Customizable centimeter-scale epoxy-based composite hollow spheres and methods of making the same

Abstract

The application discloses customizable centimeter-level epoxy-based composite hollow spheres and a preparation method thereof. The epoxy-based composite hollow spheres are prepared by taking a centimeter-level light foam sphere as a core, uniformly spraying an epoxy resin mixture on the outer surface of the sphere, uniformly coating a layer of hollow glass microspheres or fiber powder, and repeating the process until the epoxy-based composite hollow spheres reach a target density, so that the requirement of customization of the static water pressure strength of the hollow spheres can be met. The customizable centimeter-level epoxy-based composite hollow spheres are composed of a light foam sphere, an epoxy resin, a curing agent, an additive, hollow glass microspheres or fiber powder. The diameter of the customizable centimeter-level epoxy-based composite hollow spheres is 1.04-5.6 cm, the wall thickness is 0.02-0.3 cm, the density is 0.1-0.6 g / cm 3 , and the static water pressure strength is 2-60 MPa. The hollow spheres prepared by the method have high strength and low density, and can be used in buoyancy materials, so that three-phase buoyancy materials with excellent properties such as high strength, low density and low water absorption rate can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of solid buoyancy material manufacturing, specifically relating to a customizable centimeter-scale epoxy-based composite hollow sphere and its preparation method. Background Technology

[0002] Buoyancy materials are closed-cell composite foams made by uniformly dispersing fillers such as hollow glass microspheres, hollow resin microspheres, and hollow metal microspheres into a polymer matrix (resin, etc.) through a specific preparation process. To minimize material density, the content of hollow glass microspheres needs to be increased. However, after reaching a certain limit, further addition of hollow glass microspheres to further reduce the density of the buoyancy material will significantly reduce its mechanical properties. Therefore, how to maintain excellent mechanical properties while reducing water absorption and density is a problem worthy of consideration and attention. The key to preparing solid buoyancy materials with excellent properties such as low density, low water absorption, and high pressure resistance is to prepare resin-based composite hollow spheres. These hollow spheres are used to fill most of the volume of the solid buoyancy material, which not only reduces production costs but, more importantly, allows for a significant reduction in the density of the solid buoyancy material due to its hollow structure, while also providing a certain degree of pressure resistance. However, there are currently no mature products of this kind in China.

[0003] To prepare the aforementioned hollow spheres, researchers both domestically and internationally have conducted extensive studies on the preparation of hollow spheres made of resin-based composite materials. In patent CN103665615B, researchers described the preparation of a fiber microsphere for solid buoyancy materials, with an apparent density of 0.35-1.2 g / cm³. 3 Clearly, the density of this sphere is too high, which does not conform to the low-density characteristics of solid buoyancy materials. More importantly, the surface of the final prepared fiber spheres has defects and deviates significantly from the spherical shape. This is because the resin system spraying and filler coating were uneven during the preparation process, failing to achieve the desired effect. This will seriously affect the density and pressure resistance of the solid buoyancy material subsequently used for preparation. In CN102557594A patent, researchers introduced the preparation of a high-strength, low-density ceramic hollow sphere. The preparation process of this hollow sphere is too cumbersome and ultimately requires high-temperature sintering at 1400-1800℃, which is energy-intensive and costly, making it unsuitable for industrial production.

[0004] This invention provides a customizable centimeter-scale epoxy-based composite hollow sphere. Based on the density of the customized hollow sphere, and through extensive preliminary research using correction curves obtained on Origin or similar data analysis software, the corresponding theoretical density value can be determined from the customized density value. Combined with empirical density formulas, the content of each component in the raw material formulation can be customized. The hollow sphere uses a centimeter-scale lightweight foam ball as its core. An epoxy resin mixture is first uniformly sprayed onto the outer surface of the sphere, followed by a uniform coating of hollow glass microspheres or fiber powder. Repeating this process allows for the preparation of an epoxy-based composite sphere preform at room temperature. Then, by heating, a customizable centimeter-scale epoxy-based composite hollow sphere is finally obtained. The resulting customizable centimeter-scale epoxy-based composite hollow sphere exhibits an excellent density of 0.1-0.6 g / cm³. 3 Its hydrostatic pressure resistance is 2-60 MPa. Summary of the Invention

[0005] One objective of this invention is to provide a customizable centimeter-scale epoxy-based composite hollow sphere. This hollow sphere addresses current issues such as poor hydrostatic pressure resistance and product deviation from the sphere shape, and provides a centimeter-scale epoxy-based composite hollow sphere with customizable density, customizable hydrostatic pressure resistance, and excellent overall performance.

[0006] Another objective of this invention is to provide a method for preparing customizable centimeter-scale epoxy-based hollow spheres. The prepared customizable centimeter-scale epoxy-based hollow spheres have a diameter of 5.6 cm, a wall thickness of 0.3 cm, and a density of 0.6 g / cm³. 3 The hollow spheres obtained exhibit a hydrostatic pressure resistance of up to 60 MPa, possessing both high strength and low density. They can be used in buoyancy materials to prepare three-phase buoyancy materials with excellent properties such as high strength, low density, and low water absorption.

[0007] The specific plan is as follows:

[0008] This invention provides a method for preparing customizable centimeter-scale epoxy composite hollow spheres. The hollow spheres consist of a lightweight foam core and an epoxy resin composite layer sequentially coating its outer surface. The epoxy resin composite layer is formed by mixing and curing epoxy resin, curing agent, additives, and hollow glass microspheres or fiber powder. The hollow spheres have a diameter of 1.04-5.6 cm, a wall thickness of 0.02-0.3 cm, a density of 0.1-0.6 g / cm³, and a hydrostatic pressure resistance of 2-60 MPa.

[0009] The specific steps are as follows:

[0010] (1) Based on the target density of the hollow sphere and the associated hydrostatic pressure resistance requirements, the corresponding theoretical density value is determined by formula (6) using a pre-established correction curve characterizing the relationship between theoretical density and actual density. Then, the mass of each component in the raw material formula, including resin, curing agent, additives, and hollow glass microspheres or fiber powder, is calculated by combining the density empirical formulas (1) to (5).

[0011] The empirical formula for density is:

[0012] m 空心球 =(m 树脂 +m 固化剂 +m 微珠 +m 纤维 ) / N+m 轻质泡沫球 Equation (1)

[0013] V 空心球 =4 / 3Π(R 轻质泡沫球 +R 壁厚 ) 3 Equation (2)

[0014] V 球壁 =(m 树脂 / ρ 树脂 +m 固化剂 / ρ 固化剂 +m 微珠 / ρ 微珠 +m 纤维 / ρ 纤维 Formula (3) / N

[0015] V 球壁 =Π Equation (4)

[0016] ρ 空心球理论 =m 空心球 / V 空心球 Equation (5)

[0017] ρ 空心球实际 =k·ρ 空心球理论 Equation (6)

[0018] Where ρ 空心球实际 ρ is the actual density value of the hollow sphere. 空心球理论 m is the theoretical density value of a hollow sphere. 树脂 m 固化剂 m 微珠 and m 纤维 m represents the mass of each component in the raw material. 轻质泡沫球 For the mass of a single lightweight foam ball, ρ 树脂 ρ 固化剂 ρ 微珠 and ρ 纤维 m is the density of each component in the raw material.空心球 For the mass of a single hollow sphere, V 空心球 V is the volume of a single hollow sphere. 球壁 Let N be the volume of the wall of a single hollow sphere, and R be the number of lightweight foam spheres. 轻质泡沫球 R is the radius of the lightweight foam ball. 壁厚 Let be the wall thickness of the hollow sphere, and k be a correction coefficient. The correction curve is obtained by preparing a series of samples with different theoretical densities under curing process conditions, measuring their actual densities, and then calculating multiple sets of ρ values. 空心球理论 With ρ 空心球实际 The curve obtained by linear fitting of the data pairs;

[0019] (2) Select lightweight foam balls that meet the size requirements;

[0020] (3) Place the lightweight foam balls into the ball rolling machine;

[0021] (4) The mixture of epoxy resin, curing agent and additives calculated in step (1) is evenly sprayed onto the outer surface of lightweight foam balls through a spray gun, and then the weighed hollow glass microspheres or fiber powder is added through a sieve to make it evenly coated on the epoxy resin surface.

[0022] (5) Repeat the process of step (4) until the total amount of the mixture of epoxy resin, curing agent and additives is sprayed to prepare epoxy composite spherical blanks;

[0023] (6) The epoxy composite sphere blank obtained in step (5) is heated and cured to obtain a customizable centimeter-sized epoxy composite hollow sphere. At the same time, a hollow sphere with customizable hydrostatic pressure resistance can also be obtained based on the density. The two are strongly correlated, and their density and hydrostatic pressure resistance meet the customization requirements.

[0024] The hydrostatic pressure resistance of the hollow spheres provided by this invention can be customized. Since, under the same material system, the hydrostatic pressure resistance of the hollow spheres is only related to the wall thickness, and the wall thickness corresponds to the density of the spheres, the hydrostatic pressure resistance of the hollow spheres is strongly correlated with the density of the hollow spheres. For details, please refer to [link to relevant documentation]. Figure 5 Meanwhile, hollow spheres are large in size and low in density, with excellent overall performance, and can be efficiently filled into buoyancy materials for use in deeper waters.

[0025] This invention provides a customizable method for preparing centimeter-scale epoxy composite hollow spheres. By adjusting the ball rolling machine and controlling conditions such as the ball rolling machine speed, spray gun spraying speed, and filler coating time, hollow spheres with regular and complete shapes and smooth surfaces can be prepared at room temperature.

[0026] This invention provides a preparation method that, based on the density of customized hollow spheres, determines the theoretical density value through a correction curve, and then combines it with empirical density formulas to customize the content of each component in the raw material formula. It also involves adjusting factors such as the rotation speed of the ball rolling machine, the amount of epoxy resin mixture sprayed each time, the coating time of each filler, and the sieve mesh size during the preparation process. This method efficiently and easily produces a series of hollow spheres that meet the target density and hydrostatic pressure resistance, suitable for pressure-resistant environments under different water depths, and fulfilling the performance requirements for solid buoyancy materials.

[0027] In some embodiments, the correction factor k is the ratio of the actual density value to the theoretical density value of the hollow sphere. The range of k is 0.7-0.9, which reflects the loss of the content of various raw materials in the designed formula during the actual preparation process. The k value is affected by process parameters such as the rotation speed of the ball rolling machine, the spraying time of each epoxy resin mixture, the coating time of each filler, and the mesh size of the sieve during the preparation process.

[0028] In some implementations, the correction curve is obtained by using Origin or similar data analysis software to convert ρ... 空心球理论 With ρ 空心球实际 The data were obtained by linear regression fitting, and the coefficient of determination R² of the linear equation is greater than 0.95.

[0029] In some embodiments, the lightweight foam ball is one of polyethylene foam ball, polypropylene foam ball, and polystyrene foam ball, and the diameter of the lightweight foam ball used to prepare the hollow ball is at least one of 1-5 cm.

[0030] In some embodiments, the sieve used to prepare the hollow spheres has a mesh size of at least one between 10 and 200 mesh.

[0031] In some embodiments, the actual density of the hollow glass microspheres used to prepare the hollow spheres is 0.15-0.6 g / cm³. 3 At least one of the following, the glass fiber having a length of at least 3-50 mm, and the carbon fiber having a length of at least 6-25 mm.

[0032] In some embodiments, in step (2) of preparing hollow spheres, the number of lightweight foam spheres selected is 200-5000; in step (3) of preparing hollow spheres, the rotation speed of the rolling ball machine is 5-20 rpm; in step (4), the rotation speed of the rolling ball machine is 20-50 rpm, the nozzle diameter of the spray gun is 1.0-4.0, the time for each spraying of the epoxy resin system is 20-80s, and the coating time is 10-60s.

[0033] In some embodiments, in step (6) of preparing hollow spheres, the spheres are heated and cured in a blower oven. The heating process is based on the curing process of epoxy resin. The heating temperature is first raised to 40-80℃ and the heating time is 4-20 h. Then the heating temperature is raised to 80℃-150℃ and the heating time is 1-10 h.

[0034] In some embodiments, the epoxy resin system materials for preparing the hollow spheres are expressed in parts by weight as follows: 70-100 parts epoxy resin, 30-90 parts curing agent, 0.001-0.005 parts diluent, and 0.01-0.05 parts coupling agent.

[0035] In some embodiments, the epoxy resin used to prepare the hollow spheres is one or more of bisphenol A type epoxy resin, alicyclic epoxy resin, and glycidyl ester epoxy resin; the curing agent is one or more of aliphatic amine, aromatic amine, and acid anhydride substances; the diluent is one or more of glycidyl ether substances; and the coupling agent is one or two of γ-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. Since the epoxy resin system is used for spray gun application, it requires good flowability and low viscosity, with a viscosity of 100-400 cps.

[0036] In some specific embodiments, the preparation method includes: based on the density of customized hollow spheres, through extensive preliminary research using correction curves obtained on Origin or similar data analysis software, the customized density value can determine the corresponding theoretical density value. Combined with empirical density formulas, the content of each component in the raw material formulation can be customized. Then, 200-5000 lightweight foam spheres with a diameter of 1-5 cm are selected. The lightweight foam spheres are then placed in a ball rolling machine with a rotation speed of 5-20 rpm. A mixture of epoxy resin, curing agent, and additives, weighed according to the customized formulation, is then uniformly sprayed onto the outer surface of the lightweight foam spheres through a spray gun with a nozzle diameter of 1.0-4.0 mm. The ball rolling machine rotates at 20-50 rpm, and each spraying of the epoxy resin system takes 20-80 seconds. Hollow glass microspheres or fiber powder are then added through a sieve with a mesh size of 10-200 mesh to uniformly coat the epoxy resin surface for 10-60 seconds. s; Repeat the above steps and parameters until the total amount of epoxy resin system is sprayed, and the parameter indicators of the ball reach the customized target value, thus initially preparing epoxy composite spheres; Finally, heat and cure the epoxy composite spheres obtained above. The heating temperature is first raised to 40-80℃ and the heating time is 4-20h, and then the heating temperature is raised to 80℃-150℃ and the heating time is 1-10h. Finally, customized centimeter-scale epoxy composite hollow spheres are prepared, and hollow spheres with customized hydrostatic pressure resistance can also be obtained according to the density.

[0037] In some specific embodiments of the present invention, when epoxy resin and hollow glass microspheres or fiber powder are added to prepare hollow spheres, the mass ratio of epoxy resin to hollow glass microspheres or fiber powder is 1:2-30.

[0038] Another objective of this invention is to provide an application of customizable centimeter-scale epoxy-based composite hollow spheres, which are used in buoyancy materials to efficiently and cost-effectively prepare three-phase buoyancy materials with excellent properties such as high strength, low density, and low water absorption. Attached Figure Description

[0039] Figure 1 Photograph of a customizable centimeter-scale epoxy composite hollow sphere (the filler used in the figure is hollow glass microspheres).

[0040] Figure 2 Photograph of a customizable centimeter-scale epoxy composite hollow sphere (the filler used in the image is glass fiber powder).

[0041] Figure 3 Photograph of a customizable centimeter-scale epoxy composite hollow sphere (the filler used in the image is carbon fiber powder).

[0042] Figure 4 It is a correction curve fitted based on data from several customized hollow spheres, with a polystyrene foam sphere of 3 cm in diameter as the core.

[0043] Figure 5 This is a graph showing the relationship between the hydrostatic pressure resistance and density of a hollow sphere constructed with a 3 cm diameter polystyrene foam core and an alicyclic epoxy resin / aliphatic amine curing agent / a certain type of hollow glass microsphere system. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments. However, the scope of protection of the present invention is not limited to the following embodiments. Any non-essential adjustments and modifications made to the present invention based on the above description shall still fall within the scope of protection of the present invention.

[0045] I. The process of establishing and fitting the correction curve

[0046] Taking the establishment of a correction curve for a system of alicyclic epoxy resin / aliphatic amine curing agent / a certain type of hollow glass microspheres with a diameter of 3 cm as the core as an example:

[0047] Step 1: Basic Data Collection and Sample Preparation

[0048] The number of polystyrene foam balls was set to 600, the initial rotation speed of the ball rolling machine was 10 rpm, the rotation speed during the spraying stage was 25 rpm, the spray gun nozzle diameter was 3.0 mm, the single spraying time was 50 s, the sieve mesh size was 100 mesh, and the single coating time was 50 s. The curing process was 80℃ / 8h + 100℃ / 6h.

[0049] Design theoretical formulations: Design multiple different experimental schemes;

[0050] Experimental protocol Alicyclic epoxy resin (g) Curing agent (g) Diluent (g) Coupling agent (g) Microbeads (g) A 500 150 1 5 1100 B 800 240 1.6 8 1760 C 1100 330 2.2 11 2420 D 1400 420 2.8 14 3080 E 1700 510 3.4 17 3740

[0051] Calculate the theoretical density: For each scheme, calculate its ρ according to the empirical density formulas (Equations (1)-(5)). 空心球理论 The densities of the raw materials required for the calculation are known values.

[0052] m 空心球 =(m 树脂 +m 固化剂 +m 微珠 +m 纤维 ) / N+m 轻质泡沫球 Equation (1)

[0053] V 空心球 =4 / 3Π(R 轻质泡沫球 +R 壁厚 ) 3 Equation (2)

[0054] V 球壁 =(m 树脂 / ρ 树脂 +m 固化剂 / ρ 固化剂 +m 微珠 / ρ 微珠 +m 纤维 / ρ 纤维 Formula (3) / N

[0055] V 球壁 =Π Equation (4)

[0056] ρ 空心球理论 =m 空心球 / V 空心球 Equation (5)

[0057] Preparation and Measurement: Following the curing process parameters described above, five batches of hollow sphere samples were prepared for each group of procedures. At least 30 intact spheres were randomly selected from each batch, and their mass and diameter were measured. The actual density of each sphere was calculated, and the average value was taken as the ρ of that batch. 空心球实际 .

[0058] Step Two: Data Fitting and Modeling

[0059] The above multiple groups (ρ) 空心球理论 , ρ 空心球实际 The data was entered into Origin or similar data analysis software for linear fitting. Please refer to [link / reference needed] for details. Figure 4 .

[0060] The fitted curve equation is: ρ 空心球实际 =0.824 * ρ 空心球理论 Equation (6); the coefficient of determination for this linear relationship is R² = 0.998.

[0061] Therefore, under this material system and process window, the correction factor k = 0.824.

[0062] Meanwhile, taking a 3 cm diameter polystyrene foam sphere as the core, and using an alicyclic epoxy resin / aliphatic amine curing agent / a certain type of hollow glass microsphere system as an example, the relationship between the hydrostatic pressure resistance and density of the hollow sphere is examined:

[0063] The number of polystyrene foam balls was set to 600, the initial rotation speed of the ball rolling machine was 10 rpm, the rotation speed during the spraying stage was 25 rpm, the spray gun nozzle diameter was 3.0 mm, the single spraying time was 50 s, the sieve mesh size was 100 mesh, and the single coating time was 50 s. The curing process was 80℃ / 8h + 100℃ / 6h.

[0064] Design theoretical formulations: Design multiple different experimental schemes;

[0065] Experimental protocol Alicyclic epoxy resin (g) Curing agent (g) Diluent (g) Coupling agent (g) Microbeads (g) A 600 180 1.2 6 1320 B 900 270 1.8 9 1980 C 1200 360 2.4 12 2640 D 1500 450 3 15 3300 E 1800 540 3.6 18 3960 F 2100 630 4.2 21 4620 G 2400 720 4.8 24 5280 H 2700 810 5.4 27 5940

[0066] Preparation and Measurement: Following the curing process parameters described above, eight batches of hollow sphere samples were prepared for each procedure. At least 30 intact spheres were randomly selected from each batch, and their mass, diameter, and wall thickness were measured. The actual density of each sphere was calculated, and the average value was taken as the ρ of that batch. 空心球实际 Next, the prepared hollow spheres were subjected to hydrostatic pressure tests. The measurements and performance tests of the hollow spheres are shown in the table below.

[0067] Experimental protocol <![CDATA[Ball density (g / cm 3 )]]> Mass (g) Diameter (cm) Wall thickness (cm) Hydrostatic pressure resistance (MPa) A 0.148 2.54 3.2 0.10 4 B 0.201 3.71 3.28 0.14 7 C 0.248 5.10 3.40 0.20 12 D 0.303 6.92 3.52 0.26 18 E 0.349 8.96 3.66 0.33 24 F 0.404 11.61 3.80 0.40 30 G 0.453 14.73 3.96 0.48 37 H 0.502 19.20 4.18 0.59 46

[0068] Therefore, under this material system and process window, the relationship between the hydrostatic pressure resistance and density of the hollow spheres is as follows: Figure 5 As shown, they have a strong correlation.

[0069] II. Customized Hollow Spheres

[0070] Example 1: Custom-made hollow spheres with a density of 0.25 g / cm³

[0071] A method for preparing customizable centimeter-scale epoxy-based hollow spheres includes the following steps:

[0072] (1) Formulation design: target density ρ 目标 =0.25 g / cm³. Using the correction curve established above (k=0.824), the required theoretical density is calculated: ρ 理论 =0.25 / 0.824≈0.303 g / cm³. Substituting this value into the empirical formula for density, and combining it with the density of each raw material (ρ... 树脂 =1.15 g / cm³, ρ 固化剂 =0.98 g / cm³, ρ 微珠 =0.38 g / cm³), calculate the specific amount of raw materials used. The mass ratio of epoxy resin mixture to hollow glass microspheres is approximately 1:2.2, see Raw Material Formulation Table 1;

[0073] (2) Raw materials: 100 parts by weight of alicyclic epoxy resin, 30 parts by weight of aliphatic amine curing agent, 0.002 parts by weight of diluent butyl glycidyl ether, 0.01 parts by weight of coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), and 220 parts by weight of hollow glass microspheres.

[0074] (3) Preparation: Select 600 polystyrene foam balls with an average diameter of about 3 cm. Place the polystyrene foam balls into a rolling ball machine at a speed of 10 rpm. The mixture of epoxy resin, curing agent, and additives weighed according to the customized formula in Table 1 is evenly sprayed onto the outer surface of the polystyrene foam balls through a 3.0 mm nozzle. At this time, the speed of the rolling ball machine is 25 rpm, and the spraying time of the epoxy resin system is 50 s. Then, hollow glass microspheres are added through a sieve with a mesh size of 100 mesh to evenly coat the epoxy resin surface. The coating time is 50 s. Repeat this spraying-coating cycle until the material is used up. Finally, heat the epoxy composite spheres obtained above to cure. The heating temperature is first raised to 80℃ and the heating time is 8 h. Then the heating temperature is raised to 100℃ and the heating time is 6 h. Finally, customized centimeter-sized epoxy composite hollow spheres are prepared (see the actual picture). Figure 1 ).

[0075] Table 1 Raw material formulation in Example 1

[0076] raw material Number of weights Alicyclic epoxy resin 100 Aliphatic amine curing agents 30 Butyl glycidyl ether 0.002 γ-glycidoxypropyltrimethoxysilane 0.01 Hollow glass microspheres 220

[0077] The customizable centimeter-scale epoxy-based hollow spheres prepared in this embodiment have a sphere density of 0.248 g / cm³. 3 The total mass is 5.10 g, the average diameter is 3.40 cm, the average wall thickness of the spherical shell is 0.20 cm, and the hydrostatic pressure resistance is 12 MPa.

[0078] Example 2: Custom-made hollow spheres with a density of 0.31 g / cm³

[0079] A method for preparing customizable centimeter-scale epoxy-based hollow spheres includes the following steps:

[0080] (1) Formulation design: A correction curve was pre-established using the glass fiber powder system, following the method for establishing the correction curve in Example 1 (k=0.85). Target density ρ 目标 =0.31 g / cm³, inversely calculate ρ 理论 ≈0.365 g / cm³. Calculations show that the mass ratio of epoxy resin mixture to glass fiber powder is approximately 1:2.8, as shown in Raw Material Formulation Table 2.

[0081] (2) Raw materials: 100 parts by weight of alicyclic epoxy resin, 35 parts by weight of aliphatic amine curing agent, 0.001 parts by weight of diluent alkyl glycidyl ether, 0.02 parts by weight of coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), and 280 parts by weight of glass fiber powder.

[0082] (3) Preparation method: Select polypropylene foam balls with an average diameter of about 3 cm, and the number of polypropylene foam balls is 400; put the polypropylene foam balls into a rolling ball machine with a rotation speed of 15 rpm; the mixture of epoxy resin, curing agent and additives weighed according to the customized formula table 2 is evenly sprayed onto the outer surface of the polypropylene foam balls through a spray gun with a nozzle diameter of 2.5 mm. At this time, the rotation speed of the self-made ball machine is 30 rpm, and the spraying time of the epoxy resin system is 60 s. Then, glass fiber powder is added through a sieve with a mesh size of 20 to evenly coat the epoxy resin surface. The coating time is 40 s. Repeat this spraying-coating cycle until the material is used up. Finally, heat the epoxy composite ball obtained above to cure. The heating temperature is first raised to 70℃ and the heating time is 10 h. Then the heating temperature is raised to 120℃ and the heating time is 3 h. Finally, a customizable centimeter-sized epoxy composite hollow ball is prepared (see the actual picture). Figure 2 ).

[0083] Table 2 Raw material formula in Example 2

[0084] raw material Number of weights Alicyclic epoxy resin 100 Aliphatic amine curing agents 35 alkylene glycidyl ethers 0.001 γ-glycidoxypropyltrimethoxysilane 0.02 glass fiber powder 280

[0085] The customizable centimeter-scale epoxy-based hollow spheres prepared in this embodiment have a sphere density of 0.314 g / cm³. 3 The total mass is 5.29 g, the average diameter is 3.18 cm, the average wall thickness of the spherical shell is 0.09 cm, and the hydrostatic pressure resistance is 25 MPa.

[0086] Example 3: Custom-made hollow spheres with a density of 0.28 g / cm³

[0087] A method for preparing customizable centimeter-scale epoxy-based hollow spheres includes the following steps:

[0088] (1) Formulation design: A correction curve was pre-established using the carbon fiber powder system, following the method for establishing the correction curve in Example 1 (k=0.80). Target density ρ 目标 =0.28 g / cm³, inversely calculate ρ 理论 =0.35 g / cm³. Calculations show that the mass ratio of epoxy resin mixture to carbon fiber powder is approximately 1:2.4, as shown in Raw Material Formulation Table 3.

[0089] (2) Raw materials: 100 parts by weight of alicyclic epoxy resin, 40 parts by weight of aliphatic amine curing agent, 0.002 parts by weight of diluent butyl glycidyl ether, 0.02 parts by weight of coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), and 240 parts by weight of carbon fiber powder.

[0090] (3) Preparation method: Select 800 polystyrene foam balls with an average diameter of about 3 cm. Place the polystyrene foam balls into a rolling ball machine with a rotation speed of 5 rpm. The mixture of epoxy resin, curing agent, and additives weighed according to the customized formula in Table 3 is evenly sprayed onto the outer surface of the polystyrene foam balls through a spray gun with a nozzle diameter of 4.0 mm. At this time, the rotation speed of the rolling ball machine is 20 rpm, and the spraying time of the epoxy resin system is 40 s. Then, carbon fiber powder is added through a sieve with a mesh size of 30 and the coating time is 45 s. Repeat this spraying-coating cycle until the material is used up. Finally, heat the epoxy composite spheres obtained above to cure. The heating temperature is first raised to 50℃ and the heating time is 12 h. Then the heating temperature is raised to 130℃ and the heating time is 2 h. Finally, a customizable centimeter-sized epoxy composite hollow sphere is prepared (see the actual picture). Figure 3 ).

[0091] Table 3 Raw material formulation in Example 3

[0092] raw material Number of weights Alicyclic epoxy resin 100 Aliphatic amine curing agents 40 Butyl glycidyl ether 0.002 γ-glycidoxypropyltrimethoxysilane 0.02 carbon fiber powder 240

[0093] The customizable centimeter-scale epoxy-based hollow spheres prepared in this embodiment have a sphere density of 0.278 g / cm³. 3 The total mass is 4.59 g, the average diameter is 3.16 cm, the average wall thickness of the spherical shell is 0.08 cm, and the hydrostatic pressure resistance is 30 MPa.

[0094] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention.

Claims

1. A customizable centimeter-scale epoxy-based composite hollow sphere, characterized in that: The hollow sphere consists of a lightweight foam core and an epoxy resin composite material layer sequentially covering its outer surface. The epoxy resin composite material layer includes epoxy resin, curing agent, additives, and hollow glass microspheres or fiber powder. The hollow sphere has a diameter of 1.04-5.6 cm, a wall thickness of 0.02-0.3 cm, a density of 0.1-0.6 g / cm3, and a hydrostatic pressure resistance of 2-60 MPa. The hollow sphere is prepared by the following method: (1) Based on the target density of the hollow sphere and the associated hydrostatic pressure resistance requirements, the corresponding theoretical density value is determined by formula (6) using a pre-established correction curve characterizing the relationship between theoretical density and actual density. Then, the mass of each component in the raw material formula, including resin, curing agent, additives, and hollow glass microspheres or fiber powder, is calculated by combining the density empirical formulas (1) to (5). The empirical formula for density is: m 空心球 =(m 树脂 +m 固化剂 +m 微珠 +m 纤维 ) / N+m 轻质泡沫球 Equation (1) V 空心球 =4 / 3Π(R 轻质泡沫球 +R 壁厚 ) 3 formula (2) V 球壁 =(m 树脂 / ρ 树脂 +m 固化剂 / ρ 固化剂 +m 微珠 / ρ 微珠 +m 纤维 / ρ 纤维 ) / N Equation (3) V 球壁 =Π Equation (4) ρ 空心球理论 =m 空心球 / V 空心球 Equation (5) r 空心球实际 =k·r 空心球理论 expression(6) Where, ρ 空心球实际 ρ is the actual density value of the hollow sphere. 空心球理论 m is the theoretical density value of a hollow sphere. 树脂 m 固化剂 m 微珠 and m 纤维 m represents the mass of each component in the raw material. 轻质泡沫球 For the mass of a single lightweight foam ball, ρ 树脂 ρ 固化剂 ρ 微珠 and ρ 纤维 m is the density of each component in the raw material. 空心球 For the mass of a single hollow sphere, V 空心球 V is the volume of a single hollow sphere. 球壁 Let N be the volume of the wall of a single hollow sphere, and R be the number of lightweight foam spheres. 轻质泡沫球 R is the radius of the lightweight foam ball. 壁厚 Let be the wall thickness of the hollow sphere, and k be a correction coefficient. The correction curve is obtained by preparing a series of samples with different theoretical densities under curing process conditions, measuring their actual densities, and then calculating multiple sets of ρ values. 空心球理论 With ρ 空心球实际 The curve obtained by linear fitting of the data pairs; (2) Select lightweight foam balls that meet the size requirements; (3) Place the lightweight foam balls into the ball rolling machine; (4) The mixture of epoxy resin, curing agent and additives calculated in step (1) is evenly sprayed onto the outer surface of lightweight foam balls through a spray gun, and then the weighed hollow glass microspheres or fiber powder is added through a sieve to make it evenly coated on the epoxy resin surface. (5) Repeat the process of step (4) until the total amount of the mixture of epoxy resin, curing agent and additives is sprayed to prepare epoxy composite spherical blanks; (6) The epoxy composite sphere blank obtained in step (5) is heated and cured to obtain a customizable centimeter-sized epoxy composite hollow sphere, whose density and hydrostatic pressure resistance meet the customization requirements.

2. The centimeter-scale epoxy-based hollow sphere according to claim 1, characterized in that: The correction factor k is the ratio of the actual density value to the theoretical density value of the hollow sphere, and the value of k ranges from 0.7 to 0.

9.

3. The centimeter-scale epoxy-based composite hollow sphere according to claim 2, characterized in that: The correction curve is obtained by using Origin or similar data analysis software to convert ρ 空心球理论 With ρ 空心球实际 The data were obtained by linear regression fitting, and the coefficient of determination R² of the linear equation is greater than 0.

95.

4. The centimeter-scale epoxy-based hollow sphere according to claim 1, characterized in that: The lightweight foam ball is one of polyethylene foam balls, polypropylene foam balls, and polystyrene foam balls, and the diameter of the lightweight foam ball is 1-5 cm.

5. The centimeter-scale epoxy-based hollow sphere according to claim 1, characterized in that: When adding epoxy resin and hollow glass microspheres or fiber powder, the mass ratio of epoxy resin to hollow glass microspheres or fiber powder is controlled to be 1:2-30.

6. The centimeter-scale epoxy-based composite hollow sphere according to claim 5, characterized in that: The epoxy resin system material, expressed in parts by weight, comprises the following components: 70-100 parts epoxy resin, 30-90 parts curing agent, 0.001-0.005 parts diluent, and 0.01-0.05 parts coupling agent.

7. The centimeter-scale epoxy-based hollow sphere according to claim 6, characterized in that: The epoxy resin is one or more of bisphenol A type epoxy resin, alicyclic epoxy resin, and glycidyl ester epoxy resin; the curing agent is one or more of aliphatic amine, aromatic amine, and acid anhydride; the diluent is one or more of glycidyl ether; and the coupling agent is one or both of γ-aminopropyltriethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. The epoxy resin system is used for spray gun application, therefore the epoxy resin system requires good fluidity and low viscosity, with a viscosity of 100-400 cps.

8. The centimeter-scale epoxy-based composite hollow sphere according to claim 1, characterized in that: The actual density of the hollow glass microspheres is 0.15-0.6 g / cm³. 3 The fiber powder is one or more of glass fiber powder and carbon fiber powder, wherein the length of the glass fiber is 3-50 mm and the length of the carbon fiber is 6-25 mm.

9. The centimeter-scale epoxy-based hollow sphere according to claim 1, characterized in that: In step (2), the number of lightweight foam balls selected is 200-5000; in step (3), the initial rotation speed of the ball rolling machine is 5-20 rpm; in step (4), the rotation speed of the ball rolling machine during spraying is 20-50 rpm, the nozzle diameter of the spray gun is 1.0-4.0 mm, the spraying time is 20-80 s, the mesh size of the sieve is 10-200 mesh, and the coating time is 10-60 s; in step (6), the heating and curing are carried out in a forced-air oven, using a stepped heating program: first, the temperature is raised to 40-80℃ and held for 4-20 h, then the temperature is raised to 80℃-150℃ and held for 1-10 h.

10. The application of a customizable centimeter-scale epoxy-based composite hollow sphere as described in any one of claims 1-9 in the preparation of solid buoyancy materials.

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