Preparation method of low-cost bio-based intrinsic flame-retardant polyurethane

Abstract

The invention belongs to the technical field of preparation of environment-friendly flame-retardant high polymer materials, and particularly relates to a preparation method of low-cost bio-based intrinsic flame-retardant polyurethane. The low-cost bio-based polyol is prepared by taking phytic acid and micromolecular polyol as raw materials, and the low-cost bio-based intrinsic flame-retardant polyurethane is prepared by carrying out simple one-pot polymerization on the self-prepared low-cost bio-based polyol and isocyanate. The material has excellent flame retardant property without adding any flame retardant, and the preparation method is simple and convenient and low in cost. The invention belongs to a bio-based flame-retardant high polymer material, and a renewable material with low-cost bio-based intrinsic flame-retardant polyurethane as a bio-based source is prepared. The invention is mainly applicable to the fields of energy storage / power battery thermal management materials, buildings, packaging materials, protective coatings, oil tank sealants, high-safety electronic equipment and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of environmentally friendly flame-retardant polymer materials, and in particular relates to a method for preparing low-cost bio-based flame-retardant polyurethane. Background Art

[0002] Compared with traditional flame-retardant inorganic materials and metal materials, flame-retardant polymer materials have the advantages of light weight, low rigidity and strong environmental adaptability. Therefore, they are widely used in packaging materials, protective coatings, wires and cables, oil tank sealants, electronic equipment and other fields. Flame-retardant polymer materials can quickly self-extinguish after being ignited, thereby effectively preventing the spread of flames and significantly improving safety indicators. Polyurethane refers to a synthetic polymer with carbamate repeating units in the polymer main chain, which has excellent mechanical properties, corrosion resistance and low temperature resistance. Due to the designability of its molecular structure, polyurethane materials play an irreplaceable role in energy storage / power battery thermal management materials, construction, foams, medical equipment, adhesives / sealants, coatings, packaging materials and other fields, and are known as "universal polymer materials."

[0003] However, current research shows that polyurethane is an extremely flammable material that releases toxic gases when burned, causing great harm to people's lives and property. Therefore, it is crucial to develop flame-retardant polyurethane materials. Currently, the preparation of flame-retardant polyurethane mostly adopts the method of adding flame retardants, which leads to several disadvantages, including complex operation, migration of small molecule additives, deterioration of the inherent properties of the matrix, harmful combustion by-products and high costs. In summary, the development of low-cost bio-based flame-retardant polyurethane is urgent, but there is no report yet. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention proposes a method for preparing a low-cost bio-based flame-retardant polyurethane, which solves the technical problems of the complex preparation of traditional flame-retardant polyurethane, the migration of small molecule additives, the deterioration of the inherent properties of the matrix, harmful combustion byproducts and high costs. In addition, the material is prepared using low-cost raw materials and bio-based phytic acid, so that the obtained low-cost bio-based flame-retardant polyurethane is a renewable material of bio-based origin, which can be widely used in energy storage / power battery thermal management materials, construction, packaging materials, protective coatings, wires and cables, oil tank sealants, electronic equipment and other industries.

[0005] The present invention adopts the following technical solution:

[0006] Low-cost bio-based flame-retardant polyurethane is prepared by a simple one-pot polymerization of homemade low-cost bio-based polyol and isocyanate. The reaction equation is as follows:

[0007]

[0008] The specific steps are as follows:

[0009] (1) Adding phytic acid and a small molecular weight polyol into a 250 ml three-necked flask, reacting at 130-140° C. under nitrogen protection for 2 h, until the acid value drops to 1 mg KOH / g and the reaction is stopped, the crude product is washed with cyclohexane and placed in a vacuum oven at 80° C. for 4 h, and then cooled to obtain a low-cost phytic acid polyol;

[0010] Wherein, the small molecule polyol is one of glycerol, diglycerol, pentaerythritol, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol;

[0011] The molar ratio of the phosphoric acid group in the phytic acid to the hydroxyl group in the small molecule polyol is 1:2.

[0012] (2) adding linear diol oligomer, isocyanate, organotin catalyst and organic solvent to the dehydrated low-cost phytic acid polyol, reacting at 60-80° C. for 4 h, pouring the above product into a polytetrafluoroethylene plate, and drying in an oven at 80° C. for 24-48 h to obtain a low-cost bio-based flame-retardant polyurethane;

[0013] Wherein, the linear diol oligomer is one of polycarbonate diol, polycaprolactone diol, polylactic acid diol, polytetrahydrofuran diol, polyethylene glycol, and hydroxyl-terminated polydimethylsiloxane, and the number average molecular weight is 600-1000;

[0014] The isocyanate is one of isophorone diisocyanate, 2,4-toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate;

[0015] The organic tin catalyst is dibutyltin dilaurate or stannous octoate; the organic solvent is one of N,N-dimethylformamide, acetone, ethyl acetate, butyl acetate, dichloromethane and tetrahydrofuran.

[0016] The organotin catalyst is dibutyltin dilaurate or stannous octoate;

[0017] The molar ratio of the isocyanate in the isocyanate to the hydroxyl in the low-cost phytic acid polyol and the hydroxyl in the linear diol oligomer is 3:1.5-3:0-1.5; preferably 3:2.4:1.

[0018] The amount of the organotin catalyst is 0.1-0.5 wt % of the mass of the low-cost phytic acid polyol.

[0019] Beneficial effects:

[0020] The present invention uses low-cost bio-based phytic acid widely present in plant seeds and grains as a raw material to prepare low-cost phytic acid polyols, and then prepares low-cost bio-based flame-retardant polyurethane materials. When the material encounters an open flame, it can self-extinguish without adding any flame retardant because the molecular chain structure contains a large amount of phosphorus elements; in addition, due to the rigid structure and multi-functionality of phytic acid polyols, there are a suitable number of rigid cross-linking sites in the polyurethane, so that the material has excellent mechanical properties. Due to the low cost of material preparation, the green and environmentally friendly source of raw materials, and the excellent performance of the obtained material, the low-cost bio-based flame-retardant polyurethane has broad industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an infrared spectrum of a low-cost bio-based flame-retardant polyurethane prepared in Example 1 using diglycerol as a small molecule polyol, polytetramethylene glycol with a number average molecular weight of 600 and isophorone diisocyanate as raw materials;

[0022] Figure 2 This is a thermogravimetric analysis diagram of a low-cost bio-based flame-retardant polyurethane obtained by using diglycerol as a small molecule polyol, polytetramethylene glycol with a number average molecular weight of 600 and isophorone diisocyanate as raw materials in Example 1;

[0023] Figure 3 This is a differential scanning calorimetry diagram of the low-cost bio-based flame-retardant polyurethane prepared in Example 1 using diglycerol as a small molecule polyol, polytetramethylene glycol with a number average molecular weight of 600, and isophorone diisocyanate as raw materials. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (5.2 g) with a number average molecular weight of 600, isophorone diisocyanate (6.6 g), an organic tin catalyst (0.0045 g), and N, N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0027] Infrared analysis showed that the product -1 The characteristic peak of the isocyanate group disappears, indicating that the isocyanate reaction is complete; at 3300cm -1 The peak near is the characteristic peak of -NH, at 490cm -1 The characteristic peak of POC appears, 1440cm -1 and 2910cm -1 The left and right sides are the characteristic peaks of -CH2, 1500cm -1 , 1600cm -1 The characteristic peaks of amides are on the left and right, 1700 cm -1 It is the characteristic peak of carbonyl group. The appearance of the above characteristic peaks indicates the successful synthesis of low-cost bio-based flame-retardant polyurethane.

[0028] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 29.8%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 11.87MPa, and the elongation at break was 663%.

[0029] Example 2

[0030] Phytic acid (66 g) and glycerol (36.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (5.2 g) with a number average molecular weight of 600, isophorone diisocyanate (6.6 g), an organic tin catalyst (0.0045 g), and N, N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0031] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 29.6%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 10.33MPa, and the elongation at break was 652%.

[0032] Example 3

[0033] Phytic acid (66 g) and 1,4-butanediol (54 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (5.2 g) with a number average molecular weight of 600, isophorone diisocyanate (6.6 g), an organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0034] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 28.3%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 8.01MPa, and the elongation at break was 702%.

[0035] Example 4

[0036] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (5.2 g) with a number average molecular weight of 600, toluene diisocyanate (5.2 g), an organic tin catalyst (0.0045 g), and N, N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0037] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 29.9%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 12.06MPa, and the elongation at break was 415%.

[0038] Example 5

[0039] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130°C under nitrogen protection for 2 h until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80°C for 4 h. After cooling, low-cost phytic acid polyol was obtained. To the dehydrated low-cost phytic acid polyol (4.5 g), polytetrahydrofuran diol (5.2 g) with a number average molecular weight of 600, hexamethylene diisocyanate (5.1 g), an organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 mL) were added. The mixture was rapidly stirred and reacted at 80°C under nitrogen atmosphere for 4 h. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80°C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0040] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0, and the limiting oxygen index was 28.0%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 8.62MPa, and the elongation at break was 692%.

[0041] Example 6

[0042] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (9.2 g) with a number average molecular weight of 1000, isophorone diisocyanate (6.6 g), an organic tin catalyst (0.0045 g), and N, N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0043] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-2 level, and the limiting oxygen index was 25.2%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 8.32MPa, and the elongation at break was 910%.

[0044] Example 7

[0045] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Isophorone diisocyanate (5.17 g), an organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g), and the mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0046] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 27.2%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 10.46MPa, and the elongation at break was 522%.

[0047] Example 8

[0048] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (3.5 g) with a number average molecular weight of 600, isophorone diisocyanate (2.59 g), an organic tin catalyst (0.0045 g), and N, N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0049] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 29.8%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 9.53MPa, and the elongation at break was 604%.

[0050] Example 9

[0051] Phytic acid (66 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130 ° C for 2 h under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, low-cost phytic acid polyol was obtained. Polytetrahydrofuran diol (3.51 g) with a number average molecular weight of 600, isophorone diisocyanate (1.94 g), an organic tin catalyst (0.0045 g), and N, N-dimethylformamide (10 mL) were added to the dehydrated low-cost phytic acid polyol (4.5 g). The mixture was rapidly stirred and reacted at 80 ° C for 4 h under nitrogen atmosphere. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0052] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 29.8%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 10.24MPa, and the elongation at break was 479%.

[0053] Comparative Example 1

[0054] Cyclohexanehexacarboxylic acid (34.8 g) and diglycerol (49.8 g) were added to a 250 ml three-necked flask, and the mixture was reacted at 130° C. under nitrogen protection for 2 h until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80° C. for 4 h. After cooling, a low-cost polyol was obtained. Polytetrahydrofuran diol (10.2 g) with a number average molecular weight of 600, isophorone diisocyanate (6.6 g), an organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 mL) were added to the dehydrated low-cost polyol (4.5 g). The mixture was rapidly stirred and reacted at 80° C. under nitrogen atmosphere for 4 h. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80° C. for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0055] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0, and the limiting oxygen index was 17.8%; the mechanical properties were tested according to ASTM D882, with a test speed of 50mm / min, the tensile strength was 6.67MPa, and the elongation at break was 500%.

[0056] Comparative Example 2

[0057] Phytic acid (66 g) and diglycerol (41.5 g) were added to a 250 ml three-necked flask, and the mixture was reacted for 2 h at 130 ° C under nitrogen protection until the acid value dropped to 1 mg KOH / g and the reaction was stopped. The crude product was washed with cyclohexane and placed in a vacuum oven at 80 ° C for 4 h. After cooling, a low-cost polyol was obtained. To the dehydrated polytetrahydrofuran diol (10.2 g) with a number average molecular weight of 600, isophorone diisocyanate (6.6 g), an organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 mL), the mixture was rapidly stirred and reacted for 2 h at 80 ° C under a nitrogen atmosphere, and a low-cost polyol (4.5 g) was added and reacted for 2 h. The above product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 ° C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0058] In order to verify the flame retardant properties of the material, a flame retardant test was carried out according to the UL94 standard, and the flame retardant grade was measured to be UL94V-0 level, and the limiting oxygen index was 17.8%; the mechanical properties were tested according to ASTM D882 sample preparation, the test speed was 50mm / min, the tensile strength was 7.24MPa, and the elongation at break was 491%.

[0059] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a low-cost bio-based flame-retardant polyurethane, characterized in that: The preparation method steps are as follows: (1) mixing phytic acid and a small molecule polyol, reacting them under nitrogen protection until the acid value drops to 1 mg KOH / g to stop the reaction, washing, drying, and cooling to obtain a low-cost phytic acid polyol; (2) Adding linear diol oligomer, isocyanate, organotin catalyst and organic solvent to low-cost phytic acid polyol, mixing and reacting, and drying to obtain low-cost bio-based flame-retardant polyurethane.

2. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: The small molecule polyol in step (1) is one of glycerol, diglycerol, pentaerythritol, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

3. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: In step (1), the molar ratio of the phosphoric acid group in the phytic acid to the hydroxyl group in the small molecule polyol is 1:

2.

4. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: The reaction temperature in step (1) is 130-140° C. and the reaction time is 2 h.

5. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: The linear diol oligomer in step (2) is one of polycarbonate diol, polycaprolactone diol, polylactic acid diol, polytetrahydrofuran diol, polyethylene glycol, and hydroxyl-terminated polydimethylsiloxane, and has a number average molecular weight of 600-1000; The isocyanate is one of isophorone diisocyanate, 2,4-toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate; The organotin catalyst is dibutyltin dilaurate or stannous octoate; The organic solvent is one of N,N-dimethylformamide, acetone, ethyl acetate, butyl acetate, dichloromethane and tetrahydrofuran.

6. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: In step (2), the molar ratio of the isocyanate in the isocyanate to the hydroxyl in the low-cost phytic acid polyol and the hydroxyl in the linear diol oligomer is 3:1.5-3:0-1.

5.

7. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: The amount of the organotin catalyst in step (2) is 0.1-0.5wt% of the mass of the low-cost phytic acid polyol.

8. The method for preparing low-cost bio-based flame-retardant polyurethane according to claim 1, characterized in that: The mixed reaction temperature in step (2) is 60-80°C and the time is 4 hours.

9. A low-cost bio-based flame-retardant polyurethane prepared by the method according to any one of claims 1 to 8.

Images