Raw material composition for manufacturing robot skin, method for manufacturing skin, and skin

Abstract

The present application belongs to the field of robot skin, and particularly relates to a raw material composition for manufacturing robot skin, a skin manufacturing method and the robot skin. The raw material composition for manufacturing robot skin comprises silica gel, a thermoplastic elastomer, modified diphenyl methane diisocyanate, a polyether, a silane coupling agent, a catalyst and a vulcanizing agent. The content of the silica gel is more than 60 wt% based on the total mass of the raw material composition. The robot skin manufactured by the raw material composition is not prone to aging and discoloration, has a long service life, strong resistance to extrusion and stretching, and will not be cracked and softened even if the number of extrusion and stretching is large.

Description

Technical Field

[0001] This invention belongs to the field of robotic skin, specifically relating to the raw material composition for manufacturing robotic skin, the skin manufacturing method, and the skin itself. Background Technology

[0002] With increasing investment in robotics and the explosive growth of AI, humanoid robots will increasingly enter human society. It is estimated that one billion robots will emerge within the next decade, primarily serving in homes. Therefore, it is argued that robots must first and foremost be humanoid to be more acceptable and widely adopted. Currently, humanoid robots utilize various materials, with the most realistic approach using silicone cast from a human model. Their skin closely resembles human skin, achieving a near-perfect indistinguishable quality. While currently of good quality, they still suffer from the following drawbacks: they are prone to aging, discoloration, cracking, and have a short lifespan, affecting their appearance and usability; they have poor resistance to compression and stretching, and repeated compression and stretching can cause cracking and softening; their skin surface has low smoothness, high friction, and high viscosity; and they lack sensory functions, unable to perceive and respond to factors such as pressure, temperature, humidity, and odor.

[0003] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing robotic skin, such as easy aging, discoloration, short lifespan, poor resistance to compression and stretching, easy cracking and softening after repeated compression and stretching, low skin surface smoothness, high friction, high viscosity, and lack of sensing function. This invention provides a raw material composition for manufacturing robotic skin, a skin manufacturing method, and the manufactured robotic skin. The resulting robotic skin is not prone to aging and discoloration, has a long lifespan, strong resistance to compression and stretching, and will not crack or soften even after repeated compression and stretching. The skin surface is smoother and has certain sensing capabilities.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a raw material composition for manufacturing robotic skin, comprising silicone, thermoplastic elastomer, modified diphenylmethane diisocyanate, polyether, silane coupling agent, catalyst, and vulcanizing agent, wherein the silicone content is 60 wt% or more based on the total mass of the raw material composition.

[0006] In some preferred embodiments, based on the total mass of the raw material composition, the content of the silicone is 60 wt% to 77.5 wt%, the content of the thermoplastic elastomer is 10 wt% to 15 wt%, the content of the modified diphenylmethane diisocyanate is 5 wt% to 10 wt%, the content of the polyether is 5 wt% to 10 wt%, the content of the silane coupling agent is 0.5 wt% to 5 wt%, the content of the catalyst is 1 wt% to 2 wt%, and the content of the vulcanizing agent is 1 wt% to 5 wt%.

[0007] In some preferred embodiments, the silicone comprises liquid silicone, and the content of the liquid silicone is 20 wt% or more based on the total mass of the silicone.

[0008] Preferably, the silicone comprises solid silicone and liquid silicone, wherein the content of liquid silicone is 60wt% to 80wt% and the content of solid silicone is 20wt% to 40wt% based on the total mass of the silicone.

[0009] In some preferred embodiments, the thermoplastic elastomer comprises a hydrogenated styrene-butadiene-hydrogenated styrene block copolymer; the silane coupling agent comprises 3-aminopropyltriethoxysilane; the catalyst comprises cyclohexylamine and / or tetrabutyltin; and the vulcanizing agent comprises benzoyl peroxide.

[0010] In some preferred embodiments, the raw material composition further includes graphene oxide.

[0011] Preferably, the content of graphene oxide is 0.01 wt% to 2 wt% based on the total mass of the raw material composition.

[0012] Secondly, the present invention provides a method for manufacturing robot skin, which involves mixing and stirring the raw material composition for manufacturing robot skin as described in the first aspect, molding, and centrifugally rotating to obtain the robot skin.

[0013] In some preferred embodiments, the centrifugal rotation conditions include: a rotation speed of 100 rpm to 3000 rpm, a time of 3 min to 5 min, and a vacuum pressure of 0.01 bar to 0.2 bar; the mixing and stirring conditions include: a rotation speed of 50 rpm to 300 rpm, a temperature of 80°C to 300°C, and a time of 5 min to 30 min.

[0014] Thirdly, the present invention provides a robotic skin, which is manufactured by the robotic skin manufacturing method described in the second aspect.

[0015] Because silicone and thermoplastic elastomers, whether used alone or in combination, still present significant problems in the preparation of skin, and their physicochemical properties differ greatly, resulting in poor mixing effects and ineffective improvement of skin performance, this invention addresses these issues by using a composite of silicone, thermoplastic elastomers, and polyurethane to synergistically enhance the overall performance of robotic skin. This results in robotic skin that is less prone to aging, discoloration, and cracking, has a longer lifespan, and exhibits superior appearance and performance. Furthermore, the robotic skin demonstrates strong resistance to compression and stretching, remaining durable even after numerous compression and stretching cycles without cracking or softening. The surface of the robotic skin is also smoother, with lower friction and less stickiness (no noticeable stickiness).

[0016] Due to the significant differences in properties among silicone, polyurethane, and thermoplastic elastomers, they are difficult to mix evenly in the skin, often resulting in layering. To improve the mixing of these three components, the raw material composition for manufacturing robotic skin in this invention includes modified diphenylmethane diisocyanate and polyether. Modified diphenylmethane diisocyanate and polyether are added as raw material components, serving as the main raw materials required for the polyurethane reaction. Modified diphenylmethane diisocyanate has isocyanate groups (-NCO), which can react with substances containing hydroxyl groups (-OH). Silicone contains silanol groups (Si-OH) on its surface, which can react with isocyanate groups to form crosslinks. In the system of modified diphenylmethane diisocyanate, polyether, and silicone, the modified diphenylmethane diisocyanate and polyether are mixed and polymerized to generate polyurethane. The resulting polyurethane can better bond with silicone, promoting silicone... The uniform dispersion and inter-combination of silicone, thermoplastic elastomer, and polyurethane in this invention fully leverages their synergistic effects to enhance the performance of the robotic skin. The raw material composition for manufacturing the robotic skin includes a silane coupling agent. This agent typically contains a functional group (such as a silane group) capable of reacting with the silicone surface and a group (such as an amino or isocyanate group) capable of participating in the polyurethane reaction. Using the silane coupling agent as a bridge, reactive groups such as amino groups are introduced onto the silicone surface. These groups react with isocyanate groups and other groups in the polyurethane reaction, promoting deep cross-linking of silicone, polyurethane, and thermoplastic elastomer, further enhancing their synergistic effects.

[0017] The manufacturing method of robotic skin involves a mixing and stirring process that reacts to form polyurethane. Various substances, such as silicone, polyurethane, thermoplastic elastomer, and silane coupling agent, begin to cross-link with each other, resulting in an emulsion state. Centrifugal rotation is then added, during which the material is in a semi-solid state. Centrifugal rotation, on the one hand, eliminates the small amount of air bubbles generated by the polyurethane reaction, making the skin surface smoother and the strength more uniform; on the other hand, within a certain thickness range, the uniformity of the same layer is improved, which can enhance the skin's homogeneity, vertical layering, and mechanical balance (where vertical layering is relative to the skin and located in the direction parallel to centrifugation). Silicone has a high density, while polyurethane and thermoplastic elastomers are light. Through centrifugation, the denser silicone portion and the lighter polyurethane and thermoplastic elastomer portion are appropriately layered, forming a layered structure where the silicone content on the skin surface is slightly lower than the silicone content inside the skin, and the polyurethane and thermoplastic elastomer content on the skin surface is slightly higher than the polyurethane and thermoplastic elastomer content inside the skin. Thermoplastic elastomers have good elasticity, tensile strength, and impact resistance, while polyurethane has good color retention. By bringing thermoplastic elastomers and polyurethane relatively closer to the skin surface, it is more conducive to improving the skin's elasticity, tensile strength, impact resistance, strength uniformity, and surface smoothness, and improving skin tone. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a photograph of the appearance of the robot skin one year after it was molded, as shown in Example 1.

[0020] Figure 2 This is a photo of the robot's skin after it was molded, as shown in Comparative Example 1. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The inventors of this invention have discovered that existing robotic skin is prone to aging, discoloration, and has a short lifespan. It also has poor resistance to compression and stretching, and is prone to cracking and softening after repeated compression and stretching. Furthermore, the skin has low surface smoothness, high friction, high stickiness, and no sensing function.

[0023] In this regard, in a first aspect, the present invention provides a raw material composition for manufacturing robotic skin, comprising silicone, thermoplastic elastomer, modified diphenylmethane diisocyanate, polyether, silane coupling agent, catalyst, and vulcanizing agent, wherein the silicone content is 60 wt% or more based on the total mass of the raw material composition.

[0024] The raw material composition for manufacturing robot skin of the present invention includes silicone at a content of 60 wt% or more, with silicone as the main component as the matrix. Silicone is close to human skin and has a soft feel, which can improve the softness of robot skin. Silicone is heat resistant and has good stability in a wide temperature range of -40℃ to 250℃, which can improve the high temperature aging resistance of robot skin. Silicone has high corrosion resistance and can resist the corrosion of most chemical substances, such as acids, alkalis, and salts, which can improve the corrosion resistance of robot skin. Silicone has good resilience, which can improve the compression resistance of robot skin.

[0025] The raw material composition for manufacturing robot skin according to the present invention includes thermoplastic elastomer (TPE). TPE has high elasticity and can be stretched to 6-8 times its own length, which can improve the skin's resistance to compression and stretching, and avoid cracking and softening caused by repeated compression and stretching. TPE has strong impact resistance, which can improve the skin's impact resistance. TPE has high abrasion resistance and is not easily worn, which can improve the skin's abrasion resistance and extend its service life. TPE has good processability, which can improve the skin's formability and is suitable for molding complex surfaces of robots. The use of TPE can enhance the skin's elasticity, extensibility and weather resistance.

[0026] The raw material composition for manufacturing robotic skin of the present invention includes modified diphenylmethane diisocyanate and polyether. The two are mixed to form polyurethane. Polyurethane has good water resistance and expands to a certain extent after absorbing water, which can improve the skin's ability to withstand changes in moisture. At the same time, it can reduce problems such as the decomposition of silicone when it comes into contact with water, improve the skin's water resistance, and extend the skin's lifespan. The polyurethane material itself has good transparency and good color retention and presentation, which can reduce skin discoloration and aging, and reduce problems that affect appearance and use.

[0027] This invention improves the overall performance of robot skin by combining silicone, thermoplastic elastomer, and polyurethane in a synergistic manner. The robot skin is less prone to aging, discoloration, and cracking, and has a long lifespan. It has a better appearance and performance, strong resistance to compression and stretching, and can withstand multiple compression and stretching cycles without cracking or softening, making it more durable. The surface of the robot skin is also smoother, with less friction and less stickiness (no noticeable stickiness).

[0028] The inventors discovered that due to the significant differences in properties among silicone, polyurethane, and thermoplastic elastomers, they are difficult to mix evenly in the skin, and the mixture tends to separate into layers. The raw material composition for manufacturing robotic skin in this invention includes modified diphenylmethane diisocyanate and polyether. The modified diphenylmethane diisocyanate has isocyanate groups (-NCO), which can react with substances containing hydroxyl groups (-OH). Silicone contains silanol groups (Si-OH), which can react with isocyanate groups to form crosslinks. In the system of modified diphenylmethane diisocyanate, polyether, and silicone, the modified diphenylmethane diisocyanate and polyether are mixed and polymerized to generate polyurethane. The resulting polyurethane can better bond with silicone, promoting the uniform dispersion and mutual bonding of silicone, polyurethane, and thermoplastic elastomer, and enabling full utilization of the polymer. This invention leverages the synergistic effect of silicone, thermoplastic elastomer, and polyurethane to improve the performance of robotic skin. The raw material composition for manufacturing robotic skin includes a silane coupling agent. This silane coupling agent typically contains a functional group (such as a silane group) capable of reacting with the silicone surface and a group (such as an amino or isocyanate group) capable of participating in the polyurethane reaction. Using the silane coupling agent as a bridge, reactive groups such as amino groups are introduced onto the silicone surface. These groups react with isocyanate groups and other groups in the polyurethane reaction, promoting deep cross-linking of silicone, polyurethane, and thermoplastic elastomer, further enhancing the synergistic effect of the composite. The reaction between the Si-OH groups on the silicone surface and the isocyanate groups in this invention results in a polymer with excellent strength, softness, and compression resistance, thus improving the skin's strength, softness, and compression resistance. If the silicone content of the present invention is less than 60 wt%, the cross-linking reaction ratio of silicone with modified diphenylmethane diisocyanate, polyether, silane coupling agent, etc. will be low, which will affect the mixing effect among silicone, thermoplastic elastomer and polyurethane generated by reaction, and affect the synergistic effect. In addition, if the silicone content is too low, the high temperature resistance, corrosion resistance and resilience will be adversely affected.

[0029] This invention does not limit the type of modification of diphenylmethane diisocyanate, as long as the isocyanate group can react with substances having hydroxyl (-OH) groups, such as the Si-OH groups on the surface of silicone. In some preferred embodiments, diphenylmethane diisocyanate modified with carbodiimide is used, which is more conducive to improving the elasticity and surface smoothness of the skin.

[0030] In some preferred embodiments, based on the total mass of the raw material composition, the content of the silicone is 60wt% to 77.5wt%, the content of the thermoplastic elastomer is 10wt% to 15wt%, the content of the modified diphenylmethane diisocyanate is 5wt% to 10wt%, the content of the polyether is 5wt% to 10wt%, the content of the silane coupling agent is 0.5wt% to 5wt%, the content of the catalyst is 1wt% to 2wt%, and the content of the vulcanizing agent is 1wt% to 5wt%. This preferred embodiment further promotes the cross-linking reaction between the Si-OH groups and isocyanate groups on the silicone surface, introducing reactive groups such as amino groups onto the silicone surface. This promotes deep cross-linking of silicone, polyurethane, and thermoplastic elastomer, facilitating uniform dispersion and mutual bonding of these substances. It fully leverages the synergistic effect of the composite of silicone, thermoplastic elastomer, and polyurethane, improving the strength, softness, and compression resistance of the robotic skin. TPE has a narrow temperature range (e.g., -70℃ to 90℃), and is particularly intolerant of high temperatures. Therefore, its usage should be limited, ideally using a relatively small proportion. A thermoplastic elastomer content of 10wt%–15wt% is more beneficial for improving the skin's resistance to high-temperature aging, as well as enhancing overall skin shapeability, elasticity, extensibility, and compression resistance. Since polyurethane has a certain degree of water absorption and swelling, the content of modified diphenylmethane diisocyanate should not exceed 10wt%, and the content of polyether should not exceed 10wt%. This limits the proportion of newly generated polyurethane, preventing deformation caused by water absorption. The silicone content should not exceed 77.5wt%. Higher contents of thermoplastic elastomers and reacted polyurethanes are more conducive to leveraging the properties of thermoplastic elastomers and polyurethanes, fully utilizing the synergistic effects of the silicone, thermoplastic elastomer, and polyurethane composite. The content of silicone is, for example, 60 wt%, 63 wt%, 67 wt%, 70 wt%, 73 wt%, 76 wt%, and 77.5 wt%; the content of thermoplastic elastomer is, for example, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, and 15 wt%; the content of modified diphenylmethane diisocyanate is, for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, and 10 wt%; the content of polyether is, for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, and 10 wt%; the content of silane coupling agent is, for example, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%; the content of catalyst is, for example, 1 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, and 2 wt%; and the content of vulcanizing agent is, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%.

[0031] In some preferred embodiments, the content of modified diphenylmethane diisocyanate by weight is 1.4 to 1.6% of the polyether content, preferably 1.5%. Increasing the proportion of modified diphenylmethane diisocyanate and the content of isocyanate groups is beneficial for promoting the cross-linking reaction between the Si-OH groups on the silicone surface and the isocyanate groups. This further promotes the uniform dispersion and mutual bonding of silicone, polyurethane, and thermoplastic elastomer, and fully leverages the synergistic effect of the composite of silicone, thermoplastic elastomer, and polyurethane to improve the performance of the robotic skin.

[0032] In some preferred embodiments, the silicone comprises liquid silicone, and the content of liquid silicone is 20 wt% or more based on the total mass of the silicone. This preferred embodiment is more conducive to improving the flexibility of the robotic skin. The liquid silicone has high reactivity, which enhances its reaction with thermoplastic elastomers and polyurethane generating raw materials, thereby improving the mixing effect among silicone, thermoplastic elastomers, and reacted polyurethane. Below this proportion, the potential cross-linking reaction with other substances (polyurethane reactive components such as MDI, polyether, and silane coupling agents) is low, and the mixing effect with PET and polyurethane components is poor. A more preferred proportion is 60 wt% to 80 wt%; controlling its proportion to avoid excessively soft skin, poor formability and morphological stability, excessively low hardness, and unstable color.

[0033] Liquid silicone can be selected as hydroxyl-terminated polydimethylsiloxane (PMDS), which is an organosilicon material polymerized from siloxane monomers with hydroxyl groups at both ends of its molecule. It is also known as hydroxyl silicone oil, 107 glue, etc., and has a density of approximately 0.85 g / cm³. 3 ~0.95g / cm 3 The kinematic viscosity at room temperature can be above 10 mPa·s, and the hydroxyl content (%) is 6-10. Suitable kinematic viscosity can be obtained by custom formulation from the manufacturer as needed. Preferably, the kinematic viscosity at room temperature is 1000 mPa·s-20000 mPa·s, 3000 mPa·s-10000 mPa·s, 4300 mPa·s-8000 mPa·s, and 5200 mPa·s-6500 mPa·s. By using liquid silicone with a suitable viscosity, its fluidity during stirring and mixing can be improved, thereby improving reactivity and the mixing effect between silicone, thermoplastic elastomer, and the reacted polyurethane. Its presence of Si-OH and hydroxyl groups gives it superior reactivity. For example, its surface has Si-OH groups, polyurethane reactions have -NCO groups, and the -NCO groups present when the Si-OH groups in silicone react with MDI and polyether in polyurethane reactions may also undergo partial cross-linking with the Si-OH groups and -NCO groups, thus facilitating possible cross-linking reactions with other substances (polyurethane reaction components such as MDI, polyether, and silane coupling agents).

[0034] Preferably, the silicone comprises solid silicone and liquid silicone, with the content of solid silicone ranging from 20 wt% to 80 wt% based on the total mass of the silicone. More preferably, the content of liquid silicone is 60 wt% to 80 wt%, and the content of solid silicone is 20 wt% to 40 wt%. Solid silicone offers better molding performance, higher hardness, and more stable color. This preferred configuration further enhances moldability, improves skin texture stability, and increases skin hardness. The combination of solid and liquid silicone provides the skin with better softness and hardness, improves its resistance to compression, facilitates coloring, and maintains color stability. Furthermore, centrifugation increases the distribution of substances along the centrifugal direction, enhancing the skin's internal and external texture.

[0035] For example, solid silicone is selected from Dow Corning (RBB-2881-80) in the United States. It is an organic silicone rubber composite material with a hardness of 80. It is specially used to produce molded products. It has good performance and good molding characteristics. It is semi-transparent in appearance, so it is easy to color and helps to form the most ideal skin tone.

[0036] In some preferred embodiments, the thermoplastic elastomer is selected from hydrogenated styrene-butadiene-hydrogenated styrene block copolymer (SEBS); the density may be 0.909 g / cm³. 3 Specific options include TSRC 6151 and Kuraray 4055. In this preferred embodiment, the thermoplastic elastomer includes a hydrogenated styrene-butadiene-hydrogenated styrene block copolymer, which helps to avoid skin cracking and softening caused by repeated extrusion and stretching, thus improving the skin's abrasion resistance and formability.

[0037] The silane coupling agent includes 3-aminopropyltriethoxysilane; the catalyst includes cyclohexylamine and / or tetrabutyltin; and the vulcanizing agent includes benzoyl peroxide. The silane coupling agent, including 3-aminopropyltriethoxysilane, is more conducive to promoting deep cross-linking of various substances such as silicone, polyurethane, and thermoplastic elastomers. The catalyst, including cyclohexylamine and / or tetrabutyltin, is more conducive to accelerating the polyurethane reaction process and promoting deep cross-linking of various substances such as silicone, polyurethane, and thermoplastic elastomers. Cyclohexylamine contains a -NH2 reactive group, which is also conducive to deep cross-linking of various substances. The vulcanizing agent, including benzoyl peroxide, is more conducive to improving the skin's antioxidant properties and promoting vulcanization.

[0038] In some preferred embodiments, the raw material composition further includes graphene oxide. Graphene oxide has a high elastic modulus (≈1 TPa). In this preferred embodiment, the inclusion of graphene oxide in the raw material composition is more conducive to improving skin abrasion resistance, increasing skin strength, prolonging skin lifespan, improving skin's resistance to ultraviolet radiation, preventing color changes and high-temperature aging, improving skin's antistatic properties, improving skin's hydrophobicity (waterproofness) and barrier properties, improving skin's weather resistance, improving skin's electrical and thermal conductivity, and enabling the skin to have sensing properties, perceiving and responding to factors such as pressure, temperature, humidity, and odor.

[0039] Graphene oxide monolayers have randomly distributed hydroxyl and epoxy groups, while carboxyl and carbonyl groups are introduced at the edges. The surface of graphene oxide contains functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy groups. Firstly, graphene oxide combines with the surface hydroxyl (-OH) groups of silicone. The surface hydroxyl groups of graphene oxide and silicone interact through esterification or other covalent reactions. For example, the -COOH groups of graphene oxide react with Si-OH to form a mixture. Graphene oxide can better chemically and physically bond with silicone and thermoplastic elastomers. Secondly, silane coupling agents firmly bond graphene oxide to the surface of silicone through covalent bonds. The end groups (such as amino groups) of silane coupling agents react with the oxide groups of graphene, further enhancing the interaction between graphene and silicone. Based on the above two aspects, graphene is oxidized to form graphene oxide (GO) and functional groups (such as carboxyl groups) are introduced. Through esterification reactions, silane coupling agents, and other methods, the combination of graphene oxide and silicone, thermoplastic elastomers is promoted. Graphene is closely combined with silicone, thermoplastic elastomers, and polyurethane and a certain cross-linking reaction occurs. Graphene is better integrated into the system and is less prone to problems such as graphene oxide agglomeration and uneven distribution. This is more conducive to promoting the uniform dispersion and mutual combination of graphene, silicone, thermoplastic elastomers, and polyurethane, reducing delamination, and giving full play to the synergistic effect of the graphene, silicone, thermoplastic elastomers, and polyurethane composite to improve skin performance.

[0040] The actual cross-linking reaction process is usually extremely complex and difficult to determine accurately. The above analysis explains to some extent why the addition of substances affects the mixture system of multiple substances, but it does not mean that the reaction will necessarily be based on the above reasons. From the overall performance improvement of the reaction system, it can also be seen that the addition of the above substances has a good promoting effect.

[0041] Preferably, the content of graphene oxide is 0.01 wt% to 2 wt% based on the total mass of the raw material composition. This preferred embodiment helps to avoid significant delamination between graphene oxide, silicone, thermoplastic elastomer, and polyurethane, fully leveraging the synergistic effect of the graphene oxide, silicone, thermoplastic elastomer, and polyurethane composite to improve skin performance. The graphene oxide content can be, for example, 0.01 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1.2 wt%, 1.5 wt%, 1.7 wt%, and 2 wt%.

[0042] Secondly, the present invention provides a method for manufacturing robot skin, which involves mixing and stirring the raw material composition for manufacturing robot skin as described in the first aspect, molding, and centrifugally rotating to obtain the robot skin.

[0043] The manufacturing method of the robot skin of the present invention involves a mixing and stirring process in which polyurethane is formed. Various substances such as silicone, polyurethane, thermoplastic elastomer, silane coupling agent, and graphene oxide begin to cross-link with each other, and the material is in an emulsion state. When centrifuged, the material is in a semi-solid state. Centrifugal rotation, on the one hand, eliminates the small amount of air bubbles generated by the polyurethane reaction, making the skin surface smoother and the strength more uniform; on the other hand, within a certain thickness range, the uniformity of the same layer is improved, which can enhance the skin's homogeneity, vertical layering, and mechanical balance (where vertical layering is relative to the skin and located in the direction parallel to centrifugation). Silicone has a high density, while polyurethane and thermoplastic elastomers are light. Through centrifugation, the denser silicone portion and the lighter polyurethane and thermoplastic elastomer portion are appropriately layered, forming a layered structure where the silicone content on the skin surface is slightly lower than the silicone content inside the skin, and the polyurethane and thermoplastic elastomer content on the skin surface is slightly higher than the polyurethane and thermoplastic elastomer content inside the skin. Thermoplastic elastomers have good elasticity, tensile strength, and impact resistance, while polyurethane has good color retention. By bringing thermoplastic elastomers and polyurethane relatively closer to the skin surface, it is more conducive to improving the skin's elasticity, tensile strength, impact resistance, strength uniformity, and surface smoothness, and improving skin tone.

[0044] It is understandable that raw materials such as silicone will introduce water. During the mixing and stirring process in the preparation of the robotic skin, a polyurethane reaction is promoted, eliminating the need for additional water. This invention does not limit the molding method; for example, it can be extrusion molding, injection molding, or casting molding. A casting molding manufacturing method, for example, involves mixing and stirring, casting, centrifugal rotation, and demolding to obtain the robotic skin.

[0045] In some preferred embodiments, the centrifugal rotation conditions include: a rotational speed of 100 rpm to 3000 rpm, a time of 3 min to 5 min, and a pressure of 0.01 bar to 0.2 bar. This preferred embodiment is more conducive to improving the uniformity of skin layers, vertical hierarchical arrangement, and mechanical balance, thereby improving skin elasticity, tensile strength, impact resistance, strength uniformity, and surface smoothness, and improving skin tone. The pressure refers to absolute pressure.

[0046] In some preferred embodiments, the mixing and stirring conditions include: a rotation speed of 50 rpm to 300 rpm, a temperature of 80°C to 300°C, and a time of 5 min to 30 min. This preferred approach is more conducive to promoting the polyurethane reaction process, facilitating the deep cross-linking of various substances such as silicone, polyurethane, thermoplastic elastomers, silane coupling agents, and graphene oxide, thereby improving the overall skin performance.

[0047] Thirdly, the present invention provides a robotic skin, which is manufactured by the robotic skin manufacturing method described in the second aspect.

[0048] The robot skin of this invention is made of silicone, thermoplastic elastomer, and polyurethane, which are uniformly dispersed and combined with each other. It fully utilizes the synergistic effect of silicone, thermoplastic elastomer, and polyurethane composite. The robot skin is not easy to age or discolor, has good wear resistance, long service life, strong resistance to compression and stretching, and will not crack or soften even after many compression and stretching cycles.

[0049] The robot skin of this invention has a Young's modulus of 0.2 MPa-0.5 MPa, suitable skin hardness, a surface friction coefficient of 0.5-0.8, a smooth skin surface, and low friction.

[0050] The following detailed description of examples of the present invention is exemplary and is only used to explain the present invention, and should not be construed as limiting the present invention. The raw materials used are as follows: liquid silica gel (hydroxyl-terminated polydimethylsiloxane) purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd.; solid silica gel purchased from Dow Corning (RBB-2881-80); hydrogenated styrene-butadiene-hydrogenated styrene block copolymer SEBS purchased from TSRC Corporation (6151); modified diphenylmethane diisocyanate purchased from BASF (Lupranate MM103c); polyether purchased from Dow (VORANOL 2000LM); silane coupling agent 3-aminopropyltriethoxysilane; catalyst cyclohexylamine; catalyst tetrabutyltin; benzoyl peroxide vulcanizing agent can be selected from commercially available related products; and graphene oxide is preferably a commercially available product with functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy groups on its surface.

[0051] Example 1

[0052] A raw material composition for manufacturing robotic skin includes silicone, hydrogenated styrene-butadiene-hydrogenated styrene block copolymer (thermoplastic elastomer), modified diphenylmethane diisocyanate, polyether, 3-aminopropyltriethoxysilane (silane coupling agent), tetrabutyltin (catalyst), cyclohexylamine (catalyst), benzoyl peroxide (vulcanizing agent), and graphene oxide. The silicone content is 72 wt% based on the total mass of the raw material composition. The content is 12wt%, the content of modified diphenylmethane diisocyanate is 6wt%, the content of polyether is 6wt%, the content of 3-aminopropyltriethoxysilane is 1wt%, the content of tetrabutyltin is 0.5wt%, the content of cyclohexylamine is 0.5wt%, the content of benzoyl peroxide is 1wt%, and the content of graphene oxide is 1wt%. The silica gel includes liquid silica gel and solid silica gel. Based on the total mass of silica gel, the content of liquid silica gel is 70wt%, and the content of solid silica gel is 30wt%.

[0053] A method for manufacturing robotic skin involves mixing and stirring the aforementioned raw material composition for manufacturing robotic skin, pouring into a mold, centrifuging and rotating, and demolding to obtain robotic skin. The mixing and stirring speed is 150 rpm, the temperature is 200°C, and the time is 20 min. The centrifugation speed is 1500 rpm, the time is 5 min, and the pressure is 0.1 bar.

[0054] Example 2

[0055] The raw material composition is the same as that in Example 1, except that the content of 3-aminopropyltriethoxysilane is 0.3 wt% and the content of silica gel is 72.7 wt% based on the total mass of the raw material composition.

[0056] Example 3

[0057] The raw material composition is the same as in Example 1, except that the content of liquid silicone is 84 wt% and the content of solid silicone is 16 wt% based on the total mass of silicone.

[0058] Example 4

[0059] The raw material composition is the same as in Example 1, except that the content of liquid silicone is 50 wt% and the content of solid silicone is 50 wt% based on the total mass of silicone.

[0060] Example 5

[0061] The raw material composition is the same as in Example 1, except that tetrabutyltin is used instead of cyclohexylamine, and the content of tetrabutyltin is 1 wt% based on the total mass of the raw material composition. 。

[0062] Example 6

[0063] The raw material composition of Example 1 is the same as that of Example 1, except that it does not include graphene oxide and the content of silica gel is 73 wt% based on the total mass of the raw material composition.

[0064] Example 7

[0065] The method for manufacturing robotic skin is similar to that in Example 1, except that the centrifugal rotation speed is 30 rpm and the time is 3 min.

[0066] Example 8

[0067] The method for manufacturing robotic skin according to Example 1 differs in that centrifugal rotation is not performed.

[0068] Example 9

[0069] Referring to the raw material composition of Example 1, the difference is that, based on the total mass of the raw material composition, the content of the silicone is 71.5 wt%, the content of the modified diphenylmethane diisocyanate is 7.5 wt%, and the content of the polyether is 5 wt%.

[0070] Comparative Example 1

[0071] The raw material composition of Example 1 is different in that it does not include modified diphenylmethane diisocyanate and polyether, but directly uses thermoplastic elastomer instead. The content of silicone is 70 wt% and the content of thermoplastic elastomer is 26 wt% based on the total mass of the raw material composition.

[0072] Comparative Example 2

[0073] The raw material composition is the same as that in Example 1, except that the raw material composition does not include 3-aminopropyltriethoxysilane, and the content of the silica gel is 73 wt% based on the total mass of the raw material composition.

[0074] Test case

[0075] The Young's modulus, surface friction coefficient, tensile fatigue resistance, color stability, and aging resistance of the robotic skins prepared in Examples 1-9 and Comparative Examples 1-2 were characterized. The Young's modulus was tested according to GB / T 1447, reflecting the solid material's resistance to deformation and its hardness. The surface friction coefficient was tested according to ASTM D2000, the tensile fatigue resistance according to GB / T 33429-2016, and the aging resistance according to GB / T 16422.3. Color stability was obtained by placing the robotic skin under natural indoor light. ΔE represents the color difference between the skin color after a period of time following demolding and the original skin color. A larger ΔE value indicates a larger color difference and poorer color stability. The characterization results for Young's modulus are shown in Table 1, the surface friction coefficient in Table 2, the tensile fatigue resistance in Table 3, the color stability in Table 4, and the aging resistance in Table 5. A photograph of the appearance of the robotic skin from Example 1 one year after demolding is shown below. Figure 1 For comparison, see the image of the robot's skin after molding. Figure 2 , Figure 1 The skin shows no obvious signs of aging. Figure 2 The skin shows obvious signs of aging.

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080]

[0081] Table 3

[0082]

[0083] Table 4

[0084]

[0085] Table 5

[0086]

[0087]

[0088] Comparative Examples 1 and 2 show that the raw material composition includes polyurethane, which can improve the tensile fatigue resistance, color stability, and aging resistance of the robotic skin, giving the skin a suitable softness and hardness, inhibiting the change of Young's modulus over time, and reducing the coefficient of friction of the skin surface. Comparative Examples 2 and 3 show that the raw material composition includes a silane coupling agent, which can improve the tensile fatigue resistance, color stability, and aging resistance of the robotic skin, giving the skin a suitable softness and hardness, inhibiting the change of Young's modulus over time, and reducing the coefficient of friction of the skin surface.

[0089] Compared with Examples 1 and 2, the content of silane coupling agent, based on the total mass of the raw material composition, is 0.5 wt% to 5 wt%, which is more conducive to improving the skin's tensile fatigue resistance, color stability, and aging resistance, inhibiting the change of Young's modulus over time, and reducing the skin's surface friction coefficient. Compared with Examples 1 and 3, the content of liquid silicone is not higher than 80 wt% and the content of solid silicone is not lower than 20 wt%, based on the total mass of silicone, which is more conducive to improving the skin's tensile fatigue resistance, color stability, and aging resistance, giving the skin suitable softness and hardness, inhibiting the change of Young's modulus over time, and reducing the skin's surface friction coefficient. Compared with Examples 1 and 4, the content of liquid silicone is not lower than 60 wt% and the content of solid silicone is not higher than 40 wt%, based on the total mass of silicone, which is more conducive to improving the robot skin's tensile fatigue resistance, color stability, and aging resistance, giving the skin suitable softness and hardness, inhibiting the change of Young's modulus over time, and reducing the skin's surface friction coefficient. Compared with Examples 1 and 5, the catalyst includes cyclohexylamine, and a composite catalyst is used. The process further enhances the robot skin's tensile fatigue resistance, color stability, and aging resistance, inhibits changes in Young's modulus over time, and reduces the skin's surface friction coefficient. Comparative Examples 1 and 6, where the raw material composition includes graphene oxide, further improves the robot skin's tensile fatigue resistance, color stability, and aging resistance, giving the skin suitable softness and hardness, inhibiting changes in Young's modulus over time, and reducing the skin's surface friction coefficient. Comparative Examples 1, 7, and 8, centrifugal rotation further enhances the robot skin's tensile fatigue resistance, color stability, and aging resistance, as well as reduces the skin's surface friction coefficient. The centrifugal rotation speed is 100 rpm to 3000 rpm, further enhancing the robot skin's tensile fatigue resistance, color stability, and aging resistance, and reducing the skin's surface friction coefficient. Comparative Examples 1 and 9, increasing the modified diphenylmethane diisocyanate content further enhances the robot skin's tensile fatigue resistance, color stability, and aging resistance, inhibits changes in Young's modulus over time, and reduces the skin's surface friction coefficient.

[0090] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A raw material composition for manufacturing robotic skin, characterized in that, The composition includes silicone, thermoplastic elastomer, modified diphenylmethane diisocyanate, polyether, silane coupling agent, catalyst, and vulcanizing agent. Based on the total mass of the raw material composition, the silicone content is 60wt%~77.5wt%, the thermoplastic elastomer content is 10wt%~15wt%, the modified diphenylmethane diisocyanate content is 5wt%~10wt%, the polyether content is 5wt%~10wt%, the silane coupling agent content is 0.5wt%~5wt%, the catalyst content is 1wt%~2wt%, and the vulcanizing agent content is 1wt%~5wt%. The silica gel comprises solid silica gel and liquid silica gel, wherein, based on the total mass of the silica gel, the content of liquid silica gel is 60wt%~80wt% and the content of solid silica gel is 20wt%~40wt%. The content of the modified diphenylmethane diisocyanate is: the content of the polyether is 1.4~1.6; The modified diphenylmethane diisocyanate is a carbodiimide-modified diphenylmethane diisocyanate.

2. The raw material composition according to claim 1, characterized in that, The thermoplastic elastomer comprises a hydrogenated styrene-butadiene-hydrogenated styrene block copolymer; the silane coupling agent comprises 3-aminopropyltriethoxysilane; the catalyst comprises cyclohexylamine and / or tetrabutyltin; and the vulcanizing agent comprises benzoyl peroxide.

3. The raw material composition according to claim 1, characterized in that, The raw material composition also includes graphene oxide.

4. The raw material composition according to claim 3, characterized in that, The content of graphene oxide is 0.01wt% to 2wt% based on the total mass of the raw material composition.

5. A method for manufacturing robotic skin, characterized in that, The raw material composition for manufacturing robotic skin according to any one of claims 1 to 4 is mixed and stirred, shaped, and centrifuged to obtain the robotic skin; the centrifugal rotation conditions include: a rotation speed of 100 rpm to 3000 rpm, a time of 3 min to 5 min, and a vacuum pressure of 0.01 bar to 0.2 bar; the mixing and stirring conditions include: a rotation speed of 50 rpm to 300 rpm, a temperature of 80℃ to 300℃, and a time of 5 min to 30 min.

6. A robotic skin, characterized in that, It is manufactured by the method for manufacturing robotic skin as described in claim 5.

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