Stain-resistant and high-strength polyurethane elastomer composition as well as preparation method and application thereof

Abstract

The invention provides a stain-resistant and high-strength polyurethane elastomer composition as well as a preparation method and application thereof, and belongs to the technical field of chemical materials. The polyurethane elastomer is prepared from the following raw materials in parts by weight: 90-110 parts of polyurethane elastomer, 20-50 parts of composite modified white carbon black and 0-15 parts of functional additive, the composite modified white carbon black is prepared by the following steps: dispersing white carbon black in an organic solvent to obtain a white carbon black suspension; adding an amino silane coupling agent into the white carbon black suspension, and reacting to obtain amino silane modified white carbon black; and then adding long-chain alkyl silane into the amino silane modified white carbon black, and reacting to obtain the composite modified white carbon black. The composite modified white carbon black is obtained through a step-by-step modification method, and then the composite modified white carbon black is used as a filler to be mixed with the polyurethane elastomer, so that the mechanical property and the stain resistance of the polyurethane elastomer are improved, the stain-resistant and high-strength polyurethane elastomer is obtained, and the stain-resistant and high-strength polyurethane elastomer has a wider application prospect in the field of intelligent wearing.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials technology, specifically relating to a stain-resistant and high-strength polyurethane elastomer composition, its preparation method, and its uses. Background Technology

[0002] Polyurethane (PU) is a class of polymers whose molecular chains contain urethane groups (-NHCOO-). In addition to urethane groups, its molecular structure sometimes also contains ester, ether, and urea groups. It offers a high degree of freedom in structural design and a wide range of adjustable properties. It is widely used in various forms such as foams, synthetic leather, fibers, elastomers, coatings, and adhesives in many fields including aerospace, transportation, medical, construction, and textiles, and has become an indispensable synthetic material in daily life.

[0003] Polyurethane elastomers can be classified into three main categories according to their product processing methods: cast polyurethane elastomers (CPU), compounded polyurethane elastomers (MPU), and thermoplastic polyurethane elastomers (TPU). MPU has promising application prospects because its molding process is similar to that of fluororubber and silicone rubber used in existing smart wearables. As a rubber material, MPU requires the addition of various fillers for reinforcement to achieve good mechanical properties. However, in practical applications, it has been found that while adding fillers can effectively reinforce its mechanical properties, the fillers themselves have poor stain resistance and insufficient bonding with the rubber, leading to pores in the microscopic surface structure. This makes it prone to penetration and contamination, significantly negatively impacting its stain resistance.

[0004] Therefore, how to improve the stain resistance of MPU by modifying fillers while ensuring mechanical properties is an urgent problem to be solved in its application in the field of smart wearables. Summary of the Invention

[0005] The purpose of this invention is to provide a stain-resistant and high-strength polyurethane elastomer composition, its preparation method, and its uses.

[0006] This invention provides a composite modified silica, which is prepared by the following method: (1) Add silica to an organic solvent and disperse to obtain a silica suspension; (2) Add an aminosilane coupling agent to the silica suspension and react to obtain aminosilane modified silica; (3) Add long-chain alkyl silane to aminosilane modified silica and react to obtain composite modified silica.

[0007] Furthermore, the mass ratio of the aminosilane coupling agent to the long-chain alkylsilane is 1:0.2~1.5, and the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 5%~20% of the mass of the silica. The reaction temperatures in steps (2) and (3) are independently 60℃~90℃, and the reaction times are independently 1~4h; The general formula of the long-chain alkyl silane is R-Si-(OR')3, where R is a straight-chain or branched alkyl group of C8 to C22, and R' is an alkyl group of C1 to C4; the aminosilane coupling agent includes monoaminosilane coupling agent, diaminosilane coupling agent, amino-epoxy bifunctional silane or amino-mercaptosilane.

[0008] Furthermore, the mass ratio of the aminosilane coupling agent to the long-chain alkylsilane is 1:0.5~1, and the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 12% of the mass of the silica. The long-chain alkylsilanes include at least one of n-octyltrimethoxysilane, n-octyltriethoxysilane, n-dodecyltrimethoxysilane, n-dodecyltriethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, and n-docosadecyltrimethoxysilane. The monoaminosilane coupling agent comprises at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, and 3-aminoisobutyltrimethoxysilane; the diaminosilane coupling agent comprises at least one of N-aminoethyl-γ-aminopropyltrimethoxysilane, N-aminoethyl-γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and bis-(γ-trimethoxysilylpropyl)amine; the amino-epoxy bifunctional... The silane includes at least one of N-(2-aminoethyl)-3-(2,3-epoxypropoxy)propyltrimethoxysilane, N-(2-aminoethyl)-3-(2,3-epoxypropoxy)propyltriethoxysilane, bis(3-aminopropyl)tetramethyldisiloxane, and 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane; the amino-mercaptosilane includes at least one of 3-aminopropyl-3-mercaptopropyltrimethoxysilane, N-(2-aminoethyl)-3-mercaptopropyltrimethoxysilane, and 3-aminopropyl-3-mercaptopropylmethyldimethoxysilane. The organic solvents include at least one of toluene, xylene, ethylbenzene, methanol, ethanol, isopropanol, ethyl acetate, acetone, diethyl ether, and n-hexane.

[0009] This invention also provides a method for preparing composite modified silica, comprising the following steps: (1) Add silica to an organic solvent and disperse to obtain a silica suspension; (2) Add an aminosilane coupling agent to the silica suspension and react to obtain aminosilane modified silica; (3) Add long-chain alkyl silane to aminosilane modified silica and react to obtain composite modified silica.

[0010] The present invention also provides the use of composite modified silica as a rubber filler to improve stain resistance and / or mechanical properties.

[0011] The present invention also provides a polyurethane elastomer composition, which is prepared from raw materials comprising the following parts by weight: 90-110 parts of polyurethane elastomer, 20-50 parts of the composite modified silica as described in any one of claims 1-3, and 0-15 parts of functional additives; wherein the functional additives include at least one of crosslinking agent, vulcanizing agent, antioxidant, plasticizer, and flame retardant.

[0012] Furthermore, the polyurethane elastomer is prepared by the following method: mixing a polymeric diol with a polyisocyanate and a chain extender; then adding a catalyst and mixing, followed by aging, to obtain the polyurethane elastomer.

[0013] Further, the molar ratio of the polymeric diol, polyisocyanate, and chain extender is 0.2~1:0.5~1.5:0.2~1; the mass of the catalyst is 0.05~0.15% of the sum of the masses of the polymeric diol, polyisocyanate, and chain extender; the mixing temperature is 90~120℃, and the time is 3~10 min; the aging temperature is 60~80℃, and the time is 4~6 h; the polymeric diol includes at least one selected from polycarbonate diol, polyadipate diol, polytetrahydrofuran diol, and polyethylene glycol. The polyisocyanate includes at least one selected from 4,4'-dicyclohexylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; the chain extender includes at least one selected from 1,4-butanediol, ethylene glycol, 1,6-hexanediol, ethylenediamine, and 1,4-butanediamine; the catalyst includes at least one selected from dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dichloride, triethylenediamine, and N-methylmorpholine.

[0014] Further, the molar ratio of the polymer diol, polyisocyanate, and chain extender is 0.5:1:0.5; the mass of the catalyst is 0.1% of the sum of the masses of the polymer diol, polyisocyanate, and chain extender; the mixing temperature is 100°C and the time is 5 min; the aging temperature is 70°C and the time is 5 h.

[0015] Furthermore, the polyurethane elastomer composition is made from raw materials comprising the following parts by weight: 90-110 parts of polyurethane elastomer, 10-50 parts of composite modified silica, 1-5 parts of crosslinking agent, and 1-5 parts of vulcanizing agent. The crosslinking agent includes trifunctional crosslinking agents, amine crosslinking agents, or isocyanate crosslinking agents; The vulcanizing agent includes sulfur-based vulcanizing agents, peroxide vulcanizing agents, metal oxide vulcanizing agents, or oxime vulcanizing agents.

[0016] Furthermore, the polyurethane elastomer composition is made from raw materials comprising the following parts by weight: 100 parts polyurethane elastomer, 20 parts composite modified silica, 1.5 parts crosslinking agent, and 2 parts vulcanizing agent. The trifunctional crosslinking agent includes at least one of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and triglycidyl isocyanurate; the amine crosslinking agent includes at least one of hexamethylenediamine carbamate, hexamethylenediamine formaldehyde, and N,N'-dicinnamylene-1,6-hexamethylenediamine; the isocyanate crosslinking agent includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate; the sulfur-based vulcanizing agent includes sulfur... The following are included: at least one of sulfonium, tetramethylthiuram disulfide, dibenzothiazole disulfide, bis(pentamylthiuram) disulfide, and morpholine disulfide; peroxide vulcanizing agents include at least one of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, bis(tert-butylperoxy)isopropylbenzene, benzoyl peroxide, and tert-butyl peroxide; metal oxide vulcanizing agents include at least one of zinc oxide, magnesium oxide, lead oxide, calcium oxide, and aluminum oxide; oxime vulcanizing agents include at least one of p-benzoquinone dioxime, dibenzoylp-quinone dioxime, methyltributanone oxime silane, methyltributanone oxime silane, and tetrabutanone oxime silane.

[0017] The present invention also provides a method for preparing a polyurethane elastomer composition, specifically: fully plasticizing the polyurethane elastomer, then adding other raw materials and mixing them evenly, adjusting the roller gap, thinning, rolling, and extruding into sheets to obtain the final product.

[0018] The present invention also provides the use of polyurethane elastomer compositions in the field of smart wearables.

[0019] This invention first modifies silica with aminosilane, then further modifies silica with long-chain alkylsilane, obtaining composite modified silica through a stepwise modification method. This composite modified silica is then used as a filler and compounded with polyurethane elastomer, thereby improving the mechanical properties and stain resistance of the polyurethane elastomer. The aminosilane and long-chain alkylsilane exhibit a synergistic effect. Specifically, in the synergistic modification of silica by the aminosilane coupling agent and the long-chain alkylsilane coupling agent, the terminal primary amino group of the aminosilane can form extremely strong hydrogen bonds, and even covalent bonds, with the urethane, urea, and isocyanate groups in the polyurethane, greatly improving the interfacial adhesion between silica and polyurethane and enhancing its reinforcing effect. Meanwhile, the long alkyl chains of the long-chain alkylsilane, through entropy repulsion and low surface energy, can construct a robust hydrophobic and oleophobic layer after being added to the polyurethane, significantly improving the stain resistance of the polyurethane elastomer.

[0020] Experiments have shown that the polyurethane watch strap prepared by the method of the present invention has significantly improved mechanical properties and stain resistance. In particular, the polyurethane elastomer prepared in Example 2 has increased tensile strength by 6.1%, elongation at break by 9.0%, elongation at a given point by 13.8%, and tensile strength by 13.2%. This demonstrates that the method of the present invention can obtain a stain-resistant and high-strength polyurethane elastomer, which has a broader application prospect in the field of smart wearables.

[0021] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0022] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0023] Figure 1 The images, from left to right, show polyurethane watch straps of Examples 1-4 and Comparative Examples 1-4 after being marked with a marker (A) and after being wiped with alcohol (B). Detailed Implementation

[0024] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0025] In the specific embodiment, the polyurethane elastomer is a self-made product, prepared by the following method: 1000g (0.5mol) of polycarbonate diol (average molecular weight 2000) was added to a three-necked flask and mixed. After removing water at 110℃ under vacuum for 2 hours, nitrogen gas was introduced. Then, 262g (1mol) of 4,4'-dicyclohexylmethane diisocyanate and 45g (0.5mol) of 1,4-butanediol were added at 100℃ and mixed for 5 minutes. Then, 0.1% of the mass of dibutyltin dilaurate catalyst (the sum of the masses of polycarbonate diol, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-butanediol) was added and mixed for 5 minutes. The mixture was then poured into a tray and placed in a 70℃ oven for 5 hours to cure, and the polyurethane elastomer was obtained.

[0026] Example 1: Preparation of polyurethane elastomer composition 1.1 Preparation of Composite Modified Silica The aminosilane is 8g of γ-aminopropyltriethoxysilane (KH-550), and the long-chain alkylsilane is 4g of n-hexadecyltriethoxysilane; the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 12% of the mass of silica, and the mass ratio of aminosilane to long-chain alkylsilane is 1:0.5; the specific steps are as follows: (1) Take 100g of fumed silica (fumed silica produced by fumed silica production, with a specific surface area of ​​200m²) 2 / g) was vacuum dried at 110℃ for 6 hours to completely remove moisture; then it was put into a 2000ml three-necked flask equipped with a reflux condenser, a constant pressure dropping funnel and a mechanical stirrer, and 1200ml of anhydrous toluene was added. Under nitrogen protection, it was stirred and dispersed at 75℃ for 1 hour to form a uniform suspension, thus obtaining a silica suspension. (2) First step modification (grafting aminosilane): 8g KH-550 was diluted with 50ml of anhydrous toluene and slowly added dropwise to the suspension. The dropping speed was controlled to ensure that the dropping was completed within 30 minutes. Then, the reaction was carried out under nitrogen protection at 75℃ and refluxed for 3 hours to obtain amino-modified silica reaction solution. (3) Second step modification (grafting long-chain alkylsilane): Under nitrogen protection at 75°C, 4g of n-hexadecyltriethoxysilane was diluted with 50ml of anhydrous toluene and then slowly added dropwise to amino-modified silica reaction solution. After the addition was complete, the reaction was continued to be refluxed at 75°C for 2 hours. (4) After the reaction is complete, the solid product is collected by natural cooling to room temperature, filtered, washed three times with anhydrous toluene to remove unreacted substances, and finally, the filter cake is vacuum dried at 80°C for 10 hours to obtain composite modified silica.

[0027] 1.2 Preparation of Polyurethane Watch Straps (1) By weight, 100 parts of polyurethane elastomer are added to a two-roll mill and plasticized at room temperature. Then, 20 parts of composite modified silica, 1.5 parts of triallyl isocyanurate and 2 parts of bis(2,5)5 are added and mixed evenly. The roll gap is adjusted to less than 1 mm to wrap the rolls, and the rolls are thinly wrapped in a triangular shape and rolled up. Finally, the roll gap is adjusted to 2.2 mm to produce the sheet and the compound is obtained. (2) Place the compound into the mold and vulcanize for 5 minutes under a pressure of 16 MPa and a temperature of 160 °C to obtain a polyurethane watch strap.

[0028] Example 2: Preparation of polyurethane elastomer composition Referring to Example 1, the only difference lies in the preparation of the composite modified silica in 1.1: 6g of aminosilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, and 6g of long-chain alkylsilane, octadecyltrimethoxysilane; the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 12% of the mass of silica, and the mass ratio of aminosilane to long-chain alkylsilane is 1:1.

[0029] Example 3: Preparation of polyurethane elastomer composition Referring to Example 1, the only difference is in the preparation of the composite modified silica in 1.1: 10g of aminosilane N-(aminoethyl)-γ-aminopropyltrimethoxysilane and 10g of long-chain alkylsilane octadecyltrimethoxysilane; the total mass of aminosilane coupling agent and long-chain alkylsilane is 20% of the mass of silica, and the mass ratio of aminosilane to long-chain alkylsilane is 1:1.

[0030] Example 4: Preparation of polyurethane elastomer composition Referring to Example 1, the only difference lies in the preparation of the composite modified silica in 1.1: 6g of aminosilane, N-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 9g of long-chain alkylsilane, octadecyltrimethoxysilane; the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 15% of the mass of silica, and the mass ratio of aminosilane to long-chain alkylsilane is 1:1.5.

[0031] Comparative Example 1: Preparation of Polyurethane Elastomer Composition Referring to Example 1, the only difference is that in 1.1 the composite modified silica was not modified, and in 1.2 the polyurethane watchband was prepared by directly using the composite modified silica instead of silica obtained by vacuum drying at 110°C for 6 hours without any chemical modification.

[0032] Comparative Example 2: Preparation of Polyurethane Elastomer Composition Referring to Example 1, the only difference is in the preparation of the composite modified silica in 1.1: only steps (1), (2), and (4) are performed; 12g of KH-550 is used in step (2); the total reaction time for steps (1) and (2) is 4 hours; (only aminosilane is grafted, and long-chain alkyl is not grafted).

[0033] Comparative Example 3: Preparation of Polyurethane Elastomer Composition Referring to Example 1, the only difference is in the preparation of the composite modified silica in 1.1: only steps (1), (3), and (4) are performed; 12g of n-hexadecyltriethoxysilane is used in step (3); the total reaction time for steps (1) and (3) is 4 hours; (only long-chain alkyl groups are grafted, and aminosilanes are not grafted).

[0034] Comparative Example 4: Preparation of Polyurethane Elastomer Composition Referring to Example 1, the only difference is in the preparation of 1.1 composite modified silica: aminosilane and long-chain alkylsilane are mixed to modify silica in one step: specifically, 8g KH-550 and 4g n-hexadecyltriethoxysilane are mixed simultaneously in 1200ml anhydrous toluene, and then added dropwise to the silica suspension. After the addition is complete, the mixture is refluxed at 75°C for 4 hours.

[0035] Experimental Examples and Performance Testing of Polyurethane Elastomer Compositions 1. Experimental subjects Polyurethane watch straps prepared in Examples 1-4 and Comparative Examples 1-4.

[0036] 2. Experimental Methods (1) Mechanical property test: Hardness test is conducted according to national standard GB / T531.1-2008, and the hardness is measured using a Shore A hardness tester; tensile strength, elongation at break and 100% elongation are tested according to national standard GB / T 528-2009; the strap tension is tested by a tensile tester, and the strap is stretched continuously until the punch cracks or the strap breaks, and the maximum tensile value is obtained. The test speed is 30mm / min.

[0037] (2) Stain resistance test: After writing with a marker, let it stand for 10 minutes, then wipe it off with alcohol and record the wiping results.

[0038] 3. Experimental Results As shown in Tables 1 and 2, compared with the unmodified Comparative Example 1, the elongation at break and tensile strength of the watch straps in Examples 1-4 were significantly improved. Specifically, the tensile strength, elongation at break, elongation at a given point, and tensile strength of the watch straps in Examples 1-2 were all significantly improved. This indicates that the polyurethane watch straps prepared by first modifying the silica with aminosilane and then modifying it with long-chain alkylsilane have better mechanical properties. In particular, when the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 12% of the silica mass, and the mass ratio of aminosilane to long-chain alkylsilane is 1:0.5-1, the resulting watch straps exhibit significantly improved mechanical properties, with tensile strength increased by 2.0%-6.1%, elongation at break increased by 4.0%-9.0%, elongation at a given point increased by 6.9%-13.8%, and tensile strength increased by 7.4%-13.2%, without significantly affecting the hardness of the watch strap. Simultaneously, the stain resistance of Examples 1-4 was significantly improved.

[0039] For the one-step modification of Comparative Example 4, its stain resistance was improved compared to Comparative Example 1, but it was significantly worse than Examples 1-4. At the same time, its mechanical properties were not significantly improved. Compared to Comparative Example 1, only the elongation at break was improved, while the tensile strength, elongation at a given point, and tensile force were significantly reduced. This indicates that the one-step modification not only cannot effectively improve the performance of polyurethane elastomer, but is also detrimental to its mechanical properties.

[0040] Regarding the single modification of Comparative Examples 2 and 3, Comparative Example 2 is a single aminosilane modification, which significantly improves the mechanical properties compared to Comparative Example 1, but significantly reduces the stain resistance compared to Examples 1-4; Comparative Example 3 is a single long-chain alkylsilane modification, which does not significantly improve the mechanical properties. Compared to Comparative Example 1, only the elongation at break is improved, while the tensile strength, elongation at a given point, and tensile force are all significantly reduced, and the stain resistance is significantly reduced compared to Examples 1-4. This shows that using a single silane modification cannot achieve a comprehensive improvement in stain resistance and reinforcement performance, and cannot enable polyurethane elastomers to possess both excellent stain resistance and mechanical properties.

[0041] Meanwhile, modification with a single long-chain alkyl silane is not conducive to improving the mechanical properties and stain resistance of polyurethane watch straps, and modification with a single amino silane is not conducive to improving the stain resistance of polyurethane watch straps. However, through a two-step modification with amino silane, the mechanical properties and stain resistance of polyurethane watch straps are significantly improved simultaneously. This indicates that the amino silane and long-chain alkyl silane in this invention have a synergistic effect.

[0042] Table 1. Mechanical properties of polyurethane watch straps prepared in Examples 1-4 and Comparative Examples 1-4 Table 2 shows the stain resistance of the polyurethane watch straps prepared in Examples 1-4 and Comparative Examples 1-4. Note: √ for complete erasure, ○ for most of the erasure, ▲ for a small portion of the erasure, and × for no erasure.

[0043] In summary, this invention first modifies silica with aminosilane, then adds long-chain alkylsilane for further modification, obtaining composite modified silica through a stepwise modification method. This composite modified silica is then blended with polyurethane elastomer, achieving a significant and simultaneous improvement in the mechanical properties and stain resistance of the polyurethane elastomer. Furthermore, the aminosilane and long-chain alkylsilane exhibit a synergistic effect. Example 2 demonstrates the best performance, with the total mass of the aminosilane coupling agent and long-chain alkylsilane being 12% of the silica mass, and the mass ratio of aminosilane to long-chain alkylsilane being 1:1. The resulting watchband exhibits significantly improved mechanical properties and stain resistance, with tensile strength increased by 6.1%, elongation at break by 9.0%, elongation at a given point by 13.8%, and tensile strength by 13.2%.

Claims

1. A composite modified silica, characterized in that, It is prepared by the following method: (1) Add silica to an organic solvent and disperse to obtain a silica suspension; (2) Add an aminosilane coupling agent to the silica suspension and react to obtain aminosilane modified silica; (3) Add long-chain alkyl silane to aminosilane modified silica and react to obtain composite modified silica.

2. The composite modified silica according to claim 1, characterized in that: The mass ratio of the aminosilane coupling agent to the long-chain alkylsilane is 1:0.2~1.5, and the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 5%~20% of the mass of the silica. The reaction temperatures in steps (2) and (3) are independently 60℃~90℃, and the reaction times are independently 1~4h; The general formula of the long-chain alkyl silane is R-Si-(OR')3, where R is a straight-chain or branched alkyl group of C8 to C22, and R' is an alkyl group of C1 to C4; the aminosilane coupling agent includes monoaminosilane coupling agent, diaminosilane coupling agent, amino-epoxy bifunctional silane or amino-mercaptosilane.

3. The composite modified silica according to claim 2, characterized in that: The mass ratio of the aminosilane coupling agent to the long-chain alkylsilane is 1:0.5~1, and the total mass of the aminosilane coupling agent and the long-chain alkylsilane is 12% of the mass of the silica. The long-chain alkylsilanes include at least one of n-octyltrimethoxysilane, n-octyltriethoxysilane, n-dodecyltrimethoxysilane, n-dodecyltriethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, and n-docosadecyltrimethoxysilane. The monoaminosilane coupling agent comprises at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, and 3-aminoisobutyltrimethoxysilane; the diaminosilane coupling agent comprises at least one of N-aminoethyl-γ-aminopropyltrimethoxysilane, N-aminoethyl-γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and bis-(γ-trimethoxysilylpropyl)amine; the amino-epoxy bifunctional... The silane includes at least one of N-(2-aminoethyl)-3-(2,3-epoxypropoxy)propyltrimethoxysilane, N-(2-aminoethyl)-3-(2,3-epoxypropoxy)propyltriethoxysilane, bis(3-aminopropyl)tetramethyldisiloxane, and 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane; the amino-mercaptosilane includes at least one of 3-aminopropyl-3-mercaptopropyltrimethoxysilane, N-(2-aminoethyl)-3-mercaptopropyltrimethoxysilane, and 3-aminopropyl-3-mercaptopropylmethyldimethoxysilane. The organic solvent includes at least one of toluene, xylene, ethylbenzene, methanol, ethanol, isopropanol, ethyl acetate, acetone, diethyl ether, and n-hexane.

4. The method for preparing the composite modified silica according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Add silica to an organic solvent and disperse to obtain a silica suspension; (2) Add an aminosilane coupling agent to the silica suspension and react to obtain aminosilane modified silica; (3) Add long-chain alkyl silane to aminosilane modified silica and react to obtain composite modified silica.

5. The use of the composite modified silica according to any one of claims 1 to 3 as a rubber filler to improve stain resistance and / or mechanical properties.

6. A polyurethane elastomer composition, characterized in that: It is made from raw materials comprising the following parts by weight: 90-110 parts of polyurethane elastomer, 20-50 parts of the composite modified silica as described in any one of claims 1-3, and 0-15 parts of functional additives; wherein the functional additives include at least one of crosslinking agent, vulcanizing agent, antioxidant, plasticizer, and flame retardant.

7. The polyurethane elastomer composition according to claim 6, characterized in that: It is made from the following raw materials in parts by weight: 90-110 parts of polyurethane elastomer, 10-50 parts of composite modified silica, 1-5 parts of crosslinking agent, and 1-5 parts of vulcanizing agent. The crosslinking agent includes trifunctional crosslinking agents, amine crosslinking agents, or isocyanate crosslinking agents; The vulcanizing agent includes sulfur-based vulcanizing agents, peroxide vulcanizing agents, metal oxide vulcanizing agents, or oxime vulcanizing agents.

8. The polyurethane elastomer composition according to claim 7, characterized in that: It is made from the following raw materials in parts by weight: 100 parts polyurethane elastomer, 20 parts composite modified silica, 1.5 parts crosslinking agent, and 2 parts vulcanizing agent. The trifunctional crosslinking agent includes at least one of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and triglycidyl isocyanurate; the amine crosslinking agent includes at least one of hexamethylenediamine carbamate, hexamethylenediamine formaldehyde, and N,N'-dicinnamylene-1,6-hexamethylenediamine; the isocyanate crosslinking agent includes at least one of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate; the sulfur-based vulcanizing agent includes sulfur... The following are included: at least one of sulfonium, tetramethylthiuram disulfide, dibenzothiazole disulfide, bis(pentamylthiuram) disulfide, and morpholine disulfide; peroxide vulcanizing agents include at least one of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, bis(tert-butylperoxy)isopropylbenzene, benzoyl peroxide, and tert-butyl peroxide; metal oxide vulcanizing agents include at least one of zinc oxide, magnesium oxide, lead oxide, calcium oxide, and aluminum oxide; oxime vulcanizing agents include at least one of p-benzoquinone dioxime, dibenzoylp-quinone dioxime, methyltributanone oxime silane, methyltributanone oxime silane, and tetrabutanone oxime silane.

9. A method for preparing the polyurethane elastomer composition according to any one of claims 6 to 8, characterized in that, The polyurethane elastomer is fully plasticized, then other raw materials are added and mixed evenly. The roller gap is adjusted, the mixture is passed through a thin tube, rolled, and then sheeted out to obtain the final product.

10. Use of the polyurethane elastomer composition according to any one of claims 6 to 8 in the field of smart wearables.

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