TPU composite material and preparation method thereof

Abstract

The invention discloses a TPU composite material and a preparation method thereof.The preparation method comprises the following steps that a coupling agent is dropwise added into POSS dispersion liquid for a reaction, filtering, washing and drying are conducted after the reaction is completed, and coupling agent modified POSS is obtained; dispersing the coupling agent modified POSS and PCL in a solvent, carrying out a heating reaction, and after the reaction is completed, carrying out centrifugation, washing, drying and grinding to obtain PCL modified POSS; dispersing the activated two-dimensional nano material in an organic solvent, adding a hydrophobic cross-linking agent, uniformly mixing, heating for reaction, cooling, carrying out suction filtration, washing, and drying to obtain a modified two-dimensional nano material; and mixing the PCL modified POSS, the modified two-dimensional nano material and TPU particles, and carrying out basic granulation by adopting double screws to obtain the TPU composite material. According to the invention, the brittle fracture resistance toughness of the TPU composite material in an ultralow temperature environment and the hydrolysis resistance stability of the TPU composite material in long-term use are synchronously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a TPU composite material and a preparation method thereof. BACKGROUND

[0002] Thermoplastic polyurethane elastomer (TPU) is an important thermoplastic elastomer, which not only has high elasticity of rubber and high strength of engineering plastic, but also has excellent processing performance, and is widely used in many fields. However, the traditional TPU material faces a significant performance bottleneck: in the ultra-low temperature environment (such as-60℃), the molecular chain segment movement ability of the TPU material decreases sharply, and the TPU material is prone to brittle fracture and loss of elasticity; at the same time, the ester group or ether group in the molecular structure of the TPU material is prone to interact with water molecules, and after long-term use in a high-temperature and high-humidity environment, the TPU material is prone to hydrolytic degradation, resulting in a significant decrease in mechanical properties.

[0003] In the prior art, in order to improve the low-temperature performance of the TPU, a method of adding a plasticizer or a low glass transition temperature (Tg) elastomer is usually used, but the plasticizer is prone to migration, which causes performance degradation, and the compatibility of the elastomer blend with the TPU matrix is difficult to ensure; in order to enhance the hydrolysis resistance, a polyether type TPU is usually selected to replace a polyester type TPU, or a small molecule hydrolysis-resistant additive is added, however, the mechanical strength of the polyether type TPU is relatively low, and the polyether type TPU cannot meet the requirement of high tensile performance; patent application CN112318976A discloses a high-weather-resistant TPU composite material, which improves the weather resistance through a multi-layer coating structure, but the scheme mainly focuses on ultraviolet aging protection, and does not involve optimization of ultra-low temperature toughness, and the hydrolysis resistance depends on the synergistic effect of the hydrolysis-resistant PU adhesive and the additive, and a long-term protection mechanism cannot be constructed from the internal structure design of the material. In addition, most of the existing modification schemes are aimed at single performance optimization, and it is difficult to simultaneously improve the ultra-low temperature toughness and long-term hydrolysis resistance, thereby limiting the application of the TPU in extreme environments. SUMMARY

[0004] The application aims to overcome the deficiencies in the prior art, and provides a TPU composite material and a preparation method thereof, which simultaneously improve the brittle fracture resistance of the TPU composite material in an ultra-low temperature environment and the hydrolysis resistance during long-term use.

[0005] The application provides the following technical scheme: In a first aspect, a preparation method of a TPU composite material is provided, which comprises the following steps: The coupling agent modified POSS is obtained by adding a coupling agent dropwise into a POSS dispersion liquid for reaction, and then filtering, washing and drying after the reaction is completed; The PCL modified POSS is obtained by dispersing the coupling agent modified POSS and PCL in a solvent for warming reaction, and then centrifuging, washing, drying and grinding after the reaction is completed. The activated two-dimensional nanomaterial is dispersed in an organic solvent, a hydrophobic crosslinking agent is added, mixed, and heated to react, and then cooled, filtered, washed, and dried to obtain a modified two-dimensional nanomaterial. The PCL modified POSS and the modified two-dimensional nanomaterial are mixed with TPU particles, and a double screw is used for basic granulation to obtain a TPU composite material.

[0006] Further, the preparation method of the POSS dispersion liquid comprises: dispersing POSS nanometer powder in anhydrous ethanol, and ultrasonic dispersion.

[0007] Further, the pH value of the POSS dispersion liquid is adjusted to 2-4, and then a coupling agent is added dropwise for reaction, the reaction temperature is 80-110 DEG C, and the reaction time is 4-6 h.

[0008] In the above technical solution, the pH value of the POSS dispersion liquid is adjusted to 2-4, which is helpful for the hydrolysis of the coupling agent under acidic conditions, and then the reaction with the surface group of POSS is realized to realize the surface modification of the coupling agent on POSS.

[0009] Further, the mass ratio of POSS in the POSS dispersion liquid to the coupling agent is 1: (0.5-1).

[0010] In the above technical solution, if the mass of the coupling agent is higher than the above-mentioned limited mass range, the coupling agent will react to cause self-polymerization, resulting in poor modification effect; if the mass of the coupling agent is lower than the above-mentioned limited mass range, the modification effect on POSS will be poor.

[0011] Further, the coupling agent is one or more of N-(2-aminoethyl) methacrylamide, gamma-glycidyl ether propyl trimethoxysilane, and gamma-(methacryloyloxy) propyl trimethoxysilane.

[0012] Further, the coupling agent modified POSS and PCL are dispersed in a solvent at a mass ratio of 1: (0.08-0.15), heated to 80-120 DEG C for reaction, and the reaction time is 2-4 h.

[0013] In the above technical solution, if the reaction temperature is too low (lower than 80 DEG C), the modification effect will be poor, if the temperature is too high (higher than 120 DEG C), the PCL will be invalid; and the reaction time is too short, which will cause insufficient reaction.

[0014] Further, the activation method of the two-dimensional nanomaterial comprises: placing the two-dimensional nanomaterial under nitrogen protection for activation, the activation temperature is 120-230 DEG C, and the activation time is 1-3 h.

[0015] Further, the two-dimensional nanomaterial is one or both of nanomontmorillonite and nanohydrotalcite.

[0016] Further, the activated two-dimensional nanomaterial is dispersed in an organic solvent, a hydrophobic crosslinking agent is added, and ultrasonic mixing is performed until uniform, and then heating is performed to 60-100℃, and reaction is performed for 0.5-2h.

[0017] In the above technical solution, if the reaction temperature is lower than 60℃, the modification effect of the two-dimensional nanomaterial is poor, and if the temperature is higher than 100℃, the hydrophobic crosslinking agent groups self-polymerize and lose effectiveness; and if the reaction time is too short, the reaction is insufficient.

[0018] Further, the mass ratio of the activated two-dimensional nanomaterial to the hydrophobic crosslinking agent is 1:0.3.

[0019] Further, the hydrophobic crosslinking agent is one or more of p-chlorophenyl isocyanate, p-methylphenyl isocyanate, and thiodiisocyanate.

[0020] Further, the mixing mass ratio of the PCL modified POSS, the modified two-dimensional nanomaterial, and the TPU particles is (4-8):(2-4):100.

[0021] In the above technical solution, if the mass of the PCL modified POSS and the modified two-dimensional nanomaterial is low, the low-temperature resistance and hydrolysis resistance of the TPU composite material are reduced; and if the mass of the PCL modified POSS and the modified two-dimensional nanomaterial is high, the performance of the TPU composite material is reduced due to the agglomeration of the POSS and the two-dimensional material.

[0022] Further, the TPU is a polyester TPU.

[0023] In a second aspect, a TPU composite material prepared by the method of any one of the first aspect is provided.

[0024] Compared with the prior art, the present application has the following beneficial effects: (1) The present application realizes chemical grafting of PCL on the surface of POSS through a coupling agent; on the one hand, PCL has good compatibility with TPU, realizes uniform dispersion of POSS in the TPU, and the POSS can effectively reduce the Tg of the soft segment of the TPU, so that the material can still maintain the movement ability of the molecular chain at a lower temperature; on the other hand, the molecular chain flexibility of the PCL soft segment is good, which can effectively reduce the crystallinity of the material, thereby improving the dynamic performance of the TPU at low temperature, so the low-temperature resistance of the TPU is significantly improved through the joint action of the two; at the same time, the large molecular space and the grafted hydrophobic functional groups reduce the contact area between the matrix and water, thereby improving the hydrophobic performance of the TPU composite material; (2) The rigid skeleton of the two-dimensional nanomaterial used in the application can support the soft segment structure of the TPU, reduce the brittleness caused by the crystallization of the hard segment at low temperature; the two-dimensional material is modified by using a hydrophobic crosslinking agent which is compatible with TPU, which can improve the dispersibility of the two-dimensional nanomaterial and further improve the hydrophobic performance of the product; in addition, the use of zero-dimensional materials alone may reduce the active sites due to aggregation, while the two-dimensional nanomaterial is easy to stack and reduce the specific surface area, after compounding, the zero-dimensional material can disperse the two-dimensional sheet layer to prevent agglomeration, and the two-dimensional material provides a stable carrier for the zero-dimensional particles, maximizes the use of the characteristics of both, which helps to further improve the low-temperature resistance and hydrolysis resistance of the TPU composite material; (3) The preparation method provided by the application simultaneously realizes the improvement of the anti-brittle fracture toughness of the TPU composite material in the ultra-low temperature environment and the hydrolysis resistance stability in long-term use, and can be widely applied to oil storage materials, sports tents and sealing materials in low-temperature and humid environments. DETAILED DESCRIPTION

[0025] The following examples are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0026] Example 1

[0027] 1. Preparation of modified POSS.

[0028] 1.1, 100g of POSS nanometer powder was vacuum dried at 90℃ for 5h, added into 1500mL of anhydrous ethanol, and ultrasonically dispersed for 25min to obtain a POSS dispersion liquid.

[0029] 1.2, Coupling agent modification: the pH of the POSS dispersion liquid was adjusted to 3.5 with dilute hydrochloric acid, 50g of KH560 modifier was added, and stirring reaction was carried out at 80℃ for 4h, then the product was filtered and washed with ethanol, and dried to obtain the coupling agent modified POSS.

[0030] 1.3, Composite modifier grafting: 8g of PCL was dissolved in 100mL of anhydrous ethanol, and then slowly added into 60g of the coupling agent modified POSS, and the temperature was raised to 80℃, and stirring reaction was carried out for 3h.

[0031] 1.4, Post-treatment: the product was centrifuged and washed with anhydrous ethanol for 4 times, and vacuum dried at 75℃ for 7h, and then ground to obtain the modified POSS nanomaterial.

[0032] 2. Preparation of modified two-dimensional nanomaterial.

[0033] 2.1, The montmorillonite was put into a three-necked flask, heated to 210℃ under nitrogen protection, and activated for 2h to obtain activated montmorillonite.

[0034] 2.2、In a three-necked flask, under nitrogen protection, the activated montmorillonite and dithiodiisocyanate were added into anhydrous toluene at a mass ratio of 1:0.3, stirred and mixed for 30 min; heated to 80°C and reacted for 80 min; then naturally cooled, filtered, washed, and dried at 40°C under vacuum to obtain modified montmorillonite nanosheets.

[0035] 3. Preparation of TPU composite material.

[0036] After 8 parts of modified POSS nanomaterial (particle size 10 nm), 4 parts of modified montmorillonite nanosheet (aspect ratio 100:1), and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) were uniformly mixed, they were added into a twin-screw extruder and extruded at 190°C to obtain TPU masterbatch.

[0037] Example 2

[0038] 1. Preparation of modified POSS.

[0039] 1.1. 100 g of POSS nanometer powder was vacuum dried at 90°C for 5 h, added into 1500 mL of anhydrous ethanol, and ultrasonically dispersed for 25 min to obtain a POS dispersion.

[0040] 1.2. Coupling agent modification: the pH of the POSS dispersion was adjusted to 3.5 with dilute hydrochloric acid, 50 g of KH560 modifier was added, and stirred at 80°C for 4 h, then filtered, washed with ethanol, and dried to obtain coupling agent modified POSS.

[0041] 1.3. Composite modifier grafting: 8 g of PCL was dissolved in 100 mL of anhydrous ethanol, slowly added into 60 g of coupling agent modified POSS, and heated to 80°C for stirring reaction for 3 h.

[0042] 1.4. Post-treatment: the product was centrifuged, washed with anhydrous ethanol 4 times, vacuum dried at 75°C for 7 h, and ground to obtain modified POSS nanomaterial.

[0043] 2. Preparation of modified two-dimensional nanomaterial.

[0044] 2.1. Hydrotalcite was weighed into a three-necked flask, heated to 210°C under nitrogen protection, and activated for 2 h to obtain activated hydrotalcite.

[0045] 2.2. In a three-necked flask, under nitrogen protection, the activated hydrotalcite and dithiodiisocyanate were added into anhydrous toluene at a mass ratio of 1:0.3, stirred and mixed for 30 min. Heated to 80°C and reacted for 80 min. Naturally cooled, filtered, washed, and dried at 40°C under vacuum to obtain modified hydrotalcite nanosheet.

[0046] 3. Preparation of TPU composite material.

[0047] 8 parts of modified POSS nanomaterial (particle size 10 nm), 4 parts of modified hydrotalcite nanosheet (aspect ratio 100:1) and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) were uniformly mixed and then added to a twin-screw extruder to be extruded at 190°C to obtain TPU masterbatch.

[0048] Example 3

[0049] 1. Preparation of modified POSS.

[0050] 1.1. 100 g of POSS nanometer powder was vacuum dried at 90°C for 5 h, added to 1500 mL of anhydrous ethanol, and ultrasonically dispersed for 25 min to obtain a POS dispersion.

[0051] 1.2. Coupling agent modification: the pH of the POSS dispersion was adjusted to 3.5 with dilute hydrochloric acid, 50 g of KH560 modifier was added, and the mixture was stirred at 80°C for 4 h, then filtered and washed with ethanol, and dried to obtain coupling agent modified POSS.

[0052] 1.3. Composite modifier grafting: 8 g of PCL was dissolved in 100 mL of anhydrous ethanol, slowly added to 60 g of coupling agent modified POSS, and the mixture was heated to 80°C and stirred for 3 h.

[0053] 1.4. Post-treatment: the product was centrifuged and washed with anhydrous ethanol 4 times, vacuum dried at 75°C for 7 h, and ground to obtain modified POSS nanomaterial.

[0054] 2. Preparation of modified two-dimensional nanomaterial.

[0055] 2.1. Montmorillonite was weighed into a three-necked flask, heated to 210°C under nitrogen protection, and activated for 2 h to obtain activated montmorillonite.

[0056] 2.2. In a three-necked flask, the activated montmorillonite and dithiodiisocyanate were added to anhydrous toluene under nitrogen protection at a mass ratio of 1:0.3, stirred and mixed for 30 min, heated to 80°C, and reacted for 80 min. The mixture was naturally cooled, filtered, washed, and vacuum dried at 40°C to obtain modified montmorillonite nanosheet.

[0057] 3. Preparation of TPU composite material.

[0058] 6 parts of modified POSS nanomaterial (particle size 10 nm), 2 parts of modified montmorillonite nanosheet (aspect ratio 100:1) and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) were uniformly mixed and then added to a twin-screw extruder to be extruded at 190°C to obtain TPU masterbatch.

[0059] Example 4

[0060] 1. Preparation of modified POSS.

[0061] 1.1, Take 100g of POSS nanometer powder, vacuum drying at 90℃ for 5h, add 1500ml of anhydrous ethanol, ultrasonic dispersion for 25min, get POSS dispersion.

[0062] 1.2, Coupling agent modification: adjust the pH of POSS dispersion to 3.5 with dilute hydrochloric acid, add 50g of KH560 modifier, stir at 80℃ for 4h, then filter and wash with ethanol, dry to get coupling agent modified POSS.

[0063] 1.3, Composite modifier grafting: weigh 8g of PCL dissolved in 100ml of anhydrous ethanol, slowly drop into 60g of coupling agent modified POSS, heat to 80℃, stir for 3h.

[0064] 1.4, Post-processing: centrifugal separation of the product, washed with anhydrous ethanol 4 times, vacuum drying at 75℃ for 7h, grinding to get modified POSS nanometer material.

[0065] 2. Preparation of modified two-dimensional nanometer material.

[0066] 2.1, Take montmorillonite into a three-necked flask, heat to 210℃ under nitrogen protection, activate for 2h to get activated montmorillonite.

[0067] 2.2, In a three-necked flask, under nitrogen protection, add activated montmorillonite and p-chlorophenyl isocyanate with mass ratio of 1:0.3 into anhydrous toluene, stir and mix for 30min. Heat to 80℃, react for 80min. Cool naturally, filter, wash, vacuum drying at 40℃ to get modified montmorillonite nanosheet.

[0068] 3. Preparation of TPU composite material.

[0069] Mix 8 parts of modified POSS nanometer material (particle size 10nm), 4 parts of modified montmorillonite nanosheet (aspect ratio 100:1) and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) uniformly, then add into a twin screw extruder, extrude into TPU masterbatch at 190℃.

[0070] Example 5

[0071] 1. Preparation of modified POSS.

[0072] 1.1, Take 100g of POSS nanometer powder, vacuum drying at 90℃ for 5h, add 1500ml of anhydrous ethanol, ultrasonic dispersion for 25min, get POSS dispersion.

[0073] 1.2, Coupling agent modification: the pH of the POSS dispersion is adjusted to 3.5 with dilute hydrochloric acid, 50 g of KH560 modifier is added, and stirring is carried out at 80°C for 4 h, then filtered and washed with ethanol, dried to obtain coupling agent modified POSS.

[0074] 1.3, Composite modifier grafting: 15 g of PCL is dissolved in 100 mL of anhydrous ethanol, slowly added dropwise into 60 g of coupling agent modified POSS, and the temperature is raised to 80°C, and stirring is carried out for 3 h.

[0075] 1.4, Post-treatment: the product is centrifuged, washed with anhydrous ethanol 4 times, vacuum dried at 75°C for 7 h, and ground to obtain modified POSS nanomaterial.

[0076] 2, Preparation of modified two-dimensional nanomaterials.

[0077] 2.1, Montmorillonite is weighed into a three-necked flask, heated to 210°C under nitrogen protection, and activated for 2 h to obtain activated montmorillonite.

[0078] 2.2, In a three-necked flask, the activated montmorillonite is added to anhydrous toluene under nitrogen protection, and the mass ratio of dithiodiisocyanate is 1:0.3, stirring, mixing and dispersing for 30 min. Heat to 80°C and react for 80 min. Naturally cool, filter, wash, and vacuum dry at 40°C to obtain modified montmorillonite nanosheet.

[0079] 3, Preparation of TPU composite material.

[0080] 8 parts of modified POSS nanomaterial (particle size 10 nm), 4 parts of modified montmorillonite nanosheet (aspect ratio 100:1), and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) are mixed uniformly, then added to a twin-screw extruder, and extruded into a TPU masterbatch at 190°C.

[0081] Example 6

[0082] 1, Preparation of modified POSS.

[0083] 1.1, 100 g of POSS nanometer powder is vacuum dried at 90°C for 5 h, added to 1500 mL of anhydrous ethanol, and ultrasonically dispersed for 25 min to obtain a POSS dispersion.

[0084] 1.2, Coupling agent modification: the pH of the POSS dispersion is adjusted to 3.5 with dilute hydrochloric acid, 50 g of KH560 modifier is added, and stirring is carried out at 80°C for 4 h, then filtered and washed with ethanol, dried to obtain coupling agent modified POSS.

[0085] 1.3, Complex modifier grafting: 8 g of PCL was dissolved in 100 mL of anhydrous ethanol, and was slowly added dropwise into 60 g of the coupling agent modified POSS, and was heated to 110°C, and was stirred for 3 h.

[0086] 1.4, Post-processing: The product was centrifuged, washed with anhydrous ethanol 4 times, vacuum dried at 75°C for 7 h, and was ground to obtain the modified POSS nanomaterial.

[0087] 2, Preparation of modified two-dimensional nanomaterials.

[0088] 2.1, Montmorillonite was weighed into a three-necked flask, and was heated to 210°C under nitrogen protection for 2 h to obtain activated montmorillonite.

[0089] 2.2, In a three-necked flask, the activated montmorillonite was added into anhydrous toluene under nitrogen protection, and was mixed and dispersed with dithiodiisocyanate at a mass ratio of 1:0.3 for 30 min. It was heated to 80°C and reacted for 80 min. It was naturally cooled, filtered, washed, and vacuum dried at 40°C to obtain modified montmorillonite nanosheets.

[0090] 3, Preparation of TPU composite.

[0091] 8 parts of modified POSS nanomaterial (particle size 10 nm), 4 parts of modified montmorillonite nanosheet (aspect ratio 100:1), and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) were uniformly mixed, and were added into a twin-screw extruder, and were extruded and molded at 190°C to obtain TPU masterbatch.

[0092] Comparative Example 1 1, Preparation of modified POSS.

[0093] 1.1, 100 g of POSS nanometer powder was vacuum dried at 90°C for 5 h, was added into 1500 mL of anhydrous ethanol, and was ultrasonically dispersed for 25 min to obtain a POSS dispersion.

[0094] 1.2, Coupling agent modification: the pH of the POSS dispersion was adjusted to 3.5 with dilute hydrochloric acid, 50 g of KH560 modifier was added, and was stirred and reacted at 80°C for 4 h. Then it was filtered, washed with ethanol, and dried to obtain coupling agent modified POSS.

[0095] 1.3, Complex modifier grafting: 8 g of PCL was dissolved in 100 mL of anhydrous ethanol, and was slowly added dropwise into 60 g of the coupling agent modified POSS, and was heated to 80°C, and was stirred for 3 h.

[0096] 1.4, Post-processing: The product was centrifuged, washed with anhydrous ethanol 4 times, vacuum dried at 75°C for 7 h, and was ground to obtain the modified POSS nanomaterial.

[0097] 2. Preparation of TPU composite material.

[0098] 8 parts of modified POSS nanomaterial (particle size 10 nm) and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) were mixed uniformly and then added to a twin-screw extruder for extrusion molding at 190°C to obtain TPU masterbatch.

[0099] Comparative Example 2 1. Preparation of modified two-dimensional nanomaterial.

[0100] 1.1. Put montmorillonite into a three-necked flask, heat to 210°C under nitrogen protection, and activate for 2h to obtain activated montmorillonite.

[0101] 1.2. In a three-necked flask, add activated montmorillonite and dithiodiisocyanate in a mass ratio of 1:0.3 to anhydrous toluene under nitrogen protection, stir, mix and disperse for 30min; heat to 80°C and react for 80min; then naturally cool, suction filter, wash, and vacuum dry at 40°C to obtain modified montmorillonite nanosheet.

[0102] 2. Preparation of TPU composite material.

[0103] 4 parts of modified montmorillonite nanosheet (aspect ratio 100:1) and 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) were mixed uniformly and then added to a twin-screw extruder for extrusion molding at 190°C to obtain TPU masterbatch.

[0104] Comparative Example 3 The same 100 parts of polyester TPU (hard segment content 30%, number average molecular weight 100000) as in Example 1 were added to a twin-screw extruder for extrusion molding at 190°C to obtain TPU masterbatch.

[0105] Performance test example The TPU masterbatch prepared in Examples 1-6 and Comparative Examples 1-3 was used to prepare TPU film with a thickness of 0.3mm by extrusion casting method, and the film was cut into rectangular samples with a width of 15mm and a gauge of 50mm according to the standard.

[0106] 1. Test of elongation at break in low temperature environment.

[0107] The sample was placed in a precisely controlled low temperature environment of -60°C (such as a refrigerator or thermostat at -60°C) for 24h to ensure sufficient temperature conduction. After taking out, the product was restored for 0.5h in standard environment (23±2°C), and then the elongation at break of the product was tested, with the results shown in Table 1 below.

[0108] 2. Test of shrinkage in low temperature environment.

[0109] The initial size (L0) of the sample was measured at room temperature. Then the sample was placed in a precisely controlled low temperature environment (-60°C, such as a refrigerator or a thermostat at -60°C) for 24 h to ensure sufficient temperature conduction. After taking out, it was restored for 0.5 h in a standard environment (23±2°C), and then its final size (L1) was measured. The shrinkage (or contraction) rate was calculated by the following formula: shrinkage rate = (L0-L1) / L0x 100%. The results are shown in Table 1 below.

[0110] 3. Hydrolysis strength retention test

[0111] The sample was soaked in 70°C distilled water for 500 h, and the mechanical property retention rate was tested. The results are shown in Table 1. Table 1 Performance test table of TPU composite sample in Example 1-Example 6

[0112] As can be seen from Table 1, by comparing the performance of the samples of the comparative examples and the comparative examples, it is found that POSS and two-dimensional nanomaterials can improve the low-temperature resistance and hydrolysis resistance of the material, but the combination of the two can have a synergistic effect to play an advantage, further improving the comprehensive performance of the product such as low-temperature resistance and hydrolysis resistance. In addition, by comparing Example 1 and Example 2, it is found that montmorillonite has better hydrolysis resistance than hydrotalcite, because montmorillonite has a significant water molecule blocking effect; by comparing Example 1 and Example 3, it can be seen that with the addition of POSS and two-dimensional nanomaterials, the low-temperature resistance and hydrolysis resistance of the TPU composite material are significantly improved; by comparing Example 1 and Example 4, it can be found that dithiodiisocyanate has excellent hydrolysis resistance compared with chlorophenyl isocyanate, because the disulfide bond in dithiodiisocyanate has strong hydrophobicity; by comparing Example 1 and Example 5, it is found that with the increase of the amount of PCL, the comprehensive performance of the product increases; by comparing Example 1 and Example 6, it is found that with the increase of the amount of PCL grafted on the surface of POSS with the increase of the modification temperature, the performance of the product increases.

[0113] The application realizes the chemical grafting of PCL on the surface of POSS by a coupling agent; on the one hand, PCL has good compatibility with TPU, realizing the uniform dispersion of POSS in the TPU, and the Tg of the soft segment of TPU can be effectively reduced, so that the material can still maintain the movement ability of molecular chains at a lower temperature; on the other hand, the molecular chain flexibility of PCL soft segment is good, which can effectively reduce the crystallinity of the material, thereby improving the dynamic performance of TPU at low temperature, so the low-temperature resistance of TPU is significantly improved by the joint action of the two; at the same time, the large molecular space and the grafted hydrophobic functional groups reduce the contact area between the matrix and water, and improve the hydrophobic performance of the TPU composite material; the rigid skeleton of the two-dimensional nanometer material used in the application can support the soft segment structure of TPU, reducing the brittleness caused by the crystallization of hard segments at low temperature; the two-dimensional material is modified by using a hydrophobic crosslinking agent which has good compatibility with TPU, which can improve the dispersion of two-dimensional nanometer materials and further improve the hydrophobic performance of the product; in addition, the use of zero-dimensional materials alone may reduce active sites due to aggregation, and two-dimensional nanometer materials are easy to stack and reduce specific surface area, after compounding, zero-dimensional materials can disperse two-dimensional layers to prevent agglomeration, and two-dimensional materials provide a stable carrier for zero-dimensional particles, maximizing the use of the characteristics of the two, which helps to further improve the low-temperature resistance and hydrolysis resistance of the TPU composite material; the preparation method provided by the application simultaneously realizes the improvement of the anti-brittle fracture toughness of the TPU composite material in the super-low temperature environment and the hydrolysis resistance stability during long-term use, and can be widely used in oil storage materials, sports tents and sealing materials in low-temperature and humid environments.

[0114] The above only describes the preferred embodiments of the application, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the application, and these improvements and modifications should also be considered as the protection scope of the application.

Claims

1. A method of making a TPU composite material, characterized in that, The method comprises the following steps: The coupling agent modified POSS is obtained by adding the coupling agent dropwise into the POSS dispersion liquid for reaction, filtering, washing and drying after the reaction is completed; The PCL modified POSS is obtained by dispersing the coupling agent modified POSS and PCL in a solvent for reaction, centrifuging, washing, drying and grinding after the reaction is completed; The modified two-dimensional nanomaterial is obtained by dispersing the activated two-dimensional nanomaterial in an organic solvent, adding a hydrophobic crosslinking agent, uniformly mixing, heating for reaction, cooling, suction filtering, washing and drying after the reaction; The TPU composite material is obtained by mixing the PCL modified POSS, the modified two-dimensional nanomaterial and TPU particles, and performing basic granulation by using a double screw.

2. The method of claim 1, wherein the TPU composite is prepared by a process comprising: The preparation method of the POSS dispersion liquid comprises the following steps: dispersing POSS nanometer powder in anhydrous ethanol, and ultrasonic dispersion.

3. The method of claim 1, wherein the TPU composite is prepared by a process comprising: The coupling agent is added dropwise for reaction after the pH value of the POSS dispersion liquid is adjusted to 2-4, the reaction temperature is 80-110 DEG C, and the reaction time is 4-6 h. The mass ratio of the POSS in the POSS dispersion liquid to the coupling agent is 1:(0.5-1).

4. The method of claim 1, wherein the TPU composite is prepared by a process comprising: The coupling agent is one or more of N-(2-aminoethyl) methacrylamide, γ-glycidyl ether propyl trimethoxysilane and γ-(methacryloyloxy) propyl trimethoxysilane.

5. The method of claim 1, wherein the TPU composite is prepared by a process comprising: The coupling agent modified POSS and PCL are dispersed in a solvent in a mass ratio of 1:(0.08-0.15), and the reaction is performed by heating to 80-120 DEG C for 2-4 h.

6. The method of making a TPU composite of claim 1, wherein, The activation method of the two-dimensional nanomaterial comprises the following steps: placing the two-dimensional nanomaterial under nitrogen protection for activation, the activation temperature is 120-230 DEG C, and the activation time is 1-3 h.

7. The method of claim 1, wherein the TPU composite is prepared by a process comprising: The two-dimensional nanomaterial is one or both of nanometer montmorillonite and nanometer hydrotalcite.

8. The method of claim 1, wherein the TPU composite is prepared by a process comprising: The activated two-dimensional nanomaterial is dispersed in an organic solvent, the hydrophobic crosslinking agent is ultrasonic mixed uniformly, and then heating is performed to 60-100 DEG C for 0.5-2 h. The mass ratio of the activated two-dimensional nanomaterial to the hydrophobic crosslinking agent is 1:0.

3. The hydrophobic crosslinking agent is one or more of p-chlorophenyl isocyanate, p-methylphenyl isocyanate and thiodiisocyanate.

9. The method of making a TPU composite of claim 1, wherein, The mixing mass ratio of the PCL modified POSS, the modified two-dimensional nanomaterial and TPU particles is (4-8):(2-4):

100. The TPU is polyester TPU.

10. A TPU composite material prepared by the method in any one of claims 1-9.

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