Norton Company

Wesley R Kaczmarek

Eugene Zador

Sitaramaiah Ravipati

Ernest A Coleman

Stanley J Supkis

David Rostoker

Richard H Vogel

Shyiguei Hsu

Coated abrasive material for fine finishing applications including second fining ophthalmic application, having patterned surface coating of abrasive grains dispersed in radiation-cured adhesive binder. The patterned surface coating is defined by a plurality of formations of such abrasive/binder each having an inner bottom edge defining an area devoid of coated abrasive, a top edge defining a somewhat larger area devoid of coated abrasive and an inner wall connecting the top and bottom edges.

Patterned coated abrasive for fine surface finishing

A single step fining pad for use in a ophthalmic applications having radiation cured maker and size coats of different hardnesses.

Single step, radiation curable ophthalmic fining pad

A coated abrasive which is advantageous for certain applications has at least two distinct layers of abrasive grits: a coarse outer layer and a finer inner layer. The median particle size of the grits in the outer layer is at least 150% of that of the inner layer grits. The grits may be adhered to the backing with adhesives compounded primarily of acrylates and cured by exposure to UV light. A product made in this way is effective for one step fining of plastic ophthalmic lenses.

Plural layered coated abrasive

Previous coated abrasives with adhesives suited to rapid, UV light initiated cure often had intractable curl problems. Therefore, such coated abrasives have been unsuited to precision finishing of workpieces with strict flatness or other curvature requirements, such as read-write heads for magnetic recorders or computer memories. This invention provides coated abrasives, having adhesives with cure initiated by UV light, which are suited to curvature control by the methods used conventionally for magnetic recording media. The preferred adhesive formulations include reaction products of 2-hydroxyethyl acrylate with polyol polyester oligomers capped with isocyanate end groups, alkoxylated diacrylated monomers, and N-vinyl pyrrolidone and other monomers with only one polymerizable unsaturated double bond per molecule, and sometimes also include nonpolymerizable thermoplastic polymers. The adhesives, with abrasives grain dispersed therein, are milled in special mills combining the actions of small milling media with large scale high speed agitation to reduce their viscosity to a workable level for gravure roll coating. The dispersion is then coated on plastic film backings and cured with UV lamps having a high spectral output in the near UV, the backing being kept cool during cure by contact with a cooled metal roll. The warm coated abrasive thus formed is finally shaped into accurately flat or other controlled curvature.

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Ballston Lake, NY, United States of America

Wesley R Kaczmarek