ELECTROPHORETIC INK PROVIDING COLOURED AND TRANSPARENT STATES

Abstract

The present invention refers to an electrophoretic ink, a method for preparing an electrophoretic ink, an electrophoretic display comprising the electrophoretic ink, a smart window comprising the electrophoretic ink as well as the use of the electrophoretic ink in electrophoretic displays or smart windows and the use of a mixture of charge control agents for the preparation of an electrophoretic ink.

Claims

1: An electrophoretic ink, comprising, a) at least one carrier fluid, b) pigment particles dispersed in the at least one carrier fluid, and c) a mixture of charge control agents comprising i) at least one polydimethylsiloxane substituted primary amine and/or polydimethylsiloxane substituted secondary amine and/or polydimethylsiloxane substituted tertiary amine, and ii) at least one polydimethylsiloxane substituted quaternary ammonium with counterion.

2: The electrophoretic ink of claim 1, wherein the at least one carrier fluid comprises an aliphatic hydrocarbon, a halogenated alkane, a silicon oil and mixtures thereof.

3: The electrophoretic ink of claim 1, wherein the pigment particles are selected from the group consisting of a color pigment, an effect pigment, an electrically conductive pigment, a magnetically shielding pigment, a fluorescent pigment, an extender pigment, an anticorrosion pigment, an organic pigment, an inorganic pigment and mixtures thereof.

4: The electrophoretic ink of claim 1, further comprising at least one dispersing agent of Formula (I) ##STR00071## wherein p+q is an integer in a range of from 30 to 200, n+m is an integer in a range of from 5 to 50, X.sup. is an anion of a monovalent organic or inorganic acid, R.sub.1 is a C.sub.4-C.sub.22-linear or branched alkyl group and R.sub.2 is a C.sub.1-C.sub.12-comprising group.

5: The electrophoretic ink of claim 1, wherein the mixture of charge control agents comprises the at least one polydimethylsiloxane substituted primary amine and/or polydimethylsiloxane substituted secondary amine and/or polydimethylsiloxane substituted tertiary amine of i) and the at least one polydimethylsiloxane substituted quaternary ammonium with counterion of ii) in a weight ratio ranging from 1:10 to 1:1.5.

6: The electrophoretic ink of claim 1, wherein the at least one polydimethylsiloxane substituted primary amine and/or polydimethylsiloxane substituted secondary amine and/or polydimethylsiloxane substituted tertiary amine of i) is a polydimethylsiloxane substituted tertiary amine.

7: The electrophoretic ink of claim 1, wherein the at least one polydimethylsiloxane substituted primary amine and/or polydimethylsiloxane substituted secondary amine and/or polydimethylsiloxane substituted tertiary amine of i) is a compound of Formula (IIa) ##STR00072## wherein x is an integer in a range of from 5 to 20, and/or a compound of Formula (IIb) ##STR00073## wherein x is an integer in a range of from 5 to 20 and y is an integer in a range of from 0 to 12, and/or a compound of Formula (IIc) ##STR00074## wherein x is an integer in a range of from 5 to 20 and y and z are each independently an integer in a range of from 0 to 12.

8: The electrophoretic ink of claim 1, wherein the at least one polydimethylsiloxane substituted quaternary ammonium with counterion of ii) is a compound of Formula (III) ##STR00075## wherein x is an integer in a range of from 5 to 20; y and z are each independently an integer in a range of from 0 to 12 and X.sup. is selected from the group consisting of iodide, bromide, chloride, methylsulfate anion and ethylsulfate anion.

9: The electrophoretic ink of claim 1, wherein the at least one polydimethylsiloxane substituted quaternary ammonium with counterion of ii) is a compound of Formula (IV) ##STR00076## wherein x is an integer in a range of from 5 to 20; y and z are each independently an integer in a range of from 0 to 12 and X.sup. is selected from the group consisting of iodide, bromide, chloride, methylsulfate anion and ethylsulfate anion.

10: The electrophoretic ink of claim 7, wherein x is the same in Formula (II) and Formula (III) or Formula (IV) and/or y is the same in Formula (II) and Formula (III) or Formula (IV) and/or z is the same in Formula (II) and Formula (III) or Formula (IV).

11: The electrophoretic ink of claim 1, comprising the mixture of charge control agents in an amount of 5 to 40 wt. % based on a total weight of the electrophoretic ink.

12: A method of preparing an electrophoretic ink, the method comprising: a) providing at least one carrier fluid as defined in claim 1, b) providing pigment particles as defined in claim 1, c) optionally providing at least one dispersing agent of Formula (I) ##STR00077## wherein p+q is an integer in a range of from 30 to 200, n+m is an integer in a range of from 5 to 50, X.sup. is an anion of a monovalent organic or inorganic acid, R.sub.1 is a C.sub.4-C.sub.22-linear or branched alkyl group and R.sub.2 is a C.sub.1-C.sub.12-comprising group, d) providing a mixture of charge control agents as defined in claim 1, optionally in a weight ratio [i)/ii)] ranging from 1:10 to 1:1.5, and e) combining the at least one carrier fluid of a), the pigment particles of b), the optional at least one dispersing agent of c) and the mixture of charge control agents of d).

13: An electrophoretic display, comprising: a) a top layer and a bottom layer, wherein at least one of the top layer and the bottom layer is transparent, and b) an array of cells sandwiched between the top layer and the bottom layer, wherein the cells comprise the electrophoretic ink of claim 1.

14: A smart window, comprising a) a top layer and a bottom layer, wherein at least one of the top layer and the bottom layer is transparent, and b) an array of cells sandwiched between the top layer and the bottom layer, wherein the cells comprise the electrophoretic ink of claim 1.

15: An electrophoretic display or smart window, comprising the electrophoretic ink of claim 1.

16. A method of preparing an electrophoretic ink, the method comprising mixing components, wherein at least one of the components is a mixture of charge control agents as defined in claim 1.

Description

BRIEF DESCRIPTION OF FIGURES

[0206] FIG. 1 refers to a schematic illustration of a display cell containing a black or coloured electrophoretic ink.

[0207] FIG. 2 refers to a schematic illustration of a smart window cell containing a black or coloured electrophoretic ink.

[0208] FIG. 3 refers to a schematic illustration of a display or smart window cell viewed from above.

[0209] FIG. 4 refers to a schematic illustration of stacked display cells containing coloured electrophoretic inks.

[0210] FIG. 5 refers to a schematic illustration of stacked smart window cells containing coloured electrophoretic inks.

EXAMPLES

1. Preparation of Charge Control Agents (CCAs)

1.1 Allyldialkylamine

[0211] ##STR00045##

[0212] Compound (1) is commercially available from Sigma-Aldrich. Compound (2) is synthesized as described in 1.1.1. Compounds (3), (4), and (5) are synthesized as described in 1.1.2.

1.1.1 Allyldiethylamine

[0213] ##STR00046##

[0214] 6 g of compound (6) (Fluke) is dissolved in 40 g of deionized water. 10 g of allylbromide (Sigma-Aldrich) is added to the solution. The pH value of the reaction mixture is adjusted to 10.7 by adding 32 mL of NaOH solution (10%). The mixture is stirred for 5.5 hours at 80 C. After cooling to ambient temperature, an organic phase is separated from the reaction mixture and the residual aqueous phase is removed. The obtained organic phase is washed twice with water (Nanopur) and dried in a rotary evaporator at 60 C. in vacuo, leaving 2.1 g of a crude product.

[0215] The crude product is distilled at 80 C. in vacuo, resulting in 1.6 g of allyldiethylamine (compound (2)) according to .sup.1H- or .sup.13C-NMR.

1.1.2 Allyldibutylamine, Allyldihexylamine, and Allyldidecylamine

[0216] ##STR00047##

[0217] 80.0 g of compound (7) and 494.1 g of n-butyl bromide are added to 600 g of deionized water. The pH value of the reaction mixture is adjusted to 10.7 by adding 314.9 g of NaOH solution (30%). The mixture is stirred for 7 hours at 95 C. After cooling to ambient temperature, the mixture is stirred overnight for ca. 16.5 hours. After that, the pH value of the mixture is adjusted to 10.7 by adding 131.7 g of NaOH solution (30%). The mixture is stirred for 7 hours at 99 C. After cooling to ambient temperature, the mixture is stirred overnight for ca. 16 hours. An organic phase is separated from the reaction mixture and washed with deionized water. The organic phase is distilled initially at 75 C. and then at 85 C. in vacuo, resulting in 180.0 g of allyldibutylamine (compound (3)) according to .sup.1H- and .sup.13C-NMR.

##STR00048##

[0218] 58.3 g of compound (7) and 437.9 g of n-hexyl bromide are added to 437 g of deionized water. The pH value of the reaction mixture is adjusted to 10.7 by adding 259.8 g of NaOH solution (30%). The mixture is stirred for 8 hours at 95 C. After cooling to ambient temperature, the mixture is stirred overnight for ca. 16 hours. After that, the pH value of the mixture is adjusted to 10.7 by adding 75.8 g of NaOH solution (30%). The mixture is stirred for 6 hours at 97 C. After cooling to ambient temperature, an organic phase is separated from the reaction mixture and washed with deionized water. The organic phase is distilled initially at 70 C. and then at 120 C. in vacuo, resulting in 169.5 g of allyldihexylamine (compound (4)) according to .sup.1H- and .sup.13C-NMR.

##STR00049##

[0219] 46.6 g of compound (7) and 470.0 g of n-decyl bromide are added to 350 g of deionized water. The pH value of the reaction mixture is adjusted to 10.7 by adding 116.3 g of NaOH solution (30%). The mixture is stirred for 7.5 hours at 95 C. After cooling to ambient temperature, the mixture is stirred overnight for ca. 16 hours. After that, the pH value of the mixture is adjusted to 10.7 by adding 119.7 g of NaOH solution (30%). The mixture is stirred for 6.5 hours at 97 C.

[0220] After cooling to ambient temperature, an organic phase is separated from the reaction mixture and is first washed with deionized water, then with NaCl solution (20%). The organic phase is distilled initially at 70 C. and then at 160 C. in vacuo, resulting in 160.3 g of allyldidecylamine (compound (5)) according to .sup.1H- and .sup.13C-NMR.

1.2 N,N-dialkylamino-propyl-polydimethylsiloxane

[0221] ##STR00050##

[0222] A solution of 0.025 g of hexachloroplatinic acid in 1 mL of tetrahydrofuran is added to 50.0 g of compound (8) (ABCR), a linear poly(dimethylsiloxane) terminated by a butyl group at one end and a hydride at the other end with a viscosity of 5-9 cSt (i.e. n is about 10). The mixture is heated to 90 C. in a reactor with nitrogen as protective gas. 4.35 g of allyldimethylamine (compound (1), Sigma-Aldrich) is added by drop to the mixture under stirring; the process is finished within 30 minutes. The reaction mixture is stirred for 2 hours at 90 C. and then cooled down to 60 C. 1.0 g of active carbon (Norit Azo) is added to the reaction mixture. After stirring for 2 hours, the mixture is filtered through diatomaceous earth (Clarcel DIC), resulting in 50.8 g of compound (9) according to .sup.1H- and .sup.13C-NMR.

##STR00051##

[0223] A solution of 0.008 g of hexachloroplatinic acid in 1 mL of tetrahydrofuran is added to 13.0 g of compound (8) (ABCR), a linear poly(dimethylsiloxane) terminated by a butyl group at one end and a hydride at the other end with a viscosity of 5-9 cSt (i.e. n is about 10). The mixture is heated to 90 C. in a reactor with nitrogen as protective gas. 1.50 g of allyldiethylamine (compound (2)) is added by drop to the mixture under stirring; the process is finished within 30 minutes. The reaction mixture is stirred for 2.5 hours at 90 C. and then cooled down to 60 C. 0.26 g of active carbon (Norit Azo) is added to the reaction mixture. After stirring for 2 hours, the mixture is filtered through diatomaceous earth (Clarcel DIC), resulting in 10.9 g of compound (10) according to .sup.1H- and 13C-NMR.

##STR00052##

[0224] A solution of 0.040 g of hexachloroplatinic acid in 1 mL of tetrahydrofuran is added to 500.0 g of compound (8) (ABCR), a linear poly(dimethylsiloxane) terminated by a butyl group at one end and a hydride at the other end with a viscosity of 5-9 cSt (i.e. n is about 10). The mixture is heated to 90 C. in a reactor with nitrogen as protective gas. 87.30 g of allyldibutylamine (compound (3)) is added by drop to the mixture under stirring; the process is finished within 30 minutes. The reaction mixture is stirred for 1 hour at 90 C. and then cooled down to 60 C. 10.0 g of active carbon (Norit Azo) is added to the reaction mixture. After stirring for 2 hours, the mixture is filtered through diatomaceous earth (Clarcel DIC), resulting in 561.1 g of compound (11) according to .sup.1H- and .sup.13C-NMR.

##STR00053##

[0225] A solution of 0.025 g of hexachloroplatinic acid in 1 mL of tetrahydrofuran is added to 50.0 g of compound (8) (ABCR), a linear poly(dimethylsiloxane) terminated by a butyl group at one end and a hydride at the other end with a viscosity of 5-9 cSt (i.e. n is about 10). The mixture is heated to 90 C. in a reactor with nitrogen as protective gas. 11.50 g of allyldihexylamine (compound (4)) is added by drop to the mixture under stirring; the process is finished within 30 minutes. The reaction mixture is stirred for 1 hour at 90 C. and then cooled down to 60 C. 1.0 g of active carbon (Norit Azo) is added to the reaction mixture. After stirring for 2 hours, the mixture is filtered through diatomaceous earth (Clarcel DIC), resulting in 57.7 g of compound (12) according to .sup.1H- and .sup.13C-NMR.

##STR00054##

[0226] A solution of 0.025 g of hexachloroplatinic acid in 1 mL of tetrahydrofuran is added to 50.0 g of compound (8) (ABCR), a linear poly(dimethylsiloxane) terminated by a butyl group at one end and a hydride at the other end with a viscosity of 5-9 cSt (i.e. n is about 10). The mixture is heated to 90 C. in a reactor with nitrogen as protective gas. 17.24 g of allyldidecylamine (compound (5)) is added by drop to the mixture under stirring; the process is finished within 30 minutes. The reaction mixture is stirred for 1 hour at 90 C. and then cooled down to 60 C. 1.0 g of active carbon (Norit Azo) is added to the reaction mixture. After stirring for 2 hours, the mixture is filtered through diatomaceous earth (Clarcel DIC), resulting in 62.0 g of compound (13) according to .sup.1H- and .sup.13C-NMR.

##STR00055##

[0227] A solution of 0.030 g of hexachloroplatinic acid in 1 mL of tetrahydrofuran is added to 84.0 g of compound (14) (Gelest), a linear poly(dimethylsiloxane) terminated by a butyl group at one end and a hydride at the other end with a viscosity of 10-15 cSt (i.e. n is about 12). The mixture is heated to 90 C. in a reactor with nitrogen as protective gas. 12.20 g of allyldibutylamine (compound (3)) is added by drop to the mixture under stirring; the process is finished within 30 minutes. The reaction mixture is stirred for 1.5 hours at 90 C. and then cooled down to 60 C. 2.0 g of active carbon (Norit Azo) is added to the reaction mixture. After stirring for 1 hours, the mixture is filtered through diatomaceous earth (Clarcel DIC), resulting in 90.4 g of compound (15) according to .sup.1H- and .sup.13C-NMR.

1.3 Methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane

[0228] ##STR00056##

[0229] 2.55 g of methyl iodide is added to 20.0 g of compound (9), and this mixture is stirred for 3 hours at 43 C. The reaction mixture is diluted with dichloromethane and another 1.30 g of methyl iodide is added to it. The reaction mixture is stirred for 2 hours at 43 C. After cooling to ambient temperature, the excess of methyl iodide and dichloromethane is removed in vacuo, leaving behind 20.6 g of compound (16) according to .sup.1H-NMR.

##STR00057##

[0230] 366.0 g of methyl iodide is added to 806.5 g of compound (11), and this process is finished within 30 minutes. The reaction mixture is stirred at 43 C. After adding methyl iodide, complete conversion of compound (11) is achieved according to.sup.1H-NMR. The mixture is cooled to ambient temperature and the excess of methyl iodide is removed in vacuo, leaving behind 909.9 g of compound (17).

##STR00058##

[0231] 3.38 g of methyl iodide is added to 20.0 g of compound (12), and this process is finished within 10 minutes. The reaction mixture is stirred for 5 hours at 43 C. After cooling to ambient temperature, the excess of methyl iodide and is removed in vacuo, leaving behind 19.8 g of compound (18) according to .sup.1H-NMR.

##STR00059##

[0232] 3.10 g of methyl iodide is added to 20.0 g of compound (13), and this process is finished within 10 minutes. The reaction mixture is stirred for 5 hours at 42 C. After cooling to ambient temperature, the excess of methyl iodide is removed in vacuo, leaving behind 20.8 g of compound (19) according to .sup.1H-NMR.

##STR00060##

[0233] 14.6 g of methyl iodide is added to 100.0 g of compound (15), and this process is finished within 30 minutes. The reaction mixture is stirred for 5 hours at 42 C. After cooling to ambient temperature, the excess of methyl iodide is removed in vacuo, leaving behind 109.3 g of compound (20) according to .sup.1H-NMR.

##STR00061##

[0234] 2.36 g of dimethyl sulfate is added to 20.0 g of compound (9), and the reaction mixture is diluted with 5 g of dichloromethane. The reaction mixture is stirred for 2 hours at 42 C. After cooling to ambient temperature, compound (9) and dimethyl sulfate are completely conversed, and dichloromethane is removed in vacuo, leaving behind 22.0 g of compound (21) according to.sup.1H-NMR.

##STR00062##

[0235] 0.23 g of dimethyl sulfate is added to 2.0 g of compound (10), the reaction mixture is stirred for 30 minutes at 42 C. Compound (10) and dimethyl sulfate are completely conversed, leaving behind 2.1 g of compound (22) according to .sup.1H-NMR.

##STR00063##

[0236] 7.30 g of dimethyl sulfate is added to 75.0 g of compound (11), the reaction mixture is stirred for 5 hours at 42 C. Compound (11) and dimethyl sulfate are completely conversed, leaving behind 81.3 g of compound (23) according to .sup.1H-NMR.

##STR00064##

[0237] 7.20 g of dimethyl sulfate is added to 89.9 g of compound (15), the reaction mixture is stirred for 5 hours at 42 C. Compound (15) and dimethyl sulfate are completely conversed, leaving behind 95.9 g of compound (24) according to .sup.1H-NMR.

1.4 Ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane

[0238] ##STR00065##

[0239] 0.28 g of diethyl sulfate is added to 2.0 g of compound (10), the reaction mixture is stirred first for 3 hours at 60 C. and then for 2 hours 20 minutes at 80 C. Compound (10) and diethyl sulfate are completely conversed, leaving behind 2.1 g of compound (25) according to .sup.1H-NMR.

##STR00066##

[0240] 2.66 g of diethyl sulfate is added to 20.0 g of compound (11), the reaction mixture is stirred for 3 hours at 99 C. Compound (11) and diethyl sulfate are completely conversed, leaving behind 21.5 g of compound (26) according to .sup.1H-NMR.

2. Electrophoretic Ink Dispersion Comprising Black Pigment Particles

2.1 Initial Formulation of Electrophoretic Ink Dispersion Comprising Black Pigment Particles

[0241] 0.5 g of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 1.0 g of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 1.0 g of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 7.95 g of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 0.5 g of black pigment particles (compound (27) or (28) or their mixture) and 0.05 g of dispersant (compound (29)) are added to the charge control agent solution. The mixture is dispersed with 50 g of zirconium dioxide beads (diameter: 0.5 mm) for 30 hours in a vial set in a Skandex shaker.

2.2 Final Formulation of Electrophoretic Ink Dispersion Comprising Black Pigment Particles

[0242] 30 mg of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 80 mg of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 80 mg of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 290 mg of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 600 mg of electrophoretic ink dispersion as described in 2.1 is added to the charge control agent solution. The mixture is dispersed with 1 g of zirconium dioxide beads (diameter: 0.5 mm) for 15 hours in a vial set in a Skandex shaker.

##STR00067##

2.3 Switching-Test of Electrophoretic Ink Dispersion Comprising Black Pigment Particles

[0243] A droplet of the electrophoretic ink dispersion comprising black pigment particles as described in 2.2 is spread on a glass substrate with an ITO (indium tin oxide) pattern consisting of two series of oppositely charged electrodes with 30-60 m gap in-between and covered with a cover glass. The thickness of the liquid layer is controlled by a spherical spacer material (diameter: 15 m). The ITO substrate is driven with 20V, 40V, 60V, or 80V block wave with a frequency of 1.0 Hz. The pigment particles switch between electrodes under the above mentioned driving conditions.

3. Electrophoretic Ink Dispersion Comprising Cyan Pigment Particles

3.1 Initial Formulation of Electrophoretic Ink Dispersion Comprising Cyan Pigment Particles

[0244] 0.5 g of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 1.0 g of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 1.0 g of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 7.9 g of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 0.5 g of cyan pigment particles (compound (30) or (31) or their mixture), 0.05 g of Solsperse 5000, and 0.05 g of dispersant (compound (29)) are added to the charge control agent solution. The mixture is dispersed with 50 g of zirconium dioxide beads (diameter:

[0245] 0.5 mm) for 30 hours in a vial set in a Skandex shaker.

##STR00068##

3.2 Final Formulation of Electrophoretic Ink Dispersion Comprising Cyan Pigment Particles

[0246] 30 mg of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 80 mg of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 80 mg of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 290 mg of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 600 mg of electrophoretic ink dispersion as described in 3.1 is added to the charge control agent solution. The mixture is dispersed with 1 g of zirconium dioxide beads (diameter: 0.5 mm) for 15 hours in a vial set in a Skandex shaker.

3.3 Switching-Test of Electrophoretic Ink Dispersion Comprising Cyan Pigment Particles

[0247] A droplet of the electrophoretic ink dispersion comprising cyan pigment particles as described in 3.2 is spread on a glass substrate with an ITO (indium tin oxide) pattern consisting of two series of oppositely charged electrodes with 30-60 m gap in-between and covered with a cover glass. The thickness of the liquid layer is controlled by a spherical spacer material (diameter: 15 m).

[0248] The ITO substrate is driven with 20V, 40V, 60V, or 80V block wave with a frequency of 1.0 Hz. The pigment particles switch between electrodes under the above mentioned driving conditions.

4. Electrophoretic Ink Dispersion Comprising Magenta Pigment Particles

4.1 Initial Formulation of Electrophoretic Ink Dispersion Comprising Magnetic Pigment Particles

[0249] 0.5 g of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 1.0 g of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 1.0 g of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 7.95 g of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 0.5 g of magenta pigment particles (one or more examples selected from compound (32), (33), and/or (34)) and 0.05 g of dispersant (compound (29)) are added to the charge control agent solution. The mixture is dispersed with 50 g of zirconium dioxide beads (diameter: 0.5 mm) for 30 hours in a vial set in a Skandex shaker.

##STR00069##

4.2 Final Formulation of Electrophoretic Ink Dispersion Comprising Magenta Pigment Particles

[0250] 30 mg of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 80 mg of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 80 mg of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 290 mg of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 600 mg of electrophoretic ink dispersion as described in 4.1 is added to the charge control agent solution. The mixture is dispersed with 1 g of zirconium dioxide beads (diameter: 0.5 mm) for 15 hours in a vial set in a Skandex shaker.

4.3 Switching-Test of Electrophoretic Ink Dispersion Comprising Magenta Pigment Particles

[0251] A droplet of the electrophoretic ink dispersion comprising magenta pigment particles as described in 3.2 is spread on a glass substrate with an ITO (indium tin oxide) pattern consisting of two series of oppositely charged electrodes with 30-60 m gap in-between and covered with a cover glass. The thickness of the liquid layer is controlled by a spherical spacer material (diameter: 15 m). The ITO substrate is driven with 20V, 40V, 60V, or 80V block wave with a frequency of 1.0 Hz. The pigment particles switch between electrodes under the above mentioned driving conditions.

5. Electrophoretic Ink Dispersion Comprising Yellow Pigment Particles

5.1 Initial Formulation of Electrophoretic Ink Dispersion Comprising Yellow Pigment Particles

[0252] 0.5 g of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 1.0 g of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 1.0 g of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 7.95 g of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 0.5 g of yellow pigment particles (one or more examples selected from compound (35), (36), (37), and/or (38)) and 0.05 g of dispersant (compound (29)) are added to the charge control agent solution. The mixture is dispersed with 50 g of zirconium dioxide beads (diameter: 0.5 mm) for 30 hours in a vial set in a Skandex shaker.

##STR00070##

5.2 Final Formulation of Electrophoretic Ink Dispersion Comprising Yellow Pigment Particles

[0253] 30 mg of N,N-dialkylamino-propyl-polydimethylsiloxane as described in 1.2 (one or more examples selected from compound (9), (10), (11), (12), (13), and/or (15)) and 80 mg of methyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.3 (one or more examples selected from compound (16), (17), (18), (19), (20), (21), (22), (23), and/or (24)) or 80 mg of ethyl-dialkyl-ammoniumpropyl-polydimethylsiloxane as described in 1.4 (compound (25) or (26) or their mixture) are dissolved in 290 mg of carrier fluid (one or more examples selected from alkanes, halogenated or partially halogenated alkanes, and/or siloxanes), resulting in a charge control agent solution. 600 mg of electrophoretic ink dispersion as described in 5.1 is added to the charge control agent solution. The mixture is dispersed with 1 g of zirconium dioxide beads (diameter: 0.5 mm) for 15 hours in a vial set in a Skandex shaker.

5.3 Switching-Test of Electrophoretic Ink Dispersion Comprising Yellow Pigment Particles

[0254] A droplet of the electrophoretic ink dispersion comprising yellow pigment particles as described in 5.2 is spread on a glass substrate with an ITO (indium tin oxide) pattern consisting of two series of oppositely charged electrodes with 30-60 m gap in-between and covered with a cover glass. The thickness of the liquid layer is controlled by a spherical spacer material (diameter: 15 m). The ITO substrate is driven with 20V, 40V, 60V, or 80V block wave with a frequency of 1.0 Hz. The pigment particles switch between electrodes under the above mentioned driving conditions.