* 3M sees deal to improve product line
* Sees deal to add to earnings, ex-items
* Says offer conditional upon 66.67 percent shares tendered
* Winterthur chairman agreed to tender his 14 percent stake
(Adds details)
Dec 6 (Reuters) - 3M Co said it will buy Swiss precision grinding technology supplier Winterthur Technologies AG for about $448 million in an effort to provide a broader range of industrial grinding and finishing solutions.
Under the agreement, the U.S.-based 3M will pay 62.00 Swiss francs ($63.56) for each share through a public tender offer and the offer is conditional upon a tendering of 66.67 percent of the shares of Winterthur.
The deal, which is expected to close in the first-quarter of 2011, will slightly add to earnings, excluding items, in the first 12 months following the completion, the company said.
Winterthur's Chairman Dr. Edgar Rappold will also tender his stake of 14 percent in Winterthur as part of the agreement, 3M said.
Winterthur's shares closed at 58.00 francs on Friday. 3M stock closed at $86.94 Friday on the New York Stock Exchange. (Reporting by Abhinav Sharma in Bangalore; Editing by Jon Loades-Carter)