Polyurethane modified composite coating with bulletproof and explosion-proof functions and preparation method thereof

Abstract

The invention discloses a polyurethane modified composite coating with bulletproof and explosion-proof functions and a preparation method thereof, and relates to the technical field of coatings. The preparation method comprises the following steps: carrying out chemical reaction on diisocyanate containing benzene rings and polyester polyol to obtain a polyurethane prepolymer; the preparation method comprises the following steps: carrying out chemical reaction on diisocyanate containing a benzene ring and diamine to obtain a polyurea prepolymer; carrying out chemical reaction on the polyurethane prepolymer and the polyurea prepolymer to obtain a polyurethane-polyurea composite polymer; and finally, compounding the polyurethane-polyurea composite polymer, ultra-high molecular weight polyethylene fibers, the polyurethane-modified silicon carbide whisker shear thickening liquid and an auxiliary agent to prepare the polyurethane modified composite coating with bulletproof and explosion-proof functions. The polyurethane modified composite coating has excellent bulletproof and explosion-proof functions, and has wide and potential application prospects.

Description

Technical Field

[0001] The present application relates to the technical field of coatings, and in particular to a polyurethane modified composite coating with bulletproof and explosion-proof functions and a preparation method thereof. Background Art

[0002] With the rapid development of modern industrial technology, demand for bulletproof and explosion-resistant materials is growing in applications such as military equipment, public safety facilities, and transportation. Traditional bulletproof and explosion-resistant materials, often made of metal alloys, ceramics, or single polymers, offer some degree of protection but suffer from drawbacks such as heavy weight, poor flexibility, and insufficient resistance to multiple impacts. Furthermore, single-material systems are insufficient to meet current demands for explosion and bulletproof protection, necessitating breakthroughs in performance through material composites and structural optimization.

[0003] For example, Chinese patent application CN116218338A discloses a ballistic and explosion-proof coating and its preparation method. The coating comprises: 40-50 parts by weight of polyurea resin, 1-3 parts by weight of a dispersing agent, 1-2 parts by weight of an anti-settling agent; 20-35 parts by weight of a ballistic filler; 1-3 parts by weight of a defoaming agent; 10-20 parts by weight of a coloring pigment; and 20-30 parts by weight of a modified curing agent. The molecular weight of the polyurea resin is adjusted to 30,000-50,000. However, the coating produced by this technical solution simply physically combines a single reinforcing phase with a matrix and lacks a multi-scale synergistic reinforcement mechanism. Therefore, its ballistic and explosion-proof performance still has significant room for improvement. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this application provides a polyurethane-modified composite coating with bulletproof and explosion-proof properties and its preparation method. The process involves chemically reacting a benzene-ring-containing diisocyanate with a polyester polyol to produce a polyurethane prepolymer; chemically reacting the benzene-ring-containing diisocyanate with a diamine to produce a polyurea prepolymer; then chemically reacting the polyurethane prepolymer with a polyurea prepolymer to produce a polyurethane-polyurea composite polymer; and finally, compounding the polyurethane-polyurea composite polymer with ultra-high molecular weight polyethylene fibers, a polyurethane-modified silicon carbide whisker shear thickening fluid, and additives to produce a polyurethane-modified composite coating with bulletproof and explosion-proof properties.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a polyurethane-modified composite coating with bulletproof and explosion-proof functions, comprising a polyurethane-polyurea composite polymer, ultra-high molecular weight polyethylene fibers, a polyurethane-modified silicon carbide whisker shear thickening liquid, and an additive; the polyurethane-polyurea composite polymer is obtained by a chemical reaction between a polyurethane prepolymer and a polyurea prepolymer; the polyurethane prepolymer is obtained by a chemical reaction between a diisocyanate containing a benzene ring and a polyester polyol; and the polyurea prepolymer is obtained by a chemical reaction between a diisocyanate containing a benzene ring and a diamine.

[0007] In a second aspect, the present application provides a method for preparing a polyurethane modified composite coating having bulletproof and explosion-proof functions, comprising the following steps:

[0008] Add silicon carbide whiskers into a stirrer, and add isocyanate silane coupling agent dropwise into the stirrer while stirring under nitrogen protection;

[0009] After the isocyanate silane coupling agent is added, stirring is continued for 5 to 10 minutes, and the mixture is dried at 80 to 100° C. for 2 to 4 hours under nitrogen protection to obtain modified silicon carbide whiskers, which are then sealed for later use.

[0010] Add polyurethane to xylene, stir and dissolve at 50-60°C to obtain a mixed solution, add the sealed modified silicon carbide whiskers, and stir for 10-30 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening solution;

[0011] DMF, benzene ring-containing diisocyanate, polyester polyol and organotin catalyst are added to a reactor, and stirred at 60-90° C. for 1-3 hours under nitrogen protection to obtain a polyurethane prepolymer;

[0012] DMF, benzene ring-containing diisocyanate and diamine are added to a reaction kettle, and stirred and reacted at 40-60°C for 20-40 minutes under nitrogen protection to obtain a polyurea prepolymer;

[0013] Putting polyurethane prepolymer, polyurea prepolymer and organotin catalyst into a reactor, stirring and reacting at 50-80° C. for 5-8 hours under nitrogen protection to obtain a polyurethane-polyurea composite polymer;

[0014] Ultra-high molecular weight polyethylene fiber, polyurethane-modified silicon carbide whisker shear thickening liquid, dispersant, flame retardant and toughening agent are added to the polyurethane-polyurea composite polymer, stirred at 45-60°C for 30-60 minutes under nitrogen protection, then the leveling agent and stabilizer are added in sequence, and finally the defoaming agent is added, and stirring is continued for 10-20 minutes to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0015] Beneficial technical effects:

[0016] In the polyurethane-modified composite coating with bulletproof and explosion-proof functions prepared in this application, the polyurethane prepolymer and the polyurea prepolymer obtained by the reaction further undergo a chemical reaction between isocyanate groups and hydroxyl groups to produce a polyurethane-polyurea composite polymer whose molecular chain contains both a rigid network of rigid groups such as benzene rings and urea groups and a flexible carbon chain derived from polyester polyols and long carbon chain diamines. Using this polyurethane-polyurea composite polymer as the matrix of the composite coating gives the composite coating excellent mechanical properties. When subjected to bullet or explosion impact, it can absorb energy through deformation and resist penetration and crack propagation through the rigid network, thus having excellent bulletproof and explosion-proof functions. The polyurethane-modified silicon carbide whisker shear thickening liquid allows the composite coating to quickly trigger the shear thickening effect when subjected to high-speed impact, rapidly hardening to resist penetration. Moreover, in the polyurethane-modified silicon carbide whisker shear thickening fluid, the isocyanate-silane coupling agent-modified silicon carbide whiskers contain a large number of isocyanate groups, which can improve the interfacial compatibility between the inorganic whiskers and the organic matrix on the one hand; on the other hand, they can further react with the amino or hydroxyl groups in the polyurethane-polyurea composite polymer to form strong chemical bonds. In addition, the polyurethane component in it also promotes the compatibility of the inorganic whiskers with the organic matrix due to the principle of like compatibility; therefore, the composite coating can reduce stress concentration and prevent interfacial debonding of the components. In summary, the polyurethane-modified silicon carbide whisker shear thickening fluid and the polyurethane-polyurea composite polymer matrix work synergistically, thereby further enhancing the bulletproof and explosion-proof functions of the prepared composite coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the preparation process of polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0018] Figure 2 Schematic diagram of the chemical reactions occurring during the preparation of the composite coating. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the following examples. However, this should not be construed as limiting the scope of this application to the following examples. Without departing from the above-mentioned method concepts of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0020] In this application, the terms used in this application are for the purpose of describing specific embodiments only and are not intended to be limiting of the application.

[0021] As used in this application, the singular forms "a," "an," "any," "one," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0022] In addition, if the terms "first" and "second" appear in this application, they are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0023] In a first aspect, the present application provides a polyurethane-modified composite coating with bulletproof and explosion-proof functions, comprising a polyurethane-polyurea composite polymer, ultra-high molecular weight polyethylene fibers, a polyurethane-modified silicon carbide whisker shear thickening liquid, and additives; the polyurethane-polyurea composite polymer is obtained by a chemical reaction between a polyurethane prepolymer and a polyurea prepolymer; the polyurethane prepolymer is obtained by a chemical reaction between a diisocyanate containing a benzene ring and a polyester polyol; the polyurea prepolymer is obtained by a chemical reaction between a diisocyanate containing a benzene ring and a diamine; the additives include a dispersant, a leveling agent, a defoaming agent, a stabilizer, a flame retardant, and a toughening agent.

[0024] In one feasible implementation scheme, in the polyurethane-modified silicon carbide whisker shear thickening fluid, the modified silicon carbide whisker is a silicon carbide whisker modified by an isocyanate silane coupling agent; the mass ratio of the silicon carbide whisker to the isocyanate silane coupling agent is (95-99): (1-5).

[0025] In one feasible embodiment, the isocyanate-based silane coupling agent includes any one of 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane and tris(3-trimethoxysilylpropyl)isocyanurate.

[0026] In terms of a feasible implementation scheme, the mass ratio of the polyurethane-polyurea composite polymer, ultra-high molecular weight polyethylene fiber, polyurethane-modified silicon carbide whisker shear thickening liquid, dispersant, leveling agent, defoaming agent, stabilizer, flame retardant and toughening agent is (40-60): (8-15): (15-25): (1-3): (1-2): (1-2): (1-2): (5-8): (3-5).

[0027] In one feasible embodiment, the dispersant includes any one of sodium polyacrylate, sodium polymethacrylate, sodium tripolyphosphate, sodium hexametaphosphate, oleic acid, stearic acid, alkylphenol polyoxyethylene ether phosphate, glyceryl monostearate, BYK-111 and BYK-190.

[0028] In one feasible embodiment, the leveling agent includes any one of polydimethylsiloxane, polyether-modified polydimethylsiloxane, and acrylic acid-ethyl acrylate copolymer.

[0029] In one feasible embodiment, the defoaming agent includes any one of dimethyl silicone oil, polyoxyethylene glyceryl ether and polyoxypropylene glyceryl ether.

[0030] In one feasible embodiment, the stabilizer includes any one of barium stearate, calcium stearate, zinc stearate, 2,6-di-tert-butyl-p-cresol, phenyl parahydroxybenzoate, dilauryl thiodipropionate, and triphenyl phosphite.

[0031] In one feasible embodiment, the flame retardant includes any one of aluminum hydroxide, magnesium hydroxide, triethyl phosphate, diphenyl phosphate, tricresyl phosphate, decabromodiphenyl ether and tetrabromobisphenol A.

[0032] In one feasible embodiment, the toughening agent includes any one of nitrile rubber, ethylene propylene rubber, chloroprene rubber, styrene butadiene rubber, SBS, SIS and TPU.

[0033] In one feasible embodiment, the benzene ring-containing diisocyanate includes any one of meta-xylylene diisocyanate, tetramethyl-meta-xylylene diisocyanate and diphenylmethane diisocyanate.

[0034] In one possible embodiment, the diamine includes any one of heptanediamine, decanediamine, 1,12-diaminododecane and 1,14-tetradecanediamine.

[0035] In a second aspect, the present application provides a method for preparing a polyurethane modified composite coating having bulletproof and explosion-proof functions, such as Figure 1 As shown, the following steps are included:

[0036] Add silicon carbide whiskers into a stirrer, and add isocyanate silane coupling agent dropwise into the stirrer while stirring under nitrogen protection;

[0037] After the addition of the isocyanate silane coupling agent is completed, stirring is continued for 5 to 10 minutes, and the mixture is dried at 80°C for 2 to 4 hours under nitrogen protection to obtain modified silicon carbide whiskers, which are then sealed for later use;

[0038] Add polyurethane to xylene, stir and dissolve at 50-60°C to obtain a mixed solution, add the sealed modified silicon carbide whiskers, and stir for 10-30 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening solution;

[0039] DMF, benzene ring-containing diisocyanate, polyester polyol and organotin catalyst are added to a reactor, and stirred at 60-90° C. for 1-3 hours under nitrogen protection to obtain a polyurethane prepolymer;

[0040] DMF, benzene ring-containing diisocyanate and diamine are added to a reaction kettle, and stirred and reacted at 40-60°C for 20-40 minutes under nitrogen protection to obtain a polyurea prepolymer;

[0041] Putting polyurethane prepolymer, polyurea prepolymer and organotin catalyst into a reactor, stirring and reacting at 50-80° C. for 5-8 hours under nitrogen protection to obtain a polyurethane-polyurea composite polymer;

[0042] Ultra-high molecular weight polyethylene fiber, polyurethane-modified silicon carbide whisker shear thickening liquid, dispersant, flame retardant and toughening agent are added to the polyurethane-polyurea composite polymer, stirred at 45-60°C for 30-60 minutes under nitrogen protection, then the leveling agent and stabilizer are added in sequence, and finally the defoaming agent is added, and stirring is continued for 10-20 minutes to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0043] In one feasible embodiment, in the process of preparing the polyurethane-modified silicon carbide whisker shear thickening fluid, the mass ratio of xylene, polyurethane and modified silicon carbide whisker is (30-50): (25-40): (15-30).

[0044] In one feasible embodiment, in the process of preparing the polyurethane prepolymer, the mass ratio of the DMF, benzene ring-containing diisocyanate, polyester polyol and organotin catalyst is (40-60): (10-20): (30-40): (0.1-0.5).

[0045] In one feasible embodiment, during the preparation of the polyurea prepolymer, the mass ratio of DMF, benzene ring-containing diisocyanate and diamine is (50-70): (20-40): (5-10).

[0046] In a feasible embodiment, in the process of preparing the polyurethane-polyurea composite polymer, the mass ratio of the polyurethane prepolymer, the polyurea prepolymer and the organotin catalyst is (62-74): (25-42): (0.1-0.5).

[0047] The following will describe in detail a polyurethane modified composite coating with bulletproof and explosion-proof functions and a preparation method thereof provided by the present application in combination with different embodiments.

[0048] Example 1:

[0049] like Figure 1 As shown, a method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0050] 1. Add 97g of silicon carbide whiskers to a blender and add 3g of 3-isocyanatepropyltrimethoxysilane dropwise to the blender while stirring under nitrogen protection.

[0051] 2. After the addition of 3-isocyanatepropyltrimethoxysilane, continue stirring for 8 minutes to obtain modified silicon carbide whiskers, dry them at 80°C under nitrogen protection for 3 hours, and seal them for later use;

[0052] 3. Add 35 g of polyurethane to 40 g of xylene, stir and dissolve at 55°C, then add 25 g of sealed modified silicon carbide whiskers and stir for 20 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0053] 4. Add 50 g of DMF, 15 g of m-xylylene diisocyanate, 34.8 g of polyester polyol and 0.2 g of organotin catalyst into a reactor, stir and react at 75 ° C under nitrogen protection for 2 hours to obtain a polyurethane prepolymer dispersion;

[0054] 5. Add 60g DMF, 30g m-xylylene diisocyanate and 10g heptylene diamine into the reactor, stir and react at 50°C for 30min under nitrogen protection to obtain a polyurea prepolymer dispersion;

[0055] 6. Add 70g of polyurethane prepolymer dispersion, 29.8g of polyurea prepolymer dispersion and 0.2g of organotin catalyst into the reactor, stir and react at 65°C for 6h under nitrogen protection to obtain a polyurethane-polyurea composite polymer; the reaction diagram of steps 4 to 6 is shown in the following figure: Figure 2 As shown;

[0056] 7. Add 10 g of ultra-high molecular weight polyethylene fiber, 24 g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2 g of sodium polymethacrylate, 6 g of triethyl phosphate and 4 g of ethylene propylene rubber to 50 g of polyurethane-polyurea composite polymer, stir at 50 ° C for 45 minutes under nitrogen protection, then add 1.5 g of polyether-modified polydimethylsiloxane and 1.5 g of zinc stearate in sequence, and finally add 1 g of polyoxyethylene glycerol ether, and continue stirring for 12 minutes to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0057] Example 2:

[0058] like Figure 1 As shown, a method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0059] 1. Add 95g of silicon carbide whiskers to a blender and add 5g of tris(3-trimethoxysilylpropyl)isocyanurate dropwise to the blender while stirring under nitrogen protection;

[0060] 2. After the addition of tris(3-trimethoxysilylpropyl)isocyanurate, continue stirring for 7 minutes to obtain modified silicon carbide whiskers, which are then dried at 90°C under nitrogen for 4 hours and sealed for later use;

[0061] 3. Add 40 g of polyurethane to 35 g of xylene, stir and dissolve at 60°C, then add 25 g of sealed modified silicon carbide whiskers and stir for 30 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0062] 4. Add 45 g of DMF, 18 g of diphenylmethane diisocyanate, 36.7 g of polyester polyol, and 0.3 g of an organotin catalyst into a reactor, and stir the mixture at 90° C. under nitrogen protection for 1 h to obtain a polyurethane prepolymer dispersion.

[0063] 5. Add 55 g of DMF, 35 g of diphenylmethane diisocyanate and 10 g of decanediamine to a reactor, stir and react at 60° C. under nitrogen protection for 20 min to obtain a polyurea prepolymer dispersion;

[0064] 6. Add 65 g of polyurethane prepolymer dispersion, 34.7 g of polyurea prepolymer dispersion and 0.3 g of organotin catalyst into a reactor, stir and react at 80° C. under nitrogen protection for 5 h to obtain a polyurethane-polyurea composite polymer;

[0065] 7. Add 12 g of ultra-high molecular weight polyethylene fiber, 22 g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2 g of glycerol monostearate, 7 g of decabromodiphenyl ether and 4 g of chloroprene rubber to 49 g of polyurethane-polyurea composite polymer, stir at 60 ° C for 30 minutes under nitrogen protection, then add 1 g of polydimethylsiloxane and 2 g of triphenyl phosphite in sequence, and finally add 1 g of dimethyl silicone oil, and continue stirring for 10 minutes to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0066] Example 3:

[0067] like Figure 1 As shown, a method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0068] 1. Add 98g of silicon carbide whiskers to a blender and add 2g of 3-isocyanatepropyltriethoxysilane dropwise to the blender while stirring under nitrogen protection.

[0069] 2. After the addition of 3-isocyanatepropyltriethoxysilane, continue stirring for 10 minutes to obtain modified silicon carbide whiskers, which are then dried at 100°C for 2 hours under nitrogen protection and sealed for later use;

[0070] 3. Add 30 g of polyurethane to 50 g of xylene, stir and dissolve at 50°C, then add 20 g of sealed modified silicon carbide whiskers and stir for 10 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0071] 4. Add 60 g of DMF, 12 g of tetramethyl-m-xylylene diisocyanate, 27.5 g of polyester polyol and 0.5 g of organotin catalyst into a reactor, stir and react at 60 ° C under nitrogen protection for 3 hours to obtain a polyurethane prepolymer dispersion;

[0072] 5. Add 70g DMF, 25g tetramethyl-m-xylylene diisocyanate and 5g 1,12-diaminododecane into the reactor, stir and react at 40°C under nitrogen protection for 40 minutes to obtain a polyurea prepolymer dispersion;

[0073] 6. Add 74 g of polyurethane prepolymer dispersion, 25.5 g of polyurea prepolymer dispersion and 0.5 g of organotin catalyst into a reactor, stir and react at 50° C. under nitrogen protection for 8 h to obtain a polyurethane-polyurea composite polymer;

[0074] 7. Add 8 g of ultra-high molecular weight polyethylene fiber, 15 g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2 g of alkylphenol polyoxyethylene ether phosphate, 5 g of tricresyl phosphate and 5 g of nitrile rubber to 60 g of polyurethane-polyurea composite polymer, stir at 45 ° C for 60 min under nitrogen protection, then add 2 g of acrylic acid-ethyl acrylate copolymer and 1 g of phenyl parahydroxybenzoate in sequence, and finally add 2 g of polyoxypropylene glycerol ether, and continue stirring for 20 min to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0075] Example 4:

[0076] like Figure 1 As shown, a method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0077] 1. Add 99g of silicon carbide whiskers to a blender and add 1g of tris(3-trimethoxysilylpropyl)isocyanurate dropwise to the blender while stirring under nitrogen protection;

[0078] 2. After the addition of tris(3-trimethoxysilylpropyl)isocyanurate, continue stirring for 5 minutes to obtain modified silicon carbide whiskers, which are then dried at 85°C under nitrogen protection for 4 hours and sealed for later use;

[0079] 3. Add 40 g of polyurethane to 30 g of xylene, stir and dissolve at 60°C, then add 30 g of sealed modified silicon carbide whiskers and stir for 30 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0080] 4. Add 40 g of DMF, 20 g of diphenylmethane diisocyanate, 39.9 g of polyester polyol and 0.1 g of an organotin catalyst into a reactor, and stir the mixture at 90° C. under nitrogen protection for 1 h to obtain a polyurethane prepolymer dispersion.

[0081] 5. Add 50g DMF, 40g diphenylmethane diisocyanate and 10g 1,14-tetradecanediamine into the reactor, stir and react at 60°C under nitrogen protection for 20min to obtain a polyurea prepolymer dispersion;

[0082] 6. Add 62 g of polyurethane prepolymer dispersion, 37.9 g of polyurea prepolymer dispersion and 0.1 g of organotin catalyst into a reactor, stir and react at 80° C. under nitrogen protection for 5 h to obtain a polyurethane-polyurea composite polymer;

[0083] 7. Add 15g of ultra-high molecular weight polyethylene fiber, 25g of polyurethane-modified silicon carbide whisker shear thickening liquid, 1g of sodium polyacrylate, 8g of aluminum hydroxide and 3g of styrene-butadiene rubber to 44g of polyurethane-polyurea composite polymer, stir at 60°C for 30min under nitrogen protection, then add 1g of polyether-modified polydimethylsiloxane and 2g of dilauryl thiodipropionate in sequence, and finally add 1g of polyoxyethylene glycerol ether, and continue stirring for 10min to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0084] Example 5:

[0085] like Figure 1 As shown, a method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0086] 1. Add 96g of silicon carbide whiskers to a blender and add 4g of 3-isocyanatepropyltrimethoxysilane dropwise to the blender while stirring under nitrogen protection.

[0087] 2. After the addition of 3-isocyanatepropyltrimethoxysilane, continue stirring for 9 minutes to obtain modified silicon carbide whiskers, which are then dried at 95°C under nitrogen for 3 hours and sealed for later use;

[0088] 3. Add 35 g of polyurethane to 45 g of xylene, stir and dissolve at 55°C, then add 20 g of sealed modified silicon carbide whiskers and stir for 25 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0089] 4. Add 55 g of DMF, 15 g of diphenylmethane diisocyanate, 29.8 g of polyester polyol, and 0.2 g of an organotin catalyst into a reactor, and stir the mixture at 80° C. under nitrogen for 2 h to obtain a polyurethane prepolymer dispersion.

[0090] 5. Add 65g DMF, 30g m-xylylene diisocyanate and 5g diamine into the reactor, stir and react at 50°C for 35min under nitrogen protection to obtain a polyurea prepolymer dispersion;

[0091] 6. Add 68 g of polyurethane prepolymer dispersion, 31.9 g of polyurea prepolymer dispersion and 0.1 g of organotin catalyst into a reactor, stir and react at 70° C. under nitrogen protection for 7 h to obtain a polyurethane-polyurea composite polymer;

[0092] 7. Add 10g of ultra-high molecular weight polyethylene fiber, 22g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2g of BYK-190, 6g of diphenyl phosphate and 4g of TPU to 52g of polyurethane-polyurea composite polymer, stir at 55°C for 50min under nitrogen protection, then add 1.5g of polydimethylsiloxane and 1g of 2,6-di-tert-butyl-p-cresol in sequence, and finally add 1.5g of polyoxypropylene glycerol ether, and continue stirring for 15min to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0093] Example 6:

[0094] like Figure 1 As shown, a method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0095] 1. Add 99.5g of silicon carbide whiskers to a blender and add 0.5g of 3-isocyanatepropyltrimethoxysilane dropwise to the blender while stirring under nitrogen protection.

[0096] 2. After the addition of 3-isocyanatepropyltrimethoxysilane, continue stirring for 6 minutes to obtain modified silicon carbide whiskers, which are then dried at 90°C under nitrogen protection for 2.5 hours and sealed for later use;

[0097] 3. Add 38 g of polyurethane to 42 g of xylene, stir and dissolve at 58 °C, then add 20 g of sealed modified silicon carbide whiskers and stir for 15 min to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0098] 4. Add 48 g of DMF, 17 g of tetramethyl-m-xylylene diisocyanate, 34.9 g of polyester polyol, and 0.1 g of an organotin catalyst into a reactor, and stir the mixture at 85° C. under nitrogen protection for 1.5 h to obtain a polyurethane prepolymer dispersion.

[0099] 5. Add 58g DMF, 32g m-xylylene diisocyanate and 10g diamine into the reactor, stir and react at 55°C under nitrogen protection for 25min to obtain a polyurea prepolymer dispersion;

[0100] 6. Add 70 g of polyurethane prepolymer dispersion, 29.8 g of polyurea prepolymer dispersion and 0.2 g of organotin catalyst into a reactor, stir and react at 75°C under nitrogen protection for 6.5 hours to obtain a polyurethane-polyurea composite polymer;

[0101] 7. Add 9 g of ultra-high molecular weight polyethylene fiber, 18 g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2 g of alkylphenol polyoxyethylene ether phosphate, 7 g of tricresyl phosphate and 3 g of styrene-butadiene rubber to 58 g of polyurethane-polyurea composite polymer, stir at 50°C under nitrogen protection for 40 min, then add 1 g of acrylic acid-ethyl acrylate copolymer and 1 g of triphenyl phosphite in sequence, and finally add 1 g of polyoxyethylene glycerol ether, and continue stirring for 12 min to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0102] Comparative Example 1:

[0103] A method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0104] 1. Add 35g of polyurethane to 40g of xylene, stir and dissolve at 55°C, then add 25g of silicon carbide whiskers and stir for 20min to obtain a polyurethane-silicon carbide whisker shear thickening liquid;

[0105] 2. Add 50g DMF, 15g m-xylylene diisocyanate, 34.8g polyester polyol and 0.2g organotin catalyst into a reactor, stir and react at 75°C under nitrogen protection for 2h to obtain a polyurethane prepolymer dispersion;

[0106] 3. Add 60g DMF, 30g m-xylylene diisocyanate and 10g heptylene diamine into the reactor, stir and react at 50°C for 30min under nitrogen protection to obtain a polyurea prepolymer dispersion;

[0107] 4. Add 70 g of polyurethane prepolymer dispersion, 29.8 g of polyurea prepolymer dispersion and 0.2 g of organotin catalyst into a reactor, stir and react at 65° C. under nitrogen protection for 6 h to obtain a polyurethane-polyurea composite polymer;

[0108] 5. Add 10g of ultra-high molecular weight polyethylene fiber, 24g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2g of sodium polymethacrylate, 6g of triethyl phosphate and 4g of ethylene propylene rubber to 50g of polyurethane-polyurea composite polymer, stir at 50°C under nitrogen protection for 45min, then add 1.5g of polyether-modified polydimethylsiloxane and 1.5g of zinc stearate in sequence, and finally add 1g of polyoxyethylene glycerol ether, and continue stirring for 12min to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0109] Comparative Example 2:

[0110] A method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0111] 1. Add 98g of silicon carbide whiskers to a blender and dropwise add 2g of 3-isocyanatepropyltriethoxysilane to the blender while stirring under nitrogen protection.

[0112] 2. After the addition of 3-isocyanatepropyltriethoxysilane, continue stirring for 10 minutes to obtain modified silicon carbide whiskers, which are then dried at 100°C for 2 hours under nitrogen protection and sealed for later use;

[0113] 3. Add 30 g of polyurethane to 50 g of xylene, stir and dissolve at 50°C, then add 20 g of sealed modified silicon carbide whiskers and stir for 10 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening liquid;

[0114] 4. Add 8 g of ultra-high molecular weight polyethylene fiber, 15 g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2 g of alkylphenol polyoxyethylene ether phosphate, 5 g of tricresyl phosphate and 5 g of nitrile rubber to 60 g of polyurea resin, stir at 45 ° C for 60 min under nitrogen protection, then add 2 g of acrylic acid-ethyl acrylate copolymer and 1 g of phenyl parahydroxybenzoate in sequence, and finally add 2 g of polyoxypropylene glycerol ether, and continue stirring for 20 min to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0115] Comparative Example 3:

[0116] A method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions comprises the following steps:

[0117] 1. Add 38g of polyurethane to 42g of xylene, stir and dissolve at 58°C, then add 20g of silicon carbide whiskers and stir for 15 minutes to obtain a polyurethane-silicon carbide whisker shear thickening liquid;

[0118] 2. Add 9 g of ultra-high molecular weight polyethylene fiber, 18 g of polyurethane-modified silicon carbide whisker shear thickening liquid, 2 g of alkylphenol polyoxyethylene ether phosphate, 7 g of tricresyl phosphate and 3 g of styrene-butadiene rubber to 58 g of polyurea resin, stir at 50 ° C for 40 minutes under nitrogen protection, then add 1 g of acrylic acid-ethyl acrylate copolymer and 1 g of triphenyl phosphite in sequence, and finally add 1 g of polyoxyethylene glycerol ether, and continue stirring for 12 minutes to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

[0119] Referring to the group standard of the Chemical Industry and Engineering Society of China "Spray-type Explosion-proof Elastomer Materials" (standard number T / CIESC 0019-2021), the mechanical properties of the prepared polyurethane modified composite coating were tested to demonstrate its explosion-proof and bulletproof functions.

[0120] Table 1 Test results of polyurethane modified composite coatings prepared in Examples and Comparative Examples

[0121]

[0122] As can be seen from Table 1, all test data of the polyurethane modified composite coatings prepared in Examples 1 to 6 are better than those in Comparative Examples 1 to 3.

[0123] This is because, in the polyurethane-modified composite coatings with bulletproof and explosion-proof functions prepared in Examples 1 to 6, the polyurethane prepolymer and the polyurea prepolymer obtained by the reaction further undergo a chemical reaction between isocyanate groups and hydroxyl groups to produce a polyurethane-polyurea composite polymer whose molecular chain contains both a rigid network of rigid groups such as benzene rings and urea groups and a flexible carbon chain derived from polyester polyols and long carbon chain diamines. Using this polyurethane-polyurea composite polymer as the matrix of the composite coating gives the composite coating excellent mechanical properties. Furthermore, when subjected to bullet or explosion impact, it can absorb energy through deformation and resist penetration and crack propagation through its rigid network, thus providing excellent bulletproof and explosion-proof functions. The polyurethane-modified silicon carbide whisker shear thickening fluid causes the composite coating to rapidly trigger a shear thickening effect when subjected to high-speed impact, rapidly hardening to resist penetration. Moreover, in the polyurethane-modified silicon carbide whisker shear thickening fluid, the isocyanate-silane coupling agent-modified silicon carbide whiskers contain a large number of isocyanate groups, which can improve the interfacial compatibility between the inorganic whiskers and the organic matrix on the one hand; on the other hand, they can further react with the amino or hydroxyl groups in the polyurethane-polyurea composite polymer to form strong chemical bonds. In addition, the polyurethane component in it also promotes the compatibility of the inorganic whiskers with the organic matrix due to the principle of like compatibility; therefore, the composite coating can reduce stress concentration and prevent interfacial debonding of the components. In summary, the polyurethane-modified silicon carbide whisker shear thickening fluid and the polyurethane-polyurea composite polymer matrix work synergistically, thereby further enhancing the bulletproof and explosion-proof functions of the prepared composite coating.

[0124] In Comparative Example 1, however, the silicon carbide whiskers were not modified, thus failing to improve the interfacial compatibility between the inorganic whiskers and the organic matrix. Furthermore, they were unable to react with the amino or hydroxyl groups in the polyurethane-polyurea composite polymer to form strong chemical bonds, resulting in poor explosion-proof and ballistic-resistant properties. In Comparative Example 2, the composite coating's matrix consisted solely of polyurea resin, which lacked excellent mechanical properties, resulting in poor explosion-proof and ballistic-resistant properties. The composite coating prepared in Comparative Example 3, which neither modified the silicon carbide whiskers nor used a polyurethane-polyurea composite polymer as its matrix, exhibited the worst explosion-proof and ballistic-resistant properties.

[0125] The above results show and describe the basic principles and main features of this application as well as the advantages of this application.

[0126] Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely illustrative of the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. Such changes and improvements are intended to fall within the scope of the present application. The scope of protection claimed in the present application is defined by the equivalents of the appended claims.

Claims

1. A polyurethane modified composite coating with bulletproof and explosion-proof functions, characterized in that: The invention comprises a polyurethane-polyurea composite polymer, ultra-high molecular weight polyethylene fibers, a polyurethane-modified silicon carbide whisker shear thickening fluid and additives; the polyurethane-polyurea composite polymer is obtained by chemical reaction between a polyurethane prepolymer and a polyurea prepolymer; the polyurethane prepolymer is obtained by chemical reaction between a diisocyanate containing a benzene ring and a polyester polyol; the polyurea prepolymer is obtained by chemical reaction between a diisocyanate containing a benzene ring and a diamine; the additives comprise a dispersant, a leveling agent, a defoaming agent, a stabilizer, a flame retardant and a toughening agent.

2. The polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 1, characterized in that: In the polyurethane-modified silicon carbide whisker shear thickening fluid, the modified silicon carbide whisker is a silicon carbide whisker modified by an isocyanate silane coupling agent; and the mass ratio of the silicon carbide whisker to the isocyanate silane coupling agent is (95-99):(1-5).

3. The polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 1, characterized in that: The mass ratio of the polyurethane-polyurea composite polymer, ultra-high molecular weight polyethylene fiber, polyurethane-modified silicon carbide whisker shear thickening liquid, dispersant, leveling agent, defoamer, stabilizer, flame retardant and toughening agent is (40-60): (8-15): (15-25): (1-3): (1-2): (1-2): (1-2): (5-8): (3-5).

4. The polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 1, characterized in that: The benzene ring-containing diisocyanate includes any one of meta-xylylene diisocyanate, tetramethyl meta-xylylene diisocyanate and diphenylmethane diisocyanate.

5. The polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 1, characterized in that: The diamine includes any one of heptanediamine, decanediamine, 1,12-diaminododecane and 1,14-tetradecanediamine.

6. The method for preparing the polyurethane modified composite coating with bulletproof and explosion-proof functions according to any one of claims 1 to 5, characterized in that: The following steps are involved: Add silicon carbide whiskers into a stirrer, and add isocyanate silane coupling agent dropwise into the stirrer while stirring under nitrogen protection; After the isocyanate silane coupling agent is added, stirring is continued for 5 to 10 minutes, and the mixture is dried at 80 to 100° C. for 2 to 4 hours under nitrogen protection to obtain modified silicon carbide whiskers, which are then sealed for later use. Add polyurethane to xylene, stir and dissolve at 50-60°C to obtain a mixed solution, add the sealed modified silicon carbide whiskers, and stir for 10-30 minutes to obtain a polyurethane-modified silicon carbide whisker shear thickening solution; DMF, benzene ring-containing diisocyanate, polyester polyol and organotin catalyst are added to a reactor, and stirred at 60-90° C. for 1-3 hours under nitrogen protection to obtain a polyurethane prepolymer; DMF, benzene ring-containing diisocyanate and diamine are added to a reaction kettle, and stirred and reacted at 40-60°C for 20-40 minutes under nitrogen protection to obtain a polyurea prepolymer; Putting polyurethane prepolymer, polyurea prepolymer and organotin catalyst into a reactor, stirring and reacting at 50-80° C. for 5-8 hours under nitrogen protection to obtain a polyurethane-polyurea composite polymer; Ultra-high molecular weight polyethylene fiber, polyurethane-modified silicon carbide whisker shear thickening liquid, dispersant, flame retardant and toughening agent are added to the polyurethane-polyurea composite polymer, stirred at 45-60°C for 30-60 minutes under nitrogen protection, then the leveling agent and stabilizer are added in sequence, and finally the defoaming agent is added, and stirring is continued for 10-20 minutes to obtain a polyurethane modified composite coating with bulletproof and explosion-proof functions.

7. The method for preparing a polyurethane modified composite coating having bulletproof and explosion-proof functions according to claim 6, characterized in that: In the process of preparing the polyurethane-modified silicon carbide whisker shear thickening fluid, the mass ratio of xylene, polyurethane and modified silicon carbide whisker is (30-50): (25-40): (15-30).

8. The method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 6, characterized in that: In the process of preparing the polyurethane prepolymer, the mass ratio of the DMF, the benzene ring-containing diisocyanate, the polyester polyol and the organotin catalyst is (40-60): (10-20): (30-40): (0.1-0.5).

9. The method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 6, characterized in that: In the process of preparing the polyurea prepolymer, the mass ratio of the DMF, the benzene ring-containing diisocyanate and the diamine is (50-70): (20-40): (5-10).

10. The method for preparing a polyurethane modified composite coating with bulletproof and explosion-proof functions according to claim 6, characterized in that: In the process of preparing the polyurethane-polyurea composite polymer, the mass ratio of the polyurethane prepolymer, the polyurea prepolymer and the organic tin catalyst is (62-74): (25-42): (0.1-0.5).

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