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

Claim 1

A laser-optical recording element which can be repeatedly erased and recorded on, containing a) a recording layer having a thickness (d) which exhibits enantiotropic, ferroelectric smectic liquid crystalline (S c* ) behavior and can be switched back and forth between two thermodynamically stable, optically distinguishable ferroelectric smectic liquid crystalline S c* order states on exposure to a laser beam of sufficient luminous power by applying an external electric field, the said recording layer (a) containing at least one polymer I having chiral mesogenic pendant side groups exhibiting ferroelectric smectic liquid crystalline behavior and comprising monomer units derived from monomers of the structure I ##STR124## where R is hydrogen, chlorine or methyl, A is a flexible space-maintaining long-chain molecular moiety having the formula --(CH 2 --) R -- where R is an integer of from 1 to 30, C is an optically active chiral molecular moiety and B is a mesogenic molecular moiety which consists of three or more aromatic nuclei bonded linearly or virtually linearly to one another and which is selected from the group consisting of i) moieties B which contain one or more napth-2,6-ylene groups, ii) moieties B of the formula II ##STR125## where B 2 is a p-phenylene, a biphenyl-4-4'-diyl or a napth-2,6-ylene group, Y is an ether, an ester, a thioester group or a carbon-carbon single bond and m and n are each 0 or an integer ≧1; iii) moieties B of the formula IV ##STR126## where m and n and Y have the abovementioned meanings and B 3 is selected from the group consisting of the p-phenylene, the biphenyl-4-4'-diyl and the napth-2,6-ylene group and the group III-1 ##STR127## where Y has the abovementioned meanings; and iv) moieties B, selected from the group consisting of the groups X-1 to X-4 ##STR128## where Y has the abovementioned meanings and the groups X-1 to X-4 are bonded via the ether group to moiety A, with the proviso that the moiety C of the molecule is exclusively selected from the group consisting of the pinan-3-yl, the camphan-2-yl and the p-methan-3-yl group and the group of the formula VII ##STR129## where R 3 is methyl or trifluoromethyl, x and r independently of one another are each 0 or 1 and s is an integer from 1 to 3, the group of the formula VIII ##STR130## where s has the abovementioned meaning, and the group of the formula IX ##STR131## where t, u and v independently of one another are each an integer of from 1 to 10, t and u independently of one another may furthermore be 0, and y is 0 or 1, whenever one of the said groups X-1 to X-4 is selected for moiety B of the molecule.

Claim 22

A method for repeated recording, reading, and erasing of data, comprising the steps of (1) recording digital or analog data with the aid of a write laser beam of sufficient luminous power, if necessary with the application of an external electric field, in the ferroelectric smectic liquid crystalline (S c* ) recording layer (a) having a thickness (d) of a laser-optical recording element in the form of optically detectable regions which are stable at room temperature and which are ferroelectric smectic liquid crystalline S c* phases, smectic liquid crystalline S A* phases, disordered microdomains (scattering centers) or isotropic i phases, the said ferroelectric smectic liquid crystalline (S c* ) recording layer (a) containing at least one polymer I having chiral mesogenic side groups exhibiting ferroelectric smectic liquid crystalline behavior and comprising monomer units derived from monomers of the structure I ##STR140## where is hydrogen, chlorine or methyl, A is a flexible space-maintaining long-chain molecular moiety having the formula --(--CH 2 --) R -- where R is an integer from 1 to 30, is an optically active chiral molecular moiety and B is a mesogenic molecular moiety which consists of three or more aromatic nuclei bonded linearly or virtually linearly to one another and which is selected from the group consisting of i) moieties B which contain one or more napth-2,6-ylene groups, ii) moieties B of the formula III ##STR141## where B 2 is a p-phenylene, a biphenyl-4,4'-diyl or a napth-2,6-ylene group Y is an ether, an ester a thioester group or a carbon-carbon single bond and m and n are each 0 or an integer ≧1; iii) moieties b of the formula IV ##STR142## where m and n and Y have the abovementioned meanings and B 3 is selected from the group consisting of the p-phenylene, the biphenyl-4-4'-diyl and the napth-2,6-ylene group and the group III-1 ##STR143## where Y has the abovementioned meanings; and iv) moieties B, selected from the group consisting of the groups X-1 to X-4 ##STR144## where Y has the abovementioned meanings and the groups X-1 to X-4 are bonded via the ether group to moiety A, with the proviso that the moiety C of the molecule is exclusively selected from the group consisting of the pinan-3-yl, the camphan-2-yl and the p-menthan-3-yl group and the group of the formula VII ##STR145## where R 3 is methyl or trifluoromethyl, x and r independently of one another are each 0 or 1 and s is an integer from 1 to 3, the group of the formula VIII ##STR146## where s has the abovementioned meaning, and the group of the formula IX ##STR147## where t, u and v independently of one another are each an integer of from 1 to 10, t and u independently of one another may furthermore be 0, and y is 0 or 1, whenever one of the said groups X-1 to X-4 is selected for moiety B of the molecule, (2) detecting the recorded data or regions with the aid of a read laser beam by means of the birefringence contrast, the dichroic contrast, light scattering at scattering centers and/or interference of reflected laser light waves of different phase velocities, the light reflected by the recording element being analyzed, and then (3) erasing the recorded data or regions completely or sector by sector by heating the entire surface or individual sectors of the recording layer (a) in an external electric field, and (4) repeating process steps (1) and (2).

Claim 23

A method for repeated recording, reading, and erasing of data, comprising the steps of (1) recording digital or analog data with the aid of a write laser beam of sufficient luminous power, if necessary with the application of an external electric field, in the ferroelectric smectic liquid crystalline (S c* ) recording layer (a) having a thickness (d) of a laser-optical recording element in the form of optically detectable regions which are stable at room temperature and which are ferroelectric smectic liquid crystalline S c* phases, smectic liquid crystalline S A* phases, disordered microdomains (scattering centers) or isotropic i phases, the said ferroelectric smectic liquid crystalline (S c* ) recording layer (a) containing at least one polymer I having chiral mesogenic side groups exhibiting ferroelectric smectic liquid crystalline behavior and comprising monomer units derived from monomers of the structure I ##STR140## where is hydrogen, chlorine or methyl, A is a flexible space-maintaining long-chain molecular moiety having the formula --(--CH 2 --) R -- where R is an integer from 1 to 30, is an optically active chiral molecular moiety and B is a mesogenic molecular moiety which consists of three or more aromatic nuclei bonded linearly or virtually linearly to one another and which is selected from the group consisting of i) moieties B which contain one or more napth-2,6-ylene groups, ii) moieties B of the formula III ##STR141## where B 2 is a p-phenylene, a biphenyl-4,4'-diyl or a napth-2,6-ylene group Y is an ether, an ester a thioester group or a carbon-carbon single bond and m and n are each 0 or an integer ≧1; iii) moieties b of the formula IV ##STR142## where m and n and Y have the abovementioned meanings and B 3 is selected from the group consisting of the p-phenylene, the biphenyl-4-4'-diyl and the napth-2,6-ylene group and the group III-1 ##STR143## where Y has the abovementioned meanings; and iv) moieties B, selected from the group consisting of the groups X-1 to X-4 ##STR144## where Y has the abovementioned meanings and the groups X-1 to X-4 are bonded via the ether group to moiety A, with the proviso that the moiety C of the molecule is exclusively selected from the group consisting of the pinan-3-yl, the camphan-2-yl and the p-menthan-3-yl group and the group of the formula VII ##STR145## where R 3 is methyl or trifluoromethyl, x and r independently of one another are each 0 or 1 and s is an integer from 1 to 3, the group of the formula VIII ##STR146## where s has the abovementioned meaning, and the group of the formula IX ##STR147## where t, u and v independently of one another are each an integer of from 1 to 10, t and u independently of one another may furthermore be 0, and y is 0 or 1, whenever one of the said groups X-1 to X-4 is selected for moiety B of the molecule, (2) detecting the recorded data or regions with the aid of a read laser beam by means of the birefringence contrast, the dichroic contrast, light scattering at scattering centers and/or interference of reflected laser light waves of different phase velocities, the light reflected by the recording element being analyzed, and then (3) erasing the recorded data or regions completely or sector by sector by heating the entire surface or individual sectors of the recording layer (a) in an external electric field, and (4) repeating process steps (1) and (2).