WILMINGTON, Del. – MBNA Corp., a leading purchaser of credit union card portfolios and a specialist in affinity group card marketing, has purchased an estimated $50 million in affinity card portfolios from the Royal Bank of Canada, based in Toronto, Canada, according to media sources. The purchase adds 40 new affinity marketing partnerships to the 450 MBNA already has in Canada. An MBNA spokesman could not identify any of the partners, but said they include sports teams, colleges and universities and advocacy groups. The deal is expected to close June 30. MBNA has about $2.7 billion in loans through MBNA Canada, representing just under 9% of the market share, the source reported.