A method of surface cross-linking superabsorbent polymer particles using
UV irradiation is provided. The method is carried out in a so-called drum
reactor, which comprises a hollow drum and an irradiation source. The
drum has a longitudinal axis and a cross-section. Radical former
molecules are applied on the surface of superabsorbent polymer particles.
These superabsorbent polymer particles are fed into the drum and are
irradiated while they move within the drum, which is rotated around its
longitudinal axis. The irradiation source is provided such that the
radiation emitted by the irradiation source is able to reach
superabsorbent polymer particles within said drum. The irradiation source
for use in the method is able to emit UV radiation of a wavelength
between about 201 nm and about 400 nm.