Synthetic leather composite silica gel humanoid robot simulation skin, and preparation method and application thereof

Abstract

The application discloses synthetic leather composite silica gel humanoid robot simulation skin and a preparation method and application thereof, and belongs to the humanoid robot surface material application field. The skin comprises, from outside to inside, a synthetic leather layer with bionic texture, a water-based polyurethane interface layer with a thickness of 0.03-0.06 mm, and a silica gel layer. The water-based polyurethane interface layer is composed of a water-based polyurethane-silicone block copolymer with a hydroxyethyl acrylate end cap and a side chain containing a vinyl group. In the preparation, the water-based polyurethane interface layer is first formed on the back of the synthetic leather, then a platinum gold catalyst is sprayed on the interface and a mold, and finally the addition type liquid silica gel containing a silicon hydrogen bond is compounded in the mold and is cured at 24-26 DEG C and 40%-60% humidity. Peeling damage is realized to occur in the silica gel body; meanwhile, the interface layer and the synthetic leather cooperatively constitute a double barrier, so that the silicon oil exosmosis is avoided. The product has strong comprehensive advantages, and the process is environment-friendly and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of humanoid robot surface material application, specifically relating to a synthetic leather composite silicone humanoid robot simulated skin, its preparation method and application. Background Technology

[0002] With the rapid development of humanoid robot technology, the market's demands for human-like appearance and realistic touch are constantly increasing. Currently, pure silicone is widely used as the skin material for robots. However, the following problems have been exposed in practical applications: 1. The surface texture of silicone depends entirely on the etching of the inner wall of the mold, resulting in long mold-making cycles, high costs, and a single mold can only correspond to one texture, making it difficult to meet diverse appearance requirements; 2. Silicone has low surface hardness and poor wear resistance, making it prone to wear and scratches when the robot's joints move frequently or come into contact with the outside world; 3. Silicone oil-based additives added to the silicone will migrate to the surface over time, resulting in a sticky feel, changes in surface gloss, and easy dust attraction; 4. The feel of pure silicone skin is either too "rough" or too "slippery," which differs from the delicate and slightly rough feel of human skin.

[0003] Patent application CN117021699 A discloses a biomimetic robot skin and its preparation method, employing a multi-layer silicone gradient hardness structure combined with elastic fiber cloth, prepared through vacuum curing and precise temperature control. While this approach simulates skin elasticity to some extent, it still fails to address issues such as strong dependence on mold texture, poor surface wear resistance, and silicone oil precipitation. Furthermore, the multiple vacuum curing and precise temperature control processes result in complex manufacturing processes and high costs.

[0004] If polyurethane synthetic leather is directly used as the surface material to bond silicone, the texture and wear resistance problems can be solved. However, due to the extremely low surface energy of silicone, traditional adhesives cannot form an effective bond, and quality problems such as delamination and bulging are very likely to occur during use.

[0005] Therefore, developing a humanoid robot skin that can achieve rich biomimetic textures, excellent surface wear resistance, and ensure a firm bond between synthetic leather and silicone layer is of great practical significance. Summary of the Invention

[0006] One of the objectives of this invention is to provide a synthetic leather composite silicone humanoid robot simulated skin to solve the problems of existing pure silicone skin, such as monotonous texture, poor surface wear resistance, silicone oil exudation causing a sticky feel, and poor interfacial bonding when composited with synthetic leather.

[0007] The second objective of this invention is to provide a method for preparing a synthetic leather composite silicone humanoid robot simulated skin, which is used to prepare the aforementioned synthetic leather composite silicone humanoid robot simulated skin.

[0008] The third objective of this invention is to provide an application of synthetic leather composite silicone humanoid robot simulated skin in humanoid robots.

[0009] The objective of this invention can be achieved through the following technical solutions: Firstly, a synthetic leather composite silicone humanoid robot simulated skin, comprising layers stacked sequentially from the outside in: The synthetic leather layer has a biomimetic texture on its outer surface; A waterborne polyurethane interface layer is formed on the inner surface of the synthetic leather layer, with a thickness of 0.03-0.06 mm. The waterborne polyurethane interface layer is formed by drying a waterborne interface treatment agent at 65-75°C. The waterborne interface treatment agent contains a waterborne polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl side chains. The silicone layer is formed by curing addition-type liquid silicone containing silane bonds in the presence of a platinum catalyst at 24-26°C and 40%-60% humidity, and the silicone layer is chemically bonded to the waterborne polyurethane interface layer through Si-C covalent bonds.

[0010] The biomimetic texture of the synthetic leather layer is prefabricated using a release paper transfer process, decoupling the texture from the mold and eliminating the need for re-molding when changing the texture. The waterborne polyurethane interface layer, 0.03-0.06 mm thick, is formed by drying a waterborne treatment agent containing hydroxyethyl acrylate-terminated, vinyl-side-chain waterborne polyurethane-silicone block copolymer at 65-75°C. The polyurethane backbone of this copolymer provides film-forming properties and affinity for synthetic leather; the silicone side chains reduce interfacial tension and promote molecular-level wetting of silicone; the terminal acrylate double bonds and the vinyl side chains serve as chemical anchors for subsequent hydrosilylation reactions. The 0.03-0.06 mm thickness represents an optimized balance between bonding strength and barrier continuity. Drying at 65-75°C ensures sufficient moisture evaporation and crosslinking reaction while preserving the activity of the terminal double bonds.

[0011] The silicone layer is formed by curing addition-type liquid silicone containing Si-H bonds under platinum catalyst and conditions of 24-26℃ and 40%-60% humidity, and is chemically bonded to the waterborne polyurethane interface layer through Si-C covalent bonds. The principle is that the catalyst is enriched at the interface, preferentially catalyzing the terminal double bonds and side chain vinyl groups of the copolymer to undergo specific hydrosilylation with the Si-H bonds of the silicone, generating a dense Si-C covalent network; at the same time, the silicone bulk also undergoes hydrosilylation crosslinking to form a three-dimensional elastic network.

[0012] Furthermore, the aqueous polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl-containing side chains is prepared by the following steps: (1) Polyether diol and diisocyanate are reacted at 80-90℃ for 1.5-2.5 hours under an inert atmosphere to obtain a polyurethane prepolymer with isocyanate end groups; (2) Cool down to 70-80℃, add dimethylolpropionic acid as a hydrophilic chain extender, and react for 1-2 hours in the presence of a catalyst to introduce carboxyl groups into the prepolymer chain segment; (3) Cool down to 55-65℃, add vinyl-containing silane coupling agent, react for 1-2 hours, so that the silane coupling agent is grafted to the side chain of the prepolymer through condensation reaction to obtain polyurethane-organosilicon prepolymer with vinyl side chain. (4) Cool down to 50-60℃, add hydroxyethyl acrylate for end-capping reaction, stir the reaction for 2-4 hours until the isocyanate group reacts completely and acrylate double bonds are introduced at the end of the molecular chain; (5) Cool down to below 40°C, add a neutralizing agent to form salt, add deionized water under high speed stirring to perform reverse emulsification, and obtain the waterborne polyurethane-silicone block copolymer emulsion with hydroxyethyl acrylate end-capped and vinyl side chain; The composition, by weight, includes 100 parts polyether glycol, 25-45 parts diisocyanate, 5-10 parts dimethylolpropionic acid, 6-15 parts vinyl silane coupling agent, and 3-8 parts hydroxyethyl acrylate.

[0013] First, a polyurethane backbone is constructed and carboxyl groups are introduced through prepolymerization and chain extension. Then, organosilicon and side-chain vinyl groups are introduced by side-linking using a vinyl silane coupling agent. Finally, terminal double bonds are introduced by end-capping with hydroxyethyl acrylate, followed by neutralization and emulsification to obtain an emulsion. This sequence ensures that each functional group is accurately located on the molecular chain.

[0014] Furthermore, the vinyl-containing silane coupling agent mentioned in step (3) is at least one of vinyltrimethoxysilane and vinyltriethoxysilane. The alkoxy group of vinyltrimethoxy / triethoxysilane can be condensed and grafted with the active hydrogen on the polyurethane chain, while the vinyl group provides the reaction anchor.

[0015] Furthermore, the water-based interface treatment agent, by weight, comprises the following components: 100 parts of the copolymer, 0.5-2 parts of isocyanate curing agent, 0.5-2 parts of leveling agent, 0.1-2 parts of abrasion-resistant agent, and 0.1-1 parts of water-based thickener; during the drying process in step S1, the isocyanate groups of the isocyanate curing agent undergo a cross-linking reaction with the active hydrogen on the copolymer chain and the active groups on the back of the synthetic leather, thereby constructing a cross-linked interpenetrating network inside the interface layer and between the interface layer and the synthetic leather.

[0016] Furthermore, the isocyanate curing agent is a hydrophilic modified polyisocyanate based on hexamethylene diisocyanate trimer; the leveling agent is a polyether siloxane copolymer; the abrasion-resistant agent is a water-based silicone feel agent; and the water-based thickener is a nonionic associative polyurethane thickener. The use of hydrophilic modified polyisocyanate ensures water dispersibility, the leveling agent improves film formation, the abrasion-resistant agent enhances surface properties, and the thickener adjusts the application viscosity.

[0017] Furthermore, the synthetic leather is a hydrolysis-resistant polyurethane synthetic leather with a thickness of 0.5-1.2 mm. Its surface biomimetic texture is formed through a release paper transfer process, and the texture types include biomimetic leather texture, pore texture, or fingerprint texture. The hydrolysis-resistant PU leather ensures durability, and the release paper transfer texture enables low-cost and diversified biomimetic textures.

[0018] Furthermore, the thickness of the silicone layer is 2-8 mm; the addition-type liquid silicone is the Silastic™ MDX4-4210 series; the platinum catalyst is KP25, and its spraying amount on the surface of the waterborne polyurethane interface layer is 3-5 g / m². 2 Silastic™ MDX4-4210 is a medical-grade addition-type silicone containing Si-H components; KP25 is a highly active platinum catalyst; interfacial spraying ensures enrichment of catalytic sites.

[0019] Secondly, a method for preparing a synthetic leather composite silicone humanoid robot simulated skin includes the following steps: S1. Select a polyurethane synthetic leather with a biomimetic texture on the surface, spray a water-based interface treatment agent onto the non-textured back of the synthetic leather, and dry it at 65-75℃ to form a water-based polyurethane interface layer with a thickness of 0.03-0.06mm; the water-based interface treatment agent contains a water-based polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl side chains. S2. A platinum-based silicone catalyst is sprayed onto the surface of the waterborne polyurethane interface layer obtained in step S1 and onto the inner wall of the mold cavity. S3. The synthetic leather treated in step S2 is laid flat with its texture facing down and fixed to the inner surface of the mold cavity. After the mold is closed, the uniformly mixed addition-type liquid silicone containing silane bonds is injected into the mold cavity. It is cured for 4-6 hours at a temperature of 24-26℃ and a humidity of 40%-60%. During this period, the terminal double bonds and side chain vinyl groups of the copolymer undergo silane addition reactions with the silane bonds in the silicone under the action of a platinum catalyst to form multi-site chemical bonds. S4. After demolding, the humanoid robot simulated skin made of synthetic leather composite silicone is obtained.

[0020] The dependence on mold etching is solved by selecting synthetic leather (S1), and a chemically active interface is constructed using an interface treatment agent containing copolymers. The interface is guided to preferentially undergo hydrosilylation at the interface by spraying a catalyst (S2). The Si-H silicone is injected into the mold and cured at a specific temperature and humidity (S3), so that the end double bonds and side chain vinyl groups of the copolymer undergo multi-site hydrosilylation with the silicone to form chemical bonds. The product is obtained by demolding (S4).

[0021] Furthermore, the viscosity of the water-based interface treatment agent is controlled at 2000-3000 cps; the nozzle diameter of the spray gun used for spraying is 0.5 mm, and the spraying pressure is 0.6-1.0 MPa. The viscosity of 2000-3000 cps and the pressure of 0.6-1.0 MPa ensure uniform atomization, forming a defect-free film layer with controllable thickness.

[0022] Furthermore, the mold cavity has a smooth surface, and its depth determines the thickness of the silicone layer.

[0023] Thirdly, the application of a synthetic leather composite silicone humanoid robot simulated skin in humanoid robots, wherein the simulated skin is used to cover the jointed and non-jointed parts of the humanoid robot to provide a low-cost switchable biomimetic texture, wear-resistant surface, dry touch without silicone oil seepage, and a highly realistic human skin tactile experience.

[0024] The beneficial effects of this invention are: (1) This invention changes the traditional silicone skin process that relies on mold etching to obtain texture by selecting polyurethane synthetic leather with biomimetic textures as the skin surface. The biomimetic texture of the synthetic leather is pre-formed through a release paper transfer process. During production, the appearance of the product can be switched on the same set of smooth molds by changing the synthetic leather rolls with different textures. There is no need to make a separate etching mold for each texture, which greatly reduces the mold opening cost and significantly improves the diversity of textures. At the same time, the surface of polyurethane synthetic leather has excellent wear and scratch resistance. The Taber abrasion test can reach more than 3000 revolutions (H22, 1kg) without obvious damage, which effectively solves the problem of pure silicone skin being easily worn and scratched when the robot joints move.

[0025] (2) This invention uses a waterborne interface treatment agent formulated from a waterborne polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl-containing side chains. The thickness of the waterborne polyurethane interface layer is controlled at 0.03-0.06 mm, constructing a chemically bonded interface layer between synthetic leather and silicone. The copolymer molecular chain simultaneously possesses a polyurethane backbone, silicone side chains, vinyl side chains, and terminal acrylate double bonds. After spraying a platinum catalyst onto the interface, the catalytic active centers preferentially accumulate at the interface to be bonded, guiding the hydrosilylation reaction to occur preferentially in the interface region, while reducing the risk of incomplete interface reaction. Addition-type liquid silicone containing hydroxyl bonds is injected and cured for 4-6 hours at a temperature of 24-26℃ and a humidity of 40%-60%. The terminal double bonds and side chain vinyls of the copolymer undergo hydrosilylation reactions with the hydroxyl bonds of the silicone, forming multi-site Si-C covalent bonds. This mechanism ensures that peeling failure occurs in the silicone body rather than the interface layer, resulting in high bonding strength and solving the quality problem of easy delamination between synthetic leather and silicone in traditional adhesive processes.

[0026] (3) The three structural elements employed in this invention—terminal double bonds, side-chain vinyl groups, and side-chain organosilicon—exhibit synergistic effects and complement the process design of catalyst interface enrichment. The principle is as follows: The acrylate double bonds at the ends of the copolymer have low steric hindrance and preferentially undergo hydrosilylation reactions with the silane bonds of silica gel under the action of platinum catalysts; the side-chain vinyl groups are distributed throughout the molecular chain, providing a large number of secondary reaction sites after the terminal double bonds initiate bonding, expanding from "points" to a "surface" bonding network. The side-chain organosilicon blocks (PDMS structure) reduce interfacial tension, allowing the copolymer to tightly wet the silica gel surface at the molecular level, ensuring effective contact of each anchor point rather than suspension. This synergistic effect also brings the following benefits: the chemically cross-linked interface layer and the synthetic leather surface layer together form a double barrier, effectively preventing the migration of silicone oil from the silicone interior to the surface. After 5 weeks at 70℃ / 95%RH, the surface remains dry and clean, solving the problem of oiliness on the surface of pure silicone skin, which leads to a sticky feel and easy dust attraction. The synthetic leather surface layer provides a slightly rough and delicate touch similar to the stratum corneum of human skin, while the silicone inner layer provides a soft and elastic feel when pressed. The two are connected by a chemically bonded interface layer, simulating the layered mechanical characteristics of the human "epidermis-dermis", and the touch is closer to that of real skin than that of pure silicone.

[0027] (4) In this invention, the synthetic leather texture is fixed downwards in the mold cavity. After the mold is closed, addition-curing liquid silicone is injected. One set of smooth molds can be adapted to synthetic leathers with all textures, thus achieving decoupling between the mold and the texture. The preparation process uses water as the dispersion medium, does not involve organic solvents, and has low VOC emissions. The silicone cures at room temperature, resulting in low energy consumption. The depth of the mold cavity can be flexibly controlled to adjust the silicone layer thickness from 2 to 8 mm, meeting the needs of different parts of the robot. Attached Figure Description

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of the cross-sectional structure of the synthetic leather composite silicone humanoid robot simulated skin prepared in Example 1 of the present invention. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0031] Preparation Example 1: Synthesis of HEA-terminated WPU-Si copolymer emulsion (WPU-Si-1) Under dry nitrogen protection, 40.0 g of polytetrahydrofuran ether diol (PTMG, Mn≈2000 g / mol) and 12.0 g of isophorone diisocyanate (IPDI) were added sequentially to a 500 mL four-necked flask. The system was heated to 85 °C with stirring and reacted at this temperature for 2 hours to obtain a polyurethane prepolymer with isocyanate-terminated (-NCO) groups. Cool to 75°C, add 2.2g of dimethylolpropionic acid (DMPA), and add 2 drops of dibutyltin dilaurate (DBTDL) as a catalyst. Continue stirring the reaction at 75°C for 1.5 hours to introduce carboxyl groups into the prepolymer chain segment. The system temperature was then lowered to 60-65℃, and 3.5g of vinyltrimethoxysilane (VTMS) was added dropwise. The reaction was carried out for 1.5 hours. During this process, the methoxy group of the silane condensed with the active hydrogen on the prepolymer chain, grafting the vinyl silane segment onto the polyurethane side chain to obtain a polyurethane-organosilicon prepolymer with vinyl side chain.

[0032] Then lower the system temperature to 55-60℃, add 1.8g of precisely measured hydroxyethyl acrylate (HEA) dropwise, and keep the mixture warm and stir for 3 hours. Stop heating and cool the system to below 40°C. While stirring at high speed (1500-2000 rpm), slowly add the theoretical amount of deionized water (approximately 120 g) required to neutralize the carboxyl groups of DMPA with 1.6 g of triethylamine (TEA) to the reaction flask to perform reverse emulsification; after continuous dispersion for 30 minutes, a waterborne polyurethane-silicone block copolymer emulsion (WPU-Si-1) with hydroxyethyl acrylate end-capped and vinyl-containing side chains is obtained.

[0033] Preparation Example 2: Synthesis of HEA-terminated WPU-Si copolymer emulsion (WPU-Si-2) The difference between this preparation example and Preparation Example 1 is that the amount of vinyltrimethoxysilane was adjusted from 3.5 g to 5.0 g to further increase the grafting density of the side-chain vinyl groups. The remaining synthesis steps and raw materials are the same as in Preparation Example 1.

[0034] Preparation Example 3: Synthesis of HEA-terminated WPU-Si copolymer emulsion (WPU-Si-3) The difference between this preparation example and Preparation Example 1 is that the amount of vinyltrimethoxysilane is adjusted from 3.5g to 1.5g, appropriately reducing the grafting density of the side-chain vinyl groups. The remaining synthesis steps and raw materials are the same as in Preparation Example 1.

[0035] Preparation Example 4: Synthesis of a waterborne polyurethane-silicone copolymer emulsion (WPU-Si-4) with only side-chain vinyl groups and no terminal double bonds. The difference between this preparation example and Preparation Example 1 is that hydroxyethyl acrylate is not used for end-capping; instead, an equimolar amount of ethanol is used. The resulting copolymer has vinyl and organosilicon blocks in its side chains, but no carbon-carbon double bonds at the molecular chain ends. The remaining synthesis steps and raw materials are the same as in Preparation Example 1.

[0036] Preparation Example 5: Synthesis of an aqueous polyurethane copolymer emulsion (WPU-Si-5) with only terminal double bonds capped and side chains containing silicone but no vinyl groups. The difference between this preparation example and Preparation Example 1 is that vinyltrimethoxysilane is replaced with an equimolar amount of methyltrimethoxysilane (a vinyl-free silane coupling agent). The resulting copolymer has organosilicon blocks in its side chains and acrylate double bonds at the ends of the molecular chains, but no vinyl groups participating in hydrosilylation are present in the side chains. The remaining synthesis steps and starting materials are the same as in Preparation Example 1.

[0037] Example 1 This embodiment provides a synthetic leather composite silicone humanoid robot simulated skin, which is prepared through the following steps: S1. Take 100 parts by weight of WPU-Si-1 emulsion, and under mechanical stirring, add 1.0 part by weight of isocyanate curing agent WH-268, 0.5 parts by weight of polyether silicone copolymer leveling agent WH-907, 0.5 parts by weight of water-based silicone abrasion-resistant hand feel agent DC-51, and 0.2 parts by weight of nonionic associative polyurethane thickener RM-12W. After the addition is complete, continue stirring for 20 minutes until uniform and defoamed. Adjust the viscosity to 3000 cps to obtain the water-based interface treatment agent; Commercially available hydrolysis-resistant polyurethane synthetic leather was selected. The base fabric was microfiber nonwoven fabric, and the surface layer was polyether polyurethane with a thickness of 0.8 mm and a clear biomimetic leather texture. The above-mentioned water-based interface treatment agent was evenly sprayed onto the back of the synthetic leather and dried in an oven at 70°C. The wet film thickness was controlled so that the dry film thickness was about 0.04 mm, forming a water-based polyurethane interface layer on the back of the synthetic leather. S2. The platinum-based silica gel catalyst KP25 is uniformly sprayed onto the surface of the above-mentioned waterborne polyurethane interface layer and the inner wall of the mold cavity, with the catalyst spraying amount precisely controlled at 4 g / m³.2 ; S3. Lay the synthetic leather textured surface flat with the surface facing down and fix it to the inner surface of the mold cavity. After closing the mold (the mold cavity depth is 4mm), inject the well-mixed addition-curing liquid silicone Silastic™ MDX4-4210 at 0 degrees Celsius into the mold cavity. The silicone AB ratio is 100:100. After curing for 5 hours at 25°C and 50% humidity, demold. S4. After demolding, you can obtain the synthetic leather composite silicone humanoid robot simulation skin.

[0038] The prepared synthetic leather composite silicone humanoid robot simulated skin was applied to the humanoid robot.

[0039] A schematic diagram of the cross-sectional structure of the humanoid robot simulated skin prepared in this embodiment is shown below. Figure 1 As shown.

[0040] Example 2 The difference between this embodiment and Example 1 is that a hydrolysis-resistant polyurethane synthetic leather with a biomimetic pore texture and a thickness of 1.0 mm is selected; the amount of crosslinking agent WH-268 in the interface treatment agent formulation is adjusted to 1.5 parts, the amount of thickener RM-12W is adjusted to 0.15 parts, the viscosity is adjusted to 2500 cps, and the thickness of the waterborne polyurethane interface layer after drying is 0.05 mm; the amount of catalyst KP25 sprayed is adjusted to 3 g / m 2 The mold cavity depth was adjusted to 3.0 mm; the silicone type was changed to Silastic™ MDX4-4210 5; the curing time was 4 hours. The remaining raw materials and preparation process remained the same as in Example 1.

[0041] Example 3 Compared with Example 1, this embodiment differs in that it uses hydrolysis-resistant polyurethane synthetic leather with a fine fingerprint texture and a thickness of 0.6 mm; the amount of crosslinking agent WH-268 in the interface treatment agent formulation is adjusted to 0.8 parts, the amount of thickener RM-12W is adjusted to 0.15 parts, the viscosity is adjusted to 2800 cps, and the thickness of the waterborne polyurethane interface layer after drying is 0.03 mm; the amount of catalyst KP25 sprayed is adjusted to 5 g / m 2 The mold cavity depth was increased to 6.0 mm; the silicone type was Silastic™ MDX4-4210 0; the curing time was 6 hours. All other raw materials and preparation processes remained the same as in Example 1.

[0042] Example 4 The difference between this embodiment and Example 1 is that the WPU-Si-2 emulsion synthesized in Preparation Example 2 is used to replace WPU-Si-1 in an equal amount to prepare the interface treatment agent. All other raw materials and preparation processes remain the same as in Example 1.

[0043] Example 5 The difference between this embodiment and Example 1 is that the WPU-Si-3 emulsion synthesized in Preparation Example 3 is used in an equal amount to replace WPU-Si-1 in the preparation of the interface treatment agent. All other raw materials and preparation processes remain the same as in Example 1.

[0044] Example 6 The difference between this embodiment and Example 1 is that the thickness of the waterborne polyurethane interface layer after drying is controlled to be 0.03 mm by adjusting the thickness of the sprayed wet film and the atomization pressure. All other raw materials and preparation processes remain the same as in Example 1.

[0045] Example 7 The difference between this embodiment and Example 1 is that the thickness of the waterborne polyurethane interface layer after drying is controlled to 0.06 mm by adjusting the thickness of the sprayed wet film. All other raw materials and preparation processes remain the same as in Example 1.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that a metal mold with a cavity depth of 4.8 mm and an inner wall chemically etched with a similar leather texture was used; synthetic leather and interface treatment agents were not used, and Silastic™ MDX4-4210 0 silicone was directly injected into the mold and cured for 5 hours under the same conditions before demolding. All other raw materials and preparation processes remained the same as in Example 1.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that the WPU-Si-1 interface treatment agent used in Example 1 was not employed. Instead, a commercially available ordinary anionic waterborne polyurethane adhesive (50% solids content, free of double bonds and silicone modification) was applied to the back of the same synthetic leather and dried at 70°C until the adhesive layer remained tacky. The synthetic leather was then hot-pressed onto a pre-cured 4.0mm thick MDX4-4210 silicone sheet at 80°C and 0.5MPa for 2 minutes. All other raw materials and preparation processes remained the same as in Example 1.

[0048] Comparative Example 3 The difference between this comparative example and Example 1 is that, following a similar method to Example 1, a conventional aqueous polyurethane (denoted as WPU-C) was synthesized, consisting only of HEA end-capping without the addition of vinyltrimethoxysilane for side-linking. The WPU-C molecular chain has double bonds at the ends, but the entire chain consists of pure polyurethane segments, without organosilicon side chains or vinyl side chains. The WPU-C was used to completely replace WPU-Si-1 in Example 1, and the interface treatment agent was formulated and the composite skin was prepared according to the exact same steps and conditions. All other raw materials and preparation processes remained the same as in Example 1.

[0049] Comparative Example 4 The difference between this comparative example and Example 1 is that the WPU-Si-4 emulsion synthesized in Preparation Example 4 was used in an equal amount to replace WPU-Si-1 in the preparation of the interface treatment agent. All other raw materials and preparation processes remained the same as in Example 1.

[0050] Comparative Example 5 The difference between this comparative example and Example 1 is that the WPU-Si-5 emulsion synthesized in Preparation Example 5 was used in an equal amount to replace WPU-Si-1 in the preparation of the interface treatment agent. All other raw materials and preparation processes remained the same as in Example 1.

[0051] Performance testing After all samples prepared in the examples and comparative examples were conditioned for 48 hours in a standard environment (23°C / 50%RH), the following performance tests were performed: 1. Abrasion resistance: The abrasion resistance test was conducted according to QB / T 5253.1-2018 "Leather Physical and Mechanical Tests - Determination of Staining Properties - Part 1: Martindale Friction Method" (Test standard: 500,000 cycles). 2. Weather resistance (oil exudation test): The test shall be conducted in accordance with QB / T 4671-2014 "Test Methods for Hydrolysis Resistance of Artificial Leather and Synthetic Leather" (Test standard: 70℃×95%RH×5W), and the presence of oil exudation on the surface shall be observed. 3. Peel strength: The peel strength test was conducted according to GB / T 2792-2014 "Test method for peel strength of adhesive tape" (test standard: 100 mm / min). 4. Touch evaluation: Ten testers were invited to conduct a blind touch test on the samples (1-10 points, with 10 points being the closest to real human skin). 5. Hardness: Tested according to GB / T 39693.4-2025 "Determination of hardness of vulcanized rubber or thermoplastic rubber - Part 4: Determination of indentation hardness by Shore hardness tester (Shore hardness)"; 6. Cost (RMB / m) 2 Cost accounting for each sample; 7. Weight (g / m³) 2 ): The test was conducted according to ISO 3801:1977 "Textiles - Determination of mass per unit length and mass per unit area of ​​woven fabrics".

[0052] The results are shown in Table 1: Table 1

[0053] As shown in Table 1, Comparative Example 2, using traditional polyurethane adhesive, achieved a peel strength of only 2.1 N / cm relying solely on physical adsorption and mechanical interlocking, indicating interface failure. This reveals the fundamental nature of the complete failure of physical adhesion due to the low surface energy of silicone. Comparative Example 3 introduced terminal double bonds, which could form single-point chemical anchoring through hydrosilylation, increasing the peel strength to 8.5 N / cm. However, the failure mode was mixed failure, indicating poor wettability between pure PU segments and silicone, sparse effective bond connections, and a failure to form a complete bonding network. Comparative Example 4 retained only the side-chain vinyl groups while sealing the terminal double bonds, resulting in a peel strength of 6.2 N / cm, primarily due to interface failure. This demonstrates that the bonding efficiency of the side-chain vinyl groups is far lower than that of the terminal double bonds due to steric hindrance. Comparative Example 5 removed the side-chain vinyl groups while retaining the terminal double bonds and the silicone wetting of the side chains. The peel strength rebounded to 12.5 N / cm, but it was still mixed failure, indicating that relying solely on terminal anchor points and improved wetting is insufficient to form a dense bonding network spanning the entire chain.

[0054] Examples 1-7 all achieved bulk destruction of the silicone, with peel strength exceeding the cohesive strength of the silicone. The principle behind this is that the WPU-Si copolymer, through molecular design, simultaneously possesses "terminal double bonds," "side-chain vinyl groups," and "side-chain organosilicon segments." Under conditions where the platinum catalyst is enriched at the interface, the Si-H bonds of the silicone undergo multi-site hydrosilylation reactions with the C=C bonds of the copolymer, forming a dense Si-C covalent bond network. The wetting of the side-chain organosilicon ensures effective contact at each anchor point, the terminal double bonds provide preferential sites for reaction initiation, and the side-chain vinyl groups extend the bond density to the entire interface; these three factors synergistically significantly improve performance.

[0055] Comparative Example 1: Pure silicone exhibited severe oil seepage within 24 hours, primarily due to its loose cross-linking and large free volume, allowing silicone oil molecules to migrate freely. Comparative Examples 3-5, although using reactive copolymers, all showed slight or very slight oil seepage, indicating that a single chemically bonded interface layer or a single microphase separation morphology is insufficient to construct a complete barrier. Examples 1-7 showed completely dry surfaces after 5 weeks of accelerated aging. This effect is attributed to the extremely high cross-linking density formed by the isocyanate curing agent, copolymer, and synthetic leather; and the excellent barrier properties provided by the microphase separation of polyurethane hard / soft segments and silicone blocks.

[0056] The tactile scores of Examples 1-7 were all ≥8.8, significantly better than Comparative Example 1 (6.2) and Comparative Example 2 (7.8). The biomimetic texture of the synthetic leather surface and the polyurethane material provided a slightly abrasive damping sensation similar to the stratum corneum of human skin, while the silicone layer provided a deep, soft, and elastic feel. Through the seamless chemically bonded interface layer, force transmission was continuous and smooth, replicating the layered tactile sensation of human skin. The changes in thickness parameters in Examples 6 and 7 showed slight fluctuations in the tactile scores, but all were within an acceptable range, demonstrating that the 0.03-0.06 mm interface layer thickness window ensured both bonding strength and barrier performance while also providing a soft and natural tactile feel.

[0057] In terms of cost, the unit area cost of Example 1 is only 385 yuan / m². 2 Comparison ratio 1: Pure silicone skin (1210 yuan / m) 2 The cost is reduced by approximately 68%. Furthermore, the raw material cost of synthetic leather is lower than that of medical-grade silicone of the same thickness. In terms of weight, the weight per unit area of ​​Example 1 is 3620 g / m². 2 Comparison ratio 1: Pure silicone skin (5500g / m²) 2 The weight is reduced by approximately 34%. This is significant for humanoid robots, as lighter skin can reduce joint load, improve mobility, and extend battery life.

[0058] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A synthetic leather composite silica gel humanoid robot artificial skin, characterized in that, Including layers stacked from the outside in: The synthetic leather layer has a biomimetic texture on its outer surface; A waterborne polyurethane interface layer is formed on the inner surface of the synthetic leather layer, with a thickness of 0.03-0.06 mm. The waterborne polyurethane interface layer is formed by drying a waterborne interface treatment agent at 65-75°C. The waterborne interface treatment agent contains a waterborne polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl side chains. The silicone layer is formed by curing addition-type liquid silicone containing silane bonds in the presence of a platinum catalyst at 24-26°C and 40%-60% humidity, and the silicone layer is chemically bonded to the waterborne polyurethane interface layer through Si-C covalent bonds.

2. The synthetic leather composite silica gel humanoid robot artificial skin according to claim 1, characterized in that, The aqueous polyurethane-silicone block copolymer, which is end-capped with hydroxyethyl acrylate and contains vinyl side chains, is prepared by the following steps: (1) Polyether diol and diisocyanate are reacted at 80-90℃ for 1.5-2.5 hours under an inert atmosphere to obtain a polyurethane prepolymer with isocyanate end groups; (2) Cool down to 70-80℃, add dimethylolpropionic acid as a hydrophilic chain extender, and react for 1-2 hours in the presence of a catalyst to introduce carboxyl groups into the prepolymer chain segment; (3) Cool down to 55-65℃, add vinyl-containing silane coupling agent, react for 1-2 hours, so that the silane coupling agent is grafted to the side chain of the prepolymer through condensation reaction to obtain polyurethane-organosilicon prepolymer with vinyl side chain. (4) Cool down to 50-60℃, add hydroxyethyl acrylate for end-capping reaction, stir the reaction for 2-4 hours until the isocyanate group reacts completely and acrylate double bonds are introduced at the end of the molecular chain; (5) Cool down to below 40°C, add a neutralizing agent to form salt, add deionized water under high speed stirring to perform reverse emulsification, and obtain the waterborne polyurethane-silicone block copolymer emulsion with hydroxyethyl acrylate end-capped and vinyl side chain; The composition, by weight, includes 100 parts polyether glycol, 25-45 parts diisocyanate, 5-10 parts dimethylolpropionic acid, 6-15 parts vinyl silane coupling agent, and 3-8 parts hydroxyethyl acrylate.

3. The synthetic leather composite silica gel humanoid robot artificial skin according to claim 2, characterized in that, The vinyl-containing silane coupling agent mentioned in step (3) is at least one of vinyltrimethoxysilane and vinyltriethoxysilane.

4. The synthetic leather composite silica gel humanoid robot artificial skin according to claim 1, characterized in that, The water-based interface treatment agent, by weight, comprises the following components: 100 parts of the water-based polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl-containing side chains, 0.5-2 parts of isocyanate curing agent, 0.5-2 parts of leveling agent, 0.1-2 parts of wear-resistant agent, and 0.1-1 parts of water-based thickener.

5. The synthetic leather composite silicone humanoid robot simulated skin according to claim 4, characterized in that, The isocyanate curing agent is a hydrophilic modified polyisocyanate based on hexamethylene diisocyanate trimer; the leveling agent is a polyether siloxane copolymer; the abrasion-resistant agent is a water-based organosilicon hand feel agent; and the water-based thickener is a nonionic associative polyurethane thickener.

6. The synthetic leather composite silicone humanoid robot simulated skin according to claim 1, characterized in that, The thickness of the synthetic leather layer is 0.5-1.2 mm, and the synthetic leather is a hydrolysis-resistant polyurethane synthetic leather with biomimetic texture types including biomimetic leather texture, pore texture or fingerprint texture.

7. The synthetic leather composite silicone humanoid robot simulated skin according to claim 1, characterized in that, The thickness of the silicone layer is 2-8 mm; the addition type liquid silicone is Silastic™ MDX4-4210 series; the platinum catalyst is KP25, and the spraying amount of KP25 on the surface of the aqueous polyurethane interfacial layer is 3-5 g / m 2 .

8. A method for preparing humanoid robot simulated skin made of synthetic leather composite silicone, characterized in that, The method for preparing the synthetic leather composite silicone humanoid robot simulated skin according to any one of claims 1-7 comprises the following steps: S1. Select a polyurethane synthetic leather with a biomimetic texture on the surface, spray a water-based interface treatment agent onto the non-textured back of the synthetic leather, and dry it at 65-75°C to form a water-based polyurethane interface layer with a thickness of 0.03-0.06 mm; the water-based interface treatment agent comprises the water-based polyurethane-silicone block copolymer with hydroxyethyl acrylate end-capped and vinyl side chains as described in claim 1. S2. A platinum-based silicone catalyst is sprayed onto the surface of the waterborne polyurethane interface layer obtained in step S1 and onto the inner wall of the mold cavity. S3. The synthetic leather treated in step S2 is laid flat with its texture facing down and fixed to the inner surface of the mold cavity. After the mold is closed, the uniformly mixed addition-type liquid silicone containing silane bonds is injected into the mold cavity. It is cured for 4-6 hours at a temperature of 24-26℃ and a humidity of 40%-60%. During this period, the terminal double bonds and side chain vinyl groups of the copolymer undergo silane addition reactions with the silane bonds in the silicone under the action of a platinum catalyst to form multi-site chemical bonds. S4. After demolding, the humanoid robot simulated skin made of synthetic leather composite silicone is obtained.

9. The method for preparing the synthetic leather composite silicone humanoid robot simulated skin according to claim 8, characterized in that, The viscosity of the water-based interface treatment agent is controlled at 2000-3000 cps; the nozzle diameter of the spray gun used for spraying is 0.5 mm, and the spraying pressure is 0.6-1.0 MPa; The mold cavity has a smooth surface, and its depth determines the thickness of the silicone layer.

10. The application of the synthetic leather composite silicone humanoid robot simulated skin as described in any one of claims 1-7 in a humanoid robot, characterized in that, The simulated skin is used to cover the jointed and non-jointed parts of the humanoid robot to provide a low-cost, switchable biomimetic texture, a wear-resistant surface, a dry touch without silicone oil seepage, and a highly realistic human skin tactile experience.

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