High-damping polyurethane composition resistant to rapid temperature change and preparation method thereof

Abstract

The invention discloses a high-damping polyurethane composition resistant to rapid temperature change and a preparation method thereof, and belongs to the field of high polymer materials. The composition comprises the following components in parts by weight: 100 parts of a matrix polyurethane prepolymer, 5-25 parts of a high-performance polyurethane damping agent and 0.5-8 parts of modified nano filler, 3-10 parts of other fillers, 7-15 parts of a plasticizer, 0.01-0.5 part of a catalyst, and 0-5 parts of other assistants; wherein the matrix polyurethane prepolymer is prepared by reacting mixed polyol with excessive diisocyanate, and the mixed polyol comprises polyester polyol or polycarbonate polyol with a medium glass transition temperature and polyether polyol with a low glass transition temperature; the high-performance polyurethane damping agent is a high-damping polyurethane polymer which takes polyfunctional micromolecular alcohol as a core and is terminated by long-chain monofunctional alcohol. The composition is suitable for shock absorption of low-altitude aircrafts, high-speed rail transit vehicles and instruments which need vibration resistance and high reliability in a severe temperature alternating environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a high-damping polyurethane composition resistant to rapid temperature change and a preparation method thereof. BACKGROUND

[0002] In high-end equipment such as low-altitude aircraft and high-speed railway locomotives, shock-absorbing sealing materials often need to withstand extreme high-low temperature cyclic impact in a very short time (for example, rapid temperature change from -60℃ to +150℃). Such working conditions put stringent requirements on the damping performance (dissipating vibration energy) and heat fatigue resistance of the materials.

[0003] Traditional shock-absorbing damping materials, such as high-damping rubber or resin, usually have a relatively narrow effective damping temperature range, and are severely dependent on the glass transition temperature (Tg). Once the temperature exceeds the Tg range, the damping performance will decrease sharply. Ordinary polyurethane elastomers have good toughness and low-temperature resistance, but their inherent damping factor (tan δ) is low, and in the process of frequent rapid temperature change, due to the difference in thermal expansion coefficient between the hard segments and soft segments in the matrix, internal stress accumulation easily occurs, leading to material cracking and debonding from the substrate, thereby losing the sealing and shock-absorbing functions.

[0004] In the prior art, the damping performance of polyurethane is often improved by adding inorganic fillers (such as carbon black and silicon dioxide) or blending with other polymers (such as acrylate). However, these methods often have limitations: the addition of a large amount of fillers will significantly damage the flexibility and elongation at break of the material, and increase the density, which cannot meet the demand for lightweight aircraft; simple physical blending easily leads to phase separation, and the phase interface becomes a weak point under thermal cycling stress, which may cause durability problems. Therefore, how to significantly broaden the effective damping temperature range while ensuring the stability of the mechanical properties of the material under rapid temperature change and the interface durability is a technical problem to be solved in the field.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a high-damping polyurethane composition resistant to rapid temperature change and a preparation method thereof, which has the characteristics of ultra-wide temperature range and high damping, excellent heat shock resistance and high strength and toughness, thereby solving the technical problems of narrow temperature range and poor rapid temperature change fatigue resistance of existing polyurethane damping materials.

[0007] The purpose of the present application is achieved by the following technical solutions: A high-damping polyurethane composition resistant to rapid temperature change, which is prepared from the following components by weight parts: 100 parts of a base polyurethane prepolymer, 5-25 parts of a high-performance polyurethane damping agent, modified nano-filler 0.5-8 parts; other filler 3-10 parts, plasticizer 7-15 parts, catalyst 0.01-0.5 parts, other auxiliary agent 0-5 parts; The base polyurethane prepolymer is prepared by mixing polyol with excess diisocyanate, wherein the polyol comprises polyester polyol or polycarbonate polyol with medium glass transition temperature, and polyether polyol with low glass transition temperature. The high-performance polyurethane damping agent is a high-damping polyurethane polymer with multifunctional small molecular alcohol as core and long-chain monofunctional alcohol as end.

[0008] Preferably, in the composition, the mass ratio of the polyether polyol with low glass transition temperature to the polyester polyol or polycarbonate polyol with medium glass transition temperature is 50:50 to 80:20.

[0009] Preferably, in the composition, the number average molecular weight Mn of the polyether polyol with low glass transition temperature is 2000-4000, and the glass transition temperature Tg is lower than -70℃. The number average molecular weight Mn of the polyester polyol or polycarbonate polyol with medium glass transition temperature is 1000-3000, and the glass transition temperature Tg is -30℃ to 10℃. The diisocyanate is asymmetric aliphatic diisocyanate. The NCO mass content of the base polyurethane prepolymer is 2.0%-5.0%.

[0010] Preferably, in the composition, the high-performance polyurethane damping agent is synthesized in the following way, comprising: First, excess diisocyanate is reacted with multifunctional small molecular alcohol to form core prepolymer with high NCO functionality; then, the high-performance polyurethane damping agent is prepared by reacting the core prepolymer with metered long-chain monofunctional alcohol to consume the remaining NCO groups.

[0011] Preferably, in the composition, the modified nano-filler is at least one of surface-modified carbon nanotube, graphene, and nano-silica.

[0012] Preferably, in the composition, the other filler is carbon black. The catalyst is organic bismuth catalyst. The other auxiliary agent is at least one of antioxidant, ultraviolet absorber, and adhesion promoter. In the composition, the preferred amount of the other auxiliary agent is 0.1-5 parts.

[0013] Preferably, in the above composition, the plasticizer can be DOS, DOTP, DINP and other ester plasticizers, preferably DOS.

[0014] A preparation method of the high-damping polyurethane composition with fast temperature resistance, according to the present application, characterized in that it comprises: The raw materials for the high-damping polyurethane composition according to the present application are prepared according to the formula. The base polyurethane prepolymer, high-performance polyurethane damping agent, modified nano filler, other fillers and plasticizer are added to the stirred tank, stirred at a low speed of 5-15 rpm for 10-15 min, then vacuumized, and then stirred at a high speed of 25-40 rpm for 45-55 min to ensure uniform mixing of the raw materials. The vacuum is released, and other additives and catalysts are added under nitrogen protection. The mixture is vacuumized to-0.095 MPa at a medium speed of 15-25 rpm and stirred for 15-20 min. The product is discharged and stored in a sealed container to obtain a uniform, fine and bubble-free paste-like polyurethane composition, which is the high-damping polyurethane composition with fast temperature resistance.

[0015] Preferably, in the above method, the base polyurethane prepolymer is synthesized in the following manner, comprising: In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet and vacuum system, 50-80 parts by weight of low glass transition temperature polyether polyol and 50-20 parts by weight of medium glass transition temperature polyester polyol or polycarbonate polyol are added. Dehydration is carried out at 120℃ under vacuum of-0.098 MPa for 2.5 hours. The temperature is lowered to 60℃, and the vacuum is released by passing nitrogen. 0.3 parts by weight of antioxidant is added. Under nitrogen protection and stirring, the dropping speed is controlled at 60℃. 23 parts by weight of diisocyanate is added dropwise for 30 min. After dropping, the temperature is raised to 80℃, and 0.02 parts by weight of organic bismuth catalyst is added. The reaction is carried out at constant temperature. The NCO content is titrated by di-n-butylamine method every 1 hour. After 5 hours of reaction, the NCO content is stabilized at 3.5%±0.2%. The temperature is lowered to 60℃, and a light yellow transparent polyurethane resin is obtained, which is the base polyurethane prepolymer.

[0016] Preferably, in the above method, the high-performance polyurethane damping agent is synthesized in the following manner, comprising: In a dry, stirring, thermometer, condenser and nitrogen inlet reaction bottle, 250 parts by weight of diisocyanate and 120 parts by weight of anhydrous xylene are dissolved under nitrogen protection at 60℃, 34.1 parts by weight of multifunctional small molecule alcohol is dissolved in 60 parts of hot anhydrous xylene, and slowly added to the reaction bottle with a constant pressure dropping funnel within 1.5 hours, heated to 80±2℃, reacted for 2-3 hours, the NCO content is close to the theoretical value, cooled to 60℃, slowly added 719 parts by weight of dehydrated polytetrahydrofuran ether diol and 0.1 parts by weight of organic tin catalyst mixed solution to the reaction bottle, 2.5-3h drop completion, heated to 75-80℃, continue to react for 3-5 hours, during the reaction, sample titration until the NCO content reaches the theoretical value for the subsequent blocking agent, cool to 65℃, start adding 26.5 parts by weight of n-octanol, and react for 3-4 hours at 65-70℃, after the reaction is completed, the xylene is removed by reduced pressure evaporation, and a yellow viscous high-performance polyurethane damping agent is obtained.

[0017] Compared with the prior art, the high-damping polyurethane composition resistant to rapid temperature change and the preparation method thereof have the beneficial effects including: Ultra-wide temperature range high damping performance: the damping loss factor (tan δ) can be stably kept above 0.5 in the temperature range of-40℃ to 100℃, and the peak value can reach 1.2-1.8, which is much higher than that of ordinary polyurethane materials. Excellent resistance to rapid temperature change fatigue: after at least 50 high-low temperature impact cycles of-55℃ (keeping for 30min) and +125℃ (keeping for 30min), the tensile strength retention rate of the material is >90%, the damping performance does not obviously attenuate, and the sample has no cracking and debonding phenomenon.

[0018] Excellent comprehensive mechanical properties: while maintaining high damping, the tensile strength of the material is ≥5MPa, and the elongation at break is ≥300%, achieving the balance of high damping, high strength and high toughness.

[0019] Good processability: the viscosity of the composition is moderate, the operable time is long, and it is suitable for conventional polyurethane processing processes such as pouring, potting, coating and the like. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The structure diagram of the high-performance polyurethane damping agent in the high-damping polyurethane composition provided by the embodiment of the application is shown. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the specific contents of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application, which do not constitute a limitation to the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0022] Firstly, the terms possibly used in the present application are described as follows: The term "and / or" means either of the two or both, for example, X and / or Y means three cases including "X" or "Y" or "X and Y".

[0023] The terms "include", "contain", "have", "possess" or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, including a technical feature element (such as raw materials, components, ingredients, carriers, dosage forms, materials, sizes, parts, components, mechanisms, devices, steps, processes, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or articles, etc.) should be interpreted as not only including the explicitly listed technical feature element, but also including other technical feature elements not explicitly listed in the art.

[0024] The term "consisting of" means excluding any technical feature element not explicitly listed. If this term is used in the claims, the term will make the claim closed, so that it does not contain technical feature elements other than the explicitly listed technical feature elements, except for conventional impurities related thereto. If the term only appears in a certain clause of the claim, it is only limited to the elements explicitly listed in that clause, and the elements described in other clauses are not excluded from the overall claim.

[0025] The term "mass parts" means the mass ratio relationship between multiple components, for example: if it is described that the X component is x mass parts and the Y component is y mass parts, it means that the mass ratio of the X component to the Y component is x:y; 1 mass part can represent any mass, for example: 1 mass part can represent 1 kg or 3.1415926 kg, etc. The sum of the mass parts of all components does not necessarily equal 100 parts, and can be greater than 100 parts, less than 100 parts or equal to 100 parts. Unless otherwise specified, the parts, proportions and percentages described in the present application are by mass.

[0026] When concentrations, temperatures, pressures, sizes, or other parameters are expressed in numerical ranges, the numerical ranges should be interpreted as specifically disclosing all possible combinations of the numerical ranges for the maximum value, minimum value, and preferred values within the numerical range, whether the range is expressly recited or not; for example, if a numerical range of "2 to 8" is recited, the numerical range should be interpreted as including ranges of "2 to 7," "2 to 6," "5 to 7," "3 to 4 and 6 to 7," "3 to 5 and 7," "2 and 5 to 7," and the like. Unless otherwise indicated, numerical ranges recited herein are inclusive of the ends and all the integers and fractions within the range.

[0027] The solutions provided by the present application are described in detail below. The content not described in detail in the embodiments of the present application belongs to the prior art known to those skilled in the art. Unless otherwise specified, the conditions in the embodiments of the present application are carried out according to the conventional conditions in the art or the conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used in the embodiments of the present application are conventional products that can be obtained by commercial purchase.

[0028] The high-damping polyurethane composition provided by the embodiments of the present application is resistant to rapid temperature change and can maintain high damping performance and structural integrity in a severe temperature alternating environment, and is suitable for high-speed rail transportation, aerospace instruments, and other fields with extremely high reliability requirements. The high-damping polyurethane composition comprises the following components in parts by weight: matrix polyurethane prepolymer: 100 parts; high-performance polyurethane damping agent: 5-25 parts; modified nanofiller: 0.5-8 parts; other fillers: 3-10 parts; plasticizer: 7-15 parts catalyst: 0.01-0.5 parts; other additives: 0-5 parts, including at least one of an antioxidant, an ultraviolet absorber, and an adhesion promoter.

[0029] In some specific embodiments, the matrix polyurethane prepolymer is prepared by reacting mixed polyols with excess diisocyanate; wherein the mixed polyols comprise polyether polyol (number average molecular weight Mn = 2000-4000, Tg < -70°C) and polyester polyol or polycarbonate polyol (number average molecular weight Mn = 1000-3000, Tg at -30°C to 10°C), and the mass ratio of the two is (50:50) to (80:20).

[0030] The diisocyanate is preferably an asymmetric aliphatic isocyanate, such as isophorone diisocyanate (IPDI).

[0031] The NCO mass content of the base polyurethane prepolymer is controlled at 2.0% to 5.0%.

[0032] In some specific embodiments, in the high-damping polyurethane composition, the high-performance polyurethane damping agent is a star-shaped polymer with a multifunctional small-molecule alcohol (such as pentaerythritol) as a core and a small-molecule polyether polyol or a polyester polyol as an arm. It is synthesized by the following steps: first, an excess of diisocyanate (such as MDI) is reacted with a multifunctional small-molecule alcohol (such as pentaerythritol) to form a high-NCO-functionality core prepolymer; then, a metered amount of a monofunctional long-chain alcohol is reacted, and after the NCO groups are substantially consumed, the obtained high-damping polyurethane resin is the high-performance polyurethane damping agent. The high-damping polyurethane resin contains a large number of terminal soft segment chains and potential intramolecular cavities, can produce strong interchain entanglement and friction with the base polyurethane prepolymer, and at the same time, the contained isocyanate groups also entangle and link with the base polyurethane resin, improving the compatibility.

[0033] In some specific embodiments, in the high-damping polyurethane composition, the modified nanofiller is a surface-modified carbon nanotube, graphene, or nanosilica.

[0034] The innovation of the present application lies in: Soft and hard segment coordinated wide temperature range damping mechanism: the mixed soft segment of low Tg polyether and medium-high Tg polyester is used to make the material have chain segment movement energy contribution to damping in different temperature intervals, realizing the widening of temperature range. At the same time, the asymmetric hard segment structure such as IPDI is selected to inhibit the excessive ordered crystallization of the hard segment and reduce the internal stress caused by the change of crystallinity in thermal cycling.

[0035] High-performance polyurethane damping agent constructs a multi-scale energy dissipation network: a specially designed high-performance polyurethane damping agent is introduced as a damping agent. Its multi-arm structure and a large number of terminal groups form topological entanglement and multiple hydrogen bond effects with the linear base prepolymer, producing strong intermolecular friction and dissipating energy when stressed. Its good chemical compatibility with the base avoids phase separation.

[0036] Skeleton-reinforced composite damping effect: surface-modified nanofillers are used to mechanically mix with the polyurethane matrix to reinforce and toughen, and the interfacial sliding between the nanometer particles and the polymer chains becomes an effective additional damping source. The three are coordinated to construct a multi-scale energy dissipation system from molecular chain friction, entangled network friction to filler interface friction.

[0037] In order to more clearly show the technical solutions provided by the present application and the technical effects produced, the schemes provided by the embodiments of the present application are described in detail below with specific examples.

[0038] Example 1 The embodiment provides a high-damping polyurethane composition resistant to rapid temperature change, and a preparation method thereof as follows (the amount of each raw material is in parts by weight), comprising the following steps: 1) Synthesis of base polyurethane prepolymer (denoted as A1): in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet and a vacuum system, 70 parts of polypropylene glycol (PPG, Mn=2000) and 30 parts of polycaprolactone diol (PCL, Mn=2000) are added. Dehydrate at 120 DEG C under -0.098 MPa vacuum for 2.5 hours. Cool to 60 DEG C, remove the vacuum by passing nitrogen, and add 0.3 parts of antioxidant 1010. Slowly drop 23 parts of isophorone diisocyanate (IPDI) at 60 DEG C under nitrogen protection and stirring, and then raise the temperature to 80 DEG C. Add 0.02 parts of organic bismuth catalyst, and take samples every 1 hour to titrate NCO content by using di-n-butylamine method. After about 5 hours of reaction, the NCO content is stabilized at 3.5%±0.2%, and the temperature is lowered to 60 DEG C to obtain a light yellow transparent polyurethane resin, which is the base polyurethane prepolymer, and is sealed for storage.

[0039] 2) Synthesis of high-performance polyurethane damping agent (denoted as B1): in a dry reaction bottle equipped with a stirrer, a thermometer, a condenser and a nitrogen inlet, 250 parts of 4,4'-diphenyl methane diisocyanate (MDI) and 120 parts of anhydrous xylene are added, and the temperature is raised to 60 DEG C under nitrogen protection to dissolve. 34.1 parts of pentaerythritol are dissolved in 60 parts of hot anhydrous xylene, and a constant-pressure dropping funnel is used to slowly drop the solution into the reaction bottle within 1.5 hours. The temperature is raised to 80±2 DEG C, and the reaction is carried out for 2-3 hours. The NCO content approaches the theoretical value (11.3%), the temperature is lowered to 60 DEG C, and 719 parts of a mixed solution of dehydrated PTMG-1000 and 0.14 parts of catalyst DBTDL is slowly dropped into the reaction bottle. After 2.5-3 hours of dropping, the temperature is raised to 75-80 DEG C, and the reaction is continued for 3-5 hours. During the period, samples are taken for titration until the NCO content reaches the theoretical value (about 1.1%) for the subsequent blocking agent. The temperature is lowered to 65 DEG C, and 26.5 parts of n-octanol is added. The reaction is carried out at 65-70 DEG C for 3-4 hours. After the reaction is completed, anhydrous xylene is removed by reduced pressure evaporation, and a yellow viscous substance is obtained, which is the high-performance polyurethane damping agent (hereinafter referred to as damping agent B1).

[0040] 3) Preparation of high-damping polyurethane sealant resistant to rapid temperature change: the raw materials are taken according to the following parts by weight, and are prepared in a vacuum planetary mixer: base polyurethane prepolymer (A1): 100 parts, high-performance polyurethane damping agent (B1): 15 parts, modified nanofiller: functionalized carbon nanotube (diameter 10-20 nm, length 10-30 μm), 3 parts, other fillers: carbon black, 7 parts, plasticizer: 10 parts, Catalyst: Organic bismuth catalyst (BiCAT® 8117), 0.08 parts, Other additives: Antioxidant 1010 (0.3 parts), ultraviolet absorber (0.5 parts), light stabilizer (0.5 parts) for a total of 1.3 parts, adhesion promoter (0.5 parts).

[0041] Preparation process: The base polyurethane prepolymer (A1), high-performance polyurethane damping agent (B1), plasticizer, functionalized carbon nanotubes, and treated carbon black are added to a stirred tank. Vacuum is drawn, and the mixture is stirred at medium speed for 45 minutes to ensure uniform mixing of the fillers. The vacuum is released. Under nitrogen protection, the aging aids (light stabilizers, etc.), adhesion promoter, and catalyst are added in sequence. High-speed vacuum is drawn to -0.095 MPa, and stirring is performed for 15-20 minutes. The material is discharged and stored in a sealed state to obtain a uniform, fine, and bubble-free paste-like polyurethane compound, which is a high-damping polyurethane composition resistant to rapid temperature changes. The operable time of the composition is about 50 minutes.

[0042] Example 2 The difference between this example and Example 1 is that the amount of high-damping polyurethane polymer (damping agent B1) is adjusted to investigate the effect of the amount of key components.

[0043] 1) The synthesis method of the base polyurethane prepolymer (A1) is the same as in Example 1: 2) The synthesis method of the high-damping polyurethane polymer (B1) is the same as in Example 1.

[0044] 3) Preparation of high-damping polyurethane sealant resistant to rapid temperature changes: The raw materials are prepared in the following weight parts in a vacuum planetary mixer: Base polyurethane prepolymer (A1): 100 parts, High-damping polyurethane polymer (B1): 20 parts, Modified nanofiller: functionalized carbon nanotubes (diameter 10-20 nm, length 10-30 μm), 3 parts Other fillers: carbon black, 7 parts, Plasticizer: 10 parts, Catalyst: Organic bismuth catalyst (BiCAT® 8117), 0.08 parts, Other additives: Antioxidant 1010 (0.3 parts), ultraviolet absorber (0.5 parts), light stabilizer (0.5 parts) for a total of 1.3 parts, adhesion promoter (0.5 parts).

[0045] The preparation process of the high-damping polyurethane sealant resistant to rapid temperature changes is the same as in Example 1.

[0046] Example 3 This example aims to verify that the material can still maintain good performance by optimizing other components when adjusting the soft / hard segment ratio of the base polyurethane prepolymer.

[0047] 1) Synthesis of base polyurethane prepolymer (denoted as A2): In a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet and a vacuum system, 60 parts of polypropylene glycol (PPG, Mn=2000) and 40 parts of polycaprolactone diol (PCL, Mn=2000) were added. Dehydration was carried out at 120°C under a vacuum of -0.098 MPa for 2.5 hours. The temperature was lowered to 60°C, the vacuum was released by passing nitrogen, and 0.3 parts of antioxidant 1010 was added. Under nitrogen protection and stirring, 23.0 parts of isophorone diisocyanate (IPDI) was slowly added dropwise at 60°C. After the dropwise addition was completed, the temperature was raised to 80°C, and 0.02 parts of organic bismuth catalyst was added. The temperature was kept constant, and the NCO content was titrated every hour with di-n-butylamine. After about 5 hours of reaction, the NCO content stabilized at 3.5%±0.2%. The temperature was lowered to 60°C to obtain a light yellow transparent first polyurethane resin (prepolymer A2), which was sealed and stored.

[0048] 2) Synthesis of high-damping polyurethane polymer (B1) in the same manner as in Example 1.

[0049] 3) Preparation of a rapid temperature change resistant high-damping polyurethane sealant, the following ingredients were taken by weight: Base polyurethane prepolymer (A2): 100 parts, High-damping polyurethane polymer (B1): 20 parts, Modified nano filler: nano silicon dioxide (particle size 20 nm), 5 parts, Other fillers: carbon black, 8 parts, Plasticizer: 10 parts, Catalyst: organic bismuth catalyst, 0.10 parts, Other additives: antioxidant 1010 (0.3 parts), ultraviolet absorber UV-327 (0.5 parts), light stabilizer 770 (0.5 parts), total 1.3 parts,

[0050] Adhesion promoter: KH-560, 0.5 parts.

[0051] The preparation process of the rapid temperature change resistant high-damping polyurethane sealant is the same as in Example 1.

[0052] Comparative Example 1 This comparative example provides a polyurethane composition without high-damping polyurethane polymer (B1), aiming to verify the key role of high-damping polyurethane polymer (B1) in damping performance and temperature change resistance.

[0053] Formulation: Except that high damping polyurethane polymer (B1) was not added, the other components and their amounts, and the preparation process were the same as those of Example 1. The share of high damping polyurethane polymer (B1) was replaced with an equal amount of base polyurethane prepolymer (A1) to prepare the polyurethane composition of Comparative Example 1.

[0054] Comparative Example 2 This comparative example provides a polyurethane composition, which is prepared by the following process (the amount of each component is by weight parts), including: In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet and vacuum system, 100 parts of polyoxypropylene glycol (PPG, Mn=2000) was added. Dehydration was carried out at 120°C under a vacuum of -0.098 MPa for 2.5 hours. The temperature was lowered to 60°C, the vacuum was released by passing nitrogen gas, and 0.3 parts of antioxidant 1010 was added. Under nitrogen protection and stirring, 23.0 parts of isophorone diisocyanate (IPDI) was slowly added dropwise at 60°C. After the dropwise addition was completed, the temperature was raised to 80°C, and 0.02 parts of organic bismuth catalyst was added. The temperature was kept constant, and the NCO content was titrated by the di-n-butylamine method every 1 hour. After about 5 hours of reaction, the NCO content was stabilized at 3.5%±0.2%. The temperature was lowered to 60°C to obtain a light yellow transparent first polyurethane resin as a single soft segment prepolymer (denoted as A2), which was sealed and stored.

[0055] Sealant preparation: This single soft segment prepolymer was used, and the other components, amounts and preparation process were the same as those of Example 1 to prepare the polyurethane composition of Comparative Example 2.

[0056] Performance test and result analysis The polyurethane compositions prepared in Examples 1-3 and Comparative Examples 1-2 were cast into standard test bars under the same conditions, and tested after curing at 25°C / 50% RH for 7 days. The main test results are shown in Table 1.

[0057] Table 1 is the test results .

[0058] Result analysis: As can be seen from the above table, the examples 1-3 of the present application all exhibit the characteristics of high strength and high toughness (strength > 6 MPa, elongation > 350%). The strength of the comparative example 2 is the lowest, indicating that the mixed soft segment design has an important contribution to the mechanical strength. According to the test of the damping temperature range, it is shown that the examples 1-3 all exhibit an ultra-wide effective damping temperature range, realizing the "seamless" high damping from low temperature to high temperature. The damping peak value and temperature range of the comparative example 1 are sharply reduced, proving that the damping agent B1 is the core of constructing a wide temperature range high damping network. Although the comparative example 2 has an early low-temperature damping peak (low Tg), the damping decreases rapidly in the high-temperature zone, and the effective temperature range is narrow. Especially after 50 severe thermal shocks, the mechanical properties and damping performance retention rates of the three examples are all higher than 89%, and the appearance is intact, proving the excellent rapid temperature change fatigue resistance of the present application.

[0059] Conclusion: The comparison data of the examples and the comparative examples fully prove that, through the synergistic technical scheme of mixed soft segment matrix design, high-performance damping agent introduction, and modified nano filler composite, the polyurethane composition with ultra-wide temperature range high damping, excellent rapid temperature change fatigue resistance, and high strength and high toughness is successfully prepared.

[0060] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements within the technical range disclosed in the present application can be easily thought by those skilled in the art, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes the prior art known by those skilled in the art.

Claims

1. A high-damping polyurethane composition resistant to rapid temperature changes, characterized in that, The composition comprises the following components in parts by weight: 100 parts of matrix polyurethane prepolymer, 5-25 parts of high-performance polyurethane damping agent 0.5–8 parts of modified nanofiller; Other fillers, 3-10 parts Plasticizer 7-15 parts, Catalyst 0.01–0.5 parts, Other auxiliary agents: 0-5 parts; The matrix polyurethane prepolymer is prepared by reacting a mixture of polyols with an excess of diisocyanate. The mixture of polyols includes polyester polyols or polycarbonate polyols with a medium glass transition temperature and polyether polyols with a low glass transition temperature. The high-performance polyurethane damping agent is a high-damping polyurethane polymer with a multifunctional small molecule alcohol as the core and long-chain monofunctional alcohols as the end caps.

2. The high-damping polyurethane composition resistant to rapid temperature changes according to claim 1, characterized in that, The mass ratio of the low glass transition temperature polyether polyol to the medium glass transition temperature polyester polyol or polycarbonate polyol is 50:50 to 80:

20.

3. The high-damping polyurethane composition resistant to rapid temperature changes according to claim 1 or 2, characterized in that, The polyether polyol with the low glass transition temperature has a number average molecular weight Mn of 2000 to 4000 and a glass transition temperature Tg < -70℃. The number-average molecular weight Mn of the polyester polyol or polycarbonate polyol with a medium glass transition temperature is 1000 to 3000, and the glass transition temperature Tg is -30°C to 10°C. The diisocyanate is an asymmetric aliphatic diisocyanate; The NCO content of the matrix polyurethane prepolymer is 2.0% to 5.0%.

4. The high-damping polyurethane composition resistant to rapid temperature changes according to claim 1 or 2, characterized in that, The high-performance polyurethane damping agent is synthesized in the following manner, including: First, excess diisocyanate is reacted with polyfunctional small molecule alcohol to form a core prepolymer with high NCO functionality; then, it is reacted with a stoichiometric amount of long-chain monofunctional alcohol to consume the remaining NCO groups, thus obtaining a high-performance polyurethane damping agent.

5. The high-damping polyurethane composition resistant to rapid temperature changes according to claim 1 or 2, characterized in that, The modified nanofiller is at least one of surface-modified carbon nanotubes, graphene, and nano-silica.

6. The high-damping polyurethane composition resistant to rapid temperature changes according to claim 1 or 2, characterized in that, The other fillers are carbon black; The catalyst used is an organic bismuth catalyst; The other additives are at least one of antioxidants, ultraviolet absorbers, and adhesion promoters.

7. The high-damping polyurethane composition resistant to rapid temperature changes according to claim 1 or 2, characterized in that, The plasticizer used is an ester-based plasticizer.

8. A method for preparing the high-damping polyurethane composition resistant to rapid temperature change according to any one of claims 1-7, characterized in that, include: The raw materials are prepared according to the formulation of the high-damping polyurethane composition according to any one of claims 1-7; The matrix polyurethane prepolymer, high-performance polyurethane damping agent, modified nanofiller, other fillers and plasticizer are added to a mixing tank and stirred at a low speed of 5-15 rpm for 10-15 minutes. Then, a vacuum is drawn, and the mixture is stirred at a high speed of 25-40 rpm for 45-55 minutes to ensure that all raw materials are mixed evenly. The vacuum is then released, and other additives and catalysts are added under nitrogen protection. The vacuum is drawn to -0.095 MPa at a medium speed of 15-25 rpm and stirred for 15-20 minutes. The mixture is then discharged, sealed and stored to obtain a uniform, fine, bubble-free paste-like polyurethane composition, which is the high-damping polyurethane composition resistant to rapid temperature changes.

9. The method for preparing the high-damping polyurethane composition resistant to rapid temperature changes according to claim 8, characterized in that, The matrix polyurethane prepolymer is synthesized in the following manner, including: In a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet, and vacuum system, 50–80 parts by weight of a polyether polyol with a low glass transition temperature and 50–20 parts by weight of a polyester polyol or polycarbonate polyol with a medium glass transition temperature were added. The mixture was dehydrated at 120°C and under a vacuum of -0.098 MPa for 2.5 hours. The temperature was then lowered to 60°C, and the vacuum was released by purging with nitrogen. 0.3 parts by weight of an antioxidant were added. Under nitrogen protection and stirring, the dropping rate was controlled within 60°C, and 23 parts by weight of diisocyanate were added dropwise over 30 minutes. After the addition was complete, the temperature was raised to 80°C, and 0.02 parts by weight of an organic bismuth catalyst were added. The reaction was carried out at a constant temperature, and samples were taken every hour to titrate the NCO content using the di-n-butylamine method. After 5 hours of reaction, the NCO content stabilized at 3.5% ± 0.2%. The temperature was then lowered to 60°C to obtain a pale yellow transparent polyurethane resin, which is the matrix polyurethane prepolymer.

10. The method for preparing the high-damping polyurethane composition resistant to rapid temperature changes according to claim 8, characterized in that, The high-performance polyurethane damping agent is synthesized in the following manner, including: In a dry reaction flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet, add 250 parts by weight of diisocyanate and 120 parts by weight of anhydrous xylene. Dissolve the xylene by heating to 60°C under nitrogen protection. Dissolve 34.1 parts by weight of a multifunctional small-molecule alcohol in 60 parts by weight of hot anhydrous xylene. Slowly add the solution dropwise to the reaction flask over 1.5 hours using a constant-pressure dropping funnel. Heat to 80±2°C and react for 2–3 hours. When the NCO content approaches the theoretical value, cool the flask to 60°C and add 719 parts by weight of diisocyanate dropwise to the reaction flask. A mixture of 0.1 parts by weight of dehydrated polytetrahydrofuran ether diol and 0.1 parts by weight of organotin catalyst was added dropwise over 2.5–3 hours. The temperature was then raised to 75–80°C, and the reaction continued for 3–5 hours. During this period, samples were taken and titrated until the NCO content reached the theoretical value calculated for subsequent end-capping agents. The temperature was then lowered to 65°C, and 26.5 parts by weight of n-octanol were added. The reaction was maintained at 65–70°C for 3–4 hours. After the reaction was completed, xylene was removed by vacuum distillation, yielding a yellow viscous substance, which is the high-performance polyurethane damping agent.

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