Abstract: The invention relates to a method of producing platelets, wherein a material to be processed into platelets is applied in a flowable or gaseous state to a substrate, consolidated, removed from the substrate, and subjected to a crushing or grinding process, wherein the material is applied to the substrate in succeeding layers such that after application, a lamina pack is present which, in cross section perpendicular to its surface, has individual laminae of a thickness of between 0.2-1000 &mgr;m, and said lamina pack, having been stripped from the substrate, is treated in such a way that the material disintegrates into individual laminae and the individual laminae are reduced in size to a particle size of 0.5-10000 &mgr;m.

Abstract: A mixture of crosslinkable liquid-crystalline substances having a chiral phase (LC mixture), containing polymerizable groups, where at least 90% of the polymerizable groups are part of molecules containing at least two polymerizable groups (crosslinker molecules), wherein from 3.2 to 15 mmol of polymerizable groups are present per g of LC mixture. The crosslinked pigments show little color shift in the presence of solvents or upon application to substrate different temperatures.

Abstract: The invention relates to a method of producing platelets, wherein a material to be processed into platelets is applied in a flowable or gaseous state to a substrate, consolidated, removed from the substrate, and subjected to a crushing or grinding process, wherein the material is applied to the substrate in succeeding layers such that after application, a lamina pack is present which, in cross section perpendicular to its surface, has individual laminae of a thickness of between 0.2-1000 &mgr;m, and said lamina pack, having been stripped from the substrate, is treated in such a way that the material disintegrates into individual laminae and the individual laminae are reduced in size to a particle size of 0.5-10 000 &mgr;m.

Abstract: The invention relates to mixtures containing pigments which comprise oriented three-dimensionally crosslinked substances having a liquid-crystalline structure with a chiral phase, and to the use of such mixtures. Pigment and matrix are matched to one another in such a way that on application of the mixture at different temperatures to a substrate, the lowest application temperature and highest application temperature differing by at least 10° C. and by not more than 150° C., there are no visually perceptible color differences of the pigmented paint on the substrate after drying.

Abstract: The invention relates to a process for the preparation of three-dimensionally crosslinked polymeric materials having a broad cholesteric reflection band, which comprises bringing polymeric materials having cholesteric properties and an extractable material content into contact with a solvent or solvent mixture.

Abstract: Process for broadening cholesteric reflection bands of photopolymerizable cholesteric liquid crystals, and optical elements produced by this process. The invention relates to a process for broadening the cholesteric reflection bands of photopolymerizable cholesteric liquid crystals, which comprises the following process steps:1) partial polymerization of a layer containing photopolymerizable cholesteric liquid crystals by exposure to actinic light for a defined brief period at a defined temperature,2) observance of a defined waiting time without exposure (dark phase) at a defined temperature,3) fixing of the resultant layer by exposure to actinic light at a defined temperature.

Abstract: Organosiloxanes having low transition temperatures comprise at least one group of the general formula 1--(CH.sub.2).sub.p --(O).sub.q --C.sub.6 H.sub.4 --Z--(COO).sub.s --[A--M].sub.t --E--(CH.sub.2 --CH.sub.2 --O).sub.a --VN (1)and, if desired, a group of the general formula 2--(CH.sub.2).sub.m --(O).sub.n --(A).sub.t --Q--X (2)whereVN is a group --COO--CH.dbd.CH.sub.2, --COO--C(CH.sub.3).dbd.CH.sub.2, --(CH.sub.2).sub.u --OCH.dbd.CH.sub.2, --CH.dbd.CH.sub.2 or an oxiranyl group and X, Z, A, M, Q, E, m, n, p, q, r, s, t, u, v and a are as defined herein.

Abstract: Liquid-crystalline materials having a cholesteric phase with a pitch of less than 400 nm, comprising a) liquid-crystalline organosiloxanes containing dianhydrohexitol derivatives as chiral groups, and b) chiral monomeric additives which induce the same helicality as the respective liquid-crystalline organo-siloxanes.

Abstract: The liquid crystalline organosiloxanes contain per molecule at least one doristeryl group bonded at the 3.beta. position and can be used as right-handed filter materials and optical media.

Abstract: Wavelength-selective and polarization-selective optical elements contain pigments embedded in a transparent binder, in which the pigments include at least one three-dimensionally crosslinked substance having a liquid-crystalline structure with a chiral phase.

Abstract: The invention relates to optical elements having image-forming, color- and polarization-selective reflection and containing cholesteric liquid crystals, and to the preparation and use of these elements. In the wavelength- and polarization-selective elements which form an optical image, at least one cholesteric liquid crystal is enclosed in the cavity of constant thickness between two light-transmitting substrates having curved surfaces in such a way that the helix axis of the liquid crystal is aligned perpendicular to the curved surface of the light-transmitting substrates. The elements are suitable for use as beam splitters or recombiners in projection displays.

Abstract: Liquid-crystalline polyorganosiloxanes containing methacryloxy and/or acryloxy groups are prepared by reaction of polyorganosiloxanes containing hydrogen atoms bonded directly to silicon atoms with alkenes and/or alkynes containing mesogenic groups in two steps, wherein the polyorganosiloxanes mentioned are reacted in a first step with alkene and/or alkyne containing mesogenic groups and are reacted in a second step with an alkene and/or alkyne containing at least one methacryloxy and/or acryloxy group and mesogenic groups.

Abstract: The liquid-crystalline organosiloxanes containing, per molecule, at least one Si--C-bonded chiral tartarimide radical of the formula ##STR1## in which M, A.sup.5 and k are as defined in claim 1, can be employed as chiral filter materials, for decorative purposes and in optical elements.

Abstract: Organosilsesquioxanes having at least one mesogenic side group and processes for their preparation, which comprise reacting organosilsesquioxanes having at least one Si-bonded hydrogen atom with chiral or achiral mesogenic compounds containing an aliphatic multiple bond.

Abstract: A compound of the general formulaM--(CH.sub.2).sub.n --(O).sub.m --[--D--B--].sub.q --Y, (I)in which M represents a silicon radical having 2 to 5 silicon atoms which are linked together by bridging elements A, and the remaining valencies of the silicon atoms are saturated with radicals R; A is a bridging element selected from the group consisting of C.sub.1 - to C.sub.8 -alkylene radicals and oxygen with the proviso that at least one radical A per M radical is a C.sub.1 - to C.sub.8 -alkylene radical; R represents optionally fluorine or chlorine atom- or cyano group-substituted straight-chain C.sub.1 - to C.sub.10 -alkyl or C.sub.2 - to C.sub.10 -alkenyl radicals, branched chain C.sub.3 - to C.sub.10 -alkyl or C.sub.3 - to C.sub.10 -alkenyl radicals, optionally C.sub.1 - to C.sub.4 -alkyl- , C.sub.1 - to C.sub.4 -alkoxy radicals, fluorine, chlorine, bromine atom, cyano, trifluoromethyl or nitro radical substituted C.sub.6 - to C.sub.12 -cycloalkyl, C.sub.6 - to C.sub.12 -cycloalkenyl, C.sub.6 - to C.sub.

Abstract: The invention relates to pigments whose color depends on the viewing angle, their preparation and use.These pigments comprise oriented three-dimensionally crosslinked substances of liquid-crystalline structure having a chiral phase and, if desired, further dyes and pigments, the further dyes and pigments if present not serving as base for the oriented three-dimensionally crosslinked liquid-crystalline substances having a chiral phase.

Abstract: Hydrophilic, water-dilatable cyclodextrin polymerizates have a high cyclodextrin content and possess good mechanical properties. The cyclodextrin pearl polymerizates are produced by reacting hydroxyalkyl cyclodextrin derivatives with bifunctional crosslinking agents such as epichlorohydrin or diepoxides, followed by hydroxyalkylation of the primary product so obtained. The cyclodextrin polymerizates produced in this manner have mechanical properties appreciably superior to those of known, comparable cyclodextrin polymers.

Abstract: The invention relates to optical elements based on liquid-crystalline substances, and to a process for the production thereof. The optical elements based on liquid-crystalline substances are ones which exhibit no birefringence in a defined direction of incidence, optical elements in which no birefringence occurs perpendicularly to the surface being excepted. The process for preparing the optical elements comprises illuminating a liquid-crystalline substance with unpolarized light of suitable wavelength at a defined angle in such a way that, after illumination, the director of this substance is aligned parallel to the direction of the illuminating light on passing through said substance.

Abstract: A hydrophilic, water-dilatable cyclodextrin polymerizate has a high cyclodextrin content which possesses good mechanical properties. The cyclodextrin pearl polymerizates are produced by radical, inversion suspension polymerization of cyclodextrin derivatives carrying methacrylate groups or their copolymerization with suitable comonomers such as hydroxyethylacrylate or hydroxymethylacrylate. Suitable cyclodextrin derivatives can be produced by reacting cyclodextrins or hydroxyalkyl cyclodextrins with methacrylic anhydride or with glycidyl methacrylate. The cyclodextrin polymerizates produced in this manner have mechanical properties appreciably superior to those of known, comparable cyclodextrin polymers.

Abstract: The present invention relates to compounds of the formula ##STR1## in which Z is a halogen atom, a cyano group or a hydroxyl group,n is 0, 1 or 2,R' is a radical of the formulaR"'--[Si(R*).sub.2 ].sub.x (CH.sub.2).sub.y R""-- (9),in whichx is the number 0 or 1,y is an integer from 1 to 18,R"'is a defined in the description,R* is identical or different, optionally substituted C.sub.1 - to C.sub.18 -hydrocarbon or hydrocarbonoxy radicals,R"" is a phenylene or biphenylene radical or a radical of the formula --E--, whereE is a divalent radical of the formula --O-- or --[Si(R*).sub.2 ].sub.z --, andz is the number 0 or 1,and the compounds contain at least one group of the formula --Si(R*).sub.2 -- per molecule, and the radicalR" is a cholesteryl radical, a radical as defined for R* or a radical of the formula --C.sub.6 H.sub.4 --R*,and the preparation and use thereof.