Glass surface wet anti-slip bionic friction pad and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials and preparation thereof, and discloses a wet anti-slip bionic friction pad on a glass surface, which is inspired by a micro-nano structure of toe pads of organisms such as tree frogs and long-horned grasshoppers with wet friction increasing characteristics, and a bulge array is added on the surface of a high-friction material, so that the friction coefficient of the friction pad is increased; the microstructure arrays can discharge a water film on the surface of the friction pad under the capillary action in a wet environment, and the effective contact area between solids is increased, so that the friction pad and a friction surface are always kept in a dry friction state, and stable friction force is ensured. The friction pad comprises a connecting layer, a supporting layer and a tail end protruding straight column array, a tail end contact layer is in a hexagonal straight column shape, the diameter of an inscribed circle of a hexagonal micro-column structure ranges from 5 micrometers to 5000 micrometers, column bodies are densely arranged in a hexagonal mode, the height of the column bodies ranges from 10 micrometers to 1500 micrometers, the tail ends of the column bodies are planes, the interval between every two column bodies ranges from 2 micrometers to 600 micrometers, and tight drainage grooves are formed.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials and preparation thereof, in particular to a bionic friction pad for wet anti-skidding of glass surface and a preparation method thereof. Background Art

[0002] In nature, there are many examples of organisms with excellent tribological properties, and tree frogs are one of them. As excellent climbers in wet environments, the foot structure of tree frogs is particularly unique, showing a microscopic morphology composed of hexagonal nanopillars with concave tips. This structure gives them stable and reusable wet adhesion capabilities. Professor Chen Huawei of Beijing University of Aeronautics and Astronautics found that in a wet environment, the self-splitting effect of the liquid makes it evenly distributed on the hexagonal micropillars, while the self-absorption effect of the cavity edge forms a liquid film with nanometer thickness, increasing the possibility of forming a strong capillary liquid bridge, resulting in stronger boundary friction in the absence of external pressure. Subsequently, through the study of the interfacial liquid film movement and prism deformation, it was further discovered that nanofiber prisms have a special interfacial stress transfer effect in wet friction. This mechanism enhances the stability of the nano-liquid film at the prism interface, confirming the practical application potential of bionic high-strength wet friction surfaces in the field of wet anti-skid on solid interfaces, and also prompting friction materials with micro-nanoscale prism array structures to gain widespread attention in wet anti-skid engineering applications.

[0003] Chinese patent publication number CN114909386A discloses "a bionic adhesion friction microstructure and a bionic adhesion friction surface, which consists of a micro suction cup and a micro channel plane structure, wherein the adsorption surface of the micro suction cup is provided with an adsorption cavity, and one side of the adsorption cavity is provided with a plurality of micro channels arranged in the same direction. The invention relies on the viscosity of the fluid in the micro channel to achieve adhesion without energy consumption, can achieve the effect of high friction and high adhesion in a water environment, and can achieve rapid desorption, demonstrating the advantage of the design of micro channels in maintaining high friction in a wet environment"; CN10 2900945A discloses "a cross-scale friction-enhancing rubber plate imitating the foot pad of a tree frog and a preparation method thereof. A bionic adhesive plate with a millimeter-level pit structure on a centimeter-level protrusion structure is prepared by secondary vulcanization embossing, wherein the millimeter-level pit structure is formed by arranging silica particles between a template and a sample formed by a single vulcanization, and then secondary vulcanization embossing. The friction force of the bionic friction-enhancing plate prepared by this method has a good friction-enhancing effect. However, this structure is difficult to meet the demand for high friction under wet conditions, and secondary molding restricts large-scale development to a certain extent."

[0004] In a humid or rainy environment, when the glass surface contacts ordinary materials, the roughness of the contact surface may reduce the contact area, so that tiny water droplets act as a lubricating layer to transform the contact state from solid-solid contact to solid-liquid contact, thereby reducing the friction coefficient during contact. This causes climbing mechanisms, wall-climbing robots, window-cleaning robots and other equipment to easily slip when walking on glass materials or performing glass cleaning work, and they cannot be stably adsorbed on the glass surface, significantly increasing safety hazards. Therefore, a bionic friction pad with wet anti-skid properties on the glass surface and a preparation method thereof are proposed to solve the above-mentioned problems. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the shortcomings of the prior art, the present invention provides a bionic friction pad for wet anti-skid glass surface and a preparation method thereof, which can exhibit higher tangential friction in a wet environment and can be used repeatedly, and solves the problem that the contact surface between ordinary materials and glass is prone to slippage and has poor stability.

[0007] (II) Technical solution

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a bionic friction pad for wet anti-skid glass surface, inspired by the micro-nano structure of the toe pads of tree frogs and katydids, which have wet friction-increasing properties, adds a protrusion array on the surface of the high-friction material, and these microstructure arrays can use capillary action to discharge the water film on the surface of the friction pad in a wet environment, increase the effective contact area between solids, thereby ensuring that the friction pad and the friction surface always maintain a dry friction state, and ensure stable friction. The friction pad includes a connecting layer, a supporting layer, and an array of end protrusion straight columns, and the end contact layer is in the shape of a hexagonal straight column.

[0009] Preferably, the inscribed circle diameter of the hexagonal microcolumn structure is 5 microns to 5000 microns, the columns are arranged in hexagonal close-packed pattern, the column height is 10 microns to 1500 microns, the column ends are flat, and each column is spaced 2 microns to 600 microns apart, forming a tight drainage groove.

[0010] Preferably, the support layer and the end raised straight column array are both made of elastic materials, which are any one or a combination of natural rubber, artificial rubber, polyurethane, polyimide, polyolefin, polylactic acid, polycaprolactone, hydrogel, aerogel, and oil gel; the device connection layer material is any one or a combination of rubber, resin, metal, and ceramic.

[0011] Preferably, the array of end raised straight columns is the portion that is in direct contact with the object being acted upon.

[0012] Preferably, the support layer and the end raised straight column array are integrally formed.

[0013] Preferably, the preparation method of the bionic friction pad for wet anti-skid glass surface includes method one, method two and method three, wherein method one includes: step one, using photolithography technology to accurately transfer the preset hexagonal microstructure array pattern to the photoresist layer evenly spin-coated on the surface of the glass substrate, and then using magnetron sputtering technology to preliminarily deposit a nickel plating layer on the surface of the material, and then immerse the sample in an electroplating solution, and further implement a nickel electroplating process to construct a high-precision metal mold; step two, completely mix the basic components of liquid silicone and the curing agent in a certain weight ratio, and use a vacuum pump to degas under reduced pressure. Then, use spin coating to evenly coat the silicone prepolymer on the surface of the metal mold to obtain a uniform silicone film; step three, lightly place the connecting layer coated with the silicone prepolymer on the surface of the metal mold coated with the silicone prepolymer, and apply about 0.2N / cm 2 The normal pressure ensures that the two surfaces are completely fitted together and increases the bonding force between the connecting layer and the supporting layer. After vacuuming, the material is placed in an oven for curing. After demoulding, a bionic friction pad with an array of protruding straight columns at the end is obtained;

[0014] Preferably, the second method comprises: step 1, placing a metal mold of a preset shape in a metal cavity of corresponding thickness and configuration, and heating it; step 2, evenly laying a rubber raw material on the preheated metal mold, and then performing a hot pressing vulcanization process for about 5 minutes to form a rubber sheet with a fine structure; step 3, using an adhesive to evenly and firmly adhere the prepared rubber sheet to the surface of the connecting layer;

[0015] Preferably, the method three comprises: step one, pre-treating the surface of the connecting layer component to remove impurities such as oil, dust, etc., and pre-burying it in the mold cavity; step two, placing the precision metal mold at the bottom of the mold cavity, and evenly laying the rubber raw material between the connecting layer component and the metal mold; step three, curing the rubber material by heating and pressurizing to form a rubber coating layer with a fine structure on the end face, and the rubber coating layer is firmly bonded to the connecting layer component.

[0016] (III) Beneficial effects

[0017] Compared with the prior art, the present invention provides a method for preparing a bionic friction pad for wet anti-skid glass surface, which has the following beneficial effects:

[0018] 1. A method for preparing a bionic friction pad with wet anti-skid properties on a glass surface, using photolithography technology to transfer a hexagonal microstructure to a photoresist layer on a glass substrate, magnetron sputtering an initial nickel layer, and then electroplating nickel to make a high-precision metal mold. The first method of the preparation method is suitable for molding polymer prepolymers with low viscosity, and the preparation process has little effect on mold wear and plastic deformation, which is conducive to the low-cost promotion and application of the manufacturing process. The second preparation technology uses a rubber vulcanization embossing process. This method has a fast processing speed, and the prepared bionic friction pad has more excellent wear resistance and aging resistance, and can operate stably under complex environments such as high and low temperatures and radiation. The third preparation method uses a rubber encapsulation process, which can complete the integration of multiple components at one time and shorten the production cycle. The rubber coating layer is tightly integrated with the connector, eliminating the bonding process between the bionic friction pad and the surface of the carrier or connector, greatly improving the connection strength and stability between the bionic friction pad and the carrier or connector, thereby giving the bionic friction pad assembly or device the dual advantages of high connection strength and high durability in the engineering application process, showing broad market application potential.

[0019] 2. The preparation method of the bionic friction pad with wet anti-skid properties on the glass surface is inspired by the micro-nano structure of the toe pads of tree frogs and katydids, which are organisms with wet friction-increasing properties. The end straight columns are hexagonal in shape, and there are tiny gaps between the straight columns. Under wet conditions, the V-shaped tiny gaps can form a liquid film of a certain thickness by capillary force, that is, the self-adsorption effect of nanopits. The self-adsorption effect can discharge tiny water droplets between the contact surfaces, so that the bionic friction pad can directly contact the surface it acts on, increase the effective contact area, or form a strong capillary liquid bridge effect, thereby ensuring that the friction pad and the friction surface always maintain a dry friction state, reducing the possibility of slippage between the bionic friction pad and the surface it acts on. This allows the material to exhibit excellent anti-skid and friction-increasing properties. The end straight columns described in the present invention are hexagonally closely packed. This structure provides the longest drainage grooves, the greatest lateral stability and isotropy, and ensures the stability of the entire contact area in complex environments.

[0020] 3. The method for preparing a bionic friction pad for wet anti-skid glass surface provides a bionic friction pad for wet anti-skid glass surface, which significantly reduces the risk of sliding of low-roughness surfaces such as glass in a wet and slippery state, and can be widely used in climbing mechanisms, wall-climbing robots, window-cleaning robots, multi-dimensional cleaning robots and other equipment fields, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure proposed by the present invention;

[0022] Figure 2This is a schematic diagram of the structural parameters of the bionic friction pad for wet anti-skid glass surface proposed by the present invention, wherein the structural parameters include the diameter D1 of the inscribed circle of the pillars on one side of the bionic friction pad, the array spacing S1, and the pillar height h1;

[0023] Figure 3 This is a flow chart of the method for preparing the bionic friction pad for wet anti-skid glass surface proposed by the present invention;

[0024] Figure 4 A schematic diagram of the microstructure proposed by the present invention;

[0025] Figure 5 The friction test performance effect in a wet environment proposed by the present invention;

[0026] Figure 6 This is the friction test performance effect of the flat sample proposed in the present invention under different wet environments.

[0027] In the figure: 1. connection layer; 2. support layer; 3. array of raised straight columns at the end. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1

[0030] like Figure 1 As shown, the present embodiment 1 provides a bionic friction pad for wet anti-skid glass surface, comprising a connection layer 1, a support layer 2, and an array of end protruding straight columns 3. The columns of the end protruding straight columns array are arranged in a hexagonal close-packed pattern, and the cross section is a hexagon. Figure 2 As shown, the diameter D1 of the inscribed circle is 5-5000 microns, the columns are arranged in a hexagonal close-packed manner, the interval S1 between each column is 2 microns-600 microns, and the column height h1 is 10 microns-1500 microns.

[0031] Embodiment 2

[0032] like Figure 3 - Figure 4 As shown, the preparation method of a bionic friction pad for wet anti-skid glass surface provided in the second embodiment is as follows:

[0033] Method 1:

[0034] Step 1: Use photolithography to replicate the pattern of the hexagonal microstructure array onto a photoresist spin-coated on a glass substrate, then use magnetron sputtering technology to preliminarily deposit a layer of nickel plating on the surface of the material, then immerse the sample in an electroplating solution and further implement a nickel electroplating process to construct a high-precision metal mold.

[0035] Step 2: Mix the basic components of liquid silicone and the curing agent in a certain weight ratio, and use a vacuum pump to degas under reduced pressure. Then use the spin coating method to evenly coat the silicone prepolymer on the surface of the metal mold to obtain a uniform silicone film.

[0036] Step 3: Place the connecting layer coated with silicone prepolymer on the surface of the metal mold coated with silicone prepolymer and apply about 0.2N / cm 2 The normal pressure ensures that the two surfaces are completely fitted together and increases the bonding force between the connecting layer and the supporting layer. After vacuuming, the material is placed in an oven. During curing, the temperature and time are set according to the properties of the polymer material. After demoulding, a bionic friction pad with an array of protruding straight columns at the end is obtained.

[0037] Method 2:

[0038] Step 1: Place a metal mold of a preset shape in a metal cavity of corresponding thickness and configuration, and heat it.

[0039] Step 2: Evenly spread the rubber raw material on the preheated metal mold, and then perform a hot pressing vulcanization process, with the pressing temperature at 110°C to 120°C, the pressure at 500KPa to 550KPa, and the holding time at about 5 minutes to form a rubber sheet with a fine structure.

[0040] Step 3: Use an adhesive to evenly and firmly adhere the rubber sheet prepared above to the surface of the connecting layer.

[0041] Method 3:

[0042] Step 1: pre-treat the surface of the connection layer component to remove impurities such as oil, dust, etc., and embed the connection layer component in the cavity of the mold.

[0043] Step 2: Place the precisely machined metal mold securely at the bottom of the mold cavity, and then evenly lay the rubber material between the connecting layer assembly and the metal mold.

[0044] Step three, curing the rubber material by heating and pressurizing to form a rubber coating layer with a fine structure on the end surface, and the rubber coating layer is firmly combined with the connecting layer component.

[0045] Embodiment 3

[0046] like Figure 5 - Figure 6As shown, this embodiment provides a bionic friction pad for wet anti-skid glass surface and a preparation method thereof, and a friction performance testing device is used to test the friction performance of the material. The material of the tested sample is fluororubber, and the sample size is 1 cm×1 cm.

[0047] Figure 5 The friction test performance of the microstructured sample in a wet environment is described. The inscribed circle diameter of the hexagonal microcolumn structure is 0.035mm, the columns are arranged in a hexagonal close-packed pattern, each column is 0.004mm apart, and the column height is 0.012mm. During the test, the preload and pulling speed are the same. From the test results, it can be seen that in a wet environment, the friction performance of the microstructured sample is about 9 times that of the flat sample.

[0048] Figure 6 The friction test performance of the microstructured samples and flat samples of the above-mentioned sizes under different wet environments is described. During the test, the samples were pre-loaded the same. From the test results, it can be seen that when the water content per unit area is 0, that is, in a dry environment, the friction performance of the microstructured samples is equivalent to that of the flat samples. When the water content per unit area gradually increases, the friction force of the microstructured samples is greater than that of the flat samples, and the difference between the two is obvious. The friction coefficient of the microstructured samples is significantly higher than that of the flat samples.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A bionic friction pad for preventing slipping on a glass surface, characterized in that: Inspired by the micro-nano structure of the toe pads of organisms with wet friction-increasing properties, such as tree frogs and katydids, a protrusion array is added to the surface of a high-friction material, including a friction pad. The friction pad includes a connecting layer, a supporting layer, an end protrusion straight column array and a connecting layer, and the end contact layer is in the shape of a hexagonal straight column.

2. A bionic friction pad for wet anti-skid glass surface according to claim 1, characterized in that: The inscribed circle diameter of the hexagonal microcolumn structure is 5 micrometers to 5000 micrometers, the columns are arranged in a hexagonal close-packed manner, the column height is 10 micrometers to 1500 micrometers, the column ends are flat, and each column is spaced 2-600 micrometers apart, forming a tight drainage groove.

3. The bionic friction pad for wet anti-skid glass surface according to claim 1, characterized in that: The supporting layer and the end raised column array are both made of elastic materials, which are any one or a combination of natural rubber, artificial rubber, polyurethane, polyimide, polyolefin, polylactic acid, polycaprolactone, hydrogel, aerogel, and oil gel; the connecting layer material is any one or a combination of rubber, resin, metal, and ceramic.

4. The bionic friction pad for wet anti-skid glass surface according to claim 1, characterized in that: The end protruding straight column array is the part that directly contacts the object being acted on.

5. The bionic friction pad for wet anti-skid glass surface according to claim 1, characterized in that: The support layer and the end raised straight column array are integrally formed.

6. The method for preparing a bionic friction pad for wet anti-skid glass surface according to any one of claims 1 to 5, characterized in that: The preparation method of the bionic friction pad for wet anti-skid glass surface comprises: method one, method two and method three, wherein the method one comprises: Step 1: Use photolithography technology to accurately transfer the preset hexagonal microstructure array pattern to a photoresist layer evenly spin-coated on the surface of a glass substrate, and then use magnetron sputtering technology to preliminarily deposit a nickel plating layer on the surface of the material. Then, immerse the sample in an electroplating solution and further implement a nickel electroplating process to construct a high-precision metal mold; Step 2: Mix the basic components of liquid silicone and the curing agent in a certain weight ratio, and use a vacuum pump to degas under reduced pressure, and then use a spin coating method to evenly coat the silicone prepolymer on the surface of the metal mold to obtain a uniform silicone film; Step 3: Place the connecting layer coated with silicone prepolymer lightly on the surface of the metal mold coated with silicone prepolymer, and apply about 0.2N / cm 2 The normal pressure is applied to ensure that the two surfaces are completely fitted together, increasing the bonding force between the connecting layer and the supporting layer. After vacuuming, the pad is placed in an oven for curing, and after demoulding, a bionic friction pad with an array of protruding straight columns at the end is obtained.

7. The method for preparing a bionic friction pad for wet anti-skid glass surface according to claim 6, characterized in that: The second method comprises: Step 1: placing a metal mold of a preset shape in a metal cavity of corresponding thickness and configuration, and heating it; Step 2: evenly lay the rubber raw material on the preheated metal mold, and then perform a hot pressing vulcanization process for about 5 minutes to form a rubber sheet with a fine structure; Step 3: Use an adhesive to evenly and firmly adhere the rubber sheet prepared above to the surface of the connecting layer.

8. The method for preparing a bionic friction pad for wet anti-skid glass surface according to claim 6, characterized in that: The third method comprises: Step 1: pre-treat the surface of the connection layer component to remove impurities such as oil, dust, etc., and embed it in the mold cavity; Step 2: Place the precision metal mold at the bottom of the mold cavity, and evenly lay the rubber raw material between the connecting layer component and the metal mold; Step 3: Curing the rubber material by heating and pressurizing to form a rubber coating layer with a fine structure on the end surface, and the rubber coating layer is firmly combined with the connecting layer component.

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