Food shoe silicon rubber antiskid material and its preparation method

Abstract

This invention discloses a silicone rubber anti-slip material for food footwear and its preparation method, belonging to the field of silicone rubber technology. The silicone rubber anti-slip material for food footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 15-25 parts of modified anti-slip filler, 8-12 parts of fumed silica, 3-5 parts of zinc acrylate, 1-2 parts of silicon carbide nanowires, 2-3 parts of hydrogen-containing silicone oil crosslinking agent, 0.5-1.0 parts of catalyst, and 0.3-0.8 parts of reaction inhibitor; the modified anti-slip filler is fluorosilane-modified chitosan-coated mesoporous silica vesicles. The material of this invention maintains high tensile strength, tear strength, and performance retention after aging while improving the interfacial friction coefficient.

Description

Technical Field

[0001] This invention belongs to the field of silicone rubber technology, specifically relating to a silicone rubber anti-slip material for food footwear and its preparation method. Background Technology

[0002] In food processing environments (such as meat processing, dairy production, and restaurant kitchens), floors are often wet due to cleaning operations or have residual animal and vegetable oils from raw material handling, creating complex, slippery interfaces of water, oil, or a mixture of both. The anti-slip performance of the protective footwear worn by workers directly affects production safety and work efficiency. Silicone rubber, with its non-toxic, odorless, high and low temperature resistance, hydrolysis resistance, and good chemical stability, is the ideal base material for food-grade protective footwear.

[0003] However, the densely distributed nonpolar methyl groups on the outer side of the silicone rubber molecular backbone result in low surface energy, exhibiting significant hydrophobic and oleophilic properties. When the sole comes into contact with a water-oil mixture, the interfacial liquid easily spreads and forms a continuous lubricating film on the contact surface, thereby blocking the actual contact between the material and the ground, leading to a significant decrease in friction and making it difficult to meet the anti-slip requirements under wet and slippery conditions in the food industry.

[0004] In existing technologies, surface roughness is often improved by directly filling the rubber matrix with hard inorganic particles. For example, Chinese patent application CN105255190A discloses a rubber anti-slip material comprising: zinc oxide, stearic acid, sulfur, coupling agent, carbon fiber, silica, colorant, silicone rubber, and anti-slip agent. This material achieves increased friction by adding components such as carbon fiber and silica to the silicone rubber. However, this conventional physical blending method can disrupt the integrity of the silicone rubber crosslinking network, easily leading to stress concentration and a significant decrease in tensile strength and tear resistance.

[0005] To address the issue of wet slip resistance, Chinese patent application CN120399307A discloses a method for preparing silicone rubber, comprising the following steps: S10, dispersing fumed silica in an acid solution to obtain a fumed silica solution, dispersing chitosan in a dilute acid solution to obtain a chitosan solution, then mixing the fumed silica solution and chitosan solution, and obtaining a coated product by stirring, centrifugation, washing, and drying; S20, mixing the coated product, magnesium hydroxide, raw rubber, crosslinking agent, vulcanizing agent, and catalyst, heating and kneading, and obtaining the initial silicone rubber after vacuuming.

[0006] This method employs chitosan-coated fillers and hydrophilic modification of the silicone rubber surface to improve the frictional properties of water-slippery interfaces. However, the above technical solution is mainly designed for single water film environments and is prone to failure due to oil film coverage in oil-slippery or water-oil mixed interfaces. At the same time, the secondary surface treatment layer in this technical solution is prone to peeling off after repeated friction, making it difficult to guarantee a long-term stable anti-slip effect.

[0007] Furthermore, traditional anti-slip silicone rubber materials are mostly produced through molding or cutting, which is insufficient to meet the demands of modern footwear industries for granular material supply. Therefore, developing a silicone rubber anti-slip material for food-grade footwear that can effectively disrupt fluid lubrication films in water, oil, and water-oil mixtures, while also maintaining mechanical strength and long-lasting resistance to high-temperature cleaning and aging in the food industry, along with its preparation method, is of great significance for solving the practical application problems of safety and protective footwear materials in the food industry. It is also suitable for extremely slippery environments with complex fluid lubrication films, such as petrochemical plants, machining workshops, and medical operating rooms, and is particularly suitable for special work shoes and protective boots. Summary of the Invention

[0008] To address the deficiencies in the aforementioned technical solutions, the present invention aims to provide a food-grade silicone rubber anti-slip material for footwear and its preparation method.

[0009] To achieve the above objectives, the present invention provides a food-grade silicone rubber anti-slip material for footwear, comprising, by weight, the following: 100 parts of vinyl silicone rubber raw rubber, 15-25 parts of modified anti-slip filler, 8-12 parts of fumed silica, 3-5 parts of zinc acrylate, 1-2 parts of silicon carbide nanowires, 2-3 parts of hydrogen-containing silicone oil crosslinking agent, 0.5-1.0 parts of catalyst, and 0.3-0.8 parts of reaction inhibitor.

[0010] The modified anti-slip filler is a fluorosilane-modified chitosan-coated mesoporous silica vesicle. The vinyl silicone rubber raw material is a methyl vinyl polysiloxane with a molecular weight of 600,000-800,000 and a vinyl content of 0.8%-1.2% by mass; The fumed silica is fumed silica produced by a hexamethyldisilazane surface hydrophobic treatment, with a specific surface area ≥200 m². 2 / g; The zinc acrylate is zinc acrylate with a purity of ≥99% and an average particle size of ≤5μm; The silicon carbide nanowires have an average diameter of 20-50 nm and an aspect ratio of 50-70. The mass fraction of active hydrogen in the hydrogen-containing silicone oil crosslinking agent is 0.8%-1.2%; The catalyst is a Pt-vinylsiloxane complex; The mass fraction of Pt atoms in the catalyst is 3000-5000 ppm; The reaction inhibitor is 1-ethynyl-1-cyclohexanol.

[0011] The preparation method of the modified anti-slip filler includes the following steps: Step 1: In a reactor equipped with an ultrasonic dispersing device and a mechanical stirrer, add 1%-2% glacial acetic acid aqueous solution and mesoporous silica vesicles, and ultrasonically disperse for 15 minutes; separately, disperse chitosan in 1%-2% glacial acetic acid aqueous solution to form a homogeneous solution; mix the two and mechanically stir at 50°C for 3 hours; then centrifuge at 8000 rpm, wash with deionized water until neutral, and vacuum dry at 60°C to obtain chitosan-coated vesicles; Step 2: Redisperse the chitosan-coated vesicles obtained in Step 1 in a mixed solvent of anhydrous ethanol and water, and adjust the pH of the system; under mechanical stirring, slowly add fluorosilane coupling agent dropwise, and after the addition is complete, continue to stir mechanically at room temperature for 4-6 hours. Step 3: After the reaction is complete, the product is filtered and washed three times with anhydrous ethanol to completely remove unreacted fluorosilane coupling agent. Finally, the product is placed in a vacuum oven and dried at 80°C for 4-6 hours. After grinding and sieving, a modified anti-slip filler in the form of a slightly yellow powder is obtained.

[0012] Furthermore, the mesoporous silica vesicles in step 1 have an average particle size of 30-50 nm, a vesicle wall thickness of 5-10 nm, and an internal cavity structure. Furthermore, in step 1, the mass ratio of mesoporous silica vesicles to chitosan is controlled at 4:1-6:1; Furthermore, the fluorosilane coupling agent in step 2 is heptadecafluorodecyltrimethoxysilane; Furthermore, in step 2, the mass of the added fluorosilane coupling agent is 4%-6% of the mass of the mesoporous silica vesicles.

[0013] A method for preparing a silicone rubber anti-slip material for food footwear includes the following steps: Step A: Mix the zinc acrylate and anhydrous ethanol in a mass ratio of 1:3, place them in a ball mill with zirconia balls as the grinding medium, and ball mill at 400 rpm for 2 hours; then vacuum dry at 60°C to remove residual anhydrous ethanol, and obtain a nanoscale zinc acrylate dispersion with an average particle size ≤20nm. Step B: Preheat the internal mixer to 45°C, add vinyl silicone rubber raw rubber and silicon carbide nanowires, and perform the first mixing for 5 minutes; raise the temperature to 85°C, add the modified anti-slip filler, fumed silica and nano-grade zinc acrylate prepared in step A in two batches, and perform the second mixing for 20 minutes; then turn on the cooling water to cool the material to below 40°C, add the hydrogen-containing silicone oil crosslinking agent and reaction inhibitor, and perform the third mixing for 8 minutes; discharge the rubber, and pass it through a two-roll mill to obtain the compounded rubber sheet; Step C: Crush the compounded rubber sheet obtained in Step B and feed it together with the platinum catalyst into a co-rotating twin-screw extruder; set the temperature of each zone of the extruder: Zone 1 80℃, Zone 2 90℃, Zones 3 to 5 95-100℃, and the die head 90℃; after the material is extruded through the die head, it is air-cooled and pelletized to prepare silicone rubber anti-slip granules.

[0014] The beneficial effects of this invention are: 1. This invention constructs a composite membrane-breaking system that combines hydrophilic adsorption, oleophobic repulsion, and capillary conduction by introducing fluorosilane-modified chitosan to coat mesoporous silica vesicles. This enables the material to effectively weaken the lubricating film in pure water, pure oil, and water-oil mixed interfaces, thereby significantly improving the anti-slip performance of food protective shoe soles under complex wet and slippery conditions. 2. This invention reduces stress concentration caused by rigid fillers by rationally controlling the synergistic ratio of modified anti-slip filler, fumed silica, zinc acrylate and silicon carbide nanowires, and by using mesoporous vesicle fillers to replace traditional solid hard particles. This allows the material to maintain high tensile strength, tear strength and performance retention after aging while improving the interfacial friction coefficient. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a product image of a food-grade silicone rubber anti-slip granule material for footwear prepared according to an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Furthermore, regarding numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0017] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0018] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0019] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0020] Example 1 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following raw materials: 100 parts of vinyl silicone rubber raw rubber, 15 parts of modified anti-slip filler, 8 parts of fumed silica, 3 parts of zinc acrylate, 1 part of silicon carbide nanowires, 2 parts of hydrogen-containing silicone oil crosslinking agent, 0.5 parts of platinum catalyst, and 0.3 parts of reaction inhibitor.

[0021] The modified anti-slip filler is a fluorosilane-modified chitosan-coated mesoporous silica vesicle. The vinyl silicone rubber raw material is a methyl vinyl polysiloxane with a molecular weight of 600,000 and a vinyl content of 0.8% by mass; The fumed silica is fumed silica produced by a hexamethyldisilazane surface hydrophobic treatment, with a specific surface area ≥200 m². 2 / g; The zinc acrylate has a purity of ≥99% and an average particle size of ≤5μm. The silicon carbide nanowires have an average diameter of 20-50 nm and an aspect ratio of 50. The mass fraction of active hydrogen in the hydrogen-containing silicone oil crosslinking agent is 0.8%; The platinum catalyst is a Pt-vinylsiloxane complex with a Pt atomic mass fraction of 3000. The reaction inhibitor is 1-ethynyl-1-cyclohexanol.

[0022] The preparation method of the modified anti-slip filler includes the following steps: Step 1: In a reactor equipped with an ultrasonic dispersion device and a mechanical stirrer, add 1% glacial acetic acid aqueous solution and mesoporous silica vesicles, and turn on ultrasonic dispersion for 15 minutes; separately, disperse chitosan in 1% glacial acetic acid aqueous solution to form a homogeneous solution; mix the two and mechanically stir at 50°C for 3 hours to allow chitosan to fully coat the vesicle surface through hydrogen bonding and electrostatic interaction; then centrifuge at 8000 rpm, wash with deionized water until neutral, and vacuum dry at 60°C to obtain chitosan-coated vesicles; Step 2: The chitosan-coated vesicles obtained in Step 1 are redispersed in a mixed solvent of anhydrous ethanol and water at a volume ratio of 9:1, and the pH of the system is adjusted to about 4.5. Under continuous sonication and stirring, fluorosilane coupling agent is slowly added dropwise, with low-power intermittent sonication (sonication for 5 minutes, stop for 10 minutes) to promote the dispersion of fluorosilane. After the addition is completed, the sonication is stopped, and the reaction is carried out under mechanical constant temperature stirring at room temperature for 4 hours to allow the fluorosilane to modify the surface of the chitosan coating. Step 3: After the reaction is complete, the product is filtered and washed three times with anhydrous ethanol to completely remove unreacted fluorosilane coupling agent. Finally, the product is placed in a vacuum oven and dried at 80°C for 4-6 hours. It is then ground through a 200-mesh sieve to obtain a slightly yellow powdery modified anti-slip filler.

[0023] Specifically, the mesoporous silica vesicles in step 1 have an average particle size of 30-50 nm, a vesicle wall thickness of 5-10 nm, and an internal cavity structure; the mesoporous silica vesicles are commercially available products purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Specifically, the mesoporous silica vesicles are commercially available products or prepared using existing methods; Specifically, in step 1, the mass ratio of mesoporous silica vesicles to chitosan is controlled at 5:1; Specifically, the fluorosilane coupling agent in step 2 is heptadecafluorodecyltrimethoxysilane; Specifically, in step 2, the added mass of the fluorosilane coupling agent is 4% of the mass of the mesoporous silica vesicles.

[0024] A method for preparing a silicone rubber anti-slip material for food footwear includes the following steps: Step A: Mix the zinc acrylate and anhydrous ethanol in a mass ratio of 1:3, place them in a ball mill with zirconia balls as the grinding medium, and ball mill at 400 rpm for 2 hours; then vacuum dry at 60°C to remove residual anhydrous ethanol, and obtain a nanoscale zinc acrylate dispersion with an average particle size ≤20nm. Step B: Preheat the internal mixer to 45°C, add vinyl silicone rubber raw rubber and silicon carbide nanowires, and perform the first mixing for 5 minutes; raise the temperature to 85°C, add the modified anti-slip filler, fumed silica and nano-grade zinc acrylate prepared in step A in two batches, and perform the second mixing for 20 minutes; then turn on the cooling water to cool the material to below 40°C, add the hydrogen-containing silicone oil crosslinking agent and reaction inhibitor, and perform the third mixing for 8 minutes; discharge the rubber, and pass it through a two-roll mill to obtain the compounded rubber sheet; Step C: The compounded rubber sheet obtained in Step B is crushed and fed into a co-rotating twin-screw extruder along with the platinum catalyst. The temperatures of each zone of the extruder are set as follows: Zone 1 80℃, Zone 2 90℃, Zones 3 to 5 95-100℃, and the die head 90℃. Under strong shear, the zinc ions of zinc acrylate and carboxylate groups form a dynamic and reversible ionic bond network, giving the rubber compound excellent melt strength. At the same time, the reaction inhibitor locks the activity of the platinum catalyst, preventing covalent cross-linking. After the material is extruded through the die head, it is air-cooled and pelletized to obtain non-sticky silicone rubber anti-slip granules.

[0025] Example 2 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 25 parts of modified anti-slip filler, 12 parts of fumed silica, 5 parts of zinc acrylate, 2 parts of silicon carbide nanowires, 3 parts of hydrogen-containing silicone oil crosslinking agent, 1.0 part of platinum catalyst, and 0.8 parts of reaction inhibitor.

[0026] In the preparation process of the modified anti-slip filler: the mass ratio of mesoporous silica vesicles to chitosan in step 1 is controlled at 4:1; The fluorosilane coupling agent in step 2 is heptadecafluorodecyltrimethoxysilane, and its added mass is 6% of the mass of the mesoporous silica vesicles. The other preparation methods of the modified anti-slip filler in Example 2 and the preparation methods of the food shoe silicone rubber anti-slip material are the same as those in Example 1.

[0027] Example 3 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 20 parts of modified anti-slip filler, 10 parts of fumed silica, 4 parts of zinc acrylate, 1.5 parts of silicon carbide nanowires, 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of platinum catalyst, and 0.5 parts of reaction inhibitor.

[0028] In the preparation process of the modified anti-slip filler: the mass ratio of mesoporous silica vesicles to chitosan in step 1 is controlled at 5.5:1; The fluorosilane coupling agent in step 2 is heptadecafluorodecyltrimethoxysilane, and its added mass is 5% of the mass of the mesoporous silica vesicles. The other preparation methods of the modified anti-slip filler in Example 3 and the preparation methods of the food shoe silicone rubber anti-slip material are the same as those in Example 1.

[0029] Example 4 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 18 parts of modified anti-slip filler, 9 parts of fumed silica, 3.5 parts of zinc acrylate, 1.2 parts of silicon carbide nanowires, 2.2 parts of hydrogen-containing silicone oil crosslinking agent, 0.6 parts of platinum catalyst, and 0.4 parts of reaction inhibitor.

[0030] In the preparation process of the modified anti-slip filler: the mass ratio of mesoporous silica vesicles to chitosan in step 1 is controlled at 6:1; The fluorosilane coupling agent in step 2 is heptadecafluorodecyltrimethoxysilane, and its added mass is 4.5% of the mass of the mesoporous silica vesicles; The other preparation methods of the modified anti-slip filler in Example 4 and the preparation methods of the food shoe silicone rubber anti-slip material are the same as those in Example 1.

[0031] Example 5 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 22 parts of modified anti-slip filler, 11 parts of fumed silica, 4.5 parts of zinc acrylate, 1.8 parts of silicon carbide nanowires, 2.8 parts of hydrogen-containing silicone oil crosslinking agent, 0.9 parts of platinum catalyst, and 0.7 parts of reaction inhibitor.

[0032] In the preparation process of the modified anti-slip filler: the mass ratio of mesoporous silica vesicles to chitosan in step 1 is controlled at 4.5:1; The fluorosilane coupling agent in step 2 is heptadecafluorodecyltrimethoxysilane, and its added mass is 5.5% of the mass of the mesoporous silica vesicles; The other preparation methods of the modified anti-slip filler in Example 5 and the preparation methods of the food shoe silicone rubber anti-slip material are the same as those in Example 1.

[0033] Comparative Example 1 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 5 parts of modified anti-slip filler, 10 parts of fumed silica, 4 parts of zinc acrylate, 1.5 parts of silicon carbide nanowires, 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of platinum catalyst, and 0.5 parts of reaction inhibitor.

[0034] The difference between this comparative example and Example 3 is that the amount of modified anti-slip filler added is reduced to 5 parts.

[0035] Apart from the above, the preparation methods of the modified anti-slip filler and the preparation methods of the food footwear silicone anti-slip material in this comparative example are the same as those in Example 3.

[0036] Comparative Example 2 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 40 parts of modified anti-slip filler, 10 parts of fumed silica, 4 parts of zinc acrylate, 1.5 parts of silicon carbide nanowires, 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of platinum catalyst, and 0.5 parts of reaction inhibitor.

[0037] The difference between this comparative example and Example 3 is that the amount of modified anti-slip filler added is increased to 40 parts.

[0038] Apart from the above, the preparation methods of the modified anti-slip filler and the preparation methods of the food footwear silicone anti-slip material in this comparative example are the same as those in Example 3.

[0039] Comparative Example 3 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 20 parts of modified anti-slip filler, 10 parts of fumed silica, 1.5 parts of silicon carbide nanowires, 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of platinum catalyst, and 0.5 parts of reaction inhibitor.

[0040] The difference between this comparative example and Example 3 is that zinc acrylate was not added, and pretreatment step A was omitted.

[0041] Apart from the above, the preparation methods of the modified anti-slip filler and the preparation methods of the food footwear silicone anti-slip material in this comparative example are the same as those in Example 3.

[0042] Comparative Example 4 The difference between this comparative example and Example 3 is that in the preparation process of the modified anti-slip filler, the mass ratio of mesoporous silica vesicles to chitosan in step 1 is controlled at 10:1.

[0043] Apart from the above, the raw material components and their amounts, as well as the preparation method of the food-grade silicone rubber anti-slip material for footwear, are the same as in Example 3.

[0044] Comparative Example 5 The difference between this comparative example and Example 3 is that in the preparation process of the modified anti-slip filler, the mass ratio of mesoporous silica vesicles to chitosan in step 1 is controlled at 2:1.

[0045] Apart from the above, the raw material components and their amounts, as well as the preparation method of the food-grade silicone rubber anti-slip material for footwear, are the same as in Example 3.

[0046] Comparative Example 6 The difference between this comparative example and Example 3 is that, in the preparation process of the modified anti-slip filler, the amount of heptadecafluorodecyltrimethoxysilane added in step 2 is 1% of the mass of the mesoporous silica vesicles.

[0047] Apart from the above, the raw material components and their amounts, as well as the preparation method of the food-grade silicone rubber anti-slip material for footwear, are the same as in Example 3.

[0048] Comparative Example 7 The difference between this comparative example and Example 3 is that, in the preparation process of the modified anti-slip filler, the amount of heptadecafluorodecyltrimethoxysilane added in step 2 is 12% of the mass of the mesoporous silica vesicles.

[0049] Apart from the above, the raw material components and their amounts, as well as the preparation method of the food-grade silicone rubber anti-slip material for footwear, are the same as in Example 3.

[0050] Comparative Example 8 The difference between this comparative example and Example 3 is that, in the preparation process of the modified anti-slip filler, heptadecafluorodecyltrimethoxysilane is replaced with an equal mass of trifluoropropyltrimethoxysilane.

[0051] Apart from the above, the raw material components and their amounts, as well as the preparation method of the food-grade silicone rubber anti-slip material for footwear, are the same as in Example 3.

[0052] Comparative Example 9 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 30 parts of fumed silica, 4 parts of zinc acrylate, 1.5 parts of silicon carbide nanowires, 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of platinum catalyst, and 0.5 parts of reaction inhibitor.

[0053] The difference between this comparative example and Example 3 is that an equal amount of unmodified solid fumed silica is used to replace the modified anti-slip filler and fumed silica in Example 3.

[0054] Except for the preparation method of the food-grade silicone rubber anti-slip material for footwear in this comparative example, it is the same as that in Example 3.

[0055] Comparative Example 10 The difference between this comparative example and Example 3 is that in step B, the vinyl silicone rubber raw rubber, silicon carbide nanowires, modified anti-slip filler, fumed silica, nano-grade zinc acrylate obtained in step A, hydrogen-containing silicone oil crosslinking agent and reaction inhibitor are all added at once to a mixer preheated to 85°C and mixed for 25 minutes.

[0056] Apart from the above, the other raw material components and their amounts, the preparation method of the modified anti-slip filler, and steps A and C in this comparative example are all the same as in Example 3.

[0057] Comparative Example 11 A food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 15 parts of fumed silica, 30 parts of silicon carbide micro powder (particle size 5μm), 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of platinum catalyst, and 0.5 parts of reaction inhibitor.

[0058] The difference between this comparative example and Example 3 is that zinc acrylate is not added; and silicon carbide micro powder is used to replace the modified anti-slip filler and silicon carbide nanowires.

[0059] Except for the preparation method of the food-grade silicone rubber anti-slip material for footwear in this comparative example, it is the same as that in Example 3.

[0060] Test case Preparation of test samples: The silicone rubber anti-slip material for food footwear prepared by the method of Example 1-5 and Comparative Examples 1-11 was injected into a food footwear mold and molded and cured at 160-175℃ and 10MPa pressure for 5-10 minutes. At this temperature, the reaction inhibitors volatilized and became ineffective, the platinum catalyst was activated and catalyzed the irreversible addition reaction between Si-H and vinyl groups to form a stable covalent crosslinking network. At the same time, the ionic bonds were reorganized. Then the mold was opened and cooled, and after appropriate cutting, the test samples of Example 1-5 and Comparative Examples 1-10 were prepared.

[0061] Friction and anti-slip performance test: Referring to GB / T 3903.6-2024 "Test Methods for Anti-slip Performance of Whole Footwear", a dynamic friction coefficient tester was used to test the dynamic friction coefficient of the food shoe samples prepared in the examples and comparative examples; the test interface was set to a stainless steel plate. The test media were set as follows: dry interface, pure water interface, pure oil interface (soybean oil), and water-oil mixture interface (emulsion of water and soybean oil mixed in a 1:1 volume ratio) to evaluate the grip and anti-slip ability of each sample under complex fluid lubrication film; the test results are shown in Table 1: Table 1 Mechanical property testing: Referring to GB / T 528 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" and GB / T 529 "Determination of tear strength of vulcanized rubber or thermoplastic rubber", standard dumbbell-shaped specimens and right-angled specimens with a thickness of 2 mm were prepared. Using an electronic universal tensile testing machine, the tensile strength, elongation at break and tear strength of the examples and comparative examples were determined at a tensile speed of 500 mm / min.

[0062] Simulated high-temperature cleaning aging test in the food industry: A water-oil mixture containing 5% weakly alkaline cleaning agent (soybean oil:water = 1:4) was prepared and heated to 85°C. Standard dumbbell-shaped samples were completely immersed in the simulated high-temperature cleaning solution from a food factory for 168 hours. The samples were then removed, rinsed with deionized water, and dried. After 24 hours, a tensile strength test was performed again, and the tensile strength retention rate after aging was calculated to evaluate the material's durability under extreme cleaning conditions.

[0063] The test results are shown in Table 2: Table 2 Performance test data analysis: As can be seen from the data in Tables 1 and 2, the food shoe silicone rubber anti-slip materials prepared in Examples 1-5 of this invention all exhibit good comprehensive performance, among which Example 3 has the best balance.

[0064] In Example 3, the coefficients of dynamic friction at dry, pure water, pure oil, and water-oil mixed interfaces were 0.67, 0.58, 0.52, and 0.56, respectively; the tensile strength, elongation at break, and tear strength were 8.54 MPa, 668%, and 35.7 kN / m, respectively; and the tensile strength retention rate after aging was 90.6%. The test results in Tables 1 and 2 demonstrate that this invention does not simply improve a single property, but rather achieves a good overall balance between anti-slip properties, mechanical strength, and resistance to cleaning and aging at complex wet and slippery interfaces.

[0065] In Comparative Example 1, after the modified anti-slip filler was reduced to 5 parts, the dynamic friction coefficients of the pure water, pure oil, and water-oil mixture interfaces decreased to 0.31, 0.28, and 0.19, respectively. The possible reason is that when there are insufficient anti-slip active sites, the material is difficult to effectively disrupt the continuous lubricating film. In Comparative Example 2, after the modified anti-slip filler was increased to 40 parts, although the anti-slip component was strengthened, its tensile strength and elongation at break decreased to 2.24 MPa and 167%, respectively. The possible reason is that excessive filler will disrupt the continuity of the matrix, thereby causing significant mechanical degradation.

[0066] In Comparative Example 3, after omitting zinc acrylate, the tear strength and tensile strength retention rates after aging decreased to 15.8 kN / m and 51.3%, respectively. The possible reason for this is that the dynamic ionic bond network formed by zinc ions and carboxylate groups, in which zinc acrylate participates, plays an important role in the material's toughness and aging resistance.

[0067] Comparative Examples 4 and 5 correspond to insufficient chitosan and excessive chitosan, respectively. The dynamic friction coefficients of both examples at the pure water interface and the water-oil mixed interface are lower than those of Example 3, indicating that the chitosan layer should not be too thin, nor should it be too thick to weaken the flow-guiding effect of the mesoporous structure. Comparative Examples 6 and 7 correspond to low and high amounts of fluorosilane, respectively. The dynamic friction coefficients of the pure oil interface or pure water interface both decreased, indicating that the oleophobic component also needs to be maintained in an appropriate proportion. In Comparative Example 8, replacing heptadecafluorodecyltrimethoxysilane with trifluoropropyltrimethoxysilane reduced the dynamic friction coefficient of the pure oil interface to 0.28. In Comparative Example 9, after replacing the modified vesicle filler with unmodified solid fumed silica, the dynamic friction coefficient of the water-oil interface was further reduced to 0.11.

[0068] Comparative Example 11, as a reference to the prior art, showed that after replacing the modified vesicles and nanowires of the present invention with micron-sized hard silicon carbide powder instead of zinc acrylate, although the dry dynamic friction coefficient was acceptable, the dynamic friction coefficient at the water-oil mixing interface plummeted to 0.15, making it impossible to effectively break the film. At the same time, the addition of a large number of hard particles severely damaged the continuous cross-linked network, reducing the tensile strength to 4.50 MPa, the tear strength to 17.2 kN / m, and the aging retention rate to only 60.5%. This fully demonstrates that the physical friction-enhancing technology in the prior art cannot cope with complex emulsions and significantly sacrifices mechanical and aging properties.

[0069] The above results collectively demonstrate that this invention does not simply rely on roughness to increase friction, but rather on the combined action of chitosan, fluorosilane, and mesoporous vesicle structures to establish a stable film-breaking anti-slip effect in complex media. The possible reason for this lies in the technical solution of this application: utilizing the strong hydrogen bond adsorption of water molecules by the dense amino and hydroxyl groups in the outer chitosan structure, instantly piercing and disintegrating the continuous water film; combined with the extremely low surface energy characteristics of the locally grafted fluorosilane, it strongly repels grease and breaks it into isolated oil droplets, blocking the formation of a continuous oil film; simultaneously, with the microscopic capillary negative pressure suction effect within the mesoporous vesicle cavity, it rapidly adsorbs and guides the free fluid at the interface into the pores. This mechanism enables the material to quickly displace lubricating fluid and establish true dry contact between the silicone rubber sole and the ground in complex wet and slippery interfaces of water, oil, and water-oil mixtures in the food industry, effectively solving the problem of hydrodynamic lubrication slippage caused by the low surface energy of traditional silicone rubber, and giving the sole excellent anti-slip performance. After changing the feeding and mixing order in step B of Comparative Example 10, the tensile strength and the retention rate of tensile strength after aging decreased to 5.76 MPa and 71.5%, respectively. This indicates that segmented mixing during the preparation process is beneficial for the uniform dispersion of fillers, thereby achieving stable control of the crosslinking process and the formation of a uniform network structure in the end.

[0070] Furthermore, this invention ingeniously combines thermodynamic and kinetic time difference control of volatile alkynyl alcohol reaction inhibitors. In the twin-screw low-temperature extrusion stage, the inhibitor completely locks the activity of the platinum catalyst to avoid irreversible covalent dead bonding. At the same time, the dynamic ionic bond network formed by zinc ions and carboxylate groups in zinc acrylate endows the rubber compound with excellent thermoplasticity and melt strength, achieving apparent non-stickiness and thus enabling efficient air-cooled pelletizing. In the subsequent high-temperature molding stage, the inhibitor volatilizes upon heating, instantly activating the platinum catalyst and catalyzing the completion of the hydrosilylation reaction. Combined with the rapid recombination of ionic bonds, the material possesses both the excellent processing continuity of thermoplastic elastomers and the high strength of thermosetting rubbers, making it extremely suitable for large-scale industrial production of food footwear.

[0071] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silicone rubber anti-slip material for food-grade shoes, characterized in that, The composition by weight is as follows: 100 parts of vinyl silicone rubber raw rubber, 15-25 parts of modified anti-slip filler, 8-12 parts of fumed silica, 3-5 parts of zinc acrylate, 1-2 parts of silicon carbide nanowires, 2-3 parts of hydrogen-containing silicone oil crosslinking agent, 0.5-1.0 parts of catalyst, and 0.3-0.8 parts of reaction inhibitor. The modified anti-slip filler is a fluorosilane-modified chitosan-coated mesoporous silica vesicle.

2. The silicone rubber anti-slip material for food-grade shoes according to claim 1, characterized in that, The food-grade silicone rubber anti-slip material for footwear, by weight, comprises the following: 100 parts of vinyl silicone rubber raw rubber, 20 parts of modified anti-slip filler, 10 parts of fumed silica, 4 parts of zinc acrylate, 1.5 parts of silicon carbide nanowires, 2.5 parts of hydrogen-containing silicone oil crosslinking agent, 0.8 parts of catalyst, and 0.5 parts of reaction inhibitor.

3. The silicone rubber anti-slip material for food-grade shoes according to claim 1, characterized in that, The fumed silica is fumed silica produced by a hexamethyldisilazane surface hydrophobic treatment, with a specific surface area ≥200 m². 2 / g.

4. The silicone rubber anti-slip material for food-grade shoes according to claim 1, characterized in that, The catalyst is a Pt-vinylsiloxane complex.

5. The silicone rubber anti-slip material for food-grade shoes according to claim 1, characterized in that, The reaction inhibitor is 1-ethynyl-1-cyclohexanol.

6. The silicone rubber anti-slip material for food-grade shoes according to claim 1, characterized in that, The modified anti-slip filler was prepared by the following method: Step 1: In a reactor equipped with an ultrasonic dispersing device and a mechanical stirrer, add glacial acetic acid aqueous solution and mesoporous silica vesicles, and ultrasonically disperse for 15 minutes; separately, disperse chitosan in glacial acetic acid aqueous solution to form a homogeneous solution; mix the two and mechanically stir at 50°C for 3 hours; then centrifuge at 8000 rpm, wash with deionized water until neutral, and vacuum dry at 60°C to obtain chitosan-coated vesicles; Step 2: Redisperse the chitosan-coated vesicles obtained in Step 1 in a mixed solvent of anhydrous ethanol and water, and adjust the pH of the system; add fluorosilane coupling agent dropwise, and stir the reaction for 4-6 hours after the addition is complete. Step 3: After the reaction is complete, the product is filtered and washed three times with anhydrous ethanol. Finally, the product is placed in a vacuum oven and dried at 80°C for 4-6 hours. After grinding and sieving, a modified anti-slip filler in the form of a slightly yellow powder is obtained.

7. The silicone rubber anti-slip material for food shoes according to claim 6, characterized in that, In step 1, the mass ratio of mesoporous silica vesicles to chitosan is controlled at 4:1-6:

1.

8. The silicone rubber anti-slip material for food shoes according to claim 6, characterized in that, In step 2, the mass of the added fluorosilane coupling agent is 4%-6% of the mass of the mesoporous silica vesicles.

9. A method for preparing a silicone rubber anti-slip material for food footwear according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: Step A: Mix the zinc acrylate and anhydrous ethanol in a mass ratio of 1:3, place them in a ball mill with zirconia balls as the grinding medium, and ball mill for 2 hours; then vacuum dry at 60°C to remove residual anhydrous ethanol to obtain zinc acrylate dispersion; Step B: Preheat the internal mixer to 45°C, add vinyl silicone rubber raw rubber and silicon carbide nanowires, and perform the first mixing for 5 minutes; raise the temperature to 85°C, add the modified anti-slip filler, fumed silica and nano-grade zinc acrylate prepared in step A in two batches, and perform the second mixing for 20 minutes; then turn on the cooling water to cool the material to below 40°C, add the hydrogen-containing silicone oil crosslinking agent and reaction inhibitor, and perform the third mixing for 8 minutes; discharge the rubber, and pass it through a two-roll mill to obtain the compounded rubber sheet; Step C: Crush the compounded rubber sheet obtained in Step B and feed it together with the platinum catalyst into a co-rotating twin-screw extruder; set the temperature of each zone of the extruder: Zone 1 80℃, Zone 2 90℃, Zones 3 to 5 95-100℃, and the die head 90℃; after the material is extruded through the die head, it is air-cooled and pelletized to prepare silicone rubber anti-slip granules.

10. The preparation method according to claim 9, characterized in that, The zinc acrylate is zinc acrylate with a purity of ≥99% and an average particle size of ≤5μm.

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