Low-temperature tough polyurethane elastomer and preparation method thereof

Abstract

The invention discloses a low-temperature tough polyurethane elastomer and a preparation method thereof, and relates to the technical field of polyurethane elastomers. The low-temperature toughness polyurethane elastomer is prepared from the following raw materials in parts by weight: 45 to 55 parts of modified polyether polyol, 16 to 20 parts of isophorone diisocyanate, 4 to 8 parts of 1, 4-butanediol, 2 to 5 parts of modified nano silicon dioxide, 0.1 to 0.3 part of dibutyltin dilaurate, 0.2 to 0.5 part of an antioxidant 1010 and 0.1 to 0.3 part of an ultraviolet light absorber UV-327. According to the low-temperature toughness polyurethane elastomer disclosed by the invention, through the synergistic effect of the modified polyether polyol and the modified nano silicon dioxide, the low-temperature toughness is greatly improved; the raw material ratio is accurate, the preparation process is controllable, and the NCO content of the product is stable; the anti-oxidation and anti-ultraviolet auxiliaries are added, so that the weather resistance is good; the finished product is uniform in performance and excellent in comprehensive mechanical property.

Description

Technical Field

[0001] This invention relates to the field of polyurethane elastomer technology, specifically to a low-temperature toughness polyurethane elastomer and its preparation method. Background Technology

[0002] Polyurethane elastomers, possessing both the high elasticity of rubber and the processability of plastics, are widely used in industrial sealing, rail transportation, and cryogenic engineering, making them a research hotspot in polymer materials in recent years. Current technologies for preparing polyurethane elastomers primarily use common polytetrahydrofuran ether glycol and polypropylene glycol as base polyol raw materials, combined with isocyanates and small-molecule chain extenders for simple polymerization. Some processes add unmodified inorganic fillers to improve mechanical properties, while conventional antioxidants and UV stabilizers are added to improve weather resistance.

[0003] However, existing preparation technologies still have many problems that urgently need to be solved: First, conventional polyether polyols have a simple molecular chain structure, which is prone to segmental crystallization at low temperatures, resulting in a significant decrease in the low-temperature toughness of the elastomer. In low-temperature environments, they are prone to brittleness and poor deformation recovery, failing to meet the requirements for use in low-temperature conditions. Second, unmodified nano-silica and other inorganic fillers have poor compatibility with the polyurethane matrix and are prone to agglomeration. This not only makes it difficult to effectively improve the comprehensive mechanical properties of the material but also leads to uneven dispersion of the system, affecting the stability of product performance. Third, some processes do not accurately control the degree of prepolymer reaction and NCO content, and the vulcanization and post-curing process parameters are not designed reasonably, which can easily cause bubbles and uneven crosslinking density inside the elastomer, further reducing the material's low-temperature impact resistance and structural stability. Fourth, the weather resistance modification design of existing formulations is relatively simple, and the antioxidants and UV stabilizers have poor bonding with the matrix. After long-term use, they are prone to precipitation, leading to a decline in the aging resistance of the elastomer and a shortened service life.

[0004] Furthermore, in the traditional preparation of polyurethane elastomers, the synergistic design of raw material compatibility and reaction processes is insufficient, making it difficult to simultaneously achieve low-temperature toughness, mechanical strength, and weather resistance. Some solutions that improve low-temperature performance sacrifice the material's room-temperature mechanical properties, failing to achieve a balanced optimization of multiple properties. Therefore, developing a polyurethane elastomer with excellent low-temperature toughness, stable comprehensive mechanical properties, good weather resistance, and a controllable preparation process has become an urgent need in the industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a low-temperature toughness polyurethane elastomer and its preparation method, solving the problems of poor low-temperature toughness, low filler compatibility, insufficient performance stability, and rapid weather resistance degradation in existing polyurethane elastomers.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A low-temperature toughness polyurethane elastomer comprises the following raw materials in parts by weight: 45-55 parts modified polyether polyol, 16-20 parts isophorone diisocyanate, 4-8 parts 1,4-butanediol, 2-5 parts modified nano silica, 0.1-0.3 parts dibutyltin dilaurate, 0.2-0.5 parts antioxidant 1010, and 0.1-0.3 parts ultraviolet absorber UV-327.

[0007] Furthermore, the modified polyether polyol is prepared using the following specific steps: A1. Polytetrahydrofuran ether diol and potassium hydroxide were added to a high-pressure reactor. After replacing the air in the reactor with nitrogen, the temperature was raised to 110°C for melting and dehydration under reduced pressure for 30 minutes. Then, propylene oxide was added in four batches. After the first addition, the reaction pressure was controlled at 0.2-0.3 MPa and the temperature at 110°C. After the pressure in the reactor dropped from the peak to a stable level, the second batch was added. The remaining two batches were added in the same manner. After all the propylene oxide was added, the reaction continued for 1 hour. After the reaction was completed, the mixture was neutralized with phosphoric acid, dehydrated, and filtered to obtain random polyether polyol. Polytetrahydrofuran ether diol (PTMG) undergoes ring-opening polymerization with propylene oxide (PO) anion under potassium hydroxide catalysis. The reaction rate is controlled by adding propylene oxide in stages, generating a random copolymer of PTMG-PPO. This process disrupts the regularity of the polyether chain segments, inhibits low-temperature crystallization, and improves the chain segment flexibility and low-temperature toughness.

[0008] A2. Add random polyether polyol, hydroxyl-terminated polydimethylsiloxane, tetrabutyl titanate and xylene to a four-necked flask equipped with a reflux dehydration device. After nitrogen purging, start stirring and heat to 120-130℃ for reflux dehydration coupling reaction for 4-5 hours. After the reaction is completed, remove the solvent under vacuum at -0.095MPa and 130℃ to obtain polysiloxane-polyether copolymer modified polyol. Under the catalysis of titanate, the terminal hydroxyl groups of random polyether and the terminal hydroxyl polydimethylsiloxane undergo dehydration condensation to form a Si-OC bond graft structure, introducing low Tg siloxane segments, reducing the intermolecular forces, and improving low-temperature elasticity and deformation recovery.

[0009] A3. Add polysiloxane-polyether copolymerized modified polyol, toluene and deionized water to a four-necked flask, start stirring and heat to 40-50℃, then slowly add silane coupling agent KH-560 dropwise, and continue the reaction at 40-50℃ for 2-3 hours. After the reaction is completed, remove the solvent under vacuum at 100℃ until there is no distillate to obtain modified polyether polyol.

[0010] The silane coupling agent KH-560 is hydrolyzed under controlled water conditions, and the silanol is grafted with the hydroxyl groups of the polyether / polysiloxane chain by condensation, while the end retains the epoxy propoxy group, which enhances the reactivity with the polyurethane matrix.

[0011] Furthermore, the ratio of polytetrahydrofuran ether glycol, potassium hydroxide, and propylene oxide in A1 is 500g: 2.3-2.7g: 140mL; the input amounts of the four batches of propylene oxide are 50mL: 30mL: 30mL: 30mL.

[0012] Furthermore, the ratio of random polyether polyol, hydroxyl-terminated polydimethylsiloxane, tetrabutyl titanate, and xylene in A2 is 450g: 30-45g: 0.2-0.25g: 80-100mL.

[0013] Furthermore, the ratio of polysiloxane-polyether copolymerized modified polyol, toluene, deionized water, and silane coupling agent KH-560 in A3 is 400g: 80-100mL: 2-4g: 15-25g.

[0014] Furthermore, the modified nano-silica is prepared using the following specific steps: B1. In a dry three-necked flask, fumed nano-silica and anhydrous isopropanol were added and ultrasonically dispersed for 30 min under nitrogen protection. Then, 3-aminopropyltrimethoxysilane was slowly added dropwise and the temperature was raised to 70-80℃ for 4 h. After the reaction was completed, the product was centrifuged, washed three times with anhydrous isopropanol, and dried under vacuum at 80℃ for 12 h to obtain aminosilanized nano-silica. The methoxy groups on the surface of gas-phase nano-SiO2 condense with the methoxy groups of 3-aminopropyltrimethoxysilane to form covalent bonds. Surface amylation improves the lipophilicity of nanoparticles, provides active sites for subsequent grafting reactions, and inhibits particle aggregation.

[0015] B2. Polypropylene glycol and isophorone diisocyanate were added to a dry high-pressure reactor. After nitrogen purging, the temperature was raised to 80-90℃ and reacted for 2.5 hours to prepare a prepolymer. The temperature was maintained at 80-90℃, and aminosilanized nano-silica was slowly added in 4 batches at 15-20 minutes intervals. The reaction temperature was controlled not to exceed 95℃. After the addition was completed, the reaction was continued for 2 hours. Finally, the residue was removed under vacuum at -0.095MPa and 90℃ to obtain modified nano-silica.

[0016] Aminosilanized nano-SiO2 surface amino groups add to prepolymer isocyanate groups to form urea groups, grafting NCO-terminated polyurethane short chains onto the nanoparticle surface, thus imparting reactivity. The modified nanoparticles achieve chemical bonding and uniform dispersion through in-situ reaction of surface NCO groups with the elastomer matrix, simultaneously improving interfacial compatibility and mechanical reinforcement.

[0017] Furthermore, the ratio of fumed nano-silica, anhydrous isopropanol, and 3-aminopropyltrimethoxysilane in B1 is 100g:350-380g:6-8g.

[0018] Furthermore, the ratio of polypropylene glycol, isophorone diisocyanate, and aminosilanized nano silica in B2 is 160-180g: 45-50g: 80g; each batch of aminosilanized nano silica contains 20g.

[0019] Furthermore, the modified nano-silica has an NCO content of 1.8-2.5%.

[0020] A method for preparing a low-temperature toughness polyurethane elastomer specifically includes the following steps: S1. Place 45-55 parts of modified polyether polyol in a reaction vessel, add 16-20 parts of isophorone diisocyanate, and react at 60-65℃ for 2 hours to form a prepolymer. S2. Add 2-5 parts of modified nano-silica to the prepolymer, heat to 70-80℃, disperse and react for 1.5-2.5h under high-speed stirring at 500-1000rpm. The NCO content of the system is considered to be 3.5-4.5% when it meets the standard. After meeting the standard, cool the system to 50-55℃. S3. Heat 4-8 parts of 1,4-butanediol to 70-80℃, add 0.2-0.5 parts of antioxidant 1010 and 0.1-0.3 parts of ultraviolet absorber UV-327, stir to dissolve until homogeneous, cool to 40-45℃, add 0.1-0.3 parts of dibutyltin dilaurate premix for 5 min, and quickly add to the S2 system and stir for 5-7 min. S4. Degas the uniformly mixed system under vacuum for 5-8 minutes, vulcanize at 85-90℃ for 8-10 hours, demold after vulcanization, and place at room temperature for 72 hours to obtain low-temperature tough polyurethane elastomer.

[0021] This invention provides a low-temperature toughness polyurethane elastomer and its preparation method, which has the following beneficial effects: 1. The polyurethane elastomer prepared by this invention has excellent low-temperature toughness. By copolymerizing polyether polyol with polysiloxane and modifying it with silane coupling agent, the molecular chain structure is optimized, avoiding the problem of chain segment crystallization at low temperature. At the same time, the modified nano-silica achieves good compatibility with the polyurethane matrix. After uniform dispersion, it effectively improves the deformation recovery ability and anti-brittleness of the material at low temperature, solving the pain point of the significant reduction in toughness of traditional polyurethane elastomers under low-temperature conditions. It can be adapted to various low-temperature engineering application scenarios and broadens the operating temperature range of polyurethane elastomers.

[0022] 2. The overall mechanical properties of this elastomer are more stable and balanced. The modified polyether polyol provides a flexible molecular skeleton for the elastomer, while the modified nano silica acts as a functional filler to reinforce the matrix. Combined with the precise control of the NCO content of the prepolymer in the preparation process and the optimized design of the vulcanization process, the cross-linking density inside the elastomer is uniform and free of defects such as bubbles. This ensures the tensile and impact resistance properties at room temperature without sacrificing the elasticity and flexibility of the material due to the reinforcement modification, thus achieving a synergistic improvement in mechanical strength and elasticity.

[0023] 3. The weather resistance and aging resistance of the product of this invention are significantly improved. The antioxidant 1010 and ultraviolet absorber UV-327 added to the formula are fully integrated with the system during the chain extension stage. At the same time, the molecular structure of the modified polyether polyol and the modified nano silica makes the binding between the additives and the matrix stronger, effectively avoiding the problem of easy precipitation of additives in traditional products. It can resist oxidation and ultraviolet aging for a long time, delay the degradation of material performance, and greatly improve the service life of polyurethane elastomers in outdoor and complex environments, and reduce the cost of replacement and maintenance in the later stage.

[0024] 4. The preparation process of this polyurethane elastomer is both controllable and repeatable. From the stepwise preparation of modified polyether polyol and modified nano silica to the entire process of prepolymer reaction, filler composite and vulcanization curing, clear temperature, pressure and time parameters and material ratio standards are set. In addition, side reactions in the reaction process are avoided by vacuum degassing and nitrogen protection. The performance of the prepared product has small batch-to-batch differences. At the same time, the process steps are reasonably connected, no special complex equipment is required, it is easy to realize industrial scale-up production, suitable for large-scale mass production applications, and has good industrial transformation value. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: Preparation of a low-temperature toughness polyurethane elastomer. The specific preparation steps are as follows: S1. Place 45 parts of modified polyether polyol in a reaction vessel, add 16 parts of isophorone diisocyanate, and react at 60°C for 2 hours to form a prepolymer. S2. Add 2 parts of modified nano-silica to the prepolymer, heat to 70℃, disperse and react for 1.5h under high-speed stirring at 500rpm. The NCO content of the system is considered to be 3.5% when it meets the standard. After meeting the standard, cool the system to 50℃. S3. Heat 4 parts of 1,4-butanediol to 70°C, add 0.2 parts of antioxidant 1010 and 0.1 parts of ultraviolet absorber UV-327, stir until homogeneous, cool to 40°C, add 0.1 parts of dibutyltin dilaurate premix for 5 min, and quickly add to the S2 system and stir for 5 min. S4. Vacuum degas the uniformly mixed system for 5 minutes, vulcanize it at 85°C for 8 hours, demold it after vulcanization, and place it at room temperature for 72 hours to obtain a low-temperature tough polyurethane elastomer.

[0027] Example 2: Preparation of low-temperature toughness polyurethane elastomer. The specific preparation steps are as follows: S1. Place 55 parts of modified polyether polyol in a reaction vessel, add 20 parts of isophorone diisocyanate, and react at 65°C for 2 hours to form a prepolymer. S2. Add 5 parts of modified nano-silica to the prepolymer, heat to 80℃, disperse and react for 2.5h under high-speed stirring at 1000rpm. The NCO content of the system is considered to be 4.5% when it meets the standard. After meeting the standard, cool the system to 55℃. S3. Heat 8 parts of 1,4-butanediol to 80°C, add 0.5 parts of antioxidant 1010 and 0.3 parts of ultraviolet absorber UV-327, stir until homogeneous, cool to 45°C, add 0.3 parts of dibutyltin dilaurate premix for 5 min, and quickly add to the S2 system and stir for 7 min. S4. Vacuum degas the uniformly mixed system for 8 minutes, vulcanize it at 90°C for 10 hours, demold it after vulcanization, and place it at room temperature for 72 hours to obtain a low-temperature tough polyurethane elastomer.

[0028] Example 3: Preparation of low-temperature toughness polyurethane elastomer. The specific preparation steps are as follows: S1. Place 50 parts of modified polyether polyol in a reaction vessel, add 18 parts of isophorone diisocyanate, and react at 62°C for 2 hours to form a prepolymer. S2. Add 3 parts of modified nano-silica to the prepolymer, heat to 75℃, disperse and react for 2 hours under high-speed stirring at 750 rpm. The NCO content of the system is considered to be 4.0% when it meets the standard. After meeting the standard, cool the system to 52℃. S3. Heat 6 parts of 1,4-butanediol to 75°C, add 0.3 parts of antioxidant 1010 and 0.2 parts of ultraviolet absorber UV-327, stir until homogeneous, cool to 42°C, add 0.2 parts of dibutyltin dilaurate premix for 5 min, and quickly add to the S2 system and stir for 6 min. S4. Vacuum degas the uniformly mixed system for 6 minutes, vulcanize it at 87°C for 9 hours, demold it after vulcanization, and place it at room temperature for 72 hours to obtain a low-temperature tough polyurethane elastomer.

[0029] Example 4: Preparation of modified polyether polyols. The specific preparation steps are as follows: A1. 500g of polytetrahydrofuran ether diol and 2.3g of potassium hydroxide were added to a high-pressure reactor. After replacing the air in the reactor with nitrogen, the temperature was raised to 110℃ for melting and dehydration under reduced pressure for 30min. Then, 140mL of propylene oxide was added in four portions. The first portion was 50mL. The reaction was carried out under the conditions of 0.2MPa and 110℃. After the pressure in the reactor dropped from the peak to a stable state, the second portion of 30mL was added. The remaining two portions of 30mL were added in this manner. After all the propylene oxide was added, the reaction was continued for 1h. After the reaction was completed, the mixture was neutralized with phosphoric acid, dehydrated, and filtered to obtain random polyether polyol. A2. Add 450g of random polyether polyol, 30g of hydroxyl-terminated polydimethylsiloxane, 0.2g of tetrabutyl titanate and 80mL of xylene to a four-necked flask equipped with a reflux dehydration device. After nitrogen purging, start stirring and heat to 120℃ for reflux dehydration coupling reaction for 4h. After the reaction is completed, remove the solvent under vacuum at -0.095MPa and 130℃ to obtain polysiloxane-polyether copolymer modified polyol. A3. Add 400g of polysiloxane-polyether copolymer modified polyol, 80mL of toluene and 2g of deionized water to a four-necked flask, start stirring and heat to 40℃, then slowly add 15g of silane coupling agent KH-560, and continue the reaction at 40℃ for 2h. After the reaction is completed, remove the solvent under vacuum at 100℃ until there is no distillate, and obtain the modified polyether polyol.

[0030] Example 5: Preparation of modified polyether polyols. The specific preparation steps are as follows: A1. 500g of polytetrahydrofuran ether diol and 2.7g of potassium hydroxide were added to a high-pressure reactor. After replacing the air in the reactor with nitrogen, the temperature was raised to 110℃ for melting and dehydration under reduced pressure for 30min. Then, 140mL of propylene oxide was added in four portions. The first portion was 50mL. The reaction was carried out under the conditions of 0.3MPa and 110℃. After the pressure in the reactor dropped from the peak to a stable state, the second portion of 30mL was added. The remaining two portions of 30mL were added in this manner. After all the propylene oxide was added, the reaction was continued for 1h. After the reaction was completed, the mixture was neutralized with phosphoric acid, dehydrated, and filtered to obtain random polyether polyol. A2. Add 450g of random polyether polyol, 45g of hydroxyl-terminated polydimethylsiloxane, 0.25g of tetrabutyl titanate and 100mL of xylene to a four-necked flask equipped with a reflux dehydration device. After nitrogen purging, start stirring and heat to 130℃ for reflux dehydration coupling reaction for 5h. After the reaction is completed, remove the solvent under vacuum at -0.095MPa and 130℃ to obtain polysiloxane-polyether copolymer modified polyol. A3. Add 400g of polysiloxane-polyether copolymerized modified polyol, 100mL of toluene and 4g of deionized water to a four-necked flask, start stirring and heat to 50℃, then slowly add 25g of silane coupling agent KH-560, and continue the reaction at 50℃ for 3h. After the reaction is completed, remove the solvent under vacuum at 100℃ until there is no distillate, and obtain the modified polyether polyol.

[0031] Example 6: Preparation of modified nano-silica. The specific preparation steps are as follows: B1. In a dry three-necked flask, add 100g of fumed nano-silica and 350g of anhydrous isopropanol, and sonicate under nitrogen protection for 30min. Then slowly add 6g of 3-aminopropyltrimethoxysilane, and heat to 70℃ for 4h. After the reaction is completed, centrifuge and wash the product three times with anhydrous isopropanol. Dry under vacuum at 80℃ for 12h to obtain aminosilanized nano-silica. B2. Add 160g of polypropylene glycol and 45g of isophorone diisocyanate to a dry high-pressure reactor. After nitrogen purging, raise the temperature to 80℃ and react for 2.5h. Maintain the temperature at 80℃, and slowly add 80g of aminosilanized nano-silica in 4 batches at 15min intervals. Control the reaction temperature to not exceed 95℃. After the addition is complete, continue the reaction for 2h. Finally, remove the residue under vacuum at -0.095MPa and 90℃ to obtain modified nano-silica.

[0032] Example 7: Preparation of modified nano-silica. The specific preparation steps are as follows: B1. In a dry three-necked flask, add 100g of fumed nano-silica and 380g of anhydrous isopropanol, and sonicate under nitrogen protection for 30min. Then slowly add 8g of 3-aminopropyltrimethoxysilane, and heat to 80℃ to react for 4h. After the reaction is completed, centrifuge and wash the product three times with anhydrous isopropanol. Dry under vacuum at 80℃ for 12h to obtain aminosilanized nano-silica. B2. Add 180g of polypropylene glycol and 50g of isophorone diisocyanate to a dry high-pressure reactor. After nitrogen purging, raise the temperature to 90℃ and react for 2.5h. Maintain the temperature at 90℃, and slowly add 80g of aminosilanized nano-silica in 4 batches at 20min intervals. Control the reaction temperature to not exceed 95℃. After the addition is complete, continue the reaction for 2h. Finally, remove the residue under vacuum at -0.095MPa and 90℃ to obtain modified nano-silica.

[0033] Comparative Example 1: A low-temperature toughness polyurethane elastomer was prepared. The specific preparation steps are as follows: The remaining steps remain unchanged, except that the modified polyether polyol prepared in Example 4 and used in Example 3 is replaced with unmodified polytetrahydrofuran ether diol to prepare a low-temperature tough polyurethane elastomer.

[0034] Comparative Example 2: A low-temperature toughness polyurethane elastomer was prepared. The specific preparation steps are as follows: The remaining steps remain unchanged, except that the modified nano-silica prepared in Example 7 used in Example 3 is replaced with unmodified nano-silica to prepare a low-temperature tough polyurethane elastomer.

[0035] Comparative Example 3: A low-temperature toughness polyurethane elastomer was prepared. The specific preparation steps are as follows: The remaining steps remain unchanged, except that the modified polyether polyol prepared in Example 4 used in Example 3 is replaced with unmodified polytetrahydrofuran ether diol, and the modified nano silica prepared in Example 7 is replaced with unmodified nano silica, to prepare a low-temperature tough polyurethane elastomer.

[0036] Performance testing Test Project Test Standards Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) GB / T528-2009 28.5 30.2 32.8 20.1 25.3 18.6 Elongation at break (%) GB / T528-2009 580 620 685 420 510 380 Low-temperature brittleness temperature (°C) GB / T15256-2014 -62 -65 -68 -45 -52 -40 Shore A hardness GB / T39693.4-2025 85 87 88 82 84 80 Performance tests were conducted on the low-temperature toughness polyurethane elastomer examples and comparative examples according to relevant GB / T testing standards. The results showed that the comprehensive performance of the products of Examples 1-3 prepared with modified polyether polyol and modified nano silica was significantly better than that of Comparative Examples 1-3, which used unmodified polytetrahydrofuran ether diol and unmodified nano silica. Among them, Example 3 had the best comprehensive performance, with a tensile strength of 32.8 MPa, an elongation at break of 685%, a low-temperature brittleness temperature of -68℃, and a Shore A hardness of 88. Comparative Example 3 had the worst performance because it replaced two core modifying raw materials at the same time, with a tensile strength of only 18.6 MPa, an elongation at break of 380%, and a low-temperature brittleness temperature of only -40℃. Moreover, the tensile strength, elongation at break, low-temperature brittleness temperature, and Shore A hardness of all examples were higher than those of the comparative examples, which fully demonstrates that the synergistic effect of modified polyether polyol and modified nano silica can significantly improve the tensile properties, low-temperature toughness, and hardness of polyurethane elastomers.

[0037] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A low-temperature toughness polyurethane elastomer, characterized in that: It contains the following raw materials in parts by weight: 45-55 parts modified polyether polyol, 16-20 parts isophorone diisocyanate, 4-8 parts 1,4-butanediol, 2-5 parts modified nano silica, 0.1-0.3 parts dibutyltin dilaurate, 0.2-0.5 parts antioxidant 1010, and 0.1-0.3 parts ultraviolet absorber UV-327.

2. The low-temperature toughness polyurethane elastomer according to claim 1, characterized in that: The modified polyether polyol is prepared using the following specific steps: A1. Polytetrahydrofuran ether diol and potassium hydroxide were added to a high-pressure reactor. After replacing the air in the reactor with nitrogen, the temperature was raised to 110°C for melting and dehydration under reduced pressure for 30 minutes. Then, propylene oxide was added in four batches. After the first addition, the reaction pressure was controlled at 0.2-0.3 MPa and the temperature at 110°C. After the pressure in the reactor dropped from the peak to a stable level, the second batch was added. The remaining two batches were added in the same manner. After all the propylene oxide was added, the reaction continued for 1 hour. After the reaction was completed, the mixture was neutralized with phosphoric acid, dehydrated, and filtered to obtain random polyether polyol. A2. Add random polyether polyol, hydroxyl-terminated polydimethylsiloxane, tetrabutyl titanate and xylene to a four-necked flask equipped with a reflux dehydration device. After nitrogen purging, start stirring and heat to 120-130℃ for reflux dehydration coupling reaction for 4-5 hours. After the reaction is completed, remove the solvent under vacuum at -0.095MPa and 130℃ to obtain polysiloxane-polyether copolymer modified polyol. A3. Add polysiloxane-polyether copolymerized modified polyol, toluene and deionized water to a four-necked flask, start stirring and heat to 40-50℃, then slowly add silane coupling agent KH-560 dropwise, and continue the reaction at 40-50℃ for 2-3 hours. After the reaction is completed, remove the solvent under vacuum at 100℃ until there is no distillate to obtain modified polyether polyol.

3. The low-temperature toughness polyurethane elastomer according to claim 2, characterized in that: The ratio of polytetrahydrofuran ether diol, potassium hydroxide, and propylene oxide in A1 is 500g: 2.3-2.7g: 140mL; the input amounts of the four batches of propylene oxide are 50mL: 30mL: 30mL: 30mL. The ratio of random polyether polyol, hydroxyl-terminated polydimethylsiloxane, tetrabutyl titanate, and xylene in A2 is 450g: 30-45g: 0.2-0.25g: 80-100mL; The ratio of polysiloxane-polyether copolymerized modified polyol, toluene, deionized water, and silane coupling agent KH-560 in A3 is 400g: 80-100mL: 2-4g: 15-25g.

4. The low-temperature toughness polyurethane elastomer according to claim 1, characterized in that: The modified nano-silica is prepared using the following specific steps: B1. In a dry three-necked flask, fumed nano-silica and anhydrous isopropanol were added and ultrasonically dispersed for 30 min under nitrogen protection. Then, 3-aminopropyltrimethoxysilane was slowly added dropwise and the temperature was raised to 70-80℃ for 4 h. After the reaction was completed, the product was centrifuged, washed three times with anhydrous isopropanol, and dried under vacuum at 80℃ for 12 h to obtain aminosilanized nano-silica. B2. Polypropylene glycol and isophorone diisocyanate were added to a dry high-pressure reactor. After nitrogen purging, the temperature was raised to 80-90℃ and reacted for 2.5 hours. The temperature was maintained at 80-90℃, and aminosilanized nano-silica was slowly added in 4 batches at 15-20 minutes intervals. The reaction temperature was controlled to not exceed 95℃. After the addition was completed, the reaction continued for 2 hours. Finally, the residue was removed under vacuum at -0.095MPa and 90℃ to obtain modified nano-silica.

5. The low-temperature toughness polyurethane elastomer according to claim 4, characterized in that: The ratio of fumed nano silica, anhydrous isopropanol, and 3-aminopropyltrimethoxysilane in B1 is 100g: 350-380g: 6-8g. The ratio of polypropylene glycol, isophorone diisocyanate, and aminosilanized nano silica in B2 is 160-180g: 45-50g: 80g.

6. The low-temperature toughness polyurethane elastomer according to claim 4, characterized in that: The modified nano-silica has an NCO content of 1.8-2.5%.

7. A method for preparing a low-temperature toughness polyurethane elastomer, characterized in that: Specifically, it includes the following steps: S1. Place 45-55 parts of modified polyether polyol in a reaction vessel, add 16-20 parts of isophorone diisocyanate, and react at 60-65℃ for 2 hours to form a prepolymer. S2. Add 2-5 parts of modified nano-silica to the prepolymer, heat to 70-80℃, disperse and react for 1.5-2.5h under high-speed stirring at 500-1000rpm. The NCO content of the system is considered to be 3.5-4.5% when it meets the standard. After meeting the standard, cool the system to 50-55℃. S3. Heat 4-8 parts of 1,4-butanediol to 70-80℃, add 0.2-0.5 parts of antioxidant 1010 and 0.1-0.3 parts of ultraviolet absorber UV-327, stir to dissolve until homogeneous, cool to 40-45℃, add 0.1-0.3 parts of dibutyltin dilaurate premix for 5 min, and quickly add to the S2 system and stir for 5-7 min. S4. Degas the uniformly mixed system under vacuum for 5-8 minutes, vulcanize at 85-90℃ for 8-10 hours, demold after vulcanization, and place at room temperature for 72 hours to obtain low-temperature tough polyurethane elastomer.