Monomers and their use for the production of a laser-optical recording element which can be repeatedly erased and recorded on

US5187298A · kind A · utility

Assignee

• BASF SE

Inventors

• Kark-Heinz Etzbach · Bischofswerda, DE
• Gerhard Wagenblast · Wachenheim, DE
• Wolfgang Brox · Heidelberg, DE
• Axel Paul · Lampertheim, DE
• Volker Bach · Neustadt, DE

Key dates

• Filing date: May 18, 1990
• Grant date: Feb 16, 1993
• Expiry date: May 18, 2010

Classification

• Technology area (CPC G): Physics
• CPC primary: G11B7/25
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

Novel laser-optical recording elements which can be repeatedly erased and recorded on contain recording layers (a) which exhibit enantiotropic, ferroelectric smectic liquid crystalline (S.sub.C*) behavior, so that they can be switched back and forth between two thermodynamically stable, optically distinguishable ferroelectric smectic liquid crystlaline S.sub.C* order states on exposure to a laser beam of sufficient luminous power, by applying an external electric field. The recording layers (a) themselves consist mainly or exclusively of novel polymers P having chiral mesogenic side groups. The novel polymers P are prepared using the novel monomers of the general formula I ##STR1## where R is hydrogen, chlorine or methyl, A is a flexible space-maintaining long-chain molecular moiety, and C is an optically active chiral molecular moiety and B is a mesogenic molecular moiety composed of at least three aromatic nuclei which are bonded linearly or virtually linearly to one another, or they are prepared using the novel monomers I which contain specially selected molecular moieties B in a novel combination with selected molecular moieties C.