| 摘要 |
The invention relates to a new process for constructing electro-optical displays 1 that use a liquid crystal dispersed in a polymer (international acronym: polymer dispersed liquid crystal - PDLC) in which the polymer used in the process is an elastomer derived from cellulose. The displays consist of a porous film of a cellulose- derived elastomer (Fig. 1: 1) impregnated with liquid crystal in a birefringent mesophase (the liquid crystal fills the porous cavities of the polymeric film), this film being contained between two transparent supports (Fig. 1: 2 and 3) coated inside with a conducting deposit (Fig. 1: 5) and fixed by sealing supports (Fig. 1: 6). The cellulose-derived polymeric films used are obtained from I cellulose acetate AC, from II hydroxypropylcellulose HPC and from III esters of HPC in which the radicals added to the HPC are of the type R = - CO(CH2)nCH3 or R' = - CO(CH2)nC6H5 in which n can take the values from 0 to 5 [with an average degree of esterification (DE) of less than 3] and which are subsequently cross-linked with IV diisocyanates of the type OCN(CH2)nNCO in which n can be equal to 4 or 6 [1,4- butanodiisocyanate BDI] or 1,6-hexanodiisocyanate HDI or diphenylmethano 4,4'diisocyanate MDI or V bifunctional esters of the type CICO(CH2)nCOCI in which n can take values from 1 to 5 or of the type CICO(CH2)nC6H4(CH2)nCOICI in which n can take values from 0 to 4. The preparation of films of the elastomers obtained by the reaction IV or V with the polymers I or II or III is carried out from solutions of the polymers I or II or III, either isotropic or anisotropic, in different solvents of which acetone, ethanol and dimethylacetamide are examples; subsequently the cross-linking agent of type IV or V is to be added [to the] solution. These solutions are spread either directly onto the surface of the conducting supports of the cell (display) (1: 5), using a graduated rule so as to ensure an even distribution of the solution, or, according to the same method on a plane surface, the reaction times are optimized according to the quantity [of] cross-linking agent added. Solid films are obtained by controlled evaporation of the solvent. The liquid crystals used are those commercially available. <IMAGE>
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