Damping and buffering polyurethane insole material and preparation method thereof
By introducing functional crosslinking agents and regulating soft and hard segments in polyurethane insole materials, multiple physical crosslinking points and reversible covalent bonds are constructed, which solves the shortcomings of traditional polyurethane materials in shock absorption, cushioning and rebound performance, forming an excellent cell structure and improving the material's stability and lifespan.
Patent Information
- Application Number
- CN202610466976.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-10
- Publication Date
- 2026-05-19
AI Technical Summary
Traditional polyurethane insole materials are difficult to optimize in a coordinated manner in terms of shock absorption, cushioning and rebound performance, and the ability to control the cell structure is insufficient, which makes the materials prone to irreversible deformation and performance degradation during long-term use.
A dynamic disulfide bond and hindered phenol structure is constructed using a functional crosslinking agent. Combined with the soft and hard segment regulation of polypropylene glycol and dimethylthiotoluene diamine, energy dissipation and structural stability are achieved through multiple physical crosslinking points and reversible covalent bonds. Combined with a multi-component reaction injection molding process, a uniform and dense pore structure is formed.
This technology enables polyurethane insole materials to achieve efficient energy dissipation and rapid recovery under dynamic impact, maintaining the long-term structural stability of the material and the excellent anti-collapse ability of the cell network, thus significantly extending its service life.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polyurethane materials, specifically to a shock-absorbing and cushioning polyurethane insole material and its preparation method. Background Technology
[0002] Polyurethane materials are widely used in the footwear industry, especially in insole manufacturing, due to their excellent abrasion resistance, flexibility, and controllable physical properties. Traditional polyurethane insoles typically employ a one-step synthesis process, where raw materials such as polyols, isocyanates, chain extenders, and foaming agents are mixed and foamed in a single step. However, the materials prepared by this process exhibit a significant imbalance in their overall mechanical properties. Specifically, to improve the shock absorption and cushioning performance of insoles, it is usually necessary to reduce the material density or increase the proportion of soft segments. However, this leads to a significant decrease in the material's resilience and exacerbates its permanent deformation under long-term stress, resulting in insoles that fail to meet usage requirements in terms of support and dimensional stability. Conversely, increasing the content of hard segments or increasing the crosslinking density to improve resilience results in excessive material rigidity, significantly reducing the shock absorption and cushioning effect, ultimately leading to a stiff feel and poor comfort. Therefore, how to achieve synergistic optimization of shock absorption, cushioning, and resilience performance in a single material system has always been a core technical challenge that urgently needs to be solved in this field.
[0003] From the perspective of molecular chain structure design, existing technologies for controlling polyurethane molecular chains are relatively simple, mainly relying on chemical cross-linking points to provide the material's elastic recovery capability, lacking precise control over chain segment movement. This single energy dissipation mechanism makes it difficult for the material to dissipate energy through various forms of physical interactions when subjected to dynamic impacts, resulting in limited shock absorption and cushioning effects. Furthermore, traditional polyurethane materials struggle to maintain stable damping performance across a wide range of stress frequencies and temperatures, exhibiting a narrow effective damping temperature range that cannot adapt to complex and variable operating environments. Due to the lack of effective physical cross-linking points and the introduction of weak interactions, molecular chains are prone to uncontrolled slippage and rearrangement during stress, further weakening the material's long-term stability.
[0004] In terms of foaming molding processes, traditional polyurethane insole manufacturing methods lack sufficient control over the cell structure. Due to uneven bubble nucleation and bubble merging during foaming, the resulting material typically has a wide pore size distribution, a large average pore size, and is difficult to precisely control. This uncontrollable cell structure not only leads to significant fluctuations in rebound consistency between product batches but also directly affects the material's fatigue life and long-term stability. Traditional polyurethane materials are highly susceptible to irreversible compression set, also known as flattening failure, which severely restricts the lifespan of insoles and the user experience. Summary of the Invention
[0005] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a shock-absorbing and cushioning polyurethane insole material and its application.
[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing a shock-absorbing and cushioning polyurethane insole material, comprising the following preparation steps: Step S1: Mix polyethylene adipate, dimethyl silicone oil, ethylene glycol and water evenly to obtain component A; Step S2: Mix polyethylene adipate, polypropylene glycol, diphenylmethane diisocyanate and phosphoric acid evenly to obtain component B; Step S3: Mix dimethylthiotoluene diamine, ethylene glycol, functional crosslinking agent and water evenly to obtain component C; Step S4: Mix components A, B and C and inject the mixture into the mold. After curing, open the mold and demold to obtain the shock-absorbing and cushioning polyurethane insole material.
[0007] Furthermore, in component A, the proportions of each material by weight are as follows: 90-97 parts of polyethylene adipate, 0.2-1.0 parts of dimethyl silicone oil, 3-10 parts of ethylene glycol, and 0.05-0.1 parts of water.
[0008] Furthermore, in component B, the proportions of each material by weight are as follows: 15-25 parts of polyethylene adipate, 5-10 parts of polypropylene glycol, 70-80 parts of diphenylmethane diisocyanate, and 0.005-0.008 parts of phosphoric acid.
[0009] Furthermore, in component C, the proportions of each material by weight are as follows: 30-35 parts of dimethylthiotoluene diamine, 5-10 parts of ethylene glycol, 5-10 parts of functional crosslinking agent, and 0.5-2.0 parts of water.
[0010] Furthermore, the preparation method of the functional crosslinking agent is as follows: Step A1: Melt diphenylmethane diisocyanate by heating, add dibutyltin dilaurate, and add dithiodiethylene glycol dropwise under inert gas protection. Heat to 75℃-80℃ and react for 1.5h-2h to obtain a prepolymer with free isocyanate groups at the end. Step A2: Cool the prepolymer containing free isocyanate groups at the end to 60℃-65℃, add 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and stir for 1h-1.5h to obtain the grafted hindered phenol prepolymer. Step A3: Add 1,4-butanediol to the grafted hindered phenol prepolymer, heat to 80℃-85℃ and react for 1.5h-2h until NCO (isocyanate group) completely disappears to obtain the chain extended prepolymer; Step A4: Cool the chain-extended prepolymer to 40℃-50℃, add tetraethyl titanate, and stir the reaction for 0.5h-1h to obtain the functional crosslinking agent.
[0011] Furthermore, in the preparation process of the functional crosslinking agent, the materials are proportioned as follows by weight: 40-45 parts of diphenylmethane diisocyanate, 8-12 parts of dithiodiethylene glycol, 15-20 parts of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 15-20 parts of 1,4-butanediol, 0.2-0.5 parts of dibutyltin dilaurate, and 0.5-1.5 parts of tetraethyl titanate.
[0012] Furthermore, in step S4, the mass ratio of component A, component B, and component C is 100:100-120:15-25.
[0013] Further, in step S4, the mixing method for mixing components A, B, and C is as follows: components A, B, and C are respectively transported to the respective material tanks of the high-pressure foaming machine, the material temperature is controlled at 38℃-42℃, and they are transported to the mixing head via a metering pump, where they are impacted and mixed for 2s-5s under a pressure of 15MPa-25MPa.
[0014] Furthermore, in step S4, the mold temperature is controlled at 35℃-55℃, and the curing time is 4min-6min.
[0015] Secondly, the present invention provides a shock-absorbing and cushioning polyurethane insole material, which is prepared by the above-mentioned method for preparing shock-absorbing and cushioning polyurethane insole material.
[0016] The beneficial effects of this invention are: This invention introduces multiple physical crosslinking points and reversible covalent bonds into a polyurethane system by constructing a functional crosslinking agent containing dynamic disulfide bonds and hindered phenolic structures. This unique molecular structure design allows the molecular chain segments to effectively dissipate and rapidly recover energy through the synergistic cooperation of multiple weak interactions when subjected to dynamic impacts. This avoids the problem of traditional polyurethane materials, which rely on a single chemical crosslinking point, making it difficult to simultaneously achieve shock absorption and resilience. Simultaneously, the presence of dynamic covalent bonds endows the material with reversible reorganization capabilities during stress, significantly suppressing uncontrolled slippage of the molecular chains. Therefore, while ensuring excellent shock absorption, it also maintains the structural stability and dimensional accuracy of the material during long-term use.
[0017] This invention optimizes the microstructure of a material by precisely controlling the ratio of soft to hard segments, particularly by introducing polypropylene glycol as a flexible segment component and dimethyl thiotoluene diamine as a rigid segment chain extender. Polypropylene glycol imparts excellent flexibility to the molecular chains, ensuring the material can fully deform during compression to absorb impact energy; while dimethyl thiotoluene diamine promotes the orderly arrangement of hard segment microregions, providing a stable elastic recovery framework for the material. This molecular network, synergistically enhanced by soft and hard segments, fundamentally solves the contradiction of traditional polyurethane insoles being prone to permanent deformation at low densities and exhibiting a stiff feel at high rigidities, achieving a high degree of unity between shock absorption and high resilience.
[0018] This invention combines functional crosslinking agents, soft and hard segment regulating components, and a multi-component reactive injection molding process to form a uniform and dense cell structure during rapid mixing and in-mold curing. The functional crosslinking agent participates in the regulation of interface stability and bubble nucleation during foaming, effectively inhibiting bubble merging and excessive pore size growth, thereby obtaining a closed-cell structure with narrow pore size distribution and high cell density. This highly ordered cell network not only improves the initial cushioning performance of the material but also exhibits excellent anti-collapse ability during long-term dynamic compression fatigue, significantly delaying performance degradation caused by cell structure damage, and significantly extending the service life of insoles, meeting the dual requirements of comfort and durability for high-end footwear materials. Detailed Implementation
[0019] 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.
[0020] The polyethylene adipate used in this invention has CAS number 24938-37-2 and was purchased from Shanghai Hongzhuang Chemical Technology Co., Ltd.
[0021] The polypropylene glycol used in this invention has CAS number 25322-69-4 and was purchased from Hubei Watson Chemical Technology Co., Ltd.
[0022] Example 1 A method for preparing a shock-absorbing and cushioning polyurethane insole material includes the following preparation steps: Preparation of functional crosslinking agents: By weight, take 40 parts of diphenylmethane diisocyanate, 8 parts of dithiodiethylene glycol, 15 parts of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 15 parts of 1,4-butanediol, 0.2 parts of dibutyltin dilaurate, and 0.5 parts of tetraethyl titanate. Step A1: Melt diphenylmethane diisocyanate by heating, add dibutyltin dilaurate, stir at 200 rpm under nitrogen protection, add dithiodiethylene glycol dropwise at a uniform rate over 30 min, and after the addition is complete, heat to 75 °C and react for 1.5 h to obtain a prepolymer with free isocyanate groups at the end. Step A2: Cool the prepolymer containing free isocyanate groups at the end to 60°C, add 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and stir at 200 rpm for 1 hour to obtain the grafted hindered phenol prepolymer. Step A3: Add 1,4-butanediol to the grafted hindered phenol prepolymer, heat to 80°C, and react at a stirring speed of 200 rpm for 1.5 h until NCO is completely eliminated to obtain the chain-extended prepolymer; Step A4: Cool the chain-extended prepolymer to 40°C, add tetraethyl titanate, and stir the reaction at 200 rpm for 0.5 h to obtain the functional crosslinking agent.
[0023] Step S1: Take 90 parts by weight of polyethylene adipate, 0.2 parts by weight of dimethyl silicone oil, 3 parts by weight of ethylene glycol, and 0.05 parts by weight of water; mix polyethylene adipate, dimethyl silicone oil, ethylene glycol, and water evenly to obtain component A; Step S2: By weight, take 15 parts of polyethylene adipate, 5 parts of polypropylene glycol, 70 parts of diphenylmethane diisocyanate, and 0.005 parts of phosphoric acid; mix polyethylene adipate, polypropylene glycol, diphenylmethane diisocyanate, and phosphoric acid evenly to obtain component B; Step S3: By weight, take 30 parts of dimethylthiotoluene diamine, 5 parts of ethylene glycol, 5 parts of functional crosslinking agent, and 0.5 parts of water; mix the dimethylthiotoluene diamine, ethylene glycol, functional crosslinking agent, and water evenly to obtain component C; Step S4: Components A, B, and C are fed into the A, B, and C tanks of the high-pressure foaming machine at a mass ratio of 100:100:15, respectively. The temperature of each component is controlled at 38°C. The three components are then fed into the mixing head at a set ratio using a metering pump. The mixture is then impacted and mixed for 2 seconds under an impact pressure of 15 MPa. The mixture is then immediately injected into a mold preheated to 35°C. After curing for 4 minutes, the mold is opened and the material is demolded to obtain the shock-absorbing and cushioning polyurethane insole material.
[0024] Example 2 A method for preparing a shock-absorbing and cushioning polyurethane insole material includes the following preparation steps: Preparation of functional crosslinking agents: By weight, take 42 parts of diphenylmethane diisocyanate, 10 parts of dithiodiethylene glycol, 18 parts of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 18 parts of 1,4-butanediol, 0.4 parts of dibutyltin dilaurate, and 0.8 parts of tetraethyl titanate. Step A1: Melt diphenylmethane diisocyanate by heating, add dibutyltin dilaurate, stir at 300 rpm under nitrogen protection, add dithiodiethylene glycol dropwise at a uniform rate over 45 min, and after the addition is complete, heat to 78 °C and react for 1.8 h to obtain a prepolymer with free isocyanate groups at the end. Step A2: Cool the prepolymer containing free isocyanate groups at the end to 62°C, add 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and stir at 300 rpm for 1.2 h to obtain the grafted hindered phenol prepolymer. Step A3: Add 1,4-butanediol to the grafted hindered phenol prepolymer, heat to 82°C, and react at a stirring speed of 300 rpm for 1.8 h until NCO is completely eliminated to obtain the chain-extended prepolymer; Step A4: Cool the chain-extended prepolymer to 45°C, add tetraethyl titanate, and stir the reaction at 300 rpm for 0.8 h to obtain the functional crosslinking agent.
[0025] Step S1: By weight, take 94 parts of polyethylene adipate, 0.6 parts of dimethyl silicone oil, 6 parts of ethylene glycol, and 0.07 parts of water; mix polyethylene adipate, dimethyl silicone oil, ethylene glycol, and water evenly to obtain component A; Step S2: By weight, take 20 parts of polyethylene adipate, 8 parts of polypropylene glycol, 75 parts of diphenylmethane diisocyanate, and 0.006 parts of phosphoric acid; mix polyethylene adipate, polypropylene glycol, diphenylmethane diisocyanate, and phosphoric acid evenly to obtain component B; Step S3: By weight, take 33 parts of dimethylthiotoluene diamine, 7 parts of ethylene glycol, 7 parts of functional crosslinking agent, and 1 part of water; mix the dimethylthiotoluene diamine, ethylene glycol, functional crosslinking agent, and water evenly to obtain component C; Step S4: Components A, B, and C are fed into the A, B, and C tanks of the high-pressure foaming machine at a mass ratio of 100:110:20, respectively. The temperature of each component is controlled at 40℃. The three components are fed into the mixing head according to the set ratio through a metering pump. They are impacted and mixed for 4 seconds under an impact pressure of 20MPa. Then, they are immediately injected into a mold preheated to 45℃. After curing for 5 minutes, the mold is opened and demolded to obtain the shock-absorbing and cushioning polyurethane insole material.
[0026] Example 3 A method for preparing a shock-absorbing and cushioning polyurethane insole material includes the following preparation steps: Preparation of functional crosslinking agents: By weight, take 45 parts of diphenylmethane diisocyanate, 12 parts of dithiodiethylene glycol, 20 parts of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 20 parts of 1,4-butanediol, 0.5 parts of dibutyltin dilaurate, and 1.5 parts of tetraethyl titanate. Step A1: Melt diphenylmethane diisocyanate by heating, add dibutyltin dilaurate, stir at 400 rpm under nitrogen protection, add dithiodiethylene glycol dropwise at a uniform rate over 60 min, and after the addition is complete, heat to 80℃ and react for 2 h to obtain a prepolymer with free isocyanate groups at the end. Step A2: Cool the prepolymer containing free isocyanate groups at the end to 65°C, add 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and stir at 400 rpm for 1.5 h to obtain the grafted hindered phenol prepolymer. Step A3: Add 1,4-butanediol to the grafted hindered phenol prepolymer, heat to 85°C, and react at a stirring speed of 400 rpm for 2 hours until NCO is completely eliminated to obtain the chain-extended prepolymer. Step A4: Cool the chain-extended prepolymer to 50°C, add tetraethyl titanate, and stir at 400 rpm for 1 hour to obtain the functional crosslinking agent.
[0027] Step S1: By weight, take 97 parts of polyethylene adipate, 1.0 part of dimethyl silicone oil, 10 parts of ethylene glycol, and 0.1 parts of water; mix polyethylene adipate, dimethyl silicone oil, ethylene glycol, and water evenly to obtain component A; Step S2: By weight, take 25 parts of polyethylene adipate, 10 parts of polypropylene glycol, 80 parts of diphenylmethane diisocyanate, and 0.008 parts of phosphoric acid; mix polyethylene adipate, polypropylene glycol, diphenylmethane diisocyanate, and phosphoric acid evenly to obtain component B; Step S3: By weight, take 35 parts of dimethylthiotoluene diamine, 10 parts of ethylene glycol, 10 parts of functional crosslinking agent, and 2 parts of water; mix the dimethylthiotoluene diamine, ethylene glycol, functional crosslinking agent, and water evenly to obtain component C; Step S4: Components A, B, and C are fed into the A, B, and C tanks of the high-pressure foaming machine at a mass ratio of 100:120:25, respectively. The temperature of each component is controlled at 38°C. The three components are then fed into the mixing head at a set ratio using a metering pump. The mixture is then impacted and mixed for 5 seconds under an impact pressure of 25 MPa. The mixture is then immediately injected into a mold preheated to 55°C. After curing for 6 minutes, the mold is opened and the material is demolded to obtain the shock-absorbing and cushioning polyurethane insole material.
[0028] Comparative Example 1 Compared with Example 1, the "functional crosslinking agent" in this comparative example is replaced with "chain extender prepolymer"; the remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, polyurethane insole material is obtained.
[0029] Comparative Example 2 Compared with Example 1, in step A2, "3,5-di-tert-butyl-4-hydroxybenzyl alcohol" was replaced with "n-butanol"; the remaining steps and parameters were the same, and will not be repeated in this comparative example. Finally, polyurethane insole material was obtained.
[0030] Comparative Example 3 Compared with Example 1, in step A1, "dithiodiethylene glycol" was replaced with an equimolar amount of "1,6-hexanediol"; the remaining steps and parameters were the same, and will not be repeated here. The final product was a polyurethane insole material.
[0031] Comparative Example 4 Compared with Example 1, in this comparative example, "polypropylene glycol" in component B is replaced with an equimolar amount of "polyethylene adipate" (both are diols with a functionality of 2, and equimolar replacement means equimolar hydroxyl equivalent replacement); the remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, polyurethane insole material is obtained.
[0032] Comparative Example 5 Compared with Example 1, in this comparative example, "dimethylthiotoluene diamine" in component C is replaced with an equimolar amount of "ethylenediamine" (both are diamines with a functionality of 2, and equimolar replacement means equi-amino equivalent replacement); the remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, a polyurethane insole material is obtained.
[0033] The shock-absorbing and cushioning polyurethane insole materials prepared in Examples 1-3 and the polyurethane insole materials prepared in Comparative Examples 1-5 were tested.
[0034] Compression set test: Following ASTM D395 Method B, cylindrical specimens with a diameter of 29.0 mm ± 0.5 mm and a height of 12.5 mm ± 0.5 mm were cut from the polyurethane insole materials prepared in Examples 1-3 and Comparative Examples 1-5. The specimens were placed in a compression device, clamped between two parallel plates at a constant compression rate (25% of the specimen thickness), and placed in a constant temperature chamber at 70°C for 22 hours. After the specified time, the specimens were unloaded and allowed to recover freely at room temperature for 30 minutes. Finally, the recovered thickness was measured using a thickness gauge, and the compression set (%) was calculated. The results are recorded in Table 1.
[0035] Drop ball rebound performance test: Referring to GB / T 6670-2008, the polyurethane insole materials prepared in Examples 1-3 and Comparative Examples 1-5 were cut into samples with a thickness of not less than 50 mm and an area sufficient to cover the test base, and placed on a rebound tester. A steel ball with a diameter of 16 mm was dropped freely from a height of 500 mm onto the sample surface, and the initial rebound height of the steel ball was recorded. The rebound rate is the percentage of the rebound height to the drop height. Multiple tests were performed on each sample, and the average value was taken. The results are recorded in Table 1.
[0036] Cell structure characterization and testing: Polyurethane insole material was cut into 10mm×10mm×5mm samples along the cross section. After liquid nitrogen freezing and gold sputtering, the cell morphology was observed using a scanning electron microscope (SEM) at 50x and 200x magnification. The average pore size, pore size distribution coefficient (pore size standard deviation / average pore size) and cell density (number of cells per unit area, cells / mm²) were statistically analyzed using image analysis software. The results are recorded in Table 2.
[0037] Compression fatigue life test: Referring to the national standard GB / T 18941-2003, the sample was processed into a polyurethane insole material of 50mm×50mm×25mm. In an environment of 23℃ and 50% relative humidity, the sample was subjected to dynamic compression test using a fatigue testing machine. The compression stroke was 30% of the original thickness, the compression frequency was 3Hz, and after 100,000 consecutive compressions, the resilience rate (testing method is the same as the drop ball resilience test mentioned above), average pore size, pore size distribution coefficient, and cell density (number of cells per unit area, cells / mm²) of the polyurethane insole material after compression fatigue life test were recorded in Table 3.
[0038] The method for testing the resilience of polyurethane insole material after compression fatigue life testing is the same as the drop ball rebound performance test described above; the methods for testing the average pore size, pore size distribution coefficient, and cell density of polyurethane insole material after compression fatigue life testing are the same as the cell structure characterization test described above.
[0039] Table 1: Results of Compression Permanent Deformation Rate and Falling Ball Rebound Performance Tests
[0040] Table 2: Initial bubble structure characterization and detection results
[0041] Table 3: Performance and cell structure test results after 100,000 compression fatigue cycles
[0042] As shown in Tables 1 to 3, the shock-absorbing and cushioning polyurethane insole materials prepared in Examples 1-3 of this invention exhibit excellent performance in terms of compression set, ball rebound rate, cell structure uniformity, and performance retention rate after compression fatigue life. Their overall performance is significantly better than that of Comparative Examples 1-5.
[0043] As can be seen from Example 1 and Comparative Example 1, Comparative Example 1 replaced the "functional crosslinking agent" with the "chain extender prepolymer" and did not undergo tetraethyl titanate treatment. It lacked metal coordination crosslinking points, and the system only had a single chemical crosslinking structure, which could not form a multi-network synergistic effect. This resulted in an increase in compression set, a decrease in resilience, and a deterioration in the cell structure. This indicates that the metal coordination crosslinking points introduced by tetraethyl titanate play a key role in constructing a multi-network and improving buffer resilience and fatigue resistance.
[0044] As can be seen from Example 1 and Comparative Example 2, replacing "3,5-di-tert-butyl-4-hydroxybenzyl alcohol" with "n-butanol" and not adding hindered phenolic groups during the preparation of the functional crosslinking agent in Comparative Example 2 resulted in the material lacking energy dissipation mechanisms such as hydrogen bonding and other weak interactions. This led to a significant increase in compression set, a significant decrease in resilience, and a deterioration in the uniformity of the cell structure. This indicates that hindered phenolic groups play an irreplaceable role in constructing multiple weak interaction networks, synergistically dissipating impact energy, and improving the shock absorption and buffering performance of the material.
[0045] As can be seen from Example 1 and Comparative Example 3, replacing "dithiodiethylene glycol" with an equimolar amount of "1,6-hexanediol" in step A1 results in the absence of dynamic disulfide bonds in the material, making it impossible to achieve reversible covalent crosslinking. The molecular chains are prone to uncontrollable slippage during the stress process, resulting in increased compression set, decreased resilience, and collapse of the cell structure. This indicates that dynamic disulfide bonds play a key role in endowing the material with reversible reforming ability, inhibiting permanent deformation, and maintaining long-term structural stability.
[0046] As shown in Example 1 and Comparative Example 4, in Comparative Example 4, the "polypropylene glycol" in component B was replaced with an equimolar amount of "polyethylene adipate". Polypropylene glycol is a flexible segment, giving the molecular chain good flexibility, while polyethylene adipate has relatively high rigidity. The replacement disrupted the synergistic regulation of the ratio of soft and hard segments, leading to increased material rigidity and decreased flexibility. Test data showed that the compression set rate of Comparative Example 4 was significantly higher than that of Example 1, the rebound rate was significantly lower, the average pore size increased, the pore size distribution widened, and the cell density decreased. After fatigue testing, the rebound rate further decreased, and the cell structure deteriorated more severely. This indicates that the introduction of polypropylene glycol plays a crucial role in optimizing the ratio of soft and hard segments and improving the material's shock absorption and structural stability; its absence leads to decreased material cushioning performance and increased permanent deformation.
[0047] As shown in Example 1 and Comparative Example 5, in Comparative Example 5, "dimethylthiotoluene diamine" in component C was replaced with an equimolar amount of "ethylenediamine". Dimethylthiotoluene diamine is an aromatic diamine chain extender, which can promote the orderly arrangement of hard segment microregions and form a stable elastic recovery framework; while ethylenediamine is an aliphatic diamine with higher reactivity, but it is difficult to form ordered hard segment microregions, resulting in impaired material rigidity and elastic recovery capabilities. Test data showed that the compression set rate of Comparative Example 5 was significantly higher than that of Example 1, the drop ball rebound rate was significantly lower, the average pore size was significantly larger, the pore size distribution was significantly wider, and the cell density was significantly lower. After fatigue testing, the rebound rate further decreased, and the cell structure severely collapsed. This indicates that dimethylthiotoluene diamine plays an irreplaceable role in constructing stable hard segment microregions and improving the material's resilience and resistance to compressive fatigue.
[0048] In summary, this invention introduces a dynamic reversible cross-linking structure through a functional cross-linking agent and combines the synergistic regulation of the soft and hard segments of polypropylene glycol and dimethylthiotoluene diamine to successfully prepare a polyurethane insole material that combines excellent shock absorption and cushioning performance, high resilience, uniform cell structure, and excellent resistance to compression fatigue. This material is significantly superior to the comparative examples and has important industrial application value and promotion prospects.
[0049] The above description is merely an example and illustration of the concept 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 concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.
Claims
1. A method for preparing a shock-absorbing and cushioning polyurethane insole material, characterized in that, The preparation steps include the following: Step S1: Mix polyethylene adipate, dimethyl silicone oil, ethylene glycol and water evenly to obtain component A; Step S2: Mix polyethylene adipate, polypropylene glycol, diphenylmethane diisocyanate and phosphoric acid evenly to obtain component B; Step S3: Mix dimethylthiotoluene diamine, ethylene glycol, functional crosslinking agent and water evenly to obtain component C; Step S4: Mix components A, B and C and inject the mixture into the mold. After curing, open the mold and demold to obtain the shock-absorbing and cushioning polyurethane insole material.
2. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 1, characterized in that, In component A, the proportions of each material by weight are as follows: 90-97 parts of polyethylene adipate, 0.2-1.0 parts of dimethyl silicone oil, 3-10 parts of ethylene glycol, and 0.05-0.1 parts of water.
3. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 1, characterized in that, The components of component B are formulated as follows by weight: 15-25 parts polyethylene adipate, 5-10 parts polypropylene glycol, 70-80 parts diphenylmethane diisocyanate, and 0.005-0.008 parts phosphoric acid.
4. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 1, characterized in that, The components of component C are formulated as follows by weight: 30-35 parts of dimethylthiotoluene diamine, 5-10 parts of ethylene glycol, 5-10 parts of functional crosslinking agent, and 0.5-2.0 parts of water.
5. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 4, characterized in that, The preparation method of the functional crosslinking agent is as follows: Step A1: Melt diphenylmethane diisocyanate by heating, add dibutyltin dilaurate, and add dithiodiethylene glycol dropwise under inert gas protection. Heat to 75℃-80℃ and react for 1.5h-2h to obtain a prepolymer with free isocyanate groups at the end. Step A2: Cool the prepolymer containing free isocyanate groups at the end to 60℃-65℃, add 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and stir for 1h-1.5h to obtain the grafted hindered phenol prepolymer. Step A3: Add 1,4-butanediol to the grafted hindered phenol prepolymer, heat to 80℃-85℃ and react for 1.5h-2h until NCO is completely eliminated to obtain the chain-extended prepolymer; Step A4: Cool the chain-extended prepolymer to 40℃-50℃, add tetraethyl titanate, and stir the reaction for 0.5h-1h to obtain the functional crosslinking agent.
6. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 5, characterized in that, In the preparation of the functional crosslinking agent, the materials are proportioned as follows by weight: 40-45 parts of diphenylmethane diisocyanate, 8-12 parts of dithiodiethylene glycol, 15-20 parts of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 15-20 parts of 1,4-butanediol, 0.2-0.5 parts of dibutyltin dilaurate, and 0.5-1.5 parts of tetraethyl titanate.
7. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 1, characterized in that, In step S4, the mass ratio of component A, component B, and component C is 100:100-120:15-25.
8. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 1, characterized in that, In step S4, the mixing method for components A, B, and C is as follows: components A, B, and C are respectively fed into the respective material tanks of the high-pressure foaming machine, the material temperature is controlled at 38℃-42℃, and they are fed to the mixing head by a metering pump and mixed by impact under a pressure of 15MPa-25MPa for 2s-5s.
9. The method for preparing a shock-absorbing and cushioning polyurethane insole material according to claim 1, characterized in that, In step S4, the mold temperature is controlled at 35℃-55℃, and the curing time is 4min-6min.
10. A shock-absorbing and cushioning polyurethane insole material, characterized in that, It is prepared by the method for preparing the shock-absorbing and cushioning polyurethane insole material according to any one of claims 1-9.