A low-smoke, halogen-free flame-retardant TPU cable material and its preparation method

Abstract

This invention relates to the field of materials technology and discloses a low-smoke, halogen-free flame-retardant TPU cable material and its preparation method. This cable material uses thermoplastic polyurethane elastomer as the base material and composite flame-retardant modifiers and antioxidants as auxiliary materials, obtained through mixing, melt extrusion, and granulation. The composite flame-retardant modifier is obtained by modifying the surface of perlite with an organic phosphorus-containing flame retardant. The presence of the organic phosphorus-containing flame retardant improves the compatibility between perlite and thermoplastic polyurethane elastomer, allowing perlite to be uniformly dispersed in the TPU cable material, thereby improving the mechanical strength of the cable material. When the cable material burns, the presence of the organic phosphorus-containing flame retardant enables the rapid formation of an expanding carbon layer on the surface of the cable material, preventing the combustion from continuing. The uniformly dispersed perlite can also absorb the smoke generated by combustion using its glassy porous structure, thus achieving low-smoke, halogen-free flame-retardant modification of the TPU cable material.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a low-smoke, halogen-free flame-retardant TPU cable material and its preparation method. Background Technology

[0002] Thermoplastic polyurethane elastomer (TPU), with its unique molecular structure, has become an ideal choice for flexible cable sheathing materials. Its core advantages include excellent mechanical properties, capable of withstanding harsh conditions such as repeated bending and dragging of dynamic cables, as well as good processability, allowing it to be molded through extrusion, injection molding, and other processes without vulcanization. Based on these characteristics, TPU has been widely used in power energy, communications, automotive, industrial control, medical equipment, and other fields, especially in enclosed spaces such as subways, locomotives, and ships, as well as large public buildings, where its demand is experiencing rapid growth.

[0003] Despite its many advantages, TPU's poor flame retardancy has been a major factor limiting its continued development. Unmodified TPU has a limiting oxygen index of only 17%-20%, and it cannot pass the UL-94 V-0 rating in vertical burning tests, making it prone to flame spread. Moreover, 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. Furthermore, the mortality rate from inhaling toxic gases is much higher than that from direct burns from flames.

[0004] Currently, the poor flame retardancy of TPU is generally addressed by adding flame retardants, such as halogenated, phosphorus-based, and inorganic flame retardants. However, these flame retardants all have significant drawbacks in practical applications. Halogenated flame retardants produce large amounts of toxic gases during combustion, posing a safety hazard. Phosphorus-based flame retardants are mostly small molecules, leading to migration problems. Inorganic flame retardants generally have poor performance and require large dosages. Therefore, this invention provides a TPU cable material with excellent flame retardant properties, solving the problems existing in the prior art. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a low-smoke, halogen-free flame-retardant TPU cable material and its preparation method.

[0007] (II) Technical Solution

[0008] A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials by weight:

[0009] The composition includes 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, and 0.5-1.5 parts of ultraviolet absorber.

[0010] The composite flame retardant modifier is perlite with an organophosphorus flame retardant modified on its surface.

[0011] As a further aspect of the present invention, the preparation method of the composite flame retardant modifier includes the following steps:

[0012] Step 1: Modification of perlite with silane coupling agent

[0013] Perlite was dispersed in a mixed solution of ethanol and deionized water with a volume ratio of 1:1. Then, silane coupling agent was added to the resulting dispersion. After the addition was complete, the temperature was raised to 70-80℃ and stirred continuously for 4-8 hours. Heating was then stopped, the material was cooled and discharged to obtain modified perlite.

[0014] Step 2: Preparation of perlite intermediate

[0015] Modified perlite was added to toluene and ultrasonically dispersed evenly. Then, 2-phenyl-4,7-bis(4-carboxyphenyl)-1H-benzimidazole and phase transfer catalyst were added to the dispersion. After the addition was complete, heating was started and the temperature was maintained at 60-70℃. After stirring for 6-9 hours, the solid material was centrifuged, washed, and vacuum dried to obtain the perlite intermediate.

[0016] Step 3: Preparation of composite flame retardant modifier

[0017] Perlite intermediates are added to N,N-dimethylformamide. After addition, the mixture is sonicated until a uniform dispersion is formed. Then, an active phosphorus-containing flame retardant and a catalyst are added to the dispersion. After addition, nitrogen gas is introduced for protection, and the temperature is raised to 100-110℃. The temperature is maintained for 6-12 hours, then heating is stopped, the mixture is cooled, and the material is discharged to obtain the composite flame retardant modifier.

[0018] As a further aspect of the present invention, in step one, the silane coupling agent is 3-glycidyl etheroxypropyltrimethoxysilane or 3-glycidyl etheroxypropyltriethoxysilane.

[0019] As a further aspect of the present invention, in step two, the mass ratio of the modified perlite to 2-phenyl-4,7-bis(4-carboxyphenyl)-1H-benzimidazole is 1:0.2-0.4.

[0020] As a further aspect of the present invention, in step two, the phase transfer catalyst is any one of tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide, and tetramethylammonium chloride.

[0021] As a further aspect 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.

[0022] As a further embodiment of the present invention, in step three, the catalyst is p-toluenesulfonic acid or aminosulfonic acid.

[0023] As a further aspect 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.

[0024] In the above technical solution, perlite is first surface modified using a silane coupling agent to obtain perlite with epoxy substituents on the surface, thus 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-bis(4-carboxyphenyl)-1H-benzimidazole structure can undergo ring-opening esterification with the epoxy substituents of the modified perlite to obtain a perlite intermediate. Finally, under the action of a catalyst, the unreacted active carboxyl substituents in the perlite intermediate can undergo esterification condensation with the hydroxyl substituents in the structure of the active phosphorus-containing flame retardant to obtain perlite with an organophosphorus flame retardant modified on the surface, i.e., a composite flame retardant modifier.

[0025] 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.

[0026] A method for preparing a low-smoke, halogen-free, flame-retardant TPU cable material includes the following steps:

[0027] Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix.

[0028] The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature to 200-210℃ and the screw speed to 200-240rpm, and then obtain TPU cable material through melt extrusion process.

[0029] (iii) Beneficial technical effects

[0030] This 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 act as a transitional structure between perlite and thermoplastic polyurethane elastomer, greatly improving their compatibility and allowing perlite to be uniformly dispersed in TPU cable material. This facilitates the utilization of the inorganic properties of perlite itself, improving the mechanical strength of the cable material. Second, when the cable material burns, the nitrogen element in the organic phosphorus-containing flame retardant structure can act as a gas source, and the phosphorus element provides an acid source, causing an expanding carbon layer to quickly form on the surface of the cable material, preventing the combustion from continuing. The uniformly dispersed perlite can also absorb the smoke generated by combustion using its glassy porous structure, thereby achieving low-smoke halogen-free flame retardant modification of TPU cable material. Detailed Implementation

[0031] To facilitate understanding of the present invention, a more complete description will be provided below. Preferred embodiments of the invention are given below. However, the 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 thorough and complete understanding of the disclosure of the invention.

[0032] Preparation Example

[0033] Preparation of composite flame retardant modifiers:

[0034] Step 1: Modification of perlite with silane coupling agent

[0035] 1.2g of perlite was dispersed in a 1:1 mixture of ethanol and deionized water. Then, 1.5g of 3-glycidyl etheroxypropyltriethoxysilane was added to the resulting dispersion. After the addition was complete, the temperature was raised to 75°C and stirred continuously for 6 hours. Then, the heating was stopped, the material was cooled and discharged to obtain modified perlite.

[0036] Step 2: Preparation of perlite intermediate

[0037] 1g of modified perlite was added to toluene and ultrasonically dispersed evenly. Then, 0.3g of 2-phenyl-4,7-bis(4-carboxyphenyl)-1H-benzimidazole and 0.1g of tetrabutylammonium bromide were added to the dispersion. After the addition was complete, the heating was turned on and the temperature was maintained at 65℃. After stirring for 8 hours, the solid material was centrifuged, washed, and vacuum dried to obtain the perlite intermediate.

[0038] Step 3: Preparation of composite flame retardant modifier

[0039] 0.5g of perlite intermediate was added to N,N-dimethylformamide. After the addition was complete, the mixture was sonicated until a uniform dispersion was formed. Then, 0.08g of 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide and 0.01g of p-toluenesulfonic acid were added to the dispersion. After the addition was complete, nitrogen gas was introduced for protection, the temperature was raised to 100℃, and the temperature was maintained for 9 hours. Then, the heating was stopped, the material was cooled and discharged to obtain the composite flame retardant modifier.

[0040] Example 1

[0041] A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials by weight:

[0042] 65 parts thermoplastic polyurethane elastomer, 2 parts composite flame retardant modifier, 0.5 parts antioxidant 1098, 1 part calcium stearate lubricant, and 0.5 parts ultraviolet absorber UV-9;

[0043] The preparation method of the TPU cable material includes the following steps:

[0044] Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix.

[0045] The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature to 200℃ and the screw speed to 200rpm, and then obtain TPU cable material through melt extrusion process.

[0046] The preparation method of the composite flame retardant modifier is shown in the preparation example, and the same applies to the following.

[0047] Example 2

[0048] A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials by weight:

[0049] 70 parts thermoplastic polyurethane elastomer, 5 parts composite flame retardant modifier, 1 part antioxidant 1076, 2 parts lubricant zinc stearate, and 1 part ultraviolet absorber UV-P.

[0050] The preparation method of the TPU cable material includes the following steps:

[0051] Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix.

[0052] The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature at 210℃ and the screw speed at 220rpm, and then obtain TPU cable material through melt extrusion process.

[0053] Example 3

[0054] A low-smoke, halogen-free, flame-retardant TPU cable material, comprising the following raw materials by weight:

[0055] 85 parts thermoplastic polyurethane elastomer, 6.5 parts composite flame retardant modifier, 1.5 parts antioxidant 1076, 3 parts lubricant polyethylene wax, and 1.5 parts ultraviolet absorber UV-531;

[0056] The preparation method of the TPU cable material includes the following steps:

[0057] Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix.

[0058] The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature at 210℃ and the screw speed at 240rpm, and then obtain TPU cable material through melt extrusion process.

[0059] Comparative Example 1

[0060] A TPU cable material, by weight, comprises the following raw materials:

[0061] 70 parts thermoplastic polyurethane elastomer, 5 parts perlite, 1 part antioxidant 1076, 2 parts zinc stearate lubricant, and 1 part ultraviolet absorber UV-P.

[0062] The preparation method of the TPU cable material includes the following steps:

[0063] Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix.

[0064] The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature at 210℃ and the screw speed at 220rpm, and then obtain TPU cable material through melt extrusion process.

[0065] Comparative Example 2

[0066] A TPU cable material, by weight, comprises the following raw materials:

[0067] 70 parts thermoplastic polyurethane elastomer, 1 part antioxidant 1076, 2 parts lubricant zinc stearate, and 1 part ultraviolet absorber UV-P;

[0068] The preparation method of the TPU cable material includes the following steps:

[0069] Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix.

[0070] The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature at 210℃ and the screw speed at 220rpm, and then obtain TPU cable material through melt extrusion process.

[0071] Performance testing

[0072] The cable materials from the examples and comparative examples were made into test samples conforming to specifications, and various performance tests were conducted. Tensile strength was tested according to standard GB / T 1040.1-2018 at a tensile rate of 50 mm / min; limiting oxygen index was tested according to standard GB / T 2406.2-2009; and smoke density was tested according to standard GB / T 8323.2-2008. The test results are recorded in the table below:

[0073] Table 1 - Test Results

[0074]

[0075] Analysis of the test results shows that the cable material prepared in the embodiments of the present invention has excellent mechanical properties, good flame retardant properties and low smoke density. After replacing the composite flame retardant modifier with unmodified perlite, the perlite is difficult to achieve uniform dispersion due to interface problems. Moreover, the loss of the surface-modified organic phosphorus flame retardant leads to a significant reduction in the various properties of the prepared cable material.

[0076] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are merely for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including implementing any combination of methods. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the wording of the claims, or if they include equivalent structural elements that are not substantially different from the wording of the claims, then these other embodiments should also be included within the scope of the claims.

[0077] Based on the preferred embodiments of the present invention, and through the above description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this 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, By weight, it includes the following ingredients: The composition includes 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, and 0.5-1.5 parts of ultraviolet absorber. The composite flame retardant modifier is perlite with an organophosphorus flame retardant modified on its surface; The preparation method of the composite flame retardant modifier includes the following steps: Step 1: Modification of perlite with silane coupling agent Perlite was dispersed in a mixed solution of ethanol and deionized water with a volume ratio of 1:

1. Then, silane coupling agent was added to the resulting dispersion. After the addition was complete, the temperature was raised to 70-80℃ and stirred continuously for 4-8 hours. Heating was then stopped, the material was cooled and discharged to obtain modified perlite. Step 2: Preparation of perlite intermediate Modified perlite was added to toluene and ultrasonically dispersed evenly. Then, 2-phenyl-4,7-bis(4-carboxyphenyl)-1H-benzimidazole and phase transfer catalyst were added to the dispersion. After the addition was complete, heating was started and the temperature was maintained at 60-70℃. After stirring for 6-9 hours, the solid material was centrifuged, washed, and vacuum dried to obtain the perlite intermediate. Step 3: Preparation of composite flame retardant modifier Perlite intermediates are added to N,N-dimethylformamide. After the addition is complete, the mixture is sonicated until a uniform dispersion is formed. Then, an active phosphorus-containing flame retardant and a catalyst are added to the dispersion. After the addition is complete, nitrogen gas is introduced for protection. The temperature is raised to 100-110℃ and kept at this temperature for 6-12 hours. Then, the heating is stopped, the material is cooled, and the composite flame retardant modifier is obtained. The silane coupling agent is 3-glycidyl etheroxypropyltrimethoxysilane or 3-glycidyl etheroxypropyltriethoxysilane; 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.

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

4.

3. The low-smoke halogen-free flame-retardant TPU cable material according to claim 1, characterized in that, In step two, the phase transfer catalyst is any one of tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, tetramethylammonium bromide, and tetramethylammonium chloride.

4. The low-smoke halogen-free flame-retardant TPU cable material according to claim 1, characterized in that, In step three, the catalyst is p-toluenesulfonic acid or aminosulfonic acid.

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

2.

6. 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; and the ultraviolet absorber is any one of ultraviolet absorber UV-9, ultraviolet absorber UV-P, or ultraviolet absorber UV-531.

7. A method for preparing low-smoke halogen-free flame-retardant TPU cable material as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh all the raw materials according to the specified weight proportions, add them to a high-speed mixer, and mechanically mix them evenly to form a premix. The second step is to put the premixed material into a twin-screw extruder, control the extrusion temperature to 200-210℃ and the screw speed to 200-240rpm, and then obtain TPU cable material through melt extrusion process.

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