Self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material as well as preparation method and application thereof

Abstract

The invention discloses a self-crosslinking type soft low-smoke halogen-free flame-retardant polyolefin cable material as well as a preparation method and application thereof. The cable material comprises the following raw materials in parts by weight: 30-40 parts of modified polyethylene; 30 to 40 parts of modified polypropylene; 25 to 35 parts of an ethylene-tetrafluoroethylene copolymer; 30-40 parts of a fuming inhibitor; 40 to 50 parts of a halogen-free flame retardant; 2-3 parts of a lubricant; 2-3 parts of a compatibilizer; and 7-11 parts of a thermoplastic elastomer. The flame-retardant and smoke-suppression effects are achieved through aluminum hydroxide at the initial stage of combustion, the thermal decomposition temperature of PE and PP materials can be remarkably reduced through magnesium hydroxide, meanwhile, the excellent carbonization and flame-retardant effects on polymers are achieved, an isolation belt for isolating fire can be formed through the heating expansion characteristic of pentaerythritol phosphate melamine salt, and the flame-retardant and smoke-suppression effects are achieved. And the phosphorylated linseed oil is used as a bio-based flame retardant, so that harmless treatment of harmful substances can be realized during combustion, and the fireproof performance of the cable is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of cable material preparation, and in particular to a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material and a preparation method and application thereof. Background Art

[0002] Cable materials refer to materials used for the insulation and sheath of wires and cables, including rubber, plastic, nylon, etc. Polyolefins are a type of thermoplastic resin obtained by polymerizing or copolymerizing a variety of olefin compounds. Polyolefins are commonly used in cable processing because of their relatively low density, excellent chemical and water resistance, high mechanical strength, and high electrical insulation.

[0003] With the rapid development of power facility engineering and communication data transmission, cables are widely used. The heat resistance and flame retardant effect of polyolefin cables in the existing technology are limited. When operating under high temperature conditions, it is necessary to further improve the heat resistance of the cable to the working environment temperature, and at the same time, it is necessary to further improve the fire retardant properties of the cable inner layer structure.

[0004] After searching, it was found that the invention patent with Chinese patent publication number CN110527161A disclosed a silane cross-linked low-smoke halogen-free flame retardant polyolefin cable material. The cable material is prepared by introducing a strong polar reactive group as a flame retardant and filling material by using a maleic anhydride grafted compatibilizer, and using silicon carbide and silicone rubber to increase the corrosion resistance and high temperature resistance of the cable material, and further enhance the strength of the cable material. However, due to the high hardness of silicon carbide material, it is difficult to maintain the softness of the cable material after adding the silicon carbide into the cable material, and the cable material cannot effectively suppress the smoke generated during a fire.

[0005] The invention patent with Chinese patent publication number CN117402438A discloses a method for preparing and using a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material. The self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material is prepared by utilizing the interlayer structural characteristics of layered double metal hydroxides and their synergistic flame retardant effect, and compounding with polyhydroxy structured phosphorus-containing phytic acid. The flame retardant effect is enhanced by intercalation modification and grafting modification. However, the preparation process of the cable material lacks smoke-suppressing materials, and the generation of a large amount of smoke after a cable fire cannot be effectively avoided.

[0006] Therefore, how to solve the above-mentioned deficiencies in the prior art has become a subject to be studied and solved by the present invention. Summary of the invention

[0007] The purpose of the present invention is to provide a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material and a preparation method and application thereof.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material, comprising the following raw materials in parts by weight:

[0010] 30-40 parts of modified polyethylene;

[0011] 30-40 parts of modified polypropylene;

[0012] 25-35 parts of ethylene-tetrafluoroethylene copolymer;

[0013] 30-40 parts of smoke suppressant;

[0014] 40-50 parts of halogen-free flame retardant;

[0015] 2-3 parts of lubricant;

[0016] 2-3 parts of expander;

[0017] Thermoplastic elastomer 7-11 parts.

[0018] In a further technical solution, the modified polyethylene is a modified structure of POE and PE;

[0019] The modified polypropylene is a modified structure of POE and PP;

[0020] The smoke suppressant is a mixed powder formed by mixing 25 to 32 parts of aluminum hydroxide and 5 to 8 parts of magnesium hydroxide;

[0021] The halogen-free flame retardant is prepared by mixing 25 to 30 parts of siloxane, 10 to 15 parts of pentaerythritol phosphate melamine salt and 5 to 10 parts of phosphorylated linseed oil.

[0022] The lubricant is vinyl chloride wax;

[0023] The compatibilizer is prepared by mixing 1 to 1.5 parts of a cyclic anhydride type compatibilizer and 1 to 1.5 parts of a carboxylic acid type compatibilizer;

[0024] The thermoplastic elastomer is polyphenylene ether.

[0025] Furthermore, the present invention also discloses a method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material, which is used to prepare the self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material. The preparation method comprises the following steps:

[0026] S1. Weigh the powder particles of aluminum hydroxide and magnesium hydroxide according to the proportion, and put them into a grinder, grind and mix to obtain a smoke suppressant;

[0027] S2. Weigh a sufficient amount of anhydrous ethanol, melamine, phosphoric acid and pentaerythritol, add them to a vessel No. 1 according to the mass ratio of 2:0.5:0.5:1, heat in a water bath and stir evenly to allow them to react fully to obtain a pentaerythritol phosphate melamine salt solution;

[0028] S3. The pentaerythritol phosphate melamine salt solution is transferred to the second vessel, siloxane and phosphorylated linseed oil are weighed according to the proportion, and added to the second vessel, heated in a water bath and stirred under reflux to obtain a primary solution;

[0029] S4. The primary solution is filtered, washed and dried in sequence to obtain a halogen-free flame retardant;

[0030] S5. According to the proportion of the modified polyethylene, modified polypropylene, ethylene - tetrafluoroethylene copolymer, smoke suppressant, halogen-free flame retardant, lubricant, compatibilizer and thermoplastic elastomer, added to the mixer and stirred to obtain the initial mixed particles;

[0031] S6. The prepared primary mixed material particles are put into a twin-screw extruder granulator, and after extrusion, the pellets are cut into pellets to obtain a soft, low-smoke, halogen-free, flame-retardant polyolefin cable material, which is then placed in a natural environment to wait for the polymer to form a self-crosslinking soft, low-smoke, halogen-free, flame-retardant polyolefin cable material through a cross-linking reaction of its own intermolecular chemical bonds, thereby completing the preparation.

[0032] In the above scheme, "after extrusion, pelletizing is performed to obtain a soft, low-smoke, halogen-free, flame-retardant polyolefin cable material, which is then placed in a natural environment to allow the polymer to form a self-crosslinking, soft, low-smoke, halogen-free, flame-retardant polyolefin cable material through the cross-linking reaction of its own intermolecular chemical bonds." This design eliminates the need to add a cross-linking agent, which not only reduces costs but is also more environmentally friendly.

[0033] According to a further technical solution, in S1, the powder particles of the aluminum hydroxide and the magnesium hydroxide are added into a grinding mill at a mass ratio of 4:1, and the mixing time is 20 to 25 minutes to obtain the smoke suppressant.

[0034] According to a further technical solution, in S2, the vessel No. 1 is a beaker or a flask, the temperature of heating the vessel No. 1 in a water bath is 92 to 100° C., and the stirring time in the water bath is 1 to 1.2 hours.

[0035] In a further technical solution, in S3, the second vessel is a beaker or a flask, the temperature of the water bath heating of the second vessel is 72 to 80° C., and the stirring time of the water bath is 2 to 2.3 hours;

[0036] In S4, the washing is performed three times.

[0037] According to a further technical solution, in S5, the stirring and mixing time is 25 to 30 minutes;

[0038] In S6, the diameter of the twin-screw extruder granulator is 150 mm, and the pelletizing speed is 250 to 1500 rpm.

[0039] Furthermore, the present invention also discloses a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable, comprising a cable core, an insulating filling layer and an outer sheath layer;

[0040] Wherein, the cable core is extruded and coated by the self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material;

[0041] The outer sheath layer is extruded on the outer layer of the cable core, and the insulating filling layer is filled between the cable core and the outer sheath layer.

[0042] According to a further technical solution, the cable core has multiple cores, and the cable core is a bundled tinned copper wire structure; the insulating filling layer is a PP fiber filament coated with a calcium carbonate layer on the surface, and the outer sheath layer is a thermoplastic polyurethane material layer.

[0043] The words “include,” “including,” and “have” used in this document are open-ended terms, meaning including but not limited to.

[0044] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0045] Compared with the prior art, the present invention provides the following beneficial effects:

[0046] 1. The present invention uses a mixed powder of aluminum hydroxide and magnesium hydroxide as a smoke suppressant during combustion. The thermal decomposition temperature of aluminum hydroxide is lower than that of magnesium hydroxide, and the flame retardant and smoke suppressant effect can be exerted at the initial stage of combustion. The combination of magnesium hydroxide and aluminum hydroxide can significantly reduce the thermal decomposition temperature of PE and PP materials, and has excellent carbonization flame retardant effect on polymers. The combined use of the two has a better flame retardant effect. The modified polyethylene and modified polypropylene are used to increase the bending toughness of the cable material while ensuring its elasticity, thereby ensuring that the manufactured cable has a better anti-fracture effect.

[0047] 2. The present invention prepares halogen-free flame retardants from siloxane, pentaerythritol phosphate melamine salt and phosphorylated linseed oil, utilizes the thermal expansion property of pentaerythritol phosphate melamine salt to form an isolation zone for isolating fire, and utilizes phosphorylated linseed oil as a bio-based flame retardant to achieve harmless treatment of harmful substances during combustion, thereby further improving the fire resistance of the cable.

[0048] 3. The present invention has the advantage of providing double fire protection for the inner layer of the cable through smoke suppressants and flame retardants, solving the problem of poor smoke suppression effect of cable materials in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Attached Figure 1 is a flow chart of the preparation method of each embodiment of the present invention;

[0050] Attached Figure 2 This is a schematic diagram of the cable structure layer using a self-cross-linking soft low-smoke halogen-free flame-retardant polyolefin cable material according to an embodiment of the present invention.

[0051] In the above figures: 1. Cable core; 2. Insulation filling layer; 3. Outer sheath layer. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0053] The present invention will be clearly described below with drawings and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0054] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0055] Embodiment 1:

[0056] A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material comprises the following raw materials in parts by weight: 30 parts of modified polyethylene, 30 parts of modified polypropylene, 25 parts of ethylene-tetrafluoroethylene copolymer, 30 parts of smoke suppressant, 40 parts of halogen-free flame retardant, 2 parts of lubricant, 2 parts of compatibilizer and 7 parts of thermoplastic elastomer.

[0057] Specifically, the modified polyethylene is a modified structure of POE and PE, the modified polypropylene is a modified structure of POE and PP, the smoke suppressant is a mixed powder of 25 parts of aluminum hydroxide and 5 parts of magnesium hydroxide, the halogen-free flame retardant is composed of 25 parts of siloxane, 10 parts of pentaerythritol phosphate melamine salt and 5 parts of phosphorylated linseed oil, the lubricant is a vinyl chloride wax structure, the compatibilizer is composed of 1 part of cyclic anhydride type compatibilizer and 1 part of carboxylic acid type compatibilizer, and the thermoplastic elastomer is polyphenylene ether.

[0058] Embodiment 2:

[0059] A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material comprises the following raw materials in parts by weight: 35 parts of modified polyethylene, 35 parts of modified polypropylene, 30 parts of ethylene-tetrafluoroethylene copolymer, 35 parts of smoke suppressant, 45 parts of halogen-free flame retardant, 2.5 parts of lubricant, 2.4 parts of compatibilizer and 9 parts of thermoplastic elastomer.

[0060] Specifically, the modified polyethylene is a modified structure of POE and PE, the modified polypropylene is a modified structure of POE and PP, the smoke suppressant is a mixed powder of 29 parts of aluminum hydroxide and 6 parts of magnesium hydroxide, the halogen-free flame retardant is composed of 27 parts of siloxane, 12 parts of pentaerythritol phosphate melamine salt and 6 parts of phosphorylated linseed oil, the lubricant is vinyl chloride wax, the compatibilizer is composed of 1.2 parts of cyclic anhydride type compatibilizer and 1.3 parts of carboxylic acid type compatibilizer, and the thermoplastic elastomer is polyphenylene ether.

[0061] Embodiment three:

[0062] A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material comprises the following raw materials in parts by weight: 40 parts of modified polyethylene, 40 parts of modified polypropylene, 35 parts of ethylene-tetrafluoroethylene copolymer, 40 parts of smoke suppressant, 50 parts of halogen-free flame retardant, 3 parts of lubricant, 3 parts of compatibilizer and 11 parts of thermoplastic elastomer.

[0063] Specifically, the modified polyethylene is a modified structure of POE and PE, the modified polypropylene is a modified structure of POE and PP, the smoke suppressant is a mixed powder of 32 parts of aluminum hydroxide and 8 parts of magnesium hydroxide, the halogen-free flame retardant is composed of 29 parts of siloxane, 13 parts of pentaerythritol phosphate melamine salt and 8 parts of phosphorylated linseed oil, the lubricant is vinyl chloride wax, the compatibilizer is composed of 1.5 parts of cyclic anhydride type compatibilizer and 1.5 parts of carboxylic acid type compatibilizer, and the thermoplastic elastomer is polyphenylene ether.

[0064] The above three embodiments were used to prepare self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable materials according to the following preparation methods.

[0065] like Figure 1 As shown, a method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material comprises the following processing steps:

[0066] S1. Weigh the powder particles of aluminum hydroxide and magnesium hydroxide in a mass ratio of 4:1, put them into a grinder, grind and mix for 20 minutes to obtain a smoke suppressant;

[0067] S2. Weigh sufficient amounts of anhydrous ethanol, melamine, phosphoric acid and pentaerythritol, add them to a vessel No. 1 in a mass ratio of 2:0.5:0.5:1, heat in a water bath at 100°C and stir for 1 hour to allow the reaction to fully react to obtain a pentaerythritol phosphate melamine salt solution;

[0068] S3. The pentaerythritol phosphate melamine salt solution was transferred to the second vessel, siloxane and phosphorylated linseed oil were weighed according to the proportion, and added to the second vessel, heated in a water bath at 80°C and stirred under reflux for 2h to obtain a primary solution;

[0069] S4. The primary solution is filtered, washed and dried to obtain a halogen-free flame retardant;

[0070] S5. According to the proportion of the modified polyethylene, modified polypropylene, ethylene - tetrafluoroethylene copolymer, smoke suppressant, halogen-free flame retardant, lubricant, compatibilizer and thermoplastic elastomer, added to the mixer and stirred for 30min to obtain the initial mixed particles;

[0071] S6. The prepared primary mixed material particles are put into a twin-screw extruder granulator, and the pellets are cut after extrusion to obtain a soft, low-smoke, halogen-free, flame-retardant polyolefin cable material. After being placed in a natural environment for 3 to 7 days, without adding any cross-linking agent, the polymer undergoes a cross-linking reaction of its own intermolecular chemical bonds to form a self-cross-linking soft, low-smoke, halogen-free, flame-retardant polyolefin cable.

[0072] The comparison of the formula of a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material in Example 1, Example 2 and Example 3 is shown in the following table:

[0073]

[0074]

[0075] The performance test data of a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material in Example 1, Example 2 and Example 3 are shown in the following table:

[0076]

[0077] The present invention uses a mixed powder of aluminum hydroxide and magnesium hydroxide as a smoke suppressant during combustion. The thermal decomposition temperature of aluminum hydroxide is lower than that of magnesium hydroxide, and the aluminum hydroxide can play a flame retardant and smoke suppressant role at the initial stage of combustion. The combination of magnesium hydroxide and aluminum hydroxide can significantly reduce the thermal decomposition temperature of PE and PP materials, and has an excellent carbonization flame retardant effect on polymers. The composite use of the two has a better flame retardant effect. Modified polyethylene and modified polypropylene are used to increase the bending toughness of the cable material while ensuring its elasticity, thereby ensuring that the manufactured cable has a better fracture resistance effect. Halogen-free flame retardants are prepared from siloxane, pentaerythritol phosphate melamine salt and phosphorylated linseed oil, and the thermal expansion property of pentaerythritol phosphate melamine salt is utilized to form an isolation zone for isolating fire. Phosphorylated linseed oil is used as a bio-based flame retardant to achieve harmless treatment of harmful substances during combustion, thereby further improving the fireproof performance of the cable.

[0078] like Figure 2 As shown, a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable comprises a cable core 1, an insulating filling layer 2 and an outer sheath layer 3.

[0079] Among them, the cable core 1 is extruded and coated with the self-cross-linking soft low-smoke halogen-free flame-retardant polyolefin cable material; the outer sheath layer 3 is extruded on the outer layer of the cable core 1, and the insulating filling layer 2 is filled between the cable core 1 and the outer sheath layer 3.

[0080] Preferably, there are multiple cable cores 1, and the cable core 1 is a bundled tinned copper wire structure; the insulating filling layer 2 is a PP fiber filament coated with a calcium carbonate layer on the surface, and the outer sheath layer 3 is a thermoplastic polyurethane material layer.

[0081] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material, characterized by: The invention comprises the following raw materials in parts by weight: 30-40 parts of modified polyethylene; 30-40 parts of modified polypropylene; 25-35 parts of ethylene-tetrafluoroethylene copolymer; 30-40 parts of smoke suppressant; 40~50 parts of halogen-free flame retardant; 2~3 parts of lubricant; 2~3 parts of expander; Thermoplastic elastomer 7~11 parts.

2. The self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to claim 1, characterized in that: The modified polyethylene is a modified structure of POE and PE; The modified polypropylene is a modified structure of POE and PP; The smoke suppressant is a mixed powder formed by mixing 25-32 parts of aluminum hydroxide and 5-8 parts of magnesium hydroxide; The halogen-free flame retardant is prepared by mixing 25-30 parts of siloxane, 10-15 parts of pentaerythritol phosphate melamine salt and 5-10 parts of phosphorylated linseed oil; The lubricant is vinyl chloride wax; The compatibilizer is prepared by mixing 1 to 1.5 parts of a cyclic anhydride type compatibilizer and 1 to 1.5 parts of a carboxylic acid type compatibilizer; The thermoplastic elastomer is polyphenylene ether.

3. A method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material, characterized in that: Used to prepare a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to any one of claims 1 to 2, the preparation method comprises the following steps: S1. Weigh the powder particles of aluminum hydroxide and magnesium hydroxide according to the proportion, put them into a grinder, grind and mix them to obtain a smoke suppressant; S2. Weigh sufficient amounts of anhydrous ethanol, melamine, phosphoric acid and pentaerythritol, add them to a vessel No. 1 according to a mass ratio of 2:0.5:0.5:1, heat in a water bath and stir evenly to allow them to react fully to obtain a pentaerythritol phosphate melamine salt solution; S3. The pentaerythritol phosphate melamine salt solution was transferred to the second vessel, and the siloxane and phosphorylated linseed oil were weighed according to the proportion, and added to the second vessel, heated in a water bath and stirred under reflux to obtain a primary solution; S4. The primary solution is filtered, washed and dried in sequence to obtain a halogen-free flame retardant; S5. According to the proportion of the modified polyethylene, modified polypropylene, ethylene - tetrafluoroethylene copolymer, smoke suppressant, halogen-free flame retardant, lubricant, compatibilizer and thermoplastic elastomer, added to the mixer and stirred to obtain the initial mixed particles; S6. The prepared primary mixed material particles are put into a twin-screw extruder granulator, and after extrusion, the pellets are cut into pellets to obtain a soft, low-smoke, halogen-free, flame-retardant polyolefin cable material, which is then placed in a natural environment to wait for the polymer to form a self-crosslinking soft, low-smoke, halogen-free, flame-retardant polyolefin cable material through a cross-linking reaction of its own intermolecular chemical bonds, thereby completing the preparation.

4. The method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to claim 3, characterized in that: In S1, the powder particles of the aluminum hydroxide and the magnesium hydroxide are added into a grinding mill at a mass ratio of 4:1, and the mixing time is 20 to 25 minutes to obtain the smoke suppressant.

5. The method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to claim 3, characterized in that: In S2, the vessel No. 1 is a beaker or a flask, the temperature of the water bath heating of the vessel No. 1 is 92-100° C., and the time of stirring in the water bath is 1-1.2 h.

6. The method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to claim 3, characterized in that: In S3, the second vessel is a beaker or a flask, the temperature of the water bath heating of the second vessel is 72-80° C., and the stirring time of the water bath is 2-2.3 h; In S4, the washing is performed three times.

7. The method for preparing a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to claim 3, characterized in that: In S5, the stirring and mixing time is 25 to 30 minutes; In S6, the diameter of the twin-screw extruder granulator is 150 mm, and the pelletizing speed is 250-1500 rpm.

8. A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable, characterized in that: It comprises a cable core (1), an insulating filling layer (2) and an outer sheath layer (3); Wherein, the cable core (1) is extruded and coated with a self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable material according to any one of claims 1 to 2; The outer sheath layer (3) is extruded onto the outer layer of the cable core (1), and the insulating filling layer (2) is filled between the cable core (1) and the outer sheath layer (3).

9. A self-crosslinking soft low-smoke halogen-free flame-retardant polyolefin cable according to claim 8, characterized in that: The cable core (1) has a plurality of strands, and the cable core (1) is a bundled tinned copper wire structure; the insulating filling layer (2) is a PP fiber filament with a calcium carbonate layer coated on the surface; and the outer sheath layer (3) is a thermoplastic polyurethane material layer.

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