Coated abrasives with rapidly curable adhesives and controllable curvature
First Claim
1. A coated abrasive having at least one layer of adhesive comprising the cured product of liquids containing chemical unsaturation and capable of rapid, spontaneous polymerization initiated by actinic radiation, said cured adhesive being sufficiently deformable at a first temperature of not more than 130°
- C. to be shaped, along with the backing on which it is coated, into a predetermined curvature by the application of tensile forces less than those required to break the coated abrasive, said cured adhesive further being sufficiently rigid at a second temperature not less than 25°
C. so as to cause said coated abrasive to retain at said second temperature, in the absence of mechanical forces other than those induced by natural gravity, the curvature imparted to said coated abrasive at said first temperature and maintained during cooling from said first temperature to said second temperature.
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Accused Products
Abstract
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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Citations
20 Claims
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1. A coated abrasive having at least one layer of adhesive comprising the cured product of liquids containing chemical unsaturation and capable of rapid, spontaneous polymerization initiated by actinic radiation, said cured adhesive being sufficiently deformable at a first temperature of not more than 130°
- C. to be shaped, along with the backing on which it is coated, into a predetermined curvature by the application of tensile forces less than those required to break the coated abrasive, said cured adhesive further being sufficiently rigid at a second temperature not less than 25°
C. so as to cause said coated abrasive to retain at said second temperature, in the absence of mechanical forces other than those induced by natural gravity, the curvature imparted to said coated abrasive at said first temperature and maintained during cooling from said first temperature to said second temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- C. to be shaped, along with the backing on which it is coated, into a predetermined curvature by the application of tensile forces less than those required to break the coated abrasive, said cured adhesive further being sufficiently rigid at a second temperature not less than 25°
Specification