SECURITY DEVICE WITH TEMPERATURE ACTIVATABLE POLYMERIC LAYER

摘要

The present invention relates to improvements in security devices that can be used in varying shapes and sizes for authenticating or security applications. In particular, the invention refers to a durable security device (10) comprising a layer (12) that switches from opaque to transparent at a specified temperature. The security device (10) comprises an activatable layer (12) of polymeric material comprising a hard segment and crystallisable soft segment or at least one soft segment which is crosslinked and contains a crystallisable soft segment. The segments are selected to provide a predetermined activation temperature whereby the layer (12) is opaque at temperatures below the activation temperature and becomes transparent at temperatures above the activation temperature.