High-flame-retardant polyurethane thermal insulation material and preparation method thereof

Abstract

The invention belongs to the technical field of polyurethane thermal insulation materials, and particularly relates to a high-flame-retardant polyurethane thermal insulation material and a preparation method thereof. The polyurethane thermal insulation material is prepared from the following raw materials in parts by weight: 20-25 parts of polyisocyanate; 15 to 20 parts of polyol; 2-4 parts of a foaming agent; 0.6 to 0.8 part of a foam stabilizer; 0.3 to 0.5 part of a catalyst; 2-3 parts of a modified additive; through the synergistic effect of polyphosphate-diol containing a polyphosphate group and a nitrogen element and the modified additive containing a polyphosphate group, a nitrogen element and a silicon element, the multiple flame-retardant effect is achieved, and the polyurethane thermal insulation material with high flame-retardant property is obtained; the prepared polyurethane thermal insulation material also has good dimensional stability, thermal insulation performance and strength, and can better meet market requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane thermal insulation materials, and particularly relates to a highly flame-retardant polyurethane thermal insulation material and a preparation method thereof. Background Art

[0002] Commonly used organic thermal insulation materials mainly include polyurethane materials, polystyrene materials and phenolic materials. Among them, polyurethane materials are polymers made of polyisocyanates, polyols, polyamines, water and other raw materials. They have the advantages of porosity, low density, chemical corrosion resistance, good thermal insulation and good thermal insulation performance. They are widely used in many fields such as construction, cold chain facilities, furniture, etc.; but traditional polyurethane materials themselves also have some defects, especially poor fire resistance, easy aging and easy burning; with the continuous enhancement of people's safety awareness, higher and higher requirements are placed on the flame retardant properties of polyurethane materials, and improving their flame retardant properties has also become a research focus. At present, polyurethane materials with flame retardant properties are mainly obtained by flame retardant modification of the raw materials for synthesizing polyurethane or adding flame retardants during the preparation of polyurethane materials.

[0003] Chinese patent CN110845697B discloses a polyurethane flame retardant foam material, which is prepared from raw materials such as polyether polyol, melamine polyether, phthalic anhydride polyester polyol, polyether tetraol, foam stabilizer, foaming agent HFC-245fa, composite flame retardant, water, chain extender, etc. in specific weight proportions. The prepared material has the characteristics of rapid molding, good dimensional stability, good air tightness, low thermal conductivity, high compressive strength, etc., wherein the polyether polyol is prepared by mixing polyether diol, polyether triol and polyether tetraol, and the composite flame retardant used is TCPP and TEP. By adding the composite flame retardant, the difficulty of the polyurethane material being flammable is solved and the fire hazard is reduced. The oxygen index of the polyurethane flame retardant foam material is 30.4-30.6%.

[0004] Chinese patent CN113929864B discloses a flame retardant and heat-insulating polyurethane material, which is made of the following raw materials in parts by weight: 10-20 parts of a polyol composition; 10-20 parts of PM-200; 0.03-0.05 parts of a catalyst; 2-5 parts of a foaming agent; and 0.2-0.5 parts of a foaming agent. The polyol composition is composed of a phosphorus-nitrogen polyol, a silicon-boron flame retardant, and a polyester polyol. The polyurethane material is made by reacting a polyol composition containing phosphorus, nitrogen, silicon, boron, and fluorine with multiple methyl polyphenyl isocyanates, so that the polyurethane material has excellent flame retardant properties and excellent mechanical properties, and its oxygen index reaches up to 33.4%.

[0005] Chinese patent CN116655877A discloses a wall insulation composite material and its production process, which uses polyether polyol, diisocyanate, branched flame retardant cross-linking agent, catalyst, physical foaming agent, chemical foaming agent and inorganic filler as raw materials, and obtains a thermal insulation composite material with good flame retardant performance through foaming, aging and curing processes. The branched flame retardant cross-linking agent contains rich organic silicon and phenyl phosphate structures, which serve as phosphorus-silicon synergistic flame retardant to improve the flame retardant performance of the material, and its limiting oxygen index reaches 33.0%.

[0006] Although the above patents all adopt different methods to modify the polyurethane materials and improve the flame retardant properties of the polyurethane materials, there is still room for improvement in the oxygen index of the polyurethane materials and the requirements for high flame retardant properties cannot be met. Summary of the invention

[0007] The purpose of the present invention is to provide a highly flame-retardant polyurethane thermal insulation material and a preparation method thereof in view of the deficiencies of the prior art, so as to obtain a polyurethane thermal insulation material with high flame retardancy.

[0008] The technical solution of the present invention is as follows:

[0009] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 20-25 parts of polyisocyanate; 15-20 parts of polyol; 2-4 parts of foaming agent; 0.6-0.8 parts of foam stabilizer; 0.3-0.5 parts of catalyst; 2-3 parts of modified additive;

[0010] Furthermore, the polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 1-2:1.

[0011] Furthermore, the polyisocyanate is any one of diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate, or a mixture of several of them.

[0012] Furthermore, the foaming agent consists of a physical foaming agent and a chemical foaming agent in a mass ratio of 2-3:1.

[0013] Furthermore, the physical foaming agent is any one of dichloromethane, n-hexane, and petroleum ether, or a mixture of several of them.

[0014] Furthermore, the chemical foaming agent is any one of water, azodicarbonamide, and isopropyl azodicarboxylate, or a mixture of several of them.

[0015] Furthermore, the foam stabilizer is dimethyl silicone oil or vinyl silicone oil.

[0016] Furthermore, the catalyst is any one of pentamethyldiethylenetriamine, dimethylcyclohexylamine, pentamethylcyclohexylamine, or a mixture of several thereof.

[0017] The present invention also provides a method for preparing a highly flame-retardant polyurethane thermal insulation material, comprising the following steps: uniformly mixing polyol, foaming agent, foam stabilizer, catalyst, and modifying additive according to a mass ratio, adding polyisocyanate, stirring uniformly, pouring into a mold, and obtaining a highly flame-retardant polyurethane thermal insulation material through foaming, aging, and curing.

[0018] Furthermore, the foaming conditions are: foaming at 25-30° C. for 20-30 minutes; the aging conditions are: aging at room temperature for 1-2 hours; and the curing conditions are: curing at 70-80° C. for 2-3 hours.

[0019] In the technical scheme of the present invention, the preparation method of the modified additive is: add 80-90wt% ethanol solution and modified silane into a reaction container, perform ultrasound for 0.5-1h, add diatomaceous earth and calcium carbonate, continue ultrasound for 2-3h, filter, and dry the filter residue to obtain the modified additive; the mass ratio of the diatomaceous earth, calcium carbonate, modified silane, and 80-90wt% ethanol solution is 1:0.8-1:0.3-0.5:25-30.

[0020] In the technical scheme of the present invention, the preparation method of the polyphosphate-diol is as follows: anhydrous tetrahydrofuran, chloro-polyphosphate and N,N-diisopropylethylamine are added to a reaction container, nitrogen protection is provided, stirring is performed uniformly, a tetrahydrofuran solution containing 2-amino-1,3-propanediol is added dropwise, after the addition is completed, the temperature is raised to 50-60° C., and the reaction is performed for 4-5 hours to obtain a polyphosphate-diol having the structural formula:

[0021] The molar ratio of the 2-amino-1,3-propanediol, the chloro-polyphosphate and the N,N-diisopropylethylamine is 1:1-1.1:1.3-1.5.

[0022] In the technical solution of the present invention, the preparation method of the modified silane is:

[0023] S1. Add N,N-dimethylformamide, 4-chlorophenyl dichlorophosphate and triethylamine to the reaction vessel, protect with nitrogen, stir evenly, cool to -5-0°C, add dropwise N,N-dimethylformamide solution containing dimethyl 2-hydroxyethylphosphonate, react for 6-8h, and obtain chloro-polyphosphate, the structural formula of which is:

[0024] The molar ratio of the 4-chlorophenyl dichlorophosphate, 2-hydroxyethyl dimethyl phosphonate and triethylamine is 1:2-2.1:2.3-2.5;

[0025] S2. Add anhydrous tetrahydrofuran, chloro-polyphosphate and triethylamine to the reaction vessel, protect with nitrogen, stir evenly, dropwise add tetrahydrofuran solution containing 3-aminopropyltriethoxysilane, after dropwise addition, heat to 45-50°C, react for 4-6h, and obtain modified silane with the structural formula:

[0026] The molar ratio of the 3-aminopropyltriethoxysilane, chloro-polyphosphate and triethylamine is 1:1-1.1:0.3-0.5.

[0027] The present invention has the following beneficial effects:

[0028] In order to obtain a polyurethane thermal insulation material with high flame retardancy, the present invention modifies the raw materials for synthesizing polyurethane. On the one hand, 2-amino-1,3-propanediol is reacted with chloro-polyphosphate to obtain a flame retardant polyphosphate-diol. The obtained polyphosphate-diol structure contains a flame retardant polyphosphate group and a nitrogen element. The polyphosphate-diol is used in the synthesis of polyurethane to greatly improve the flame retardancy of the polyurethane thermal insulation material. On the other hand, the present invention uses a modified silane containing a polyphosphate group to modify diatomaceous earth and calcium carbonate. The modified diatomaceous earth and calcium carbonate both contain a flame retardant polyphosphate group, a nitrogen element and a silicon element, which can not only synergize with the polyphosphate-diol to jointly improve the flame retardancy of the polyurethane thermal insulation material, but also the modified diatomaceous earth and calcium carbonate have better compatibility with other organic raw materials, can be better dispersed in the polyurethane system, form a thermal insulation material with a more uniform structure and stability, and help to improve the strength and flame retardancy of the thermal insulation material.

[0029] The present invention achieves multiple flame retardant effects through the synergistic effect of polyphosphate-diol containing polyphosphate groups and nitrogen elements and modified additives containing polyphosphate groups, nitrogen elements and silicon elements, thereby obtaining a polyurethane thermal insulation material with high flame retardant performance. The prepared polyurethane thermal insulation material also has good dimensional stability, thermal insulation performance and strength, and can better meet market demand. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solution of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] In the technical scheme of the present invention, all chemical reagents in the following embodiments and comparative examples are commonly available on the market, wherein the polyether polyol is polyether polyol 4110; diphenylmethane diisocyanate CAS No. 101-68-8; hexamethylene diisocyanate CAS No. 822-06-0; toluene diisocyanate CAS No. 26471-62-5; azodicarbonamide CAS No. 123-77-3; isopropyl azodicarboxylate CAS No. 2446-83-5; pentamethyldiethylenetriamine CAS No. 3030-47-5; dimethylcyclohexylamine CAS No. 98-94-2; pentamethylcyclohexylamine CAS No. 219810-59-0; calcium carbonate CAS No. 471 -34-1; 4-chlorophenyl dichlorophosphate CAS No. 772-79-2; 2-hydroxyethylphosphonic acid dimethyl ester CAS No. 54731-72-5; triethylamine CAS No. 121-44-8; 3-aminopropyltriethoxysilane CAS No. 919-30-2; N,N-diisopropylethylamine CAS No. 7087-68-5; 2-amino-1,3-propanediol CAS No. 534-03-2; N,N-dimethylformamide CAS No. 68-12-2; tetrahydrofuran CAS No. 109-99-9; dichloromethane CAS No. 75-09-2; n-hexane CAS No. 110-54-3; petroleum ether CAS No. 8032-32-4.

[0032] In the technical solution of the present invention, the preparation method of modified silane is:

[0033]

[0034] S1. Add 400 mL of N,N-dimethylformamide, 25.0 g of 4-chlorophenyl dichlorophosphate and 25.8 g of triethylamine to a reaction vessel, protect with nitrogen, stir evenly, cool to -5°C, dropwise add 100 mL of N,N-dimethylformamide solution containing 31.4 g of dimethyl 2-hydroxyethylphosphonate, react for 7 h, filter after the reaction is completed, add water and dichloromethane to the filtrate for extraction, and concentrate the organic phase under reduced pressure to obtain 41.6 g of chloro-polyphosphate, the molar ratio of 4-chlorophenyl dichlorophosphate, dimethyl 2-hydroxyethylphosphonate and triethylamine is 1:2:2.5; chloro-polyphosphate: ESI (m / z): 481.7 [M+H] + , 1 H-NMR (600MHz, DMSO-d6, δppm): 7.40 (d, J=8.6Hz, 2H), 7.22 (d, J=8.6Hz, 2H), 4.27-4.30 (m, 4H), 3.65 (s, 12H), 2.14-2.17 (m, 4H).

[0035] S2. Add 220 mL of anhydrous tetrahydrofuran, 20.0 g of chloro-polyphosphate and 1.3 g of triethylamine to the reaction container, protect with nitrogen, stir evenly, dropwise add 80 mL of tetrahydrofuran solution containing 9.2 g of 3-aminopropyltriethoxysilane, after dropwise addition, heat to 45°C, react for 6 h, after the reaction is completed, naturally cool to room temperature, remove tetrahydrofuran and triethylamine, and obtain 23.5 g of modified silane; the molar ratio of 3-aminopropyltriethoxysilane, chloro-polyphosphate and triethylamine is 1:1:0.3; modified silane: ESI (m / z): 666.6 [M+H] + , 1 H-NMR (600MHz, DMSO-d6, δppm): 7.18 (d, J=8.5Hz, 2H), 6.78 (d, J=8.5Hz, 2H), 6.43 (s, 1H), 4.27-4.30 (m, 4H), 3.83-3.86 (m, 6H), 3.65 (s, 12H), 3.35-3.37 (m, 2H), 1.48-1.50 (m, 2H), 2.14-2.17 (m, 4H), 1.21 (t, J=7.2Hz, 9H), 0.55-0.57 (m, 2H).

[0036] In the technical solution of the present invention, the preparation method of polyphosphate-diol is:

[0037]

[0038] Add 260 mL of anhydrous tetrahydrofuran, 20.0 g of chloro-polyphosphate and 8.1 g of N,N-diisopropylethylamine to the reaction vessel, protect with nitrogen, stir evenly, add 40 mL of tetrahydrofuran solution containing 3.8 g of 2-amino-1,3-propanediol dropwise, raise the temperature to 60°C, react for 5 h, and after the reaction is completed, naturally cool to room temperature, remove tetrahydrofuran, extract with water and dichloromethane, and concentrate the organic phase under reduced pressure to obtain 23.5 g of polyphosphate-diol; the molar ratio of 2-amino-1,3-propanediol, chloro-polyphosphate, and N,N-diisopropylethylamine is 1:1:1.5; polyphosphate-diol: ESI (m / z): 536.4 [M+H] + , 1 H-NMR (600MHz, DMSO-d6, δppm): 7.34 (s, 1H), 7.18 (d, J = 8.5Hz, 2H), 6.78 (d, J = 8.5Hz, 2H), 4.49 (s, 2H), 4.27-4.30 (m, 4H), 3.65-3.70 (m, 16H), 2.63-2.66 (m, 1H), 2.14-2.17 (m, 4H).

[0039] Example 1

[0040] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 25 parts of polyisocyanate; 20 parts of polyol; 3 parts of foaming agent; 0.8 parts of foam stabilizer; 0.4 parts of catalyst; 3 parts of modified additive;

[0041] The polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 2:1; the polyisocyanate is hexamethylene diisocyanate; the foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2:1; the physical foaming agent is n-hexane; the chemical foaming agent is water; the foam stabilizer is dimethyl silicone oil; and the catalyst is pentamethyldiethylenetriamine.

[0042] The preparation method of the modified additive is as follows: adding 90wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 1h, adding diatomaceous earth and calcium carbonate, continuing ultrasonicating for 3h, filtering, and drying the filter residue to obtain the modified additive; the mass ratio of diatomaceous earth, calcium carbonate, modified silane, and 90wt% ethanol solution is 1:1:0.5:30.

[0043] A preparation method of a highly flame-retardant polyurethane thermal insulation material comprises the following steps: uniformly mixing polyol, a foaming agent, a foam stabilizer, a catalyst and a modified additive according to a mass ratio, adding polyisocyanate, stirring uniformly, pouring into a mold, foaming, aging and curing to obtain a highly flame-retardant polyurethane thermal insulation material; the foaming conditions are: foaming at 30°C for 20 minutes; the aging conditions are: aging at room temperature for 2 hours; and the curing conditions are: curing at 70°C for 3 hours.

[0044] Example 2

[0045] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 23 parts of polyisocyanate; 15 parts of polyol; 4 parts of foaming agent; 0.6 parts of foam stabilizer; 0.5 parts of catalyst; 2 parts of modified additive;

[0046] The polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 1.5:1; the polyisocyanate is diphenylmethane diisocyanate; the blowing agent is composed of a physical blowing agent and a chemical blowing agent in a mass ratio of 3:1; the physical blowing agent is dichloromethane; the chemical blowing agent is isopropyl azodicarboxylate; the foam stabilizer is vinyl silicone oil; and the catalyst is dimethylcyclohexylamine.

[0047] The preparation method of the modified additive is as follows: adding 80wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 0.5h, adding diatomaceous earth and calcium carbonate, continuing ultrasonicating for 2.5h, filtering, and drying the filter residue to obtain the modified additive; the mass ratio of diatomaceous earth, calcium carbonate, modified silane, and 80wt% ethanol solution is 1:0.9:0.3:25.

[0048] A preparation method of a highly flame-retardant polyurethane thermal insulation material comprises the following steps: uniformly mixing polyol, a foaming agent, a foam stabilizer, a catalyst and a modified additive according to a mass ratio, adding polyisocyanate, stirring uniformly, pouring into a mold, foaming, aging and curing to obtain a highly flame-retardant polyurethane thermal insulation material; the foaming conditions are: foaming at 25°C for 30 minutes; the aging conditions are: aging at room temperature for 1 hour; and the curing conditions are: curing at 80°C for 2 hours.

[0049] Example 3

[0050] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 20 parts of polyisocyanate; 17 parts of polyol; 2 parts of foaming agent; 0.7 parts of foam stabilizer; 0.3 parts of catalyst; 2.5 parts of modified additive;

[0051] The polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 1:1; the polyisocyanate is toluene diisocyanate; the foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2.5:1; the physical foaming agent is petroleum ether; the chemical foaming agent is azodicarbonamide; the foam stabilizer is dimethyl silicone oil; and the catalyst is pentamethylcyclohexylamine.

[0052] The preparation method of the modified additive is as follows: adding 85wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 0.6h, adding diatomaceous earth and calcium carbonate, continuing ultrasonicating for 2h, filtering, and drying the filter residue to obtain the modified additive; the mass ratio of diatomaceous earth, calcium carbonate, modified silane, and 85wt% ethanol solution is 1:0.8:0.4:28.

[0053] A preparation method of a highly flame-retardant polyurethane thermal insulation material comprises the following steps: uniformly mixing polyol, a foaming agent, a foam stabilizer, a catalyst and a modified additive according to a mass ratio, adding polyisocyanate, stirring uniformly, pouring into a mold, foaming, aging and curing to obtain a highly flame-retardant polyurethane thermal insulation material; the foaming conditions are: foaming at 30°C for 25 minutes; the aging conditions are: aging at room temperature for 1.5 hours; and the curing conditions are: curing at 75°C for 2.5 hours.

[0054] Example 4

[0055] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 25 parts of polyisocyanate; 15 parts of polyol; 3 parts of foaming agent; 0.7 parts of foam stabilizer; 0.4 parts of catalyst; 3 parts of modified additive;

[0056] The polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 2:1; the polyisocyanate is hexamethylene diisocyanate; the blowing agent is composed of a physical blowing agent and a chemical blowing agent in a mass ratio of 3:1; the physical blowing agent is dichloromethane; the chemical blowing agent is water; the foam stabilizer is vinyl silicone oil; and the catalyst is dimethylcyclohexylamine.

[0057] The preparation method of the modified additive is as follows: adding 80wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 1h, adding diatomaceous earth and calcium carbonate, continuing ultrasonicating for 2.5h, filtering, and drying the filter residue to obtain the modified additive; the mass ratio of diatomaceous earth, calcium carbonate, modified silane, and 80wt% ethanol solution is 1:1:0.5:28.

[0058] A preparation method of a highly flame-retardant polyurethane thermal insulation material comprises the following steps: uniformly mixing polyol, a foaming agent, a foam stabilizer, a catalyst and a modified additive according to a mass ratio, adding polyisocyanate, stirring uniformly, pouring into a mold, foaming, aging and curing to obtain a highly flame-retardant polyurethane thermal insulation material; the foaming conditions are: foaming at 25°C for 20 minutes; the aging conditions are: aging at room temperature for 2 hours; and the curing conditions are: curing at 70°C for 2 hours.

[0059] Comparative Example 1

[0060] Compared to Example 1, the polyol is different.

[0061] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 25 parts of polyisocyanate; 20 parts of polyol; 3 parts of foaming agent; 0.8 parts of foam stabilizer; 0.4 parts of catalyst; 3 parts of modified additive;

[0062] The polyol is polyether polyol; the polyisocyanate is hexamethylene diisocyanate; the foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2:1; the physical foaming agent is n-hexane; the chemical foaming agent is water; the foam stabilizer is dimethyl silicone oil; and the catalyst is pentamethyldiethylenetriamine.

[0063] The preparation method of the modified additive and the highly flame-retardant polyurethane thermal insulation material is the same as that in Example 1.

[0064] Comparative Example 2

[0065] Compared with Example 1, the preparation method of the modified additive is different.

[0066] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 25 parts of polyisocyanate; 20 parts of polyol; 3 parts of foaming agent; 0.8 parts of foam stabilizer; 0.4 parts of catalyst; 3 parts of modified additive;

[0067] The polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 2:1; the polyisocyanate is hexamethylene diisocyanate; the foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2:1; the physical foaming agent is n-hexane; the chemical foaming agent is water; the foam stabilizer is dimethyl silicone oil; and the catalyst is pentamethyldiethylenetriamine.

[0068] The preparation method of the modified additive is as follows: adding 90wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 1h, adding calcium carbonate, continuing ultrasonicating for 3h, filtering, drying the filter residue, and uniformly mixing with diatomaceous earth to obtain the modified additive; the mass ratio of diatomaceous earth, calcium carbonate, modified silane and 90wt% ethanol solution is 1:1:0.5:30.

[0069] The preparation method of a highly flame-retardant polyurethane thermal insulation material is the same as that in Example 1.

[0070] Comparative Example 3

[0071] Compared with Example 1, the preparation method of the modified additive is different.

[0072] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 25 parts of polyisocyanate; 20 parts of polyol; 3 parts of foaming agent; 0.8 parts of foam stabilizer; 0.4 parts of catalyst; 3 parts of modified additive;

[0073] The polyol is composed of polyether polyol and polyphosphate-diol in a mass ratio of 2:1; the polyisocyanate is hexamethylene diisocyanate; the foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2:1; the physical foaming agent is n-hexane; the chemical foaming agent is water; the foam stabilizer is dimethyl silicone oil; and the catalyst is pentamethyldiethylenetriamine.

[0074] The preparation method of the modified additive is as follows: adding 90wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 1h, adding diatomaceous earth, continuing ultrasonicating for 3h, filtering, drying the filter residue, and uniformly mixing with calcium carbonate to obtain the modified additive; the mass ratio of diatomaceous earth, calcium carbonate, modified silane and 90wt% ethanol solution is 1:1:0.5:30.

[0075] The preparation method of a highly flame-retardant polyurethane thermal insulation material is the same as that in Example 1.

[0076] Comparative Example 4

[0077] Compared with Example 1, the preparation methods of the polyol and the modifying additive are different.

[0078] A highly flame-retardant polyurethane thermal insulation material is prepared by including the following raw materials in parts by weight: 25 parts of polyisocyanate; 20 parts of polyol; 3 parts of foaming agent; 0.8 parts of foam stabilizer; 0.4 parts of catalyst; 3 parts of modified additive;

[0079] The polyol is polyether polyol; the polyisocyanate is hexamethylene diisocyanate; the foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2:1; the physical foaming agent is n-hexane; the chemical foaming agent is water; the foam stabilizer is dimethyl silicone oil; and the catalyst is pentamethyldiethylenetriamine.

[0080] The preparation method of the modified additive is as follows: diatomaceous earth and calcium carbonate in a mass ratio of 1:1 are uniformly mixed to obtain the modified additive.

[0081] The preparation method of a highly flame-retardant polyurethane thermal insulation material is the same as that in Example 1.

[0082] Related performance tests

[0083] The polyurethane thermal insulation materials prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests, wherein the density test was conducted in accordance with GB / T 6343-2009; the thermal conductivity test was conducted in accordance with GB / T 3399-1982; the dimensional stability test was conducted in accordance with GB / T 8811-2008, under the conditions of measuring the dimensional change of the foam at a low temperature of -30°C after 48 hours, and measuring the dimensional change of the foam at a high temperature of 70°C and a relative humidity of 95% after 48 hours; the compression strength test was conducted in accordance with GB / T 8813-2008; and the limiting oxygen index test was conducted in accordance with GB / T 2406.2-2008. The test results are shown in Table 1.

[0084] Table 1 Performance test results of polyurethane insulation materials

[0085]

[0086] It can be seen from the results in Table 1 that the density, dimensional stability, compressive strength and limiting oxygen index of the polyurethane thermal insulation materials prepared in Examples 1-4 of the present invention are higher than those in Comparative Examples 1-4, and the thermal conductivity is lower than that in Comparative Examples 1-4, indicating that the polyurethane thermal insulation materials prepared in the present invention have good dimensional stability, thermal insulation performance, strength and flame retardant properties; especially excellent strength and flame retardant properties.

[0087] By comparing Example 1 with Comparative Examples 1-4, it can be seen that the polyol in Example 1 of the present invention is composed of polyether polyol and polyphosphate-diol. The polyphosphate-diol contains flame-retardant polyphosphate groups and nitrogen elements, which greatly improves the flame retardant properties of the polyurethane thermal insulation material. The added modifying additives are diatomaceous earth and calcium carbonate modified by modified silane containing polyphosphate groups. The modified diatomaceous earth and calcium carbonate both contain flame-retardant polyphosphate groups, nitrogen elements and silicon elements, which can synergize with polyphosphate-diol to jointly improve the flame retardant properties of the polyurethane thermal insulation material. Moreover, the modified diatomaceous earth and calcium carbonate have better compatibility with other organic raw materials, can be better dispersed in the polyurethane system, and form a thermal insulation material with a more uniform and stable structure, which helps to improve the strength and flame retardancy of the thermal insulation material, thereby obtaining a polyurethane thermal insulation material with good comprehensive performance.

[0088] It should be noted that, in this document, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or device; although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A highly flame-retardant polyurethane thermal insulation material, characterized in that: The preparation method comprises the following raw materials in parts by weight: 20-25 parts of polyisocyanate; 15-20 parts of polyol; 2-4 parts of foaming agent; 0.6-0.8 parts of foam stabilizer; 0.3-0.5 parts of catalyst; 2-3 parts of modified additive; The polyol is composed of a polyether polyol and a polyphosphate-diol in a mass ratio of 1-2:1; the preparation method of the polyphosphate-diol is as follows: anhydrous tetrahydrofuran, chloro-polyphosphate and N,N-diisopropylethylamine are added to a reaction container, nitrogen protection is provided, stirring is performed uniformly, a tetrahydrofuran solution containing 2-amino-1,3-propanediol is added dropwise, after the addition is completed, the temperature is raised to 50-60° C., and the reaction is performed for 4-5 hours to obtain a polyphosphate-diol having the structural formula: The preparation method of the modified additive is as follows: adding 80-90wt% ethanol solution and modified silane into a reaction container, ultrasonicating for 0.5-1h, adding diatomaceous earth and calcium carbonate, ultrasonicating for 2-3h, filtering, and drying the filter residue to obtain the modified additive; the structural formula of the modified silane is:

2. A highly flame-retardant polyurethane thermal insulation material according to claim 1, characterized in that: The preparation method of the modified silane is: S1. Add N,N-dimethylformamide, 4-chlorophenyl dichlorophosphate and triethylamine to the reaction vessel, protect with nitrogen, stir evenly, cool to -5-0°C, add dropwise N,N-dimethylformamide solution containing dimethyl 2-hydroxyethylphosphonate, react for 6-8h, and obtain chloro-polyphosphate, the structural formula of which is: S2. Add anhydrous tetrahydrofuran, chloro-polyphosphate and triethylamine into the reaction container, protect with nitrogen, stir evenly, add dropwise a tetrahydrofuran solution containing 3-aminopropyltriethoxysilane, raise the temperature to 45-50°C, react for 4-6h, and obtain modified silane.

3. A highly flame-retardant polyurethane thermal insulation material according to claim 2, characterized in that: The molar ratio of 4-chlorophenyl dichlorophosphate, 2-hydroxyethyl dimethyl phosphonate and triethylamine in step S1 is 1:2-2.1:2.3-2.5; the molar ratio of 3-aminopropyl triethoxysilane, chloro-polyphosphate and triethylamine in step S2 is 1:1-1.1:0.3-0.

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4. A highly flame-retardant polyurethane thermal insulation material according to claim 1, characterized in that: In the preparation method of polyphosphate-diol, the molar ratio of 2-amino-1,3-propanediol, chloro-polyphosphate and N,N-diisopropylethylamine is 1:1-1.1:1.3-1.

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5. The highly flame-retardant polyurethane thermal insulation material according to claim 1, characterized in that: In the preparation method of the modified additive, the mass ratio of diatomite, calcium carbonate, modified silane and 80-90wt% ethanol solution is 1:0.8-1:0.3-0.5:25-30.

6. The highly flame-retardant polyurethane thermal insulation material according to claim 1, characterized in that: The polyisocyanate is any one of diphenylmethane diisocyanate, hexamethylene diisocyanate and toluene diisocyanate or a mixture of several of them.

7. The highly flame-retardant polyurethane thermal insulation material according to claim 1, characterized in that: The foaming agent is composed of a physical foaming agent and a chemical foaming agent in a mass ratio of 2-3:1; the physical foaming agent is any one of dichloromethane, n-hexane, and petroleum ether, or a mixture of several of them; the chemical foaming agent is any one of water, azodicarbonamide, and isopropyl azodicarboxylate, or a mixture of several of them.

8. The highly flame-retardant polyurethane thermal insulation material according to claim 1, characterized in that: The foam stabilizer is dimethyl silicone oil or vinyl silicone oil; the catalyst is any one of pentamethyldiethylenetriamine, dimethylcyclohexylamine and pentamethylcyclohexylamine or a mixture of several of them.

9. The method for preparing a highly flame-retardant polyurethane thermal insulation material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly mixing polyol, foaming agent, foam stabilizer, catalyst and modified additive according to mass ratio, adding polyisocyanate, stirring uniformly, pouring into a mold, foaming, aging and curing to obtain a highly flame-retardant polyurethane thermal insulation material.

10. The method for preparing a highly flame-retardant polyurethane thermal insulation material according to claim 9, characterized in that: The foaming conditions are: foaming at 25-30° C. for 20-30 minutes; the aging conditions are: aging at room temperature for 1-2 hours; and the curing conditions are: curing at 70-80° C. for 2-3 hours.

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