# US 5,705,093 A · Thermochromic media

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,705,093 A
- Document ID: US5705093A
- Status: Granted
- Kind: A
- Application number: 08/286,181
- Filed: 1994-08-05
- Granted: 1998-01-06
- Earliest claimed: 1993-08-06
- Assignees: Merck Patent GmbH
- Inventors: David Coates; Alison Linda May; Jacqueline Dawn Percy
- Web page: https://patentgrep.com/patent/US5705093A

## CPC

- C09D 11/50: Sympathetic, colour changing or similar inks
- C09K 19/3068: {chain containing -COO- or -OCO- groups}
- C09K 19/46: containing esters
- C09K 2019/3095: {in which the end group is the monoterpene menthyl}
- C09K 2323/06: Substrate layer characterised by chemical composition
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

An improved ink comprising a thermochromic liquid crystalline media comprising at least one optically inactive nematic component and at least one optically active component, the improvement wherein the optically active component comprises at least one menthol derivative of formula I ##STR1## wherein ##STR2## is 1,4-phenylene optionally substituted by up to 4 methyl group and/or halogen atoms, particularly fluorine atoms or is 1,4 cyclohexylene and MG is a mesogenic group, or forms a mesogenic group together with ##STR3##

## Claims

### Claim 1

An improved thermochromic liquid crystalline medium comprising at least one optically inactive nematic component and at least one optically active component, wherein the optically active component comprises at least one compound of formula I having one menthyl group ##STR45## wherein ##STR46## is 1,4-phenylene optionally substituted by 1 to 4 methyl groups, halogen atoms or a combination thereof, or 1,4-cyclohexylene and
MG is a group of formula II
R.sup.1 --(A.sup.1 --Z.sup.1).sub.m --A.sup.2 --Z.sup.2 -- (II)
wherein
R.sup.1 is hydrogen or a straight-chained or branched alkyl or alkenyl group of 1 to 16 C atoms, wherein one or two nonadjacent CH.sub.2 groups are optionally replaced by --O--, --S--, --CO--O-- or --O--CO--, independently,
A.sup.1 and A.sup.2 each independently denote:
(a) 1,4-phenylene optionally substituted by 1 to 4 fluorine atoms, in which one or two CH groups may be replaced by N,
(b) 1,4-cyclohexylene optionally substituted by --CN or --CH.sub.3, in which one or two CH.sub.2 groups may be replaced by O,
(c) naphthalin-2,5-diyl or piperidin-1,4-diyl,
Z.sup.1 and Z.sup.2 are each independently --CO--O--, --O--CO--, --CH.sub.2 O--, --OCH.sub.2 --, --N.dbd.CH--, --CH.dbd.N--, --CH.sub.2 CH.sub.2 --, --C--C.tbd. or a single bond and
m is 0, 1 or 2
and wherein the optically inactive nematic component comprises at least one compound selected from the formula III to VII ##STR47## wherein R.sup.2 and R.sup.3 each independently is hydrogen or a straight-chained or branched alkyl or alkenyl group of 1-16 C atoms, wherein one or two non-adjacent CH.sub.2 groups are optionally replaced by --O--, --S--, --CO--O-- or --O--CO--, independently,
R.sup.4 has one of the meanings given for R.sup.2 and R.sup.3 or is halogen or cyano, ##STR48## each independently denote 1,4-phenylene or 1,4-cyclohexylene, n is 1 or 2, and
o, p, q are each independently 0, 1 or 2.

### Claim 2 (depends on 1)

A medium according to claim 1, which is micro-encapsulated.

### Claim 3 (depends on 1)

An electro-optic device containing a liquid crystalline medium according to claim 1.

### Claim 4 (depends on 1)

A temperature indicating device containing a liquid crystalline medium according to claim 1.

### Claim 5 (depends on 1)

A method of surface thermography which includes the step of
(a) applying a thin film of a liquid crystalline medium according to claim 1 to a surface, and
(b) observing the color of the film in reflection at an angle of 90.degree. to the surface.

### Claim 6 (depends on 1)

A decorative coating or cosmetic containing a medium according to claim 1.

### Claim 7 (depends on 1)

The liquid crystalline medium of claim 1, wherein the compound of formula I is a compound of one of the following formulae I1 to I14:
______________________________________ R.sup.1 --Phe--Phe--COO-Ment I1 R.sup.1 --Cyc--Phe--COO-Ment I2 R.sup.1 --Cyc--Cyc--COO-Ment I3 R.sup.1 --Phe--Phe--Z.sup.2 --Phe--COO-Ment I4 R.sup.1 --Cyc--Phe--Z.sup.2 --Phe--COO-Ment I5 R.sup.1 --Phe--Phe--Phe--COO-Ment I6 R.sup.1 --Cyc--Phe--Phe--COO-Ment I7 R.sup.1 --Cyc--Cyc--Phe--COO-Ment I8 R.sup.1 --PhePheX--COO-Ment I9 R.sup.1 --CycPheX--COO-Ment I10 R.sup.1 --PhePhe--Z.sup.2 --PheX--COO-Ment I11 R.sup.1 --PheXPhe--Z.sup.2 --Phe--COO-Ment I12 R.sup.1 --PhePhePheX--COO-Ment I13 R.sup.1 --PhePheXPhe--COO-Ment I14 ______________________________________
wherein Ment denotes a group of the formula ##STR49## Phe denotes an unsubstituted 1,4-phenylene group, PheX denotes a 1,4-phenylene group substituted by up to four methyl groups, halogen atoms or a combination thereof, Cyc denotes 1,4-cyclohexylene and R.sup.1 and Z.sup.2 are as defined.

### Claim 8 (depends on 7)

The liquid crystalline medium of claim 7, wherein the compound of formula I is of one of the formulae I9 to I14 and contains a PheX group which is 1,4-phenylene substituted by one or two halogen groups.

### Claim 9 (depends on 1)

The liquid crystalline medium of claim 1, wherein R.sup.1 is H or C.sub.1-6 -alkoxy.

### Claim 10 (depends on 1)

The liquid crystalline medium of claim 1, wherein the compound of the formula I has an HTP value of less than 0.5 .mu.m.

### Claim 11 (depends on 1)

The liquid crystalline medium of claim 1 which contains 2 to 80% by weight of one or more compounds of the formula I.

### Claim 12 (depends on 1)

The liquid crystalline medium of claim 1, wherein the optically inactive nematic component comprises a racemic mixture of at least one compound of one of the formulae III to VII having at least one terminal group R.sup.2, R.sup.3 or R.sup.4, which is a chiral alkyl or alkoxy group of 4 to 16 carbon atoms.

### Claim 13

An improved ink composition comprising a thermochromic liquid crystalline medium comprising at least one optically inactive nematic component and at least one optically active component, the improvement wherein the optically active component comprises at least one menthol derivative of formula I ##STR50## wherein ##STR51## is 1,4-phenylene optionally substituted by 1 to 4 methyl groups, halogen atoms, or a combination thereof, or 1,4-cyclohexylene and
MG is a group of formula II
R.sup.1 --(A.sup.1 --Z.sup.1).sub.m --A.sup.2 --Z.sup.2 -- (II)
wherein
R.sup.1 is hydrogen or a straight-chained or branched alkyl or alkenyl group of 1 to 16 C atoms, wherein one or two nonadjacent CH.sub.2 groups are optionally replaced by --O--, --S--, --CO--O-- or --O--CO--, independently,
A.sup.1 and A.sup.2 each independently denote:
(a) 1,4-phenylene optionally substituted by 1 to 4 fluorine atoms, in which one or two CH groups may be replaced by N,
(b) 1,4-cyclohexylene optionally substituted by --CN or --CH.sub.3, in which one or two CH.sub.2 groups may be replaced by O,
(c) naphthalin-2,5-diyl or piperidin-1,4-diyl,
Z.sup.1 and Z.sup.2 are each independently --CO--O--, --O--CO--, --CH.sub.2 O--, --OCH.sub.2 --, --N.dbd.CH--, --CH.dbd.N--, --CH.sub.2 CH.sub.2 --, --C.tbd.C-- or a single bond and
m is 0, 1 or 2.

### Claim 14 (depends on 13)

An improved ink composition according to claim 13, wherein the optically inactive nematic medium comprises at least one compound selected from those of the formulae III to VII ##STR52## wherein R.sup.2 and R.sup.3 each independently is hydrogen or a straight-chained or branched alkyl or alkenyl group of 1-16 C atoms, wherein one or two non-adjacent CH.sub.2 groups are optionally replaced by --O-- --S--, --CO--O-- or --O--CO--, independently,
R.sup.4 has one of the meanings given for R.sup.2 and R.sup.3 or is halogen or cyano, ##STR53## each independently denote 1,4-phenylene or 1,4-cyclohexylene, n is 1 or 2, and
o, p, q are each independently 0, 1 or 2.

### Claim 15 (depends on 13)

An improved composition according to claim 13, wherein said medium comprises 10-30% of at least one compound of formula I.

### Claim 16 (depends on 1)

A substrate coated with a thermochromic ink according to claim 1, wherein said substrate reflects right circular polarized light and absorbs left circular polarized light.

### Claim 17 (depends on 1)

A substrate coated with a thermochromic ink according to claim 1, wherein said substrate reflects left circular polarized light and absorbs right circular polarized light.