A method for preparing a low cost bio-based essential flame retardant polyurethane

Abstract

The present application belongs to the technical field of environment-friendly flame-retardant polymer material preparation, and particularly relates to a preparation method of low-cost bio-based characteristic flame-retardant polyurethane. The present application uses phytic acid and small-molecule polyols as raw materials to prepare low-cost bio-based polyols, and then the low-cost bio-based polyols are subjected to simple one-pot polymerization with isocyanate to prepare low-cost bio-based characteristic flame-retardant polyurethane. The material has excellent flame-retardant performance without adding any flame retardant, and the preparation method is simple and low in cost. The present application belongs to bio-based flame-retardant polymer material, and the prepared low-cost bio-based characteristic flame-retardant polyurethane is a renewable material of bio-based origin. The present application is mainly suitable for the fields of energy storage / power battery thermal management materials, building, packaging materials, protective coating, oil tank sealing glue, high-safety electronic equipment and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environment-friendly flame-retardant polymer material preparation, and particularly relates to a preparation method of low-cost bio-based flame-retardant polyurethane. BACKGROUND

[0002] Compared with traditional flame-retardant inorganic materials and metal materials, the flame-retardant polymer material has the advantages of lightweight, low rigidity, and strong environmental adaptability, and is thus widely applied in the fields of packaging materials, protective coatings, electric wires and cables, tank sealing glue, electronic equipment, etc. The flame-retardant polymer material can be self-extinguished after being ignited, thereby effectively preventing the spread of fire and significantly improving the safety index. The polyurethane refers to a synthetic polymer with urethane repeating units in the polymer main chain, and has excellent mechanical properties, corrosion resistance and low-temperature resistance. Due to the designability of the molecular structure, the polyurethane material has an irreplaceable role in the fields of energy storage / power battery thermal management materials, buildings, foams, medical devices, adhesives / sealants, coatings, packaging materials, etc., and is known as the "all-purpose polymer material".

[0003] However, current research shows that the polyurethane is a highly flammable material, which releases toxic gases during combustion, thereby causing great harm to people's life and property safety. Therefore, it is crucial to develop flame-retardant polyurethane materials. At present, the flame-retardant polyurethane is mostly prepared by adding flame retardants, which causes several shortcomings, including complex operation, migration of small molecule additives, deterioration of inherent properties of the matrix, harmful combustion byproducts and high cost. In summary, it is urgent to develop low-cost bio-based flame-retardant polyurethane, but there is no report on this at present. SUMMARY

[0004] The present application aims at the deficiencies of the prior art, and provides a preparation method of low-cost bio-based flame-retardant polyurethane, which solves the technical problems of complex preparation of traditional flame-retardant polyurethane, migration of small molecule additives, deterioration of inherent properties of the matrix, harmful combustion byproducts and high cost. Moreover, the material is prepared by 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, and can be widely applied in the industries of energy storage / power battery thermal management materials, buildings, packaging materials, protective coatings, electric wires and cables, tank sealing glue, electronic equipment, etc.

[0005] The application adopts the following technical scheme:

[0006] The low-cost bio-based flame-retardant polyurethane is prepared by simple one-pot polymerization of self-made low-cost bio-based polyol and isocyanate, and the reaction equation is as follows:

[0007]

[0008] The specific steps are as follows:

[0009] (1) In a 250ml three-necked flask, add phytic acid and small molecule polyol, and react under nitrogen protection at 130-140℃ for 2h until the acid value is reduced to 1mg KOH / g to stop the reaction, wash the crude product with cyclohexane, and then place it in a 80℃ vacuum oven for 4h, and then cool to obtain low-cost phytic acid polyol;

[0010] The small molecule polyol is one of glycerol, diglycerol, pentaerythritol, ethylene glycol, 1,3-propanediol, 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) Add linear diol oligomer, isocyanate, organic tin catalyst, and organic solvent to the low-cost phytic acid polyol treated by dehydration, and react at 60-80℃ for 4h, pour the product into a polytetrafluoroethylene plate, and dry in an oven at 80℃ for 24-48h to obtain low-cost bio-based flame-retardant polyurethane;

[0013] 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; and the organic solvent is one of N,N-dimethylformamide, acetone, ethyl acetate, butyl acetate, dichloromethane, and tetrahydrofuran.

[0016] The organic tin catalyst is dibutyltin dilaurate or stannous octoate.

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

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

[0019] Beneficial effects:

[0020] The low-cost bio-based flame-retardant polyurethane material is prepared by using the low-cost bio-based phytic acid widely existing in plant seeds and grains as raw material. When the material meets open fire, it can be self-extinguished without adding any flame retardant due to the large amount of phosphorus element in the molecular chain structure. In addition, due to the rigid structure and multi-functionality of the phytic acid polyol, there are a proper number of rigid crosslinking sites in the polyurethane, so that the material has excellent mechanical properties. Since the material has low preparation cost, green and environmentally friendly raw material source and excellent performance, the low-cost bio-based flame-retardant polyurethane has broad industrialization prospects. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The infrared spectrum of the low-cost bio-based flame-retardant polyurethane prepared by using diglycerol as a small molecule polyol, polytetrahydrofuran diol with a number average molecular weight of 600 and isophorone diisocyanate as raw materials in Example 1;

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

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

[0024] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] Example 1

[0026] In a 250 ml three-necked flask, phytic acid (66 g) and diglycerol (49.8 g) were added and reacted under nitrogen atmosphere at 130 °C for 2 h until the acid value was reduced to 1 mg KOH / g. The crude product was washed with cyclohexane and then placed in a vacuum oven at 80 °C for 4 h. After cooling, the low cost phytic acid polyol was obtained. To the low cost phytic acid polyol (4.5 g) treated by dehydration, polytetrahydrofuran diol with a number average molecular weight of 600 (5.2 g), isophorone diisocyanate (6.6 g), tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml) were added. The reaction was carried out under nitrogen atmosphere at 80 °C for 4 h with rapid stirring. The product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 °C for 24 h to obtain the low cost bio-based flame retardant polyurethane.

[0027] Infrared analysis showed that the characteristic peak of isocyanate group at 2270 cm -1 disappeared, indicating that the isocyanate reaction was complete. The peak near 3300 cm -1 was the characteristic peak of -NH, the characteristic peak of P-O-C appeared at 490 cm -1 , the characteristic peaks of -CH2appeared at 1440 cm -1 and 2910 cm -1 , the characteristic peaks of amide appeared at 1500 cm -1 and 1600 cm -1 , and the characteristic peak of carbonyl appeared at 1700 cm -1 . The appearance of the above characteristic peaks indicated the successful synthesis of the low cost bio-based flame retardant polyurethane.

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

[0029] Example 2

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

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

[0032] Example 3

[0033] In a 250 ml three-necked flask, phytic acid (66 g) and glycerol (36.8 g) were added and reacted under nitrogen atmosphere at 130 °C for 2 h until the acid value was reduced to 1 mg KOH / g. The reaction was stopped and the crude product was washed with cyclohexane and then placed in a vacuum oven at 80 °C for 4 h. After cooling, the low-cost phytic acid polyol was obtained. To the low-cost phytic acid polyol (4.5 g) treated by dehydration, polytetrahydrofuran diol (5.2 g) with a number average molecular weight of 600, isophorone diisocyanate (6.6 g), tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml) were added. The reaction was carried out under nitrogen atmosphere at 80 °C for 4 h with rapid stirring. The product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 °C for 24 h to obtain the low-cost bio-based flame-retardant polyurethane.

[0034] To verify the flame retardant properties of the material, the flame retardancy test was carried out according to the UL94 standard, and the flame retardant grade was UL94 V-0 level, and the limiting oxygen index was 29.6%. The mechanical properties were tested according to ASTM D882, the test speed was 50 mm / min, the tensile strength was 10.33 MPa, and the elongation at break was 652%.

[0035] Example 4

[0036] In a 250 ml flask, add phytic acid (66 g) and diglycerol (49.8 g), and react under nitrogen protection at 130 °C for 2 h until the acid value is reduced to 1 mg KOH / g, stop the reaction, wash the crude product with cyclohexane, and then place it in a vacuum oven at 80 °C for 4 h, cool it, and obtain the low-cost phytic acid polyol; to the low-cost phytic acid polyol (4.5 g) treated by dehydration, add polytetrahydrofuran diol with a number average molecular weight of 600 (5.2 g), toluene diisocyanate (5.2 g), organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml), and react under nitrogen atmosphere at 80 °C for 4 h with rapid stirring, pour the above product into a polytetrafluoroethylene plate, dry it in an oven at 80 °C for 24 h, and obtain the low-cost bio-based flame-retardant polyurethane.

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

[0038] Example 5

[0039] In a 250 ml flask, add phytic acid (66 g) and diglycerol (49.8 g), and react under nitrogen protection at 130 °C for 2 h until the acid value is reduced to 1 mg KOH / g, stop the reaction, wash the crude product with cyclohexane, and then place it in a vacuum oven at 80 °C for 4 h, cool it, and obtain the low-cost phytic acid polyol; to the low-cost phytic acid polyol (4.5 g) treated by dehydration, add polytetrahydrofuran diol with a number average molecular weight of 600 (5.2 g), toluene diisocyanate (5.2 g), organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml), and react under nitrogen atmosphere at 80 °C for 4 h with rapid stirring, pour the above product into a polytetrafluoroethylene plate, dry it in an oven at 80 °C for 24 h, and obtain the low-cost bio-based flame-retardant polyurethane.

[0040] In order to verify the flame-retardant performance of the material, the flame-retardant test is carried out according to the UL94 standard, and the flame-retardant grade is UL94 V-0 level, and the limiting oxygen index is 29.9%; the mechanical properties are tested according to ASTM D882, the test speed is 50 mm / min, the tensile strength is 12.06 MPa, and the elongation at break is 415%.

[0041] Example 6

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

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

[0044] Example 7

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

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

[0047] Example 8

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

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

[0050] Example 9

[0051] In a 250 ml three-necked flask, phytic acid (66 g) and diglycerol (49.8 g) were added and reacted under nitrogen atmosphere at 130 °C for 2 h until the acid value was reduced to 1 mg KOH / g. The reaction was stopped and the crude product was washed with cyclohexane and then placed in a vacuum oven at 80 °C for 4 h. After cooling, the low-cost phytic acid polyol was obtained. To the dehydrated low-cost phytic acid polyol (4.5 g), polytetrahydrofuran diol with a number average molecular weight of 600 (3.5 g), isophorone diisocyanate (2.59 g), tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml) were added. The reaction was carried out under nitrogen atmosphere at 80 °C for 4 h with rapid stirring. The product was poured into a polytetrafluoroethylene plate and dried in an oven at 80 °C for 24 h to obtain the low-cost bio-based flame retardant polyurethane.

[0052] To verify the flame retardant properties of the material, the flame retardancy test was carried out according to the UL94 standard, and the flame retardant grade was UL94 V-0 level, and the limiting oxygen index was 29.8%. The mechanical properties were tested according to ASTM D882, the test speed was 50 mm / min, the tensile strength was 9.53 MPa, and the elongation at break was 604%.

[0053] Comparative Example 1

[0054] In a 250 ml flask, add phytic acid (66 g) and diglycerol (41.5 g), and react under nitrogen atmosphere at 130°C for 2 h until the acid value is reduced to 1 mg KOH / g, stop the reaction, wash the crude product with cyclohexane, and then place it in a vacuum oven at 80°C for 4 h, and after cooling, obtain a low-cost polyol; add polytetrahydrofuran diol with a number average molecular weight of 600 (10.2 g), isophorone diisocyanate (6.6 g), organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml) to the dehydrated low-cost polyol (4.5 g), and react under nitrogen atmosphere at 80°C for 2 h, add the low-cost polyol (4.5 g) and react for 2 h, pour the product into a polytetrafluoroethylene plate, and dry it in an oven at 80°C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0055] To verify the flame-retardant properties of the material, perform the flame-retardant test according to the UL94 standard, and measure that the flame-retardant grade is UL94 V-0 level and the limiting oxygen index is 17.8%; perform the sample preparation test according to ASTM D882, and measure that the tensile strength is 6.67 MPa and the elongation at break is 500% at a test speed of 50 mm / min.

[0056] Comparative Example 2

[0057] In a 250 ml flask, add phytic acid (66 g) and diglycerol (41.5 g), and react under nitrogen atmosphere at 130°C for 2 h until the acid value is reduced to 1 mg KOH / g, stop the reaction, wash the crude product with cyclohexane, and then place it in a vacuum oven at 80°C for 4 h, and after cooling, obtain a low-cost polyol; add polytetrahydrofuran diol with a number average molecular weight of 600 (10.2 g), isophorone diisocyanate (6.6 g), organic tin catalyst (0.0045 g), and N,N-dimethylformamide (10 ml) to the dehydrated low-cost polyol (4.5 g), and react under nitrogen atmosphere at 80°C for 2 h, add the low-cost polyol (4.5 g) and react for 2 h, pour the product into a polytetrafluoroethylene plate, and dry it in an oven at 80°C for 24 h to obtain a low-cost bio-based flame-retardant polyurethane.

[0058] To verify the flame-retardant properties of the material, perform the flame-retardant test according to the UL94 standard, and measure that the flame-retardant grade is UL94 V-0 level and the limiting oxygen index is 17.8%; perform the sample preparation test according to ASTM D882, and measure that the tensile strength is 6.67 MPa and the elongation at break is 500% at a test speed of 50 mm / min.

[0059] Based on the above ideal embodiments according to the present application, the relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A process for the preparation of a low cost bio-based essential sign flame retardant polyurethane characterized by: The preparation method steps are as follows: (1) mixing phytic acid and small molecule polyols, reacting under nitrogen protection until the acid value is reduced to 1 mg KOH / g, stopping the reaction, washing, drying, and cooling to obtain low-cost phytic acid polyol; the small molecule polyol is one of glycerol, diglycerol, pentaerythritol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; (2) adding linear diol oligomer, isocyanate, organic tin catalyst, and organic solvent to the low-cost phytic acid polyol, mixing and reacting, and drying to obtain low-cost bio-based characteristic flame-retardant polyurethane.

2. A process for the preparation of low cost bio-based essential flame retardant polyurethane as claimed in claim 1 wherein: 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.

3. A process for the preparation of low cost bio-based essential flame retardant polyurethane as claimed in claim 1 wherein: In step (1), the reaction temperature is 130-140°C, and the time is 2h.

4. The process for the preparation of low cost bio-based primary flame retardant polyurethane as claimed in claim 1 wherein: In step (2), 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; The isocyanate is one of isophorone diisocyanate, 2,4-toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate; 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.

5. The process for the preparation of low cost bio-based primary flame retardant polyurethane as claimed in claim 1, wherein: In step (2), the molar ratio of the isocyanate group in the isocyanate to the hydroxyl group in the low-cost phytic acid polyol and the hydroxyl group in the linear diol oligomer is 3:1.5-3:1-1.

5.

6. The process for the preparation of low cost bio-based essential sign flame retardant polyurethane as claimed in claim 1 wherein: In step (2), the amount of the organic tin catalyst is 0.1-0.5 wt% of the mass of the low-cost phytic acid polyol.

7. The process for the preparation of low cost bio-based primary flame retardant polyurethane as claimed in claim 1, wherein: In step (2), the mixing reaction temperature is 60-80°C, and the time is 4h.

8. Low-cost bio-based characteristic flame-retardant polyurethane prepared by the method of any one of claims 1-7.

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