2′-dibenzimidazole at 6-8 ppm.

[0057] Figure 4 Thermogravimetric (TG) diagram of 2,2′-dibenzimidazole.

[0058] Figure 5 Differential scanning calorimetry (DSC) spectra of 2,2′-dibenzimidazole as an organic nucleating agent in PET, added to PET at an amount of 1.0 wt.%. Detailed Implementation

[0059] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0060] All raw materials used in this invention are commercially available.

[0061] Test methods:

[0062] (1) DSC test: According to the determination method of GB1662-81, the non-isothermal crystallization melting behavior of PET and its composites was studied on a differential scanning calorimeter under a nitrogen atmosphere, with a sample amount of 5-10 mg. The temperature was increased from room temperature to 300℃ at a rate of 50℃ / min and held for 5 min; then the temperature was decreased from 300℃ to room temperature at a rate of 10℃ / min, and the crystallization temperature was recorded; finally, the temperature was increased from room temperature to 300℃ at a rate of 10℃ / min, and the crystallinity was calculated using the built-in program of DSC.

[0063] (2) TG test: Accurately weigh 3mg (±0.5mg) of nucleating agent powder and test it using a thermogravimetric analyzer. In high-purity nitrogen (50mL / min), the temperature is increased to 600℃ at 10℃ / min, and the thermogravimetric curve is measured.

[0064] (3) Heat distortion temperature test: According to GB / T1633-2000, standard specimens with dimensions of 80mm×10mm×4mm were prepared by injection molding. During the test, the specimens were placed horizontally on the test table and tested using the WKW-300B heat distortion Vicat instrument of Changchun Intelligent Instruments.

[0065] (4) Vicat softening temperature test: According to GB / T1633-2000, a square sample with a thickness of 4.0 mm and a side length of 10 mm was prepared, and the Vicat softening temperature was determined under a load of 50 N and a heating rate of 50 °C / h (the average value of 5 parallel tests was taken).

[0066] (5) Bending modulus: According to GB / T1843-2008, an 80mm×10mm×4mm (±0.2mm) standard specimen was used, the bending rate was 5.0mm / min, the test span was 64.00mm, and the specified bending deflection was 6.00mm. Five specimens of each type were taken for testing, and the average value was taken.

[0067] The embodiments described in this invention are obtained by the following method:

[0068] S1: Weigh a certain molar mass of o-phenylenediamine and dicarboxylic acid. Add the o-phenylenediamine to a three-necked flask, then add a certain volume and concentration of phosphoric acid solution and a certain volume and concentration of polyphosphoric acid composite solvent to obtain a 1.5-8 mol / L o-phenylenediamine-phosphoric acid-polyphosphoric acid composite solution. Turn on the reflux condenser and introduce nitrogen gas, and heat to a certain temperature with magnetic stirring. Then dissolve the dicarboxylic acid in 85 wt% phosphoric acid solution to obtain a 5-25 mol / L dicarboxylic acid-phosphoric acid solution. Add the solution slowly in three portions through a constant pressure dropping funnel to the reaction system, controlling the total dropping time to 45 minutes. After the dropping is completed, continue the reaction for 5 hours. During this period, maintain nitrogen protection to inhibit the formation of oxidation byproducts.

[0069] S2: After the reaction in S1 is completed, adjust the pH of the reaction solution to a certain range with an alkaline solution of a certain concentration, add distilled water to make up to 1000 mL and stir continuously, then filter to obtain the solid product.

[0070] S3: The solid product obtained in S2 is washed several times with anhydrous ethanol preheated to a certain temperature, and filtered to remove residual impurities; finally, the obtained solid is dried in a vacuum drying oven at a certain temperature.

[0071] Table 1. Mass, parameter conditions, and yield results of each component in Examples 1-6.

[0072]

[0073]

[0074] The substance obtained in Example 1 was subjected to nuclear magnetic resonance (NMR) detection, and the 1H NMR spectrum is shown below. Figure 2 and Figure 3 As shown in the figure, the chemical shift at 11.9 ppm is the -NH- proton signal peak on the imidazole ring, and the chemical shifts at 7.08 and 7.12 ppm are the proton signal peaks on the benzene ring of benzimidazole. This demonstrates that the preparation method provided by this invention can yield the target substance: 2,2′-dibenzimidazole.

[0075] In this invention, the substance obtained in Example 2 is 2-(1H-benzimidazole-2-ylmethyl)-1H-benzimidazole; the substance obtained in Example 3 is 2,2′-(1,2-ethylidene)bis(1H-benzimidazole); the substance obtained in Example 4 is 1,3-bis(2-benzimidazole)propane; the substance obtained in Example 5 is 2-[4-(1H-benzimidazole-2-yl)butyl]-1H-benzimidazole; and the substance obtained in Example 6 is 2,2′-(1,5-pentylidene)bis(1H-benzimidazole). The preparation reaction principle of Examples 2-6 is the same as that of Example 1.

[0076] Table 2 shows the mass, parameters, and yield results of each component in Examples 7-12.

[0077]

[0078]

[0079] Table 3. Mass, parameter conditions, and yield results of each component in Examples 13-18

[0080]

[0081]

[0082] As can be seen from Examples 1-18, the preparation method provided by the present invention can obtain the target product. Where n is a constant, n = 0, 1, 2, 3, 4, 5. The preparation method provided by this invention has a yield ≥ 90 wt%.

[0083] Comparative Example 1:

[0084] Oxalic acid was not first dissolved in phosphoric acid solution, but was instead added together with o-phenylenediamine into a three-necked flask. The phosphoric acid solution used to dissolve the oxalic acid was mixed with a complex acidic solvent and then added to the three-necked flask. Other conditions were the same as in Example 1. The yield was 86.5%.

[0085] Comparative Example 2:

[0086] Instead of using a phosphoric acid-polyphosphoric acid complex solution, a sulfuric acid solution of the same concentration was used, with other conditions the same as in Example 1. The yield was 74.2%.

[0087] Application Example 1:

[0088] Polyethylene terephthalate (PET) and the 2,2′-dibenzimidazole nucleating agent obtained in Example 1 were dried in an oven at 80°C for 6 hours. PET and the nucleating agent were then thoroughly mixed at a mass ratio of 100:0.1. The extruder temperature zones were set to 250, 260, 280, 280, 270, 270, and 250°C. The extruder speed was set to 200 r / min. The mixture was then fed into a twin-screw extruder to obtain a PET composition with a 2,2′-dibenzimidazole weight percentage of 0.1 wt.%, named PET / 2,2′-dibenzimidazole-0.1 wt.%.

[0089] Application Example 2:

[0090] The mass ratio of PET to nucleating agent was adjusted to 100:0.3, and other conditions were the same as in Application Example 1. It was named PET / 2,2′-dibenzimidazole-0.3wt%.

[0091] Application Example 3:

[0092] The mass ratio of PET to nucleating agent was adjusted to 100:0.5, and other conditions were the same as in Application Example 1. The mixture was named PET / 2,2′-dibenzimidazole-0.5wt%.

[0093] Application Example 4:

[0094] The mass ratio of PET to nucleating agent was adjusted to 100:1, and other conditions were the same as in Application Example 1. The product was named PET / 2,2′-dibenzimidazole-1.0wt%.

[0095] Application Example 5:

[0096] The nucleating agent was replaced with 2-(1H-benzimidazole-2-ylmethyl)-1H-benzimidazole prepared in Example 2, and other conditions were the same as in Application Example 4. It was named PET / 2-(1H-benzimidazole-2-ylmethyl)-1H-benzimidazole-1.0wt%.

[0097] Application Example 6:

[0098] The nucleating agent was replaced with 2,2′-(1,2-ethylidene)bis(1H-benzimidazole) prepared in Example 3, and other conditions were the same as in Application Example 4. It was named PET / 2,2′-(1,2-ethylidene)bis(1H-benzimidazole)-1.0wt%.

[0099] Application Example 7:

[0100] The nucleating agent was replaced with 1,3-bis(2-benzimidazole)propane prepared in Example 4, and other conditions were the same as in Application Example 4. It was named PET / 1,3-bis(2-benzimidazole)propane-1.0wt%.

[0101] Application Example 8:

[0102] The nucleating agent was replaced with 2-[4-(1H-benzimidazole-2-yl)butyl]-1H-benzimidazole prepared in Example 5, and other conditions were the same as in Application Example 4. It was named PET / 2-[4-(1H-benzimidazole-2-yl)butyl]-1H-benzimidazole-1.0wt%.

[0103] Application Example 9:

[0104] The nucleating agent was replaced with 2,2′-(1,5-pentylene)bis(1H-benzimidazole) prepared in Example 6, and other conditions were the same as in Application Example 4. It was named PET / 2,2′-(1,5-pentylene)bis(1H-benzimidazole)-1.0wt%.

[0105] Comparative application example 1:

[0106] Replace the nucleating agent with a commercially available conventional PET nucleating agent, namely sodium montancetate (NAV101) manufactured by Clariant, and keep other conditions the same as in Application Example 4.

[0107] Table 4 shows the performance test results of Application Examples 1-9 and Comparative Application Example 1 and Blank Application Example.

[0108]

[0109] As shown in Table 4, compared with pure PET without nucleating agent (blank application example), the crystallinity, thermodynamic properties, and mechanical properties of PET materials were significantly improved after adding the nucleating agent provided by this invention (application examples 1-9). Specifically, the crystallization peak temperature increased to above 197℃, and the crystallinity increased significantly; the heat distortion temperature and Vicat softening temperature increased significantly, indicating that the heat resistance of the material was effectively improved; the flexural modulus was also enhanced, indicating that the rigidity of the material was improved.

[0110] In comparison with the commercial nucleating agent NAV101 (Comparative Application Example 1), the nucleating agent provided by the present invention exhibits comparable or better comprehensive performance in many key performance parameters, especially showing good results in crystallinity and thermal stability, indicating that the nucleating agent of the present invention has good industrial application potential.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An application of a benzimidazole derivative, characterized in that, The benzimidazole derivative used in the preparation of PET compositions has the following structure: ； Where n is a constant, n = 0, 1, 2, 3, 4, 5.

2. A PET composition, characterized in that, It comprises a benzimidazole derivative as described in claim 1 and PET.

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