Flame retardant polyurethane material and preparation method thereof

Abstract

The present invention discloses a flame retardant polyurethane material and a preparation method thereof. The preparation method of the flame retardant polyurethane material comprises the following steps: (1) surface modifying mica stone with a silane coupling agent, dispersing the obtained surface modified mica stone and imidazole in a solvent, adding zinc salt, reacting, and obtaining a synergistic flame retardant; (2) mixing and reacting the synergistic flame retardant with ammonium polyphosphate, isocyanate, and polyol, adding a chain extender and a catalyst, mixing, and obtaining a flame retardant polyurethane material. The flame retardant polyurethane material of the present invention uses ammonium polyphosphate as a main flame retardant and a synergistic flame retardant prepared from mica stone as an auxiliary flame retardant, and the flame retardant effect is greatly improved, which effectively solves the problems of large addition amount and low flame retardant efficiency of traditional additive flame retardants, avoids affecting the mechanical properties of the material, and is a green, environmentally friendly and efficient halogen-free flame retardant material.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant materials, and in particular to a flame retardant polyurethane material and a preparation method thereof. Background Art

[0002] Polyurethane is an organic polymer with the advantages of high mechanical strength, good elasticity, oil resistance and low temperature resistance. It is widely used in the fields of automobiles, building materials and cable sheaths. However, polyurethane is a flammable material. The limiting oxygen index (LOI) of ordinary polyurethane is very low, generally around 18%, which is very easy to cause combustion. At the same time, the combustion process is accompanied by the release of heat and smoke, and the dripping of molten droplets can easily cause secondary combustion. In order to solve the above problems, polyurethane is generally made flame retardant by adding flame retardants. Specifically, flame retardants are added in the process of synthesizing polymers by physical incorporation. The flame retardants usually added are halogen-containing, phosphorus-nitrogen compounds, aluminum hydroxide, magnesium hydroxide, and mica. These flame retardants are added in large amounts, are easy to precipitate, have poor compatibility with polyurethane, and affect the mechanical properties of the material. Summary of the invention

[0003] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a flame retardant polyurethane material and a preparation method thereof.

[0004] Another object of the present invention is to provide a method for preparing the flame retardant polyurethane material.

[0005] The purpose of the present invention is achieved by the following technical solution: A method for preparing a flame retardant polyurethane material comprises the following steps:

[0006] (1) using a silane coupling agent to modify the surface of mica, dispersing the obtained surface-modified mica and imidazole in a solvent, adding zinc salt, reacting, and obtaining a synergistic flame retardant;

[0007] (2) The synergistic flame retardant is mixed with ammonium polyphosphate, isocyanate and polyol to react, and a chain extender and a catalyst are added and mixed to obtain a flame retardant polyurethane material.

[0008] Preferably, the silane coupling agent in step (1) is at least one of KH550, KH560, KH570, KH792, DL602, DL171, A-1100, Z-6011 and KBM-903.

[0009] Preferably, the particle size of the mica in step (1) is 3-5 μm.

[0010] Preferably, the mass ratio of the silane coupling agent to mica in step (1) is 1:1-1.5.

[0011] Preferably, the surface modification in step (1) uses alcohol as solvent; more preferably, the solvent is ethanol.

[0012] Preferably, the surface modification method in step (1) is: ultrasonically dispersing the raw material in a solvent, stirring the reaction at 25-120° C. for 1-12 hours, washing with the solvent, filtering, and drying to obtain surface-modified mica.

[0013] Preferably, in step (1), the mass ratio of the surface-modified mica, imidazole and zinc salt is 1:1-2:0.5-1.

[0014] Preferably, the imidazole in step (1) is 2-methylimidazole.

[0015] Preferably, the zinc salt in step (1) is at least one of zinc nitrate hexahydrate and zinc acetate.

[0016] Preferably, the solvent in step (1) is an organic alcohol; more preferably, the solvent in step (1) is methanol.

[0017] Preferably, the reaction after adding the zinc salt in step (1) is stirred at 30-50° C. for 2-8 hours.

[0018] Preferably, the synergistic flame retardant in step (1) is washed with a reaction solvent, dried and then subjected to subsequent reaction.

[0019] Preferably, the isocyanate in step (2) is at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI) and hexamethylene diisocyanate (HDI).

[0020] Preferably, the polyol in step (2) is at least one of polyester polyol and polyether polyol.

[0021] Preferably, the chain extender in step (2) is 1,4-butanediol.

[0022] Preferably, the catalyst in step (2) is dibutyltin dilaurate.

[0023] Preferably, in step (2), the mass ratio of the synergistic flame retardant, ammonium polyphosphate, isocyanate and polyol is 1-5:4-10:15-20:70-80.

[0024] Preferably, the amounts of the chain extender and catalyst used in step (2) are 3wt%-7wt% and 0.1wt%-0.5wt% of the total mass of the reactants, respectively.

[0025] Preferably, the reaction in step (2) is carried out under a nitrogen atmosphere.

[0026] A flame retardant polyurethane material is prepared by the above preparation method. The flame retardant polyurethane material of the invention can play a flame retardant role in both gas phase and condensed phase, can be cracked to generate phosphoric acid molecules during combustion, and can capture free radicals required for the combustion reaction; can dehydrate and carbonize the polymer to avoid the generation of combustible gas, and at the same time form a coke layer on the surface of the burning fabric to isolate the combustion environment.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The flame-retardant polyurethane material of the present invention is prepared with ammonium polyphosphate as the main flame retardant and the synergistic flame retardant prepared from mica as the auxiliary flame retardant, and the flame retardant effect is greatly improved, which effectively solves the problems of large addition amount and low flame retardant efficiency of traditional additive flame retardants, avoids affecting the mechanical properties of the material, and is a green, environmentally friendly and efficient halogen-free flame retardant material.

[0029] 2. The flame retardant polyurethane material of the present invention can regulate the flame retardant properties of the polyurethane material by controlling the ratio of ammonium polyphosphate and the synergistic flame retardant. The operation is flexible and convenient, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the infrared spectrum of the flame retardant polyurethane material prepared in Example 1. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] 1. Add 20g of silane coupling agent KH-55030g to 75% ethanol solution, ultrasonicate for 10min, then add 25g of mica with a particle size of 5μm and ultrasonicate for 15min, stir at 80℃ for 6h, wash with 75% ethanol solution, filter, and dry at 50℃ to obtain surface modified mica.

[0034] 2. Add 25 g of surface modified mica and 30 g of 2-methylimidazole to 500 ml of methanol and stir ultrasonically for 1 hour. Then add 25 g of zinc nitrate hexahydrate to the above solution, stir at 50°C for 3 hours, wash and filter with methanol, and dry at 50°C to obtain a synergistic flame retardant.

[0035] 3. Add 200g of polybutylene adipate to a three-necked flask, remove water at 110°C for 2h, then cool to 75°C, add 50g of toluene diisocyanate, react for 2h under nitrogen atmosphere, add 15g of ammonium polyphosphate and 5g of synergistic flame retardant, stir for 1h and remove bubbles in vacuum. Then add 17g of chain extender 1,4-butanediol and 0.7g of dibutyltin dilaurate, stir for 1min to mix evenly, and obtain flame-retardant polyurethane material. Cast the material on a flat vulcanizer at 110°C, keep it at a pressure of 10MPa for 30min for compression molding, cool to room temperature, and obtain flame-retardant polyurethane (isocyanate index is 1.04) sheet.

[0036] The infrared spectrum of the flame retardant polyurethane material of this embodiment is as follows Figure 1 As shown, at 1540cm -1 NH deformation at 3332cm -1 NH stretching vibration at 1732 cm -1 The C=O stretching vibrations at 1235 cm -1 The P=O stretching vibration peak near 1070cm -1 and 880cm -1 The nearby PO symmetric and antisymmetric stretching vibration peaks both appear in the infrared spectrum of the flame-retardant polyurethane material.

[0037] Example 2

[0038] 1. Add 20g of silane coupling agent KH-55030g to 75% ethanol solution, ultrasonicate for 10min, then add 20g of mica with a particle size of 3μm and ultrasonicate for 15min, stir at 80℃ for 6h, wash with 75% ethanol solution, filter, and dry at 50℃ to obtain surface modified mica.

[0039] 2. Add 20 g of surface modified mica and 20 g of 2-methylimidazole to 500 ml of methanol and stir ultrasonically for 1 hour. Then add 16 g of zinc nitrate hexahydrate to the above solution, stir at 40°C for 4 hours, wash and filter with methanol, and dry at 50°C to obtain a synergistic flame retardant.

[0040] 3. Add 200g of polybutylene adipate to a three-necked flask and remove water at 110°C for 2h. Then cool to 75°C, add 40g of toluene diisocyanate, react for 2h under nitrogen atmosphere, add 15g of ammonium polyphosphate and 10g of synergistic flame retardant, stir for 1h and then remove bubbles in vacuum. Then add 17g of chain extender 1,4-butanediol and 0.7g of dibutyltin dilaurate, stir for 1min to mix evenly, and obtain a flame-retardant polyurethane material. The flame-retardant polyurethane material is cast in a flat vulcanizer at 110°C, maintained at a pressure of 10MPa for 30min for compression molding, cooled to room temperature, and a flame-retardant polyurethane (isocyanate index is 1.02) sheet is obtained.

[0041] Example 3

[0042] 1. Add 20g of silane coupling agent KH-55030g to 75% ethanol solution, ultrasonicate for 10min, then add 22g of mica with a particle size of 3μm and ultrasonicate for 15min, stir at 80℃ for 6h, wash with 75% ethanol solution, filter, and dry at 50℃ to obtain surface modified mica.

[0043] 2. Add 22 g of surface modified mica and 24 g of 2-methylimidazole into 500 ml of methanol and stir ultrasonically for 1 h. Then add 20 g of zinc nitrate hexahydrate into the above solution, stir at 30 ° C for 5 h, wash and filter with methanol, and dry at 50 ° C to obtain mica ZIF-8 synergistic flame retardant.

[0044] 3. Add 200g of polybutylene adipate to a three-necked flask and remove water at 110°C for 2h. Then cool to 75°C, add 44g of toluene diisocyanate, react for 2h under nitrogen atmosphere, add 15g of ammonium polyphosphate and 15g of synergistic flame retardant, stir for 1h and remove bubbles in vacuum. Then add 17g of chain extender 1,4-butanediol and 0.7g of dibutyltin dilaurate, stir for 1min to mix evenly, and obtain a flame-retardant polyurethane material. The flame-retardant polyurethane material is cast in a flat vulcanizer at 110°C, maintained at a pressure of 10MPa for 30min for compression molding, cooled to room temperature, and a flame-retardant polyurethane (isocyanate index is 0.98) sheet is obtained.

[0045] Comparative Example 1

[0046] 200g of polybutylene adipate was added to a three-necked flask, and water was removed at 110°C for 2h, then the temperature was lowered to 75°C, 50g of toluene diisocyanate was added, and the reaction was carried out under a nitrogen atmosphere for 2h, and then 20g of ammonium polyphosphate was added and stirred for 1h and then vacuum defoamed. Then 17g of chain extender 1,4-butanediol and 0.7g of dibutyltin dilaurate were added, and the mixture was stirred for 1min to obtain a flame-retardant polyurethane material. The material was cast in a flat vulcanizer at 110°C, and kept at a pressure of 10MPa for 30min for compression molding, and cooled to room temperature to obtain a flame-retardant polyurethane (isocyanate index of 1.04) sheet.

[0047] Comparative Example 2

[0048] 200g of polybutylene adipate was added to a three-necked flask, and water was removed at 110°C for 2h, then the temperature was lowered to 75°C, 50g of toluene diisocyanate was added, and after reacting for 2h under a nitrogen atmosphere, 20g of the synergistic flame retardant prepared in Example 1 was added, and vacuum defoaming was performed after stirring for 1h. Then 17g of chain extender 1,4-butanediol and 0.7g of dibutyltin dilaurate were added, and the mixture was stirred for 1min to obtain a flame-retardant polyurethane material. The material was cast in a flat vulcanizer at 110°C, maintained at a pressure of 10MPa for 30min for compression molding, and cooled to room temperature to obtain a flame-retardant polyurethane (isocyanate index of 1.04) sheet.

[0049] Performance Testing

[0050] The flame retardant polyurethane sheets of Examples 1-3 and Comparative Examples 1 and 2 were tested for tensile modulus and elongation at break according to GB / T 528-2009, for fire rating (vertical burning, UL-94 V-0 evaluation method) according to GB / T 2408-2021, and for limiting oxygen index (LOI) according to GB / T 2406.2-2008.

[0051] Table 1 Test results

[0052]

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a flame retardant polyurethane material, characterized in that: The following steps are involved: (1) ultrasonically dispersing a silane coupling agent and mica in a solvent, stirring and reacting at 25-120° C. for 1-12 hours, washing with solvent, filtering, and drying to obtain surface-modified mica, dispersing the obtained surface-modified mica and imidazole in a solvent, adding zinc salt, reacting, and obtaining a synergistic flame retardant; (2) mixing the synergistic flame retardant with ammonium polyphosphate, isocyanate and polyol and reacting them, adding a chain extender and a catalyst, and mixing them to obtain a flame retardant polyurethane material; The mass ratio of the silane coupling agent to mica in step (1) is 1:1-1.5; In step (1), the mass ratio of the surface-modified mica, imidazole and zinc salt is 1:1-2:0.5-1; In step (2), the mass ratio of the synergistic flame retardant, ammonium polyphosphate, isocyanate and polyol is 1-5:4-10:15-20:70-80.

2. The method for preparing the flame retardant polyurethane material according to claim 1, characterized in that: Include at least one of the following: The silane coupling agent in step (1) is at least one of KH550, KH560, KH570, KH792, DL602, DL171, A-1100, Z-6011 and KBM-903; The particle size of the mica in step (1) is 3-5 μm.

3. The method for preparing the flame retardant polyurethane material according to claim 1, characterized in that: Include at least one of the following: The imidazole in step (1) is 2-methylimidazole; The zinc salt in step (1) is at least one of zinc nitrate hexahydrate and zinc acetate; The solvent in step (1) is an organic alcohol.

4. The method for preparing the flame retardant polyurethane material according to claim 1, characterized in that: Include at least one of the following: The isocyanate in step (2) is at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; The polyol in step (2) is at least one of polyester polyol and polyether polyol.

5. The method for preparing the flame retardant polyurethane material according to claim 1, characterized in that: Include at least one of the following: The chain extender in step (2) is 1,4-butanediol; The catalyst in step (2) is dibutyltin dilaurate.

6. The method for preparing the flame retardant polyurethane material according to claim 1, characterized in that: The amounts of the chain extender and catalyst used in step (2) are 3wt%-7wt% and 0.1wt%-0.5wt% of the total mass of the reactants, respectively.

7. A flame retardant polyurethane material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 6.

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