Low-smoke halogen-free flame-retardant TPU cable material and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a low-smoke halogen-free flame-retardant TPU (thermoplastic polyurethane) cable material and a preparation method thereof.The cable material is prepared by taking a thermoplastic polyurethane elastomer as a base material and a composite flame-retardant modifier, an antioxidant and the like as auxiliary materials through mixing, melt extrusion and granulation. Wherein the composite flame-retardant modifier is prepared by modifying the surface of perlite with an organic phosphorus-containing flame retardant, the compatibility between the perlite and a thermoplastic polyurethane elastomer can be improved due to the existence of the organic phosphorus-containing flame retardant, so that the perlite can be uniformly dispersed in the TPU cable material, the mechanical strength of the cable material is further improved, and when the cable material burns, the flame-retardant property of the cable material is improved. In the presence of the organic phosphorus-containing flame retardant, an expanded carbon layer can be rapidly formed on the surface of the cable material to prevent continuous combustion, and the uniformly dispersed perlite can absorb smoke generated by combustion by using a vitreous porous structure of the perlite, so that low-smoke halogen-free flame-retardant modification of the TPU cable material is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a low-smoke, halogen-free, flame-retardant TPU cable material and a preparation method thereof. Background Art

[0002] Thermoplastic polyurethane (TPU), with its unique molecular structure, is an ideal choice for flexible cable sheathing. Its core advantages include excellent mechanical properties, enabling it to withstand the rigors of dynamic cable bending, repeated flexing, and dragging. It also offers excellent processability, allowing it to be formed through extrusion and injection molding without the need for vulcanization. These properties have led to its widespread application in the power and energy, communications, automotive, industrial control, and medical equipment sectors. Demand is particularly rapidly growing in confined spaces such as subways, locomotives, and ships, as well as in large public buildings.

[0003] Although TPU has many advantages, its poor flame retardancy has always been an important factor restricting its sustainable development. The limiting oxygen index of unmodified TPU is only 17%-20%, and it cannot pass the UL-94 V-0 level in the vertical burning test, which can easily cause flame spread. In addition, conventional TPU produces a large amount of black smoke and toxic gases (such as CO and HCN) when burning, resulting in low visibility at the fire scene. The mortality rate of people after inhaling toxic gases is much higher than direct burns from the flames.

[0004] Currently, the problem of poor flame retardancy of TPU is generally addressed by adding flame retardants, such as halogen flame retardants, phosphorus flame retardants, and inorganic flame retardants. However, these flame retardants all have significant drawbacks in practical applications. Halogen flame retardants, in particular, produce large amounts of toxic gases during combustion, posing a safety hazard. Phosphorus flame retardants are mostly small molecules and are prone to migration. Inorganic flame retardants are generally less effective and require a large addition amount. Based on this, the present invention provides a TPU cable material with excellent flame retardant properties that can address 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 low-smoke, halogen-free, flame-retardant TPU cable material and a preparation method thereof.

[0006] (2) Technical solution A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials in parts by weight: 65-85 parts of thermoplastic polyurethane elastomer, 2-6.5 parts of composite flame retardant modifier, 0.5-1.5 parts of antioxidant, 1-3 parts of lubricant, 0.5-1.5 parts of UV absorber; The composite flame retardant modifier is perlite with an organic phosphorus flame retardant modified on the surface.

[0007] As a further embodiment of the present invention, the preparation method of the composite flame retardant modifier comprises the following steps: Step 1: Modify perlite with silane coupling agent The perlite is dispersed in a mixed solution of ethanol and deionized water in a volume ratio of 1:1. Then, a silane coupling agent is added to the formed dispersion. After the addition is completed, the temperature is raised to 70-80°C, and stirring is continued for 4-8 hours. Then, heating is stopped, the temperature is lowered, and the material is discharged to obtain the modified perlite. Step 2: Preparation of perlite intermediate The modified perlite is added to toluene and dispersed uniformly by ultrasonication. Then, 2-phenyl-4,7-di(4-carboxyphenyl)-1H-benzimidazole and a phase transfer catalyst are added to the resulting dispersion. After the addition is completed, heating is started and the temperature is maintained at 60-70° C. The mixture is stirred for 6-9 hours, and the solid material is centrifuged, washed, and vacuum-dried to obtain a perlite intermediate. Step 3: Preparation of composite flame retardant modifier The perlite intermediate is added to N,N-dimethylformamide. After the addition is completed, ultrasonication is performed to form a uniform dispersion. Then, the active phosphorus-containing flame retardant and the catalyst are added to the dispersion. After the addition is completed, nitrogen is introduced for protection. The temperature is raised to 100-110°C and kept warm for 6-12 hours. Then, heating is stopped, the temperature is lowered, and the material is discharged to obtain a composite flame retardant modifier.

[0008] As a further embodiment of the present invention, in step 1, the silane coupling agent is 3-glycidyloxypropyltrimethoxysilane or 3-glycidyloxypropyltriethoxysilane.

[0009] As a further embodiment of the present invention, in step 2, the mass ratio of the modified perlite to 2-phenyl-4,7-di(4-carboxyphenyl)-1H-benzimidazole is 1:0.2-0.4.

[0010] As a further embodiment of the present invention, in step 2, the phase transfer catalyst is any one of tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide, and tetramethylammonium chloride.

[0011] As a further embodiment of the present invention, in step three, the active phosphorus-containing flame retardant is any one of flame retardant FRC-2, flame retardant FRC-6 or 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide.

[0012] As a further embodiment of the present invention, in step three, the catalyst is p-toluenesulfonic acid or aminosulfonic acid.

[0013] As a further embodiment of the present invention, in step three, the mass ratio of the perlite intermediate to the active phosphorus-containing flame retardant is 1:0.1-0.2.

[0014] In the above technical solution, the surface of perlite is first modified with a silane coupling agent to obtain perlite containing epoxy substituents on the surface, thereby obtaining modified perlite. Then, under the action of a phase transfer catalyst, the active carboxyl substituent at one end of the 2-phenyl-4,7-di(4-carboxyphenyl)-1H-benzimidazole structure can undergo ring-opening esterification with the epoxy substituent of the modified perlite to obtain a perlite intermediate. Finally, under the action of a catalyst, the active carboxyl substituent in the perlite intermediate that does not participate in the reaction can undergo esterification condensation with the hydroxyl substituent in the structure of the active phosphorus-containing flame retardant, thereby obtaining perlite surface-modified with an organophosphorus flame retardant, i.e., a composite flame retardant modifier.

[0015] As a further embodiment of the present invention, the antioxidant is at least one of antioxidant 1098, antioxidant 1076, antioxidant 168 or antioxidant 1010; the lubricant is at least one of calcium stearate, zinc stearate or polyethylene wax; and the ultraviolet absorber is any one of ultraviolet absorber UV-9, ultraviolet absorber UV-P or ultraviolet absorber UV-531.

[0016] A method for preparing a low-smoke, halogen-free, flame-retardant TPU cable material comprises the following steps: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; The second step is to put the premix into a twin-screw extruder, control the extrusion temperature to 200-210°C and the screw speed to 200-240rpm, and obtain TPU cable material through melt extrusion process.

[0017] (3) Beneficial technical effects The present invention prepares an organic-inorganic synergistic composite flame retardant modifier by modifying the surface of perlite with an organic phosphorus-containing flame retardant. First, the presence of the organic phosphorus-containing flame retardant can serve as a transition structure between the perlite and the thermoplastic polyurethane elastomer, greatly improving the compatibility between them and enabling the perlite to be evenly dispersed in the TPU cable material, which is beneficial for utilizing the inorganic properties of the perlite itself to improve the mechanical strength of the cable material. Secondly, when the cable material burns, the nitrogen element in the structure of the organic phosphorus-containing flame retardant can serve as a gas source, and the phosphorus element provides an acid source, so that an expanded carbon layer is quickly formed on the surface of the cable material to prevent continued combustion. The evenly dispersed perlite can also utilize its own glassy porous structure to absorb the smoke generated by the combustion, thereby achieving low-smoke halogen-free flame retardant modification of the TPU cable material. DETAILED DESCRIPTION

[0018] 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.

[0019] Preparation Example Preparation of composite flame retardant modifier: Step 1: Modify perlite with silane coupling agent 1.2 g of perlite was dispersed in a mixed solution of ethanol and deionized water in a volume ratio of 1:1. Then, 1.5 g of 3-glycidoxypropyltriethoxysilane was added to the resulting dispersion. After the addition, the temperature was raised to 75° C. and stirred for 6 h. The heating was stopped, the temperature was lowered, and the material was discharged to obtain modified perlite. Step 2: Preparation of perlite intermediate 1 g of modified perlite was added to toluene and dispersed uniformly by ultrasonication. Then, 0.3 g of 2-phenyl-4,7-di(4-carboxyphenyl)-1H-benzimidazole and 0.1 g of tetrabutylammonium bromide were added to the resulting dispersion. After the addition was completed, heating was started and the temperature was maintained at 65° C. After stirring for 8 hours, the solid material was centrifuged, washed, and vacuum-dried to obtain a perlite intermediate. Step 3: Preparation of composite flame retardant modifier Add 0.5 g of perlite intermediate to N,N-dimethylformamide. After the addition is completed, ultrasonicate to form a uniform dispersion. Then, add 0.08 g of 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide and 0.01 g of p-toluenesulfonic acid to the dispersion. After the addition is completed, introduce nitrogen protection, raise the temperature to 100°C, keep warm for 9 hours, stop heating, cool and discharge the material to obtain a composite flame retardant modifier.

[0020] Example 1 A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials in parts by weight: 65 parts of thermoplastic polyurethane elastomer, 2 parts of composite flame retardant modifier, 0.5 parts of antioxidant 1098, 1 part of lubricant calcium stearate, and 0.5 parts of ultraviolet absorber UV-9; The preparation method of the TPU cable material comprises the following steps: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; The second step is to put the premix into a twin-screw extruder, control the extrusion temperature to 200°C and the screw speed to 200 rpm, and obtain TPU cable material through a melt extrusion process.

[0021] The preparation method of the composite flame retardant modifier is shown in the preparation example, and the following are the same.

[0022] Example 2 A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials in parts by weight: 70 parts of thermoplastic polyurethane elastomer, 5 parts of composite flame retardant modifier, 1 part of antioxidant 1076, 2 parts of lubricant zinc stearate, 1 part of ultraviolet absorber UV-P; The preparation method of the TPU cable material comprises the following steps: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; In the second step, the premix is ​​put into a twin-screw extruder, the extrusion temperature is controlled at 210°C and the screw speed is 220 rpm, and the TPU cable material is obtained through a melt extrusion process.

[0023] Example 3 A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials in parts by weight: 85 parts of thermoplastic polyurethane elastomer, 6.5 parts of composite flame retardant modifier, 1.5 parts of antioxidant 1076, 3 parts of lubricant polyethylene wax, 1.5 parts of ultraviolet absorber UV-531; The preparation method of the TPU cable material comprises the following steps: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; The second step is to put the premix into a twin-screw extruder, control the extrusion temperature to 210°C and the screw speed to 240 rpm, and obtain TPU cable material through a melt extrusion process.

[0024] Comparative Example 1 A TPU cable material, comprising the following raw materials in parts by weight: 70 parts of thermoplastic polyurethane elastomer, 5 parts of perlite, 1 part of antioxidant 1076, 2 parts of lubricant zinc stearate, 1 part of ultraviolet absorber UV-P; The preparation method of the TPU cable material comprises the following steps: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; In the second step, the premix is ​​put into a twin-screw extruder, the extrusion temperature is controlled at 210°C and the screw speed is 220 rpm, and the TPU cable material is obtained through a melt extrusion process.

[0025] Comparative Example 2 A TPU cable material, comprising the following raw materials in parts by weight: 70 parts of thermoplastic polyurethane elastomer, 1 part of antioxidant 1076, 2 parts of lubricant zinc stearate, 1 part of ultraviolet absorber UV-P; The preparation method of the TPU cable material comprises the following steps: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; In the second step, the premix is ​​put into a twin-screw extruder, the extrusion temperature is controlled at 210°C and the screw speed is 220 rpm, and the TPU cable material is obtained through a melt extrusion process.

[0026] Performance Testing The cable materials in the examples and comparative examples were made into test samples that met the specifications and subjected to various performance tests. The tensile strength was tested according to the standard GB / T 1040.1-2018 at a tensile rate of 50 mm / min; the limiting oxygen index was tested according to the standard GB / T 2406.2-2009; and the smoke density was tested according to the standard GB / T 8323.2-2008. The test results are recorded in the following table: Table 1 - Test results

[0027] Analysis and test results show that the cable material prepared in the embodiment of the present invention has excellent mechanical properties, good flame retardant properties and low smoke density. After the composite flame retardant modifier is replaced with perlite without surface modification, due to the existence of interface problems, the perlite is difficult to achieve uniform dispersion, and the surface-modified organic phosphorus-containing flame retardant is lost, resulting in a significant decrease in the performance of the prepared cable material.

[0028] 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.

[0029] 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 low-smoke, halogen-free, flame-retardant TPU cable material, characterized in that: According to parts by weight, the following raw materials are included: 65-85 parts of thermoplastic polyurethane elastomer, 2-6.5 parts of composite flame retardant modifier, 0.5-1.5 parts of antioxidant, 1-3 parts of lubricant, 0.5-1.5 parts of UV absorber; The composite flame retardant modifier is perlite with an organic phosphorus flame retardant modified on the surface.

2. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 1, characterized in that: The preparation method of the composite flame retardant modifier comprises the following steps: Step 1: Modify perlite with silane coupling agent The perlite is dispersed in a mixed solution of ethanol and deionized water in a volume ratio of 1:

1. Then, a silane coupling agent is added to the formed dispersion. After the addition is completed, the temperature is raised to 70-80°C, and stirring is continued for 4-8 hours. Then, heating is stopped, the temperature is lowered, and the material is discharged to obtain the modified perlite. Step 2: Preparation of perlite intermediate The modified perlite is added to toluene and dispersed uniformly by ultrasonication. Then, 2-phenyl-4,7-di(4-carboxyphenyl)-1H-benzimidazole and a phase transfer catalyst are added to the resulting dispersion. After the addition is completed, heating is started and the temperature is maintained at 60-70° C. The mixture is stirred for 6-9 hours, and the solid material is centrifuged, washed, and vacuum-dried to obtain a perlite intermediate. Step 3: Preparation of composite flame retardant modifier The perlite intermediate is added to N,N-dimethylformamide. After the addition is completed, ultrasonication is performed to form a uniform dispersion. Then, the active phosphorus-containing flame retardant and the catalyst are added to the dispersion. After the addition is completed, nitrogen is introduced for protection. The temperature is raised to 100-110°C and kept warm for 6-12 hours. Then, heating is stopped, the temperature is lowered, and the material is discharged to obtain a composite flame retardant modifier.

3. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 2, characterized in that: In step 1, the silane coupling agent is 3-glycidyloxypropyltrimethoxysilane or 3-glycidyloxypropyltriethoxysilane.

4. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 2, characterized in that: In step 2, the mass ratio of the modified perlite to 2-phenyl-4,7-di(4-carboxyphenyl)-1H-benzimidazole is 1:0.2-0.

4.

5. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 2, characterized in that: In step 2, the phase transfer catalyst is any one of tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide, and tetramethylammonium chloride.

6. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 2, characterized in that: In step 3, the active phosphorus-containing flame retardant is any one of flame retardant FRC-2, flame retardant FRC-6 or 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide.

7. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 2, characterized in that: In step 3, the catalyst is p-toluenesulfonic acid or aminosulfonic acid.

8. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 2, characterized in that: In step 3, the mass ratio of the perlite intermediate to the active phosphorus-containing flame retardant is 1:0.1-0.

2.

9. The low-smoke, halogen-free, flame-retardant TPU cable material according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1098, antioxidant 1076, antioxidant 168 or antioxidant 1010; the lubricant is at least 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.

10. A method for preparing the low-smoke, halogen-free, flame-retardant TPU cable material according to claim 1, characterized in that: The following steps are involved: The first step is to weigh all the raw materials according to their weight, add them into a high-speed mixer, and mechanically mix them evenly to form a premix; The second step is to put the premix into a twin-screw extruder, control the extrusion temperature to 200-210°C and the screw speed to 200-240rpm, and obtain TPU cable material through melt extrusion process.

Images