Wear-resistant halogen-free flame-retardant TPU elastomer for wires and cables and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a wear-resistant halogen-free flame-retardant TPU elastomer for electric wires and cables and a preparation method thereof.The TPU elastomer is prepared by taking a thermoplastic polyurethane elastomer as a base material and taking modified nano molybdenum disulfide, a lubricant and the like as auxiliary materials through mixing and extrusion processes. Wherein the modified nano-molybdenum disulfide is prepared by modifying the surface of nano-molybdenum disulfide with a multi-element flame-retardant modifier, and the existence of the multi-element flame-retardant modifier can improve the interface problem between the nano-molybdenum disulfide and the thermoplastic polyurethane elastomer, so that uniform dispersion of the nano-molybdenum disulfide is facilitated; therefore, the advantages of the nano molybdenum disulfide are efficiently utilized, the wear resistance and mechanical strength of the elastomer are improved, and the flame retardant property of the elastomer can be greatly enhanced in the presence of the multi-element flame retardant modifier.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables and a preparation method thereof. Background Art

[0002] Thermoplastic polyurethane elastomer (TPU) is composed of a soft segment of oligomer diol and a hard segment of diisocyanate-chain extender. This block copolymer structure of alternating soft and hard segments gives thermoplastic polyurethane elastomer both the elasticity of rubber and the processing properties of plastic. Therefore, its application in the field of wires and cables has become increasingly extensive in recent years. At present, thermoplastic polyurethane elastomer has been widely used in automotive cables (such as anti-lock braking system ABS cables, odometer cables), industrial automation cables, medical equipment cables and consumer electronics cables, and has achieved great application results. However, as the application scenarios evolve towards high safety and high environmental protection, the limitations of traditional thermoplastic polyurethane elastomer materials have become increasingly prominent, driving the industry to carry out targeted modification research.

[0003] First, the limiting oxygen index of ordinary thermoplastic polyurethane elastomers is only 19%, and combustion produces large amounts of black smoke and toxic gases, which cannot meet the fire protection requirements of public buildings and confined spaces. Secondly, although thermoplastic polyurethane elastomers have acceptable wear resistance, they cannot withstand the wear caused by repeated dragging. Therefore, functional improvements such as wear resistance and flame retardancy of thermoplastic polyurethane elastomers are of great significance for their further application in the wire and cable industry.

[0004] At present, it is common to use various functional additives, such as halogen flame retardants or inorganic flame retardants such as magnesium hydroxide, to achieve functional improvements such as flame retardancy of thermoplastic polyurethane elastomers. However, these additives have obvious defects in practical applications. For example, halogen flame retardants release carcinogens such as dioxins when burned, which not only pollutes the environment but also poses safety hazards. Therefore, they are not suitable for use. There are obvious interface problems between inorganic flame retardants and thermoplastic polyurethane elastomers. Adding a small amount cannot achieve a good modification effect, and adding a large amount will cause a loss of mechanical properties of the material. Based on this, the present invention provides a TPU elastomer with good comprehensive performance, which can be directly applied to the field of wires and cables and can solve the problems existing in the prior art. Summary of the Invention

[0005] (1) Technical problems solved In view of the deficiencies in the prior art, the present invention provides a wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables and a preparation method thereof.

[0006] (2) Technical solution A wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables, comprising the following raw materials in parts by weight: 65-85 parts of thermoplastic polyurethane elastomer, 3-6.5 parts of modified nano-molybdenum disulfide, 2-3 parts of lubricant, 0.5-1 part of UV absorber, and 0.5-1.5 parts of antioxidant; The modified nano molybdenum disulfide is prepared by modifying the surface of the nano molybdenum disulfide with a multi-element flame retardant modifier.

[0007] As a further embodiment of the present invention, the preparation method of the modified nano-molybdenum disulfide is as follows: Add nano-molybdenum disulfide and toluene into a reactor, ultrasonically disperse until a uniform dispersion is formed, and introduce nitrogen for protection. Then, add a multi-component flame retardant modifier and an organic tin catalyst into the reactor. After the addition is completed, stir and mix evenly. Then, heat and raise the temperature to 70-80°C. After keeping warm and stirring for 6-9 hours, remove the nitrogen, stop heating, separate the solid material, wash, and vacuum dry to obtain modified nano-molybdenum disulfide.

[0008] As a further embodiment of the present invention, the preparation method of the multi-element flame retardant modifier comprises the following steps: Step 1: Add N-(P-maleimidophenyl) isocyanate and N,N-dimethylformamide to a reactor filled with nitrogen. After the addition is completed, stir and mix evenly. Then, add dimethylchlorosilane to the reactor. Then, increase the temperature to 80-90°C, continue to add platinum catalyst to the reactor, keep stirring for 8-12 hours, evaporate and remove the solvent, collect the product, and prepare a modifier intermediate. Step 2: Add the modifier intermediate and flame retardant FRC-2 to tetrahydrofuran, start stirring, mix evenly, then add the acid binder to the formed mixed solution, then increase the temperature to 50-60°C, and continue stirring for 4-8 hours to obtain the multi-component flame retardant modifier.

[0009] As a further embodiment of the present invention, in step 1, the molar ratio of N-(P-maleimidophenyl)isocyanate to dimethylchlorosilane is 1:1.

[0010] As a further embodiment of the present invention, in step 1, the mass of the platinum catalyst added is 0.1%-0.3% of the total mass of N-(P-maleimidophenyl)isocyanate and dimethylchlorosilane.

[0011] As a further embodiment of the present invention, in step 2, the acid binding agent is pyridine.

[0012] As a further solution of the present invention, the mass ratio of the nano-molybdenum disulfide to the multi-component flame retardant modifier is 1:1.5-2.

[0013] As a further embodiment of the present invention, the organotin catalyst is any one of dibutyltin diacetate, methyltin mercaptan, octyltin mercaptan, dibutyltin dilaurate or stannous octoate.

[0014] In the above technical solution, N-(P-maleimidophenyl) isocyanate and dimethylchlorosilane are first used as reactants. Under the action of a platinum catalyst, the unsaturated olefinic groups in their structures undergo a hydrosilylation reaction with Si-H bonds to produce a modifier intermediate. Subsequently, under the action of an acid-binding agent, the Si-Cl in its structure can be substituted with the active hydroxyl substituent in the structure of the flame retardant FRC-2, thereby producing a multi-component flame retardant modifier containing nitrogen, phosphorus, and silicon ternary flame retardant elements in its structure.

[0015] The multi-element flame retardant modifier contains highly active isocyanate groups in its structure, which can react with the hydroxyl groups on the surface of nano-molybdenum disulfide under the action of an organic tin catalyst, thereby achieving surface modification of nano-molybdenum disulfide to obtain modified nano-molybdenum disulfide.

[0016] As a further embodiment of the present invention, the lubricant is any one of calcium stearate, zinc stearate or polyethylene wax; the ultraviolet absorber is any one of ultraviolet absorber UV-9, ultraviolet absorber UV-P or ultraviolet absorber UV-531; and the antioxidant is at least one of antioxidant 168, antioxidant 1010 or antioxidant 1076.

[0017] A method for preparing a wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables, comprising the following steps: The first step is to weigh each raw material according to the weight and set aside; The second step is to add the raw materials into the mixer, set the temperature to 60-80 ° C, and mechanically stir and mix at a stirring rate of 1000-2000 r / min for 5-10 minutes. Then, the formed mixture is transferred to the twin-screw extruder, and the temperature of the extruder feeding zone is controlled to 180-190 ° C, the temperature of the plasticizing zone is controlled to 190-200 ° C, the head temperature is controlled to 200-210 ° C, and the screw speed is controlled to 70-80 rpm. The extrusion granulation process is carried out.

[0018] (3) Beneficial technical effects The present invention modifies the surface of nano-molybdenum disulfide with a multi-element flame retardant modifier containing nitrogen, phosphorus, and silicon ternary flame retardant elements to obtain modified nano-molybdenum disulfide, which is used as an additive to modify thermoplastic polyurethane elastomer. First, the presence of the multi-element flame retardant modifier can play a bridging role, effectively improving the interface problem between the nano-molybdenum disulfide and the thermoplastic polyurethane elastomer, which is conducive to the uniform dispersion of the nano-molybdenum disulfide. Therefore, the inherent advantages of the nano-molybdenum disulfide can be efficiently utilized to improve the wear resistance and mechanical strength of the elastomer. Secondly, the multi-element flame retardant modifier structure contains a large amount of flame retardant elements, which can quickly form an expanded carbon layer on the surface of the elastomer when combustion occurs, isolating oxygen and heat, while the silicon element can increase the surface strength of the expanded carbon layer, prevent collapse, and thus prevent the combustion from continuing to the inside of the elastomer. At the same time, the evenly dispersed nano-molybdenum disulfide can form a physical barrier layer, which cooperates with the expanded carbon layer to achieve the effect of significantly enhancing the flame retardant properties of the elastomer by adding a small amount of it. DETAILED DESCRIPTION

[0019] To facilitate understanding of the present invention, the present invention will be described in more detail below. Preferred embodiments of the present invention are provided below. However, the present invention 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 comprehensive understanding of the disclosure of the present invention.

[0020] Example 1 A wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables, comprising the following raw materials in parts by weight: 65 parts of thermoplastic polyurethane elastomer, 3 parts of modified nano molybdenum disulfide, 2 parts of lubricant calcium stearate, 0.5 parts of ultraviolet absorber UV-9, and 0.5 parts of antioxidant 168; The preparation method of the TPU elastomer comprises the following steps: The first step is to weigh each raw material according to the weight and set aside; The second step is to add all the raw materials into the mixer, set the temperature to 60 ° C, and mechanically stir and mix at a stirring rate of 1000 r / min for 5 minutes. Then, transfer the formed mixture to the twin-screw extruder, control the temperature of the extruder feeding zone to 180 ° C, the temperature of the plasticizing zone to 190 ° C, the head temperature to 200 ° C, and the screw speed to 80 rpm, and carry out the extrusion granulation process.

[0021] The preparation method of modified nano molybdenum disulfide comprises the following steps: Step S1, adding 2 g of N-(P-maleimidophenyl) isocyanate and N,N-dimethylformamide to a reactor filled with nitrogen, starting stirring and mixing evenly, then adding 0.88 g of dimethylchlorosilane to the reactor, then raising the temperature to 85° C., continuing to add 0.003 g of platinum catalyst to the reactor, keeping the temperature and stirring for 9 hours, evaporating the solvent, and collecting the product to obtain a modifier intermediate; Step S2: add 0.5 g of the modifier intermediate and 0.34 g of the flame retardant FRC-2 to tetrahydrofuran, start stirring, and mix evenly. Then, add 0.01 g of pyridine to the formed mixed solution, then increase the temperature to 55° C. and continue stirring for 6 hours to obtain a multi-component flame retardant modifier.

[0022] Step S3, adding 1.2g of nano-molybdenum disulfide and toluene to the reactor, ultrasonically dispersing until a uniform dispersion is formed, introducing nitrogen protection, then adding 2g of multi-component flame retardant modifier and 0.1g of dibutyltin dilaurate to the reactor, after the addition is completed, stirring is started, after mixing evenly, heating is turned on, the temperature is raised to 75°C, and after keeping warm and stirring for 8h, the nitrogen is removed, the heating is stopped, the solid material is separated, and after washing and vacuum drying, the modified nano-molybdenum disulfide can be obtained.

[0023] Example 2 A wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables, comprising the following raw materials in parts by weight: 70 parts of thermoplastic polyurethane elastomer, 6 parts of modified nano molybdenum disulfide, 2.5 parts of lubricant zinc stearate, 0.6 parts of ultraviolet absorber UV-9, 1 part of antioxidant 1010; The preparation method of the TPU elastomer comprises the following steps: The first step is to weigh each raw material according to the weight and set aside; The second step is to add all the raw materials into the mixer, set the temperature to 70 ° C, and mechanically stir and mix at a stirring rate of 1500 r / min for 5 minutes. Then, transfer the formed mixture to the twin-screw extruder, control the temperature of the extruder feeding zone to 185 ° C, the temperature of the plasticizing zone to 195 ° C, the head temperature to 200 ° C, and the screw speed to 80 rpm, and carry out the extrusion granulation process.

[0024] The preparation method of modified nano-molybdenum disulfide is the same as that in Example 1.

[0025] Example 3 A wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables, comprising the following raw materials in parts by weight: 85 parts of thermoplastic polyurethane elastomer, 6.5 parts of modified nano molybdenum disulfide, 3 parts of lubricant zinc stearate, 1 part of ultraviolet absorber UV-P, and 1.5 parts of antioxidant 1076; The preparation method of the TPU elastomer comprises the following steps: The first step is to weigh each raw material according to the weight and set aside; The second step is to add all the raw materials into the mixer, set the temperature to 80 ° C, and mechanically stir and mix at a stirring rate of 2000 r / min for 5 minutes. Then, transfer the formed mixture to the twin-screw extruder, control the temperature of the extruder feeding zone to 190 ° C, the temperature of the plasticizing zone to 200 ° C, the head temperature to 210 ° C, and the screw speed to 80 rpm, and carry out the extrusion granulation process.

[0026] The preparation method of modified nano-molybdenum disulfide is the same as that in Example 1.

[0027] Comparative Example 1 A TPU elastomer, comprising the following raw materials in parts by weight: 70 parts of thermoplastic polyurethane elastomer, 6 parts of nano-molybdenum disulfide, 2.5 parts of lubricant zinc stearate, 0.6 parts of ultraviolet absorber UV-9, 1 part of antioxidant 1010; The preparation method of the TPU elastomer comprises the following steps: The first step is to weigh each raw material according to the weight and set aside; The second step is to add all the raw materials into the mixer, set the temperature to 70 ° C, and mechanically stir and mix at a stirring rate of 1500 r / min for 5 minutes. Then, transfer the formed mixture to the twin-screw extruder, control the temperature of the extruder feeding zone to 185 ° C, the temperature of the plasticizing zone to 195 ° C, the head temperature to 200 ° C, and the screw speed to 80 rpm, and carry out the extrusion granulation process.

[0028] Comparative Example 2 A TPU elastomer, comprising the following raw materials in parts by weight: 70 parts of thermoplastic polyurethane elastomer, 2.5 parts of lubricant zinc stearate, 0.6 parts of ultraviolet absorber UV-9, 1 part of antioxidant 1010; The preparation method of the TPU elastomer comprises the following steps: The first step is to weigh each raw material according to the weight and set aside; The second step is to add all the raw materials into the mixer, set the temperature to 70 ° C, and mechanically stir and mix at a stirring rate of 1500 r / min for 5 minutes. Then, transfer the formed mixture to the twin-screw extruder, control the temperature of the extruder feeding zone to 185 ° C, the temperature of the plasticizing zone to 195 ° C, the head temperature to 200 ° C, and the screw speed to 80 rpm, and carry out the extrusion granulation process.

[0029] Performance Testing The elastomers in the examples and comparative examples were made into samples that met the test specifications, and various performance tests were performed. The results are recorded in the following table: Table 1 - Test results

[0030] The wear resistance was tested according to the ASTM D3884 standard, using an SC10 grinding wheel, a 1000g load, and 5000 tests. The tensile performance was tested according to the GB / T 1040.1-2018 standard, with a tensile speed of 50mm / min. The limiting oxygen index was tested according to the GB / T 2406.2-2009 standard.

[0031] From the analysis and test results, it can be seen that the elastomer prepared in the embodiment of the present invention has obviously better performance in various aspects. However, after the modified nano-molybdenum disulfide is replaced with nano-molybdenum disulfide that has not been surface-modified, due to the interface problem between it and the thermoplastic polyurethane elastomer substrate, it cannot be evenly dispersed and thus cannot efficiently exert its own effectiveness, so all performances are significantly reduced.

[0032] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in this field to practice the present invention, including implementing any combined methods. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

[0033] Based on the ideal embodiments of the present invention, and with reference to the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables, characterized in that: According to parts by weight, it includes the following raw materials: 65-85 parts of thermoplastic polyurethane elastomer, 3-6.5 parts of modified nano-molybdenum disulfide, 2-3 parts of lubricant, 0.5-1 part of UV absorber, and 0.5-1.5 parts of antioxidant; The modified nano-molybdenum disulfide is prepared by modifying the surface of nano-molybdenum disulfide with a multi-component flame retardant modifier; The preparation method of the multi-component flame retardant modifier comprises the following steps: Step 1: Add N-(P-maleimidophenyl) isocyanate and N,N-dimethylformamide to a reactor filled with nitrogen. After the addition is completed, stir and mix evenly. Then, add dimethylchlorosilane to the reactor. Then, increase the temperature to 80-90°C, continue to add platinum catalyst to the reactor, keep stirring for 8-12 hours, evaporate and remove the solvent, collect the product, and prepare a modifier intermediate. Step 2: Add the modifier intermediate and flame retardant FRC-2 to tetrahydrofuran, start stirring, mix evenly, then add the acid binder to the formed mixed solution, then increase the temperature to 50-60°C, and continue stirring for 4-8 hours to obtain the multi-component flame retardant modifier.

2. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 1, characterized in that: The preparation method of the modified nano molybdenum disulfide is as follows: Add nano-molybdenum disulfide and toluene into a reactor, ultrasonically disperse until a uniform dispersion is formed, and introduce nitrogen for protection. Then, add a multi-component flame retardant modifier and an organic tin catalyst into the reactor. After the addition is completed, stir and mix evenly. Then, heat and raise the temperature to 70-80°C. After keeping warm and stirring for 6-9 hours, remove the nitrogen, stop heating, separate the solid material, wash, and vacuum dry to obtain modified nano-molybdenum disulfide.

3. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 2, characterized in that: The mass ratio of the nano-molybdenum disulfide to the multi-component flame retardant modifier is 1:1.5-2.

4. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 2, characterized in that: The organic tin catalyst is any one of dibutyltin diacetate, methyltin mercaptan, octyltin mercaptan, dibutyltin dilaurate or stannous octoate.

5. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 1, characterized in that: In step 1, the molar ratio of N-(P-maleimidophenyl)isocyanate to dimethylchlorosilane is 1:

1.

6. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 1, characterized in that: In step 1, the mass of the platinum catalyst added is 0.1%-0.3% of the total mass of N-(P-maleimidophenyl)isocyanate and dimethylchlorosilane.

7. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 1, characterized in that: In step 2, the acid binding agent is pyridine.

8. The wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 1, characterized in that: The lubricant is any one of calcium stearate, zinc stearate or polyethylene wax; the ultraviolet absorber is any one of ultraviolet absorber UV-9, ultraviolet absorber UV-P or ultraviolet absorber UV-531; the antioxidant is at least one of antioxidant 168, antioxidant 1010 or antioxidant 1076.

9. A method for preparing the wear-resistant, halogen-free, flame-retardant TPU elastomer for wires and cables according to claim 1, characterized in that: The following steps are involved: The first step is to weigh each raw material according to the weight and set aside; The second step is to add the raw materials into the mixer, set the temperature to 60-80 ° C, and mechanically stir and mix at a stirring rate of 1000-2000 r / min for 5-10 minutes. Then, the formed mixture is transferred to the twin-screw extruder, and the temperature of the extruder feeding zone is controlled to 180-190 ° C, the temperature of the plasticizing zone is controlled to 190-200 ° C, the head temperature is controlled to 200-210 ° C, and the screw speed is controlled to 70-80 rpm. The extrusion granulation process is carried out.

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