Shape memory polyurethane resin, rectifying tower filler prepared from shape memory polyurethane resin and preparation methods of shape memory polyurethane resin and rectifying tower filler

Abstract

The invention relates to the technical field of organic polymer materials, in particular to shape memory polyurethane resin, rectifying tower filler prepared from the same and preparation methods of the shape memory polyurethane resin and the rectifying tower filler. The preparation method comprises the following steps: by taking hydroxyl-terminated polybutadiene and polytetrahydrofuran ether glycol as soft segments and toluene diisocynate as a hard segment, forming a prepolymer under the action of a chain extender 2-ethyl-1, 3-hexanediol, and carrying out end-group end capping by adopting alpha-hydroxyl and omega-epoxy polycaprolactone oligomer, so as to obtain a shape memory polyurethane material; carrying out melt blending on the synthesized shape memory polyurethane resin, a polypropylene matrix, maleic anhydride modified polybutadiene rubber and a maleic anhydride grafted polypropylene compatilizer, and carrying out high-temperature shear plasticizing, granulation and injection molding through a double-screw extruder, so as to prepare the rectifying tower filler with excellent mechanical strength, corrosion resistance and self-adaptive shape recovery characteristics. According to the technical scheme, through molecular structure design and compound process optimization, the mechanical performance and working condition adaptability of traditional polypropylene filler are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic polymer materials, and particularly to a shape memory polyurethane resin, a rectifying column packing prepared therefrom, and preparation methods for both. Background Art

[0002] As a tower-type gas-liquid mass transfer device, the working principle of a rectifying column is based on the difference in the volatility of each component in a mixture. By promoting the vaporization and migration of low-boiling components in the liquid phase to the gas phase, while the high-boiling components in the gas phase condense into the liquid phase, material separation is ultimately achieved. Generally, according to the contact method, rectifying columns can be divided into two major categories: continuous contact type (packed column) and stage-by-stage contact type (plate column). In a packed column, resin packings such as polypropylene packings exhibit significant advantages: relatively low fluid resistance, relatively low unit mass transfer height, relatively high flooding critical value, and with sufficient gas-liquid contact effect, making it an ideal choice for improving the distillation separation efficiency.

[0003] Long-term exposure to the high-temperature environment of a rectifying column will cause the polypropylene packing to become brittle or lose its strength, resulting in the collapse or breakage of the packing layer, shortening the packing life, reducing the rectification efficiency, and increasing the maintenance cost. Thermoplastic polyurethane elastomers combine the high elasticity of rubber materials and the processing performance of thermoplastic plastics, with excellent wear resistance, oil resistance, and corrosion resistance, and can effectively cope with chemical corrosion in a rectifying column. Moreover, since it belongs to a thermally induced shape memory polymer material, it not only exhibits better mechanical properties at high temperatures but also can achieve dynamic adjustment of shape through temperature stimulation to optimize the mass transfer efficiency of the packed column. By blending a thermoplastic polyurethane elastomer with shape memory function with polypropylene to prepare a rectifying column packing, the service life can be extended. However, existing literature shows that due to the poor compatibility between the two, even when a compatibilizer is added during blending, too high a dosage of polyurethane will cause a reduction in the performance of the mixture (Wang Ying, Du Wuqing, Zhong Huiting, etc. Research on the mechanical properties and micro-morphology of polypropylene / thermoplastic polyurethane composites [J]. China Plastics Industry, 2020, 48(10): 134-137+149.). Therefore, new modification methods need to be tried. Summary of the Invention

[0004] The purpose of the present invention is to provide a shape memory polyurethane resin, a rectifying column packing prepared therefrom, and preparation methods for both, so as to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the present invention provides the following technical solution: A preparation method for a shape memory polyurethane resin, comprising the following steps: Step 1: Using lipase Novozym-435 as a catalyst, ε-caprolactone and glycidol were added to toluene under argon protection, and the mixture was stirred at 60-65 °C for 24 h. After adding chloroform to terminate the reaction, lipase Novozym-435 was removed by filtration. The filtrate was added to n-hexane for precipitation, and the precipitate was washed with n-hexane and then dried in vacuo at 50-60 °C to obtain α-hydroxy, ω-epoxy polycaprolactone oligomer; Step 2: Hydroxyl-terminated polybutadiene and polytetrahydrofuran glycol were taken, vacuum dried and dehydrated, and then mixed to obtain a mixed diol. Using dibutyltin dilaurate as a catalyst, toluene diisocyanate was added to the mixed diol, and the reaction was carried out at 65-75 °C for 2-3 h to obtain a prepolymer. 2-Ethyl-1,3-hexanediol was added as a chain extender and the reaction was continued for 0.5-1 h to obtain an isocyanate-terminated polyurethane prepolymer; α-Hydroxy, ω-epoxy polycaprolactone oligomer was added for reaction to obtain a shape memory polyurethane resin.

[0006] Furthermore, in step 1, the number average molecular weight of the α-hydroxy, ω-epoxy polycaprolactone oligomer is 1500-2000.

[0007] Furthermore, in step 1, the dosage of each component, by weight, is 0.5-0.7 parts of lipase Novozym-435, 1-2 parts of glycidol, 10-12 parts of ε-caprolactone, and 20-25 parts of toluene.

[0008] Furthermore, in step 2, in the mixed diol, the weight ratio of hydroxyl-terminated polybutadiene to polytetrahydrofuran glycol is (1-1.5):5.

[0009] Furthermore, in step 2, the mixed diol and toluene diisocyanate react according to the molar ratio of hydroxyl group to isocyanate group of (0.8-0.9):(1.5-2).

[0010] Furthermore, in step 2, the molar ratio of 2-ethyl-1,3-hexanediol to toluene diisocyanate is (0.3-0.5):(1.5-2).

[0011] Furthermore, in step 2, the α-hydroxy, ω-epoxy polycaprolactone oligomer and the isocyanate-terminated polyurethane prepolymer react according to the molar ratio of hydroxyl group to isocyanate group of 1:1.

[0012] A method for preparing a rectification column packing from a shape memory polyurethane resin, comprising the following steps: S1: Mix polypropylene, maleic anhydride modified polybutadiene rubber and maleic anhydride grafted polypropylene, heat to 50-60°C and keep for 3-5 minutes, add shape memory polyurethane resin, vulcanizer and accelerator and mix evenly, add to the upstream feeding port of twin-screw extruder for mixing, extrude tie rods and granulate to obtain polypropylene composite material; S2: Cooling the polypropylene composite material and vacuum drying it for 4 to 6 hours; injection molding the dried polypropylene composite material and cooling it to obtain a distillation tower filler.

[0013] Furthermore, in S1, the amount of each component, by weight, is 100 parts of polypropylene, 10-12 parts of maleic anhydride modified polybutadiene rubber, 5-8 parts of maleic anhydride grafted polypropylene, 18-23 parts of shape memory polyurethane resin, 0.2-0.3 parts of vulcanizing agent, and 0.05-0.1 parts of accelerator.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention first uses hydroxy-terminated polybutadiene, polytetramethylene glycol, and toluene diisocyanate as raw materials, uses 2-ethyl-1,3-hexanediol as a chain extender, and uses α-hydroxy, ω-epoxy polycaprolactone oligomer as a capping agent to react and obtain a shape memory polyurethane resin. The shape memory polyurethane resin, polypropylene, maleic anhydride-modified polybutadiene rubber, and maleic anhydride-grafted polypropylene are mixed, melt-extruded, and granulated to obtain a polypropylene composite material, which is then injection molded and cooled to obtain a distillation tower filler.

[0015] Normally, due to the difference in polarity, the compatibility of polyurethane and polypropylene is poor, and it is difficult to obtain a composite material with excellent performance by direct blending. In the present invention, maleic anhydride-modified polybutadiene rubber and maleic anhydride-grafted polypropylene are added as compatibilizers to reduce the interfacial tension between polyurethane and polypropylene, thereby solving the problem of incompatibility between the two after blending. On the one hand, maleic anhydride-modified polybutadiene rubber and the polyurethane resin prepared in the present invention both contain polybutadiene molecular segments, and the molecular structures of the two are similar; and maleic anhydride-grafted polypropylene and polypropylene also have similar molecular structures, so during melt blending, components with similar structures have better compatibility with each other and are easier to mix; and after maleic anhydride-grafted polypropylene is mixed with polypropylene, the polarity of the latter is improved, thereby improving the compatibility between polypropylene and polyurethane.

[0016] In addition, in the present invention, since the end groups of the polyurethane resin are epoxy groups, a chemical reaction can occur between them and maleic anhydride. The components form an interpenetrating three-dimensional network structure through physical crosslinking and chemical bonding. Compared with single polypropylene, the composite material prepared in the present invention has good mechanical properties and shape memory function, overcomes the disadvantages of poor toughness and easy deformation at high temperature of polypropylene, and can effectively increase the service life when used as a distillation column packing in the chemical distillation stage, reduce the maintenance cost in industrial production operation, and improve economic benefits. Description of the Drawings

[0017] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings: Figure 1 is a cross-sectional SEM electron microscope scanning image of the distillation column packing in Example 1 of the present invention (magnification: 2000 times). Detailed Embodiments

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0019] The materials used in the present invention and their sources: Polypropylene comes from Beijing Yanshan Petrochemical Co., Ltd., model M2600R; Maleic anhydride-modified polybutadiene rubber comes from Evonik Industries AG of Germany, model MA-75; Maleic anhydride-grafted polypropylene comes from ExxonMobil of the United States, model PO 1020; The vulcanizing agent is dicumyl peroxide, and the accelerator is dibenzothiazole disulfide, both from Hebi Yuanhao New Materials Group Co., Ltd.; Hydroxyl-terminated polybutadiene comes from Shandong Zero Degree New Materials Co., Ltd., model LBH 2000; Poly(tetramethylene ether) glycol comes from Jining Lidu Chemical Co., Ltd., with an average molecular weight of 2000.

[0020] Example 1: A preparation method of a distillation column packing prepared from a shape memory polyurethane resin, comprising the following steps: Step 1: Take 100 kg of polypropylene, 12 kg of maleic anhydride-modified polybutadiene rubber, and 6 kg of maleic anhydride-grafted polypropylene, mix them, heat to 50 °C and hold for 3 min, add 21 kg of shape memory polyurethane resin, 0.27 kg of vulcanizing agent, and 0.08 kg of accelerator, mix them evenly, add them to the upstream feeding port of a twin-screw extruder for mixing, extrude and draw into strands, and pelletize to obtain a polypropylene composite material; Among them, the preparation method of the shape memory polyurethane resin comprises the following steps: S1: Using lipase Novozym-435 as a catalyst, ε-caprolactone and glycidol were added to toluene under argon protection, and the mixture was stirred at 60 °C for 24 h. After adding chloroform to terminate the reaction, lipase Novozym-435 was removed by filtration. The filtrate was added to n-hexane for precipitation, and the precipitate was washed with n-hexane and then vacuum-dried at 50 °C to obtain α-hydroxy, ω-epoxy polycaprolactone oligomer with a number-average molecular weight of 1500. Among them, the dosage of each component was: 0.5 kg of lipase Novozym-435, 1 kg of glycidol, 12 kg of ε-caprolactone, and 25 kg of toluene; S2: Hydroxyl-terminated polybutadiene and polytetrahydrofuran glycol were taken, vacuum-dried and dehydrated, and then mixed to obtain a mixed diol. Using dibutyltin dilaurate as a catalyst, toluene diisocyanate was added to the mixed diol, and the reaction was carried out at 65 °C for 2 h to obtain a prepolymer. 2-Ethyl-1,3-hexanediol was added as a chain extender and the reaction was continued for 0.5 h to obtain an isocyanate-terminated polyurethane prepolymer; α-Hydroxy, ω-epoxy polycaprolactone oligomer was added for reaction to obtain a shape memory polyurethane resin; Among them, in the mixed diol, the weight ratio of hydroxyl-terminated polybutadiene to polytetrahydrofuran glycol was 1:5; the mixed diol; the mixed diol and toluene diisocyanate reacted according to a molar ratio of hydroxyl group to isocyanate group of 0.8:1.6; the molar ratio of 2-ethyl-1,3-hexanediol to toluene diisocyanate was 0.4:1.6; α-Hydroxy, ω-epoxy polycaprolactone oligomer and isocyanate-terminated polyurethane prepolymer reacted according to a molar ratio of hydroxyl group to isocyanate group of 1:1.

[0021] Step 2: After the polypropylene composite material was cooled, it was vacuum-dried for 4 h; the dried polypropylene composite material was injection-molded and cooled to form a rectification tower packing.

[0022] Example 2: A preparation method of a rectification tower packing prepared from a shape memory polyurethane resin, comprising the following steps: Step 1: Take 100 kg of polypropylene, 10 kg of maleic anhydride-modified polybutadiene rubber, and 5 kg of maleic anhydride-grafted polypropylene, heat to 55 °C and keep for 4 min, add 18 kg of shape memory polyurethane resin, 0.2 kg of vulcanizing agent, and 0.05 kg of accelerator, mix evenly, and add to the upstream feeding port of a twin-screw extruder for mixing, extrude and pelletize to obtain a polypropylene composite material; Among them, the preparation method of the shape memory polyurethane resin comprises the following steps: S1: Using lipase Novozym-435 as a catalyst, ε-caprolactone and glycidol were added to toluene under argon protection, and the mixture was stirred at 63 °C for 24 h. After adding chloroform to terminate the reaction, the lipase Novozym-435 was removed by filtration. The filtrate was added to n-hexane for precipitation, and the precipitate was washed with n-hexane and then vacuum dried at 55 °C to obtain α-hydroxy, ω-epoxy polycaprolactone oligomer with a number average molecular weight of 1800. Among them, the dosage of each component was: 0.6 kg of lipase Novozym-435, 1.4 kg of glycidol, 10 kg of ε-caprolactone, and 20 kg of toluene; S2: Take hydroxyl-terminated polybutadiene and polytetrahydrofuran ether diol, vacuum dry and dehydrate them, and then mix them to obtain a mixed diol. Using dibutyltin dilaurate as a catalyst, toluene diisocyanate was added to the mixed diol, and the reaction was carried out at 70 °C for 2.5 h to obtain a prepolymer. 2-Ethyl-1,3-hexanediol was added as a chain extender and the reaction was continued for 0.5 h to obtain an isocyanate-terminated polyurethane prepolymer; React with α-hydroxy, ω-epoxy polycaprolactone oligomer to obtain a shape memory polyurethane resin; Among them, in the mixed diol, the weight ratio of hydroxyl-terminated polybutadiene to polytetrahydrofuran ether diol is 1.2:5; the mixed diol; the mixed diol and toluene diisocyanate react according to a molar ratio of hydroxyl group to isocyanate group of 0.8:1.5; the molar ratio of 2-ethyl-1,3-hexanediol to toluene diisocyanate is 0.3:1.5; the α-hydroxy, ω-epoxy polycaprolactone oligomer and the isocyanate-terminated polyurethane prepolymer react according to a molar ratio of hydroxyl group to isocyanate group of 1:1.

[0023] Step 2: Cool the polypropylene composite material and then vacuum dry it for 5 h; Carry out injection molding and cooling molding on the dried polypropylene composite material to obtain a distillation column packing.

[0024] Example 3: A preparation method of a distillation column packing prepared from a shape memory polyurethane resin, comprising the following steps: Step 1: Take 100 kg of polypropylene, 11 kg of maleic anhydride-modified polybutadiene rubber, and 8 kg of maleic anhydride-grafted polypropylene, heat to 60 °C and hold for 4 min, add 23 kg of shape memory polyurethane resin, 0.3 kg of vulcanizing agent, and 0.1 kg of accelerator, mix evenly, and add them to the upstream feeding port of a twin-screw extruder for mixing, extrude and pelletize to obtain a polypropylene composite material; Among them, the preparation method of the shape memory polyurethane resin comprises the following steps: S1: Using lipase Novozym-435 as a catalyst, ε-caprolactone and glycidol were added to toluene under argon protection, and the mixture was stirred at 65 °C for 24 h. After adding chloroform to terminate the reaction, the lipase Novozym-435 was removed by filtration. The filtrate was added to n-hexane for precipitation, and the precipitate was washed with n-hexane and then vacuum dried at 60 °C to obtain α-hydroxy, ω-epoxy polycaprolactone oligomer with a number average molecular weight of 2000. Among them, the dosage of each component was: 0.7 kg of lipase Novozym-435, 2 kg of glycidol, 11 kg of ε-caprolactone, and 23 kg of toluene. S2: Hydroxyl-terminated polybutadiene and polytetrahydrofuran ether diol were taken, vacuum dried and dehydrated, and then mixed to obtain a mixed diol. Using dibutyltin dilaurate as a catalyst, toluene diisocyanate was added to the mixed diol, and the reaction was carried out at 75 °C for 3 h to obtain a prepolymer. 2-Ethyl-1,3-hexanediol was added as a chain extender and the reaction was continued for 0.5 - 1 h to obtain an isocyanate-terminated polyurethane prepolymer. The α-hydroxy, ω-epoxy polycaprolactone oligomer was added for reaction to obtain a shape memory polyurethane resin. Among them, in the mixed diol, the weight ratio of hydroxyl-terminated polybutadiene to polytetrahydrofuran ether diol was 1.5:5; the mixed diol; the mixed diol and toluene diisocyanate were reacted according to a molar ratio of hydroxyl group to isocyanate group of 0.9:2; the molar ratio of 2-ethyl-1,3-hexanediol to toluene diisocyanate was 0.5:2; the α-hydroxy, ω-epoxy polycaprolactone oligomer and the isocyanate-terminated polyurethane prepolymer were reacted according to a molar ratio of hydroxyl group to isocyanate group of 1:1.

[0025] Step 2: After cooling the polypropylene composite material, it was vacuum dried for 6 h; the dried polypropylene composite material was injection molded and cooled to form a distillation column packing.

[0026] Comparative Example 1: A conventional thermoplastic polyurethane resin (model polyether type 1180A, BASF (China) Co., Ltd.) was used as a raw material to prepare a distillation column packing, and the other parameters were the same as those in Example 1.

[0027] Step 1: 100 kg of polypropylene, 12 kg of maleic anhydride-modified polybutadiene rubber, and 6 kg of maleic anhydride-grafted polypropylene were taken, heated to 50 °C and maintained for 3 min, 21 kg of shape memory polyurethane resin, 0.27 kg of vulcanizing agent, and 0.08 kg of accelerator were added and mixed evenly, and then added to the upstream feeding port of a twin-screw extruder for mixing, extrusion, drawing, and pelletizing to obtain a polypropylene composite material. Step 2: After cooling the polypropylene composite material, it was vacuum dried for 4 h; the dried polypropylene composite material was injection molded and cooled to form a distillation column packing.

[0028] Comparative Example 2: Without adding maleic anhydride modified polybutadiene rubber, and the remaining parameters are the same as those in Example 2.

[0029] Step 1: Take 100 kg of polypropylene and 5 kg of maleic anhydride grafted polypropylene, mix them, heat to 55 °C and keep for 4 min, add 18 kg of shape memory polyurethane resin, 0.2 kg of vulcanizing agent, and 0.05 kg of accelerator, mix evenly, add them to the upstream feeding port of a twin-screw extruder for mixing, extrude and draw into strands, and granulate to obtain a polypropylene composite material; Among them, the preparation method of the shape memory polyurethane resin includes the following steps: S1: Using lipase Novozym-435 as a catalyst, under argon protection, add ε-caprolactone and glycidyl to toluene, stir and react at 63 °C for 24 h, add chloroform to terminate the reaction, filter to remove lipase Novozym-435, add the filtrate to n-hexane for precipitation, wash the precipitate with n-hexane, and then vacuum dry at 55 °C to obtain α-hydroxy, ω-epoxy polycaprolactone oligomer with a number average molecular weight of 1800; among them, the dosage of each component is: 0.6 kg of lipase Novozym-435, 1.4 kg of glycidyl, 10 kg of ε-caprolactone, and 20 kg of toluene; S2: Take hydroxyl-terminated polybutadiene and polytetrahydrofuran ether diol, vacuum dry and dehydrate them, then mix to obtain a mixed diol. Using dibutyltin dilaurate as a catalyst, add toluene diisocyanate to the mixed diol, react at 70 °C for 2.5 h to obtain a prepolymer, add 2-ethyl-1,3-hexanediol as a chain extender and continue to react for 0.5 h to obtain an isocyanate-terminated polyurethane prepolymer; add α-hydroxy, ω-epoxy polycaprolactone oligomer to react to obtain a shape memory polyurethane resin; Among them, in the mixed diol, the weight ratio of hydroxyl-terminated polybutadiene to polytetrahydrofuran ether diol is 1.2:5; the mixed diol; the mixed diol and toluene diisocyanate react according to a molar ratio of hydroxyl group to isocyanate group of 0.8:1.5; the molar ratio of 2-ethyl-1,3-hexanediol to toluene diisocyanate is 0.3:1.5; the α-hydroxy, ω-epoxy polycaprolactone oligomer and the isocyanate-terminated polyurethane prepolymer react according to a molar ratio of hydroxyl group to isocyanate group of 1:1.

[0030] Step 2: Cool the polypropylene composite material and then vacuum dry it for 5 h; perform injection molding processing and cooling molding on the dried polypropylene composite material to obtain a distillation column packing.

[0031] Comparative Example 3: Without adding shape memory polyurethane resin, and the remaining parameters are the same as those in Example 3.

[0032] Step 1: Take 100 kg of polypropylene, 11 kg of maleic anhydride modified polybutadiene rubber, and 8 kg of maleic anhydride grafted polypropylene, mix them, heat to 60 °C and keep for 4 min, add 0.3 kg of vulcanizing agent and 0.1 kg of accelerator, mix evenly, add them to the upstream feeding port of the twin-screw extruder for mixing, extrude and draw into strips, and pelletize to obtain the polypropylene composite material; Step 2: Cool the polypropylene composite material and then vacuum dry it for 6 h; perform injection molding processing and cooling molding on the dried polypropylene composite material to obtain the distillation column packing.

[0033] Experiment: Refer to the preparation methods in Examples 1-3 and Comparative Examples 1-3 to prepare samples of the polypropylene composite material for performance experiment tests. The experimental methods are as follows: Impact performance: Use a pendulum impact testing machine, prepare a V-notch using a notch sample preparation machine, refer to the standard of GB / T 1043.1-2018, the number of test specimens in each group is 5, and calculate the average value.

[0034] Tensile performance: Use an electronic universal testing machine, refer to the standard of GB / T 1040.2-2006, the tensile speed is 35 mm / min, the number of test specimens in each group is 5, and calculate the average value.

[0035] Heat resistance performance: Take 10 samples in each group, place them in a vacuum oven at 180 °C for 300 h respectively, take them out and place them in a vacuum drying environment at 25 °C to cool naturally, and test and observe whether the samples show collapse deformation, cracking and other situations.

[0036] Deformation recovery rate: Select a standard specimen and take 50 mm on the sample as the initial gauge length L0, heat it to 165 °C in the hot box of the testing machine and keep for 5 min; perform a tensile setting test on the specimen at a rate of 20 mm / min and a tensile ratio of 80%, cool it at 25 °C for 24 h after setting, measure its gauge length and record it as L1; finally, place the specimen in an oven at 170 °C for deformation recovery for 3 min, take it out and measure its gauge length and record it as L2, and calculate the deformation recovery rate R = (L1 - L2) / (L1 - L0) The experimental results are shown in the following table: Table 1. Test results of various performance of each group of samples

[0037] Analyze the cross-sectional morphology of the distillation column packing in Example 1 by SEM electron microscopy.

[0038] Conclusion: The data of Examples 1 to 3 show that the shape memory polyurethane resin prepared by the present invention can effectively improve the properties of polypropylene, and the filler made of the modified polypropylene composite material can be applied to a distillation column. The data of Example 1 and Comparative Example 1 show that compared with the conventional thermoplastic polyurethane resin, the shape memory polyurethane resin prepared by the present invention has better compatibility with polypropylene, and the obtained polypropylene composite material has higher impact strength, tensile strength, heat resistance, and more excellent shape memory effect. The data of Example 2 and Comparative Example 2 show that maleic anhydride-modified polybutadiene rubber can effectively reduce the interfacial tension between polypropylene and the shape memory polyurethane resin, increase the compatibility between the two, and improve the properties of the polypropylene composite material. The data of Example 3 and Comparative Example 3 show that the properties of the polypropylene material prepared without adding the shape memory polyurethane resin are all poor.

[0039] Figure 1 In the electron micrograph, no obvious phase separation appears. Combining with other data, it shows that the improvement of compatibility has improved the properties of the polypropylene composite material.

[0040] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a shape memory polyurethane resin, characterized in that: It includes the following steps: Step 1: Using lipase Novozym-435 as a catalyst, ε-caprolactone and glycidyl are added to toluene under argon protection, and stirred at 60-65 °C for 24 h. After adding chloroform to terminate the reaction, the lipase Novozym-435 is filtered off. The filtrate is added to n-hexane for precipitation, and the precipitate is washed with n-hexane and then vacuum dried at 50-60 °C to obtain α-hydroxy, ω-epoxy polycaprolactone oligomer; Among them, by weight, 0.5-0.7 parts of lipase Novozym-435, 1-2 parts of glycidyl, 10-12 parts of ε-caprolactone, 20-25 parts of toluene; Step 2: Take hydroxyl-terminated polybutadiene and polytetrahydrofuran ether diol, vacuum dry and dehydrate them, and then mix them to obtain a mixed diol. Using dibutyltin dilaurate as a catalyst, toluene diisocyanate is added to the mixed diol, and the reaction is carried out at 65-75 °C for 2-3 h to obtain a prepolymer. 2-Ethyl-1,3-hexanediol is added as a chain extender and the reaction is continued for 0.5-1 h to obtain an isocyanate-terminated polyurethane prepolymer; α-Hydroxy, ω-epoxy polycaprolactone oligomer is added for reaction to obtain a shape memory polyurethane resin; Among them, in the mixed diol, the weight ratio of hydroxyl-terminated polybutadiene to polytetrahydrofuran ether diol is (1-1.5):5; the mixed diol and toluene diisocyanate react according to the molar ratio of hydroxyl group to isocyanate group (0.8-0.9):(1.5-2); the molar ratio of 2-ethyl-1,3-hexanediol to toluene diisocyanate is (0.3-0.5):(1.5-2); α-Hydroxy, ω-epoxy polycaprolactone oligomer and isocyanate-terminated polyurethane prepolymer react according to the molar ratio of hydroxyl group to isocyanate group 1:

1.

2. The preparation method of a shape memory polyurethane resin according to claim 1, characterized in that: In Step 1, the number average molecular weight of the α-hydroxy, ω-epoxy polycaprolactone oligomer is 1500-2000.

3. A shape memory polyurethane resin prepared by the preparation method according to any one of claims 1-2.

4. A method for preparing a rectifying column packing from the shape memory polyurethane resin as described in claim 3, characterized in that: It includes the following steps: S1: Take polypropylene, maleic anhydride-modified polybutadiene rubber, and maleic anhydride-grafted polypropylene, mix them, heat to 50-60 °C and keep for 3-5 min, add the shape memory polyurethane resin, vulcanizing agent, and accelerator and mix evenly, add them to the upstream feeding port of a twin-screw extruder for mixing, extrude and draw into strips, and granulate to obtain a polypropylene composite material; S2: Cool the polypropylene composite material and then vacuum dry it for 4-6 h; carry out injection molding processing and cooling molding on the dried polypropylene composite material to obtain a rectification tower packing.

5. A method for preparing a rectifying column packing from the shape memory polyurethane resin as described in claim 4, characterized in that: In S1, the dosage of each component, by weight, is 100 parts of polypropylene, 10-12 parts of maleic anhydride-modified polybutadiene rubber, 5-8 parts of maleic anhydride-grafted polypropylene, 18-23 parts of shape memory polyurethane resin, 0.2-0.3 parts of vulcanizing agent, and 0.05-0.1 parts of accelerator.

6. A rectification tower packing prepared by the preparation method according to any one of claims 4-5.

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