Halogen-free flame-retardant polyurethane elastomer and preparation process therefor

Abstract

Disclosed are a halogen-free flame-retardant polyurethane elastomer and a preparation process therefor. Phenyl dichlorophosphate and 4-(4-hydroxyphenyl)-2,3-diaza(4-nitrophenyl)naphthalen-1-one undergo a phosphate esterification reaction, followed by reduction with a Pd / C catalyst to yield a novel phosphate-bis-diazanaphthalone chain extender. Introducing a highly thermally stable bis-diazanaphthalone rigid fused-ring structure into a polyurethane molecular chain significantly increases the thermal decomposition temperature of the polyurethane elastomer; moreover, the phosphate-bis-diazanaphthalone chain extender contains a phosphate-based flame-retardant structure that forms a nitrogen-phosphorus halogen-free flame retardant with a diazanaphthalone nitrogen-containing heterocycle, achieving a condensed-phase flame-retardant effect; thus, the total heat release and the peak heat release rate of the polyurethane elastomer are reduced, and excellent flame-retardant performance is achieved.

Description

Halogen-free flame-retardant polyurethane elastomer and preparation process TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane, in particular to a halogen-free flame-retardant polyurethane elastomer and a preparation process. BACKGROUND

[0002] Polyurethane elastomer has high elasticity, good mechanical strength and solvent resistance, and is widely used in shoe materials, pipe materials, cables, medical and health fields. Generally, polyurethane elastomer is prepared from polyether polyol, polyester polyol, diisocyanate, chain extender and other raw materials. The polyether polyurethane elastomer has better low temperature resistance, toughness, hydrolysis stability and other properties. The polyurethane chain extender mainly includes amine chain extender and alcohol chain extender. The current polyurethane elastomer has defects such as easy decomposition at high temperature and easy combustion, which limits the application of polyurethane elastomer in high temperature resistant and flame resistant materials.

[0003] Phthalazinone compounds have rigid groups, high temperature structure stability is very good, and they contain active imino, hydroxyl and other groups, and have high reactivity, and can be used as polymer monomers, and have wide application in polyurethane, polyarylether ketone and other materials, and can improve the high temperature resistance, strength and other properties of polyurethane and other materials. The present application aims to prepare a diamine chain extender containing phosphate and phthalazinone structure, and improve the high temperature resistance and flame retardant properties of polyurethane elastomer.

[0004] SUMMARY

[0005] The present application solves the problem of poor high temperature resistance and flame retardance of polyurethane elastomer.

[0006] The technical scheme of the present application is a halogen-free flame-retardant polyurethane elastomer, which comprises the following raw materials: polyether polyol, toluene-2, 4-diisocyanate, phosphate ester bis-phthalazinone chain extender and catalyst, and the molar ratio is 1: (2.4-2.8): (0.04-0.12): (0.0012-0.0017).

[0007] Further, the structural formula of the phosphate ester bis-phthalazinone chain extender is formula (I):

[0008] Further, the polyether polyol is any one of polyethylene glycol, polytetrahydrofuran ether diol and polypropylene glycol.

[0009] Further, the catalyst is stannous octoate or dibutyltin dilaurate.

[0010] Further, the preparation process of the phosphate ester bis-phthalazinone chain extender comprises the following steps:

[0011] Step (1) under ice water bath, to the toluene is added phenyl dichlorophosphate, 4-(4-hydroxyphenyl)-2,3-diazine (4-nitrobenzene) naphthalene-1-ketone, pyridine in a molar ratio of 1: (2.3-2.8): (3.2-4), after reaction, filter, distill under reduced pressure, the product is washed with petroleum ether, dry, to obtain intermediate 1.

[0012] Step (2) to the ethanol is added hydrazine hydrate, intermediate 1, Pd / C catalyst in a mass ratio of 1: (0.12-0.16), mix well and then react, distill under reduced pressure, the product is washed with petroleum ether, then dissolved in toluene, evaporate and concentrate until a large amount of precipitate is precipitated, filter, to obtain phosphonate bisnaphthotriazine chain extender.

[0013] Further, the reaction in step (1) is carried out at a temperature of 30-45℃ for 18-36h.

[0014] Further, the reaction in step (2) is carried out at a temperature of 70-75℃ for 12-15h.

[0015] Further, the preparation process of halogen-free flame-retardant polyurethane elastomer: the dried polyether polyol, toluene-2, 4-diisocyanate are mixed, reacted at 70-75℃ for 2-3h, then the material is placed in a preheated mold, and the phosphonate bisnaphthotriazine chain extender and catalyst are added, stirred and mixed, heated and cured at 110-120℃ for 1-2h, then placed in a forced air drying machine, vulcanized at 100-110℃ for 12-18h, and finally placed at room temperature for 5-7 days to obtain halogen-free flame-retardant polyurethane elastomer.

[0016] The technical effect of the present application: the present application utilizes phenyl dichlorophosphate and 4-(4-hydroxyphenyl)-2,3-diazine (4-nitrobenzene) naphthalene-1-ketone to carry out phosphonate reaction, and then reduced by Pd / C catalyst to obtain a new phosphonate bisnaphthotriazine chain extender.

[0017] The present application introduces high-thermal-stability double-phthalazinone rigid fused ring structure into the polyurethane molecular chain, significantly improves the thermal decomposition temperature of the polyurethane elastomer, reaches 323.1-339.8 DEG C, and has good high-temperature resistance. And the phosphate double-phthalazinone chain extender contains a phosphate flame-retardant structure, and the nitrogen-containing heterocycle of phthalazinone forms a nitrogen-phosphorus halogen-free flame retardant, which decomposes into oxygen-containing phosphoric acid and nitrogen and other non-combustible gases at high temperature, can promote the dehydration and carbonization of the polyurethane elastomer, form a carbon layer structure with heat insulation and oxygen insulation on the surface of the elastomer, can reduce the high-temperature decomposition rate of the polymer, and has a condensed state flame-retardant effect, thereby reducing the total heat release and the peak value of the heat release rate of the polyurethane elastomer, and showing excellent flame-retardant performance. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described below clearly and completely. Obviously, the described embodiments are 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 belong to the scope of protection of the present application.

[0019] Into 40 mL of N,N-dimethylformamide, 4 mmol of 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one 4-nitroiodobenzene 4.2 mmol of cuprous iodide, 8.4 mmol of cesium carbonate, reaction under nitrogen atmosphere at a temperature of 120 DEG C for 12 h, addition of ethyl acetate and sodium chloride aqueous solution, extraction and separation, addition of distilled water to the ethyl acetate organic phase, extraction and separation, and column chromatography separation of the crude product with a solution of petroleum ether: ethyl acetate = 6:1 (volume ratio) as eluent to obtain 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one (4-nitrophenyl). The structural formula is

[0020] Example 1

[0021] (1) Under an ice water bath, 5 mmol of phenyl dichlorophosphate, 11.5 mmol of 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one (4-nitrophenyl), and 20 mmol of pyridine were added to 60 mL of toluene, and the reaction was carried out at a temperature of 35 DEG C for 18 h. Filtration, distillation of the filtrate under reduced pressure, washing of the product with petroleum ether, drying, weighing, and calculation of the yield. The reaction formula is:

[0022] (2) To 100 mL of ethanol, 4.5 mL of hydrazine hydrate (80% mass fraction), 8 g (9.35 mmol) of intermediate 1, 0.96 g of Pd / C catalyst were added, mixed and reacted at a temperature of 75°C for 12 h, distilled under reduced pressure, the product was washed with petroleum ether, then dissolved in toluene, evaporated and concentrated until a large amount of precipitate was precipitated, filtered to obtain the phosphonate bisphthalazinone chain extender. Weighed and calculated the yield.

[0023] Example 2

[0024] (1) To 100 mL of toluene, 5 mmol of phenyl dichlorophosphate, 14 mmol of 4-(4-hydroxyphenyl)-2,3-dinitro(4-nitrobenzene)naphthalen-1-one, 18 mmol of pyridine were added under ice water bath, reacted at a temperature of 45°C for 18 h, filtered, the filtrate was distilled under reduced pressure, the product was washed with petroleum ether and dried to obtain intermediate 1. Weighed and calculated the yield.

[0025] (2) To 100 mL of ethanol, 3.5 mL of hydrazine hydrate (80% mass fraction), 8 g (9.35 mmol) of intermediate 1, 1.28 g of Pd / C catalyst were added, mixed and reacted at a temperature of 70°C for 12 h, distilled under reduced pressure, the product was washed with petroleum ether, then dissolved in toluene, evaporated and concentrated until a large amount of precipitate was precipitated, filtered to obtain the phosphonate bisphthalazinone chain extender. Weighed and calculated the yield.

[0026] Example 3

[0027] (1) To 80 mL of toluene, 5 mmol of phenyl dichlorophosphate, 12.6 mmol of 4-(4-hydroxyphenyl)-2,3-dinitro(4-nitrobenzene)naphthalen-1-one, 20 mmol of pyridine were added under ice water bath, reacted at a temperature of 30°C for 36 h, filtered, the filtrate was distilled under reduced pressure, the product was washed with petroleum ether and dried to obtain intermediate 1. Weighed and calculated the yield.

[0028] (2) To 80 mL of ethanol, 4 mL of hydrazine hydrate (80% mass fraction), 8 g (9.35 mmol) of intermediate 1, 0.96 g of Pd / C catalyst were added, mixed and reacted at a temperature of 70°C for 15 h, distilled under reduced pressure, the product was washed with petroleum ether, then dissolved in toluene, evaporated and concentrated until a large amount of precipitate was precipitated, filtered to obtain the phosphonate bisphthalazinone chain extender. Weighed and calculated the yield.

[0029] The yield of intermediate 1 and phosphonate bisphthalazinone chain extender is as follows.

[0030] Table 1 Yield table of intermediate 1 and phosphonate bisphthalazinone chain extender

[0031] The present application utilizes phenyl dichlorophosphate, 4-(4-hydroxyphenyl)-2,3- diaza(4-nitrophenyl)naphthalen-1-one to carry out phosphonate reaction to obtain intermediate 1, and then reduction by Pd / C catalyst to obtain novel phosphonate bis-diazanaphthalenone chain extender with a yield of 69.1-76.3%

[0032] Example 4

[0033] Dry 100 mmol of polytetrahydrofuran ether glycol, 280 mmol of toluene-2,4-diisocyanate are mixed and reacted at 70°C for 3h, then the material is placed in a preheated mold (mold temperature is 110°C), and 4 mmol of phosphonate bis-diazanaphthalenone chain extender and 0.12 mmol of catalyst stannous octoate are added, stirred and mixed, hot cured at 120°C for 1h, then placed in a forced air drying machine, vulcanized at 100°C for 12h, and finally placed at room temperature for 5 days to obtain a halogen-free flame-retardant polyurethane elastomer.

[0034] Example 5

[0035] Dry 100 mmol of polyethylene glycol, 265 mmol of toluene-2,4-diisocyanate are mixed and reacted at 75°C for 2h, then the material is placed in a preheated mold (mold temperature is 110°C), and 8 mmol of phosphonate bis-diazanaphthalenone chain extender and 0.17 mmol of catalyst dibutyltin dilaurate are added, stirred and mixed, hot cured at 110°C for 2h, then placed in a forced air drying machine, vulcanized at 100°C for 18h, and finally placed at room temperature for 7 days to obtain a halogen-free flame-retardant polyurethane elastomer.

[0036] Example 6

[0037] Dry 100 mmol of polypropylene glycol, 240 mmol of toluene-2,4-diisocyanate are mixed and reacted at 75°C for 3h, then the material is placed in a preheated mold (mold temperature is 110°C), and 12 mmol of phosphonate bis-diazanaphthalenone chain extender and 0.17 mmol of catalyst dibutyltin dilaurate are added, stirred and mixed, hot cured at 120°C for 1h, then placed in a forced air drying machine, vulcanized at 110°C for 12h, and finally placed at room temperature for 7 days to obtain a halogen-free flame-retardant polyurethane elastomer.

[0038] Comparative Example 1

[0039] Dry 100 mmol polytetrahydrofuran ether glycol, 280 mmol toluene-2, 4-diisocyanate were mixed, reacted at 70℃ for 3h, then the material was placed in a preheated mold (mold temperature was 110℃), and 4 mmol of 4-(4-hydroxyphenyl)-2, 3-phthalazin-1-one was added as a chain extender, 0.12 mmol of catalyst stannous octoate, stirred and mixed, 120℃ hot curing 1h, then placed in a forced air drying machine, 100℃ vulcanization 12h, finally placed at room temperature for 5 days, to obtain a polyurethane elastomer.

[0040] Comparative Example 2

[0041] Dry 100 mmol polytetrahydrofuran ether glycol, 280 mmol toluene-2, 4-diisocyanate were mixed, reacted at 70℃ for 3h, then the material was placed in a preheated mold (mold temperature was 110℃), and 4 mmol of 4-(4-hydroxyphenyl)-2, 3-phthalazin-1-one was added as a chain extender, 0.12 mmol of catalyst stannous octoate, stirred and mixed, 120℃ hot curing 1h, then placed in a forced air drying machine, 100℃ vulcanization 12h, finally placed at room temperature for 5 days, to obtain a polyurethane elastomer.

[0042] The polyurethane elastomer was made into a sample of 1cm x 1cm x 0.5cm, placed in a thermal gravimetric analyzer, nitrogen as the test atmosphere, from 20℃ to 800℃, to test the initial thermal decomposition temperature (5% mass loss number) and the carbon residue.

[0043] The polyurethane elastomer was made into a sample of 10cm x 10cm x 0.2cm, placed in a cone calorimeter for testing, the heat radiation power was 35kW / m 2 .

[0044] The test results are shown in Table 2.

[0045] Table 2 Thermal properties and flame retardant properties of polyurethane elastomer

[0046] The present application uses phosphate phthalazinone as a diamine chain extender for polyurethane, introduces a high-thermal-stability double-phthalazinone rigid fused ring structure into the polyurethane molecular chain, significantly improves the thermal decomposition temperature of the polyurethane elastomer, reaching 323.1-339.8℃, and has good high-temperature resistance. And the phosphate double-phthalazinone chain extender contains a phosphate flame retardant structure, and the phthalazinone nitrogen heterocycle forms a nitrogen-phosphorus halogen-free flame retardant, which decomposes at high temperature to generate oxygen-containing phosphoric acid and nitrogen and other non-combustible gases, can promote the dehydration and carbonization of the polyurethane elastomer, and form a carbon layer structure on the surface of the elastomer with heat and oxygen insulation, which can reduce the high-temperature decomposition rate of the polymer, and has a condensed state flame retardant effect, thereby reducing the total heat release and heat release rate peak of the polyurethane elastomer, and showing excellent flame retardant performance.​

[0047] Comparative Example 1 uses ordinary p-phenylenediamine as a chain extender of the polyurethane elastomer, which does not contain the high-thermal-stability phthalazinone rigid condensed ring structure and the phosphate flame-retardant structure, and does not form a nitrogen-phosphorus halogen-free flame retardant, and the thermal decomposition temperature of the polyurethane elastomer is low, and the high-temperature resistance and flame retardance are poor.

[0048] Comparative Example 2 uses 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one as a chain extender, which contains the high-thermal-stability phthalazinone rigid condensed ring structure, and the thermal decomposition temperature is significantly higher than that of Comparative Example 1. However, compared with Examples 1-3, the 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one contains only one phthalazinone structure, while the phosphate phthalazinone chain extender of the Examples contains a double phthalazinone structure, resulting in that the thermal decomposition temperature of the polyurethane elastomer of Comparative Example 2 is lower than that of Examples 1-3, and the 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one does not contain the phosphate flame-retardant structure, and cannot form a nitrogen-phosphorus halogen-free flame retardant, and the total heat release and the peak heat release rate of the polyurethane elastomer are large, and the flame retardance is poor.

[0049] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form. It should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A halogen-free flame-retardant polyurethane elastomer, characterized in that, The halogen-free flame-retardant polyurethane elastomer comprises the following raw materials: polyether polyol, toluene-2,4-diisocyanate, phosphate bisphthalazinone chain extender, and catalyst, and the molar ratio is 1:(2.4-2.8):(0.04-0.12):(0.0012-0.0017). The structural formula of the phosphate ester phthalazinone chain extender is formula (I):

2. The halogen-free flame retardant polyurethane elastomer according to claim 1, wherein, The polyether polyol is any one of polyethylene glycol, polytetrahydrofuran ether glycol, and polypropylene glycol.

3. The halogen-free flame retardant polyurethane elastomer according to claim 1, wherein, The catalyst is stannous octoate or dibutyltin dilaurate.

4. The halogen-free flame retardant polyurethane elastomer according to claim 1, wherein, The preparation process of the phosphate bisphthalazinone chain extender comprises the following steps: Step (1) under an ice water bath, phenyl dichlorophosphate, 4-(4-hydroxyphenyl)-2,3-diazine(4-nitrobenzene)naphthalene-1-ketone, and pyridine are added into toluene, and after reaction, filtration is performed, the filtrate is distilled under reduced pressure, washed, and dried to obtain intermediate 1; Step (2) hydrazine hydrate, intermediate 1, and Pd / C catalyst are added into ethanol, and after mixing, reaction is performed, distillation is performed under reduced pressure, the product is washed with petroleum ether, then dissolved into toluene, and precipitate is obtained by evaporation and concentration, and filtration is performed to obtain the phosphate bisphthalazinone chain extender.

5. The halogen-free flame retardant polyurethane elastomer according to claim 4, wherein, In step (1), the molar ratio of phenyl dichlorophosphate, 4-(4-hydroxyphenyl)-2,3-diazine(4-nitrobenzene)naphthalene-1-ketone, and pyridine is 1:(2.3-2.8):(3.2-4).

6. The halogen-free flame retardant polyurethane elastomer according to claim 4, wherein, In step (1), the reaction is performed at a temperature of 30-45℃ for 18-36h.

7. The halogen-free flame retardant polyurethane elastomer according to claim 4, wherein In step (2), the mass ratio of intermediate 1 and Pd / C catalyst is 1:(0.12-0.16).

8. The halogen-free flame retardant polyurethane elastomer according to claim 4, wherein, In step (2), the reaction is performed at a temperature of 70-75℃ for 12-15h.

9. A process for the preparation of a halogen-free flame-retardant polyurethane elastomer as claimed in any one of claims 1 to 8, characterized in that, The dry polyether polyol and toluene-2,4-diisocyanate are mixed, and reaction is performed at 70-75℃ for 2-3h, then the material is placed in a preheated mold, and the phosphate bisphthalazinone chain extender and the catalyst are added, stirred and uniformly mixed, hot cured at 110-120℃ for 1-2h, then placed in a forced air drying machine, vulcanized at 100-110℃ for 12-18h, and finally placed at room temperature for 5-7 days to obtain the halogen-free flame-retardant polyurethane elastomer.

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