Three-phase solid buoyancy material based on gradient fiber structure hollow sphere and preparation method and application thereof

Abstract

The application belongs to the technical field of composite materials, and specifically discloses a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere, a preparation method and application thereof, the three-phase solid buoyancy material comprising a gradient fiber reinforced hollow sphere, hollow glass microspheres and a thermosetting resin matrix; the shell of the gradient fiber reinforced hollow sphere is composed of laminated thermosetting resin / reinforcing fiber layers, and at least contains two layers of thermosetting resin / reinforcing fiber layers, the fiber length in the thermosetting resin / reinforcing fiber layer is distributed in a gradient increasing manner from the inner layer to the outer layer along the radial direction of the hollow sphere; the hollow glass microspheres are uniformly dispersed in the gaps between the fiber reinforced hollow spheres; and the thermosetting resin matrix penetrates and solidifies to wrap the gradient fiber reinforced hollow spheres and the hollow glass microspheres. The application breaks the singleness of traditional solid buoyancy materials, and is suitable for 11000-meter and below full-sea-depth detection equipment.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere and its preparation method. Background Technology

[0002] Solid buoyancy materials are core materials for marine engineering and deep-sea exploration equipment, used to provide stable buoyancy in high-pressure underwater environments. The current mainstream technology is a two-phase homogeneous structure, that is, micron-sized hollow microspheres uniformly dispersed in a resin matrix. This type of material has significant technical bottlenecks in deep-sea applications, making it difficult to meet the comprehensive requirements of large depth, long life, lightweight and low cost.

[0003] First, their pressure resistance and sealing performance are insufficient. Existing materials mostly use homogeneous microspheres of 50-100 μm, with densities generally greater than 0.4 g / cm³. 3 The compressive strength is only 40-60 MPa, which cannot meet the hydrostatic pressure requirements of over 100 MPa at a depth of 11,000 meters. Simultaneously, the interfacial bonding is weak, and the water absorption rate exceeds 4%, making it prone to buoyancy reduction due to water seepage during long-term service, affecting equipment reliability. Secondly, there is a mismatch between cost and function. To improve strength, existing technologies often introduce expensive homogeneous fibers such as carbon fiber, significantly increasing material costs; moreover, there is a lack of depth-differentiated design, with the same formulation for shallow water (<500 meters) and deep water (>1000 meters), resulting in over-strengthening in shallow water and wasted resources. Thirdly, packing efficiency and interfacial processes are limited. The filler particle size is uniform, and the bulk density is less than 0.65 g / cm³. 3 The buoyancy efficiency and structural compactness are insufficient; the interface between the microspheres and the matrix depends on the modification of silane coupling agents, which is complex, costly and has limited interface stability.

[0004] Furthermore, there is an inherent contradiction between compressive strength and density. In traditional materials, increased strength is often accompanied by increased density, making it difficult to achieve a balance between low density and high strength and toughness. For example, in existing technologies, the density is approximately 0.706 g / cm³ when the compressive strength is 50 MPa. 3 It is impossible to simultaneously meet the requirements of lightweight and high strength. Uniform fiber distribution leads to performance shortcomings. The uniform distribution of fibers in hollow spheres makes it impossible to optimize the size distribution according to the layer thickness, which limits the compressive performance and interfacial bonding strength; moreover, it is difficult to balance tensile and compressive stresses, resulting in insufficient fatigue life.

[0005] In summary, traditional two-phase solid buoyancy materials suffer from problems such as limited performance, high cost, poor functional adaptability, low stacking efficiency, and contradictions between strength and density, which restrict the lightweight and economical development of deep-sea equipment. There is an urgent need to develop new structural and formulation systems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere, its preparation method, and its application. By introducing a gradient fiber structure hollow sphere into a two-phase system, a three-phase solid buoyancy material is prepared, enabling precise control of material properties. The material composition can be dynamically optimized for different water depth environments, balancing mechanical properties and cost. At the same time, the material's packing density and compressive strength are improved, water absorption is reduced, and fatigue life is extended. This provides a high-performance, low-cost, and customizable solid buoyancy material for deep-sea exploration equipment, solving problems such as single performance, high cost, poor functionality, low packing efficiency, and contradiction between compressive strength and density in existing two-phase solid buoyancy materials.

[0007] To achieve the above objectives, one of the technical solutions of the present invention is: a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere, comprising a gradient fiber reinforced hollow sphere, hollow glass microspheres, and a thermosetting resin matrix; the shell of the gradient fiber reinforced hollow sphere is composed of stacked thermosetting resin / reinforcing fiber layers, and includes at least two thermosetting resin / reinforcing fiber layers, wherein the fiber length in the thermosetting resin / reinforcing fiber layers is distributed in a gradient increasing manner from the inner layer to the outer layer along the radial direction of the hollow sphere; the hollow glass microspheres are uniformly dispersed in the gaps between the gradient fiber reinforced hollow spheres; the thermosetting resin / reinforcing fiber matrix... A resin matrix penetrates and cures the gradient fiber reinforced hollow spheres and hollow glass microspheres; the shell composition of the gradient fiber reinforced hollow spheres includes, by mass parts, 100 parts thermosetting resin, 20-40 parts diluent, 1-5 parts coupling agent, 20-100 parts curing agent, 1-5 parts accelerator, and 50-300 parts reinforcing fibers; the mass ratio of the core material to the single layer of thermosetting resin in the shell is 1:1-1.5; the volume ratio of the thermosetting resin matrix to the hollow glass microspheres and gradient fiber reinforced hollow spheres is 100:(30-70):(20-105).

[0008] In a preferred embodiment of the present invention, the diameter of the hollow glass microspheres is 20~100 μm, and the diameter of the gradient fiber reinforced hollow spheres is 6~30 mm when made of carbon fiber, and 6~60 mm when made of glass fiber or wollastonite fiber.

[0009] In a preferred embodiment of the present invention, the core material is one or more of expanded polystyrene (EPS), expanded polyethylene (EPP), and expanded polypropylene (EPE).

[0010] In a preferred embodiment of the present invention, the thermosetting resin comprises one or more of epoxy resin, phenolic resin, polyurethane resin, and polyimide resin; the polyimide resin comprises one or more of unsaturated polyester resin, vinyl resin, and polyester resin; and the polyurethane resin comprises one or more of polyether polyurethane and polyester polyurethane. The thermosetting resin serves as a matrix to provide interfacial adhesion and water resistance.

[0011] In a preferred embodiment of the present invention, the curing agent comprises one or more of amines, acid anhydrides, latent curing agents, alcohols, phenols, imidazoles, thiols, ketone-aldehyde-phenol-aldehyde curing agents, and isocyanates; the diluent comprises one or more glycidyl ethers; the coupling agent comprises a silane coupling agent or a titanate coupling agent, wherein the silane coupling agent comprises one or two of γ-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane, and the titanate coupling agent comprises one or more of isopropyltris(dioctylphosphoyloxy)titanate, isopropyltris(dioctylpyrophosphoyloxy)titanate, and bis(diisooctylpyrophosphoyloxy)ethylene titanate; and the accelerator comprises one or more of 2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine.

[0012] In a preferred embodiment of the present invention, the reinforcing fiber comprises one of carbon fiber, glass fiber, wollastonite fiber, aramid fiber, and basalt fiber.

[0013] In a preferred embodiment of the present invention, the short fiber length is 50~200μm and the long fiber length is 200~6000μm.

[0014] To achieve the above objectives, the second technical solution of the present invention is: a method for preparing a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere, comprising the following steps:

[0015] Preparation of S1 gradient fiber reinforced hollow spheres:

[0016] (1) The core material is placed into the air classifier to suspend it;

[0017] (2) Mix the thermosetting resin, diluent, silane coupling agent, curing agent and accelerator evenly according to the composition ratio, and use an atomizer to atomize the resulting mixed liquid. The atomization pressure is 0.5~5 bar and the droplet size is 10~150 μm. Then, evenly cover the core material surface to form a resin film.

[0018] (3) The reinforcing fiber filaments are cut into specific gradient sizes using a long fiber cutting spray gun, and the cut reinforcing fibers are sprayed onto the surface of the core material that has formed a resin film to obtain a resin fiber solid ball;

[0019] (4) The resin fiber solid spheres are put into a fluidized bed for rolling and heating curing. The curing temperature is 40~70℃ and the time is 0.25~0.60 h to form a preliminary gradient fiber reinforced solid sphere. Then the spheres are put into an air classifier to suspend them again.

[0020] (5) Repeat steps (2) to (4) to control fiber size and number of wraps until the target density and number of layers are achieved, forming a fiber length gradient distribution with short inner layers and long outer layers, and optimizing compression performance and core-shell interface bonding;

[0021] (6) The spheres obtained in step (5) are subjected to post-curing treatment. The post-curing temperature is 110~150℃ and the time is 80~150min. The core material melts due to the heating temperature being higher than its melting point, and the volume shrinks, resulting in the formation of a cavity inside the sphere. Finally, a hollow sphere of fiber gradient reinforced thermosetting resin composite material with a hollow structure is obtained.

[0022] Preparation of S2 three-phase solid buoyancy material:

[0023] (1) Graded compound filler: According to the working conditions, hollow glass microspheres and gradient fiber reinforced hollow spheres obtained in step S1 are mixed in proportion to obtain a mixed filler.

[0024] (2) Vacuum infusion: Place the mixed filler in the mold, evacuate to a vacuum degree of -0.10~-0.08 MPa, and inject a resin mixture containing thermosetting resin, diluent, silane coupling agent, curing agent and accelerator. The viscosity of the resin mixture is controlled at 200~300 mPa·s to ensure that the resin fully wets the gradient fiber reinforced hollow spheres and hollow glass microspheres.

[0025] (3) Segmented vacuum control: Before the resin injection material is injected into the mold, the mold is subjected to a low negative pressure of -0.08~-0.04 MPa. After the resin injection material is injected into the mold, the negative pressure is increased to -0.10~-0.07 MPa to suppress the floating of microbeads and ensure the stability of the product density gradient.

[0026] (4) Curing and molding: heat curing at 40~70℃ for 0.1~0.4 h, demolding and then curing at 110~150℃ for 0.5~1.5 h to obtain a three-phase solid buoyancy material.

[0027] In a preferred embodiment of the present invention, the airflow velocity of the air classifier in steps (1) and (4) of step S1 is 0.2~1 m / s, and the flow rate is 1000~3000 m³ / s. 3 / h.

[0028] To achieve the above objectives, the third technical solution of the present invention is: an application of a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Excellent mechanical properties: Fiber gradient optimizes compressive performance and interface bonding, with short inner fibers resisting compression and long outer fibers resisting tension, balancing tensile and compressive stress and improving fatigue life;

[0031] 2. Low water absorption: The high interfacial bonding strength between the gradient fiber reinforced hollow spheres and microspheres greatly reduces the water absorption rate of the material, significantly improving the long-term stability and reliability of the material in the deep-sea environment.

[0032] 3. High fatigue life: The stress transmission path is optimized by the fiber length gradient distribution, reducing interface stress concentration and significantly extending the material's fatigue life;

[0033] 4. High process controllability: The air classifier precisely controls the matrix density, the atomizer ensures uniform resin coverage, the fiber cutting spray gun precisely controls the fiber size, and the vacuum filling mold, injection port size, and process parameters have a wide range of adjustable parameters, making the preparation process stable and reliable.

[0034] 5. High bonding strength between core material and shell: The gradient fiber structure design enhances the bonding strength between the core material and shell, making the overall structure of the material more stable and significantly improving its compressive strength.

[0035] 6. Functional and targeted optimization: Through fiber gradient design and graded compounding of fillers, it can be adapted to all working conditions: On the same process platform, only the parameters of gradient hollow spheres and hollow microspheres need to be adjusted to adapt to the needs of the entire ocean depth of 11,000m and below, which significantly improves the applicability and engineering value of the material. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the three-phase solid buoyancy material based on a gradient fiber structure hollow sphere obtained by the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0038] Figure 1 This is a schematic diagram of the three-phase solid buoyancy material based on a gradient fiber structure hollow sphere obtained by the present invention.

[0039] A three-phase solid buoyancy material based on gradient fiber-reinforced hollow spheres includes gradient fiber-reinforced hollow spheres, hollow glass microspheres, and a thermosetting resin matrix. The shell of each gradient fiber-reinforced hollow sphere is composed of stacked thermosetting resin / reinforcing fiber layers, and includes at least two thermosetting resin / reinforcing fiber layers. The fiber length in each thermosetting resin / reinforcing fiber layer increases in a gradient manner from the inner to the outer layer along the radial direction of the hollow sphere. The hollow glass microspheres are uniformly dispersed in the gaps between the gradient fiber-reinforced hollow spheres. The thermosetting resin matrix penetrates and is cured. The core material is encapsulated in the gradient fiber reinforced hollow spheres and hollow glass microspheres. The shell of the gradient fiber reinforced hollow spheres comprises, by mass parts, 100 parts of thermosetting resin, 20-40 parts of diluent, 1-5 parts of coupling agent, 20-100 parts of curing agent, 1-5 parts of accelerator, and 50-300 parts of reinforcing fiber. The mass ratio of the core material to the single layer of thermosetting resin in the shell is 1:1-1.5. The volume ratio of the thermosetting resin matrix to the hollow glass microspheres and gradient fiber reinforced hollow spheres is 100:(30-70):(20-105).

[0040] The hollow glass microspheres have a diameter of 20~100 μm. The gradient fiber reinforced hollow spheres have a diameter of 6~30 mm when made of carbon fiber and 6~60 mm when made of glass fiber or wollastonite fiber.

[0041] The core material is one or more of expanded polystyrene (EPS), expanded polyethylene (EPP), and expanded polypropylene (EPE).

[0042] The thermosetting resin comprises one or more of epoxy resin, phenolic resin, polyurethane resin, and polyimide resin; the polyimide resin comprises one or more of unsaturated polyester resin, vinyl resin, and polyester resin; and the polyurethane resin comprises one or more of polyether polyurethane and polyester polyurethane. The thermosetting resin serves as a matrix to provide interfacial adhesion and water resistance.

[0043] The curing agent comprises one or more of the following: amines, acid anhydrides, latent curing agents, alcohols, phenols, imidazoles, thiols, ketone-aldehyde-phenol-aldehyde curing agents, and isocyanates; the diluent comprises one or more of the following: glycidyl ethers; the coupling agent comprises a silane coupling agent or a titanate coupling agent, wherein the silane coupling agent comprises one or two of γ-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane, and the titanate coupling agent comprises one or more of the following: isopropyltris(dioctylphosphoyloxy)titanate, isopropyltris(dioctylpyrophosphoyloxy)titanate, and bis(diisooctylpyrophosphoyloxy)ethylene titanate; and the accelerator comprises one or more of the following: 2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine.

[0044] The reinforcing fiber comprises one of carbon fiber, glass fiber, wollastonite fiber, aramid fiber, and basalt fiber.

[0045] When the reinforcing fiber is carbon fiber, the inner carbon fiber has a length of 50~200μm and the outer carbon fiber has a length of 200~6000μm; when the reinforcing fiber is glass fiber, the inner carbon fiber has a length of 50~200μm and the outer carbon fiber has a length of 200~6000μm; when the reinforcing fiber is wollastonite fiber, the inner carbon fiber has a length of 50~200μm and the outer carbon fiber has a length of 200~6000μm.

[0046] A method for preparing a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere includes the following steps:

[0047] Preparation of S1 gradient fiber reinforced hollow spheres:

[0048] (1) The core material is placed into the air classifier to suspend it;

[0049] (2) Mix the thermosetting resin, diluent, silane coupling agent, curing agent and accelerator evenly according to the composition ratio, and use an atomizer to atomize the resulting mixed liquid. The atomization pressure is 0.5~5 bar and the droplet size is 10~150 μm. Then, evenly cover the core material surface to form a resin film.

[0050] (3) The reinforcing fiber filaments are cut into specific gradient sizes using a long fiber cutting spray gun, and the cut reinforcing fibers are sprayed onto the surface of the core material that has formed a resin film to obtain a resin fiber solid ball;

[0051] (4) The resin fiber solid spheres are put into a fluidized bed for rolling and heating curing. The curing temperature is 40~70℃ and the time is 0.25~0.60 h to form a preliminary gradient fiber reinforced solid sphere. Then the spheres are put into an air classifier to suspend them again.

[0052] (5) Repeat steps (2) to (4) to control fiber size and number of wraps until the target density and number of layers are achieved, forming a fiber length gradient distribution with short inner layers and long outer layers, and optimizing compression performance and core-shell interface bonding;

[0053] (6) The spheres obtained in step (5) are subjected to post-curing treatment at a temperature of 110~150℃ for 80~150 min.

[0054] (7) The core material melts due to the heating temperature being higher than its melting point, and the volume shrinks, resulting in the formation of a cavity inside the sphere, ultimately obtaining a hollow sphere of fiber gradient reinforced thermosetting resin composite material with a hollow structure.

[0055] Preparation of S2 three-phase solid buoyancy material:

[0056] (1) Graded compound filler: According to the working conditions, hollow glass microspheres and gradient fiber reinforced hollow spheres obtained in step S1 are mixed in proportion to obtain a mixed filler.

[0057] (2) Vacuum infusion: Place the mixed filler in the mold, evacuate to a vacuum degree of -0.10~-0.08 MPa, and inject a resin mixture containing thermosetting resin, diluent, silane coupling agent, curing agent and accelerator. The viscosity of the resin mixture is controlled at 200~300 mPa·s to ensure that the resin fully wets the gradient fiber reinforced hollow spheres and hollow glass microspheres.

[0058] (3) Segmented vacuum control: Before the resin injection material is injected into the mold, the mold is subjected to a low negative pressure of -0.08~-0.04 MPa. After the resin injection material is injected into the mold, the negative pressure is increased to -0.10~-0.07 MPa to suppress the floating of microbeads and ensure the stability of the product density gradient.

[0059] (4) Curing and molding: heat curing at 40~70℃ for 0.1~0.4 h, demolding and then curing at 110~150℃ for 0.5~1.5 h to obtain a three-phase solid buoyancy material.

[0060] In steps S1 (1) and (4), the airflow velocity of the air classifier is 0.2~1 m / s, and the flow rate is 1000~3000 m³ / s. 3 / h.

[0061] Application of a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere.

[0062] Table 1. Types of Gradient Fiber Hollow Spheres Applicable to Different Water Depths / Operating Conditions, Optimal Fiber Gradient Design, and Performance

[0063]

[0064] Example 1

[0065] A three-phase solid buoyancy material suitable for the entire ocean depth range (11000m) comprises gradient fiber reinforced hollow spheres, hollow glass microspheres, and a thermosetting resin matrix; the shell of the gradient fiber reinforced hollow spheres is composed of stacked thermosetting resin / reinforcing fiber layers, comprising 13 layers of thermosetting resin / reinforcing fiber layers, wherein the fiber length in the thermosetting resin / reinforcing fiber layers is distributed in a gradient increasing manner from the inner layer to the outer layer along the radial direction of the hollow spheres; the hollow glass microspheres are uniformly dispersed in the gaps between the gradient fiber reinforced hollow spheres; the thermosetting resin matrix penetrates and cures, encapsulating the gradient fiber reinforced hollow spheres and the hollow glass microspheres; its composition includes:

[0066] 1. Gradient fiber reinforced hollow spheres: carbon fiber reinforced spheres (diameter 6~7mm, inner fiber length 50~100μm, outer fiber length 120~200μm); 100g.

[0067] Table 2. Composition of the resin-fiber composite shell in carbon fiber graded reinforced spheres

[0068]

[0069] The mass ratio of the core material, a thermosetting resin layer, and a reinforcing fiber layer is 100:110:105.

[0070] 2. Micron-sized hollow glass microspheres: HGM-1 (true density 0.60g / cm³) 120g.

[0071] 3. Thermosetting resin: 100g of E44 epoxy resin

[0072] 4. Curing agent: 20g diethylamine

[0073] 5. Diluent: 30g n-Butyl glycidyl ether

[0074] 6. Coupling agent: 5g γ-aminopropyltriethoxysilane

[0075] 7. Accelerator: 2,4,6-Tris(dimethylaminomethyl)phenol: 2g

[0076] Prepared by the following method:

[0077] Preparation of S1 gradient fiber reinforced hollow spheres:

[0078] (1) Select EPS balls with a diameter of 6~7mm as the core material, and adjust the airflow speed and flow rate (specific values ​​are shown in Table 3) to make the EPS balls suspend.

[0079] (2) The thermosetting resin, diluent, silane coupling agent, curing agent and accelerator are mixed evenly according to the composition ratio. The amount of resin added to each layer of the mixture is 110 parts by mass. The obtained mixed liquid is atomized using an atomizer. The atomization pressure is 2.4 bar and the droplet size is controlled at 60 μm. The atomized liquid is sprayed onto the surface of the core material suspended in step (1) to form a resin film and obtain a thermosetting resin layer.

[0080] (3) Use a long fiber cutting spray gun to cut the carbon fiber filament into short fibers with a length of 50~100μm. The amount of each layer of fiber is 105 parts by mass. Spray the cut carbon fiber evenly onto the surface of the core material that has been covered with resin in step (2) to obtain a layer of reinforcing fiber and obtain a resin fiber solid ball.

[0081] (4) Place the resin balls covered with fibers into a vulcanizing bed, set the temperature to 50°C, and keep them warm for 25 minutes. Cur them by rolling and heating to form a preliminary gradient fiber-reinforced solid ball. Then, put the ball into an air classifier to suspend it again.

[0082] (5) Repeat steps (2) to (4) until the 6-layer reinforcing fiber layer is completed. Starting from the preparation of the 7th layer of reinforcing fiber, adjust the cutting length of the carbon fiber filament in the long fiber cutting spray gun in step (3) to 120~200μm to form the outer long fiber structure. Continue to repeat steps (2) to (4) until the 13th layer of reinforcing fiber is completed.

[0083] (6) The spheres obtained in step (5) are placed in an oven for post-curing and core shrinkage at 110°C for 90 min, resulting in a total shell wall thickness of 0.4~0.5 mm and a density of 0.55 g / cm³. 3 Carbon fiber reinforced hollow spheres with a fiber length gradient distribution.

[0084] Preparation of S2 three-phase solid buoyancy material:

[0085] (1) Graded compound filler: The carbon fiber reinforced hollow spheres prepared in step S1 are mixed with HGM-1 microspheres according to the above addition amount to obtain a mixed filler;

[0086] (2) Vacuum infusion: Place the mixed filler in the mold; evacuate to -0.06 MPa and maintain for 10 min to ensure uniform distribution of the filler; inject a resin mixture containing E44 epoxy resin, diethylamine, n-butyl glycidyl ether, γ-aminopropyltriethoxysilane, and 7,2,4,6-tris(dimethylaminomethyl)phenol. The viscosity of the resin mixture is controlled at 250 mPa·s (25℃) to ensure that the resin fully wets the fibers and microspheres.

[0087] (3) Segmented vacuum control: Before the resin injection material is pumped in, a low negative pressure of -0.08 MPa is used. After the resin injection material is pumped in, the vacuum pressure is increased to -0.10 MPa and maintained for 15 min.

[0088] (4) Curing and molding: heat curing at 70℃ for 0.25 h, and after demolding, curing at 150℃ for 1 h to obtain the final three-phase solid buoyancy material.

[0089] Table 3. Airflow velocity, flow rate, and fiber length used in each layer during the preparation process of Example 1

[0090]

[0091] The density, water absorption rate, and other properties of the obtained three-phase solid buoyancy material were tested, and the test results are as follows:

[0092] Density: 0.650 g / cm³ 3 ;

[0093] Water absorption rate: 0.8% (tested at 135MPa for 96 hours);

[0094] Compressive strength: 105MPa (test method refers to GB / T 45900-2025).

[0095] Application: Suitable for full ocean depth exploration equipment up to 11,000 meters.

[0096] Example 2

[0097] A three-phase solid buoyancy material suitable for medium-deep water (2000m) comprises gradient fiber reinforced hollow spheres, hollow glass microspheres, and a thermosetting resin matrix; the shell of the gradient fiber reinforced hollow spheres is composed of stacked thermosetting resin / reinforcing fiber layers, comprising 21 layers of thermosetting resin / reinforcing fiber layers, wherein the fiber length in the thermosetting resin / reinforcing fiber layers increases in a gradient from the inner layer to the outer layer along the radial direction of the hollow spheres; the hollow glass microspheres are uniformly dispersed in the gaps between the gradient fiber reinforced hollow spheres; the thermosetting resin matrix penetrates and cures, encapsulating the gradient fiber reinforced hollow spheres and the hollow glass microspheres; its composition includes:

[0098] 1. Gradient fiber reinforced hollow spheres: 90g of glass fiber reinforced spheres (diameter 31~34mm, inner fiber length 150~250μm, outer fiber length 500~1000μm).

[0099] Table 4. Composition of the resin-fiber composite shell in glass fiber reinforced spheres

[0100]

[0101] The mass ratio of the core material, the thermosetting resin layer, and the reinforcing fiber layer is 100:120:200.

[0102] 2. Micron-sized hollow glass microspheres: HGM-2 (true density 0.50 g / cm³) 3 ), 130g;

[0103] 3. Thermosetting resin: 100g of E54 epoxy resin

[0104] 4. Diluent: 40g propylene oxide butyl

[0105] 5. Curing agent: 30g modified amine

[0106] 6. Coupling agent: Isopropyl tris(dioctylpyrophosphate)titanate 5g

[0107] 7. Accelerator: 2,4,6-Tris(dimethylaminomethyl)phenol: 2g

[0108] Prepared by the following method:

[0109] Preparation of S1 gradient fiber reinforced hollow spheres:

[0110] (1) Weigh 100 parts by mass of expanded polystyrene (EPS) core material and add them to the air classifier. Adjust the airflow speed and flow rate (specific values ​​are shown in Table 4) to keep them in a suspended state.

[0111] (2) The thermosetting resin, diluent, silane coupling agent, curing agent and accelerator are mixed evenly according to the composition ratio. The amount of resin added to each layer of the mixture is 120 parts by mass. The obtained mixed liquid is atomized using an atomizer. The atomization pressure is 1.7 bar and the droplet size is controlled at 45 μm. The atomized liquid is sprayed onto the surface of the core material suspended in step (1) to form a resin film and obtain a thermosetting resin layer.

[0112] (3) Fiber spraying: The glass fiber filament is cut into short fibers of 150-250μm length using a long fiber cutting spray gun. The amount of each layer of fiber is 200 parts by mass. The cut glass fiber is evenly sprayed onto the surface of the core material that has been covered with resin in step (2) to obtain a layer of reinforcing fiber and obtain a resin fiber solid ball.

[0113] (4) Curing and molding: The resin fiber solid spheres obtained in step (3) are placed in a fluidized bed, the temperature is set to 60℃, the holding time is 35 min, and the resin fiber solid spheres with shell structure are obtained by rolling heating and curing. Then the spheres are put into an air classifier to suspend them again.

[0114] (5) Fiber gradient structure formation: Repeat steps (2) to (4) until 11 layers of reinforcing fiber are wrapped. Starting from the preparation of the 12th layer of reinforcing fiber, the fiber cutting size in step (3) is adjusted to 500~1000 μm. Continue to repeat steps (2) to (4) until 21 layers of reinforcing fiber are wrapped.

[0115] (6) Post-curing and formation of hollow structure: The spheres obtained in step (5) are placed in an oven for post-curing and core shrinkage at 130°C for 120 min, finally obtaining a total shell wall thickness of 1.0~1.1 mm and a density of 0.38 g / cm³. 3 Glass fiber reinforced hollow spheres with a fiber length gradient distribution.

[0116] Preparation of S2 three-phase solid buoyancy material:

[0117] (1) Graded compound filler: The glass fiber reinforced hollow spheres prepared in step S1 are mixed with HGM-2 microspheres according to the above addition amount to obtain a mixed filler;

[0118] (2) Vacuum infusion: Place the mixed filler in the mold; evacuate to -0.06 MPa and maintain for 10 min to ensure uniform distribution of the filler; inject a resin mixture containing E54 epoxy resin, modified amine, propylene oxide butyl glycidyl ether, isopropyl tris(dioctyl pyrophosphate) titanate, and 2,4,6-tris(dimethylaminomethyl)phenol. The viscosity of the resin mixture is controlled at 250 mPa·s (25℃) to ensure that the resin fully wets the fibers and microspheres.

[0119] (3) Segmented vacuum control: Before the resin injection material is pumped in, a low negative pressure of -0.06 MPa is used. After the resin injection material is pumped in, the vacuum pressure is increased to -0.08 MPa and maintained for 15 min.

[0120] (4) Curing and molding: heat curing at 60℃ for 0.25 h, and after demolding, curing at 140℃ for 1 h to obtain the final three-phase solid buoyancy material.

[0121] Table 5. Airflow velocity, flow rate, and fiber length used in each layer during the preparation process of Example 2.

[0122]

[0123] The density, water absorption rate, and other properties of the obtained three-phase solid buoyancy material were tested, and the test results are as follows:

[0124] Density: 0.550 g / cm³ 3 ;

[0125] Water absorption rate: 1.2% (tested at 25MPa for 96 hours);

[0126] Compressive strength: 38MPa (test method refers to GB / T 45900-2025).

[0127] Application: Suitable for engineering equipment up to 2000 meters.

[0128] Example 3

[0129] A three-phase solid buoyancy material suitable for shallow water areas (500m) comprises gradient fiber reinforced hollow spheres, hollow glass microspheres, and a thermosetting resin matrix; the shell of the gradient fiber reinforced hollow spheres is composed of stacked thermosetting resin / reinforcing fiber layers, comprising 14 layers of thermosetting resin / reinforcing fiber layers, wherein the fiber length in the thermosetting resin / reinforcing fiber layers is distributed in a gradient increasing manner from the inner layer to the outer layer along the radial direction of the hollow spheres; the hollow glass microspheres are uniformly dispersed in the gaps between the gradient fiber reinforced hollow spheres; the thermosetting resin matrix penetrates and cures, encapsulating the gradient fiber reinforced hollow spheres and the hollow glass microspheres; its components include:

[0130] 1. Gradient fiber reinforced hollow spheres: 60g of wollastonite fiber reinforced spheres (diameter 31~33mm, inner fiber length 150~250μm, outer fiber length 500~1000μm).

[0131] Table 6. Composition of the resin-fiber composite shell in wollastonite fiber-reinforced spheres

[0132]

[0133] The mass ratio of the core material, a thermosetting resin layer, and a reinforcing fiber layer is 100:120:210.

[0134] 2. Micron-sized hollow glass microspheres: HGM-3 (true density 0.38 g / cm³), 80 g.

[0135] 3. Thermosetting resin matrix: Polyether polyurethane 100g

[0136] 4. Curing agent: 20g diethylamine

[0137] 5. Diluent: 15g 1,4-Butanediol diglycidyl ether, 6g polyethylene glycol diglycidyl ether

[0138] 6. Coupling agent: 5g γ-glycidyl oxypropyltrimethoxysilane

[0139] 7. Accelerator: N,N-dimethylcyclohexylamine: 2g

[0140] Prepared by the following method:

[0141] Preparation of S1 gradient fiber reinforced hollow spheres:

[0142] (1) Weigh 100 parts by mass of foamed polypropylene plastic balls (EPE) and add them to the air classifier. Adjust the airflow speed and flow rate (specific values ​​are shown in Table 4) to keep them in a suspended state.

[0143] (2) The thermosetting resin, diluent, silane coupling agent, curing agent and accelerator are mixed evenly according to the composition ratio. The amount of resin added to each layer of the mixture is 120 parts by mass. The obtained mixed liquid is atomized using an atomizer. The atomization pressure is 1.6 bar and the droplet size is controlled at 50 μm. The atomized liquid is sprayed onto the surface of the core material suspended in step (1) to form a resin film and obtain a thermosetting resin layer.

[0144] (3) Fiber spraying: The 1-7 layers of shell are wrapped with a long fiber cutting spray gun to cut the wollastonite fiber filament into short fibers with a length of 150-250 μm. The amount of each layer of fiber is 210 parts by mass. The cut wollastonite fiber is evenly sprayed onto the surface of the core material that has been covered with resin in step (2) to obtain a layer of reinforcing fiber and obtain a resin fiber solid ball.

[0145] (4) Curing and molding: The resin fiber solid spheres obtained in step (3) are placed in a fluidized bed, the temperature is set to 65℃, the holding time is 30min, and the resin fiber solid spheres with shell structure are obtained by rolling heating and curing. Then the spheres are put into an air classifier to suspend them again.

[0146] (5) Fiber gradient structure formation: Repeat steps (2) to (4), starting from the preparation of the 8th reinforcing fiber layer, adjust the fiber cutting size in step (3) to 500~1000 μm, and continue to repeat steps (2) to (4) until the 14-layer reinforcing fiber layer is completed;

[0147] (6) Post-curing and formation of hollow structure: The spheres obtained in step (5) are placed in an oven for post-curing and core shrinkage at 130°C for 120 minutes, resulting in a total shell wall thickness of 0.75~0.85 mm and a density of 0.25 g / cm³. 3 Hollow spheres reinforced with wollastonite fibers featuring a gradient distribution of fiber length.

[0148] Preparation of S2 three-phase solid buoyancy material:

[0149] (1) Graded compound filler: The carbon fiber reinforced hollow spheres prepared in step S1 are mixed with HGM-3 microspheres according to the above addition amount to obtain a mixed filler;

[0150] (2) Vacuum infusion: Place the mixed filler in the mold; evacuate to -0.06 MPa and maintain for 10 min to ensure uniform distribution of the filler; inject a resin mixture containing E44 epoxy resin, diethylamine, n-butyl glycidyl ether, γ-aminopropyltriethoxysilane, and 7,2,4,6-tris(dimethylaminomethyl)phenol. The viscosity of the resin mixture is controlled at 250 mPa·s (25℃) to ensure that the resin fully wets the fibers and microspheres.

[0151] (3) Segmented vacuum control: Before the resin injection material is pumped in, a low negative pressure of -0.04 MPa is used. After the resin injection material is pumped in, the vacuum pressure is increased to -0.06 MPa and maintained for 15 min.

[0152] (4) Curing and molding: heat curing at 50℃ for 0.25 h, and after demolding, curing at 130℃ for 1.5 h to obtain the final three-phase solid buoyancy material.

[0153] Table 7. Airflow velocity, flow rate, and fiber length used in each layer during the preparation process of Example 3.

[0154]

[0155] The density, water absorption rate, and other properties of the obtained three-phase solid buoyancy material were tested, and the test results are as follows:

[0156] Density: 0.45 g / cm³;

[0157] Water absorption rate: 0.3% (tested at 7MPa for 96 hours);

[0158] Compressive strength: 18MPa (test method refers to GB / T 45900-2025).

[0159] Application: Suitable for products in shallow water areas up to 500 meters deep.

[0160] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-phase solid buoyancy material based on a gradient fiber structure hollow sphere, characterized in that, The device comprises gradient fiber reinforced hollow spheres, hollow glass microspheres, and a thermosetting resin matrix. The shell of each gradient fiber reinforced hollow sphere is composed of stacked thermosetting resin / reinforcing fiber layers, and includes at least two thermosetting resin / reinforcing fiber layers. The fiber length in each thermosetting resin / reinforcing fiber layer increases in a gradient from the inner to the outermost layer along the radial direction of the hollow sphere. The hollow glass microspheres are uniformly dispersed in the gaps between the fiber-reinforced hollow spheres. The thermosetting resin matrix penetrates and cures, encapsulating the gradient fiber reinforced hollow spheres. The hollow spheres and hollow glass microspheres; the shell composition of the gradient fiber reinforced hollow spheres includes, by mass parts, 100 parts thermosetting resin, 20-40 parts diluent, 1-5 parts coupling agent, 20-100 parts curing agent, 1-5 parts accelerator, and 50-300 parts reinforcing fiber, the mass ratio of the core material to the single layer of thermosetting resin in the shell is 1:1-1.5; the volume ratio of the thermosetting resin matrix to the hollow glass microspheres and gradient fiber reinforced hollow spheres is 100:(30-70):(20-105).

2. The three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 1, characterized in that, The hollow glass microspheres have a diameter of 20~100 μm. The gradient fiber reinforced hollow spheres have a diameter of 6~30 mm when made of carbon fiber and 6~60 mm when made of glass fiber or wollastonite fiber.

3. The three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 1, characterized in that, The core material is one or more of expanded polystyrene plastic balls, expanded polyethylene balls, and expanded polypropylene balls.

4. The three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 1, characterized in that, The thermosetting resin includes one or more of epoxy resin, phenolic resin, polyurethane resin, and polyimide resin; the polyimide resin includes one or more of unsaturated polyester resin, vinyl resin, and polyester resin; and the polyurethane resin includes one or more of polyether polyurethane and polyester polyurethane.

5. The three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 1, characterized in that, The curing agent comprises one or more of the following: amines, acid anhydrides, latent curing agents, alcohols, phenols, imidazoles, thiols, ketone-aldehyde-phenol-aldehyde curing agents, and isocyanates; the diluent comprises one or more of the following: glycidyl ethers; the coupling agent comprises a silane coupling agent or a titanate coupling agent, wherein the silane coupling agent comprises one or two of γ-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane, and the titanate coupling agent comprises one or more of the following: isopropyltris(dioctylphosphoyloxy)titanate, isopropyltris(dioctylpyrophosphoyloxy)titanate, and bis(diisooctylpyrophosphoyloxy)ethylene titanate; and the accelerator comprises one or more of the following: 2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine.

6. The three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 1, characterized in that, The reinforcing fiber comprises one of carbon fiber, glass fiber, wollastonite fiber, aramid fiber, and basalt fiber.

7. The three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 1, characterized in that, The short fibers have a length of 50~200μm, and the long fibers have a length of 200~6000μm.

8. An application of a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in any one of claims 1-7.

9. A method for preparing a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in any one of claims 1-7, characterized in that, Includes the following steps: Preparation of S1 gradient fiber reinforced hollow spheres: (1) The core material is placed into the air classifier to suspend it; (2) Mix the thermosetting resin, diluent, silane coupling agent, curing agent and accelerator evenly according to the composition ratio, and use an atomizer to atomize the resulting mixed liquid. The atomization pressure is 0.5~5 bar and the droplet size is 10~150 μm. Then, evenly cover the core material surface to form a resin film. (3) The reinforcing fiber filaments are cut into specific gradient sizes using a long fiber cutting spray gun, and the cut reinforcing fibers are sprayed onto the surface of the core material that has formed a resin film to obtain a resin fiber solid ball; (4) The resin fiber solid spheres are put into a fluidized bed for rolling and heating curing. The curing temperature is 40~70℃ and the time is 0.25~0.60 h to form a preliminary gradient fiber reinforced solid sphere. Then the spheres are put into an air classifier to suspend them again. (5) Repeat steps (2) to (4) to control fiber size and number of wraps until the target density and number of layers are achieved, forming a fiber length gradient distribution with short inner layers and long outer layers, and optimizing compression performance and core-shell interface bonding; (6) The spheres obtained in step (5) are subjected to post-curing treatment. The post-curing temperature is 110~150℃ and the heating time is 80~150min. The core material shrinks in volume, causing a cavity to form inside the sphere. Finally, a hollow sphere of fiber gradient reinforced thermosetting resin composite material with a hollow structure is obtained. Preparation of S2 three-phase solid buoyancy material: (1) Graded compound filler: Hollow glass microspheres and gradient fiber reinforced hollow spheres obtained in step S1 are mixed in proportion to obtain a mixed filler; (2) Vacuum infusion: Place the mixed filler in the mold, evacuate to a vacuum degree of -0.10~-0.08 MPa, and inject a resin mixture containing thermosetting resin, diluent, silane coupling agent, curing agent and accelerator. The viscosity of the resin mixture is controlled at 200~300 mPa·s to ensure that the resin fully wets the gradient fiber reinforced hollow spheres and hollow glass microspheres. (3) Segmented vacuum control: Before the resin injection material is injected into the mold, the mold is subjected to a low negative pressure of -0.08~-0.04 MPa. After the resin injection material is injected into the mold, the negative pressure is increased to -0.10~-0.07 MPa to suppress the floating of microbeads and ensure the stability of the product density gradient. (4) Curing and molding: heat curing at 40~70℃ for 0.1~0.4 h, demolding and then curing at 110~150℃ for 0.5~1.5 h to obtain a three-phase solid buoyancy material.

10. The method for preparing a three-phase solid buoyancy material based on a gradient fiber structure hollow sphere as described in claim 9, characterized in that, In steps S1 (1) and (4), the airflow velocity of the air classifier is 0.2~1 m / s, and the flow rate is 1000~3000 m³ / s. 3 / h.

Images