EP2598291B1

EP2598291B1 - Hybrid abrasive hand pad and method of abrading a surface

Info

Publication number: EP2598291B1
Application number: EP10855168.0A
Authority: EP
Inventors: Anthony R. Carrozzella; William G. Suzuki; Deyue Yu; Zhijun Zhang
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2010-07-28
Filing date: 2010-07-28
Publication date: 2019-07-10
Anticipated expiration: 2030-07-28
Also published as: EP2598291A4; WO2012012940A1; TW201219155A; EP2598291A1; CN103068525A; US20130130600A1; CN103068525B

Description

TECHNICAL FIELD

The present disclosure relates broadly to abrasive articles.

BACKGROUND

In general, coated abrasive articles comprise an abrasive layer secured to a major surface of a backing. The abrasive layer typically includes abrasive particles and a binder that secures the abrasive particles to the backing. An abrasive hand pad comprising: a coated abrasive member comprising an abrasive layer secured to a major surface of a flexible, dense backing, wherein the abrasive layer comprises first abrasive particles and a first binder; is e.g. known from document US 2009/017727 A1 .
One common type of coated abrasive article has an abrasive layer which comprises a make layer, a size layer, and abrasive particles. In making such a coated abrasive article, a make layer comprising a first binder precursor is applied to a major surface of the backing. Abrasive particles are then at least partially embedded into the make layer (for example, by electrostatic coating), and the first binder precursor is cured (that is, crosslinked) to secure the particles to the make layer. A size layer comprising a second binder precursor is then applied over the make layer and abrasive particles, followed by curing of the binder precursors.
Another common type of coated abrasive article comprises an abrasive layer secured to a major surface of a backing, wherein the abrasive layer is provided by applying a slurry including a binder precursor and abrasive particles onto a major surface of a the backing, and then curing the binder precursor. Typically, the slurry is shaped prior to curing to form a plurality of shaped abrasive composites secured to the backing.
Nonwoven abrasive products are generally made by applying an abrasive coating precursor to a nonwoven fiber web (for example, a lofty open nonwoven fiber web) and curing the abrasive coating precursor. Familiar nonwoven abrasives of this type are sold under the trade designation "SCOTCH-BRITE" by 3M Company of St. Paul, Minnesota.
During hand finishing operations of painted surfaces (for example, of car bodies) it is common practice to use handheld coated abrasive sheets (for example, sandpaper) or resilient urethane sanding sponges. Handheld coated abrasive sheets are typically used by folding the sheet, and using a linear motion to generate the abrading action. Typical workpiece surfaces include wood, filler, primers, and/or other hard coatings. This mode of abrading generally leads to a relatively aggressive and/or uneven scratch patterns due to uneven pressure created by contact with fingers and/or the palm of the hand. Additionally, many handheld coated abrasive sheets are flat and relatively stiff, making them difficult to handle, especially if abrading contoured or irregular shaped surfaces.

SUMMARY

In one aspect, the present disclosure according to claim 1 provides an abrasive hand pad comprising:

a coated abrasive member comprising an abrasive layer secured to a major surface of a flexible, dense backing, wherein the abrasive layer comprises first abrasive particles and a first binder; and
a nonwoven abrasive member secured to the backing opposite the abrasive layer, wherein the nonwoven abrasive member comprises second abrasive particles secured to a lofty open nonwoven fiber web by a second binder.

In some embodiments, the abrasive layer comprises a make layer, a size layer, and the abrasive particles. In some embodiments, the abrasive layer comprises shaped abrasive composites comprising the first abrasive particles and the first binder. In some embodiments, the coated abrasive member has a plurality of perforations extending through the abrasive layer and the backing.
Abrasive hand pads according to the present disclosure are useful; for example, for abrading a surface of a workpiece. Accordingly, the present disclosure provides a method of abrading a surface of a workpiece, the method comprising frictionally contacting an abrasive hand pad according to the present disclosure with a surface of a workpiece, and moving at least one of the abrasive hand pad or the workpiece to abrade the surface of the workpiece.
Abrasive hand pads according to the present disclosure substantially reduce or eliminate the problem of finger pressure wear patterns while providing the ergonomic benefit of having both abrasives in a single article. In addition they eliminate the constant need to reach for separate coated abrasive and nonwoven abrasive articles during abrading processes.
The features and advantages of the present disclosure will be understood upon consideration of the detailed description as well as the appended claims. These and other features and advantages of the disclosure may be described below in connection with various illustrative embodiments of the disclosure. The above summary is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The Figures and the detailed description which follow more particularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic side view of an exemplary abrasive hand pad 100 according to the present disclosure;
Fig. 2A is a side view of an exemplary coated abrasive member 120A of abrasive article 100;
Fig. 2B is a side view of an alternative exemplary coated abrasive member 120B of abrasive article 100;
Fig. 3A is an perspective view of nonwoven abrasive member 120 of abrasive article 100; and
Fig. 3B is an enlarged view of the nonwoven abrasive member 120 in Fig. 3A.

It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale. Like reference numbers may have been used throughout the figures to denote like parts.

DETAILED DESCRIPTION

Referring now to Fig. 1, an exemplary abrasive hand pad 100 according to the present disclosure comprises coated abrasive member 120 secured to nonwoven abrasive member 150. Optional perforations 105 extend through coated abrasive member 120.
As shown in Fig. 2A, coated abrasive member 120A comprises an abrasive layer 123 secured to major surface 125 of backing 127. Abrasive layer 123 comprises first abrasive particles 131, make layer 133, size layer 137, and optional supersize layer 139. Make layer 133 (and optionally size layer 137) comprises a first binder 135.
Coated abrasives suitable for use as the coated abrasive member include coated abrasives having a flexible, dense backing. As used herein, the term "flexible, dense backing" refers to a backing that is substantially flexible and non-compressible, and does not comprise a foam (for example, an open cell or closed cell foam) or a lofty open nonwoven fiber web. Examples of suitable backings include cloth (for example, woven or knitted), vulcanized fiber, paper, nonwoven fabrics, polymeric films (for example, polyester or polyolefin films), and multilayer combinations thereof. Exemplary cloth backings may be woven, knitted or stitch bonded and may include fibers or yarns of cotton, polyester, rayon, silk, nylon or blends thereof. Exemplary nonwoven backings may comprise cellulosic fibers, synthetic fibers or blends thereof. The flexible, dense backing may comprise a backing treatment including, for example, a presize, subsize, saturant and/or tie layer. Typically, such treatments may be applied in any order.
The make layer can be formed by coating a curable make layer precursor onto a major surface of the backing. The make layer precursor may comprise, for example, glue, phenolic resin, aminoplast resin, urea-formaldehyde resin, melamine-formaldehyde resin, urethane resin, free-radically polymerizable polyfunctional (meth)acrylate (for example, aminoplast resin having pendant alpha, beta-unsaturated groups, acrylated urethane, acrylated epoxy, acrylated isocyanurate), epoxy resin (including bis-maleimide and fluorene-modified epoxy resins), isocyanurate resin, and mixtures thereof. The make layer precursor may be applied by any known coating method for applying a make layer to a backing, including roll coating, extrusion die coating, curtain coating, knife coating, gravure coating, spray coating, and the like.
The basis weight of the make layer utilized may depend, for example, on the intended use(s), type(s) of abrasive particles, and nature of the coated abrasive article being prepared, but generally will be in the range of from 1, 2, 5, 10, or 15 grams per square meter (gsm) to 20, 25, 100, 200, 300, 400, or even 600 gsm. The make layer may be applied by any known coating method for applying a make layer (for example, a make coat) to a backing, including, for example, roll coating, extrusion die coating, curtain coating, knife coating, gravure coating, and spray coating.
Once the make layer precursor is coated on the backing, abrasive particles are applied to and embedded in the make layer precursor (for example, by drop coating and/or electrostatic coating). The abrasive particles can be applied or placed randomly or in a precise pattern onto the make layer precursor.
Exemplary useful abrasive particles include fused aluminum oxide based materials such as aluminum oxide, ceramic aluminum oxide (which may include one or more metal oxide modifiers and/or seeding or nucleating agents), and heat-treated aluminum oxide, silicon carbide, co-fused alumina-zirconia, diamond, ceria, titanium diboride, cubic boron nitride, boron carbide, garnet, flint, emery, sol-gel derived abrasive particles, and blends thereof. Examples of sol-gel abrasive particles include those described in U.S. Patent No. 4,314,827 (Leitheiser et al. ); U.S. Patent No. 4,518,397 (Leitheiser et al. ); U.S. Patent No. 4,623,364 (Cottringer et al. ); U.S. Patent No. 4,744,802 (Schwabel ); U.S. Patent No. 4,770,671 (Monroe et al. ); U.S. Patent No. 4,881,951 (Wood et al. ); U.S. Patent No. 5,011,508 (Wald et al. ); U.S. Patent No. 5,090,968 (Pellow ); U.S. Patent No. 5,139,978 (Wood ); U.S. Patent No. 5,201,916 (Berg et al. ); U.S. Patent No. 5,227,104 (Bauer ); U.S. Patent No. 5,366,523 (Rowenhorst et al. ); U.S. Patent No. 5,429,647 (Larmie ); U.S. Patent No. 5,498,269 (Larmie ); and U.S. Patent No. 5,551,963 (Larmie ). The abrasive particles may be in the form of, for example, individual particles, agglomerates, abrasive composite particles, and mixtures thereof. Exemplary agglomerates are described, for example, in U.S. Patent No. 4,652,275 (Bloecher et al. ) and U.S. Patent No. 4,799,939 (Bloecher et al. ). It is also within the scope of the present disclosure to use diluent erodible agglomerate grains as described, for example, in U.S. Patent No. 5,078,753 (Broberg et al. ). Abrasive composite particles comprise abrasive grains in a binder. Exemplary abrasive composite particles are described, for example, in U.S. Patent No. 5,549,962 (Holmes et al. ).
Coating weights for the abrasive particles may depend, for example, on the specific coated abrasive article desired, the process for applying the abrasive particles, and the size of the abrasive particles, but typically range from 1 to 2000 gsm.
The abrasive particles typically have a size in a range of from 0.1 to about 5000 micrometers, more typically from about 1 to about 2000 micrometers; more typically from about 5 to about 1500 micrometers, more typically from about 100 to about 1500 micrometers, although other sizes may be used.
The abrasive particles are typically selected to correspond to abrasives industry accepted nominal grades such as, for example, the American National Standards Institute, Inc. (ANSI) standards, Federation of European Producers of Abrasive Products (FEPA) standards, and Japanese Industrial Standard (JIS) standards. Exemplary ANSI grade designations (that is, specified nominal grades) include: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 36, ANSI 40, ANSI 50, ANSI 60, ANSI 80, ANSI 100, ANSI 120, ANSI 150, ANSI 180, ANSI 220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400, and ANSI 600. Exemplary FEPA grade designations include: P8, P12, P16, P24, P36, P40, P50, P60, P80, P100, P120, P180, P220, P320, P400, P500, 600, P800, P1000, and P1200. Exemplary JIS grade designations include: JIS8, JIS12, JIS16, JIS24, JIS36, JIS46, JIS54, JIS60, JIS80, JIS100, JIS150, JIS180, JIS220, JIS240, JIS280, JIS320, JIS360, JIS400, JIS400, JIS600, JIS800, JIS1000, JIS1500, JIS2500, JIS4000, JIS6000, JIS8000, and JIS10,000.
Once the abrasive particles have been embedded in the make layer precursor, it is at least partially cured in order to preserve orientation of the mineral during application of the size layer precursor. Typically, this involves B-staging the make layer precursor, but more advanced cures may also be used if desired. B-staging may be accomplished, for example, using heat and/or light and/or use of a curative, depending on the nature of the make layer precursor selected.
Next, the size layer precursor is applied over the at least partially cured make layer precursor and abrasive particles. The size layer can be formed by coating a curable size layer precursor onto a major surface of the backing. The size layer precursor may comprise, for example, glue, phenolic resin, aminoplast resin, urea-formaldehyde resin, melamine-formaldehyde resin, urethane resin, free-radically polymerizable polyfunctional (meth)acrylate (for example, aminoplast resin having pendant alpha, beta-unsaturated groups, acrylated urethane, acrylated epoxy, acrylated isocyanurate), epoxy resin (including bis-maleimide and fluorene-modified epoxy resins), isocyanurate resin, and mixtures thereof. The size layer precursor may be applied by any known coating method for applying a size layer to a backing, including roll coating, extrusion die coating, curtain coating, knife coating, gravure coating, spray coating, and the like. If desired, a presize layer precursor or make layer precursor according to the present disclosure may be also used as the size layer precursor.
The basis weight of the size layer will also necessarily vary depending on the intended use(s), type(s) of abrasive particles, and nature of the coated abrasive article being prepared, but generally will be in the range of from 1 or 5 gsm to 300, 400, or even 500 gsm, or more. The size layer precursor may be applied by any known coating method for applying a size layer precursor (for example, a size coat) to a backing including, for example, roll coating, extrusion die coating, curtain coating, and spray coating.
Once applied, the size layer precursor, and typically the partially cured make layer precursor, are sufficiently cured to provide a usable coated abrasive article. In general, this curing step involves thermal energy, but this is not a requirement. Useful forms of thermal energy include, for example, heat and infrared radiation. Exemplary sources of thermal energy include ovens (for example, festoon ovens), heated rolls, hot air blowers, infrared lamps, and combinations thereof.
In addition to other components, binder precursors, if present, in the make layer precursor and/or presize layer precursor of coated abrasive articles according to the present invention may optionally contain catalysts (for example, thermally activated catalysts or photocatalysts), free-radical initiators (for example, thermal initiators or photoinitiators), curing agents to facilitate cure. Such catalysts (for example, thermally activated catalysts or photocatalysts), free-radical initiators (for example, thermal initiators or photoinitiators), and/or curing agents may be of any type known for use in coated abrasive articles including, for example, those described herein.
The make and size layer precursors may contain optional additives, for example, to modify performance and/or appearance. Exemplary additives include grinding aids, fillers, plasticizers, wetting agents, surfactants, pigments, coupling agents, fibers, lubricants, thixotropic materials, antistatic agents, suspending agents, and/or dyes. Exemplary grinding aids, which may be organic or inorganic, include waxes, halogenated organic compounds such as chlorinated waxes like tetrachloronaphthalene, pentachloronaphthalene, and polyvinyl chloride; halide salts such as sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides, potassium chloride, magnesium chloride; and metals and their alloys such as tin, lead, bismuth, cobalt, antimony, cadmium, iron, and titanium; and the like. Examples of other grinding aids include sulfur, organic sulfur compounds, graphite, and metallic sulfides. A combination of different grinding aids can be used. Exemplary antistatic agents include electrically conductive material such as vanadium pentoxide (for example, dispersed in a sulfonated polyester), humectants, carbon black and/or graphite in a binder. Examples of useful fillers for this invention include silica such as quartz, glass beads, glass bubbles and glass fibers; silicates such as talc, clays (for example, montmorillonite) feldspar, mica, calcium silicate, calcium metasilicate, sodium aluminosilicate, sodium silicate; metal sulfates such as calcium sulfate, barium sulfate, sodium sulfate, aluminum sodium sulfate, aluminum sulfate; gypsum; vermiculite: wood flour; aluminum trihydrate; carbon black; aluminum oxide; titanium dioxide; cryolite; chiolite; and metal sulfites such as calcium sulfite.
Optionally a supersize layer may be applied to at least a portion of the size layer. If present, the supersize typically includes grinding aids and/or anti-loading materials. The optional supersize layer may serve to prevent or reduce the accumulation of swarf (the material abraded from a workpiece) between abrasive particles, which can dramatically reduce the cutting ability of the coated abrasive article. Useful supersize layers typically include a grinding aid (for example, potassium tetrafluoroborate), metal salts of fatty acids (for example, zinc stearate or calcium stearate), salts of phosphate esters (for example, potassium behenyl phosphate), phosphate esters, urea-formaldehyde resins, mineral oils, crosslinked silanes, crosslinked silicones, and/or fluorochemicals. Useful supersize materials are further described, for example, in U.S. Patent No. 5,556,437 (Lee et al. ). Typically, the amount of grinding aid incorporated into coated abrasive products is about 50 to about 400 gsm, more typically about 80 to about 300 gsm. The supersize may contain a binder such as for example, those used to prepare the size or make layer, but it need not have any binder.
As shown in Fig. 2B, coated abrasive member 120B may also comprise a structured abrasive layer 124 secured to major surface 125 of backing 127. Structured abrasive layer 124 comprises a plurality of shaped abrasive composites 128, each comprising first abrasive particles 131 dispersed in first binder 135. In making coated abrasive members, a slurry comprising a binder precursor and abrasive particles may be applied to a tool having a plurality of precisely-shaped cavities therein, thereby urging the slurry into at least a portion of the cavities. The slurry is then at least partially polymerized and adhered to the tie layer, for example, by adhesive or addition polymerization of the slurry. Examples of suitable binder precursors and abrasive particles include those listed above for use in the make and size layer precursors.
The abrasive composites may have a variety of shapes including, for example, those shapes selected from the group consisting of cubic, block-like, cylindrical, prismatic, pyramidal, truncated pyramidal, conical, truncated conical, cross-shaped, and hemispherical. The abrasive composites may be precisely shaped or not.
Coated abrasives suitable for use as the coated abrasive member are widely available from commercial sources including, for example, under the trade designations "TRIZACT", "STIK-IT" and "WET OR DRY" from 3M Company.
The coated abrasive member may be continuous, without perforations, or it may be perforated, for example, to facilitate swarf removal as described in U.S. Patent No. 7,628,829 (Woo et al. ), U.S. Patent No. 7,393,269 (Rambosek et al. ); U.S. Patent No. 7,329,175 (Woo et al. ); U.S. Patent No. 7,258,705 (Woo et al. ); and U.S. Patent No. 7,244,170 (Woo et al. ). If present, the perforations may extend through the abrasive layer and the backing such that essentially no abrasive particles and binder are present on the surface of the perforations within the backing. In typical embodiments, essentially no abrasive particles are adhered to the backing on the side opposite the abrasive layer, although this is not a requirement.
Further details concerning techniques and materials for making coated abrasive sheets having make and size layers or structured abrasive layers may be found, for example, in U.S. Patent No. 4,734,104 (Broberg ); U.S. Patent No. 4,744,802 (Schwabel ); U.S. Patent No. 4,751,138 (Tumey et al. ); U.S. Patent No. 4,770,671 (Monroe et al. ); U.S. Patent No. 4,881,951 (Wood et al. ); U.S. Patent No. 5,014,468 (Ravipati et al. ); U.S. Patent No. 5,435,816 (Spurgeon et al. ); U.S. Patent No. 5,498,269 (Larmie ); U.S. Patent No. 5,152,917 (Pieper et al. ); U.S. Patent No. 5,201,916 (Berg et al. ); U.S. Patent No. 5,203,884 (Buchanan et al. ); U.S. Patent No. 5,304,223 (Pieper et al. ); U.S. Patent No. 5,366,523 (Rowenhorst et al. ); U.S. Patent No. 5,378,251 (Culler et al. ); U.S. Patent No. 5,436,063 (Follett et al. ); U.S. Patent No. 5,549,962 (Holmes et al. ); U.S. Patent No. 5,681,217 (Hoopman et al. ); U.S. Patent No. 5,855,632 (Stoetzel et al. ); and U.S. Patent No. 5,942,015 (Culler et al. ).
Referring now to Figs. 3A and 3B, nonwoven abrasive member 150 comprises second abrasive particles 165 secured to a lofty open nonwoven fiber web 157 by a second binder 161. Nonwoven abrasive member 150 is secured to backing 127 opposite abrasive layer 123.
The term "lofty open nonwoven fiber web" refers to a porous layer of nonwoven web material composed of a plurality of randomly oriented fibers, the layer having a thickness (prior to corrugation) of at least 150 micrometers, usually at least 500 micrometers (0.5 mm). In most embodiments, lofty open nonwoven fiber web 12 is at least 3.175 mm (1/8 inch) thick. Common thicknesses for the lofty open nonwoven fiber web are, for example, 6.35 mm (1/4 inch) to 12.7 mm (1/2 inch). The fiber web may have a prebond resin thereon.
Exemplary fiber materials include: thermoplastic polymers that are known to form fibers such as polyolefins (for example, polyethylenes, polypropylenes, and polybutylenes), polyamides (for example, nylon 6. nylon 6/6. and nylon 10), polyesters (for example, polyethylene terephthalate), copolymers containing acrylic monomers, and blends and copolymers thereof. Semi-synthetic fibers (such as acetate fibers), natural fibers (such as cotton), regenerated fibers (such as rayon), and other non-thermoplastic fibers can also be used. Blends of the foregoing fibers may be used.
The fibers typically have a denier of from about 6 to about 200, more usually about 50 to about 100. The basis weight of the lofty nonwoven substrate 12 (fibers only, with no prebond binder layer) is preferably from about 50 grams per square meter to about 1 kilogram per square meter, and more preferably from about 150 to about 600 grams per square meter. Typically, a prebond binder is applied to the lofty open nonwoven substrate to lock the fibers. The basis weight of the lofty open nonwoven fiber web, with prebond binder, is usually from about 100 grams per square meter to about 2 kilogram per square meter, and more preferably from about 300 grams to about 1.5 kilogram per square meter.
The lofty open nonwoven fiber web can be prepared by any suitable web forming operation. For example, the lofty nonwoven webs may be carded, spunbonded, spunlaced, melt blown, air laid, creped, or made by other processes as are known in the art.
The lofty open fiber web is coated with abrasive particles and a binder precursor. The binder precursor and abrasive particles may be applied as a mixture of may be applied to the fiber web in separate steps. For example, the binder precursor may be applied to the fiber web and then the abrasive particles deposited on the binder precursor. Once coated, the binder precursor (with abrasive particles) is cured. Generally, the resultant binder and ab3rasive particles are deposited through out the nonwoven fiber web, although the distribution may not be uniform. Exemplary binder precursors and abrasive particles include those listed hereinabove in regard to the coated abrasive member.
Suitable nonwoven abrasive members are widely available commercially and include, for example, those available under the trade designation "SCOTCH-BRITE" from 3M Company.
Further details concerning nonwoven abrasive members may be found, for example, in U.S. Patent No. 2,958,593 (Hoover et al. ); U.S. Patent No. 5,591,239 (Larson et al. ); and U.S. Patent No. 6,017,831 (Beardsley et al. ).
The coated abrasive member and the nonwoven abrasive member are secured to one another, typically by means of glue or adhesive (for example, a pressure-sensitive and/or thermosetting adhesive) or adhesive tape (for example, double-sided pressure-sensitive adhesive coated tape), although mechanical methods (for example, ultrasonic welding or stitching) may also be used.
Hybrid abrasive hand pads according to the present disclosure may be used in combination with a lubricant such as water or oil. If water is used, it may contain a surfactant (for example, anionic, nonionic, or cationic surfactant) or a combination thereof.
Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight.

EXAMPLE 1

A hybrid abrasive hand pad, 4 inches (10 cm) x 6 inches (15 cm), was prepared by laminating a piece of nonwoven abrasive sheet (available as MULTI-FLEX ABRASIVE SHEET ROLL S-UFN from 3M Company of St. Paul, MN) to the backing of a piece of a coated abrasive sheet (grade P320, available as 216U P320 9X11 GOLD FRECUT SHEET from 3M Company) using double-sided adhesive tape such that the nonwoven abrasive piece was coextensive with the coated abrasive piece.

Various abrasive articles (as indicated in Table 1) were used by hand to abrade a steel panel coated with DUPONT 1147S 2K URETHANE PRIMER-FILLER automotive primer obtained from DuPont Automotive Finishes of Troy, MI. using a linear motion for a total of 20 strokes. The average depth of scratch (Ra) was measured with a FEDERAL POCKET SURF III profilometer (obtained from Federal Products Corp. of Providence, R1) and recorded as an average of 5 independent measurements. Results are reported in Table 1 (below).

TABLE 1

	ABRASIVE TYPE	TYPE	Ra, microinches, (micrometers)	Standard Deviation, microinches, (micrometers)
COMPARATIVE EXAMPLE A	216U P320 9X11 GOLD FRECUT SHEET	coated abrasive	54	4.6
COMPARATIVE EXAMPLE A	216U P320 9X11 GOLD FRECUT SHEET	coated abrasive	(1.4)	(0.11)
COMPARATIVE EXAMPLE B	MULTI-FLEX ABRASIVE SHEET ROLL S-UFN	nonwoven abrasive	23	2.6
COMPARATIVE EXAMPLE B	MULTI-FLEX ABRASIVE SHEET ROLL S-UFN	nonwoven abrasive	(0.58)	(0.066)
EXAMPLE 1	Hybrid Abrasive Hand pad	coated abrasive side	38	2.1
		coated abrasive side	(0.97)	(0.053)
		nonwoven abrasive side	18	1.9
		nonwoven abrasive side	(0.46)	(0.048)

EXAMPLE 2

A hybrid abrasive hand pad, prepared as in Example 1, and a coated abrasive sheet (grade P320, available as 216U P320 9X11 GOLD FRECUT SHEET) were evaluated using a hand operated pneumatic orbital sanding device (obtained as HUTCHINS INDUSTRIAL PNEUMATIC SPEED SANDER, MODEL 3004 from Hutchins Manufacturing Company of Pasadena, CA). The workpiece was a 18 inches (46 cm) by 24 inches (61 cm) metal cold roll steel panel coated with DUPONT 1147S 2K URETHANE PRIMER-FILLER automotive primer. The panel was abraded for a total of 7 minutes using a reciprocating (back and forth) motion, with measurements made at specific intervals. Cut measurements were made by weighing the amount of material removed from the panel over the specified time interval, and depth of scratch (Ra) was measured with a FEDERAL POCKET SURF III profilometer and recorded as an average of 5 independent measurements. Results are reported in Table 2 (below).

TABLE 2

	ABRASIVE ARTICLE
	216U P320 9X11 GOLD FRECUT SHEET,		HYBRID ABRASIVE HAND PAD,
	coated abrasive surface		coated abrasive surface
TIME, sec	CUMULATIVE CUT, grams	Ra, microinches, (micrometers)	CUMULATIVE CUT, grams	Ra, microinches, (micrometers)
30	2.70	44.4	2.1	34.2
		(1.13)		(0.869)
120	9.70	43.4	7.7	34.8
		(1.10)		(0.884)
300	18.50	43.6	17.4	35.4
		(1.11)		(0.899)
420	21.50	41.2	20.9	34.6
		(1.04)		(0.879)

EXAMPLE 3

The backing of a coated abrasive sheet, grade P80 available as 3M STIKIT GREEN CORPS SHEET GRADE 80D from 3M Company was adhered to a piece of nonwoven abrasive sheet (available as MULTI-FLEX ABRASIVE SHEET ROLL S-UFN from 3M Company) using spray adhesive (available as HI-STRENGTH 90 SPRAY ADHESIVE from 3M Company) such that the two layers were coextensive.
Pieces (2¾ inches (7.0 cm) by 17½ inches (44 cm)) of the hybrid abrasive hand pad and the coated abrasive sheet alone were evaluated using a pneumatic reciprocating straight-line hand operated sander obtained as HUTCHINS 2000- HUSTLER STRAIGHT LINE SANDER from Hutchins Manufacturing Company). The workpiece was an 18 inches (46 cm) by 24 inches (61 cm) cold roll steel panel, which was coated with 1/4 inch (0,6 cm) of cured (24 hrs at room temperature) automotive body filler, available as 3M ZEBRA ADVANCED FINISHING LIGHTWEIGHT FILLER from 3M Company.

The panel was abraded for a total of 7 minutes using a reciprocating (back and forth) motion, with measurements made at specific intervals. Cut measurements were made by weighing the amount of material removed from the panel over the specified time interval, and depth of scratch (R_a) was measured with a FEDERAL POCKET SURF III profilometer and recorded as an average of 5 independent measurements. Results are reported in Table 3 (below).

TABLE 3

	ABRASIVE ARTICLE
	3M STIKIT GREEN CORPS SHEET GRADE 80D,		HYBRID ABRASIVE HAND PAD,
	coated abrasive surface		coated abrasive surface
TIME, sec	CUMULATIVE CUT, grams	R_a, microinches (micrometers)	CUMULATIVE CUT, grams	R_a, microinches (micrometers)
30	2.5	218	2.3	176
		(5.53)		(4.47)
120	8.8	203	8.1	173
		(5.16)		(4.39)
300	16.3	195	16.7	165
		(4.95)		(4.19)
420	20.8	186	21.5	169
		(4.72)		(4.29)

All examples given herein are to be considered non-limiting unless otherwise indicated. Various modifications and alterations of this disclosure may be made by those skilled in the art without departing from the scope of this disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth herein, but by the appended claims.

Claims

A hybrid abrasive hand pad (100) comprising:
a coated abrasive member (120) comprising an abrasive layer (123) secured to a major surface (125) of a flexible, dense backing (127) wherein the abrasive layer comprises first abrasive particles (131) and a first binder (135) and

a nonwoven abrasive member (150) secured to the backing (127) opposite the abrasive layer (123) wherein the nonwoven abrasive member comprises second abrasive particles (165) secured to a lofty open nonwoven fiber web (157) by a second binder (161).
The hybrid abrasive hand pad of claim 1, wherein the abrasive layer comprises a make layer (133), a size layer (137) and the first abrasive particles (131).
The hybrid abrasive hand pad of claim 1, wherein the abrasive layer comprises shaped abrasive composites (128) comprising the first abrasive particles (131) and the first binder (135).
The hybrid abrasive hand pad of claim 1, wherein the coated abrasive member has a plurality of perforations (105) extending through the abrasive layer and the backing.
A method of abrading a surface of a workpiece, the method comprising frictionally contacting the hybrid abrasive hand pad of claim 4 with the surface of the workpiece, and moving at least one of the abrasive hand pad or the workpiece to abrade the surface of the workpiece.
A method of abrading a surface of a workpiece, the method comprising frictionally contacting the hybrid abrasive hand pad of claim 1 with the surface of the workpiece, and moving at least one of the abrasive hand pad or the workpiece to abrade the surface of the workpiece.