High-removal optical element polishing white pad and production process thereof

Abstract

The application discloses a high-removal optical element polishing white pad and a production process thereof, and belongs to the technical field of optical element processing. The high-removal optical element polishing white pad comprises a substrate layer, a buffer layer and a polishing layer which are sequentially connected, the substrate layer is made of a polyimide and glass fiber composite material, the buffer layer is made of a polyurethane foaming material, and the surface of the polishing layer is provided with longitudinal and transverse intersecting grid grooves. The application solves the technical problem of low removal rate. The high-removal optical element polishing white pad and the production process thereof adopt high-temperature-resistant and high-strength polyimide material as the substrate layer, ensure stable form under high-speed rotation and pressure state, improve the overall service life, and the array protrusions are regularly arranged micro protrusions, the micro structures can increase the holding capacity of the polishing liquid, promote the effective rolling and shearing of the polishing particles, and thus the material removal rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical element processing, in particular to a high-removal optical element polishing white pad and a production process thereof. BACKGROUND

[0002] In the traditional polishing process of optical elements, low removal rate and difficult surface defect control are two major problems, which directly affect the processing efficiency and yield of optical elements. The existing polishing pad materials have problems such as insufficient wear resistance, poor thermal stability, or difficulty in adapting to complex curved surface polishing, which limits the processing precision and efficiency of optical elements. SUMMARY

[0003] The purpose of the present application is to provide a high-removal optical element polishing white pad and a production process thereof. By using polyurethane and polytetrafluoroethylene materials in the polishing layer, the wear resistance is good, and the chitosan and starch can improve the hydrophilicity of the polishing layer. At the same time, the array protrusions are regularly arranged micro-protrusions. These microstructures can increase the holding capacity of the polishing liquid, promote the effective rolling and shearing of the polishing particles, thereby improving the material removal rate and solving the problems raised in the background art.

[0004] To achieve the above purpose, the present application provides the following technical scheme: a high-removal optical element polishing white pad, comprising a substrate layer, a buffer layer and a polishing layer connected in sequence, the substrate layer is made of a polyimide and glass fiber composite material, the buffer layer is made of a polyurethane foam material, the surface of the polishing layer is provided with longitudinal and transverse intersecting grid grooves, the grid grooves divide the upper surface of the polishing layer into rectangular blocks, the rectangular blocks are connected with array protrusions, the upper surface of the array protrusions is a spherical structure, and the diameter of the array protrusions gradually decreases from top to bottom.

[0005] Preferably, the substrate layer comprises the following raw materials by weight: 56-75 parts of polyimide and 25-48 parts of glass fiber. The preparation method of the substrate layer is as follows: the glass fiber is arranged in the mold in a longitudinal and transverse intersecting manner, the polyimide is poured into the mold containing the glass fiber, and the polyimide is uniformly filled into the voids in the mold by vibration, and the polyimide and the glass fiber are combined into a whole by hot pressing to form the substrate layer.

[0006] Preferably, the preparation method of the glass fiber is as follows: the glass liquid is drawn into a fine fiber with a diameter of 10-20 μm by a drawing device, the fine fiber is washed, then immersed in a silane coupling agent solution for 1-2 hours, then washed with water to remove unreacted silane and solvent, and then dried by heating to remove residual moisture to form the glass fiber.

[0007] Preferably, the polyurethane foaming material comprises the following raw materials by weight: polyether polyol 90-110 parts, isocyanate 70-100 parts, foaming agent 3.5-5 parts, foam stabilizer 0-4 parts, catalyst 0-2 parts, chain extender 2-8 parts and lignumvitae powder 2-10 parts.

[0008] Preferably, the preparation method of the buffer layer comprises the following steps: uniformly dispersing lignumvitae powder in polyether polyol, then adding catalyst, chain extender, foaming agent and foam stabilizer, uniformly stirring rapidly, quickly adding isocyanate into the above mixture, uniformly stirring mechanically, pouring into a mold at 40-55℃ for foaming reaction, and standing at room temperature for 18h after the reaction is completed to obtain the buffer layer.

[0009] Preferably, the preparation method of the lignumvitae powder is as follows: pre-drying lignumvitae at a temperature between 60℃ and 100℃ to reduce the water content of lignumvitae to below 20%, slowly increasing the temperature to 180℃ and maintaining for 1-2h, naturally cooling to room temperature, crushing lignumvitae into powder with a size of 10-50um, immersing into perfluorooctyl vinyl ether solvent and adding polyisocyanate as crosslinking agent, curing at an environment of 40-50℃, and cleaning the surface after curing to remove excess monomers and by-products to obtain lignumvitae powder.

[0010] Preferably, the polishing layer comprises the following raw materials by weight: polyurethane powder 20-60 parts, polytetrafluoroethylene powder 10-50 parts, nano abrasive 1-10 parts, ammonium perfluorooctanoate 1-5 parts, three-arm bismaleimide-amino 3-5 parts, chitosan 1-5 parts and starch 2-6 parts.

[0011] Preferably, the nano abrasive comprises the following raw materials by weight: nano cerium 2-5 parts, nano alumina 3-4 parts and nano silicon oxide 1-2 parts.

[0012] Preferably, the preparation method of the polishing layer 3 is as follows: uniformly mixing polyurethane powder, polytetrafluoroethylene powder, nano abrasive, ammonium perfluorooctanoate, three-arm bismaleimide-amino, chitosan and starch, and putting the mixed material into a mold, pressing into a green body, preheating the green body, sintering the preheated green body on a hot roller with a surface temperature of 350℃ for 15-20s to obtain the polishing layer.

[0013] Another technical problem to be solved by the present application is to provide a production process of optical element polishing white pad with high removal rate, comprising the following steps:

[0014] Step one: first prepare the base layer and the polishing layer, and fill the material of the buffer layer between the base layer and the polishing layer, after the foaming of the material of the buffer layer is completed, heat-press the base layer and the polishing layer towards each other to obtain the base layer, the buffer layer and the polishing layer connected in sequence;

[0015] Step two: use laser engraving technology to process array protrusions and grid trenches on the surface of the polishing layer, then clean and dry, and trim the edges to obtain a polished white pad.

[0016] Compared with the prior art, the beneficial effects of the present application are:

[0017] The present application adopts high-temperature-resistant and high-strength polyimide material as the base layer, ensuring stable form under high-speed rotation and pressure state, improving overall service life, and adding pearwood powder in the buffer layer to enhance the mechanical strength of the polyurethane foaming material. The hydrophobicity of pearwood itself can help improve the hydrophobicity of the polyurethane foam to some extent. The hydrophobicity of the buffer layer makes it not easy to stick to the polishing liquid, keeps the internal space clean, facilitates heat dissipation, and uses polyurethane and polytetrafluoroethylene materials in the polishing layer, which has good wear resistance. Chitosan and starch can improve the hydrophilicity of the polishing layer, and the array protrusions are regularly arranged micro-bumps. These microstructures can increase the holding capacity of the polishing liquid, promote the effective rolling and shearing of the polishing particles, and thus improve the material removal rate. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 Structure diagram of the high-removal-rate optical element polishing white pad of the present application;

[0019] Fig. 2 Front view of the high-removal-rate optical element polishing white pad of the present application.

[0020] In the figure: 1, base layer; 2, buffer layer; 3, polishing layer; 31, array protrusions; 32, grid trenches. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] Embodiment one:

[0023] To solve the problems of low removal rate and difficult surface defect control of existing polishing white pads, please refer to Figs. 1-2 The present embodiment provides the following technical solutions:

[0024] The utility model provides a high removal rate's optical element polishing white pad, including the base layer 1, buffer layer 2 and polishing layer 3 connected in turn, the base layer 1 adopts the polyimide and glass fiber composite material is made, adopts high temperature resistance, high strength polyimide material as support layer, ensure that the stable form under high speed rotation and pressure state, improve overall service life, buffer layer 2 is made of polyurethane foaming material, as stress buffer zone, can effectively absorb the vibration in the polishing process, reduce the damage to optical element, help heat to dissipate quickly simultaneously, maintain constant polishing temperature, the surface of polishing layer 3 is provided with longitudinal and transverse interlaced grid ditch 32, inlaying grid ditch 32 in polishing layer 3, help the circulation flow of polishing liquid and heat dissipation, facilitate the chip generated in the polishing process to discharge simultaneously, reduce the risk of scratching, grid ditch 32 divides the upper surface of polishing layer 3 into rectangular block, and the rectangular block is connected with array protrusion 31, and the array protrusion 31 is regularly arranged micro convex point, these microstructures can increase the holding capacity of polishing liquid, promote the effective rolling and shearing of polishing particles, thereby improve material removal rate, the upper surface of array protrusion 31 is spherical structure, and the diameter of array protrusion 31 gradually reduces from top to bottom, the sidewall of array protrusion 31 is inwardly recessed structure, and the recessed degree of lower end is greater than upper end, by setting the shape of array protrusion 31, further increase the holding capacity of polishing liquid.

[0025] The base layer 1 includes the following raw materials by weight: 56 parts of polyimide and 26 parts of glass fiber. The base layer 1 is prepared by the following method: the glass fiber is arranged in a mold in a longitudinal and transverse interlaced manner, the polyimide is poured into the mold containing the glass fiber, and the polyimide is uniformly filled into the gaps in the mold by vibration, and the polyimide and the glass fiber are combined into a whole by hot pressing to form the base layer 1.

[0026] The glass fiber is prepared by the following method: the glass liquid is drawn into fine fibers with a diameter of 10-20 μm by a drawing device, the fine fibers are washed and then soaked in a silane coupling agent solution for 1-2 hours to allow the silane molecules to react with the silanol groups on the surface of the glass, then the unreacted silane and solvent are washed away with water, and then dried by heating to remove residual moisture to form the glass fiber.

[0027] The polyurethane foam material comprises the following raw materials in parts by weight: polyether polyol 90 parts, isocyanate 73 parts, foaming agent 4 parts, foam stabilizer 2 parts, catalyst 1 part, chain extender 5 parts, and pearwood powder 2 parts. The foaming agent is dimethyl ether, the foam stabilizer is polyether siloxane, the catalyst is polyethylene imine, the chain extender is ethylene glycol, and the pearwood powder is used as a natural filler to enhance the mechanical strength of the polyurethane foam material, such as improving its compressive strength and impact resistance, so that the material is more durable. The hydrophobicity of pearwood itself can help to improve the hydrophobicity of the polyurethane foam to some extent, and the wood structure helps to form a microporous structure, which may improve the air permeability of the material.

[0028] The preparation method of the buffer layer 2 comprises the following steps: uniformly dispersing the pearwood powder in the polyether polyol, then adding the catalyst, chain extender, foaming agent and foam stabilizer, rapidly stirring to be uniform, rapidly adding the isocyanate into the above mixture, mechanically stirring to be uniform, pouring into a 50℃ mold for foaming reaction, and standing at room temperature for 18h after the reaction is completed to obtain the buffer layer 2.

[0029] The preparation method of the pearwood powder is as follows: pre-drying the pearwood at a temperature of 60-100℃ to reduce the water content of the pearwood to below 20%, slowly increasing the temperature to 180℃ and maintaining for 1-2h, naturally cooling to room temperature, crushing the pearwood into powder with a size of 10-50um, changing the microstructure of the pearwood through high-temperature heat treatment to reduce its hygroscopicity and possibly change the surface chemical properties to improve the compatibility with polyurethane, immersing the pearwood into a perfluorooctyl vinyl ether solvent and adding a polyisocyanate as a crosslinking agent to solidify at an environment of 40-50℃, cleaning the surface after solidification to remove excess monomers and byproducts to obtain the pearwood powder, immersing the monomer solution containing fluorine atoms into the pearwood, and then initiating crosslinking by a chemical crosslinking agent to solidify the fluorinated monomer in the pores of the pearwood to form a stable bond with the pearwood. The fluorinated monomer in the perfluorooctyl vinyl ether solvent can form a hydrophobic layer on the surface of the material to effectively improve the hydrophobicity of the material and further enhance the hydrophobicity of the pearwood.

[0030] The polishing layer 3 comprises the following raw materials in parts by weight: polyurethane powder 24 parts, polytetrafluoroethylene powder 18 parts, nano abrasive 2 parts, ammonium perfluorooctanoate 1 part, three-arm bismaleimide-amino 3 parts, chitosan 1 part, and starch 2 parts.

[0031] The nano abrasive comprises the following raw materials in parts by weight: nano cerium 2 parts, nano aluminum oxide 3 parts, and nano silicon oxide 1 part.

[0032] The preparation method of the polishing layer 3 is as follows: polyurethane powder, polytetrafluoroethylene powder, nano abrasive, ammonium perfluorooctanoate, three-arm bismaleimide-amino, chitosan and starch are uniformly mixed, and the mixed material is put into a mold to be pressed into a green body, the green body is preheated, and the preheated green body is sintered on a hot roller with a surface temperature of 350°C for 15-20 seconds to form the polishing layer 3.

[0033] In order to better show the production process of the high-removal optical element polishing white pad, the present embodiment proposes a production process of the high-removal optical element polishing white pad, which comprises the following steps:

[0034] Step one: first prepare the base layer 1 and the polishing layer 3, and fill the material of the buffer layer 2 between the base layer 1 and the polishing layer 3, after the material of the buffer layer 2 is foamed, the base layer 1 and the polishing layer 3 are hot-pressed towards each other to strengthen the connection firmness between the layers, and the base layer 1, the buffer layer 2 and the polishing layer 3 connected in sequence are prepared;

[0035] Step two: use laser engraving technology to process array protrusions 31 and grid grooves 32 on the surface of the polishing layer 3, then clean and dry, and cut the edges to obtain the polishing white pad.

[0036] Embodiment two:

[0037] In this embodiment, the base layer 1 comprises the following raw materials by weight: 56 parts of polyimide and 26 parts of glass fiber;

[0038] The polyurethane foaming material comprises the following raw materials by weight: 90 parts of polyether polyol, 73 parts of isocyanate, 4 parts of foaming agent, 2 parts of foam stabilizer, 1 part of catalyst, 5 parts of chain extender and 2 parts of pearwood powder;

[0039] The polishing layer 3 comprises the following raw materials by weight: 24 parts of polyurethane powder, 18 parts of polytetrafluoroethylene powder, 2 parts of nano abrasive, 1 part of ammonium perfluorooctanoate, 3 parts of three-arm bismaleimide-amino, 3 parts of chitosan and 4 parts of starch.

[0040] The white pad is prepared by the same method as in embodiment one, and the content of chitosan and starch in the polishing layer 3 is increased in this embodiment.

[0041] Embodiment three:

[0042] In this embodiment, the base layer 1 comprises the following raw materials by weight: 56 parts of polyimide and 26 parts of glass fiber;

[0043] The polyurethane foaming material comprises the following raw materials by weight: 90 parts of polyether polyol, 73 parts of isocyanate, 4 parts of foaming agent, 2 parts of foam stabilizer, 1 part of catalyst, 5 parts of chain extender and 5 parts of pearwood powder;

[0044] The polishing layer 3 comprises the following raw materials by weight: 24 parts of polyurethane powder, 18 parts of polytetrafluoroethylene powder, 2 parts of nano abrasive, 1 part of ammonium perfluorooctanoate, 3 parts of tri-arm bismaleimide-amino, 1 part of chitosan, and 2 parts of starch.

[0045] The white pad is prepared by the same method as in Example 1, and the content of the pear wood powder in the polyurethane foaming material is increased in this embodiment.

[0046] Comparative Example 1

[0047] The same materials as in Example 1 are used to prepare the white pad by the following method: first, the base layer 1 and the polishing layer 3 are prepared, and the material of the buffer layer 2 is filled between the base layer 1 and the polishing layer 3. After the material of the buffer layer 2 is foamed, the base layer 1 and the polishing layer 3 are hot-pressed towards each other to strengthen the connection between the layers, thereby preparing the polished white pad.

[0048] Comparative Example 2

[0049] In this comparative example, the polishing layer 3 does not contain chitosan and starch components, and the other materials are the same as in Example 1. The polished white pad is prepared by the method of Example 1.

[0050] Comparative Example 3

[0051] In this comparative example, the polyurethane foaming material does not contain pear wood powder components, and the other materials are the same as in Example 1. The polished white pad is prepared by the method of Example 1.

[0052] The white pads processed in the above examples and comparative examples are measured, and the same polishing parameters are set. The 20-minute polishing experiment is performed on an optical glass with a diameter of 5 cm and an initial thickness of 5 mm, and the following data are obtained:

[0053]

[0054] From the above table, it can be seen that the polishing loss of the white pad prepared in the examples is lower than that of the white pad prepared in the comparative examples, and the wear resistance is better. In the same polishing time, the polishing thickness of the white pad prepared in the examples is higher, and the removal rate is higher. In Comparative Example 1, no array protrusions 31 and grid grooves 32 are set, and the overall polishing thickness is the lowest. In Comparative Example 3, no pear wood powder component is set, and the elasticity of the buffer layer 2 is the lowest. The increase of the content of chitosan and starch in Example 2 and the increase of the content of pear wood powder in the polyurethane foaming material in Example 3 both help to reduce the polishing loss, increase the polishing thickness, and increase the removal rate of the polished white pad.

[0055] In summary: the high removal rate of optical element polishing white pad and its production process, using high temperature resistance, high strength polyimide material as the base layer 1, ensure that in the high speed rotation and pressure state keeps stable form, improve the overall service life, the buffer layer 2 increase pear wood powder, can enhance the mechanical strength of polyurethane foaming material, pear wood itself hydrophobic can help to improve the hydrophobic performance of polyurethane foam to a certain extent, the hydrophobic property of buffer layer 2 makes it not easy to stick polishing liquid, keep the internal gap clean, facilitate heat dissipation, in the polishing layer 3 using polyurethane and polytetrafluoroethylene material, wear resistance is good, and chitosan and starch can improve the hydrophilicity of polishing layer 3, at the same time array convex 31 is regularly arranged micro convex, these microstructures can increase the holding capacity of polishing liquid, promote the effective rolling and shearing of polishing particles, thereby improving the material removal rate.

[0056] It should be noted that in this document, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply these entities or operations have any such actual relationship or order. Also, the terms "comprises", "comprising", or any other variations thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent to such a process, method, article, or apparatus.

[0057] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A white polishing pad for optical components with a high removal rate, comprising a base layer (1), a buffer layer (2) and a polishing layer (3) connected in sequence, characterized in that: The base layer (1) is made of a composite material of polyimide and glass fiber, the buffer layer (2) is made of a polyurethane foam material, the surface of the polishing layer (3) is provided with crisscross grid grooves (32), the grid grooves (32) divide the upper surface of the polishing layer (3) into rectangular blocks, the rectangular blocks are connected to array protrusions (31), the upper surface of the array protrusions (31) is a spherical structure, and the diameter of the array protrusions (31) gradually decreases from top to bottom; The base layer (1) comprises the following raw materials in parts by weight: 56-75 parts of polyimide and 25-48 parts of glass fiber. The base layer (1) is prepared by the following method: arranging the glass fiber in a crisscross pattern in a mold, adding polyimide into the mold containing the glass fiber, and using vibration to uniformly fill the gaps in the mold with the polyimide, and hot-pressing the polyimide and the glass fiber to form a whole, thereby preparing the base layer (1); The polyurethane foam material comprises the following raw materials in parts by weight: 90-110 parts of polyether polyol, 70-100 parts of isocyanate, 3.5-5 parts of foaming agent, 0-4 parts of foam stabilizer, 0-2 parts of catalyst, 2-8 parts of chain extender and 2-10 parts of pear wood powder; The polishing layer (3) comprises the following raw materials in parts by weight: 20-60 parts of polyurethane powder, 10-50 parts of polytetrafluoroethylene powder, 1-10 parts of nano-abrasive, 1-5 parts of ammonium perfluorooctanoate, 3-5 parts of three-arm bismaleimide-amino, 1-5 parts of chitosan and 2-6 parts of starch.

2. The optical element polishing white pad with high removal rate according to claim 1, characterized in that: The preparation method of the glass fiber is as follows: glass liquid is drawn into fine fibers with a diameter of 10-20 μm through a drawing device, the fine fibers are cleaned, and then the fine fibers are immersed in a silane coupling agent solution and soaked for 1-2 hours. Thereafter, unreacted silane and solvent are rinsed with water, and then residual moisture is removed by heating and drying to prepare glass fibers.

3. The optical element polishing white pad with high removal rate according to claim 1, characterized in that: The preparation method of the buffer layer (2) comprises the following steps: uniformly dispersing pear wood powder in polyether polyol, then adding a catalyst, a chain extender, a foaming agent and a foam stabilizer, and quickly stirring the mixture to be uniform; then quickly adding isocyanate to the mixture, mechanically stirring the mixture to be uniform; pouring the mixture into a mold at 40-55°C for foaming reaction; and standing the mixture at room temperature for 18 hours after the reaction is completed to obtain the buffer layer (2).

4. The optical element polishing white pad with high removal rate according to claim 1, characterized in that: The preparation method of the pear wood powder is as follows: pre-drying the pear wood at a temperature between 60°C and 100°C, reducing the moisture content of the pear wood to below 20%, slowly raising the temperature to 180°C and maintaining it for 1-2 hours, naturally cooling it to room temperature, crushing the pear wood into a powder of 10-50 μm in size, immersing it in a perfluorooctyl vinyl ether solvent, adding polyisocyanate as a cross-linking agent, and curing it at 40-50°C. After curing, cleaning the surface to remove excess monomers and by-products to obtain the pear wood powder.

5. The optical element polishing white pad with high removal rate according to claim 1, characterized in that: The nano-abrasive comprises the following raw materials in parts by weight: 2-5 parts of nano-cerium, 3-4 parts of nano-aluminum oxide and 1-2 parts of nano-silicon oxide.

6. The optical element polishing white pad with high removal rate according to claim 1, characterized in that: The preparation method of the polishing layer (3) is as follows: polyurethane powder, polytetrafluoroethylene powder, nano-abrasive, ammonium perfluorooctanoate, three-arm bismaleimide-amino, chitosan and starch are uniformly mixed, and the mixed materials are put into a mold, pressed into a green body, preheated, and sintered on a hot roller with a surface temperature of 350°C for 15-20 seconds to prepare the polishing layer (3).

7. A production process for a high-removal-rate optical element polishing white pad, for producing the high-removal-rate optical element polishing white pad described in any one of 1 to 6, characterized in that: The steps include: S1: first preparing a base layer (1) and a polishing layer (3), and filling the buffer layer (2) material between the base layer (1) and the polishing layer (3); after the foaming of the buffer layer (2) material is completed, hot pressing is performed from the base layer (1) and the polishing layer (3) toward each other to form a base layer (1), a buffer layer (2) and a polishing layer (3) connected in sequence; S2: Using laser engraving technology to process array protrusions (31) and grid grooves (32) on the surface of the polishing layer (3), then cleaning and drying, and trimming the edges to obtain a polishing white pad.

Images