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

Abstract

The invention 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 skin. The raw material composition for manufacturing the robot skin comprises silica gel, a thermoplastic elastomer, modified diphenylmethane diisocyanate, polyether, a silane coupling agent, a catalyst and a vulcanizing agent, the content of the silica gel is 60 wt% or above based on the total mass of the raw material composition, and the manufactured robot skin is not prone to aging and discoloring, long in service life and high in safety. And the extrusion and stretching resistance is high, and cracking and softening cannot be caused even if extrusion and stretching are performed for many times.

Description

Technical Field

[0001] The present invention belongs to the field of robot skin. Specifically, it relates to a raw material composition for manufacturing robot skin, a skin manufacturing method, and the skin. Background Art

[0002] Currently, more and more robots are being put into use. With the explosion of AI intelligence, humanoid robots will enter human society more in the future. It is said that there will be one billion robots in the next ten years, and these robots will mainly serve households. Therefore, it is proposed that robots must be humanoid first to be more acceptable and popular. Currently, humanoid robots use many material methods. Among them, the one that is closest to the human appearance is cast from silicone according to the human model, and its skin is similar to that of humans, almost reaching the point of being indistinguishable from the real thing. Currently, the quality is relatively good, but there are still the following defects: it is easy to age, discolor, crack, and has a short life cycle, affecting the appearance and use effect; its anti-extrusion and stretching ability is poor, and cracking and softening will occur after multiple extrusion and stretching times; the smoothness of the skin surface is low, the friction is large, the viscosity is large, and it has no sensing function, and it cannot sense and respond to factors such as pressure, temperature, humidity, and smell.

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

[0004] The purpose of the present invention is to overcome the defects of existing robot skin, such as being easy to age, discolor, having a short life cycle, poor anti-extrusion and stretching ability, easy cracking and softening after multiple extrusion and stretching times, low smoothness of the skin surface, large friction, large viscosity, and no sensing function. The present invention provides a raw material composition for manufacturing robot skin, a skin manufacturing method, and the skin. The manufactured robot skin is not easy to age, discolor, has a long life, has strong anti-extrusion and stretching ability, and will not cause cracking and softening even after multiple extrusion and stretching times. The skin surface is smoother and has a certain sensing ability.

[0005] To achieve the above purpose, in the first aspect, the present invention provides a raw material composition for manufacturing robot skin, which 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 content of the silicone is more than 60wt%.

[0006] In some preferred embodiments, based on the total mass of the raw material composition, the content of the silica gel 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 silica gel includes liquid silica gel, and based on the total mass of the silica gel, the content of the liquid silica gel is more than 20 wt%.

[0008] Preferably, the silica gel includes solid silica gel and liquid silica gel. Based on the total mass of the silica gel, the content of the liquid silica gel is 60 wt% to 80 wt%, and the content of the solid silica gel is 20 wt% to 40 wt%.

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

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

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

[0012] In a second aspect, the present invention provides a method for manufacturing a robot skin. The raw material composition for manufacturing the robot skin described in the first aspect is used for mixing, stirring, molding, and centrifugal rotation to obtain the robot skin.

[0013] In some preferred embodiments, the conditions for the centrifugal rotation 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 conditions for the mixing and stirring 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] In a third aspect, the present invention provides a robot skin, which is manufactured by the method for manufacturing a robot skin described in the second aspect.

[0015] Since there are still major problems in preparing the skin using silicone and thermoplastic elastomer alone or in combination, and the physical and chemical properties of the two are quite different, the mixing effect is not good, and the skin performance cannot be effectively improved. In the present invention, the combination of silicone, thermoplastic elastomer, and polyurethane is compounded and synergistic with each other, which can improve the comprehensive performance of the robot skin. The robot skin is not easy to age, discolor, crack, and has a long lifespan. The robot skin has a better appearance and usage effect. The robot skin has strong resistance to extrusion and stretching, and it will not crack or soften even after multiple extrusion and stretching operations, making it more durable; the surface of the robot skin is smoother, with less friction and less stickiness (no obvious sticky feeling).

[0016] Due to the large performance differences among silicone, polyurethane, and thermoplastic elastomer, it is not easy to mix them evenly in the skin, and the mixture is prone to layering. To improve the mixing of the three, the raw material composition for manufacturing the robot skin in the present invention includes modified diphenylmethane diisocyanate and polyether. Modified diphenylmethane diisocyanate and polyether are the main raw materials required for the polyurethane reaction, and they are added as raw material components. Modified diphenylmethane diisocyanate has an isocyanate group (-NCO), and the isocyanate group can react with substances having a hydroxyl group (-OH). The silicone surface contains silanol groups (Si-OH), and the Si-OH groups on the silicone surface can react with the isocyanate group to undergo cross-linking. In the system of modified diphenylmethane diisocyanate, polyether, and silicone, after the modified diphenylmethane diisocyanate and polyether are mixed, they undergo a polymerization reaction to form polyurethane. The generated polyurethane can better combine with silicone at the same time, which can promote the uniform dispersion and mutual combination of silicone, polyurethane, and thermoplastic elastomer, and can fully exert the compound and synergistic effect of the combination of silicone, thermoplastic elastomer, and polyurethane to improve the performance of the robot skin; the raw material composition for manufacturing the robot skin in the present invention includes a silane coupling agent. The silane coupling agent usually contains a functional group capable of reacting with the silicone surface (such as a silyl group) and a group capable of participating in the polyurethane reaction (such as an amino group or an isocyanate group). Using the silane coupling agent as a bridge, reactive groups such as amino groups are introduced on the silicone surface. By reacting these groups with groups such as the isocyanate group in the polyurethane reaction, it can promote the formation of deep cross-linking of multiple substances such as silicone, polyurethane, and thermoplastic elastomer, and further exert the compound and synergistic effect of the combination of silicone, thermoplastic elastomer, and polyurethane.

[0017] Manufacturing method of robot skin, mixing process, reaction to form polyurethane, and various substances such as silicone, polyurethane, thermoplastic elastomer, and silane coupling agent start to crosslink with each other. The material is in a emulsion state, and centrifugal rotation treatment is added. During centrifugal rotation, the material is in a semi-solidified state. Centrifugal rotation, on the one hand, eliminates a small amount of 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 improve the uniformity of the skin in the same layer, the vertical layer property, and the mechanical balanced arrangement (where the vertical position is relative to the skin and is in the parallel direction of the centrifugation); silicone has a high density, while polyurethane and thermoplastic elastomer are light. Through centrifugation, the part with a high density of silicone is moderately stratified from the part with a light density of polyurethane and thermoplastic elastomer, forming a hierarchical structure where the silicone content on the skin surface is slightly lower than that inside the skin, and the polyurethane and thermoplastic elastomer content on the skin surface is slightly higher than that inside the skin. The thermoplastic elastomer has good elasticity, good tensile resistance, and good impact resistance, and polyurethane has good color retention. By having the thermoplastic elastomer and polyurethane relatively closer to the skin surface, it is more conducive to improving the elasticity, tensile resistance, impact resistance, strength uniformity of the skin, and the smoothness of the skin surface, and improving the color of the skin. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use 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 therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0019] Figure 1 Appearance photo of the robot skin 1 year after demolding in Example 1.

[0020] Figure 2 Appearance photo of the robot skin after demolding in Comparative Example 1. Detailed Embodiments

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] The inventors of the present invention have found through research that existing robot skins are prone to aging, discoloration, short lifespan, poor anti-extrusion and stretching ability, and are likely to crack and soften after multiple extrusion and stretching operations. The skin surface has low smoothness, high friction, high viscosity, and no sensing function.

[0023] In view of this, on the one hand, the present invention provides a raw material composition for manufacturing a robot skin, which includes silica gel, thermoplastic elastomer, modified diphenylmethane diisocyanate, polyether, silane coupling agent, catalyst, and vulcanizing agent. Based on the total mass of the raw material composition, the content of silica gel is more than 60wt%.

[0024] The raw material composition for manufacturing a robot skin of the present invention includes silica gel with a content of more than 60wt%. Taking silica gel as the main component as the matrix, silica gel is close to human skin, has a soft touch, can improve the softness of the robot skin, is heat-resistant, has good stability in a wide temperature range from -40°C to 250°C, can improve the high-temperature aging resistance of the robot skin, has high corrosion resistance, can resist the corrosion of most chemical substances such as acids, alkalis, salts, etc., can improve the corrosion resistance of the robot skin, has good resilience, and can improve the anti-extrusion ability of the robot skin.

[0025] The raw material composition for manufacturing a robot skin of 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 anti-extrusion and stretching ability of the skin and avoid cracking and softening caused by multiple extrusion and stretching operations; TPE has strong impact resistance, can improve the impact resistance of the skin, has high wear resistance and is not easily worn, can improve the wear resistance of the skin, and the service life of the skin is longer; TPE has good processability, improves the formability of the skin, and is suitable for the molding of complex surfaces of robots; the use of TPE can enhance the elasticity, ductility and weather resistance of the skin.

[0026] The raw material composition for manufacturing a robot skin of the present invention includes modified diphenylmethane diisocyanate and polyether. After mixing, they form polyurethane. Polyurethane has good water resistance and expands slightly after absorbing water, which can improve the skin's tolerance to water changes, reduce problems such as the decomposition of silica gel when exposed to water, improve the water resistance of the skin, and extend the skin's lifespan; the polyurethane material itself has good transparency, retains and presents color effects well, can reduce problems such as skin discoloration and aging that affect the appearance and use effect.

[0027] Through the compounding and mutual cooperation of silicone, thermoplastic elastomer, and polyurethane, the comprehensive performance of the robot skin can be improved. The robot skin is not easily aged, discolored, cracked, and has a long service life. The robot skin has a better appearance and usage effect. The robot skin has strong resistance to extrusion and stretching, and it will not crack or soften even after multiple extrusion and stretching operations, making it more durable. The surface of the robot skin is smoother, with less friction and less stickiness (no obvious sticky feeling).

[0028] The inventors found that due to the large differences in the properties of silicone, polyurethane, and thermoplastic elastomer, it is difficult to mix them evenly in the skin, and the mixture is prone to delamination. The raw material composition for manufacturing the robot skin of the present invention includes modified diphenylmethane diisocyanate and polyether. The modified diphenylmethane diisocyanate has an isocyanate group (-NCO), and the isocyanate group can react with substances having a hydroxyl group (-OH). The silicone surface contains silanol groups (Si-OH), and the Si-OH groups on the silicone surface can react with the isocyanate group to undergo cross-linking. In the system of modified diphenylmethane diisocyanate, polyether, and silicone, after the modified diphenylmethane diisocyanate and polyether are mixed, a polymerization reaction occurs to form polyurethane. The generated polyurethane can better combine with silicone, promote the uniform dispersion and mutual combination of silicone, polyurethane, and thermoplastic elastomer, and can fully exert the compounding and mutual cooperation effects of silicone, thermoplastic elastomer, and polyurethane, thereby improving the performance of the robot skin. The raw material composition for manufacturing the robot skin of the present invention includes a silane coupling agent. The silane coupling agent usually contains a functional group (such as a silane group) that can react with the silicone surface and a group (such as an amino group or an isocyanate group) that can participate in the reaction with polyurethane. Using the silane coupling agent as a bridge, reactive groups such as amino groups are introduced onto the silicone surface, and through the reaction of these groups with groups such as the isocyanate group in the polyurethane reaction, it can promote the formation of deep cross-linking of multiple substances such as silicone, polyurethane, and thermoplastic elastomer, and further exert the compounding and mutual cooperation effects of silicone, thermoplastic elastomer, and polyurethane. The reaction of the Si-OH groups on the silicone surface of the present invention with the isocyanate group results in a polymer with good strength, softness, and extrusion resistance, which can improve the strength, softness, and extrusion resistance of the skin. If the content of silicone in the present invention is less than 60 wt%, the cross-linking reaction ratio between silicone and modified diphenylmethane diisocyanate, polyether, silane coupling agent, etc. is low, which affects the mixing effect among silicone, thermoplastic elastomer, and the reaction to form polyurethane, and affects the exertion of the synergistic effect. Moreover, if the silicone content is too low, the high temperature resistance, corrosion resistance, and resilience will all be adversely affected.

[0029] The modification type of the modified diphenylmethane diisocyanate of the present invention is not limited, as long as the isocyanate group can react with a substance having a hydroxyl group (-OH) and react with the Si-OH group on the surface of the silica gel. In some preferred embodiments, the diphenylmethane diisocyanate modified with carbodiimide 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 silica gel is 60 wt% - 77.5 wt%, the content of thermoplastic elastomer is 10 wt% - 15 wt%, the content of modified diphenylmethane diisocyanate is 5 wt% - 10 wt%, the content of polyether is 5 wt% - 10 wt%, the content of silane coupling agent is 0.5 wt% - 5 wt%, the content of catalyst is 1 wt% - 2 wt%, and the content of vulcanizing agent is 1 wt% - 5 wt%. Under this preferred scheme, it can further promote the reaction between Si-OH groups on the silica gel surface and isocyanate groups to occur cross-linking, introduce reactive groups such as amino groups on the silica gel surface, promote the formation of deep cross-linking of multiple substances of silica gel, polyurethane, and thermoplastic elastomer, and is more conducive to the uniform dispersion and mutual combination of silica gel, polyurethane, and thermoplastic elastomer, giving full play to the synergistic effect of the three composites of silica gel, thermoplastic elastomer, and polyurethane, and improving the strength, softness, and extrusion resistance of the robot skin. The temperature resistance range of TPE is relatively narrow (such as -70°C to 90°C), especially not resistant to high temperatures, so its dosage should be limited. That is, using a relatively small proportion, the content of thermoplastic elastomer is 10 wt% - 15 wt%, which is more conducive to improving the high-temperature aging resistance of the skin, and at the same time is conducive to improving the overall formability of the skin, enhancing the elasticity, ductility, and extrusion resistance of the skin; due to the certain water absorption and swelling of polyurethane, the content of modified diphenylmethane diisocyanate is not higher than 10 wt%, and the content of polyether is not higher than 10 wt%, so as to limit the proportion of newly formed polyurethane not to be too high, which is more conducive to avoiding deformation caused by water absorption of the skin; the content of silica gel is not higher than 77.5 wt%, and the content of thermoplastic elastomer and reaction-generated polyurethane is relatively high, which is more conducive to giving full play to the characteristics of thermoplastic elastomer and polyurethane, and giving full play to the synergistic effect of the three composites of silica gel, thermoplastic elastomer, and polyurethane. The content of silica gel 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, by mass, the content ratio of the modified diphenylmethane diisocyanate to the polyether is 1.4 to 1.6, preferably 1.5. Increasing the usage ratio of the modified diphenylmethane diisocyanate and the content of isocyanate groups is beneficial to promoting the reaction between the Si-OH groups on the silica gel surface and the isocyanate groups to undergo cross-linking and other reactions, which can further promote the uniform dispersion and mutual combination of silica gel, polyurethane, and thermoplastic elastomer, and can give full play to the synergistic effect of the three composites of silica gel, thermoplastic elastomer, and polyurethane, improving the performance of the robot skin.

[0032] In some preferred embodiments, the silica gel includes liquid silica gel. By the total mass of the silica gel, the content of the liquid silica gel is more than 20 wt%. Under this preferred scheme, it is more conducive to improving the flexibility of the robot skin. The liquid silica gel has high reactivity to promote the reaction with the raw materials of thermoplastic elastomer and polyurethane, thereby improving the mixing effect among silica gel, thermoplastic elastomer, and the reaction-generated polyurethane. If the proportion is lower than the above, the proportion of possible cross-linking reactions with other substances (such as MDI, polyether, silane coupling agent, etc. in the polyurethane reaction components) is low, and the mixing effect with PET, polyurethane components, etc. is not good. More preferably, it is 60 wt% - 80 wt%. Controlling its proportion not to be too high can reduce problems such as overly soft skin, poor formability, poor morphological stability, too low hardness, and unstable color.

[0033] The liquid silica gel can be selected as hydroxy-terminated polydimethylsiloxane (PMDS), which is an organosilicon material polymerized from siloxane monomers and has hydroxyl groups at both ends of its molecules. It is also simply called hydroxy silicone oil, 107 glue, etc., with a density of about 0.85 g / cm 3 ~0.95 g / cm 3 , and the kinematic viscosity at room temperature can be 10 mPa·s or more. The hydroxyl content (%): 6 - 10. The appropriate kinematic viscosity can be customized from the manufacturer according to needs; 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, 5200 mPa·s - 6500 mPa·s. By using liquid silica gel with an appropriate viscosity, its fluidity during stirring and mixing can be improved, thereby improving the reactivity and the mixing effect among silica gel, thermoplastic elastomer, and the reaction-generated polyurethane. It has Si-OH, hydroxyl groups, etc., making it have better reactivity. For example, there are Si-OH groups on its surface, -NCO groups in the polyurethane reaction, and when the Si-OH groups in the silica gel react with MDI and polyether in the polyurethane reaction, there are -NCO groups, and partial cross-linking may also occur between the Si-OH groups and the -NCO groups, thus facilitating possible cross-linking reactions with other substances (such as MDI, polyether, silane coupling agent, etc. in the polyurethane reaction components).

[0034] Preferably, the silicone includes solid silicone and liquid silicone. Based on the total mass of the silicone, the content of the solid silicone is 20wt% - 80wt%. Preferably, the content of the liquid silicone is 60wt% - 80wt%, and the content of the solid silicone is 20wt% - 40wt%. The solid silicone has better forming effect, higher hardness and relatively stable color. In this preferred scheme, it is more conducive to improving the formability, enhancing the stability of the skin shape, increasing the hardness of the skin. The combination of solid silicone and liquid silicone makes the skin have better softness and hardness, improves the extrusion resistance of the skin, makes the skin easy to be colored and maintains color stability. At the same time, after centrifugal treatment, the distribution of various substances along the centrifugal direction can be increased, and the internal and external layering of the skin can be enhanced.

[0035] For example: The solid silicone is selected from Dow Corning (RBB - 2881 - 80) in the United States. It is a silicone rubber composite material with a hardness of 80, which is specifically used for producing molded products. It has good effects and the characteristics of good forming. Its appearance is semi - transparent, so it is easy to be colored and helps the skin to form the most ideal color tone.

[0036] In some preferred embodiments, the thermoplastic elastomer is selected from hydrogenated styrene - butadiene - hydrogenated styrene block copolymer (SEBS); the density can be 0.909g / cm 3 Specifically, TAIPOL 6151, KURARAY 4055, etc. can be selected. In this preferred scheme, the thermoplastic elastomer includes hydrogenated styrene - butadiene - hydrogenated styrene block copolymer, which is more conducive to avoiding skin cracking and softening caused by multiple extrusion and stretching times, and improving the wear resistance and formability of the skin.

[0037] The silane coupling agent includes 3 - aminopropyltriethoxysilane; the catalyst includes cyclohexylamine and / or tetrabutyltin; the vulcanizing agent includes dibenzoyl peroxide. The silane coupling agent including 3 - aminopropyltriethoxysilane is more conducive to promoting the deep cross - linking of multiple substances such as silicone, polyurethane and thermoplastic elastomer; the catalyst including cyclohexylamine and / or tetrabutyltin is more conducive to accelerating the polyurethane reaction process and promoting the deep cross - linking of multiple substances such as silicone, polyurethane and thermoplastic elastomer. Cyclohexylamine contains - NH 2 reaction groups, which is also beneficial to the deep cross - linking of multiple substances; the vulcanizing agent including dibenzoyl peroxide is more conducive to improving the antioxidant property of the skin and promoting vulcanization.

[0038] In some preferred embodiments, the raw material composition also includes graphene oxide. Graphene oxide has a high elastic modulus (≈1TPa). Under this preferred embodiment, the raw material composition includes graphene oxide, which is more conducive to improving the wear resistance of the skin, improving the strength of the skin, extending the life of the skin, improving the skin's resistance to ultraviolet radiation, preventing color changes and high temperature aging resistance, improving the skin's antistatic performance, improving the skin's hydrophobicity (waterproofness) and barrier properties, improving the skin's weather resistance, improving the skin's electrical and thermal conductivity, and making the skin have sensing properties, such as sensing pressure, temperature, humidity, odor, etc. and responding accordingly.

[0039] Hydroxyl and epoxy groups are randomly distributed on the graphene oxide single sheet, while carboxyl and carbonyl groups are introduced at the edge of the single sheet. The surface of graphene oxide contains functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy. On the one hand, graphene oxide combines with the surface hydroxyl (-OH) of silica gel, and graphene oxide interacts with the surface hydroxyl of silica gel through esterification reaction or other covalent reactions. For example, the -COOH group of graphene oxide reacts with Si-OH to generate a mixture, and graphene oxide and silica gel and thermoplastic elastomer can be better chemically and physically combined. On the second hand, the silane coupling agent firmly combines graphene oxide with the silica gel surface through covalent bonds, and the end group (such as amino group) of the silane coupling agent reacts with the oxide group of graphene to further enhance the interaction between graphene and silica gel. From the above two aspects, graphene is oxidized to form graphene oxide (GO) and functional groups (such as carboxyl) are introduced. The combination of graphene oxide and silicone and thermoplastic elastomer is promoted through esterification reaction, silane coupling agent and other methods. Graphene is closely combined with silicone, thermoplastic elastomer and polyurethane and produces a certain cross-linking reaction. Graphene is better integrated into the system, and it is not easy to produce problems such as graphene oxide agglomeration and uneven distribution. It is more conducive to promoting the uniform dispersion and mutual combination of graphene, silicone, thermoplastic elastomer and polyurethane, reducing stratification, and giving full play to the synergistic effect of graphene, silicone, thermoplastic elastomer and polyurethane to improve skin performance.

[0040] Usually the actual cross-linking reaction process is extremely complex and difficult to determine accurately. The above analysis explains to a certain extent why the addition of substances affects the mixture system of multiple substances, but it does not mean that it will necessarily react 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, based on the total mass of the raw material composition, the content of graphene oxide is 0.01 wt% to 2 wt%. Under this preferred scheme, it is more conducive to avoiding obvious delamination among graphene oxide, silica gel, thermoplastic elastomer and polyurethane, and giving full play to the synergistic effect of the composite of graphene oxide, silica gel, thermoplastic elastomer and polyurethane, so as to improve the skin performance. The content of graphene oxide is, 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] In a second aspect, the present invention provides a method for manufacturing a robot skin, which uses the raw material composition for manufacturing a robot skin described in the first aspect to perform mixing, stirring, molding and centrifugal rotation to obtain the robot skin.

[0043] In the method for manufacturing a robot skin of the present invention, during the mixing and stirring process, polyurethane is formed by reaction, and various substances such as silica gel, polyurethane, thermoplastic elastomer, silane coupling agent and graphene oxide start to crosslink with each other, and the material is in an emulsion state. During centrifugal rotation, the material is in a semi-solidified state. Centrifugal rotation, on the one hand, eliminates a small amount of 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 improve the uniformity of the same layer of the skin, the vertical layer property and the mechanical balanced arrangement (where the vertical position is relative to the skin and is in the parallel direction of centrifugation); the silica gel has a high density, while the polyurethane and thermoplastic elastomer are light. Through centrifugation, the part with a high density of silica gel is moderately layered with the part with a light density of polyurethane and thermoplastic elastomer, forming a hierarchical structure in which the silica gel content on the skin surface is slightly lower than that inside the skin and the polyurethane and thermoplastic elastomer content on the skin surface is slightly higher than that inside the skin. The thermoplastic elastomer has good elasticity, good tensile resistance and good impact resistance, and the polyurethane has good color retention. By making the thermoplastic elastomer and polyurethane closer to the skin surface, it is more conducive to improving the elasticity, tensile resistance, impact resistance, strength uniformity of the skin and the smoothness of the skin surface, and improving the color of the skin.

[0044] It can be understood that raw materials such as silica gel will bring water, and it is not necessary to add another amount of water during the mixing and stirring process for preparing the robot skin to promote the polyurethane reaction. The present invention does not limit the molding method, for example, it can be extrusion molding, injection molding or casting molding. The manufacturing method by casting molding is, for example, mixing, casting, centrifugal rotation and demolding to obtain the robot skin.

[0045] In some preferred embodiments, the conditions for centrifugal rotation 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. Under this preferred scheme, it is more conducive to improving the uniformity within the same layer of the skin, the vertical layer hierarchy, and the mechanical balanced arrangement of the skin, enhancing the elasticity, anti-stretching property, impact resistance, strength uniformity of the skin, as well as the smoothness of the skin surface, and improving the color of the skin. The pressure herein refers to absolute pressure.

[0046] In some preferred embodiments, the conditions for mixing and stirring include: a rotational speed of 50 rPm to 300 rPm, a temperature of 80 °C to 300 °C, and a time of 5 min to 30 min. Under this preferred scheme, it is more conducive to promoting the reaction process of polyurethane, promoting the deep cross-linking of various substances such as silicone, polyurethane, thermoplastic elastomer, silane coupling agent, and graphene oxide, and improving the comprehensive performance of the skin.

[0047] In a third aspect, the present invention provides a robot skin, which is manufactured by the manufacturing method of the robot skin described in the second aspect.

[0048] For the robot skin of the present invention, silicone, thermoplastic elastomer, and polyurethane are uniformly dispersed and combined with each other, giving full play to the synergistic effect of the composite of silicone, thermoplastic elastomer, and polyurethane. The robot skin is not easily aged or discolored, has good abrasion resistance, a long service life, strong resistance to extrusion and stretching, and will not cause cracking or softening even after multiple extrusion and stretching times.

[0049] The Young's modulus of the robot skin of the present invention is 0.2 Mpa - 0.5 Mpa, the softness and hardness of the skin are appropriate, the surface friction coefficient is 0.5 - 0.8, the skin surface is smooth, and the frictional force is small.

[0050] The following details the examples of the present invention. They are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention. Among them, the raw materials used are as follows: Liquid silicone is purchased from Shenzhen Jipeng Silicon Fluoride Materials Co., Ltd. (hydroxyl-terminated polydimethylsiloxane), solid silicone is purchased from Dow Corning of the United States (RBB - 2881 - 80), hydrogenated styrene-butadiene-hydrogenated styrene block copolymer SEBS is purchased from Taixiang Co., Ltd. (6151), modified diphenylmethane diisocyanate is purchased from BASF (Lupranate MM103c), polyether is purchased from Dow DOW (VORANOL 2000LM), silane coupling agent 3-aminopropyltriethoxysilane, catalyst cyclohexylamine, catalyst tetrabutyltin, and vulcanizing agent dibenzoyl peroxide can be selected from commercially available related products. Graphene oxide preferably uses commercially available products with functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy groups on the surface.

[0051] Example 1

[0052] A raw material composition for manufacturing robot skin, comprising silica gel, 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. Based on the total mass of the raw material composition, the content of silica gel is 72 wt%, the content of hydrogenated styrene-butadiene-hydrogenated styrene block copolymer is 12 wt%, the content of modified diphenylmethane diisocyanate is 6 wt%, the content of polyether is 6 wt%, the content of 3-aminopropyltriethoxysilane is 1 wt%, the content of tetrabutyltin is 0.5 wt%, the content of cyclohexylamine is 0.5 wt%, the content of benzoyl peroxide is 1 wt%, and the content of graphene oxide is 1 wt%; among them, the silica gel includes liquid silica gel and solid silica gel. Based on the total mass of the silica gel, the content of liquid silica gel is 70 wt%, and the content of solid silica gel is 30 wt%.

[0053] A manufacturing method for robot skin, which uses the aforementioned raw material composition for manufacturing robot skin for mixing and stirring, casting, centrifugal rotation, and demolding to obtain robot skin. The rotation speed of mixing and stirring is 150 rPm, the temperature is 200 °C, the time is 20 min, the rotation speed of centrifugal rotation is 1500 rPm, the time is 5 min, and the pressure is 0.1 bar.

[0054] Example 2

[0055] 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 3-aminopropyltriethoxysilane is 0.3 wt%, and the content of silica gel is 72.7 wt%.

[0056] Example 3

[0057] Referring to the raw material composition of Example 1, the difference is that, based on the total mass of the silica gel, the content of liquid silica gel is 84 wt%, and the content of solid silica gel is 16 wt%.

[0058] Example 4

[0059] Referring to the raw material composition of Example 1, the difference is that, based on the total mass of the silica gel, the content of liquid silica gel is 50 wt%, and the content of solid silica gel is 50 wt%.

[0060] Example 5

[0061] Referring to the raw material composition of Example 1, the difference is that tetrabutyltin is used to replace cyclohexylamine. Based on the total mass of the raw material composition, the content of tetrabutyltin is 1 wt% 。

[0062] Example 6

[0063] Referring to the raw material composition of Reference Example 1, except that graphene oxide is not included, and based on the total mass of the raw material composition, the content of silica gel is 73 wt%.

[0064] Example 7

[0065] Referring to the manufacturing method of the robot skin of Reference Example 1, except that the rotational speed of centrifugal rotation is 30 rPm and the time is 3 min.

[0066] Example 8

[0067] Referring to the manufacturing method of the robot skin of Reference Example 1, except that centrifugal rotation is not performed.

[0068] Example 9

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

[0070] Comparative Example 1

[0071] Referring to the raw material composition of Reference Example 1, except that the raw material composition does not include modified diphenylmethane diisocyanate and polyether, and directly uses thermoplastic elastomer instead. Based on the total mass of the raw material composition, the content of silica gel is 70 wt%, and the content of thermoplastic elastomer is 26 wt%.

[0072] Comparative Example 2

[0073] Referring to the raw material composition of Reference Example 1, except that the raw material composition does not include 3-aminopropyltriethoxysilane. Based on the total mass of the raw material composition, the content of silica gel is 73 wt%.

[0074] Test Example

[0075] The Young's modulus, surface friction coefficient, tensile fatigue resistance, color stability, and aging resistance of the robot skins prepared in Examples 1-9 and Comparative Examples 1-2 were characterized. The detection method for Young's modulus referred to GB / T 1447, which reflects the ability of solid materials to resist deformation and their softness and hardness; the detection method for surface friction coefficient referred to ASTM D2000, the detection method for tensile fatigue resistance referred to GB / T 33429-2016, and the detection method for aging resistance referred to GB / T 16422.3. The color stability was obtained by placing the robot skin under indoor natural light. ΔE represents the color difference between the skin color after a period of placement after demolding and the skin color after demolding. The larger the value of ΔE, the greater the color difference and the worse the color stability. The characterization results of Young's modulus are shown in Table 1, the characterization results of surface friction coefficient are shown in Table 2, the characterization results of tensile fatigue resistance are shown in Table 3, the characterization results of color stability are shown in Table 4, and the characterization results of aging resistance are shown in Table 5. The appearance photos of the robot skin of Example 1 one year after demolding are shown in Figure 1 , and the appearance photos of the robot skin of Comparative Example 1 after demolding are shown in Figure 2 , Figure 1 The skin of Figure 2 showed no obvious aging,

[0076] Table 1

[0077]

[0078] Table 2

[0079]

[0080]

[0081] Table 3

[0082]

[0083] Table 4

[0084]

[0085] Table 5

[0086]

[0087]

[0088] Comparing the comparative example with Comparative Example 1, the raw material composition includes polyurethane, which can improve the tensile fatigue resistance, color stability and aging resistance of the robot skin, endow the skin with appropriate softness and hardness, inhibit the change of Young's modulus over time, and reduce the skin surface friction coefficient. Comparing the comparative example with Comparative Example 2, the raw material composition includes a silane coupling agent, which can improve the tensile fatigue resistance, color stability and aging resistance of the robot skin, endow the skin with appropriate softness and hardness, inhibit the change of Young's modulus over time, and reduce the skin surface friction coefficient.

[0089] Comparing Comparative Example 1 with Example 2, based on the total mass of the raw material composition, the content of the silane coupling agent is 0.5 wt% - 5 wt%, which is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the skin, inhibiting the change of Young's modulus over time, and reducing the skin surface friction coefficient. Comparing Comparative Example 1 with Example 3, based on the total mass of the silica gel, the content of the liquid silica gel is not higher than 80 wt%, and the content of the solid silica gel is not lower than 20 wt%, which is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the skin, endowing the skin with appropriate softness and hardness, inhibiting the change of Young's modulus over time, and reducing the skin surface friction coefficient. Comparing Comparative Example 1 with Example 4, based on the total mass of the silica gel, the content of the liquid silica gel is not lower than 60 wt%, and the content of the solid silica gel is not higher than 40 wt%, which is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the robot skin, endowing the skin with appropriate softness and hardness, inhibiting the change of Young's modulus over time, and reducing the skin surface friction coefficient. Comparing Comparative Example 1 with Example 5, the catalyst includes cyclohexylamine, and using a composite catalyst is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the robot skin, inhibiting the change of Young's modulus over time, and reducing the skin surface friction coefficient. Comparing Comparative Example 1 with Example 6, the raw material composition includes graphene oxide, which is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the robot skin, endowing the skin with appropriate softness and hardness, inhibiting the change of Young's modulus over time, and reducing the skin surface friction coefficient. Comparing Comparative Example 1, Example 7 and Example 8, centrifugal rotation is carried out, which is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the robot skin, and reducing the skin surface friction coefficient. The rotation speed of the centrifugal rotation is 100 rPm - 3000 rPm, which is further more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the robot skin, and reducing the skin surface friction coefficient. Comparing Comparative Example 1 with Example 9, increasing the content of modified diphenylmethane diisocyanate is more conducive to improving the tensile fatigue resistance, color stability, aging resistance of the robot skin, inhibiting the change of Young's modulus over time, and reducing the skin 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 technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A raw material composition for manufacturing robot skin, characterized in that: The invention comprises silica gel, thermoplastic elastomer, modified diphenylmethane diisocyanate, polyether, silane coupling agent, catalyst and vulcanizing agent. The content of the silica gel is more than 60wt% based on the total mass of the raw material composition.

2. The raw material composition according to claim 1, characterized in that Based on the total mass of the raw material composition, the content of the silica gel is 60wt% to 77.5wt%, the content of the thermoplastic elastomer is 10wt% to 15wt%, the content of modified diphenylmethane diisocyanate is 5wt% to 10wt%, the content of polyether is 5wt% to 10wt%, the content of silane coupling agent is 0.5wt% to 5wt%, the content of catalyst is 1wt% to 2wt%, and the content of vulcanizing agent is 1wt% to 5wt%.

3. The raw material composition according to claim 1, characterized in that The silica gel includes liquid silica gel, and the content of the liquid silica gel is greater than 20wt% based on the total mass of the silica gel.

4. The raw material composition according to claim 3, characterized in that The silica gel comprises solid silica gel and liquid silica gel. Based on the total mass of the silica gel, the content of the liquid silica gel is 60wt% to 80wt%, and the content of the solid silica gel is 20wt% to 40wt%.

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

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

7. The raw material composition according to claim 6, characterized in that Based on the total mass of the raw material composition, the content of the graphene oxide is 0.01wt% to 2wt%.

8. A method for manufacturing robot skin, characterized in that: The raw material composition for manufacturing robot skin according to any one of claims 1 to 7 is mixed, stirred, molded, and centrifuged to obtain the robot skin.

9. The manufacturing method according to claim 8, characterized in that: The conditions for the centrifugal rotation 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 conditions for the mixing and stirring 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.

10. A robot skin, characterized in that: It is manufactured by the method for manufacturing robot skin according to claim 8 or 9.

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