High near infrared reflection polyurethane and preparation method thereof

Abstract

The invention discloses high near infrared reflection polyurethane and a preparation method thereof, the high near infrared reflection polyurethane has a general formula 1, in the formula, x, y and z are random copolymerization chain segment numbers, and x, y and z are independently any integer greater than 0; r1 is (CH2) n, and n is an integer larger than or equal to 3 and smaller than or equal to 9; r2 is C8H17, C10H21 or # imgabs0 #. The high near-infrared reflection polyurethane disclosed by the invention has excellent mechanical property, good thermal stability and high near-infrared reflection performance, solves the problems that the optical property of perylene diimide molecules is influenced and the application processing performance is poor, and can be used for preparing a high near-infrared reflection material.

Description

Technical Field

[0001] The present application belongs to the technical field of high near-infrared reflective materials, and specifically relates to a high near-infrared reflective polyurethane and a preparation method thereof. Background Art

[0002] Near-infrared (NIR) radiation (700-2500nm) accounts for 52% of solar radiation, but most materials cannot effectively reflect near-infrared radiation, resulting in increased material internal energy and environmental heat accumulation, accelerated material loss and increased energy consumption such as refrigeration, leading to an increasingly serious urban heat island effect, with urban areas being hotter than surrounding rural areas. Some studies have shown that using materials with high near-infrared reflectivity is an effective way to reduce the heat island effect.

[0003] So far, near-infrared reflective pigments can be mainly divided into two categories: metal oxide pigments and organic pigments. Among metal oxide pigments, light-colored pigments such as titanium dioxide have a higher near-infrared reflectivity, and organic pigments such as perylene diimide have a higher near-infrared reflectivity. Compared with metal oxide pigments, organic pigments have the advantages of low cost, low toxicity, high compatibility, and good processing performance. Therefore, the preparation of organic pigments with high near-infrared reflectivity has become a research hotspot in recent years.

[0004] Perylene-based pigments have chemical stability, high colorability and excellent optical properties, and are widely used in the high-performance pigment industry. Related literature reports that perylene diimide has a unique π-conjugated skeleton and a highly symmetrical rectangular shape. These characteristics give perylene diimide high activity and near-infrared absorption bands, and the strong π-π conjugation between molecules makes it exhibit excellent thermal stability and photoelectric properties. However, the large conjugated plane and rigid structure in perylene diimide (PDI) molecules easily lead to strong π-π stacking between molecules, thereby affecting its optical properties and bringing great challenges to the application and processing of PDI molecules. Summary of the invention

[0005] The purpose of the present application is to provide a high near-infrared reflective polyurethane and a preparation method thereof, so as to solve the problem in the prior art that the large conjugated plane and rigid structure in the perylene diimide (PDI) molecule easily lead to strong π-π stacking between molecules, thereby affecting its optical properties and bringing great challenges to the application and processability of the PDI molecule.

[0006] In order to achieve the above-mentioned object, the first aspect of the present application provides a high near-infrared reflective polyurethane having the following general formula 1:

[0007] [General formula 1]

[0008]

[0009] In the general formula 1, x, y, and z are the number of random copolymer segments, and x, y, and z are each independently any integer greater than 0;

[0010] R1 is (CH2) n , where n is an integer greater than or equal to 3 and less than or equal to 9;

[0011] R2 is C8H 17 , C 10 H 21 or

[0012] In one or more embodiments, the high near infrared reflective polyurethane has the following general formula 2:

[0013] [General formula 2]

[0014]

[0015]

[0016] In the general formula 2, x, y, and z are the numbers of random copolymer segments, and x, y, and z are each independently any integer greater than 0.

[0017] In order to achieve the above object, the second aspect of the present application provides a method for preparing a highly near-infrared reflective polyurethane, comprising:

[0018] Poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG and isophorone diisocyanate are reacted to obtain a first intermediate product having the following general formula 3;

[0019] The first intermediate product and terephthalic acid dihydrazide are reacted under the catalysis of dibutyltin dilaurate DBTDL to obtain a second intermediate product having the following general formula 4;

[0020] The second intermediate product is reacted with a perylene diimide having the following general formula 5 to obtain a high near-infrared reflective polyurethane having the following general formula 1;

[0021] [General formula 3]

[0022]

[0023] [General formula 4]

[0024]

[0025] [General formula 5]

[0026]

[0027] [General formula 1]

[0028]

[0029] In each of the general formulas 1, 3, 4, and 5, x, y, and z are the numbers of random copolymer segments, and x, y, and z are each independently any integer greater than 0;

[0030] R1 is (CH2) n , where n is an integer greater than or equal to 3 and less than or equal to 9;

[0031] R2 is C8H 17 , C 10 H 21 or

[0032] In one or more embodiments, the step of reacting poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG and isophorone diisocyanate comprises:

[0033] Heat poly-ε-caprolactone PCDL and polytetramethylene ether glycol PTMG to 115-125° C. under vacuum conditions and dry for 1.5-2.5 hours;

[0034] Inert gas is introduced into the system, and then the temperature is lowered to 70-80° C., isophorone diisocyanate is added, and the reaction is stirred for 2.5-3.5 hours to obtain the first intermediate product.

[0035] In one or more embodiments, the molar ratio of the poly-ε-caprolactone PCDL, the polytetramethylene ether glycol PTMG and the isophorone diisocyanate is (0.8-1.2):(0.8-1.2):(4.5-5.5).

[0036] In one or more embodiments, the step of reacting the first intermediate product with terephthalic acid dihydrazide under the catalysis of dibutyltin dilaurate DBTDL comprises:

[0037] An organic solvent is added to the first intermediate product at 60-70° C., and then terephthalic acid dihydrazide and dibutyltin dilaurate are dissolved in the organic solvent and added to the system, and the reaction is carried out at a constant temperature for 2.5-3.5 hours to obtain the second intermediate product.

[0038] In one or more embodiments, the molar ratio of the poly-ε-caprolactone to terephthalic acid dihydrazide is (0.8-1.2): (1.8-2.2).

[0039] In one or more embodiments, the step of reacting the second intermediate product with a perylene diimide having the general formula 5 comprises:

[0040] Adding the perylene diimide dissolved in an organic solvent to the second intermediate product at 60-70° C., and reacting at a constant temperature for 2.5-3.5 hours;

[0041] The reacted solution is poured into a mold, dried at 35-45° C. for 11-13 hours, then heated to 45-55° C. for further drying for 11-13 hours, and then heated to 55-65° C. for further drying for 11-13 hours to obtain the highly near-infrared reflective polyurethane.

[0042] In one or more embodiments, the molar ratio of the poly-ε-caprolactone to perylene diimide is (0.8-1.2): (0.049-0.050).

[0043] In order to achieve the above objectives, the third aspect of the present application provides a use of the high near-infrared reflective polyurethane described in any of the above embodiments or the high near-infrared reflective polyurethane prepared by the preparation method described in any of the above embodiments in the preparation of high near-infrared reflective materials.

[0044] Different from the prior art, the beneficial effects of this application are:

[0045] The present application adopts perylene diimide (PDI) grafted polyurethane to synthesize a highly near-infrared reflective polyurethane containing PDI in essence. The material has excellent mechanical properties, good thermal stability and high near-infrared reflective performance, solves the problem that the optical properties are affected by the presence of perylene diimide molecules and the application and processing performance is poor, and can be used to prepare highly near-infrared reflective materials;

[0046] The preparation method of the high near-infrared reflective polyurethane of the present application is simple, and has the advantages of low cost and easy operation;

[0047] The high near-infrared reflective polyurethane of the present application has the characteristics of being pollution-free, having good processing performance, being beneficial to environmental protection, and meeting the requirements of green chemistry, and is expected to be industrialized and applied on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of PU-PDI-1 of Example 1 of the present application;

[0050] Figure 2 is the infrared spectrum of PU-PDI-1 of Example 1 of the present application;

[0051] Figure 3 is a one-dimensional X-ray diffraction pattern of PU-PDI-1 of Example 1 of the present application;

[0052] Figure 4 is the UV-visible absorption spectrum of PU-PDI-1 of Example 1 of the present application;

[0053] Figure 5 It is a transmission spectrum of PU-PDI-1 of Example 1 of the present application and PU of Comparative Example 1;

[0054] Figure 6 is the thermogravimetric curve of PU-PDI-1 of Example 1 of the present application and PU of Comparative Example 1;

[0055] Figure 7 : are stress-strain curves of PU-PDI-1 of Example 1 of the present application and PU of Comparative Example 1;

[0056] Figure 8 This is the near-infrared reflection spectrum of PU-PDI-1 of Example 1 of the present application. DETAILED DESCRIPTION

[0057] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0058] Currently, the large conjugated plane and rigid structure in perylene diimide (PDI) molecules easily lead to strong π-π stacking between molecules, thereby affecting their optical properties and posing great challenges to the application and processability of PDI molecules.

[0059] There are two main strategies for developing near-infrared reflective materials containing perylene diimide (PDI). One is to synthesize polymers with near-infrared reflective properties that contain PDI intrinsically, and the other is to physically dope PDI additives with near-infrared reflective properties into the polymer matrix. The absorption and emission characteristics of perylene-based materials are easily affected by the intermolecular distance and the relative orientation of the chromophore molecules. In comparison, although the method of doping chromophores is highly versatile, in the actual application and processing process, polymers containing PDI intrinsically can better ensure the overall dispersion of PDI and avoid high accumulation between perylene cores, so that the material maintains good near-infrared reflective properties.

[0060] Therefore, in order to solve the problem that the optical properties of the current perylene diimide (PDI) molecules are affected and the application and processing performance is poor, the applicant has developed a near-infrared reflective material containing perylene diimide (PDI), which is obtained by covalently combining perylene diimide (PDI) with polyurethane to obtain a polymer containing PDI essentially.

[0061] Polyurethane is widely used in textile, construction, aviation, shipbuilding, transportation, medicine, electronics and other fields due to its strong plasticity, good elasticity and chemical resistance. Among them, thermoplastic polyurethane elastomer has better impact resistance, resilience and processing performance. The introduction of polyurethane not only ensures that PDI optically active molecules have sufficient dispersion space, but also provides excellent stability and mechanical properties, which brings significant advantages to the transportation and storage of materials.

[0062] Specifically, the high near-infrared reflective polyurethane of the present application has the following general formula 1:

[0063] [General formula 1]

[0064]

[0065] In Formula 1, x, y, and z are the numbers of random copolymer segments, and x, y, and z are each independently any integer greater than 0;

[0066] R1 is (CH2) n , where n is an integer greater than or equal to 3 and less than or equal to 9;

[0067] R2 is C8H 17 , C 10 H 21 or

[0068] Wherein, LDCP is poly-ε-caprolactone PCDL, and PTMG is polytetramethylene ether glycol.

[0069] In a more specific embodiment, the high near-infrared reflective polyurethane of the present application may have the following general formula 2:

[0070] [General formula 2]

[0071]

[0072] In Formula 2, x, y, and z are the numbers of random copolymer segments, and x, y, and z are each independently any integer greater than 0.

[0073] The present application also provides a method for preparing a high near-infrared reflective polyurethane according to any of the above embodiments, comprising:

[0074] S100, reacting poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG and isophorone diisocyanate to obtain a first intermediate product having a general formula 3.

[0075] [General formula 3]

[0076]

[0077] In one embodiment, the molar ratio of poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG, and isophorone diisocyanate may be (0.8-1.2):(0.8-1.2):(4.5-5.5).

[0078] In one implementation, S100 may specifically include:

[0079] Heat poly-ε-caprolactone PCDL and polytetramethylene ether glycol PTMG to 115-125° C. under vacuum conditions and dry for 1.5-2.5 hours;

[0080] Inert gas is introduced into the system, and then the temperature is lowered to 70-80° C., isophorone diisocyanate is added, and the reaction is stirred for 2.5-3.5 hours to obtain a first intermediate product.

[0081] The inert gas may be nitrogen, argon, or the like.

[0082] Specifically, the reaction formula of S100 can be as follows:

[0083]

[0084] S200, reacting the first intermediate product with terephthalic acid dihydrazide under the catalysis of dibutyltin dilaurate DBTDL to obtain a second intermediate product having the general formula 4.

[0085] [General formula 4]

[0086]

[0087] In one embodiment, the molar ratio of poly-ε-caprolactone to terephthalic acid dihydrazide in S100 may be (0.8-1.2):(1.8-2.2).

[0088] In one implementation, S200 may specifically include:

[0089] An organic solvent is added to the first intermediate product at 60-70° C., and then terephthalic acid dihydrazide and dibutyltin dilaurate are dissolved in the organic solvent and added to the system, and the reaction is carried out at a constant temperature for 2.5-3.5 hours to obtain a second intermediate product.

[0090] In one embodiment, the organic solvent may be anhydrous DMF.

[0091] Specifically, the reaction formula of S200 may be as follows:

[0092]

[0093] S300, reacting the second intermediate product with perylene diimide of general formula 5 to obtain a high near-infrared reflective polyurethane of general formula 1.

[0094] [General formula 5]

[0095]

[0096] [General formula 1]

[0097]

[0098] In one embodiment, the molar ratio of poly-ε-caprolactone to perylene diimide in S100 may be (0.8-1.2):(0.049-0.050).

[0099] In one embodiment, S300 specifically includes:

[0100] Adding perylene diimide dissolved in an organic solvent to the second intermediate product at 60-70° C. and reacting at a constant temperature for 2.5-3.5 hours;

[0101] The reacted solution is poured into a mold, dried at 35-45° C. for 11-13 hours, then heated to 45-55° C. for further drying for 11-13 hours, and then heated to 55-65° C. for further drying for 11-13 hours to obtain a highly near-infrared reflective polyurethane.

[0102] Wherein, the organic solvent can be anhydrous DMF.

[0103] The beneficial effects of the technical solution of the present application are further elaborated in detail below in conjunction with specific embodiments.

[0104] Embodiment 1:

[0105] A high near-infrared reflective polyurethane, the structural formula is as follows:

[0106]

[0107] The high near-infrared reflective polyurethane is prepared by the following steps:

[0108] Weigh 2 g of poly-ε-caprolactone (1 mmol) and 1 g of polytetramethylene ether glycol (1 mmol), heat to 120 °C and dry for 2 h under vacuum;

[0109] The system was filled with nitrogen, cooled to 80°C, 1.11 g of isophorone diisocyanate (5 mmol) was added, and the reaction was stirred for 3 h;

[0110] The temperature was lowered to 65°C, 20 ml of anhydrous DMF was added to the reaction system, and then 0.39 g of terephthalic acid dihydrazide (2 mmol) was dissolved in 5 mL of anhydrous DMF and 2 drops of dibutyltin dilaurate were added to the reaction system, and the reaction was continued at a constant temperature for 3 h.

[0111] Weigh 0.045 g PDI-OH (0.0495 mmol, ) was dissolved in anhydrous DMF (5 ml), then added to the reaction system and reacted at constant temperature for 3 h;

[0112] The reaction solution was poured into a silica gel mold, dried at 40°C for 12 h, heated to 50°C for 12 h, and then heated to 60°C for 12 h to obtain an orange transparent perylene diimide grafted polyurethane material (PU-PDI-1), i.e., a high near-infrared reflective polyurethane.

[0113] Embodiment 2:

[0114] A high near-infrared reflective polyurethane, the structural formula is as follows:

[0115]

[0116] The high near-infrared reflective polyurethane is prepared by the following steps:

[0117] Weigh 2.4 g of poly-ε-caprolactone (1.2 mmol) and 0.8 g of polytetramethylene ether glycol (0.8 mmol), heat to 120 °C and dry for 2 h under vacuum;

[0118] The system was filled with nitrogen, cooled to 80°C, 1.0 g of isophorone diisocyanate (4.5 mmol) was added, and the reaction was stirred for 3 h;

[0119] The temperature was lowered to 65°C, 20 ml of anhydrous DMF was added to the reaction system, and then 0.43 g of terephthalic acid dihydrazide (2.2 mmol) was dissolved in 5 mL of anhydrous DMF and 2 drops of dibutyltin dilaurate were added to the reaction system, and the reaction was continued at a constant temperature for 3 h.

[0120] Weigh 0.0349 g PDI-OH (0.050 mmol, ) was dissolved in anhydrous DMF (5 ml), then added to the reaction system and reacted at constant temperature for 3 h;

[0121] The reaction solution was poured into a silica gel mold, dried at 40°C for 12 h, heated to 50°C for 12 h, and then heated to 60°C for 12 h to obtain a perylene diimide grafted polyurethane material (PU-PDI-2), i.e., a high near-infrared reflective polyurethane.

[0122] Embodiment 3:

[0123] A high near-infrared reflective polyurethane, the structural formula is as follows:

[0124]

[0125] The high near-infrared reflective polyurethane is prepared by the following steps:

[0126] Weigh 1.6 g of poly-ε-caprolactone (0.8 mmol) and 1.2 g of polytetramethylene ether glycol (1.2 mmol), heat to 120 °C and dry for 2 h under vacuum;

[0127] The system was filled with nitrogen, cooled to 80°C, 1.22 g of isophorone diisocyanate (5.5 mmol) was added, and the reaction was stirred for 3 h;

[0128] The temperature was lowered to 65°C, 20 ml of anhydrous DMF was added to the reaction system, and then 0.43 g of terephthalic acid dihydrazide (1.8 mmol) was dissolved in 5 mL of anhydrous DMF and 2 drops of dibutyltin dilaurate were added to the reaction system, and the reaction was continued at a constant temperature for 3 h.

[0129] Weigh 0.039 g PDI-OH (0.049 mmol, ) was dissolved in anhydrous DMF (5 ml), then added to the reaction system and reacted at constant temperature for 3 h;

[0130] The reaction solution was poured into a silica gel mold, dried at 40°C for 12 h, heated to 50°C for 12 h, and then heated to 60°C for 12 h to obtain an orange transparent perylene diimide grafted polyurethane material (PU-PDI-3), i.e., a high near-infrared reflective polyurethane.

[0131] Comparative Example 1:

[0132] A polyurethane is prepared by the following steps:

[0133] Weigh 2 g of poly-ε-caprolactone (1 mmol) and 1 g of polytetramethylene ether glycol (1 mmol), heat to 120 °C and dry for 2 h under vacuum;

[0134] The system was filled with nitrogen, cooled to 80°C, 1.11 g of isophorone diisocyanate (5 mmol) was added, and the reaction was stirred for 3 h;

[0135] The temperature was lowered to 65°C, 20 ml of anhydrous DMF was added to the reaction system, and then 0.39 g of terephthalic acid dihydrazide (2 mmol) was dissolved in 5 mL of anhydrous DMF and 2 drops of dibutyltin dilaurate were added to the reaction system, and the reaction was continued at a constant temperature for 3 h.

[0136] The reacted solution was poured into a silica gel mold, dried at 40°C for 12 h, heated to 50°C for 12 h, and then heated to 60°C for 12 h to obtain a polyurethane material (PU).

[0137] Effect Example 1: Characterization Analysis

[0138] The high near-infrared reflective polyurethane (PU-PDI-1) prepared in Example 1 was subjected to nuclear magnetic resonance hydrogen spectrum analysis to obtain Figure 1 , Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of PU-PDI-1 in Example 1 of the present application.

[0139] See also Figure 1 The hydrogen at the displacements of 7.96 and 7.83 comes from the benzene ring of terephthalic acid dihydrazide and PDI-OH, respectively; the hydrogen at the displacement of 10.29 comes from the -NH- of terephthalic acid dihydrazide; the hydrogen at the displacements of 1.29, 1.52, 2.27, and 3.98 comes from the alkyl chains of PCDL and PTMG and the six-membered ring of PDI-OH; the hydrogen at the displacement of 3.32 comes from isophorone diisocyanate; and the hydrogen at the displacement of 0.87 comes from the methyl group of isophorone diisocyanate and PDI-OH.

[0140] The high near-infrared reflective polyurethane (PU-PDI-1) prepared in Example 1 was subjected to infrared spectroscopy analysis to obtain Figure 2 , Figure 2 This is the infrared spectrum of PU-PDI-1 of Example 1 of the present application.

[0141] See also Figure 2 PU-PDI-1 at 2260cm -1 There is no N=C=O stretching vibration peak corresponding to isophorone diisocyanate nearby, and the stretching vibration peak corresponding to NH and C=O of the urethane bond appears at 3325 cm -1 and 1730cm -1 That is, the isocyanate bond disappears and a urethane bond is formed;

[0142] In addition, PU-PDI-1 at 2939cm -1 and 2859cm -1 The asymmetric stretching vibration peak corresponding to the methylene group appeared at 1104 cm -1The stretching vibration peak corresponding to the ether bond appears at 1161 cm -1 and 1236cm -1 Place.

[0143] In summary, the present application successfully synthesized highly near-infrared reflective polyurethane.

[0144] Effect Example 2: Photophysical properties and aggregation behavior analysis

[0145] The PU-PDI-1 material prepared in Example 1 was cut into samples of 1 cm×1 cm in size, and subjected to X-ray diffraction (XRD) analysis and UV-visible absorption spectroscopy analysis to obtain Figure 3 and Figure 4 , Figure 3 is a one-dimensional X-ray diffraction pattern of PU-PDI-1 of Example 1 of the present application, Figure 4 It is the UV-visible absorption spectrum of PU-PDI-1 of Example 1 of the present application.

[0146] like Figure 3 As shown in the figure, no obvious diffraction peak was observed in the small-angle region of PU-PDI-1, indicating that the PDI chromophore did not show obvious aggregation, had good compatibility with the substrate, and could be evenly dispersed in the substrate; a broad diffraction peak was observed in the wide-angle region (2θ≈20°). This is because the crystallization process in the polymer is different from that of the small molecule. The crystallization is insufficient and incomplete, forming a crystalline microregion, which causes the X-ray diffraction peak to become broad, reflecting the short-range order characteristics of the amorphous polymer matrix.

[0147] like Figure 4 As shown in the figure, the PU-PDI-1 sample has three well-resolved absorption peaks at 520nm, 486nm, and 426nm, which are caused by the clear vibration structure of the characteristic PDI chromophore, corresponding to S 0-0 , S 0-1 , S 0-2 However, the absorption bands of these three absorption peaks are generally broad and the peak shape is gentle, indicating that there is a certain aggregation tendency between the perylene cores, but the degree is not high.

[0148] Effect Example 3: Transparency Analysis

[0149] The PU-PDI-1 material prepared in Example 1 and the PU material prepared in Comparative Example 1 were subjected to transmission spectrum analysis to obtain Figure 5 , Figure 5 It is the transmission spectrum graph of PU-PDI-1 of Example 1 of the present application and PU of Comparative Example 1.

[0150] like Figure 5As shown in the figure, the optical transmittance of PU is about 80%, which may be because the introduction of terephthalic acid dihydrazide causes yellowing of polyurethane, making the PU sample slightly yellow and the optical transmittance decreased. The optical transmittance of PU-PDI-1 is lower than that of PU, but it is also about 80%, which has excellent transmittance performance.

[0151] Effect Example 4: Thermal Stability Analysis

[0152] The thermal stability of the PU-PDI-1 material prepared in Example 1 and the PU material prepared in Comparative Example 1 was analyzed, and the results were as follows: Figure 6 , Figure 6 It is the thermogravimetric curve of PU-PDI-1 of Example 1 of the present application and PU of Comparative Example 1.

[0153] like Figure 6 As shown in the figure, the thermogravimetric curves of PU-PDI-1 and PU are almost completely overlapped, and the thermal decomposition temperatures of PU and PU-PDI-1 at 5% weight loss are 288°C and 287°C, respectively, which are almost exactly the same, indicating that PU-PDI-1 has good thermal stability, and the grafting of perylene diimide has no significant effect on the thermal stability of the polyurethane sample.

[0154] Effect Example 5: Mechanical Performance Analysis

[0155] The PU-PDI-1 material prepared in Example 1 and the PU material prepared in Comparative Example 1 were subjected to stress-strain tests using a universal testing machine, and the results were as follows: Figure 7 , Figure 7 It is the stress-strain curve of PU-PDI-1 of Example 1 of the present application and PU of Comparative Example 1.

[0156] like Figure 7 As shown, the breaking strength of PU-PDI-1 prepared in Example 1 is 34.11 MPa, and the breaking elongation is 771.53%. Compared with PU, the breaking strength of PU-PDI-1 is slightly improved, but the breaking elongation is reduced. This is because the PDI chromophore connected to the end of the polymer chain increases the number of benzene rings and π-π interactions, resulting in enhanced rigidity of the polyurethane material.

[0157] It can be seen from the above experiments that polyurethane can provide sufficient space for the dispersion of PDI macromolecules, there are no obvious defects on the surface of the material, and the high near-infrared reflective polyurethane prepared in Example 1 has excellent mechanical properties.

[0158] Effect Example 6: Near-infrared reflection performance analysis

[0159] The PU-PDI-1 material prepared in Example 1 was cut into samples of 3 cm × 3 cm in size, and a near-infrared reflectance spectrum test was performed by UV-visible-near-infrared spectrophotometry under white substrate conditions to obtain Figure 8 , Figure 8 This is the near-infrared reflection spectrum of PU-PDI-1 of Example 1 of the present application.

[0160] like Figure 8 As shown, the reflectivity value gradually increases in the wavelength range of 700-1750nm. This region (700-1750nm) accounts for more than 80% of near-infrared solar energy, so it has an important influence on the cooling activity of the pigment. In the 1750-2500n band, the PU-PDI-1 system can still maintain high reflective properties. PDI molecules are covalently bonded to the polyurethane chains and evenly dispersed in the polymer matrix. This uniform dispersion leads to a more uniform molecular network, allowing the PDI chromophore to effectively participate in the near-infrared reflection process, resulting in PU-PDI-1 having a relatively excellent near-infrared reflection effect.

[0161] Based on the above experiments, it can be seen that introducing PDI into polyurethane through a covalent binding strategy can effectively retain good mechanical properties while obtaining a polyurethane with near-infrared reflection properties. The high near-infrared reflection polyurethane prepared in Example 1 can be used to prepare high near-infrared reflection materials.

[0162] It is obvious to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0163] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high near-infrared reflective polyurethane, characterized in that: It has the following general formula 1: [General formula 1] In the general formula 1, x, y, and z are the number of random copolymer segments, and x, y, and z are each independently any integer greater than 0; R1 is (CH2) n , where n is an integer greater than or equal to 3 and less than or equal to 9; R2 is C8H 17 , C 10 H 21 or 2. The high near-infrared reflective polyurethane according to claim 1, characterized in that: It has the following general formula 2: [General formula 2] In the general formula 2, x, y, and z are the numbers of random copolymer segments, and x, y, and z are each independently any integer greater than 0.

3. A method for preparing a highly near-infrared reflective polyurethane, characterized in that: include: Poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG and isophorone diisocyanate are reacted to obtain a first intermediate product having the following general formula 3; The first intermediate product and terephthalic acid dihydrazide are reacted under the catalysis of dibutyltin dilaurate DBTDL to obtain a second intermediate product having the following general formula 4; The second intermediate product is reacted with a perylene diimide having the following general formula 5 to obtain a high near-infrared reflective polyurethane having the following general formula 1; [General formula 3] [General formula 4] [Formula 5] [General formula 1] In each of the general formulas 1, 3, 4, and 5, x, y, and z are the numbers of random copolymer segments, and x, y, and z are each independently any integer greater than 0; R1 is (CH2) n , where n is an integer greater than or equal to 3 and less than or equal to 9; R2 is C8H 17 , C 10 H 21 or 4. The preparation method according to claim 3, characterized in that: The step of reacting poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG and isophorone diisocyanate comprises: Heat poly-ε-caprolactone PCDL and polytetramethylene ether glycol PTMG to 115-125° C. under vacuum conditions and dry for 1.5-2.5 hours; Inert gas is introduced into the system, and then the temperature is lowered to 70-80° C., isophorone diisocyanate is added, and the reaction is stirred for 2.5-3.5 hours to obtain the first intermediate product.

5. The preparation method according to claim 4, characterized in that: The molar ratio of the poly-ε-caprolactone PCDL, polytetramethylene ether glycol PTMG and isophorone diisocyanate is (0.8-1.2): (0.8-1.2): (4.5-5.5).

6. The preparation method according to claim 3, characterized in that: The step of reacting the first intermediate product with terephthalic acid dihydrazide under the catalysis of dibutyltin dilaurate DBTDL comprises: An organic solvent is added to the first intermediate product at 60-70° C., and then terephthalic acid dihydrazide and dibutyltin dilaurate are dissolved in the organic solvent and added to the system, and the reaction is carried out at a constant temperature for 2.5-3.5 hours to obtain the second intermediate product.

7. The preparation method according to claim 6, characterized in that: The molar ratio of the poly-ε-caprolactone to terephthalic acid dihydrazide is (0.8-1.2): (1.8-2.2).

8. The preparation method according to claim 3, characterized in that: The step of reacting the second intermediate product with a perylene diimide having the general formula 5 comprises: Adding the perylene diimide dissolved in an organic solvent to the second intermediate product at 60-70° C., and reacting at a constant temperature for 2.5-3.5 hours; The reacted solution is poured into a mold, dried at 35-45° C. for 11-13 hours, then heated to 45-55° C. for further drying for 11-13 hours, and then heated to 55-65° C. for further drying for 11-13 hours to obtain the highly near-infrared reflective polyurethane.

9. The preparation method according to claim 3, characterized in that: The molar ratio of the poly-ε-caprolactone to perylene diimide is (0.8-1.2):(0.049-0.050).

10. Use of the high near-infrared reflective polyurethane according to any one of claims 1 to 3 or the high near-infrared reflective polyurethane prepared by the preparation method according to any one of claims 4 to 9 in the preparation of high near-infrared reflective materials.

Images