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Title:
SHEET-FORM COATED ABRASIVE ARTICLE
Document Type and Number:
WIPO Patent Application WO/2006/113374
Kind Code:
A1
Abstract:
To provide a sheet-form coated abrasive article which is excellent in removing abrasive swarf, yet provide a fine, uniformly textured surface, during the roughening process of autobody repair. A sheet-form coated abrasive article having two kinds of effective abrasive faces on an abrasive surface, the one being an effective abrasive face which has a plurality of perforations, and the other being an effective abrasive face which is non-perforated, wherein an effective abrasive face at peripheral part reaches to an end of the abrasive article.

Inventors:
OKA HITOSHI (JP)
TAKINAMI SATORU (JP)
Application Number:
PCT/US2006/013938
Publication Date:
October 26, 2006
Filing Date:
April 12, 2006
Export Citation:
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Assignee:
3M INNOVATIVE PROPERTIES CO (US)
OKA HITOSHI (JP)
TAKINAMI SATORU (JP)
International Classes:
B24D11/04
Foreign References:
US20030003856A12003-01-02
US4964245A1990-10-23
GB1532772A1978-11-22
US20020016144A12002-02-07
US5810650A1998-09-22
US20040180618A12004-09-16
Attorney, Agent or Firm:
Stewart, Pamela L. (Office Of Intellectual Property Counsel Post Office Box 33427 Saint Paul, Minnesota, US)
Download PDF:
Claims:
We Claim:
1. A sheetform coated abrasive article having two kinds of effective abrasive faces on an abrasive surface, the one being an effective abrasive face which has a plurality of perforations, and the other being an effective abrasive face which is nonperforated, wherein an effective abrasive face at peripheral part reaches to an end of the abrasive article.
2. The sheetform coated abrasive article according to claim 1 which has two effective abrasive faces, the first effective abrasive face having a plurality of perforations, and the second effective abrasive face is nonperforated.
3. The sheetform coated abrasive article according to claim 1 or 2, wherein the adjacent perforations have a distance between edges of from 1 to 20 mm.
4. The sheetform coated abrasive article according to any one of claims 1 to 3, wherein one perforation has an area of from 0.5 to 350 mm .
5. The sheetform coated abrasive article according to any one of claims 1 to 4, wherein one contacting abrasive face has at least 10 perforations.
6. The sheetform coated abrasive article according to any one of claims 1 to 5, wherein the coated abrasive article is mounted on a manual abrasive block or a sander and used.
Description:
SHEET-FORM COATED ABRASIVE ARTICLE

Field of Invention

The present invention relates to an abrasive article, and in particular, to a sheet-form coated abrasive article which is appropriate for repair work on automobiles.

Background

In automobile body repair both the soft coated repair film or putty and the adjacent plastic or steel body panel are abraded. When the repair film or putty is abraded, a large amount of swarf is generated during the sanding process, and therefore, it becomes necessary to remove the swarf to prevent clogging of the abrasive article. Perforated sheet-form coated abrasive articles for removing dust are known. However, the perforations are uniformly distributed over the entirety of the abrasive surface in such a manner that they inevitably make contact with the surface to be abraded. The edges of these perforations have the potential to cause scratches or uneven patterns on the repair surface.

Meanwhile, a fine uniform texture (which is, in general, referred to as "scuffing") is required on the body panel surface in order to improve putty and paint adhesion. That is to say, it is desirable for the body panel surface to be free of scratches or uneven patterns. As a result, it is difficult for uniformly perforated sheet-form coated abrasive articles to provide acceptable finish in the roughening process.

Abrasive discs having perforations non-uniformly distributed in an annular band, typically 1/3 to 1/4 of the disc radius, are also known. However, there is room for this multi-perforated structure to be further optimized in order to increase the efficiency of swarf removal. In addition, since the non-perforated regions are separated into a center

portion and an outer periphery portion by the annular perforated band, it is difficult to carry out the roughening process using a non-perforated region.

Brief Description of the Drawings Fig. 1. A cross sectional diagram showing a portion of the structure of a sheet-form coated abrasive article having perforations;

Fig. 2. A front diagram showing a coated abrasive disc according to one embodiment of the present invention;

Fig. 3. A side diagram showing an example of the manner in which the coated abrasive disc of Fig. 2 is used;

Fig. 4. A front diagram showing a sheet-form coated abrasive disc according to another embodiment of the present invention;

Fig. 5. A side diagram showing an example of the manner in which the coated abrasive disc of Fig. 4 is used; Figs. 6(a), 6(b) and 6(c). Front diagrams showing sheet-form coated abrasive articles according to other embodiments of the present invention;

Fig. 7. A front diagram showing a portion of a sheet-form coated abrasive article according to another embodiment of the present invention; and

Figs. 8(a) and 8(b). Side diagrams showing examples of the manner in which a coated abrasive article of the present invention is used.

Explanation of Numbering

11 base

12 binder 13 abrasive grains

14 perforations

20, 40 abrasive article disc

21, 41 first effective abrasive face

22, 42 second effective abrasive face

Disclosure of the Invention

The present invention is provided in order to solve the above described problems with the prior art, and an object thereof is to provide a sheet-form coated abrasive article which is excellent in removing abrasive swarf, yet provide a fine, uniformly textured surface, during the roughening process of autobody repair.

The present invention provides a sheet-form coated abrasive article having a base, abrasive grains placed on a surface of the base and a binder for securing the abrasive grains to the surface of the base. The coated abrasive article may be in sheet or disc format, wherein perforated and non-perforated surfaces are provided. A coated abrasive article of the present invention has a portion for efficiently removing swarf from the abraded surface, and a portion only for sanding, that is to say, the coated abrasive article has two functions within the same surface. Therefore, where an object to be sanded may generate a large amount of swarf, such as a repair putty or a coated film, the swarf is efficiently removed from the sanded surface using the perforated area of the sheet, whereas the non-perforated area of the coated abrasive sheet is used for the roughening process.

Fig. 1 is a cross sectional diagram showing a portion of a sheet-form coated abrasive article having perforations. The surface of a base 11 is coated with a binder 12, and abrasive grains 13 are secured to base 11 by means of binder 12. A number of perforations 14 are provided through the abrasive article. It is preferable for the edges of

the perforations on the abrasive surface side to be rounded. This is because there is a risk that the surface to be abraded will be scratched in the case where the perforated edges of the abrasive surface are sharp or protruding.

It is preferable for the perforations to be formed by carrying out a post-process on the sheet-form coated abrasive article. It is preferable that the perforating process be carried out in the direction from the abrasive surface toward the rear surface of the base. This is because the edges of the perforations on the abrasive surface side are rounded as a result of such processing. Alternatively, the base may be perforated prior to the abrasive coating step. Suitable materials used for the base include backings used in the abrasive art such as, for example, polymeric film (including primed polymeric film), cloth, paper, foraminous and non-foraminous polymeric foam, vulcanized fiber, fiber reinforced thermoplastic backing, nonwovens, treated versions thereof (e.g., with a waterproofing treatment), and combinations thereof, or any of these backings on which a metal has been vapor deposited. The thickness of the base that is particularly preferable is, in general, from 10 μm to 300 μm, and more preferably from 30 μm to 150 μm.

Abrasive grains are secured to the surface of a base by means of a binder. As for the binder, a binder that can sufficiently secure the abrasive grains and is conventionally used in an abrasive article for the repair of automobiles is used. Urea resins, phenol resins, epoxy resins, polyester resins, urethane resins, acrylate resins and composites of these can be cited as examples.

As for the abrasive grains, abrasive grains which are conventionally used for abrasive articles for the repair of automobiles are used. Examples include, aluminum oxide (such as fused alumina, ceramic alumina (including sol gel alumina) and the like), cerium oxide, zirconium oxide, other metal oxides, silicon carbide, alumina zirconia,

diamond, boron nitride, silicon nitride and other metal nitrides. In addition, the abrasive grains may be plastic fine grains made of polymethacrylate, polystyrene, polyolefin or the like. As for the dimensions of the abrasive grains, the average grain diameter is generally from approximately 520 μm to 0.45 μm. That is to say, the average grain diameter ranges from 520 μm (JIS #36) to 0.45 μm (JIS #20000), preferably from 5 μm (JIS #3000) to 260 μm (JIS #60).

A coated abrasive article of the present invention may be made by known methods used in the abrasive arts, for example, applying a binder and a mineral (a make coat) to a non-perforated base, applying an optional size coat, curing, then perforating the article. Alternatively, a number of perforations are formed in the surface of a base prior to the mineral and size coating.

The coated abrasive article of the present invention has two kinds of effective abrasive faces on the abrasive surface, one being an effective abrasive face having a plurality of perforations, and the other being an effective abrasive face with no perforations. Effective abrasive face means a region on an abrasive surface which is effective for providing an acceptable uniform finish on the repair surface.

Fig. 2 is a front diagram showing one embodiment of a coated abrasive article according to the present invention. The abrasive disc 20 has two effective abrasive faces on the abrasive surface. It is not necessary for the abrasive disc to be circular, and it may have any form, as long as it can be mounted on a sander for use.

The perforated region does not provide the same abrading efficiency as the non-perforated region, and the two become effective abrasive faces which are different from each other on the abrasive surface. The border between the two is defined by an imaginary line of the shortest distance connecting the perforations located at the end. A first effective abrasive face 21 has a plurality of perforations and is located

along the outer peripheral portion. A second effective abrasive face 22 is non-perforated and is located on the center portion. As described above, in the case where the effective abrasive surface is divided into concentric forms, it is preferable for the number thereof to be two. This is because in the case where three or more effective abrasive faces are formed, the practicality of the effective abrasive surfaces is reduced.

The area per penetration is from 0.5 mm 2 to 350 mm 2 . In the case where the area of the perforations is in this range, the shape of the perforations may be any of: circular, elliptical, polygonal, fan-shaped, leaf-shaped, arched or the like. In the case where the area per perforation is not greater than 0.5 mm , it becomes easy for abrading swarf in lump form to clog, lowering the efficiency of swarf removal. As a result of this, the sanding performance cannot be greatly increased.

In the case where the area per perforation is not less than 350 mm 2 and, particularly, when the coated abrasive article is mounted for use on a vacuum sander, the vacuum per perforation is reduced, and the abrading swarf cannot be efficiently removed. As a result of this, the sanding performance cannot be greatly increased. Here, this is not so in the area of a large perforation located in the center portion of the abrasive article in donut form. In the case where the area per perforation ranges from 1 mm to 80 mm , the sanding performance can be further increased.

The distance between end portions of adjacent perforations is from 1 mm to 20 mm. In the case where the distance between end portions of adjacent perforations is no, greater than 1 mm, the sheet strength between the perforations is weak, causing breaking. In addition, the difference in stress within the sheet causes warping in portions having many penetrations, and negatively affects the quality of the abrasive article. As a result of this, the sanding performance cannot be greatly increased. In the case where the distance between end portions of adjacent perforations is not less than 20 mm, the

frequency at which the perforations encounter abrading swarf is low throughout the abrading movement of the abrasive article, and the abrading swarf cannot be efficiently removed. Again, as a result of this, the sanding performance cannot be greatly increased. Fig. 3 is a side diagram showing an example of how the above described abrasive disc is used. An abrasive disc 31 is mounted on a sander 33 via a support pad 32, and is pressed at an angle against an object to be abraded 34 having a step or the like from which a large amount of abrading swarf is generated. In this case, the first effective abrasive face of the abrasive disc is used. It is preferable, in the roughening process, that the second effective abrasive face is used. Fig. 4 is a front diagram showing a sheet-form coated abrasive article according to another embodiment of the present invention. This abrasive disc 40 has two effective abrasive faces on the abrasive surface. A first effective abrasive face 41 is non-perforated and is located along the outer peripheral portion. A second effective abrading face 42 has a plurality of perforations and is located on the center portion. Fig. 5 is a side diagram showing an example of the manner in which the above described abrasive disc is used. An abrasive disc 51 is mounted on a sander 53 via a support pad 52 and pressed against a protruding object to be abraded from which a large amount of abrading swarf is generated. In this case, the second effective abrasive face of the abrasive disc is utilized. It is preferable to use the first effective abrasive face in the roughening process.

As shown in Figs. 3 and 5, in the case where abrading is carried out using an effective abrasive face having a plurality of perforations, for example, the number of perforations per effective abrasive face that actually makes contact with the object to be abraded is not less than 10. As a result of this, abrading swarf can be efficiently removed from the effective abrasive face that makes contact with the object, and as a result, the

sanding performance can be effectively increased.

Figs. 6(a) to 6(c) are front diagrams showing sheet-form coated abrasive articles according to other embodiments of the present invention. As shown in these figures, shapes of the coated abrasive articles may be polygonal including rectangle or oval. The abrasive sheets of Fig. 6(a) respectively have two effective abrasive faces on the abrasive surface. In addition, as for the respective effective abrasive faces, the first effective abrasive face has a plurality of perforations, and the second effective abrasive face is non-perforated, or the first effective abrasive face is non-perforated, and the second effective abrasive face has a plurality of perforations. The respective abrasive sheets of Fig. 6(b) have two kinds of effective abrasive faces, in such a manner that the center portion and the two end portions on the same abrasive surface have effective abrasive faces that are different from each other. In addition, as for the respective effective abrasive faces, the first effective abrasive face has a plurality of perforations, and the second effective abrasive face is non-perforated, or the first effective abrasive face is non-perforated, and the second effective abrasive face has a plurality of perforations.

The abrasive sheets of Fig. 6(c) have two effective abrasive faces which are divided into concentric forms on an abrasive surface. In addition, as for the respective effective abrasive faces, the first effective abrasive face has a plurality of perforations, and the second effective abrasive face is non-perforated, or the first effective abrasive face is non-perforated, and the second effective abrasive face has a plurality of perforations.

Fig. 7 is a front diagram showing a portion of a sheet-form coated abrasive article according to another embodiment of the present invention. This abrasive sheet has an effective abrasive face having a plurality of perforations, and an effective abrasive face that is non-perforated. The penetrations within the multi-penetrations structure may exist in a number of groups, as shown here.

Figs. 8 (a) and 8(b) are side diagrams showing examples of the manner in which the above described abrasive sheets are used. The abrasive sheet may have any form, as long as it can be mounted on a hand pad or a sander for use. In Fig. 8(a), an abrasive sheet 71 is mounted on a hand pad 3 via a support pad 72, and pressed at an angle against an object to be abraded 74 having a step or the like. In Fig. 8(b), an abrasive sheet 81 is mounted on a sander 83 via a support pad 82, and pressed against a protruding object to be abraded 84. In the same manner as in the above described embodiments, an effective abrasive face having a plurality of perforations is used for the abrading of a portion from which a large amount of abrading swarf is generated, and an effective abrasive face that is non-perforated can be used in the roughening work.

In the following examples, the present invention is described more concretely, but the present invention is not limited to these examples. Examples

Predetermined penetrations were created in "one-touch disc UNI abrasive disc, P120" made by Sumitomo 3M Ltd., having a diameter of 125 mm, and the abrading performance on putty was evaluated. "PN 5200 high soft super," made by Sumitomo 3M Ltd., was used as the putty, "PN 3965 double action sander," made by Sumitomo 3M Ltd., was used as the sander, and "PN 5595 one touch disc pad with penetrations," made by Sumitomo 3 M Ltd., was used as the support pad that was mounted on the sander. Each of examples 1 to 11 had a non- perforated abrasive face and a perforated abrasive face on an abrasive surface. The non- perforated abrasive face was located along the outer peripheral portion and the perforated abrasive face was located on the center portion. On the other hand, comparative examples 1 and 2 had only 6 and 7 perforations which are separately located on an abrasive surface respectively. An XY tester was used for the abrading evaluation, and the total amount of

abrading when putty was abraded for three minutes x 3 times was compared (indicated by the ratio in the case where the amount of abrading with one-touch disc UNI having no penetrations is 100%). The results are shown in Table 1.

Table 1