Cubic boron nitride resin grinding wheel and preparation method thereof

Abstract

The invention discloses a cubic boron nitride resin grinding wheel and a preparation method thereof, and belongs to the technical field of cubic boron nitride grinding wheels. The raw materials comprise, by weight, 4-8 parts of aluminum oxide, 40-50 parts of modified phenolic resin, 30-40 parts of cubic boron nitride powder, 10-20 parts of copper, and 2-4 parts of a lubricant. Aluminum oxide and modified phenolic resin are added into the prepared cubic boron nitride resin grinding wheel to serve as binding agents; aluminum oxide can enhance the heat resistance, heat dissipation and easy-to-wear performance of the grinding wheel; the phenolic resin can improve the self-sharpening property and grinding efficiency of the grinding wheel, the phenolic resin is modified, the mechanical property, heat resistance and certain flame retardant property of the phenolic resin are greatly enhanced, and the performance is long and stable. Therefore, the prepared cubic boron nitride resin grinding wheel is good in self-sharpening property, grinding efficiency and mechanical property, stable and efficient in heat resistance and certain in flame retardance, and has important application value in the technical field of cubic boron nitride grinding wheels.

Description

Technical Field

[0001] The invention belongs to the technical field of cubic boron nitride grinding wheels, and in particular relates to a cubic boron nitride resin grinding wheel and a preparation method thereof. Background Art

[0002] Cubic boron nitride resin grinding wheel is a grinding tool made of cubic boron nitride as abrasive and resin binder through high pressure and high temperature polymerization. Cubic boron nitride resin grinding wheel has high hardness, high strength, high grinding efficiency, high wear resistance, little consumption of abrasive grains themselves, and a very long service life, especially when grinding hard and brittle workpieces; the abrasive grains have high hardness and wear resistance, the abrasive grains can remain sharp for a long time, and can easily cut into the workpiece, achieving low stress grinding, and the workpieces ground have high precision and good surface quality. It is mainly used for grinding high and hard alloys, non-metallic materials, cutting hard and brittle carbide, non-metallic minerals, etc. Such as carbide, ceramics, agate, optical glass, semiconductor materials, wear-resistant cast iron, stone, etc. Due to its excellent performance, it is widely used in various fields such as mechanical processing, automobile manufacturing, aerospace, biology, medical equipment, electronic information, construction, transportation, geological mining, art, new materials, etc.

[0003] Cubic boron nitride resin grinding wheels use resin as a binder, which has good self-sharpening properties, high grinding efficiency, low grinding heat, and can improve the roughness of the workpiece surface. Common resin binders include phenolic resin, polyimide resin, polyamide resin, epoxy resin, polyurethane resin, aralkyl phenolic resin, etc. Among them, phenolic resin is the most common resin binder with low price, excellent corrosion resistance and flame retardancy, and occupies the largest market share in traditional grinding wheels. The phenolic hydroxyl and methylene groups on the phenolic resin structure are easily oxidized, and the heat resistance is affected. Moreover, the cured phenolic resin is brittle and lacks toughness because the aromatic nuclei are only connected by methylene groups. Therefore, it is urgent to solve this problem to meet the higher demands in the field of cubic boron nitride grinding wheel technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a cubic boron nitride resin grinding wheel and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a cubic boron nitride resin grinding wheel comprises the following steps:

[0007] A1. Put alumina and modified phenolic resin into a mixer and mix for 12 hours, then add cubic boron nitride powder, copper and lubricant and stir and mix for 12 hours to obtain a mixture;

[0008] A2, the mixture obtained in step A1 and the aluminum grinding wheel matrix are loaded into a mold, pressed and formed under high temperature and high pressure for 10-20 minutes, and then heat-cured for 2-3 hours under normal pressure, and demolded to obtain a pre-cured cubic boron nitride resin grinding wheel;

[0009] A3, placing the pre-cured cubic boron nitride resin grinding wheel obtained in step A2 into an oven for re-curing, and performing turning and grinding after curing to obtain a cubic boron nitride resin grinding wheel.

[0010] Furthermore, the high temperature and high pressure conditions in step A2 are 130-170° C. and the pressure is 100-120 MPa.

[0011] Furthermore, the temperature of heat preservation and curing in step A2 is 130-170°C.

[0012] Furthermore, the re-curing temperature in step A3 is 140-180°C

[0013] Furthermore, the raw materials are calculated in parts by weight as follows: 4-8 parts of aluminum oxide, 40-50 parts of modified phenolic resin, 30-40 parts of cubic boron nitride powder, 10-20 parts of copper, and 2-4 parts of lubricant.

[0014] Furthermore, the lubricant is one of paraffin and epoxidized soybean oil.

[0015] A mixed binder of ceramic and resin is used, which has the excellent properties of both. The alumina ceramic binder can improve the heat resistance, heat dissipation and wear resistance of the grinding wheel body, and can prevent the grinding wheel base from burning or scratching the workpiece when it contacts the workpiece, while the phenolic resin binder can improve the self-sharpening and grinding efficiency of the grinding wheel.

[0016] Furthermore, the modified phenolic resin is prepared by the following steps:

[0017] Add boric acid, phenol and n-butanol into a three-necked flask and keep stirring until the solid is completely dissolved. Then add NaOH solution and control the reaction temperature to 85-95°C. Keep the temperature for reaction for 3-4 hours to obtain a borate solution. Add a modifier and keep the temperature with polyformaldehyde (solid) for reaction for 4-6 hours under ultrasonic-assisted dispersion. After the reaction is completed, heat and pressurize to solidify the base resin to obtain a modified phenolic resin.

[0018] Furthermore, the usage ratio of the boric acid, phenol, n-butanol, NaOH solution, modifier and paraformaldehyde is 11g:60g:200mL:20mL:5-15g:25g.

[0019] Adding boric acid can replace the hydrogen in the phenolic hydroxyl group with a boron atom. The resulting BO bond has high bond energy, which can improve the heat resistance of the phenolic resin matrix. The BO bond also has good flexibility, which can reduce the brittleness of the matrix resin to a certain extent and improve the mechanical properties of the phenolic resin.

[0020] Furthermore, the modifier is prepared by the following steps:

[0021] S1. At room temperature, under nitrogen protection, 3-aminopropane sulfonic acid, NaOH solution (mass fraction 12%) and tetrahydrofuran were mixed in a three-necked flask equipped with a stirring reflux device. After stirring for 2 hours, 4-bromo-1-butene was added, and the reaction temperature was controlled to 70°C. The reaction was refluxed for 4 hours. After the reaction was completed, part of the solvent was first removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / methanol in a volume ratio of 4:1). The eluent was removed by rotary evaporation to obtain intermediate 1; the ratio of the amount of 3-aminopropane sulfonic acid, NaOH solution, tetrahydrofuran and 4-bromo-1-butene was 13.9 g:50 mL:100 mL:13.3 g;

[0022] 3-Aminopropanesulfonic acid and 4-bromo-1-butene undergo nucleophilic substitution, and the NaOH solution can not only generate sodium sulfonate, but also neutralize the hydrogen bromide generated by the reaction, accelerate the reaction, and obtain intermediate 1; the specific reaction process is as follows:

[0023]

[0024] S2. Add hydrogenated silicone oil, N,N-dimethylformamide and Speier catalyst to a three-necked flask equipped with a stirring reflux device, stir at room temperature for 60 minutes, add intermediate 1, raise the temperature to 75°C, and keep the reaction for 8 hours. Stir continuously during the reaction. After the reaction is completed, stop heating, wait for the device to cool to room temperature, stir for 2 hours, filter, and remove the solvent by rotary evaporation to obtain a modifier; the ratio of hydrogenated silicone oil, N,N-dimethylformamide, Speier catalyst, and intermediate 1 is 10g:100mL:0.4mL:21.6g;

[0025] Under the catalysis of Speier catalyst, hydrogen-containing silicone oil and the unsaturated carbon-carbon double bond of intermediate 1 undergo a hydrosilylation reaction to obtain a modifier; the specific reaction process is as follows:

[0026]

[0027] The prepared modifier molecule is mainly composed of a polysiloxane chain, and the main chain of the polysiloxane is composed of a silicon-oxygen bond (Si-O bond). The bond energy of this bond is relatively high, which can greatly enhance the heat resistance of the phenolic resin matrix. The silicon-oxygen bond has flexibility and can also enhance the mechanical properties of the matrix. In addition, the modifier molecule also contains a sodium sulfonate group. As an anionic surfactant, sodium sulfonate can timely capture hydrogen atoms generated by high-temperature decomposition of the phenolic resin, inhibit further breakage of the molecular chain, and further improve the thermal stability of the phenolic resin. Finally, the modifier molecule also contains heteroatoms such as sulfur and nitrogen, which can enhance the flame retardancy of the phenolic resin matrix to a certain extent.

[0028] It should be noted that the prepared modifier is a macromolecule, which is less likely to migrate and seep out than small molecule modifiers and has better stability.

[0029] Beneficial effects of the present invention:

[0030] The cubic boron nitride resin grinding wheel prepared by the present invention is added with aluminum oxide and modified phenolic resin as a binder;

[0031] 1. Alumina can enhance the heat resistance, heat dissipation and wear resistance of the grinding wheel;

[0032] 2. Phenolic resin can improve the self-sharpening and grinding efficiency of the grinding wheel. By modifying the phenolic resin, the mechanical properties, heat resistance and certain flame retardant properties of the phenolic resin are greatly enhanced, and the performance is long-lasting and stable;

[0033] Therefore, the cubic boron nitride resin grinding wheel prepared by the present invention has good self-sharpening, grinding efficiency and mechanical properties, and also has stable and efficient heat resistance and certain flame retardancy, and has important application value in the technical field of cubic boron nitride grinding wheels. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] Preparation of modifier:

[0037] S1. At room temperature, under nitrogen protection, 13.9 g of 3-aminopropanesulfonic acid, 50 mL of NaOH solution (mass fraction 12%) and 100 mL of tetrahydrofuran were mixed in a three-necked flask equipped with a stirring reflux device. After stirring for 2 h, 13.3 g of 4-bromo-1-butene was added. The reaction temperature was controlled to 70°C and refluxed for 4 h. After the reaction was completed, part of the solvent was first removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / methanol in a volume ratio of 4:1), and the eluent was removed by rotary evaporation to obtain intermediate 1;

[0038] S2. Add 10 g of hydrogenated silicone oil, 100 mL of N,N-dimethylformamide and 0.4 mL of Speier catalyst into a three-necked flask equipped with a stirring reflux device, stir at room temperature for 60 min, then add 21.6 g of intermediate 1, raise the temperature to 75 ° C, and keep the reaction for 8 h. Stir continuously during the reaction. After the reaction is completed, stop heating, wait for the device to cool to room temperature, stir for 2 h, filter, and evaporate to remove the solvent to obtain a modifier; wherein the Speier catalyst is prepared by dissolving 0.1 g of chloroplatinic acid in 100 mL of isopropanol and stirring at room temperature.

[0039] Embodiment 2

[0040] Preparation of modifier:

[0041] S1. At room temperature, under nitrogen protection, 27.8 g of 3-aminopropanesulfonic acid, 100 mL of NaOH solution (mass fraction 12%) and 200 mL of tetrahydrofuran were mixed in a three-necked flask equipped with a stirring reflux device. After stirring for 2 h, 26.6 g of 4-bromo-1-butene was added. The reaction temperature was controlled to 70°C and refluxed for 4 h. After the reaction was completed, part of the solvent was first removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / methanol, and the volume ratio of the two was 4:1). The eluent was removed by rotary evaporation to obtain intermediate 1;

[0042] S2. Add 20 g of hydrogenated silicone oil, 200 mL of N,N-dimethylformamide and 0.8 mL of Speier catalyst into a three-necked flask equipped with a stirring reflux device. After stirring at room temperature for 60 min, add 43.2 g of intermediate 1, raise the temperature to 75 ° C, and keep the reaction for 8 h. Stir continuously during the reaction. After the reaction is completed, stop heating, wait for the device to cool to room temperature, stir for 2 h, filter, and rotary evaporate to remove the solvent to obtain a modifier; wherein the Speier catalyst is prepared by dissolving 0.1 g of chloroplatinic acid in 100 mL of isopropanol and stirring at room temperature.

[0043] Embodiment 3

[0044] Preparation of modified phenolic resin:

[0045] 11 g of boric acid, 60 g of phenol and 200 mL of n-butanol were added to a three-necked flask and stirred continuously until the solid was completely dissolved. Then 20 mL of NaOH solution was added and the reaction temperature was controlled to 85° C. The mixture was kept warm for 3 h to obtain a borate solution. 5 g of the modifier prepared in Example 1 was added and the mixture was kept warm for 4 h with 25 g of paraformaldehyde (solid) under ultrasonic-assisted dispersion. After the reaction was completed, the base resin was cured by heating and pressurizing to obtain a modified phenolic resin.

[0046] Embodiment 4

[0047] Preparation of modified phenolic resin:

[0048] 11 g of boric acid, 60 g of phenol and 200 mL of n-butanol were added to a three-necked flask and stirred continuously until the solid was completely dissolved. Then 20 mL of NaOH solution was added and the reaction temperature was controlled to 95° C. The mixture was kept warm for 4 h to obtain a borate solution. 10 g of the modifier prepared in Example 2 was added and the mixture was kept warm for 6 h with 25 g of paraformaldehyde (solid) under ultrasonic-assisted dispersion. After the reaction was completed, the base resin was cured by heating and pressurizing to obtain a modified phenolic resin.

[0049] Embodiment 5

[0050] Preparation of modified phenolic resin:

[0051] 11 g of boric acid, 60 g of phenol and 200 mL of n-butanol were added to a three-necked flask and stirred continuously until the solid was completely dissolved. Then 20 mL of NaOH solution was added and the reaction temperature was controlled to 95° C. The reaction was kept warm for 4 h to obtain a borate solution. 15 g of the modifier prepared in Example 2 was added and the solution was kept warm for 6 h with 25 g of paraformaldehyde (solid) under ultrasonic-assisted dispersion. After the reaction was completed, the base resin was cured by heating and pressurizing to obtain a modified phenolic resin.

[0052] Embodiment 6

[0053] A1. Put 4 g of aluminum oxide and 40 g of the modified phenolic resin obtained in Example 5 into a mixer and mix for 12 h, then add 30 g of cubic boron nitride powder, 10 g of copper and 2 g of paraffin and stir for 12 h to obtain a mixture;

[0054] A2, the mixture obtained in step A1 and the aluminum grinding wheel matrix are loaded into a mold, pressed at 130° C. and a pressure of 100 MPa for 10 min, then cured at 130° C. and normal pressure for 2 h, and demolded to obtain a pre-cured cubic boron nitride resin grinding wheel;

[0055] A3, placing the pre-cured cubic boron nitride resin grinding wheel obtained in step A2 in a 140° C. oven for re-curing, and performing lathing after curing to obtain a cubic boron nitride resin grinding wheel.

[0056] Embodiment 7

[0057] A1. 8 g of aluminum oxide and 50 g of the modified phenolic resin obtained in Example 5 were placed in a mixer and mixed for 12 h, and then 40 g of cubic boron nitride powder, 20 g of copper and 4 g of epoxy soybean oil were added and stirred for 12 h to obtain a mixture;

[0058] A2, the mixture obtained in step A1 and the aluminum grinding wheel matrix are loaded into a mold, pressed at 170° C. and a pressure of 120 MPa for 20 min, then cured at 170° C. and normal pressure for 3 h, and demolded to obtain a pre-cured cubic boron nitride resin grinding wheel;

[0059] A3, placing the pre-cured cubic boron nitride resin grinding wheel obtained in step A2 in a 180° C. oven for re-curing, and performing lathing after curing to obtain a cubic boron nitride resin grinding wheel.

[0060] Comparative Example 1

[0061] The modifier in Example 5 was replaced by a commercially available heat-resistant agent of the same quality, and the remaining steps were the same as those in Example 5 to obtain a phenolic resin.

[0062] Comparative Example 2

[0063] A commercially available phenolic resin binder was used.

[0064] Comparative Example 3

[0065] A commercially available cubic boron nitride resin grinding wheel was used.

[0066] Embodiments 3, 4, 5, and comparative examples 1 and 2 were made into corresponding shapes according to different test standards, and the following performance tests were performed:

[0067] The notched impact strength is determined using the national standard GB / T 1043.1-2008 "Determination of impact properties of simply supported beams of plastics Part 1: Non-instrumented impact test";

[0068] The flame retardant properties are measured using the national standard GB / T 2408-2008 "Horizontal and vertical methods for the determination of combustion properties of plastics";

[0069] The national standard GB / T 1634-2004 "Plastics - Determination of Deformation Temperature under Load" was used to measure the heat deformation temperature of Examples 3, 4, 5 and Comparative Example 1 before and after being placed at room temperature for 200 days;

[0070] The measured results are shown in Table 1:

[0071] Table 1

[0072]

[0073] The grinding wheels of Examples 6 and 7 and Comparative Example 3 were subjected to grinding tests, and the grinding ratio was calculated; the calculation formula of the grinding ratio is: grinding ratio=(weight of workpiece before grinding-weight of workpiece after grinding) / (weight of grinding wheel before grinding-weight of grinding wheel after grinding).

[0074] The measured results are shown in Table 2:

[0075] Table 2

[0076] Test items Embodiment 6 Embodiment 7 Comparative Example 3 Grinding ratio (g / g) 133.6 134.1 88.9

[0077] It can be seen from Table 1 that the modified phenolic resin prepared in the embodiment of the present invention has excellent mechanical properties, and its flame retardancy and heat resistance are better than those of the comparative example, and after 200 days, it still maintains good performance; it can be seen from Table 2 that the grinding ratio of the embodiment is greater than that of the comparative example, and the grinding performance is good. Therefore, the present invention has important application value in the field of cubic boron nitride grinding wheel technology.

[0078] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0079] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a cubic boron nitride resin grinding wheel, characterized in that: The following steps are involved: A1. Put aluminum oxide and modified phenolic resin into a mixer and mix them, add cubic boron nitride powder, copper and lubricant, stir and mix to obtain a mixture; A2, placing the mixture obtained in step A1 and the aluminum grinding wheel matrix into a mold, pressing and molding under high temperature and high pressure, then heat-curing and demolding under normal pressure to obtain a pre-cured cubic boron nitride resin grinding wheel; A3, placing the pre-cured cubic boron nitride resin grinding wheel obtained in step A2 into an oven for re-curing, and performing turning and grinding after curing to obtain a cubic boron nitride resin grinding wheel.

2. The method for preparing a cubic boron nitride resin grinding wheel according to claim 1, characterized in that: The modified phenolic resin is prepared by the following steps: Add boric acid, phenol and n-butanol into a three-necked flask and keep stirring until the solid is completely dissolved. Then add NaOH solution and control the reaction temperature to 85-95°C. Keep the temperature for reaction for 3-4 hours to obtain a borate solution. Add a modifier and keep the temperature with paraformaldehyde for reaction for 4-6 hours under ultrasonic-assisted dispersion. After the reaction is completed, heat and pressurize to solidify the base resin to obtain a modified phenolic resin.

3. The method for preparing a cubic boron nitride resin grinding wheel according to claim 2, characterized in that: The modifying agent is prepared by the following steps: S1. At room temperature, 3-aminopropanesulfonic acid, NaOH solution and tetrahydrofuran were mixed under nitrogen protection, stirred for 2 h, and then 4-bromo-1-butene was added. The mixture was refluxed at 70°C for 4 h. After the reaction was completed, the mixture was rotary evaporated, purified by column chromatography, and rotary evaporated to obtain intermediate 1. S2. Stir hydrogenated silicone oil, N,N-dimethylformamide and Speier catalyst at room temperature for 60 min, then add intermediate 1 and react at 75°C for 8 h. Stir continuously during the reaction. When the reaction is complete, stop heating, wait for the device to cool to room temperature, stir for 2 h, filter, and rotary evaporate to obtain a modifier.

4. The method for preparing a cubic boron nitride resin grinding wheel according to claim 3, characterized in that: In step S1, the ratio of the amount of 3-aminopropanesulfonic acid, NaOH solution, tetrahydrofuran and 4-bromo-1-butene is 13.9 g:50 mL:100 mL:13.3 g.

5. The method for preparing a cubic boron nitride resin grinding wheel according to claim 3, characterized in that: In step S2, the ratio of the amount of hydrogen-containing silicone oil, N,N-dimethylformamide, Speier catalyst, and intermediate 1 is 10 g: 100 mL: 0.4 mL: 21.6 g.

6. The method for preparing a cubic boron nitride resin grinding wheel according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 4-8 parts of aluminum oxide, 40-50 parts of modified phenolic resin, 30-40 parts of cubic boron nitride powder, 10-20 parts of copper, and 2-4 parts of lubricant.

7. The method for preparing a cubic boron nitride resin grinding wheel according to claim 2, characterized in that: The usage ratio of the boric acid, phenol, n-butanol, NaOH solution, modifier and paraformaldehyde is 11g:60g:200mL:20mL:5-15g:25g.

8. A cubic boron nitride resin grinding wheel, characterized in that: Prepared according to the method according to any one of claims 1 to 7.

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