PEEK material applied to humanoid robot

Abstract

The invention relates to a PEEK material applied to a humanoid robot, and belongs to the technical field of polymer composite materials. The PEEK material is prepared from the following components in percentage by weight: 8.5 to 11 percent of short carbon fiber, 3.7 to 4.4 percent of anti-cracking modifier, 1.5 to 2.1 percent of lubricant, 0.35 to 0.4 percent of antioxidant and the balance of PEEK resin, the anti-cracking modifier is prepared by the following steps: carrying out substitution reaction on active primary amino of 3-bromopropyltrimethoxysilane and N-(3-aminopropyl) diethanol amine to prepare an intermediate, activating 1, 3-adamantanedicarboxylic acid by using thionyl chloride, and esterifying with the intermediate to form a chain polyester compound; the anti-cracking modifier significantly reduces the cracking risk of the humanoid robot material through the rigid gradient transition layer design and the multi-interface anchoring mechanism, and breaks through the application bottleneck of the existing carbon fiber composite PEEK material under the thermal cycle working condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials, and in particular relates to a PEEK material applied to a humanoid robot. Background Art

[0002] Polyetheretherketone (PEEK), a high-performance thermoplastic engineering plastic, is an ideal lightweight material for replacing metal components in robotics due to its exceptional mechanical strength, high-temperature resistance, and low density. In the field of humanoid robots, its high specific strength significantly improves joint load capacity and reduces energy consumption. However, PEEK's inherent brittleness limits its reliability under dynamic loads and complex structures. Therefore, existing technologies commonly use carbon fiber as a reinforcement, creating carbon fiber-reinforced PEEK composites through blending to enhance their mechanical properties.

[0003] Although the composite material of carbon fiber and PEEK performs well under static conditions, the following key defects are exposed in the actual working conditions of humanoid robots: there is a significant difference in the thermal expansion coefficients of carbon fiber and PEEK matrix. When the temperature fluctuates violently, periodic shear stress is generated at the interface, inducing microcracks that gradually expand into macroscopic stratification. In addition, the bionic curved surface structure of the humanoid robot exacerbates stress concentration, resulting in a significantly increased risk of cracking of the composite material in the area of ​​sudden curvature change; conventional silane coupling agents (silane coupling agents, titanate coupling agents, etc.) are easily decomposed or volatilized at the PEEK processing temperature and cannot effectively bridge the fiber and the matrix; the existing technology uses polyamide sizing agents to treat carbon fiber. Although it meets the purpose of surface modification at high temperature and improves the wettability of carbon fiber and resin, the polyamide sizing layer only has a surface modification effect, and the bonding effect with the PEEK matrix and carbon fiber is poor. It cannot resist external forces and interfacial slip under stress, and has no significant effect on improving the PEEK material, and cannot meet the performance requirements of some humanoid robot parts. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a PEEK material for use in humanoid robots.

[0005] The purpose of the present invention can be achieved through the following technical solutions: The PEEK material used in humanoid robots has the following components: 8.5-11wt% of chopped carbon fibers, 3.7-4.4wt% of an anti-cracking modifier, 1.5-2.1wt% of a lubricant, 0.35-0.4wt% of an antioxidant, and the balance being PEEK resin.

[0006] The anti-cracking modifier is prepared by the following method: Step A1: N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane and anhydrous tetrahydrofuran were pre-mixed, dry nitrogen was introduced to protect, the temperature was controlled at 40-50°C by water bath, triethylamine was slowly added and stirred for 6-8h, then filtered and rotary evaporated to obtain the intermediate; Further, in the reaction process of step A1, the amount ratio of N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, triethylamine and anhydrous tetrahydrofuran was 0.1mol:0.1mol:0.12-0.15mol:280-360mL, triethylamine was used as an acid-binding agent to promote the substitution reaction of the active primary amine group of 3-bromopropyltrimethoxysilane and N-(3-aminopropyl)diethanolamine, and the reaction process was as follows: Step A2: 1,3-adamantane dicarboxylic acid and DMF were mixed, dry nitrogen was introduced to protect, chlorosulfuric acid was added and stirred, the temperature was increased to 85-90°C, and the reaction was carried out for 1.5-2h, then the intermediate was added and the pressure was reduced to 0.1kPa, the temperature was increased to 120-140°C, and the reaction was continued for 4.5-5.8h, during the reaction process, DMF was recovered by using a condenser tube containing alkaline dry tube, and the reaction was completed to obtain the anti-cracking modifier; Further, in the reaction process of step A2, the amount ratio of 1,3-adamantane dicarboxylic acid, intermediate, chlorosulfuric acid and DMF was 0.1mol:0.102-0.104mol:0.35-0.4mol:550-700mL, 1,3-adamantane dicarboxylic acid was activated by chlorosulfuric acid, then esterified with the intermediate to form a polyester compound, and the reaction process was as follows: Further, the chopped carbon fiber is a glue-free chopped carbon fiber filament with a length of 4-6mm, which has stable reinforcing effect under this specification, and the glue-free bare filament surface contains a large number of active groups, which is easy to interact with the anti-cracking modifier.

[0007] Further, the lubricant is a combination of pentaerythritol stearate and polytetrafluoroethylene resin powder, which has high and low temperature lubrication effect, especially good stability at high temperature, and maintains the fluidity of the melt.

[0008] Further, the antioxidant is a combination of antioxidant 330 and antioxidant 9228, which is suitable for the processing technology of PEEK and maintains stable antioxidant capacity at high temperature.

[0009] The forming process of PEEK material applied to humanoid robots is as follows: the anti-cracking modifier, lubricant, antioxidant and PEEK resin are pre-mixed, the pre-mixed material and chopped carbon fiber are respectively fed from the main and side feeding ports of the double screw extruder, then melted and blended, discharged and pelletized to form.

[0010] Furthermore, the temperature process parameters during the melt blending process are: 340-360°C in the feeding section, 370-390°C in the melting section, and 390-400°C in the homogenization section.

[0011] Beneficial effects of the present invention: The present invention is based on the existing carbon fiber reinforcement system, and adds a self-developed anti-cracking modifier for blending modification. The system is prepared by the substitution reaction of the active primary amine group of 3-bromopropyltrimethoxysilane and N-(3-aminopropyl)diethanolamine to form an intermediate, and then 1,3-adamantanedicarboxylic acid is activated by thionyl chloride, and then esterified with the intermediate to form a chain polyester compound, which is the anti-cracking modifier. During the composite processing, the methoxysilane structure of the anti-cracking modifier is coupled with the carbon fiber surface and then grafted to the carbon fiber surface, introducing a layer of adamantane structure modification on the carbon fiber surface. The rigidity of the adamantane structure is between that of the carbon fiber and the PEEK matrix. The rigid gradient transition layer fills the rigid fault between the carbon fiber and the PEEK matrix, making the interfacial stress distribution more continuous. When the temperature changes and the external force acts, it acts as a transition layer to alleviate the separation of the interface. In addition, the secondary amine structure on the side chain of the anti-cracking modifier molecule is combined with the ketone group on the PEEK molecular chain through hydrogen bonding, thereby forming a spatial interlocking between the adamantane cage structure and the benzene ring on the PEEK molecule, effectively improving the interface bonding strength and inhibiting interface slip. The rigid gradient transition layer design and multiple interface anchoring mechanism significantly reduce the cracking risk of materials used in humanoid robots, breaking through the application bottleneck of existing carbon fiber composite PEEK materials under thermal cycling conditions. DETAILED DESCRIPTION

[0012] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0013] Example 1: Preparation of PEEK material for use in humanoid robots. The specific implementation method is as follows: (1) Preparation of anti-cracking modifier Step A1: Premix N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, and anhydrous tetrahydrofuran, introduce dry nitrogen protection, control the temperature of the water bath at 40°C, slowly add triethylamine, and stir to react for 8 hours. The amount ratio of N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 0.12 mol: 280 mL. After the reaction, filter to remove salt, and then remove tetrahydrofuran by rotary evaporation to obtain an intermediate.

[0014] Step A2: 1,3-adamantanedicarboxylic acid and DMF were mixed and passed through dry nitrogen for protection. Thionyl chloride was added and mixed, and the mixture was heated to 85°C and stirred for 2 hours. Then, the intermediate was added and the pressure was reduced to 0.1 kPa. The temperature was raised to 120°C and the reaction was continued for 5.8 hours. During the reaction, DMF was recovered using a condenser containing an alkaline drying tube. After the reaction was completed, the material was discharged to obtain an anti-cracking modifier.

[0015] (2) PEEK material mixing and granulation The following components are taken in percentage by weight: 8.5wt% of chopped carbon fiber, using 6mm glue-free chopped carbon fiber yarn; 3.7wt% of anti-cracking modifier, homemade in this embodiment; 1.5wt% of lubricant, using pentaerythritol stearate and polytetrafluoroethylene resin powder in a weight ratio of 1:1; 0.4wt% of antioxidant, using antioxidant 330 and antioxidant 9228 in a weight ratio of 2:1; the remainder is PEEK resin, using KT-820NT type resin raw material.

[0016] Mixing: Add the anti-cracking modifier, lubricant, antioxidant and PEEK resin into a high-speed mixer and mix them at 1500 rpm for 10 minutes. Then, feed the premix and chopped carbon fiber from the main and side feeding ports of the twin-screw extruder respectively. The temperature parameters of the twin-screw extruder are set as follows: feeding section, zone 1 340°C, zone 2 350°C, zone 3 360°C; melting section, zone 1 370°C, zone 2 380°C, zone 3 390°C; homogenizing section, zone 1 390°C, zone 2 400°C; melt and blend the raw materials of each component, and then discharge and pelletize to obtain PEEK material.

[0017] Example 2: Preparation of PEEK material for use in humanoid robots. The specific implementation method is as follows: (1) Preparation of anti-cracking modifier Step A1: Premix N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, and anhydrous tetrahydrofuran, introduce dry nitrogen protection, control the temperature of the water bath at 50°C, slowly add triethylamine, and stir to react for 6 hours. The amount ratio of N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 0.15 mol: 360 mL. After the reaction, filter to remove salt, and then remove tetrahydrofuran by rotary evaporation to obtain an intermediate.

[0018] Step A2: 1,3-adamantanedicarboxylic acid and DMF were mixed and passed through dry nitrogen for protection. Thionyl chloride was added and mixed, and the mixture was heated to 90°C and stirred for reaction for 1.5 hours. Then, the intermediate was added and the pressure was reduced to 0.1 kPa. The temperature was raised to 140°C and the reaction was continued for 4.5 hours. During the reaction, DMF was recovered using a condenser containing an alkaline drying tube. After the reaction was completed, the material was discharged to obtain an anti-cracking modifier.

[0019] (2) PEEK material mixing and granulation The following components are taken in percentage by weight: 10.2wt% of chopped carbon fiber, using 4mm glue-free chopped carbon fiber filaments; 4.1wt% of anti-cracking modifier, homemade by this embodiment; 1.9wt% of lubricant, using pentaerythritol stearate and polytetrafluoroethylene resin powder in a weight ratio of 1:1; 0.38wt% of antioxidant, using antioxidant 330 and antioxidant 9228 in a weight ratio of 2:1; the remainder is PEEK resin, using KT-820NT type resin raw material.

[0020] Mixing: Add the anti-cracking modifier, lubricant, antioxidant and PEEK resin into a high-speed mixer and mix them at 1500 rpm for 10 minutes. Then, feed the premix and chopped carbon fiber from the main and side feeding ports of the twin-screw extruder respectively. The temperature parameters of the twin-screw extruder are set as follows: feeding section, zone 1 340°C, zone 2 350°C, zone 3 350°C; melting section, zone 1 370°C, zone 2 370°C, zone 3 380°C; homogenizing section, zone 1 390°C, zone 2 390°C; melt and blend the raw materials of each component, and then discharge and pelletize to obtain PEEK material.

[0021] Example 3: Preparation of PEEK material for use in humanoid robots. The specific implementation method is as follows: (1) Preparation of anti-cracking modifier Step A1: Premix N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, and anhydrous tetrahydrofuran, introduce dry nitrogen protection, control the temperature of the water bath at 50°C, slowly add triethylamine, and stir to react for 6.5 hours. The amount ratio of N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 0.14 mol: 330 mL. After the reaction, filter to remove salt, and then remove tetrahydrofuran by rotary evaporation to obtain an intermediate.

[0022] Step A2: 1,3-adamantanedicarboxylic acid and DMF were mixed and passed through dry nitrogen for protection. Thionyl chloride was added, mixed, and the temperature was raised to 90°C with stirring for 1.7 hours. Then, the intermediate was added and the pressure was reduced to 0.1 kPa. The temperature was raised to 130°C and the reaction was continued for 5.2 hours. During the reaction, DMF was recovered using a condenser containing an alkaline drying tube. After the reaction was completed, the material was discharged to obtain an anti-cracking modifier.

[0023] (2) PEEK material mixing and granulation The following components are taken in percentage by weight: 11wt% of chopped carbon fiber, using 4mm glue-free chopped carbon fiber filaments; 4.4wt% of anti-cracking modifier, homemade in this embodiment; 2.1wt% of lubricant, using pentaerythritol stearate and polytetrafluoroethylene resin powder in a weight ratio of 1:1; 0.35wt% of antioxidant, using antioxidant 330 and antioxidant 9228 in a weight ratio of 2:1; the remainder is PEEK resin, using KT-820NT type resin raw material.

[0024] Mixing: Add the anti-cracking modifier, lubricant, antioxidant and PEEK resin into a high-speed mixer and mix them at 1500rpm for 10 minutes. Then, feed the premix and chopped carbon fiber from the main and side feeding ports of the twin-screw extruder respectively. The temperature parameters of the twin-screw extruder are set as follows: feeding section, zone 1 350℃, zone 2 360℃, zone 3 360℃; melting section, zone 1 370℃, zone 2 390℃, zone 3 390℃; homogenizing section, zone 1 400℃, zone 2 400℃; melt-blend the raw materials of each component, and then discharge and pelletize to obtain PEEK material.

[0025] Example 4: Preparation of PEEK material for use in humanoid robots. The specific implementation method is as follows: (1) Preparation of anti-cracking modifier Step A1: Premix N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, and anhydrous tetrahydrofuran, introduce dry nitrogen protection, control the temperature of the water bath at 45°C, slowly add triethylamine, and stir to react for 7.5 hours. The amount ratio of N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 0.13 mol: 300 mL. After the reaction, filter to remove salt, and then remove tetrahydrofuran by rotary evaporation to obtain an intermediate.

[0026] Step A2: 1,3-adamantanedicarboxylic acid and DMF were mixed and passed through dry nitrogen for protection. Thionyl chloride was added, mixed, and the temperature was raised to 85°C with stirring for 2 hours. Then, the intermediate was added and the pressure was reduced to 0.1 kPa. The temperature was raised to 130°C and the reaction was continued for 5.5 hours. During the reaction, DMF was recovered using a condenser containing an alkaline drying tube. After the reaction was completed, the material was discharged to obtain an anti-cracking modifier.

[0027] (2) PEEK material mixing and granulation The following components are taken in percentage by weight: 9.6wt% of chopped carbon fiber, using 6mm glue-free chopped carbon fiber yarn; 3.9wt% of anti-cracking modifier, homemade in this embodiment; 1.8wt% of lubricant, using pentaerythritol stearate and polytetrafluoroethylene resin powder in a weight ratio of 1:1; 0.35wt% of antioxidant, using antioxidant 330 and antioxidant 9228 in a weight ratio of 2:1; the remainder is PEEK resin, using KT-820NT type resin raw material.

[0028] Mixing: Add the anti-cracking modifier, lubricant, antioxidant and PEEK resin into a high-speed mixer and mix them at 1500 rpm for 10 minutes. Then, feed the premix and chopped carbon fiber into the main and side feeding ports of the twin-screw extruder respectively. The temperature parameters of the twin-screw extruder are set as follows: feeding section, zone 1 350°C, zone 2 350°C, zone 3 360°C; melting section, zone 1 370°C, zone 2 380°C, zone 3 380°C; homogenizing section, zone 1 390°C, zone 2 390°C; melt and blend the raw materials of each component, and then discharge and pelletize to obtain PEEK material.

[0029] In a comparative example, referring to the implementation method of Example 4, the total amount of chopped carbon fiber and anti-cracking modifier was replaced with TR06NL polyamide sizing chopped carbon fiber, and the rest of the implementation process was exactly the same.

[0030] The PEEK material prepared as above was injection molded into a specimen, and the tensile properties were tested according to ASTM D638-2022, the bending properties were tested according to ASTM D790-2017, and the impact properties were tested according to ASTM D6110-2017. The specific test results are shown in Table 1: Table 1

[0031] It can be seen from the test results in Table 1 that the PEEK material prepared in the embodiment has better strength and toughness.

[0032] The above specimens were subjected to 100 cycles of thermal shock at -30°C (2h) and 150°C (2h) according to ASTM D3045-2018. The tensile and impact properties of the specimens were then tested again and the retention rate was calculated. The cross-sectional morphology was observed using a metallographic microscope, and the crack density per unit area was calculated. The specific test results are shown in Table 2: Table 2

[0033] It can be seen from the test results in Table 2 that the PEEK material prepared in the example has more stable performance under thermal cycle shock. In particular, after thermal cycle shock, the number of visible cracks in the example is significantly lower than that in the comparative example.

[0034] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0035] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. PEEK material used in humanoid robots, characterized by: The specific components are: 8.5-11wt% of chopped carbon fiber, 3.7-4.4wt% of anti-crack modifier, 1.5-2.1wt% of lubricant and 0.35-0.4wt% of antioxidant, and the balance is PEEK resin; The anti-cracking modifier is prepared by the following method: Step A1: Premix N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, and anhydrous tetrahydrofuran, introduce dry nitrogen gas, control the temperature in a water bath at 40-50°C, slowly add triethylamine, and stir to react for 6-8 hours to prepare an intermediate; Step A2: 1,3-adamantanedicarboxylic acid and DMF were mixed, and dry nitrogen was introduced for protection. Thionyl chloride was added, mixed, and the mixture was heated to 85-90°C and stirred for reaction for 1.5-2 hours. Then, the intermediate was added, the pressure was reduced to 0.1 kPa, and the mixture was heated to 120-140°C and the reaction was continued for 4.5-5.8 hours to prepare an anti-cracking modifier.

2. The PEEK material for humanoid robots according to claim 1, characterized in that: The usage ratio of N-(3-aminopropyl)diethanolamine, 3-bromopropyltrimethoxysilane, triethylamine and anhydrous tetrahydrofuran is 0.1 mol: 0.1 mol: 0.12-0.15 mol: 280-360 mL.

3. The PEEK material for humanoid robots according to claim 2, characterized in that: The usage ratio of 1,3-adamantanedicarboxylic acid, intermediate, thionyl chloride and DMF is 0.1 mol: 0.102-0.104 mol: 0.35-0.4 mol: 550-700 mL.

4. The PEEK material for a humanoid robot according to claim 1, characterized in that: Chopped carbon fiber is glue-free chopped carbon fiber filament with a length of 4-6mm.

5. The PEEK material for humanoid robots according to claim 1, characterized in that: The lubricant is prepared by combining pentaerythritol stearate and polytetrafluoroethylene resin powder.

6. The PEEK material for humanoid robots according to claim 1, characterized in that: The antioxidant is used in combination with antioxidant 330 and antioxidant 9228.

7. The PEEK material for a humanoid robot according to claim 1, characterized in that: The molding process of the PEEK material is as follows: premixing an anti-crack modifier, a lubricant, an antioxidant and a PEEK resin, feeding the premix and chopped carbon fibers into the main and side feed ports of a twin-screw extruder respectively, and then melt-blending, discharging and pelletizing.

8. The PEEK material for a humanoid robot according to claim 7, characterized in that: The temperature process parameters during the melt blending process are: 340-360°C in the feeding section, 370-390°C in the melting section, and 390-400°C in the homogenizing section.

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