WO2011059935A1

WO2011059935A1 - Rotary buffing pad

Info

Publication number: WO2011059935A1
Application number: PCT/US2010/055905
Authority: WO
Inventors: Gregory A. Koehnle; Scott R. Culler; Brant A. Moegenburg; Schoen A. Schuknecht; Edward J. Woo
Original assignee: 3M Innovative Properties Company
Priority date: 2009-11-12
Filing date: 2010-11-09
Publication date: 2011-05-19
Also published as: US20120258652A1; CN102639299A; EP2498951A1; RU2012116583A; BR112012011210A2

Abstract

Provided is a flat-faced buffing pad that includes a plurality of apertures of variable size. The apertures are generally larger in the areas toward the center of the pad, while being generally smaller in the areas toward the periphery of the pad. Some embodiments further include apertures disposed along one or more concentric circular rings located along the front surface and generally symmetrical about the rotation axis. These configurations of apertures provide both superior cut performance and superior finish. Moreover, these configurations minimize several undesirable aspects in a polishing operation, such as slinging of the polishing compound, vibration, wobbling, and drag felt by the operator as the rotary pad slides across the surface to be polished.

Description

ROTARY BUFFING PAD

Field of the Invention

Buffing pads are provided for polishing the surface of a workpiece. More particularly, patterned rotary buffing pads are provided for polishing the surface of a workpiece. Background

The visual appearance of painted surfaces, for example, exterior painted automotive and marine surfaces is an important aesthetic property. Original equipment manufacturer and aftermarket industries have devoted many resources to the development and application of paint systems that provide aesthetic properties such as, for example, low haze and good distinctness of image. It is commonplace for vehicle and boat

manufacturers to use a base coat and clear coat paint system. The base coat provides the desired color, while the clear coat, which is applied over the base coat, provides a transparent scratch and chip-resistant protective coat. Such paint systems, however, have the tendency to magnify defects (for example, scratches, haze, and dust nibs) in either the base coat or the clear coat. One common method for imparting, or restoring, a high quality appearance to the paint system uses a multi-step process.

First, the defects are abraded using a coated abrasive product with a fine abrasive particle size, for example, sandpaper, or a structured abrasive article. This step provides rapid removal of the defects, but typically leaves scuff, or "swirl" marks, and sometimes scratches, that need to be removed. Next, the swirl marks are removed by buffing using a buffing composition. The buffing composition is typically an aqueous or petroleum based medium containing abrasive particles of smaller size than the abrasive particles used in the coated abrasive article. However, depending of the paint system, the buffing step may result in a surface with a hazy appearance. The hazy appearance is removed by a finishing step in which the hazy portion of the paint system is buffed with a finishing composition. The finishing composition is typically an aqueous or petroleum based medium containing abrasive particles of smaller size than the abrasive particles used in the buffing

composition. Finally, residue from the buffing and/or finishing compositions is removed, for example, with a soft cloth, thereby producing an aesthetically appealing finish substantially free of surface residue.

Buffing pads used in the above polishing steps are generally compressible to allow even pressure to be applied across the buffing surfaces. Such pads are often made from either wool or a polymeric foam. While the polishing steps may be a manual process, it can be facilitated by attaching the buffing pad to an electric or air-driven pneumatic power tool. As used herein, "polishing steps" include any of the steps used in restoring or improving a surface, including compounding, buffing, and finishing steps.

The performance of a buffing pad may be appraised on a number of factors. First, the buffing pad provides a certain level of cut performance (or "cut"), defined as the rate at which the moving pad removes surface defects. Cut performance should be adequately high to allow polishing to be completed within a reasonable amount of time. Second, the buffing pad provides a certain level of finish. The finish provided by a buffing operation is defined by the smoothness of the resulting surface and can be quantified by measuring "haze". Haze decreases with increasing smoothness, and thus should be as low as possible. Third, the rotary buffing pad can be appraised on user experience. Here, it is desirable for a rotary buffing pad to engage the surface to be polished in a controlled manner to reduce the incidence of jerking or other unpredictable motions (known as "chatter") of the power tool during the polishing process. This assists the operator in maintaining a high degree of control over the orientation of the pad and helps avoid inadvertent gouging of the workpiece. Summary

In buffing applications, it is often a challenge to achieve both good cut and fine finish simultaneously. Modifications to the buffing pad or abrasive compound that enhance cutting performance often lead to a coarser finish. Conversely, modifications which lead to a finer finish often also tend to reduce the rate of abrasion and thereby degrade cut performance. The apparent inverse relationship between cut performance and finish has been a source of frustration to many of skill in the art. Herein are provided rotary buffing pads which overcome the dilemma faced by one desiring to achieve both superior cut performance and a fine finish. This combination of advantages is provided by using a flat-faced buffing pad that includes a plurality of apertures of variable size. The apertures are generally larger in the areas toward the center of the pad, while being generally smaller in the areas toward the periphery of the pad. This synergistic arrangement of large and small apertures provides both superior cut performance and a superior finish.

This configuration further provides other unexpected advantages over conventional foam buffing pads. First, the center apertures advantageously capture excess abrasive composition thereby reducing the amount of liquid sling during the buffing process and therefore reducing both waste and clean up time after the operation is completed. Second, the amount of vibration, or "chatter", felt by the operator during the buffing process is maintained at low levels. Reduced vibration in turn leads to reduced fatigue and enhanced operator comfort. Third, locating the larger apertures toward the center of the pad improves operator control by reducing the drag resistance due to the center of the pad and also preventing the pad from wobbling during the buffing process. Since wobbling can cause the buffing pad to jump or jerk across the surface, this configuration improves operator control and reduces the risk of damaging the surface being polished.

In one aspect, a rotary buffing pad is provided, comprising a substrate having a front surface, back surface, and a rotation axis perpendicular to the front and back surfaces, the substrate further comprising an inner region adjacent to and surrounding the rotation axis, an outer region surrounding the inner region, a plurality of first apertures having a first average size located within the inner region and extending from the front surface toward the back surface; and a plurality of second apertures having a second average size located within the outer region and extending from the front surface toward the back surface, wherein the first average size is larger than the second average size.

In another aspect, a rotary buffing pad is provided comprising a substrate having a front surface, back surface, and a rotation axis perpendicular to the front and back surfaces, the substrate further comprising an inner region adjacent to and surrounding the rotation axis, an outer region surrounding the inner region, a plurality of first apertures having a first aperture density located within the inner region and extending from the front surface toward the back surface, and a plurality of second apertures having a second aperture density located within the outer region and extending from the front surface toward the back surface, wherein the first aperture density is larger than the second aperture density.

In still another aspect, a rotary buffing pad is provided comprising a substrate having a front surface, back surface, and a rotation axis perpendicular to the front and back surfaces, the substrate further comprising an inner region adjacent to and surrounding the rotation axis, an outer region surrounding the inner region, a plurality of first apertures having a first average size located within the inner region and extending from the front surface toward the back surface, a plurality of second apertures having a second average size located within the outer region and extending from the front surface toward the back surface, wherein the first average size is larger than the second average size, and wherein the outer region further comprises at least one annular region and wherein the plurality of second apertures further comprises a second subset of second apertures located in the at least one annular region, the second subset extending from the front surface toward the back surface and being disposed along at least one circular ring, each circular ring being coplanar with the front surface and generally symmetrical about the rotation axis.

In yet another aspect, a rotary buffing pad is provided comprising a substrate having a front surface, back surface, and a rotation axis perpendicular to the front and back surfaces, the substrate further comprising an inner region adjacent to and surrounding the rotation axis, an outer region surrounding the inner region, and a plurality of apertures extending from the front surface toward the back surface, wherein the apertures have a distribution of sizes and the apertures having relatively large size are predominantly located in the inner region relative to the outer region. Brief Description of the Drawings

FIG. 1 is a front view of a buffing pad according to one exemplary embodiment of the invention;

FIG. 2 is an elevational cross-sectional view of the buffing pad along the line 2-2 in FIG. 1;

FIG. 3 is a perspective view of the buffing pad in FIGS. 1-2, looking at the back surface; FIG. 4 is a magnified fragmentary front view of the buffing pad shown in the rectangular inset 4 of FIG. 1; and

FIG. 5 is a front view of a buffing pad according to an alternative embodiment of the invention.

DEFINTIONS:

As used herein:

"Aperture" refers to an opening in an article which may or may not penetrate through the article;

"Aperture spacing" refers to the center-to-center distance between two neighboring apertures;

"Compressible" refers to a material that reduces in volume upon application of pressure; "Diameter" refers to the largest lateral dimension; and

"Aperture density" refers to the total population of apertures located within a given region divided by the total surface area of that region.

Detailed Description

The following description is directed to buffing pads useful for removing defects from a surface and polishing the surface to a fine finish. These buffing pads are especially useful in the automotive and marine applications, where there is a need to polish a painted exterior surface to produce a glossy, aesthetic appearance. However, the buffing pads are not limited to these applications. For example, they may be useful on any other painted surfaces or even non-painted surfaces, and are not limited to polishing operations on any particular type of article. For example, workpiece surfaces may include marbled, varnished, composite, or gel coated surfaces.

Moreover, buffing pads are not limited to a specific method of use. Any of a wide variety of abrasive polishes and compounds, both in liquid and solid form, may be advantageously used with these buffing pads to achieve a desirable surface finish. Various power tools may be used to generate the relative motion between the buffing pad and the surface to be polished. Moreover, the application of these pads is not restricted to any particular stage of a workflow used to polish an article. For example, they may be used as a first step, intermediate step, or last step of a multi-step polishing method. Alternatively, these buffing pads may be used in a single-step polishing method.

An exemplary buffing pad according to one embodiment is illustrated in FIGS. 1-4 and designated by the numeral 100. As shown in front view by FIG. 1, the buffing pad 100 has a substrate 102 with a front surface 104. The front surface 104 is generally flat and has a circular shape in plan view. While not shown here, the front surface 104 may also assume non-circular shapes. As shown, the substrate 102 further includes a side surface 106 and a back surface 108. Optionally and as shown, a backing layer 110, denoted by the dashed lines, extends across nearly all of the back surface 108. In one exemplary embodiment, the buffing pad 100 has an overall diameter of about 8.0 inches (20.3 centimeters (cm)) and a thickness of about 1.5 inches (3.8 cm). In this description, the "front" is defined as the side that contacts the workpiece and the "back" is the opposite surface.

When used in a buffing operation, the buffing pad 100 rotates about a rotation axis 112, shown in FIGS. 1 and 2. The rotation axis 112 is perpendicular to the front surface 104 and passes through the center of the buffing pad 100. In the embodiment shown, the substrate 102 is symmetrically disposed about the rotation axis 112 to help minimize wobbling of the buffing pad 100 during operation.

In some embodiments, the substrate 102 is made from a compressible material, such as a polymeric foam. Exemplary substrates having this property include open-celled polyurethane foams. Open-celled foams are advantageous in that they can be made soft and compliant and do not significantly expand in the side directions when compressed from the top and bottom directions. Open-celled foams may also allow limited

permeability to the buffing polish or compound material. Such permeability may advantageously improve overall retention of the polish or compound material on the pad

100 during a polishing operation. Other commercial foams are also possible, such as those disclosed in issued U.S. Patent No. 4,962,562 (Englund, et al). In exemplary

embodiments, the stiffness of the substrate 102, as measured by the pressure required to produce a compression to 25% of original volume (or 25% Compression Load Deflection), ranges from 0.3 to 1 pound per square inch (2.1 to 6.9 kiloPascals (kPa)).

The optional backing layer 110 preferably has a flexural modulus greater than that of the substrate 102 and augments the stiffness along the back side of the buffing pad 100. As increasing the stiffness of the backing layer 110 generally increases the rate of cut, the flexural modulus can be tailored to provide the rate of cut desired for the application. The backing layer 110 can be coupled to the back surface 108 of the substrate 102 by physical means such as thermal lamination. Alternatively, the backing layer 110 may be adhesively bonded to the substrate 102.

Optionally, the backing layer 110 may include a fibrous material, such as a scrim or non-woven material. Advantageously, the fibrous material can facilitate coupling the buffing pad 100 to a power tool. In some embodiments, for example, the backing layer 100 includes one-half of a hook and loop attachment system, the other half being disposed on a plate affixed to the power tool. Such an attachment system secures the buffing pad 100 to the power tool while allowing convenient attachment and removal of pads between operations.

As particularly shown in FIG. 1, the substrate 102 includes two mutually exclusive regions, an inner region 114 and an outer region 116. The inner region 114, defined as the portion of the substrate 102 located within the hexagonal dashed loop A', is both adjacent to and surrounding the rotation axis 112. In some embodiments, the inner region 114 is symmetrically disposed about the axis 112. While the inner region 114 depicted in FIG. 1 happens to have a hexagonal shape, other shapes (for example, a square, circle, or octagon) are also possible. Preferably, the inner region 114 has a diameter ranging from 20 to 40 percent of the overall diameter of the substrate 102. The outer region 116 is defined as the portion of the substrate 102 located outside of the dashed loop A'. The outer region 116 surrounds the inner region 114 and is both contiguous and concentric with the inner region 114.

It is noted here that both the inner and outer regions 114,116 are solid three dimensional shapes. Therefore, these regions 114,116 are defined not only by the visible areas of the front surface 104 shown in FIG. 1 but also those portions of the substrate 102 located directly thereunder (i.e. beneath the plane of the page in perpendicular view). That is, the regions 114 and 116 include the front surface 104 of the substrate 102 and also have the depth or thickness of the substrate 102.

A plurality of first apertures 120 and a plurality of second apertures 122 extend from the front surface 104 toward the back surface 108 at different locations along the inner and outer regions 114,116 of substrate 102. The plurality of first apertures 120 include all of the apertures present within the inner region 1 14. Optionally and as shown, the first apertures 120 have a generally uniform size and shape and are distributed evenly across the inner region 114 in a close packed (e.g. square, hexagonal) arrangement such that there is a constant spacing between neighboring apertures 120. As an alternative, the apertures 120 may be uniformly spread across the front surface 104 but randomized with irregular spacing between neighboring apertures 120. As another alternative, the apertures 120 may have an overall distribution that is non-uniform across the inner region 114.

Optionally and as shown in this embodiment, the plurality of second apertures 122 includes first and second subsets 123,124 of apertures. The first and second subsets

123,124 of apertures include all of the apertures present within the outer region 116, and are distinguishable from each other based on having different arrangements across the front surface 104 and different size/shape characteristics. Although both subsets 123,124 of apertures are shown, the outer region 116 may include only the first subset 123 or only the second subset 124.

As shown in FIG. 1, the first subset 123 of the second apertures 122 are arranged in a series of discrete and replicated polygonal groupings (or clusters) that are spaced apart from each another. In this particular example, each grouping is hexagonal in shape and consists of seven apertures each having the same size and shape and being equidistant from its closest neighboring aperture(s). The hexagonal groupings shown here are exemplary, however, and other polygonal or even circular groupings can also be used. As another alternative, the first subset 123 can be evenly distributed across the outer region 116 in a configuration similar to that of the first apertures 120. Although not shown here, the first subset 123 can include all of the apertures present within the outer region 114.

Optionally and as shown in FIG. 1, the second subset 124 of the second apertures

122 are disposed along three generally circular rings 140 located within the outer region 116. FIG. 4 is a magnified view of the rectangular inset shown in FIG. 1 and shows the outermost ring 140 in more detail. As shown, the second subset 124 of apertures are located in an annular region 118 within in the outer region 116. The annular region 118 is defined herein as the portion of the outer region 116 bounded between the circular dashed lines B'-B' and B"-B", shown in fragmentary view in FIG. 4. While not shown in their entirety, the lines B'-B' and B"-B" are imaginary concentric circles located on the front surface 104 and symmetrically disposed about the rotation axis 112. Like the inner and outer regions 114,116, the annular region 118 is a three-dimensional shape that includes not only the portions of the front surface 104 located between the lines B'-B' and B"-B", but also portions of the substrate 102 located directly thereunder (i.e. beneath the plane of the page in perpendicular view). Although exactly three rings 140 are shown in FIG. 1, more or fewer than three rings are also possible. Optionally but not shown here, the second subset 124 can include all of the apertures present within the outer region 114.

In the embodiment shown, the second subset 124 of apertures have a generally uniform aperture diameter. In other words, the diameters of the apertures 124 are not only generally uniform along each individual ring 140 but also generally uniform across all three of the rings 140. Further, neighboring apertures 124 display a certain spacing (as measured between the centers of the apertures) which is generally uniform across the rings 140. Preferably, the ratio between the certain diameter to the certain spacing is at least 0.2. More preferably, the ratio between the certain diameter to the certain spacing is at least 0.3. Most preferably, the ratio between the certain diameter to the certain spacing is at least 0.35. As shown in FIG. 1, the three rings 140 are coplanar with the front surface 104, concentric with each other and symmetrically disposed about the rotation axis 112. Optionally, the three rings 140 are evenly spaced apart from each other in radial directions, although this need not be the case.

FIG. 2 shows the apertures 120,123,124 in cross-section, the cross-section being taken along cutting plane 3-3 in FIG. 1. As can be seen in FIG. 2, the apertures 120,122 within the substrate 102 have a distribution of sizes, where the plurality of first apertures 120 within the inner region 114 have an average size larger than that of the plurality of second apertures 122 within the outer region 116. In other words, the apertures 120,122 of relatively large average size are predominantly located in the inner region 114 relative to the outer region 116.

The "size" of a given aperture, as used herein, can refer to any dimension of the aperture. For example, the size may represent the diameter, perimeter, inner surface area, or depth of the aperture, volume occupied by the aperture, or combinations thereof. In FIG. 2, for example, both the average diameter and average depth of the plurality of first apertures 120 is larger than those of the plurality of second apertures 122. Likewise in this embodiment, the average volume occupied by the plurality of first apertures 120 within the inner region 114 is larger than the average volume occupied by the plurality of second apertures 122 within the outer region 116.

In exemplary embodiments, the plurality of first apertures 120 have an average depth ranging from 8 to 12 mm, an average diameter ranging from 2 to 4 mm, and average occupied volume ranging from 25 to 150 cubic mm. In other embodiments, the first subset 123 of apertures have an average depth ranging from 3.5 to 7.5 mm, an average diameter ranging from 3 to 5 mm, and average occupied volume ranging from 25 to 147 cubic mm. In still other embodiments, the second subset 124 of apertures have an average depth ranging from 9 to 13 mm, an average diameter ranging from 0.5 to 1.5 mm, and average occupied volume ranging from 1.6 to 25 cubic mm.

In addition to differences in dimensions, the aperture density (in apertures per unit area) of the plurality of first apertures 120 over the front side of the inner region 114 is greater than that of the plurality of second apertures 122 over the front side of the outer region 116. In some embodiments, the plurality of first apertures 120 have a aperture density ranging from 1.5 to 5.0 per square centimeter, while the plurality of second apertures 122 have a aperture density ranging from 0.8 to 1.5 per square centimeter over their respective areas.

The apertures 120,123,124, as shown in FIGS. 1 and 2, are generally cylindrical in cross-sectional shape. Optionally, some of the apertures 120,123,124 are non-cylindrical. For example, one or more of the apertures 120,123,124 may have rounded bottoms, tapered walls, or even reverse tapered walls where the lateral dimension increases with increasing depth. In some embodiments, the apertures 120,123,124 have an elongated shape in plan view (i.e. as viewed normal to the front surface 104). Such elongated apertures may be oriented in either the radial direction, the tangential direction, or at some intermediate angle between the two.

Preferably, the buffing pad 100 uses apertures with a length-to-width aspect ratio, measured in plan view, that does not exceed 2: 1. Use of discrete apertures with a relatively small aspect ratio is advantageous because such apertures are resistant to undue expansion during a polishing operation. Expansion of an aperture can allow compounding or polishing material to accumulate and become trapped in the pad. Agglomerations of abrasive material, if sufficiently large, can scratch the workpiece and degrade haze performance. It was additionally observed that expansion of an elongated aperture can even cause the sidewalls of the aperture to contact the workpiece, again causing undesirable scratches.

As shown in FIGS. 1, 2, and 4, the plurality of first apertures 120 and the first and second subsets 123,124 of apertures each has a uniform aperture size within its respective group. However, this need not be the case. For example, any of the apertures

120,123,124 could display a significant variability in size, either by choice or as a result of manufacturing tolerances. It is further contemplated that this variability may even result in overlap between the size ranges of the apertures 120,123, the apertures 123,124, or even the apertures 120,124 (as long as the average size of the apertures 120 is larger than the average size of the apertures 122).

Similarly, aperture density need not be uniform along the front sides of regions 114,116. As a result, the plurality of first apertures 120 may have an overall aperture density greater than that of the plurality of second apertures 122 even when the former apertures have a local aperture density within a certain area of the inner region 114 less than that of the latter apertures within some other area of the outer region 116. As such, there may well be significant overlap between number densities observed on a local level between the plurality of first apertures 120 and the plurality of second apertures 122.

While the apertures 120,123,124 extend from the front surface 104 into the substrate 102 in a generally perpendicular fashion as shown in FIG. 2, they may also extend into the substrate 102 at an acute angle to the perpendicular direction if so desired.

The described configuration of the apertures 120,123,124 along the substrate 102 of the buffing pad 100 has been shown to provide a number of unexpected advantages in a polishing operation. First, the apertures 120, by virtue of their larger average size relative to the apertures 123,124, significantly reduce drag resistance as the center of the rotating pad passes over the surface being polished. Second, the generally larger apertures 120 also reduce the degree of buckling of the pad 100 that occurs as a result of uneven friction between the front surface 104 and the surface being polished. As a result, significantly less jerking and jumping of the rotary pad occurs during operation. The alleviation of jerking and jumping in turn improves operator control and reduces strain and fatigue experienced by the operator.

Further advantages are provided by the concentric circular rings 140 located along the outer region 116. By partitioning the front surface 104 of the pad 100 into four distinct sections, the rings 140 of apertures 124 help isolate localized deformation of the pad 100 that occur during a buffing operation within its particular section. This advantageously prevents propagation of deformation across the entire front surface 104 and again results in a more manageable and predictable buffing operation.

Use of apertures of larger sizes in areas near the center of the pad 100 also provides superior performance compared with conventional buffing pads. Particularly, these pads 100 provide both increased cut rate and finer finish responses compared with conventional pads in which the average size of the apertures is generally uniform across the front surface. This is also an unexpected advantage, because superior cut and finer finish are often inversely related and it is generally difficult to realize both qualities simultaneously. A buffing pad which provides both a superior cut and finer finish allows a polishing job to be completed more efficiently and with less opportunity for operator error.

The apertures 120,123,124 in the substrate 102 may be provided using any number of manufacturing methods known to the skilled artisan. In some embodiments, the apertures 120,123,124 are formed by providing a suitable substrate 102, then applying a post-processing method to form the apertures. Examples of such post-processing methods include thermal embossing methods such as those described in U.S. Patent Publication No. 2007/0254567 (McLain) or water jet cutting as described in issued U.S. Patent No.

5,527,215 (Rubino et al.) and U.S. Patent Publication No. 2007/0204420 (Hornby et al). Alternatively, conventional methods such as engraving, mechanical boring, or cutting are also possible.

In one preferred method of making the pad 100, a laser is used vaporize the foam to produce the apertures 120,123,124. Laser cutting leaves behind a minimum amount of debris, and provides the flexibility for an operator to make nearly any configuration of apertures desired. Generally, the desired shape can be programmed into a computer aided drafting (CAD) system that interfaces with software that controls the position and intensity of the laser. The methods are advantageous because they are robust, versatile, and cost effective.

Alternatively, the apertures 120,123,124 may be provided in situ without need for a post-processing step. For example, the apertures 120,123,124 can be formed by casting and curing of the foam in a suitably shaped mold. FIG. 5 shows a buffing pad 200 according to another embodiment of the invention. Like buffing pad 100, the buffing pad 200 has a substrate 202 with a flat, circular front surface 204 extending across the substrate 202. The buffing pad 200 further includes apertures 220,223,224 in a pattern having characteristics similar to the respective apertures 120,123,124 of the buffing pad 100. In an exemplary embodiment, the buffing pad 200 has a diameter of about 3.25 inches (8.26 cm) and a thickness of about 0.88 inches (2.2 cm). Other aspects of the buffing pad 200 are analogous to those already described for pad 100 and shall not be repeated.

EXAMPLES

Comparative A.

A loop backed planar, open cell, polyurethane foam buffing pad, 3-¼-inches diameter by 1-inch depth (8.26 by 2.54 cm), was obtained under the trade designation "VP FG 3570-ID, Anthrazit", from Woodbridge FoamPartner Company, Chattanooga, Tennessee. The foam had an average density of 31.4 kilograms per cubic meter (kg/m³) and 40% Compression Load Deflection (CLD) of 8.47 kiloPascals (kPa).

Comparative B.

The face side of the foam buffing pad described in Comparative A, was formed into a convoluted pattern as described in U.S Patent No. 4,962,562 (Englund et al), the disclosure of which is incorporated herein by reference. Convoluted square array dimensions were 1.14 projections per square inch (0.18 projections per square cm), with a peak-to-valley height of 0.16 inches (0.04 cm) and peak-to-peak distance of 0.88 inches (0.35 cm).

Comparative C.

The front side of the foam buffing pad described in Comparative A was formed into a hexagonal channel array using an Eagle C0₂ Laser, Model No. 500, from LMI Technologies, Royal Oak, Michigan, according to the conditions listed in Table 1. The pattern was similar to a commercially available foam buffing pad, type "Hex-Logic", from Chemical Guys, Hawthorne, California.

TABLE 1

Example 1.

The buffing pad substrate used in Comparative A was provided and then a series of apertures were subsequently cut into the exposed face of the planar foam sheet to provide the aperture pattern shown in FIG. 5. The pattern cut into the face of the foam includes the first apertures and both the first and second subsets of the second apertures (hexagonal groupings and rings). This was accomplished using the Eagle C0₂ Laser operating according to the conditions listed in Table 2.

TABLE 2

Comparative D.

A loop backed planar, open cell, polyurethane foam compounding pad, 8-inch diameter by 1-inch depth (20.3 by 2.54 cm), having an average density of 28.7 kilograms per cubic meter (kg/m³) and 25% CLD of 6.52 kiloPascals (kPa), obtained from Pinta Foamtec, Inc., Minneapolis, Minnesota.

Comparative E.

The front side of the foam buffing pad Comparative D was formed into a convoluted pattern as described in Comparative B, wherein the peak-to-valley height was increased to 0.44 inches (0.17 cm).

Comparative F.

The front side of the foam buffing pad Comparative D was formed into a hexagonal channel array, as described in Comparative C. Example 2.

The complete aperture pattern as shown in FIGS. 1-2 was formed into the front side of foam buffing pad of Comparative D according to the method described in Example 1. As in Example 1 , the first apertures and both first and second subsets of the second apertures (hexagonal grouping and rings) were laser cut into the face of the foam.

Comparative G.

A foam buffing pad was made as described in Example 2, except only the second subset of the second apertures (rings) were laser cut into the face of the foam.

Comparative H.

A foam buffing pad was made as described in Example 2, except only the first subset of second apertures were laser cut into the face of the foam.

Example 3.

A foam buffing pad was made as described in Example 2, except only the first apertures and first subset of second apertures (hexagonal groupings) were laser cut into the face of the foam.

Cut Test 1.

The foam buffing pad of Example 1 and Comparatives A-C, were attached to a 3¼-inch (8.26 cm) diameter foam backup pad available from 3M Company, St. Paul, Minnesota, under the trade designation "3M Finesse-It Backup Pad, Part No. 84226". The backup pad was then attached to an air driven pneumatic buffer, available under the trade designation "Dyna Buffer #57240" from Dynabrade USA, Clarence, New York, with a down weight of 5 pounds (2.27 kg), and air pressure of 94 pounds per square inch (psi) (648.1 kiloPascals (kPa)) at the face).

A pre-weighed 18 by 24-inch (45.7 by 61.0 cm) painted metal test panel, type "APR 40577" obtained from ACT laboratories, Hillsdale, Michigan, was used as the test substrate. The test panel had the following coatings: E-Coat ED6060; Primer 764204; Basecoat 542AB921 BLACK; Clearcoat RK8148". The panel was cleaned and dried using a 50% by weight aqueous solution of isopropanol and a soft lint- free cloth. The panel was then fixed horizontally in place and 10 grams of buffing compound, type "Finesse-it Purple Polish, Part No. 51056", obtained from 3M Company, was applied to the center of the panel. The entire panel uniformly buffed for 2 minutes, using lateral motion and without applying substantial downward hand-force, after which the panel was cleaned and dried as described above. The buffing process was repeated 8 times.

Upon completion the panel was again wiped clean and dried as described above, after which the panel was reweighed. Cut was calculated as the difference between the initial and final weight of the panel. Higher cut values are better.

Cut Test 2.

The foam buffing pads of Example 2 and Comparatives D-I, were attached to an 8- inch (20.3 cm) diameter foam backup pad available from 3M Company, St. Paul,

Minnesota, under the trade designation "3M Finesse-It Backup Pad, Part No. 5717", using an adapter type "5710", also from 3M Company. The backup pad was then attached to an electric buffer, available under the trade designation "DeWALT DW849" from DeWALT Industrial Tool Company, Baltimore, Maryland, with a down weight of 5 pounds (2.27 kg).

A pre -weighed 45.7 centimeter x 61.0 centimeter (18 inch x 24 inch) painted metal test panel, type "APR 51534(H)" obtained from ACT laboratories, was cleaned and dried according to the method described in Cut Test 1. The test panel had the following coatings: E-Coat ED6060; Primer 765224EH; Basecoat 270AB921 BLACK; Clearcoat RK8148". 10 grams of rubbing compound, type "Perfect-it Rubbing Compound, Part no. 6085", obtained from 3M Company, was applied to the test panel and manually buffed for 1 minute at 1,400 revolutions per minute (rpm). The panel was cleaned and dried as described above and the buffing process repeated four more times, using successively less amounts of rubbing compound of 8, 6, 5 and 4 gram, respectively. After the fifth buffing step the test panel was cleaned, dried and reweighed, and the cut in grams determined. Each Example and Comparative was run in duplicate. As before, higher cut values are better. Haze Measurement.

Haze was measured using a haze gloss meter, Catalog no."AG-4601" from Byk- Gardener USA, Columbia, Maryland. Measurements were made before and after Cut Test 1, at the approximate center of each of the four quadrants of the test panel (that is, resulting in four measurements), at a 20 degree measurement angle. Lower haze values are better.

Comparative Samples A-C and Example 1 were subjected to Cut Test 1 and Haze Measurement. Results are listed in Table 3. Tests on Comparatives A and B, and

Example 1, were run in triplicate.

TABLE 3

Comparatives D-F and Examples 2-3 was subjected to Cut Test 2, in duplicate. Results are listed in Table 4.

TABLE 4

All of the patents and patent applications mentioned above are hereby expressly incorporated by reference. The embodiments described above are illustrative of the present invention and other constructions are also possible. Accordingly, the present invention should not be deemed limited to the embodiments described in detail above and shown in the accompanying drawings, but instead only by a fair scope of the claims that follow along with their equivalents.

Claims

CLAIMS:

1. A rotary buffing pad comprising:

a substrate having a front surface, back surface, and a rotation axis perpendicular to the front and back surfaces, the substrate further comprising:

an inner region adjacent to and surrounding the rotation axis; an outer region surrounding the inner region;

a plurality of first apertures having a first average size located within the inner region and extending from the front surface toward the back surface; and

a plurality of second apertures having a second average size located within the outer region and extending from the front surface toward the back surface, wherein the first average size is larger than the second average size.

2. A rotary buffing pad comprising:

a plurality of first apertures having a first aperture density located within the inner region and extending from the front surface toward the back surface; and

a plurality of second apertures having a second aperture density located within the outer region and extending from the front surface toward the back surface, wherein the first aperture density is larger than the second aperture density.

3. The buffing pad of claim 2, wherein the first aperture density ranges from 1.5 to 5.0 per square centimeter and the second aperture density ranges from 0.8 to 1.5 per square centimeter.

4. The buffing pad of claim 1 or 2, wherein the plurality of second apertures include a first subset of second apertures arranged according to a series of replicated polygonal groupings that are spaced apart from each another.

5. The buffing pad of claim 4, wherein the polygonal groupings are hexagonal groupings.

6. The buffing pad of claim 1 or 2, wherein the plurality of first apertures have a first average depth and the plurality of second apertures have a second average depth that is less than the first average depth.

7. The buffing pad of claim 1 or 2, wherein the plurality of first apertures have a first average diameter and the plurality of second apertures have a second average diameter that is less than the first average diameter.

8. The buffing pad of claim 1 or 2, wherein the plurality of first apertures occupy a first average volume and the plurality of second apertures occupy a second average volume that is less than the first average volume.

9. The buffing pad of claim 1 or 2, wherein the substrate comprises an open-celled polymeric foam that has a compression deflection value when compressed to 25 percent of original volume ranging from 2000 to 7000 Pascals.

10. The buffing pad of claim 1 or 2, wherein the inner region has a diameter ranging from 20 to 40 percent of the diameter of the substrate.

11. The buffing pad of claim 1 or 2, wherein the inner region occupies an area ranging from 4 to 16 percent of the total area of the front surface.

12. The buffing pad of claim 1 or 2, wherein the apertures are generally circular in shape.

13. The buffing pad of claim 1 or 2, further comprising a backing layer extending along at least a portion of the back surface and having a flexural modulus that is greater than that of the substrate.

14. The buffing pad of claim 13, wherein the backing layer comprises a fibrous material to facilitate coupling to a power tool having a hook face attachment surface.

15. The buffing pad of claim 1 or 2, wherein the plurality of first apertures include all of the apertures present within the inner region.

16. The buffing pad of claim 15, wherein the plurality of second apertures include all of the apertures present within the outer region.

17. The buffing pad of claim 1 or 2, wherein the outer region further comprises at least one annular region and wherein the plurality of second apertures further comprises a second subset of second apertures located in the at least one annular region, the second subset extending from the front surface toward the back surface and being disposed along at least one circular ring, each circular ring being coplanar with the front surface and generally symmetrical about the rotation axis.

18. The buffing pad of claim 17, wherein the second subset of second apertures have a certain diameter and a certain spacing between neighboring apertures and the ratio between the certain diameter to the certain spacing is at least 0.2.

19. The buffing pad of claim 18, wherein the ratio between the certain diameter to the certain spacing is at least 0.3.

20. The buffing pad of claim 19, wherein the ratio between the certain diameter to the certain spacing is at least 0.35.

21. The buffing pad of claim 17, further wherein the at least one annular region comprises two or more annular regions and the at least one circular ring comprises two or more circular rings that are located within the respective annular regions and concentric with each other.

22. A rotary buffing pad comprising:

an inner region adjacent to and surrounding the rotation axis; an outer region surrounding the inner region; and

a plurality of apertures extending from the front surface toward the back surface, wherein the apertures have a distribution of sizes and the apertures having relatively large size are predominantly located in the inner region relative to the outer region.