KR100494605B1 - Abrasive Article for Providing a Clear Surface Finish on Glass - Google Patents

Abstract

An abrasive article is provided comprising at least one three-dimensional abrasive coating comprising a backing material and diamond particles dispersed in a binder bonded to the backing material surface and comprising a cured binder precursor comprising a urethane acrylate oligomer. The abrasive article has a rapid glass material removal capability with reduced surface finish, indicated by a reduced Ra value using the RPP method.

Description

Abrasive article for providing a clear surface finish on glass

The present invention relates to an abrasive article for glass polishing and a method of using the same.

Articles made of glass are widely found in homes, offices and factories in the form of lenses, prisms, mirrors, CRT screens and other items. Many of these glass surfaces are used as optical components where an optically transparent and visible surface is free of flaws and / or defects. If there are flaws, defects and fine scratches, they hinder the optical transparency of the glass article. In some cases, these flaws, defects, and / or minor scratches may impair the ability to see through the glass accurately. Thus, the glass surface is required to be essentially free of any flaws, defects and / or scratches.

Many glass components are curved or have a radius associated with them. These radii and bends are generally produced during the glass forming process. However, as a result of the glass forming process, flaws such as mold lines, rough surfaces, small dots and other small defects may be present on the glass outer surface. These flaws and / or defects, however small, tend to affect the optical transparency of the glass. Polishing means have been widely used to remove these defects and / or flaws. Polishing means typically fall into three main classes: grinding, fine polishing and polishing.

In the polishing step, the glass components are roughened with abrasive tools to make the desired bend or radius more complete and to remove casting flaws. Typically such abrasives comprise ultrahard abrasive particles such as diamond, tungsten carbide or cubic boron nitride. The glass surface obtained from this usually has the required roughness. However, abrasives in this rough polishing step are subject to rough scratches on the glass surface so that the resulting glass surface is not precise enough or smooth enough to be directly polished in an optically transparent state.

The second step is called the fine polishing step. The purpose of the fine polishing step is to refine the coarse scratches generated during the coarse polishing step. In general, the fine polishing step removes deep scratches resulting from rough polishing and provides a substantially smooth but not polished surface. In addition, the fine polishing step should remove enough coarse scratches so that the glass surface can be polished to become an optically clear surface. If all the rough scratches are not removed in the fine polishing step, it may be very difficult to remove these scratches in the polishing step to obtain an optically clear surface.

This fine polishing step is typically done with a loose abrasive slurry. The loose abrasive slurry contains a plurality of abrasive particles dispersed in a liquid medium such as water. The most common abrasive particles used in loose slurry are pumice, silicon carbide, aluminum oxide and the like. The loose abrasive slurry may optionally include other additives such as dispersants, lubricants, antifoams and the like. In most cases, loose abrasive slurry is pumped to exist between the glass intermediate and the lap pad. The wrap pad can be made of any material such as rubber, foam, polymeric material, metal, steel, and the like. Typically the glass intermediate and the wrap pad will be rotated relative to each other. This fine polishing step includes one or more steps in each step that gradually create a more sophisticated surface finish on the glass intermediate. Finer surface finish can be achieved by various methods, including using softer abrasive particles, smaller abrasive particles, softer wrap pad material, and / or using different mechanical conditions. The surface finish of the optical component after this fine polishing step typically has an Rtm value in excess of 0.06 to 0.13 micrometers (Ra) and (or) about 0.3 to 0.90 micrometers.

The roughness of the surface is generally due to scratches or scratched patterns, which may or may not be visible to the naked eye. The scratched pattern can be defined as a series of peaks and valleys along the surface. Rtm and Ra are conventional units of roughness used in the polishing industry, but the exact measurement process may vary depending on the type of equipment used to evaluate the surface roughness. As used herein, Rtm and Ra are measured based on a measurement method according to Rank Taylor Hobson (Leicester, UK) profilometer, available under the trade name SURTRONIC 3.

Ra is defined as the average roughness height value of the arithmetic mean of the degree to which the surface roughness profile deviates from the mean line on the surface. Measure at both points above and below the average line on the surface within the evaluation length determined by the Rank Taylor Hobson instrument. Ra and Rtm (defined below) are measured with a profilometer probe, a needle with a diamond with a radius of 5 micrometers at the end, and the results are reported in micrometers (μm). Sum these deviations and divide by the number of measurements to find the average. In general, the lower the Ra value, the smoother the surface finish.

Rt is defined as the maximum hill-gol height. Rtm is the mean value of the maximum hill-bone height in each length assessment, measured in five consecutive length assessments. In general, the smaller the Rtm value, the smoother the surface finish. Some deviations in Ra and Rtm values may, but are not necessarily, be measured with other commercially available profilometers on the same glass finish surface.

The third step of the overall process is the polishing step, which creates an optically transparent surface on the glass article. Typically, the loose slurry provides a means to create an optically clear surface that is essentially free of any flaws, defects and / or fine scratches, so in most cases this polishing step is done with a loose abrasive slurry. The loose abrasive slurry typically contains cerium oxide abrasive particles dispersed in water.

Although loose polishing slurries are widely used in fine polishing and polishing steps to provide an optically transparent surface finish on glass articles, loose polishing slurries have many disadvantages associated with them. These disadvantages include the inconvenience of handling the large volume of slurry required, the need for agitation to prevent the abrasive particles from settling and to make the concentration of abrasive particles uniform at the polishing interface, to manufacture, handle and Included is the need for additional equipment to process or recover and recycle. In addition, the slurry itself needs to be periodically analyzed to ensure its quality and dispersion stability, which requires additional man-hour costs. Moreover, pump heads, valves, feed lines, abrasive wraps, and other parts of the slurry feeder in contact with the loose abrasive slurry eventually become undesirable. Furthermore, loose abrasive slurries are viscous liquids that are difficult to pop out and contain, so the steps for using the slurry are often very sloppy.

Naturally, attempts have been made and some success has been made to replace the loose abrasive slurry fine polishing and polishing steps with wrapping coated abrasives. In general, the lapping coated abrasive includes a backing material bonded to the abrasive coating. This abrasive coating comprises a plurality of abrasive particles dispersed in a binder. For example, US Pat. Nos. 4,255,164 (Butzke et al.), 4,576,612 (Shukla et al.), 4,733,502 (Braun) and European Patent Application No. 650,803 Articles and polishing steps are disclosed. Other documents that disclose lapping coated abrasive articles include US Pat. Nos. 4,644,703 (Kaczmarek et al.), 4,773,920 (Chasman et al.) And 5,014,468 (Ravipati et al.). Included. However, lapping coated abrasives did not completely replace the loose abrasive slurry. In some instances, the lapping coated abrasives are optically transparent and do not provide a surface that is essentially free of flaws, defects, and / or fine scratches. In other cases a long time is required to polish the glass article with the lapping coated abrasive, which makes it advantageous in terms of cost to use a loose abrasive slurry. Similar to some cases, the life of the wrapped coated abrasive is not long enough to justify the high cost associated with the wrapped coated abrasive as compared to the loose abrasive slurry. Thus, in some cases lapping coated abrasives are not as economically desirable as loose abrasive slurries.

What is needed in the glass industry is that the glass surface can be efficiently and economically polished in a timely manner in order to obtain optical transparency essentially free of defects, scratches and / or scratches on the glass surface without the disadvantages associated with loose abrasive slurries. Abrasive products.

Brief Description of the Invention

One aspect of the present invention relates to an abrasive article for polishing a glass intermediate. The abrasive article comprises a backing and at least one three-dimensional abrasive coating comprising diamond particles dispersed in a binder bonded to the backing surface.

It is preferred that the at least one three-dimensional abrasive coating comprises a plurality of abrasive composites. The plurality of abrasive composites may be composites having a clear shape, composites having irregular shapes, or composites having a clear shape, including substantially cut pyramid shapes with flat top faces. Preferably, the composite having a definite shape has a bottom with a surface area of 60% or less than the top, more preferably 40% or less and most preferably 20% or less.

Preferably, the binder is formed from a binder precursor containing ethylenically unsaturated resins such as acrylate resins. More preferably, the binder precursor comprises urethane acrylate oligomers, ethylenically unsaturated monomers and mixtures thereof. The ethylenically unsaturated monomer is preferably selected from the group consisting of monofunctional acrylate monomers, difunctional acrylate monomers, trifunctional acrylate monomers and mixtures thereof. Preferably, the binder precursor is about 30 to 70 parts by weight of urethane acrylate monomer and about 70 to 30 parts by weight of ethylenically unsaturated monomer, more preferably about 34 to 65 parts by weight of urethane acrylate oligomer and about 46 to 54 parts by weight Ethylenically unsaturated monomers, most preferably about 50 parts by weight of urethane acrylate oligomer and about 50 parts by weight of ethylenically unsaturated monomer.

The abrasive grains preferably comprise diamond abrasive grains. Optionally, the diamond particles can be mixed with other non-diamond hard abrasive particles, soft inorganic abrasive particles and mixtures thereof. Preferably the average size of the abrasive particles is about 0.01 to 300 micrometers, more preferably about 5 to 150 micrometers and most preferably about 9 to 80 micrometers.

In one embodiment of the present invention, the abrasive article may reduce an initial Ra of about 1.2 μm or more on a glass test blank to a final Ra of about 0.7 μm or less using an RPP method having a polishing time interval of about 25 seconds. Can be. Preferably, the diamond particles included in the abrasive article have an average size of about 74 micrometers.

In another embodiment of the present invention, the abrasive article can reduce an initial Ra of about 0.2 μm or greater on the test glass blank to a final Ra of about 0.12 μm or less using an RPP method having a polishing time interval of about 25 seconds. Preferably, the diamond particles included in the abrasive article have an average size of about 30 to 45 micrometers.

In another embodiment of the present invention, the abrasive article can reduce the initial Ra of about 0.05 μm or more on the test glass blank to a final Ra of about 0.05 μm or less using an RPP method having a polishing time interval of about 25 seconds. Preferably, the diamond particles included in the abrasive article have an average size of about 9 to 15 micrometers.

These abrasive articles can be provided continuously in a glass polishing system to polish the glass intermediate to have a very sophisticated surface finish.

RPP test method

The RPP method uses a "Buehler Ecomet 4" variable speed grinder-polisher equipped with a "Buehler Ecomet 2" power head (these are commercially available from Bueller Industries Limited, Lake Bluff, Illinois). The test is performed using a motor speed of 500 rpm with a force of 50 pounds corresponding to a pressure of about 7.1 psi (about 50 kPa) over the surface area of the test glass blank.

A flat round test glass blank, 7.62 cm (3 inches) in diameter and about 1.0 cm thick, is prepared (commercially available from Corning Glass Company under the trade name CORNING # 9061). The glass material is fixed in the grinder-polisher power head. The test glass blank rotates the fixed power head clockwise at 35 rpm, while the grinder-polisher's 12-inch aluminum platform rotates counterclockwise.

The extruded slab stock foam urethane backing material was die cut to a circular diameter of 20.3 cm (8.0 inches) and had a Shore A hardness of about 90 durometer. Attach directly to the pad with a pressure sensitive adhesive. The urethane backing pad is attached to an extruded slab open cell, a soft foam pad about 30 mm thick. The pad assembly is fixed on the grinder / polisher's aluminum platform. Tap water is sprayed onto the abrasive at a flow rate of about 3 liters / minute to lubricate between the abrasive surface and the test glass blank.

In order to provide a substantially similar initial surface finish on the test glass blanks (ie, prior to polishing with the abrasive), each test glass blank was named 3M (St. Paul, Minn.) Under the trade name "3M Flexible Diamond M125". It is worn with a metal bonded diamond abrasive article which is commercially available from. These diamond particles have an average particle size of about 125 micrometers.

Initial surface finish on test glass blanks is evaluated with a diamond needle profilometer commercially available from Taylor Hobson (Leicester, UK) under the name SURTRONIC 3 (112 / 1518-822323). Also record the initial weight of the test glass blank. Initial surface finish or Ra values for evaluating abrasive articles according to the invention typically fall into three categories: at least about 1.2 μm, at least about 0.2 μm and at least about 0.05 μm.

The test glass blanks are polished using the grinder / polisher described above. The polishing time interval of the grinder / polisher is set to 15 seconds or 10 seconds. However, the actual contact time between the abrasive article and the test glass blank surface may be greater than the set time since the grinder / polisher does not start counting until the abrasive article on the test glass blank surface has stabilized. That is, the abrasive article on the glass surface may bounce or run and the grinder / polisher begins to time at a point where the contact between the abrasive article and the glass surface is substantially constant. Thus, the actual polishing time interval, ie the contact between the abrasive article and the glass surface, is less than about 25 seconds. After polishing, the final surface finish and final weight are recorded respectively. The weight change of the test glass blank during the polishing time (“Ｘ” seconds) is referred to as “cutting speed” and is given in grams (glass material removed / “Ｘ” seconds).

The actual time (speed) required to polish the glass intermediate to a certain Ra value according to the method described above depends on the polishing apparatus used, the backing pad under the abrasive, the polishing rotational speed, the size of the surface area being polished, and the contact. It will be appreciated that this will vary depending on many factors such as pressure, abrasive grain size, initial state of the surface being polished and the like. Each step of the RPP method described above simply provides one baseline performance characteristic that can be used to compare the abrasive article and method according to the present invention with conventional glass polishing techniques.

Another aspect of the invention provides a method of contacting a glass intermediate having an initial Ra value with an abrasive as described above, supplying liquid to the contact between the glass intermediate and the abrasive, glass intermediate and polishing A method of polishing a glass intermediate by rubbing the articles against each other and reducing the initial Ra to the final Ra.

In one embodiment, the method is an abrasive article capable of removing about 0.75 g of glass material from a test glass blank using an RPP method with a polishing time interval of about 25 seconds and a glass medium having an initial Ra value of at least about 1.2 μm. Contacting the product, where initial Ra is reduced to a final Ra of about 0.7 μm or less. Preferably, the abrasive article comprises diamond particles dispersed in the binder. More preferably, the abrasive particles have an average size of about 74 μm.

In another embodiment, the method has an abrasive article capable of removing about 0.2 g of glass material from a test glass blank using an RPP method having a polishing time interval of about 25 seconds and an initial Ra value of about 0.2 μm or greater. Contacting the glass intermediate, wherein the initial Ra is reduced to a final Ra of about 0.05 μm or less. Preferably, the abrasive article comprises diamond particles dispersed in the binder. More preferably, the abrasive particles have an average size of about 30 to 45 μm.

In another embodiment, an abrasive article capable of removing about 0.02 g of glass material from a test glass blank using an RPP method having a polishing time interval of about 25 seconds and a glass intermediate having an initial Ra value of about 0.05 μm or greater. In which the initial Ra is reduced to a final Ra of about 0.05 μm or less. Preferably, the abrasive article comprises diamond particles dispersed in the binder. More preferably, the abrasive particles have an average size of about 9-15 μm.

The abrasive articles of the present invention used to polish glass surfaces provide a smooth surface in surprisingly relatively short time. While not wishing to be bound by any theory, it is believed that the chemical properties of the binder impart desirable properties to the abrasive article. In particular, the chemical nature of this binder is believed to provide a tough, durable and long lasting medium for firmly supporting abrasive particles over the life of the abrasive article. The chemical nature of this binder is particularly effective when used with diamond abrasive particles. Strong and durable binders are desirable because diamond abrasive particles last significantly longer than most conventional abrasive particles. Thus, the combination of urethane acrylate oligomers, or mixtures of urethane acrylate oligomers and acrylate monomers with diamond abrasive particles, provides a long lasting and durable abrasive coating. It is assumed that the chemical properties of the abrasive particles and the binder provide a combination with a synergistic effect such that the use of the abrasive article according to the invention has improved glass polishing results.

As used herein, the clear shape refers to the shape of the abrasive composite that is molded by curing the binder precursor while the precursor is molded on the backing material and filled in a cavity on the surface of the production tool. This abrasive composite has a three-dimensional shape, defined by faces with relatively smooth surfaces, which have sharp edges with clear edge lengths, with distinct drawbacks defined by the intersection of several faces. Bounded and combined by The abrasive composites of the present invention are described as structured in the sense that a number of such abrasive shapes are disposed. The abrasive composite may also have an irregular shape, which means that the faces or boundaries forming the abrasive composite, as used herein, are broken and unclear. In abrasive composites having irregular shapes, the polishing slurry is first molded into the desired shape and / or pattern. Once the polishing slurry is molded, the binder precursor in the polishing slurry is cured or solidified. Generally there is a time interval between molding and curing the binder precursor. During this time interval, the polishing slurry can flow and / or deform, thereby deforming the shaped shape. The abrasive composites are also sized, pitched or shaped within one single abrasive article as described in WO 95/07797 published March 23, 1995 and WO 95/22436 published August 24, 1995. Can be different.

Boundary as used herein refers to the exposed surfaces and edges of each composite that bound and define the actual three-dimensional shape of each abrasive composite. These boundaries are readily visible and discernible when viewing the cross section of the abrasive article of the present invention under a microscope. These boundaries allow one abrasive composite to be distinguished and distinguished from the other even if the composites are adjacent to each other along a common border at the bottom. For abrasive composites with a definite shape, the boundaries and edges are sharp and distinct. In contrast, in abrasive composites that do not have a definite shape, the boundaries and edges are not apparent (ie, the abrasive composite sags before hardening is complete). These abrasive composites, whether clear or irregular, may be of any geometry defined by substantially distinct and identifiable boundaries, where the clear geometry is a cubic, prismatic, conical, or block-shaped truncated cone. , Pyramidal, truncated pyramidal, cylindrical, hemispherical, and the like.

As used herein, texture refers to a polishing layer having any of the three-dimensional composites described above, whether each three-dimensional composite has a definite or irregular shape. These grains may all be formed from a plurality of abrasive composites having substantially the same geometry (ie, the grains may be regular). Similarly, the texture can be any pattern, with different geometries per composite.

Optically transparent surfaces refer to surfaces that are essentially free of any flaws, defects and / or microscopic scratches visible to the naked eye.

1 is a plan view of one preferred abrasive article according to the present invention.

2 is an enlarged cross-sectional view of a cross section taken along line 2-2 of the abrasive article shown in FIG.

3 is a plan view of another preferred abrasive article according to the present invention.

4 is an enlarged cross-sectional view of a cross section taken along the line 4-4 of the abrasive article shown in FIG.

The present invention provides a method for finely polishing (preferably polishing) a glass intermediate with an abrasive article comprising at least one three-dimensional abrasive coating comprising a backing material and preferably diamond particles dispersed in a binder bonded to the backing surface. It relates to methods and things. The abrasive coating comprises a binder formed from a binder precursor and a plurality of abrasive particles, preferably diamond abrasive particles.

The end use of the glass may be a home or commercial environment. Glass can be used for decorative or architectural purposes. The glass has one or more surfaces to be polished. The glass may be relatively flat or have a contour associated therewith. These contours may be curved or corner shaped. Examples of glass intermediates include optical components such as lenses, prisms, mirrors, cathode ray tube (CRT) screens, and the like. CRT screens are widely found on display surfaces used in devices such as television sets, computer monitors, computer terminals, and the like. The size of the CRT screen (measured diagonally) ranges from about 10 cm (4 inches) to about 100 cm (40 inches) or more. The CRT screen has an outer surface that is convex and has a radius of curvature. The abrasive article of the present invention polishes this CRT screen during polishing.

end. bookbinder

The binder is formed from a binder precursor. The binder precursor includes a resin in an uncured or nonpolymerized state. During manufacture of the abrasive article, the resin in the binder precursor is polymerized or cured to form a binder. The binder precursor may include condensation curable resins, addition polymerizable resins, free radical curable resins, and / or combinations and mixtures thereof.

Preferred binder precursors are resins which can polymerize via a free radical mechanism. The polymerization process is initiated by exposing the binder precursor with an appropriate catalyst to an energy source such as thermal or radiant energy. Examples of radiant energy include electron beams, ultraviolet rays or visible light.

Examples of free radical curable resins include acrylated urethanes, acrylated epoxy, acrylated polyesters, ethylenically unsaturated compounds, amino resin derivatives having at least one pendant acrylate group, and isocyanurate having at least one pendant acrylate group. Derivatives, isocyanate derivatives having one or more pendant acrylate groups and mixtures and combinations thereof. The term acrylate encompasses acrylates and methacrylates.

One preferred binder precursor of the present invention comprises a urethane acrylate oligomer or a mixture of urethane acrylate oligomers and ethylenically unsaturated monomers. Preferred ethylenically unsaturated monomers are monofunctional acrylate monomers, difunctional acrylate monomers, trifunctional acrylate monomers or combinations thereof. While not wishing to be bound by any theory, it is believed that imparting desirable properties to the abrasive article is the chemical nature of the binder derived from the binder precursors described above. In particular, the binder's chemistry provides a tough, durable and long lasting medium for firmly supporting abrasive particles over the life of the abrasive article. The binder's chemistry is particularly effective when used with diamond abrasive particles because diamond abrasive particles last significantly longer than most conventional abrasive particles. In order to fully utilize the long life associated with diamond particles, a strong and durable binder is required. Accordingly, the combination of urethane acrylate oligomer or a mixture of urethane acrylate oligomer and acrylate monomer with diamond abrasive particles provides a long lasting and durable abrasive coating.

It is also an acrylated ester of an isocyanate expanded polyester or polyether with an acrylated urethane hydroxy end group. These may be aliphatic or aromatic. Examples of commercially available acrylated urethanes include those manufactured by Henkel Corporation, Hoboken, NJ, under the trade name PHOTOMER (such as PHOTOMER 6010), and EBECRYL 220 (molecular weight 1000, manufactured by Yousvy Radcure Inc., Smirna, GA). 6-functional aromatic urethane acrylate), EBECRYL 284 (aliphatic urethane diacrylate with molecular weight 1200 diluted with 1,6-hexanediol diacrylate), EBECRYL 4827 (aromatic urethane diacrylate with molecular weight 1600), EBECRYL 4830 ( Aliphatic urethane diacrylate with molecular weight 1200 diluted with tetraethylene glycol diacrylate), EBECRYL 6602 (trifunctional aromatic urethane acrylate with molecular weight 1300 diluted with trimethylolpropane ethoxy triacrylate) and EBECRYL 840 (molecular weight of 1000 Aliphatic urethane diacrylate), West, PA Located in the master Sartomer Company, Inc. manufactured by SARTOMER (e.g., SARTOMER 9635, 9645, 9655, 963-B80, 966-A80, etc.), and UVITHANE (e.g., UVITHANE 782) a molteon International Inc., located in Chicago, IL Manufacturing belongs.

The ethylenically unsaturated monomers or oligomers or acrylate monomers or oligomers may be mono-, di-, tri- or tetra- or more functional groups. The term acrylate includes acrylates and methacrylates. Ethylenically unsaturated binder precursors include monomers and polymeric compounds containing carbon, hydrogen and oxygen and optionally nitrogen and halogen atoms. Oxygen or nitrogen atoms or both are generally present in ether, ester, urethane, amide and urea groups. The ethylenically unsaturated compound preferably has a molecular weight of less than 4000, preferably a compound containing an aliphatic monohydroxy group or an aliphatic polyhydroxy group and acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, male Esters made from reaction with unsaturated carboxylic acids such as acids and the like. Representative examples of ethylenically unsaturated monomers include methyl methacrylate, ethyl methacrylate, styrene, divinylbenzene, hydroxy ethyl acrylate, hydroxy ethyl methacrylate, hydroxy propyl acrylate, hydroxy propyl methacrylate, Hydroxy butyl acrylate, hydroxy butyl methacrylate, vinyl toluene, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol diacrylate, triethylene glycol diacrylate, trimethylol Propane triacrylate, glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate and pentaerythritol tetramethacrylate. Other ethylenically unsaturated resins include amides of monoallyl, polyallyl and polymetall esters with carboxylic acids such as diallyl phthalate, diallyl adipate and N, N-diallyl adiamide. Other nitrogenous compounds include tris (2-acryl-oxyethyl) isocyanurate, 1,3,5-tri (2-methylacryloxyethyl) -s-triazine, acrylamide, methylacrylamide, N- Methyl-acrylamide, N, N-dimethylacrylamide, N-vinyl-pyrrolidone, N-vinyl-piperidone and CMD 3700 available from Radcure Specialities. Examples of ethylenically unsaturated diluents or monomers can be found in US Pat. Nos. 5,236,472 (Kirk et al.) And 5,580,647 (Larson et al.).

In general, the weight ratio between these acrylate monomers depends on the weight percentage of diamond abrasive particles required for the final abrasive article. Typically, however, these acrylate monomers have a range of about 5 to 95 parts by weight of urethane acrylate oligomer relative to about 5 to 95 parts by weight of ethylenically unsaturated monomer. Preferably, these acrylate monomers are from about 30 to 70 parts by weight of urethane acrylate oligomers, and more preferably from about 46 to 54 parts by weight of ethylenically unsaturated monomers, relative to about 30 to 70 parts by weight of ethylenically unsaturated monomers. To 65 parts by weight of urethane acrylate oligomer, most preferably 50 parts by weight of urethane acrylate oligomer relative to 50 parts by weight of ethylenically unsaturated monomer.

Further information regarding other potentially useful binders and binder precursors is disclosed in pending patent application 08 / 694,014, filed Aug. 8, 1996 (Application No. 08 / 557,727, filed Nov. 11, 1995). Bruxvoort et al.) And US Pat. No. 4,773,920 (partial application of Chasman et al.).

An acrylated epoxy is a diacrylate ester of an epoxy resin, such as a diacrylate ester of a bisphenol A epoxy resin. Examples of commercially available acrylated epoxies include CMD 3500, CMD 3600 and CMD 3700 available from Radcure Specialty Corporation and CN103, CN104, CN111, CN112 and CN114 available from Sartomer, West Chester, PA. .

Examples of polyester acrylates include Photomer 5007 and Photomer 5018, available from Henkel Corporation, Hoboken, NJ.

Amino resins have one or more pendant alpha, beta-unsaturated carbonyl groups per molecule or oligomer. These unsaturated carbonyl groups can be groups of the acrylate, methacrylate or acrylamide type. Examples of such materials include N- (hydroxymethyl) -acrylamide, N, N'-oxydimethylenebisacrylamide, o- and p-acrylamidomethylated phenols, acrylamidomethylated phenolic novolacs novolac) and combinations thereof. These materials are described in more detail in US Pat. Nos. 4,903,440 (Ralson et al.) And 5,236,472 (Kirk et al.).

Isocyanurate derivatives having one or more pendant acrylate groups and isocyanate derivatives having one or more pendant acrylate groups are described in more detail in US Pat. No. 4,652,27 (Boettcher et al.). Preferred isocyanurate materials are triacrylates of tris (hydroxy ethyl) isocyanurate.

Depending on how the free radically curable resin is cured or polymerized, the binder precursor may further comprise a curing agent (also known as a catalyst or initiator). Exposure of the curing agent to a suitable energy source generates a free radical source that initiates the polymerization reaction.

The binder precursor may comprise an epoxy resin. Epoxy resins have an oxirane and are polymerized by ring opening. Such epoxy resins include epoxy resins of monomers and epoxy resins of polymers. Some examples of preferred epoxy resins include 2,2-bis [4- (2,3-epoxypropoxy) -phenyl) propane, diglycidyl ether of bisphenol, EPON 828, EPON 1004 and EPON 1001F from Shell Chemicals. And DER-331, DER-332 and DER-334 available from Dow Chemical. Other suitable epoxy resins include alicyclic epoxy, glycidyl ethers of phenol formaldehyde novolacs (eg, DEN-431 and DEN-428 available from Dow Chemical). Mixtures of free radical curable resins and epoxy resins are described in more detail in US Pat. Nos. 4,751,138 (Tumey et al.) And 5,256,170 (Harmer et al.).

In some cases it may be desirable to form the abrasive article using make and size coating. In these abrasive article embodiments, a make coat is applied to the backing material, abrasive particles are applied to the backing material, the make coat is exposed to constant conditions to at least partially cure the make coat, and over the abrasive particles and the make coat. Apply size coat. This component is then exposed to conditions sufficient to cure the make and size coating. Any presize and supersize coatings may be applied as known in the art.

I. Backing material

The backing material functions to support an abrasive composite formed from a combination of a binder and abrasive particles. The backing material useful in the present invention should be able to adhere to the binder after exposing the binder precursor to curing conditions, and the flexibility after said exposure such that the object used in the method of the present invention matches the contour, radius and irregularities of the surface in the glass. It is desirable to have this.

In many glass polishing applications, the backing material needs to be strong and durable so that the abrasive article can last long. In addition, for some polishing applications, the backing material needs to be strong and flexible so that the abrasive article can be uniformly matched to the glass intermediate. This is usually the case when the glass intermediate has some shape or contour associated with it. The backing material may be a polymeric film, paper, cured fiber, processed nonwoven backing or processed cloth backing to impart this strength and consistency. Examples of the polymer film include a polyester film, a polyester copolymer film, a polyimide film, a polyamide film, and the like. Including paper, the nonwoven can be saturated with a thermoset or thermoplastic material to impart the required properties.

One preferred backing material is a processed cloth backing material. The fabric may be a J weight, X weight, Y weight or M weight cloth. The fibers or yarns of the cloth may be selected from the group consisting of polyester, nylon, rayon, cotton, glass fibers and combinations thereof. The fabric may be a knit or woven fabric (eg, trills, twills or sateen weaves), may be stitched, or may be a weft insertion cloth. The greige cloth can be woven, singed desizing or any conventional processing on the greige cloth. It is desirable to fabricate the fabric with a polymeric material to seal the fabric and protect the fibers of the fabric. Such processing may be associated with one or more of presize, saturant or backsize processing. One such processing involves first applying a presized coat followed by a backsized coat. Alternatively, the saturant coating is followed by the back size coating. In general, the front face of the backing material is preferably relatively smooth. In addition, since the glass polishing is usually performed in the presence of water, the treatment coating (s) should make the backing material waterproof. In addition, the treatment coating (s) should ensure that the backing material has sufficient strength and flexibility. One preferred backing agent is a crosslinked urethane acrylate oligomer mixed with acrylate monomer resin. It is within the scope of the present invention that the chemical action of the fabric treating agent is substantially the same as or similar to that of the binder. The chemical action of the fabric treating agent may further include fillers, dyes, pigments, wetting agents, binders, plasticizers and the like.

Other treatment coatings include thermosets and thermoplastics. Examples of typical and preferred thermosetting resins include phenolic resins, amino resins, urethane resins, epoxy resins, ethylenically unsaturated resins, acrylated isocyanurate resins, urea-formaldehyde resins, isocyanurate resins, acrylated urethane resins, Acrylated epoxy resins, bismaleimide resins and mixtures thereof. Examples of preferred thermoplastic resins are polyamide resins (such as nylon), polyester resins and polyurethane resins (including polyurethane-urea resins). One preferred thermoplastic resin is a polyurethane obtained from the reaction product of polyester polyols and isocyanates.

All. Abrasive particles

The abrasive article according to the invention also comprises a plurality of abrasive particles. The term "abrasive particles" includes a single abrasive particle that is joined together by a binder to form an abrasive agglomerate or composite. Abrasive lumps are described in more detail in US Pat. Nos. 4,311,489, 4,652,275, and 4,799,939. The abrasive particles may further comprise a binder or a surface treatment agent or coating such as a metal or ceramic coating.

Abrasive particles useful in the present invention are preferably about 0.01 micrometers (small particles) to 300 micrometers (large particles), more preferably about 5 micrometers to 150 micrometers, and most preferably about 9 to 80 micrometers. Has an average particle size. It is preferable that the abrasive particles have a Morse hardness of 8 or more, more preferably 9 or more. Examples of such abrasive particles include fused aluminum oxide, ceramic aluminum oxide, heat treated aluminum oxide, silicon carbide, alumina zirconia, iron oxide, diamond (natural and synthetic), cerium oxide, cubic boron nitride, garnet and combinations thereof. Included.

In the case of glass polishing, an abrasive article using diamond abrasive particles is preferred. These diamond abrasive particles may be natural or artificially synthesized diamonds. With regard to synthetic diamonds, the particles can be considered as "resin bonded diamonds", "saw blade grade diamonds" or "metal bonded diamonds". Diamonds can have the shape of a block or needle like shape associated with them. Diamond particles may include surface coatings such as metal coatings (eg nickel, aluminum, copper, etc.), inorganic coatings (eg silica) or organic coatings. The abrasive article of the present invention may comprise a mixture of diamond and other abrasive particles.

The three-dimensional abrasive coating may comprise about 0.1 to 90 parts by weight of abrasive particles and about 10 to 99.9 parts by weight of the binder. However, due to the costs associated with diamond abrasive particles, the abrasive coating preferably includes about 0.1 to 50 parts by weight of abrasive particles and about 50 to 99.9 parts by weight of the binder. More preferably, the abrasive coating comprises about 1 to 30 parts by weight of abrasive particles and about 70 to 90 parts by weight binder, most preferably about 3 to 25 parts by weight abrasive particles and about 75 to 97 parts by weight binder.

la. additive

Abrasive coatings of the present invention include abrasive particle surface modification additives, binders, fillers, expanding agents, fibers, antistatic agents, curing agents, suspending agents, photosensitizers, lubricants, wetting agents, surfactants, pigments, dyes, ultraviolet stabilizers, and It may further include any additives such as antioxidants. These materials are used in amounts necessary to give the desired properties.

Binder

The binder can provide a binding bridge between the binder and the abrasive particles. The binder may also provide a binding bridge between the binder and the filler particles. Examples of binders include silanes, titanates and zircoaluminates. There are various ways of introducing the binder. For example, the binder can be added directly to the binder precursor. The abrasive coating may comprise about 0 to 30% by weight of binder, preferably about 0.1 to 25% by weight of binder. In addition, a binder may be applied to the filler particle surface. In another way, a binder is applied to the surface of the abrasive particles prior to introduction into the abrasive article. The abrasive particles may comprise about 0 to 3 weight percent binder based on the weight of the abrasive particles and binder. Examples of commercially available binders include "A174" and "A1230" from OSI. Another example of a commercially available binder is the isopropyl triisosteroyl titanate, available from Kenrich Petrochemical, Bayonne, NJ under the trade name “KR-TTS”.

Filling

In addition, the abrasive coating may optionally include a filler. Fillers are granular materials and generally have an average particle size of 0.1 to 50 micrometers, typically 1 to 30 micrometers. Examples of fillers useful in the present invention include metal carbonates (such as calcium carbonate (choke, calcite, marl, travertine, marble and limestone), calcium magnesium carbonate, sodium carbonate, magnesium carbonate), silica (such as quartz, glass beads , Glass bubbles and glass fibers), silicates (such as talc, clay, (montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate), metal sulfates (such as calcium sulfate, Barium sulfate, sodium sulfate, sodium aluminum sulfate, aluminum sulfate), gypsum, vermiculite, wood flour, aluminum trihydrate, carbon black, metal oxides (such as calcium oxide (lime), aluminum oxide, tin oxide (such as tin oxide), titanium dioxide) And metal sulfite (such as calcium sulfite), thermoplastic resin particles (polycarbonate, polyetherimide, polyester, polyethylene, Risulfone, polystyrene, acrylonitrile-butadiene-styrene block copolymers, polypropylene, acetal polymers, polyurethanes, nylon particles) and thermosetting resin particles (e.g. phenolic resin bubbles, phenolic resin beads, polyurethane foam particles) Etc.). The filler may also be a salt such as a halide salt. Examples of halide salts include sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluoride, potassium chloride, magnesium chloride. Examples of metal fillers include tin, lead, bismuth, cobalt, antimony, cadmium, iron, titanium. Other various fillers include sulfur, organic sulfur compounds, graphite, metal-containing sulfur compounds and the like.

Suspension

One example of a suspending agent is amorphous silica particles having a surface area of less than 150 m 2 / g, which is available under the trade name “OX-50” from DeGussa Corp., Ridgefield, NJ. . Adding a suspending agent may lower the overall viscosity of the polishing slurry. The use of suspending agents is described in more detail in US Pat. No. 5,368,619.

Hardener

The binder precursor may further comprise a curing agent. Curing agents are materials that help initiate and complete a polymerization reaction or crosslinking procedure so that the binder precursor can be converted to a binder. The term curing agent encompasses initiators, photoinitiators, catalysts and activators. The amount and type of curing agent will depend largely on the chemistry of the binder precursor.

Free radical initiator

The polymerization of the preferred ethylenically unsaturated monomer (s) or oligomer (s) takes place via a free-radical mechanism. If the energy source is an electron beam, the electron beam produces free-radicals that initiate the polymerization reaction. However, the use of an initiator even if exposing the binder precursor to an electron beam is within the scope of the present invention. If the energy source is heat, ultraviolet light, or visible light, an initiator may have to be present to generate free-radicals. Examples of initiators (ie photoinitiators) that generate free-radicals when exposed to ultraviolet or heat include organic peroxides, azo compounds, quinones, nitroso compounds, acyl halides, hydrazones, mercapto compounds, pyryllium compounds, imidazoles , Chlorotriazine, benzoin, benzoin alkyl ethers, diketones, phenones, and mixtures thereof, are included, but are not limited to these. Examples of those commercially available as photoinitiators that generate free radicals when exposed to ultraviolet light include IGACURE 651 and IGACURE 184 available from Ciba Gaiji, Hawthorne, New Jersey, and DAROCUR 1173 available from Merck. do. Examples of initiators that generate free radicals when exposed to visible light can be found in US Pat. No. 4,735,632. Another photoinitiator that generates free radicals when exposed to visible light bears the trade name IRGACURE 369, which is available from Ciba Geiza.

Typically, the initiator is used in an amount of 0.1 to 10% by weight, preferably 2 to 4% by weight, based on the weight of the binder precursor. It is also desirable to disperse (preferably uniformly) the initiator in the binder precursor prior to adding any particulate matter such as abrasive particles and / or filler particles.

In general, it is desirable to expose the binder precursor to radiant energy, preferably ultraviolet or visible light. In some cases, certain abrasive particles and / or certain additives absorb ultraviolet and visible light, making it difficult to fully cure the binder precursor. This phenomenon is particularly well seen in the case of cerium oxide abrasive particles and silicon carbide abrasive particles. Quite unexpectedly, it has been found that the use of photoinitiators containing phosphates, in particular those containing acylphosphine oxide, tends to overcome this problem. One example of such a photoinitiator is 2,4,6-trimethylbenzoyldiphenylphosphine oxide, available from BASF Corporation, Charlotte, NC under the trade name LUCIRIN TPO. Other examples of commercially available acylphosphine oxides include DAROCUR 4263 and DAROCUR 4265 (both available from Merck).

Photosensitizer

Optionally, the curable composite can include a photosensitizer or photoinitiator system that affects the polymerization reaction, whether in air or in an inert gas environment such as nitrogen. These photosensitizers or photoinitiator systems include compounds having a carbonyl or t-amino group and mixtures thereof. Preferred compounds having carbonyl groups include benzophenone, acetophenone, benzyl, benzaldehyde, o-chlorobenzaldehyde, xanthone, thioxanthone, 9,10-anthraquinone and other aromatic ketones which can act as photosensitizers. Preferred t-amines are methyl diethanolamine, ethyl diethanolamine, triethanolamine, phenylmethylethanolamine and dimethylaminoethylbenzoate. In general, the amount of photosensitizer or photoinitiator system may vary in the range of about 0.01 to 10% by weight, more preferably 0.25 to 4.0% by weight, based on the weight of the binder precursor. Examples of photosensitizers include QUANTICURE ITX, QUANTICURE QTX, QUANTICURE PTX and QUANTICURE EPD (all available from Biddle Sawyer Corp.).

The abrasive article according to the present invention comprises a backing material bonded to an abrasive coating. The abrasive coating preferably includes a plurality of abrasive composites in shape. These abrasive composites can have a clear or irregular shape. Since the composite having a clear shape is more uniform and consistent, it is preferable that the abrasive composite has a clear shape.

Referring to the drawings, one preferred embodiment 10 of an abrasive article according to the present invention is shown in plan views and enlarged cross-sectional views, respectively, in FIGS. 1 and 2. The abrasive article 10 includes a backing 12, which has an abrasive composite 16 on one of its major surfaces. The abrasive composite 16 includes a plurality of abrasive particles 14 dispersed in the binder 15. The abrasive particles 14 may be a mixture of different abrasive materials. Binder 15 may be used to bond abrasive composite 16 to backing 12. A presize coating or tie layer 13 may optionally be inserted between the abrasive composite 16 and the backing 12.

The abrasive composites 16 preferably have an identifiable shape. Initially, it is preferred that the abrasive particles not come out of the surface of the binder 15. Wearing the surface with the abrasive article 10 causes the composite to collapse, revealing unused abrasive particles 14.

The abrasive composites can have any shape. Typically, the cross-sectional surface area of the bottom surface of the shape in contact with the backing material is greater than the distal end surface area of the composite away from the backing material. The shape of the composite is from a number of geometries such as cubic, block-like, cylindrical, prismatic, rectangular, pyramid, truncated pyramid, cone, truncated cone, cross, and columnar flat top. Can be selected. Another shape is hemispherical and this is described in more detail in PCT WO 95/22436. The resulting abrasive article may have a mixture of different abrasive composite shapes.

The bottoms of the abrasive composites may abut one another, or the bottoms of adjacent abrasive composites may be separated from each other by a certain distance. It will be appreciated that this definition of border also includes an arrangement, such as a bridge, in which adjacent composites share a common abrasive material area or bridge and contact opposite sides between the composites. The abrasive material region is formed from an abrasive slurry such as used to form an abrasive composite. Composites are "adjacent" in the sense that no composite is sandwiched in a virtual straight line drawn between the centers of the composites.

As shown in FIG. 2, one preferred shape of the abrasive composite 16 is a truncated pyramid shape having a generally flat top 18 and an outwardly flanked bottom 20. Although it is desirable to make the height H of the abrasive composite 16 constant throughout the coated abrasive article 10, it is also possible to have abrasive composites of various heights. The height H of the composite may have a value of about 10 to 1500 micrometers, preferably about 25 to 1000 micrometers, more preferably about 100 to 600 micrometers and most preferably about 300 to 500 micrometers.

The bottoms 20 of adjacent abrasive composites are preferably separated from each other by land areas 22. While not wishing to be bound by any theory, it is believed that this land region 22 or separation gap provides a means by which the fluid medium can flow freely between the abrasive composites. And it is believed that this free flow of fluid medium tends to contribute to better cutting speed, surface finish or flatness during the glass polishing process. The spacing between the abrasive composites is about 1 to 100 abrasive composites per cm straight, preferably about 5 to 20 abrasive composites per cm straight, more preferably about 5 to 10 abrasive composites per cm straight Preferably it has a value in the range of about 6-7 abrasive composites per cm of straight line.

In one embodiment of the abrasive article, the spacing area is at least 5 composites / cm 2, preferably at least 100 composites / cm 2. In another embodiment of the present invention, the spacing area has a value of about 1 to 12,000 composites / cm 2.

The base 20 generally has a length of about 100 to 500 micrometers when using a rectangular or truncated pyramid shape. The faces that make up the abrasive composite can be straight or inclined. When the face is inclined, it is generally easier to remove the abrasive composite 16 from the cavity of the production tool as described below. Each “A” in FIG. 2 is an imaginary vertical line across the underside 20 of the abrasive composite 16, ie, the land region 22, at the point where the abrasive composite 16 is in contact with the land region 22. Measure from the vertical line. Each "A" may have a range of about 1 to 75 degrees, preferably about 2 to 50 degrees, more preferably about 3 to 35 degrees and most preferably about 5 to 15 degrees.

In the polishing procedure, the abrasive article backing 12 is attached to a backing pad 24 such as, for example, a urethane backing pad having a Shore A hardness of about 90 durometer or a silicone foam pad having a Shore A hardness of about 65 durometer. The abrasive article backing material 12 can be attached directly onto the backing pad 24 with a pressure sensitive adhesive. Back pad 24 is attached to foam pad 26 that cushions the abrasive article during polishing. Foam pads 26, including the abrasive article, are then installed on the polisher platform 28.

With reference to FIGS. 3 and 4, another preferred embodiment 10 ′ of an abrasive article according to the present invention is shown in FIGS. 3 and 4 in plan and enlarged cross-sectional views, respectively. In this embodiment, the abrasive composite 16 'has a hemispherical shape as shown in FIG. The abrasive article 10 'comprises a woven polyester backing 12', which is sealed on one of its major surfaces with a thermoplastic polyester presized sheath 13 '. A slurry comprising abrasive particles and a binder precursor is applied to the cured presized coating 13 'through a screen (not shown). The hemispherical abrasive composites 16 'may vary in size and shape and may be distributed irregularly or uniformly on the presized sheath 13'. Preferably, the hemispherical abrasive composite 16 'appears circular in the top view as shown in FIG. 3 and has the same diameter.

Regardless of the shape of each abrasive composite, preferably about 20-90%, more preferably about 40-70%, most preferably about 50-60% of the backing surface area is covered with the abrasive composite. . In addition, the surface area difference between the bottom and the top surface is preferably about 0 to 60%, more preferably about 0 to 40%, most preferably about 0 to 20%.

Manufacturing method of abrasive composites having a clear shape

The first step in making an abrasive article is to prepare an abrasive slurry. The abrasive slurry is prepared by mixing the binder precursor, abrasive particles and any additives together by any suitable mixing technique. Examples of mixing techniques include low shear and high shear mixing, with high shear mixing being preferred. Ultrasonic energy can also be used with the mixing step to lower the viscosity of the polishing slurry. Typically, abrasive particles are gradually added into the binder precursor. The polishing slurry is preferably a homogeneous mixture of binder precursor, abrasive particles and optional additives. If necessary, water and / or solvent may be added to lower the viscosity. The amount of bubbles in the polishing slurry can be minimized by drawing off in vacuum during or after the mixing step. In some cases, it is desirable to heat the polishing slurry (generally about 30 to 70 ° C.) to lower the viscosity. It is important to monitor the polishing slurry before coating to ensure that the coating has good rheological properties and that the abrasive particles and other fillers have not settled before coating.

According to this method, an abrasive composite generally having a definite shape is obtained. To obtain a clear shape, the binder precursor is substantially solidified or cured while the abrasive slurry is present in the cavities of the production tool. Alternatively, removal of the product from the binder precursor prior to substantial curing results in flanks having some irregular shape that collapses.

A preferred method of producing an abrasive article comprising an abrasive composite having a definite shape uses a production tool comprising a plurality of cavities. These cavities are essentially the inverse of the desired abrasive composite and create the shape of the abrasive composite. Depending on the number of cavities per unit area, the abrasive article has a corresponding number of abrasive composites per unit area. These cavities can be cylindrical, domed, pyramid, rectangular, truncated pyramid, prismatic, cubic, conical, truncated cone, or any shape whose top face is triangular, square, circular, rectangular, hexagonal, octagonal, etc. It may have a geometric shape. The dimensions of the cavity are chosen to yield the desired number of abrasive composites per unit area. The cavities can be in the same pattern as a spaced point between adjacent cavities or can be adjacent to each other.

The polishing slurry may be coated into the cavities of the production tool by any conventional technique such as die coating, vacuum die coating, spray, roll coating, transfer coating, knife coating, or the like. . If the production tool comprises cavities having a flat top or relatively straight side, it is desirable to use a vacuum during the coating process to minimize trapping of the bubbles.

The production tool may be a belt, sheet, continuous sheet or web, coating rolls such as rotogravure rolls, sleeves or dies installed on the coating rolls. The production tool may consist of metal (including those with nickel plated surfaces), metal alloys, ceramics or plastics. More detailed information on production tools, their manufacture, materials and the like can be found in US Pat. Nos. 5,152,917 (Pieper et al.) And 5,435,816 (Spurgeon et al.). One preferred production tool is a thermoplastic resin production tool that has been embossed from a metal disc.

If the polishing slurry comprises a thermosetting binder precursor, the binder precursor is cured or polymerized. This polymerization is usually initiated by exposure to an energy source. In general, the amount of energy depends on several factors, such as the chemical nature of the binder precursor, the dimensions of the abrasive slurry, the amount and type of abrasive particles, and the amount and type of any additives. Radiant energy is a preferred energy source. Radiant energy sources include electron beams, ultraviolet light, or visible light. Electron beam (ionized) radiation can be used at an energy level of about 0.1 to 10 Mrad, preferably about 0.1 to 10 Mrad. Ultraviolet radiation refers to unspecific radiation having a wavelength in the range of about 200 to 400 nanometers, preferably about 250 to 400 nanometers. The preferred power of the radiation source is 118 to 236 Watt / cm. Visible light radiation refers to unspecific radiation having a wavelength in the range of about 400 to 800 nanometers, preferably about 400 to 550 nanometers.

After the production tool is coated, the backing material and the polishing slurry are contacted by any means so that the polishing slurry wets the front face of the backing material. The abrasive slurry is contacted with the backing material, for example by means of a contact nip roll. Thereafter, some form of radiant energy, as described herein, is transferred to the polishing slurry by an energy source to at least partially cure the binder precursor. For example, the production tool may be a transparent material (eg, polyester, polyethylene or polypropylene) to allow radiant light to be transferred to the slurry contained in the cavity. The term "partially hardened" means that the polymer is polymerized to the extent that the binder precursor does not flow when the polishing slurry is removed from the production tool. If the binder precursor is not fully cured, it can be removed from the production tool and then completely cured with any energy source. Other details of the use of the production tool for producing abrasive articles according to this preferred method are described in US Pat. Nos. 5,152,917 (Pieper et al.) (Coated abrasives produced here are reverse replicas of production tools) and 5,435,816. (Spursion, etc.).

In another variant of this first method, the polishing slurry can be coated onto the backing material rather than into the cavity of the production tool. The backing material coated with the polishing slurry is then contacted with the production tool to allow the polishing slurry to flow into the cavity of the production tool. The remaining steps for making the abrasive tool are as described above. In connection with this method, it is preferable to cure the binder precursor by radiant energy. Radiant energy may be transmitted through the backing material and / or the production tool. If radiant energy is transferred through the backing material or production equipment, the backing material or production equipment should not absorb radiation energy to a significant extent. In addition, the source of radiant energy should not significantly disrupt the backing material or production equipment. For example, ultraviolet light can be transmitted through the polyester film backing material.

Alternatively, when the production tool is made of a constant thermoplastic material such as polyethylene, polypropylene, polyester, polycarbonate, poly (ether sulfone), poly (methyl methacrylate), polyurethane, polyvinylchloride or a combination thereof Ultraviolet or visible light may pass through the production tool and into the polishing slurry. In some cases, it is desirable to introduce ultraviolet stabilizers and / or antioxidants into the thermoplastic resin production tool. The easier the material to deform, the easier the processing procedure. In the case of a polishing tool based on a thermoplastic resin, the operating conditions for making the polishing tool should be set so that excessive heat is not generated. If excessive heat is generated, the thermoplastic resin tool may be deformed or melted.

After the abrasive article is made, it may be bent or wetted prior to conversion to the appropriate form (shape) prior to use.

Another method of making an abrasive article is to join a plurality of lumps of abrasive to the backing material. These abrasive masses comprise a plurality of abrasive particles joined together by a first binder and shaped into a shaped mass. The resulting abrasive mass is dispersed in a second binder precursor and coated on the backing material. The second binder precursor solidifies to form a binder and bonds the abrasive mass to the backing material.

The abrasive mass may comprise any of the additives described above. The abrasive mass should have the desired wear rate to collapse during use. In other words, this wear rate can be determined by the type of abrasive particles, the first binder type, the type of additives and their proportions.

Abrasive lumps are described in US Pat. No. 4,311,489; No. 4,652,275; It may be prepared by any conventional method such as those described in detail in US Pat. Nos. 4,799,939 and 5,500,273.

The abrasive mass is dispersed in a second binder precursor to form an abrasive slurry. The remaining steps for making the abrasive article may be as mentioned herein. Alternatively, the polishing slurry may be applied onto the backing material by blade coating, roll coating, spraying, gravure coating, die coating, curtain coating or other conventional coating techniques. The polishing slurry is then exposed to an energy source to cure the binder precursor and convert the polishing slurry into an abrasive composite.

Method for producing an abrasive composite having an unclear shape

A second method of making an abrasive article relates to a method in which the abrasive composites have an opaque or irregular shape. In this method, the polishing slurry is exposed to an energy source once removed from the production tool. The first step is to coat the polishing slurry on one side of the backing material by any conventional technique, such as a drop die coater, roll coater, blade coater, curtain coater, vacuum die coater, or die coater. If desired, the polishing slurry may be heated and / or sonicated prior to coating to lower the viscosity. The polishing slurry / back material combination is then contacted with the production tool. The tool may be the same as the type of tool described above. The production tool includes a series of cavities and the abrasive slurry flows into these cavities. When the abrasive slurry is removed from the tool, the abrasive slurry has a pattern associated with it (ie, the pattern of abrasive composite is formed from the cavities in the tool). After removal, the backing material coated with the polishing slurry is exposed to an energy source to initiate the polymerization reaction of the binder precursor and form an abrasive composite. It is generally desirable to minimize the time from removing the backing material coated with the polishing slurry from the production tool to curing the binder precursor. If this time is too long, the polishing slurry will flow and deform to the extent that the pattern disappears substantially.

In another variant of this second method, the polishing slurry can be coated into the cavity of the production tool rather than on the backing material. The backing material is then contacted with the production tool such that the polishing slurry wets the backing material and adheres to the backing material. In this modified method, for example, the production tool may be a rotogravure roll. The remaining steps for producing the abrasive article are as described above.

Another variant is to spray or coat the abrasive slurry through a sieve to create a pattern. The binder precursor is then cured or solidified to form an abrasive composite.

Another technique for manufacturing an abrasive article having an abrasive coating having a pattern or a grain associated therewith is to provide an embossed backing material and then coat the polishing slurry on the backing material. The abrasive slurry provides a coating having a pattern or texture along the contour of the embossed backing material.

Another method for making an abrasive article is described in US Pat. No. 5,219,462. The polishing slurry is coated with a dent in the embossed backing material. The abrasive slurry includes abrasive particles, binder precursors and swelling agents. The resulting structure is exposed to conditions such that the expanding agent can expand the abrasive slurry onto the front of the backing material. The binder precursor is then solidified to form a binder and the polishing slurry is converted to an abrasive composite.

The abrasive article can be converted into any desired shape or form, depending on the desired appearance for glass polishing. This switching can be performed by slitting, die cutting or any suitable means.

Glass polishing method

Prior to polishing according to the method of the invention, the glass is typically treated with various physical treatment procedures (including polishing) to obtain glass of the desired dimensions. These previous steps leave scratches or exposed defects on the glass surface, which results in a surface that is typically blurred. The present invention is directed to a method of polishing a glass surface that sufficiently removes the depth of scratches and defects to provide a surface that can be polished to obtain optical transparency.

Generally one or more "polishing" or "fine abrasive" articles are used in the polishing step of the method of the present invention. In the past, one abrasive article with a given average abrasive grain size was insufficient to produce a surface with a very high gloss. Rather, abrasive articles are used continuously so that the average scratch depth decreases continuously. The first abrasive article typically includes abrasive particles having a larger particle size. As polishing continues, the abrasive particle size in the abrasive article used by the user to replace the abrasive article gradually decreases. This leads to a gradual decrease in scratch depth. The number of abrasive articles, polishing time, type of abrasive particles and the size of the abrasive particles can be affected by several factors such as the size of the glass surface to be polished, the severity of scratches and / or defects present in the glass prior to polishing, and the composition of the glass itself Will depend on.

Preference is given to polishing the glass in the presence of a liquid. Liquids have several advantages associated with them. This prevents heat generation during the polishing process and removes cutting swarf from the polishing interface. "Cutting shavings" is a term that describes the actual glass shavings polished by the abrasive article. In some cases, the glass cutting chips can damage the glass surface to be polished. Therefore, it is desirable to remove the cutting chips from the interface. Polishing in the presence of liquid also results in a finer glass finish surface. This liquid can be water, organic lubricants, detergents, coolants or combinations thereof. The liquid may also further include additives to enhance polishing. In general, water is the preferred liquid.

During the polishing process, the abrasive article moves against the glass surface and is preferably lowered on the glass surface with a force of about 0.35 to 7.0 g / mm 2, more preferably about 0.7 to 3.5 g / mm 2 and most preferably about 5 g / mm 2. Force is applied in the direction. If the force in the downward direction is too great, the abrasive may not be able to fine the scratch depth and in some cases increase the scratch depth. In addition, too much force in the downward direction may cause the abrasive article to wear excessively. Conversely, if the force in the downward direction is too weak, the abrasive article may not effectively fine the scratch depth and produce an optically transparent surface.

As mentioned above, the glass or abrasive article or both move relative to each other during the polishing step. This motion may be a rotational motion, a random motion or a linear motion. The rotational motion can be generated by attaching the polishing disk to the rotating tool. The glass surface and the abrasive may rotate in the same direction or in opposite directions, but in the same direction, vary the rotation speed. In the case of a machine, the revolutions per working minute ranges from about 4000 rpm or less, preferably from about 25 to 2000 rpm, more preferably from about 50 to 1000 rpm, depending on the abrasive article used. For example, when disks such as those shown in FIGS. 1 and 2 are used, the machine may have a rotation speed of about 25 to 2000 rpm, typically about 500 rpm. Random track motion can be generated by a random track tool, and linear motion by a continuous polishing belt. The relative motion between the glass and the abrasive article may also depend on the dimensions of the glass. If the glass is relatively large, it is desirable to hold the glass and move the abrasive article during the polishing process.

In many cases, the abrasive article is bonded to a support pad. The support pad is typically a compressive material that supports the abrasive article. In addition, the support pads may be shaped so that they conform to the shape of the glass intermediate, if the resulting abrasive is required when the abrasive is attached to the support pad, especially when the glass intermediate has a curve or a shape associated with itself. It is made from a material capable of matching. The support pad can be made of polyurethane foam, rubber material, elastomer, foam based on rubber, or any other suitable material. The hardness and / or compressibility of the support pad material is selected to provide the desired polishing properties (cutting speed, abrasive life and surface finish of the glass intermediate).

The support pad may have a continuous, relatively flat surface to which the abrasive article is secured. Alternatively, the support pad may have a discontinuous surface with a series of protrusions and depressions to which the abrasive article is secured. In the case of discontinuous surfaces, the abrasive article may be fixed only to the protrusions. In contrast, one piece of abrasive article may be secured to one or more protrusions such that the entire abrasive article is not fully supported. The discontinuous surface of the support pad is selected to provide the desired flow of water and the desired polishing properties (cut speed, abrasive life and surface finish of the glass intermediate).

It is also within the scope of the present invention that the backing material of the abrasive article functions as a support pad. For example, the backing material may be a foam backing material, such as a polyurethane foam.

The support pads can have any shape, such as round, rectangular, square, oval, or the like. The support pad can have a size (longest dimension) in the range of about 5-1500 cm.

Attachment means

The abrasive article is fixed to the support pad by the attachment means. These attachment means can be pressure sensitive adhesives, hook and loop attachment means, mechanical attachment means or permanent adhesives. The attachment means should be such that the abrasive article is firmly attached to the support pad to withstand the harsh conditions (humid environment, heat generation and pressure) during glass polishing.

Representative examples of pressure sensitive adhesives suitable for the present invention include latex crepe, rosins, acrylic polymers and copolymers (e.g. polybutylacrylate, polyacrylate esters), vinyl ethers (e.g. polyvinyl n- Butyl ether), alkyd adhesives, rubber adhesives (eg, natural rubber, synthetic rubber, chlorinated rubber) and mixtures thereof. Pressure sensitive adhesives may be coated from water or solvents. In some cases, it is preferable to use a pressure-sensitive adhesive based on rubber coated from a nonpolar organic solvent. Alternatively, the pressure sensitive adhesive may be a transfer tape.

Alternatively, the abrasive article may include a hook and loop type attachment system for securing the abrasive article to the support pad. There is a hook on the support pad and the loop fabric may be on the back side of the coated abrasive. Alternatively, a loop may be present on the support pad and the hook may be on the back side of the coated abrasive. Such hook and loop type attachment systems are described in more detail in US Pat. Nos. 4,609,581, 5,254,194, 5,505,747 and PCT WO95 / 19242.

The following test methods and examples are intended to illustrate the invention in more detail, but the invention is not limited to these examples. All parts, percentages, ratios, etc. used in the examples are by weight unless otherwise indicated.

RPP test method

The "RPP" method used a "Buehler Ecomet 4" variable speed grinder-polisher equipped with a "Buehler Ecomet 2" power head, both of which are commercially available from Bueller Industries, Lake Bluff, Illinois. The test was performed using a 500 rpm motor speed with a force of 50 pounds corresponding to a pressure of about 7.1 psi (about 50 kPa) over the surface area of the test glass blank.

A flat circular test glass blank was prepared from Corning Glass Company under the trade name CORNING # 9061, having a diameter of about 7.62 cm (3 inches) and about 1.0 cm thick. The glass material was fixed in the grinder-polisher power head. The grinder-polisher's 12-inch aluminum platform was rotated counterclockwise while the test glass blank rotated the fixed power head clockwise at 35 rpm.

The abrasive article to be tested was die cut into 20.3 cm (8.0 inch) diameter circles and attached directly with a pressure sensitive adhesive onto a urethane backing pad having a Shore A hardness of about 90 durometer. The urethane backing pad was attached to an open cell (soft foam pad having a thickness of about 30 mm cut out from the soft foam sheet). This pad assembly was fixed to the aluminum platform of the grinder / polisher. Tap water was sprayed onto the abrasive article at a flow rate of about 3 liters per minute to lubricate at the interface between the abrasive article surface and the test glass blank.

In order to provide a substantially similar initial surface finish on the test glass blanks (ie, prior to polishing with the abrasive), each test glass blank was mined with a metal-bonded diamond abrasive (trade name "3M Flexible Diamond M125"). Wear, commercially available from 3M, St. Paul). These diamond particles have an average particle size of about 125 micrometers.

Initial surface finish on test glass blanks was evaluated with a diamond probe profilometer (commercially available from Taylor Hobson, Leicester, UK under the tradename SURTRONIC 3 (112 / 1518-822323)). The initial weight of the test glass blank was also recorded. Initial surface finish or Ra values for evaluating abrasive articles according to the present invention typically fall into three categories: at least about 1.2 μm, at least about 0.2 μm, and at least about 0.05 μm.

The test glass blanks were polished using the grinder / polisher described above. The polishing time interval of the grinder / polisher was set to 15 seconds or 10 seconds. However, since the grinder / polisher does not start counting until the abrasive is stabilized on the test glass blank surface, the actual contact time between the abrasive and the test glass blank surface was found to be greater than the set time. That is, the abrasive article on the glass surface bouncing or jumping was observed and the grinder / polisher began to time at the point where the contact between the abrasive article and the glass surface was substantially constant. Thus, the real time polishing interval, ie the contact time between the abrasive article and the glass surface, was less than about 25 seconds when the polishing time interval was set to 15 seconds or 10 seconds.

After polishing, the final surface finish and final weight were recorded respectively. The change in weight of the test glass blank during the polishing time is represented by the number of grams of glass stock removed. The cutting speed (grams of glass material removed) and Ra value were recorded.

The following abbreviations have been used throughout.

Material description

UAO: urethane acrylate (available under the trade name UVITHANE 893, available from Malton International Inc., Chicago, Illinois);

HDDA: 1,6-hexanediol diacrylate (available under the trade name SR 238, available from Sartomer, Exton, Pa.);

TPDA: tripropylene glycol diacrylate (available under the trade name SR 306, available from Sartomer, Exton, Pa.);

PH2: Ciba Geiza, Greensboro, NC under the trade name IRGACURE 369, 2-benzyl-2-N, N-dimethylamino-1- (4-morpholino-phenyl) -1-butanone photoinitiator Available from);

ACH: 1,1'-azobis (cyclohexanecarbonitrile) (available under the trade name VAZO 88, available from Dupont de Nemours, Wilmington, Delaware);

ASF: amorphous silica filler (available under the trade name AEROSIL R-972, available from Demug GmbH, Germany);

TFS: trifluoropropylmethyl siloxane defoaming agent (trade name, available from Dow Corning Company, Midland, Mich.);

DIA: Industrial Diamond Particles (various sizes) (available under the trade name RB, available from Warren Diamond, Olifant, Pa.); And

SIC: Silicon carbide abrasive grains with an average size of 60 micrometers (available from Norton Company, Worcester, Mass.).

Abrasive Composite Topography

Topography A was prepared according to the following procedure. The production tool was made by casting a polypropylene material onto a metal disc tool having a casting surface consisting of a set of adjacent truncated pyramids. The metal disc tool was made by a diamond turning procedure. The resulting polymer production tool includes four-sided cut pyramidal cavities. The height of each truncated pyramid was about 355 micrometers (14 mils (1 mil = 1/1000 inch)), each base was about 1427 micrometers (1.4 mm) per side and the top was about 1350 micrometers (1.35 mm) per side. Between the bases of adjacent truncated pyramids was about 445 micrometers.

Topography B was prepared as described above except that the height of each truncated pyramid was about 760 micrometers, each base was about 880 micrometers per side and the top was about 640 micrometers per side. Between the bases of adjacent truncated pyramids was about 127 micrometers. In each of these topography, the composites have a definite shape.

Example 1-18

Examples 1-9 were prepared by mixing the ingredients listed in Table 1 in a high shear air mixer for 30 minutes (added in the order described from left to right). Diamond (DIA) has an average particle size of 74 micrometers.

Example UAO HDDA TPDA PH2 ACH ASF DIA SIC TFS DIA One 60.70 7.70 23.00 1.00 0.50 2.00 5.00 0 0.10 5% 2 55.70 7.70 23.00 1.00 0.50 2.00 10.00 0 0.10 10% 3 50.70 7.70 23.00 1.00 0.50 2.00 15.00 0 0.10 15% 4 45.7 7.70 23.00 1.00 0.050 2.00 20.00 0 0.10 20% 5 35.70 7.70 23.00 1.00 0.50 2.00 30.00 0 0.10 30% 6 25.70 7.70 23.00 1.00 0.50 2.00 40.00 0 0.10 40% 7 55.70 7.70 23.00 1.00 0.50 2.00 5.00 5.00 0.10 8 45.70 7.70 23.00 1.00 0.50 2.00 10.00 10.00 0.10 9 35.70 7.70 23.00 1.00 0.50 2.00 15.00 15.00 0.10

Manufacture of abrasive articles

The polishing slurry mixed above was applied into the cavities of the production tool (topography A) using a rubber spatula at room temperature. Then, a polyester film (108 micrometers thick) with an ethylene acrylic acid (EAA) pretreatment on the surface was contacted with the production tool coated with the abrasive slurry so that the polishing slurry could wet the front side of the backing material with the pretreatment agent. Ultraviolet and visible radiation was passed through the backing material and into the polishing slurry. Two lamps were used in series. Both lamps are ultraviolet-visible lamps from American Ultraviole Company, Murray Hill, NJ, using medium pressure mercury bulbs and operate at 157.5 watts / cm (400 watts / inch). Curing rate was about 7.62 meters / minute (25 ft / minute). Upon exposure to ultraviolet light the binder precursor turned into a binder and the polishing slurry turned into an abrasive composite. The tool was then removed from the abrasive composite / backing material.

Examples 10-18 were prepared in the same manner as described in Examples 1-9, except that the production tool used was Topography B.

Examples 1-18 were tested using the RPP test method with a polishing time interval of about 25 seconds as described above. The input Ra was about 1.4 to 1.5 micrometers. The results are shown in Table 2 below.

Example Removed Material (grams) Ra (micrometer) One 1.54 0.55 2 1.52 0.52 3 1.43 0.44 4 1.42 0.39 5 1.10 0.34 6 1.25 0.35 7 1.33 0.45 8 1.33 0.47 9 1.19 0.44 10 1.39 0.60 11 1.35 0.48 12 1.43 0.53 13 1.32 0.40 14 NA NA 15 1.13 0.36 16 1.08 0.52 17 1.17 0.43 18 1.17 0.39

Examples 19 and 20 (topography A) were prepared in the same manner as in Examples 1-9, except that the components shown in Table 3 below were used. Examples 19 and 21 used a mixture of two diamond particles of size about 30 μm and about 45 μm. Examples 20 and 22 used two diamond particle mixtures of about 9 μm and about 15 μm in size. Examples 21 and 22 were prepared in the same manner as in Examples 19 and 20 except that the production tool used was Topography B.

Examples 19 and 20 were tested using test glass blanks polished with the abrasive articles of Examples 4, 7, 8 and 9. Thus, the final Ra value is the input Ra value of Examples 19-22. Examples 19 and 21 were tested using the RPP test method described for Examples 1-18. These test glass blanks were polished using the RPP test method with a polishing time interval of about 25 seconds as described above and using the abrasive articles of Examples 20 and 22. Thus, Examples 4, 7, 8 and 9 (with an average particle size of about 74 μm), Example 19 (a mixture of two diamond particles about 30 μm and about 45 μm in size) and Example 20 (about 9 The polishing system comprising the abrasive article according to the present invention was evaluated in the order of polishing of a mixture of two diamond particles having a size of about 탆 and about 15 탆. The initial Ra before polishing with Examples 4, 7, 8 and 9 was at least about 1.4 μm. The results are shown in Table 4.

Example UAO HDDA TPDA PH2 ACH ASF TFS DIA DIA 19/21 45.70 7.70 23.00 1.00 0.50 2.00 0.10 15.00 (30㎛) 5.00 (45㎛) 20/22 45.80 30.60 0 1.00 0.50 2.00 0.10 15.00 (9㎛) 5.00 (15㎛)

Example Ra Example Ra Example Ra Example Ra 4 0.39 7 0.45 8 0.47 9 0.44 19 0.06 19 0.07 19 0.08 19 0.08 20 0.04 20 0.03 20 0.04 20 0.04

The results in Table 4 show that addition of silicon carbide particles to an abrasive article having a large particle size does not improve the surface finish Ra value before polishing with two abrasive articles having a smaller particle size. However, the overall finish was not adversely affected.

Comparative Example A-F

Comparative Example A-F was prepared in the same manner as in Example 1-9 except for using the components shown in Table 5. For each comparative pair (ie, A and V, C and D, E and F), Topography A was used for the first comparative example and Topography X was used for the second comparative example. Silicon carbide particles (SIC) had an average particle size of 60 μm.

Comparative Example A-F was tested in the same manner as in Example 1-18 described above. Two samples were tested for each comparative example and both results were shown. The results are shown in Table 6 below. Ra and Rtm values are the average of five measurements for each abrasive article tested.

Comparative example UAO HDDA TPDA PH2 ACH ASF SIC TFS SIC A / Ｂ 60.70 7.70 23.00 1.00 0.50 2.00 5.00 0.10 5% C / D 55.70 7.70 23.00 1.00 0.50 2.00 10.00 0.10 10% E / F 50.70 7.70 23.00 1.00 0.50 2.00 15.00 0.10 15%

Comparative Example A Comparative Example Comparative Example C Comparative Example D Comparative Example E Comparative Example F Removed Material (grams) 0.01 0.01 0.02 0.03 0.02 0.05 Average Ra 0.81 0.90 1.21 0.70 0.73 0.52 Removed Material (grams) 0.02 0.05 0.02 0.03 0.03 0.05 Average Ra 1.17 0.95 0.69 0.71 0.74 0.96

The data above show that an abrasive article comprising silicon carbide particles removes less glass material than the abrasive article according to the present invention as shown in Examples 1-18 of Table 2. Moreover, no significant polishing difference between topography A and topography B was seen.

Comparative example

Comparative Example Vs-S below demonstrates the ability of Example 20 to include 20% diamond particles having an average size of about 9 μm and about 15 μm. Comparative Examples V-S are other similar abrasive articles commercially available. These abrasive articles were polished with an abrasive article of Example 4 (average size of diamond particles about 74 μm) and Example 19 (mixing of two diamond particles of size about 30 μm and about 45 μm) onto a test glass blank after polishing. Was tested. The abrasive article was tested using the test method above, except that silicone foam pads with Shore A hardness of about 65 durometers were used instead of urethane open cells (soft foam pads). As mentioned above, it was expected that changing the backing pad would affect polishing performance both in the number of grams of material removed and in the surface finish indicated by the Ra value. In addition, the "polishing time" described in the table below actually refers to the polishing time interval set on the polisher / grinder device. The input Ra value before polishing with the abrasive article of Example 4 was at least about 1.4 μm.

Example 4 19 20 Polishing time 15 seconds 15 seconds 10 sec Removed Material (grams) 1.2 0.18 0 Average Ra 0.32 0.07 0.03

The data shown in Table 7 shows that the exchange of the backing pad did not affect the number of grams of material removed from the test glass blank using the abrasive article according to the invention comprising abrasive grains in three size ranges. However, after polishing with the abrasive article of Example 20 (mixing of two diamond particles of about 9 μm and about 15 μm in size), a substantially optically transparent surface was obtained on the test glass blank.

For Comparative Example V-S, a polishing test was conducted using the RPP test method as described for Examples 20 and 22. The results are shown below.

Comparative Example 금속 is a metal-bonded diamond abrasive product available under the trade name "Flexible Diamond M20 (3M 6001J)" from Minnesota Mining and Manufacturing Company (hereinafter referred to as "3M") in St. Paul, Minn. . Diamond particles have an average particle size of about 20 micrometers.

Comparative Example H is a metal-bonded diamond abrasive article available from 3M under the trade name "3M Flexible Diamond M10 (3M 6001J)". Diamond particles have an average particle size of about 10 micrometers.

Example 4 19 Comparative Example Comparative Example H Removed Material (grams) 0.2 0.02 1.56 0.79 Polishing time 10 sec 10 sec 10 sec 10 sec Average Ra 0.23 0.06 0.61 0.35

Comparative Example I is a conventional silicon carbide wrapped abrasive article available from 3M under the trade name "Imperial Microfinishing Film S / C PSA (3M 468L)". Silicon carbide particles have an average particle size of about 9 micrometers.

Examples 4 and 19 and Comparative Example I were tested as described above. The input Ra value was about 1.59 micrometers.

Example 4 19 Comparative Example I Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.24 0.06 0.04

Comparative Example V is a conventional silicon carbide wrapped abrasive article available from 3M under the trade name "Imperial Microfinishing Film S / C PSA (3M 468L)". Silicon carbide particles have an average particle size of about 15 micrometers.

Examples 4 and 19 and Comparative Example VII were tested as described above. The input Ra value was 1.42 micrometers and the input Rtm value was 15.35 micrometers.

Example 4 19 Comparative Example Removed Material (grams) 0.78 0.09 0.04 Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.24 0.06 0.05 Average Rtm 8.91 10.25 9.82

Examples 4 and 19 and Comparative Examples I and V were tested as described above. The input Ra value was 1.50 micrometers and the input Rtm value was 10.56 micrometers.

Example 4 19 Comparative Example J Comparative Example I Removed Material (grams) 0.63 0.09 0.08 0.0 Polishing time 10 sec 10 sec 10 sec 10 sec Average Ra 0.026 0.06 0.06 0.04 Average Rtm 3.42 4.22 5.91 7.77

Comparative Example V is a conventional aluminum oxide wrapped abrasive article available from 3M under the trade name "Imperial Fre-Cut Microfinishing Film PSA (3M 266L)". Aluminum oxide particles have an average particle size of about 15 micrometers.

Examples 4 and 19 and Comparative Example VII were tested as described above. The input Ra value was 1.54 micrometers and the input Rtm value was 10.38 micrometers.

Example 4 19 Comparative Example Removed Material (grams) 0.95 0.13 0.0 Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.29 0.07 0.06 Average Rtm 2.44 0.90 0.84

Comparative Example L is a conventional diamond wrapped abrasive article available from 3M under the trade name "Imperial Diamond Lapping Film 3 mil backing (3M 662X)". Diamond particles have an average particle size of about 15 micrometers.

Comparative Example M is a conventional diamond wrapped abrasive article available from 3M under the trade name "Imperial Diamond Lapping Film 3 mil backing (3M 662X)". Diamond particles have an average particle size of about 9 micrometers.

Examples 4 and 19 and Comparative Examples L and M were tested as described above. The input Ra value was 1.41 micrometers.

Example 4 19 Comparative Example L Comparative Example M Removed Material (grams) 0.21 0.02 0.02 0.01 Polishing time 10 sec 10 sec 10 sec 10 sec Average Ra 0.19 0.08 0.08 0.06

Comparative Example N is a conventional resin bonded diamond abrasive article available from 3M under the trade name "Imperial Diamond Lapping Film-Type P PSA (3M 664X)". Diamond particles have an average particle size of about 9 micrometers.

Examples 4 and 19 and Comparative Example N were tested as described above. The input Ra value was 1.34 micrometers.

Example 4 19 Comparative Example N Removed Material (grams) 0.44 0.07 0.02 Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.23 0.07 0.06

Comparative Example O is a conventional beaded diamond abrasive article available from 3M under the trade name "Imperial Diamond Lapping Film-Type B PSA (3M 666X)". Diamond particles have an average particle size of about 9 micrometers.

Examples 4 and 19 and Comparative Example O were tested as described above. The input Ra value was 1.60 micrometers.

Example 4 19 Comparative Example Removed Material (grams) 0.68 0.09 0.04 Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.25 0.06 0.08

Comparative Example P is a conventional aluminum oxide wrapped abrasive article available from 3M under the trade name "Imperial Fre-Cut Microfinishing Film PSA (3M 266L)". Aluminum oxide particles have an average particle size of about 9 micrometers.

Examples 4 and 19 and Comparative Examples X and P were tested as described above. The input Ra value was 1.72 micrometers and the input Rtm value was 11.62 micrometers.

Example 4 19 Comparative Example Comparative example P Removed Material (grams) 0.55 0.11 0.01 0.0 Polishing time 10 sec 10 sec 10 sec 10 sec Average Ra 0.31 0.08 0.06 0.05 Average Rtm 2.86 0.85 0.64 0.61

Examples 4 and 19 and Comparative Example P were tested as described above. The input Ra value was 1.47 micrometers.

Example 4 19 Comparative example P Removed Material (grams) 0.45 0.07 0.0 Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.22 0.06 0.06

Comparative Example V was prepared in the same manner as in Example 20 except that the abrasive particles used were white aluminum oxide, a 50/50 mixture of particles having an average particle size of about 9 and about 15 microns.

Examples 4 and 19 and Comparative Example VII were tested as described above. The input Ra value was 1.51 micrometers.

Example 4 19 Comparative Example Removed Material (grams) 0.28 0.03 0.01 Polishing time 15 seconds 15 seconds 10 sec Average Ra 0.15 0.05 0.06

Comparative Example R was prepared in the same manner as in Example 20 except for using silicon carbide abrasive particles instead of white aluminum oxide.

Comparative Example S is an abrasive article containing cerium oxide particles and prepared as follows. The polishing slurry contains the following components:

BP1: pentaerythritol tetraacrylate (available under the trade name SR 295, available from Sartomer, Exton, Pa.);

BP2: 2-phenoxyethyl acrylate resin (commercially available from Sartomer under the trade name SR 339);

CA1: 3-methacryloxypropyltrimethoxysilane binder (available under the trade name A-174, available from OSI Specialty, Inc., Danbury, CT);

PH7: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide liquid photoinitiator (commercially available from BASF Corporation, Charlotte, NC under the trade name Lucirin LR 8893);

CEO1: cerium oxide abrasive particles having an average particle size of about 0.5 micrometers (available from Long Franca, Shelton, CT); And

APS: Anionic polyester surfactant (available under the trade names FP4 and PS4, available from IC America, Inc., Wilmington, Delaware).

The abrasive article of Example 1 was prepared from the abrasive slurry formulation described in Table 19.

ingredient weight% BP1 6.85 BP2 6.85 CA1 0.84 APS 1.26 PH7 0.47 CEO1 83.74

This abrasive article was made from a cerium oxide slurry having the above formulation. The abrasive article includes abrasive composites having a definite shape. The cerium oxide particles have an average particle size of about 0.3 micrometers.

Examples 4 and 19 and Comparative Examples R and S were tested using the same test method as described above except that the polishing times shown in Table 20 were used. The input Ra was about 1.46 micrometers.

Example 4 19 Comparative Example R Comparative Example S Removed Material (grams) 0.25 0.0 0.0 0.0 Polishing time 10 sec 10 sec 10 sec 10 sec Average Ra 0.15 0.07 0.05 0.06

The abrasive articles of Comparative Example V-S were not effective in obtaining a nearly optically transparent surface finish compared with the results obtained with the abrasive article of Example 20 above. Although the Ra value may be similar to that achieved using the abrasive article of Example 20, the test glass blanks polished with the abrasive article of Comparative Example B-S exhibited an overall hazy surface finish with deep scratches in some cases. .

Comparative Example T-Ｗ

Example 4 (average size of abrasive particles about 74 μm), Example 19 (abrasive particles having an average size of about 30 μm and about 45 μm), and Example 20 (average sizes of about 9 μm and about 15 μm) A three-part abrasive article system, wherein the glass polishing article of the present invention has an aluminum oxide having an average size of 125 탆, 35 탆, 10 탆, and 5 탆 (Comparative Examples T, V, V and V, respectively). Compared to structured polishing pad system comprising particles. These polishing pads are typically used for off-hand lapping, A 125 MIC 3M 268XA AO, A 35 MIC 3M 268XA XO, A 10 MIC 3M 268XA AO, and A 5 MIC 3M, respectively, from 3M Available under the trade name 268XA AO.

Comparative example Ｔ Ｕ Ｖ Ｗ Removed Material (grams) 8.05 2.26 0.58 0.16 0.10 0.03 0.01 0.01 Polishing time 15 seconds 15 seconds 15 seconds 10 sec Average Ra 1.97 0.43 0.17 0.08

The test glass blank polished with the abrasive article system of Comparative Example T-X did not show a fine surface finish compared to the results of Table 7 for the abrasive article of the present invention. Furthermore, the surface finish state made of the abrasive article of Comparative Example T-X was more cloudy than that produced with the abrasive article of the present invention.

It will be apparent to those skilled in the art that various modifications or variations of the present invention can be made without departing from the scope and spirit of the invention, and it is to be understood that the invention is not to be unduly limited to the illustrative embodiments set forth herein. .

Claims (12)

Backing material; And One or more three-dimensional abrasive coatings containing cured binder precursors with urethane acrylate oligomers and containing diamond particles dispersed in a binder bound to the backing surface and tested according to the RPP method having a polishing time interval of about 25 seconds. An abrasive article capable of reducing an initial Ra of about 0.05 μm or more on a glass test blank to a final Ra of about 0.05 μm or less. The abrasive article of claim 1, wherein the at least one abrasive coating comprises a plurality of composites having a definite shape. The abrasive article of claim 1, wherein the at least one abrasive coating comprises a plurality of composites having an irregular shape. 3. The abrasive article of claim 2, wherein each of the composites having a definite shape comprises a bottom having a surface area of up to about 60% greater than the top. delete delete delete delete delete Contacting the abrasive article according to any one of claims 1 to 4 with the ability to remove at least about 0.75 g of glass material from the test glass blank according to the RPP method having a polishing time interval of about 25 seconds. Making a step; Supplying a liquid to an interface between the glass intermediate product and the abrasive article; Rubbing the glass intermediate product and the abrasive article against each other; And Reducing the initial Ra to about 0.7 μm or less. Contacting an abrasive article comprising a backing material and at least one three-dimensional abrasive coating containing a plurality of diamond particles dispersed in a binder bonded to the backing surface, with the convex surface of the cathode ray tube product; Rubbing the convex surface of the cathode ray tube glass article and the abrasive article against each other in the presence of water; And A method of polishing a non-flat cathode tube glass article, the method comprising reducing the surface finish of a convex surface of the cathode tube glass article. delete