purchaser of chattel paper or an instrument who gives new value and takes possession of it in the ordinary course of his business has priority over a security interest in the chattel paper or instrument:

(a) Which is perfected under Section 9304 (permissive filing and temporary perfection) or under Section 9306 (perfection as to proceeds) if he acts without knowledge that the specific paper or instrument is subject to a security interest; or

(b) Which is claimed merely as proceeds of inventory subject to a security interest (Section 9306) even though he knows that the specific paper or instrument is subject to the security interest.