US20170066099A1

US20170066099A1 - Abrasive pad and glass substrate abrading method

Info

Publication number: US20170066099A1
Application number: US15/123,444
Authority: US
Inventors: Yoko Nakamura
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2014-03-19
Filing date: 2015-03-17
Publication date: 2017-03-09
Also published as: EP3120379A1; JP6452295B2; KR20160135269A; JP2015178155A; WO2015142774A1; EP3120379A4; CN106104766A

Abstract

Problem: To provide an abrasive pad and abrading method using same that are capable of extending the life of the abrasive pad when applied to abrading the surface of glass substrates, and that can ensure abrading capability that is appropriate for abrading the surface of glass substrates. Resolution Means: An abrasive pad used for abrading the surface of a glass substrate, that includes a base material layer, and an abrasive layer provided on one side of the base material layer, the abrasive layer including a plurality of pillar shaped abrading portions arranged separated from each other on the base material layer, the abrading portions being made from abrasive material that includes polishing abrasive particles, a filler, and a binder resin, the polishing abrasive particles including abrasive particles and a glass matrix, and the filler including a first filler that fractures or drops out when the surface is being abraded, forming approximately spherical crown shaped recesses in the top face of the abrading portions.

Description

FIELD OF THE INVENTION

The present invention relates to an abrasive pad and a glass substrate abrading method.

BACKGROUND ART

The abrasive article disclosed in, for example, Patent Document 1 is a conventional abrasive pad. This abrasive article is configured from an abrasive material provided on one side of a backing member with a rectangular or other shape. Also, in the abrasive article disclosed in Patent Document 2, pointed protruding portions are formed on the base portion of the abrasive layer formed with abrasive material.

PRIOR ART DOCUMENTS

Patent Document 1: Japanese Unexamined Patent Application Publication (translation of PCT application) No. 2002-542057A
Patent Document 2: U.S. Unexamined Patent Application Publication No. US2011/0053460, Specification

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In order to improve the productivity of abrading glass substrates for industrial use, it is necessary to extend the life of abrasive articles. A conceivable measure to extend the useful life of an abrasive article is to increase the height of the protruding portions of the abrasive layer to increase the volume of the abrasive layer. However, increasing the height of the protruding portions may lead to the protruding portions becoming prone to collapsing due to the load during abrading. Also, the quantity of abrasive material required to form the protruding portion increases, which has the problem that the cost advantages are reduced.
Reducing the amount of abrasion of the abrasive layer is also conceivable in order to extend the life of the abrasive article. The amount of abrasion of the abrasive layer can conceivably be reduced by, for example, reducing the hardness of the abrasive layer to more easily release uneven load during abrasion. However, if the hardness of the abrasive layer is reduced, the amount of abrasion of the object to be abraded is significantly reduced, and it may not be possible to achieve sufficient abrasion.

Means to Solve the Problem

One aspect of the present invention relates to an abrasive pad used to abrade the surface of glass substrates, and includes a base material layer, and an abrasive layer provided on one side of the base material layer. In this aspect, the abrasive layer includes a plurality of pillar shaped abrading portions arranged separated from each other on the base material layer, the abrading portions are made from abrasive material that includes polishing abrasive particles, a filler, and a binder resin, the polishing abrasive particles include abrasive particles and a glass matrix, and the filler includes a first filler that fractures or drops out when the surface is being abraded, forming approximately spherical crown shaped recesses in the top face of the abrading portions.
According to this aspect, it is possible to extend the life of the abrasive pad when applied to abrading the surface of glass substrates, and ensure abrading capability that is appropriate for abrading the surface of glass substrates.
Also, another aspect of the present invention is a glass substrate abrading method using the above abrasive pad, that includes: securing a second surface side of the base material layer on a surface plate and bringing the abrasive layer into contact with an object to be abraded; and relatively rubbing the abrasive pad and the object to be abraded while introducing grinding fluid between the object to be abraded and the abrasive layer.
In the glass substrate abrading method according to this aspect, it is possible to stably carry out abrasion of the surface of the glass substrates over a long period of time because the above abrasive pads are used.

Effect of the Invention

According to the present invention, it is possible to extend the life of the abrasive pad when applied to abrading the surface of glass substrates, and ensure abrading capability that is appropriate for abrading the surface of glass substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an abrasive pad according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view illustrating the main parts of the abrasive pad illustrated in FIG. 1.

FIG. 3 is an enlarged side view illustrating the main parts of the abrasive pad illustrated in FIG. 1.

FIGS. 4A to 4E are perspective views illustrating modified examples of an abrading portion.

FIGS. 5A and 5B are side views illustrating abrading methods of an object to be abraded using the abrasive pad illustrated in FIG. 1.

FIGS. 6A-6D illustrate the results of observation of the abrading portion top face of samples of abrasive pads produced in the working examples and comparative examples, after the abrasion test, using a scanning electron microscope (SEM).

DETAILED DESCRIPTION

In the following, preferred embodiments of an abrasive pad and glass substrate abrading method according to the present invention are described in detail while referencing the figures.
FIG. 1 is a perspective view illustrating an abrasive pad according to an embodiment of the present invention. Moreover, FIG. 2 is an enlarged perspective view illustrating the main parts of the abrasive pad illustrated in FIG. 1, and FIG. 3 is an enlarged side view thereof. As illustrated in FIGS. 1 through 3, an abrasive pad 1 includes a base material layer 11 that is a support member for the pad, and an abrasive layer 12 provided on one side of the base material layer 11. Also, the abrasive layer 12 includes a plurality of pillar shaped abrading portions 15 arranged separated from each other on the base material layer 11.
Overall, the abrasive pad 1 has a disk shape with, for example, a diameter of from 30 mm to 1,500 mm. The shape of the abrasive pad according to the present invention is not limited to this, and the shape can be changed as appropriate in accordance with the abrading conditions, the abrading device, and so on.
The base material layer 11, for example, is configured with a thickness of around 1 mm so that the abrasive pad 1 has a certain amount of strength and flexibility. Also, the base material layer is configured from, for example, a base material 13 and an adhesive layer 14.
The base material 13 can be configured from, for example, polymer film, paper, vulcanized fiber, nonwoven fabric, woven fabric, and so on. Of these, preferably polymer film is used, and the polymer film can be, for example, polyethylene terephthalate film, polyester film, copolyester film, polyimide film, polyamide film, and so on.
The adhesive layer 14 is a layer that joins the base material 13 and the abrading portions 15 to provide an integrated abrasive pad. The adhesive layer 14 can be formed from, for example, hot melt adhesive, thermosetting adhesive, or the like. The hot melt adhesive can be, for example, a hot melt adhesive that includes a thermoplastic resin such as ethylene acrylic acid copolymer (EAA), ethylene vinyl acetate copolymer (EVA), and so on. Also, the thermosetting adhesive can be, for example, a thermosetting adhesive that includes a thermosetting resin such as epoxy resin, phenol resin, urea resin, and so on and a curing agent.
The abrading portions 15 are arranged on the base material layer 11 separated from each other, and are configured from abrasive materials including polishing abrasive particles, filler, and binder resin.
The polishing abrasive particles include abrasive particles and a glass matrix that are dispersed within the abrading portions 15 and retained by the binder resin. Also, in the polishing abrasive particles, the abrasive particles are retained dispersed within the glass matrix.
The average particle size of the polishing abrasive particles may be, for example, 10 μm or more, and preferably 25 μm or more. Also, the average particle size of the polishing abrasive particles may be, for example, 200 μm or less, and preferably 100 μm or less. In this patent specification, the average particle size of the polishing abrasive particles indicates the median diameter measured using a laser diffraction/scattering type particle size distribution measuring device LA-920 (manufactured by Horiba Ltd. (Kyoto City, Kyoto-fu)).
The quantity of polishing abrasive particles in the abrasive material may be, for example, 0.5 mass % or more, preferably 1 mass % or more, and more preferably 2 mass % or more of the total mass of the abrasive material. Also, the quantity of polishing abrasive particles in the abrasive material may be, for example, 60 mass % or less, preferably 30 mass % or less, and more preferably 10 mass % or less of the total mass of the abrasive material.
The abrasive particles may be, for example, diamond abrasive particles, aluminum oxide particles, cerium oxide particles, cubic boron nitride (cBN) particles, and so on, and of these preferably diamond abrasive particles are used.
The average particle size of the abrasive particles is, for example, 0.5 μm or more, and preferably 2 μm or more. Also, the average particle size of the abrasive particles is, for example, 100 μm or less, and preferably 50 μm or less. In this patent specification, the average particle size of the abrasive particles indicates the median diameter measured using a laser diffraction/scattering type particle size distribution measuring device LA-920 (manufactured by Horiba Ltd. (Kyoto City, Kyoto-fu)).
The quantity of abrasive particles in the polishing abrasive particles relative to the total volume of the polishing abrasive particles may be, for example, 20 vol % or more, and preferably 30 vol % or more. The quantity of abrasive particles in the polishing abrasive particles relative to the total volume of the polishing abrasive particles may be, for example, 80 vol % or less, and preferably 70 vol % or less.
The quantity of glass matrix in the polishing abrasive particles relative to the total volume of the polishing abrasive particles may be, for example, 20 vol % or more, and preferably 30 vol % or more. The quantity of glass matrix in the polishing abrasive particles relative to the total volume of the polishing abrasive particles may be, for example, 80 vol % or less, and preferably 70 vol % or less.
The binder resin is formed from a binder precursor. The binder precursor contains a resin in an uncured or unpolymerized state, and when the abrading portions 15 are fabricated, the resin in the binder precursor is polymerized or cured, forming the binder resin. The binder precursor may be, for example, a photocurable resin or a thermosetting resin, and of these, preferably a photocurable resin is used. For example, an acrylic resin or the like can be used as the photocurable resin, and for example an epoxy resin, phenol resin, or the like can be used as the thermosetting resin.
The filler is used to control the rate of erosion of the abrading portions 15. In present embodiment, the abrasive material includes a filler (hereafter referred to as the “first filler”) that fractures or drops off when abrading the surface of the glass substrates and forms substantially spherical crown shaped recesses in the top face 16 of the abrading portions 15.
In the present embodiment, by forming substantially spherical crown shaped recesses in the top face 16, it is considered that it is possible to extend the life of the abrasive pad while maintaining the abrasion capability appropriate for abrading the surfaces of glass substrates. The reason for this is not necessarily clear, but it is considered that by using the filler (in other words, the substantially spherical filler) capable of forming the substantially spherical crown shaped recesses due to fracture or dropping off, the wear of the abrading portions 15 is reduced, and by forming recesses in the top face 16 that contacts the object to be abraded, the contact area between the object to be abraded and the abrading portions 15 is reduced, so an effective load on the portion being abraded is applied and sufficient abrasion capability is ensured.
Preferably, the first filler is selected from glass balloons and glass beads, from the viewpoint of exhibiting the above effect more significantly. If the first filler is glass balloons or glass beads, when abrading the surface of glass substrates, effective fracture or dropping out occurs on the top face 16 of the abrading portions 15, and substantially spherical crown shaped recesses are effectively formed.
Glass balloons are hollow particles made from glass, and fine glass hollow powder may also be used.
For example, glass balloons with a compressive strength of 1 or more can be preferably used as the glass balloons. Glass balloons having this compressive strength do not easily fracture during the process of manufacturing the abrasive pads, so it is possible to more reliably obtain the effect as described above.
The true density of the glass balloons may be, for example, 0.1 g/cm³or more, and preferably 0.2 g/cm³or more. The true density of the glass balloons may be, for example, 1 g/cm³or less, and preferably 0.6 g/cm³or less.
The average particle size of the glass balloons is, for example, from 10 to 70 μm. Here, the average particle size of the glass balloons indicates the median diameter measured by laser diffraction/scattering type particle size distribution measuring device Partica LA-950 V2 (manufactured by Horiba Ltd. (Kyoto City, Kyoto-fu)). The median diameter of the glass balloon is the particle diameter at which, when the glass balloons are divided into two according to particle diameter, the glass balloons having a smaller particle diameter and the glass balloons having a larger diameter have equal volume.
In order to obtain abrading portions 15 with low wear and particularly excellent abrading capability, preferably, the average particle size of the glass balloons is 40 μm or more, and more preferably 50 μm or more. If the average particle size of the glass balloons is 40 μm or more, the ratio G of the amount of wear of the abrading portions A (cm³) to the amount of abrasion of the object to be abraded B (cm³) (the G ratio, B/A) is significantly increased, and it is possible to obtain an abrasive pad that can exhibit good abrasion capability over a long period of time. Also, the average particle size of the glass balloons may be 70 μm or less, and preferably 65 μm or less.
Glass beads are solid particles made from glass, and the average particle size of glass beads is, for example, from 5 to 100 μm. Here, the average particle size of the glass beads indicates the median diameter measured by laser diffraction/scattering type particle size distribution measuring device Partica LA-950 V2 (manufactured by Horiba Ltd. (Kyoto City, Kyoto-fu)). The median diameter of the glass beads refers the particle diameter at which, when the glass beads are divided into two according to particle diameter, the glass beads having a smaller particle diameter and the glass beads having a larger diameter have equal volume.
In order to obtain abrading portions 15 with low wear and particularly excellent abrading capability, preferably the average particle size of the glass beads is 5 μm or more, and more preferably 10 μm or more. If the average particle size of the glass beads is 10 μm or more, the ratio G of the amount of wear of the abrading portions A (cm³) to the amount of abrasion of the object to be abraded B (cm³), (the G ratio, B/A) is significantly increased, and it is possible to obtain an abrasive pad that can exhibit good abrasion capability over a long period of time. Also, the average particle size of the glass beads may be 100 μm or less, and preferably 50 μm or less.
The true density of the glass beads may be, for example, 1.5 g/cm or more, and preferably 2 g/cm³or more. Also, the true density of the glass beads may be, for example, 4 g/cm³or less, and preferably 3.5 g/cm³or less.
In the present embodiment, apart from the first filler, the abrasive material may include a commonly known filler (hereafter referred to as “second filler”).
Examples of the second filler include, for example: metal carbonates (e.g. calcium carbonate (chalk, calcite, marl, travertine, marble, and limestone), calcium magnesium carbonate, sodium carbonate, magnesium carbonate, and the like); silica (glass fibers, and the like); silicates (talc, clay (montmorillonite), feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate, lithium silicate, potassium silicate, and the like); metal sulfates (calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate, and the like), gypsum, vermiculite, wood flour, aluminum trihydrate, carbon black, metal oxides (calcium oxide (lime), aluminum oxide, tin oxide (e.g. stannic oxide), titanium dioxide, and the like), and metal sulfites (calcium sulfite, and the like); thermoplastic particles (polycarbonate, polyetherimide, polyester, polyethylene, polysulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymer, polypropylene, acetal polymers, polyurethanes, nylon particles); thermosetting particles (phenolic bubbles, phenolic beads, polyurethane foam particles, and the like); and the like.
Also, halide salts can be used as the second filler. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, and magnesium chloride. Also, a metal filler can be used, for example, tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium. Also, sulfur, organic sulfur compounds, graphite, and metal sulfides can be used.
Preferably, the quantity of filler in the abrasive material is 10 vol % or more, and more preferably is 20 vol % or more relative to the total volume of the abrasive material. If the quantity of the filler is 10 vol % or more, structural changes of the abrading portions 15 due to curing shrinkage of the binder resin are sufficiently minimized. Also, preferably the quantity of filler in the abrasive material is 70 vol % or less, and more preferably is 50 vol % or less relative to the total volume of the abrasive material. If the quantity of filler exceeds 70 vol %, it may be difficult to form the abrading portions 15.
In the present embodiment, the first filler can be used on its own as the filler, or the first filler and the second filler can be used in combination.
The quantity of the first filler relative to the total quantity of filler in the abrasive material may be, for example, 10 vol % or more, preferably 20 vol % or more, and more preferably 30 vol % or more. The quantities of first filler and second filler can be adjusted as appropriate in accordance with the ratio of both the desired quantity of wear of the abrading portions 15 per unit time and the quantity of abrasion of the object to be abraded per unit time (the G ratio) or the like.
For example, when the first filler is selected from glass balloons and glass beads, when the content of the first filler is large, both the quantity of wear of the abrading portions 15 per unit time and the quantity of abrasion of the object to be abraded per unit time tend to become small, but the rate of reduction of wear is larger, so the ratio of the two (the G ratio) tends to increase. In other words, due to the first filler, the quantity of abrasion of the object to be abraded per unit of quantity of the abrading portion increases, but the abrading time to achieve a specific quantity of abrasion tends to increase. On the other hand, if for example, a silicate mineral is used as the filler, the quantity of abrasion of the object to be abraded per unit time is increased by increasing the quantity of filler, but at the same time the quantity of wear of the abrading portions 15 per unit time tends to increase.
Therefore, by using glass balloons and/or glass beads as the first filler, and using a silicate mineral as the second filler, it is possible to increase the quantity of abrasion per unit time while maintaining the abrasion ratio (in other words the G ratio) per unit time of the abrading portions to a certain extent, so it is possible to reduce the abrasion time.
In other words, in the present embodiment, it is possible to manufacture the abrasive pad 1 by adjusting the proportions of the first filler and the second filler so that it is possible to achieve the desired quantity of wear of the abrading portions 15 per unit time and the quantity of abrasion of the object to be abraded per unit time, in other words, in order to achieve the desired abrasion ratio (G ratio) and abrasion time.
Next, the structure of the abrading portions 15 that form the abrasive layer 12 is explained.
As illustrated in FIGS. 2 and 3, the abrasive layer 12 is configured having a plurality of pillar shaped abrading portions 15. The abrading portion 15 has a top face 16, and the abrading surface of the abrasive pad is formed by each of the top faces 16 of the plurality of abrading portions 15.
The abrading portions 15 are arranged in a matrix shape on the base material layer 11 such that the density is from 3 to 7 per 1 cm², for example. Each abrading portion 15 has an approximately cuboid shape and an approximately square shape in plan view.
The area of the top face 16 of the abrading portion 15 may be, for example, 4 mm²or more, and preferably 5 mm²or more. Also, the area of the top face 16 is, for example, 100 mm²or less, and preferably 50 mm²or less. In the abrading portion 15 having the top face 16 within this ideal range of area, it is possible to more significantly obtain the effect of reducing the quantity of wear due to the recesses formed by the first filler having an average particle size within the above ideal range.
There is no particular limitation on the height of the abrading portions 15, but it can be 20% or more, or it can be 30% or more of the length of the short side on the bottom surface of the abrading portion 15. Also, there is no particular limitation on the upper limit to the height of the abrading portions 15, but in order to ensure sufficient strength in the sliding direction of the abrading portions 15, preferably the upper limit is 270% or less, and the height may be 150% or less.
Specifically, the height of the abrading portions 15 can be, for example, 0.01 mm or more, or can be 1 mm or more. Also, the height of the abrading portion may be 10 mm or less, or it may be 7 mm or less.
The three-dimensional shape of the abrading portions 15 should be a pillar shape having a top face. FIGS. 4A to 4E are perspective views illustrating modified examples of the abrading portions 15. The abrading portion 15 a which is one of the modified examples has an approximately triangular pillar shape, and the top face 16 a thereof has an approximately triangular shape. Also the abrading portion 15 b which is one of the modified examples has an approximately hexagonal pillar shape, and the top face 16 b thereof has an approximately hexagonal shape. Also the abrading portion 15 c which is one of the modified examples has an approximately circular pillar shape, and the top face 16 c thereof has an approximately circular shape. Also the abrading portion 15 d which is one of the modified examples has an approximately rectangular parallelepiped pillar shape, and the top face 16 d thereof has an approximately rectangular shape. Also the abrading portion 15 e which is one of the modified examples has an approximately square frustum of a pyramid shape, and the top face 16 e thereof has an approximately square shape. The abrasive layer 12 may have one of these modified examples as the abrading portions 15, and may have a plurality of these modified examples. The three-dimensional shape of the abrading portions 15 can be selected as appropriate in accordance with the form of abrading.
Adjacent abrading portions 15 are partitioned from each other by grooves 17 provided at predetermined intervals on the base material layer 11. The width of the groove 17 is, for example, appropriately selected from within a range of about 0.5 mm to 5 mm. If the width of the groove 17 is too narrow, there is a possibility that the flexibility of the abrasive pad 1 will be reduced. Moreover, it is also conceivable that abrading scraps, which are generated when abrading an object to be abraded, could easily clog the groove 17, resulting in a drop in abrading efficiency. On the other hand, if the width of the groove 17 is too wide, the area of the top faces 16 of the abrading portions 15 per unit area of the abrading surface of the abrasive layer 12 will be reduced, so the load applied per unit area of the top face 16 will increase, the abrading portions 15 will easily wear, and as a result, the life of the abrasive pad 1 may be reduced. Accordingly, by establishing the width of the groove 17 within the above range, the abrading efficiency of the abrasive pad 1 can be maintained and the useful life thereof can be ensured. Concerning the abrasive pad, the bottom face of the groove is may formed on the based material layer 11 and the abrading portion 15 may be settled independently each other on the base material layer 11. As the abrading portion 15 is settled independently each other on the base material layer 11, the abrasive pad which has not only the rigid abrading portion 15 but also has a flexible performance as whole is gotten.
Transfer methods, for example, can be used as the method of forming the abrasive layer 12 having the abrading portions 15 as described above. In the transfer method, a transfer mold with a three-dimensional shape corresponding to the abrading portions 15, for example, is produced, and the transfer mold is filled with a slurry that includes the polishing abrasive particles, the filler, and the binder precursor as precursors of the abrasive material that forms the abrading portions 15. Next, a film that will form the base material layer 11 is laminated onto the transfer mold filled with the slurry. Next, the slurry is cured through photoirradiation or the like, and when the film is peeled from the transfer mold, an abrasive pad 1 having the abrasive layer 12 formed on the base material layer 11 is obtained.
Also, in the method as described above, an adhesive layer made from adhesive is provided on the surface of the film that will become the base material layer 11 on the side where the abrading portions 15 are formed, and after the film is peeled from the transfer mold, the adhesive layer is cured so that the film and the abrading portions 15 can be firmly bonded.
FIGS. 5A and 5B illustrate methods of abrading a glass substrate using the abrasive pad 1. FIG. 5A illustrates an example of one-sided abrading, illustrating the abrading method for abrading one side of the object to be abraded (glass substrate) P1. In this example, the abrasive pad 1 is fixed to a surface of a grinder (surface plate) 22 via an elastic body layer 21. The grinder 22 is rotated while introducing a grinding fluid between the object to be abraded P1 and the abrasive pad 1, and the surface of the object to be abraded P1 is abraded while applying a load. A retainer 23 that holds the object to be abraded P1 may also be rotated in the same direction as the grinder 22 or in an opposite direction thereof.
FIG. 5B illustrates an example of two-sided abrading, illustrating the abrading method for abrading both sides of the object to be abraded (glass substrate) P2 at the same time. In this example, the respective abrasive pads 1 are secured to the surface of top and bottom grinders 24 with an elastic body layer 21 interposed between each abrasive pad 1 and grinder 24, and the object to be abraded P2 that is held by a retainer 25 is set between the grinders 24. The grinders 24 are rotated while supplying grinding fluid between the object to be abraded P2 and the abrasive pads 1, and both surfaces of the object to be abraded p2 are abraded while a load is applied. At this time, rotation of the grinders 24 in mutually opposite directions is preferred.
In the above examples, attachment of the abrasive pads 1 to the grinders 22 and 24 can be done using, for example, a pressure sensitive type adhesive. Examples of such an adhesive include latex crepe, rosin, polyacrylate ester, acrylic polymers, polybutyl acrylate, polyacrylate esters, vinyl ethers (e.g. polyvinyl n-butyl ether), alkyd adhesives, rubber adhesives (e.g. natural rubber, synthetic rubber, and chlorinated rubber), and mixtures thereof.
Also, for example, polyurethane foam, rubber, elastomer, rubber foam, or the like can be used as the elastic body layer (flexible layer) 21. By interposing this type of elastic body layer 21, the tracking capability of the shape of the abrasive pad 1 with regards to the grinders 22 and 24 can be improved. Note that the elastic body layer 21 may also be provided in advance on a second surface side (opposite surface side of the abrasive layer 12) of the base material layer 11 in the abrasive pad 1. Moreover, the flexible layer 21 does not necessarily have to be provided, and the abrasive pad 1 may be directly attached to the grinders 22 and 24.
Examples of grinding fluids include water-based solutions containing one or more types of the following: amines, mineral oil, kerosene, mineral spirits, water-soluble emulsions, polyethyleneimine, ethylene glycol, monoethanolamine, diethanolamine, triethanolamine, propylene glycol, amine borate, boric acid, amine carboxylate, pine oil, indole, thioamine salt, amides, hexahydro-1,3,5-triethyltriazine, carboxylic acid, sodium 2-mercaptobenzothiazole, isopropanolamine, triethylenediamine tetraacetic acid, propylene glycol methyl ether, benzotriazole, sodium 2-pyridinethiol-1-oxide, and hexylene glycol. The grinding fluid may also contain corrosion inhibitors, bactericides, stabilizers, surfactants, emulsifiers, or the like.
In abrading the object to be abraded P as described above, on the top faces 16 of the abrading portions 15 that form the abrading surface of the abrasive layer 12 of the abrasive pad 1, the first filler fractures and drops off due to the load during abrasion, and the substantially spherical crown shaped recesses are formed. In this way, in the above method, wear of the abrading portions 15 is reduced, and it is possible to stably abrade the objects to be abraded P over a long period of time.
A preferred embodiment of the present invention was described above, but the present invention is not limited to the abovementioned embodiment.
For example, in one aspect of the present invention, the method of manufacturing the abrasive pad can be determined by providing the first filler in a blending proportion determined based on the quantity of wear of the abrading portions per unit time and the quantity of abrasion of the object to be abraded per unit time. Also, in one aspect of the present invention, the life of the abrasive pad can be extended by the method of replacing the filler of the abrasive pad with the first filler as described above.

EXAMPLE

The present invention is described more specifically below using working examples, but the present invention is not limited to the working examples.
For the working examples and the comparative examples, abrasive pad samples were produced by a method that includes the following processes (1) through (6).
(1) Filling a polypropylene transfer mold with a curable diamond slurry;
(2) Applying a primer on an ethylene-acrylic acid (EAA) copolymer layer that was provided on one side of a polyethylene terephthalate (PET) film, and laminating it onto the transfer mold;
(3) Curing the curable diamond slurry;
(4) Peeling the transfer mold, to obtain a PET film on which a plurality of abrading portions are formed;
(5) Curing the formed abrading portions; and
(6) Melting the EAA at or above the EAA softening temperature, to firmly bond the abrading portions and the PET film.
The curable diamond slurry in the above process (1) includes polishing abrasive particles, filler, and binder precursor, and the composition thereof was as described in the item “Slurry composition” in Table 1 below. Also, primer N200 (a mixed solution that includes 1 to 5 mass % each of polymethylene polyphenylene isocyanate and chlorinated rubber (manufactured by Sumitomo 3M Limited, Shinagawa-ku, Tokyo)) was used as the primer in process (2). Also, the curable diamond slurry was cured by ultraviolet light irradiation in process (3). Also, in process (5), the abrading portions were cured by oven curing at 90° C. for 36 hours. Also, in process (6), the EAA was melted by heating to 130° C. for two hours, and the abrading portions and the PET film were joined by cooling to room temperature.
Also, abrasion tests were performed on the abrasive pad samples produced by a method that included the following processes (a) through (e).
(a) The abrasive pad samples were bonded to a polycarbonate board of a thickness of 0.8 mm using a pressure sensitive adhesive, and 100 mm diameter circular disks were produced.
(b) A glass substrate was prepared as the object to be abraded by processing to a 150 mm diameter.
(c) The object to be abraded was bonded to an abrasion surface plate with wax.
(d) Abrasion tests were carried out using an abrasion device EcoMet 250 (manufactured by Buehler) under the following conditions.

Rotation speed of upper surface plate: 60 rpm
Rotation speed of lower surface plate: 450 rpm
Load: 120 N
Grinding fluid: 5% aqueous solution of alkaline water soluble grinding fluid
Rate of dropping grinding fluid: 42 cc/minute
Test duration: 20 minutes×4 times

(e) After the test, the G ratio was calculated from the following equation.
G ratio=Total quantity of abrasion of the glass substrate (cm³)/total quantity of wear of the abrading portions (cm³).

Working Example 1

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 1, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Glass balloons 1 (3M™ Glass Bubbles S22 (Sumitomo 3M Limited, Shinagawa-ku, Tokyo)) with average an particle size of 35 μm, compressive strength of 2.8 MPa, true density of 0.22, and relative permittivity of 1.4 (indicated in the table as “GB1”) were used as the filler. The results of the abrasion tests are as listed in Table 2.
In the table, “SR368D” indicates acrylic resin (Sartomer USA, LLC, West Chester, Pa.), “Solsperse 32000” indicates dispersing agent (Lubrizol Japan Limited, Meguro-ku, Tokyo), “IR819” indicates photoinitiator (BASF), and “PWA3” indicates plate-like crystal alumina (Fujimi Incorporated, Kiyosu City, Aichi Prefecture). Also, “agglomerate” in the table indicates polishing abrasive particles in which diamond abrasive particles are dispersed in a glass matrix.

Working Examples 2 through 5

Abrasive pad samples were produced the same as for Working Example 1 except that instead of glass balloons 1, glass balloons 2 to 5 (indicated as “GB2”, “GB3”, “GB4”, “GB5” in the table) were used as the filler, and abrasion tests were carried out on the abrasive pad samples obtained. The compound amount of the glass balloons was adjusted so that the content of filler in the abrading portions (volume %) was the same as for Working Example 1. The results of the abrasion tests are as listed in Table 2.
Glass balloons 2 (GB2): 3M™ Glass Bubbles S38 (Sumitomo 3M Limited, Shinagawa-ku, Tokyo), median diameter 40 μm, compressive strength 28.0 MPa, true density 0.38, relative permittivity 1.6
Glass balloons 3 (GB3): 3M™ Glass Bubbles K37 (Sumitomo 3M Limited, Shinagawa-ku, Tokyo), median diameter 45 μm, compressive strength 21.0 MPa, true density 0.37, relative permittivity 1.6
Glass balloons 4 (GB4): 3M™ Glass Bubbles K25 (Sumitomo 3M Limited, Shinagawa-ku, Tokyo), median diameter 55 μm, compressive strength 5.2 MPa, true density 0.25, relative permittivity 1.4
Glass balloons 5 (GB5): 3M™ Glass Bubbles K20 (Sumitomo 3M Limited, Shinagawa-ku, Tokyo), median diameter 60 μm, compressive strength 3.5 MPa, true density 0.15, relative permittivity 1.3

Working Example 6

Abrasive pad samples were produced the same as for Working Example 1 except that the following glass beads 1 (indicated as “GD1” in the table) were used instead of the glass balloons 1 as the filler, and abrasion tests were carried out on the abrasive pads obtained. The compound amount of the glass beads was adjusted so that the content of filler in the abrading portions (volume %) was the same as for Working Example 1. The results of the abrasion tests are as listed in Table 2.
Glass beads 1 (GD1): Average particle size 10 μm, true density 2.4

Comparative Example 1

Abrasive pad samples were produced in the same manner as Working Example 1, except that instead of using glass balloons 1 as the filler, wollastonite (needle-shaped filler, average particle size 9 μm, true density 2.9, Mohs hardness 4.5) (indicated as “W1” in the table) was used, and the abrasion test was carried out on the abrasive pads obtained. The compound amount of the wollastonite was adjusted so that the content of filler in the abrading portions (volume %) was the same as for Working Example 1. The results of the abrasion tests are as listed in Table 2.

TABLE 1

	COMPARATIVE	Volume
EXAMPLES	EXAMPLE	percentage

	1	2	3	4	5	6	1	of each
Filler	GB1	GB2	GB3	GB4	GB5	GD1	W1	component

Slurry composition (mass %)	(vol %)

SR368D	37.00	37.00	37.00	37.00	37.00	37.00	37.00	58.8
Solsperse32000	0.62	0.62	0.62	0.62	0.62	0.62	0.62	1.2
IR819	0.37	0.37	0.37	0.37	0.37	0.37	0.37	0.6
PWA3	2.90	2.90	2.90	2.90	2.90	2.90	2.90	1.4
Polishing	4.00	4.00	4.00	4.00	4.00	4.00	4.00	3.2
abrasive
particles
Filler	4.18	7.22	7.03	4.75	3.80	45.60	55.10	35.0

	TABLE 2

		COMPARATIVE
	EXAMPLES	EXAMPLE

	1	2	3	4	5	6	1

Total quantity of abrasion of	544	2096	2652	2344	2316	2752	6420
the object to be abraded
(cm³)
Total quantity of wear of the	230	229	322	174	139	201	900
abrading portions
(cm³)
G-ratio	2	9	8	13	17	14	7

As shown in Table 2, the quantity of wear of the abrading portions was significantly reduced in Working Examples 1 through 6 compared with Comparative Example 1. Also, the G ratio of Working Examples 2 through 6 which had a predetermined average particle size was increased compared with Comparative Example 1, so it can be seen that more efficient abrasion work is enabled.

Working Examples 7 through 11

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 3, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Glass balloons 5 (GB5) and wollastonite (W1) were used as the filler. The compound amount of the filler was adjusted so that the content of filler (GB5 and W1) in the abrading portions (volume %) was the same in all Working Examples 7 through 11. Also, the compound amount of the glass balloons 5 expressed as the quantity of glass balloons 5 as a percentage of the total volume of the filler (indicated as GB percentage) was adjusted to 25 vol % (Working Example 7), 35 vol % (Working Example 8), 50 vol % (Working Example 9), 75 vol % (Working Example 10), and 100 vol % (Working Example 11). The results of the abrasion tests are as listed in Table 4.

Comparative Example 2

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 3, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Wollastonite (W1) was used as the filler. Also, the compound amount of the filler was adjusted so that the content of filler in the abrading portions (volume %) was the same as for Working Examples 7 through 11. The results of the abrasion tests are as listed in Table 4.

	TABLE 3

	COMPARATIVE
	EXAMPLE	EXAMPLES

	2	7	8	9	10	11

GB percentage	0	25	35	50	75	100
(vol %)

Slurry composition (mass %)

SR368D	37.00	37.00	37.00	37.00	37.00	37.00
Salspare 32000	0.62	0.62	0.62	0.62	0.62	0.62
IR819	0.37	0.37	0.37	0.37	0.37	0.37
PWA3	2.90	2.90	2.90	2.90	2.90	2.90
Polishing	4.00	4.00	4.00	4.00	4.00	4.00
abrasive
particles

Filler	GB5	0.00	0.94	1.32	1.89	2.83	3.77
	W1	54.73	41.05	35.57	27.36	13.68	0.00

	TABLE 4

	COMPARATIVE
	EXAMPLE	EXAMPLES

	2	7	8	9	10	11

Total quantity of	6420	5152	4724	3376	1588	2316
abrasion of the
object to be
abraded (cm³)
Total quantity of	901	641	473	184	115	139
wear of the
abrading portions
(cm³)
G-ratio	7	8	10	18	14	17

Working Examples 12 through 16

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 5, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Glass balloons 4 (GB4) and wollastonite (W1) were used as the filler. The compound amount of the filler was adjusted so that the content of filler (GB4 and W1) in the abrading portions (volume %) was the same in all Working Examples 12 through 16. Also, the compound amount of the glass balloons 4 expressed as the quantity of glass balloons 4 as a percentage of the total volume of the filler (indicated as GB percentage in the table) was adjusted to 25 vol % (Working Example 12), 45 vol % (Working Example 13), 50 vol % (Working Example 14), 75 vol % (Working Example 15), and 100 vol % (Working Example 16). The results of the abrasion tests are as listed in Table 6.

Comparative Example 3

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 5, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Wollastonite (W1) was used as the filler. Also, the compound amount of the filler was adjusted so that the content of filler in the abrading portions (volume %) was the same as for Working Examples 12 through 16. The results of the abrasion tests are as listed in Table 6.

	TABLE 5

	COMPARATIVE
	EXAMPLE	EXAMPLES

	3	12	13	14	15	16

GB percentage	0	25	45	50	75	100
(vol %)

Slurry composition (mass %)

Filler	GB4	0.00	1.18	2.12	2.36	3.54	4.72
	W1	54.73	41.05	30.10	27.36	13.68	0.00

	TABLE 6

	COMPARATIVE
	EXAMPLE	EXAMPLES

	3	12	13	14	15	16

Total quantity of	6420	4684	3828	3984	2896	2344
abrasion of the
object to be
abraded (cm³)
Total quantity of	901	487	310	504	143	174
wear of the
abrading portions
(cm³)
G-ratio	7	10	12	8	20	13

Examples 17 through 20

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 7, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Glass balloons 2 (GB2) and wollastonite (W1) were used as the filler. The compound amount of the filler was adjusted so that the content of filler (GB2 and W1) in the abrading portions (volume %) was the same in all Working Examples 17 through 20. Also, the compound amount of the glass balloons 2 expressed as the quantity of glass balloons 2 as a percentage of the total volume of the filler (indicated as “GB percentage” in the table) was adjusted to 25 vol % (Working Example 17), 50 vol % (Working Example 18), 75 vol % (Working Example 19), and 100 vol % (Working Example 20). The results of the abrasion tests are as listed in Table 8.

Comparative Example 4

Abrasive pad samples were produced by the above method using the curable diamond slurry with the slurry composition shown in Table 7, and the abrasive pad samples obtained were subjected to abrasion tests by the method as described above. Wollastonite (W1) was used as the filler. Also, the compound amount of the filler was adjusted so that the content of filler in the abrading portions (volume %) was the same as for Working Examples 17 through 20. The results of the abrasion tests are as listed in Table 8.

	TABLE 7

	COMPARATIVE
	EXAMPLE	EXAMPLES

	4	17	18	19	20

GB percentage (vol %)

0

25

50

75

100

Slurry composition (mass %)

SR368D	37.00	37.00	37.00	37.00	37.00
Salspare 32000	0.62	0.62	0.62	0.62	0.62
IR819	0.37	0.37	0.37	0.37	0.37
PWA3	2.90	2.90	2.90	2.90	2.90
Polishing abrasive	4.00	4.00	4.00	4.00	4.00
particles

Filler	GB2	0.00	1.79	3.59	5.38	7.17
	W1	54.73	41.05	27.36	13.68	0.00

	TABLE 8

	COMPARATIVE
	EXAMPLE	EXAMPLES

	4	17	18	19	20

Total quantity of	6420	4588	3712	2864	2096
abrasion of the object
to be abraded (cm³)
Total quantity of wear of	901	461	421	448	229
the abrading portions
(cm³)
G-ratio	7	10	9	6	9

FIGS. 6A to 6D illustrate the results of observation using a scanning electron microscope (SEM) of the abrading portion top face of samples of abrasive pad produced in the working examples and comparative example, after the abrasion test. FIG. 6A illustrates the results for the abrasive pad sample of Working Example 4, FIG. 6B illustrates the results for the abrasive pad sample of Working Example 5, FIG. 6C illustrates the results for the abrasive pad sample of Working Example 6, and FIG. 6D illustrates the results for the abrasive pad sample of Comparative Example 1.
In the SEM images illustrated in FIGS. 6A and 6B, the substantially spherical crown shaped recesses formed by the glass balloons fracturing or dropping out was seen. In the SEM image illustrated in FIG. 6C, the substantially spherical crown shaped recesses formed by the glass beads dropping out was seen. On the other hand, in the SEM image illustrated in FIG. 6D, this type of recess was not seen.

REFERENCE NUMERALS

1 . . . Abrasive pad
11 . . . Base material layer
12 . . . Abrasive layer
13 . . . Base material
14 . . . Adhesive layer
15 . . . Abrading portion
16 . . . Top face
17 . . . Groove
21 . . . Elastic body layer
22, 24 . . . Grinder
23, 25 . . . Retainer

Claims

1. An abrasive pad used for abrading the surface of a glass substrate, comprising:

a base material layer; and an abrasive layer provided on one side of the base material layer,

the abrasive layer including a plurality of pillar shaped abrading portions arranged separated from each other on the base material layer,

the abrading portions being made from abrasive material that includes polishing abrasive particles, a filler, and a binder resin,

the polishing abrasive particles including abrasive particles and a glass matrix, and

the filler including a first filler that fractures or drops out when the surface is being abraded, forming substantially spherical crown shaped recesses in the top face of the abrading portions.

2. The abrasive pad according to claim 1, wherein the first filler includes glass balloons with an average particle size of 40 μm or larger.

3. The abrasive pad according to claim 1, wherein the first filler includes glass beads with an average particle size of 10 μm or larger.

4. The abrasive pad according to claim 1, wherein the filler includes a second filler made from a silicate mineral.

5. The abrasive pad according to claim 1, wherein the abrading portions have top faces of 4 to 100 mm².

6. The abrasive pad according to claim 1, wherein a content of the filler as a percentage of the total volume of the abrasive material is from 10 to 50 vol %.

7. A glass substrate abrading method using the abrasive pad described in claim 1, comprising:

securing a second surface side of the base material layer on a surface plate and bringing the abrasive layer into contact with an object to be abraded; and relatively rubbing the abrasive pad and the object to be abraded while introducing grinding fluid between the object to be abraded and the abrasive layer.