TPU wire rod and preparation method thereof

Abstract

The invention provides a TPU wire rod and a preparation method thereof, and belongs to the technical field of polyurethane. The flame-retardant thermoplastic polyurethane elastomer is prepared from the following raw materials in parts by weight: 3-5 parts of modified graphene oxide, 7-10 parts of flame-retardant ionic liquid, 1-3 parts of a plasticizer, 0.5-1 part of a stabilizer, 0.1-0.3 part of a dispersant and 70-80 parts of a thermoplastic polyurethane elastomer. The TPU wire prepared by the invention has better flame retardance, excellent mechanical properties, high compatibility among various raw materials, lower cost and excellent performance, the preparation method is simple and efficient, and the TPU wire can be used as a flame-retardant TPU wire and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane, and in particular to a TPU wire and a preparation method thereof. Background Art

[0002] Thermoplastic polyurethane elastomer, also known as thermoplastic polyurethane rubber, abbreviated as TPU, is a (AB)n type block linear polymer. A is a high molecular weight (1000-6000) polyester or polyether, B is a diol containing 2-12 straight-chain carbon atoms, and the chemical structure between the AB segments is diisocyanate.

[0003] Traditional flame retardants used in TPU compositions are halogen-based, i.e., they contain bromine, chlorine, etc. However, due to ever-present environmental and safety concerns, halogen-free flame retardants are now popular, but they can present challenges for TPU compositions. Conventional readily available halogen-free flame retardants, such as those based on organic phosphates (e.g., resorcinol bis(diphenyl phosphate) (RDP) and bisphenol-A bis(diphenyl phosphate) (BPADP)), do not produce flame-retardant TPU compositions with good smoke suppression. The TPU industry is continuing to focus on halogen-free TPU compositions that have both good smoke suppression and flame retardancy.

[0004] US2003 / 0166749A1 discloses a flame retardant thermoplastic polyurethane, which contains melamine cyanurate as a flame retardant and improves its mechanical properties by adding up to 2% by weight of at least one crosslinking agent component. Examples of the disclosed crosslinking agent include trimethylolpropane, pentaerythritol, amines, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, etc.

[0005] US2003 / 0166749A1 also discloses a method for producing a flame retardant thermoplastic polyurethane by mixing the components by methods known to those skilled in the art (such as combining). The patent document does not disclose the need to add a crosslinking agent, such as a diisocyanate, in the form of a concentrated solution in at least one polyurethane.

[0006] DE 103 43 121 A1 discloses thermoplastic polyurethanes containing metal hydroxides as flame retardants. One of the characteristics of these thermoplastic polyurethanes is that the molecular weight is particularly high, at least 60,000 g / mol. The specification does not describe the crosslinking of the thermoplastic polyurethanes.

[0007] WO2006 / 121549A1 discloses thermoplastic polyurethane containing halogen-free flame retardant. The flame retardant described in WO2006 / 121549A1 includes an organic phosphinate component, an organic phosphate component and a polyol. According to the specification, the flame retardant is mixed by a method known to those skilled in the art (such as combining). However, the patent does not disclose that flame-retardant thermoplastic polyurethane can be obtained by adding a crosslinking agent together with the flame retardant.

[0008] The methods of the prior art are capable of producing flame-retardant thermoplastic polyurethanes, but a sufficiently high flame-retardant effect can only be achieved by a relatively high amount of filler relative to the flame retardant. In particular, for halogen-free compounds, a high content of filler is required to produce a sufficient flame-retardant effect. Conventional flame retardants are melamine compounds and phosphorus-containing compounds and also metal hydroxides, and the proportion of these compounds that needs to be added to achieve a sufficiently good flame-retardant effect is 20-60% by weight.

[0009] The disadvantage of such high additive content is that it weakens the mechanical properties of the composite thermoplastic polyurethane materials and restricts their rational use in the market. The first factor leading to the reduction of mechanical properties is the excessive filler content, and the second is the addition of specific materials during the manufacturing process that reduces the molar mass, which also leads to a reduction in mechanical properties. Summary of the invention

[0010] The purpose of the present invention is to provide a TPU wire and a preparation method thereof, which has good flame retardancy, good mechanical properties, high compatibility between various raw materials, low cost, good performance, a simple and efficient preparation method, can be used as a flame retardant TPU wire, and has broad application prospects.

[0011] The technical solution of the present invention is achieved in this way:

[0012] The invention provides a TPU wire material, which is prepared from the following raw materials in parts by weight: 3-5 parts of modified graphene oxide, 7-10 parts of flame retardant ionic liquid, 1-3 parts of plasticizer, 0.5-1 parts of stabilizer, 0.1-0.3 parts of dispersant and 70-80 parts of thermoplastic polyurethane elastomer.

[0013] As a further improvement of the present invention, the preparation method of the modified graphene oxide is as follows:

[0014] S1. adding graphene oxide to water, adding EDC and NHS, stirring to activate, adding melamine, stirring to react, filtering, washing, and drying to obtain melamine-treated graphene oxide;

[0015] S2. Add melamine-modified graphene oxide into water, disperse it evenly by ultrasonication, then add phytic acid, heat and reflux to react, filter, wash and dry to obtain modified graphene oxide.

[0016] As a further improvement of the present invention, the mass ratio of graphene oxide, EDC, NHS and melamine in step S1 is 10:2-3:1-2:3-5, the stirring activation time is 1-2h, and the stirring reaction time is 5-7h.

[0017] As a further improvement of the present invention, the mass ratio of melamine-treated graphene oxide to phytic acid in step S2 is 10:3-4, and the heating reflux reaction time is 10-14h.

[0018] As a further improvement of the present invention, the preparation method of the flame retardant ionic liquid is as follows:

[0019] T1. Dissolve N-vinylimidazole in dichloromethane, add 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, stir at room temperature for reaction, then heat up to continue the reaction, cool to room temperature, remove the solvent under reduced pressure, and purify with ethyl acetate to obtain an intermediate ionic liquid with the following structure:

[0020] T2. Add a silane coupling agent and an initiator having a double bond to the intermediate ionic liquid, heat and stir the reaction, wash with water, and remove the solvent under reduced pressure to obtain an intermediate ionic liquid 2;

[0021] T3. The intermediate ionic liquid 2 and sodium 2-naphthalenesulfonate were dissolved in water, stirred at room temperature for reaction, and extracted with dichloromethane. The extract was washed with water, the solvent was removed under reduced pressure, and dried to obtain a flame retardant ionic liquid.

[0022] As a further improvement of the present invention, the molar ratio of N-vinylimidazole to 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene in step T1 is 1-1.1:1, the stirring reaction time at room temperature is 0.5-1.5h, and the temperature of the heating reaction is 65-75°C for 20-24h.

[0023] As a further improvement of the present invention, the mass ratio of the intermediate ionic liquid, the silane coupling agent with a double bond and the initiator in step T2 is 10:2-3:0.01-0.015, the silane coupling agent with a double bond is selected from at least one of KH570, A151, and A171, the initiator is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate, and the temperature of the heating and stirring reaction is 50-60° C., and the time is 3-5 hours.

[0024] As a further improvement of the present invention, in step T3, the molar ratio of the intermediate ionic liquid 2 to sodium 2-naphthalenesulfonate is 1:1, and the reaction time under room temperature stirring is 7-9 hours.

[0025] As a further improvement of the present invention, the plasticizer is selected from at least one of glycerol, ethylene glycol, and polyethylene glycol; the stabilizer is selected from at least one of calcium hydroxide, calcium oxide, and magnesium hydroxide; and the dispersant is selected from at least one of calcium stearate, polyethylene wax, and oxidized polyethylene wax.

[0026] The present invention further protects a method for preparing the above-mentioned TPU wire, comprising the following steps:

[0027] (1) mixing modified graphene oxide and flame retardant ionic liquid, stirring and mixing for 15-30 minutes to prepare an additive;

[0028] (2) vacuum drying the thermoplastic polyurethane elastomer, adding a plasticizer, a stabilizer and a dispersant, heating until melted, adding the additives, and melt-extruding the mixture through a twin-screw extruder to obtain blended particles; the barrel temperature is 180-220° C., and the screw speed is 100-200 rpm / min;

[0029] (3) adding the blended particles into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 180-220° C., and the screw speed is 20-70 rpm / min.

[0030] The present invention has the following beneficial effects:

[0031] Ionic liquids are organic salts that are liquid at low temperatures and are composed of organic cations and inorganic or organic anions. They are halogen-free, safe and environmentally friendly. The present invention introduces 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene (DOP-Cl) into N-vinyl imidazole, then copolymerizes it through double bonds, reacts with a silane coupling agent with double bonds, and then exchanges anions. The obtained ionic liquid material introduces phosphorus, nitrogen, silicon, sulfur, etc., and achieves the best flame retardant effect. The ionic liquid itself is non-flammable and has the characteristics of low vapor pressure and high thermal stability. At the same time, it has a catalytic effect on reactions such as esterification and Friedel-Crafts alkylation. This reaction occurs during the decomposition of the polymer. The ionic liquid can improve the residual carbon content and may reduce the generation of smoke, playing a role in flame retardancy and smoke suppression. At the same time, the ionic liquid can destroy the intermolecular forces of the compound, causing it to decompose to play a flame retardant role. At the same time, the oxygen-containing functional groups of the ionic liquid can destroy its own oxygen-containing functional groups and hinder the reaction with oxygen, thereby achieving a flame retardant effect.

[0032] The structure of the ionic liquid flame retardant of the present invention has good solubility, can promote the dispersibility of modified graphene oxide in polyurethane, avoid incompatibility, and can also improve its compatibility and processability with plastics, with little effect on the mechanical properties and other properties of plastics. The compounding with modified graphene oxide shows an unexpected synergistic effect, enhances flame retardancy, and reduces the influence of additives on plastic properties.

[0033] The present invention also prepares modified graphene oxide, and the nitrogen content in the melamine-modified graphene oxide is greatly increased through condensation of the carboxyl groups on the surface of the graphene oxide with the amino groups of melamine, thereby improving its flame retardancy. At the same time, the graphene oxide itself can significantly improve the mechanical properties and wear resistance of the polyurethane material. At the same time, the formed amide structure is similar to the polyurethane structure, which improves the compatibility of the modified graphene oxide with the polyurethane, and further reacts with phytic acid to increase the phosphorus content of the modified graphene oxide, thereby further improving its flame retardancy.

[0034] The TPU wire prepared by the invention has good flame retardancy, good mechanical properties, high compatibility between various raw materials, low cost, good performance, simple and efficient preparation method, can be used as flame retardant TPU wire, and has broad application prospects. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Graphene oxide, with an oxygen content of 30-35 wt%, a sheet diameter of 15-25 μm, and a thickness of <5 nm, was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0037] EDC, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, is commercially available.

[0038] NHS, N-hydroxysuccinimide, commercially available.

[0039] Preparation Example 1 Preparation of modified graphene oxide

[0040] Here’s how:

[0041] S1. Add 10 g of graphene oxide to 200 mL of water, add 2 g of EDC and 1 g of NHS, stir and activate for 1 h, add 3 g of melamine, stir and react for 5 h, filter, wash, and dry to obtain melamine-modified graphene oxide;

[0042] S2. Add 10 g of melamine-treated graphene oxide into 200 mL of water, disperse at 1000 W ultrasonically for 10 min, then add 3 g of phytic acid, heat and reflux for 10 h, filter, wash, and dry to obtain modified graphene oxide.

[0043] Preparation Example 2 Preparation of modified graphene oxide

[0044] Here’s how:

[0045] S1. Add 10 g of graphene oxide to 200 mL of water, add 3 g of EDC and 2 g of NHS, stir and activate for 2 h, add 5 g of melamine, stir and react for 7 h, filter, wash, and dry to obtain melamine-modified graphene oxide;

[0046] S2. Add 10 g of melamine-treated graphene oxide into 200 mL of water, disperse at 1000 W ultrasonically for 10 min, then add 4 g of phytic acid, heat and reflux for 14 h, filter, wash, and dry to obtain modified graphene oxide.

[0047] Preparation Example 3 Preparation of modified graphene oxide

[0048] Here’s how:

[0049] S1. Add 10 g of graphene oxide to 200 mL of water, add 2.5 g of EDC and 1.5 g of NHS, stir and activate for 1.5 h, add 4 g of melamine, stir and react for 6 h, filter, wash, and dry to obtain melamine-modified graphene oxide;

[0050] S2. Add 10 g of melamine-treated graphene oxide into 200 mL of water, disperse at 1000 W ultrasonically for 10 min, then add 3.5 g of phytic acid, heat and reflux for 12 h, filter, wash, and dry to obtain modified graphene oxide.

[0051] Comparative Preparation Example 1

[0052] Compared with Preparation Example 3, the difference is that step S1 is not performed.

[0053] The details are as follows:

[0054] 10 g of graphene oxide was added to 200 mL of water, and ultrasonically dispersed at 1000 W for 10 min. Then 3.5 g of phytic acid was added, and the mixture was heated under reflux for 12 h. The mixture was filtered, washed, and dried to obtain modified graphene oxide.

[0055] Comparative Preparation Example 2

[0056] Compared with Preparation Example 3, the difference is that step S2 is not performed.

[0057] The details are as follows:

[0058] 10 g of graphene oxide was added to 200 mL of water, 2.5 g of EDC and 1.5 g of NHS were added, and the mixture was stirred for activation for 1.5 h. 4 g of melamine was added, and the mixture was stirred for reaction for 6 h. The mixture was filtered, washed, and dried to obtain modified graphene oxide.

[0059] Preparation Example 4 Preparation of flame retardant ionic liquid

[0060] Here’s how:

[0061] The synthetic route is as follows:

[0062]

[0063] T1. Dissolve 10 mmol N-vinyl imidazole in 100 mL dichloromethane, add 10 mmol 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, stir at room temperature for 0.5 h, then heat to 65 ° C, continue to react for 20 h, cool to room temperature, remove the solvent under reduced pressure, and purify with ethyl acetate to obtain an intermediate ionic liquid with a yield of 70%;

[0064] T2. Add 2 g of silane coupling agent A151 and 0.01 g of potassium persulfate to 10 g of the intermediate ionic liquid, heat to 50 ° C, stir and react for 3 h, wash with water, and remove the solvent under reduced pressure to obtain an intermediate ionic liquid 2;

[0065] T3. Dissolve 10 mmol of the intermediate ionic liquid 2 and 10 mmol of sodium 2-naphthalenesulfonate in 200 mL of water, stir and react at room temperature for 7 h, add an equal volume of dichloromethane for extraction, wash the extract with water, remove the solvent under reduced pressure, and dry to obtain a flame retardant ionic liquid.

[0066] Preparation Example 5 Preparation of flame retardant ionic liquid

[0067] Here’s how:

[0068] T1. Dissolve 11mmol N-vinyl imidazole in 100mL dichloromethane, add 10mmol 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, stir at room temperature for 1.5h, then heat to 75°C, continue to react for 24h, cool to room temperature, remove the solvent under reduced pressure, and purify with ethyl acetate to obtain an intermediate ionic liquid;

[0069] T2. Add 3 g of silane coupling agent A171 and 0.015 g of ammonium persulfate to 10 g of the intermediate ionic liquid, heat to 60 ° C, stir and react for 5 h, wash with water, and remove the solvent under reduced pressure to obtain an intermediate ionic liquid 2;

[0070] T3. Dissolve 10 mmol of the intermediate ionic liquid 2 and 10 mmol of sodium 2-naphthalenesulfonate in 200 mL of water, stir and react at room temperature for 9 h, add an equal volume of dichloromethane for extraction, wash the extract with water, remove the solvent under reduced pressure, and dry to obtain a flame retardant ionic liquid.

[0071] Preparation Example 6 Preparation of flame retardant ionic liquid

[0072] Here’s how:

[0073] T1. Dissolve 10.5mmol N-vinyl imidazole in 100mL dichloromethane, add 10mmol 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, stir at room temperature for 1h, then heat to 70°C, continue to react for 22h, cool to room temperature, remove the solvent under reduced pressure, and purify with ethyl acetate to obtain an intermediate ionic liquid;

[0074] T2. Add 2.5 g of silane coupling agent KH570 and 0.012 g of ammonium persulfate to 10 g of the intermediate ionic liquid, heat to 55 ° C, stir and react for 4 h, wash with water, and remove the solvent under reduced pressure to obtain an intermediate ionic liquid 2;

[0075] T3. Dissolve 10 mmol of the intermediate ionic liquid 2 and 10 mmol of sodium 2-naphthalenesulfonate in 200 mL of water, stir and react at room temperature for 8 h, add an equal volume of dichloromethane for extraction, wash the extract with water, remove the solvent under reduced pressure, and dry to obtain a flame retardant ionic liquid.

[0076] Comparative Preparation Example 3

[0077] Compared with Preparation Example 6, the difference is that step T1 is not performed.

[0078] The details are as follows:

[0079] T1. Add 2.5 g of silane coupling agent KH570 and 0.012 g of ammonium persulfate to 10 g of N-vinyl imidazole, heat to 55 ° C, stir and react for 4 h, wash with water, and remove the solvent under reduced pressure to obtain an intermediate ionic liquid;

[0080] T2. Dissolve 10 mmol of the intermediate ionic liquid and 10 mmol of sodium 2-naphthalenesulfonate in 200 mL of water, stir and react at room temperature for 8 h, add an equal volume of dichloromethane for extraction, wash the extract with water, remove the solvent under reduced pressure, and dry to obtain a flame retardant ionic liquid.

[0081] Comparative Preparation Example 4

[0082] Compared with Preparation Example 6, the difference is that step T2 is not performed.

[0083] The details are as follows:

[0084] T1. Dissolve 10.5mmol N-vinyl imidazole in 100mL dichloromethane, add 10mmol 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, stir at room temperature for 1h, then heat to 70°C, continue to react for 22h, cool to room temperature, remove the solvent under reduced pressure, and purify with ethyl acetate to obtain an intermediate ionic liquid;

[0085] T2. Dissolve 10 mmol of the intermediate ionic liquid and 10 mmol of sodium 2-naphthalenesulfonate in 200 mL of water, stir and react at room temperature for 8 h, add an equal volume of dichloromethane for extraction, wash the extract with water, remove the solvent under reduced pressure, and dry to obtain a flame retardant ionic liquid.

[0086] Example 1

[0087] This embodiment provides a method for preparing a TPU wire, comprising the following steps:

[0088] (1) 3 parts by weight of the modified graphene oxide prepared in Preparation Example 1 and 7 parts by weight of the flame retardant ionic liquid prepared in Preparation Example 4 were mixed and stirred for 15 minutes to prepare an additive;

[0089] (2) drying 70 parts by weight of thermoplastic polyurethane elastomer at 105° C. in vacuum for 1 h, adding 1 part by weight of glycerol, 0.5 part by weight of magnesium hydroxide and 0.1 part by weight of oxidized polyethylene wax, heating until melted, adding the additive prepared in step (1), and melt-extruding the mixture through a twin-screw extruder to obtain blended particles; the barrel temperature is 180° C. and the screw speed is 100 rpm / min;

[0090] (3) The blended particles are added into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 180°C and the screw speed is 20 rpm / min.

[0091] Example 2

[0092] This embodiment provides a method for preparing a TPU wire, comprising the following steps:

[0093] (1) 5 parts by weight of the modified graphene oxide prepared in Preparation Example 2 and 10 parts by weight of the flame retardant ionic liquid prepared in Preparation Example 5 were mixed and stirred for 30 minutes to prepare an additive;

[0094] (2) 80 parts by weight of thermoplastic polyurethane elastomer was dried at 105° C. in vacuum for 1 h, 3 parts by weight of ethylene glycol, 1 part by weight of calcium oxide and 0.3 parts by weight of polyethylene wax were added, and the mixture was heated until melted, and the additive prepared in step (1) was added, and the mixture was melt-extruded through a twin-screw extruder to obtain blended particles; the barrel temperature was 220° C., and the screw speed was 200 rpm / min;

[0095] (3) The blended particles are added into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 220°C and the screw speed is 70 rpm / min.

[0096] Example 3

[0097] This embodiment provides a method for preparing a TPU wire, comprising the following steps:

[0098] (1) 4 parts by weight of the modified graphene oxide prepared in Preparation Example 3 and 8 parts by weight of the flame retardant ionic liquid prepared in Preparation Example 6 were mixed and stirred for 20 minutes to prepare an additive;

[0099] (2) drying 75 parts by weight of thermoplastic polyurethane elastomer at 105° C. in vacuum for 1 h, adding 2 parts by weight of polyethylene glycol 1000, 0.7 parts by weight of calcium hydroxide and 0.2 parts by weight of calcium stearate, heating until melted, adding the additive prepared in step (1), and melt-extruding the mixture through a twin-screw extruder to obtain blended particles; the barrel temperature is 200° C. and the screw speed is 150 rpm / min;

[0100] (3) The blended particles are added into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 200°C and the screw speed is 50 rpm / min.

[0101] Comparative Example 1

[0102] Compared with Example 3, the difference is that the modified graphene oxide is prepared by Comparative Preparation Example 1.

[0103] Comparative Example 2

[0104] Compared with Example 3, the difference is that the modified graphene oxide is prepared by Comparative Preparation Example 2.

[0105] Comparative Example 3

[0106] Compared with Example 3, the difference is that the flame retardant ionic liquid is prepared by Comparative Preparation Example 3.

[0107] Comparative Example 4

[0108] Compared with Example 3, the difference is that the flame retardant ionic liquid is prepared by Comparative Preparation Example 4.

[0109] Comparative Example 5

[0110] Compared with Example 3, the difference is that no modified graphene oxide is added.

[0111] The details are as follows:

[0112] (1) 12 parts by weight of the flame retardant ionic liquid prepared in Preparation Example 6 was stirred and mixed for 20 minutes to prepare an additive;

[0113] (2) drying 75 parts by weight of thermoplastic polyurethane elastomer at 105° C. in vacuum for 1 h, adding 2 parts by weight of polyethylene glycol 1000, 0.7 parts by weight of calcium hydroxide and 0.2 parts by weight of calcium stearate, heating until melted, adding the additive prepared in step (1), and melt-extruding the mixture through a twin-screw extruder to obtain blended particles; the barrel temperature is 200° C. and the screw speed is 150 rpm / min;

[0114] (3) The blended particles are added into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 200°C and the screw speed is 50 rpm / min.

[0115] Comparative Example 6

[0116] Compared with Example 3, the difference is that no flame retardant ionic liquid is added.

[0117] The details are as follows:

[0118] (1) stirring and mixing 12 parts by weight of the modified graphene oxide obtained in Preparation Example 3 for 20 minutes to obtain an additive;

[0119] (2) drying 75 parts by weight of thermoplastic polyurethane elastomer at 105° C. in vacuum for 1 h, adding 2 parts by weight of polyethylene glycol 1000, 0.7 parts by weight of calcium hydroxide and 0.2 parts by weight of calcium stearate, heating until melted, adding the additive prepared in step (1), and melt-extruding the mixture through a twin-screw extruder to obtain blended particles; the barrel temperature is 200° C. and the screw speed is 150 rpm / min;

[0120] (3) The blended particles are added into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 200°C and the screw speed is 50 rpm / min.

[0121] Comparative Example 7

[0122] Compared with Example 3, the difference is that modified graphene oxide and flame retardant ionic liquid are not added.

[0123] The details are as follows:

[0124] (1) 75 parts by weight of thermoplastic polyurethane elastomer was dried at 105° C. in vacuum for 1 h, 2 parts by weight of polyethylene glycol 1000, 0.7 parts by weight of calcium hydroxide and 0.2 parts by weight of calcium stearate were added, and the mixture was heated until melted, and melt-extruded through a twin-screw extruder to obtain blended particles; the barrel temperature was 200° C., and the screw speed was 150 rpm / min;

[0125] (2) The blended particles are added into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 200°C and the screw speed is 50 rpm / min.

[0126] Test Example 1 Mechanical Properties Test

[0127] The TPU blended particles prepared in Examples 1-3 of the present invention or Comparative Examples 1-6 were further processed into 5-type dumbbell pieces with a thickness of 1.0 mm, and mechanical properties were tested. The results are shown in Table 1.

[0128] The tensile strength and elongation at break tests were carried out in accordance with GB / T528-2009 “Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber”, with a tensile rate of 500 mm / min.

[0129] Table 1

[0130] Group Tensile strength(MPa) Elongation at break (%) Example 1 55.9 605 Example 2 55.6 602 Example 3 56.2 610 Comparative Example 1 54.2 595 Comparative Example 2 54.0 590 Comparative Example 3 54.8 598 Comparative Example 4 53.4 586 Comparative Example 5 49.9 550 Comparative Example 6 52.8 578 Comparative Example 7 48.2 540

[0131] It can be seen from the above table that the TPU materials prepared in Examples 1-3 of the present invention have good mechanical properties.

[0132] Test Example 2 Flame retardant performance test

[0133] The TPU blended particles prepared in Examples 1-3 of the present invention or Comparative Examples 1-6 were further processed into standard specimens for flame retardant performance tests. The results are shown in Table 2.

[0134] The vertical burning test is carried out in accordance with GB / T2408-2021 "Horizontal and Vertical Methods for Determination of Combustion Performance of Plastics", and the specimen is a flame-retardant strip with a thickness of 3.2 mm.

[0135] The limiting oxygen index test is carried out in accordance with GB / T2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method Part 2: Room Temperature Test", using Type IV oxygen index splines and the diffusion ignition method.

[0136] Table 2

[0137] Group Vertical burning level Limiting oxygen index (%) Example 1 V0 41.5 Example 2 V0 41.2 Example 3 V0 41.9 Comparative Example 1 V1 26.7 Comparative Example 2 V1 27.2 Comparative Example 3 V1 28.0 Comparative Example 4 V1 26.1 Comparative Example 5 V2 24.9 Comparative Example 6 V2 23.2 Comparative Example 7 HB 19.0

[0138] It can be seen from the above table that the TPU materials prepared in Examples 1-3 of the present invention have good flame retardant properties.

[0139] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A TPU wire, characterized in that: The invention is prepared from the following raw materials in parts by weight: 3-5 parts of modified graphene oxide, 7-10 parts of flame retardant ionic liquid, 1-3 parts of plasticizer, 0.5-1 parts of stabilizer, 0.1-0.3 parts of dispersant and 70-80 parts of thermoplastic polyurethane elastomer.

2. The TPU wire according to claim 1, characterized in that: The preparation method of the modified graphene oxide is as follows: S1. adding graphene oxide to water, adding EDC and NHS, stirring to activate, adding melamine, stirring to react, filtering, washing, and drying to obtain melamine-treated graphene oxide; S2. Add melamine-modified graphene oxide into water, disperse it evenly by ultrasonication, then add phytic acid, heat and reflux to react, filter, wash and dry to obtain modified graphene oxide.

3. The TPU wire according to claim 2, characterized in that: In step S1, the mass ratio of graphene oxide, EDC, NHS and melamine is 10:2-3:1-2:3-5, the stirring activation time is 1-2h, and the stirring reaction time is 5-7h.

4. The TPU wire according to claim 2, characterized in that: In step S2, the mass ratio of melamine-treated graphene oxide to phytic acid is 10:3-4, and the heating reflux reaction time is 10-14h.

5. The TPU wire according to claim 1, characterized in that: The preparation method of the flame retardant ionic liquid is as follows: T1. Dissolve N-vinylimidazole in dichloromethane, add 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, stir at room temperature for reaction, then heat up to continue the reaction, cool to room temperature, remove the solvent under reduced pressure, and purify with ethyl acetate to obtain an intermediate ionic liquid with the following structure: T2. Add a silane coupling agent and an initiator having a double bond to the intermediate ionic liquid, heat and stir the reaction, wash with water, and remove the solvent under reduced pressure to obtain an intermediate ionic liquid 2; T3. The intermediate ionic liquid 2 and sodium 2-naphthalenesulfonate were dissolved in water, stirred at room temperature for reaction, and extracted with dichloromethane. The extract was washed with water, the solvent was removed under reduced pressure, and dried to obtain a flame retardant ionic liquid.

6. The TPU wire according to claim 5, characterized in that: In step T1, the molar ratio of N-vinylimidazole to 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene is 1-1.1:1, the stirring reaction time at room temperature is 0.5-1.5h, and the temperature of the heating reaction is 65-75°C for 20-24h.

7. The TPU wire according to claim 5, characterized in that: The mass ratio of the intermediate ionic liquid, the silane coupling agent with a double bond and the initiator in step T2 is 10:2-3:0.01-0.015, the silane coupling agent with a double bond is selected from at least one of KH570, A151, and A171, the initiator is selected from at least one of sodium persulfate, potassium persulfate, and ammonium persulfate, and the temperature of the heating and stirring reaction is 50-60° C., and the time is 3-5h.

8. The TPU wire according to claim 5, characterized in that: In step T3, the molar ratio of the intermediate ionic liquid 2 to sodium 2-naphthalenesulfonate is 1:1, and the reaction time under stirring at room temperature is 7-9 hours.

9. The TPU wire according to claim 1, characterized in that: The plasticizer is selected from at least one of glycerol, ethylene glycol, and polyethylene glycol; the stabilizer is selected from at least one of calcium hydroxide, calcium oxide, and magnesium hydroxide; and the dispersant is selected from at least one of calcium stearate, polyethylene wax, and oxidized polyethylene wax.

10. A method for preparing a TPU wire according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) mixing modified graphene oxide and flame retardant ionic liquid, stirring and mixing for 15-30 minutes to prepare an additive; (2) vacuum drying the thermoplastic polyurethane elastomer, adding a plasticizer, a stabilizer and a dispersant, heating until melted, adding the additives, and melt-extruding the mixture through a twin-screw extruder to obtain blended particles; the barrel temperature is 180-220° C., and the screw speed is 100-200 rpm / min; (3) adding the blended particles into a single screw extruder for extrusion, shaping and winding to obtain TPU wire; the barrel temperature is 180-220° C., and the screw speed is 20-70 rpm / min.

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