A positive pressure assisted vacuum infusion manufacturing process for preparing a buoyancy compensating material

Abstract

This invention belongs to the field of marine engineering technology, and particularly relates to a positive pressure assisted vacuum casting process for preparing buoyancy compensation materials. The positive pressure assisted vacuum casting process for preparing buoyancy compensation materials includes the following steps: Step 1: Filling a mold with 60-200 parts of material with a density grade of 0.10-0.35 g / cm³. 3 For composite hollow spheres, a vacuum is applied to the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Step 2: Mix 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of DMP-30, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes at a constant speed. This invention provides a positive pressure assisted vacuum casting process for preparing buoyancy compensation materials.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering technology, and in particular relates to a positive pressure assisted vacuum casting process for preparing buoyancy compensation materials. Background Technology

[0002] Existing technology:

[0003] In recent years, with the continuous expansion of my country's marine mineral and oil and gas resource development, the demand for various marine engineering materials, represented by solid buoyancy materials, has increased significantly. Taking drilling riser pontoons, commonly used in offshore oil extraction, as an example, the annual domestic demand exceeds one thousand meters. Traditional solid buoyancy materials mainly use epoxy resin and hollow glass microspheres as raw materials. Although they have excellent performance, they are also costly and have high material density.

[0004] Existing solid buoyancy materials mainly use epoxy resin and hollow glass microspheres as raw materials, and are prepared using processes such as compression molding and casting. Using epoxy resin and hollow microspheres as the main raw materials results in high costs, making it unsuitable for producing large buoyancy compensation devices such as riser buoyancy blocks. Furthermore, due to the limitation on the amount of hollow glass microspheres that can be added to the formula, the bulk density of the material is difficult to lower than 0.35 g / cm³. 3 The net buoyancy provided by the material per unit volume is relatively low.

[0005] The difficulty and significance of solving the above technical problems:

[0006] Therefore, based on these current problems, providing a positive pressure assisted vacuum casting process for preparing buoyancy compensation materials has significant practical value. Summary of the Invention

[0007] The purpose of this application is to provide a positive pressure assisted vacuum casting process for preparing buoyancy compensation materials in order to solve the technical problems in the prior art.

[0008] The technical solution adopted in this application embodiment to solve the technical problems existing in the prior art is as follows:

[0009] A positive pressure assisted vacuum casting process for preparing buoyancy compensation materials includes the following steps:

[0010] Step 1: Fill the mold with 60-200 parts of a material with a density grade of 0.10-0.35 g / cm³. 3 For composite hollow spheres, a vacuum is applied to the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0011] Step 2: Mix 100 parts of E51 epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593 curing agent, 1-3 parts of DMP-30, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes.

[0012] Step 3: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0013] Step 4: Pour the casting material into the mold and cure the mold at 120-150℃.

[0014] The embodiments of this application may also employ the following technical solutions:

[0015] In the above-described positive pressure assisted vacuum casting process for preparing buoyancy compensation materials, further, before step one, there is the following step:

[0016] A mixture of 1%-5% by weight of E51 epoxy resin, methyltetrahydrophthalic anhydride, 593 curing agent, DMP-30, and γ-aminopropyltriethoxysilane was mixed with 60-200 parts of a density grade of 0.10-0.35 g / cm³ in a ball rolling machine. 3 The composite hollow spheres are mixed at room temperature for 3-5 minutes, the ball rolling machine speed is 30-60 rpm, and the amount of resin is 1%-5% of the mass of the composite hollow spheres.

[0017] In the above-mentioned positive pressure assisted vacuum casting preparation process for preparing buoyancy compensation materials, the mass ratio of E51 epoxy resin, methyltetrahydrophthalic anhydride, 593 curing agent, DMP-30, and γ-aminopropyltriethoxysilane is further 100:70:3:3:2.

[0018] In the above-mentioned positive pressure assisted vacuum casting preparation process for preparing buoyancy compensation materials, further, in step four, the casting material is injected into the mold under a pressure of 0.2-0.5 MPa.

[0019] In the above-described positive pressure assisted vacuum casting process for preparing buoyancy compensation materials, further, before step one, there is the following step:

[0020] A mixture of 1%-5% by weight of E51 epoxy resin, methyltetrahydrophthalic anhydride, 593 curing agent, DMP-30, and γ-aminopropyltriethoxysilane was mixed with 60-200 parts of a density grade of 0.10-0.35 g / cm³ in a ball rolling machine. 3The composite hollow spheres are mixed at room temperature for 3-5 minutes, the ball rolling machine speed is 30-60 rpm, and the amount of resin is 1%-5% of the mass of the composite hollow spheres.

[0021] A material for preparing buoyancy compensation, wherein the material is prepared by the positive pressure assisted vacuum casting process described in any one of the preceding claims.

[0022] One or more technical solutions provided in the embodiments of this application have at least the following beneficial effects:

[0023] 1. This invention incorporates low-density composite hollow spheres into the material formulation system, with the spheres comprising over 60% of the material's volume. Because composite hollow spheres possess advantages such as low cost, low density, closed pores, few defects, and uniform size, they not only significantly reduce raw material costs but also substantially decrease the overall density of the material.

[0024] 2. Due to the addition of composite hollow spheres, conventional casting methods cannot fully fill the gaps between the composite hollow spheres with the castable material. This invention impregnates the surface of the composite hollow spheres with resin and applies positive pressure to the castable material during the casting process to improve the density of the internal structure of the material, so as to ensure the mechanical properties and yield of the product.

[0025] 3. In the casting process, the present invention applies appropriate positive pressure to the casting material, and the voids inside the product are quickly and completely filled by the casting material. Therefore, the density is high, the defects in the product are reduced, the defect rate is reduced, and the mechanical properties are improved. Moreover, the production efficiency is also improved due to the shortened casting process time.

[0026] 4. Before the composite hollow sphere is filled into the mold, the surface of the hollow sphere is impregnated with epoxy resin, so that the casting material can fully fill the internal voids under a small pressure, avoiding damage to the composite hollow sphere due to excessive pressure, which would cause the density of the product to increase; at the same time, it improves the interfacial bonding effect between the casting material and the composite hollow sphere, resulting in better mechanical properties.

[0027] 5. Compared to traditional non-foamed buoyancy materials, this invention has a lower density; it also effectively alleviates the problems of decreased mechanical properties and increased water absorption caused by using technical means to reduce density. Since the composite hollow spheres account for more than 60% of the material's volume, its unit volume cost is far lower than that of epoxy resin and hollow glass microspheres, thus reducing its raw material cost by more than 30% compared to traditional solid buoyancy materials. Due to the impregnation of the composite hollow sphere surface and the application of positive pressure to the castable during casting, the internal density of the cast body is increased, defects are reduced, mechanical properties are better, and the production cycle is shorter. Therefore, the method described in this invention is very suitable for the production of large buoyancy compensation devices such as riser buoyancy blocks. Attached Figure Description

[0028] The technical solutions of the embodiments of this application will be further described in detail below with reference to the accompanying drawings. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of this application. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0029] Figure 1 This is a process flow diagram for preparing buoyancy materials using the positive pressure assisted vacuum casting method. Detailed Implementation

[0030] This invention uses composite hollow spheres, epoxy resin and its modifiers, hollow glass microspheres, and chopped fibers as main raw materials. The preparation method of the composite hollow spheres is as follows:

[0031] Step 1: Prepare the spherical shell base liquid using epoxy resin and a portion of rigid fibers as the main raw materials;

[0032] Step 2: Add room temperature and medium temperature composite curing agent and accelerator to the spherical shell base liquid and stir evenly to form a spherical shell mixture;

[0033] Step 3: Immerse the lightweight foamed balls in the shell-mixture solution until fully soaked, then remove them and place them on a wire mesh at room temperature until the shell-mixture solution on the lightweight foamed balls is drained off, forming resin-based hollow balls;

[0034] Step 4: Put the resin-based hollow spheres and the remaining rigid fibers into the ball rolling machine, start the ball rolling machine, until a rigid fiber composite sphere shell is formed; then take it out and let it stand in a room temperature environment for 12-24 hours until the sphere shell loses its fluidity;

[0035] Step 5: Repeat steps 1-4 as needed to prepare multi-layer composite spherical shells until the density of the composite hollow spheres reaches the target value. Then, keep them at 60-100℃ for 2-4 hours to complete the curing process. After natural cooling, they are ready for use.

[0036] Composite hollow spheres offer advantages such as low cost, low density, and closed pores. Adding them to traditional buoyancy materials can significantly reduce raw material costs and decrease the material's bulk density. The casting method further enhances production efficiency and eliminates the need for post-processing. However, traditional casting methods require well-flowable refractory materials, and the addition of composite hollow spheres increases the casting difficulty. When the buoyancy device is large, internal defects due to insufficient refractory filling can occur, severely impacting the material's mechanical properties and reliability.

[0037] This embodiment addresses the above problems with the following specific formula:

[0038] Epoxy resin: E51, 100 parts;

[0039] Curing agent: Methyltetrahydrophthalic anhydride, 60-80 parts; 593 curing agent, 0-3 parts;

[0040] Curing accelerator: DMP-30, namely 2,4,6-tris(dimethylaminomethyl)phenol, 1-3 parts;

[0041] Coupling agent: γ-aminopropyltriethoxysilane, 2 parts;

[0042] Composite hollow spheres (density grade: 0.10-0.35 g / cm³) 3 ), 60-200 copies;

[0043] Hollow glass microspheres (density grade: 0.15-0.38 g / cm³) 3 ), 35-80 copies;

[0044] Short-cut glass fiber powder (15-120μm), 0-2 parts.

[0045] The main process steps are as follows:

[0046] Step 1: Assemble the mold and verify its sealing performance;

[0047] Step 2: Mix epoxy resin, curing agent, curing accelerator, and coupling agent according to the formulation ratio of this embodiment, and mix with composite hollow spheres in a ball rolling machine at 10-80℃ for 3-5 minutes. The ball rolling machine speed is 30-60 rpm, and the amount of epoxy resin is 1%-5% of the mass of the composite hollow spheres.

[0048] Step 3: Fill the mold with the composite hollow spheres, and evacuate the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0049] Step 4: Mix epoxy resin, curing agent, curing accelerator and coupling agent in proportion, and stir at a constant speed for 5-15 minutes in a vacuum heating container at 40-60℃.

[0050] Step 5: Add hollow glass microspheres and chopped fiber powder in proportion, and stir at a uniform speed for 10-30 minutes under vacuum at 40-60℃ to obtain the castable.

[0051] Step Six: Inject the castable refractory into the mold under a pressure of 0.2-3.0 MPa;

[0052] Step 7: Cur the mold at 120-150℃;

[0053] Step 8: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0054] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0055] Comparative Examples

[0056] Step 1: Assemble the mold and verify its sealing performance;

[0057] Step 2: Evacuate the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0058] Step 3: Mix 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes at a uniform speed.

[0059] Step 4: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0060] Step 5: Inject the refractory material into the mold under normal pressure;

[0061] Step 6: Cur the mold at 120-150℃ for 4 hours;

[0062] Step 7: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0063] The casting obtained in this comparative embodiment has a bulk density of 0.53-0.70 g / cm³. 3 Although the product has a good appearance, its high bulk density and high raw material cost make it unsuitable for practical use.

[0064] Example 1

[0065] To reduce density and lower costs, composite hollow spheres were added to the raw materials based on the comparative examples, thereby reducing raw material costs and product bulk density.

[0066] The process flow for this embodiment is as follows:

[0067] Step 1: Assemble the mold and verify its sealing performance;

[0068] Step 2: Fill the mold with 60-200 parts of a material with a density grade of 0.10-0.35 g / cm³. 3 For composite hollow spheres, a vacuum is applied to the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0069] Step 3: Mix 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes at a uniform speed.

[0070] Step 4: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0071] Step 5: Inject the refractory material into the mold under normal pressure;

[0072] Step 6: Cur the mold at 120-150℃ for 4 hours;

[0073] Step 7: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0074] The casting obtained in this embodiment has a bulk density of 0.24-0.46 g / cm³. 3 The compressive strength is 4-21 MPa, and the water absorption rate of the bare material after 24 hours is 3-7%. Compared with the comparative example, the bulk density of the product in this example is significantly reduced, and the net buoyancy per unit volume is thus significantly improved.

[0075] Example 2

[0076] Based on Example 1, a certain positive pressure is applied to the castable material during casting to promote its full filling of the gap between the mold and the composite hollow sphere, thereby improving the material's density. The specific process is as follows:

[0077] Step 1: Assemble the mold and verify its sealing performance;

[0078] Step 2: Fill the mold with 60-200 parts of a material with a density grade of 0.10-0.35 g / cm³. 3 For composite hollow spheres, a vacuum is applied to the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0079] Step 3: Mix 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes at a uniform speed.

[0080] Step 4: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0081] Step 5: Inject the castable refractory into the mold under a pressure of 2.0-3.0 MPa;

[0082] Step 6: Cur the mold at 120-150℃ for 4 hours;

[0083] Step 7: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0084] The casting obtained in this embodiment has a bulk density of 0.39-0.62 g / cm³. 3 The compressive strength is 9-28 MPa, and the water absorption rate of the bare material after 24 hours is 0.5-0.8%. Compared with Example 1, this example shows that applying sufficient positive pressure to the castable promotes its filling of the gap between the mold and the composite hollow sphere, resulting in a well-formed product with no obvious defects. Therefore, its compressive strength is significantly improved, and the water absorption rate of the bare material after 24 hours is greatly reduced.

[0085] Example 3

[0086] Based on Example 2, the positive pressure during casting is appropriately reduced to avoid increased product density due to breakage of the composite hollow spheres. The specific process is as follows:

[0087] Step 1: Assemble the mold and verify its sealing performance;

[0088] Step 2: Fill the mold with 60-200 parts of a material with a density grade of 0.10-0.35 g / cm³. 3 For composite hollow spheres, a vacuum is applied to the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0089] Step 3: Mix 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes at a uniform speed.

[0090] Step 4: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0091] Step 5: Inject the castable refractory into the mold under a pressure of 0.2-0.5 MPa;

[0092] Step 6: Cur the mold at 120-150℃ for 4 hours;

[0093] Step 7: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0094] The casting obtained in this embodiment has a bulk density of 0.26-0.46 g / cm³. 3 The compressive strength is 6-23 MPa, and the water absorption rate of the bare material after 24 hours is 0.5-1.0%. Compared with Example 2, the density of the product in this example is further reduced, and the net buoyancy per unit volume is further improved.

[0095] Example 4

[0096] Based on Example 1, resin is impregnated onto the surface of the composite hollow sphere before filling the mold to enhance the interfacial bonding between the castable and the composite hollow sphere. The specific process is as follows:

[0097] Step 1: Assemble the mold and verify its sealing performance;

[0098] Step 2: Mix 1%-5% by weight of E51 type epoxy resin, methyltetrahydrophthalic anhydride, 593, 2,4,6-tris(dimethylaminomethyl)phenol, and γ-aminopropyltriethoxysilane (formulation ratio 100:70:3:3:2) with 60-200 parts of a sphere-forming agent with a density grade of 0.10-0.35 g / cm³ in a ball-forming machine. 3 The composite hollow spheres are mixed at room temperature for 3-5 minutes. The ball rolling machine speed is 30-60 rpm, and the resin amount is 1%-5% of the mass of the composite hollow spheres.

[0099] Step 3: Fill the mold with the composite hollow spheres, and evacuate the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0100] Step 4: Stir 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane at a uniform speed for 5-15 minutes under vacuum at 40-60°C.

[0101] Step 5: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0102] Step Six: Inject the casting material into the mold under normal pressure;

[0103] Step 7: Cur the mold at 120-150℃ for 4 hours;

[0104] Step 8: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0105] The casting obtained in this embodiment has a bulk density of 0.24-0.47 g / cm³. 3 The compressive strength is 6-25 MPa, and the water absorption rate of the bare material after 24 hours is 3-6%. Due to the impregnation of the surface of the composite hollow sphere, the interfacial bonding between the castable and the composite hollow sphere is promoted. Therefore, compared with Comparative Example 1, the bulk density and water absorption rate of the product in this example are not significantly different, but the mechanical strength is slightly improved.

[0106] Example 5

[0107] Based on Example 2, resin is impregnated onto the surface of the composite hollow spheres before filling the mold. This improves the density of the product and enhances the interfacial bonding between the castable and the composite hollow spheres, thus ensuring its mechanical properties. The specific process is as follows:

[0108] Step 1: Assemble the mold and verify its sealing performance;

[0109] Step 2: Mix 1%-5% by weight of E51 type epoxy resin, methyltetrahydrophthalic anhydride, 593, 2,4,6-tris(dimethylaminomethyl)phenol, and γ-aminopropyltriethoxysilane (formulation ratio 100:70:3:3:2) with 60-200 parts of a sphere-forming agent with a density grade of 0.10-0.35 g / cm³ in a ball-forming machine. 3 The composite hollow spheres are mixed at room temperature for 3-5 minutes. The ball rolling machine speed is 30-60 rpm, and the resin amount is 1%-5% of the mass of the composite hollow spheres.

[0110] Step 3: Prepare 60-200 portions of material with a density grade of 0.10-0.35 g / cm³. 3 Composite hollow spheres are filled into the mold, and the mold is evacuated to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0111] Step 4: Stir 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane at a uniform speed for 5-15 minutes under vacuum at 40-60°C.

[0112] Step 5: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0113] Step Six: Inject the castable refractory into the mold under a pressure of 2.0-3.0 MPa;

[0114] Step 7: Cur the mold at 120-150℃ for 4 hours;

[0115] Step 8: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0116] The casting obtained in this embodiment has a bulk density of 0.38-0.63 g / cm³. 3 The compressive strength is 11-31 MPa, and the water absorption rate of the bare material after 24 hours is 0.5-0.9%. Compared with Example 2, due to the impregnation of the surface of the composite hollow sphere, the interfacial bonding strength between the castable and the composite hollow sphere is improved. Therefore, under the condition that the bulk density and water absorption rate do not change significantly, the mechanical strength of the product is slightly improved.

[0117] Example 6

[0118] Based on Example 3, resin is impregnated onto the surface of the composite hollow spheres before filling the mold. This improves the density of the product and promotes interfacial bonding between the castable and the composite hollow spheres, thus ensuring its mechanical properties. The specific process is as follows:

[0119] Step 1: Assemble the mold and verify its sealing performance;

[0120] Step 2: Mix 1%-5% by weight of E51 type epoxy resin, methyltetrahydrophthalic anhydride, 593, 2,4,6-tris(dimethylaminomethyl)phenol, and γ-aminopropyltriethoxysilane (formulation ratio 100:70:3:3:2) with 60-200 parts of a sphere-forming agent with a density grade of 0.10-0.35 g / cm³ in a ball-forming machine. 3 The composite hollow spheres are mixed at room temperature for 3-5 minutes. The ball rolling machine speed is 30-60 rpm, and the resin amount is 1%-5% of the mass of the composite hollow spheres.

[0121] Step 3: Prepare 60-200 portions of material with a density grade of 0.10-0.35 g / cm³. 3 Composite hollow spheres are filled into the mold, and the mold is evacuated to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa;

[0122] Step 4: Stir 100 parts of E51 type epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593, 1-3 parts of 2,4,6-tris(dimethylaminomethyl)phenol, and 2 parts of γ-aminopropyltriethoxysilane at a uniform speed for 5-15 minutes under vacuum at 40-60°C.

[0123] Step 5: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material.

[0124] Step Six: Inject the castable refractory into the mold under a pressure of 0.2-0.5 MPa;

[0125] Step 7: Cur the mold at 120-150℃ for 4 hours;

[0126] Step 8: After natural cooling, demold the product and treat any burrs or defects on the surface.

[0127] The casting obtained in this embodiment has a bulk density of 0.27-0.46 g / cm³. 3 The compressive strength ranges from 7 to 28 MPa, and the water absorption rate of the bare material after 24 hours is less than 0.5%. Compared with Example 3, the mechanical strength of the product did not change significantly, but the bulk density decreased significantly, increasing the net buoyancy per unit material; the water absorption rate of the product also decreased significantly. Because the composite hollow sphere is impregnated, the castable can fully fill the gap between the mold and the composite hollow sphere under a relatively low positive pressure, resulting in a well-preserved product with no obvious defects inside or outside; due to the appropriate pressure, the phenomenon of castable seeping into the hollow sphere is also rare, and the bulk density does not increase significantly. The product obtained in this example has a low bulk density, excellent mechanical properties, and low cost; the yield and production efficiency during the preparation process are high, making it very suitable for the production of large buoyancy compensation devices such as water-proof pipe buoyancy blocks.

[0128] Because of the process described in this patent, the surface of the composite hollow sphere is impregnated with epoxy resin that is basically the same as the casting material formula. When a certain positive pressure is applied during the casting process, the internal voids of the product can be completely filled by the casting material. Therefore, the density is high, the product has a good shape, no obvious internal defects, low defect rate, and high production efficiency.

[0129] As can be seen from Example 6, the buoyancy material prepared using the process described in this invention can achieve a minimum density of 0.27 g / cm³. 3With a compression modulus of 850-1950 MPa and a 24-hour water absorption rate of less than 0.5% for the bare material, this material boasts lower density, higher strength, and lower water absorption compared to traditional non-foamed buoyancy materials. Since the composite hollow spheres account for over 60% of the material's volume, its unit volume cost is significantly lower than that of epoxy resin and hollow glass microspheres. Therefore, its raw material cost is reduced by more than 30% compared to traditional solid buoyancy materials, making it highly suitable for the production of large buoyancy compensation devices such as riser buoyancy blocks.

[0130] In summary, this invention provides a positive pressure assisted vacuum casting process for preparing buoyancy compensation materials.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. 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. Such modifications or substitutions, such as using lightweight fillers like lightweight ceramic particles to replace composite hollow spheres, using hollow glass microspheres and composite hollow spheres of other density grades, using other cementing materials like polypropylene resin to replace epoxy resin, or changing the type of short-cut fibers or other types of reinforcing materials, 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 positive pressure assisted vacuum casting process for preparing buoyancy compensation materials, characterized in that: The positive pressure assisted vacuum casting process for preparing buoyancy compensation materials includes the following steps: Step 1: Mix 1%-5% by weight of E51 type epoxy resin, methyltetrahydrophthalic anhydride, 593 curing agent, DMP-30, and γ-aminopropyltriethoxysilane into a ball rolling machine with 60-200 parts of a resin with a density grade of 0.10-0.35 g / cm³. 3 The composite hollow spheres are mixed at room temperature for 3-5 minutes, the ball rolling machine speed is 30-60 rpm, and the resin amount is 1%-5% of the mass of the composite hollow spheres; The method for preparing the composite hollow spheres is as follows: Step 1: Prepare the spherical shell base liquid using epoxy resin and a portion of rigid fibers as the main raw materials; Step 2: Add room temperature and medium temperature composite curing agent and accelerator to the spherical shell base liquid and stir evenly to form a spherical shell mixture; Step 3: Immerse the lightweight foamed balls in the shell mixture, then remove them and place them on a wire mesh at room temperature until the shell mixture on the lightweight foamed balls is drained, forming resin-based hollow balls; Step 4: Put the resin-based hollow spheres and the remaining rigid fibers into the ball rolling machine, start the ball rolling machine, until a rigid fiber composite sphere shell is formed; then take it out and let it stand in a room temperature environment for 12-24 hours until the sphere shell loses its fluidity; Step 5: Repeat steps 1-4 as needed to prepare multi-layer composite spherical shells until the density of the composite hollow spheres reaches the target value. Then, keep them in an environment of 60-100℃ for 2-4 hours to complete the curing. After natural cooling, they can be used. Step 2: Fill the mold with 60-200 parts of a material with a density grade of 0.10-0.35 g / cm³. 3 For composite hollow spheres, a vacuum is applied to the mold to ensure that the internal pressure does not exceed 1×10⁻⁶. 4 Pa; Step 3: Mix 100 parts of E51 epoxy resin, 60-80 parts of methyltetrahydrophthalic anhydride, 0-3 parts of 593 curing agent, 1-3 parts of DMP-30, and 2 parts of γ-aminopropyltriethoxysilane under vacuum at 40-60°C for 5-15 minutes. Step 4: Add 35-80 parts of a density grade of 0.15-0.38 g / cm³ 3 Hollow glass microspheres and 0-2 parts of chopped glass fiber powder are stirred at a constant speed for 10-30 minutes under vacuum at 40-60℃ to obtain a casting material. Step 5: Inject the casting material into the mold and cure the mold at 120-150℃. In step 5, the casting material is injected into the mold under a pressure of 0.2-0.5MPa.

2. The positive pressure assisted vacuum casting preparation process for preparing buoyancy compensation materials according to claim 1, characterized in that: The mass ratio of the E51 type epoxy resin, methyltetrahydrophthalic anhydride, 593 curing agent, DMP-30, and γ-aminopropyltriethoxysilane is 100:70:3:3:

2.

3. A material for preparing buoyancy compensation, wherein the material is prepared by the positive pressure assisted vacuum casting process according to any one of claims 1-2.

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