CN111216037B

CN111216037B - Polishing pad and preparation method thereof

Info

Publication number: CN111216037B
Application number: CN202010213590.1A
Authority: CN
Inventors: 王国微; 汪静
Original assignee: Henan Union Precision Material Co ltd
Current assignee: Henan Union Precision Material Co ltd
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2021-03-30
Anticipated expiration: 2040-03-24
Also published as: CN111216037A

Abstract

The invention belongs to the technical field of polishing tool processing, and particularly relates to a polishing pad and a preparation method thereof. The abrasive layer of the polishing pad comprises the following components in percentage by mass: 10-22% of aggregate abrasive, 1-5% of coupling agent, 45-65% of resin bonding agent, 10-20% of calcium carbonate, 10-20% of cerium oxide, 1-5% of fumed silica, 1-5% of sodium bicarbonate and 1-3% of filament fiber. In the polishing pad abrasive layer, sodium bicarbonate can be decomposed in the curing process as a pore-forming agent to generate micro pores, so that chip removal is facilitated during polishing of the polishing pad, the stability of polishing efficiency is facilitated, the strength of a working layer can be ensured by taking cerium oxide, calcium carbonate, fumed silica, nano alumina and the like as filling materials, the cerium oxide is used as an auxiliary abrasive, the fumed silica can prevent sedimentation to enable slurry components to be uniform, and the filament fibers play a role of framework support during molding of the abrasive layer.

Description

Polishing pad and preparation method thereof

Technical Field

The invention belongs to the technical field of polishing tool processing, and particularly relates to a polishing pad and a preparation method thereof.

Background

The abrasive currently used for lapping, grinding or polishing can be free abrasive, e.g., in the form of a slurry, or fixed abrasive, e.g., a coated abrasive or a bonded abrasive article. In consideration of the removal rate and the processing quality, composite abrasives (also called aggregate abrasives) processed by single-phase abrasives are more and more popular and widely used in the fields of metal processing and manufacturing, optical glass processing and the like.

The application publication number of the Chinese invention patent application is CN103608424A, which discloses an abrasive product containing an aggregate abrasive, wherein an abrasive belt can be prepared for processing a workpiece, and a bonding material used in the preparation of the aggregate abrasive is a glass bonding material, so that the surface of the workpiece is easily damaged, and the abrasive product is not suitable for processing the workpiece with high processing precision; the Chinese invention patent application with application publication number CN110216597A discloses a resin polishing block with a composite abrasive grain structure, which comprises 8-20% of composite abrasive grains, 50-70% of resin bonding agent, 10-18% of functional additive and 5-15% of pore-forming agent by mass percentage, wherein the resin bonding agent is modified phenolic resin, the functional additive is at least one of graphite powder, talcum powder, cryolite powder, calcium carbonate, sodium stearate and zinc stearate, and the pore-forming agent is one of salt, magnesium sulfate and polyethylene hollow spheres. The resin polishing block has the problems of low polishing efficiency and short service life, so that the polishing cost is high when the resin polishing block is used for polishing workpieces with high machining precision requirements.

Disclosure of Invention

The invention aims to provide a polishing pad, which aims to solve the problems of low polishing efficiency and short service life of the conventional resin polishing block.

Another object of the present invention is to provide a method for preparing a polishing pad, which solves the problems of low polishing efficiency and short service life of the polishing pad obtained by the existing method for preparing the polishing pad.

In order to achieve the above object, the polishing pad of the present invention comprises:

a polishing pad is characterized in that an abrasive layer of the polishing pad is formed by solidifying the following raw materials in percentage by mass: 10-22% of aggregate abrasive, 1-5% of coupling agent, 45-65% of resin bonding agent, 10-20% of calcium carbonate, 10-20% of cerium oxide, 1-5% of fumed silica, 1-5% of sodium bicarbonate and 1-3% of filament fiber.

The sodium bicarbonate in the raw materials of the abrasive layer of the polishing pad can be decomposed in the curing process as a pore-forming agent to generate micro pores, so that chip removal is facilitated during polishing of the polishing pad, the stability of polishing efficiency is facilitated, the strength of the abrasive layer can be ensured by taking cerium oxide, calcium carbonate, fumed silica, nano alumina and the like as filling materials, and the cerium oxide is used as an auxiliary abrasive, and the fumed silica can prevent sedimentation, so that slurry components are uniform. The filament fibers serve as a framework support during the formation of the abrasive layer and may be selected from wool, typically 14.5-15.5 μm in diameter. The coupling agent is used for surface modification of the aggregate abrasive to improve the bonding performance between the individual abrasive particles and the resin binder, and is selected from KH-550. The polishing pad provided by the invention takes the aggregate abrasive as the abrasive, has the polishing quality of the nano-grade abrasive particles and the polishing removal amount of the micron-grade abrasive particles, and can improve the polishing efficiency and prolong the service life while ensuring the polishing precision.

Considering polishing efficiency and polishing precision comprehensively, generally, the aggregate abrasive is formed by aggregating nano abrasive particles, and the particle size of the aggregate abrasive is 1-3 μm. The particle size of the fumed silica is 200-300nm, and the particle size of the sodium bicarbonate is 100-150 mu m.

The preparation method of the aggregate abrasive comprises the following steps:

1) uniformly mixing the nano abrasive particles, the surfactant and the silica sol to obtain a mixed solution;

2) stirring the mixed solution obtained in the step 1) with a water binding agent, and separating out an aggregate abrasive precursor;

3) sintering the aggregate abrasive precursor obtained in the step 2) at the temperature of 450-750 ℃ for 1-3 h;

wherein the solid content of the silica sol in the step 1) is 35-55%.

In the preparation method of the aggregate abrasive, the silica sol plays a role of a binder; the surfactant can promote the bonding between the nano abrasive particles, generally, the surfactant is an anionic surfactant, is beneficial to enhancing the bonding effect of silica sol, and specifically adopts AY-65, AY-50 and the like; the water-binding agent can combine with water in the system to make the silica sol exert the binding effect, and the specific water-binding agent can be a liquid water-binding agent so as to facilitate the subsequent separation, such as C₄-C₁₁The fatty alcohol of (2) may be, specifically, isooctanol, isobutanol, etc.; the uniform mixed solution can be obtained by stirring, further, rotary stirring can be selected, for example, a high-speed shear stirrer is used, the water binding agent is gradually combined with the water in the silica sol, so as to obtain a uniform aggregate abrasive precursor, the aggregate abrasive precursor with a proper particle size is obtained by controlling the rotating speed and the stirring time, and generally, the mixture is stirred for 1-2 hours at the rotating speed of 1500-.

Further, the polishing pad comprises an elastic base and a transition layer arranged on the elastic base, wherein the abrasive layer is compounded on the non-woven fabric base material to form a working layer, and the working layer is compounded on the surface of the transition layer.

The non-woven fabric substrate is compounded with the abrasive layer, so that the formed working layer and the transition layer are combined more firmly, the strength of the polishing pad is further enhanced, and the non-woven fabric substrate also has a certain supporting effect on the abrasive layer; the arrangement of the transition layer can avoid the problem of low bonding strength when the working layer is directly bonded with the elastic substrate, thereby improving the bonding strength of the whole polishing pad; the elastic substrate can make the polishing pad have certain flexibility, be difficult to damage the work piece to can make the polishing pad take place little elastic deformation so that the avris has the work piece of treating of certain radian and also can accomplish comprehensive polishing in the polishing operation, for example cell-phone cover plate glass, the transition between the biggest surface of its area and the side has certain radian, can further improve holistic polishing quality to this partial polishing. Generally, the elastic substrate can be selected from a rubber plate, and the Shore hardness of the rubber plate is A30-40.

The polishing pad disclosed by the invention has the advantages of high polishing efficiency, low processing cost and high processing precision, can avoid the use of a large amount of chemical reagents in common free abrasive polishing solution, and is energy-saving and environment-friendly.

The thickness of the working layer is 1.0-2.0mm, the thickness of the non-woven fabric base material is 200-300 mu m, and the thickness of the transition layer is 0.5-1.0 mm.

The thickness of the working layer and the transition layer is set to ensure the service life of the polishing pad and the sufficient and appropriate transition buffering effect, so that the service life of the polishing pad is prolonged.

Specifically, the transition layer is formed by solidifying the following raw materials in percentage by mass: 55-70% of resin binder, 20-30% of calcium carbonate and 10-20% of nano aluminum oxide. Typically, the calcium carbonate has an average particle size of 1 to 3 μm; the average grain diameter of the nano-alumina is 100-200 nm.

The raw materials of transition layer and the raw materials nature of working layer are similar, and the purpose is to improve the bonding ability of transition layer and working layer, guarantee the bonding strength of transition layer and working layer to improve polishing pad's intensity and life.

The resin binder comprises the following components in percentage by mass: 45-63.5% of thermosetting resin, 35-53.5% of amine curing agent, 1-5% of dispersant and 0.5-1.5% of accelerator. The dispersing agent can promote the components of the resin binder to be uniformly dispersed in the system, and when the system is heated, the thermosetting resin cures and forms the abrasive layer, the non-woven fabric substrate and the transition layer under the action of the amine curing agent and the accelerating agent.

The transition layer is bonded to the elastic substrate through an adhesive layer. The bonding layer can improve the connection strength of the elastic substrate and the transition layer, so that the strength of the polishing pad is improved.

The thickness of the adhesive layer is 100-150 μm, and the thickness of the elastic substrate is 1000-1200 μm. The thickness of the bonding layer is set to provide the necessary strength for the connection between the resilient base and the transition layer, and the thickness of the resilient base is set to provide the polishing pad with suitable flexibility for the resilient deformation of the polishing pad during the polishing operation.

The preparation method of the polishing pad comprises the following specific technical scheme:

a method of preparing a polishing pad comprising the steps of:

A. uniformly mixing the raw materials of the abrasive layer to obtain mixed slurry;

B. pouring the mixed slurry obtained in the step A into a mould, pressing a non-woven fabric on the surface of the mixed slurry, and heating and curing;

C. uniformly mixing the raw materials of the transition layer, coating the raw materials on the non-woven fabric obtained in the step B, and heating and curing to obtain a semi-finished product;

D. and C, attaching the semi-finished product in the step C to a rubber plate to obtain the rubber plate.

According to the preparation method of the polishing pad, the mixed slurry for forming the abrasive layer is poured into the mold, and then the non-woven fabric is covered, so that the transition layer and the abrasive layer have good binding force and have a certain supporting effect on the abrasive layer, the problem that the binding strength is not high due to the fact that aggregate abrasives with large particle sizes directly contact with the slurry of the transition layer is solved, the semi-finished product is attached to the elastic substrate through the adhesive layer, and specifically, the adhesive layer can be made of double-sided adhesive.

The vacuum centrifugal stirring process is preferably selected during uniform mixing, so that centrifugal dispersion defoaming is performed in the stirring process, and large cavities are prevented from being generated in the curing process of the mixed slurry of the abrasive layer and the mixed slurry of the transition layer, so that the service life of the polishing pad is prolonged.

Drawings

FIG. 1 is a schematic diagram of the structure of the polishing pad of the present invention;

FIG. 2 is a schematic view of a polishing process of the polishing pad of the present invention;

in fig. 1: a-an abrasive layer, b-a non-woven fabric substrate, c-a transition layer, d-a rubber plate layer and e-a double-sided adhesive layer;

in fig. 2: 1-a stirring pump; 2-a water tank; 3, mounting a workbench; 4-a polishing pad; 5-lower working table.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting.

The percentages in the following examples are given by mass.

First, an embodiment of the polishing pad of the invention

Example 1

The polishing pad of the embodiment comprises an elastic substrate and a transition layer arranged on the elastic substrate, wherein the elastic substrate is connected with the transition layer through an adhesive layer, and a working layer of the polishing pad is compounded on the surface of the transition layer. Wherein the elastic substrate is a rubber plate; the bonding layer is specifically double-sided adhesive tape; the working layer is formed by compounding an abrasive layer on a non-woven fabric substrate, the abrasive layer is composed of a matrix and aggregate abrasives dispersed in the matrix, and the aggregate abrasives are diamond round grains obtained by agglomeration of nano diamonds.

The polishing pad of the embodiment has a structure as shown in fig. 1, and comprises a rubber sheet layer d, and a two-sided adhesive layer e, a transition layer c and a working layer formed by compounding an abrasive layer a on a non-woven fabric substrate b, which are compounded on the rubber sheet layer d in sequence. When the polishing pad is used, in order to firmly combine the polishing pad and the workbench, the polishing pad is fixed on the workbench by a double-sided adhesive layer e. Specifically, the method comprises the following steps:

the thickness of the working layer is 1.0-2.0mm, wherein the thickness of the non-woven fabric base material is 200-300 μm, and the raw material composition of the abrasive layer in the working layer is as follows: 15.8 percent of diamond round particles, KH-5502.1 percent of coupling agent, 10.5 percent of calcium carbonate, 10.5 percent of cerium oxide, 1.1 percent of fumed silica, 1.1 percent of sodium bicarbonate, 57.9 percent of resin bonding agent and 1.1 percent of wool, wherein the average particle size of the calcium carbonate is 1-3 mu m, the average particle size of the cerium oxide is 1 mu m, the average particle size of the fumed silica is 200-300nm, the average particle size of the sodium bicarbonate is 100-150 mu m, and the diameter of the wool is 14.5-15.5 mu m;

the thickness of the transition layer is 0.5-1.0mm, and the transition layer comprises the following raw materials: 55% of resin bonding agent, 30% of calcium carbonate and 15% of nano-alumina, wherein the average particle size of the calcium carbonate is 1-3 μm, and the average particle size of the nano-alumina is 100-200 nm;

the resin binder used in the abrasive layer and the transition layer comprises the following raw materials: epoxy resin E5145%, amine curing agent 3-aminomethyl trimethyl cyclohexylamine (IPDA) 50%, dispersant D3464% and accelerator A0-41%.

The thickness of the double-sided adhesive layer is 100-150 mu m, the thickness of the rubber plate layer is 1000-1200 mu m, and the Shore hardness of the rubber plate is A30-40.

The diamond round grains in the raw material of the abrasive layer are prepared by the method comprising the following steps:

1) taking the following raw materials in percentage by mass: adding 100mL of deionized water into 100mL of 40% of nano-diamond, 40% of surfactant AY-651% and 59% of silica sol, mixing, and ultrasonically dispersing for 30min to obtain 200mL of mixed solution, wherein the particle size of the nano-diamond is 20-30nm, the solid content of the silica sol is 40%, and the particle size is 10 nm;

2) pouring the mixed solution obtained in the step 1) into a high-speed shearing stirrer, adding 10L of isooctyl alcohol, stirring at the rotating speed of 5000r/min for 1h, and separating to obtain an aggregate abrasive precursor;

3) sintering the precursor of the aggregate abrasive at 650 ℃ for 3h, and sieving to obtain the aggregate abrasive with the average particle size of 1-3 μm.

Example 2

The polishing pad of this example has the same structure as the polishing pad of example 1, except that the composition of the raw materials is different, specifically, the composition of the raw materials of the polishing pad of this example is:

the raw material composition of the abrasive material layer is as follows: 10.5 percent of diamond round particles, 10.5 percent of coupling agent KH-5502.1 percent of calcium carbonate, 10.5 percent of cerium oxide, 1.1 percent of fumed silica, 1.1 percent of sodium bicarbonate, 63.2 percent of resin bonding agent and 1.1 percent of wool, wherein the average particle size of the calcium carbonate is 1-3 mu m, the average particle size of the cerium oxide is 1 mu m, the average particle size of the fumed silica is 200-300nm, the average particle size of the sodium bicarbonate is 100-150 mu m, and the diameter of the wool is 14.5-15.5 mu m;

the transition layer comprises the following raw materials: 55% of resin bonding agent, 30% of calcium carbonate and 15% of nano-alumina, wherein the average particle size of the calcium carbonate is 1-3 μm, and the average particle size of the nano-alumina is 100-200 nm;

the resin binder used in the abrasive layer and the transition layer comprises the following components: epoxy resin E5145%, amine curing agent 3-aminomethyl trimethyl cyclohexylamine (IPDA) 50%, dispersant D3464% and accelerator A0-41%.

1) taking the following raw materials in percentage by mass: adding 100mL of deionized water into 100mL of 55% of the nano-diamond, AY-651% of the surfactant and 44% of the silica sol, mixing, and ultrasonically dispersing for 30min to obtain 200mL of mixed solution, wherein the particle size of the nano-diamond is 20-30nm, the solid content of the silica sol is 40%, and the particle size is 10 nm;

2) pouring the mixed solution obtained in the step 1) into a high-speed shearing stirrer, adding 10L of isooctyl alcohol, stirring at the rotating speed of 5000r/min for 2 hours, and separating to obtain an aggregate abrasive precursor;

3) sintering the precursor of the aggregate abrasive at 550 ℃ for 2h, and sieving to obtain the aggregate abrasive with the average particle size of 1-3 mu m.

Example 3

the raw material composition of the abrasive material layer is as follows: 21.1 percent of diamond round particles, KH-5502.1 percent of coupling agent, 10.5 percent of calcium carbonate, 10.5 percent of cerium oxide, 1.1 percent of fumed silica, 1.1 percent of sodium bicarbonate, 52.6 percent of resin bonding agent and 1.1 percent of wool, wherein the average particle size of the calcium carbonate is 1-3 mu m, the average particle size of the cerium oxide is 1 mu m, the average particle size of the fumed silica is 200-300nm, the average particle size of the sodium bicarbonate is 100-150 mu m, and the diameter of the wool is 14.5-15.5 mu m;

1) taking the following raw materials in percentage by mass: adding 100mL of deionized water into 100mL of 45% of nano-diamond, AY-651% of surfactant and 54% of silica sol, mixing, and ultrasonically dispersing for 30min to obtain 200mL of mixed solution, wherein the particle size of the nano-diamond is 20-30nm, the solid content of the silica sol is 40%, and the particle size is 10 nm;

In other embodiments, the nano-abrasive particles in the aggregate abrasive preparation raw material may be one or more of nano-alumina and nano-silica, and any one of embodiments 1 to 3 may be adopted in the specific preparation method, which is not described again.

Second, the method of manufacturing the polishing pad of the present invention

Example 4

The method for preparing a polishing pad of this embodiment is described in relation to the preparation of the polishing pad of embodiment 1, and specifically includes 4 steps of preparing a mixed slurry, preparing a working layer, preparing a semi-finished product, and assembling a finished product, and the specific preparation method includes:

A. preparing mixed slurry: putting calcium carbonate, cerium oxide, fumed silica and sodium bicarbonate powder into a powder mixer for mixing powder for 1h, mixing diamond round particles with a coupling agent KH-550, putting into 1L of alcohol, stirring for 20min, putting into a drying oven for drying for 1h, adding the dried diamond round particles into the mixed powder, putting into the powder mixer again for mixing for 1h, adding wool and a resin bonding agent after mixing, putting into a centrifugal vacuum mixer, and stirring uniformly to obtain mixed slurry. The specific preparation process of the diamond round grains is shown in example 1.

B. Preparation of a working layer: and D, pouring the mixed slurry obtained in the step A into a circular groove of a polishing pad metal mold, flattening the slurry, covering a layer of non-woven fabric, placing the non-woven fabric into the mold, pressing the non-woven fabric into the mold, covering the non-woven fabric, placing the mold into a hardening furnace, heating the mold for 1 hour at the temperature of 80 ℃, heating the mold to 100 ℃, heating the mold for 2 hours, and cooling the mold to obtain a formed working layer.

C. Preparing a semi-finished product: uniformly stirring calcium carbonate, resin binder and nano-alumina, uniformly coating on the non-woven fabric of the formed working layer, putting into a hardening furnace, heating at 100 ℃ for 1h, and cooling to obtain a semi-finished product.

D. Assembling a finished product: and (3) pasting the double-sided adhesive tape on the two sides of the rubber plate, covering the semi-finished product on the rubber plate pasted with the double-sided adhesive tape by using a pasting machine, and cutting off the redundant part by using a laser cutting machine to obtain a finished product.

In other embodiments, the method of preparing the polishing pad is the same as that of embodiment 4, and thus, the description thereof is omitted.

Third, comparative example

The polishing pad of this comparative example differs from the polishing pad of example 1 only in that the abrasive layer thereof had a raw material composition of: 15.8% of diamond round grains, KH-5502.1% of coupling agent, 57.9% of resin bonding agent, 7.2% of calcium carbonate, 5% of cryolite, 9% of talcum powder, 1.5% of zinc stearate, 1.0% of salt and 0.5% of graphite, wherein the diamond round grains, the coupling agent and the resin bonding agent are the same as those in example 1. The polishing pad of this comparative example was prepared in the same manner as in example 4.

Fourth, example of experiment

The polishing treatment was performed on the workpiece using the polishing pads of example 1 and comparative example. Polishing process as shown in fig. 2, deionized water is driven by a stirring pump 1 and flows into a water tank 2 on an upper table 3, an arrow at the upper left of fig. 2 indicates the direction of deionized water flow into the table, and the water tank 2 flows into a polishing region between the upper table 3 and a lower table 5 through a water outlet. During polishing operation, the upper workbench 3 presses the workpiece onto the lower workbench 5 under the pressure F, the upper workbench 3 and the lower workbench 5 rotate oppositely, and the workpiece is polished under the cooperation of deionized water and the polishing pad 4.

Experimental example 1 polishing Performance test

In this example, the polishing pads of examples 1 to 3 were used and the glass was polished by the above-described process, and the results of the polishing properties are shown in Table 1.

TABLE 1 polishing Performance of polishing pads of examples 1-3

Note: the polishing removal amount is the polishing thinning amount of the product, and the flatness is the difference between the thickest thickness and the thinnest thickness of the polished product, which is the same as that in table 2.

The results in table 1 show that the polishing pad of the present invention can significantly improve the processing efficiency and the removal rate of polishing can reach 2.5 μm/min while ensuring that the roughness, flatness, yield and the like of the processed product meet the requirements.

Experimental example 2 Life comparison test with conventional polishing pad

In this example, glass was polished using the polishing pads of example 1 and the conventional polishing pad by the above-described process, and the results of comparing the life are shown in Table 2.

Table 2 comparison of polishing performance of example 1 with existing polishing pad

	Example 1	Comparative example
			Removal by polishing (micron)	25	25
Polishing time (seconds)	700	750
			Life span (sheet)	20000	16000
Cost of polishing a single piece of glass (Yuan)	0.8	0.95
			Roughness of processed product (nanometer)	0.7	0.7
Flatness of processed product (micron)	10	10
			Yield of processed product (%)	99.50	99.50

As can be seen from the data in Table 2, the polishing pad of the present invention can significantly improve the service life of the polishing pad, reduce the cost of polishing operation by about 16%, and have significant economic benefits, while ensuring that the roughness, flatness, and yield of the processed product are the same as those of the existing polishing pad.

Claims

1. The polishing pad is characterized in that an abrasive layer of the polishing pad is formed by solidifying the following raw materials in percentage by mass: 10-22% of aggregate abrasive, 1-5% of coupling agent, 45-65% of resin bonding agent, 10-20% of calcium carbonate, 10-20% of cerium oxide, 1-5% of fumed silica, 1-5% of sodium bicarbonate and 1-3% of filament fiber; the preparation method of the aggregate abrasive comprises the following steps:

wherein the solid content of the silica sol in the step 1) is 35-55%.

2. The polishing pad according to claim 1, wherein the aggregate abrasive is formed by aggregating nano abrasive grains and has a particle size of 1 to 3 μm.

3. The polishing pad of any one of claims 1-2, wherein the polishing pad comprises an elastic base and a transition layer disposed on the elastic base, the abrasive layer being composited on a nonwoven substrate to form a working layer, the working layer being composited on a surface of the transition layer.

4. The polishing pad of claim 3, wherein the working layer has a thickness of 1.0-2.0mm, the non-woven fabric substrate has a thickness of 200-300 μm, and the transition layer has a thickness of 0.5-1.0 mm.

5. The polishing pad of claim 4, wherein the transition layer is consolidated from the following raw materials in mass percent: 55-70% of resin binder, 20-30% of calcium carbonate and 10-20% of nano aluminum oxide.

6. The polishing pad of claim 3, wherein the transition layer is bonded to the resilient base by an adhesive layer.

7. The polishing pad of claim 6, wherein the adhesive layer has a thickness of 100-150 μm and the resilient substrate has a thickness of 1000-1200 μm.

8. The method of producing a polishing pad according to any one of claims 1 to 7, comprising the steps of:

9. The method of claim 8, wherein the blending step A is performed by vacuum centrifugal stirring.