Hi!
I have been using 74HCT595 for the purpose like yours.It isn't i2c chip,it is 8-bit shift register with serial input, clock input and latches on outputs (so when you move bits, you cannot see blinking). It has also serial output so you can simply expand the number of digits.
I have been using it to drive via serial interface 35 led digits and it is working fine.

Jacek