TPU surface layer foamed material, preparation method and application thereof

Abstract

The application discloses a TPU surface layer foaming material, a preparation method and application thereof, and belongs to the technical field of foaming materials. In view of the problem that existing TPU foaming materials are difficult to consider antibiosis, antifouling, hydrolysis resistance and long-term use durability, the application first terminates the carboxyl group of polycaprolactone dihydric alcohol by using adipic anhydride, then performs ring-opening reaction with KH-560 to introduce trimethoxysilane end groups, and prepares hydrolysis-resistant modified polyol; meanwhile, an antibacterial and antifouling modified chain extender is prepared by copolymerizing a double bond-containing quaternary ammonium salt monomer and SH-PDMS through thiol-ene click reaction. The target material is prepared by supercritical foaming after polymerization of the above-mentioned modified components and diisocyanate. The water contact angle of the obtained product reaches 143.5 degrees, the antibacterial rate on staphylococcus aureus reaches more than 97%, and the performance is good after accelerated hydrolysis aging.

Description

Technical Field

[0001] This invention relates to the field of foaming materials technology, specifically to TPU surface layer foaming materials, preparation methods, and applications. Background Technology

[0002] Thermoplastic polyurethane (TPU) is widely used in footwear, synthetic leather, and medical supplies due to its excellent physical and mechanical properties. However, its surface is prone to bacterial growth and is hydrophilic and easily stained. Existing technologies typically introduce organosilicon quaternary ammonium salts into the polyurethane system through chemical grafting. For example, the scheme disclosed in prior art document (CN 112679689 B) grafts organosilicon quaternary ammonium salts onto polyurethane side chains. The physical migration of organosilicon segments to the material surface leads to the enrichment of quaternary ammonium salt cations to achieve antibacterial and antifouling effects.

[0003] However, this type of "branch physical migration" mode has inherent limitations: First, there is a lack of strong interaction between functional groups and the matrix. Under repeated washing, friction, or humid and hot environments, the surface enrichment layer is prone to reconstruction and loss, resulting in rapid decay of antibacterial and antifouling properties and insufficient durability. Second, the organosilicon introduced by the branch has a significant difference in polarity with the polyurethane soft segment, which can easily induce excessive phase separation, destroy the cell wall strength required for microfoamed materials, and affect the mechanical properties and foaming stability of the product.

[0004] In conclusion, how to endow TPU foam materials with long-lasting anti-fouling and antibacterial functions without sacrificing the excellent mechanical properties of TPU has become an urgent technical problem to be solved. Summary of the Invention

[0005] (a) Technical problems to be solved The present invention provides a TPU foam material that is resistant to hydrolysis, stain-resistant, and antibacterial, and its preparation method.

[0006] (II) Technical Solution A TPU surface foam material includes a modified polyol, and based on 100 parts of the modified polyol, further includes the following components by weight: 15-35 parts diisocyanate derivative, 6-12 parts co-chain extender; The modified polyol is prepared by reacting polyester polyol, acid anhydride and monoepoxide compound; The diisocyanate derivatives include at least one of aromatic diisocyanates, aliphatic diisocyanates, or alicyclic diisocyanates.

[0007] Preferably, the modified polyol is prepared by the following method: a polyester polyol is reacted with an acid anhydride to obtain a carboxyl-containing intermediate; after cooling, a monoepoxide compound is added to the carboxyl-containing intermediate, and a second reaction is carried out under the action of a catalyst to obtain the modified polyol.

[0008] Preferably, the molar ratio between the polyester polyol, acid anhydride and monoepoxide is 1:0.9-1.1:0.9-1.1; the temperature of the first reaction is 100-120℃ and the reaction time is 1-3h; the temperature of the second reaction is 80-100℃ and the reaction time is 2-4h; the catalyst is an organic bismuth catalyst, and its amount is 0.1-0.5 wt% of the monoepoxide.

[0009] Preferably, the polyester polyol includes one or more of polycaprolactone diol (PCL) and branched aliphatic polyester polyols. Preferably, the acid anhydride includes one or more of adipic anhydride, sebacic anhydride, lauric anhydride, and palmitic anhydride; Preferably, the monoepoxide compound includes one or more of γ-glycidyl etherpropyltrimethoxysilane (KH-560) and γ-glycidyl etherpropylmethyldimethoxysilane.

[0010] Preferably, the branched aliphatic polyester polyol is synthesized from one or two of BEPG and BEPD as monomers.

[0011] Preferably, the co-chain extender comprises a combination of 1,4-butanediol (BDO) and a modified chain extender, wherein the mass ratio of BDO to the modified chain extender is 1:0.05-0.15. The modified chain extender is prepared by dissolving dihydroxyethylallyl quaternary ammonium salt (MDAAC) and mercaptopropyl-terminated polydimethylsiloxane (SH-PDMS) in an organic solvent, adding a photoinitiator, and then stirring under ultraviolet light. After the reaction is completed, the organic solvent is removed by rotary evaporation, the resulting residue is dissolved in dichloromethane, and extracted with a methanol-water mixed solvent. Finally, the residue is dried, filtered, and the solvent is removed by vacuum evaporation to obtain the modified chain extender.

[0012] Preferably, the molar ratio of the dihydroxyethylallyl quaternary ammonium salt to the mercaptopropyl-terminated polydimethylsiloxane is 2-2.5:1; the photoinitiator is DMPA, and its amount is 1-5 wt% of the dihydroxyethylallyl quaternary ammonium salt; the ultraviolet irradiation reaction time is 60-80 min; the organic solvent includes one or more of dichloromethane and toluene; the extraction is performed 3 times; and the volume ratio of methanol to water in the methanol-water mixed solvent is 1:0.9-1.1.

[0013] A method for preparing a TPU surface foam material includes the following steps: S1. Preparation of TPU masterbatch: Modified polyol, diisocyanate and organometallic catalyst are mixed and stirred at 75-90℃ for 3-8h. Then, co-chain extender is added and cured at 80-90℃ for 10-20h to obtain solid TPU masterbatch. S2. High-pressure impregnation saturation: The TPU masterbatch is placed in a high-pressure autoclave and sealed. Supercritical gas is introduced and the pressure is controlled at 18-22MPa and the temperature at 70-80℃. The constant temperature and pressure are maintained for 45-90 minutes to allow the supercritical gas to fully penetrate into the masterbatch, thereby obtaining TPU masterbatch containing saturated gas. S3. Heating and foaming molding: Quickly remove the saturated TPU masterbatch and place it in a constant temperature heat medium of 80-120℃ for foaming for 0.1-2 minutes. Finally, place the foamed particles in a pressure-holding container, introduce CO2 to 1.5MPa, and hold the pressure for 15-18 hours to obtain the TPU surface foam material.

[0014] Preferably, the organometallic catalyst in S1 includes one or more of organobismuth and organozinc catalysts; the supercritical gas in S2 includes one or more of carbon dioxide and nitrogen.

[0015] Preferably, the TPU surface foam material prepared by the preparation method is used in the preparation of shoe materials.

[0016] The beneficial effects of this invention are as follows: 1. This invention introduces carboxyl groups and forms ester bonds through the reaction of polyester polyol with acid anhydride. Simultaneously, the carboxyl groups undergo ring-opening addition with an epoxy compound, attaching trimethoxysilane groups to both ends of the polyester polyol molecular chain via β-hydroxy ester bonds through end-group grafting. The main chain itself remains unchanged, continuing to provide the material's basic mechanical strength and elasticity. During TPU curing and foaming, the end-group-introduced trimethoxysilane groups form a Si-O-Si crosslinked network through hydrolysis-condensation reactions. This network constructs a hydrophobic barrier around the polyester soft segments, effectively blocking water molecules from attacking the ester bonds, thereby improving the material's hydrolysis resistance. Compared to traditional blending modifications where functional additives rely on physical dispersion leading to easy migration and precipitation, this invention covalently grafts ether bonds and siloxane groups onto the molecular chain, resulting in more durable hydrolysis resistance and a more uniform distribution of functional components within the material.

[0017] 2. This invention modifies the surface properties of TPU foam materials by introducing a modified chain extender containing polydimethylsiloxane and quaternary ammonium salt segments. This effectively reduces the surface energy of the material, endowing it with hydrophobic and antifouling self-cleaning properties, preventing liquid wetting and the adhesion of organic pollutants. Furthermore, the quaternary ammonium salt component in the chain extender structure imparts long-lasting antibacterial properties, effectively inhibiting the adhesion and reproduction of bacteria and fungi on and inside the cell surface. All of these functions are covalently linked to the molecular chain and will not migrate or be lost due to use or washing, giving the material both durable hydrophobic and antifouling properties and antibacterial properties. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, structure, features and effects of the present invention, in conjunction with the scheme and preferred embodiments, is provided below.

[0019] The following provides a detailed description of specific embodiments of the present invention. Unless otherwise specified, the materials and reagents used in the specific embodiments described herein are commercially available. Experimental methods not specified in the examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0020] Preparation of dihydroxyethylallyl quaternary ammonium salt (MDAAC): N-methyldiethanolamine (MDEA) and allyl chloride were mixed in a molar ratio of 1:1.3 and stirred at 50°C for 60 min without solvent. After recrystallization and purification, MDAAC was obtained.

[0021] Example 1 S1. Preparation of modified polyols: 1 mol of PCL and 1 mol of adipic anhydride were added to a reaction vessel and reacted at 110 °C for 2 h to obtain a carboxyl-containing intermediate. The temperature was lowered to 90 °C, and 1 mol of KH-560 and 0.3 wt% of an organic bismuth catalyst (based on the mass of KH-560) were added to the carboxyl-containing intermediate. The reaction was carried out at 90 °C for 3 h to obtain a modified polyol.

[0022] S2. Grafting to obtain modified chain extenders: 2.25 mol MDAAC and 1 mol SH-PDMS were dissolved in dichloromethane, and DMPA (3 wt% of MDAAC) was added. The mixture was irradiated under UV light and stirred for 70 min. After the reaction was complete, the organic solvent was removed by rotary evaporation. The residue was dissolved in dichloromethane and extracted three times with a methanol-water mixture (methanol to water volume ratio of 1:1). After drying with anhydrous sodium sulfate and filtering, the solvent was removed by vacuum evaporation to obtain the modified chain extender.

[0023] The characterization results of the modified chain extender are as follows: Fourier transform infrared spectroscopy (FT-IR) (KBr) test / cm-1: 3450(br, m, νO-H+νN-H), 2962(s,νasCH3), 2908(s,νasCH2), 2855(s,νsCH3), 1728(s, νC=O), 1462(m,δasCH3), 1410(m,δCH2), 1259(s,δSi-CH3), 1120(vs, br,νasSi-O-Si), 1095(s,νC-OC), 1020(m,νsSi-O-Si), 840(vs,γSi-CH3), 700(m,ρCH2).

[0024] Nuclear magnetic resonance spectrometer (NMR) 1 ¹H NMR (CDCl₃, 400 MHz) test / ppm: δ 4.20 (t, 2H), 3.65 (s, 3H), 3.50~3.30 (m, 4H), 2.85~2.60 (m, 2H), 1.95~1.75 (m, 2H), 1.65~1.45 (m, 2H), 1.20 (s, 3H), 0.88 (t, 3H), 0.55~0.35 (m, 2H), 0.08 (s, ~45H).

[0025] Based on the FT-IR characterization results, an extremely strong and broad peak appears at 1120 cm⁻¹, and at 840 cm⁻¹... -1 The extremely strong peaks at 1728 cm⁻¹ are attributed to the asymmetric stretching vibration of the Si-O-Si bond and the in-plane rocking vibration of the Si-CH₃ group in the polydimethylsiloxane (PDMS) chain, respectively. The strong absorption peak at 1728 cm⁻¹ is attributed to the stretching vibration of the ester carbonyl group (C=O) on the MDAAC backbone. Compared to the starting material, the SH stretching vibration peak at 2570 cm⁻¹ almost disappears in the product spectrum, and the C=C stretching vibration peak is significantly weakened, indicating that the mercapto-alkene click reaction proceeds efficiently. 1 ¹H NMR characterization showed that the extremely strong single peak at δ 0.08 was attributed to Si-(CH) in the PDMS chain segment. 3)2 The protons at δ 3.50~3.30 and δ 2.85~2.60 are attributed to the methylene protons on both sides of the newly formed thioether bond (-CH2-CH2-S-); in summary, SH-PDMS has been successfully grafted onto the MDAAC molecule via covalent bonds, thus obtaining the target modified chain extender.

[0026] The co-chain extender is composed of BDO and modified chain extender at a mass ratio of 1:0.1.

[0027] S3. Preparation of TPU masterbatch: 100 parts of modified polyol, 25 parts of HDI (1,6-hexamethylene diisocyanate), and 0.1 parts of organic bismuth catalyst were mixed and stirred at 82.5℃ for 5.5 h. Then, 9 parts of co-chain extender (8.2 parts of BDO and 0.8 parts of modified chain extender) were added and cured at 85℃ for 15 h to obtain solid TPU masterbatch.

[0028] S4. Preparation of TPU surface foam material: TPU masterbatch was placed in an autoclave and sealed. CO2 was introduced, and the pressure was controlled at 20 MPa and the temperature at 75°C. This constant temperature and pressure was maintained for 67.5 minutes to allow the supercritical gas to fully permeate into the masterbatch, resulting in TPU masterbatch saturated with gas. The saturated TPU masterbatch was then quickly removed and placed in a constant temperature water bath at 100°C for 1 minute to foam. Finally, the foamed particles were placed in a pressure-holding container, and CO2 was introduced to 1.5 MPa. The pressure was maintained for 16.5 hours to obtain the TPU surface foam material.

[0029] Example 2 S1. Preparation of modified polyols: 0.9 mol PCL and 0.9 mol adipic anhydride were added to a reaction vessel and reacted at 110 °C for 2 h to obtain a carboxyl-containing intermediate. The temperature was lowered to 90 °C, and 0.9 mol KH-560 and 0.1 wt% organic bismuth catalyst (based on the mass of KH-560) were added to the intermediate. The reaction was continued at 90 °C for 3 h to obtain the modified polyol.

[0030] S2. Grafting to obtain modified chain extenders: 2 mol MDAAC and 1 mol SH-PDMS were dissolved in dichloromethane, and 1 wt% (by weight of MDAAC) of photoinitiator DMPA was added. The mixture was irradiated under UV light and stirred for 70 min. After the reaction, the organic solvent was removed by rotary evaporation. The residue was dissolved in dichloromethane and extracted three times with a methanol-water mixture (methanol to water volume ratio of 1:0.9). After drying with anhydrous sodium sulfate and filtering, the solvent was removed by vacuum evaporation to obtain the modified chain extender. The co-chain extender was composed of BDO and the above modified chain extender in a mass ratio of 1:0.05.

[0031] S3. Preparation of TPU masterbatch: 100 parts of modified polyol, 15 parts of HDI, and 0.1 parts of organic bismuth catalyst were mixed and reacted at 82.5℃ for 5.5 h with stirring. Then, 6 parts of co-chain extender (5.72 parts of BDO and 0.28 parts of modified chain extender) were added, and the mixture was cured at 85℃ for 15 h to obtain solid TPU masterbatch.

[0032] S4. Preparation of TPU surface foam material: TPU masterbatch was placed in an autoclave and sealed. Supercritical CO2 was introduced, and the pressure was controlled at 18 MPa and the temperature at 75℃. This constant temperature and pressure was maintained for 67 minutes to allow the supercritical gas to fully permeate into the masterbatch, resulting in TPU masterbatch saturated with gas. The saturated TPU masterbatch was then quickly removed and placed in a constant temperature water bath at 100℃ for 1 minute to foam. Finally, the foamed particles were placed in a pressure-holding container, and CO2 was introduced to 1.5 MPa. The pressure was maintained for 16.5 hours to obtain the TPU surface foam material.

[0033] Example 3 S1. Preparation of modified polyols: 1.1 mol PCL and 1.1 mol adipic anhydride were added to a reaction vessel and reacted at 110 °C for 2 h to obtain a carboxyl-containing intermediate. The temperature was lowered to 90 °C, and 1.1 mol KH-560 and 0.5 wt% (by mass of KH-560) of an organic bismuth catalyst were added. The reaction was continued at 90 °C for 3 h to obtain a modified polyol.

[0034] S2. Grafting to obtain modified chain extenders: 2.5 mol MDAAC and 1 mol SH-PDMS were dissolved in dichloromethane, and DMPA (5 wt% of MDAAC) was added. The mixture was irradiated under UV light and stirred for 70 min. After the reaction, the organic solvent was removed by rotary evaporation. The residue was dissolved in dichloromethane and extracted three times with a methanol-water mixture (methanol to water volume ratio of 1:1.1). After drying with anhydrous sodium sulfate and filtering, the solvent was removed by vacuum evaporation to obtain the modified chain extender. The co-chain extender consisted of BDO and the modified chain extender in a mass ratio of 1:0.15.

[0035] S3. Preparation of TPU masterbatch: 100 parts of modified polyol, 35 parts of HDI, and 0.1 parts of organic bismuth catalyst were mixed and reacted at 82.5℃ for 5.5 h with stirring. Then, 12 parts of co-chain extender (10.5 parts of BDO and 1.5 parts of modified chain extender) were added, and the mixture was cured at 85℃ for 15 h to obtain solid TPU masterbatch.

[0036] S4. Preparation of TPU surface foam material: TPU masterbatch was placed in an autoclave and sealed. Supercritical CO2 was introduced, and the pressure was controlled at 22 MPa and the temperature at 75°C. This constant temperature and pressure was maintained for 67.5 minutes to allow the supercritical gas to fully permeate into the masterbatch, resulting in TPU masterbatch saturated with gas. The saturated TPU masterbatch was then quickly removed and placed in a constant temperature water bath at 100°C for 1 minute to foam. Finally, the foamed particles were placed in a pressure-holding container, and CO2 was introduced to 1.5 MPa. The pressure was maintained for 16.5 hours to obtain the TPU surface foam material.

[0037] Example 4 S1. Preparation of modified polyols: 1 mol of PCL and 1 mol of adipic anhydride were added to a reaction vessel and reacted at 100 °C for 1 h to obtain a carboxyl-containing intermediate. The temperature was then lowered to 80 °C, and 1 mol of KH-560 and 0.3 wt% of an organic bismuth catalyst were added. The reaction was continued at 80 °C for 2 h to obtain a modified polyol.

[0038] S2. Grafting to obtain modified chain extenders: 2.25 mol MDAAC and 1 mol SH-PDMS were dissolved in dichloromethane, and DMPA (3 wt% of MDAAC) was added. The mixture was irradiated under UV light and stirred for 60 min. After the reaction, the organic solvent was removed by rotary evaporation. The residue was dissolved in dichloromethane and extracted three times with a methanol-water mixture (methanol to water volume ratio of 1:1). After drying with anhydrous sodium sulfate and filtering, the solvent was removed by vacuum evaporation to obtain the modified chain extender. The co-chain extender consisted of BDO and the modified chain extender in a mass ratio of 1:0.1.

[0039] S3. Preparation of TPU masterbatch: 100 parts of modified polyol, 25 parts of HDI, and 0.1 parts of organic bismuth catalyst were mixed and stirred at 75°C for 3 hours. Then, 9 parts of co-chain extender (8.2 parts of BDO and 0.8 parts of modified chain extender) were added, and the mixture was cured at 80°C for 10 hours to obtain solid TPU masterbatch.

[0040] S4. Preparation of TPU surface foam material: TPU masterbatch was placed in an autoclave and sealed. Supercritical CO2 was introduced, and the pressure was controlled at 20 MPa and the temperature at 70°C. This constant temperature and pressure was maintained for 45 minutes to allow the supercritical gas to fully permeate into the masterbatch, resulting in TPU masterbatch saturated with gas. The saturated TPU masterbatch was then quickly removed and placed in a constant temperature water bath at 80°C for 0.1 minutes to foam. Finally, the foamed particles were placed in a pressure-holding container, and CO2 was introduced to 1.5 MPa. The pressure was maintained for 15 hours to obtain the TPU surface foam material.

[0041] Example 5 S1. Preparation of modified polyols: 1 mol of PCL and 1 mol of adipic anhydride were added to a reaction vessel and reacted at 120 °C for 3 h to obtain a carboxyl-containing intermediate. The temperature was lowered to 100 °C, and 1 mol of KH-560 and 0.3 wt% of an organic bismuth catalyst were added. The reaction was continued at 100 °C for 4 h to obtain a modified polyol.

[0042] S2. Grafting to obtain modified chain extenders: 2.25 mol MDAAC and 1 mol SH-PDMS were dissolved in dichloromethane, and DMPA (3 wt% of MDAAC) was added. The mixture was irradiated under UV light and stirred for 80 min. After the reaction, the organic solvent was removed by rotary evaporation. The residue was dissolved in dichloromethane and extracted three times with a methanol-water mixture (methanol to water volume ratio of 1:1). After drying with anhydrous sodium sulfate and filtering, the solvent was removed by vacuum evaporation to obtain the modified chain extender. The co-chain extender consisted of BDO and the modified chain extender in a mass ratio of 1:0.1.

[0043] S3. Preparation of TPU masterbatch: 100 parts of modified polyol, 25 parts of HDI, and 0.1 parts of organic bismuth catalyst were mixed and stirred at 90°C for 8 hours. Then, 9 parts of co-chain extender (8.2 parts of BDO and 0.8 parts of modified chain extender) were added, and the mixture was cured at 90°C for 20 hours to obtain solid TPU masterbatch.

[0044] S4. Preparation of TPU surface foam material: TPU masterbatch was placed in an autoclave and sealed. Supercritical CO2 was introduced, and the pressure was controlled at 20 MPa and the temperature at 80°C. This constant temperature and pressure was maintained for 90 minutes to allow the supercritical gas to fully permeate into the masterbatch, resulting in TPU masterbatch saturated with gas. The saturated TPU masterbatch was then quickly removed and placed in a constant temperature water bath at 120°C for 2 minutes to foam. Finally, the foamed particles were placed in a pressure-holding container, and CO2 was introduced to 1.5 MPa. The pressure was maintained for 18 hours to obtain the TPU surface foam material.

[0045] Comparative Example 1 The comparative example is prepared using the same process as Example 1 for the TPU surface foam material, except that KH-560 in step S1 is replaced with butyl glycidyl ether (BGE).

[0046] Comparative Example 2 The comparative example follows the same process as Example 1 in preparing the TPU surface foam material, except that in step S2, MDAAC is replaced with butyl methacrylate (BMA).

[0047] Comparative Example 3 The comparative example follows the same process as Example 1 in preparing the TPU surface foam material, except that SH-PDMS is not added in step S2.

[0048] Comparative Example 4 The comparative example is prepared using the same process as Example 1 for the TPU surface foam material, except that in step S2, SH-PDMS is added to the masterbatch for blending instead of being grafted with ultraviolet light.

[0049] Comparative Example 5 The comparative example follows the same process as Example 1 in preparing the TPU surface foam material, except that in step S3, the modified polyester polyol is replaced with a common polyester polyol of the same molecular weight.

[0050] Comparative Example 6 The comparative example is prepared using the same process as Example 1 for the TPU surface foam material, except that in step S3, the modified polyester polyol is replaced with a common polyester polyol of the same molecular weight, and an anti-hydrolysis agent is added.

[0051] Comparative Example 7 The comparative example is prepared using the same process as Example 1 for the TPU surface foam material, except that in step S3, the modified polyester polyol is replaced with a common polyester polyol of the same molecular weight, and only BDO is added as a chain extender.

[0052] The performance testing method is as follows: Hydrolysis resistance tests: The finished products of each embodiment were first placed in a 10% NaOH solution and soaked at 25°C for 72 hours. After removing the samples, their tensile strength and tear strength were tested according to GB / T 528-2009 and GB / T 529-2008, respectively. Three samples were tested for each group, and the average value was taken.

[0053] Antimicrobial performance testing: The anti-staphylococcal properties of the antimicrobial shoe materials in each example and comparative example were tested according to ISO 16187-2025 before washing, after washing, and after hydrolysis treatment. Ten antimicrobial shoe materials were randomly selected from each example and comparative example for antimicrobial testing, and the average results are recorded in Table 1 below. A 5% (w / w) concentration of Blue Moon detergent was prepared, and the washing cycle was 100 times.

[0054] Antifouling performance test: The water contact angle was measured using a JC2000D contact angle measuring instrument. The water used for the test was ultrapure water. Five points were tested for each sample, and the average value was taken.

[0055] Cell structure: Take cross-sections of foamed samples from the examples and comparative examples to observe cell diameter and uniformity; The test results are shown in the table below:

[0056] The test results in the table above show that the TPU surface foam material prepared by the present invention through Examples 1-3 has both excellent antibacterial and antifouling properties; at the same time, its mechanical properties are less affected by humid and high temperature environments, showing good comprehensive performance.

[0057] As shown in the table, the tensile and tear strengths of Examples 1-5 were significantly higher than those of Comparative Example 1. This is attributed to KH-560's covalent grafting of γ-glycidoxypropyltrimethoxysilane onto the PCL chain via a carboxyl-epoxy ring-opening reaction, which imparts a trimethoxysilane end group to the product, enhancing its hydrolysis resistance and thermal stability. In contrast, Comparative Example 1 used only BGE, with an inert butyl tail and no trimethoxysilane group. The resulting carboxylated PCL polyol was still a conventional organic polyol, its performance limited by the inherent flexibility and degradability of PCL, thus exhibiting poorer results.

[0058] The antibacterial test results show that the antibacterial rates of Examples 1-5 are significantly better than those of Comparative Example 2. The reason for this is that a quaternary ammonium salt cation was introduced into the modified chain extender used in this invention. This quaternary ammonium salt group (N... + The PDMS component adsorbs onto the negatively charged bacterial surface via electrostatic attraction, and its hydrophobic segments then insert into and disrupt the lipid bilayer of the cell membrane, causing membrane rupture and thus achieving contact sterilization. In contrast, Comparative Example 2 did not introduce quaternary ammonium salt groups and relied solely on the low surface energy of the PDMS component to achieve physical antifouling, lacking chemical sterilization capabilities. This comparison demonstrates that quaternary ammonium salt groups are an indispensable structural basis for constructing the antibacterial properties of the TPU surface layer described in this invention.

[0059] Furthermore, the data in the table also shows that the antifouling performance of Examples 1-5 is significantly better than that of Comparative Example 3. This is because the foamed material prepared in Comparative Example 3 does not contain PDMS, and therefore cannot form a stable low-surface-energy surface fixed by covalent bonds. Regarding antibacterial performance, the inhibition rate of Comparative Example 3 against Staphylococcus aureus decreased from 98.2% in Example 1 to 92%, presumably due to the lack of hydrophobic PDMS components, making it easier for bacteria to adhere.

[0060] By comparing the performance of Examples 1-5 with that of Comparative Example 4, it was found that the hydrolysis performance, antifouling performance, and hydrolysis resistance of PDMS introduced by direct grafting were superior to those of the masterbatch blending process. This is because SH-PDMS is difficult to achieve molecular-level uniform dispersion in the matrix during masterbatch blending, and is prone to agglomeration, thus affecting the uniformity and mechanical properties of the material.

[0061] Comparing the properties of Examples 1-5 with Comparative Example 5, it can be found that the antibacterial rate, water contact angle, and mechanical properties of the two groups of materials are at similar levels before hydrolysis treatment, indicating that there is no significant difference in their basic properties in the initial state. However, after accelerated hydrolysis aging under the same conditions, the properties of the two materials show a significant divergence. This difference stems from the introduction of an anti-hydrolysis structure (trimethoxysilane) in the polyols of Examples 1-5, which can effectively resist water molecule attack; while Comparative Example 5 lacks this structure, and after aging, the molecular chain breaks, the PDMS layer is damaged, and the quaternary ammonium salt groups are detached, resulting in a decline in antibacterial, antifouling, and mechanical properties.

[0062] Furthermore, comparing the properties of Examples 1-5 with those of Comparative Example 6, it was found that the antibacterial, antifouling, and mechanical properties of Comparative Example 6 were lower than those of Examples 1-5, but higher than those of Comparative Example 5. This indicates that although the effect of blending with anti-hydrolysis agents is not as significant as that of chemical grafting, it can still impart a certain degree of hydrolysis resistance to the material, which is superior to the system without any added anti-hydrolysis components.

[0063] Finally, comparing Examples 1-5 with Comparative Example 7 reveals that, under the same foaming process conditions, Examples 1-5, which use modified polyols and modified chain extenders, exhibit significantly higher tensile and tear strengths than Comparative Example 7, which uses unmodified components; simultaneously, their water contact angles are also much higher than those of Comparative Example 7. This result indicates that the introduction of silane and organosilicon segments effectively enhances the interaction forces between TPU molecular chains and reduces the surface energy of the material, thereby achieving a synergistic improvement in both mechanical and hydrophobic properties.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A TPU surface layer foam material, characterized in that, The product includes a modified polyol, and based on 100 parts of the modified polyol, it also includes the following components by weight: 15-35 parts diisocyanate derivative, 6-12 parts co-chain extender; The modified polyol is prepared by reacting polyester polyol, acid anhydride and monoepoxide compound; The diisocyanate derivatives include at least one of aromatic diisocyanates, aliphatic diisocyanates, or alicyclic diisocyanates.

2. The TPU surface foam material according to claim 1, characterized in that, The modified polyol is prepared by the following method: a polyester polyol is reacted with an acid anhydride to obtain a carboxyl-containing intermediate; after cooling, a monoepoxide compound is added to the carboxyl-containing intermediate, and a second reaction is carried out under the action of a catalyst to obtain the modified polyol.

3. The TPU surface foam material according to claim 2, characterized in that, The molar ratio between the polyester polyol, acid anhydride and monoepoxide is 1:0.9-1.1:0.9-1.1; the temperature of the first reaction is 100-120℃ and the reaction time is 1-3h; the temperature of the second reaction is 80-100℃ and the reaction time is 2-4h; the catalyst is an organic bismuth catalyst, and its amount is 0.1-0.5 wt% of the monoepoxide.

4. The TPU surface foam material according to claim 2, characterized in that, The polyester polyol includes one or more of polycaprolactone diol and branched aliphatic polyester polyol. The acid anhydride includes one or more of adipic anhydride, sebacic anhydride, lauric anhydride, and palmitic anhydride; The monoepoxy compound includes one or more of γ-glycidyl etherpropyltrimethoxysilane and γ-glycidyl etherpropylmethyldimethoxysilane.

5. The TPU surface foam material according to claim 4, characterized in that, Branched aliphatic polyester polyols are synthesized from one or two of BEPG and BEPD as monomers.

6. The TPU surface foam material according to claim 1, characterized in that, The co-chain extender comprises a combination of BDO and a modified chain extender, wherein the mass ratio of BDO to the modified chain extender is 1:0.05-0.

15. The modified chain extender is prepared by dissolving dihydroxyethylallyl quaternary ammonium salt and mercaptopropyl-terminated polydimethylsiloxane in an organic solvent, adding a photoinitiator, and then stirring under ultraviolet light. After the reaction is completed, the organic solvent is removed by rotary evaporation, the residue is dissolved in dichloromethane, and extracted with a methanol-water mixed solvent. Finally, the residue is dried, filtered, and the solvent is removed by vacuum evaporation to obtain the modified chain extender.

7. The TPU surface foam material according to claim 6, characterized in that, The molar ratio of the dihydroxyethylallyl quaternary ammonium salt to the mercaptopropyl-terminated polydimethylsiloxane is 2-2.5:1; the photoinitiator is DMPA, and its amount is 1-5 wt% of the dihydroxyethylallyl quaternary ammonium salt; the ultraviolet irradiation reaction time is 60-80 min; the organic solvent includes one or more of dichloromethane and toluene; the extraction is performed 3 times; and the volume ratio of methanol to water in the methanol-water mixed solvent is 1:0.9-1.

1.

8. A method for preparing a TPU surface layer foam material, characterized in that, Includes the following steps: S1. Preparation of TPU masterbatch: Modified polyol, diisocyanate and organometallic catalyst are mixed and stirred at 75-90℃ for 3-8h. Then, co-chain extender is added and cured at 80-90℃ for 10-20h to obtain solid TPU masterbatch. S2. High-pressure impregnation saturation: The TPU masterbatch is placed in a high-pressure autoclave and sealed. Supercritical gas is introduced and the pressure is controlled at 18-22MPa and the temperature at 70-80℃. The constant temperature and pressure are maintained for 45-90 minutes to allow the supercritical gas to fully penetrate into the masterbatch, thereby obtaining TPU masterbatch containing saturated gas. S3. Heating and foaming molding: Quickly remove the saturated TPU masterbatch and place it in a constant temperature heat medium of 80-120℃ for foaming for 0.1-2 minutes. Finally, place the foamed particles in a pressure-holding container, introduce CO2 to 1.5MPa, and hold the pressure for 15-18 hours to obtain the TPU surface foam material.

9. The method for preparing the TPU surface foam material according to claim 8, characterized in that, The organometallic catalyst in S1 includes one or more of organobismuth and organozinc catalysts; the supercritical gas in S2 includes one or more of carbon dioxide and nitrogen.

10. The application of a TPU surface foam material in the preparation of shoe materials, characterized in that, The shoe material includes the TPU surface foam material according to any one of claims 1-7 or the TPU surface foam material prepared by the preparation method according to any one of claims 8-9.

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