A diamond polishing liquid for optical lenses and a method for preparing the same

Abstract

The application discloses a diamond polishing liquid for optical lenses and a preparation method thereof, and relates to the technical field of polishing materials.The application comprises the following raw materials in mass parts: deionized water 93.3-116.6 parts, diamond micro powder 4-5 parts, sodium polyacrylate 1.5-1.9 parts, a surfactant 0.3-0.4 parts, a synergist 0.5-0.6 parts, and a zwitterionic copolymer 0.2-0.25 parts; the synergist is poly(acrylic acid-co-hydroxyethyl acrylate)-b-poly(N-vinylbenzyl benzotriazole) block copolymer; and the zwitterionic copolymer is a sulfobetaine methacrylate-polyethylene glycol methacrylate copolymer.The introduction of the synergist, the zwitterionic copolymer and the like effectively improves the material adaptation range, the material removal rate, the low residual property and the stability of the diamond polishing liquid.Therefore, the application has a more extensive application prospect.

Description

Technical Field

[0001] This invention relates to the field of polishing materials technology, specifically to a diamond polishing slurry for optical lenses and its preparation method. Background Technology

[0002] Chemical mechanical polishing (CMP) materials are core materials for surface finishing of precision optical devices through the synergistic effect of chemicals and machinery, providing strong support for meeting the demands of optical systems for extreme surface finish and shape accuracy. Currently, optical devices are transitioning from traditional glass to advanced materials such as sapphire and quartz. While these materials possess advantages such as adaptability to extreme environments and broad spectral transmittance, their higher Mohs hardness (e.g., sapphire reaches level 9) places dual higher demands on the polishing process for "efficient material removal" and "low subsurface damage." The quality of precision polishing directly affects device performance: in high-power laser applications, surface irregularities can easily lead to localized heating and damage; in ultra-low scattering scientific instruments, nanoscale surface variations can reduce measurement accuracy; and maintaining optical performance under extreme environments also depends on the quality of the polished surface and the absence of subsurface damage.

[0003] Diamond abrasive slurry is key to addressing this challenge. Traditional abrasives (such as corundum and silicon carbide) have a Mohs hardness of less than 8, which leads to low removal efficiency, easy surface scratches, and thick subsurface damage layers when used with hard materials such as sapphire. Diamond (Mohs hardness of 10), with its extremely high hardness and excellent chemical stability, can effectively control the thickness of the surface damage layer while efficiently removing hard materials, thus meeting the core requirements of the grinding stage.

[0004] However, diamond polishing slurries still have the following performance shortcomings in practical applications: First, their stability is limited, and long-term storage can easily lead to particle agglomeration, resulting in decreased polishing uniformity. Second, their material compatibility is narrow; when polishing soft optical materials, they are prone to excessive surface damage, making it difficult to meet the differentiated polishing needs of both soft and hard materials. Third, there is a high risk of polishing residue; trace particles can degrade the light transmission performance of optical devices and increase the difficulty of subsequent cleaning. Fourth, their polishing efficiency is insufficient; the material removal rate for high-hardness single-crystal materials is low, and the uniformity of the micro-roughness of the surface after polishing needs to be improved. Therefore, the material compatibility, material removal rate, low residue, and stability of existing diamond polishing slurries still need to be improved. Summary of the Invention

[0005] The purpose of this invention is to provide a diamond polishing slurry for optical lenses and its preparation method, thereby solving the following technical problems: Existing diamond polishing fluids still have problems with material compatibility, material removal rate, low residue, and poor stability.

[0006] The objective of this invention can be achieved through the following technical solutions: A diamond polishing slurry for optical lenses comprises the following raw materials in parts by weight: 93.3-116.6 parts deionized water, 4-5 parts diamond micro powder, 1.5-1.9 parts sodium polyacrylate, 0.3-0.4 parts surfactant, 0.5-0.6 parts synergist, and 0.2-0.25 parts zwitterionic copolymer; The synergist is a poly(acrylic acid-co-hydroxyethyl acrylate)-b-poly(N-vinylbenzylbenzotriazole) block copolymer; The zwitterionic copolymer is a sulfobetaine methacrylate-polyethylene glycol methacrylate copolymer.

[0007] Preferably, the synergist is prepared by the following method: A1: Acrylic acid is subjected to vacuum distillation to obtain pretreated acrylic acid; A2: Hydroxyethyl acrylate was subjected to vacuum distillation to obtain pretreated hydroxyethyl acrylate; A3: Add pretreated acrylic acid, pretreated hydroxyethyl acrylate, 2-dodecyl thiocarbonyl thio-2-methylpropionic acid, and azobisisobutyronitrile to anhydrous N,N-dimethylformamide and bubble with high-purity nitrogen for 30-50 min. After sealing, heat to 70℃ and react for 12 h. After cooling, purify and dry to obtain the chain transfer agent. A4: Add vinyl benzyl chloride to anhydrous tetrahydrofuran and stir for 20-30 min to obtain a vinyl benzyl chloride solution; A5: Add benzotriazole and anhydrous potassium carbonate to anhydrous N,N-dimethylformamide and stir for 30-40 min. Then, add vinylbenzyl chloride solution dropwise under a nitrogen atmosphere, heat to 60℃ and react in the dark for 24-25 h. After cooling, filter and wash the filtrate. Then, add anhydrous magnesium sulfate to the organic phase and dry for 8-10 h. After filtration, remove N,N-dimethylformamide by vacuum distillation. Finally, purify and concentrate under vacuum to obtain N-vinylbenzylbenzotriazole. A6: Add N-vinylbenzylbenzotriazole, azobisisobutyronitrile, and anhydrous tetrahydrofuran to the chain transfer agent and stir for 20-30 min. Then bubble with nitrogen for 30-40 min, seal, heat to 65℃ and react in the dark for 36-40 h. After cooling, add saturated sodium bicarbonate aqueous solution and stir for 10-15 min. Then let stand to separate the layers and take the organic phase for dialyzing. After freeze-drying, the synergist is obtained.

[0008] Preferably, the ratio of anhydrous N,N-dimethylformamide, pretreated acrylic acid, pretreated hydroxyethyl acrylate, 2-dodecyl thiocarbonyl thio-2-methylpropionic acid, and azobisisobutyronitrile in A3 is 30-35 mL: 5.04 g: 3.48 g: 0.55 g: 0.055 g.

[0009] Preferably, the ratio of anhydrous tetrahydrofuran to vinylbenzyl chloride in A4 is 5-6 mL: 4.6 g.

[0010] Preferably, the ratio of anhydrous N,N-dimethylformamide, benzotriazole, anhydrous potassium carbonate, vinyl benzyl chloride solution, and anhydrous magnesium sulfate in A5 is 20 mL: 3 g: 2.78 g: 9-9.8 g: 5 g.

[0011] Preferably, the ratio of the chain transfer agent, N-vinylbenzylbenzotriazole, azobisisobutyronitrile, anhydrous tetrahydrofuran, and saturated sodium bicarbonate aqueous solution in A6 is 3g:2.51g:0.0247g:15-17mL:10mL.

[0012] Preferably, the zwitterionic copolymer is prepared as follows: Add sulfobetaine methacrylate, polyethylene glycol methacrylate, and mercaptoethanol to deionized water and stir for 20-30 min. Then, bubble high-purity nitrogen gas for 30-50 min. Then, add 4,4'-azobis(4-cyanopentanoic acid) under nitrogen atmosphere and react at 70-72℃ for 8-12 h. After cooling to 4-8℃, filter, dialyze, and freeze dry to obtain zwitterionic copolymer.

[0013] Preferably, the mass ratio of deionized water, sulfobetaine methacrylate, polyethylene glycol methacrylate, mercaptoethanol, and 4,4'-azobis(4-cyanovaleric acid) is 40-45:7:3:0.03:0.42.

[0014] A method for preparing a diamond polishing slurry for optical lenses includes the following steps: S1: Add deionized water to diamond micro powder and stir for 10-15 min, then let stand for 10-15 min, and then ultrasonically disperse for 10-20 min to obtain diamond dispersion; S2: While stirring, add sodium polyacrylate to deionized water 1 and stir for 15-20 min. Then add surfactant and stir for 10-15 min. Adjust the pH to 8.5-9.0 and stir for 10 min. Then add synergist and zwitterionic copolymer while stirring and stir for 20-30 min. Then add diamond dispersion and stir for 30-40 min. After ultrasonic treatment for 45-55 min, add deionized water 2 and stir for 2-3 h. Finally, ultrasonic treatment for 15-20 min to obtain diamond polishing slurry for optical lenses.

[0015] Preferably, the mass ratio of diamond micro powder to deionized water in S1 is 4-5:20-25; The mass ratio of deionized water 1, sodium polyacrylate, surfactant, synergist, zwitterionic copolymer, diamond dispersion, and deionized water 2 in S2 is 70-88:1.5-1.9:0.3-0.4:0.5-0.6:0.2-0.25:24-30:3.3-3.6.

[0016] The beneficial effects of this invention are: This invention provides a diamond polishing slurry for optical lenses and its preparation method. The invention improves the material compatibility, material removal rate, low residue and stability of the diamond polishing slurry through the following methods.

[0017] (1) The benzotriazole in the side chain of the synergist of this invention can be adsorbed onto the surface of sapphire through π-π stacking and van der Waals forces to form an organic film, thereby regulating the interaction between the abrasive and the substrate, inhibiting the excessive etching of the crystal surface by diamond micropowder, and avoiding local deep scratches; on the surface of calcium fluoride, benzotriazole can form a weak adsorption layer through hydrophobic interaction and van der Waals forces, reducing irregular grinding phenomena. The carboxyl group of the synergist main chain can be ionized into carboxylate ions under alkaline conditions of pH 8.5-9.0 in the grinding solution, increasing the negative charge density on the surface of diamond particles, and together with sodium polyacrylate, enhancing the double layer repulsion, reducing the formation of particle agglomerates, improving grinding uniformity, and thus improving the ability of diamond grinding solution to reduce surface roughness. Meanwhile, the synergist has a molecular weight greater than 3500 Da, and its polymer chains can cover the diamond surface, providing steric hindrance and further preventing particles from agglomerating, allowing more individual diamond particles to participate in cutting. The adsorption layer formed by benzotriazole can also reduce the crystal surface energy, reduce the adhesion between diamond particles and the workpiece surface, improve the desorption efficiency of particles after cutting, and avoid the attenuation of cutting ability caused by grinding debris encapsulation, thereby improving the material removal rate of diamond polishing fluid. The synergist backbone contains a large number of hydrophilic groups, and after treatment with saturated sodium bicarbonate, the carboxyl groups are partially salted, further enhancing the hydrophilicity and making it easy to desorb during water rinsing. Under alkaline conditions with a pH of 8.5-9.0 in the polishing fluid, both the crystal surface and the synergist backbone are negatively charged, and the electrostatic repulsion can weaken the adsorption strength. In addition, the "anti-polyelectrolyte effect" of the zwitterionic copolymer can also reduce the adsorption of polymers on the crystal surface, significantly reducing the residual amount of polishing fluid. The synergist adsorbs onto the diamond surface through hydrophobic segments (dodecyl) and polar groups in the main chain, forming a stable steric hindrance layer that effectively prevents particles from agglomerating. At the same time, the ionized carboxyl groups of the synergist's main chain carry a negative charge, which, together with sodium polyacrylate, enhances the negative charge density on the diamond particle surface, increases the electrostatic repulsion between particles, significantly reduces the agglomeration rate, and significantly improves the dispersion stability of the diamond polishing slurry.

[0018] (2) The polyethylene glycol long chain of the zwitterionic copolymer of the present invention can provide steric hindrance, prevent diamond micro powder agglomeration, avoid deep scratches caused by large-sized agglomerates, and improve grinding uniformity; its sulfobetaine group forms a stable hydration layer near the substrate through strong hydration, reduces direct contact between diamond and substrate, reduces surface micro-damage caused by mechanical friction, and improves the surface roughness reduction. The zwitterionic copolymer is electrically neutral as a whole and has extremely strong hydrophilicity. Therefore, its adsorption on the surface of sapphire (negatively charged hydroxyl groups on the surface) and calcium fluoride (slightly negatively charged on the surface) is extremely weak. It mainly exists in the aqueous phase in a free state. It is not easy to form adsorption residues, and it is easy to be washed and desorbed by water. It will not form a hydrophobic adsorption layer on the substrate surface. For sodium polyacrylate (anion) that may be strongly adsorbed on the sapphire surface in the system, the presence of zwitterionic copolymer can dilute its concentration in the interface region and indirectly reduce the residue rate. The steric hindrance of the polyethylene glycol chain in the zwitterionic copolymer and the strong hydration layer of the zwitterionic groups can synergize with sodium polyacrylate and surfactants in the original system, further enhancing the dispersion stability of diamond micropowder. The zwitterionic structure of the zwitterionic copolymer is not easily degraded, and its hydration layer will continue to exist, effectively inhibiting particle sedimentation and agglomeration, and prolonging the stability period of the grinding fluid.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The embodiments described below 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: A method for preparing a diamond polishing slurry for optical lenses is as follows: S1: 8g of acrylic acid was subjected to vacuum distillation at 60℃ and 0.01MPa for 20min to obtain pretreated acrylic acid; S2: 5g of hydroxyethyl acrylate was subjected to vacuum distillation at 80℃ and 0.01MPa for 20min to obtain pretreated hydroxyethyl acrylate; S3: Add 5.04g of pretreated acrylic acid, 3.48g of pretreated hydroxyethyl acrylate, 0.55g of 2-dodecylthiocarbonylthio-2-methylpropionic acid, and 0.055g of azobisisobutyronitrile to 30mL of anhydrous N,N-dimethylformamide, and bubble with high-purity nitrogen for 30min. After sealing, heat to 70℃ and react for 12h. After cooling, dropwise into 200mL of 0℃ diethyl ether stirred at 800r / min. After standing for 20min, remove the supernatant and redissolve the precipitate in 20mL of tetrahydrofuran. Then dropwise into 200mL of 0℃ diethyl ether again and let stand to remove the precipitate. Repeat the "tetrahydrofuran dissolution, ice-cold diethyl ether precipitation" process three times. Then vacuum dry at 40℃ for 12h to obtain the chain transfer agent. S4: Add 4.6 g of vinyl benzyl chloride to 5 mL of anhydrous tetrahydrofuran and stir for 20 min to obtain a vinyl benzyl chloride solution; S5: Add 3g benzotriazole and 2.78g anhydrous potassium carbonate to 20mL of anhydrous N,N-dimethylformamide and stir for 30min. Then, under a nitrogen atmosphere, add 9g vinylbenzyl chloride solution dropwise at 1.4g / min. Then, heat to 60℃ and react in the dark for 24h. After cooling, filter and wash the filtrate three times with deionized water. Then, add 5g anhydrous magnesium sulfate to the organic phase and dry for 8h. After filtration, remove N,N-dimethylformamide by vacuum distillation at 80℃ and 0.01MPa. Finally, purify by silica gel column chromatography (eluent is petroleum ether and ethyl acetate in a volume ratio of 4:1) and concentrate the target fraction under reduced pressure to obtain N-vinylbenzylbenzotriazole. S6: Add 2.51g N-vinylbenzylbenzotriazole, 0.0247g azobisisobutyronitrile, and 15-17mL anhydrous tetrahydrofuran to 3g chain transfer agent and stir for 20min. Then bubble with high-purity nitrogen for 30min. After sealing, heat to 65℃ and react in the dark for 36h. After cooling, add 10mL saturated sodium bicarbonate aqueous solution and stir for 10min. Then let stand to separate the layers and take the organic phase. Transfer the organic phase to a dialysis bag (MWCO: 3500Da) and dialyze with deionized water for 3 days (changing the water 3 times a day during this period). Finally, freeze-dry at -50℃ and 0.01MPa for 48h to obtain the synergist. S7: Add 7g of sulfobetaine methacrylate, 3g of polyethylene glycol methacrylate (Mn = 1000), and 0.03g of mercaptoethanol to 40mL of deionized water and stir for 20min. Then, bubble with high-purity nitrogen for 30min. Then, add 0.42g of 4,4'-azobis(4-cyanopentanoic acid) under nitrogen atmosphere and react at 70℃ for 8h. After cooling to 4℃, filter with a 0.45μm aqueous filter membrane, then transfer to a dialysis bag (MWCO: 3500Da) and dialyze with deionized water at 4℃ for 5 days (changing the water 3 times a day during this period). Freeze-dry at -50℃ for 48h to obtain zwitterionic copolymer. S8: Add 20 mL of deionized water to 4 g of diamond micro powder (particle size 1-2 μm) and stir for 10 min, then let stand for 10 min, and then ultrasonically disperse for 10 min to obtain diamond dispersion; S9: While stirring at 400 r / min, add 1.5 g of sodium polyacrylate to 70 mL of deionized water and stir for 15 min. Then add 0.3 g of surfactant XP-90 and stir for 10 min. Adjust the pH to 8.5 with 0.1 mol / L potassium hydroxide aqueous solution and stir for 10 min. Then add 0.5 g of synergist and 0.2 g of zwitterionic copolymer while stirring for 20 min. Then add 24 g of diamond dispersion at 1 mL / min and stir for 30 min. After ultrasonic treatment for 45 min, add 3.3 g of deionized water and stir at 500 r / min for 2 h. Finally, ultrasonic treatment for 15 min yields diamond polishing slurry for optical lenses.

[0022] Example 2: A method for preparing a diamond polishing slurry for optical lenses is as follows: S1: 9g of acrylic acid was subjected to vacuum distillation at 60℃ and 0.01MPa for 20-30min to obtain pretreated acrylic acid; S2: 6g of hydroxyethyl acrylate was subjected to vacuum distillation at 80℃ and 0.01MPa for 25min to obtain pretreated hydroxyethyl acrylate; S3: Add 5.04g of pretreated acrylic acid, 3.48g of pretreated hydroxyethyl acrylate, 0.55g of 2-dodecylthiocarbonylthio-2-methylpropionic acid, and 0.055g of azobisisobutyronitrile to 33mL of anhydrous N,N-dimethylformamide, and bubble with high-purity nitrogen for 40min. After sealing, heat to 70℃ and react for 12h. After cooling, dropwise into 200mL of ether at 3℃ with stirring at 900r / min. After standing for 25min, remove the supernatant and redissolve the precipitate in 20mL of tetrahydrofuran. Then dropwise into 200mL of ether at 3℃ again and let stand to remove the precipitate. Repeat the "tetrahydrofuran dissolution, ice-cold ether precipitation" process three times. After vacuum drying at 40℃ for 14h, obtain the chain transfer agent. S4: Add 4.6 g of vinyl benzyl chloride to 5.5 mL of anhydrous tetrahydrofuran and stir for 25 min to obtain a vinyl benzyl chloride solution; S5: Add 3g benzotriazole and 2.78g anhydrous potassium carbonate to 20mL of anhydrous N,N-dimethylformamide and stir for 35min. Then, under a nitrogen atmosphere, add 9.4g vinylbenzyl chloride solution dropwise at 1.5g / min. Heat to 60℃ and react in the dark for 24.5h. After cooling, filter and wash the filtrate 4 times with deionized water. Then, add 5g anhydrous magnesium sulfate to the organic phase and dry for 9h. After filtration, remove N,N-dimethylformamide by vacuum distillation at 80℃ and 0.01MPa. Finally, purify by silica gel column chromatography (eluent is petroleum ether and ethyl acetate in a volume ratio of 4:1) and concentrate the target fraction under reduced pressure to obtain N-vinylbenzylbenzotriazole. S6: Add 2.51g N-vinylbenzylbenzotriazole, 0.0247g azobisisobutyronitrile, and 16mL anhydrous tetrahydrofuran to 3g chain transfer agent and stir for 25min. Then bubble with high-purity nitrogen for 35min, seal, heat to 65℃ and react in the dark for 38h. After cooling, add 10mL saturated sodium bicarbonate aqueous solution and stir for 13min. Then let stand to separate the layers and take the organic phase. Transfer the organic phase to a dialysis bag (MWCO: 3500Da) and dialyze with deionized water for 3 days (changing the water 3 times a day during this period). Finally, freeze-dry at -50℃ and 0.01MPa for 49h to obtain the synergist. S7: Add 7g of sulfobetaine methacrylate, 3g of polyethylene glycol methacrylate (Mn = 1000), and 0.03g of mercaptoethanol to 43mL of deionized water and stir for 25min. Then, bubble with high-purity nitrogen for 30-50min. Then, add 0.42g of 4,4'-azobis(4-cyanopentanoic acid) under nitrogen atmosphere and react at 71℃ for 10h. After cooling to 6℃, filter with a 0.45μm aqueous filter membrane, then transfer to a dialysis bag (MWCO: 3500Da) and dialyze with deionized water at 4℃ for 5 days (changing the water 3 times a day during this period). Freeze-dry at -50℃ for 49h to obtain zwitterionic copolymer. S8: Add 23 mL of deionized water to 4.5 g of diamond micro powder (particle size 1-2 μm) and stir for 13 min, then let stand for 13 min, and then ultrasonically disperse for 15 min to obtain a diamond dispersion. S9: While stirring at 450 r / min, add 1.7 g of sodium polyacrylate to 79 mL of deionized water and stir for 18 min. Then add 0.35 g of surfactant AEO-9 and stir for 10-15 min. Adjust the pH to 8.8 with 0.1 mol / L potassium hydroxide aqueous solution and stir for 10 min. Then add 0.55 g of synergist and 0.23 g of zwitterionic copolymer while stirring for 25 min. Then add 27 g of diamond dispersion at 1.5 mL / min and stir for 35 min. After ultrasonic treatment for 50 min, add 3.4 g of deionized water and stir at 500 r / min for 2.5 h. Finally, ultrasonic treatment for 18 min yields the diamond polishing slurry for optical lenses.

[0023] Example 3: A method for preparing a diamond polishing slurry for optical lenses is as follows: S1: 10g of acrylic acid was subjected to vacuum distillation at 60℃ and 0.01MPa for 20-30min to obtain pretreated acrylic acid; S2: 7g of hydroxyethyl acrylate was subjected to vacuum distillation at 80℃ and 0.01MPa for 30min to obtain pretreated hydroxyethyl acrylate; S3: Add 5.04g of pretreated acrylic acid, 3.48g of pretreated hydroxyethyl acrylate, 0.55g of 2-dodecylthiocarbonylthio-2-methylpropionic acid, and 0.055g of azobisisobutyronitrile to 35mL of anhydrous N,N-dimethylformamide, and bubble with high-purity nitrogen for 50min. After sealing, heat to 70℃ and react for 12h. After cooling, dropwise into 200mL of 5℃ diethyl ether stirred at 1000r / min. After standing for 30min, remove the supernatant and redissolve the precipitate in 20mL of tetrahydrofuran. Then dropwise into 200mL of 5℃ diethyl ether again and let stand to remove the precipitate. Repeat the "tetrahydrofuran dissolution, ice-cold diethyl ether precipitation" process three times. Then vacuum dry at 40℃ for 15h to obtain the chain transfer agent. S4: Add 4.6 g of vinyl benzyl chloride to 6 mL of anhydrous tetrahydrofuran and stir for 30 min to obtain a vinyl benzyl chloride solution; S5: Add 3g benzotriazole and 2.78g anhydrous potassium carbonate to 20mL of anhydrous N,N-dimethylformamide and stir for 30-40min. Then, under a nitrogen atmosphere, add 9.8g vinylbenzyl chloride solution dropwise at 1.6g / min. Heat to 60℃ and react in the dark for 25h. After cooling, filter and wash the filtrate 5 times with deionized water. Then, add 5g anhydrous magnesium sulfate to the organic phase and dry for 10h. After filtration, remove N,N-dimethylformamide by vacuum distillation at 80℃ and 0.01MPa. Finally, purify by silica gel column chromatography (eluent is petroleum ether and ethyl acetate in a volume ratio of 4:1) and concentrate the target fraction under reduced pressure to obtain N-vinylbenzylbenzotriazole. S6: Add 2.51g N-vinylbenzylbenzotriazole, 0.0247g azobisisobutyronitrile, and 17mL anhydrous tetrahydrofuran to 3g chain transfer agent and stir for 30min. Then bubble with high-purity nitrogen for 40min. After sealing, heat to 65℃ and react in the dark for 40h. After cooling, add 10mL saturated sodium bicarbonate aqueous solution and stir for 15min. Then let stand to separate the layers and take the organic phase. Transfer the organic phase to a dialysis bag (MWCO: 3500Da) and dialyze with deionized water for 3 days (changing the water 3 times a day during this period). Finally, freeze-dry at -50℃ and 0.01MPa for 50h to obtain the synergist. S7: Add 7g of sulfobetaine methacrylate, 3g of polyethylene glycol methacrylate (Mn = 1000), and 0.03g of mercaptoethanol to 45mL of deionized water and stir for 30min. Then, bubble with high-purity nitrogen for 50min. Then, add 0.42g of 4,4'-azobis(4-cyanopentanoic acid) under nitrogen atmosphere and react at 72℃ for 12h. After cooling to 8℃, filter with a 0.45μm aqueous filter membrane, then transfer to a dialysis bag (MWCO: 3500Da) and dialyze with deionized water at 4℃ for 5 days (changing the water 3 times a day during this period). Freeze-dry at -50℃ for 50h to obtain zwitterionic copolymer. S8: Add 25 mL of deionized water to 5 g of diamond micro powder (particle size 1-2 μm) and stir for 15 min, then let stand for 15 min, and then ultrasonically disperse for 20 min to obtain diamond dispersion. S9: While stirring at 500 r / min, add 1.9 g of sodium polyacrylate to 88 mL of deionized water and stir for 20 min. Then add 0.4 g of surfactant AEO-9 and stir for 15 min. Adjust the pH to 9.0 with 0.1 mol / L potassium hydroxide aqueous solution and stir for 10 min. Then add 0.6 g of synergist and 0.25 g of zwitterionic copolymer while stirring and stir for 30 min. Then add 30 g of diamond dispersion at 2 mL / min and stir for 40 min. After ultrasonic treatment for 55 min, add 3.6 g of deionized water and stir at 500 r / min for 3 h. Finally, ultrasonic treatment for 20 min yields diamond polishing slurry for optical lenses.

[0024] Comparative Example 1: Compared with Example 1, this comparative example only did not add a "synergist" in the preparation process of S9. All other steps and parameters were the same, and will not be repeated here. The final result was a diamond polishing slurry for optical lenses.

[0025] Comparative Example 2: Compared with Example 1, this comparative example only did not add "zwitterionic copolymer" in the preparation process of S9. All other steps and parameters were the same, and will not be repeated here. The final result was a diamond polishing slurry for optical lenses.

[0026] Performance testing: Surface roughness measurement: The optical lenses prepared in Examples 1-3 and Comparative Examples 1-2 of this invention were ground with diamond polishing fluid on sapphire and calcium fluoride crystals for 20 minutes at a pressure of 0.1 MPa, a grinding disc speed of 50 r / min, and a polishing fluid flow rate of 10 mL / min. After that, the surface of the workpiece was rinsed with flowing deionized water for 30 seconds and then naturally dried. The surface roughness (nm) of the two materials is shown in Table 1.

[0027] Determination of material removal rate: The optical lenses prepared in Examples 1-3 and Comparative Examples 1-2 of this invention were ground with diamond polishing fluid on sapphire and calcium fluoride crystals for 20 minutes at a pressure of 0.1 MPa, a grinding disc speed of 50 r / min, and a polishing fluid flow rate of 10 mL / min. After that, the workpiece surface was rinsed with flowing deionized water for 30 seconds and then naturally dried. The material removal rate (μm / min) of the two materials was measured. The test results are shown in Table 1.

[0028] Determination of residual rate: The optical lenses prepared in Examples 1-3 and Comparative Examples 1-2 of this invention were ground with diamond polishing sapphire at a pressure of 0.1 MPa, a grinding disc speed of 50 r / min, and a polishing slurry flow rate of 10 mL / min for 20 min. After that, the workpiece surface was rinsed with flowing deionized water for 30 s and allowed to air dry. The polishing slurry residue rate (%) on the material surface was measured. The test results are shown in Table 2.

[0029] Determination of dispersion stability: The agglomeration rate (%) of the optical lenses prepared by Examples 1-3 and Comparative Examples 1-2 of the present invention after standing for 180 days with diamond polishing slurry was determined, and the test results are shown in Table 2.

[0030] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-2

[0031] Table 2: Performance test results of Examples 1-3 and Comparative Examples 1-2

[0032] Data Analysis: As can be seen from Tables 1 and 2, the diamond polishing slurry for optical lenses prepared in the embodiments of the present invention has excellent polishing performance, material compatibility range, material removal rate, low residue and stability.

[0033] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A diamond polishing fluid for optical lenses, characterized in that, The raw materials include the following parts by weight: 93.3-116.6 parts deionized water, 4-5 parts diamond micro powder, 1.5-1.9 parts sodium polyacrylate, 0.3-0.4 parts surfactant, 0.5-0.6 parts synergist, and 0.2-0.25 parts zwitterionic copolymer; The preparation method of the synergist is as follows: A1: Acrylic acid is subjected to vacuum distillation to obtain pretreated acrylic acid; A2: Hydroxyethyl acrylate was subjected to vacuum distillation to obtain pretreated hydroxyethyl acrylate; A3: Add pretreated acrylic acid, pretreated hydroxyethyl acrylate, 2-dodecyl thiocarbonyl thio-2-methylpropionic acid, and azobisisobutyronitrile to anhydrous N,N-dimethylformamide and bubble with high-purity nitrogen for 30-50 min. After sealing, heat to 70℃ and react for 12 h. After cooling, purify and dry to obtain the chain transfer agent. A4: Add vinyl benzyl chloride to anhydrous tetrahydrofuran and stir for 20-30 min to obtain a vinyl benzyl chloride solution; A5: Add benzotriazole and anhydrous potassium carbonate to anhydrous N,N-dimethylformamide and stir for 30-40 min. Then, add vinylbenzyl chloride solution dropwise under a nitrogen atmosphere, heat to 60℃ and react in the dark for 24-25 h. After cooling, filter and wash the filtrate. Then, add anhydrous magnesium sulfate to the organic phase and dry for 8-10 h. After filtration, remove N,N-dimethylformamide by vacuum distillation. Finally, purify and concentrate under vacuum to obtain N-vinylbenzylbenzotriazole. A6: Add N-vinylbenzylbenzotriazole, azobisisobutyronitrile, and anhydrous tetrahydrofuran to the chain transfer agent and stir for 20-30 min. Then bubble with nitrogen for 30-40 min, seal, heat to 65℃ and react in the dark for 36-40 h. After cooling, add saturated sodium bicarbonate aqueous solution and stir for 10-15 min. Then let stand to separate the layers and take the organic phase for dialyzing. After freeze-drying, the synergist is obtained. The preparation method of the zwitterionic copolymer is as follows: Add sulfobetaine methacrylate, polyethylene glycol methacrylate, and mercaptoethanol to deionized water and stir for 20-30 min. Then, bubble high-purity nitrogen gas for 30-50 min. Then, add 4,4'-azobis(4-cyanopentanoic acid) under nitrogen atmosphere and react at 70-72℃ for 8-12 h. After cooling to 4-8℃, filter, dialyze, and freeze dry to obtain zwitterionic copolymer. The surfactant is either surfactant XP-90 or surfactant AEO-9; The pH of the diamond polishing solution used for the optical lenses is 8.5-9.

2. The diamond polishing slurry for optical lenses according to claim 1, characterized in that, The ratio of anhydrous N,N-dimethylformamide, pretreated acrylic acid, pretreated hydroxyethyl acrylate, 2-dodecyl thiocarbonyl thio-2-methylpropionic acid, and azobisisobutyronitrile in A3 is 30-35 mL: 5.04 g: 3.48 g: 0.55 g: 0.055 g.

3. The diamond polishing slurry for optical lenses according to claim 1, characterized in that, The ratio of anhydrous tetrahydrofuran to vinylbenzyl chloride described in A4 is 5-6 mL: 4.6 g.

4. The diamond polishing slurry for optical lenses according to claim 1, characterized in that, The ratio of anhydrous N,N-dimethylformamide, benzotriazole, anhydrous potassium carbonate, vinyl benzyl chloride solution, and anhydrous magnesium sulfate in A5 is 20 mL: 3 g: 2.78 g: 9-9.8 g: 5 g.

5. The diamond polishing slurry for optical lenses according to claim 1, characterized in that, The ratio of chain transfer agent, N-vinylbenzylbenzotriazole, azobisisobutyronitrile, anhydrous tetrahydrofuran, and saturated sodium bicarbonate aqueous solution in A6 is 3g:2.51g:0.0247g:15-17mL:10mL.

6. The diamond polishing slurry for optical lenses according to claim 1, characterized in that, The mass ratio of deionized water, sulfobetaine methacrylate, polyethylene glycol methacrylate, mercaptoethanol, and 4,4'-azobis(4-cyanovaleric acid) is 40-45:7:3:0.03:0.

42.

7. A method for preparing a diamond polishing slurry for optical lenses according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Add deionized water to diamond micro powder and stir for 10-15 min, then let stand for 10-15 min, and then ultrasonically disperse for 10-20 min to obtain diamond dispersion; S2: While stirring, add sodium polyacrylate to deionized water 1 and stir for 15-20 min. Then add surfactant and stir for 10-15 min. Adjust the pH to 8.5-9.0 and stir for 10 min. Then add synergist and zwitterionic copolymer while stirring and stir for 20-30 min. Then add diamond dispersion and stir for 30-40 min. After ultrasonic treatment for 45-55 min, add deionized water 2 and stir for 2-3 h. Finally, ultrasonic treatment for 15-20 min to obtain diamond polishing slurry for optical lenses.

8. The method for preparing diamond polishing slurry for optical lenses according to claim 7, characterized in that, The mass ratio of diamond micro powder to deionized water in S1 is 4-5:20-25; The mass ratio of deionized water 1, sodium polyacrylate, surfactant, synergist, zwitterionic copolymer, diamond dispersion, and deionized water 2 in S2 is 70-88: 1.5-1.9：0.3-0.4：0.5-0.6：0.2-0.25：24-30：3.3-3.6。

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