A high-temperature-stable and non-combustible thermal insulation board and a production method thereof

Abstract

The application discloses a kind of high low-temperature stability heat insulation non-combustible board and production method thereof, belong to polyurethane heat insulation non-combustible insulation material technical field.The heat insulation non-combustible board includes polyol 100 parts, catalyst 0.3~2.0 parts, foaming agent 18~25 parts, modified isocyanate 115~140 parts, flame retardant 475~550 parts.The heat insulation non-combustible board discards the mode of traditional additional low-temperature modifier, by the reaction of modified diisocyanate of special structure, can significantly reduce the low-temperature shrinkage and low-temperature brittleness of heat insulation non-combustible board, and improve the heat preservation performance of heat insulation non-combustible board at low temperature.

Description

TECHNICAL FIELD

[0001] The application relates to a kind of adiabatic non-combustible board with high low-temperature stability and a production method thereof, and belongs to the technical field of polyurethane adiabatic non-combustible thermal insulation material. BACKGROUND

[0002] Polyurethane adiabatic non-combustible thermal insulation material is a kind of high polymer material made of isocyanate and polyether polyol as main raw materials through foaming reaction. It has been widely used in building insulation, such as external wall insulation system, roof insulation layer, cold storage insulation, etc. due to its low thermal conductivity, high mechanical strength, good corrosion resistance, convenient construction and other characteristics.

[0003] In cold regions, the external wall insulation needs to be able to withstand lower temperatures without damage, and generally requires at least good mechanical strength and physical properties below -20℃, without cracking, peeling and other problems. However, when the temperature is lower than -20℃, the activity of polyurethane molecular chain segments decreases, the material toughness decreases, and brittle fracture is easy to occur. Therefore, the external wall insulation layer in the northern cold region may produce microcracks due to shrinkage stress under extremely low temperature, resulting in a decrease in insulation performance.

[0004] In addition, the thermal expansion coefficient of polyurethane is relatively high, which leads to a significant increase in shrinkage rate under low temperature environment compared to normal temperature environment, resulting in debonding, hollowing and other situations at the joint between the polyurethane insulation material and the base layer. In severe cases, the insulation material may fall off, reducing the safety of polyurethane insulation material. Moreover, the applicant found that the thermal conductivity of polyurethane insulation material also increases under extremely low temperature, resulting in a decrease in the insulation performance of polyurethane insulation material. Therefore, it is necessary to develop an insulation board with good dimensional stability under extremely low temperature.

[0005] In order to solve the technical problem, patent CN201710200282.3 discloses a kind of polyurethane low temperature resistant thermal insulation material, which adds low temperature resistant modifier such as butadiene rubber, ethylene-propylene rubber and ethylene-vinyl acetate copolymer to polyurethane material, which can improve the chemical stability of the insulation material under low temperature to a certain extent. However, the applicant found that the addition of the low temperature resistant modifier would cause a certain degree of phase separation with the polyurethane material, resulting in a large difference in performance of the insulation material in different areas, and its addition would affect the crosslinking and foaming process of the polyurethane insulation material, thereby destroying the rigid skeleton of the polyurethane, causing the collapse of the cell structure and the decrease of the closed cell rate, thus reducing the mechanical properties and insulation performance of the insulation material.

[0006] Therefore, there is an urgent need for a polyurethane adiabatic non-combustible board with high low-temperature stability, excellent mechanical strength and insulation performance. SUMMARY

[0007] In order to solve the above problems, the application provides a high-low-temperature-stable thermal insulation non-combustible board and a production method thereof, which discards the traditional method of adding a low-temperature-resistant modifier, and reduces the low-temperature shrinkage and low-temperature brittleness of the thermal insulation non-combustible board by designing a special structure of modified diisocyanate, so as to obtain a polyurethane thermal insulation non-combustible board with high low-temperature stability, excellent mechanical strength and thermal insulation performance.

[0008] According to an aspect of the application, a high-low-temperature-stable thermal insulation non-combustible board is provided, which comprises, by weight, 100 parts of a polyol, 0.3-2.0 parts of a catalyst, 18-25 parts of a foaming agent, 115-140 parts of a modified isocyanate, and 475-550 parts of a flame retardant.

[0009] The structural formula of the modified isocyanate is as follows:

[0010] wherein R is selected from one of , , and * represents a connection site.

[0011] The R group in the modified isocyanate is formed by the original diisocyanate with a benzene ring, so the structure between the two ends of R in the modified isocyanate is a modified structure, the benzene ring group contained in the modified isocyanate can reduce the low-temperature shrinkage of the polyurethane, enhance the rigid structure of the polyurethane, maintain the rigid skeleton of the polyurethane, reduce the collapse of the pore structure, and improve the closed cell rate, so as to obtain a thermal insulation non-combustible board with high low-temperature stability and high mechanical properties and thermal insulation performance.

[0012] The modified isocyanate contains two epoxy groups, which can increase the activity of the polyurethane molecular chain, reduce the glass transition temperature of the polyurethane, and thus improve the low-temperature brittleness of the thermal insulation non-combustible board and avoid the generation of micro-cracks. In addition, the epoxy group can also form a hydrogen bond with the amide bond, which can be broken and reorganized when subjected to shrinkage stress, effectively dissipating the shrinkage stress, and thus also improving the low-temperature toughness of the thermal insulation non-combustible board.

[0013] The modified isocyanate also contains two acylhydrazone bonds, which can also increase the number of hydrogen bonds in the polyurethane network, improve the low-temperature brittleness of the thermal insulation non-combustible board, and improve the impact resistance of the thermal insulation non-combustible board. In addition, the two acylhydrazone bonds are symmetrical structures, which can further reduce the inter-chain steric hindrance of the polyurethane and improve the movement ability of the polymer chain, so that the thermal insulation non-combustible board maintains high thermal insulation and high strength at low temperature.

[0014] Optionally, R is selected from .

[0015] The above selection can increase the number of benzene rings in the modified isocyanate, so that the mechanical strength of the thermal insulation non-combustible board reaches the best.

[0016] Optionally, the preparation step of the modified isocyanate is as follows:

[0017] S1: reacting p-acetamidobenzaldehyde and diepoxy glycerol ether according to a molar ratio of 1:(1.2-1.5) to obtain an intermediate A;

[0018] S2: reacting terephthalic acid dihydrazide and the intermediate A according to a molar ratio of 1:(2.1-2.4) to obtain an intermediate B;

[0019] S3: reacting the intermediate B with a benzene ring-containing diisocyanate to obtain the modified isocyanate.

[0020] In step S1, the amino group carried in the p-acetamidobenzaldehyde reacts with one of the epoxy groups in the diepoxy glycerol ether to generate the intermediate A. In step S2, the hydrazide groups of the terephthalic acid dihydrazide react with the aldehyde groups of the intermediate A to generate acylhydrazone bonds. The molar ratio is to improve the reaction rate of the terephthalic acid dihydrazide and improve the yield of the intermediate B. Since the terephthalic acid dihydrazide has a symmetrical structure and each end contains one hydrazide group, the intermediate B after reaction has hydroxyl groups at both ends, which can react with one of the isocyanate groups in the benzene ring-containing diisocyanate in step S3, thereby obtaining the modified isocyanate terminated by isocyanate at both ends.

[0021] Optionally, the benzene ring-containing diisocyanate is selected from one of m-xylylene diisocyanate, 2,4-toluene diisocyanate, and 4,4'-methylene bis(phenyl isocyanate).

[0022] Optionally, the reaction temperature of step S1 is 20-40°C, and the reaction time is 2-5h. In the reaction, 0.3wt% of a basic catalyst based on the diepoxy glycerol ether is also added.

[0023] Optionally, the basic catalyst is selected from NaOH or KOH.

[0024] Optionally, the reaction temperature of step S2 is 75-85°C, and the reaction time is 4-6h.

[0025] Optionally, the molar ratio of the intermediate B and the benzene ring-containing diisocyanate in step S3 is 1:(3-5).

[0026] Optionally, the reaction temperature of step S3 is 75-85°C, and the reaction time is 3-5h.

[0027] The reaction temperature, reaction time, and molar ratio of steps S1, S2, and S3 can improve the reaction efficiency of the reactants and the yield of the product.

[0028] Optionally, the flame retardant comprises expandable graphite, graphene oxide, inorganic flame retardant, N-based flame retardant, phosphorus-based flame retardant and halogen-based flame retardant in a weight ratio of (0.05-0.1) : (0.01-0.02) : (0.5-0.8) : (0.2-0.3) : (0.1-0.3) : (0.1-0.3).

[0029] Optionally, the inorganic flame retardant is selected from at least one of aluminum oxide, magnesium oxide, aluminum hydroxide, silicon oxide, aluminum silicate.

[0030] Optionally, the N-based flame retardant is selected from at least one of melamine and dicyandiamide.

[0031] Optionally, the phosphorus-based flame retardant is selected from at least one of dimethyl methylphosphonate, triphenyl phosphite, tributyl phosphate.

[0032] Optionally, the halogen-based flame retardant is selected from at least one of tris (2-chloropropyl) phosphate and trichloroethyl phosphate.

[0033] According to another aspect of the present application, a production method of the above-mentioned flame-retardant board with high low-temperature stability is provided, comprising the steps of:

[0034] (1) mixing a catalyst, a foaming agent, a modified isocyanate and a polyol to obtain a premix;

[0035] (2) mixing a flame retardant with the premix to obtain a mixture, and then foaming and curing the mixture to obtain a to-be-treated board;

[0036] (3) treating the to-be-treated board at 0-10°C for 8-10h, then raising the temperature to 20-30°C for 4-5h, and then raising the temperature to 50-60°C for 6-8h, and finally lowering the temperature to 20-30°C for 1-2h.

[0037] The present application uses step (3) to treat the formed board at low temperature, room temperature and medium temperature, respectively, which can adjust and relax the above-mentioned formed polyurethane molecular chain to a certain extent, reduce the internal stress, and thus reduce the low-temperature shrinkage in use.

[0038] Optionally, the temperature raising speed from 0-10°C to 20-30°C is 0.5-1.0°C / min, the temperature raising speed from 20-30°C to 50-60°C is 0.5-1.5°C / min, and the temperature lowering speed from 50-60°C to 20-30°C is 0.5-1.0°C / min.

[0039] The above heating rate and cooling rate are relatively slow, which can maximize the adjustment of the molecular chain of the polyurethane, further reduce the internal stress, and improve the uniformity of various properties of the thermal insulation non-combustible board. The maximum limit of the heating rate from 20-30℃ to 50-60℃ is higher than the rest, because in the temperature process from room temperature to medium temperature 50-60℃, the adjustment speed of the molecular chain is also relatively fast, and a higher heating rate can be used to reduce the processing time and save production cost. The cooling rate from 50-60℃ to 20-30℃ is 0.5-1.0℃ / min, in order to preliminarily fix the adjusted molecular chain and avoid introducing internal stress again.

[0040] The beneficial effects of the present application include but are not limited to:

[0041] 1. The thermal insulation non-combustible board with high low-temperature stability according to the present application, which uses modified isocyanate to form a polyurethane cross-linked network, can effectively reduce the low-temperature shrinkage of the thermal insulation non-combustible board, maintain good mechanical properties and thermal insulation properties at extremely low temperatures, and avoid the debonding or hollowing of the thermal insulation non-combustible board and the base material, thereby improving the service life and use safety.

[0042] 2. The thermal insulation non-combustible board with high low-temperature stability according to the present application, which uses modified diisocyanate, can enhance the toughness of polyurethane at low temperatures, avoid brittle fracture of the non-combustible board, reduce the shrinkage stress at low temperatures, thereby avoiding the generation of low-temperature micro-cracks, and maintaining the same stability at low temperatures as at room temperature.

[0043] 3. The thermal insulation non-combustible board with high low-temperature stability according to the present application, which uses modified diisocyanate, can improve the mechanical strength and bubble structure stability of the thermal insulation non-combustible board, avoid structure collapse, and improve the closed cell rate, thereby doubling the mechanical properties and thermal insulation properties of the thermal insulation non-combustible board.

[0044] 4. The thermal insulation non-combustible board with high low-temperature stability according to the present application, which can double the mechanical strength and thermal insulation properties on the basis of improving low-temperature stability, to meet the use requirements at extremely low temperatures, and is suitable for industrialization and popularization. BRIEF DESCRIPTION OF DRAWINGS

[0045] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0046] Figure 1 The reaction equation diagram related to Example 1 of the present application.

[0047] Figure 2 The reaction equation diagram related to Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0048] The application will be described in detail below with reference to examples, but the application is not limited to these examples.

[0049] Unless otherwise specified, the raw materials in the examples and comparative examples of the present application are purchased through commercial channels. The polyol used in the following examples and comparative examples is a polyether tetrol (hydroxyl value of 400 mg KOH / g) and a polyacrylate polyol (hydroxyl value of 650 mg KOH / g) with a weight ratio of 3:1, the catalyst is dibutyl tin dilaurate, and the foaming agent is water and pentane with a weight ratio of 1:1. The NaOH catalyst used in the following examples is an alkaline catalyst, and the amount added refers to the weight of anhydrous NaOH. In actual addition, NaOH can be dissolved in a solvent to prepare a solution with a concentration of 20-70 wt% before addition to improve catalytic efficiency. In addition, the solvent used in the following examples and comparative examples is not specifically limited as long as it can dissolve the monomers and does not inhibit the normal progress of the reaction.

[0050] Unless otherwise specified, the method used in the examples and comparative examples of the present application is a conventional method in the prior art.

[0051] Example 1

[0052] This example relates to a high-temperature-stable thermal insulation non-combustible board and a production method thereof. The components of the thermal insulation non-combustible board include, by weight fraction, 100 parts of a polyol, 0.3 parts of a catalyst, 18 parts of a foaming agent, 115 parts of a modified isocyanate, and 475 parts of a flame retardant selected from expandable graphite, graphene oxide, aluminum oxide, melamine, dimethyl methylphosphonate, and tris(2-chloropropyl) phosphate) with a weight ratio of 0.05:0.01:0.5:0.3:0.3:0.1.

[0053] The structural formula of the modified isocyanate is as follows:

[0054] wherein R is selected from , and * represents a connection site.

[0055] Reference Figure 1 The preparation steps of the modified isocyanate are as follows:

[0056] S1: Dissolve p-acetamidobenzaldehyde and diepoxyglyceryl ether in a solvent, respectively, mix them in a reaction kettle according to a molar ratio of 1:1.5, add NaOH as a catalyst accounting for 0.3 wt% of diepoxyglyceryl ether, react at 40°C for 2 h, and spin to obtain intermediate A;

[0057] S2: Dissolve p-terephthalic acid dihydrazide and intermediate A in a solvent, respectively, add them to a reaction kettle according to a molar ratio of 1:2.1, react at 75°C for 6 h, and obtain intermediate B after vacuum filtration and washing,Figure 1 Two molecules of H2O are also formed in the formation of intermediate B, which is not shown in the figure;

[0058] S3: intermediate B and m-xylylene isocyanate in a molar ratio of 1:3 are mixed in a reaction kettle, and then reacted at 85℃ for 3h, and rotary evaporation to obtain the modified isocyanate.

[0059] The production method of the heat-insulating non-combustible board comprises the following steps:

[0060] (1) mixing the catalyst, the foaming agent, the modified isocyanate and the polyol to obtain a premix;

[0061] (2) mixing the flame retardant with the premix to obtain a mixture, and then foaming the mixture at 50℃ and curing the mixture at 40℃ for 2.0h to obtain a to-be-treated board;

[0062] (3) treating the to-be-treated board at 0℃ for 10h, then heating to 20℃ at a heating rate of 1.0℃ / min for 5h, then heating to 50℃ at a heating rate of 0.5℃ / min for 8h, and finally cooling to 20℃ at a cooling rate of 0.5℃ / min for 2h.

[0063] Example 2

[0064] The present embodiment relates to a heat-insulating non-combustible board with high low-temperature stability and a production method thereof. The components of the heat-insulating non-combustible board include, by weight fraction, 100 parts of polyol, 2.0 parts of catalyst, 25 parts of foaming agent, 140 parts of modified isocyanate, and 550 parts of flame retardant selected from expandable graphite, graphene oxide, magnesium oxide, dicyandiamide, triphenyl phosphite and trichloroethyl phosphate in a weight ratio of 0.1:0.02:0.8:0.2:0.1:0.3.

[0065] The structural formula of the modified isocyanate is as follows:

[0066] wherein R is selected from , and * represents a connection site.

[0067] The preparation steps of the modified isocyanate are as follows:

[0068] S1: p-acetamidobenzaldehyde and diglycidyl ether are dissolved in a solvent respectively, mixed in a reaction kettle in a molar ratio of 1:1.2, 0.3wt% of NaOH based on the weight of diglycidyl ether is added as a catalyst, and reacted at 20℃ for 5h, and rotary evaporation to obtain intermediate A;

[0069] S2: Dissolve terephthalic dihydrazide and intermediate A in solvents respectively, add to the reaction kettle according to the molar ratio of 1:2.4, react at 85℃ for 4h, and obtain intermediate B after vacuum filtration and washing;

[0070] S3: Mix intermediate B and 2,4-toluene diisocyanate in a molar ratio of 1:4 in a reaction kettle, then react at 75℃ for 5h, and obtain the modified isocyanate by rotary evaporation.

[0071] The production method of the heat-insulating non-combustible board comprises the following steps:

[0072] (1) Mix the catalyst, foaming agent, modified isocyanate and polyol to obtain a premix;

[0073] (2) Mix the flame retardant with the premix to obtain a mixture, then foam the mixture at 50℃ and cure at 40℃ for 2.0h to obtain a to-be-treated board;

[0074] (3) Treat the to-be-treated board at 10℃ for 8h, then heat it to 30℃ at a heating rate of 0.5℃ / min for 4h, heat it to 60℃ at a heating rate of 1.5℃ / min for 8h, and finally cool it to 30℃ at a cooling rate of 1.0℃ / min for 1h.

[0075] Example 3

[0076] This embodiment relates to a heat-insulating non-combustible board with high low-temperature stability and a production method thereof. The components of the heat-insulating non-combustible board comprise, by weight fraction, 100 parts of polyol, 1.5 parts of catalyst, 22 parts of foaming agent, 136 parts of modified isocyanate and 510 parts of flame retardant, wherein the flame retardant is selected from expandable graphite, graphene oxide, aluminum hydroxide, melamine, tributyl phosphate and tris(2-chloropropyl) phosphate) in a weight ratio of 0.1:0.02:0.7:0.2:0.2:0.2.

[0077] The structural formula of the modified isocyanate is as follows:

[0078] wherein R is selected from , and * represents a connection site.

[0079] The preparation steps of the modified isocyanate are as follows:

[0080] S1: Dissolve and p-acetamidobenzaldehyde and diglycidyl ether in solvents respectively, mix them in a reaction kettle according to the molar ratio of 1:1.4, add 0.3wt% of NaOH based on the weight of diglycidyl ether as a catalyst, react at 30℃ for 4h, and obtain intermediate A by rotary evaporation.

[0081] S2: Dissolve terephthalic dihydrazide and intermediate A in solvent respectively, add to the reaction kettle according to the molar ratio of 1:2.2, react at 80℃ for 5h, and then obtain intermediate B after filtration and washing under reduced pressure;

[0082] S3: Mix intermediate B and 4,4'-methylene bis(phenyl isocyanate) in the reaction kettle according to the molar ratio of 1:5, then react at 85℃ for 4h, and then obtain the modified isocyanate by rotary evaporation.

[0083] The production method of the heat-insulating non-combustible board comprises the following steps:

[0084] (1) Mix the catalyst, foaming agent, modified isocyanate and polyol to obtain a premix;

[0085] (2) Mix the flame retardant with the premix to obtain a mixture, then foam the mixture at 50℃, and then obtain a to-be-treated board after curing the mixture at 40℃ for 2.0h;

[0086] (3) Place the to-be-treated board at 10℃ for 10h, then heat to 25℃ at a heating rate of 1.0℃ / min for 5h, then heat to 50℃ at a heating rate of 1.5℃ / min for 8h, and finally cool to 25℃ at a cooling rate of 1.0℃ / min for 2h.

[0087] Example 4

[0088] The difference between this example and Example 3 is that m-xylylene isocyanate is used to replace 4,4'-methylene bis(phenyl isocyanate).

[0089] Example 5

[0090] The difference between this example and Example 3 is that 2,4-toluene diisocyanate is used to replace 4,4'-methylene bis(phenyl isocyanate).

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 3 is that (methoxymethyl)oxirane is used to replace diglycidyl ether in step S1, and the reaction equation of the modified isocyanate prepared is as shown in Figure 2 Figure 2 Two molecules of H2O are also formed in the formation of intermediate B, which is not shown in the figure.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 3 is that 4,4'-methylene bis(phenyl isocyanate) is directly used to replace the modified isocyanate, that is, the modified isocyanate is not prepared in this comparative example, and 4,4'-methylene bis(phenyl isocyanate) is directly used to prepare the heat-insulating non-combustible board. ​

[0095] Test Example 1

[0096] The thermal conductivity (15 cm thickness), flame retardant and mechanical properties of the thermal insulation non-combustible board prepared in the above examples and comparative examples were tested, and the results are shown in Table 1 below, wherein the flame retardant performance is carried out according to GB8624-2012 standard.

[0097] Table 1

[0098]

[0099] Test Example 2

[0100] The thermal insulation non-combustible board prepared in the above examples and comparative examples was placed at -50°C for 10 days, and the thermal conductivity reduction rate, compression strength reduction rate, and dimensional shrinkage rate were tested, and whether micro cracks appeared in the treated board was observed, and the test results are shown in Table 2, and the calculation formula of each parameter in Table 2 is as follows:

[0101] Thermal conductivity increase rate = [(thermal conductivity after low temperature treatment-initial thermal conductivity) / initial thermal conductivity]*100%;

[0102] Compression strength reduction rate = [(initial compression strength-compression strength after low temperature treatment) / initial compression strength]*100%;

[0103] Lengthwise dimensional shrinkage rate = [(initial length-length after low temperature treatment) / initial length]*100%;

[0104] Widthwise dimensional shrinkage rate = [(initial width-width after low temperature treatment) / initial width]*100%.

[0105] Table 2

[0106]

[0107] According to the above test results, the modified isocyanate added in the thermal insulation non-combustible board of the present application can effectively reduce the thermal insulation performance, mechanical properties and dimensional shrinkage rate of the material at low temperature, reduce the generation of micro cracks at low temperature, and prolong the use performance of the thermal insulation non-combustible board at low temperature.

[0108] According to the comparison of Examples 3-5, the modified isocyanate prepared by using isocyanate with two benzene rings in the thermal insulation non-combustible board has the best thermal insulation performance, mechanical properties, and the smallest dimensional shrinkage rate.

[0109] According to the comparison of Example 3 and Comparative Example 1, the presence of excess epoxy groups in the modified isocyanate can increase the number of hydrogen bonds in the thermal insulation non-combustible board, thereby improving the low temperature toughness of the board, increasing the compression strength at low temperature, and avoiding the generation of micro cracks.

[0110] According to the comparison between Example 3 and Comparative Example 2, the addition of the modified isocyanate can reduce the thermal conductivity reduction rate from 3.56% to 0.77%, and the reduction of Example 3 compared with Comparative Example 2 can reach 78.4%, which proves that the addition of the modified isocyanate can effectively solve the problems of high brittleness, poor thermal insulation, and poor mechanical strength of the polyurethane non-combustible insulation board at low temperature.

[0111] The above merely describes the embodiments of the present application, and the protection scope of the present application is not limited by these specific embodiments, but determined by the claims of the present application. Various modifications and changes can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the technical concept and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A heat-insulating, non-combustible board with high low-temperature stability, characterized in that, The polyol is 100 parts, the catalyst is 0.3-2.0 parts, the foaming agent is 18-25 parts, the modified isocyanate is 115-140 parts, and the flame retardant is 475-550 parts by weight; The structural formula of the modified isocyanate is as follows: wherein R is selected from , , one of the following, * indicates the point of attachment.

2. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 1, characterized by R is selected from .

3. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 1, characterized by The preparation steps of the modified isocyanate are as follows: S1: reacting p-acetamidobenzaldehyde and diepoxy glycerol ether according to a molar ratio of 1:(1.2-1.5) to obtain an intermediate A; S2: reacting terephthalic dihydrazide and the intermediate A according to a molar ratio of 1:(2.1-2.4) to obtain an intermediate B; S3: reacting the intermediate B with a benzene ring-containing diisocyanate to obtain the modified isocyanate.

4. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 3, characterized by The benzene ring-containing diisocyanate is selected from one of m-xylylene diisocyanate, 2,4-toluene diisocyanate, and 4,4'-methylenebis(phenyl isocyanate).

5. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 3, characterized by The reaction temperature of step S1 is 20-40℃, and the reaction time is 2-5h. In the reaction, 0.3wt% of a basic catalyst based on diepoxy glycerol ether is also added.

6. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 3, characterized by The reaction temperature of step S2 is 75-85℃, and the reaction time is 4-6h.

7. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 3, characterized by In step S3, the molar ratio of the intermediate B to the benzene ring-containing diisocyanate is 1:(3-5).

8. The thermal-insulating non-combustible panel with high low-temperature stability according to claim 3, characterized by The reaction temperature of step S3 is 75-85℃, and the reaction time is 3-5h.

9. The method for producing an incombustible thermal board having high low-temperature stability according to any one of claims 1 to 8, characterized by, The steps include: (1) mixing the catalyst, the foaming agent, the modified isocyanate, and the polyol to obtain a premix; (2) mixing the flame retardant with the premix to obtain a mixture, and then foaming and curing the mixture to obtain a to-be-treated plate; (3) placing the to-be-treated plate at 0-10℃ for 8-10h, then heating to 20-30℃ for 4-5h, and then heating to 50-60℃ for 6-8h, and finally cooling to 20-30℃ for 1-2h.

10. The production method according to claim 9, characterized by, The heating rate from 0-10℃ to 20-30℃ is 0.5-1.0℃ / min, the heating rate from 20-30℃ to 50-60℃ is 0.5-1.5℃ / min, and the cooling rate from 50-60℃ to 20-30℃ is 0.5-1.0℃ / min.

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