Polyethylene stiffening modifier and application thereof

Abstract

The invention discloses a polyethylene stiffening modifier and application thereof, and relates to the technical field of polyethylene modification. The rigid benzene ring structure in the molecular chain of the polyethylene stiffening modifier can inhibit the movement ability of the polyethylene molecular chain and enhance the non-deformability of the polyethylene molecular chain, thereby enhancing the rigidity of the polyethylene molecular chain. Meanwhile, the polyethylene stiffening modifier has the capability of forming lattice matching with polyethylene, and can improve the crystal structure of the polyethylene, thereby further improving the rigidity of the polyethylene.

Description

Technical Field

[0001] This invention relates to a polyethylene stiffening modifier and its application, belonging to the field of polymer materials technology. Background Technology

[0002] Polyethylene, as one of the world's largest-produced general-purpose plastics, is widely used in packaging materials, building materials, automotive parts, and electronic appliance housings due to its excellent chemical resistance, good processing flowability, lightweight, and low cost. However, because polyethylene molecular chains are tough but lack rigidity, it exhibits disadvantages such as poor pressure resistance in hollow and blow-molded products, thus limiting its application in scenarios with strict requirements for material rigidity. Therefore, there is an urgent need to develop a modifier with a stable molecular structure, low dosage, and good economic efficiency to enhance its rigidity and adapt it to its applications in related fields. Summary of the Invention

[0003] This invention provides a polyethylene stiffening modifier and its application. The rigid benzene ring structure in the polyethylene stiffening modifier's molecular chain can inhibit the movement of the polyethylene molecular chain, enhancing its resistance to deformation. Simultaneously, it has the ability to form a lattice match with polyethylene, and can serve as an effective modifier to improve its crystal structure, thereby significantly increasing its rigidity.

[0004] This invention provides a polyethylene stiffening modifier, which is prepared by the following method, comprising: S1. Add 1.6 mL of dry pyridine and 1.26 g of melamine to 100 mL of dry N-methylpyrrolidone, keeping the system temperature at 0 °C. Dissolve 4.33 g of biphenyl-4-formyl chloride in 20 mL of N-methylpyrrolidone. Add the above solution of biphenyl-4-formyl chloride in N-methylpyrrolidone to the system dropwise over 30 min. After the addition is complete, heat the system temperature to 100 °C and stir at 800 rpm for 8 h. After the reaction is complete, pour 500 mL of ice water into the system to precipitate the product. Filter and wash with ethanol until neutral. Then dry the product at 80 °C to constant weight to obtain intermediate product A. S2. Add 1 mL of dry pyridine and 4.86 g of intermediate product A to 100 mL of dry N-methylpyrrolidone. Keep the system temperature at 0 °C. Dissolve 2 g of benzoyl chloride in 20 mL of N-methylpyrrolidone. Add the above benzoyl chloride N-methylpyrrolidone solution dropwise to the system over 30 min. After the addition is complete, heat the system temperature to 100 °C and stir at 800 rpm for 8 h. After the reaction is complete, pour 500 mL of ice water into the system to precipitate the product. Filter and wash with ethanol until neutral. Then dry the product at 80 °C to constant weight to obtain the polyethylene stiffening modifier.

[0005] The various reaction conditions and parameters in the preparation method of the polyethylene stiffening modifier described in this invention are all optimal conditions that have been experimentally verified.

[0006] The reaction temperature and time of this invention are determined based on the boiling point and reactivity of the solvent, and the above-mentioned reaction conditions are the optimal conditions verified by experiments.

[0007] The present invention has been verified that the solvents, their amounts, temperatures, and drying conditions used in the impurity removal process during the reaction are all determined based on the solubility of the impurities that may appear during the reaction and the boiling point of the solvent. The above-mentioned impurity removal methods are all optimal conditions verified by experiments, which can fully remove unreacted impurities and ensure economy. In addition, if the drying temperature of the product is too high or too low, the drying effect cannot be guaranteed.

[0008] The present invention also provides an application of a polyethylene stiffening modifier in polyethylene, wherein the amount of the polyethylene stiffening modifier is 0.01%-1% of the polyethylene mass.

[0009] Preferably, the amount of the polyethylene stiffening modifier is 0.5% of the polyethylene mass.

[0010] The amount of the polyethylene stiffening modifier synthesized in this invention must be appropriate. Too little addition will not achieve the desired effect, while too much addition will reach the upper limit of performance improvement, resulting in waste of the polyethylene stiffening modifier. The above-mentioned addition amount is the optimal condition verified by experiments.

[0011] Compared with the prior art, the present invention has the following technical effects.

[0012] 1. The rigid benzene ring structure in the molecular chain of the polyethylene stiffening modifier described above can inhibit the movement of the polyethylene molecular chain, enhance its resistance to deformation, and thus improve its rigidity.

[0013] 2. The aforementioned polyethylene stiffening modifier has the ability to form a lattice match with polyethylene, which can effectively improve its crystal structure and thus enhance its rigidity. Specific implementation methods

[0014] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. The polyethylene (grade: 5502S), melamine (CAS: 108-78-1), biphenyl-4-formyl chloride (CAS: 14002-51-8), and benzoyl chloride (CAS: 98-88-4) used in the present invention are all commercially available in the technical field.

[0015] Example 1 Add 1.6 mL of dry pyridine and 1.26 g of melamine to 100 mL of dry N-methylpyrrolidone, maintaining the system temperature at 0 °C. Dissolve 4.33 g of biphenyl-4-formyl chloride in 20 mL of N-methylpyrrolidone. Add the above biphenyl-4-formyl chloride N-methylpyrrolidone solution dropwise to the system over 30 min. After the addition is complete, heat the system to 100 °C and stir at 800 rpm for 8 h. After the reaction is complete, pour 500 mL of ice water into the system to precipitate the product. Filter and wash with ethanol until neutral. Then dry the product at 80 °C to constant weight to obtain intermediate product A. Add 1 mL of dry pyridine and 4.86 g of intermediate product A to 100 mL of dry N-methylpyrrolidone, maintaining the system temperature at 0 °C. Dissolve 2 g of benzoyl chloride in 20 mL of... N-methylpyrrolidone was prepared by adding the above-mentioned benzoyl chloride N-methylpyrrolidone solution dropwise to the system over 30 min. After the addition was completed, the system temperature was heated to 100 °C and stirred at 800 rpm for 8 h. After the reaction was completed, 500 mL of ice water was added to the system to precipitate the product. The product was filtered and washed with ethanol until neutral. Then, the product was dried at 80 °C to constant weight to obtain the polyethylene stiffening modifier. The polyethylene stiffening modifier and polyethylene were mixed in a high-speed mixer at a mass ratio of 0.5:100 (mixing speed 3000 rpm, mixing time 3 min). The mixture was then extruded and granulated in a conventional twin-screw extruder. Samples were prepared and their flexural modulus was measured according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0016] Example 2 This embodiment is basically the same as Embodiment 1, except that the polyethylene stiffening modifier synthesized in Embodiment 1 and polyethylene are used to prepare the sample at a mass ratio of 1:100. The test data are shown in Table 1.

[0017] Example 3 This embodiment is basically the same as Embodiment 1, except that the polyethylene stiffening modifier synthesized in Embodiment 1 and polyethylene are used to prepare the sample at a mass ratio of 0.01:100. The test data are shown in Table 1.

[0018] Comparative Example 1 After pure polyethylene was extruded and granulated in a conventional twin-screw extruder, the flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0019] Comparative Example 2 The raw materials melamine and polyethylene were extruded and granulated in a conventional twin-screw extruder at a mass ratio of 0.5:100. The flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0020] Comparative Example 3 The raw materials biphenyl-4-formyl chloride and polyethylene were extruded and granulated in a conventional twin-screw extruder at a mass ratio of 0.5:100. The flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0021] Comparative Example 4 Benzoyl chloride and polyethylene were extruded and granulated in a conventional twin-screw extruder at a mass ratio of 0.5:100. The flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0022] Comparative Example 5 Intermediate product A and polyethylene were extruded and granulated in a conventional twin-screw extruder at a mass ratio of 0.5:100. The flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0023] Comparative Example 6 4.86 g of intermediate product A and 2 g of benzoyl chloride were conventionally mixed in a high-speed mixer (mixing speed 3000 rpm, mixing time 3 min), and then extruded and granulated with polyethylene at a mass ratio of 0.5:100 in a conventional twin-screw extruder. The flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0024] Comparative Example 7 1.26 g of melamine, 4.33 g of biphenyl-4-carboxyl chloride and 2 g of benzoyl chloride were conventionally mixed in a high-speed mixer (mixing speed 3000 rpm, mixing time 3 min). Then, the mixture was extruded and granulated with polyethylene at a mass ratio of 0.5:100 in a conventional twin-screw extruder. The flexural modulus of the blend system was tested according to the method specified in GB / T 9341-2008. The specific data are shown in Table 1.

[0025] Table 1 Test results for each embodiment and comparative example Flexural modulus (MPa) Example 1 2909 Example 2 2684 Example 3 2432 Comparative Example 1 1605 Comparative Example 2 1634 Comparative Example 3 1599 Comparative Example 4 1585 Comparative Example 5 1854 Comparative Example 6 1881 Comparative Example 7 1600 According to the experimental results in Table 1, the flexural modulus of polyethylene in Examples 1-3 after adding the polyethylene stiffening modifier prepared in this invention is higher than that of the comparative example. The optimal addition amount is found in Example 1, with 1.5% addition. Compared to the pure polyethylene of Comparative Example 1, this demonstrates that the polyethylene stiffening modifier synthesized in this invention significantly improves the flexural modulus of polyethylene. Furthermore, both excessive and insufficient addition of the polyethylene stiffening modifier will adversely affect the flexural modulus of polyethylene.

[0026] The polyethylene stiffening modifier prepared in this invention is synthesized through a chemical reaction. Its rigid benzene ring structure in the molecular chain can inhibit the movement of polyethylene molecular chains, enhancing its resistance to deformation and thus improving its rigidity. Simultaneously, the polyethylene stiffening modifier has the ability to form a lattice match with polyethylene, effectively perfecting its crystal structure and significantly improving its rigidity. In contrast, Comparative Examples 2-6 only added single raw materials, intermediate products, or simple mixtures of raw materials, and therefore could not achieve the desired effect. Specifically, the melamine added in Comparative Example 2, the biphenyl-4-formyl chloride added in Comparative Example 3, and the benzoyl chloride added in Comparative Example 4 had little effect on the flexural modulus of polyethylene. The intermediate product A added in Comparative Example 5, with a stable structure formed through a chemical reaction, can act as a heterogeneous nucleating agent, promoting polyethylene crystallization and perfecting its crystal structure; therefore, its flexural modulus is higher than that of Comparative Examples 2, 3, and 4. Comparative Example 6, with the addition of intermediate product A and benzoyl chloride in a simple mixture, exhibits a weak chemical reaction during the high-temperature processing of polyethylene, generating a trace amount of the polyethylene stiffening modifier, thus increasing its flexural modulus compared to Comparative Example 5. Comparative Example 7, being a simple mixture of raw materials, cannot form the molecular structure of the polyethylene stiffening modifier described in this invention; therefore, its effect is weak.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A polyethylene stiffening modifier, characterized in that, Prepared as follows: S1. Add 1.6 mL of dry pyridine and 1.26 g of melamine to 100 mL of dry N-methylpyrrolidone, keeping the system temperature at 0 °C. Dissolve 4.33 g of biphenyl-4-formyl chloride in 20 mL of N-methylpyrrolidone. Add the above solution of biphenyl-4-formyl chloride in N-methylpyrrolidone to the system dropwise over 30 min. After the addition is complete, heat the system temperature to 100 °C and stir at 800 rpm for 8 h. After the reaction is complete, pour 500 mL of ice water into the system to precipitate the product. Filter and wash with ethanol until neutral. Then dry the product at 80 °C to constant weight to obtain intermediate product A. S2. Add 1 mL of dry pyridine and 4.86 g of intermediate product A to 100 mL of dry N-methylpyrrolidone. Keep the system temperature at 0 °C. Dissolve 2 g of benzoyl chloride in 20 mL of N-methylpyrrolidone. Add the above benzoyl chloride N-methylpyrrolidone solution dropwise to the system over 30 min. After the addition is complete, heat the system temperature to 100 °C and stir at 800 rpm for 8 h. After the reaction is complete, pour 500 mL of ice water into the system to precipitate the product. Filter and wash with ethanol until neutral. Then dry the product at 80 °C to constant weight to obtain the polyethylene stiffening modifier.

2. The application of the polyethylene stiffening modifier according to claim 1 in polyethylene, characterized in that, The amount of the polyethylene modifier used is 0.01%-1% of the polyethylene mass.

3. The application of the polyethylene stiffening modifier according to claim 2 in polyethylene, characterized in that, The amount of the polyethylene modifier used is 0.5% of the polyethylene mass.