Flame-retardant isocyanate, intrinsic flame-retardant polyurea elastomer as well as preparation method and application of intrinsic flame-retardant polyurea elastomer

Abstract

The invention relates to a flame-retardant polyurea elastomer, in particular to flame-retardant isocyanate, an intrinsic flame-retardant polyurea elastomer as well as a preparation method and application of the intrinsic flame-retardant polyurea elastomer. The preparation method comprises the following steps: firstly, modifying isocyanate, and introducing a functional group with a flame-retardant function to obtain flame-retardant isocyanate; then, aliphatic secondary amine with a flame-retardant function is introduced into a component R of the polyurea elastomer, and meanwhile, flame-retardant isocyanate is used as a component A of the polyurea elastomer, so that the intrinsic flame-retardant polyurea elastomer which is obviously improved in flame-retardant property and capable of ensuring the mechanical property of the original polyurea elastomer is obtained.

Description

Technical Field

[0001] The invention relates to a flame retardant polyurea elastomer, and more particularly to a flame retardant isocyanate, an intrinsic flame retardant polyurea elastomer and a preparation method and application thereof. Background Art

[0002] Polyurea is an elastomeric substance generated by the reaction of isocyanate components and amino compound components. The most basic properties of polyurea are anti-corrosion, waterproof, and wear resistance. Polyurea coatings have been widely used in many fields such as the automotive industry, shipbuilding industry, and construction industry due to their advantages such as fast curing, high solid content, moisture resistance, and excellent physical and chemical properties. Polyurea itself is a flammable polymer. In order to expand its scope and field of application, it needs to be modified for flame retardant properties.

[0003] There are currently two main technical approaches to improve the flame retardancy of polyurea materials, one is additive flame retardants, and the other is reactive flame retardants. Additive flame retardants are compounded by adding flame-retardant inorganic powders, phosphates, nitrogen-phosphorus flame retardants, halogen-containing flame retardants, aramid fibers, and other flame retardants to polyurea materials, or surface-modified flame retardant materials are used to improve the compatibility of the system. Reactive flame retardants are reacted with hydroxyl or amino flame retardants (such as phosphates, hydroxyl phosphates, nitrogen-phosphorus hydroxyl polyethers, hypophosphites, aminosilane coupling agents, alkylhydroxy silicone oils, etc.) in the resin system.

[0004] The method of using additive flame retardants to prepare flame retardant polyurea is relatively simple, but there are many subsequent problems. Liquid flame retardants have poor compatibility with the resin system and migrate and precipitate over time, causing the flame retardant properties of the material to decrease; solid flame retardants will significantly reduce the mechanical properties of the material. Conventional reactive flame retardants are mostly hydroxy phosphates, which can be stabilized in the resin system after reacting with NCO, improving the migration phenomenon of additive flame retardants. However, reactive flame retardants will reduce the content of urea bonds in the molecule, resulting in a decrease in intermolecular hydrogen bonds, which will lead to a decrease in strength. Summary of the invention

[0005] Improving the flame retardancy of polyurea while maintaining the original mechanical properties has always been a difficult technical barrier to overcome. In order to overcome this technical barrier, the present invention provides an intrinsic flame retardant polyurea elastomer and a preparation method and application thereof.

[0006] "Maintaining the original mechanical properties" means that the mechanical properties have declined, but the decline is far less than the improvement in flame retardant properties, and the mechanical properties can meet the use requirements.

[0007] The present invention first modifies isocyanate and introduces a functional group with a flame retardant function to obtain a flame retardant isocyanate; then, an aliphatic secondary amine with a flame retardant function is introduced into the R component of the polyurea elastomer, and at the same time, the flame retardant isocyanate is used as the A component of the polyurea elastomer, thereby obtaining an intrinsic flame retardant polyurea elastomer with significantly improved flame retardant properties while ensuring the mechanical properties of the original polyurea elastomer.

[0008] One of the objects of the present invention is to provide a flame retardant isocyanate for preparing an intrinsically flame retardant polyurea elastomer.

[0009] The structural formula of the flame retardant isocyanate is:

[0010]

[0011] M is selected from one of X, or, M is selected from more than one of X and -OCHN-R3-NHCO-;

[0012] X is and -O-R0-O-; -O-R0-O- is derived from a polyhydroxy compound;

[0013] R1, R2, R3 are independently selected from

[0014] When M is selected from one or more of X and -OCHN-R3-NHCO-, both ends of -OCHN-R3-NHCO- are connected to structures selected from X, and the structures at both ends of -OCHN-R3-NHCO- may be the same or different.

[0015] The flame retardant isocyanate, the two end groups (NCO-R1-NHCOO- or -OOCHN-R2-NCO) are derived from isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HDI), and the intermediate structure M The compound represented by formula I and the compound represented by formula II are derived to react to form a dynamic covalent adaptive network, Derived from the compound shown in formula III, -OCHN-R3-NHCO- is derived from isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HDI), and -O-R0-O- is derived from a polyhydroxy compound.

[0016]

[0017] The compound shown in formula I can be prepared by the reaction of furfural and 4-aminophenylpropanol. The preferred synthesis method of the compound shown in formula I is as follows.

[0018] Dissolve furfural and 4-aminophenylpropanol in anhydrous ethanol in an equal molar ratio to obtain a furfural solution and a 4-aminophenylpropanol solution with a mass concentration range of 5 to 10%. Under N2 protection, stir at a uniform speed, add the 4-aminophenylpropanol solution dropwise to the furfural solution within 30 to 60 minutes, heat in a water bath to 30-60°C, and reflux for 2 hours. Cool to room temperature, wash with anhydrous ethanol, and obtain the compound shown in formula I.

[0019] The specific reaction equation is as follows:

[0020]

[0021] The compound shown in formula II can be prepared by reacting succinic anhydride with 4-aminophenylpropanol. The preferred synthesis method of the compound shown in formula II is as follows.

[0022] Dissolve dianhydride and 4-aminophenylpropanol in equal molar ratios in dimethylformamide (DMF) to obtain dianhydride solution and 4-aminophenylpropanol solution with a mass concentration of 15-25%. Under N2 protection and uniform stirring, add the dianhydride solution dropwise to the 4-aminophenylpropanol solution, and complete the addition within 60 minutes; react at 40-50°C for 2-4 hours, then add phosphorus pentoxide several times (for example, 4 times), slowly add concentrated sulfuric acid to the reaction system within 15 minutes, raise the temperature to 80-85°C within 30 minutes after the addition, and react for 6-8 hours. After cooling to room temperature, precipitate in ice water, wash, and obtain the compound shown in formula II. The molar ratio of phosphorus pentoxide to dianhydride is 3-3.5:1, and the molar ratio of concentrated sulfuric acid to dianhydride is 3-3.5:1.

[0023] The specific reaction equation is as follows:

[0024]

[0025] The compound represented by formula III can be prepared by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with vanillin. The preferred synthesis method of the compound represented by formula III is as follows.

[0026] Dissolve vanillin and DOPO in anhydrous ethanol at an equal molar ratio to obtain a mixed solution with a mass concentration of 15-25%, and react at 60-80° C. for 8-10 hours under uniform stirring; distill off part of the solvent under reduced pressure, cool to room temperature, filter and dry, recrystallize and wash three times to obtain a compound represented by formula III.

[0027] The specific reaction equation is as follows:

[0028]

[0029] The flame retardant isocyanate is obtained by reacting isocyanate and a flame retardant modifier; the flame retardant modifier includes a compound shown in formula I, a compound shown in formula II, a compound shown in formula III and a polyhydroxy compound;

[0030] The molar ratio of the compound represented by formula I, the compound represented by formula II, the compound represented by formula III and the polyhydroxy compound is 1:1:(1-5):(1-10);

[0031] The molar ratio of -NCO in the isocyanate to -OH in the flame retardant modifier is (2-3):1.

[0032] The molar amount of -OH in the flame retardant modifier refers to the sum of the molar amount of -OH of the compound represented by formula I, the molar amount of -OH of the compound represented by formula II, the molar amount of -OH of the compound represented by formula III and the molar amount of -OH of the polyhydroxy compound in the flame retardant modifier.

[0033] The isocyanate may be composed of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI). As a preferred embodiment, the isocyanate is composed of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) in a molar ratio of (0.25-4):1.

[0034] The polyhydroxy compound is a compound containing two or more hydroxyl groups and can be selected from one or more of polyacrylic acid polyol, polyester polyol, polyether polyol, polycarbonate polyol, castor oil, hydroxyl-terminated polyurethane resin, and polyhydroxyl-containing epoxy resin.

[0035] The preparation method of the flame retardant isocyanate comprises:

[0036] The flame retardant modifier is dissolved in a solvent to obtain a flame retardant modifier solution; the isocyanate is heated to 50-60°C, and the flame retardant modifier solution is added dropwise under N2 protection and stirring, and the addition is completed within 0.5-1h. The reaction is carried out at 80-90°C. After the reaction is completed, the discharged material is cooled to room temperature, the solvent is removed by vacuum distillation, and the product is dried to obtain a flame retardant isocyanate.

[0037] The solvent may be butyl acetate. The mass concentration of the flame retardant modifier solution may be 40%-60%, preferably 50%.

[0038] The "reaction until the isocyanate is completely reacted" can usually be determined by measuring the NCO content. If the measured NCO% is greater than the theoretical value, it is considered that the raw material has not reacted completely and needs to be reacted further. If the measured NCO% is less than or equal to the theoretical value, it is considered that the raw material has reacted completely. The calculation method of the theoretical value of NCO% is common knowledge.

[0039] Take the molar ratio of the compound represented by formula I, the compound represented by formula II, the compound represented by formula III and the polyhydroxy compound as 1:1:1:4; the molar ratio of -NCO in isocyanate to -OH in flame retardant modifier as 8:3, the molar ratio of isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) as 3:1, and the mass concentration of flame retardant modifier solution as 50% as an example; the theoretical value of NCO% is 13.039%. Therefore, when the NCO% content in the reaction system is less than or equal to 13.039%, it means that the reaction is completed.

[0040] Normally, the reaction time required for completion of the reaction is 2 to 3 hours.

[0041] A second object of the present invention is to provide an intrinsic flame retardant polyurea elastomer.

[0042] The intrinsic flame retardant polyurea elastomer is prepared by reacting component A and component R;

[0043] The A component includes the flame retardant isocyanate as described in one of the objects of the invention;

[0044] The R component includes an amino-terminated resin, a flame-retardant aliphatic secondary amine and an amine chain extender;

[0045] The molar ratio of -NCO in the A component to -NH2 in the R component is 1:0.95-1.05.

[0046] The components of the R component are calculated by weight:

[0047] 100 parts by weight of amino-terminated resin;

[0048] 10 to 80 parts by weight of flame retardant aliphatic secondary amine; preferably 20 to 60 parts by weight;

[0049] Amine chain extender 10 to 60 parts by weight, preferably 10 to 30 parts by weight.

[0050] The amino-terminated resin is selected from at least one of polyetheramine and polyaspartic acid ester.

[0051] The amine chain extender is selected from at least one of diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-methylenebis(2-chloroaniline), and 4,4'-methylenebis(2-ethylaniline).

[0052] The flame retardant aliphatic secondary amine has a structure as shown in Formula IV;

[0053]

[0054] The flame retardant aliphatic secondary amine is prepared by the reaction of phenol, cyanuric chloride and laurylamine dipropylene diamine. The specific reaction equation is as follows:

[0055]

[0056] The preparation method of the flame retardant aliphatic secondary amine comprises:

[0057] (1) adding dropwise a solution of cyanuric chloride to a solution of phenol, and reacting under reflux at room temperature; after the reaction is completed, removing the solvent, standing to precipitate, washing, and drying to obtain a primary product;

[0058] (2) Under N2 protection and stirring, the solution of laurylamine dipropylene diamine is added dropwise to the solution of the initial product, and the reaction is carried out at 0-4°C for 4-6 hours, and then the temperature is raised to room temperature for 48 hours. After the reaction is completed, the solvent is removed, the mixture is washed, and dried to obtain a flame-retardant aliphatic secondary amine.

[0059] The solvent of cyanuric chloride is preferably dioxane, the solvent of phenol is preferably dioxane and NaOH ice water, and the solvents of the product and laurylamine dipropylene diamine are preferably tetrahydrofuran.

[0060] The flame retardant aliphatic secondary amine is preferably prepared by the following method:

[0061] (1) Phenol (0.04 mol) was dissolved in a mixed solution of 5 wt% NaOH ice water and dioxane to obtain a phenol solution with a mass concentration of 4%; cyanuric chloride (0.02 mol) was dissolved in dioxane to obtain a cyanuric chloride solution with a mass concentration of 4%. The cyanuric chloride solution was slowly added to the phenol solution within 90 minutes at room temperature and refluxed for 10 hours. After the reaction was completed, the dioxane was removed by rotary evaporation, and the solution was allowed to stand for precipitation, washed with ethyl acetate 3 times, and dried for 24 hours to obtain the initial product.

[0062] (2) Dissolve 0.05 mol of the initial product and 0.05 mol of laurylamine dipropylene diamine in 100 ml of tetrahydrofuran to obtain a primary product solution and a laurylamine dipropylene diamine solution respectively; under N2 protection, add the laurylamine dipropylene diamine solution dropwise to the initial product solution under uniform stirring within 30 min; react at 0-4°C for 4-6 h, then warm to room temperature and react for 48 h. After the reaction is completed, remove tetrahydrofuran by rotary evaporation. Wash with ethyl acetate 3 times and dry for 24 h to obtain a flame-retardant aliphatic secondary amine.

[0063] The second object of the invention is that the intrinsic flame retardant polyurea elastomer; its A component is a flame retardant isocyanate; its R component may contain one or more auxiliary agents including but not limited to leveling agent, defoamer, antistatic agent, additive flame retardant, etc. in addition to the amino-terminated resin, flame retardant aliphatic secondary amine, and amine chain extender. The dosage is conventional, and technicians can choose to add according to actual conditions.

[0064] Existing polyurea elastomers contain both hard and soft segment regions and a low degree of crosslinking, so that the polyurea material can take into account the dual properties of elasticity and strength. However, the low Tg brought about by the flexible segments and the molecular structure with a low degree of crosslinking, as well as the breaking of hydrogen bonds at high temperatures, will lead to a low melting temperature of the material and the generation of melt droplets, which will more easily lead to the spread of flames. The second purpose of the invention is the intrinsic flame-retardant polyurea elastomer, in which the compound represented by formula I in component A is introduced into a Schiff base structure through the reaction of furfural and 4-aminophenylpropanol, in which -C=N- is cracked at high temperature to form free radicals, which can not only capture the small molecular segments produced by combustion, but also undergo rearrangement-polymerization at high temperatures, thereby improving the high temperature stability of the material.

[0065] Conventional reactive flame retardants are mostly hydroxy phosphates, which can be stabilized in the resin system after reacting with NCO, improving the migration phenomenon of additive flame retardants; but at the same time, the content of urea bonds in the molecule will be reduced, resulting in a decrease in intermolecular hydrogen bonds, which will lead to a decrease in strength and fail to meet the use requirements. The intrinsic flame-retardant polyurea elastomer described in the second purpose of the invention, the compound shown in formula II in its A component, is introduced into the succinimide structure by reacting succinic anhydride with 4-aminophenylpropanol. Succinimide and furan in the compound shown in formula I jointly construct a dynamic covalent adaptive network (CANs). Even if the hydrogen bond content in the original system is reduced, the dynamic covalent bond is used to replace the N...H binding force to ensure the interaction between the original chain segments, so that the polyurea still has a high strength while improving the flame retardancy and can meet the use requirements. The principle of the dynamic covalent adaptive network is as follows.

[0066]

[0067] Among them, Rx is Ry

[0068] Currently, most of the DOPO flame retardants on the market are designed for epoxy systems, and flame retardants specifically for polyurea systems are rare. In addition, the added DOPO flame retardants in the polyurea system still have migration problems caused by poor compatibility. However, the compound shown in formula III in component A of the intrinsic flame-retardant polyurea elastomer described in the second purpose of the invention is a new DOPO reactive flame retardant synthesized from DOPO and vanillin, which can be used in polyurea. When used in polyurea, the rigid benzene ring contained in vanillin is selected to connect with P in DOPO, introducing a benzene ring to further improve the thermal stability of the material.

[0069] In the R component of the intrinsic flame-retardant polyurea elastomer described in the second object of the invention, the flame-retardant aliphatic secondary amine is an aliphatic secondary amine containing a phenyl ether triazine ring. The triazine ring has a high decomposition temperature. After the side group is connected to the phenyl group, a conjugated structure will be formed, which further improves the stability. The nitrogen-rich structure makes the triazine ring self-extinguishing when away from the fire, which can reduce the flame propagation. By controlling the molar ratio, after the phenol and cyanuric chloride react, the phenyl ether is connected to the triazine ring, and then the remaining -Cl is reacted with laurylamine dipropylene diamine to finally obtain an aliphatic secondary amine containing a phenyl ether triazine ring, which can increase the thermal decomposition temperature of the material and reduce the flame spread rate.

[0070] The third object of the present invention is to provide a method for preparing the intrinsic flame retardant polyurea elastomer described in the second object of the invention.

[0071] The preparation method of the intrinsic flame retardant polyurea elastomer comprises:

[0072] Mixing the components of component A uniformly according to the weight parts to obtain component A;

[0073] The components of the R component are mixed uniformly according to the weight parts to prepare the R component;

[0074] The A component and the R component are mixed and reacted according to the molar ratio to obtain the intrinsic flame-retardant polyurea elastomer.

[0075] For example, the R component is mixed according to the amount, and the contents of -NH2 and -NCO in the A component and the R component are calculated respectively; the A component and the B component are mixed according to the molar ratio of m(-NH2):m(-NCO)=0.95-1.05, and can be cast or sprayed; according to the construction requirements, a solvent can be appropriately added, and the solvent is preferably one or more of ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, cyclohexanone, xylene, dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylformamide.

[0076] The fourth object of the present invention is to provide an application of the intrinsic flame retardant polyurea elastomer described in the second object of the invention.

[0077] The intrinsic flame-retardant polyurea elastomer is used for making thermoplastic materials, thermosetting materials, liquid casting materials, flooring materials, waterproof materials, vibration-damping materials, edge protection materials and coatings.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] The intrinsic flame-retardant polyurea elastomer provided by the present invention does not add a flame retardant or a reactive flame retardant, but rather modifies the amino-terminated resin component (R component) and the isocyanate component (A component) respectively, and introduces functional groups with flame-retardant function into the R component and the A component; and there is no problem of decreased flame retardant performance due to precipitation of the added flame retardant.

[0080] The intrinsic flame-retardant polyurea elastomer provided by the present invention introduces functional groups into the A component and the R component; it can not only capture the small molecular segments generated by combustion, but also rearrange and polymerize at high temperature to improve the high temperature stability of the material; it can also form a dynamic covalent adaptive network, using dynamic covalent bonds instead of N...H binding forces to ensure the interaction between the original segments, so that the polyurea has a high strength while improving the flame retardancy; it can also increase the thermal decomposition temperature of the material and reduce the flame spread rate. Therefore, the intrinsic flame-retardant polyurea elastomer provided by the present invention can ensure the mechanical properties of the original polyurea elastomer and improve the flame retardancy.

[0081] The intrinsic flame-retardant polyurea elastomer provided by the present invention adopts a self-made flame-retardant resin system and has high flame-retardant efficiency.

[0082] The intrinsic flame-retardant polyurea elastomer provided by the present invention has mechanical properties that can reach the level of general polyurea materials.

[0083] The intrinsic flame-retardant polyurea elastomer provided by the present invention uses self-made flame-retardant aliphatic secondary amine and flame-retardant isocyanate, optimizes and adjusts the structure of the resin, ensures the original mechanical properties of the polyurea, and improves the flame retardancy of the material.

[0084] The intrinsic flame-retardant polyurea elastomer provided by the present invention can be used in the fields of making thermoplastic materials, thermosetting materials, liquid casting materials, flooring, waterproof materials, vibration-damping materials, edge protection materials, coatings, etc. DETAILED DESCRIPTION

[0085] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0086] The raw materials used in the examples and comparative examples are all conventional commercially available raw materials.

[0087] Example 1

[0088] (1) Dissolve 0.1 mol of furfural and 0.1 mol of 4-aminophenylpropanol in anhydrous ethanol to obtain a furfural solution and a 4-aminophenylpropanol solution with a mass concentration of 6%, respectively. Under N2 protection and uniform stirring, add the 4-aminophenylpropanol solution dropwise to the furfural solution within 45 minutes, heat in a water bath at 40°C, and reflux for 2 hours. Cool to room temperature, wash with anhydrous ethanol 3 times, and obtain the compound of formula I.

[0089]

[0090] (2) Dissolve 0.1 mol of dianhydride and 0.1 mol of 4-aminophenylpropanol in dimethylformamide (DMF) to obtain dianhydride solution and 4-aminophenylpropanol solution with a mass concentration of 15%, respectively. Under N2 protection and uniform stirring, add the dianhydride solution dropwise to the 4-aminophenylpropanol solution and complete the addition within 60 minutes. Keep the reaction at 45°C for 3 hours. Then, add 0.3 mol of phosphorus pentoxide in 4 portions, and slowly add 0.3 mol of concentrated sulfuric acid to the reaction system within 15 minutes. After the addition is complete, heat to 80°C within 30 minutes and react for 8 hours. After cooling to room temperature, precipitate in ice water and wash to obtain the compound shown in formula II.

[0091]

[0092] (3) Dissolve 0.1 mol of vanillin and 0.1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) in anhydrous ethanol to obtain a vanillin solution and a DOPO solution with a mass concentration of 15%, respectively. Mix the vanillin solution and the DOPO solution, set the temperature to 70°C, and react for 9 hours under uniform stirring. Distill off part of the solvent under reduced pressure, cool to room temperature, filter and dry, recrystallize and wash three times to obtain the compound shown in formula III.

[0093]

[0094] (4) The compounds of formula I, formula II and formula III prepared in steps (1), (2) and (3) and polyacrylic acid polyol (Dow Chemical Company, PPG-1000LM) are mixed in a molar ratio of 1:1:1:4 as a flame retardant modifier; the flame retardant modifier is prepared with butyl acetate as a solvent to prepare a flame retardant modifier solution with a mass concentration of 50%.

[0095] (5) Add a mixed solution of IPDI and HDI (the molar ratio of IPDI to HDI is 3:1) into the reactor, heat it to 50°C, and under N2 protection, dropwise add a flame retardant modifier solution (the molar ratio of -NCO in IPDI and HDI to -OH in the flame retardant modifier is 8:3) with stirring. The addition is completed within 0.5 h. After the temperature is maintained at 85°C for 3 h, the NCO content is measured to be 13.012% (theoretical NCO% = 13.039%) and the reaction is stopped. The discharge is cooled to room temperature, the solvent is removed by distillation under reduced pressure, and the mixture is dried to obtain a flame retardant isocyanate.

[0096] (6) 0.04 mol of phenol was dissolved in a mixed solution of 5 wt% NaOH ice water and dioxane (the volume ratio of NaOH ice water to dioxane was 1:1) to obtain a phenol solution with a mass concentration of 4%. 0.02 mol of cyanuric chloride was dissolved in dioxane to obtain a cyanuric chloride solution with a mass concentration of 4%. The cyanuric chloride solution was slowly added to the phenol solution within 90 minutes at room temperature, and the reaction was refluxed for 10 hours. After the reaction was completed, the dioxane was removed by rotary evaporation, and the precipitation was allowed to stand, washed with ethyl acetate 3 times, and dried for 24 hours to obtain the initial product. 0.05 mol of the initial product and 0.05 mol of laurylamine dipropylene diamine were dissolved in 100 ml of tetrahydrofuran respectively to obtain the initial product solution and laurylamine dipropylene diamine solution. Under N2 protection, the laurylamine dipropylene diamine solution was added dropwise to the initial product solution under uniform stirring within 30 minutes. The reaction was carried out at 4°C for 4 hours, and then the reaction temperature was raised to room temperature for 48 hours. After the reaction was completed, tetrahydrofuran was removed by rotary evaporation. The mixture was washed with ethyl acetate for 3 times and dried for 24 hours to obtain a flame retardant aliphatic secondary amine. The flame retardant aliphatic secondary amine has a structure as shown in Formula IV.

[0097]

[0098] (7) Mix the raw materials according to Table 1 to obtain the R component.

[0099] Table 1

[0100] raw material Weight source Polyaspartic acid F420 20 Shenzhen Feiyang Polyetheramine D2000 80 Huntsman USA Flame retardant aliphatic secondary amine 60 Step (6) Preparation Amine chain extender A95 10 Degussa

[0101] (8) The flame-retardant isocyanate prepared in step (5) is used as component A and is mixed with component R prepared in step (7) at a molar ratio of (-NCO) to (-NH2) of 1:0.95 to obtain an intrinsic flame-retardant polyurea elastomer.

[0102] (9) The performance of the intrinsic flame retardant polyurea elastomer was tested. The test method and test results are shown in Table 2.

[0103] Table 2

[0104]

[0105] Example 2

[0106] (1) The compounds of Formula I, Formula II and Formula III prepared in Example 1 and polyether polyol (BASF AG, PolyTHF 1000) were mixed in a molar ratio of 1:1:5:10 as a flame retardant modifier, and the flame retardant modifier solvent butyl acetate was prepared into a flame retardant modifier solution with a mass concentration of 50%.

[0107] (2) Prepare flame retardant isocyanate according to the method of step (5) of Example 1.

[0108] The molar ratio of IPDI to HDI in the mixed solution of IPDI and HDI is 4: 1. The molar ratio of -NCO in IPDI and HDI to -OH in the flame retardant modifier is 3:1.

[0109] (3) Mix the raw materials according to Table 3 to obtain the R component.

[0110] Table 3

[0111] raw material Weight source Polyaspartic acid NH1220 85 Bayer, Germany Polyetheramine WANAMINE8100 15 Yantai Wanhua Flame retardant aliphatic secondary amine 20 Example 1 Step (6) Preparation Amine chain extender DETDA 30 Jiangsu Victory

[0112] (4) The flame-retardant isocyanate prepared in step (2) is used as component A and is mixed with component R prepared in step (3) at a molar ratio of (-NCO) to (-NH2) of 1:1.05 to obtain an intrinsic flame-retardant polyurea elastomer.

[0113] (5) The performance of the intrinsic flame retardant polyurea elastomer was tested. The test method and test results are shown in Table 4.

[0114] Table 4

[0115] Test items Test Results Detection Methods Limiting Oxygen Index LOI 30 GB / T 10107-2008 Flame retardant grade FV-0 GB / T 10107-2008 Tensile Strength 22MPa GB / T 23446-2009 Elongation at break 310％ GB / T 23446-2009 Tear strength 52N / mm GB / T 23446-2009 Waterproof 0.4MPa, watertight for 2h GB / T 23446-2009 Bond strength 4.7MPa GB / T 23446-2009

[0116] Example 3

[0117] (1) The compounds of Formula I, Formula II and Formula III prepared in Example 1 and polyether polyol (BASF AG, PolyTHF 1000) were mixed in a molar ratio of 1:1:2:1 as a flame retardant modifier, and the flame retardant modifier solvent butyl acetate was prepared into a flame retardant modifier solution with a mass concentration of 50%.

[0118] (2) Prepare flame retardant isocyanate according to the method of step (5) of Example 1.

[0119] The molar ratio of IPDI to HDI in the mixed solution of IPDI and HDI is 0.25: 1. The molar ratio of -NCO in IPDI and HDI to -OH in the flame retardant modifier is 2:1.

[0120] (3) Mix the raw materials according to Table 5 to obtain the R component.

[0121] Table 5

[0122] raw material Weight source Polyaspartic acid NH1220 85 Bayer, Germany Polyetheramine WANAMINE8100 15 Yantai Wanhua Flame retardant aliphatic secondary amine 20 Example 1 Step (6) Preparation Amine chain extender DETDA 30 Jiangsu Victory

[0123] (4) The flame-retardant isocyanate prepared in step (2) is used as component A and is mixed with component R prepared in step (3) at a molar ratio of (-NCO) to (-NH2) of 1:1.05 to obtain an intrinsic flame-retardant polyurea elastomer.

[0124] (5) The performance of the intrinsic flame retardant polyurea elastomer was tested. The test method and test results are shown in Table 6.

[0125] Table 6

[0126]

[0127] Comparative Example 1

[0128] IPDI and HDI are used as component A; the molar ratio of IPDI to HDI is 3:1.

[0129] The raw materials were mixed according to Table 7 to obtain the R component.

[0130] Table 7

[0131] raw material Weight source Polyaspartic acid NH1220 85 Bayer, Germany Polyetheramine WANAMINE8100 15 Yantai Wanhua Amine chain extender DETDA 30 Jiangsu Victory

[0132] Component A is mixed with component R prepared in step (3) at a molar ratio of (-NCO) to (-NH2) of 1:0.95 to obtain an intrinsic flame retardant polyurea elastomer.

[0133] The performance of the intrinsic flame retardant polyurea elastomer was tested. The test method and test results are shown in Table 8.

[0134] Table 8

[0135]

[0136] In Tables 2, 4, 6, and 8, a high limiting oxygen index indicates that the material is not easy to burn, and a low limiting oxygen index indicates that the material is easy to burn. It is generally believed that a limiting oxygen index <22 is a flammable material, a limiting oxygen index between 22 and 27 is a combustible material, and a limiting oxygen index >27 is a flame retardant material.

[0137] The polyurea elastomer prepared in Comparative Example 1 has a limiting oxygen index LOI of 16 and a flame retardant grade of FV-2, which indicates that the polyurea elastomer prepared in Comparative Example 1 is a flammable material and has no flame retardant effect.

[0138] The limiting oxygen index LOI of the intrinsic flame retardant polyurea elastomers prepared in Examples 1-3 is greater than 27, and the flame retardancy grade is FV-0, which indicates that the intrinsic flame retardant polyurea elastomers prepared in Examples 1-3 are flame retardant materials and have good flame retardant effect. That is, the intrinsic flame retardant polyurea elastomer provided by the present invention has good flame retardant effect.

[0139] Compared with Comparative Example 1, the difference of Example 1 is that the A component and the R component of the polyurea elastomer are modified. Compared with the polyurea elastomer prepared in Comparative Example 1, the limiting oxygen index and the flame retardant grade of the intrinsic flame retardant polyurea elastomer prepared in Example 1 are significantly improved; wherein, the limiting oxygen index is improved by 87.5%. It is shown that the present invention improves the flame retardant properties of the polyurea elastomer by modifying the A component and the R component of the polyurea elastomer.

[0140] Compared with the polyurea elastomer prepared in comparative example 1, the mechanical properties of the intrinsic flame retardant polyurea elastomer prepared in embodiment 1 are reduced; the tensile strength is reduced by 13.8%, the elongation at break is reduced by 10.5%, the tear strength is reduced by 18.5%, the bonding strength is reduced by 10.9%, and the water impermeability is not reduced. Although the mechanical properties of embodiment 1 are reduced relative to comparative example 1, the mechanical properties of embodiment 1 can still meet the use requirements. Moreover, the reduction in mechanical properties (10-19%) is much lower than the increase in limiting oxygen index (87.5%). It shows that the invention improves the flame retardant properties of the polyurea elastomer while ensuring the original mechanical properties by modifying the A component and the R component of the polyurea elastomer.

[0141] "Maintaining the original mechanical properties" should be understood as a decrease in mechanical properties, but the decrease is small and can meet the use requirements.

Claims

1. A flame retardant isocyanate, characterized in that: The structural formula of the flame retardant isocyanate is M is selected from one of X, or, M is selected from more than one of X and -OCHN-R3-NHCO-; X is and -O-R0-O-; -O-R0-O- is derived from a polyhydroxy compound; R1, R2, R3 are independently selected from 2. The flame retardant isocyanate according to claim 1, characterized in that: Obtained by the reaction of isocyanate and flame retardant modifier; The flame retardant modifier includes a compound represented by formula I, a compound represented by formula II, a compound represented by formula III and a polyhydroxy compound; The molar ratio of the compound represented by formula I, the compound represented by formula II, the compound represented by formula III and the polyhydroxy compound is 1:1:(1-5):(1-10); The molar ratio of -NCO in the isocyanate to -OH in the flame retardant modifier is (2-3):

1.

3. The flame retardant isocyanate according to claim 2, characterized in that: The isocyanate is composed of isophorone diisocyanate and hexamethylene diisocyanate in a molar ratio of (0.25-4):1; or / and, The polyhydroxy compound is selected from at least one of polyacrylic acid polyol, polyester polyol, polyether polyol, polycarbonate polyol, castor oil, hydroxyl-terminated polyurethane resin, and polyhydroxy-containing epoxy resin.

4. The flame retardant isocyanate according to claim 2, characterized in that: The preparation method of the flame retardant isocyanate comprises: The flame retardant modifier is dissolved in a solvent to obtain a flame retardant modifier solution; the isocyanate is heated to 50-60°C, and the flame retardant modifier solution is added dropwise under N2 protection and stirring, and the addition is completed within 0.5-1h. The reaction is carried out at 80-90°C. After the reaction is completed, the discharged material is cooled to room temperature, the solvent is removed by vacuum distillation, and the product is dried to obtain a flame retardant isocyanate.

5. An intrinsic flame retardant polyurea elastomer, characterized in that: The intrinsic flame retardant polyurea elastomer is prepared by reacting component A and component R; The A component comprises the flame retardant isocyanate according to any one of claims 1 to 4; The R component includes an amino-terminated resin, a flame-retardant aliphatic secondary amine and an amine chain extender; The molar ratio of -NCO in the A component to -NH2 in the R component is 1:0.95-1.

05.

6. The intrinsic flame retardant polyurea elastomer according to claim 5, characterized in that: The components of the R component are calculated by weight: 100 parts by weight of amino-terminated resin; 10 to 80 parts by weight of flame retardant aliphatic secondary amine; preferably 20 to 60 parts by weight; Amine chain extender 10 to 60 parts by weight, preferably 10 to 30 parts by weight.

7. The intrinsic flame retardant polyurea elastomer according to claim 5, characterized in that: The amino-terminated resin is selected from one or more of polyetheramine and polyaspartic acid ester; or / and, The amine chain extender is selected from at least one of diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-methylenebis(2-chloroaniline), and 4,4'-methylenebis(2-ethylaniline).

8. The intrinsic flame retardant polyurea elastomer according to claim 5, characterized in that: The flame retardant aliphatic secondary amine has a structure as shown in Formula IV; 9. A method for preparing an intrinsic flame retardant polyurea elastomer according to any one of claims 5 to 8, characterized in that: The preparation method comprises: Mixing the components of component A uniformly according to the weight parts to obtain component A; The components of the R component are mixed uniformly according to the weight parts to obtain the R component; The A component and the R component are mixed and reacted according to the molar ratio to obtain the intrinsic flame-retardant polyurea elastomer.

10. An intrinsic flame retardant polyurea elastomer as claimed in any one of claims 5 to 8, used for making thermoplastic materials, thermosetting materials, liquid casting materials, flooring, waterproof materials, vibration reduction materials, edge protection materials, and coatings.

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