Colored resin particle dispersion and inkjet ink

Abstract

A colored resin particle dispersion and an ink are provided which yield excellent abrasion resistance and prevent change in the color tone. Moreover, a colored resin particle dispersion and an inkjet ink are provided which exhibit excellent abrasion resistance, together with excellent water resistance and marker resistance. Specifically provided is a colored resin particle dispersion containing colored resin particles, a basic dispersant, and a non-aqueous solvent, wherein the colored resin particles include a colorant, a solid resin and a liquid organic compound having an acidic group, and the oxidation-reduction potential of the colored resin particle dispersion is 300 mV or less. Also provided is an inkjet ink containing this colored resin particle dispersion.

Claims

1. A colored resin particle dispersion comprising: colored resin particles; a basic dispersant; and a non-aqueous solvent, wherein the colored resin particles comprise a colorant, a solid resin and a liquid organic compound having an acidic group, a mass ratio of the liquid organic compound having an acidic group to the colorant is not less than 0.5, and an oxidation-reduction potential of the colored resin particle dispersion is 300 mV or less.

2. The colored resin particle dispersion according to claim 1, wherein the colorant comprises a dye and/or a dye lake pigment.

3. The colored resin particle dispersion according to claim 2, wherein the colorant comprises a dye.

4. The colored resin particle dispersion according to claim 2, wherein the colorant comprises a dye lake pigment.

5. The colored resin particle dispersion according to claim 1, wherein the colorant comprises a metal complex dye.

6. The colored resin particle dispersion according to claim 1, wherein the acidic group of the liquid organic compound having an acidic group comprises a phosphoric acid group.

7. An inkjet ink comprising the colored resin particle dispersion according to claim 1.

Description

EXAMPLES

(1) The present invention is described below in further detail using a series of examples, but the present invention is in no way limited by these examples. Unless specifically state otherwise, “%” refers to “mass %”.

(2) <Ink Preparation>

(3) Formulations of oil-in-oil emulsions for a series of examples and comparative examples prior to removal of the solvent B are shown in Table 2 to Table 4. In each table, when a dispersant includes a volatile component, the total amount of the dispersant is shown, and the non-volatile fraction amount is also shown in parentheses (this also applies in Tables 5 to 7 below). Further, the units for the acid values and the amine values shown in each of the tables are mgKOH/g.

(4) The continuous phase was prepared by mixing the solvent A and the basic dispersant in the blend amounts shown in each table. Subsequently, the dispersed phase was prepared by mixing the colorant, the solid resin and the acidic compound with the solvent B in the blend amounts shown in each table, and then dispersing the resulting mixture using a beads mill.

(5) With the continuous phase in a state of continuous stirring with a magnetic stirrer under ice cooling, a 10 minute irradiation with an ultrasonic homogenizer (Ultrasonic Processor VC-750, manufactured by Sonics & Materials, Inc.) was conducted while the premixed dispersed phase was added dropwise to the continuous phase, thus obtaining an oil-in-oil (O/O) emulsion.

(6) The solvent B within the dispersed phase was removed from the obtained emulsion under reduced pressure using an evaporator, thus obtaining a colored resin particle dispersion. The rate of removal of the solvent B was essentially 100 mass %. This colored resin particle dispersion was used as an ink with no further modification.

(7) Inks of the examples and comparative examples were also prepared in the same manner as described above, with the following exceptions.

(8) In Examples 2, 3, 9 and 10, dicyclohexylamine was also added to the continuous phase.

(9) The oxidation-reduction potential of each ink was adjusted using the blend amounts of the basic dispersant, the acidic compound and the dicyclohexylamine.

(10) Formulations of the inks of the examples and comparative examples following removal of the solvent B are shown in Table 5 to Table 7. The amount of the non-volatile fraction was determined from the combined total of the amount of each of the non-volatile components (the basic dispersant, the colorant, the solid resin, the acidic compound and the dicyclohexylamine) relative to the total mass of the ink, and this amount of the non-volatile fraction is also shown in each table.

(11) TABLE-US-00002 TABLE 2 Formulations of oil-in-oil emulsions of Examples (prior to solvent B removal) Example Units: mass % 1 2 3 4 5 6 Continuous Solvent A Isopar M 68.5 68.4 68.0 67.0 67.0 64.0 phase Basic S17000 1.5 1.5 1.5 3.0 dispersant S11200 3.0 6.0 (non-volatile (1.5) (3.0) fraction 50%) Additive Dicyclohexylamine 0.1 0.5 Dispersed Solvent B Methanol 23.5 22.5 22.5 22.5 22.5 22.5 phase Colorant Black metal complex 2.5 2.5 2.5 2.5 2.5 2.5 dye Valifast Black 3810 Acidic BYK111 1.5 2.5 2.5 2.5 2.5 2.5 compound (non-volatile (1.4) (2.4) (2.4) (2.4) (2.4) (2.4) fraction 95%) Solid Polyvinyl alcohol 2.5 2.5 2.5 2.5 2.5 2.5 resin JMR-8L Polyvinyl alcohol JMR-10L Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0

(12) TABLE-US-00003 TABLE 3 Formulations of oil-in-oil emulsions of Examples (prior to solvent B removal) Example Units: mass % 7 8 9 10 11 Continuous Solvent A Isopar M 68.5 68.4 68.4 67.0 67.0 phase Basic S17000 1.5 1.5 1.5 dispersant S11200 3.0 3.0 (non-volatile (1.5) (1.5) fraction 50%) Additive Dicyclohexylamine 0.1 0.1 Dispersed Solvent B Methanol 22.5 22.5 22.5 22.5 22.5 phase Colorant Red acid dye 2.5 Water Red 27 Red metal complex dye 2.5 Orasol Pink 5BLG Red salt-forming dye 2.5 Valifast Red 1308 Dye lake pigment 2.5 Seikalight Magenta 2R Black metal complex 2.5 dye Valifast Black 3830 Acidic BYK111 2.5 2.5 2.5 2.5 2.5 compound (non-volatile (2.4) (2.4) (2.4) (2.4) (2.4) fraction 95%) Solid Polyvinyl alcohol 2.5 2.5 2.5 2.5 2.5 resin JMR-8L Polyvinyl alcohol JMR-10L Total (mass %) 100.0 100.0 100.0 100.0 100.0

(13) TABLE-US-00004 TABLE 4 Formulations of oil-in-oil emulsions of Comparative Examples (prior to solvent B removal) Comparative Example Units: mass % 1 2 3 4 5 6 Continuous Solvent A Isopar M 68.5 68.5 68.5 68.5 68.5 68.5 phase Basic S17000 1.5 1.5 1.5 1.5 1.5 1.5 dispersant S11200 (non-volatile fraction 50%) Additive Dicyclohexylamine Dispersed Solvent B Methanol 22.5 21.5 23.5 21.5 22.5 22.5 phase Colorant Black metal complex 2.5 2.5 2.5 2.5 2.5 dye Valifast Black 3810 Black metal complex 2.5 dye Valifast Black 3830 Acidic BYK111 2.5 3.5 2.5 2.5 2.5 2.5 compound (non-volatile (2.4) (3.4) (2.4) (2.4) (2.4) (2.4) fraction 95%) Solid Polyvinyl alcohol 2.5 2.5 1.5 3.5 2.5 resin JMR-8L Polyvinyl alcohol 2.5 JMR-10L Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0

(14) The components shown in each of the tables are described below.

(15) (Continuous Phase)

(16) Isopar M: an isoparaffin-based hydrocarbon-based solvent, manufactured by TonenGeneral Sekiyu K.K.

(17) Basic dispersant “S17000”: Solsperse 17000 manufactured by Lubrizol Japan Ltd., non-volatile fraction 100%, base value 2 mgKOH/g.

(18) Basic dispersant “S11200”: Solsperse 11200 manufactured by Lubrizol Japan Ltd., non-volatile fraction 50%, base value 37 mgKOH/g.

(19) Dicyclohexylamine: manufactured by Wako Pure Chemical Industries, Ltd.

(20) (Dispersed Phase)

(21) Methanol: an alcohol-based solvent having a carbon number of 1, manufactured by Wako Pure Chemical Industries, Ltd.

(22) Black metal complex dye: “Valifast Black 3810” manufactured by Orient Chemical Industries Co., Ltd.

(23) Black metal complex dye: “Valifast Black 3830” manufactured by Orient Chemical Industries Co., Ltd.

(24) Red acid dye: “Water Red 27” manufactured by Orient Chemical Industries Co., Ltd.

(25) Red metal complex dye: “Orasol Pink 5BLG” manufactured by BASF Japan Ltd.

(26) Red salt-forming dye: “Valifast Red 1308” manufactured by Orient Chemical Industries Co., Ltd.

(27) Dye lake pigment: “Seikalight Magenta 2R” manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.

(28) Acidic compound “BYK111”: a liquid organic compound having two phosphoric acid groups (a phosphate ester compound having phosphoric acid groups at both terminals of a copolymer), “DISPERBYK-111” manufactured by BYK-Chemie Japan K.K., acid value 129 mgKOH/g, non-volatile fraction 95.0%.

(29) Polyvinyl alcohol 1: degree of saponification 2.7 mol %, weight-average molecular weight 15,000, “JMR-8L” manufactured by Japan VAM & Poval Co., Ltd.

(30) Polyvinyl alcohol 2: degree of saponification 37.3 mol %, weight-average molecular weight 17,500, “JMR-10L” manufactured by Japan VAM & Poval Co., Ltd.

(31) The solubility of the methanol of the solvent B in the hydrocarbon-based solvent (Isopar M) of the solvent A at 23° C. is 0.4 g/100 g. Further, the boiling point of methanol is 64.7° C., and the 50% distillation point of Isopar M is 234° C.

(32) The basic dispersant and the dicyclohexylamine were dissolved in the solvent A in accordance with the continuous phase blend proportions shown in Table 2 to Table 4, whereas the solubility of each of these components in the solvent B at 23° C. was less than 3 g/100 g.

(33) The solid resins were dissolved in the solvent B in accordance with the dispersed phase blend proportions shown in Table 2 to Table 4, whereas the solubility of the solid resins in the solvent A at 23° C. was less than 3 g/100 g, and the solubility in water at 23° C. was less than 3 g/100 g.

(34) The acidic compound was dissolved in the solvent B in accordance with the dispersed phase blend proportions shown in Table 2 to Table 4, whereas the solubility of the acidic compound in the solvent A at 23° C. was less than 3 g/100 g.

(35) The solubility parameter (HSP value) of each component is detailed below. The units are MPa/cm.sup.3. Further, the dispersion parameter δd, the polar parameter δp, and the hydrogen bonding parameter δh are also shown below.

(36) Solvent A “Isopar M”: 16 (δd=16, δp=0, δh=0).

(37) Solvent B “Methanol”: 29.6 (δd=15.1, δp=12.3, δh=22.3).

(38) The various solid resins: within a range from 22 to 27 (δd=12 to 20, δp=5 to 12, δh=10 to 20).

(39) The acidic compound: 22 to 27 (δd=12 to 20, δp=5 to 12, δh=10 to 20).

(40) The oxidation-reduction potential (ORP value) of each component is listed below. The units are mV.

(41) Solsperse 17000: the ORP value when dissolved in dodecane at 5.0 mass % was lower than the ORP value when dissolved at 0.5 mass %, and the ORP value when dissolved in dodecane at 5.0 mass % was 325.

(42) Solsperse 11200: the ORP value when dissolved in dodecane at 5.0 mass % was lower than the ORP value when dissolved at 0.5 mass %, and the ORP value when dissolved in dodecane at 5.0 mass % was −85.

(43) DISPERBYK-111: the ORP value when dissolved in methanol at 5.0 mass % was higher than the ORP value when dissolved at 0.5 mass %, and the ORP value when dissolved in methanol at 5.0 mass % was 350.

(44) TABLE-US-00005 TABLE 5 Ink formulations of Examples (after solvent B removal) and evaluation results Examples Units: mass % 1 2 3 4 5 6 Continuous Solvent A Isopar M 89.4 88.4 87.9 86.6 86.6 82.8 phase Basic S17000 2.0 1.9 1.9 3.8 dispersant S11200 3.8 7.6 (non-volatile (1.9) (3.8) fraction 50%) Additive Dicyclohexylamine 0.1 0.6 Dispersed Solvent B Methanol 0.0 0.0 0.0 0.0 0.0 0.0 phase Colorant Black metal complex 3.3 3.2 3.2 3.2 3.2 3.2 dye Valifast Black 3810 Acidic BYK111 2.0 3.2 3.2 3.2 3.2 3.2 compound (non-volatile (1.9) (3.0) (3.0) (3.0) (3.0) (3.0) fraction 95%) Solid Polyvinyl alcohol 3.3 3.2 3.2 3.2 3.2 3.2 resin JMR-8L Polyvinyl alcohol JMR-10L Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0 Amount of non-volatile fraction (mass %) 10.5 11.3 11.3 13.2 11.3 13.2 Evaluations Average particle 180 150 150 150 120 110 size [nm] Oxidation-reduction 290 240 0 290 260 200 potential (mV) Δh B A A B B A ΔE B A A B A A Rub fastness after A A A A A B standing for 1 day Storage stability B A A B AA AA at 70° C. (precipitation) Water resistance A A A A A A after standing for 1 day

(45) TABLE-US-00006 TABLE 6 Ink formulations of Examples (after solvent B removal) and evaluation results Examples Units: mass % 7 8 9 10 11 Continuous Solvent A Isopar M 88.5 88.4 88.4 86.6 86.6 phase Basic S17000 1.9 1.9 1.9 dispersant S11200 3.8 3.8 (non-volatile (1.9) (1.9) fraction 50%) Additive Dicyclohexylamine 0.1 0.1 Dispersed Solvent B Methanol 0.0 0.0 0.0 0.0 0.0 phase Colorant Red acid dye 3.2 Water Red 27 Red metal complex dye 3.2 Orasol Pink 5BLG Red salt-forming dye 3.2 Valifast Red 1308 Dye lake pigment 3.2 Seikalight Magenta 2R Black metal complex 3.2 dye Valifast Black 3830 Acidic BYK111 3.2 3.2 3.2 3.2 3.2 compound (non-volatile (3.0) (3.0) (3.0) (3.0) (3.0) fraction 95%) Solid Polyvinyl alcohol 3.2 3.2 3.2 3.2 3.2 resin JMR-8L Polyvinyl alcohol JMR-10L Total (mass %) 100.0 100.0 100.0 100.0 100.0 Amount of non-volatile fraction (mass %) 11.3 11.3 11.3 11.3 11.3 Evaluations Average particle 150 220 170 240 130 size [nm] Oxidation-reduction 230 250 235 110 270 potential (mV) Δh A A A A B ΔE A A A B A Rub fastness after A A A A A standing for 1 day Storage stability A A A B AA at 70° C. (precipitation) Water resistance B A A A A after standing for 1 day

(46) TABLE-US-00007 TABLE 7 Ink formulations of Comparative Examples (after solvent B removal) and evaluation results Comparative Example Units: mass % 1 2 3 4 5 6 Continuous Solvent A Isopar M 88.5 87.2 89.4 87.2 88.5 88.5 phase Basic S17000 1.9 1.9 2.0 1.9 1.9 1.9 dispersant S11200 (non-volatile fraction 50%) Additive Dicyclohexylamine Dispersed Solvent B Methanol 0.0 0.0 0.0 0.0 0.0 0.0 phase Colorant Black metal complex 3.2 3.2 3.3 3.2 3.2 dye Valifast Black 3810 Black metal complex 3.2 dye Valifast Black 3830 Acidic BYK111 3.2 4.5 3.3 3.2 3.2 3.2 compound (non-volatile (3.0) (4.2) (3.1) (3.0) (3.0) (3.0) fraction 95%) Solid Polyvinyl alcohol 3.2 3.2 2.0 4.5 3.2 resin JMR-8L Polyvinyl alcohol 3.2 JMR-10L Total (mass %) 100.0 100.0 100.0 100.0 100.0 100.0 Amount of non-volatile fraction (mass %) 11.3 12.5 10.4 12.5 11.3 11.3 Evaluations Average particle 140 160 160 180 150 160 size [nm] Oxidation-reduction 310 330 305 340 310 380 potential (mV) Δh C C C C C C ΔE C C C C C C Rub fastness after A B B A A A standing for 1 day Storage stability B B B B B B at 70° C. (precipitation) Water resistance A A A A A A after standing for 1 day
<Evaluations>

(47) Using each of the inks described above, each of the following evaluations was performed. The results are shown in each of the tables.

(48) (Oxidation-Reduction Potential)

(49) The oxidation-reduction potential (ORP) of each ink was measured at 23° C. using a portable pH meter “pH-208” and an ORP electrode “ORP-14” (both manufactured by FUSO Co., Ltd.).

(50) (Δh Value)

(51) For each of the prepared inks, a 70° C. accelerated test was performed, printed items were prepared using the ink before and after the test, the L* value, a* value and b* value of the printed items before and after the test were measured, and the hue difference Δh was calculated.

(52) The 70° C. accelerated test used an incubator SLI-1201 (manufactured by Tokyo Rikakikai Co., Ltd.). Each ink was placed in a glass bottle, and the bottle was sealed and stored for one week in the incubator set to 70° C.

(53) Printing was performed by mounting each of the inks in a line-type inkjet printer “Orphis-X9050” (manufactured by Riso Kagaku Corporation), and then printing a solid image onto a high-quality coated paper “Aurora Coated Paper” (manufactured by Nippon Paper Industries Co., Ltd.). The printing was performed at a resolution of 300×300 dpi, under discharge conditions including an ink volume per dot of 42 pl. The “Orphis X9050” is a system that uses a line-type inkjet head, wherein the paper is transported in a sub-scanning direction perpendicular to the main scanning direction (the direction along which the nozzles are aligned) while printing is conducted.

(54) Using a spectroscopic color difference meter (TC-1800, Mk-11 model, manufactured by Tokyo Denshoku Co., Ltd.), the a* value and the b* value were measured for the printed item printed using the ink before the 70° C. accelerated test, and the printed item printed using the ink after the 70° C. accelerated test. The hue difference Δh value was then calculated from these measured values using the formula shown below, and evaluated against the following criteria.
h=tan−1(b*/a*)(rad)
h=tan−1(b*/a*)/π×180(degree)
Δh=|h(before accelerated test)−h(after accelerated test)|

(55) A: Δh less than 10

(56) B: Δh at least 10 but less than 20

(57) C: Δh 20 or greater

(58) (ΔE Value)

(59) For each of the prepared inks, a 70° C. accelerated test was performed, printed items were prepared using the ink before and after the test, and the ΔE value for the printed items was measured.

(60) The 70° C. accelerated test and the printing method were performed in the same manner as that described above for the Δh value test.

(61) Using a spectroscopic color difference meter (TC-1800, Mk-II model, manufactured by Tokyo Denshoku Co., Ltd.), the ΔE value was measured for the printed item printed using the ink before the 70° C. accelerated test and the printed item printed using the ink after the 70° C. accelerated test. The ΔE value was evaluated against the following criteria.

(62) A: ΔE less than 6

(63) B: ΔE at least 6 but less than 10

(64) C: ΔE 10 or greater

(65) (Rub Fastness)

(66) A printed item was obtained using the same printing method as that described above for the Δh value test. Following standing for 24 hours (1 day) after printing, the solid image portion of the printed item was rubbed strongly 5 times with a finger. The state of the printed item was then inspected visually, and the rub fastness was evaluated against the following criteria.

(67) A: almost no separation of the image could be detected.

(68) B: minor separation of the image was confirmed, but not problematic in actual use.

(69) C: marked separation of the image occurred, at a level problematic for actual use.

(70) (Storage Stability)

(71) Each of the inks was placed in a glass bottle, and the bottle was sealed and stored at 70° C. After storage for 2 weeks, the ink was inspected visually for the amount of precipitation, and the storage stability was evaluated against the following criteria.

(72) A: no precipitation.

(73) B: a small amount of fluid precipitate.

(74) C: non-fluid precipitate.

(75) (Water Resistance)

(76) A printed item was obtained using the same printing method as that described above for the Δh value test. Following standing for 24 hours (1 day) after printing, 0.5 ml of water was dripped onto the solid image portion of the printed item, the level of bleeding was observed visually, and the water resistance was evaluated against the following criteria.

(77) A: no bleeding of the printed image portion.

(78) B: minor bleeding of the printed image portion, but not problematic in actual use.

(79) C: bleeding of the printed image portion, at a level problematic for actual use.

(80) (Average Particle Size of Colored Resin Particles)

(81) For each of the inks described above, the volume-based average particle size of the colored resin particles dispersed in the ink was measured using a dynamic light scattering particle size distribution analyzer “LB-500” (manufactured by Horiba, Ltd.).

(82) As is evident from the tables shown above, the ink of each example exhibited favorable results for all the evaluations, and furthermore, the average particle size of the colored resin particles also fell within an appropriate range.

(83) In Examples 2 and 3, the oxidation-reduction potential (ORP) was lower than that of Examples 1 and 4, and it is evident from the evaluation results for Δh and ΔE that the change in the color tone was less. The storage stability was also improved.

(84) Examples 5 and 6 used a different type of basic dispersant. The basic dispersant from Examples 5 and 6 exhibited a higher solubility in the solvent A.

(85) In Examples 5 and 6, the oxidation-reduction potential was lower, and it is evident from the evaluation results for Δh and ΔE that the change in the color tone was less. The storage stability was also improved.

(86) Examples 7 to 11 used different types of colorant.

(87) Regardless of which type of colorant was used, restricting the oxidation-reduction potential to 300 mV or less yielded favorable results for all the evaluations.

(88) In each of the comparative examples, the oxidation-reduction potential was high, and it is evident from the evaluation results for Δh and ΔE that the change in the color tone was much greater.

(89) It is to be noted that, besides those already mentioned above, many modifications and variations of the above embodiments may be made without departing from the novel and advantageous features of the present invention. Accordingly, all such modifications and variations are intended to be included within the scope of the appended claims.