The trustees shall not utilize any of the contributions collected as premiums for any purpose unrelated to the pool. Moneys not needed for current obligations may be invested by the trustees. Such investments shall be limited to investments permitted by Kan. Stat. Ann. §§ 12-1677b and 75-4209, and amendments thereto, except that a pool which has been in existence for at least five years shall be permitted to invest in any of the securities or other investments permitted by article 2a of chapter 40 of the Kansas Statutes Annotated.