(a) Disposition of collateral: continuation of security interest or agricultural lien; proceeds. Except as otherwise provided in this article and in Section 2–403(2):

1. (1) a security interest or agricultural lien continues in collateral notwithstanding sale, lease, license, exchange, or other disposition thereof unless the secured party authorized the disposition free of the security interest or agricultural lien; and
2. (2) a security interest attaches to any identifiable proceeds of collateral.

(b) When commingled proceeds identifiable. Proceeds that are commingled with other property are identifiable proceeds:

1. (1) if the proceeds are goods, to the extent provided by Section 9–336; and
2. (2) if the proceeds are not goods, to the extent that the secured party identifies the proceeds by a method of tracing, including application of equitable principles, that is permitted under law other than this article with respect to commingled property of the type involved.

(d) Continuation of perfection. A perfected security interest in proceeds becomes unperfected on the twenty-first day after the security interest attaches to the proceeds unless:

1. (1) the following conditions are satisfied:

   1. (A) a filed financing statement covers the original collateral;
   2. (B) the proceeds are collateral in which a security interest may be perfected by filing in the office in which the financing statement has been filed; and
   3. (C) the proceeds are not acquired with cash proceeds;
2. (2) the proceeds are identifiable cash proceeds; or
3. (3) the security interest in the proceeds is perfected other than under subsection (c) when the security interest attaches to the proceeds or within 20 days thereafter.

(e) When perfected security interest in proceeds becomes unperfected. If a filed financing statement covers the original collateral, a security interest in proceeds which remains perfected under subsection (d)(1) becomes unperfected at the later of:

1. (1) when the effectiveness of the filed financing statement lapses under Section 9–515 or is terminated under Section 9–513; or
2. (2) the twenty-first day after the security interest attaches to the proceeds.