A halogen-free flame-retardant thermoplastic polyurethane elastomer and its preparation method

Abstract

A halogen-free flame-retardant thermoplastic polyurethane elastomer and a preparation method thereof. The raw material formula comprises raw materials with the following mass percentages: 60% - 80% of thermoplastic polyurethane elastomer, 20% - 40% of halogen-free flame-retardant composition, and 0.3% - 2% of solid aromatic diol compounds. The solid aromatic diol compounds are at least one of hydroquinone bis(2-hydroxyethyl) ether, resorcinol-bis(β-hydroxyethyl) ether, 4-(2-hydroxyethoxy)-1-(2-hydroxyethyl)benzene diether, and 3-(2-hydroxyethoxy)-1-(2-hydroxyethyl)benzene diether. The solid aromatic diol compound of the additive in the present invention is coated on the surface of the halogen-free flame-retardant composition; it can effectively avoid the occurrence of dust during the mixing process of the halogen-free flame-retardant composition, and applying the halogen-free flame-retardant composition to the material can also ensure good flame-retardant performance and mechanical properties. In addition, the raw materials required are inexpensive, the operation is simple, and large-scale promotion can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer flame retardant materials, and particularly relates to a halogen-free flame retardant thermoplastic polyurethane elastomer and a preparation method thereof. Background Art

[0002] TPU is a thermoplastic polyurethane elastomer, which is widely used in the manufacturing of new energy vehicles and charging pile cables, etc. In conventional halogen-free flame retardant TPU compositions, a certain amount of halogen-free flame retardants and other additives need to be added to meet the physical properties requirements of the halogen-free flame retardant TPU compositions. The addition of halogen-free flame retardants will cause an increase in the melt viscosity of the TPU matrix, a decrease in the dispersibility of the flame retardant in the TPU melt, and the flame retardant is likely to precipitate, thus affecting the appearance of the manufactured halogen-free flame retardant TPU compositions and cable manufacturing products. Summary of the Invention

[0003] The purpose of the present invention is to provide a halogen-free flame retardant thermoplastic polyurethane elastomer and a preparation method thereof.

[0004] To achieve the above object and other related objects, the technical solution provided by the present invention is: a halogen-free flame retardant thermoplastic polyurethane elastomer, and the raw material formula includes raw materials with the following mass percentages:

[0005] Thermoplastic polyurethane elastomer 60% - 80%;

[0006] Halogen-free flame retardant composition 20% - 40%;

[0007] Solid aromatic diol compound 0.3% - 2%;

[0008] The solid aromatic diol compound is at least one of hydroquinone dihydroxyethyl ether, resorcinol-bis(β-hydroxyethyl) ether, 4-hydroxyethyloxyethyl-1-hydroxyethyl benzene ether, and 3-hydroxyethyloxyethyl-1-hydroxyethyl benzene ether.

[0009] The preferred technical solution is: the halogen-free flame retardant composition is at least one of aluminum diethylphosphinate or aluminum hypophosphite, aluminum tripolyphosphate, organic montmorillonite, and aluminum polyphosphite.

[0010] To achieve the above object and other related objects, the technical solution provided by the present invention is: a method for preparing a halogen-free flame retardant thermoplastic polyurethane elastomer, including the following steps:

[0011] Step 1: According to the raw material formula, mix the halogen-free flame retardant composition, thermoplastic polyurethane elastomer, and solid aromatic diol compound to obtain a mixture;

[0012] Step 2: Heat the mixture to melting and conduct melt extrusion to obtain the halogen-free flame retardant thermoplastic polyurethane elastomer.

[0013] The preferred technical solution is as follows: The mixing in Step 1 is carried out at room temperature, and a high-speed mixer is used as the mixing equipment. The mixing speed of the high-speed mixer is 800 - 1200 rpm, and the mixing time is 5 - 8 minutes.

[0014] The preferred technical solution is as follows: The step of melt extrusion is carried out in a twin-screw extruder. The temperatures of the twin-screw extruder are successively 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C, and 190°C - 200°C in the direction of material advancement, and the head temperature is 180°C - 190°C.

[0015] Due to the application of the above technical solution, the advantages of the present invention compared with the prior art are as follows:

[0016] The halogen-free flame-retardant composition of the present invention acts together with the solid aromatic diol compound, which can not only improve the flame-retardant performance of the material, but also have no adverse effect on the mechanical properties of the main material. Specific Embodiments

[0017] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0018] Example 1: A halogen-free flame-retardant thermoplastic polyurethane elastomer and its preparation method

[0019] A halogen-free flame-retardant thermoplastic polyurethane elastomer (halogen-free flame-retardant TPU) is as follows:

[0020] By weight, first, 71.3 parts by weight of TPU, 17 parts by weight of aluminum diethyl phosphinate, 9 parts by weight of aluminum tripolyphosphate, and 0.4 parts by weight of hydroquinone di(2-hydroxyethyl) ether are placed in a high-speed mixer for mixing. The mixing is carried out at room temperature and a mixing speed of 900 rpm for 7 minutes. During this process, the component materials are stirred by the stirring blades of the high-speed mixer, and the materials are fully mixed and homogenized through convection, diffusion, and shear actions. The mixture is then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which is dried and processed into injection-molded standard specimens.

[0021] The temperatures of the twin-screw extruder are successively 150°C, 165°C, 175°C, 185°C, 195°C, 195°C, and 195°C in the direction of material advancement, and the head temperature is 185°C.

[0022] The present invention uses a solid aromatic diol compound and a halogen-free flame retardant system to compound a flame retardant composition for manufacturing a halogen-free flame retardant TPU composition. It can effectively reduce the melt viscosity of the halogen-free flame retardant TPU composition. The reason is that the solid aromatic diol compound has a low melting point, and its alcohol hydroxyl group forms hydrogen bonds with the phosphorus-based and nitrogen-based flame retardants and the amino group in the TPU, playing a certain internal plasticizing role. During the operation of the melt screw of the halogen-free flame retardant TPU composition, it reduces the shear friction between the melt of the TPU composition inside and the inner wall of the extruder barrel and the surface of the screw, reduces the generation of shear friction heat, and helps the halogen-free flame retardant composite to be evenly dispersed in the TPU matrix. In addition, there are benzene rings and alcohol hydroxyl groups in the molecule of the solid aromatic diol compound, which produce a good flame retardant synergistic effect with the phosphorus-based flame retardant and the compatibility with the TPU matrix. It improves the flame retardancy of the halogen-free flame retardant TPU composition and the anti-bleeding property of the flame retardant, which helps the application of this product in wire and cable.

[0023] Example 2: A halogen-free flame retardant thermoplastic polyurethane elastomer and its preparation method

[0024] First, 72.2 parts by weight of TPU, 18 parts by weight of aluminum diethyl phosphinate, 9 parts by weight of aluminum tripolyphosphate, and 0.8 part by weight of hydroquinone dihydroxyethyl ether are placed in a high-speed mixer for mixing. The mixing is carried out at a mixing temperature of room temperature and a mixing speed of 900 rpm for 7 minutes. During this process, the component materials are stirred by the stirring paddle of the high-speed mixer, and the materials are fully mixed evenly through convection, diffusion, and shear effects. The mixture is then extruded and granulated by a twin-screw extruder to obtain a halogen-free flame retardant TPU material, which is dried and injection molded into standard specimens.

[0025] The step of melt extrusion is carried out in a twin-screw extruder. The temperatures of the twin-screw extruder are successively 140 °C, 160 °C, 170 °C, 180 °C, 190 °C, 190 °C, and 190 °C in the direction of the material advance, and the head temperature is 180 °C.

[0026] Example 3: A halogen-free flame retardant thermoplastic polyurethane elastomer and its preparation method

[0027] This example provides a halogen-free flame retardant TPU as follows:

[0028] First, 73.2 parts by weight of TPU, 18 parts by weight of aluminum diethyl phosphinate, 8 parts by weight of aluminum polyphosphite, and 0.8 part by weight of resorcinol-bis(β-hydroxyethyl) ether are placed in a high-speed mixer for mixing. The mixing is carried out at room temperature and a mixing speed of 900 rpm for 7 minutes. During this process, the component materials are rotated by the stirring paddle of the high-speed mixer, and the materials are fully mixed and homogenized through convection, diffusion, and shear actions. The mixture is then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which is dried and injection-molded into standard specimens.

[0029] The step of melt extrusion is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is successively 160°C, 170°C, 180°C, 190°C, 200°C, 200°C, and 200°C in the direction of material advancement, and the head temperature is 190°C.

[0030] Example 4: A halogen-free flame-retardant thermoplastic polyurethane elastomer and its preparation method

[0031] This example provides a halogen-free flame-retardant TPU as follows:

[0032] First, 73 parts by weight of TPU, 21 parts by weight of aluminum phosphinate, 5 parts by weight of organic montmorillonite, and 1.0 part by weight of a para-substituted phenylene ether diol mixture mainly composed of 4-hydroxyethyloxyethyl-1-hydroxyethyl benzene diol are placed in a high-speed mixer for mixing. The mixing is carried out at room temperature and a mixing speed of 900 rpm for 7 minutes. During this process, the component materials are rotated by the stirring paddle of the high-speed mixer, and the materials are fully mixed and homogenized through convection, diffusion, and shear actions. The mixture is then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which is dried and injection-molded into standard specimens.

[0033] The step of melt extrusion is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is successively 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C, and 190°C - 200°C in the direction of material advancement, and the head temperature is 180°C - 190°C.

[0034] Example 5: A halogen-free flame-retardant thermoplastic polyurethane elastomer and its preparation method

[0035] This example provides a halogen-free flame-retardant TPU as follows:

[0036] First, 72 parts by weight of TPU, 18 parts by weight of aluminum hypophosphite, 9 parts by weight of aluminum tripolyphosphate, and 1.0 part by weight of a meta-substituted phenyl ether diol mixture mainly composed of 3-hydroxyethyl oxyethyl-1-hydroxyethyl phenyl ether are placed in a high-speed mixer for mixing. The mixing is carried out at room temperature and a mixing speed of 900 rpm for 7 minutes. During this process, the component materials are rotated by the stirring paddle of the high-speed mixer, and the materials are fully mixed and homogenized through convection, diffusion, and shear actions. The mixture is then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which is dried and injection-molded into standard specimens.

[0037] The step of melt extrusion is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is successively 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C, and 190°C - 200°C in the direction of material advancement, and the head temperature is 180°C - 190°C.

[0038] Example 6: A halogen-free flame-retardant thermoplastic polyurethane elastomer and its preparation method

[0039] This example provides a flame-retardant composition and a polyamide plastic, specifically as follows:

[0040] This example provides a halogen-free flame-retardant TPU, specifically as follows:

[0041] First, 72.1 parts by weight of TPU, 20 parts by weight of aluminum hypophosphite, 7 parts by weight of polyaluminum phosphite, and 0.9 part by weight of hydroquinone bis(2-hydroxyethyl) ether are placed in a high-speed mixer for mixing. The mixing is carried out at room temperature and a mixing speed of 900 rpm for 7 minutes. During this process, the component materials are rotated by the stirring paddle of the high-speed mixer, and the materials are fully mixed and homogenized through convection, diffusion, and shear actions. The mixture is then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which is dried and injection-molded into standard specimens.

[0042] The step of melt extrusion is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is successively 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C, and 190°C - 200°C in the direction of material advancement, and the head temperature is 180°C - 190°C.

[0043] Example 7: A halogen-free flame-retardant thermoplastic polyurethane elastomer and its preparation method

[0044] This example provides a halogen-free flame-retardant TPU, specifically as follows:

[0045] First, 68.1 parts by weight of TPU, 22 parts by weight of aluminum diethylphosphinate, 9 parts by weight of aluminum tripolyphosphate, and 0.9 part by weight of resorcinol-bis(β-hydroxyethyl) ether were placed in a high-speed mixer for mixing. The mixing was carried out at room temperature with a mixing speed of 900 rpm for 7 minutes. During this process, the component materials were rotated by the stirring paddle of the high-speed mixer, and the materials were fully mixed and homogenized through convection, diffusion, and shear effects. The mixture was then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which was dried and injection-molded into standard specimens.

[0046] The step of melt extrusion is carried out in a twin-screw extruder. The temperatures of the twin-screw extruder are successively 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C, and 190°C - 200°C in the direction of material advancement, and the head temperature is 180°C - 190°C.

[0047] Comparative Example 1

[0048] This comparative example provides a halogen-free flame-retardant TPU as follows:

[0049] First, 63 parts of TPU, 22 parts of aluminum diethylphosphinate, and 15 parts of aluminum tripolyphosphate were placed in a high-speed mixer for mixing. The mixing was carried out at room temperature with a mixing speed of 900 rpm for 7 minutes. During this process, the component materials were rotated by the stirring paddle of the high-speed mixer, and the materials were fully mixed and homogenized through convection, diffusion, and shear effects. The mixture was then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which was dried and injection-molded into standard specimens.

[0050] Comparative Example 2

[0051] This comparative example provides a halogen-free flame-retardant TPU as follows:

[0052] First, 63 parts of TPU, 23 parts of phosphinic acid aluminum, 10 parts of MCA, and 5 parts of organic montmorillonite were placed in a high-speed mixer for mixing. The mixing was carried out at room temperature with a mixing speed of 900 rpm for 7 minutes. During this process, the component materials were rotated by the stirring paddle of the high-speed mixer, and the materials were fully mixed and homogenized through convection, diffusion, and shear effects. The mixture was then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material, which was dried and injection-molded into standard specimens.

[0053] Comparative Example 3

[0054] This comparative example provides a halogen-free flame-retardant TPU as follows:

[0055] First, 67 parts of TPU, 20 parts of aluminum diethyl phosphinate, and 13 parts of MCA were placed in a high-speed mixer for mixing. The mixing was carried out at room temperature with a mixing speed of 900 rpm for 7 minutes. During this process, the component materials were rotated by the stirring paddle of the high-speed mixer, and the materials were fully mixed and homogenized through convection, diffusion, and shear actions. The mixture was then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material. After drying treatment, standard specimens were injection-molded.

[0056] Comparative Example 4

[0057] This comparative example provides a halogen-free flame-retardant TPU, specifically as follows:

[0058] First, 64 parts of TPU, 21 parts of aluminum phosphinate, and 15 parts of MCA were placed in a high-speed mixer for mixing. The mixing was carried out at room temperature with a mixing speed of 900 rpm for 7 minutes. During this process, the component materials were rotated by the stirring paddle of the high-speed mixer, and the materials were fully mixed and homogenized through convection, diffusion, and shear actions. The mixture was then extruded and pelletized using a twin-screw extruder to obtain a halogen-free flame-retardant TPU material. After drying treatment, standard specimens were injection-molded.

[0059] Effect verification test

[0060] Effect verification experiments were carried out on Examples 1-7 and Comparative Examples 1-4 above. The tensile strength, elongation at break, oxygen index, vertical burning, and melt flow rate of the halogen-free flame-retardant TPU materials were measured.

[0061] Among them, the tensile strength was tested in accordance with GB / T1040.2-2006;

[0062] The elongation at break was tested in accordance with GB / T1040.2-2006;

[0063] The oxygen index was tested in accordance with GB / T2406.2-2009;

[0064] The vertical burning was tested in accordance with GB / T2408-2008;

[0065] The melt flow rate was tested in accordance with GBT3682-2018.

[0066] The process parameters and performance test results of Examples 1-7 and Comparative Examples 1-4 are shown in Table 1.

[0067] Table 1 Process parameters and performance test results of Examples 1-7 and Comparative Examples 1-4

[0068] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Parts by weight TPU 73.1 72.2 73.2 73 72 72.1 68.1 63 63 67 64 Parts by weight Aluminum diethylphosphinate 17 18 18 0 0 0 22 22 0 20 0 Parts by weight Phosphinate 0 0 0 21 18 20 0 0 23 0 21 Parts by weight MCA 0 0 0 0 0 0 0 0 10 13 15 Parts by weight Aluminum tripolyphosphate 9 9 0 0 9 0 9 15 0 0 0 Parts by weight Organic montmorillonite 0 0 0 5 0 0 0 0 5 0 0 Parts by weight Aluminum polyphosphite 0 0 8 0 0 7 0 0 0 0 0 Parts by weight Hydroquinone bis(2-hydroxyethyl) ether 0.4 0.8 0 0 0 0.9 0 0 0 0 0 Parts by weight Resorcinol-bis(β-hydroxyethyl) ether 0 0 0.8 0 0 0 0.9 0 0 0 0 Parts by weight Para-substituted phenol glycol mixture mainly composed of 4-hydroxyethyloxyethyl-1-hydroxyethyl benzene diether 0 0 0 1.0 0 0 0 0 0 0 0 Parts by weight Meta-substituted phenol glycol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethyl benzene diether 0 0 0 0 1.0 0 0 0 0 0 0 TPU material properties Tensile strength / MPa 10.41 11.98 12.35 11.23 11.65 12.08 12.35 9.62 8.23 9.53 9.52 TPU material properties Elongation at break / % 523 498 505 495 510 490 497 472 450 471 463 TPU material properties Oxygen index / % 28..3 29.1 29.1 29.0 29.5 29.5 29.5 27.1 27.9 27.2 27.3 TPU material properties Vertical burning / S V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-1 V-0 V-1 V-1 TPU material properties Melt flow rate g / 10min g / 10min (190 °C, 5000 g load) 17.32 16.58 16.03 15.40 17.20 15.45 16.60 10.23 9.80 12.03 10.13

[0069] As shown in Table 1, by compounding a processing aid with a solid aromatic diol compound (a para-substituted phenylene ether diol mixture mainly composed of hydroquinone dihydroxyethyl ether, resorcinol-bis(β-hydroxyethyl) ether, hydroxyethyloxyethyl-1-hydroxyethyl phenylene ether, and a meta-substituted phenylene ether diol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethyl phenylene ether) and a halogen-free flame retardant in a specific ratio and using them in the manufacture of thermoplastic elastomer TPU, a good flame retardant synergistic effect can be produced, effectively reducing the amount of flame retardant used and improving the mechanical properties, flame retardant properties, and melt fluidity of the TPU material.

[0070] Example 8: A halogen-free flame retardant thermoplastic polyurethane elastomer and its preparation method

[0071] One aspect of the present invention provides a flame retardant composition, and the components of the flame retardant composition include:

[0072] The halogen-free flame retardant composition includes the following raw materials: 60% - 80% thermoplastic elastomer TPU, 20% - 40% halogen-free flame retardant composition, and 0.3% - 2% solid aromatic diol compound processing aid. Among them, the halogen-free flame retardant composition is 15 - 30% aluminum diethylphosphinate or aluminum hypophosphite, 5% - 10% aluminum tripolyphosphate, 2% - 6% organic montmorillonite, 5% - 10% polyaluminum phosphite; the solid aromatic diol compound is 0.1% - 1.2% hydroquinone dihydroxyethyl ether or resorcinol-bis(β-hydroxyethyl) ether, a para-substituted phenylene ether diol mixture mainly composed of 0.2% - 1.2% -hydroxyethyloxyethyl-1-hydroxyethyl phenylene ether, or a meta-substituted phenylene ether diol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethyl phenylene ether.

[0073] In some of these embodiments, the components of the flame retardant composition include: 62% - 78% thermoplastic elastomer TPU, 21% - 40% halogen-free flame retardant composition, and 0.4% - 1.8% solid aromatic diol compound processing aid.

[0074] Among them, the halogen-free flame retardant composition is at least one of 16 - 28% aluminum diethylphosphinate or aluminum hypophosphite, 6% - 9% aluminum tripolyphosphate, 2% - 6% organic montmorillonite, 6% - 9% polyaluminum phosphite.

[0075] Among them, the solid aromatic diol compound is at least one of 0.3% - 1.1% hydroquinone dihydroxyethyl ether or resorcinol-bis(β-hydroxyethyl) ether, a para-substituted phenylene ether diol mixture mainly composed of 0.3% - 1.1% -hydroxyethyloxyethyl-1-hydroxyethyl phenylene ether, or a meta-substituted phenylene ether diol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethyl phenylene ether.

[0076] The present invention also provides a method for preparing a halogen-free flame-retardant thermoplastic elastomer TPU material, which comprises the following steps:

[0077] According to the raw material ratio of the halogen-free flame-retardant thermoplastic elastomer TPU material, the halogen-free flame-retardant composition, the TPU resin and the solid aromatic diol compound processing aid are mixed to obtain a mixture;

[0078] The mixture is heated to melt and melt-extruded to obtain the halogen-free flame-retardant thermoplastic elastomer TPU material.

[0079] In some embodiments, the material mixing is carried out in a high-speed mixer, the mixing speed is 800 - 1200 rpm, and the heating time is 5 min - 8 min. The melt-extrusion step is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is successively 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C and 190°C - 200°C in the direction of material advancement, and the head temperature is 180°C - 190°C.

[0080] In the flame-retardant composition of the present invention, with the above specific components and ratios, through the combined action of aluminum diethylphosphinate or aluminum hypophosphite, aluminum tripolyphosphate, organic montmorillonite, aluminum polyphosphite and a para-substituted phenol ether diol mixture mainly composed of hydroquinone dihydroxyethyl ether or resorcinol-bis(β-hydroxyethyl) ether, hydroxyethyloxyethyl-1-hydroxyethylphenyl ether or a meta-substituted phenol ether diol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethylphenyl ether, not only can the flame-retardant performance of the material be improved, but also it will not have an adverse impact on the mechanical properties of the main material.

[0081] Among them, in the flame retardant composition of the present invention, aluminum diethyl phosphinate or aluminum hypophosphite is the main component, and is compounded with aluminum tripolyphosphate, organic montmorillonite, and aluminum polyphosphite in a specific ratio, having excellent coordinated flame retardant effects. At the same time, a para-substituted phenyl ether diol mixture mainly composed of hydroquinone bis(2-hydroxyethyl) ether or resorcinol-bis(β-hydroxyethyl) ether, hydroxyethyloxyethyl-1-hydroxyethyl phenyl ether, or a meta-substituted phenyl ether diol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethyl phenyl ether and a phosphorus-nitrogen-phosphorus flame retardant compound are uniformly dispersed in the TPU material through a melt mechanical mixing technique. The alcohol hydroxyl groups in their molecular structures form hydrogen bonds with the phosphorus-based and nitrogen-based flame retardants, forming a composition that enhances and synergizes the flame retardant effect in the polyurethane elastomer. And hydroquinone bis(2-hydroxyethyl) ether or resorcinol-bis(β-hydroxyethyl) ether, hydroxyethyloxyethyl-1-hydroxyethyl phenyl ether, or a para-substituted phenyl ether diol mixture mainly composed of 3-hydroxyethyloxyethyl-1-hydroxyethyl phenyl ether dehydrates during the combustion of TPU and reacts with aluminum hypophosphite or aluminum diethyl phosphinate to form pyrophosphoric acid, which plays a role in forming carbon to block air, thereby obtaining a flame retardant effect of a high-performance halogen-free flame retardant TPU material. At the same time, the compatibility between the halogen-free flame retardant and the TPU matrix is improved, and the anti-bleeding property of the flame retardant is enhanced.

[0082] The halogen-free flame retardant composition requires relatively low cost and is easy to operate, and can be widely applied.

[0083] Example 9:

[0084] There are many solutions for using halogen-free flame retardant TPU in the traditional technology. The halogen-free flame retardant is low-smoke and halogen-free, and the obtained halogen-free flame retardant TPU material has good flame retardant performance. However, after a large number of studies and tests on the flame retardants used in traditional flame retardant TPU, the present invention found that there are some deficiencies in traditional halogen-free flame retardants. For example, when using aluminum diethyl phosphinate, due to its fine particle size, it is prone to agglomeration during its use, which affects the product appearance. When used in cables, it is easy to break down, affecting the product insulation. At the same time, excessive use will affect the mechanical strength of the product.

[0085] Based on this, after long-term research and a large number of creative experiments by the technical personnel of the present invention, it was unexpectedly found that using solid aromatic diol compounds in the preparation of halogen-free flame retardant TPU can effectively reduce the melt viscosity of halogen-free flame retardant TPU, thereby improving the molding processability of the flame retardant material. At the same time, it helps the halogen-free flame retardant to be uniformly dispersed in the TPU matrix, effectively preventing the agglomeration of the powder halogen-free flame retardant, and there are no agglomerated white spots of the flame retardant on the surface of the extruded strip, which helps to improve the product quality.

[0086] The present invention provides a flame retardant composition. By weight percentage, its raw materials include 70% thermoplastic elastomer TPU, 29% halogen-free flame retardant composition, and 1% processing aid.

[0087] The above are only preferred embodiments for explaining the present invention, and are not intended to impose any form of limitation on the present invention. Therefore, any modification or change to the present invention made under the same inventive spirit shall still be included within the scope intended to be protected by the present invention.

Claims

1. A halogen-free flame-retardant thermoplastic polyurethane elastomer, characterized in that: The raw material formula includes the following raw materials: thermoplastic polyurethane elastomer, halogen-free flame retardant composition, and solid aromatic diol compounds. By weight, it specifically includes: 71.3 parts by weight of thermoplastic polyurethane elastomer, 17 parts by weight of aluminum diethyl phosphinate, 9 parts by weight of aluminum tripolyphosphate, and 0.4 parts by weight of hydroquinone bis(2-hydroxyethyl) ether solid aromatic diol compounds 2. A preparation method of a halogen-free flame-retardant thermoplastic polyurethane elastomer, characterized in that: It includes the following steps: Step 1: According to the raw material formula described in Claim 1, mix the halogen-free flame retardant composition, thermoplastic polyurethane elastomer, and solid aromatic diol compounds to obtain a mixture; Step 2: Heat the mixture to melting and conduct melt extrusion to obtain halogen-free flame retardant thermoplastic polyurethane elastomer; The mixing in Step 1 is carried out at room temperature. The mixing equipment uses a high-speed mixer, and the mixing speed of the high-speed mixer is 800 - 1200 rpm, and the mixing time is 5 min - 8 min; The step of melt extrusion is carried out in a twin-screw extruder. The temperatures of the twin-screw extruder are in sequence along the material advancing direction: 140°C - 160°C, 160°C - 170°C, 170 - 180°C, 180°C - 190°C, 190°C - 200°C, 190°C - 200°C, and 190°C - 200°C, and the head temperature is 180°C - 190°C.