The present invention provides a composition for use in coated abrasives. The curable composition comprises a mixture of: i) from about 30 to about 60 weight percent of an oligomeric aminoplast resin having on average at least one pendant α,β-unsaturated carbonyl group per oligomeric unit; ii) from about 70 to about 40 weight percent of a thermoplastic polyamide miscible in said aminoplast resin, the weight percents being based on the total resin content; and iii) a sufficient amount of a catalyst for the curable oligomeric aminoplast resin having on average at least one pendant α,β-unsaturated carbonyl group per oligomeric unit, said catalyst being stable at a temperature of mixing of the components. The curable composition can either be in the form of a melt-processable solid or a molten mixture. The present invention also provides single and multilayered treated backing substrates used in coated abrasives.