RELATED APPLICATIONS

Under 35 USC 371, this is the national stage of international application PCT/IB2015/002668, filed on Nov. 13, 2015.

FIELD OF INVENTION

The invention relates to fraud prevention, and in particular, to hindering counterfeiting and forgery.

BACKGROUND

Known methods of manufacturing multilayer structures for use in anti-counterfeiting and anti-forgery applications require precise alignment of the various layers. This adds complexity to the manufacturing process. The complex additional process steps increase manufacturing time and costs.

It is also known to manufacture a multilayer structure that has a window laminated with a transparent layer made of thermoplastic material. Both layers have a window. The transparent layer will be part of the final multilayer-structure as it will be used. But, such a multilayer structure obtained with such a process may have faults and deformations.

SUMMARY

The invention relates to improvements in the domain of processes for manufacturing multilayer structures comprising a non-opaque window. Such a non-opaque window, which may be transparent, is used for instance in security documents or cards having laminate structures, for increasing the difficulty to counterfeit and forge them.

In one aspect, the invention includes manufacturing a non-opaque layer to be included in a multilayer structure comprising at least one non-opaque window. The non-opaque layer is made with a region having an extra-thickness that is more easily inserted and aligned with the window or cut-out made in an adjacent layer.

The region with the extra-thickness may sufficiently fill this window or cut-out for avoiding the use of patches in the window. Furthermore, a patterned plate that is heated for making the non-opaque material flowing in its cavity is removed and is not part of the final structure. The material of the patterned plate can be specifically chosen for its function, i.e. forming a cavity within which the non-opaque material can flow for shaping the region with the extra-thickness.

