Liquid crystal phase

Abstract

Liquid crystal phases containing components of the formulae I and IIIhave an acceptable combination of threshold steepness, viewing angle and temperature dependence at a low threshold voltage.

We claim:  
     
       1. A liquid crystal phase consisting essentially of 4 to 36 wt.% of at least one component of the formula I                    
       wherein R 1  is alkyl of 1 to 12 C atoms; at least one component of the formula II 
       
         
           R 1 —A 2 —Phe—CN   II  
         
       
       wherein 
       A 2  is Cy, Phe, Phe—COO, Cy—COO, Phe—Phe, Phe—COO—Phe, Phe—PHe  Phe—COO—Phe, Cy—Phe or Cy—COO—Phe,  
       Cy is trans-1,4-cyclohexylene,  
       Phe is 1,4-phenylene, and  
       R 1  has the meaning indicated above,  
       whereby the total proportion of compounds of the formulae I and II is more than 5 wt.%, 22to 71 wt.% of one or more components of the formula III 
       
         
           R 1 —A 3 —COO—Phe—R 2    III  
         
       
       wherein A 3  is Cy or Phe, 
       R 1  and R 2  each are independently alkyl of 1 to 12 C atoms, and Cy and Phe have the meanings indicated above;  
       0 to 25 wt.% of one or more components of the formula IV and/or VI  
       
         
           R 1 —A 3 —(Z 1 —A 3 ) 2 —R 2    IV  
         
         
           
           
               
               
           
         
       
       wherein Z 1  independently is —CO—O— or —O—CO—, m is 0 or 1 and R 1 , R 2  and A 3  independently have the meanings indicated above; 
       and 0 to 28 wt.% of compounds of the formula Va  
       
         
           R 1 —Dio—Phe—CN   Va  
         
       
       wherein R 1  is alkyl of 1 to 7 C atoms, Dio is trans-1,3-dioxane-2,5-diyl and Phe is 1,4-phenylene. 
     
     
       2. A liquid crystal phase according to claim  1 , wherein said phase contains simultaneously compounds of formula III wherein A 3  is Cy and Phe. 
     
     
       3. A liquid crystal phase according to claim  1 , wherein said phase contains compounds of the formula IV selected from the following formulae IVa to IVf 
       
         
           R 1 —Phe—COO—Phe—COO—Phe—R 2    IVa  
         
       
       
         
           R 1 —Cy—COO—Phe—COO—Phe—R 2    IVb  
         
       
       
         
           R 1 —Phe—COO—Cy—COO—Phe—R 2    IVc  
         
       
       
         
           R 1 —Phe—OOC—Cy—COO—Phe—R 2    IVd  
         
       
       
         
           R 1 —Cy—COO—Cy—COO—Phe—R 2    IVe  
         
       
       
         
           R 1 —Cy—COO—Phe—COO—Cy—R 2    IVf.  
         
       
     
     
       4. A liquid crystal phase according to claim  1 , wherein said phase consists essentially of 
       10% of 4-cyano-4-fluorophenyl p-ethylbenzoate  
       9% of 4-cyano-3-fluorophenyl p-propylbenzoate  
       7% of 2-p-cyanophenyl-5-propyl-1,3-dioxane  
       20% of 4-cyanobiphenyl-4′-yl trans-4-ethylcyclohexanecarboxylate  
       10% of 4-propyl-4′-cyanobiphenyl  
       3% of 4-cyanobiphenyl-4′-yl p-(p-heptylphenyl)-benzoate  
       14.8% of p-pentylphenyl p-methylbenzoate  
       17.5% of p-pentylphenyl p-propylbenzoate  
       8.7% of p-pentylphenyl p-pentylbenzoate.  
     
     
       5. A liquid crystal phase according to claim  1 , wherein said phase consists essentially of 
       7% of 4-cyano-3-fluorophenyl p-ethylbenzoate  
       7% of 4-cyanobiphenyl-4′-yl trans-4-ethylcyclohexanecarboxylate  
       15% of 4-cyano-4′-(trans-4-pentylcyclohexyl)-biphenyl  
       4% of p-(p-propylhexoxycarbonyl)-phenyl trans-4-ethylcyclohexanecarboxylate  
       24.3% of pe-pentylphenyl  p- pentylphenyl  p-methylbenzoate  
       28.4% of p-pentylphenyl p-pentylbenzoate  
       14.3% of p-pentylphenyl p-pentylbenzoate.  
     
     
       6. A liquid crystal phase according to claim  1 , wherein said phase consists essentially of 
       10% of 4-cyano-3-fluorophenyl p-ethylbenzoate  
       10% of 4-cyano-3-fluorophenyl p-propylbenzoate  
       15% of 4-ethyl-4′-cyanobiphenyl  
       5% of 2-p-cyanophenyl-5-propyl-1,3-dioxane  
       20% of 4-cyanobiphenyl-4′-yl trans-4-ethylcyclohexanecarboxylate  
       2% of p-(p-propylphenoxycarbonyl)-phenyl trans-4-ethylcyclohexanecarboxylate  
       12% of p-propylphenyl trans-4-propylcyclohexanecarboxylate  
       14.6% of p-pentylphenyl trans-4-propylcyclohexanecarboxylate and  
       11.4% of p-heptylphenyl trans-4-propylcyclohexanecarboxylate.  
     
     
       7. A liquid crystal phase according to claim  1 , wherein said phase consists essentially of 
       10% of 4-cyano-3-fluorophenyl p-ethylbenzoate  
       8% of 4-cyanobiphenyl-4′-yl trans-4-ethylcyclohexanecarboxylate  
       8% of 4-cyano-4′-(trans-4-pentylcyclohexyl)-biphenyl  
       3% of 4-cyanobiphenyl-4′-yl p-(p-heptylphenyl)-benzoate  
       15.8% of p-pentylphenyl p-methylbenzoate  
       6.8% of p-pentylphenyl p-propylbenzoate  
       3.4% of p-pentylphenyl p-pentylbenzoate  
       14.2% of p-propylphenyl trans-4-propylcyclohexanecarboxylate  
       17.3% of p-pentylphenyl trans-4-propylcyclohexanecarboxylate and  
       13.5% of p-heptylphenyl trans-4-propylcyclohexanecarboxylate.  
     
     
       8. A liquid crystal phase according to claim  1 , wherein said phase consists  consisting essentially of 
       5% of 4-cyano-3-fluorophenyl p-ethylbenzoate  
       5% of 4-cyano-3-fluorophenyl p-propylbenzoate  
       10% of 4-ethyl-4′-cyanobiphenyl  
       15% of 4-butyl-4′-cyanobiphenyl  
       15% of p-ethoxyphenyl trans-4-propylcyclohexanecarboxylate  
       15% of p-methoxyphenyl trans-4-butylcyclohexanecarboxylate  
       10% of p-methoxyphenyl trans-4-pentylcyclohexanecarboxylate  
       10% of p-ethoxyphenyl trans-4-butylcyclohexanecarboxylate  
       6% of p-propylphenyl trans-4-(p-propylphenoxycarbonyl)cyclohexanecarboxylate  
       5% of p-butylphenyl trans-4-(p-butylphenoxycarbonyl)cyclohexanecarboxylate and  
       4% of p-pentylphenyl trans-4-(p-pentylphenoxycarbonyl)cyclohexanecarboxylate.  
     
     
       9. A liquid crystal phase according to claim  1 , wherein said phase consists  consisting essentially of 
       4% of p-cyanophenyl p-ethylbenzoate  
       4% of p-cyanophenyl p-propylbenzoate  
       4% of 4-cyano-3-fluorophenyl p-ethylbenzoate  
       4% of 4-cyano-3-fluorophenyl p-propylbenzoate  
       15% of p-trans-4-propylcylcohexyl-benzonitrile  p- trans -   4   - propylcyclohexyl - benzonitrile    
       10% of p-trans-4-butylcyclohexyl-benzonitrile  
       14% of p-ethoxyphenyl trans-4-propylcyclohexanecarboxylate  
       10% of p-methoxyphenyl trans-4-butylcyclohexanecarboxylate  
       10% of p-methoxyphenyl trans-4-pentylcyclohexanecarboxylate  
       10% of p-ethoxyphenyl trans-4-butylcyclohexanecarboxylate  
       6% of p-(p-butylphenoxycarbonyl)-phenyl p-butylbenzoate  
       5% of p-propylphenyl trans-4-(p-propylphenoxycarbonyl)cyclohexane carboxylate and  
       4% of p-pentylphenyl trans-4-(p-pentylphenoxycarbonyl)cyclohexane carboxylate.  
     
     
       10. A liquid crystal phase according to claim  1 , wherein said phase consists  consisting essentially of 
       10% of 4-cyano-3-fluorophenyl p-propylbenzoate  
       0.93% of p-propylphenyl trans-4-propylcyclohexane carboxylate  
       8.47% of p-pentylphenyl trans-4-propylcyclohexane carboxylate  
       6.6% of p-heptylphenyl trans-4-propylcyclohexane carboxylate  
       17% of 4-cyano-biphenyl-4′-yl trans-4-ethylcyclohexane carboxylate  
       10% of 4-pentyl-2-fluorophenyl trans-4-(trans-4-pentylcyclohexyl)-cyclohexane carboxylate  
       9% of trans-1-p-cyanophenyl-4-propylcyclohexane  
       4% of 4-ethyl-4′-cyanobiphenyl  
       14% of 2-p-cyanophenyl-5-propyl-1,3-dioxane and  
       14% of 2-p-cyanophenyl-5-pentyl-1,3-dioxane.  
     
     
       11. A liquid crystal phase according to claim  1 , wherein said phase consists essentially of 
       4% of 4-cyano-3-fluorophenyl p-propylbenzoate  
       16% of 4-cyano-biphenyl-4′-yl trans-4-ethylcyclohexane carboxylate  
       13.23% of p-propylphenyl trans-4-propylcyclohexane carboxylate  
       16.17% of p-pentylphenyl trans-4-propylcyclohexane carboxylate  
       b  12.6% of p-heptylphenyl trans-4-propylcyclohexane carboxylate  
       20% of trans-1-p-cyanophenyl-4-propylcyclohexane  
       13% of 4-pentyl-2-fluorophenyl 4-heptylbiphenyl-4′-carboxylate and  
       5% of 4-ethyl-4′-cyanobiphenyl.  
     
     
       12. In an electrooptical display element containing a liquid crystal phase, the improvement wherein said phase is a phase according to claim  1 . 
     
     
       13. A liquid crystal phase according to claim  1 , wherein the total proportion of compounds of formula I is 10-20 wt.%. 
     
     
       14. A liquid crystal phase according to claim  1 , wherein the total proportion of compounds of formulae I and II is 29-55 wt.%. 
     
     
       15. A liquid crystal phase according to claim  1 , wherein the total proportion of the components of formula III is 38-67 wt.%. 
     
     
       16. A liquid crystal phase according to claim  1 , wherein the total proportion of the components of formula IV is 4-15 wt.%. 
     
     
       17. A liquid crystal phase according to claim  1 , wherein the total proportion of the compounds of formula Va is 0-7 wt.%. 
     
     
       18. A liquid crystal phase according to claim  1 , wherein the total proportion of compounds of formulae I and II is more than 12 wt.%. 
     
     
       19. A liquid crystal phase according to claim  1 , wherein the total proportion of compounds of formulae I and II is 20-80 wt.%.