Polyurethane foam plastic and preparation method and application thereof

Abstract

The present invention belongs to the technical field of polymer organic materials, and specifically relates to a polyurethane foam plastic and its preparation method and application. The present invention provides a polyurethane foam plastic, comprising the following raw materials in parts by weight: 100 parts of polyurethane; 5-15 parts of composite flame retardant; 10-25 parts of foaming agent; 2-5 parts of lubricant; 0.1-1 parts of curing agent; 1-5 parts of binder; 0.5-1 parts of nanofiller; the composite flame retardant is phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether. The present invention greatly improves the flame retardant properties of the foam plastic by adding a composite flame retardant without affecting the mechanical properties of the polyurethane foam plastic. In addition, the inventors found that phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether have a synergistic effect in improving the flame retardant properties of the foam plastic.

Description

Technical Field

[0001] The invention belongs to the technical field of macromolecular organic materials, and in particular relates to a polyurethane foam plastic and a preparation method and application thereof. Background Art

[0002] Foam plastics are a type of polymer material formed by a large number of gas micropores dispersed in solid plastics. They have the characteristics of light weight, heat insulation, sound absorption, shock absorption, and better dielectric properties than base resins. They are widely used. Almost all kinds of plastics can be made into foam plastics, and foaming has become an important field in plastic processing.

[0003] Polyurethane foam is made by polymerization of isocyanate and hydroxyl compounds. It can be divided into two categories according to its hardness: soft and hard, of which soft is the main variety. Generally speaking, it has excellent elasticity, softness, elongation and compression strength; good chemical stability, resistance to many solvents and oils; excellent wear resistance, 20 times greater than natural sponge; and excellent processability, thermal insulation, adhesion and other properties. It is a high-performance cushioning material, but the price is relatively high.

[0004] The prior art discloses a method for preparing flame-retardant polyurethane foam plastics, which uses reactive nitrogen-containing polyether to replace part of additive flame retardants, thereby reducing the deficiencies of additive technology while maintaining the flame retardant effect.

[0005] However, replacing part of the additive flame retardant by reactive nitrogen-containing polyether does not significantly improve the flame retardant properties of polyurethane foam. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that the flame retardant properties of polyurethane foam plastics are not significantly improved by replacing part of the additive flame retardant with reactive nitrogen-containing polyether, thereby providing a polyurethane foam plastic and a preparation method and application thereof.

[0007] To this end, the present invention provides the following technical solutions:

[0008] The present invention provides a polyurethane foam plastic, comprising the following raw materials in parts by weight:

[0009] 100 parts of polyurethane;

[0010] 5-15 parts of composite flame retardant;

[0011] 10-25 parts of foaming agent;

[0012] 2-5 parts of lubricant;

[0013] Curing agent 0.1-1 part;

[0014] 1-5 parts of binder;

[0015] Nano filler 0.5-1 part;

[0016] The composite flame retardant is phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether.

[0017] Optionally, the mass ratio of phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether is (5-15): (5-15): (5-15): (1-5).

[0018] Optionally, the nanofiller is a nanocarbon material;

[0019] The nano-carbon material includes one or more of carbon nanotubes and nano-graphene.

[0020] Optionally, the foaming agent includes at least one of n-pentane, n-hexane, petroleum ether and chloroform;

[0021] And / or, the lubricant includes at least one of calcium stearate and magnesium stearate.

[0022] Optionally, the curing agent is ethylene glycol;

[0023] And / or, the adhesive is epoxy resin.

[0024] The present invention also provides a method for preparing the polyurethane foam plastic, comprising the following steps:

[0025] S1: mixing polyurethane, foaming agent, lubricant, binder and nanofiller and then performing ultrasonic dispersion to obtain a mixture;

[0026] S2: adding the composite flame retardant into the mixture at a rate of 5-10 mL / min and stirring, then foaming, and then adding a curing agent for curing to obtain a polyurethane foam plastic.

[0027] Optionally, in step S2, the composite flame retardant is added in an environment of protective gas;

[0028] The protective gas includes one or more of nitrogen, helium and argon.

[0029] Optionally, in step S1, the ultrasonic dispersion time is 5-10 min;

[0030] And / or, after the ultrasonic dispersion, the viscosity of the mixture is 3000-5000 Pa·s.

[0031] Optionally, in step S2, the curing time is 10-15 hours;

[0032] And / or, the curing temperature is 100-120°C.

[0033] The invention also provides an application of the polyurethane foam plastic in the exterior wall of a building.

[0034] The technical solution provided by the present invention has the following advantages:

[0035] 1. The present invention provides a polyurethane foam plastic, comprising the following raw materials in parts by weight: 100 parts of polyurethane; 5-15 parts of composite flame retardant; 10-25 parts of foaming agent; 2-5 parts of lubricant; 0.1-1 parts of curing agent; 1-5 parts of binder; 0.5-1 parts of nanofiller; the composite flame retardant is phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether. The present invention greatly improves the flame retardant properties of the polyurethane foam plastic by adding the composite flame retardant without affecting the mechanical properties of the polyurethane foam plastic. In addition, the inventors found that phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether have a synergistic effect in improving the flame retardant properties of the foam plastic.

[0036] 2. The content of nitrogen-containing polyether added to the polyurethane foam provided by the present invention needs to be strictly controlled. If the content of nitrogen-containing polyether is too high, although the flame retardant properties of the foam will be slightly improved, the mechanical properties of the foam will be reduced. If the content of nitrogen-containing polyether is too low, the flame retardant properties of the foam will not be significantly improved.

[0037] 3. The present invention also provides a method for preparing the above-mentioned polyurethane foam, comprising the following steps: S1: mixing polyurethane, foaming agent, lubricant, binder, and nanofiller and then ultrasonically dispersing to obtain a mixture; S2: adding a composite flame retardant to the mixture at a rate of 5-10 mL / min and stirring, then foaming, and then adding a curing agent for curing to obtain a polyurethane foam. In the present invention, the composite flame retardant is slowly added to the mixture and stirred, so that the composite flame retardant and the mixture are mixed more evenly, thereby improving the flame retardant properties of the foam. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0039] The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters of the following embodiments that do not specify specific conditions are usually based on conventional conditions.

[0040] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0041] In the present invention, unless otherwise specified and / or described, all numerical values ​​involving the amounts of components are "parts by weight" from beginning to end. The process parameters in the following examples without specifying specific conditions are usually based on conventional conditions.

[0042] Example 1

[0043] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0044] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0045] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0046] Example 2

[0047] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0048] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0049] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3.5 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligophosphazene and 0.5 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0050] Example 3

[0051] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0052] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0053] S2: Under a nitrogen atmosphere, 10.5 kg of a composite flame retardant (2.5 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 2 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0054] Example 4

[0055] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0056] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0057] S2: Under a nitrogen atmosphere, 10.5 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 2.5 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 2 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0058] Example 5

[0059] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0060] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0061] S2: Under a nitrogen atmosphere, 10.5 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 2.5 kg of cyclic oligophosphazene and 2 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0062] Example 6

[0063] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0064] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0065] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligophosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 7 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0066] Example 7

[0067] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0068] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0069] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 8 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0070] Example 8

[0071] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0072] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0073] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 9 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0074] Example 9

[0075] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0076] S1: 100 kg of polyurethane, 15 kg of petroleum ether, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0077] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0078] Example 10

[0079] This embodiment provides a method for preparing polyurethane foam plastics, comprising the following steps:

[0080] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 8 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0081] S2: 10 kg of composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligomeric phosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed, and then 0.5 kg of ethylene glycol was added and cured at 110° C. for 12 hours to obtain a polyurethane foam.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0084] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0085] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3.5 kg of phosphorus pentoxide, 3.5 kg of propylene oxide, and 3 kg of cyclic oligomeric phosphazene) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0086] Comparative Example 2

[0087] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0088] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0089] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (2 kg of phosphorus pentoxide, 2 kg of propylene oxide, 2 kg of cyclic oligophosphazene and 4 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0090] Comparative Example 3

[0091] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0092] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0093] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3.5 kg of phosphorus pentoxide, 3.2 kg of propylene oxide, 3.2 kg of cyclic oligophosphazene and 0.1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0094] Comparative Example 4

[0095] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0096] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0097] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (3 kg of phosphorus pentoxide, 3 kg of propylene oxide, 3 kg of cyclic oligophosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 L / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0098] Comparative Example 5

[0099] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0100] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0101] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (4.5 kg of propylene oxide, 4.5 kg of cyclic oligophosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0102] Comparative Example 6

[0103] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0104] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0105] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (4.5 kg of phosphorus pentoxide, 4.5 kg of cyclic oligophosphazene and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0106] Comparative Example 7

[0107] This comparative example provides a method for preparing a polyurethane foam, comprising the following steps:

[0108] S1: 100 kg of polyurethane, 15 kg of n-pentane, 3 kg of calcium stearate, 2 kg of epoxy resin and 1 kg of carbon nanotubes were ultrasonically dispersed for 10 min to obtain a mixture with a viscosity of 4000 Pa·s;

[0109] S2: Under a nitrogen atmosphere, 10 kg of a composite flame retardant (4.5 kg of phosphorus pentoxide, 4.5 kg of propylene oxide and 1 kg of nitrogen-containing polyether) was added to the mixture at a rate of 6 mL / min while stirring, and then foamed. 0.5 kg of ethylene glycol was added and cured at 110°C for 12 hours to obtain a polyurethane foam.

[0110] Test Case

[0111] The polyurethane foams prepared in Examples 1-10 and Comparative Examples 1-7 were subjected to performance tests, and the performance test indicators included the flame retardancy of the foams and the impact strength of the foams.

[0112] Test method for flame retardant properties: Test according to the test method in GB / T 10801.1-2021.

[0113] The combustion performance classification standard is evaluated according to the 4 combustion performance grades in GB8624. The specific standards are as follows:

[0114] Combustion performance grade name A non-combustible materials B1 Flame retardant materials B2 Combustible materials B3 Flammable Materials

[0115] The test method for impact strength is: test according to the test method in GB / T13525-92.

[0116] The specific test results are shown in the following table:

[0117]

[0118]

[0119] It can be seen from the above table that the addition of composite flame retardant greatly improves the flame retardant properties of polyurethane foam without affecting the mechanical properties of polyurethane foam. Phosphorus pentoxide, propylene oxide, cyclic oligophosphazene and nitrogen-containing polyether have a synergistic effect in improving the flame retardant properties of foam. If the content of nitrogen-containing polyether is too high, although it will slightly improve the flame retardant properties of foam, it will reduce the mechanical properties of foam. If the content of nitrogen-containing polyether is too low, the flame retardant properties of foam will not be significantly improved. Slowly adding the composite flame retardant to the mixture and stirring it can make the composite flame retardant and the mixture mix more evenly, thereby improving the flame retardant properties of foam.

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A polyurethane foam plastic, characterized in that: It includes the following raw materials in parts by weight: 100 parts of polyurethane; 5-15 parts of composite flame retardant; 10-25 parts of foaming agent; 2-5 parts of lubricant; Curing agent 0.1-1 part; 1-5 parts of binder; Nano filler 0.5-1 part; The composite flame retardant is phosphorus pentoxide, propylene oxide, cyclic oligomeric phosphazene and nitrogen-containing polyether; Wherein, the mass ratio of phosphorus pentoxide, propylene oxide, cyclic oligophosphazene and nitrogen-containing polyether is (5-15): (5-15): (5-15): (1-5); The foaming agent includes at least one of n-pentane, n-hexane, petroleum ether and chloroform; The polyurethane foam is prepared by the following preparation method: S1: mixing polyurethane, foaming agent, lubricant, binder and nanofiller and then performing ultrasonic dispersion to obtain a mixture; S2: adding the composite flame retardant into the mixture at a rate of 5-10 mL / min and stirring, then foaming, and then adding a curing agent for curing to obtain a polyurethane foam plastic.

2. The polyurethane foam according to claim 1, characterized in that The nano filler is a nano carbon material; The nano-carbon material includes one or more of carbon nanotubes and nano-graphene.

3. The polyurethane foam according to claim 1, characterized in that The lubricant includes at least one of calcium stearate and magnesium stearate.

4. The polyurethane foam according to claim 1, characterized in that The curing agent is ethylene glycol; And / or, the adhesive is epoxy resin.

5. A method for preparing the polyurethane foam according to any one of claims 1 to 4, comprising the following steps: S1: mixing polyurethane, foaming agent, lubricant, binder and nanofiller and then performing ultrasonic dispersion to obtain a mixture; S2: adding the composite flame retardant into the mixture at a rate of 5-10 mL / min and stirring, then foaming, and then adding a curing agent for curing to obtain a polyurethane foam plastic.

6. The method for preparing polyurethane foam according to claim 5, characterized in that: In step S2, the composite flame retardant is added in an environment of protective gas; The protective gas includes one or more of nitrogen, helium and argon.

7. The method for preparing polyurethane foam according to claim 5, characterized in that: In step S1, the ultrasonic dispersion time is 5-10 min; And / or, after the ultrasonic dispersion, the viscosity of the mixture is 3000-5000 Pa·s.

8. The method for preparing polyurethane foam according to claim 5, characterized in that: In step S2, the curing time is 10-15h; And / or, the curing temperature is 100-120°C.

9. Use of the polyurethane foam plastic according to any one of claims 1 to 4 in building exterior walls.

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