Method and apparatus for producing embossed structures in radiation-curing materials
For the production of embossed microstructures in radiation-curing materials, use is made of a micro embossing form fixed to a reflective or scattering cylinder surface. Via a press nip, the micro embossing form comes into contact with the substrate guided over a cylinder or a deflection roller. The radiation-curing material is acted on in one or both pockets, before or after the press nip, with radiation which penetrates into the press nip by reflection or scattering.
1. A method of producing embossed structures in radiation-curing material, the method comprising:
applying an embossing form to a surface of a cylinder or a sleeve and causing the embossing form to come into contact with the radiation-curing material in a linear press nip; and
irradiating the radiation-curing material with UV radiation for curing in a pocket following the press nip downstream in a transport direction of the radiation-curing material; and
wherein the surface of the cylinder or of the sleeve is reflective and/or scattering in a wavelength range of the UV radiation used for curing.
2. The method according to claim 1 , wherein the embossing form is a micro-embossing form and a material of the micro-embossing form is transparent to radiation in a wavelength range of the radiation used for the curing.
3. The method according to claim 1 , which comprises:
providing a first radiation source in a pocket upstream of the press nip in the transport direction of the radiation-curing material, wherein the first radiation source is dimensioned with respect to the wavelength and/or the power of the radiation such that the radiation-curing material is only partially cured and remains deformable as it enters the press nip; and
providing a second radiation source in the pocket following the press nip downstream in the transport direction of the radiation-curing material, wherein the a power and/or wavelength of the second radiation source is dimensioned such that the radiation-curing material is completely and thoroughly cured after having traversed the press nip.
4. The method according to claim 1 , wherein the radiation-curing material is a web product and the method further comprises coating the web product with liquid media.
5. The method according to claim 1 , which comprises embossing and curing security labels, printed electronics, optically readable codes or holograms.