Preparation method of agglomerated diamond polyurethane polishing rod

Abstract

The invention discloses a preparation method of an agglomerated diamond polyurethane polishing rod, and relates to the field of polishing materials, the preparation method comprises the following steps: providing modified agglomerated diamond powder containing iron oxide particles and a polyurethane prepolymer containing polyol A and polyol B; preliminarily mixing the modified agglomerated diamond powder with a polyurethane prepolymer, introducing carbon dioxide, and carrying out supercritical dispersion treatment to obtain a first mixture; mixing the first mixture with a chain extender in a vacuum environment to obtain a second mixture; and the second mixture is placed in a mold to be cured, the modified agglomerated diamond powder is locked, and the polyurethane polishing rod with the directionally-arranged modified agglomerated diamond powder is obtained. The directionally-arranged modified agglomerated diamond powder serves as functional filler of the polyurethane polishing rod, the polyurethane polishing rod does not scratch materials, the polishing effect is improved, the polyurethane polishing rod has rigidity and flexibility through polyhydric alcohol A and polyhydric alcohol B, and the embrittlement condition is avoided.

Description

Technical Field

[0001] The invention relates to the field of polishing materials, in particular to a method for preparing an agglomerated diamond polyurethane polishing rod. Background Art

[0002] Polyurethane polishing rods are highly efficient finishing tools made from a polyurethane elastomer combined with abrasives. Their features include: high elasticity and cushioning to reduce workpiece damage, making them suitable for precision components; excellent self-sharpening properties, with even abrasive shedding and stable cutting force; and water and wear resistance, long life, and adaptability to wet polishing environments. They are widely used in polishing metals, non-metals, and optical components, meeting all requirements from rough polishing to mirror finishing.

[0003] The polyurethane polishing bodies obtained by the existing polyurethane polishing body preparation methods generally use single crystal diamond or cerium oxide as functional fillers, but their inherent defects lead to limited comprehensive performance. Single crystal diamond has a sharp crystal structure and is prone to scratching the surface of hard and brittle materials such as glass and sapphire during the polishing process, seriously restricting the yield of high-precision optical components, that is, the polishing effect is poor. Although cerium oxide can reduce the risk of scratching, its material removal rate is significantly low, and the processing efficiency cannot meet the needs of modern precision manufacturing. More importantly, the high-hardness polyurethane matrix designed to achieve high cutting efficiency generally has brittleness, and is prone to stress concentration under dynamic polishing loads, causing microcracks or even fracture failure.

[0004] Therefore, a method for preparing an agglomerated diamond polyurethane polishing rod is proposed to solve the above-mentioned problems of brittleness and poor polishing effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing an agglomerated diamond polyurethane polishing rod to solve the problems of easy brittleness and poor polishing effect.

[0006] To achieve this object, the present invention adopts the following technical solutions: A method for preparing an agglomerated diamond polyurethane polishing rod, comprising the following steps: Step S1, providing modified agglomerated diamond powder containing iron oxide particles and a polyurethane prepolymer containing polyol A and polyol B; Step S2: preliminarily mixing the modified agglomerated diamond powder with the polyurethane prepolymer, introducing carbon dioxide into the mixture for supercritical dispersion treatment to obtain a first mixture; Step S3, mixing the first mixture with a chain extender under a vacuum environment to obtain a second mixture; Step S4: placing the second mixture in a mold for solidification to lock the modified agglomerated diamond powder, thereby obtaining a polyurethane polishing rod having oriented modified agglomerated diamond powder.

[0007] The modified agglomerated diamond powder is obtained according to the following steps: Step S11, placing the agglomerated diamond powder in 30% hydrogen peroxide for ultrasonic cleaning and then drying to form hydroxyl groups on the surface; Step S12, placing the agglomerated diamond powder obtained in step S11 in a modification solution and mixing the mixture to obtain modified agglomerated diamond powder having Si-OC bonds formed on the surface; Step S13: placing the agglomerated diamond powder obtained in step S12 into a magnetic response mixed solution, and adding ammonia monohydrate dropwise to mix the mixture, thereby obtaining modified agglomerated diamond powder having magnetic particles on the surface.

[0008] In step S12, the solvent in the modified solution is a mixture of ethanol and water, the solute is γ-aminopropyltriethoxysilane, the mixing time is 2-2.5 hours, and the temperature is 35-40°C; In step S13, the magnetized particles are ferrosoferric oxide, the magnetically responsive mixed solution is a mixture of ferric chloride hexahydrate and ferrous chloride tetrahydrate, the molar ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate in the mixed solution is (2-3):1, the mixing time is 30-60 minutes, and the temperature is 60-70°C.

[0009] The polyurethane prepolymer is obtained according to the following steps: Step S14, mixing polyol A and polyol B in a mass ratio of (3-4):1, and adding a catalyst to obtain a mixture A; Step S15: Mixing mixture A with MDI, and adding a dynamic crosslinking agent during the mixing process to obtain a polyurethane prepolymer.

[0010] In step S14, the mixing temperature is 40-50°C, the mixing time is 10 minutes, and the mixing speed is 300-500 rpm; In step S15, the mixing time is 1-2 hours, the temperature is 65-75° C., and the rotation speed is 300-500 rpm.

[0011] The step S2 specifically includes the following steps: Step S21, preliminarily mixing the modified agglomerated diamond powder and the polyurethane prepolymer to obtain a mixture B; Step S22: placing the mixture B in a supercritical carbon dioxide reactor and stirring it with liquid carbon dioxide to uniformly disperse the modified agglomerated diamond powder in the polyurethane prepolymer to obtain a first mixture.

[0012] In step S21, the mixing time is 5-10 min and the rotation speed is 200-300 rpm; In step S22, the mixing temperature is 35-40°C, the pressure is 7-10 MPa, the rotation speed is 100-200 rpm, and the time is 30-40 minutes.

[0013] In step 3, the first mixture is placed in a vacuum mixing kettle, and a chain extender is added. The first mixture and the chain extender are stirred and mixed at a stirring speed of 100-200 rpm and a stirring temperature of 25-35° C. for no more than 5 minutes to obtain a second mixture.

[0014] The step S4 specifically includes the following steps: Step S41: providing a non-magnetic steel mold with an internal electromagnetic coil and coated with a release agent; Step S42: injecting the second mixture into a mold, applying a magnetic field to align the modified agglomerated diamond powder, and then thermally curing the second mixture in the mold to lock the aligned modified agglomerated diamond powder. After curing is completed, a polyurethane polishing body is obtained, and then the polyurethane polishing body is trimmed to obtain a polyurethane polishing rod.

[0015] In step S41, the mold is in the shape of a long strip, and the magnetic induction direction of the electromagnetic coil is distributed along the axis direction of the mold; In the step S42, the thermal curing temperature is 50-80°C, the time is 4-8 hours, the directional alignment time is 30-60 minutes, and the magnetic field strength is 10-50 mT.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a method for preparing an agglomerated diamond polyurethane polishing rod. Directly arranged modified agglomerated diamond powder is used as a functional filler for the polyurethane polishing rod. The obtained polyurethane polishing rod not only does not scratch materials during polishing but also improves the polishing effect of the polyurethane polishing rod. In addition, polyol A and polyol B can make the obtained polyurethane polishing rod have both rigidity and flexibility to avoid embrittlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] The structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not intended to limit the conditions under which the present invention can be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and objectives that can be achieved by the present invention.

[0019] Figure 1 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally located component.

[0022] Example 1: See also Figure 1 In this embodiment, a method for preparing an agglomerated diamond polyurethane polishing rod is provided, and the preparation method comprises the following steps: Step S1, providing modified agglomerated diamond powder containing iron oxide particles and a polyurethane prepolymer containing polyol A and polyol B; It should be noted that by selecting modified agglomerated diamond powder as the functional filler of the polyurethane polishing rod and the polyurethane prepolymer containing polyol A and polyol B, the subsequently prepared polyurethane polishing rod can have both rigidity and flexibility to avoid embrittlement. During polishing, it not only does not scratch the material but also improves the polishing effect of the polyurethane polishing rod.

[0023] It should also be noted that the agglomerated diamond powder is spherical and has a multi-edged structure at the microscopic level. The agglomerated diamond powder is spherical and is isotropic. When used in polyurethane polishing rods, it is not easy to produce large scratches. It has the advantages of high speed, few scratches and good roughness, thereby ensuring the polishing effect of the polyurethane polishing rod.

[0024] Specifically, the modified agglomerated diamond powder is obtained according to the following steps: Step S11, placing the agglomerated diamond powder in 30% hydrogen peroxide for ultrasonic cleaning and then drying to form hydroxyl groups on the surface; It should be noted that after the agglomerated diamond powder is cleaned and dried, the hydroxyl groups formed on its surface are used to cooperate with the subsequent steps; the agglomerated diamond powder is ultrasonically cleaned using an ultrasonic cleaning machine. The ultrasonic cleaning machine generates tiny bubbles through ultrasonic oscillation, and the tiny bubbles quickly burst on the surface of the agglomerated diamond powder, thereby removing impurities, oil or other pollutants attached to its surface; the cleaned agglomerated diamond powder is dried using a vacuum drying oven. The vacuum drying oven evaporates the moisture in the agglomerated diamond powder through a vacuum environment to prevent the moisture from affecting the subsequent processing of the agglomerated diamond powder. Under a vacuum state, the evaporation rate of moisture is faster, which can accelerate the drying process.

[0025] Step S12, placing the agglomerated diamond powder obtained in step S11 in a modification solution and mixing the mixture to obtain modified agglomerated diamond powder having Si-OC bonds formed on the surface; In step S12, the solvent in the modified solution is a mixture of ethanol and water, the solute is γ-aminopropyltriethoxysilane, the mixing time is 2-2.5 hours, and the temperature is 35-40°C; preferably, the mixing time is 2 hours and the temperature is 40°C. It should be noted that the surface of agglomerated diamond powder has strong polarity and high surface energy, and is prone to chemical reactions with external substances. By modifying its surface, its bonding strength with the polyurethane prepolymer can be improved. Under the action of the amino group in γ-aminopropyltriethoxysilane, covalent bonds can be formed on the surface of the agglomerated diamond powder to enhance the affinity between the agglomerated diamond powder and polyurethane. The amino groups contained in γ-aminopropyltriethoxysilane interact with the carboxyl groups on the surface of the agglomerated diamond powder to form stable chemical bonds, ultimately forming an organic silicon layer on the surface of the agglomerated diamond powder to enhance the adhesion between the agglomerated diamond powder and the polyurethane prepolymer, thereby laying the foundation for the mixing of the agglomerated diamond powder and the polyurethane prepolymer.

[0026] Step S13: placing the agglomerated diamond powder obtained in step S12 into a magnetic response mixed solution, and adding ammonia monohydrate dropwise to mix the mixture, thereby obtaining modified agglomerated diamond powder having magnetic particles on the surface.

[0027] In step S13, the magnetized particles are ferrosoferric oxide, the magnetically responsive mixed solution is a mixture of ferric chloride hexahydrate and ferrous chloride tetrahydrate, the molar ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate in the mixed solution is (2-3):1, the mixing time is 30-60 minutes, and the temperature is 60-70°C; preferably, the molar ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate in the mixed solution is 2:1, the mixing time is 45 minutes, and the temperature is 65°C.

[0028] It should be noted that ferrosoferric oxide, which serves as magnetized particles, is deposited on the surface of the agglomerated diamond powder by a co-precipitation method, giving the agglomerated diamond powder magnetism to form modified agglomerated diamond powder. It can be seen that the magnetized particles will be distributed along the surface of the agglomerated diamond powder, so that the modified agglomerated diamond powder has magnetic responsiveness, so as to facilitate uniform distribution and arrangement in the subsequent preparation of polyurethane polishing rods. When the modified agglomerated diamond powder is evenly distributed and arranged, it can effectively improve the polishing effect and consistency of the subsequent polyurethane polishing rods.

[0029] Specifically, the polyurethane prepolymer is obtained according to the following steps: Step S14, mixing polyol A and polyol B in a mass ratio of (3-4):1, and adding a catalyst to obtain a mixture A; preferably, the mass ratio of polyol A to polyol B is 4:1; In step S14, the mixing temperature is 40-50°C, the time is 10 minutes, the rotation speed is 300-500 rpm, the catalyst is dibutyltin dilaurate catalyst, the polyol A contains an aromatic ring, and the polyol B contains a urea group or a carboxyl group; preferably, the mixing temperature is 50°C, the time is 8 minutes, and the rotation speed is 450 rpm.

[0030] It should be noted that a uniform mixture A is formed by stirring polyol A and polyol B, and a rigid-flexible composite network is formed in the mixture A. During the mixing process, the catalyst can also control the reaction rate to avoid local overreaction causing a sudden change in the viscosity of the mixture A, which affects the formation of the rigid-flexible composite network.

[0031] It should also be noted that mixture A has both rigidity and flexibility under the action of polyol A and polyol B. The aromatic ring in polyol A provides strong rigidity, restricting the free rotation of the polymer chain segments. The π-π conjugation effect and macromolecular structure of the aromatic ring increase the glass transition temperature and mechanical strength of mixture A, thereby enhancing the rigidity of the obtained polyurethane prepolymer. The urea or carboxyl group contained in polyol B is cross-linked with other chain segments and modified agglomerated diamond powder in the subsequently prepared polyurethane prepolymer through hydrogen bonds to form a dynamic hydrogen bond network. The urea or carboxyl group has a certain polarity, which can make the polyurethane prepolymer have better flexibility and buffering effect, thereby reducing crack propagation.

[0032] It should be emphasized that polyol A provides strength, wear resistance and heat resistance for the subsequently produced polyurethane polishing rod, ensuring that the produced polyurethane polishing rod has sufficient hardness (Shore D ≥ 70) and durability; while polyol B provides a flexible buffer layer for the polyurethane chain segments in the polyurethane prepolymer through the action of hydrogen bonds or ionic bonds, preventing the subsequently produced polyurethane polishing rod from becoming brittle under high hardness, and at the same time can enhance toughness, especially playing a reinforcing role in the interface bonding between the polyurethane prepolymer and the modified agglomerated diamond powder, avoiding the shedding of the modified agglomerated diamond powder.

[0033] It is worth noting that between polyol A and polyol B, the hydrogen bonds of the urea or carboxyl groups can interact with the amino or carboxyl groups in the aromatic ring to form a strong dynamic hydrogen bond network. The reversible properties of hydrogen bonds allow the dynamic hydrogen bond network to adjust its own conformation under changes in the external environment (such as temperature, pressure, etc.) to alleviate stress concentration in the subsequently produced polyurethane polishing rod, alleviate brittleness, and prevent crack expansion or failure.

[0034] In addition, after polyol A and polyol B interact through chemical reactions, they form a balanced rigid-flexible composite network. The rigid part provides support and strength, while the flexible part reduces stress concentration through buffering and plastic deformation, thereby reducing the brittle fracture tendency of the subsequently produced polyurethane polishing rod. As the hardness increases, the chain segments become denser, the intermolecular shear force increases, and the fluidity of the molecular chain decreases moderately, further enhancing the material's resistance to deformation.

[0035] Step S15: Mixing mixture A with MDI (4,4'-diphenylmethane diisocyanate), and adding a dynamic crosslinking agent during the mixing process to obtain a polyurethane prepolymer.

[0036] In the step S15, the mixing time is 1-2 hours, the temperature is 65-75° C., and the rotation speed is 300-500 rpm; preferably, the mixing time is 1.5 hours, the temperature is 70° C., and the rotation speed is 500 rpm.

[0037] It should be noted that the isocyanate groups in MDI react with the hydroxyl groups in polyol A and polyol B to form a polyurethane main chain with higher hardness. At this time, the end of the polyurethane has an isocyanate group to facilitate the subsequent cross-linking reaction.

[0038] It should be emphasized that when the isocyanate group and the hydroxyl group undergo addition reaction, the ratio of isocyanate group to hydroxyl group needs to be controlled at (1.05-1.1):1 to ensure the completeness of the addition reaction and avoid excessive isocyanate groups, which will lead to excessive unreacted isocyanate groups, resulting in incomplete reaction or excessive cross-linking, causing the subsequently prepared polyurethane polishing rod to become brittle; excessive hydroxyl groups may lead to insufficient cross-linking, affecting the hardness.

[0039] It should also be noted that the dynamic cross-linking agent is added after the mixture A and MDI are mixed. The dynamic cross-linking agent has a UPy group (uracil group). After the UPy group combines with the dynamic hydrogen bond network in the mixture A, it further increases the toughness and crack resistance of the subsequently prepared polyurethane polishing rod. At the same time, the UPy group allows the subsequently prepared polyurethane polishing rod to self-repair cracks or delay the generation of microcracks under the reversible performance of the dynamic hydrogen bond network, thereby improving durability.

[0040] Step S2: preliminarily mixing the modified agglomerated diamond powder with the polyurethane prepolymer, introducing carbon dioxide into the mixture for supercritical dispersion treatment to obtain a first mixture; It should be noted that the physical properties of supercritical carbon dioxide are used to improve the dispersibility of the modified agglomerated diamond powder in polyurethane and prevent diamond agglomeration.

[0041] The step S2 specifically includes the following steps: Step S21, preliminarily mixing the modified agglomerated diamond powder and the polyurethane prepolymer to obtain a mixture B; In step S21, the mixing time is 5-10 minutes and the rotation speed is 200-300 rpm; preferably, the mixing time is 5 minutes and the rotation speed is 300 rpm; It should be noted that the modified agglomerated diamond powder is preliminarily mixed with the polyurethane prepolymer to form a preliminary dispersion, which provides a basis for the subsequent supercritical carbon dioxide treatment of the mixture B.

[0042] Step S22: placing the mixture B in a supercritical carbon dioxide reactor and stirring it with liquid carbon dioxide to uniformly disperse the modified agglomerated diamond powder in the polyurethane prepolymer to obtain a first mixture.

[0043] In step S22, the mixing temperature is 35-40°C, the pressure is 7-10 MPa, the rotation speed is 100-200 rpm, and the time is 30-40 min; preferably, the mixing temperature is 40°C, the pressure is 8 MPa, the rotation speed is 200 rpm, and the time is 35 min.

[0044] It should be noted that supercritical carbon dioxide has high permeability and low viscosity. In the supercritical state of carbon dioxide, it can quickly penetrate into the surface of the modified agglomerated diamond powder and destroy the agglomerated structure. After the supercritical carbon dioxide enters the tiny gaps in the modified agglomerated diamond powder, it can reduce the van der Waals force between the modified agglomerated diamond powder, so that the modified agglomerated diamond powder can be dispersed more effectively. Supercritical carbon dioxide can maintain the structural stability of the modified agglomerated diamond powder while improving its dispersibility in the polyurethane prepolymer.

[0045] It can be seen that due to the supercritical state of carbon dioxide, it can form microbubbles in mixture B to drive the uniform distribution of the modified agglomerated diamond powder, preventing agglomeration in the subsequent molding process. The evenly distributed modified agglomerated diamond powder helps the directional cutting performance of the polishing rod and avoids the polishing unevenness and cutting force instability caused by diamond agglomeration.

[0046] Step S3, mixing the first mixture with a chain extender under a vacuum environment to obtain a second mixture; Specifically, in step S3, the first mixture is placed in a vacuum mixing kettle, and a chain extender is added. The first mixture and the chain extender are stirred and mixed at a stirring speed of 100-200 rpm and a stirring temperature of 25-35° C. for no more than 5 minutes to obtain a second mixture; preferably, the stirring speed is 150 rpm and the stirring temperature is 30° C.

[0047] It should be noted that the chain extender is 1,4-butanediol chain extender, which reacts with the isocyanate groups in the polyurethane prepolymer to form a long chain structure. The second mixture after chain extension presents long molecular chain segments at the microscopic level, thereby improving the mechanical properties and thermal stability of the subsequently prepared polyurethane polishing rod.

[0048] It should be emphasized that a chain extension reaction occurs during the mixing process of the first mixture and the chain extender, causing the molecular segments in the first mixture to be rearranged to generate a network structure with a higher degree of cross-linking, thereby improving the hardness and stability of the subsequently prepared polyurethane polishing rod.

[0049] It should also be noted that, during the mixing process, the vacuum environment can also remove bubbles generated during the reaction to ensure the quality of the second mixture.

[0050] Step S4: placing the second mixture in a mold for solidification to lock the modified agglomerated diamond powder, thereby obtaining a polyurethane polishing rod having oriented modified agglomerated diamond powder.

[0051] The step S4 specifically includes the following steps: Step S41: providing a non-magnetic steel mold with an internal electromagnetic coil and coated with a release agent; In step S41, the mold is in the shape of a long strip, and the magnetic induction direction of the electromagnetic coil is distributed along the axis direction of the mold; It should be noted that the mold is used to fix and shape the obtained second mixture, and a heating element is also provided on the mold to thermally cure the second mixture through the heating element; it can be known that the setting mode and working principle of the heating element and the electromagnetic coil are well known to those skilled in the art and will not be described in this embodiment. The release agent can make subsequent demolding more convenient.

[0052] Step S42: injecting the second mixture into a mold, applying a magnetic field to align the modified agglomerated diamond powder, and then thermally curing the second mixture in the mold to lock the aligned modified agglomerated diamond powder. After curing is completed, a polyurethane polishing body is obtained, and then the polyurethane polishing body is trimmed to obtain a polyurethane polishing rod.

[0053] In step S42, the thermal curing temperature is 50-80°C, the time is 4-8 hours, the directional alignment time is 30-60 minutes, and the magnetic field strength is 10-50mT; preferably, the thermal curing temperature is 60°C, the time is 5 hours, the directional alignment time is 50 minutes, and the magnetic field strength is 40mT.

[0054] It should be noted that after the thermal curing begins, the applied magnetic field will cause the modified agglomerated diamond powder to respond magnetically through the magnetic particles on the modified agglomerated diamond powder. The modified agglomerated diamond powder after the magnetic response will be arranged along the direction of the magnetic field under the action of the magnetic field. At the same time, as the second mixture solidifies, the modified agglomerated diamond powder arranged along the direction of the magnetic field is locked, forming a directional arrangement. The directional arrangement of the modified agglomerated diamond powder optimizes the cutting ability of the polishing rod and avoids local wear caused by traditional random distribution. The directional arrangement ensures consistency during the cutting process and avoids local excessive wear.

[0055] It can be known that the externally applied magnetic field guides the directional arrangement of the modified agglomerated diamond powder through magnetic particles. The modified agglomerated diamond powder is not only arranged in the axial direction, but also forms an ideal cutting surface through continuous adjustment of the magnetic field. The directional arrangement of the magnetic field can make the modified agglomerated diamond powder arranged in an orderly manner along the axial direction of the subsequently obtained polyurethane polishing rod, thereby ensuring the stability and cutting efficiency of the polyurethane polishing rod during work; in addition, the regulation of the magnetic field can adjust the arrangement of the modified agglomerated diamond powder as needed, thereby affecting the performance of the polyurethane polishing rod to meet the needs of different processes.

[0056] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing agglomerated diamond polyurethane polishing rod, characterized in that: The preparation method comprises the following steps: Step S1, providing modified agglomerated diamond powder containing iron oxide particles and a polyurethane prepolymer containing polyol A and polyol B; Step S2: preliminarily mixing the modified agglomerated diamond powder with the polyurethane prepolymer, introducing carbon dioxide into the mixture for supercritical dispersion treatment to obtain a first mixture; Step S3, mixing the first mixture with a chain extender under a vacuum environment to obtain a second mixture; Step S4: placing the second mixture in a mold for solidification to lock the modified agglomerated diamond powder, thereby obtaining a polyurethane polishing rod having oriented modified agglomerated diamond powder.

2. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 1, wherein The modified agglomerated diamond powder is obtained according to the following steps: Step S11, placing the agglomerated diamond powder in 30% hydrogen peroxide for ultrasonic cleaning and then drying to form hydroxyl groups on the surface; Step S12, placing the agglomerated diamond powder obtained in step S11 in a modification solution and mixing the mixture to obtain modified agglomerated diamond powder having Si-OC bonds formed on the surface; Step S13: placing the agglomerated diamond powder obtained in step S12 into a magnetic response mixed solution, and adding ammonia monohydrate dropwise to mix the mixture, thereby obtaining modified agglomerated diamond powder having magnetic particles on the surface.

3. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 2, wherein: In step S12, the solvent in the modified solution is a mixture of ethanol and water, the solute is γ-aminopropyltriethoxysilane, the mixing time is 2-2.5 hours, and the temperature is 35-40°C; In step S13, the magnetized particles are ferrosoferric oxide, the magnetically responsive mixed solution is a mixture of ferric chloride hexahydrate and ferrous chloride tetrahydrate, the molar ratio of ferric chloride hexahydrate to ferrous chloride tetrahydrate in the mixed solution is (2-3):1, the mixing time is 30-60 minutes, and the temperature is 60-70°C.

4. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 1, wherein: The polyurethane prepolymer is obtained according to the following steps: Step S14, mixing polyol A and polyol B in a mass ratio of (3-4):1, and adding a catalyst to obtain a mixture A; Step S15: Mixing mixture A with MDI, and adding a dynamic crosslinking agent during the mixing process to obtain a polyurethane prepolymer.

5. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 4, characterized in that: In step S14, the mixing temperature is 40-50°C, the mixing time is 10 minutes, and the mixing speed is 300-500 rpm; In step S15, the mixing time is 1-2 hours, the temperature is 65-75° C., and the rotation speed is 300-500 rpm.

6. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 1, characterized in that: The step S2 specifically includes the following steps: Step S21, preliminarily mixing the modified agglomerated diamond powder and the polyurethane prepolymer to obtain a mixture B; Step S22: placing the mixture B in a supercritical carbon dioxide reactor and stirring it with liquid carbon dioxide to uniformly disperse the modified agglomerated diamond powder in the polyurethane prepolymer to obtain a first mixture.

7. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 6, characterized in that: In step S21, the mixing time is 5-10 min and the rotation speed is 200-300 rpm; In step S22, the mixing temperature is 35-40°C, the pressure is 7-10 MPa, the rotation speed is 100-200 rpm, and the time is 30-40 minutes.

8. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 1, characterized in that: In step 3, the first mixture is placed in a vacuum mixing kettle, and a chain extender is added. The first mixture and the chain extender are stirred and mixed at a stirring speed of 100-200 rpm and a stirring temperature of 25-35° C. for no more than 5 minutes to obtain a second mixture.

9. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 1, characterized in that: The step S4 specifically includes the following steps: Step S41: providing a non-magnetic steel mold with an internal electromagnetic coil and coated with a release agent; Step S42: injecting the second mixture into a mold, applying a magnetic field to align the modified agglomerated diamond powder, and then thermally curing the second mixture in the mold to lock the aligned modified agglomerated diamond powder. After curing is completed, a polyurethane polishing body is obtained, and then the polyurethane polishing body is trimmed to obtain a polyurethane polishing rod.

10. The method for preparing the agglomerated diamond polyurethane polishing rod according to claim 9, characterized in that: In step S41, the mold is in the shape of a long strip, and the magnetic induction direction of the electromagnetic coil is distributed along the axis direction of the mold; In the step S42, the thermal curing temperature is 50-80°C, the time is 4-8 hours, the directional alignment time is 30-60 minutes, and the magnetic field strength is 10-50 mT.

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