Rate Series 2006A Senior Notes (Tranche 2 Notes). Tranche 1 Notes bear interest of 5.53% per annum, payable semi- annually. Tranche 2 Notes bear floating rate interest, payable quarterly. The average interest rate on Tranche 2 for the years  ended December 31, 2013 and December 31, 2012 was 0.73% and 0.92%, respectively. The principal payment for both  tranches was due on October 5, 2013. The Company repaid this obligation in 2013. MINERALS TECHNOLOGIES INC. AND SUBSIDIARY COMPANIES  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS  In January 2011 , the Company entered into a Renminbi (“RMB”) denominated loan agreement at its Refractories facility  in China with the Bank of America totaling RMB 10.6 million, or $1.6 million. Principal of this loan was payable in  installments over three years. Interest was payable semi-annually and was based upon the official RMB lending rate  announced by the People’s Bank of China. The  average interest rate for the year ended December 31, 2013 was 6.8%. This  obligation was repaid in 2013.  On October 7, 2013, the Company entered into, through private placement, a Note Purchase Agreement and issued $75  million aggregate principal amount of senior unsecured notes, consisting of (a) $30,000,000 aggregate principal amount  3.46% Senior Notes, Series A, due October  7, 2020 (the “Series A Notes”), and (b) $45,000,000 aggregate principal amount  4.13% Senior Notes, Series B, due October 7, 2023 (the “Series B Notes” and, together with the Series A Notes, the  “Notes”). The Company used the proceeds of the Notes to repa y its $75 million aggregate principal amount of senior  unsecured notes which were due October 5, 2013.  The aggregate maturities of long-term debt are as follows: 2014 - $8.2 million; 2015 - $-- million; 2016 - $-- million; 2017  - $-- million; 2018 - $-- million; thereafter - $75.0 million.  The Company had available approximately $189.7 million in uncommitted, short-term bank credit lines, of which $5.5  million was in use at December 31, 2013.  Short-term borrowings as of December 31, 2013 and 2012 were $5.5 million and $7.1 million, respectively. The weighted  average interest rate on short-term borrowings outstanding as of December 31, 2013 and 2012 was 4.8% and 5.8%,  respectively.  During 2013, 2012 and 2011, respectively, the Company incurred interest costs of $3.4 million, $3.5 million and $3.5  million including $0.1 million, $0.3 million and $0.3 million, respectively, which were capitalized. Interest paid  approximated the incurred interest cost.  F-20  Note 14. Benefit Plans Pension Plans and Other Postretirement Benefit Plans The Company and its subsidiaries have pension plans covering the majority of eligible employees on a contributory or  non-contributory basis.  Benefits under defined benefit plans are generally based on years of service and an employee's career earnings. Employees  generally become fully vested after five years.  The Company provides postretirement health care and life insurance benefits for the majority of its U.S. retired  employees. Employees are generally eligible for benefits upon retirement and completion of a specified number of years of  creditable service. The Company does not pre-fund these benefits and has the right to modify or terminate the plan in the  future.  The funded status of the Company's pension plans and other postretirement benefit plans at December 31, 2013 and 2012  is as follows: 