Cholesteric liquid crystal water base ink and laminates formed therefrom

• US 4,022,706 A
• Filed: 10/31/1974
• Issued: 05/10/1977
• Est. Priority Date: 12/17/1973
• Status: Expired due to Term

• Current Assignee: E-Z-EM Incorporated (Bracco SPA)
• Original Assignee: Robert Parker Research Incorporated
• Inventors: Davis, Frederick
• Primary Examiner(s): Padgett, Benjamin R.
• Assistant Examiner(s): Gron, T. S.
• Application Number:
  US05/519,480
• Time in Patent Office: 922 Days
• Field of Search: 252/299, 252/408, 23/230 LC, 73/356, 428/1
• US Class Current: 428/1.6
• CPC Class Codes: B29C 51/14 using multilayered preforms or sheets
• CPC Class Codes: C09D 11/00 Inks
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: C09K 2323/06 Substrate layer characterised by chemical composition
• CPC Class Codes: G01K 11/165 of organic liquid crystals
• CPC Class Codes: G03C 1/73 containing organic compounds

Abstract

Thin stable, substantially uniform, liquid crystal containing films are provided by coating a liquid crystal containing ink onto an inert substrate, which may be transparent, or opaque, optionally pigmented, particularly black pigment. The liquid crystal ink comprises an oil in water latex, where the latex contains a film forming polymer, a minor amount of an organic solvent for the liquid crystals, particularly a moderately water soluble organic solvent, which may be an individual solvent or a combination of solvents, the liquid crystals, and normally a thickening agent. The liquid crystal ink may be coated onto a wide variety of substrates and may then be coated with a protective coating or a dark backing. The laminated products can be used as ornamental articles of manufacture, for photographic reproduction, for temperature determination, and the like. The films are employed as substrates and/or protective coatings, and can be dimensionally stable films, vacuum forming films, mold forming films, and the like.

Claims

1. A composition useful in the formation of liquid crystal films which comprises:

a thick oil in water emulsion having from 30 to 80 weight percent solids of which 25-80 weight percent is a cholesteric liquid crystal composition and 75-20 weight percent respectively is a transparent latex forming polymer;

from 20-70 weight percent liquid having water in from 40-75 weight percent and a moderately water soluble oxygenated organic solvent having a boiling point less than about 175°

C for said liquid crystal composition in from 25-60 weight percent; and

a small but sufficient amount of a thickening agent to provide the desired viscosity for film forming.

2. A composition according to claim 1, wherein said solids content is in the range of 35-60 weight percent, said liquid crystal composition is present in from 40-75 weight percent of said solids content, said polymer is present in from 25-60 weight percent respectively;

said liquid content is present in from 40-65 weight percent, with water present in from 45-75 weight percent and organic solvent present in from 25-55 weight percent of said liquid content; and

said thickener is present in from 0.1 to 2 weight percent and including from 0.1 to 2 weight percent of a wetting agent.

3. A composition according to claim 2, wherein said polymer is an acrylic polymer, said solvent is an oxygenated solvent of from 3 to 6 carbon atoms, and said wetting agent is a nonionic emulsifier.

4. A composition according to claim 2, wherein said polymer is a chlorovinyl polymer, said solvent is an oxygenated solvent of from 3 to 6 carbon atoms, and said wetting agent is a nonionic emulsifier.

5. A composition according to claim 2, wherein said solvent is methyl ethyl ketone.

6. A composition according to claim 2, wherein said solvent is a mixture of methyl ethyl ketone and at least one of amyl acetate isobutyl ketone.

10. A film of at least about 0.5 mil thickness prepared from a composition according to claim 1.

11. A film of at least about 0.5 mil thickness prepared from a composition according to claim 3.

12. A film of at least about 0.5 mil thickness prepared from a composition according to claim 4.

13. A laminate comprising a thin transparent film, having as one layer a film of at least about 0.5 mil thickness prepared from a composition according to claim 1 and as a second layer a black pigmented film backing.

14. A laminate according to claim 13, wherein said laminate is vacuum formable.

15. A laminate according to claim 13, wherein said laminate is blow moldable.

16. A laminate according to claim 13, wherein said laminate is elastomeric.

17. A laminate according to claim 13, including a heat-conducting film backing.

18. A laminate according to claim 13, wherein said liquid crystal composition is present in from 40-65 weight percent of said solids content.

7. A liquid crystal composition for forming films of liquid crystals, which is a thick oil in water emulsion comprising:

35-60 weight percent solids of which 50-75 weight percent is a liquid crystal composition and 25-50 wright percent is a transparent acrylic film-forming polymer;

40-65 weight percent liquid of which 50-70 weight percent is an organic solvent of at least 50 volume percent methyl ethyl ketone and 30-50 weight percent is water; and

0.5 to 1.5 weight percent of the total composition of a carboxyvinyl polymeric thickening agent.

8. A composition according to claim 7, having from 0.2 to 4 weight percent of the total composition of a nonionic emulsifier.

9. A method for forming a film-forming liquid crystal composition containing emulsion which comprises:

forming a mixture of a latex of a transparent film-forming polymer having from about 30-95 weight percent water, a solution of a liquid crystal composition in a moderately water soluble oxygenated organic solvent having a boiling point below about 175°

C, and from about 0.1-2 weight percent of the total composition of a thickening agent, said liquid crystal composition being present in an amount to provide 25-80 weight percent of the total solids content, wherein said solution is at a temperature in the range of about 40°

-100°

C; and

stirring the resulting mixture for a time sufficient to provide a substantially uniform composition.