Patent Publication Number: US-2010122498-A1

Title: Abrasive Sheet Including An Abrasive Layer

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese application No. 097144124, filed on Nov. 14, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an abrasive sheet, more particularly to an abrasive sheet including an abrasive layer. 
     2. Description of the Related Art 
     Referring to  FIG. 1 , a conventional sheet of sandpaper  100  is formed by applying an adhesive to a fabric base  11  so as to form a first adhesive layer  12 , and spreading a plurality of abrasive particles  13  on the first adhesive layer  12 , followed by uniformly applying the adhesive to the abrasive particles  13  so as to form a second adhesive layer  14 . However, since the abrasive particles  13  are very small in size and densely distributed, the spacing and depth among the abrasive particles  13  are also very small. In use, dust particles resulting from sanding of an object are likely to clog the spacing and depth among the abrasive particles  13  and cannot be removed easily, thereby reducing roughness and abrading efficiency of the sandpaper  100 . 
     Referring to  FIG. 2 , another conventional sandpaper  200  is formed by applying an adhesive to a fabric base  21  so as to form a first adhesive layer  23 , followed by attaching an abrasive web  22  to the first adhesive layer  23 . The abrasive web  22  is formed by spreading a plurality of abrasive particles on a web sheet and has a plurality of web holes  221 . The abrasive web  22  has an uneven surface, with a relatively large difference between high and low surface points due to the presence of the web holes  221 . Therefore, the dust particles resulting from a sanding process using the sandpaper  200  can be easily removed from the sandpaper  200 . 
     However, since the abrasive web  22  is attached to the fabric base  21  using only the first adhesive layer  23 , the structural strength of the sandpaper  200  is insufficient. In addition, since parts of the first adhesive layer  23  and the fabric layer  21  beneath the web holes  221  are not covered by the abrasive particles, they are likely to be damaged by the dust particles produced upon sanding at a high temperature and a high speed. Therefore, when the sandpaper  200  is used with a grinding wheel machine at a high speed, the fabric base  21  and the abrasive web  22  can be easily separated from each other and become damaged. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide an abrasive sheet that can overcome the aforesaid drawbacks associated with the prior art. 
     According to one aspect of the present invention, an abrasive sheet comprises: a fabric base; a first adhesive layer applied to the fabric base; a netted web attached to the first adhesive layer, and having a plurality of web openings therein; a second adhesive layer applied to the netted web; an abrasive layer having a plurality of abrasive particles spread on the second adhesive layer; and a third adhesive layer applied to the abrasive layer. 
     According to another aspect of the present invention, an abrasive sheet having high durability is made by a process that comprises: applying a first adhesive layer to a fabric sheet; attaching a netted web to the first adhesive layer, the netted web having a plurality of web openings so as to create an uneven surface on the netted web; applying a second adhesive layer to the uneven surface of the netted web, the second adhesive layer having an uneven surface substantially corresponding to the uneven surface of the netted web; spreading on the second adhesive layer a plurality of abrasive particles so as to form an abrasive layer, the abrasive layer having an uneven surface substantially corresponding to the uneven surface of the second adhesive layer, the abrasive particles filling the web openings of the netted web; and applying a third adhesive layer to the abrasive layer, the third adhesive layer having an uneven surface substantially corresponding to the uneven surface of the abrasive layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of this invention, with reference to the accompanying drawings, in which: 
         FIG. 1  is a sectional view of a conventional sandpaper; 
         FIG. 2  is a partly exploded perspective view of another conventional sandpaper; 
         FIGS. 3   a  to  3   f  illustrate consecutive steps of the preferred embodiment of a method for making an abrasive sheet according to this invention; and 
         FIG. 4  is a sectional view of the preferred embodiment of the abrasive sheet according to this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 3   a  to  3   f  and  FIG. 4  illustrate an abrasive sheet  300  of a preferred embodiment according to this invention. The abrasive sheet  300  includes a fabric base  31 , a first adhesive layer  41 , a netted web  50 , a second adhesive layer  42 , an abrasive layer  60 , and a third adhesive layer  43 . 
     In this embodiment, the fabric base  31  is formed in the shape of a quadrangle. Alternatively, depending on actual requirements, the fabric base  31  can be formed in the shape of a circle, strip, polygon, or ring. 
     The first adhesive layer  41  is uniformly applied to the fabric base  31 . 
     The netted web  50  is attached to the first adhesive layer  41 , and has a plurality of web openings  52  therein. In this embodiment, the netted web  50  is a woven web. The web openings  52  are formed in the shape of a quadrangle. Alternatively, the web openings  52  can be formed in the shape of a circle, oval, triangle or polygon depending on actual requirements. 
     The second adhesive layer  42  is uniformly applied to the netted web  50  and has an uneven surface corresponding to an uneven surface profile of the netted web  50 . 
     The abrasive layer  60  has a plurality of abrasive particles  601  uniformly spread on the second adhesive layer  42  such that an abrasive surface conforming with the uneven surface of the second adhesive layer  42  is formed. In this embodiment, the abrasive particles  601  are made of emery and have an arbitrary shape. It is worth mentioning that, in  FIG. 4 , in order to clearly show the abrasive particles  601  which are distributed at both high and low surface points of the uneven surface of the second adhesive layer  42 , portions of the abrasive layer  6  within the web openings  52  are omitted and are shown as being bare. Actually, the web openings  52  are filled with the abrasive particles  601 . The abrasive web  50  is connected to the fabric base  31  through the first adhesive layer  41 . 
     The third adhesive layer  43  is uniformly applied to the abrasive layer  60  and fills the clearances among the abrasive particles  601  so as to improve adhesion strength of the abrasive particles  601 . The third adhesive layer  43  also has an uneven surface conforming to the abrasive surface of the abrasive layer  60 . 
     The abrasive sheet  300  is made by a method including the steps: (a) preparing the fabric sheet  31 , an adhesive, the netted web  51  and the abrasive particles  601 ; (b) applying the adhesive to the fabric sheet  31  so as to form the first adhesive layer  41 ; (c) attaching the netted web  50  to the first adhesive layer  41  such that the netted web  50  is connected to the fabric base  31 ; (d) applying the adhesive to the netted web  50  so as to form the second adhesive layer  42 ; (e) spreading on the second adhesive layer  42  the abrasive particles  601  so as to form the abrasive layer  60 ; and (f) applying the adhesive to the abrasive layer  60  so as to form the third adhesive layer  43 . 
     By forming the abrasive surface conforming with the uneven surface of the netted web  50 , the abrasive sheet  300  has a rough surface with a relatively large distance between high and low surface points, thereby alleviating the problem of clogging the abrasive sheet  300 . Moreover, as the web openings  52  are provided with the abrasive particles  601 , the fabric base  30  can be protected from being damaged by the dust particles produced upon sanding or grinding an object. In addition, by virtue of the first, second, and third adhesive layers  91 ,  42 ,  43 , clearances among the abrasive particles  601  can be filled, thereby enhancing adhesion strength and durability of the abrasive sheet  300 . 
     With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.