Abstract:
A flexible, hand-held sanding pad comprises a conformable, multi layered, semicircle pad having a surface capable of providing temporary adhesive attachment for a sheet of pressure-sensitive adhesive-coated abrasive material.

Description:
[0001]    CROSS-REFERENCE TO RELATED APPLICATION 60/834666. APPLICANT CLAIMS THE BENEFIT OF EARLIER PROVISIONAL PATENT APPLICATION 60/834666 FILED ON Aug. 1,2006. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to an improved sanding pad for holding and supporting a sheet of pressure-sensitive adhesive-coated abrasive material during hand sanding operations. 
         [0004]    2. Prior Art 
         [0005]    Coated abrasive sheet materials are used in any of a wide variety of applications. Many applications require hand sanding where the user will grasp a coated abrasive sheet in his hand and apply it to the surface being treated. Such use has fostered numerous devices to assist in the holding of the coated abrasive sheet to avoid injuring the hand or fingers while maintaining the requisite position of and pressure on the coated abrasive sheet to its optimum effect. Improper positioning will cause uneven abrasion of the treated surface. Irregular pressure, such as caused by the fingers against the back side of the abrasive sheet in use, produces an irregular abraded surface. 
         [0006]    Early holding devices used for this purpose were inflexible blocks of solid material such as wood over which the coated abrasive sheet was wrapped. While these devices were adequate for some purposes, they required some means of holding or attachment of the ends of the coated abrasive sheet while applying one face of the block against the surface being treated, thus not making the maximum efficient use of the paper since the ends are generally never exposed to the surface being treated. Various sanding blocks of this type employing means for grasping the ends of the abrasive sheet are known, for example as disclosed in U.S. Pat. Nos. 2,765,593 and 1,562,414. U.S. Pat. No. 1,562,414 discloses a similar hand block which requires at least a part of the block to be formed of a material which is somewhat flexible but sufficiently rigid to retain the ends of the abrasive sheet in slots cut therein. 
         [0007]    There has been developed and marketed a self-adhering coated abrasive sheet and rotatable disc material using pressure-sensitive adhesive coated on its back side so that it may be adhered directly to the working face of a sanding block or rotatable disc sanding head. For the most part, this means of attachment assures exposure of the entire abrasive face of the abrasive sheet. Such abrasive sheets are disclosed in U.S. Pat. Nos. 2,485,295, 3,849,949 and 3,912,142. This type of abrasive sheet has been extremely useful in conjunction with hard sanding blocks such as the types mentioned above and for rotatable disc sanding heads. 
         [0008]    while the rigid sanding blocks are useful for sanding flat areas or areas with moderate surface variation, such as curved parts with a large radius of curvature, great quantities of abrasive sheet material are still used on complex surfaces, such as carved patterns, curved parts having a smaller radius of curvature and the like, without a pad. There has been no acceptable sanding pad, prior to the present invention, which is sufficiently conformable to be used to sand complex surfaces and particularly which can use pressure-sensitive adhesive coated abrasive disc material. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a novel improved sanding pad for holding and supporting a sheet of pressure-sensitive adhesive-coated abrasive material during hand sanding operations which overcomes the problems noted above. The sanding pad of this invention is ideally suited for use with pressure-sensitive adhesive-coated abrasive disc material. 
         [0010]    The sanding pad of the present invention comprises a conformable, three layer, self-supporting pad which has an outer surface capable of providing temporary adhesive attachment for a sheet of pressure-sensitive adhesive-coated abrasive material. The inner layer has sufficient body and integrity to distribute the forces provided by the fingertips and palm surface to eliminate discontinuities caused by finger impressions. 
         [0011]    The conformable, self-supporting pad is sufficiently conformable to permit the coated abrasive disc to conform to irregular shapes such as may be found on automobiles, and depressed and raised patterns on furniture or woodwork. The outer surface of the conformable pad upon which the pressure-sensitive adhesive-coated abrasive disc is adhered provides for temporary adhesive attachment, permitting clean removal, yet securing the sheet firmly even during the most strenuous sanding operations. 
         [0012]    These and other objects, advantages and embodiments will become more apparent when read with the accompanying figures and detained description. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a plan view of the preferred sanding pad of the invention in position on the hand; 
           [0014]      FIG. 2  is a perspective view of the sanding pad shown in  FIG. 1 ; 
           [0015]      FIG. 3  is a cross-sectional end view of the sanding pad shown in  FIG. 1 ; and 
           [0016]      FIG. 4  is a cross-sectional end view of the sanding pad shown in  FIG. 1  with a sheet of pressure-sensitive adhesive-coated abrasive material adhered on its outer surface. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring to the accompanying drawing, in which like reference numerals refer to like parts, a sanding pad  101  is shown which has a top surface  306  and bottom surface  307  capable of providing temporary adhesive attachment for a sheet  409  of pressure-sensitive adhesive-coated abrasive material. 
         [0018]    The pad must be a size convenient for holding in the hand. It has been found that sizes ranging from about 5 to about 8 inches are quite adequate. The shape of the pad is preferably a semicircle, as shown in the drawing. 
         [0019]    The conformable pad is at least about 3/16 inch thick, preferably at least ⅜ to ¾ inch thick. The pad is formed of a material which is conformable and for the most part will conform easily around intricate and complex shapes, yet it has sufficient body and integrity to distribute the forces provided by the fingertips and palm. For convenient application of a pressure-sensitive coated abrasive sheet, the conformable pad should not be so conformable as to hang limp from the handle means. It may be difficult to apply the adhesive face of the abrasive sheet to a pad which is too limp. 
         [0020]    any of a wide variety of conformable sheet materials have been found to be suitable for forming the conformable pad of the sanding pad of the present invention. Useful materials include solid rubber sheets or sheets of open or closed cell foam rubber formed of natural rubber, silicone rubber, neoprene, nitrile rubber, SBR rubber, vinyl rubber, epichlorohydrin rubber, ethylene propylene diene terpolymer rubber, polyurethane rubber, and the like; sheets of reticulated material formed of thermoplastic materials such as polyvinyl chloride, polypropylene, polystyrene, and the like; nonwoven fabrics which may be formed of adhesively bonded staple fibers or of mechanically integrated fibers, e.g., felt; woven or knit fabrics; embossed-surfaced plastic material such as embossed films of polyvinyl chloride, polyurethane, polyethylene, polypropylene; natural sheet goods such as leather; and laminations of one or more of the above. The preferred pad is formed of laminated closed cell neoprene. 
         [0021]    The materials which are sufficiently soft and conformable will have a Shore A durometer hardness value of less than about 60. Harder materials will not be easily conformable to complex surfaces. 
         [0022]    The surface of the pad is a closed cell neoprene to prevent permanent adhesion of the pressure-sensitive adhesive coated-abrasive sheet material and to provide temporary attachment of the pressure-sensitive coated-abrasive sheet. 
         [0023]    The intermediate layer  305  will preferably have a Shore A durometer hardness value between 30 and 60. This will allow the pad the ability to maintain a sufficient body and integrity to distribute the forces provided by the fingertips and palm surface to eliminate discontinuities caused by finger impressions. 
         [0024]    The top surface  306  and bottom surface  307  will preferably have a Shore A durometer hardness value between 20 and 40. This will allow the pad to conform to complex surfaces and prevent permanent adhesion of the pressure-sensitive adhesive coated-abrasive sheet material. 
         [0025]    The semicircle straight edge  204  has rounded corners  308  to allow a single round disc of pressure-sensitive adhesive coated-abrasive sheet material  409  to be applied to the top surface  306  and bottom surface  307  preventing any creasing or crinkling.