摘要:
The invention relates to a liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR1## in which Hal is fluorine or chlorine and R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms.
摘要:
Catalyst systems for the polymerization of C.sub.2 -C.sub.10 -alk-1-enes contain, as active components,a) a metallocene complex of the general formula I ##STR1## where M is titanium, zirconium, hafnium, vanadium, niobium or tantalum, X is halogen or C.sub.1 -C.sub.8 -alkyl, Y is carbon, phosphorus, sulfur, silicon or germanium, Z is C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.10 -cycloalkyl or C.sub.6 -C.sub.10 -aryl, R.sup.1 and R.sup.2 are identical or different and are each C.sub.1 -C.sub.4 -alkyl, R.sup.3 to R.sup.6 are identical or different and are each hydrogen or C.sub.1 -C.sub.8 -alkyl, or two adjacent radicals R.sup.3 and R.sup.4 and R.sup.5 and R.sup.6 in each case together form a hydrocarbon ring system of 4 to 15 carbon atoms and n is 0, 1 or 2, andb) an open-chain or cyclic alumoxane compound of the general formula II or III ##STR2## where R.sup.7 is C.sub.1 -C.sub.4 -alkyl and n is from 5 to 30. The novel catalyst systems are particularly suitable for the preparation of polyalk-1-enes having high molecular weights.
摘要:
Benzene derivatives of the formula I ##STR1## in which n is 1 to 7, Q is --CO or --(CH.sub.2).sub.r --, where r is 1 to 5, s is 0, 1 or 2, t is 0 or 1, where s+t.gtoreq.1, X is F, Cl, --CF.sub.3, --CN, --OCF.sub.3 or --OCHF.sub.2, and Y, L and Z are each, independently of one another, H or F.
摘要:
The invention relates to a liquid-crystalline medium essentially comprisinga) 5-65% by weight of a component A, comprising two or more compounds selected from group A: ##STR1## b) 20-95% by weight of a component B comprising two or more compounds selected from group B: ##STR2## and c) 0-40% by weight of a component C, comprising one or more compounds having a clearing point above 170.degree. C., where R, X and Y each, independently of one another, have the following meanings:R is in each case alkyl, oxaalkyl, haloalkyl or alkenyl having up to 7 carbon atoms,X is F, Cl, CHF.sub.2, CF.sub.3, OCHF.sub.2 or OCF.sub.3, andY is H, F or Cl.
摘要:
A process for propene oligomerization catalyzed by transition metal complexes in liquid phase to give propene oligomers with a high content of terminal double bonds, comprises oligomerizing propene in the presence of a catalyst of the formula ICp.sub.2 MX.sub.2 Iwhere Cp is an unsubstituted cyclopentadienyl unit and/or a mono-C.sub.1 -C.sub.4 -alkylcyclopentadienyl unit, M is zirconium or hafnium and the ligands X are each hydride and/or halide and/or methyl, and in the presence of an aluminoxane cocatalyst, and where the ratio of the amounts of the catalyst I and the aluminoxane cocatalyst is such that the M/Al atomic ratio is from 1:250 to 1:1000, employing a temperature of from 50.degree. to 110.degree. C. and a pressure of from 30 to 100 bar.
摘要:
The invention relates to novel halogenated benzene derivatives of the formula I ##STR1## in which n is 1 to 7 [sic], the rings A and B are each trans-1,4-cyclohexylene, or one of the rings A and B is alternatively 1,4-phenylene or 3-fluoro-1,4-phenylene, X is F, Cl, --CHF.sub.2, --CF.sub.3, --CN, --OCF.sub.3 or --OCHF.sub.2, Y and Z are each, independently of one another, H or F, r=1 or, in the case where s=1, B=trans-1,4-cyclohexylene and simultaneously X=CHF.sub.2, --CF.sub.3, --OCF.sub.3 or --OCHF.sub.2, r is alternatively 0, and s=1 or, in the case where B=1,4-phenylene or 3-fluoro-1,4-phenylene, s=0.
摘要:
The invention relates to electro-optical systems containing an addressable liquid-crystal layer and a device for compensating for the optical path difference d.multidot..DELTA.n of the addressable liquid-crystal layers, the compensating device being based on a liquid-crystalline polymer.
摘要:
Hydroxymethyl-functional siloxanes and silica gels are prepared by reacting a siloxacycle having at least one unit of the formula [SiR2(OR3)—CH2—O]n with water, optionally in the presence of a hydrolyzable silane.
摘要:
The invention relates to compensation films for liquid-crystal displays with additions of rod-shaped liquid crystals mentioned below, to polarizer plates which have at least one compensation film of this type, to liquid-crystal displays which have compensation films of the said type, and to processes for the production of the said compensation films, polarizer plates and liquid-crystal displays, to the use of the compounds described in greater detail below as additions to compensation films for liquid-crystal displays, and to further subject-matters of the invention which can be seen below.