Precise polishing grinding wheel and preparation method thereof

Abstract

The invention relates to the technical field of grinding wheel manufacturing, in particular to a precise polishing grinding wheel and a preparation method thereof. The grinding material layer comprises the following raw materials in parts by weight: 45-55 parts of diamond, 13-18 parts of modified epoxy natural rubber, 3-5 parts of a vulcanizing agent, 4-5 parts of a vulcanization accelerator and 20-30 parts of modified polyurethane. The grinding wheel manufactured by the invention is high in polishing efficiency, low in loss and long in service life, and a polished substance is not damaged.

Description

Technical Field

[0001] The invention relates to the technical field of grinding wheel manufacturing, and in particular to a precision polishing grinding wheel and a preparation method thereof. Background Art

[0002] With the improvement of people's economic level, silicon carbide, sapphire, precision ceramics and other materials are used more and more in various fields. Therefore, the thinning and polishing of such materials have become particularly important. In the field of precision material polishing, ultrafine silicon carbide abrasive polishing wheels are mostly used, and cerium oxide powder is used in combination with polishing discs or free abrasives for polishing. However, this polishing method has relatively low polishing efficiency, relatively short service life, and gradually declining polishing quality. In addition, cerium oxide abrasive polishing discs require cerium oxide, which is expensive and has high costs. Moreover, free micro-powder diamond solution needs to be used during polishing, and the diamond utilization rate is low, resulting in serious pollution.

[0003] Patent CN105397651B discloses a cast micro-powder diamond grinding wheel for gemstone polishing, including a grinding wheel base, an abrasive layer composed of abrasives and a binder, wherein the abrasive layer contains micro-powder diamond, silicon carbide micro-powder, unsaturated polyester resin liquid, curing agent, defoaming agent, and filler. During processing, it is only necessary to mix and heat the abrasive layer materials to make a mixed liquid, heat the base and the mold to 85-95°C, quickly and evenly cast the mixed liquid into the mold cavity, and keep it warm for 1-2 hours to obtain the finished grinding wheel. The grinding wheel prepared by this invention has uniform pore distribution and a dense overall structure of the abrasive layer, but the polishing efficiency of this type of grinding wheel is low.

[0004] Patent CN105058249B discloses a resin-rubber composite bond grinding wheel for polishing ceramic materials, including a grinding wheel base and an abrasive layer bonded to the outside of the base, wherein the composite bond in the abrasive layer is composed of polyvinyl butyral resin, natural rubber, a vulcanizing agent, a vulcanization accelerator and a vulcanization activator; the grinding wheel produced by this invention can meet the high-precision and high-surface quality processing requirements of precision ceramic materials, but natural rubber has poor oxygen resistance and is prone to aging and deterioration, so the grinding wheel produced has a short service life and poor performance.

[0005] Therefore, there is an urgent need for a precision polishing grinding wheel with high polishing efficiency and long service life in the market. Summary of the invention

[0006] In view of the problems existing in the prior art, the object of the present invention is to obtain a precision polishing grinding wheel which has high polishing efficiency, does not damage the polished material and has a long service life.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a precision polishing grinding wheel, comprising a grinding wheel base, an abrasive layer and a bonding adhesive between the grinding wheel base and the abrasive layer, wherein the abrasive layer comprises the following raw materials in parts by weight: 45-55 parts of diamond, 13-18 parts of modified epoxy natural rubber, 3-5 parts of vulcanizing agent, 4-5 parts of vulcanization accelerator and 20-30 parts of modified polyurethane.

[0009] In some embodiments, the method for preparing the modified epoxidized natural rubber comprises the following steps:

[0010] (1) adding methyl gallate, epichlorohydrin and benzyltriethylammonium chloride into a reaction vessel and reacting at 75-85° C. for 4-5 hours to obtain substance A;

[0011] (2) adding substance A obtained in step (1) and a catalyst to N,N-dimethylformamide, heating to 105-115° C., adding epoxidized natural rubber, stirring to react for 2-3 hours, extracting, combining the organic layers, washing, and drying to obtain substance B;

[0012] (3) Add the substance B obtained in step (2) into chloroform and heat it to 45-55° C., add sodium hydroxide, react for 1-2 hours, wash and dry to obtain modified epoxy natural rubber.

[0013] Natural rubber has relatively low plasticity, poor wear resistance and is easy to age. In actual use, natural rubber needs to be processed and treated to improve its performance and expand its application range. Therefore, people in this field modify natural rubber and graft epoxy groups on some double bonds of its molecular chain to obtain epoxy natural rubber. Not only does it maintain the excellent elasticity of natural rubber, but the introduction of epoxy groups increases the molecular polarity and improves the compatibility between rubber and other substances. However, it still has the disadvantages of unstable performance and poor aging resistance.

[0014] The invention firstly reacts epichlorohydrin ring opening with hydroxyl groups of methyl gallate, and then reacts the obtained substance A with epoxidized natural rubber, and then epoxidizes the substance to obtain modified epoxy natural rubber with epoxy groups on the side chains, which has excellent anti-aging property. On the one hand, the phenolic hydroxyl groups of methyl gallate have anti-oxidation property, so the anti-aging property is improved. In addition, the substance A reacts with the epoxidized natural rubber, so that part of the double bonds of the epoxy natural rubber are consumed, and the disadvantage of the epoxy natural rubber being not resistant to aging is further improved. On the other hand, the presence of benzene rings and epoxy groups of the modified epoxy natural rubber with epoxy groups on the side chains enhances its hydrophobicity, so that the rubber is prevented from absorbing moisture and becoming sticky due to heat generated by friction in hot weather, thereby shortening the service life of the grinding wheel and affecting the polishing effect. In addition, the main chain and the side chains all have epoxy groups, which is conducive to forming a network cross-linked structure. The hydroxyl groups of methyl gallate can react with the isocyanate groups of polyurethane, cross-entangle, and can be tightly wrapped with diamonds, so that scratches are not easily caused during high-speed polishing.

[0015] In some embodiments, the mass ratio of the gallic acid ester to epichlorohydrin is 1:(0.5-0.6).

[0016] The invention limits the mass ratio of gallic acid ester and epichlorohydrin, so that part of the hydroxyl groups of gallic acid ester reacts with epichlorohydrin, without affecting the anti-aging property of gallic acid ester.

[0017] In some embodiments, the mass ratio of substance A to epoxidized natural rubber in step (2) is (1-2):1.

[0018] The present invention limits the mass ratio of substance A to epoxidized natural rubber so that double bonds of the epoxidized natural rubber react with the substance A, while retaining part of the double bonds to participate in vulcanization to form a cross-linked network structure.

[0019] In some embodiments, the preparation method of the modified polyurethane comprises the following steps: adding polycaprolactone diol, isophorone diisocyanate, and a catalyst into a reaction container, stirring for 2-3 hours at 75-85°C under nitrogen protection, cooling to room temperature, adding DMF, stirring evenly, adding 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol and carboxymethyl chitosan, reacting at 50-60°C for 0.5-2 hours, and drying to obtain a modified polyurethane.

[0020] Polyurethane has good tensile strength and tear resistance, and can maintain excellent performance even under low temperature conditions. The grinding wheel prepared by the modified polyurethane and the modified epoxy natural rubber has certain hardness and elasticity, can polish the surface of the grinded material, and leaves few scratches. On the one hand, it may be because the chain extender contains a large amount of fluorine elements, which increases its stability. On the other hand, it may be because the surface of the carboxymethyl chitosan has a large amount of amino groups and hydroxyl groups, which is conducive to the formation of a cross-linked structure of the polyurethane, and further enhances its toughness. In addition, the fluorine element, the amino group and the carboxyl group of the carboxymethyl chitosan form hydrogen bonds with the hydroxyl group of the modified natural rubber, which improves the elasticity of the grinding wheel. It may be because the friction of the grinding wheel generates heat during polishing, and some hydrogen bonds are broken, and the abrasive grains worn off the surface of the grinded material are compressed into the abrasive layer, which reduces the scratches on the surface of the grinded workpiece. When the grinding wheel cools, the hydrogen bonds are re-formed, and the grinding wheel recovers its hardness, and still has a high sharpness, meeting the polishing requirements.

[0021] In some embodiments, the mass ratio of the polycaprolactone diol to isophorone diisocyanate is (2-4):1.

[0022] The invention limits the mass ratio of polycaprolactone diol to isophorone diisocyanate so that the polyurethane has higher hardness and retains part of isocyanate groups to react with modified natural rubber.

[0023] In some embodiments, the mass ratio of the 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol to carboxymethyl chitosan is (1-2):1.

[0024] The invention limits the mass ratio of 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol to carboxymethyl chitosan, which can enhance the stability of polyurethane on the one hand, and compensate for the defect that more isophorone diisocyanate is added to improve the hardness of polyurethane, resulting in reduced flexibility of polyurethane on the other hand.

[0025] In some embodiments, the vulcanizing agent is a combination of sulfur and zinc oxide, and the mass ratio of the two is 1:(1-3).

[0026] In some embodiments, the vulcanization accelerator is any one or more of DM, CZ, MZ, and DPG.

[0027] Another aspect of the present invention provides a method for preparing a precision polishing grinding wheel, comprising the following steps:

[0028] S1. Grind the modified epoxy natural rubber and modified polyurethane into particles with a diameter of 55-65 μm and add them into a mixer, then add diamond, vulcanizing agent and vulcanization accelerator, heat to 120-130° C. and stir for 55-65 min to obtain a mixture;

[0029] S2, adding the mixture obtained in step S1 into a mold, pressing it into a ring shape on a hot press to obtain an abrasive layer, and the specific pressing process is: the temperature of the first stage is 78-83°C, the pressure is 0.9-1.1MPa, and the pressing time is 50-70s; the temperature of the second stage is 98-103°C, the pressure is 2.8-3.2MPa, and the pressing time is 110-140s; the temperature of the third stage is 118-123°C, the pressure is 4.8-5.2MPa, and the pressing time is 110-130s; the temperature of the fourth stage is 123-128°C, the pressure is 5.8-6.2MPa, and the pressing time is 13-17min;

[0030] S3, the abrasive layer obtained in step S2 is bonded to the grinding wheel base with an adhesive to obtain a precision polishing grinding wheel.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The grinding wheel prepared by the modified polyurethane and the modified epoxy natural rubber has a certain hardness and elasticity, can polish the surface of the ground material, and leaves few scratches, and has a long service life.

[0033] (2) The present invention firstly reacts the hydroxyl group of methyl gallate with the ring-opening of epichlorohydrin, and the obtained substance A reacts with the epoxidized natural rubber, which is then epoxidized to obtain a modified epoxidized natural rubber having epoxy groups on the side chains, which has excellent anti-aging properties. In addition, the main chain and the side chains all have epoxy groups, which is conducive to forming a network cross-linked structure. The hydroxyl group of methyl gallate can react with the isocyanate group of polyurethane to cross-entangle and can be tightly wrapped with the diamond, and is not easy to cause scratches during high-speed polishing.

[0034] (3) The present invention further modifies the polyurethane to improve its stability and toughness. The fluorine element, the amino group and the carboxyl group of the carboxymethyl chitosan form hydrogen bonds with the hydroxyl group of the modified natural rubber, thereby improving the elasticity of the grinding wheel. During polishing, the grinding wheel generates heat due to friction, and some hydrogen bonds are broken. The abrasive particles worn off the surface of the grinded material are compressed into the abrasive layer, thereby reducing scratches on the surface of the grinded workpiece. When the grinding wheel cools down, the hydrogen bonds are reformed, and the grinding wheel recovers its hardness and still has a high sharpness, meeting the requirements of polishing. DETAILED DESCRIPTION

[0035] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0036] In the following examples and comparative examples, the compounds and related reagents used can be purchased from the market, among which diamond was purchased from Henan Hengwei Superhard Materials Co., Ltd. with a particle size of W1.5; epoxidized natural rubber was purchased from Dongguan Donglin Polymer Materials Co., Ltd. with a model of ENR75; polycaprolactone diol was purchased from Shandong Hui'an Chemical Co., Ltd. with a number average molecular weight of 3000.

[0037] Preparation Example 1

[0038] The preparation method of modified epoxy natural rubber-1 comprises the following steps:

[0039] (1) Add 10 g of methyl gallate, 5.5 g of epichlorohydrin, and 0.07 g of benzyltriethylammonium chloride into a reaction vessel and react at 80° C. for 4.5 h to obtain substance A;

[0040] (2) 1.5 g of substance A obtained in step (1) and 0.01 g of methanesulfonic acid were added to 30 ml of N,N-dimethylformamide, and after the temperature was raised to 110° C., 1 g of epoxidized natural rubber was added, and the mixture was stirred for 2.5 h, extracted, and the organic layers were combined, washed, and dried to obtain substance B;

[0041] (3) Add 1 g of substance B obtained in step (2) to 20 ml of chloroform and heat to 50° C., add 2 g of sodium hydroxide, react for 1.5 h, wash until pH = 7, and dry to obtain modified epoxy natural rubber-1.

[0042] Preparation Example 2

[0043] The preparation method of modified epoxy natural rubber-2 is the same as that of Preparation Example 1, except that the amount of epichlorohydrin added is 8 g.

[0044] Preparation Example 3

[0045] The preparation method of modified epoxy natural rubber-3 is the same as that of Preparation Example 1, except that the added amount of substance A is 0.7 g.

[0046] Preparation Example 4

[0047] The preparation method of modified polyurethane-1 comprises the following steps: adding 3g polycaprolactone diol, 1g isophorone diisocyanate and 0.001g DY-20 into a reaction container, stirring for 2.5h at 80°C under nitrogen protection, cooling to room temperature, adding 20ml DMF, stirring evenly, adding 0.15g 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol and 0.1g carboxymethyl chitosan, reacting at 55°C for 1h, and drying to obtain modified polyurethane-1.

[0048] Preparation Example 5

[0049] The preparation method of modified polyurethane-2 is the same as that of Preparation Example 4, except that the amount of polycaprolactone diol added is 5 g.

[0050] Preparation Example 6

[0051] The preparation method of modified polyurethane-3 is the same as that of Preparation Example 4, except that the added amount of 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol is 0.07 g.

[0052] Preparation Example 7

[0053] The preparation method of polyurethane comprises the following steps: adding 3g polycaprolactone diol, 1g isophorone diisocyanate and 0.001g DY-20 into a reaction container, stirring for 2.5h at 80°C under nitrogen protection, cooling to room temperature, adding 20ml DMF, stirring evenly, adding 0.15g 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol, reacting at 55°C for 1h, and drying to obtain polyurethane.

[0054] Example 1

[0055] A precision polishing grinding wheel comprises a grinding wheel matrix, an abrasive layer and a bonding adhesive between the grinding wheel matrix and the abrasive layer. The abrasive layer comprises the following raw materials in parts by weight: 50 parts of diamond, 1-15 parts of modified epoxy natural rubber, 4 parts of vulcanizing agent, 4.5 parts of DM and 1-25 parts of modified polyurethane.

[0056] The vulcanizing agent is a combination of sulfur and zinc oxide, and the mass ratio of the two is 1:2.

[0057] The preparation method of the precision polishing grinding wheel of this embodiment comprises the following steps:

[0058] S1. Grind the modified epoxy natural rubber-1 and modified polyurethane-1 to a particle size of 60 μm and add them into a mixer, then add diamond, vulcanizing agent and DM, heat to 125° C. and stir for 60 min to obtain a mixture;

[0059] S2, adding the mixture obtained in step S1 into a mold, pressing it into a ring shape on a hot press to obtain an abrasive layer, and the specific pressing process is: the first stage temperature is 80°C, the pressure is 1MPa, and the pressing time is 60s; the second stage temperature is 100°C, the pressure is 3MPa, and the pressing time is 135s; the third stage temperature is 120°C, the pressure is 5MPa, and the pressing time is 120s; the fourth stage temperature is 125°C, the pressure is 6MPa, and the pressing time is 15min;

[0060] S3, the abrasive layer obtained in step S2 is bonded to the grinding wheel base with an adhesive to obtain a precision polishing grinding wheel.

[0061] Example 2

[0062] A precision polishing grinding wheel comprises a grinding wheel matrix, an abrasive layer and a bonding adhesive between the grinding wheel matrix and the abrasive layer. The abrasive layer comprises the following raw materials in parts by weight: 45 parts of diamond, 13 parts of modified epoxy natural rubber-1, 3 parts of vulcanizing agent, 4 parts of DM and 20-30 parts of modified polyurethane-1.

[0063] The vulcanizing agent is a composition of sulfur and zinc oxide, and the mass ratio of the two is 1:1.

[0064] The preparation method of the precision polishing grinding wheel of this embodiment comprises the following steps:

[0065] S1. Grind the modified epoxy natural rubber-1 and modified polyurethane-1 to a particle size of 55 μm and add them into a mixer, then add diamond, vulcanizing agent and DM, heat to 130° C. and stir for 55 min to obtain a mixture;

[0066] S2, adding the mixture obtained in step S1 into a mold, pressing it into a ring shape on a hot press to obtain an abrasive layer, and the specific pressing process is: the first stage temperature is 78°C, the pressure is 0.9MPa, and the pressing time is 70s; the second stage temperature is 98°C, the pressure is 2.8MPa, and the pressing time is 140s; the third stage temperature is 118°C, the pressure is 4.8MPa, and the pressing time is 130s; the fourth stage temperature is 123°C, the pressure is 5.8MPa, and the pressing time is 17min;

[0067] S3, the abrasive layer obtained in step S2 is bonded to the grinding wheel base with an adhesive to obtain a precision polishing grinding wheel.

[0068] Example 3

[0069] A precision polishing grinding wheel comprises a grinding wheel matrix, an abrasive layer and a bonding adhesive between the grinding wheel matrix and the abrasive layer. The abrasive layer comprises the following raw materials in parts by weight: 55 parts of diamond, 18 parts of modified epoxy natural rubber-1, 5 parts of vulcanizing agent, 5 parts of DM and 30 parts of modified polyurethane-1.

[0070] The vulcanizing agent is a combination of sulfur and zinc oxide, and the mass ratio of the two is 1:3.

[0071] The preparation method of the precision polishing grinding wheel of this embodiment comprises the following steps:

[0072] S1. Grind the modified epoxy natural rubber-1 and modified polyurethane-1 to a particle size of 65 μm and add them into a mixer, then add diamond, vulcanizing agent and DM, heat to 120° C. and stir for 65 min to obtain a mixture;

[0073] S2, adding the mixture obtained in step S1 into a mold, pressing it into a ring shape on a hot press to obtain an abrasive layer, and the specific pressing process is: the temperature of the first stage is 83°C, the pressure is 1.1MPa, and the pressing time is 50s; the temperature of the second stage is 103°C, the pressure is 3.2MPa, and the pressing time is 110s; the temperature of the third stage is 123°C, the pressure is 5.2MPa, and the pressing time is 110s; the temperature of the fourth stage is 128°C, the pressure is 6.2MPa, and the pressing time is 13min;

[0074] S3, the abrasive layer obtained in step S2 is bonded to the grinding wheel base with an adhesive to obtain a precision polishing grinding wheel.

[0075] Example 4

[0076] A precision polishing grinding wheel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified epoxy natural rubber-1 is replaced by modified epoxy natural rubber-2.

[0077] Example 5

[0078] A precision polishing grinding wheel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified epoxy natural rubber-1 is replaced by modified epoxy natural rubber-3.

[0079] Example 6

[0080] A precision polishing grinding wheel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified polyurethane-1 is replaced by modified polyurethane-2.

[0081] Example 7

[0082] A precision polishing grinding wheel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified polyurethane-1 is replaced by modified polyurethane-3.

[0083] Comparative Example 1

[0084] A precision polishing grinding wheel and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that an equal amount of modified epoxy natural rubber-1 is replaced by epoxy natural rubber.

[0085] Comparative Example 2

[0086] A precision polishing grinding wheel and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified polyurethane-1 is replaced by polyurethane.

[0087] Performance Testing

[0088] The following tests were performed on the precision polishing wheels obtained in the above embodiments and comparative examples:

[0089] (1) Roughness

[0090] The zirconia ceramic plate was ground on a grinding machine using the precision polishing grinding wheel obtained in each embodiment and comparative example. The grinding wheel size was 210 mm (grinding wheel outer diameter) × 22.5 mm (grinding wheel thickness) × 160 mm (grinding wheel aperture), the grinding wheel speed was 2000 rpm, the grinding fluid was deionized water, and the removal amount was terminated when 5 μm was removed. The roughness was measured using a TR240 portable roughness meter.

[0091] (2) Wear ratio

[0092] The precision polishing grinding wheels and zirconia ceramic plates obtained in the above embodiments and comparative examples were weighed, and then the zirconia ceramic plates were processed according to the method in (1) roughness test, and then washed with deionized water, dried and weighed to calculate the wear ratio, which is the reduction in mass of the polishing grinding wheel / the reduction in mass of the zirconia ceramic plate. The smaller the wear ratio, the higher the polishing efficiency and the longer the service life of the grinding wheel.

[0093] The test results are shown in Table 1:

[0094] Table 1

[0095]

[0096]

[0097] It can be seen from the data in Table 1 that the polishing wheels obtained in Examples 1-3 of the present invention have good polishing effect and low loss; from the comparison between Example 4 and Example 1, it can be seen that the change in the ratio of gallic acid ester and epichlorohydrin in the modified epoxy natural rubber-2 may lead to a decrease in the aging resistance of the epoxy natural rubber and an increase in the loss and wear ratio; from the comparison between Example 5 and Example 1, it can be seen that the ratio of substance A to epoxy natural rubber in the modified epoxy natural rubber-3 is changed, the crosslinking degree is reduced, and the polishing effect is reduced; from the comparison between Example 6 and Example 1, it can be seen that the polycaprolactone diisocyanate in the modified polyurethane-2 is reduced. Changing the ratio of polyol to isophorone diisocyanate may lead to excessive toughness of the grinding wheel and a decrease in the polishing effect; from the comparison between Example 7 and Example 1, it can be seen that changing the ratio of 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol and carboxymethyl chitosan in modified polyurethane-3 may lead to excessive hardness of the grinding wheel, and both the polishing effect and the wear ratio are decreased; from the comparison between Comparative Example 1 and Example 1, it can be seen that the addition of unmodified epoxy natural rubber reduces the polishing effect and increases the wear ratio; from the comparison between Comparative Example 2 and Example 1, it can be seen that the addition of polyurethane makes the performance of the polishing wheel poor.

[0098] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A precision polishing grinding wheel, characterized in that: The invention comprises a grinding wheel matrix, an abrasive layer and a bonding adhesive between the grinding wheel matrix and the abrasive layer. The abrasive layer comprises the following raw materials in parts by weight: 45-55 parts of diamond, 13-18 parts of modified epoxy natural rubber, 3-5 parts of vulcanizing agent, 4-5 parts of vulcanization accelerator and 20-30 parts of modified polyurethane.

2. The precision polishing grinding wheel according to claim 1, characterized in that: The preparation method of the modified epoxy natural rubber comprises the following steps: (1) adding methyl gallate, epichlorohydrin and benzyltriethylammonium chloride into a reaction vessel and reacting at 75-85° C. for 4-5 hours to obtain substance A; (2) adding substance A obtained in step (1) and a catalyst to N,N-dimethylformamide, heating to 105-115° C., adding epoxidized natural rubber, stirring to react for 2-3 hours, extracting, combining the organic layers, washing, and drying to obtain substance B; (3) Add the substance B obtained in step (2) into chloroform and heat it to 45-55° C., add sodium hydroxide, react for 1-2 hours, wash and dry to obtain modified epoxy natural rubber.

3. The precision polishing grinding wheel according to claim 2, characterized in that: The mass ratio of the gallic acid ester to epichlorohydrin is 1:(0.5-0.6).

4. The precision polishing grinding wheel according to claim 2, characterized in that: In the step (2), the mass ratio of substance A to epoxidized natural rubber is (1-2):

1.

5. The precision polishing grinding wheel according to claim 1, characterized in that: The preparation method of the modified polyurethane comprises the following steps: adding polycaprolactone diol, isophorone diisocyanate and a catalyst into a reaction container, stirring for 2-3 hours at 75-85°C under nitrogen protection, cooling to room temperature, adding DMF, stirring evenly, adding 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol and carboxymethyl chitosan, reacting at 50-60°C for 0.5-2 hours, and drying to obtain the modified polyurethane.

6. The precision polishing grinding wheel according to claim 5, characterized in that: The mass ratio of the polycaprolactone diol to isophorone diisocyanate is (2-4):

1.

7. The precision polishing grinding wheel according to claim 5, characterized in that: The mass ratio of the 2,2,3,3,4,4-hexafluorocyclo-1,5-pentanediol to carboxymethyl chitosan is (1-2):

1.

8. The precision polishing grinding wheel according to claim 1, characterized in that: The vulcanizing agent is a composition of sulfur and zinc oxide, and the mass ratio of the two is 1:(1-3).

9. The precision polishing grinding wheel according to claim 1, characterized in that: The vulcanization accelerator is any one or more of DM, CZ, MZ and DPG.

10. A method for preparing the precision polishing grinding wheel according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Grind the modified epoxy natural rubber and modified polyurethane into particles with a diameter of 55-65 μm and add them into a mixer, then add diamond, vulcanizing agent and vulcanization accelerator, heat to 120-130° C. and stir for 55-65 min to obtain a mixture; S2, adding the mixture obtained in step S1 into a mold, pressing it into a ring shape on a hot press to obtain an abrasive layer, and the specific pressing process is: the temperature of the first stage is 78-83°C, the pressure is 0.9-1.1MPa, and the pressing time is 50-70s; the temperature of the second stage is 98-103°C, the pressure is 2.8-3.2MPa, and the pressing time is 110-140s; the temperature of the third stage is 118-123°C, the pressure is 4.8-5.2MPa, and the pressing time is 110-130s; the temperature of the fourth stage is 123-128°C, the pressure is 5.8-6.2MPa, and the pressing time is 13-17min; S3, the abrasive layer obtained in step S2 is bonded to the grinding wheel base with an adhesive to obtain a precision polishing grinding wheel.

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