Honeycomb structure polyurethane elastic grinding wheel and its preparation method

Abstract

This invention discloses a honeycomb-structured polyurethane elastic grinding wheel and its preparation method. The preparation method of the honeycomb-structured polyurethane elastic grinding wheel includes the following steps: (1) mixing isocyanate, polytetrahydrofuran, a first catalyst, and a first solvent to obtain an isocyanate prepolymer; mixing a closed-type isocyanate and the isocyanate prepolymer evenly to obtain material A; (2) dispersing abrasive, a second solvent, and a coupling agent, and then filtering and vacuum drying to obtain modified abrasive; dispersing polyol, a second catalyst, water, a pore-opening agent, an anti-settling agent, and the modified abrasive, and then sand milling to obtain material B; (3) mixing material A and material B evenly and then injecting them into a molding die for foaming and curing to obtain a honeycomb-structured polyurethane elastic grinding wheel. This invention uses isocyanate prepolymer as the main agent and uses a coupling agent to modify the abrasive, which can make the grinding wheel scratch-free when grinding the plate surface, and will not cause clogging of the pores due to agglomeration and shedding.

Description

Technical Field

[0001] This invention belongs to the field of grinding wheel preparation technology, and particularly relates to a honeycomb structure polyurethane elastic grinding wheel and its preparation method. Background Technology

[0002] In the metal or non-metal surface treatment industry, non-woven abrasive wheels are considered a high-end application for PCB surface treatment. However, the circuitry on PCBs is becoming increasingly complex and intricate. During the abrasion process, even slight scratches can lead to short circuits and failure to complete the process. In addition, many PCBs now have drilled holes, resulting in slight depressions around the holes. Ceramic abrasive wheels are too hard to meet the requirements, and nylon abrasive wheels lack sufficient cutting force. Non-woven abrasive wheels, on the other hand, have a certain degree of elasticity and strong cutting force, which can meet the abrasion requirements around the hole edges. However, the fibers in non-woven abrasive wheels are prone to clumping and falling off during the abrasion process, causing blockage of the holes and making subsequent processing difficult.

[0003] Therefore, there is an urgent need for a honeycomb structure polyurethane elastic grinding wheel and its preparation method to address the shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a honeycomb structure polyurethane elastic grinding wheel. The honeycomb structure polyurethane elastic grinding wheel prepared by this method has a grinding plate surface without scratches and without clogging of holes.

[0005] Another objective of this invention is to provide a honeycomb structure polyurethane elastic grinding wheel, which has a grinding plate surface free of scratches and does not clog holes.

[0006] To achieve the above objectives, the present invention provides a method for preparing a honeycomb structure polyurethane elastic grinding wheel, comprising the following steps:

[0007] (1) Preparation of Material A

[0008] Isocyanate, polytetrahydrofuran, a first catalyst, and a first solvent were stirred and mixed to prepare an isocyanate prepolymer.

[0009] Blocked isocyanate and isocyanate prepolymer are mixed evenly to obtain material A.

[0010] (2) Preparation of Material B

[0011] The modified abrasive is prepared by stirring and dispersing the abrasive, the second solvent and the coupling agent, followed by filtration and vacuum drying.

[0012] Polyol, second catalyst, water, pore-opening agent, anti-settling agent, and modified abrasive are stirred and dispersed, and then milled to obtain material B.

[0013] (3) Foaming molding

[0014] After mixing material A and material B evenly, the mixture is injected into a molding die for foaming and molding, and then cured to obtain a honeycomb structure polyurethane elastic grinding wheel.

[0015] Compared with existing technologies, this invention uses a high molecular weight, high strength, and good adhesive elasticity isocyanate prepolymer as the main agent. During foaming, it produces uniform pores, and after molding and curing, it forms a honeycomb structure to uniformly adhere the abrasive to the resin system. This results in a honeycomb structure polyurethane elastic grinding wheel with a uniform roughness, preventing scratches on the board surface. Simultaneously, a coupling agent is used to modify the abrasive. The coupling agent reacts with the resin, essentially pulling individual abrasive particles away from the resin, further ensuring uniform adhesion of the abrasive to the resin system. This prevents abrasive aggregation and scratches on the board surface. Therefore, using an isocyanate prepolymer as the main agent and a coupling agent to modify the abrasive results in a scratch-free polyurethane elastic grinding wheel when grinding the board surface, and also prevents agglomeration and pore blockage.

[0016] Preferably, in this invention, step (1) comprises, by weight, stirring 5-20 parts of isocyanate, 5-10 parts of polytetrahydrofuran, 0.01-0.1 parts of a first catalyst, and 2-10 parts of a first solvent at room temperature for 1-3 hours to obtain an isocyanate prepolymer; and comprising mixing the blocked isocyanate and the isocyanate prepolymer at a weight ratio of 1:1-2 to obtain material A. Specifically, the first solvent is ethyl acetate; the polytetrahydrofuran has an average molecular weight of 500-1000.

[0017] Preferably, the molar ratio of isocyanate to polytetrahydrofuran in this invention is 2-4:1, resulting in a large molecular weight of the isocyanate prepolymer, a higher initial molecular weight during foaming, and good adhesive elasticity. This is beneficial for the formation of honeycomb cells and the bearing capacity of abrasives. The resulting isocyanate prepolymer has a solid content of 70-80% and a viscosity of <10000 mPa*s at 25°C after the reaction. More preferably, the molar ratio of isocyanate to polytetrahydrofuran in this invention is 2-2.5:1.

[0018] Preferably, in this invention, step (2) includes, by weight, stirring and dispersing 100 parts of abrasive, 30-50 parts of a second solvent, and 1-3 parts of coupling agent for 3-4 hours, removing the second solvent by negative pressure filtration to obtain a filter cake, and vacuum drying the filter cake at 90-110°C for 2-8 hours to obtain modified abrasive; and includes stirring and dispersing 10-30 parts of polyol, 0.01-0.1 parts of a second catalyst, 0.1-1 parts of water, 0.5-2 parts of pore-opening agent, 0.5-2 parts of anti-settling agent, and 20-60 parts of modified abrasive, and then grinding them in a sand mill to obtain material B. Specifically, dispersion can be carried out in a dispersion mixer. Specifically, the second solvent is anhydrous ethanol. More specifically, the grinding balls configured in the sand mill are made of alumina or zirconium oxide, and the particle size of the grinding balls is adjusted according to the particle size of the abrasive, such as 3-4 mm grinding balls for 600# silicon carbide. This invention can ensure the cutting force of a honeycomb-structured polyurethane elastic grinding wheel during grinding by adjusting the content of the modified abrasive.

[0019] Preferably, step (3) of the present invention includes mixing material A and material B at a weight ratio of 0.5 to 1.3:1 and injecting the mixture into a molding mold, foaming and molding at room temperature to obtain a semi-finished product, and then placing the semi-finished product in an oven at 120 to 150°C for 2 to 4 hours to cure.

[0020] Preferably, the abrasive of the present invention is selected from at least one of silicon carbide, alumina, silicon dioxide, boron nitride, hollow silicon dioxide, and hollow alumina. Specifically, the particle size of the abrasive is 1 to 120 μm.

[0021] Preferably, the blocked isocyanate of the present invention is selected from at least one of toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI) with a viscosity of less than 5000 mPa*s at 25°C. Specifically, the blocked isocyanate has a solid content of 60-80% and a deblocking temperature of 120-140°C; the isocyanate is selected from at least one of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and isophorone diisocyanate (IPDI). The combination of the blocked isocyanate in this invention further enhances the strength of the polyurethane elastic grinding wheel, thereby further ensuring the cutting force during grinding with the honeycomb structure polyurethane elastic grinding wheel.

[0022] Preferably, the coupling agent of the present invention is selected from at least one of organochromium complexes, silanes, and titanates. Specifically, the organochromium complex coupling agent is a metallic chromium complex formed by an unsaturated organic acid and trivalent chromium ions. Specifically, the silane coupling agent may be, but is not limited to, KH550, KH560, KH570, KH792, and KH602. Specifically, the titanate coupling agent may be, but is not limited to, monoalkoxy titanates, monoalkoxy pyrophosphate type coupling agents, chelating titanate coupling agents, and ligand type titanate coupling agents. Preferably, the coupling agent of the present invention is a silane coupling agent.

[0023] Preferably, the first catalyst of the present invention is selected from organometallic catalysts. The second catalyst is selected from a mixture of organometallic catalysts and amine catalysts, wherein the organometallic catalyst catalyzes the gelation rate of polyurethane, while the amine catalyst catalyzes the foaming rate of polyurethane. Therefore, selecting a mixture of organometallic catalysts and amine catalysts as the second catalyst is more conducive to the formation of a honeycomb structure by the polyurethane elastic grinding wheel. Specifically, the organometallic catalyst may be, but is not limited to, an organobismuth catalyst or an organotin catalyst; the amine catalyst may be, but is not limited to, triethylenediamine, pentamethyldiethylenetriamine, or N,N-dimethylcyclohexylamine.

[0024] Preferably, the polyol of the present invention is selected from at least one of polyether polyols and polyester polyols with a viscosity of less than 1000 mPa*s at 25°C. If the grinding wheel is used in a wet environment, selecting a polyether polyol with a viscosity of less than 1000 mPa*s at 25°C can achieve better water resistance. Specifically, the polyether polyol may be, but is not limited to, polyether polyol PEG-1000, polyether polyol PPG-1000, and polyether polyol PEG-500.

[0025] Preferably, the pore-opening agent of the present invention is at least one selected from polypropylene oxide-ethylene oxide copolyether and polyolefin oxide-polysiloxane copolymer. More specifically, the pore-opening agent of the present invention is at least one selected from Y-1900, allchem-3365, and GS-28.

[0026] Preferably, the anti-settling agent of the present invention is a modified polyamide wax-based anti-settling agent with a particle size D50 < 30 μm.

[0027] To achieve the above objectives, the present invention also provides a honeycomb structure polyurethane elastic grinding wheel, which is prepared by the above-described method for preparing a honeycomb structure polyurethane elastic grinding wheel.

[0028] Compared with the prior art, the honeycomb structure polyurethane elastic grinding wheel of the present invention has a uniform surface roughness. When grinding the plate surface with this polyurethane elastic grinding wheel, there are no scratches and it will not clump together and fall off, causing blockage of the holes. Attached Figure Description

[0029] Figure 1 This is a 500x metallographic micrograph of the honeycomb structure polyurethane elastic grinding wheel prepared in Example 1. Detailed Implementation

[0030] To further understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0032] Example 1

[0033] This embodiment provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0034] (1) Preparation of Material A

[0035] The isocyanate prepolymer was prepared by mixing 10 parts by weight of isocyanate MDI, 10 parts by weight of polytetrahydrofuran, 0.02 parts by weight of organotin catalyst and 5 parts by weight of ethyl acetate in a reactor at room temperature for 2 hours. The polytetrahydrofuran had an average molecular weight of 500 and the molar ratio of isocyanate to polytetrahydrofuran was 2:1.

[0036] Blocked isocyanate TDI 3368 and isocyanate prepolymer were mixed evenly at a weight ratio of 1:2 to obtain material A.

[0037] (2) Preparation of Material B

[0038] 100 parts by weight of 600# silicon carbide, 40 parts by weight of anhydrous ethanol and 1.5 parts by weight of KH560 were stirred and dispersed in a dispersant for 4 hours. The anhydrous ethanol was removed by negative pressure filtration to obtain a filter cake. The filter cake was placed in a vacuum drying oven at 100°C and vacuum dried for 4 hours to obtain the modified abrasive.

[0039] 20 parts by weight of polyether polyol PEG-1000, 0.02 parts by weight of organic bismuth catalyst, 0.02 parts by weight of triethylenediamine, 0.03 parts by weight of water, 0.7 parts by weight of GS-28, 0.5 parts by weight of polyamide wax MT-PLUS, and 30 parts by weight of modified abrasive were stirred and dispersed for 5 hours, and then milled in a grinding mill to obtain material B.

[0040] (3) Foaming molding

[0041] After mixing material A and material B at a weight ratio of 1:1, the mixture is injected into a molding mold and foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 4 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0042] The grinding wheel prepared in Example 1 was observed using a metallurgical microscope at 500x magnification. The observation results are as follows: Figure 1 As shown, Figure 1 The grinding wheel prepared in Example 1 has a honeycomb structure.

[0043] Example 2

[0044] This embodiment provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0045] (1) Preparation of Material A

[0046] The isocyanate prepolymer was prepared by mixing 10 parts by weight of isocyanate MDI, 10 parts by weight of polytetrahydrofuran, 0.02 parts by weight of organotin catalyst and 5 parts by weight of ethyl acetate in a reactor at room temperature for 2 hours. The polytetrahydrofuran had an average molecular weight of 500 and the molar ratio of isocyanate to polytetrahydrofuran was 2:1.

[0047] Blocked isocyanate TDI 3368 and isocyanate prepolymer were mixed evenly at a weight ratio of 1:1 to obtain material A.

[0048] (2) Preparation of Material B

[0049] 100 parts by weight of 600# silicon carbide, 40 parts by weight of anhydrous ethanol and 2 parts by weight of KH550 were stirred and dispersed in a dispersant for 3 hours. The anhydrous ethanol was removed by negative pressure filtration to obtain a filter cake. The filter cake was placed in a vacuum drying oven at 100°C and vacuum dried for 4 hours to obtain the modified abrasive.

[0050] 25 parts by weight of polyether polyol PPG-1000, 0.02 parts by weight of organic bismuth catalyst, 0.02 parts by weight of triethylenediamine, 0.03 parts by weight of water, 0.8 parts by weight of GS-28, 0.6 parts by weight of polyamide wax MT-PLUS, and 40 parts by weight of modified abrasive were stirred and dispersed for 5 hours, and then milled in a grinding mill to obtain material B.

[0051] (3) Foaming molding

[0052] Material A and material B are mixed evenly at a weight ratio of 0.8:1 and then injected into a molding die. The mixture is foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 4 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0053] Example 3

[0054] This embodiment provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0055] (1) Preparation of Material A

[0056] An isocyanate prepolymer was prepared by mixing 8 parts by weight of 2,4-TDI isocyanate, 10 parts by weight of polytetrahydrofuran, 0.02 parts by weight of organotin catalyst and 5 parts by weight of ethyl acetate in a reactor at room temperature for 2 hours. The polytetrahydrofuran had an average molecular weight of 500 and the molar ratio of isocyanate to polytetrahydrofuran was 2.3:1.

[0057] Blocked isocyanate HDIDXB-3375 and isocyanate prepolymer were mixed evenly at a weight ratio of 1:2 to obtain material A.

[0058] (2) Preparation of Material B

[0059] 100 parts by weight of 600# silicon carbide, 40 parts by weight of anhydrous ethanol and 1.5 parts by weight of KH560 were stirred and dispersed in a dispersant for 4 hours. The anhydrous ethanol was removed by negative pressure filtration to obtain a filter cake. The filter cake was placed in a vacuum drying oven at 100°C and vacuum dried for 4 hours to obtain the modified abrasive.

[0060] 15 parts by weight of polyether polyol PEG-500, 0.04 parts by weight of organotin catalyst, 0.02 parts by weight of triethylenediamine, 0.02 parts by weight of water, 0.6 parts by weight of GS-28, 0.8 parts by weight of polyamide wax MT-PLUS, and 20 parts by weight of modified abrasive were stirred and dispersed for 5 hours, and then milled in a grinding mill to obtain material B.

[0061] (3) Foaming molding

[0062] Material A and material B are mixed evenly at a weight ratio of 1.1:1 and then injected into a molding die. The mixture is foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 2 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0063] Example 4

[0064] This embodiment provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0065] (1) Preparation of Material A

[0066] The isocyanate prepolymer was prepared by mixing 10 parts by weight of isocyanate MDI, 10 parts by weight of polytetrahydrofuran, 0.02 parts by weight of organotin catalyst and 5 parts by weight of ethyl acetate in a reactor at room temperature for 2 hours. The polytetrahydrofuran had an average molecular weight of 500 and the molar ratio of isocyanate to polytetrahydrofuran was 2:1.

[0067] Blocked isocyanate IPDI 330 and isocyanate prepolymer were mixed evenly at a weight ratio of 1:2 to obtain material A.

[0068] (2) Preparation of Material B

[0069] 100 parts by weight of 600# silicon carbide, 40 parts by weight of anhydrous ethanol and 2 parts by weight of KH550 were stirred and dispersed in a dispersant for 3 hours. The anhydrous ethanol was removed by negative pressure filtration to obtain a filter cake. The filter cake was placed in a vacuum drying oven at 100°C and vacuum dried for 4 hours to obtain the modified abrasive.

[0070] 30 parts by weight of polyether polyol PPG-1000, 0.02 parts by weight of organotin catalyst, 0.02 parts by weight of triethylenediamine, 0.01 parts by weight of water, 0.7 parts by weight of GS-28, 0.5 parts by weight of polyamide wax MT-PLUS, and 50 parts by weight of modified abrasive were stirred and dispersed for 6 hours, and then milled in a grinding mill to obtain material B.

[0071] (3) Foaming molding

[0072] Material A and material B are mixed evenly at a weight ratio of 0.7:1 and then injected into a molding die. The mixture is foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 4 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0075] (1) Preparation of Material A

[0076] The isocyanate prepolymer was prepared by mixing 10 parts by weight of isocyanate MDI, 10 parts by weight of polytetrahydrofuran, 0.02 parts by weight of organotin catalyst and 5 parts by weight of ethyl acetate in a reactor at room temperature for 2 hours. The polytetrahydrofuran had an average molecular weight of 500 and the molar ratio of isocyanate to polytetrahydrofuran was 2:1.

[0077] Blocked isocyanate TDI 3368 and isocyanate prepolymer were mixed evenly at a weight ratio of 1:2 to obtain material A.

[0078] (2) Preparation of Material B

[0079] 20 parts by weight of polyether polyol PEG-1000, 0.02 parts by weight of organic bismuth catalyst, 0.02 parts by weight of triethylenediamine, 0.03 parts by weight of water, 0.7 parts by weight of GS-28, 0.5 parts by weight of polyamide wax MT-PLUS, and 30 parts by weight of 600# silicon carbide were stirred and dispersed for 5 hours, and then milled to obtain material B.

[0080] (3) Foaming molding

[0081] After mixing material A and material B at a weight ratio of 1:1, the mixture is injected into a molding mold and foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 4 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0084] (1) Preparation of Material A

[0085] Blocked isocyanate TDI 3368 and isocyanate MDI were mixed evenly at a weight ratio of 1:2 to obtain material A.

[0086] (2) Preparation of Material B

[0087] 100 parts by weight of 600# silicon carbide, 40 parts by weight of anhydrous ethanol and 1.5 parts by weight of KH560 were stirred and dispersed in a dispersant for 4 hours. The anhydrous ethanol was removed by negative pressure filtration to obtain a filter cake. The filter cake was placed in a vacuum drying oven at 100°C and vacuum dried for 4 hours to obtain the modified abrasive.

[0088] 20 parts by weight of polyether polyol PEG-1000, 0.02 parts by weight of organic bismuth catalyst, 0.02 parts by weight of triethylenediamine, 0.03 parts by weight of water, 0.7 parts by weight of GS-28, 0.5 parts by weight of polyamide wax MT-PLUS, and 30 parts by weight of modified abrasive were stirred and dispersed for 5 hours, and then milled in a grinding mill to obtain material B.

[0089] (3) Foaming molding

[0090] After mixing material A and material B at a weight ratio of 1:1, the mixture is injected into a molding mold and foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 4 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0091] Comparative Example 3

[0092] This comparative example provides a method for preparing a honeycomb structured polyurethane elastic grinding wheel, the steps of which include:

[0093] (1) Preparation of Material A

[0094] Blocked isocyanate TDI 3368 and isocyanate MDI were mixed evenly at a weight ratio of 1:2 to obtain material A.

[0095] (2) Preparation of Material B

[0096] 20 parts by weight of polyether polyol PEG-1000, 0.02 parts by weight of organic bismuth catalyst, 0.02 parts by weight of triethylenediamine, 0.03 parts by weight of water, 0.7 parts by weight of GS-28, 0.5 parts by weight of polyamide wax MT-PLUS, and 30 parts by weight of 600# silicon carbide were stirred and dispersed for 5 hours, and then milled to obtain material B.

[0097] (3) Foaming molding

[0098] After mixing material A and material B at a weight ratio of 1:1, the mixture is injected into a molding mold and foamed at room temperature to obtain a semi-finished product. The semi-finished product is then placed in a 140℃ electric heating oven for 4 hours to cure, resulting in a honeycomb structure polyurethane elastic grinding wheel.

[0099] Comparative Example 4

[0100] This comparative example provides a method for preparing a non-woven abrasive wheel, the steps of which include:

[0101] (1) Non-woven fabric containing 600# silicon carbide is wound onto bakelite tube through a fabric pressing machine to obtain a non-woven fabric semi-finished product;

[0102] (2) By weight, 20 parts of liquid epoxy E51, 5 parts of 4,4'-diaminodiphenylmethane MDA-100 and 55 parts of propylene glycol methyl ether acetate are stirred evenly in a disperser to obtain the impregnation adhesive.

[0103] (3) Immerse the non-woven fabric semi-finished product into the impregnation glue, then spin dry and place it in a 150℃ electric heating blast oven to cure for 4 hours to obtain a non-woven fabric grinding wheel.

[0104] The grinding wheels prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests, and the test results are shown in Table 1. The test items and instruments are as follows:

[0105] Foaming ratio: measuring cup.

[0106] Density: Calculated based on mass and volume.

[0107] Hardness: Shore hardness C needle.

[0108] Roughness: Mitutoyo roughness tester.

[0109] Cutting force, board surface effect, and hole filling effect: single brush grinding machine, drilling copper clad board 400*200mm, test current 1.5A, line speed 2.5m / min.

[0110] Table 1. Performance test results of grinding wheels

[0111]

[0112] Table 1 shows that the grinding wheels of all embodiments produced no scratches or clogging of the grinding plate surface. This indicates that the present invention uses a high molecular weight, high strength, and good adhesive elasticity isocyanate prepolymer as the main agent. During foaming, it has uniform pores, and after molding and curing, it can form a honeycomb structure to uniformly attach the abrasive to the resin system. This results in a honeycomb structure polyurethane elastic grinding wheel with uniform roughness, preventing scratches on the plate surface. Simultaneously, a coupling agent is used to modify the abrasive. By attaching the coupling agent to the abrasive surface, the coupling agent reacts with the resin, effectively pulling the abrasive particles away from the resin. This allows the abrasive to adhere evenly to the resin system, preventing agglomeration and thus avoiding scratches on the plate surface. Therefore, using an isocyanate prepolymer as the main agent and a coupling agent to modify the abrasive results in a scratch-free grinding wheel on the plate surface, and also prevents agglomeration and clogging of the pores.

[0113] Comparing Examples 1 and 3-4, it can be seen that Examples 1 and 3 have a moderate abrasive content and moderate cutting force, while Examples 2 and 4 have a high abrasive content and are high-cutting brushes. This shows that the abrasive content in the grinding wheel can be adjusted by adjusting the content of the modified abrasive, thereby allowing the polyurethane elastic grinding wheel to be applied to different occasions. For example, the polyurethane elastic grinding wheel of Example 3 has low hardness, good elasticity, and low abrasive content, and can be used for polishing the surface of PCB boards with circuits without damaging the circuits. Example 4 has a high abrasive content and can be used for grinding the resin protrusions of the plugging resin.

[0114] Comparing Example 1 and Comparative Example 1, it can be seen that the surface of Comparative Example 1 has scratches. This is because the abrasive has not been modified and will agglomerate, which will occasionally cause scratches during grinding, resulting in scratches on the surface.

[0115] Comparing Example 1 and Comparative Example 2, it can be seen that the surface of Comparative Example 2 has local scratches. This is because the isocyanate was not prepolymerized, the initial molecular weight was low, the adhesive elasticity was poor, the bubbles were easy to grow infinitely large, the overall density and hardness were different, a honeycomb structure was not formed, the abrasive was not evenly attached in the system, the surface effect was poor, the roughness was uneven, and local scratches appeared.

[0116] Comparing Example 1 and Comparative Example 3, it can be seen that the surface of Comparative Example 3 has obvious scratches. The grinding wheel of Comparative Example 3 uses polyurethane as the main bonding structure. After adding abrasive, the overall glue foaming requires greater resistance and the bubbles are easily broken, resulting in uneven pore size and failure to form a honeycomb structure. At the same time, the abrasive is not modified and will agglomerate. Therefore, Comparative Example 3 cannot guarantee the surface effect.

[0117] Comparing Example 1 and Comparative Example 4, it can be seen that the preparation method of the non-woven abrasive wheel in Comparative Example 4 cannot guarantee the uniform dispersion of abrasive. Therefore, the non-woven abrasive wheel is prone to scratches and clogging during grinding.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a honeycomb structure polyurethane elastic grinding wheel, characterized in that the steps include... include: (1) Preparation of material A Isocyanate prepolymer is prepared by stirring and mixing isocyanate, polytetrahydrofuran, a first catalyst and a first solvent, wherein the molar ratio of isocyanate to polytetrahydrofuran is 2 to 4:1 and the average molecular weight of polytetrahydrofuran is 500 to 1000. The blocked isocyanate and the isocyanate prepolymer are mixed evenly to obtain material A. (2) Preparation of material B The modified abrasive is prepared by stirring and dispersing the abrasive, the second solvent and the coupling agent, followed by filtration and vacuum drying. The polyol, second catalyst, water, pore-opening agent, anti-settling agent, and the modified abrasive were stirred and dispersed, and then milled to obtain material B. (3) Foaming molding After the A material and the B material are mixed evenly, the mixture is injected into a molding die for foaming and molding, and then cured to obtain a honeycomb structure polyurethane elastic grinding wheel.

2. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, By weight, step (1) includes stirring 5-20 parts of the isocyanate, 5-10 parts of the polytetrahydrofuran, 0.01-0.1 parts of the first catalyst and 2-10 parts of the first solvent at room temperature for 1-3 hours to obtain the isocyanate prepolymer; and includes mixing the blocked isocyanate and the isocyanate prepolymer at a weight ratio of 1:1-2 to obtain material A.

3. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, By weight, step (2) includes stirring and dispersing 100 parts of the abrasive, 30-50 parts of the second solvent and 1-3 parts of the coupling agent for 3-4 hours, removing the second solvent by negative pressure filtration to obtain a filter cake, and vacuum drying the filter cake at 90-110°C for 2-8 hours to obtain the modified abrasive; and includes stirring and dispersing 10-30 parts of the polyol, 0.01-0.1 parts of the second catalyst, 0.1-1 parts of the water, 0.5-2 parts of the pore-opening agent, 0.5-2 parts of the anti-settling agent and 20-60 parts of the modified abrasive, and then grinding them in a sand mill to obtain material B.

4. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, Step (3) includes mixing material A and material B at a weight ratio of 0.5~1.3:1 and injecting the mixture into a molding mold, foaming and molding at room temperature to obtain a semi-finished product, and then placing the semi-finished product in an oven at 120~150℃ for 2~4 hours to cure.

5. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, The abrasive is selected from at least one of silicon carbide, alumina, silicon dioxide, boron nitride, hollow silicon dioxide, and hollow alumina.

6. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, The blocked isocyanate is selected from at least one of TDI, HDI and IPDI with a viscosity of less than 5000 mPa*s at 25°C; the isocyanate is selected from at least one of MDI, TDI and IPDI.

7. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, The coupling agent is selected from at least one of organochromium complexes, silanes, and titanates.

8. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, The first catalyst is selected from organometallic catalysts, and the second catalyst is selected from a mixture of organometallic catalysts and amine catalysts.

9. The method for preparing the honeycomb structure polyurethane elastic grinding wheel as described in claim 1, characterized in that, The polyol is selected from at least one of polyether polyols and polyester polyols with a viscosity of less than 1000 mPa*s at 25°C.

10. A honeycomb structure polyurethane elastic grinding wheel, characterized in that, It is prepared by the method of preparing a honeycomb structure polyurethane elastic grinding wheel as described in any one of claims 1 to 9.

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