Coated abrasives

May 16, 1961

2,984,052

J. C. MUELLER, JR

COATED ABRASIVES Filed Aug. 12, 1959

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ATTORNEY

United States Patent Office „ , „ 2,934,052

Patented May 16, 1961 . . _r 1 .

2,984,052

COATED ABRASIVES

Josef C. Mueller, Jr., Cohoes, N.Y., assignor to Norton Company, Troy, N.Y·, a corporation of Massachusetts

Filed Aug. 12,1959, Ser. No. 833,194 3 Claims. (CI. 51—188) 'This invention relates to novel open mesh type coated abrasive products.

Abrasive sheets, discs, belts, etc., formed of a web of open mesh fabric adhesively coated With abrasive grains are well known in the art. Such products commercially available are of sufficiently open mesh to be seen through and . are coated on both sides and internally of the mesh openings with abrasive grains.

Such products require special equipment and technique in order to satisfactorily coat substantially the entire circumferential surface of the yarns of the mesh with abrasive grains. Such products include a large amount of abrasive grain internally of the mesh so positioned that it is either unused or only inefficiently used in applications where the flat side of the sheet is used as opposed to applications where the edges of the sheet are used (such as the so-called “flap wheels”).

It is, therefore, an object of my invention to provide an open wesh abrasive cloth of superior characteristics but which can be more simply and inexpensive produced than open mesh coated abrasives of the prior art.

It is also an object of my invention to produce an open mesh coated abrasive of improved tear resistance which employs relatively small amounts of abrasive grain as compared to the prior art.

My invention relates to abrasive coated foraminous textile sheet material which may be in the form of belts, discs, or other desired forms. In general, I have found that improved products can be produced wherein an open mesh textile backing is provided with a coating on one or both sides which lies on the plane of the backing and ⁴⁵wherein the mesh openings formed by intersection of yarns (e.g. the crossings of the warp and fill in a woven product) are internally free of adhesive and abrasive. The backings employed in my invention may be woven or knitted textiles of relatively open construction. How- ⁵³ever constructed, the fabrics which are particularly useful in my invention are nodose, open mesh sheet materials. Many of the common open mesh woven textile materials of which I am aware can be described as nodose—i.e. they have at one or both surfaces a plurality of protuberances or nodes either at the point of intersection of certain of the warp and fill threads or, in more complex weaves or knits, at some other regularly spaced points or areas throughout the surface of the web. In practicing my invention discrete spaced areas of abrasive grain are preferably bonded to the high points of the fabric only, for example at alternate crossings of the warp and fill threads in a plain weave fabric. The above described areas of abrasive grain may be applied on one or on both sides of the backing material.

In the drawings:

Figure 1 is an enlarged plan view of one embodiment of my invention.

Figure 2 is a cross-section of the view of Figure 1, taken along the line 2—2 of Figure 1.

Figure 3 is an enlarged plan view of another modification of my invention.

Figure 4 is a cross sectional view along the line 4—4 of Figure 3.

Figure 5 is a schematic drawing of an apparatus for manufacturing the improved abrasive product of my in5 vention.

In Figure 1,1 show an enlarged view of my invention embodying a plain weave backing 1». In such a material the highest and lowest areas on each side of the material are at the crossing points of the warp threads 10 11 and fill threads 12. By lightly applying adhesive to one side of the web, I am able to coat with adhesive only these high crossing points or nodes on a given side, leaving the rest of the fabric structure free of adhesive. As can be seen in Figure 2, this means that alternate crossing 15 points of the threads will be coated with adhesive. If then a quantity of abrasive grain is applied to the adhesive coated side of the sheet, in any of the conventional ways well known in the coated abrasive art, a coating of abrasive 13 is produced at each high crossing point on the ad20 hesive coated side of the sheet. The adhesive is then dried and when of appropriate resinous nature, subsequently cured. A final sizing of adhesive may be applied if desired as is well known in the coated abrasive art. The size coat may be applied to the abrasive coated areas 25 only or may be applied to the entire sheet if desired. The resulting product may be employed in the same application in which the overall coated open mesh abrasives of the prior art are used. In such application the products of my invention, in which only outer front and back SO surfaces of the web are coated with adhesive and abrasive grain as compared with the product of the prior art wherein said coatings completely surround the yarns of said web, will produce at least equivalent results in sanding or polishing operations, even though as little as one ³⁸ quarter of the amount of abrasive grain and adhesive normally employed in said products is used. The product of my invention on either the plain weave fabrics or many other woven or knit open mesh fabrics is of attractive appearance and high friction qualities because of the regular pattern of abrasive on its surface and is thus particularly useful as a non-skid tread for application to steps or flooring. In such cases one side of the material may be free of abrasive grains and may be coated with a pressure-sensitive or other adhesive.

Figures 3 and 4 show the invention wherein a reverse leno weave fabric is employed. In the drawing the doubled warp threads are shown at 20, the fill threads are shown at 21. As is more clearly shown in Figure 4, the position of the warp threads 20 causes the high spots or nodes on each side of the fabric to lie along spaced areas of each fill thread 21. Thus the abrasive particles bonded to the fabric by the method of this invention will lie only along these spaced areas as indicated at 22.

Figure 5 shows in schematic form an apparatus for ⁵⁵ producing the novel coated abrasives of my invention.

At 31 is indicated a rubber roll upon which an adhesive film from the adhesive supply indicated at 33 is metered by a small steel roll 32. The bottom rubber roll 30 is so arranged as to gently force the web against the ⁶⁰ film of adhesive on rubber roll 31. The position of roll 30 is so adjusted that the web 35 of nodose, open mesh material contacts the adhesive film only at the high points or nodes of the material. The particular position of roll 30 relative to the backing and the amount of adhesive ⁶⁵ metered onto the roll 30 determines the extent of coverage of adhesive and thus determines the extent of abrasive coverage of the finished product. Adjustment of these variables permits a wide variation in the nature of the finished product, from a product having small widely ‘° spaced abrasive areas to a product having its surface almost entirely covered with abrasive grains. Following the application of adhesive, a feeding device schematically

2,984,052 indicated at 34 applies abrasive grain which adheres to the backing 35 only at the adhesive coated areas. As indicated on the drawing, after receiving the application of abrasive grain, the backing then travels to ovens.for drying and in some cases subsequent curm£ df the¹ abrasive. After leaving the ovens the backing may receive a sand size of adhesive which may be applied¹ to'the¹ fhisfed areas only as by rolls 30 and 31, or adhesive may be applied over both the coated and uncoated, portions,:6f the’ backing. However, I find that where the. fiber grit'sizes are used, a final sand size step is often unnecessary¹, the' backing being ready for use after curing of the maker coat. ..

In most instances, I will apply adhesive and grain¹ to both sides of the backing, the material being first coated on one side as described above and after the adhesive is completely or partially set so aS to avoid disturbing the coating in subsequent handling operations, a coating is applied to the uncoated side in the same manner as the first coating.

Although I have described and shown a method whereby the abrasive grains are deposited by gravity, the common electrostatic methods of coating known in the art may be employed in producing the abrasive products Of my invention.

In addition to providing an efficient and novel abrasive product with a saving in the amount of adhesive and abrasive employed in its manufacture, I have found that the method of coating the product results in a more efficient and faster manufacturing operation, as compared to the methods employed in the manufacturing of the prior art open mesh abrasives.

The abrasive products of my invention have vastly improved tear resistance compared to the prior art products wherein the open mesh fabric has an overall coating of adhesive and abrasive. Furthermore, the products.

of my invention are more flexible and more easily freed of swarf than the conventional open mesh products of the prior art.

The term “woven” as used herein refers to fabrics having regularly interlaced yams or threads, whether the fabrics be knitted or made on a loom.