RADIATION-CURABLE AQUEOUS POLYURETHANE DISPERSIONS

Abstract

The present invention is directed to radiation-curable aqueous polyurethane dispersion, wherein the dispersion comprises aniomcally stabilized polyurethane A present in disperse form; and wherein said polyurethane A comprises 5 (meth)acrylamide functional groups in an amount of at least 0.2 mmol per g of the polyurethane A.

Claims

1. A radiation-curable aqueous polyurethane dispersion, wherein the dispersion comprises anionically stabilized polyurethane A present in disperse form, and wherein said polyurethane A comprises (meth)acrylamide functional groups in an amount of at least 0.2 mmol per g of the polyurethane A.

2. The dispersion according to claim 1, wherein the polyurethane A comprises (meth)acrylamide functional groups in an amount of at least 0.35 mmol per g of the polyurethane A, more preferably in an amount of at least 0.5 mmol per g of the polyurethane A.

3. The dispersion according to claim 1, wherein the polyurethane A comprises (meth)acrylamide functional groups in an amount of at most 6 mmol per g of the polyurethane A, more preferably in an amount of at most 4 mmol per g of the polyurethane A and most preferably in an amount of at most 2.5 mmol per g of the polyurethane A.

4. The dispersion according to claim 1, wherein the amount of (meth)acrylamide functional groups present in the polyurethane A is chosen such to result in at least 50 mol % of the ethylenically unsaturated bond concentration of the polyurethane A, more preferably at least 75 mol %, even more preferably at least 90 mol % and most preferably 100 mol % of the ethylenically unsaturated bond concentration of the polyurethane A.

5. The dispersion according to claim 1, wherein said polyurethane A comprises acrylamide functional groups.

6. The dispersion according to claim 1, wherein the amount of (meth)acryloyl ester functional group(s) present in the dispersion is at most 4 meq/g solids content of the dispersion.

7. The dispersion according to claim 1, wherein the at least for a part anionically stabilized polyurethane A contains anionic functional groups selected from the group consisting of carboxylate groups, sulfonate groups, phosphonate groups and any combination thereof.

8. The dispersion according to claim 1, wherein the polyurethane A contains carboxylic acid groups and/or sulfonic acid groups which become anionic when deprotonated.

9. The dispersion according to claim 1, wherein a hydroxy-carboxylic acid(s), preferably a dihydroxy alkanoic acid(s), more preferably α,α-dimethylolpropionic acid, is chemically incorporated into the polyurethane A to provide after deprotonation at least a part of the hydrophilicity required to enable the polyurethane A to be stably dispersed in the aqueous dispersing medium.

10. The dispersion according to claim 8, wherein the neutralizing agent used to deprotonate (neutralize) the carboxylic acid groups and/or sulfonic acid groups is an alkali metal hydroxide.

11. The dispersion according to claim 1, wherein the polyurethane A is also non-ionically stabilized by chemically incorporating polyethylene oxide and/or polypropylene oxide units into the polyurethane A.

12. The dispersion according to claim 11, wherein the amount of (potentially) anionic functional groups present in the polyurethane A is such that the acid value of the polyurethane A is in the range from 10 to 50 mg KOH/g solids of the polyurethane A.

13. The dispersion according to claim 1, wherein the number average molecular weight M.sub.n of the polyurethane A is in the range from 800 to 50000 Daltons, more preferably in the range of 1000 to 25000 Daltons, most preferably in the range of 1100 to 20000 Daltons, especially preferred in the range of 1200 to 15000 Daltons.

14. The dispersion according to claim 1, wherein the polyurethane A comprises as building blocks at least (a) a polyisocyanate(s), (b) a component(s) containing or providing a (meth)acrylamide functional group(s), (c) a component(s) containing an isocyanate-reactive group(s) and an anionic group(s) which is capable to render the polyurethane A dispersible in the aqueous dispersing medium either directly or after reaction with a neutralizing agent to provide a salt, whereby component (c) being different from component (b), and (d) a component(s) containing at least one isocyanate-reactive group(s), whereby component (d) being different from component (b) and (c).

15. The dispersion according to claim 14, wherein component (b) is selected from the group consisting of N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-hydroxypropyl(meth)acrylamide, N,N-bis(hydroxyethyl)acrylamide, N,N-bis(hydroxypropyl)acrylamide and any mixture thereof, preferably component (b) is N-2-hydroxyethylacrylamide.

16. The dispersion according to claim 14, wherein at least one component containing an isocyanate group(s) and a (meth)acrylamide functional group(s) is used as component (b) (component (b2)).

17. The dispersion according to claim 14, wherein the polyurethane A is acryloyl amide functional, whereby the acrylamide functional groups are introduced into the polyurethane A by using at least one component containing an isocyanate group(s) and an acrylamide functional group(s) (component (b2)) as building block of the polyurethane A, which component (b2) is obtained in-situ before preparation of the urethane prepolymer by reacting in the presence of a catalyst an isocyanate compound having at least two isocyanate groups with acrylic acid.

18. The dispersion according to claim 17, wherein the anionic functionality of the polyurethane A is obtained by incorporating sulfonate groups into the polyurethane A.

19. The dispersion according to claim 1, wherein the polyurethane A is free of (meth)acryloyl ester functional groups.

20. The dispersion according to claim 1, wherein the dispersed particles have an average particle size of 10 nm or higher and of 200 nm or lower.

21. The dispersion according to claim 1, wherein the polyurethane A is present in an amount of from 10 to 50% by solids weight, based on the total solids weight of the dispersion.

22. Ink composition comprising the dispersion according to claim 1, wherein the amount of polyurethane A is in the range from 2 to 20 wt. %, relative to the total weight of the ink composition.

23. Use of an ink composition according to claim 22 for inkjet printing.

Description

EXAMPLES AND COMPARATIVE EXPERIMENTS

[0093] The following examples were prepared and tested. The compositions of the examples and results are as shown in the tables below.

Preparation of Radiation Curable Polyurethane Dispersion

Example 1

[0094] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components DMPA (14.4 g), pTHF650 (148.6 g), HEAAm (29.2 g), IPDI (107.9 g), acetone (75.0 g) and BHT (0.45 g). The reaction was heated to 50° C. and 0.06 g of Bismuthneodecanoate was added. The reaction was kept at 60° C. until the NCO content of the resultant urethane prepolymer was 0.65% on solids (theoretically 0.47%). The prepolymer was cooled down to 50° C. and a 15% KOH solution was added (40.0 g). A dispersion of the resultant prepolymer was made by adding deionized water (549.6 g) to the prepolymer mixture. Subsequently BYK011 was added (0.09 g) and the acetone was removed from the dispersion by distillation under vacuum. The dispersion was diluted with water until a solid content of 30 wt % was reached. The specifications of the resultant polyurethane dispersion are given in Table 1 and 2.

Example 2

[0095] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with IPDI (123 g), BHT (0.31 g) and MgCl.sub.2 (0.66 g). The mixture was heated to 70° C. and then acrylic acid (22.5 g) was slowly fed to the reactor in 30 minutes. After the feed was completed the reaction was kept at 85° C. for 60 minutes. The mixture was cooled to 35° C. and pTHF650 (146.0 g), Ymer N120 (14.6 g) and BHT (0.16 g) were charged to the reactor. Upon heating to 50° C. bismuth neodecanoate (0.21 g) was added. The mixture was allowed to exotherm and kept at 90° C. for 3 hours. The conversion was monitored by FT-IR. After the reaction was completed the mixture was cooled to 60° C. and dissolved in acetone (101.3 g). Vestamin A95 (27.1) was added and mixed for 15 minutes. Subsequently the reaction mixture was dispersed by adding water (482.8 g). The acetone was stripped off by vacuum distillation. Before distillation BYK011 (0.04 g) was added to prevent severe foaming. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Example 3

[0096] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with N3300 (23.5 g), IPDI (94.1 g), BHT (0.31 g) and MgCl.sub.2 (0.66 g). The mixture was heated to 70° C. and then acrylic acid (22.5 g) was slowly fed to the reactor in 30 minutes. After the feed was completed the reaction was kept at 85° C. for 60 minutes. The mixture was cooled to 35° C. and pTHF1000 (151.5 g), Ymer N120 (14.6 g) and BHT (0.16 g) were charged to the reactor. Upon heating to 50° C. bismuth neodecanoate (0.21 g) was added. The mixture was allowed to exotherm and kept at 90° C. for 3 hours. The conversion was monitored by FT-IR. After the reaction was completed the mixture was cooled to 60° C. and dissolved in acetone (101.3 g). Vestamin A95 (27.1) was added and mixed for 15 minutes. Subsequently the reaction mixture was dispersed by adding water (482.8 g). The acetone was stripped off by vacuum distillation. Before distillation BYK011 (0.04 g) was added to prevent severe foaming. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Example 4

[0097] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with H12MDI (130.8 g), BHT (0.31 g) and MgCl.sub.2 (0.66 g). The mixture was heated to 70° C. and then acrylic acid (22.5 g) was slowly fed to the reactor in 30 minutes. After the feed was completed the reaction was kept at 85° C. for 60 minutes. The mixture was cooled to 35° C. and pTHF650 (138.4 g), Ymer N120 (14.6 g) and BHT (0.16 g) were charged to the reactor. Upon heating to 50° C. bismuth neodecanoate (0.21 g) was added. The mixture was allowed to exotherm and kept at 90° C. for 3 hours. The conversion was monitored by FT-IR. After the reaction was completed the mixture was cooled to 60° C. and dissolved in acetone (101.3 g). Vestamin A95 (27.1 g) was added and mixed for 15 minutes. Subsequently the reaction mixture was dispersed by adding water (482.8 g). The acetone was stripped off by vacuum distillation. Before distillation BYK011 (0.04 g) was added to prevent severe foaming. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Example 5

[0098] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components DMPA (10.1 g), pTHF650 (105.0 g), HEAAm (20.6 g), IPDI (76.3 g), acetone (53.0) and BHT (0.32 g). The reaction was heated to 50° C. and 0.04 g of Bismuthneodecanoate was added. The reaction was kept at 60° C. until the NCO content of the resultant urethane prepolymer was 0.37% on solids (theoretically 0.52%). The prepolymer was cooled down to 40° C. and DiTMPTA (8.4 g) was added. After mixing for 5 minutes, a 15% KOH solution was added (28.3 g). A dispersion of the resultant prepolymer was made by adding deionized water (518.6 g) to the prepolymer mixture. Subsequently BYK011 was added (0.06 g) and the acetone was removed from the dispersion by vacuum distillation. The dispersion was diluted with water until a solid content of 30 wt % was reached. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Example 6

[0099] To 300 gram of example 2, 14.0 g of HEAAm and 152.6 g of water was added at room temperature and mixed for 15 minutes. The specifications of the resultant polyurethane after filtration dispersion are given in Table 1 and 2.

Example 7

[0100] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with IPDI (116.4 g), BHT (0.31 g) and MgCl.sub.2 (0.66 g). The mixture was heated to 70° C. and then acrylic acid (22.5 g) was slowly fed to the reactor in 30 minutes. After the feed was completed the reaction was kept at 85° C. for 60 minutes. The mixture was cooled to 35° C. and pTHF650 (123.5 g), Ymer N120 (14.6 g), DPHA (29.3) and BHT (0.16 g) were charged to the reactor. Upon heating to 50° C. bismuth neodecanoate (0.21 g) was added. The mixture was allowed to exotherm and kept at 90° C. for 3 hours. The conversion was monitored by FT-IR. After the reaction was completed the mixture was cooled to 60° C. and dissolved in acetone (101.3 g). Vestamin A95 (27.1) was added and mixed for 15 minutes. Subsequently the reaction mixture was dispersed by adding water (482.8 g). The acetone was stripped off by vacuum distillation. Before distillation BYK011 (0.04 g) was added to prevent severe foaming. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Example 8

[0101] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with Desmodur H (19.7 g), IPDI (78.6 g), BHT (0.31 g) and MgCl.sub.2 (0.65 g). The mixture was heated to 70° C. and then acrylic acid (22.3 g) was slowly fed to the reactor in 30 minutes. After the feed was completed the reaction was kept at 85° C. for 60 minutes. The mixture was cooled to 35° C. and pTHF1000 (167.6 g), Ymer N120 (14.5 g) and BHT (0.16 g) were charged to the reactor. Upon heating to 50° C. bismuth neodecanoate (0.20 g) was added. The mixture was allowed to exotherm and kept at 90° C. for 3 hours. The conversion was monitored by FT-IR. After the reaction was completed the mixture was cooled to 60° C. and dissolved in acetone (100.1 g). Vestamin A95 (33.8) was added and mixed for 15 minutes. Subsequently the reaction mixture was dispersed by adding water (479.2 g). The acetone was stripped off by vacuum distillation. Before distillation BYK011 (0.04 g) was added to prevent severe foaming. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Example 9

[0102] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with TMDI (118.5 g), BHT (0.31 g) and MgCl.sub.2 (0.66 g). The mixture was heated to 70° C. and then acrylic acid (22.5 g) was slowly fed to the reactor in 30 minutes. After the feed was completed the reaction was kept at 85° C. for 60 minutes. The mixture was cooled to 35° C. and pTHF650 (150.6 g), Ymer N120 (14.6 g) and BHT (0.16 g) were charged to the reactor. Upon heating to 50° C. bismuth neodecanoate (0.21 g) was added. The mixture was allowed to exotherm and kept at 90° C. for 3 hours. The conversion was monitored by FT-IR. After the reaction was completed the mixture was cooled to 60° C. and dissolved in acetone (101.3 g). Vestamin A95 (27.1) was added and mixed for 15 minutes. Subsequently the reaction mixture was dispersed by adding water (482.8 g). The acetone was stripped off by vacuum distillation. Before distillation BYK011 (0.04 g) was added to prevent severe foaming. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2.

Comparative Experiment 1

[0103] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components DMPA (14.4 g), pTHF650 (148.6 g), HEA (29.2 g), IPDI (107.9 g), acetone (75.0 g) and BHT (0.45 g). The reaction was heated to 50° C. and 0.06 g of bismuthneodecanoate was added. The reaction was kept at 60° C. until the NCO content of the resultant urethane prepolymer was 0.67% on solids (theoretically 0.47%). The prepolymer was cooled down to 50° C. and a 15% KOH solution was added (40.0 g). A dispersion of the resultant prepolymer was made by adding deionized water (549.7 g) to the prepolymer mixture. Subsequently BYK011 was added (0.09 g) and the acetone was removed from the dispersion by distillation under vacuum. The dispersion was diluted with water until a solid content of 30 wt % was reached. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2. In this Comparative Experiment 1 the polyurethane has acryloyl ester functional groups, but no (meth)acryloyl amide functional groups.

Comparative Experiment 2

[0104] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components PEG1000 (193.0 g), HEAAm (30.7 g), IPDI (76.3 g) and BHT (0.45 g). The reaction was heated to 50° C. and 0.06 g of Bismuthneodecanoate was added. The reaction was kept at 80° C. until the NCO content of the resultant urethane prepolymer was 0.49% on solids (theoretically 0.46%). The prepolymer was cooled down to 65° C. and a solution of the resultant prepolymer was made by adding deionized water (468.0 g) to the prepolymer mixture. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2. In this Comparative Experiment 2 the polyurethane is solely non-ionically stabilized.

Comparative Experiment 3

[0105] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components DMPA (30.4 g), PC diol (170.4 g), IPDI (161.4 g) and NBP (154.9 g). The reaction was heated to 50° C. and 0.26 g of DBTDL was added. The mixture was allowed to exotherm and kept at 90° C. for 2 hours. The NCO content of the resultant urethane prepolymer was 4.58% on solids (theoretically 5.10%). The prepolymer was cooled down to 75° C. and ethanol was added (86.7 g). After mixing at 75° C. for 2.5 hours, TEA (22.9 g) was added. A dispersion of the resultant prepolymer was made by feeding 459.7 g of this prepolymer to deionized water (496.8 g). To 300 gram of this dispersion, 45.0 g of HEAAm and 105.0 g of water was added at room temperature and mixed for 15 minutes. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2. In this Comparative Experiment 3 the polyurethane does not have ethylenically unsaturated bond functionality and hence the polyurethane is not radiation-curable. The dispersion is radiation-curable due to the presence of HEAAm in the dispersion. The urethane prepolymer is capped with ethanol and dispersed in water and then HEAAm is added. There is no reaction between the polyurethane and HEAAm and consequently the amount of acrylamide functional groups in the polyurethane is 0.

Comparative Experiment 4

[0106] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components DMPA (31.3 g), PC diol (175.7 g), IPDI (166.5 g) and NBP (159.7 g). The reaction was heated to 50° C. and 0.27 g of DBTDL was added. The mixture was allowed to exotherm and kept at 90° C. for 2 hours. The NCO content of the resultant urethane prepolymer was 4.50% on solids (theoretically 5.10%). The prepolymer was cooled down to 80° C. and TEA (23.7 g) was added. A dispersion of the resultant prepolymer was made by feeding 408.6 g of this prepolymer to deionized water (476.8 g). After dispersion was done, a mixture of EDA (12.9 g) and deionized water (38.6 g) was added to the dispersion in 10 minutes and rinsed with 19.7 g deionized water. To 300 gram of this dispersion, 45.0 g of HEAAm and 105.0 g of water was added at room temperature and mixed for 15 minutes. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2. In this Comparative Experiment 4 the polyurethane does not have ethylenically unsaturated bond functionality and hence the polyurethane is not radiation-curable. The dispersion is radiation-curable due to the presence of HEAAm in the dispersion. The urethane prepolymer is first dispersed in water and then chain-extended with ethylenediamine. To the chain-extended polyurethane dispersion HEAAm was added. There is no reaction between the polyurethane and HEAAm and consequently the amount of acrylamide functional groups in the polyurethane is 0.

Comparative Experiment 5

[0107] A 1000 cm.sup.3 flask equipped with a thermometer and overhead stirrer was charged with components DMPA (20.8 g), PC diol (116.9 g), IPDI (110.7 g) and NBP (106.2 g). The reaction was heated to 50° C. and 0.18 g of DBTDL was added. The mixture was allowed to exotherm and kept at 90° C. for 2 hours. The NCO content of the resultant urethane prepolymer was 4.27% on solids (theoretically 5.10%). The prepolymer was cooled down to 80° C. and TMPTA (47.0 g), TPGDA (58.0 g), BHT (0.17 g) and TEA (23.7 g) were added. A dispersion of the resultant prepolymer was made by feeding 373.8 g of this prepolymer to deionized water (526.7 g). After dispersion was done, a mixture of EDA (9.2 g) and deionized water (27.5 g) was added to the dispersion in 10 minutes and rinsed with 19.3 g deionized water. To 300 gram of this dispersion, 45.0 g of HEAAm and 105.0 g of water was added at room temperature and mixed for 15 minutes. The specifications of the resultant polyurethane dispersion after filtration are given in Table 1 and 2. In this Comparative Experiment 5 the polyurethane does not have ethylenically unsaturated bond functionality and hence is not radiation-curable. The urethane prepolymer is prepared in the presence of TMPTA and TPGDA which are radiation-curable diluents but they are not chemically incorporated into the polyurethane since they are not isocyanate-reactive. The urethane prepolymer is first dispersed in water and then chain-extended with ethylenediamine. To the chain-extended polyurethane dispersion HEAAm was added. There is no reaction between the polyurethane and HEAAm and consequently the amount of acrylamide functional groups in the polyurethane is 0.

TABLE-US-00001 TABLE 1 Specifications of prepared (comparative) examples. Solids pH PS Viscosity M.sub.n M.sub.w Sample [%] [−] [nm] [mPa .Math. s] [g/mol] [g/mol] Ex 1. 30.6 8.1 37 11 1715 6625 Ex 2. 42.0 6.6 101 112 2352 33140 Ex 3. 40.6 6.3 104 42 3268 170909 Ex 4. 36.5 7.1 106 119 2607 18999 Ex 5. 31.3 7.9 40 17 1985 6843   4244*    7956* Ex 6. 30.0 6.7 89 6   2352*    33140* Ex. 7 39.1 6.3 63 34 1711 13157 Ex. 8 39.6 7.3 71 31 2054 15704 Ex. 9 38.7 7.4 64 105 2668 61321 CEx 1. 30.3 8.0 75 13 2209 6364 CEx 2. 38.0 7.0 n.a. 68 4565 25049 CEx 3. 30.1 8.2 57 47 612 2255   2653*    4005* CEx 4. 26.0 8.6 52 80 1032 42834 14246*    60099* CEx 5. 30.0 7.8 44 74 906 53759 16462*    89057* *Excluding fraction with molar mass < 1000 g/mol (reactive diluent)

TABLE-US-00002 TABLE 2 PS and viscosity of PU binders (all diluted to 30 wt % solid content) of freshly prepared samples and upon storage at room temperature (22 ± 2° C.) and 60° C. Start (after 1 day Storage storage 3 7 14 21 28 temp at RT) days days days days days Ex. 1 PS RT 37 42 47 46 45 44 (nm) 60° C. 42 45 46 42 35 Viscosity RT 11.4 10.6 10.5 10.7 10.7 11.0 (mPa .Math. s) 60° C. 10.3 10.1 10.7 11.0 13.0 CEx. 1 PS RT 75 48 57 60 61 62 (nm) 60° C. 82 102 106 107 106 Viscosity RT 12.6 8.6 8.1 7.9 7.8 7.8 (mPa .Math. s) 60° C. 6.5 5.3 5.6 5.8 6.1 CEx. 2 PS RT n.a. (nm) 60° C. Viscosity RT n.d. (mPa .Math. s) 60° C. Ex. 2 PS RT 95 99 96 97 93 90 (nm) 60° C. 91 95 94 95 96 Viscosity RT 7.6 7.4 7.3 7.1 7.1 7.0 (mPa .Math. s) 60° C. 7.8 7.8 7.5 7.1 6.9 Ex. 3 PS RT 106 106 102 103 105 101 (nm) 60° C. 104 102 102 104 103 Viscosity RT 6.9 6.3 6.0 6.0 5.9 5.9 (mPa .Math. s) 60° C. 6.5 6.3 6.4 6.4 6.2 Ex. 4 PS RT 105 109 101 103 105 104 (nm) 60° C. 112 101 103 103 99 Viscosity RT 16.3 15.6 14.9 14.4 14.5 14.8 (mPa .Math. s) 60° C. 13.3 12.7 12.6 13.3 13.0 Ex. 5 PS RT 40 44 44 44 47 46 (nm) 60° C. 45 43 42 42 41 Viscosity RT 11.5 10.4 10.5 10.3 10.4 10.6 (mPa .Math. s) 60° C. 10.1 10.5 10.7 10.9 10.9 Ex. 6 PS RT 89 89 89 92 92 (nm) 60° C. 87 88 88 92 Viscosity RT 6.2 5.8 5.8 5.7 5.8 5.6 (mPa .Math. s) 60° C. 6.0 6.0 5.8 5.7 5.6 Ex. 7 PS RT 65 65 64 65 65 (nm) 60° C. 73 77 78 79 Viscosity RT 6.6 6.9 6.9 6.8 6.8 (mPa .Math. s) 60° C. 6.5 6.6 6.3 6.1 Ex. 8 PS RT 71 73 66 71 72 (nm) 60° C. 72 68 68 73 Viscosity RT 6.3 6.7 6.7 6.5 6.5 (mPa .Math. s) 60° C. 6.6 6.5 6.4 6.3 Ex. 9 PS RT 64 70 68 69 69 (nm) 60° C. 73 69 68 74 Viscosity RT 11.8 11.9 11.7 11.2 11.2 (mPa .Math. s) 60° C. 11.8 11.8 11.6 11.4 CEx. PS RT 55 58 60 64 61 57 3 (nm) 60° C. 99 146 165 192 189 Viscosity RT 8.2 8.0 8.0 7.9 7.8 7.8 (mPa .Math. s) 60° C. 7.8 7.7 7.7 7.7 7.6 CEx. PS RT 51 55 50 50 55 57 4 (nm) 60° C. 41 38 40 38 35 Viscosity RT 21.0 19.1 18.4 16.7 16.1 15.5 (mPa .Math. s) 60° C. 11.9 12.7 12.2 12.2 12.5 CEx. PS RT 41 45 39 39 45 43 5 (nm) 60° C. 54 44 50 55 77 Viscosity RT 10.7 9.6 9.3 9.1 9.0 8.9 (mPa .Math. s) 60° C. 8.2 7.1 6.1 5.7 5.3

[0108] It can be seen from Table 2 that the examples according to the invention retain their particle size and viscosity stability even after prolonged storage at elevated temperatures, whereas the particle size of the dispersions according to the comparative examples CEx1, CEx3 & CEx5 show a significant increase upon storage and/or a pronounced viscosity drop.

[0109] The binders of the Examples and Comparative Experiments were formulated according to Table 3.

TABLE-US-00003 TABLE 3 Formulation Formulation Resin [20 wt % solid content] 42.5  ProJet ™ Cyan APD1000 7.5 supplied by FujiFilm Surfynol 420 0.3 Omnirad TPO-L 0.3 Omnirad 1173 0.3 Application conditions Wet Film Thickness 12 μm Substrate White PE foil Drying conditions 180 seconds @ 90° C. Cure conditions 2 pass @ 500 mJ, Mercury lamp

TABLE-US-00004 TABLE 4 Application properties 25% EtOH Water resistance resistance of of cured Tackiness Tackiness cured film film [tissue before after [tissue hand hand 100 Resolubility cure cure 100 rubs] rubs] Ex. 1 + Tacky Tack-free 4 4 CEx. 1 + Tacky Tack-free 3 3 CEx. 2 + Tacky Tacky 1 1 Ex 2. + Tacky Tack-free 5 4 Ex 3. − Tacky Tack-free 5 4 Ex 4. +/− Tacky Tack-free 5 4 Ex 5. + Tacky Tack-free 5 4 Ex 6. + Tacky Tack-free 5 4 Ex. 7 + Tacky Tack-free 5 5 Ex. 8 +/− Tacky Tack-free 2 2 Ex. 9 + Tacky Tack-free 3 3 CEx. 3 − Tacky Slightly 0 0 Tacky CEx. 4 − Tack-free Tack-free 5 5 CEx. 5 − Tack-free Tack-free 5 5