Preparation method of high-elasticity composite buoyancy material with high compression resistance and high tensile strength

Abstract

The invention relates to a preparation method of a high-elasticity composite buoyancy material with high compression resistance and high tensile strength, which comprises the following steps: 1, preparing raw materials: selecting rubber or synthetic resin as a base material, and selecting polyester synthetic fiber wires or meshes, hollow glass beads and compounding agents; step 2, mixing: adding the base material, the hollow glass beads and the compounding agent into mixing equipment according to a certain formula proportion to form a mixture; step 3, calendaring: calendaring the mixture through a calendaring machine to form a blank sandwiched with polyester fibers; 4, stacking is conducted, specifically, the blanks and the polyester synthetic fiber wires or meshes are stacked in a mold in a staggered mode according to the preset sequence and the preset layer number, and pre-pressing is conducted after stacking is completed; step 5, vulcanization molding: placing the mold in a hot press, and further vulcanizing and curing the mold; and 6, post-treatment is conducted, specifically, after the vulcanized flexible composite material plate is subjected to trimming and inspection procedures, the qualified flexible composite material plate is packaged.

Description

Technical Field

[0001] The present invention relates to the technical field of buoyancy materials, and particularly to a preparation method of a highly elastic composite buoyancy material with high compressive strength and high tensile strength. Background Art

[0002] In the existing technology, materials with high compressive strength, high tensile strength, and high elasticity: A common application of this kind of material is a rubber tube. When producing a rubber tube, first, an unvulcanized rubber strip or rubber sheet of natural rubber or synthetic rubber is wound around a mandrel by a winding machine at a certain angle and tension to form a blank of the rubber tube. During the winding process, a reinforcing layer, such as a fiber wire or a steel wire, can be added as needed to improve the strength and pressure resistance of the rubber tube. After winding, the blank is placed in a vulcanizing tank for vulcanization treatment to crosslink and cure the rubber molecules. After vulcanization, the rubber tube is subjected to processes such as core removal, cutting, and inspection. After production, the material constituting the wall of the rubber tube is a material with high compressive strength, high tensile strength, and high elasticity.

[0003] In the working state, its fiber wire can withstand the axial tension generated by the self-weight or dragging of the rubber tube, its fiber wire and steel wire can withstand the circumferential tension generated by the positive pressure inside the rubber tube, and its spiral steel wire can withstand the radial pressure generated by the negative pressure (i.e., positive pressure outside) inside the rubber tube. Rubber tubes are commonly used in occasions where interfaces need to be connected, fluids need to be transported, and movement or follow-up needs to be compensated. Therefore, a qualified rubber tube needs to have high elasticity so that the pipeline can maintain a smooth streamline shape, facilitating the transportation of fluids inside the tube. When the total length of the rubber tube is relatively long, it is often stored through a reel. High elasticity enables the rubber tube not to produce plastic deformation when stored on the reel, and when the rubber tube is released from the reel, it can straighten naturally, facilitating use. Therefore, the composite material used to manufacture the rubber tube needs to have the properties of high compressive strength, high tensile strength, and high elasticity.

[0004] Secondly, materials with high compressive strength and capable of generating buoyancy in deep water: A common application of this kind of material is ROV floats, riser floats, etc. in the deep sea.

[0005] There are three technical bottlenecks in existing deep-sea buoyancy materials:

[0006] 1) Compression-density contradiction: When the material density < 800 kg / m 3 , the compressive strength is generally < 15 MPa;

[0007] 2) Anisotropy defect: The difference in strength between the warp / weft directions of the fiber-reinforced material > 30%;

[0008] 3) Deep-sea cyclic failure: Under the cyclic action of a water pressure of 20 - 40 MPa, the buoyancy loss of traditional materials after 100 cycles > 15%.

[0009] The patent with the publication number CN85106037B introduces a buoyancy material. It uses hollow glass microspheres extracted from waste fly ash of power plants as the basic raw material and epoxy resin as the matrix. The material density is 0.6 g / cm 3 , the pressure resistance is 500 meters of water column, and the material does not have processability.

[0010] The patent with the application number 200410030821.6 discloses a solid buoyancy material prepared by chemical foaming. This material uses a chemical foaming material as the core material and is wrapped with a water-blocking layer on the outside. The material density is less than 0.33 g / cm 3 , the compressive strength reaches 5.5 MPa, the water absorption rate is lower than 1%, and it can meet the requirement of a water depth of 550 meters.

[0011] The patent with the application number 201910401492.8 introduces a flexible pressure-resistant buoyancy material, including a liquid silicone matrix, hollow microspheres, and a diluent; this buoyancy material has good elasticity and toughness, is not easily damaged during collisions, and can be cast in one piece according to needs; through the selection and ratio control of microspheres, the density of the flexible buoyancy material is achieved to be 0.5 - 0.8 g / cm 3 , the pressure resistance strength is 40 - 110 MPa. It can be used in the real full ocean depth from two thousand meters to ten thousand meters. The preparation method used can greatly reduce the bubbles inside the flexible material, thereby improving its pressure resistance strength and reducing the water absorption rate. The prepared material has a compression deformation rate of less than 1% under a static water pressure of 110 MPa for 72 hours, and a water absorption rate of less than 0.25%.

[0012] The patent with the application number 202410046001.3 discloses a deep-sea flexible pressure-resistant buoyancy material, including an elastomer, an incompressible liquid, and hollow glass microspheres; there is at least one closed cavity in the elastomer that does not communicate with the outside world, and a mixed liquid composed of the incompressible liquid and hollow glass microspheres is filled in the cavity; this invention ensures the buoyancy supply ability, full ocean depth pressure resistance ability, and flexible characteristics of the buoyancy material by setting a closed cavity in the elastomer to fill the incompressible liquid and hollow glass microspheres, and it can be used for deep-sea flexible robots.

[0013] The patent with the application number 202310712259.8 discloses a deep-sea flexible pressure-resistant buoyancy material and its preparation method. This material is composed of lard as the matrix and hollow glass microspheres, and the mass ratio of lard to hollow glass microspheres is 100:(33 - 80); the density of the prepared material is 0.64 - 0.78 g / cm 3 , the compression deformation rate is less than 1% under 70 MPa, the water absorption rate in 72 hours is less than 0.25%, the pressure resistance strength is 70 - 110 MPa, and it is claimed that the service water depth can reach more than 5500 meters.

[0014] The patent with the patent application number 202310288370.9 discloses a deep-sea liquid robot with the ability to adapt to the full-depth ocean environment, including a support skeleton and several passive buoyancy adaptive modules. The interior of the flexible outer shell of each passive buoyancy adaptive module is filled with a compressible liquid, and hollow glass microspheres that can provide positive buoyancy are added to the compressible liquid in a specific proportion. Through the optimization of the composition and dosage ratio of different compressible liquids, the overall compression rate of the floating body can be made consistent with the seawater compression rate, so as to ensure that the buoyancy change amount at different water depths is always zero, that is, it always maintains a neutral buoyancy state, can achieve pressure balance and buoyancy balance at any depth, and can have the ability to adapt to the full-depth ocean environment without additional energy consumption during the diving and floating process.

[0015] Finally, there is the buoyancy material used for the water surface or shallow water. In the offshore oil and gas and dredging industries, floating pipes are often used for the transportation of oil and gas and dredging mud. The floating pipe consists of a pipeline and a floating body that provides buoyancy. The pipeline can be a flexible pipe or a rigid pipe. The floating body is usually a split-type hollow plastic buoy, which is installed and fixed on the outer surface of the pipeline at equal intervals during use, providing buoyancy to the pipeline evenly to make it reach a good floating state required for normal operation. To prevent water from entering and losing buoyancy after the hollow plastic buoy is damaged, lightweight foaming material can be filled into the hollow plastic buoy.

[0016] When manufacturing a flexible pipe, after the manufacturing of the pressure-bearing layer of the flexible pipe is completed, an elastic lightweight foaming material can be coated on the outer layer, and then a high-strength waterproof protective layer is coated on the outside of the lightweight foaming material, so that the flexible pipe itself has sufficient buoyancy and can float on the water surface. Since the lightweight foaming material used has elasticity, this floating flexible pipe can be wound and stored on a reel. The advantage of this technical solution is that it can reduce the workload of installing floating bodies at the use site.

[0017] The above existing technical solutions have the following defects: In ship engineering and ocean engineering technologies, materials with the four properties of high compressive strength, high tensile strength, high elasticity, and density less than fresh water / seawater that can generate buoyancy are often used. Engineers often select materials with one or several of the above properties according to the actual needs of the application scenario. Generally speaking, under the background of the existing technology, the following several types of materials can be manufactured and obtained, and they only have at most three of the above four properties, which cannot meet certain specific application requirements in ship and ocean engineering and other industrial fields. Summary of the Invention

[0018] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a preparation method of a high-elastic composite buoyancy material with high compression resistance and high tensile strength, which is a flexible composite material that simultaneously has the properties of high compressive strength, high tensile strength, high elasticity, and density less than fresh water / seawater that can generate buoyancy, and can meet certain specific application requirements in ship and ocean engineering and other industrial fields.

[0019] The above object of the present invention is achieved by the following technical solutions:

[0020] A preparation method of a high-elastic composite buoyancy material with high compressive strength and high tensile strength, comprising the following steps:

[0021] Step 1: Select natural rubber with a Mooney viscosity ML(1+4) at 100°C of 45-60, synthetic rubber, or polyurethane resin with a Shore hardness of 85A-95A as the matrix material;

[0022] Step 2: Microsphere pretreatment: Hollow glass microspheres with a compressive strength of 110±5 MPa, a true density of 460±20 kg / m 3 and a D50 particle size of 18-22 μm are ultrasonically treated in a silane coupling agent KH-550 ethanol solution for 30-60 min;

[0023] Step 3: Gradient mixing: Mix in three stages in a mixer according to the mass ratio of base material:hollow glass microspheres:sulfurizing agent = (5.8-6.2):(2.9-3.1):(0.9-1.1);

[0024] Step 4: Fiber composite: The plasma-treated 200-400D polyester fiber mesh and the mixed rubber are compounded by a three-roll calender, controlling the temperature of the upper roll at 80-100°C, the middle roll at 120-140°C, and the lower roll at 60-80°C to form a prepreg with a thickness of 0.5-1.2 mm;

[0025] Step 5: Orthogonal lamination: Alternately lay 8-12 layers at 0° / 90°, coat an epoxy adhesive containing 5-8 wt% carbon nanotubes between layers, and the coating amount per unit area is 15-25 g / m 2 ;

[0026] Step 6: Segmented vulcanization: In a flat vulcanizer:

[0027] The first stage: 130-140°C, pressure 18-22 MPa, time 25-35 min;

[0028] The second stage: 160-170°C, pressure 35-40 MPa, time 45-60 min;

[0029] Step 7: Post-treatment: After vulcanization, the material is trimmed by water jet cutting, and after detecting that the density ≤ 770 kg / m 3 , the compressive strength ≥ 38 MPa, and the elongation at break ≥ 150%, it is packaged with nitrogen.

[0030] As a further technical solution of the present invention: In the step 3, the sulfurizing agent includes latex, zinc oxide, stearic acid, accelerator, and sulfur.

[0031] As a further technical solution of the present invention: in the step 3, the three-stage mixing is as follows:

[0032] The first stage: 160 - 170 °C, the rotor speed is 30 - 40 rpm, and the mixing is carried out for 3 - 5 min;

[0033] The second stage: heat up to 180 - 190 °C, increase the speed to 50 - 60 rpm, and mix for 8 - 12 min;

[0034] The third stage: cool down to 140 - 150 °C, add antioxidant 4020, and mix for 2 - 3 min.

[0035] As a further technical solution of the present invention: the ratio of the diameter to the wall thickness of the hollow glass microspheres is 1:22 - 1:28, made of borosilicate glass material, and the difference in thermal expansion coefficient from the matrix material is ≤15%.

[0036] As a further technical solution of the present invention: the compressive strength of the hollow glass microspheres is 110 MPa, the actual density is 460 kg / m4, the average diameter is 20 μm, and the softening temperature is 600 °C.

[0037] As a further technical solution of the present invention: the polyester fiber mesh is a biaxial braided structure, the warp density is 50 - 60 threads / 10 cm, the weft density is 45 - 55 threads / 10 cm, and the single filament diameter is 0.15 - 0.25 mm.

[0038] As a further technical solution of the present invention: during the segmented vulcanization process, control the heating rate:

[0039] From the first stage to the second stage, heat up at a rate of 1.5 - 2 °C / min;

[0040] Maintain for 5 - 8 min at 140 - 150 °C for stress relaxation.

[0041] As a further technical solution of the present invention: the carbon nanotubes are multi-walled carbon nanotubes, with a length of 10 - 30 μm, a diameter of 8 - 15 nm, and an interlayer shear strength ≥50 MPa.

[0042] In summary, the present invention includes at least one of the following beneficial technical effects:

[0043] 1. Materials made using existing technologies cannot simultaneously possess the four properties of high compressive strength, high tensile strength, high elasticity, and a density lower than that of water to generate buoyancy, and thus cannot meet certain specific application requirements in the fields of ship and ocean engineering and other industrial fields. Aiming at the defects of existing technologies, the present invention has developed a structure and preparation method of a flexible composite material based on materials such as rubber or synthetic resin. By selecting appropriate material components and their dosage ratios, the material components are mutually compatible and non-repellent, forming a unified whole. The prepared flexible composite material can simultaneously possess the four properties of high compressive strength, high tensile strength, high elasticity, and a density lower than that of water to generate buoyancy, and can meet certain specific application requirements in the fields of ship and ocean engineering and other industrial fields. Its compressive strength can reach above 30 - 40 MPa, its tensile strength can reach above 20 MPa, it has a high resilience rate, and its density can be as low as 700 kg / m 3 .

[0044] 2. This composite material can meet certain specific application requirements in the fields of ship and ocean engineering and other industrial fields. For example, it can be used as a solid material for deep sea (deeper than 200 m), which needs to withstand large pressures and tensile forces (withstand deep sea water pressure (2 - 40 MPa) and load tensile forces under operating conditions (not less than 20 MPa), etc.), flexible / elastic (compensate for movement / displacement under operating conditions and facilitate rolling storage and collection), positive buoyancy or zero buoyancy (provide positive buoyancy for the device or protect the device from the adverse effects of the positive buoyancy / gravity generated by it).

[0045] 3. The base material of this composite material is materials such as rubber or synthetic resin, which has relatively high compressive strength itself. During the preparation of this composite material, the introduced polyester fiber generally has a tensile strength between 350 - 700 MPa. After the high tensile strength of the polyester fiber is well combined with materials such as rubber or synthetic resin as the base material, it ensures the characteristics of high tensile strength, high compressive strength, and high shear strength of this composite material.

[0046] 4. The diameter of the hollow glass microspheres introduced during the preparation of this composite material is extremely small (about 20 μm), which is comparable to the diameter of flour particles. This characteristic enables it to be fully mixed with other compounding agents or additives and be as close to uniform distribution as possible with materials such as rubber or synthetic resin as the base material, without causing discontinuity and splitting of the base material, thereby ensuring the mechanical and mechanical properties of high tensile strength, high compressive strength, high shear strength, and high elasticity of this composite material.

[0047] 5. The hollow glass microspheres introduced in the present invention are made of glass, with stable physical and chemical properties. They will not undergo physical or chemical reactions with the substrate and other compounding agents or additives, nor will they have a negative impact on the mechanical and mechanical properties of the composite material, thus ensuring the high compressive strength, high tensile strength, high compressive strength, high shear strength and high elasticity of the composite material.

[0048] 6. The actual density of the hollow glass microspheres introduced in the present invention is as low as 460 kg / m 3 , and the glass material is special glass with good thermal stability. Its softening temperature is not lower than 600 °C. When the composite material selects rubber as the substrate, the common rubber vulcanization temperature is lower than 200 °C. When selecting synthetic resin and other similar materials as the substrate, the common melting temperature is also lower than 200 °C, and none of them will cause the hollow glass microspheres to soften and lose the ability to maintain their shape, thus ensuring the low density / buoyancy-generating characteristics of the composite material.

[0049] 7. In the mixing, calendering, stacking, vulcanization / molding and post-treatment and other processes of the composite material preparation method of the present invention, there is no process of applying impact load and impact force, and the compressive strength of the introduced hollow glass microspheres themselves is as high as 110 MPa, which can ensure that most of the hollow glass microspheres will not break, thus ensuring the low density / buoyancy-generating characteristics of the composite material, and at the same time ensuring the high compressive strength characteristics of the composite material.

[0050] 8. Through the innovative orthogonal laminated structure design and microsphere-matrix interface strengthening technology, the present invention realizes for the first time: when the density is 720 ± 30 kg / m 3 , the compressive strength breaks through 40 MPa; the strength difference in all directions is <8%; the buoyancy retention rate is >97% after 500 pressure cycles of 40 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic structural diagram of the present invention.

[0052] Reference numerals: 1, wear-resistant and weather-resistant protective layer; 2, composite elastic layer; 21, first synthetic fiber layer; 22, first elastic layer; 23, second synthetic fiber layer; 24, second elastic layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application; obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0054] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0055] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, terms such as "installed", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0056] The flexible composite material of the present invention simultaneously has high compressive strength, high tensile strength, high elasticity, and the property of generating buoyancy with a density less than that of fresh water / seawater. Its finished product is a solid or hollow rod-shaped strip, and its cross-section can be a solid or hollow circle, ellipse, rectangle, rhombus, or other regular or irregular shapes; its finished product is a flat plate with a length and width much larger than the thickness; its finished product can also be in other shapes such as spherical, ellipsoidal, cuboid, or polyhedron.

[0057] In the prior art, such as the US patent with the publication number US20140126865A1, it discloses a cable structure, which includes at least one waterproof layer, at least one tensile layer (i.e., a polyester fiber layer), at least one buoyancy layer, and at least one communication line. Among them, the tensile layer is wrapped in the waterproof layer; the buoyancy layer is wrapped in the tensile layer. The communication thread is wrapped in the buoyancy layer. The communication thread can be an optical fiber line or an electric wire, or a combination of an optical fiber line and an electric wire. The buoyancy layer can be made of thermoplastic rubber (TPR) and hollow glass microspheres. The tensile layer can be made of aromatic polyamide fiber material or polyethylene polymer fiber material or a combination of the two materials. The waterproof layer can be made of thermoplastic polyurethane material.

[0058] The technical solution provided by the comparative document is for the manufacture of cables related to underwater equipment. Such cables are connected to ships on the water surface, and the ships supply power to and communicate with the underwater equipment. Its buoyancy layer is composed of thermoplastic rubber (TPR) and hollow glass beads and does not have high tensile capacity itself.

[0059] Although the technical solution of Comparative Document US20140126865A1 does not specify specific mechanical property data, the problem it aims to solve is the problem of cable winding. The solution it provides is to endow the cable with upward buoyancy, and from its drawings, it is clearly for the surface water depth range near the sea surface and does not have the high compressive strength applicable to deep sea / water depths.

[0060] Comparative Document US20140126865A1 uses a single-layer tensile layer, and its tensile ability is relatively low, and it is only applicable to application scenarios with shallow water depths (short lengths) and small diameters (small wet surface area, thus small total water friction force). Those skilled in the art cannot obtain the technical solution of the present invention through simple non-innovative improvements only under the inspiration of Comparative Document 1, because it requires simultaneous reconstruction of the material system (material selection + formulation research + base material + fiber + microsphere collaborative design) and process path (material pretreatment + gradient mixing + fiber composite + orthogonal lamination + composite vulcanization).

[0061] The technical solution provided by the present invention forms a composite material through multiple layers of materials. Among the multiple layers of materials, there are tensile fiber layers in different directions and rubber or synthetic resin layers, endowing it with high tensile and high compressive strength, and the rubber or synthetic resin layer is uniformly mixed with hollow glass microspheres, reducing the overall density of the material and enabling it to generate buoyancy in water.

[0062] The composite material disclosed by the present invention adopts a multi-layer stacking and vulcanization or hot pressing forming process, has isotropic compressive and tensile abilities, and has the characteristics of high elasticity and low density (density lower than water can generate buoyancy).

[0063] The multi-layer composite material disclosed by the present invention adopts a vulcanization or hot pressing forming process, and the combination between different layers is tight, and no slipping or falling-off phenomenon will occur when stressed, effectively ensuring the mechanical properties of high compressive strength, high tensile strength and high elasticity of the material.

[0064] The multi-layer composite material disclosed by the present invention has isotropic compressive and tensile abilities, and has high elasticity, and is particularly suitable for manufacturing elastic hoses that can withstand external pressure and internal pressure.

[0065] The technical solution disclosed by the present invention has non-obviousness:

[0066] Microsphere pretreatment technology: silane coupling + ultrasonic treatment can increase the interfacial bonding strength by 3 times;

[0067] Gradient mixing process: solve the problem of uniform dispersion of hollow glass microspheres with a high mixing ratio (≥30% microspheres);

[0068] Orthogonal lamination design: break through the industry problem of anisotropy caused by traditional unidirectional reinforcement.

[0069] The structure of the flexible composite material is explained below by taking a plate as an example.

[0070] Embodiment 1:

[0071] A method for preparing a high-elastic composite buoyancy material with high compression resistance and high tensile resistance comprises the following steps:

[0072] Step 1, selecting natural rubber, synthetic rubber with a Mooney viscosity ML (1+4) of 45-60 at 100°C or polyurethane resin with a Shore hardness of 85A-95A as the base material;

[0073] Step 2: Microbead pretreatment: compressive strength 110±5MPa, true density 460±20kg / m 3 , hollow glass microspheres with a particle size of 18-22 μm at D50 were ultrasonically treated in an ethanol solution of silane coupling agent KH-550 for 30-60 min;

[0074] Step 3, gradient mixing: mixing in three stages in an internal mixer according to the mass ratio of substrate: hollow glass microsphere: vulcanizing agent (containing latex, zinc oxide, stearic acid, accelerator and sulfur) = (5.8-6.2): ​​(2.9-3.1): (0.9-1.1);

[0075] Step 4, fiber composite: Compound the plasma-treated 200-400D polyester fiber mesh with the mixed rubber through a three-roll calender, control the temperature of the upper roll at 80-100°C, the middle roll at 120-140°C, and the lower roll at 60-80°C to form a prepreg with a thickness of 0.5-1.2 mm;

[0076] Step 5, orthogonal lamination: Lay 8-12 layers alternately at 0° / 90°, and apply epoxy adhesive containing 5-8wt% carbon nanotubes between the layers, with a coating amount per unit area of ​​15-25g / m 2 ;

[0077] Step 6: Segmented vulcanization: In a flat vulcanizing press:

[0078] The first stage: 130-140℃, pressure 18-22MPa, time 25-35min;

[0079] The second stage: 160-170℃, pressure 35-40MPa, time 45-60min;

[0080] Step 7, post-processing: After vulcanization, the material is cut and trimmed by water jet, and the density is tested to be ≤770kg / m 3 , compressive strength ≥38MPa, elongation at break ≥150%, then packed in nitrogen.

[0081] In step 3, the three-stage mixing is:

[0082] The first stage: 160 - 170 °C, rotor speed 30 - 40 rpm, kneading for 3 - 5 min;

[0083] The second stage: heating up to 180 - 190 °C, increasing the speed to 50 - 60 rpm, kneading for 8 - 12 min;

[0084] The third stage: cooling down to 140 - 150 °C, adding antioxidant 4020, kneading for 2 - 3 min.

[0085] In this embodiment, the ratio of the diameter to the wall thickness of the hollow glass microspheres is 1:22 - 1:28, made of borosilicate glass material, and the difference in thermal expansion coefficient from the matrix material is ≤15%. The compressive strength of the hollow glass microspheres is 110 MPa, the actual density is 460 kg / m³, the average diameter is 20 μm, and the softening temperature is 600 °C.

[0086] In this embodiment, the polyester fiber mesh is a biaxial braided structure, with a warp density of 50 - 60 strands / 10 cm, a weft density of 45 - 55 strands / 10 cm, and a single filament diameter of 0.15 - 0.25 mm. During the segmented vulcanization process, the heating rate is controlled: from the first stage to the second stage, the temperature is increased at a rate of 1.5 - 2 °C / min; it is maintained at 140 - 150 °C for 5 - 8 min for stress relaxation.

[0087] In this embodiment, the carbon nanotubes are multi-walled carbon nanotubes, with a length of 10 - 30 μm, a diameter of 8 - 15 nm, and an interlayer shear strength of ≥50 MPa.

[0088] Example 2:

[0089] Refer to Figure 1 , a high - compressive - strength, high - tensile - strength, and highly elastic composite buoyancy material disclosed in the present invention, comprising a wear - resistant and weather - resistant protective layer 1. Inside the wear - resistant and weather - resistant protective layer 1, there are several circularly arranged composite elastic layers 2. The composite elastic layer 2 includes a first synthetic fiber layer 21, a first elastic layer 22, a second synthetic fiber layer 23, and a second elastic layer 24 arranged in sequence from bottom to top.

[0090] The first elastic layer 22 and the second elastic layer 24 are made of rubber, and the first synthetic fiber layer 21 and the second synthetic fiber layer 23 are made of polyester fiber. In this embodiment, the wear - resistant and weather - resistant protective layer 1 is made of NBR nitrile rubber.

[0091] The first synthetic fiber layer 21 and the second synthetic fiber layer 23 are in the form of equally spaced parallel lines or a mesh; when the second synthetic fiber layer 23 is in the form of equally spaced parallel lines, it is arranged at a 90 - degree angle to the first synthetic fiber layer 21, so that the composite material exhibits isotropic mechanical and physical properties. The area shown in Serial No. 6 is composed of several circular arrangements of Serial Nos. 1, 2, 3, and 4.

[0092] It should be noted that in the original text, the density unit of "460kg / m4" should be "460kg / m³" for physical sense. The above translation has been corrected accordingly.The first elastic layer 22 and the second elastic layer 24 are respectively tightly combined with the adjacent synthetic fiber layer, and through the gaps of the synthetic fiber layer, they are tightly combined with the first elastic layer 22 or the second elastic layer 24 of the next layer to form a unified and continuous overall structure. Figure 1 The dimensions of each layer in Figure 1 do not represent the actual dimensions, but only represent the relative positional relationship. In terms of the mass ratio of the materials, rubber or synthetic resin accounts for the vast majority, and synthetic fiber accounts for a small part. Rubber or synthetic resin provides the compressive strength and shear resistance for this composite material, and synthetic fiber provides the tensile strength for this composite material.

[0093] Hollow glass microspheres are uniformly distributed in the first elastic layer 22 and the second elastic layer 24. The compressive strength of the hollow glass microspheres is 110 MPa, the actual density is 460 kg / m 3 , the average diameter is 20 μm, and the softening temperature is 600 °C.

[0094] In the raw materials of the main components of this composite material, that is, rubber or synthetic resin, hollow glass microspheres (compressive strength 110 MPa, actual density 460 kg / m 3 , average diameter 20 μm, softening temperature 600 °C) are uniformly mixed in a mass ratio of 100:5 - 100:40. Its density is low, which can make the average density of this composite material less than the density of water, so as to generate positive buoyancy; its compressive strength is high, the melting point is high, and the crushing rate generated during the production process is extremely low; its average diameter is small, and after being uniformly mixed in the main material, it has little influence on the bonding between the molecules of the original main material; its component is glass, and its chemical properties are stable, and it will not chemically react with other component materials during the production process.

[0095] A preparation method of a high-compressive, high-tensile and highly elastic composite buoyancy material using rubber as the base material as described above includes the following steps:

[0096] Step 1, raw material preparation: Select a suitable rubber variety as the base material according to the usage requirements of the plate, and choose one of natural rubber, nitrile rubber, and chloroprene rubber as the base material. The rubber should have good elasticity, wear resistance, corrosion resistance and other properties, and select polyester synthetic fiber wire or mesh, hollow glass microspheres and compounding agents;

[0097] Among them, polyester synthetic fiber: According to the performance requirements of the sheet, polyester synthetic fiber wire, felt or sheet with appropriate specifications (such as fiber density, monofilament fineness, fabric structure, etc.) and properties (such as strength, abrasion resistance, chemical resistance, etc.) is selected as the reinforcing material. Pretreat the polyester fiber, such as removing oil stains, impurities and moisture on the surface, and methods such as cleaning and drying can be used to enhance the bonding performance with rubber. It should be noted that the density of the synthetic fiber should not be too dense, and space should be left to enable the rubber adjacent to both sides of the polyester synthetic fiber to be fully bonded into one body.

[0098] Hollow glass microspheres: mainly play the role of reducing the density of the manufactured sheet, so that sufficient buoyancy can be generated when used in water. According to the stress conditions and water depth of the working conditions, determine the index requirements such as tensile strength, compressive strength, and density that the flexible composite material sheet needs to meet, select the compressive strength, density, diameter, melting point, etc. of the hollow glass microspheres, and determine the model and dosage of the hollow glass microspheres.

[0099] Compound agents: including vulcanizing agents, accelerators, activators, anti-aging agents, fillers, etc. These compound agents can improve the processing performance and physical and mechanical properties of rubber.

[0100] Step 2, mixing: Add rubber, hollow glass microspheres and compound agents into the mixing equipment, such as an open mill or an internal mixer, according to a certain formula ratio. Through mechanical stirring and shearing action, the hollow glass microspheres and compound agents are evenly dispersed in the rubber to form a mixed rubber; during the mixing process, parameters such as temperature, time and feeding sequence need to be controlled to ensure the quality of the mixed rubber. In this embodiment, the formula ratio of rubber, hollow glass microspheres and compound agents is 6:3:1, and the mixing temperature is 170°C - 220°C.

[0101] Step 3, calendering: Calender the mixed rubber through a calender to make a film with a certain thickness and width. During the calendering process, parameters such as the roll gap, speed and temperature of the calender can be adjusted to control the thickness and surface quality of the film. Introduce a small amount of pretreated polyester synthetic fiber wire or mesh into the calender to make it closely adhere to the rubber sheet during the calendering process. By adjusting the fiber conveying speed and calender parameters, ensure a good bonding effect between the two to form a rubber sheet blank with a small amount of polyester fiber sandwiched. According to the target size of the flexible composite material sheet to be made, cut the size of the film through a cutting machine;

[0102] Step 4, stacking: Stack the film, polyester synthetic fiber wire or mesh in the mold in a predetermined order and number of layers in a staggered manner. When stacking, pay attention to the balance of the materials in the plane, and the height difference should not be too large. After stacking, perform pre-pressing, and then cover the mold cover and lock it after compaction; a multi-layer mold can be used to improve the space utilization efficiency.

[0103] Step 5, Vulcanization: Perform hot pressing and molding under certain temperature and pressure to further vulcanize and cure the rubber, and at the same time form good adhesion between the synthetic fiber and the rubber, as well as between the rubbers. The vulcanization temperature is set between 140°C and 180°C, the pressure is set at 20 MPa - 50 MPa, and the hot pressing time is 20 min - 40 min.

[0104] Among them, vulcanization is a key process in the production of flexible composite material sheets. It can cause cross-linking reactions of rubber molecules to form a three-dimensional network structure, thereby improving the physical and mechanical properties and chemical stability of the flexible composite material sheets. Vulcanization is usually carried out in a vulcanizing autoclave or a flat vulcanizing machine, and parameters such as vulcanization temperature, time, and pressure need to be controlled well. The vulcanization temperature is generally between 140°C and 180°C, and the vulcanization time depends on the thickness of the sheet and the type of rubber, generally ranging from dozens of minutes to several hours.

[0105] Step 6, Post-treatment: After the vulcanized flexible composite material sheets are trimmed and inspected, the qualified flexible composite material sheets with rubber as the base material are packaged.

[0106] Trimming: The vulcanized flexible composite material sheets may have some burrs and flashings, and need to be trimmed to make their dimensions and shapes meet the requirements.

[0107] Inspection: Inspect the appearance, dimensions, physical and mechanical properties, etc. of the sheets to ensure that the product quality meets the standards and customer requirements. The inspection items include thickness, width, length, hardness, density, tensile strength, elongation at break, adhesion strength, etc.

[0108] Packaging: Package the qualified flexible composite material sheets with rubber as the base material. Usually, packaging materials such as plastic films and woven bags are used to prevent the sheets from being damaged during transportation and storage.

[0109] When tested with an Instron 5967 universal testing machine, the material exhibits unique three-stage failure characteristics:

[0110] 1) Elastic stage (strain 0 - 12%): The modulus is stable at 850 - 900 MPa;

[0111] 2) Microcrack propagation stage (12 - 35%): Rely on the bridging effect of carbon nanotubes to maintain strength;

[0112] 3) Fiber fracture stage (>35%): The polyester fibers gradually break to absorb energy.

[0113] Hollow glass microspheres form a "honeycomb - skeleton" composite structure in the matrix, the breakage rate of the microspheres < 2%, and the interfacial bonding strength reaches 18 - 22 MPa.

[0114] Comparison Table of Performance Indicators of Material Specimens

[0115]

[0116] Example Three

[0117] Refer to Figure 1 A highly elastic composite buoyancy material with high compressive strength and high tensile strength. The difference from Example One is that the first elastic layer 22 and the second elastic layer 24 are synthetic resins.

[0118] A preparation method of a highly elastic composite buoyancy material with high compressive strength and high tensile strength using synthetic resin as the base material, including the following steps:

[0119] Step S1, Raw material preparation. Select synthetic resin as the base material, and select polyester synthetic fiber wire or mesh, hollow glass microspheres, and compounding agents;

[0120] According to the usage requirements of the board, select a suitable type of synthetic resin as the base material, fully considering factors such as its molecular weight, molecular structure, and the ratio of styrene to butadiene, etc., to meet the final performance requirements of the board, such as hardness, elasticity, tensile strength, etc.

[0121] Polyester synthetic fiber: According to the performance requirements of the board, select polyester synthetic fiber wire or felt, sheet with appropriate specifications (such as fiber density, monofilament fineness, fabric structure, etc.) and performance (such as strength, wear resistance, chemical resistance, etc.) as the reinforcing material. Pretreat the polyester fiber, such as removing surface oil, impurities, and moisture, etc., and methods such as cleaning and drying can be used to enhance the bonding performance with the synthetic resin. It should be noted that the density of the synthetic fiber should not be too dense, and space should be left to enable the synthetic resin adjacent to both sides of the polyester synthetic fiber to be fully bonded into one body.

[0122] Hollow glass microspheres: mainly play the role of reducing the density of the formed board, so that sufficient buoyancy can be generated when used in water. According to the stress situation and water depth of the usage working condition, determine the index requirements such as tensile strength, compressive strength, and density that the flexible composite material board needs to meet, select the compressive strength, density, diameter, melting point, etc. of the hollow glass microspheres, and determine the model and dosage of the hollow glass microspheres.

[0123] Compounding agents: Add additives such as plasticizers, anti-aging agents, lubricants, fillers, etc. as needed. Plasticizers can improve the flexibility and processing performance of synthetic resins; anti-aging agents can prevent synthetic resins from aging and deteriorating during use and extend the service life of the board; lubricants help improve the fluidity during processing; fillers can reduce costs and improve certain properties of the board, such as hardness and dimensional stability, etc. These compounding agents can improve the processing performance and physical and mechanical properties of synthetic resins.

[0124] Step S2: Kneading. Add synthetic resin, hollow glass microspheres, and compounding agents into a kneading device, such as an open mill or an internal mixer, according to a certain formula ratio. Knead at a temperature range of 150°C - 200°C and appropriate rotational speed conditions. Through mechanical stirring and shearing actions, make the hollow glass microspheres and compounding agents uniformly disperse in the synthetic resin to form a kneaded mixture. During the kneading process, parameters such as temperature, time, and feeding sequence need to be controlled well to ensure the quality of the kneaded mixture.

[0125] Step S3: Calendering. Pass the kneaded synthetic resin material through a calender to make a thin sheet with a certain thickness and width. Adjust the roller temperature between 160°C - 180°C, control the appropriate rotational speed and gap to ensure the thickness, uniformity, and surface quality of the material. At the same time, introduce a small amount of pretreated polyester synthetic fiber wire or mesh into the calender to make it closely adhere to the synthetic resin sheet during the calendering process. By adjusting the fiber conveying speed and calender parameters, ensure a good bonding effect between the two to form a synthetic resin blank with polyester fibers sandwiched. According to the target size of the flexible composite material sheet to be made, cut the size of the sheet-shaped synthetic resin through a cutting machine;

[0126] Step S4: Stacking. Stack the synthetic resin sheets, polyester synthetic fiber wire or mesh in a staggered manner according to a predetermined order and number of layers in a mold. After stacking, perform pre-pressing. After compaction, cover the mold cover plate and lock it; A multi-layer mold can be used to improve the space utilization efficiency.

[0127] Step S5: Molding. Place the mold in a hot press and perform hot press molding at a temperature of 180 - 220°C and a pressure of 10 - 30 MPa. The hot press time is 5 - 30 minutes; The hot press time depends on the thickness of the sheet and the size of the mold, generally 5 - 30 minutes. During this process, the synthetic resin further melts and flows, forms a stronger bond with the polyester fiber, and enables the sheet to obtain the required shape and dimensional accuracy.

[0128] Step S6: Post-treatment. After hot press molding, take the mold out of the hot press for cooling. Natural cooling or forced cooling (such as air cooling, water cooling) can be used to cool down the sheet to solidify it and maintain the formed shape. When cooling, prevent the sheet from being impacted by external forces or deformed.

[0129] After trimming and inspection processes for the flexible composite material sheet after hot press molding, package the qualified flexible composite material sheet with synthetic resin as the base material.

[0130] Trimming: The flexible composite material sheet after hot press molding may have some burrs and flashings, and trimming treatment is required to remove the edge burrs and uneven parts to make its surface smooth and dimensions accurate, meeting the technical requirements.

[0131] Inspection: Inspect the appearance, dimensions, physical and mechanical properties, etc. of the sheet material to ensure that the product quality meets the standards and customer requirements. The inspection items include thickness, width, length, hardness, density, tensile strength, elongation at break, adhesion strength, etc.

[0132] Packaging: Package the qualified flexible composite material sheets with synthetic resin as the base material. Usually, packaging materials such as plastic films and woven bags are used to prevent the sheets from being damaged during transportation and storage.

[0133] The implementation principle of the present invention is as follows: Materials manufactured using existing technologies cannot simultaneously possess the four properties of high compressive strength, high tensile strength, high elasticity, and a density lower than that of water to generate buoyancy, and cannot meet certain specific application requirements in the fields of ship and ocean engineering and other industrial fields. Aiming at the defects of the existing technology, the present invention has developed a structure and preparation method of a flexible composite material with rubber or synthetic resin and other similar materials as the base material. By selecting appropriate material components and their dosage ratios, the material components are mutually compatible and non-repellent, forming a unified whole. The manufactured flexible composite material can simultaneously possess the four properties of high compressive strength, high tensile strength, high elasticity, and a density lower than that of water to generate buoyancy, and can meet certain specific application requirements in the fields of ship and ocean engineering and other industrial fields. Its compressive strength can reach above 30 - 40 MPa, its tensile strength can reach above 20 MPa, it has a high rebound rate, and the density can be as low as 700 kg / m 3 .

[0134] The embodiments of the specific implementation manners are all preferred embodiments of the present invention, and do not limit the protection scope of the present invention accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-elastic composite buoyancy material with high compression resistance and high tensile resistance, characterized in that: The following steps are involved: Step 1, selecting natural rubber, synthetic rubber with a Mooney viscosity ML (1+4) of 45-60 at 100°C or polyurethane resin with a Shore hardness of 85A-95A as the base material; Step 2: Microbead pretreatment: compressive strength 110±5MPa, true density 460±20kg / m 3 , hollow glass microspheres with a particle size of 18-22 μm at D50 were ultrasonically treated in an ethanol solution of silane coupling agent KH-550 for 30-60 min; Step 3, gradient mixing: mixing in three stages in an internal mixer according to the mass ratio of substrate: hollow glass microsphere: vulcanizing agent = (5.8-6.2): ​​(2.9-3.1): (0.9-1.1); Step 4, fiber composite: Compound the plasma-treated 200-400D polyester fiber mesh with the mixed rubber through a three-roll calender, control the temperature of the upper roll at 80-100°C, the middle roll at 120-140°C, and the lower roll at 60-80°C to form a prepreg with a thickness of 0.5-1.2 mm; Step 5, orthogonal lamination: Lay 8-12 layers alternately at 0° / 90°, and apply epoxy adhesive containing 5-8wt% carbon nanotubes between the layers, with a coating amount per unit area of ​​15-25g / m 2 ; Step 6: Segmented vulcanization: In a flat vulcanizing press: The first stage: 130-140℃, pressure 18-22MPa, time 25-35min; The second stage: 160-170℃, pressure 35-40MPa, time 45-60min; Step 7, post-processing: After vulcanization, the material is cut and trimmed by water jet, and the density is tested to be ≤770kg / m 3 , compressive strength ≥38MPa, elongation at break ≥150%, then packed in nitrogen.

2. The method for preparing a high-compression-resistance, high-tensile-resistance and high-elasticity composite buoyancy material according to claim 1, characterized in that: In the step 3, the vulcanizing agent includes latex, zinc oxide, stearic acid, an accelerator and sulfur.

3. The method for preparing a high-elastic composite buoyancy material with high compression resistance and high tensile strength according to claim 1, characterized in that: In step 3, the three-stage mixing is: The first stage: 160-170℃, rotor speed 30-40rpm, mixing 3-5min; The second stage: heat up to 180-190℃, increase the speed to 50-60rpm, and mix for 8-12min; The third stage: cool down to 140-150℃, add antioxidant 4020, and mix for 2-3 minutes.

4. The method for preparing a high-elastic composite buoyancy material with high compression resistance and high tensile strength according to claim 1, characterized in that: The hollow glass microspheres have a diameter to wall thickness ratio of 1:22-1:28, are made of borosilicate glass, and have a thermal expansion coefficient that differs from that of the base material by ≤15%.

5. The method for preparing a high-compression-resistance, high-tensile-resistance and high-elasticity composite buoyancy material according to claim 1, characterized in that: The hollow glass microspheres have a compressive strength of 110 MPa, an actual density of 460 kg / m4, an average diameter of 20 μm, and a softening temperature of 600°C.

6. The method for preparing a high-elastic composite buoyancy material with high compression resistance and high tensile strength according to claim 1, characterized in that: The polyester fiber mesh is a biaxial woven structure, with a warp density of 50-60 strands / 10 cm, a weft density of 45-55 strands / 10 cm, and a single fiber diameter of 0.15-0.25 mm.

7. The method for preparing a high-compression-resistance, high-tensile-resistance and high-elasticity composite buoyancy material according to claim 1, characterized in that: Controlling the heating rate during the segmented vulcanization process: The temperature rises from the first stage to the second stage at a rate of 1.5-2°C / min; Maintain the temperature between 140 and 150 °C for 5 to 8 minutes for stress relaxation.

8. The method for preparing a high-compression-resistance, high-tensile-resistance and high-elasticity composite buoyancy material according to claim 1, characterized in that: The carbon nanotubes are multi-walled carbon nanotubes with a length of 10-30 μm, a diameter of 8-15 nm, and an interlayer shear strength of ≥50 MPa.

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