Polyurethane flame retardant foam and preparation method thereof

Abstract

The present invention discloses a polyurethane flame-retardant foam and a preparation method thereof. The method comprises: preparing a mixture of components A and B, wherein the component B mixture is prepared from an isocyanate-terminated prepolymer and an antioxidant; and the component A mixture is prepared from a hydroxyl-terminated prepolymer, a small molecule chain extender, a composite catalyst, silicone oil, a foam stabilizer, a flame retardant, and water; mixing the components A and B at a mass ratio of 0.9 to 1.1 under high-speed stirring; and performing a foaming process through a double-sided shaping step to form the foam. The polyurethane flame-retardant foam of the present invention features rapid molding at normal pressure, generates no toxic gases during the production process, exhibits good process stability, and has a substrate with excellent flame retardant and smoke suppression properties and a high elastic recovery rate. The foam can be used as a gasket, cushioning material, or filling material in electronic devices such as mobile phones and tablet computers, as well as in the automotive field.

Description

Technical Field

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

[0002] Polyurethane foam is ubiquitous in modern society. It's often found wherever padding / cushioning is needed, making it widely used in mattresses, upholstered furniture, car seats, baby carriers, and seats for public transportation (buses, airlines, and trains). This new material technology originated in the United States, and its primary production is by foreign companies. Domestically, China relies heavily on imported finished foam to meet production needs, making the development and manufacture of high-performance cushioning foam particularly important.

[0003] As a porous polymer material, polyurethane foam contains a large number of combustible hydrocarbon segments and voids in its structure, which also makes it highly flammable. There are also great safety risks when used in the new energy vehicle industry and the electronics industry. Ammonium polyphosphate, as a phosphorus-based flame retardant material, has a high nitrogen and phosphorus content and low cost. After being ionically bonded to chitosan, it forms an expanding flame retardant system, which can greatly improve the flame retardant efficiency of the matrix. In addition, some of the hydroxyl groups contained in chitosan can also react with polyurethane, improving the dispersion and stability of the flame retardant in the matrix. At the same time, chitosan also has a certain antibacterial effect, which reduces the growth and reproduction of bacteria on the foam. With the acceleration of the localization process of polyurethane foam, it is of great significance to develop high-performance flame retardant foam by adding modified ammonium polyphosphate and metal smoke suppressants. Summary of the Invention

[0004] Based on the above situation, the present invention proposes a polyurethane flame retardant foam and a preparation method thereof, which can effectively solve the above problems.

[0005] The purpose of the present invention is to provide a polyurethane flame retardant foam, which solves the problem of balancing physical properties and flame retardant functionality encountered in existing foam products in the automotive seat, electronics industry, etc.

[0006] The technical solutions of the present invention are as follows:

[0007] A polyurethane flame retardant foam is prepared from a mixture of components A and B. The mixture of component B is composed of the following parts by mass:

[0008] 200-250 parts of isocyanate-terminated prepolymer;

[0009] 2-5 parts of antioxidant;

[0010] The mixture of component A is composed of the following parts by mass:

[0011]

[0012] Mixture A and mixture B are stirred and mixed at a mass ratio of 0.9 to 1.1 at a high speed; and foaming treatment is performed through a double-sided shaping process to form foam.

[0013] In a further embodiment, the isocyanate-terminated prepolymer is prepared from the following components in parts by mass:

[0014] 100-160 parts of carbodiimide-modified MDI;

[0015] 90-150 parts of polyoxypropylene glycol;

[0016] The carbodiimide-modified MDI is a diisocyanate with an NCO content of 28.8%. The polyoxypropylene glycol is one or a mixture of polyoxypropylene glycols having molecular weights of 1000, 1500, 2000, and 3000. The antioxidant is one or a mixture of two of antioxidant L57, antioxidant-SP, antioxidant 1135, and antioxidant AN6368.

[0017] In a further embodiment, the hydroxyl-terminated prepolymer is prepared from the following components in accordance with mass fractions:

[0018] 20-35 parts of toluene diisocyanate;

[0019] 40-90 parts of polyoxypropylene glycol;

[0020] 90-150 parts of polycarbonate diol;

[0021] The polyoxypropylene diol is one of polyoxypropylene diols with molecular weights of 1000, 1500, 2000 and 3000; the polycarbonate diol is one of polycarbonate diols with molecular weights of 500, 1000, 1500 and 2000, or a mixture of several of them.

[0022] In a further embodiment, the small molecule chain extender is any one of 1,4-butanediol, 1,3-propylene glycol and methylpropylene glycol.

[0023] In a further embodiment, the composite catalyst is a composite of an amine catalyst and a bismuth catalyst.

[0024] In a further embodiment, the foam stabilizer is any one of foam stabilizer C-08, foam stabilizer KD-550 and foam stabilizer CD-110, or a mixture of two of them.

[0025] In a further embodiment, the flame retardant is prepared from the following components in accordance with mass fractions:

[0026] 25-45 parts of modified ammonium polyphosphate;

[0027] 5-15 parts of metal smoke suppressant;

[0028] The modified ammonium polyphosphate is prepared from ammonium polyphosphate and low-viscosity chitosan; the particle sizes of the ammonium polyphosphate and chitosan are 1000-1500 mesh; the metal smoke suppressant is composed of any one or a mixture of two of ferrite, nickel hydroxide, aluminum hydroxide and magnesium hydroxide; the particle size of the metal smoke suppressant is 800-1000 mesh.

[0029] The present invention also provides a method for preparing a polyurethane flame-retardant foam, which comprises the following steps:

[0030] Preparation of component B mixture:

[0031] Preheat the reaction kettle to remove the moisture in the kettle and continuously introduce nitrogen, then add polypropylene glycol and continue stirring, and then put in carbodiimide-modified MDI and heat up to \(70^{\circ}C - 100^{\circ}C\), keep stirring at a constant temperature for 4-5h. After the content of -NCO group detected is controlled at \(10\% \lt m \lt 20\%\) by weight percentage and qualified, it can be obtained, and then an antioxidant is added.

[0032] Preparation of modified ammonium polyphosphate:

[0033] Under a nitrogen atmosphere, first pour low-viscosity chitosan into acetic acid aqueous solution and stir evenly slowly, then add the aqueous solution of ammonium polyphosphate into it, gradually heat up to \(60 - 90^{\circ}C\), and treat it through a condensation reflux device for 2-3h; after cooling to room temperature, the product can be obtained through operations such as filtration, ethanol water washing, drying, suction filtration, etc. The mass ratio of low-viscosity chitosan to ammonium polyphosphate is 1:4-6.

[0034] Preparation of component A mixture: [[ID=2|1]] [[ID=|2]]

[0035] Continuously introduce nitrogen into the reaction kettle, put toluene diisocyanate, polypropylene glycol and polycarbonate diol into the reaction kettle, heat up to \(75 - 95^{\circ}C\), stir for 1-2h, put in a composite catalyst and a small molecule chain extender, stop heating and continue stirring for 2-3 hours. After detecting that the water content is between 5000-9000ppm, then cool to room temperature and put in a composite catalyst, silicone oil, foam stabilizer, flame retardant and water, and keep stirring at a constant temperature for 1.5-2h to obtain component A, which is sealed and packaged for use.

[0036] The steps of synthesizing the foam from component A and component B mixtures include:

[0037] The solvent-free component A and component B mixtures with a mass fraction ratio of 0.9-1.1 are fully mixed by a casting machine and then cast on a transparent heat-insulating film. A soft ruler with a thickness of 0.4-1mm is used to fit the release paper and placed in an oven at \(100 - 130^{\circ}C\) to be dried until foaming is complete. After peeling off the release paper, the flame-retardant foam can be obtained.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] The present invention provides a polyurethane flame-retardant foam and a preparation method thereof. Polyols and isocyanates of varying molecular weights are selected as raw materials to synthesize a prepolymer with a specific structure. A hydroxyl-containing component A and a terminal NCO-containing component B are rapidly mixed to prepare the polyurethane flame-retardant foam. This avoids the implosion and formation of numerous byproducts that would result from direct mixing of the raw materials. Furthermore, a composite catalyst is used to adjust the reaction time at each stage, allowing the foaming reaction to proceed completely, thereby achieving the design of the high-performance foam of the present invention.

[0040] The present invention provides a flame-retardant polyurethane foam and a preparation method thereof. By selecting ammonium polyphosphate as a flame retardant and modifying the ammonium polyphosphate surface with chitosan, the modified ammonium polyphosphate improves its charring and flame retardancy in the foam. Furthermore, the active hydroxyl groups contained in the chitosan react with the polyurethane, improving its stability in the foam. Furthermore, by compounding the polyurethane foam with a metal smoke suppressant, the flame retardancy and smoke suppression effects are further enhanced.

[0041] The polyurethane flame-retardant foam of the present invention has the characteristics of rapid molding under normal pressure, no toxic gas is generated during the production process, the process stability is good, the base material has excellent flame-retardant and smoke-suppressing effects, and the elastic recovery rate is high. It can be used as a pad, cushioning material, and filling material in electronic devices such as mobile phones and tablet computers and in the automotive field. DETAILED DESCRIPTION

[0042] The present invention is further described below with reference to specific embodiments. Obviously, the embodiments described are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] Unless otherwise specified in the examples, all parts mentioned are parts by mass.

[0044] Example 1

[0045] A polyurethane flame retardant foam is prepared from a mixture of components A and B. The mixture of component B is composed of the following mass fractions:

[0046] 225 parts of isocyanate-terminated prepolymer;

[0047] 3 parts antioxidant;

[0048] The mixture of component A is composed of the following mass fractions:

[0049]

[0050]

[0051] Mixture A and mixture B are stirred and mixed at a mass ratio of 0.9 at high speed; foaming treatment is performed through a double-sided shaping process to form foam with a foam thickness of 0.5 mm.

[0052] The isocyanate-terminated prepolymer is prepared from the following components in accordance with mass fractions:

[0053] 125 parts of carbodiimide-modified MDI;

[0054] 100 parts of polyoxypropylene glycol;

[0055] The carbodiimide-modified MDI used was a diisocyanate with an NCO content of 28.8% from Wanhua Chemical. The polyoxypropylene glycol used was a 2000 molecular weight polyoxypropylene glycol produced by Shanghai Donghui Chemical Technology Co., Ltd. The antioxidant used was Antioxidant 1135 from Suzhou Liangcai Chemical Co., Ltd.

[0056] The hydroxyl terminated prepolymer is prepared from the following components in accordance with the mass fraction:

[0057] 25 parts of toluene diisocyanate;

[0058] 50 parts of polyoxypropylene glycol;

[0059] 100 parts of polycarbonate diol;

[0060] The polyoxypropylene diol selected was polyoxypropylene diol products with molecular weights of 1000 and 500 produced by Shanghai Donghui Chemical Technology Co., Ltd., with a mass ratio of 1:3; the polycarbonate diol selected was polycarbonate diol product with a molecular weight of 2000 produced by Covestro Polymers Co., Ltd.

[0061] The small molecule chain extender is a mixture of 1,4-butanediol and 1,3-propylene glycol in a mass ratio of 2:1.

[0062] The composite catalyst is a mixture of bismuth catalyst BICAT 8108 produced by Jiaxing Hexin Technology Co., Ltd. and ammonium catalyst N513 in a mass ratio of 1:3.

[0063] The foam stabilizer selected is the foam stabilizer KD-550 produced by Hexin New Materials Co., Ltd.

[0064] The flame retardant is prepared from the following components according to mass fraction:

[0065] 30 parts of modified ammonium polyphosphate;

[0066] 10 parts of metal smoke suppressant;

[0067] The modified ammonium polyphosphate is prepared from ammonium polyphosphate with a mesh size of 1000 produced by Jinan Taixing Chemical Co., Ltd. and low-viscosity chitosan produced by Shanghai Aladdin Technology Co., Ltd.; the metal smoke suppressant is prepared by mixing ferrite with a mesh size of 800 and nickel hydroxide produced by Merck in a mass ratio of 1:1.

[0068] Its preparation method includes the following steps:

[0069] Preparation of component B mixture:

[0070] Preheat the reaction kettle to remove the moisture inside the kettle and continuously introduce nitrogen, then add polypropylene glycol and continue stirring, and then add carbodiimide-modified MDI and heat up to 85°C, stir at a constant temperature for 4 hours. After the detection value of the -NCO group content m is controlled within 10% < m < 20% by weight percentage and is qualified, it can be obtained, and then an antioxidant is added.

[0071] Preparation of modified ammonium polyphosphate:

[0072] Under a nitrogen atmosphere, first pour low-viscosity chitosan into acetic acid aqueous solution and stir evenly slowly, then add the aqueous solution of ammonium polyphosphate. The mass ratio of low-viscosity chitosan to ammonium polyphosphate is 1:5. Gradually heat up to 75°C and treat it through a condensation reflux device for 2 hours; after cooling to room temperature, the product is filtered, washed with ethanol and water, dried, and suction filtered to obtain the modified ammonium polyphosphate.

[0073] Preparation of component A mixture:

[0074] Continuously introduce nitrogen into the reaction kettle, put toluene diisocyanate, polypropylene glycol and polycarbonate diol into the reaction kettle, heat up to 85°C, stir for 2 hours, add a composite catalyst and a small molecule chain extender, stop heating and continue stirring for 2 hours. Detect that the moisture content is between 5000 - 9000 ppm, and then cool to room temperature and add a composite catalyst, silicone oil, foam stabilizer, flame retardant and water, and stir at a constant temperature for 2 hours to obtain component A, which is sealed and packaged for use.

[0075] The steps for synthesizing the foam from component A and component B mixtures include:

[0076] The solvent-free component A and component B mixtures with a mass fraction ratio of 0.9 are fully mixed by a casting machine and then cast on a transparent heat insulation film. Use a 0.5 mm thick soft ruler to fit the release paper and place it in an oven at 130°C to dry until foaming is complete. After peeling off the release paper, the flame-retardant foam can be obtained.

[0077] Example 2

[0078] A polyurethane flame-retardant foam is prepared from component A and component B mixtures. The mixture of component B is composed of the following mass fractions:

[0079] 225 parts of isocyanate-terminated prepolymer;

[0080] 3 parts antioxidant;

[0081] The mixture of component A is composed of the following mass fractions:

[0082]

[0083] Mixture A and mixture B are stirred and mixed at a mass ratio of 0.9 at a high speed; foaming treatment is performed through a double-sided shaping process to form foam with a foam thickness of 0.4 mm.

[0084] The isocyanate-terminated prepolymer is prepared from the following components in accordance with mass fractions:

[0085] 125 parts of carbodiimide-modified MDI;

[0086] 100 parts of polyoxypropylene glycol;

[0087] The carbodiimide-modified MDI used was a diisocyanate with an NCO content of 28.8% from Wanhua Chemical. The polyoxypropylene glycol used was a 2000 molecular weight polyoxypropylene glycol produced by Shanghai Donghui Chemical Technology Co., Ltd. The antioxidant used was Antioxidant 1135 from Suzhou Liangcai Chemical Co., Ltd.

[0088] The hydroxyl terminated prepolymer is prepared from the following components in accordance with the mass fraction:

[0089] 25 parts of toluene diisocyanate;

[0090] 50 parts of polyoxypropylene glycol;

[0091] 100 parts of polycarbonate diol;

[0092] The polyoxypropylene diol selected was polyoxypropylene diol products with molecular weights of 1000 and 500 produced by Shanghai Donghui Chemical Technology Co., Ltd., with a mass ratio of 1:3; the polycarbonate diol selected was polycarbonate diol product with a molecular weight of 2000 produced by Covestro Polymers Co., Ltd.

[0093] The small molecule chain extender is a mixture of 1,4-butanediol and 1,3-propylene glycol in a mass ratio of 2:1.

[0094] The composite catalyst is a mixture of bismuth catalyst BICAT 8108 produced by Jiaxing Hexin Technology Co., Ltd. and ammonium catalyst N513 in a mass ratio of 1:3.

[0095] The foam stabilizer selected is the foam stabilizer KD-550 produced by Hexin New Materials Co., Ltd.

[0096] The flame retardant is prepared from the following components according to mass fraction:

[0097] 40 parts of modified ammonium polyphosphate;

[0098] The modified ammonium polyphosphate is prepared from ammonium polyphosphate with 1000 meshes produced by Jinan Taixing Chemical Co., Ltd. and low-viscosity chitosan produced by Shanghai Aladdin Technology Co., Ltd.

[0099] Its preparation method includes the following steps:

[0100] Preparation of B-component mixture:

[0101] Preheat the reaction kettle to remove the moisture in the kettle and continuously introduce nitrogen, then add polypropylene glycol and continue stirring, and then put in carbodiimide-modified MDI and heat up to 85 °C, stir at a constant temperature for 4 h. After the detection value content m of -NCO group is controlled within 10% < m < 20% by weight percentage and is qualified, it can be obtained, and then an antioxidant is added.

[0102] Preparation of modified ammonium polyphosphate

[0103] Under a nitrogen atmosphere, first pour low-viscosity chitosan into acetic acid aqueous solution and stir evenly slowly, then add the aqueous solution of ammonium polyphosphate into it. The mass ratio of low-viscosity chitosan to ammonium polyphosphate is 1:5. Gradually heat up to 75 °C and treat it with a condensation reflux device for 2 h; after cooling to room temperature, the product can be obtained by operations such as filtration, ethanol water washing, drying, and suction filtration to obtain the modified ammonium polyphosphate.

[0104] Preparation of A-component mixture:

[0105] Continuously introduce nitrogen into the reaction kettle, put toluene diisocyanate, polypropylene glycol, and polycarbonate diol into the reaction kettle, heat up to 85 °C, stir for 2 h, put in a composite catalyst and a small molecule chain extender, stop heating and continue stirring for 2 hours. Detect that the moisture content is between 5000 - 9000 ppm, and then cool to room temperature and put in a composite catalyst, silicone oil, foam stabilizer, flame retardant, and water, and stir at a constant temperature for 2 h to obtain component A, which is sealed and packaged for use.

[0106] The steps for synthesizing foam from A and B component mixtures include:

[0107] The solvent-free A and B component mixtures with a mass fraction ratio of 0.9 are fully mixed by a pouring machine and then poured onto a transparent heat-insulating film. Use a 0.5 mm thick soft ruler to fit the release paper and place it in an oven at 130 °C to dry until foaming is complete. After peeling off the release paper, the flame-retardant foam can be obtained.

[0108] Example 3

[0109] A polyurethane flame-retardant foam, which is prepared from A and B component mixtures. The mixture of component B is composed of the following mass fractions:

[0110] 225 parts of isocyanate-terminated prepolymer;

[0111] 3 parts antioxidant;

[0112] The mixture of component A is composed of the following mass fractions:

[0113]

[0114] Mixture A and mixture B are stirred and mixed at a mass ratio of 0.9 at high speed; foaming treatment is performed through a double-sided shaping process to form foam with a foam thickness of 0.5 mm.

[0115] The isocyanate-terminated prepolymer is prepared from the following components in accordance with mass fractions:

[0116] 125 parts of carbodiimide-modified MDI;

[0117] 100 parts of polyoxypropylene glycol;

[0118] The carbodiimide-modified MDI was a diisocyanate with an NCO content of 28.8% from Wanhua Chemical. The polyoxypropylene glycol was a polyoxypropylene glycol with a molecular weight of 2000 produced by Shanghai Donghui Chemical Technology Co., Ltd. The antioxidant was antioxidant 1135 produced by Suzhou Liangcai Chemical Co., Ltd.

[0119] The hydroxyl terminated prepolymer is prepared from the following components in accordance with the mass fraction:

[0120] 25 parts of toluene diisocyanate;

[0121] 50 parts of polyoxypropylene glycol;

[0122] 100 parts of polycarbonate diol;

[0123] The polyoxypropylene diol selected was polyoxypropylene diol products with molecular weights of 1000 and 500 produced by Shanghai Donghui Chemical Technology Co., Ltd., with a mass ratio of 1:3; the polycarbonate diol selected was polycarbonate diol product with a molecular weight of 2000 produced by Covestro Polymers Co., Ltd.

[0124] The small molecule chain extender is a mixture of 1,4-butanediol and 1,3-propylene glycol in a mass ratio of 2:1.

[0125] The composite catalyst is a mixture of bismuth catalyst BICAT 8108 produced by Jiaxing Hexin Technology Co., Ltd. and ammonium catalyst N513 in a mass ratio of 1:3.

[0126] The foam stabilizer selected is the foam stabilizer KD-550 produced by Hexin New Materials Co., Ltd.

[0127] The flame retardant is prepared from the following components according to the mass fraction:

[0128] 40 parts of metal smoke suppressant;

[0129] The metal smoke suppressant is a mixture of 800-mesh ferrite and nickel hydroxide produced by Merck in a mass ratio of 1:1.

[0130] Its preparation method includes the following steps:

[0131] Preparation of component B mixture:

[0132] Preheat the reaction kettle to remove the moisture in the kettle and continuously introduce nitrogen, then add polyoxypropylene glycol and continue stirring, and then put in MDI modified by carbodiimide and heat up to 85°C, stir at a constant temperature for 4 hours. After the detection value of -NCO group content m is controlled within 10% < m < 20% by weight percentage and qualified, it can be obtained, and then an antioxidant is added.

[0133] Preparation of component A mixture:

[0134] Continuously introduce nitrogen into the reaction kettle, put toluene diisocyanate, polyoxypropylene glycol and polycarbonate diol into the reaction kettle, heat up to 85°C, stir for 2 hours, put in a composite catalyst and a small molecule chain extender, stop heating and continue stirring for 2 hours. After detecting that the moisture content is between 5000 - 9000 ppm, then cool to room temperature and put in a composite catalyst, silicone oil, foam stabilizer, flame retardant and water, and stir at a constant temperature for 2 hours to obtain component A, which is sealed and packaged for use.

[0135] The steps of synthesizing foam from component A and component B mixtures include:

[0136] The solvent-free component A and component B mixtures with a mass fraction ratio of 0.9 are fully mixed by a pouring machine and then poured onto a transparent heat insulation film. Use a 0.5-mm-thick soft ruler to fit the release paper and place it in an oven at 130°C to dry until foaming is complete. After peeling off the release paper, the flame-retardant foam can be obtained.

[0137] Example 4

[0138] A polyurethane flame-retardant foam, which is prepared from component A and component B mixtures. The mixture of component B is composed of the following mass fractions:

[0139] 225 parts of isocyanate-terminated prepolymer;

[0140] 3 parts of antioxidant;

[0141] The mixture of component A is composed of the following mass fractions:

[0142]

[0143] Mixture A and mixture B are stirred and mixed at a mass ratio of 0.9 at high speed; foaming treatment is performed through a double-sided shaping process to form foam with a foam thickness of 0.5 mm.

[0144] The isocyanate-terminated prepolymer is prepared from the following components in accordance with mass fractions:

[0145] 125 parts of carbodiimide-modified MDI;

[0146] 100 parts of polyoxypropylene glycol;

[0147] The carbodiimide-modified MDI used was a diisocyanate with an NCO content of 28.8% from Wanhua Chemical. The polyoxypropylene glycol used was a 2000 molecular weight polyoxypropylene glycol produced by Shanghai Donghui Chemical Technology Co., Ltd. The antioxidant used was Antioxidant 1135 from Suzhou Liangcai Chemical Co., Ltd.

[0148] The hydroxyl terminated prepolymer is prepared from the following components in accordance with the mass fraction:

[0149] 25 parts of toluene diisocyanate;

[0150] 50 parts of polyoxypropylene glycol;

[0151] 100 parts of polycarbonate diol;

[0152] The polyoxypropylene diol selected was polyoxypropylene diol products with molecular weights of 1000 and 500 produced by Shanghai Donghui Chemical Technology Co., Ltd., with a mass ratio of 1:3; the polycarbonate diol selected was polycarbonate diol product with a molecular weight of 2000 produced by Covestro Polymers Co., Ltd.

[0153] The small molecule chain extender is a mixture of 1,4-butanediol and 1,3-propylene glycol in a mass ratio of 2:1.

[0154] The composite catalyst is a mixture of bismuth catalyst BICAT 8108 produced by Jiaxing Hexin Technology Co., Ltd. and ammonium catalyst N513 in a mass ratio of 1:3.

[0155] The foam stabilizer selected is the foam stabilizer KD-550 produced by Hexin New Materials Co., Ltd.

[0156] The flame retardant is prepared from the following components according to mass fraction:

[0157] 30 parts of ammonium polyphosphate;

[0158] 10 parts of metal smoke suppressant;

[0159] Select ammonium polyphosphate with a mesh size of 1000 produced by Jinan Taixing Chemical Co., Ltd.; for the metal smoke suppressant, select ferrite with a mesh size of 800 and nickel hydroxide produced by Merck and mix them in a mass ratio of 1:1.

[0160] Its preparation method includes the following steps:

[0161] Preparation of the B-component mixture:

[0162] Preheat the reaction kettle to remove the moisture inside the kettle and continuously introduce nitrogen, then add polypropylene glycol and continue stirring, and then add carbodiimide-modified MDI and raise the temperature to 85°C, stir at a constant temperature for 4 hours. After the detection value of the -NCO group content m is controlled within 10% < m < 20% by weight percentage and is qualified, it can be obtained, and then an antioxidant is added.

[0163] Preparation of the A-component mixture:

[0164] Continuously introduce nitrogen into the reaction kettle, put toluene diisocyanate, polypropylene glycol and polycarbonate diol into the reaction kettle, raise the temperature to 85°C, stir for 2 hours, add a composite catalyst and a small molecule chain extender, stop heating and continue stirring for 2 hours. After detecting that the moisture content is between 5000 - 9000 ppm, then lower the temperature to room temperature and add a composite catalyst, silicone oil, foam stabilizer, flame retardant and water, and stir at a constant temperature for 2 hours to obtain the A component, which is then sealed and packaged for use.

[0165] The steps for synthesizing the foam from the A and B component mixtures include:

[0166] The solvent-free A and B component mixtures with a mass fraction ratio of 0.9 are fully mixed by a pouring machine and then poured onto a transparent heat-insulating film. Use a 0.5 mm thick soft ruler to attach the release paper and place it in an oven at​​​​​​​​​​​​​​​​​​​​​​

[0174] The isocyanate-terminated prepolymer is prepared from the following components by mass fraction:

[0175] 125 parts of carbodiimide-modified MDI;

[0176] 100 parts of polypropylene glycol;

[0177] The carbodiimide-modified MDI selects the diisocyanate with an NCO content of 28.8% from Wanhua Chemical; the polypropylene glycol selects the polypropylene glycol product with a molecular weight of 2000 produced by Shanghai Donghui Chemical Technology Co., Ltd. The antioxidant selects the antioxidant 1135 product from Suzhou Liangcai Chemical Co., Ltd.

[0178] The hydroxyl-terminated prepolymer is prepared from the following components by mass fraction:

[0179] 25 parts of toluene diisocyanate;

[0180] 50 parts of polypropylene glycol;

[0181] 100 parts of polycarbonate diol;

[0182] The polypropylene glycol selects the polypropylene glycol products with molecular weights of 1000 and 500 produced by Shanghai Donghui Chemical Technology Co., Ltd., and the mass ratio is 1:3; the polycarbonate diol selects the polycarbonate diol product with a molecular weight of 2000 produced by Covestro Polymer Co., Ltd.

[0183] The small molecule chain extender is a mixture of 1,4-butanediol and 1,3-propanediol in a mass ratio of 2:1.

[0184] The composite catalyst is a mixture of the bismuth catalyst BICAT 8108 product and the ammonium catalyst N513 produced by Jiaxing Hexin Technology Co., Ltd. in a mass ratio of 1:3.

[0185] The foam stabilizer selects the foam stabilizer KD-550 produced by Hexin New Materials Co., Ltd.

[0186] Its preparation method includes the following steps:

[0187] Preparation of Component B mixture:

[0188] Preheat the reaction kettle to remove the moisture in the kettle and continuously introduce nitrogen, then add polypropylene glycol and continue stirring, and then put in carbodiimide-modified MDI and heat up to 85°C, stir at a constant temperature for 4 hours, and it can be obtained after the detection value content m of the -NCO group is controlled within 10% < m < 20% by weight percentage, and then add the antioxidant.

[0189] Preparation of Component A mixture:

[0190] Continuously introduce nitrogen into the reactor, add toluene diisocyanate, polyoxypropylene glycol and polycarbonate diol into the reactor, raise the temperature to 85°C, stir for 2 hours, add the composite catalyst and small molecule chain extender, stop heating and continue stirring for 2 hours, detect the moisture content between 5000-9000ppm, then cool to room temperature, add the composite catalyst, silicone oil, foam stabilizer and water, stir at constant temperature for 2 hours to obtain component A, and seal and package for use.

[0191] The steps of synthesizing foam from the mixture of components A and B include:

[0192] The solvent-free A and B component mixture with a mass fraction ratio of 0.9 is fully mixed in a pouring machine and poured onto a transparent thermal insulation film. A 0.5 mm thick soft ruler is used to stick the release paper to the mixture and the mixture is placed in a 130°C oven to dry for complete foaming. The foam can be obtained after peeling off the release paper.

[0193] In order to better demonstrate the benefits of the present invention, the performance of the polyurethane flame retardant foams obtained in Examples 1 to 4 of the present invention and the polyurethane foam obtained in the comparative example were tested. The test results are shown in Table 1 below:

[0194] Table 1

[0195]

[0196] Note: Product density is tested according to the method specified in GB / T 6343; 25% indentation hardness is tested according to the method specified in 5.4 of GB / T 10802-2006; rebound rate is tested according to 5.6 of GB / T 10802-2006; flame retardancy is tested according to GB 8410-2006, Combustion Characteristics of Automotive Interior Materials; the minimum oxygen concentration sufficient to sustain combustion is recorded and expressed as the Limiting Oxygen Index. Evaluation and judgment of test results are conducted according to 8.3 of GB / T 2406.2-2009.

[0197] As shown in the table above, the polyurethane flame-retardant foam prepared using the present invention exhibits good resilience and flame retardancy, with slightly improved product density and 25% indentation hardness. Compared to the comparative example, the flame retardancy ratings of the examples of the present invention are generally higher, indicating that after flame-retardant modification, the modified ammonium polyphosphate is well integrated with the polyurethane. Combined with the metal smoke suppressant and chitosan carbonizing agent, the flame retardancy is improved while the mechanical properties remain significantly unchanged.

[0198] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A polyurethane flame retardant foam, characterized in that: Made from Mixing Agent A and Mixing Agent B: The Mixing Agent B is composed of the following components by mass parts: Isocyanate-terminated prepolymer 200 - 250 parts; Antioxidant 2 - 5 parts; The Mixing Agent A is composed of the following components by mass parts: Hydroxyl-terminated prepolymer 150 - 220 parts; Low-molecular-weight chain extender 30 - 45 parts; Compound catalyst 3 - 6 parts; Silicone oil 1 - 3 parts; Foam stabilizer 1 - 3 parts; Flame retardant 30 - 50 parts; Water 0.5 - 1.5 parts; The flame retardant is prepared from the following components by mass fraction: Modified ammonium polyphosphate 25 - 45 parts; Metal smoke suppressant 5 - 15 parts; The modified ammonium polyphosphate is prepared from ammonium polyphosphate and chitosan; The metal smoke suppressant is composed of any one or a mixture of two of ferrite, nickel hydroxide, aluminum hydroxide, and magnesium hydroxide.

2. The polyurethane flame retardant foam according to claim 1, characterized in that: The isocyanate-terminated prepolymer is prepared from the following components by mass parts: Carbodiimide-modified MDI 100 - 160 parts; Polyoxypropylene glycol 90 - 150 parts; The polyoxypropylene glycol is one or a mixture of several polyoxypropylene glycols with a molecular weight of 1000 - 3000.

3. The polyurethane flame retardant foam according to claim 1, characterized in that: The antioxidant is a mixture of any one or several of antioxidant L-57, antioxidant - SP, antioxidant 1135, and antioxidant AN6368.

4. The polyurethane flame retardant foam according to claim 1, characterized in that: The hydroxyl-terminated prepolymer is prepared from the following components by mass parts: Toluene diisocyanate 20 - 35 parts; Polyoxypropylene glycol 40 - 90 parts; Polycarbonate diol 90 - 150 parts; The polyoxypropylene glycol is one of the polyoxypropylene glycols with a molecular weight of 1000 - 3000; The polycarbonate diol is one or a mixture of several polycarbonate diols with a molecular weight of 500 - 2000.

5. The polyurethane flame retardant foam according to claim 1, characterized in that: The low-molecular-weight chain extender is one of 1,4-butanediol, 1,3-butanediol, and methylpropanediol; the compound catalyst is a compound of an amine catalyst and a bismuth catalyst; the foam stabilizer is any one or a mixture of two of foam stabilizer C-08, foam stabilizer KD-550, and foam stabilizer CD-110.

6. The polyurethane flame retardant foam according to claim 5, characterized in that: The preparation of the modified ammonium polyphosphate includes: Under a nitrogen atmosphere, first pour chitosan into an acetic acid aqueous solution and stir evenly slowly, then add an aqueous solution of ammonium polyphosphate into it, gradually heat up to 60 - 90 °C, treat it with a condensing reflux device for 2 - 3 h, and after cooling to room temperature, the product can be obtained after post-treatment to get the modified ammonium polyphosphate.

7. The method for preparing the polyurethane flame retardant foam according to any one of claims 1 to 6, characterized in that: Including the following steps: Mixing Agent A and Mixing Agent B are stirred and mixed at a mass ratio of 0.9 - 1.1, and foaming treatment is carried out to form a foam, obtaining a polyurethane flame-retardant foam.

8. The method for preparing the polyurethane flame retardant foam according to claim 7, characterized in that: The preparation of the Mixing Agent B specifically includes: Preheat the reaction kettle to remove the moisture in the kettle and continuously introduce nitrogen, then add polyoxypropylene glycol and continue to stir, and then put in carbodiimide-modified MDI and heat up to 70 °C - 100 °C, stir constantly at a constant temperature for 4 - 5 h. After the detection value content m of the -NCO group is controlled within 10% < m < 20% by weight percentage and is qualified, it can be obtained, and then add the antioxidant.

9. The method for preparing the polyurethane flame retardant foam according to claim 7, characterized in that: The preparation of the Mixing Agent A specifically includes: Continuously introduce nitrogen into the reactor, add toluene diisocyanate, polyoxypropylene glycol and polycarbonate diol into the reactor, raise the temperature to 75-95°C, stir for 1-2 hours, add the composite catalyst and small molecule chain extender, stop heating and continue stirring for 2-3 hours, detect the moisture content between 5000-9000ppm, then cool down and add the composite catalyst, silicone oil, foam stabilizer, flame retardant and water, and stir at a constant temperature for 1.5-2 hours to obtain mixture A.

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