The HEF4059 is the same as a CD4059 and an MC14059. They operate from a supply from 3V to 18V. They have detailed spec's in their datasheet when the supply is 5V, 10V and 15V. The HEF datasheet says to look at another "Family Specifications" datasheet to see about supply voltage effects.
They operate at a higher frequency and have a higher output current when their supply voltage is high.
They operate at a higher frequency and have a higher output current when their supply voltage is high.