Low-temperature flame-retardant polyurethane material for coal mine as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of materials for mines, and particularly relates to a low-temperature flame-retardant polyurethane material for a coal mine as well as a preparation method and application of the low-temperature flame-retardant polyurethane material. The low-temperature flame-retardant polyurethane material for the coal mine comprises the following raw material components in parts by weight: 30-40 parts of polyether polyol, 35-45 parts of isocyanate, 1-3 parts of a modifier, 1-3 parts of a catalyst, 5-10 parts of a flame retardant, 5-10 parts of a foaming agent and 10-15 parts of a stabilizer. The low-temperature flame-retardant polyurethane material for the coal mine has the characteristics of low-temperature synthesis, strong flame retardant property, good fluidity, high strength and the like, can be tightly bonded with coal briquettes without gaps, has a better sealing effect and plays a role in leaking stoppage. Meanwhile, the high-strength flame-retardant cable has high strength and better flame retardance, and has the advantages of low temperature, flame retardance, high strength and good safety when being used in coal mines.

Description

Technical Field

[0001] The invention belongs to the technical field of mine materials, and particularly relates to a low-temperature flame-retardant polyurethane material for coal mines, a preparation method and application thereof. Background Art

[0002] Spontaneous combustion of coal is one of the major disasters in coal mines. Spontaneous combustion of coal in mines mainly occurs in goaf areas. Spontaneous combustion of coal has always been a global problem that threatens the safe production of coal mines. Areas with abnormal geological structures, isolated coal pillars, air leakage in goaf areas, and falling tunnels in mines are high-incidence areas for spontaneous combustion of coal. In my country, goaf areas caused by underground mining in mines will become unstable, which will cause large-scale falling of goaf areas and affect the structural safety of mines.

[0003] Polyurethane polymer materials are commonly used underground plugging materials. Due to their inherent flammability, they are prone to cause fires. At present, there are many studies on the various properties of polyurethane. However, as a common underground plugging material, polyurethane is prone to spontaneous combustion of coal seams. When polyurethane is used to reinforce coal seams, the internal temperature of the coal seams rises during the long-term action process, causing heat accumulation. When a certain temperature is reached, it will aggravate the spontaneous combustion of coal, causing fires and causing economic losses. In recent years, fires caused by polyurethane reinforcement have increased. Therefore, it is very necessary to develop a low-temperature synthesized polyurethane material with good flame retardant properties for coal mines to solve the above problems.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a low-temperature flame-retardant polyurethane material for coal mines, and a preparation method and application thereof; the low-temperature flame-retardant polyurethane material for coal mines has the characteristics of low-temperature synthesis, strong flame retardant performance, good fluidity, high strength, etc., can be tightly bonded to coal blocks without gaps, has a good sealing effect, and plays a leak-proof effect.

[0006] In order to overcome the deficiencies of the prior art, the present invention provides the following technical solutions: A low-temperature flame-retardant polyurethane material for coal mines comprises the following raw material components by weight: 30-40 parts of polyether polyol, 35-45 parts of isocyanate, 1-3 parts of modifier, 1-3 parts of catalyst, 5-10 parts of flame retardant, 5-10 parts of foaming agent and 10-15 parts of stabilizer.

[0007] Furthermore, the following raw material components are included in parts by weight: 34 parts of polyether polyol, 38 parts of isocyanate, 1 part of modifier, 1 part of catalyst, 7 parts of flame retardant, 6 parts of foaming agent, and 13 parts of stabilizer.

[0008] Further, the isocyanate includes one or both of hexamethylene diisocyanate and isophorone diisocyanate.

[0009] Further, the isocyanate is a mixture of hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of hexamethylene diisocyanate to isophorone diisocyanate is 1:1.

[0010] Further, the polyether polyol includes one or both of polyether polyol N330 and polyether polyol N303.

[0011] Further, the polyether polyol is a mixture of polyether polyol N330 and polyether polyol N303; the weight ratio of polyether polyol N330 to polyether polyol N303 is 1:1.

[0012] Further, the catalyst includes one or both of tertiary amine catalysts and tin catalysts; and / or, the flame retardant includes one or both of nano flame retardants and aluminum diethyl phosphinate.

[0013] and / or, the blowing agent is HCFC-141b; and / or, the stabilizer is dimethyl silicone oil.

[0014] In addition, the present invention also provides a preparation method of the low-temperature flame-retardant polyurethane material for coal mines as described above, including the following steps: Add the polyether polyol, catalyst, stabilizer, modifier, and flame retardant into a reaction vessel in sequence. After mixing evenly, add the blowing agent. After continuing to stir evenly, add the isocyanate and mix evenly to obtain the low-temperature flame-retardant polyurethane material for coal mines.

[0015] Further, it also includes the following step: Mix hexamethylene diisocyanate and isophorone diisocyanate evenly according to a weight ratio of 1:1; and / or, mix polyether polyol N330 and polyether polyol N303 evenly according to a weight ratio of 1:1.

[0016] In addition, the present invention also provides an application of the above-mentioned low-temperature flame-retardant polyurethane material for coal mines and the low-temperature flame-retardant polyurethane material for coal mines prepared by the above-mentioned preparation method as a plugging material in coal mines.

[0017] Compared with the prior art, the technical solution of the present invention has at least the following technical effects: 1. The low-temperature flame-retardant polyurethane material for coal mines of the present invention has the characteristics of low-temperature synthesis, strong flame-retardant performance, good fluidity, high strength, etc. It can adhere tightly to the bonding part of coal blocks without gaps, has a good sealing effect, and plays a role in plugging leaks. At the same time, it has high strength and good flame-retardant performance, and has the advantages of good safety such as low temperature, flame retardancy, and high strength when used in coal mines.

[0018] 2. In the preparation method of the present invention, the temperature for synthesizing polyurethane is relatively low, which has little influence on coal spontaneous combustion. The excellent adhesion between polyurethane and coal blocks enables polyurethane to play a role in filling and sealing, enhancing the stability of the goaf, and avoiding the occurrence of roof fall accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The schematic drawings in the specification that form a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. Among them: Figure 1 It is a comparative schematic diagram of the thermogravimetric curves of polyurethane (PU-CNTS-ADP) with two flame retardants added and polyurethane (PU-0) without flame retardant added in a nitrogen atmosphere.

[0020] Figure 2 It is the TG-DTG curve of polyurethane with two flame retardants added in a nitrogen atmosphere in a nitrogen atmosphere.

[0021] Figure 3 It is a comparative schematic diagram of the thermogravimetric curves of polyurethane (PU-CNTS-ADP) with two flame retardants added and polyurethane (PU-0) without flame retardant added in an oxygen atmosphere. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. The process parameters without specific conditions noted in the following embodiments are usually in accordance with conventional conditions.

[0023] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0024] According to a first aspect of the present invention, a low-temperature flame-retardant polyurethane material for coal mines is provided, which comprises the following raw material components in parts by weight: 30 to 40 parts (for example, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, and 40 parts) of polyether polyol, 35 to 45 parts (for example, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, and 40 parts) of isocyanate, and 35 to 45 parts (for example, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, and 43 parts) of isocyanate. 3 parts, 44 parts, 45 parts), modifier 1-3 parts (for example 1 part, 2 parts, 3 parts), catalyst 1-3 parts (for example 1 part, 2 parts, 3 parts), flame retardant 5-10 parts (for example 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts), foaming agent 5-10 parts (for example 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts), stabilizer 10-15 parts (for example 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts).

[0025] The weight parts described in the present invention mainly include the disclosed numerical range, any numerical value (including integers and decimals) or any interval between two numerical values ​​in the disclosed range, or multiple discontinuous intervals, and also include numerical values ​​or numerical ranges close to the end values ​​of the numerical range whose effects can be expected to be similar, such as 5-10 parts, not only including 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts and any interval between two parts, but also other numerical ranges, which are not given one by one, are all included in the present invention. Therefore, the present invention also includes the sub-range of any numerical range that has been directly disclosed or any specific numerical value therein.

[0026] The low-temperature flame-retardant polyurethane material of the present invention has the characteristics of low-temperature synthesis, strong flame-retardant performance, good fluidity, high strength, etc. under the synergistic effect of various components, can be tightly bonded with coal blocks without gaps, has good sealing effect, and plays a leak-proof effect. At the same time, it has high strength and good flame-retardant performance, and has the advantages of low temperature, flame retardant, high strength, and good safety when used in coal mines.

[0027] In particular, the effect of modifiers on polyurethane synthesis is mainly reflected in the role of adhesion and chain extension in the polyurethane synthesis process. This role can enhance the mechanical properties of the synthesized polyurethane and improve the adhesion between the matrix and the filler.

[0028] The addition of stabilizers stabilizes the performance of the synthesized polyurethane. After adding stabilizers, the synthesized polyurethane foam is uniform and the flame retardant is evenly distributed. During the synthesis process of polyurethane without adding stabilizers, other reagents will agglomerate during the stirring process, and the foam will be uneven. During the curing process of polyurethane, if stabilizers are not added, cracks of varying degrees will appear during the curing process. This shows that stabilizers not only play a stabilizing role in the synthesis process of polyurethane, but also have a certain effect on stabilizing the comprehensive performance of polyurethane.

[0029] Catalysts play an important role in regulating the reaction rate of polyurethane synthesis. The commonly used polyurethane catalysts mainly include tertiary amine catalysts and organotin catalysts. The important role of catalysts is to catalyze internal reactions. The two types of catalysts have different focuses. The main role of tertiary amine catalysts is the synthesis reaction of -NCO and -OH, and at the same time promote CO 2 gas, which can promote the formation of bubbles and volume expansion in the polyurethane synthesis reaction. During the polyurethane synthesis process, although tertiary amine catalysts have a certain catalytic effect on the NCO-OH reaction, they have a stronger catalytic effect on the NCO-H2O reaction. Organotin catalysts can make up for the deficiencies of tertiary amine catalysts and show a strong catalytic effect on the NCO-OH reaction. Therefore, in this chapter, triethylenediamine in tertiary amine catalysts and stannous octoate in organotin catalysts are selected as composite catalysts to catalyze the synthesis reaction of polyurethane.

[0030] In particular, blowing agents play an important role in the foaming of polyurethane synthesis. The role of polyurethane blowing agents is to introduce gas and promote the foaming reaction, so that a foam structure can be formed. During the reaction process, gas is introduced to form the pore structure of the foam.

[0031] To further improve the effect of low-temperature flame-retardant polyurethane materials for coal mines, this invention studied the influence degree of different ratios of various raw material components on their properties, and respectively obtained more optimal raw material component ratios: 34 parts of polyether polyol, 38 parts of isocyanate, 1 part of modifier, 1 part of catalyst, 7 parts of flame retardant, 6 parts of blowing agent, and 13 parts of stabilizer.

[0032] In the above-mentioned low-temperature flame-retardant polyurethane materials for coal mines, as a preferred embodiment, the isocyanate includes one or both of hexamethylene diisocyanate and isophorone diisocyanate.

[0033] Preferably, the isocyanate is a mixture of hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of hexamethylene diisocyanate to isophorone diisocyanate is 1:1. When two isocyanates, isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI), are mixed in different ratios, when the proportion of isophorone diisocyanate is high, the strength of the synthesized polyurethane is high, but the synthesis temperature is relatively high. When the proportion of hexamethylene diisocyanate is relatively high, the hardness of the synthesized polyurethane will decrease, and the synthesis temperature will also decrease.

[0034] In the above-mentioned low-temperature flame-retardant polyurethane materials for coal mines, as a preferred embodiment, the polyether polyol includes one or both of polyether polyol N330 and polyether polyol N303.

[0035] Preferably, the polyether polyol is a mixture of polyether polyol N330 and polyether polyol N303; the weight ratio of the polyether polyol N330 to the polyether polyol N303 is 1:1.

[0036] Regarding the hydroxyl values of the two polyols, polyether polyol N330 and N303, they are different. The difference in hydroxyl values will have different effects on the reaction rate. However, the difference in hydroxyl values will affect the strength of the synthesized polyurethane. The higher the hydroxyl value, the higher the reaction rate and the strength, but the higher the synthesis temperature. By compounding these two polyether polyols, a balance between strength and temperature can be achieved. Therefore, by compounding the two polyols, the synergistic effect of these two polyether polyols is mainly reflected in the coordination of temperature and strength. The synthesis temperatures of polyurethane using polyether polyol N330 and N303 are also different. The strength of the polyurethane synthesized from polyether polyol N330 is greater than that synthesized from polyether polyol N303. Compared with polyether polyol N303 and N330, under the same conditions, the strength of the polyurethane synthesized from polyether polyol N330 is greater than that of polyether polyol N303. In the synthesis process of polyurethane, the issues of temperature and strength need to be comprehensively considered. At the same time, considering the economic value, polyether polyol N303 and N330 can be selected for compounding to prepare a polyurethane for low-temperature synthesis.

[0037] In the above-mentioned low-temperature flame-retardant polyurethane material for coal mines, as a preferred embodiment, the catalyst includes one or both of tertiary amine catalysts and tin catalysts; Optionally, the flame retardant includes one or both of nano flame retardants and aluminum diethyl phosphinate.

[0038] Optionally, the modifier is a silane coupling agent; Optionally, the blowing agent is HCFC-141b; Optionally, the stabilizer is dimethyl silicone oil.

[0039] According to the second aspect of the present invention, a preparation method of the above-mentioned low-temperature flame-retardant polyurethane material for coal mines is provided, including the following steps: Add the polyether polyol, catalyst, stabilizer, modifier, and flame retardant into a reaction vessel in sequence. After mixing evenly, add the blowing agent. After continuing to stir evenly, add the isocyanate, and mix evenly to obtain the low-temperature flame-retardant polyurethane material for coal mines.

[0040] In the preparation method of the low-temperature flame-retardant polyurethane material for coal mines of the present invention, the highest synthesis temperature of the low-temperature synthesized polyurethane is 51.2 °C. The synthesis temperature is an important safety performance that affects its use in mines during the grouting of polyurethane. Specifically, after adding isocyanate and mixing evenly, a test sample weighing 200 ml is taken. After stirring for 15 s - 30 s under a magnetic stirrer, it is poured into a cylindrical glass container with a diameter of 50 mm. A temperature sensor is used to record the temperature change during the whole process and record the highest reaction temperature. The temperature sensor used is a KT100 thermocouple, and the thermocouple is used to measure the temperature change during the whole polyurethane synthesis process.

[0041] In the preparation process of the present invention, the temperature for synthesizing polyurethane is relatively low, and the influence on coal spontaneous combustion is small. The excellent adhesion between polyurethane and coal blocks enables polyurethane to play a role in filling and sealing, enhancing the stability of the goaf, and avoiding the occurrence of roof fall accidents.

[0042] In the above preparation method, as a preferred embodiment, the following steps are further included: mixing hexamethylene diisocyanate and isophorone diisocyanate evenly according to a weight ratio of 1:1; Optionally, polyether polyol N330 and polyether polyol N303 are mixed evenly according to a weight ratio of 1:1.

[0043] According to the third aspect of the present invention, there is provided an application of the low-temperature flame-retardant polyurethane material for coal mines as described above as a plugging material in coal mines.

[0044] The present invention will be described in detail below in conjunction with the embodiments of the present invention. Each example is provided by way of explanation of the present invention rather than limitation of the present invention. In fact, those skilled in the art will clearly understand that modifications and variations can be made to the present invention without departing from the scope or spirit of the present invention. For example, features shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention includes such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0045] In the embodiments of the present invention, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0046] Example 1 This embodiment provides a low-temperature flame-retardant polyurethane material for coal mines, and the contents of each component are as follows: 17 parts of polyether polyol N330, 17 parts of polyether polyol N303, 19 parts of hexamethylene diisocyanate, 19 parts of isophorone diisocyanate, 1 part of silane coupling agent, 1 part of stannous octoate, 7 parts of aluminum diethylphosphinate and carbon nanotubes (the weight ratio of aluminum diethylphosphinate to carbon nanotubes is 1:1), 6 parts of HCFC-141b, and 13 parts of dimethyl silicone oil; The preparation method is as follows: (1) Preparation of component A: Mix polyether polyol N303 and N330 in a ratio of 1:1. After mixing, put the catalyst stannous octoate and triethylenediamine, the flame retardant aluminum diethylphosphinate and carbon nanotubes, the stabilizer dimethyl silicone oil, and the modifier silane coupling agent into a reaction vessel and mix and stir evenly. Finally, add the blowing agent HCFC-141 and stir evenly; (2) Preparation of component B: Mix hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) in a ratio of 1:1 and stir evenly to obtain component B; (3) Mix components A and B in a mass ratio of 1:1 and stir evenly to obtain the low-temperature flame-retardant polyurethane material for coal mines of this embodiment.

[0047] Example 2 This embodiment provides a low-temperature flame-retardant polyurethane material for coal mines, and the contents of each component are as follows: 15 parts of polyether polyol N330, 15 parts of polyether polyol N303, 18 parts of hexamethylene diisocyanate, 18 parts of isophorone diisocyanate, 2 parts of silane coupling agent, 2 parts of stannous octoate, 5 parts of aluminum diethylphosphinate and carbon nanotubes (the weight ratio of aluminum diethylphosphinate to carbon nanotubes is 1:1), 5 parts of HCFC-141b, and 10 parts of dimethyl silicone oil; The preparation method of this embodiment is the same as that of Example 1.

[0048] Example 3 This embodiment provides a low-temperature flame-retardant polyurethane material for coal mines, and the contents of each component are as follows: 20 parts of polyether polyol N330, 20 parts of polyether polyol N303, 22 parts of hexamethylene diisocyanate, 22 parts of isophorone diisocyanate, 3 parts of silane coupling agent, 3 parts of stannous octoate, 10 parts of aluminum diethylphosphinate and carbon nanotubes (the weight ratio of aluminum diethylphosphinate to carbon nanotubes is 1:1), 10 parts of HCFC-141b, and 15 parts of dimethyl silicone oil; The preparation method of this embodiment is the same as that of Example 1.

[0049] Comparative Example 1 This comparative example provides a low-temperature flame-retardant polyurethane material for coal mines. The contents of the other components are the same as those in Example 1, except that the flame retardant is only 7 parts of carbon nanotubes and aluminum diethylphosphinate is not added.

[0050] The preparation method of this comparative example is the same as that of Example 1.

[0051] Comparative Example 2 This comparative example provides a low-temperature flame-retardant polyurethane material for coal mines. The contents of the other components are the same as those in Example 1, except that the flame retardant is only 7 parts of aluminum diethylphosphinate and carbon nanotubes are not added.

[0052] The preparation method of this comparative example is the same as that of Example 1.

[0053] Comparative Example 3 This comparative example provides a low-temperature flame-retardant polyurethane material for coal mines. The contents of the other components are the same as those in Example 1, except that no flame retardant is added.

[0054] The preparation method of this comparative example is the same as that of Example 1.

[0055] The cone calorimeter was used to test the flame retardancy of the low-temperature flame-retardant polyurethane materials for coal mines prepared in Examples 1-3 and Comparative Examples 1-3. The test results are shown in Table 1: Table 1 Figure 1 Schematic diagram of the comparison of the thermogravimetric curves of polyurethane (PU-CNTS-ADP) with two flame retardants added and polyurethane (PU-0) without flame retardant added in a nitrogen atmosphere.

[0056] Figure 2 TG-DTG curve of polyurethane with two flame retardants added in a nitrogen atmosphere.

[0057] Figure 3 Schematic diagram of the comparison of the thermogravimetric curves of polyurethane (PU-CNTS-ADP) with two flame retardants added and polyurethane (PU-0) without flame retardant added in an oxygen atmosphere.

[0058] The above describes and evaluates the efficacy of some embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into equivalent embodiments with equivalent changes, which does not affect the essence of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, all still fall within the scope protected by the technical solution of the present invention.

Claims

1. A low-temperature flame-retardant polyurethane material for coal mines, characterized in that: The raw material components are as follows: 30-40 parts of polyether polyol, 35-45 parts of isocyanate, 1-3 parts of modifier, 1-3 parts of catalyst, 5-10 parts of flame retardant, 5-10 parts of foaming agent and 10-15 parts of stabilizer.

2. The low-temperature flame-retardant polyurethane material for coal mines according to claim 1, characterized in that: The raw material components are as follows, calculated by weight: 34 parts of polyether polyol, 38 parts of isocyanate, 1 part of modifier, 1 part of catalyst, 7 parts of flame retardant, 6 parts of foaming agent and 13 parts of stabilizer.

3. The low-temperature flame-retardant polyurethane material for coal mines according to claim 1 or 2, characterized in that: The isocyanate includes one or both of hexamethylene diisocyanate and isophorone diisocyanate.

4. The low-temperature flame-retardant polyurethane material for coal mines according to claim 3, characterized in that: The isocyanate is a mixture of hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of the hexamethylene diisocyanate to isophorone diisocyanate is 1:

1.

5. The low-temperature flame-retardant polyurethane material for coal mines according to claim 1 or 2, characterized in that: The polyether polyol includes one or both of polyether polyol N330 and polyether polyol N303.

6. The low-temperature flame-retardant polyurethane material for coal mines according to claim 5, characterized in that: The polyether polyol is a mixture of polyether polyol N330 and polyether polyol N303; the weight ratio of the polyether polyol N330 to the polyether polyol N303 is 1:

1.

7. The low-temperature flame-retardant polyurethane material for coal mines according to claim 1 or 2, characterized in that: The catalyst includes one or two of a tertiary amine catalyst and a tin catalyst; And / or, the flame retardant includes one or two of a nano flame retardant and diethyl aluminum hypophosphite; And / or, the blowing agent is HCFC-141b; And / or, the stabilizer is dimethyl silicone oil.

8. A method for preparing a low-temperature flame-retardant polyurethane material for coal mines according to any one of claims 1 to 7, characterized in that: The following steps are involved: The polyether polyol, catalyst, stabilizer, modifier and flame retardant are sequentially added into a reaction vessel, and after being evenly mixed, a foaming agent is added, and after continuing to be evenly stirred, isocyanate is added, and after being evenly mixed, the low-temperature flame-retardant polyurethane material for coal mines is obtained.

9. The preparation method according to claim 8, characterized in that: The method further comprises the following steps: mixing hexamethylene diisocyanate and isophorone diisocyanate in a weight ratio of 1:1 and stirring evenly; And / or, polyether polyol N330 and polyether polyol N303 are mixed and stirred uniformly in a weight ratio of 1:

1.

10. Use of the low-temperature flame-retardant polyurethane material for coal mines as claimed in any one of claims 1 to 8 and the low-temperature flame-retardant polyurethane material for coal mines prepared by the preparation method of claim 8 or 9 as a plugging material in coal mines.

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