A wear-resistant cable for a robot joint and a method of manufacturing the same

Abstract

The application provides a wear-resistant cable for a robot joint and a preparation method thereof, and the preparation method comprises the following steps: surface modification is performed on nano zinc oxide to obtain first nano zinc oxide containing amino groups on the surface; the first nano zinc oxide is mixed and reacted with a styrene-maleic anhydride copolymer, so that the amino groups on the surface of the first nano zinc oxide react with maleic anhydride groups of the styrene-maleic anhydride copolymer to form amide bonds, and a pre-dispersion is obtained; SEBS, silane-grafted EVA, polyurethane elastomer, the pre-dispersion, SEBS-g-MAH and an additive are mixed and extruded, and are coated on the outside of a cable core wire; and the extruded cable is subjected to post-crosslinking, so that the gel content of the silane-grafted EVA reaches 35-75%.

Description

Technical Field

[0001] This application relates to the field of cables, specifically to a wear-resistant cable for robot joints and its preparation method. Background Technology

[0002] In the high-frequency reciprocating bending motion of industrial robot cable carriers, the sheath material is subjected to the dual loads of repeated friction and bending. The drive unit in the cable carrier track reciprocates over long distances at a high average speed. After millions of cable carrier tests, the sample sheath and insulated core surfaces must be free of visible cracks. SEBS-based thermoplastic elastomers have become the mainstream choice for sheath materials due to their combination of rubber elasticity and thermoplastic processability. SEBS can be blended with polypropylene, white oil, flame retardants, etc., to produce sheaths or outer jackets for wires and cables. Furthermore, the SEBS / TPU blend system can compensate for the insufficient abrasion resistance of SEBS through the high abrasion resistance of TPU, and the introduction of nano-ZnO can further provide a hard point reinforcement effect.

[0003] To improve wear resistance, existing technologies typically introduce nanofillers and polar polymers into the system. However, during the bending motion of a robot cable's cable carrier, continuous sliding friction occurs between the cable sheath and the cable carrier groove wall, and the wear resistance of the sheath material directly determines the cable's service life. Reducing wear while maintaining good bending performance is crucial for extending the service life of robot cables and reducing maintenance downtime costs. Summary of the Invention

[0004] To address the problems of high EVA wear contribution, unreasonable nano-ZnO distribution, and insufficient cable sheath wear resistance due to competition for MAH capacity expansion resources in existing technologies, this application provides a wear-resistant cable for robot joints and its preparation method.

[0005] The first aspect of this application provides a wear-resistant cable for robot joints, comprising a cable core and a sheath covering the outside of the cable core. The sheath is made of SEBS, silane-grafted EVA, polyurethane elastomer, styrene-maleic anhydride copolymer, SEBS-g-MAH, and first nano zinc oxide. The gel content of the silane-grafted EVA is 35-75%. The surface of the first nano zinc oxide contains amino groups, which are connected to the maleic anhydride groups of the styrene-maleic anhydride copolymer through amide bonds formed by the reaction of the amino groups on its surface.

[0006] This application achieves a systematic improvement in wear resistance through three synergistic mechanisms. First, silane-grafted EVA maintains a linear, uncrosslinked state during processing, preserving good melt flowability and plasticizing and lubricating effects on the SEBS matrix. After molding, post-crosslinking transforms EVA into a three-dimensional crosslinked network, changing it from the phase with the lowest wear resistance in the system to a highly wear-resistant phase with high shear resistance. This eliminates the preferential failure of EVA caused by plastic flow and resolves the contradiction between processing flowability and wear resistance in terms of EVA dosage. Second, the first nano-zinc oxide reacts with the maleic anhydride groups of styrene-maleic anhydride copolymer (SMA) on its surface to form high-energy amide bonds, chemically anchoring it to the SMA molecular chain. The styrene segments of SMA and the PS hard segment microphase region of SEBS are thermodynamically miscible, allowing the first nano-zinc oxide to migrate directionally and anchor to the PS hard phase region, forming a high-density hard point array. This overcomes the tendency of ZnO to preferentially enrich towards the EVA phase under thermodynamic drive and prematurely peel off and fail. Finally, the MAH group of SMA is dedicated to anchoring the first nano-zinc oxide and guiding the PS phase region, while the MAH group of SEBS-g-MAH is dedicated to interface compatibilization of TPU. The two MAH supports are distributed in different phase regions in the SEBS microphase separation structure, realizing the spatial separation of MAH compatibilization resources, eliminating the competition of reaction sites under a single support, and greatly improving their respective compatibilization efficiency.

[0007] Furthermore, the sheath material also includes a second nano-zinc oxide, the particle size of which is larger than that of the first nano-zinc oxide. By weight, the SEBS comprises 100 parts, the silane-grafted EVA 30-40 parts, the polyurethane elastomer 20-25 parts, the styrene-maleic anhydride copolymer 8-15 parts, the SEBS-g-MAH 8-12 parts, the first nano-zinc oxide 3-6 parts, and the second nano-zinc oxide 8-12 parts. By introducing the large-particle-size second nano-zinc oxide, it complements the first nano-zinc oxide, and the content of each component within this range ensures the stability of the microphase structure and the balance of wear resistance. Specifically, the amount of silane-grafted EVA can be selected from 30 parts, 35 parts, or 40 parts; the amount of polyurethane elastomer can be selected from 20 parts, 22 parts, or 25 parts.

[0008] Furthermore, the sheath material also includes an antioxidant system comprising 0.3-0.8 parts of hindered phenolic antioxidant, 0.5-1.2 parts of phosphite-assisted antioxidant, and 0.3-0.8 parts of metal passivator. This antioxidant system works synergistically to significantly improve the thermal aging stability of the sheath material under high-temperature conditions. Specifically, the hindered phenolic antioxidant can be selected from Irganox 1010, with a content of 0.3 parts, 0.5 parts, or 0.8 parts.

[0009] Furthermore, the first nano-zinc oxide has a particle size of 30-80 nm, and the second nano-zinc oxide has a particle size of 150-300 nm; both the first and second nano-zinc oxides are surface-modified with γ-aminopropyltriethoxysilane. The small-particle-size first nano-zinc oxide is anchored to the PS hard phase region via amide bonds, while the large-particle-size second nano-zinc oxide is distributed in the cross-linked EVA subcontinuous phase and SEBS continuous phase, forming a three-level wear resistance structure that fully covers all phase regions of the friction surface. Specifically, the particle size of the first nano-zinc oxide can be selected from 30 nm, 50 nm, or 80 nm; the particle size of the second nano-zinc oxide can be selected from 150 nm, 200 nm, or 300 nm.

[0010] The second aspect of this application provides a method for preparing the aforementioned wear-resistant cable for robot joints, comprising: surface modification of nano-zinc oxide to obtain a first nano-zinc oxide containing amino groups on its surface; mixing and reacting the first nano-zinc oxide with a styrene-maleic anhydride copolymer, causing the amino groups on the surface of the first nano-zinc oxide to react with the maleic anhydride groups of the styrene-maleic anhydride copolymer to form amide bonds, thereby obtaining a pre-dispersion; compounding and extruding SEBS, silane-grafted EVA, polyurethane elastomer, the pre-dispersion, SEBS-g-MAH, and additives, and coating the extruded cable core; and performing post-crosslinking on the extruded cable to achieve a gel content of 35-75% for the silane-grafted EVA. This method, through a time-separation strategy of "processing before crosslinking" and a chemical anchoring process for the pre-dispersion, ensures excellent processing performance of the material and wear resistance of the final product.

[0011] Furthermore, the nano-zinc oxide is surface-modified using γ-aminopropyltriethoxysilane; the raw material for the compound extrusion also includes a second nano-zinc oxide, the particle size of which is larger than that of the first nano-zinc oxide. γ-aminopropyltriethoxysilane can introduce amino groups onto the surface of the nano-zinc oxide, providing reaction sites for subsequent chemical anchoring. Specifically, the modification process is carried out in an ethanol / water mixed solution.

[0012] Further, by weight, the SEBS is 100 parts, the silane-grafted EVA is 30-40 parts, the polyurethane elastomer is 20-25 parts, the styrene-maleic anhydride copolymer is 8-15 parts, the SEBS-g-MAH is 8-12 parts, the first nano zinc oxide is 3-6 parts, and the second nano zinc oxide is 8-12 parts.

[0013] Furthermore, the mixing reaction temperature is 110-145℃, the time is 5-20 min, and the reaction conversion rate is 25-65%. The compounding extrusion adopts a twin-screw extruder. SEBS, silane-grafted EVA, and the pre-dispersion are added from the main feed inlet, while polyurethane elastomer, SEBS-g-MAH, and second nano zinc oxide are added from the side feed inlet. Controlling the conversion rate ensures that some MAH and SMA segments remain unreacted, which is beneficial for subsequent segment entanglement and compatibility with the SEBS matrix. This feeding sequence allows SEBS and EVA to be plasticized first to form the matrix phase, and the pre-dispersion to first complete the anchoring and distribution with the PS microphase region of the SEBS matrix. Then, TPU and SEBS-g-MAH are introduced for compatibilization and blending, avoiding direct competition between TPU and SMA for MAH reaction sites. Specifically, the mixing reaction temperature can be selected from 110℃, 130℃, or 145℃; the processing temperature of the twin-screw extruder is 170-200℃, the screw speed is 150-350rpm, and the length-to-diameter ratio is 36-48:1.

[0014] Furthermore, the post-crosslinking temperature is 50-85℃, and the time is 8-36 hours. These conditions can stably and efficiently catalyze the hydrolysis and condensation reaction of silane-grafted EVA, avoiding excessive crosslinking that leads to deterioration in bending performance. Specifically, the post-crosslinking temperature can be selected from 50℃, 70℃, and 85℃.

[0015] The present invention has the following beneficial effects:

[0016] This invention achieves step-by-step processing and crosslinking by using silane-grafted EVA and performing post-crosslinking after molding. This transforms EVA from the plastic flow phase with the lowest wear resistance in the system into a highly wear-resistant phase of a three-dimensional crosslinked network. Without sacrificing processing fluidity, it avoids preferential failure of EVA and significantly reduces wear.

[0017] By chemically anchoring the first nano-zinc oxide with styrene-maleic anhydride copolymer through amide bonds, and utilizing the thermodynamic miscibility of the PS hard segments in SMA and SEBS, a high-density directional distribution of nano-ZnO in the PS hard phase region was achieved. This overcame the tendency of ZnO to preferentially enrich into the EVA phase and prematurely peel off, significantly improving the wear resistance efficiency of hard particles.

[0018] By introducing the SMA and SEBS-g-MAH dual MAH carrier system, spatial separation of MAH compatibility resources is achieved. SMA is dedicated to anchoring and guiding ZnO, while SEBS-g-MAH is dedicated to compatibility enhancement of TPU. This completely solves the problem of reduced efficiency caused by competition for reaction sites in a single MAH carrier, ensuring the interfacial stability of the multiphase system while achieving a balance between wear resistance and bending performance. Detailed Implementation

[0019] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0023] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0024] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0025] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0026] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0027] The term "particle" as used in this application, or a substance with a defined particle size distribution, is not necessarily spherical in shape; it may be irregular and can be either primary or secondary particles. The particle size of irregular particles is calculated as the average of their maximum and minimum diameters.

[0028] In some preferred embodiments, the VA content of the silane-grafted EVA can be 18wt%, 20wt%, 22wt%, or 24wt%, and the VTMS (vinyltrimethoxysilane) grafting rate can be 1wt%, 1.5wt%, 2wt%, or 3wt%.

[0029] In some preferred embodiments, the Shore hardness of the polyurethane elastomer can be 80A, 85A, or 90A. The particle size of the first nano-zinc oxide can be 30nm, 40nm, 50nm, 60nm, or 80nm; the particle size of the second nano-zinc oxide can be 150nm, 200nm, 250nm, or 300nm.

[0030] In some preferred embodiments, the pre-dispersion preparation temperature can be 110°C, 120°C, 130°C, 140°C, or 145°C, the mixing time can be 5 min, 8 min, 12 min, 15 min, or 20 min, and the reaction conversion rate can be 25%, 30%, 40%, 50%, 60%, or 65%. The post-crosslinking water bath temperature can be 50°C, 60°C, 70°C, 80°C, or 85°C, the soaking time can be 8 h, 12 h, 18 h, 24 h, or 36 h, and the gel content of the crosslinked EVA can be 35%, 45%, 50%, 65%, or 75%.

[0031] Example 1: This example provides a wear-resistant cable for robot joints and its preparation method.

[0032] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (VA content 20%, VTMS grafting rate 1.5%, MFI 5g / 10min, 35 parts), polyester-type TPU (Wanhua WHT-1185, Shore hardness 85A, 17 parts), polyether-type TPU (Wanhua WHT-1180, Shore hardness 80A, 8 parts), first nano zinc oxide (particle size 50nm, 4.5 parts), second nano zinc oxide (particle size 200nm, 10.5 parts), SMA (Polyscope XIRAN SMAEF40, MAH content approximately 10%, 12 parts), SEBS-g-MAH (Kerteng FG1901X, MAH grafting rate 1.7%, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), zinc stearate (1.0 part).

[0033] The preparation method of this embodiment includes the following steps:

[0034] Step 1: Modification of first-nano zinc oxide. Weigh 4.5 parts of 50nm nano zinc oxide and disperse it in a mixed solution of 45 parts anhydrous ethanol and 5 parts deionized water. Add 0.135 parts of KH550 silane coupling agent, stir evenly, and heat to 70℃ for 3 hours. After the reaction is complete, filter under vacuum, wash twice with anhydrous ethanol, and dry in an 80℃ forced-air drying oven for 4 hours to obtain amino-modified first-nano zinc oxide.

[0035] Step 2: Modification of the second nano-zinc oxide. Weigh 10.5 parts of 200nm nano-zinc oxide and modify it using the same method as in Step 1, with 0.21 parts of KH550 used, to obtain amino-modified second nano-zinc oxide.

[0036] Step 3: Preparation of ZnO-SMA predispersant. 4.5 parts of amino-modified first nano zinc oxide and 12 parts of SMA XIRANEF40 were added to a 10L Henschel high-speed mixer. The temperature was set at 130℃ and the speed at 1200 rpm, and the mixture was mixed for 12 min. After cooling to room temperature, the ZnO-SMA predispersant powder was obtained.

[0037] Step 4: Main compounding and extrusion. A co-rotating twin-screw extruder (L / D=40:1, screw diameter 35mm) is used. The temperature profile is set as follows: feed section 150℃ → plasticizing section 175℃ → compounding section 190℃ → homogenizing section 185℃ → die head 180℃, screw speed 250rpm. The following are added to the main feed inlet: 100 parts SEBS, 35 parts silane-grafted EVA, 16.5 parts ZnO-SMA pre-dispersed powder, and 1 part zinc stearate; the following are added to the side feed inlet (L / D=16): 17 parts polyester TPU, 8 parts polyether TPU, 10 parts SEBS-g-MAH, 10.5 parts amino-modified second nano zinc oxide, 0.5 parts Irganox 1010, 1 part Irgafos 168, and 10.5 parts Naugard XL-. The extruded strips are water-cooled and pelletized to obtain modified elastomer pellets.

[0038] Step 5: Cable sheath extrusion. The granules from Step 4 are extruded through a single-screw extruder at 175-190℃ to coat the cable core, forming a sheath layer.

[0039] Step Six: Post-crosslinking. Place the extruded cable in a 70℃ warm water bath and soak for 18 hours. After removal, dry in a forced-air dryer at 60℃ for 2 hours.

[0040] Example 2: This example provides a wear-resistant cable for robot joints and its preparation method.

[0041] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (20% VA content, 1.5% VTMS grafting rate, 40 parts), polyester-type TPU (Wanhua WHT-1185, Shore A hardness 85A, 17.5 parts), polyether-type TPU (Wanhua WHT-1180, Shore A hardness 80A, 7.5 parts), first nano zinc oxide (30nm particle size, 6 parts), second nano zinc oxide (200nm particle size, 10.5 parts), SMA (Polyscope XIRAN SMA EF40, MAH content approximately 10%, 15 parts), SEBS-g-MAH (Kerteng FG1901X, MAH grafting rate 1.7%, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), zinc stearate (1.0 part).

[0042] The preparation method of this embodiment includes the following steps:

[0043] Step 1: Modification of first nano-zinc oxide. Weigh 6 parts of 30nm nano-zinc oxide and modify it with KH550 according to the same method as in Step 1 of Example 1 to obtain amino-modified first nano-zinc oxide.

[0044] Step 2: Modification of the second nano-zinc oxide. Weigh 10.5 parts of 200nm nano-zinc oxide and modify it with KH550 according to the same method as in Step 2 of Example 1 to obtain amino-modified second nano-zinc oxide.

[0045] Step 3: Preparation of ZnO-SMA predispersant. Six parts of amino-modified first nano zinc oxide and 15 parts of SMA XIRANEF40 were added to a high-speed mixer. The temperature was set at 140℃ and the speed at 1200 rpm, and the mixture was mixed for 15 min. After cooling, ZnO-SMA predispersant powder was obtained.

[0046] Step 4: Main compounding and extrusion. Process parameters are the same as in Example 1. Add the following to the main feed inlet: 100 parts SEBS, 40 parts silane-grafted EVA, 21 parts ZnO-SMA pre-dispersed powder, and 1 part zinc stearate; add the following to the side feed inlet: 17.5 parts polyester-type TPU, 7.5 parts polyether-type TPU, 10 parts SEBS-g-MAH, 10.5 parts amino-modified second nano zinc oxide, 0.5 parts Irganox 1010, 1 part Irgafos 168, and 0.5 parts Naugard XL-1. Extrude and granulate.

[0047] Step 5: Cable sheath extrusion. Same as Step 5 in Example 1.

[0048] Step Six: Post-crosslinking. Place the extruded cable in a 70℃ warm water bath and soak for 24 hours. After removal, dry in a forced-air dryer at 60℃ for 2 hours.

[0049] Example 3: This example provides a wear-resistant cable for robot joints and its preparation method.

[0050] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (20% VA content, 1.5% VTMS grafting rate, 35 parts), polyester-type TPU (Wanhua WHT-1185, Shore hardness 85A, 17 parts), polyether-type TPU (Wanhua WHT-1180, Shore hardness 80A, 8 parts), 100nm nano zinc oxide (15 parts), SMA (Polyscope XIRAN SMA EF40, MAH content approximately 10%, 10 parts), SEBS-g-MAH (Kerteng FG1901X, MAH grafting rate 1.7%, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), and zinc stearate (1.0 part).

[0051] The preparation method of this embodiment includes the following steps:

[0052] Step 1: Partial modification of nano zinc oxide. Weigh 5 portions of 100nm nano zinc oxide and modify them with KH550 according to the same method as in Step 1 of Example 1 to obtain amino-modified 100nm nano zinc oxide.

[0053] Step 2: Modification of remaining nano zinc oxide. Weigh 10 parts of 100nm nano zinc oxide and modify it with KH550 according to the same method as in Step 1 of Example 1 to obtain amino-modified 100nm nano zinc oxide.

[0054] Step 3: Preparation of ZnO-SMA predispersant. Five parts of amino-modified 100nm zinc oxide nanoparticles and ten parts of SMA XIRANEF40 were added to a high-speed mixer. The temperature was set at 130℃ and the mixing speed at 1200 rpm for 12 minutes. After cooling, the predispersed powder was obtained.

[0055] Step 4: Main compounding and extrusion. Process parameters are the same as in Example 1. Add the following to the main feed inlet: 100 parts SEBS, 35 parts silane-grafted EVA, 15 parts pre-dispersed powder, and 1 part zinc stearate; add the following to the side feed inlet: 17 parts polyester-type TPU, 8 parts polyether-type TPU, 10 parts SEBS-g-MAH, 10 parts amino-modified 100nm nano zinc oxide obtained in Step 2, 0.5 parts Irganox 1010, and 1 part Irgafos 168. Extrude and granulate.

[0056] Step 5: Cable sheath extrusion. Same as Step 5 in Example 1.

[0057] Step Six: Post-crosslinking. Place the extruded cable in a 60℃ warm water bath and soak for 24 hours. After removal, dry in a forced-air dryer at 60℃ for 2 hours.

[0058] Example 4: This example provides a wear-resistant cable for robot joints and its preparation method.

[0059] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (VA content 20%, VTMS grafting rate 1.5%, MFI 5g / 10min, 35 parts), polyester-type TPU (Wanhua WHT-1185, Shore hardness 85A, 17 parts), polyether-type TPU (Wanhua WHT-1180, Shore hardness 80A, 8 parts), first nano zinc oxide (particle size 30nm, 4.5 parts), second nano zinc oxide (particle size 200nm, 10.5 parts), SMA (Polyscope XIRAN SMAEF40, MAH content approximately 10%, 12 parts), SEBS-g-MAH (Kerteng FG1901X, MAH grafting rate 1.7%, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), zinc stearate (1.0 part).

[0060] The preparation method of this embodiment includes the following steps:

[0061] Step 1: Modification of first-nano zinc oxide. Weigh 4.5 parts of 50nm nano zinc oxide and disperse it in a mixed solution of 45 parts anhydrous ethanol and 5 parts deionized water. Add 0.135 parts of KH550 silane coupling agent, stir evenly, and heat to 70℃ for 3 hours. After the reaction is complete, filter under vacuum, wash twice with anhydrous ethanol, and dry in an 80℃ forced-air drying oven for 4 hours to obtain amino-modified first-nano zinc oxide.

[0062] Step 2: Modification of the second nano-zinc oxide. Weigh 10.5 parts of 200nm nano-zinc oxide and modify it using the same method as in Step 1, with 0.21 parts of KH550 used, to obtain amino-modified second nano-zinc oxide.

[0063] Step 3: Preparation of ZnO-SMA predispersant. 4.5 parts of amino-modified first nano zinc oxide and 12 parts of SMA XIRANEF40 were added to a 10L Henschel high-speed mixer. The temperature was set at 130℃ and the speed at 1200 rpm, and the mixture was mixed for 12 min. After cooling to room temperature, the ZnO-SMA predispersant powder was obtained.

[0064] Step 4: Main compounding and extrusion. A co-rotating twin-screw extruder (L / D=40:1, screw diameter 35mm) is used. The temperature profile is set as follows: feed section 150℃ → plasticizing section 175℃ → compounding section 190℃ → homogenizing section 185℃ → die head 180℃, screw speed 250rpm. The following are added to the main feed inlet: 100 parts SEBS, 35 parts silane-grafted EVA, 16.5 parts ZnO-SMA pre-dispersed powder, and 1 part zinc stearate; the following are added to the side feed inlet (L / D=16): 17 parts polyester TPU, 8 parts polyether TPU, 10 parts SEBS-g-MAH, 10.5 parts amino-modified second nano zinc oxide, 0.5 parts Irganox 1010, 1 part Irgafos 168, and 10.5 parts Naugard XL-. The extruded strips are water-cooled and pelletized to obtain modified elastomer pellets.

[0065] Step 5: Cable sheath extrusion. The granules from Step 4 are extruded through a single-screw extruder at 175-190℃ to coat the cable core, forming a sheath layer.

[0066] Step Six: Post-crosslinking. Place the extruded cable in a 70℃ warm water bath and soak for 18 hours. After removal, dry in a forced-air dryer at 60℃ for 2 hours.

[0067] Example 5: This example provides a wear-resistant cable for robot joints and its preparation method.

[0068] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (20% VA content, 1.5% VTMS grafting rate, 35 parts), polyester-type TPU (Wanhua WHT-1185, Shore hardness 85A, 14 parts), polyether-type TPU (Wanhua WHT-1180, Shore hardness 80A, 6 parts), first nano zinc oxide (50nm particle size, 4.5 parts), second nano zinc oxide (200nm particle size, 10.5 parts), SMA (Polyscope XIRAN SMA EF40, approximately 10% MAH content, 12 parts), SEBS-g-MAH (Kerteng FG1901X, 1.7% MAH grafting rate, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), zinc stearate (1.0 part).

[0069] The preparation method of this embodiment includes the following steps:

[0070] Steps one through three: Same as steps one through three in Example 1, to obtain pre-dispersed powder.

[0071] Step 4: Main compounding and extrusion. Process parameters are the same as in Example 1. Add the following to the main feed inlet: 100 parts SEBS, 35 parts silane-grafted EVA, 16.5 parts pre-dispersed powder, and 1 part zinc stearate; add the following to the side feed inlet: 14 parts polyester-type TPU, 6 parts polyether-type TPU, 10 parts SEBS-g-MAH, 10.5 parts amino-modified second nano zinc oxide, 0.5 parts Irganox 1010, 1 part Irgafos168, and 0.5 parts Naugard XL-1. Extrude and granulate.

[0072] Step 5: Cable sheath extrusion. Same as Step 5 in Example 1.

[0073] Step Six: Post-crosslinking. Place the extruded cable in a 60℃ warm water bath and soak for 12 hours. After removal, dry in a forced-air dryer at 60℃ for 2 hours.

[0074] Comparative Example 1: This comparative example provides a wear-resistant cable for robot joints and its preparation method.

[0075] The difference from Example 1 is that this comparative example uses ordinary EVA and does not perform a post-crosslinking step, thus retaining the characteristics of the pre-dispersion.

[0076] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), ordinary EVA (VA content 20%, MFI 5g / 10min, 35 parts), polyester TPU (Wanhua WHT-1185, Shore hardness 85A, 17 parts), polyether TPU (Wanhua WHT-1180, Shore hardness 80A, 8 parts), first nano zinc oxide (particle size 50nm, 4.5 parts), second nano zinc oxide (particle size 200nm, 10.5 parts), SMA (Polyscope XIRAN SMA EF40, MAH content approximately 10%, 12 parts), SEBS-g-MAH (Kerteng FG1901X, MAH grafting rate 1.7%, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), zinc stearate (1.0 part).

[0077] The preparation method of this comparative example includes the following steps:

[0078] Steps one through three: Same as steps one through three in Example 1, to obtain pre-dispersed powder.

[0079] Step 4: Main compounding and extrusion. Process parameters are the same as in Example 1. Add the following to the main feed inlet: 100 parts SEBS, 35 parts ordinary EVA, 16.5 parts pre-dispersed powder, and 1 part zinc stearate; add the following to the side feed inlet: 17 parts polyester-type TPU, 8 parts polyether-type TPU, 10 parts SEBS-g-MAH, 10.5 parts amino-modified second nano zinc oxide, 0.5 parts Irganox 1010, 1 part Irgafos 168, and 0.5 parts Naugard XL-1. Extrude and granulate.

[0080] Step 5: Cable sheath extrusion. Same as Step 5 in Example 1. This comparative example does not include the post-crosslinking step.

[0081] Comparative Example 2: This comparative example provides a wear-resistant cable for robot joints and its preparation method.

[0082] The difference from Example 1 is that this comparative example retains the silane-grafted EVA and post-crosslinking steps, but does not prepare a pre-dispersion; all ZnO is directly mixed in a twin-screw extruder. The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (20% VA content, 1.5% VTMS grafting rate, 35 parts), polyester-type TPU (Wanhua WHT-1185, Shore hardness 85A, 17 parts), polyether-type TPU (Wanhua WHT-1180, Shore hardness 80A, 8 parts), 200nm nano zinc oxide (15 parts), SMA (Polyscope XIRAN SMA EF40, MAH content approximately 10%, 12 parts), SEBS-g-MAH (Kerteng FG1901X, MAH grafting rate 1.7%, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), and zinc stearate (1.0 part).

[0083] The preparation method of this comparative example includes the following steps:

[0084] Step 1: Modification of nano zinc oxide. Weigh 15 parts of 200nm nano zinc oxide and modify it with KH550 according to the same method as in Step 1 of Example 1 to obtain amino-modified 200nm nano zinc oxide.

[0085] Step 2: Main compounding and extrusion. Process parameters are the same as in Example 1. The following are added to the main feed inlet: 100 parts SEBS, 35 parts silane-grafted EVA, 12 parts SMA, and 1 part zinc stearate; the following are added to the side feed inlet: 17 parts polyester-type TPU, 8 parts polyether-type TPU, 10 parts SEBS-g-MAH, 15 parts amino-modified 200nm nano zinc oxide obtained in Step 1, 0.5 parts Irganox 1010, 1 part Irgafos168, and 0.5 parts Naugard XL-1. Extrusion granulation is then performed.

[0086] Step 3: Cable sheath extrusion. Same as step 5 in Example 1.

[0087] Step 4: Post-crosslinking. Place the extruded cable in a 70℃ warm water bath and soak for 18 hours. After removal, dry in a forced-air dryer at 60℃ for 2 hours.

[0088] Comparative Example 3: This comparative example provides a wear-resistant cable for robot joints and its preparation method.

[0089] The difference from Example 1 is that the post-crosslinking conditions in this comparative example resulted in excessive crosslinking of EVA, with a gel content ≥80%.

[0090] The raw materials for preparing wear-resistant cable sheaths for robot joints include: SEBS (Kerteng G1652, 30% styrene content, 100 parts), silane-grafted EVA (20% VA content, 1.5% VTMS grafting rate, 35 parts), polyester-type TPU (Wanhua WHT-1185, Shore hardness 85A, 17 parts), polyether-type TPU (Wanhua WHT-1180, Shore hardness 80A, 8 parts), first nano zinc oxide (50nm particle size, 4.5 parts), second nano zinc oxide (200nm particle size, 10.5 parts), SMA (Polyscope XIRAN SMA EF40, approximately 10% MAH content, 12 parts), SEBS-g-MAH (Kerteng FG1901X, 1.7% MAH grafting rate, 10 parts), Irganox 1010 (0.5 parts), Irgafos 168 (1.0 part), Naugard XL-1 (0.5 parts), zinc stearate (1.0 part).

[0091] The preparation method of this comparative example includes the following steps:

[0092] Steps one through five: Same as steps one through five in Example 1.

[0093] Step Six: Post-crosslinking. Place the extruded cable in an 85°C water bath and soak for 36 hours. After removal, dry in a forced-air dryer at 60°C for 2 hours.

[0094] Abrasion resistance test: Refer to GB / T 1689-2014 "Determination of abrasion resistance of vulcanized rubber (using Akron abrasion tester)" and the test specimen is a standard ring specimen. The grinding wheel model is ZY-6306, the load is 27N, the tilt angle is 15°, the test stroke is 1.61km, and the volume loss of abrasion is recorded.

[0095] Bending performance test: Referring to the 2PFG 2577 standard and the group standard "Technical Specification for Testing Special Cables for Robots", the bending radius of the cable chain is 6D, the running speed is 1m / s, the stroke is ≥1m, and the surface condition of the sheath and the change rate of DC resistance of the conductor are recorded after 5 million bends.

[0096] Mechanical property testing: Refer to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" to test tensile strength and elongation at break.

[0097] EVA crosslinking degree test: Refer to the gel content determination method in GB / T 2951.21-2008, immerse the sample in boiling xylene for 8 hours, take it out and dry it, and calculate the proportion of insoluble matter.

[0098] Nano-zinc oxide dispersibility detection: Scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS) was used to fracture the sample in liquid nitrogen, observe the fracture morphology and perform Zn element surface distribution mapping.

[0099] Thermal aging performance test: Refer to GB / T 2951.12-2008, the condition is 135℃ × 168h thermal aging, and the change rate of elongation at break is tested.

[0100] Low temperature resistance test: Refer to GB / T 2951.14-2008, low temperature bending test, the condition is to bend on the specified mandrel at -25℃ and observe whether cracking occurs.

[0101] Table 1. Test results of Examples 1-5 and Comparative Examples 1-3

[0102]

[0103] As can be seen from the data in Table 1, the wear amount of Example 1 was reduced to 32-38mg, while the elongation at break was maintained at 365-390%, and the 5 million bending test was passed, achieving an excellent balance between wear resistance and bending performance.

[0104] Comparing the data from Example 1 and Comparative Example 1, Comparative Example 1, which only used a pre-dispersion for directional distribution without cross-linking EVA, showed a wear rate of 42-48 mg. Compared to Example 1, the lack of EVA cross-linking led to an increase in wear rate of approximately 10 mg. This is because, although ZnO achieved directional anchoring to the PS hard phase region through the pre-dispersion, improving the wear resistance efficiency of hard particles, the uncross-linked EVA still has a linear structure. On the friction surface, it preferentially undergoes plastic flow and material transfer as a weak phase, limiting the upper limit of overall wear resistance.

[0105] Comparing the data from Example 1 and Comparative Example 2, Comparative Example 2, which only used EVA crosslinking without ZnO pre-dispersion and directional distribution, showed a wear rate of 40-48 mg. Compared to Example 1, the lack of directionally distributed ZnO resulted in an increase in wear rate of approximately 8-10 mg. This confirms that although crosslinked EVA eliminates the weak phase plastic flow, randomly distributed ZnO cannot form a high-density hard point array in the PS phase region, making it difficult to prevent the propagation of friction chains, and thus the anti-wear efficiency did not reach its optimal level.

[0106] It is evident that there is a strict synergistic dependence between EVA crosslinking and the directional distribution of ZnO predispersants: EVA crosslinking eliminates the macroscopic failure of the weak phase in the matrix, providing a stable matrix support for the ZnO hard particles to play their role; while the directional anchoring of ZnO constructs a microscopic array of hard particles on the high wear-resistant matrix. Only by combining the two can the wear amount be reduced from more than 40mg to 32-38mg in a leapfrog manner, and neither can be omitted.

[0107] Comparative Example 3 reveals the effect of EVA crosslinking degree. When the water bath conditions intensified, causing the EVA gel content to exceed 80%, although the wear amount further decreased to 30-36 mg, the elongation at break dropped sharply to 280-320%, far below the engineering baseline of 350%, resulting in failure of the 5 million bending test. This indicates that excessive crosslinking causes the EVA phase to lose its elastic deformation ability, transforming the material from flexible to rigid, and severely deteriorating its bending performance. Therefore, post-crosslinking conditions must be precisely controlled within the gel content range of 35-75%.

[0108] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a wear-resistant cable for robot joints, characterized in that, include: Surface modification of nano zinc oxide yields first nano zinc oxide with amino groups on its surface; The first nano zinc oxide was mixed and reacted with styrene-maleic anhydride copolymer, so that the amino groups on the surface of the first nano zinc oxide reacted with the maleic anhydride groups of the styrene-maleic anhydride copolymer to form amide bonds, thus obtaining a pre-dispersion. SEBS, silane-grafted EVA, polyurethane elastomer, the pre-dispersion, SEBS-g-MAH and additives are mixed, extruded, and coated onto the outside of the cable core. The extruded cable is then subjected to post-crosslinking to achieve a gel content of 35-75% in the silane-grafted EVA.

2. The preparation method according to claim 1, characterized in that, The nano zinc oxide is surface modified using γ-aminopropyltriethoxysilane; the raw material for the compound extrusion also includes a second nano zinc oxide, the particle size of which is larger than that of the first nano zinc oxide.

3. The preparation method according to claim 2, characterized in that, By weight, the SEBS is 100 parts, the silane-grafted EVA is 30-40 parts, the polyurethane elastomer is 20-25 parts, the styrene-maleic anhydride copolymer is 8-15 parts, the SEBS-g-MAH is 8-12 parts, the first nano zinc oxide is 3-6 parts, and the second nano zinc oxide is 8-12 parts.

4. The preparation method according to claim 3, characterized in that, The mixing reaction is carried out at a temperature of 110-145℃ for 5-20 minutes, with a conversion rate of 25-65%. The compounding and extrusion is carried out using a twin-screw extruder. SEBS, silane-grafted EVA and the pre-dispersion are added from the main feed inlet, while polyurethane elastomer, SEBS-g-MAH and second nano zinc oxide are added from the side feed inlet.

5. The preparation method according to claim 1, characterized in that, The post-crosslinking temperature is 50-85℃, and the time is 8-36h.

6. A wear-resistant cable for robot joints, comprising a cable core and a sheath covering the outside of the cable core, characterized in that, The sheath is made of SEBS, silane-grafted EVA, polyurethane elastomer, styrene-maleic anhydride copolymer, SEBS-g-MAH, and first nano zinc oxide; the gel content of the silane-grafted EVA is 35-75%; the surface of the first nano zinc oxide contains amino groups, and the amino groups on its surface are connected to the maleic anhydride groups of the styrene-maleic anhydride copolymer through the reaction of the amino groups on its surface with amide bonds formed by the reaction of the maleic anhydride groups on its surface.

7. The wear-resistant cable for robot joints according to claim 6, characterized in that, The sheath material also includes a second nano-zinc oxide, the particle size of which is larger than that of the first nano-zinc oxide; by weight, the SEBS is 100 parts, the silane-grafted EVA is 30-40 parts, the polyurethane elastomer is 20-25 parts, the styrene-maleic anhydride copolymer is 8-15 parts, the SEBS-g-MAH is 8-12 parts, the first nano-zinc oxide is 3-6 parts, and the second nano-zinc oxide is 8-12 parts.

8. The wear-resistant cable for robot joints according to claim 6, characterized in that, The sheath material also includes an antioxidant system, which comprises 0.3-0.8 parts of hindered phenolic antioxidant, 0.5-1.2 parts of phosphite-assisted antioxidant, and 0.3-0.8 parts of metal passivator.

9. The wear-resistant cable for robot joints according to claim 7, characterized in that, The first nano zinc oxide has a particle size of 30-80 nm, and the second nano zinc oxide has a particle size of 150-300 nm; both the first nano zinc oxide and the second nano zinc oxide are surface modified with γ-aminopropyltriethoxysilane.

10. The application of the wear-resistant cable for robot joints as described in claim 6 in the moving cables of industrial robot cable carrier systems or automated equipment.

Images