To expand on Paco's answer, de-icing fluids are only meant to be effective on the ground and are required to blow off the airframe usually by 100KT, airborne protection comes from the aircraft's own anti-icing and de-icing systems. There are
published tables of holdover times which show how long the fluid can be expected to be effective while the aircraft is parked or taxying. If you look at them you will see that the paramaters that affect holdover time include OAT, precipitation type and intensity and fluid concentration.