Compound for use in colour change compositions

Abstract

Novel reaction media for electron donating and electron accepting components in colour-change compositions are described. The compound is of formula (VI); R.sub.1, and R.sub.2 are independently selected from an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group and an alkylene aryl group having from 5 to 22 carbon atoms; X.sub.1 and X.sub.2 are independently selected from —OC(O)—, —CO.sub.2— and O; Y.sub.1, and Y.sub.2 are independently selected from hydrogen, halogen, R.sub.1, —OR.sub.1; y is independently 0 or 1; and suitably the groups R.sub.1X.sub.1— and —X.sub.2R.sub.2 are independently in the ortho or meta position. The compounds are useful in ink compositions, writing implements containing the compound and medical and industrial applications in which temperature sensitive colour change may be required. ##STR00001##

Claims

1. A compound of formula: ##STR00010## wherein R.sub.1, and R.sub.2 are independently selected from an optionally substituted linear alkyl group, alkenyl group, and an alkylene aryl group having from 12 to 22 carbon atoms and an aryl group; X.sub.1 and X.sub.2 are independently selected from —OC(O)— and —CO.sub.2—; Y.sub.1, and Y.sub.2 are independently selected from hydrogen, halogen, R.sub.3, and —OR.sub.3 wherein R.sub.3 is selected from hydrogen and linear or branched hydrocarbyl group; y is independently 0 or 1; and the groups R.sub.1X.sub.1— and —X.sub.2R.sub.2 are independently in the ortho or meta position provided that: i) where y is 0, Y.sub.2 is independently selected from hydrogen, halogen, R.sub.3, and —OR.sub.3 wherein R.sub.3 is a linear or branched hydrocarbyl group; and ii) where y is 1, Y.sub.1 or Y.sub.2 is selected from R.sub.3, and —OR.sub.3 wherein R.sub.3 is selected from hydrogen and a linear or branched hydrocarbyl group.

2. A compound according to claim 1 wherein y is 1.

3. A compound according to claim 1 wherein R.sub.1, and R.sub.2 are independently selected from C.sub.12-22 alkyl and phenyl.

4. A compound according to claim 1 wherein R.sub.1, and R.sub.2 are independently selected from C.sub.12 to C.sub.17 alkyl and phenyl.

5. A compound according to claim 1 wherein Y.sub.1 and Y.sub.2 are independently selected from hydrogen, halogen and C.sub.1-4 alkyl.

6. A compound according to claim 1 wherein Y.sub.1 and Y.sub.2 are all hydrogen, R.sub.1 and R.sub.2 are independently selected from C.sub.12 to C.sub.22 alkyl and X.sub.1 and X.sub.2 are —OCO—.

7. A compound according to claim 1 selected from compound of formula Via: ##STR00011## and compound of formula VIb: ##STR00012## wherein R.sub.1 and R.sub.2, are independently selected from phenyl, C.sub.12-22 alkyl and alkylene aryl of formula —[CH.sub.2].sub.z Ar where z is from 1 to 6 and Ar is optionally substituted phenyl.

8. A method of making a colour-change composition, said method comprising utilizing a compound of formula (VI): ##STR00013## wherein R.sub.1, and R.sub.2 are independently selected from an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group and an alkylene aryl group having from 5 to 22 carbon atoms; X.sub.1 and X.sub.2 are independently selected from —OC(O)—, —CO.sub.2— and O; Y.sub.1, and Y.sub.2 are independently selected from hydrogen, halogen, R.sub.3, and —OR.sub.3 wherein R.sub.3 is selected from hydrogen and an optionally substituted linear or branched hydrocarbyl group; y is independently 0 or 1; and the groups R.sub.1X.sub.1— and —X.sub.2R.sub.2 are independently in the ortho or meta position.

9. A colour-change composition comprising: A) an electron donating organic colouring compound, B) an electron accepting compound and C) a compound of formula (VI): ##STR00014## wherein R.sub.1, and R.sub.2 are independently selected from an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group and an alkylene aryl group having from 5 to 22 carbon atoms; X.sub.1 and X.sub.2 are independently selected from —OC(O)—, —CO.sub.2— and O; Y.sub.1, and Y.sub.2 are independently selected from hydrogen, halogen, R.sub.3, and —OR.sub.3 wherein R.sub.3 is selected from hydrogen and an optionally substituted linear or branched hydrocarbyl group; y is independently 0 or 1; and the groups R.sub.1X.sub.1— and —X.sub.2R.sub.2 are independently in the ortho or meta position.

10. A colour-change composition according to claim 9 wherein compound A) is selected from the group consisting of 3-(4-diethylamino-2-hexyloxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3,3-bis(1-n-butyl-2-methylindol-3-yl)phthalide, 6′-(diethylamino)-2′-(phenylamino)-3H-spiro[2-benzofuran-1,9′-xanthen]-3-one, 2′-chloro-6′-diethylaminofluoran and 2-(2-chloroanilino)-6-di-n-butylaminofluoran.

11. A colour-change composition according to claim 9 wherein compound B) is selected from the group consisting of 2,2-bis(4′-hydroxyphenyl)hexafluoropropane, 4,4′-Cyclohexylidenebisphenol, 1,1-bis(4′-hydroxyphenyl)-2-methylpropane and mixtures thereof.

12. A colour-change composition according to claim 9 which has a hysteresis range from 10 to 80° C.

13. A colour-change composition according to claim 9 which has a fully coloured temperature T4 higher than ambient temperature and a fully decolorized temperature T1 lower than 20° C.

14. A colour-change composition according to claim 9 further comprising a non-ionic surfactant.

15. A colour-change microencapsulated pigment comprising a microencapsulated composition according to claim 9.

16. An ink composition for a writing implement which comprises a colour-change microencapsulated pigment according to claim 15.

17. A writing implement comprising a writing device and an ink composition according to the claim 16.

18. A colour-change composition or a colour-change microencapsulated pigment according to claim 9 wherein component C) is such that said composition or pigment has a T2 temperature at 0° C. and a T3 temperature above 50° C.

19. An indicator including the colour change composition according to claim 9, wherein said composition further comprises a first portion in its coloured state and a second portion in its discolored state.

20. A process for producing an indicator according to claim 19 comprising providing a support with a first portion of the colour-change composition, having colour change temperatures T1 comprising a fully colored temperature, T2 comprising a minimum discolored state retaining temperature, T3 comprising a maximum color-retaining temperature and T4 comprising a fully decolorized temperature, heating the first portion of the colour-change composition, pigment or ink to a temperature exceeding T4, cooling a second portion of the colour-change composition, pigment or ink composition to a temperature below T1, applying the said second portion to the support and drying the colour-change composition, pigment or ink composition at temperature not exceeding temperature T3 and not below temperature T2.

Description

(1) In the accompanying illustrative drawings:

(2) FIG. 1 shows a typical plot of changes in colour density against temperature for thermochromic compositions;

(3) FIGS. 2a to 2c show a temperature freezing indicator label according to the invention based on a memory composition according to the invention;

(4) FIGS. 3a to 3c show examples of a temperature indicator label according to the invention based on a memory composition containing Kromagen ink according to the invention.

(5) By way of illustration, in the initial state at ambient temperature above T2 and below T3 is represented in FIG. 2a. As the temperature drops below the temperature T2, and is kept below T4 at all times, the state of the indicator changes to that shown in FIG. 2b. By raising the temperature to greater than T3 the indicator provides two colourless compositions as shown in FIG. 2c).

(6) The indicator may also be configured so it may not be reset and provides a single use indicator.

(7) The invention provides for a single use indicator comprising a first portion of a colour-change composition in its coloured state and a second portion of the same colour-change composition in its discoloured state wherein the composition is according to the present invention.

(8) Suitably, the indicator has a thermochromic composition or pigment according to the invention suitably in the form of a printable ink applied to it and heated to a temperature exceeding T4 prior to application to the indicator, for example in a printing process. An ink showing permanent colour change at a desired temperature, for example 50° C. is applied to the indicator, for example printed next to the memory composition pigment converted into printed ink. Any known permanent colour change ink may be employed and a preferred example is available from TMC Hallcrest, under the brand name Kromagen. The printed label is allowed to dry at temperature not exceeding T3 or 50° C. and preferably not below T.sub.2. The combination on the label is now suitable for indication of temperature below zero, of what can be cold a “freeze indicator”. The indicator used a single time.

(9) By way of illustration, FIGS. 3a, 3b and 3c illustrate the various forms of the indicator where the indicator comprises a composition according to the invention comprising Kromagen ink. FIG. 3a shows the initial state at ambient temperature above T2 and below the temperature of colour transition of Kromagen. FIG. 3b shows the indicator as the temperature drops below T2 and below the temperature at which Kromagen changes colour and FIG. 3c shows the indicator as it appears after heating above T4.

(10) The invention is now illustrated by the following non-limiting examples in which parts are by weight unless otherwise stated.

EXAMPLE 1

(11) A thermochromic colour memory composition was obtained by homogeneously compatibilizing:

(12) 4 parts of 3-(4-diethylamino-2-hexyloxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide (electron donating compound) available from Yamada Chemicals and 6 parts 2,2-bis(4′-hydroxyphenyl)hexafluoropropane and 6 parts of 1,1-bis(4′-hydroxyphenyl)-2-methylpropane (both electron accepting compounds) available from Sigma Aldrich and 84 parts of compound (VIa1) 2,2′ biphenyl bistetradecanoate ester as shown below:

(13) ##STR00007##

(14) Component VIa1 is suitably synthesised by stirring a mixture of 1 mole of 2,2′-Dihydroxybiphenyl, which is available from Sigma Aldrich or may be prepared using the method described by B. Schmidt, M. Riemer, and M. Karras (J. Org. Chem., 2013, 78 (17), pp 8680-8688), and 2.5 moles of triethyl amine in acetone and cooling to 5° C. 2.2 moles of acid chloride is added gradually so that temperature does not rise above 35° C. during the addition. After the addition is complete the reaction is brought to room temperature and stirred for 24-48 hours. The resulting reaction medium is then poured into 7% aqueous ice cold HCI. The precipitate is filtered off and washed with water and saturated sodium bicarbonate solution. The solid precipitate is crystallised from isopropanol. The relative quantities of biphenol/acid chloride/triethylamine are 1/2.2/2.5 moles.

(15) The resulting memory composition changed colour form blue to colourless. The thermochromic colour memory composition was heated above T4. 100 parts of the hot thermochromic colour memory composition was then dispersed into 100 parts of a 10% solution of methyl vinyl ether-maleic anhydride copolymerized resin neutralised with sodium hydroxide to pH 4 by means of a high speed homogeniser. The resulting emulsion was maintained at temperature above T4 and slowly added 25 parts of a solution of melamine formaldehyde resin. The resulting emulsion was stirred and heated to a temperature of 80° C. for 6 hours. Some of the resulting dispersion was then drum dried and the pigment was isolated in encapsulated form, the thermochromic colour memory pigment having a particle size of 1.5 microns changed colour from blue to colourless.

EXAMPLE 2

(16) 4.1 parts of 3-(4-diethylamino-2-hexyloxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide (electron donating compound) available from Yamada Chemicals and 4.85 parts 2,2-bis(4′-hydroxyphenyl)hexafluoropropane and 4.85 parts of 1,1-bis(4′-hydroxyphenyl)-2-methylpropane (both electron accepting compounds) available from Sigma Aldrich and 86.2 parts of compound (VIa2) 2,2′ biphenyl bisoctadecanoate ester as shown below:

(17) ##STR00008##

(18) Component VIa2 is suitably synthesised by stirring a mixture of 1 mole of 2,2′-Dihydroxybiphenyl, which is available from Sigma Aldrich or may be prepared using the method described by B. Schmidt, M. Riemer, and M. Karras (J. Org. Chem., 2013, 78 (17), pp 8680-8688), and 2.5 moles of triethyl amine in acetone and cooling to 5° C. 2.2 moles of octadecanoyl chloride is added gradually so that temperature does not rise above 35° C. during the addition. After the addition is complete the reaction is brought to room temperature and stirred for 24-48 hours. The resulting reaction medium is then poured into 7% aqueous ice cold HCI. The precipitate is filtered off and washed with water and saturated sodium bicarbonate solution. The solid precipitate is crystallised from isopropanol. The relative quantities of biphenol/acid chloride/triethylamine are 1/2.2/2.5 moles.

(19) The resulting memory composition changed colour form blue to colourless. The thermochromic colour memory composition was heated above 100° C. 100 parts of the hot thermochromic colour memory composition was then dispersed into 100 parts of a 10% solution of methyl vinyl ether-maleic anhydride copolymerized resin neutralised with sodium hydroxide to pH 4 by means of a high speed homogeniser. The resulting emulsion was maintained at temperature above 80° C. and slowly added 25 parts of a solution of melamine formaldehyde resin. The resulting emulsion was stirred and heated to a temperature of 80° C. for 6 hours. Some of the resulting dispersion was then drum dried and the pigment was isolated in encapsulated form, the thermochromic colour memory pigment having a particle size of 2.1 microns changed colour from blue to colourless.

EXAMPLE 3

(20) 4.1 parts of 3-(4-diethylamino-2-hexyloxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide (electron donating compound) available from Yamada Chemicals and 4.85 parts 2,2-bis(4′-hydroxyphenyl)hexafluoropropane and 4.85 parts of 1,1-bis(4′-hydroxyphenyl)-2-methylpropane (both electron accepting compounds) available from Sigma Aldrich and 86.2 parts of compound (VIa3) 2,2′ biphenyl bishexadecanoate ester as shown below:

(21) ##STR00009##

(22) Component VIa3 is suitably synthesised by stirring a mixture of 1 mole of 2,2′-Dihydroxybiphenyl, which is available from Sigma Aldrich or may be prepared using the method described by B. Schmidt, M. Riemer, and M. Karras (J. Org. Chem., 2013, 78 (17), pp 8680-8688), and 2.5 moles of triethyl amine in acetone and cooling to 5° C. 2.2 moles of hexadecanoyl chloride is added gradually so that temperature does not rise above 35° C. during the addition. After the addition is complete the reaction is brought to room temperature and stirred for 24-48 hours. The resulting reaction medium is then poured into 7% aqueous ice cold HCI. The precipitate is filtered off and washed with water and saturated sodium bicarbonate solution. The solid precipitate is crystallised from isopropanol. The relative quantities of biphenol/acid chloride/triethylamine are 1/2.2/2.5 moles.

(23) The resulting memory composition changed colour form blue to colourless. The thermochromic colour memory composition was heated above 100° C. 100 parts of the hot thermochromic colour memory composition was then dispersed into 100 parts of a 10% solution of methyl vinyl ether-maleic anhydride copolymerized resin neutralised with sodium hydroxide to pH 4 by means of a high speed homogeniser. The resulting emulsion was maintained at temperature above 80° C. and slowly added 25 parts of a solution of melamine formaldehyde resin. The resulting emulsion was stirred and heated to a temperature of 80° C. for 6 hours. Some of the resulting dispersion was then drum dried and the pigment was isolated in encapsulated form, the thermochromic colour memory pigment having a particle size of 2.5 microns changed colour from blue to colourless.

(24) Preparation of the Measuring Samples

(25) 10 parts of the thermochromic colour memory composition of the water dispersion obtained in Example 1 in encapsulated form were dispersed in 10 parts of a polyvinyl alcohol solution was screen printed onto sheet of copy paper, thereby obtaining a test sample.

(26) The same method has been carried out in order to obtain a test sample for the thermochromic colour memory composition of Examples 2 to 13 in encapsulated form. Each of the test samples was heated and cooled by the below described method, The measuring sample thus prepared was set on a predetermined position of a Linkam (manufactured by linkam, UK) and the colour density at each temperature was measured by heating and cooling at a rate of 5° C./min with a temperature width of 100° C.

(27) For example, in the case of Example 1, the sample was heated up to 100° C. at a rate of 5° C./min from a measurement starting temperature of 0° C., and then cooled to −20° C. at a rate of 5° C./min. The brightness of the colour displayed at each temperature was plotted on a graph to prepare the colour density-temperature curve as illustrated in FIG. 1, and each of T.sub.1, T2, T3, T.sub.4, and ΔH was obtained.

(28) The results of the temperature analysis in ° C. of the microcapsules is reported below as per their temperature of full clearing (T4) and temperature of full colour return (T1) as well as practical hysteresis ΔH. The results are reported below for the Components C) with different R.sub.1 groups as shown in the formula below.

(29) TABLE-US-00001 Examples T1 T2 T3 T4 ΔH Example 1 −23 −20 34 38 54 Example 2 15 25 55 65 30 Example 3 +2 +8 40 52 32