Abrasive tool making process – material – or composition – With synthetic resin
Reexamination Certificate
2001-12-28
2003-09-02
Marcheschi, Michael (Department: 1755)
Abrasive tool making process, material, or composition
With synthetic resin
C051S295000, C051S307000, C051S308000, C051S309000, C051S293000
Reexamination Certificate
active
06613113
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to flexible abrasive products which comprise an abrasive coating on a substrate which includes multiple separated but connected bodies which are spaced apart to provide openings through the substrate.
BACKGROUND OF THE INVENTION
The usual objective of any sanding operation is to remove unwanted material from the surface being sanded and to prepare that surface for subsequent coating operations. Typically, these two objectives are diametrically opposed. Removing unwanted material from the surface in a reasonable amount of time requires the use of a coarse abrasive while preparing the surface for subsequent coating operations requires the use of a fine abrasive. Thus, the operator must sand the surface multiple times with a succession of increasingly finer grit sandpaper to achieve both objectives. The coarse sandpaper removes unwanted material quickly. However, a progression of increasingly finer sandpaper is often needed to remove the unacceptably deep scratches left in the surface by the coarse sandpaper. This entire sanding process is viewed by many as laborious, time consuming, and generally distasteful. Sandpaper manufacturers recognize this dilemma and have offered many products in an attempt to solve the problem.
Conventional sandpaper is normally manufactured by adhering abrasive mineral particles to a thin relatively stiff, non-porous paper backing with a relatively inflexible adhesive. This construction yields a product with good initial stock removal (cut) but with a deep scratch pattern and the product has an undesirable relatively short life. The stock removal and deep scratch characteristics of conventional sandpaper can be attributed to the relatively stiff nature of the product. Further, the non-porous nature of the backing contributes to the short life of conventional sandpaper by trapping the debris generated during sanding. This trapped debris often clogs the abrading surface of the sandpaper preventing any further stock removal. Additionally, the thin, slippery nature of conventional sandpaper makes the product difficult to hold and use.
While such flat sandpapers are widely successfully used in a multitude of commercial applications, abrasive manufacturers such as Minnesota Mining and Manufacturing Company (3M) have recognized the above-noted deficiencies with conventional sandpaper and introduced other types of sanding products in an attempt to solve the above noted problems. 3M introduced an abrasive coated sponge under the trade designation SMALL AREA SANDING SPONGE Catalog #907, as an example of such a product. Conventional sanding sponge products are normally manufactured by adhering abrasive mineral particles to a relatively thick synthetic foam backing with a relatively flexible adhesive. The finished sanding sponge is usually between 5 mm and 25 mm thick with a non-porous abrasive surface on all major surfaces. The flexible nature of this product construction yields a finer scratch pattern in the sanded surface than conventional sandpaper when comparable grit size products are used to sand the same surface while the thickness of the construction allows easier gripping and more comfortable use. However, the flexible nature of conventional sanding sponges decreases the stock removal (cut). Like conventional sandpaper, the non-porous surface of a conventional sanding sponge traps the dust generated during sanding which may clog the abrasive surface minimizing future stock removal.
RELATED PRIOR ART
U.S. Pat. No. 2,984,052 (Mueller, Jr.) discloses coated abrasive product comprising an open, woven or knit mesh fabric having a plurality of protrubences regularly spaced throughout or regularly spaced raised areas with abrasive grains bonded thereto with the remainder of the backing sheet being free of bonded abrasive grains.
U.S. Pat. No. 5,578,343 (Gaeta et al.) discloses a mesh-backed abrasive material which comprises an unfinished greige mesh fabric in which at least 20% of the surface area is voids and which is coated with a maker coat of binder to attach abrasive grain thereto and overcoated with a size coating of binder to provide an abrasive product.
U.S. Pat. No. 5,637,386 (Darjee) discloses a coated abrasive comprising a substrate selected from woven and knit materials such as an elastic knit fabric and abrasive particles bonded directly to the substrate in a spaced discontinuous pattern.
German Utility Model No. DE 201 11 245 U1, published Jun. 21, 2001, discloses a sanding cloth made by adhering abrasive particles to a textile structure with many openings.
U.S. Pat. No. 6,099,776 (Tintelnot) discloses a flexible, open-pored cleaning body having at least one scouring surface with continuously formed raised projecting ridges of different heights which may have abrasive grain embedded therein.
Notwithstanding the above disclosures, there remains a need for a highly conformable abrasive product which will not easily become clogged with the debris created by sanding operations.
SUMMARY OF THE INVENTION
The present invention provides a flexible abrasive product which is easily conformable to contoured surfaces being abraded, easily held by hand and may be used with sanding devices, yet will not easily clog with the debris created by typical abrading operations.
In one aspect the invention provides a flexible abrasive product comprising:
a. a flexible sheet-like substrate comprising a multiplicity of separated resilient bodies connected to each other in a generally planar array in a pattern which provides open spaces between adjacent connected bodies, each body having a first surface and an opposite second surface; and
b. abrasive particles to cause at least said first surface to be an abrasive surface.
Preferred flexible abrasive products include bodies which are generally square and bodies wherein the first surface is a convex surface. Preferred resilient bodies are comprised of an elastomeric material such as foam rubber composition.
The preferred manner in which to provide the abrasive surface is by coating the first surface with a curable make binder coating, applying abrasive grains to the uncured make binder coating and at least partially curing the make binder coating. A preferred embodiment includes applying a size coating over the make binder coating and abrasive particles and fully curing the coatings to firmly adhere the abrasive particles in the abrasive coating.
In a further aspect, the invention provides a method for making a flexible abrasive product comprising:
a. providing a flexible sheet-like substrate comprising a multiplicity of separated resilient bodies connected to each other in a generally planar array in a pattern which provides open spaces between adjacent connected bodies, each body having a first surface and an opposite second surface; and
b. providing abrasive particles to at least said first surface to provide an abrasive surface.
A preferred method of providing the abrasive surface is provided by coating the first surface with a make coating of curable binder composition, depositing abrasive particles onto the make coating of the curable composition and at least partially curing the make coating composition. It is also preferred to coat the make coating and abrasive particles with a size coating of a curable composition and curing the size coating composition.
An alternate preferred method of providing abrasive particles to the first surface is by mixing abrasive particles with a curable binder composition to provide a mixture which cures to provide an abrasive coating, coating the first surface with the mixture and curing the curable binder composition. Preferably, after coating but prior to curing, the curable binder composition containing abrasive particles is contacted with a surface of a tool which includes raised areas and depressed areas to provide a shaped or structured surface to the abrasive coating.
The above method of providing a shaped or structured abrasive coating is described in U.S. Pat. No. 5,435,816 assigned to the same assignee as th
Annen Michael J.
Minick Chris A.
Nelson Eric W.
3M Innovative Properties Company
Francis Richard
Marcheschi Michael
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