<p>The invention relates to core-shell particles, the core of which is essentially solid with an essentially monodisperse size distribution, with a difference between the refractive index of the core material and the shell material. The core is made from a material which either does not flow or does so at a temperature above the flow temperature of the shell material and the shell is connected to the core by means of an intermediate layer, characterised in that the shell is made from a copolymer with at least one C4-C8 alkylacrylate and at least one C4-C8 alkyl- or -alkylarylmethacrylate as monomer component.</p>
