Process for controlling layer spacing in mixtures of smectic liquid crystal compounds

• US 5,417,883 A
• Filed: 04/11/1994
• Issued: 05/23/1995
• Est. Priority Date: 04/11/1994
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Company
• Inventors: Epstein, Kenneth A., Radcliffe, Marc D., Keyes, Michael P., Snustad, Daniel C.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US08/225,882
• Time in Patent Office: 407 Days
• Field of Search: 252/299.01, 359/99, 359/100
• US Class Current: 252/299.01
• CPC Class Codes: B65B 2220/10 Creating an off-center longitudinal seal on horizontal or vertical form fill seal [FFS] machines
• CPC Class Codes: B65B 61/025 for applying, e.g. printing, code or date marks on material prior to packaging
• CPC Class Codes: B65B 9/073 the web having intermittent motion B65B9/08 takes precedence
• CPC Class Codes: C09K 19/02 characterised by optical, electrical or physical properties of the components, in general
• CPC Class Codes: C09K 19/3469 Pyrimidine with a specific end-group other than alkyl, alkoxy or -C*-
• CPC Class Codes: G02F 1/1416 Details of the smectic layer structure, e.g. bookshelf, chevron, C1 and C2

Abstract

A process for controlling layer spacing in mixtures of smectic liquid crystal compounds comprises the step of combining a liquid crystal composition having a net negative thermal layer expansion in at least one tilted (or latent tilted) smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted (or latent tilted) smectic mesophase, each of the compositions comprising at least one smectic or latent smectic liquid crystal compound. The process enables control of layer spacing in the tilted smectic mesophase(s) and thereby control or suppression of chevron layer geometry.

Claims

1. A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, so as to form a mixture of liquid crystal compounds having a controllable layer expansion or contraction behavior.

2. The process of claim 1 wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has an essentially temperature-independent layer spacing in at least one tilted smectic mesophase.

6. The process of claim 1 wherein said composition having a net negative thermal layer expansion comprises at least one chiral or achiral liquid crystal compound having at least one fluorinated terminal portion.

7. The process of claim 6 wherein said compound has at least one fluoroether terminal portion containing at least two catenary ether oxygen atoms.

8. The process of claim 7 wherein said compound comprises (a) an aliphatic fluorocarbon terminal portion containing at least two catenary ether oxygen atoms;

(b) an aliphatic hydrocarbon terminal portion; and

(c) a central core connecting said terminal portions.

9. The process of claim 8 wherein said aliphatic fluorocarbon terminal portion is represented by the formula --D(C_x F_2x O)_z C_y F_2y+1, where x is independently an integer of 1 to about 12 for each C_x F_2x O group, y is an integer of 1 to about 12, z is an integer of 2 to about 10, and D is selected from the group consisting of a covalent bond, ##STR48## --O--C_r H_2r --, --O--C_s H_2s O--_t C_r'"'"' H_2r'"'"' --, --C_r H_2r --, --C_s H_2s O--_t C_r'"'"' H_2r'"'"' --, --OSO₂ --, --SO₂ --, --SO₂ --C_r H_2r --, ##STR49## --C.tbd.C--, --CH═

CH--, ##STR50## --CH═

N--, --O--, --S--, --N(C_p H_2p+1)--, and combinations thereof, where r and r'"'"' are independently integers of 0 to about 20, s is independently an integer of 1 to about 10 for each (C_s H_2s O), t is an integer of 1 to about 6, and p is an integer of 0 to about 4.

10. The process of claim 8 wherein said compound is represented by the general formula I:

##STR51## where M, N, and P are each independently selected from the group consisting of ##STR52## a, b, and c are each independently zero or an integer of from 1 to 3, with the proviso that the sum of a+b+c be at least 1;

each A and B are non-directionally and independently selected from the group consisting of a covalent bond, ##STR53## --(CH₂ CH₂)_k -- where k is 1 to 4, --CH═

CH--, --C.tbd.C--, --CH═

N--, --CH₂ --O--, ##STR54## and --O--;

each X, Y, and Z are independently selected from the group consisting of --H, --Cl, --F, --Br, --I, --OH, --OCH₃, --CH₃, --CF₃, --OCF₃ --CN, and --NO₂ ;

each l, m, and n are independently zero or an integer of 1 to 4;

D is selected from the group consisting of a covalent bond, ##STR55## --O--C_r H_2r --, ##STR56## --C.tbd.C--, --CH═

CH--, ##STR57## --O--C_s H_2s O--_t C_r'"'"' H_2r'"'"' --, --C_r H_2r --, --C_s H_2s O--_t C_r'"'"' H_2r'"'"' --, --O--, --S--, --OSO₂ --, --SO₂ --, --SO₂ --C_r H_2r --, ##STR58## --N(C_p H_2p+1)--, ##STR59## --CH═

N--, and combinations thereof, where r and r'"'"' are independently integers of 0 to about 20, s is independently an integer of 1 to about 10 for each (C_s H_2s O), t is an integer of 1 to about 6, and p is an integer of 0 to about 4;

R is selected from the group consisting of --O--((C_q'"'"' H_{2q'"'"'-v'"'"'} --(R'"'"')_v'"'"')--O)_w --C_q H_2q+1-v --(R'"'"')_v, --((C_q'"'"' H_{2q'"'"'v'"'"'} --(R'"'"')_v'"'"')--O)_w --C_q H_2q+1-v --(R'"'"')_v, ##STR60## and --CR'"'"'H--(D)_g'"'"' --CR'"'"'H--, where each R'"'"' is independently selected from the group consisting of --Cl, --F, --CF₃, --NO₂, --CN, --H , --C_q H_2q+1, ##STR61## where q'"'"' is independently an integer of 1 to about 20 for each (C_q'"'"' H_2q'"'"' --O--), q is an integer of 1 to about 20, w is an integer of 0 to about 10, v is an integer of 0 to about 6, each v'"'"' is independently an integer of 0 to about 6, g is an integer of 1 to about 3, g'"'"' is an integer of 1 to about 3, each D is independently selected from the group set forth above, and R is linear or branched and chiral or achiral; and

R_f is --(C_x F_2x O)_z C_y F_2y+1, where x is independently an integer of 1 to about 12 for each (C_x F_2x O), y is an integer of 1 to about 12, and z is an integer of 2 to about 10.

11. The process of claim 10 wherein said compound is represented by the formula:

##STR62## where x is independently an integer of 1 to about 8 for each C_x F_2x O;

y is an integer of 1 to about 8;

z is an integer of 2 to about 4;

j is an integer of 0 or 1;

j'"'"' is an integer of 0 or 1; and

R" is selected from the group consisting of (R'"'"')_v --C_q H_2q+1-v and ##STR63## where each q is independently an integer of 2 to about 10;

each R'"'"' is independently selected from the group consisting of hydrogen, fluorine, chlorine, methyl, and perfluoromethyl;

v is an integer of 0 to about 4; and

C_q H_2q and C_q H_2q+1 are linear or branched.

12. The process of claim 6 wherein said compound has at least one fluoroaliphatic terminal portion.

13. The process of claim 12 wherein said compound is 5-hexyl-2-(4'"'"'-1,1-dihydroperfluorooctyloxy)phenylpyrimidine.

14. The process of claim 1 wherein said composition having a net positive thermal layer expansion comprises at least one chiral or achiral liquid crystal compound having terminal portions independently selected from the group consisting of aliphatic terminal portions, fluoroaliphatic terminal portions, and fluoroether terminal portions containing one catenary ether oxygen atom.

15. The process of claim 8 wherein said compound is the major component of said composition having a net negative thermal layer expansion, and wherein said composition having a net positive thermal layer expansion comprises as the major component at least one chiral or achiral liquid crystal compound having a terminal portion selected from the group consisting of fluoroaliphatic terminal portions and fluoroether terminal portions containing one catenary ether oxygen atom.

16. The process of claim 15 wherein said terminal portion is a fluoroether terminal portion containing one catenary ether oxygen atom.

18. A mixture of liquid crystal compounds prepared by the process of claim 1.

22. A liquid crystal display device containing the mixture of claim 18.

25. The process of claim 1 wherein said smectic mesophase is the smectic C mesophase.

3. A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.05 Å

/°

C.

4. The process of claim 3 wherein said range is from about -0.01 to about +0.01 Å

/°

C.

5. The process of claim 4 wherein said range is from about -0.005 to about +0.005 Å

/°

C.

17. A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion of known magnitude in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion of known magnitude in at least one tilted or latent tilted smectic mesophase, said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, and said compositions being utilized in amounts based upon said magnitudes such that the resulting combination has a desired net thermal layer expansion in at least one tilted smectic mesophase.

19. A mixture of liquid crystal compounds comprising a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is present in an amount such that said mixture has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.05 Å

/°

C.

20. The mixture of claim 19 wherein said range is from about -0.01 to about +0.01 Å

/°

C.

21. The mixture of claim 20 wherein said range is from about -0.005 to about +0.005 Å

/°

C.

23. A liquid crystal display device containing the mixture of claim 19.

24. A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in the smectic C mesophase, said composition comprising at least one chiral or achiral, smectic or latent smectic liquid crystal compound having a fluoroether terminal portion containing at least two catenary ether oxygen atoms;

and a liquid crystal composition having a net positive thermal layer expansion in the smectic C mesophase, said composition comprising at least one chiral or achiral, smectic or latent smectic liquid crystal compound having a terminal portion selected from the group consisting of fluoroaliphatic terminal portions and fluoroether terminal portions containing one catenary ether oxygen atom;

wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has a net thermal layer expansion in the smectic C mesophase within the range of from about -0.05 to about +0.05 Å

/°

C.

26. A process for controlling layer spacing comprising the step of combining at least two liquid crystal compositions having net thermal layer expansions of the same sign and known magnitudes in at least one tilted or latent tilted smectic mesophase, said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, and said compositions being utilized in amounts based upon said magnitudes such that the resulting mixture of liquid crystal compounds has a desired net thermal layer expansion in at least one tilted smectic mesophase.

27. The process of claim 26 wherein said desired net thermal layer expansion is within the range of from about -0.05 to about +0.05 Å

/°

C.

28. The process of claim 26 wherein said smectic mesophase is the smectic C mesophase.

29. A mixture of liquid crystal compounds prepared by the process of claim 26.

31. A liquid crystal display device containing the mixture of claim 29.

30. A mixture of liquid crystal compounds comprising at least two liquid crystal compositions having net thermal layer expansions of the same sign in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein each of said compositions is present in an amount such that said mixture has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.025 Å

/°

C.

32. A liquid crystal display device containing the mixture of claim 30.

33. A process for estimating the net thermal layer expansion of a latent smectic liquid crystal composition in at least one latent tilted smectic mesophase comprising the steps of (a) preparing at least one mixture of a latent smectic liquid crystal composition and a smectic liquid crystal composition, said latent smectic liquid crystal composition comprising at least one latent smectic liquid crystal compound and said smectic liquid crystal composition comprising at least one smectic liquid crystal compound;

(b) determining the net thermal layer expansion of said mixture in at least one selected tilted smectic mesophase;

(c) determining the net thermal layer expansion of said smectic liquid crystal composition in at least one corresponding tilted smectic mesophase; and

(d) extrapolating to a composition of 100 percent said latent smectic liquid crystal composition to obtain an approximate value of the net thermal layer expansion for said latent smectic liquid crystal composition in at least one corresponding latent tilted smectic mesophase.

34. The process of claim 33 wherein said smectic mesophase is the smectic C mesophase.

35. A liquid crystal display device containing a mixture of liquid crystal compounds comprising a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is present in an amount such that said mixture has an essentially temperature-independent layer spacing in at least one tilted smectic mesophase.

36. The device of claim 35 wherein said composition having a net negative thermal layer expansion comprises at least one chiral or achiral liquid crystal compound having at least one fluorinated terminal portion.

37. The device of claim 35 wherein said smectic mesophase is the smectic C mesophase.