Dispersion liquid, ink composition for ink jet recording, and dispersion resin

Abstract

A dispersion liquid includes water, a coloring material, and a dispersion resin that disperses the coloring material. The dispersion resin has a constituent unit A containing a hydrophobic monomer, and a predetermined constituent unit B.

Claims

1. A dispersion liquid comprising: water; a coloring material, wherein the coloring material is a disperse dye; and a dispersion resin that disperses the coloring material, wherein the dispersion resin has a constituent unit A containing a hydrophobic monomer and a constituent unit B represented by any one of the following formulae (1-1) and (1-2), ##STR00005## in the formulae, R.sup.1 independently represents a divalent organic group having 1 to 20 carbon atoms, and R.sup.2 independently represents a sulfonic acid group or a salt thereof.

2. The dispersion liquid according to claim 1, wherein the constituent unit A contains, as the hydrophobic monomer, one or more selected from the group consisting of styrene, -methylstyrene, allylbenzene, vinyltoluene, 1-vinylnaphthalene, and 2-vinylnaphthalene.

3. The dispersion liquid according to claim 1, wherein the constituent unit B is represented by formula (1-1).

4. The dispersion liquid according to claim 1, wherein the divalent organic group represented by R.sup.1 contains one or more selected from the group consisting of a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group.

5. The dispersion liquid according to claim 1, wherein the content of the constituent unit A is 40 to 85 mol % relative to the total amount of the dispersion resin.

6. The dispersion liquid according to claim 1, wherein the content of the constituent unit B is 15 to 60 mol % relative to the total amount of the dispersion resin.

7. The dispersion liquid according to claim 1, wherein the dispersion resin further has a constituent unit C represented by the following formula (2-1) ##STR00006##

8. The dispersion liquid according to claim 7, wherein the content of the constituent unit C is 0.5 to 15 mol % relative to the total amount of the dispersion resin.

9. The dispersion liquid according to claim 1, wherein the weight-average molecular weight of the dispersion resin is 5,000 to 30,000.

10. An ink composition for ink jet recording comprising: the dispersion liquid according to claim 1; a surfactant; and a water-soluble organic solvent.

Description

EXAMPLES

(1) The present disclosure is described in further detail below by using examples and comparative examples. The present disclosure is not limited to the examples below.

1. Synthesis Examples of Dispersion Resin

1. 1. Synthesis Example 1

(2) In a three-neck separable flask with a stirring bar and Dimroth condenser, 50 parts by mass of styrene-maleic anhydride copolymer containing a constituent unit A (Kawahara Petrochemical Co., Ltd., SMA3000P, styrene unit: 75 mol %, maleic anhydride unit: 25 mol %, weight-average molecular weight: 9,500), 60 parts by mass of sodium isethionate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 30 parts by mass of dimethylformamide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added. The inside of the system was heated to 100 C., and reaction was performed for 8 hours. After the completion of reaction, the reaction product was dropped in water to precipitate a white solid. The white solid was recovered by suction filtration, repeatedly washed with water, and then dried under vacuum at 50 C. for 10 hours, producing a copolymer. The resultant copolymer was used as a dispersion resin A.

1. 2. Synthesis Example 2

(3) A copolymer was produced by the same operations as in Synthesis Example 1 except that styrene-maleic anhydride copolymer (Kawahara Petrochemical Co., Ltd., SMA2000P, styrene unit: 66.6 mol %, maleic anhydride unit: 33.3 mol %, weight-average molecular weight: 7,500) was used in place of the styrene-maleic anhydride copolymer (SMA3000P). The resultant copolymer was used as a dispersion resin B.

1. 3. Synthesis Example 3

(4) A copolymer was produced by the same operations as in Synthesis Example 1 except that styrene-maleic anhydride copolymer (Kawahara Petrochemical Co., Ltd., SMA1000P, styrene unit: 50 mol %, maleic anhydride unit: 50 mol %, weight-average molecular weight: 5,500) was used in place of the styrene-maleic anhydride copolymer (SMA3000P). The resultant copolymer was used as a dispersion resin C.

1. 4. Synthesis Example 4

(5) A copolymer was produced by the same operations as in Synthesis Example 3 except that 80 parts by mass of p-phenolsulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used in place of 60 parts by mass of sodium isethionate. The resultant copolymer was used as a dispersion resin B.

(6) Table 1 shows the weight-average molecular weight Mw and the composition ratio of constituent units of the copolymer produced in each of the synthesis examples.

(7) TABLE-US-00001 TABLE 1 Constituent Constituent unit A Constituent unit B unit C Type mol % R.sup.1 R.sup.2 mol % mol % Mw Synthesis Styrene 75 Ethylene Sulfonate 23.8 1.2 11700 Example 1 group group Synthesis Styrene 66 Ethylene Sulfonate 32.3 1.7 9800 Example 2 group group Synthesis Styrene 50 Ethylene Sulfonate 47.5 2.5 8000 Example 3 group group Synthesis Styrene 50 Phenylene Sulfonate 47.5 2.5 9200 Example 4 group group

1. 5. NMR Analysis

(8) The composition ratio of the constituent units was confirmed by 1H-NMR analysis and 13C-NMR analysis. NMR analysis was performed by using a nuclear magnetic resonance apparatus (JNM-ECX400 manufactured by JEOL. Ltd.).

1. 6. Weight-Average Molecular Weight

(9) The weight-average molecular weight Mw of each of the dispersion resins was measured by chromatography. The conditions are shown below. Measurement conditions Apparatus name: HLC8320GPC (Tosoh Corporation) Guard column: Super AW-L Column: Super AW3000 Colum temperature: 25 C. Eluent: dimethylacetamide Flow rate: 0.6 mL/min Detector: RI

2. Preparation of Dispersion Liquid (Examples 1 to 4 and Comparative Example 1)

(10) A 1-L eggplant-shaped flask with a stirring bar and Dimroth condenser was set, and 15 parts by mass of each of the copolymers described in Table 1 and 70 parts by mass of pure water were added, heated to 80 C., and then stirred. Then, triethanolamine was added until the pH became 8.0, and pure water was further added up to 100 parts by mass. Then, the resultant mixture was cooled to 25 C., and the resultant aqueous solution was used as a varnish solution.

(11) Next, zirconia beads, 10 parts by mass of the varnish solution, 4 parts by mass of DISPERSE YELLOW 232 (also referred to as D. Y. 232 hereinafter) used as a water-insoluble coloring material, and 17 parts by mass of pure water were added and ground for 1 hour by a beads mill. Then, the zirconia beads were removed, and pure water was added up to 100 parts by mass, preparing a dispersion liquid containing 1.5 parts by mass of the copolymer and 4 parts by mass of the coloring material.

3. Preparation of Ink Composition

(12) The dispersion liquid was mixed with other components so as to obtain the composition shown in Table 2, preparing each of the ink compositions.

4. Evaluation

4. 1. Re-Dispersibility

(13) Five L of the ink composition prepared as described above was dropped on a slide glass and then solidified by drying for 16 hours in a dryer of 40 C. Then, the slide glass was dipped in a sample bottle containing ink water, and the re-dispersion behavior of a solid was confirmed by visual observation. This operation was performed with attention so that the ink water was neither stirred nor the like. The ink water represents not containing the coloring material and the dispersion resin shown in Table 2. The evaluation criteria of re-dispersibility are shown below.

(14) Evaluation Criteria

(15) A: The solid disappeared, and re-dispersion was observed. B: The solid partially remained, but re-dispersion was observed. C: The solid remained, and re-dispersion was not observed.

4. 2. Ejection Stability

(16) An ink jet-system printer EM-930C (trade name, manufactured by Seiko Epson Corporation) was filled with an ink composition for ink jet recording, and printing was continuously performed for 2 hours. A nozzle check pattern of nozzles used for printing was printed before and after printing to confirm the nozzles causing a deteriorating deviation of landing positions. In this case, the number of the nozzles was 180. The evaluation criteria are as follows. The evaluation result A or B can be determined as good.

(17) Evaluation Criteria

(18) A: The number of nozzles with a deteriorating deviation of the landing positions was 1% or less. B: The number of nozzles with a deteriorating deviation of the landing positions was over 1% and 5% or less. C: The number of nozzles with a deteriorating deviation of the landing positions was over 5%.

4. 3. Dry Ejection Characteristics

(19) An ink jet-system printer EM-930C (trade name, manufactured by Seiko Epson Corporation) was filled with an ink composition for ink jet recording, and an ejection head was removed from a suctioning cap and allowed to stand for 1 day. After allowing to stand, cleaning was performed once, and continuous printing was performed on 20 pages under ejection from all nozzles to determine the number of nozzles causing printing omission/bending based on the following criteria. The evaluation result A or B can be determined as good.

(20) Evaluation Criteria

(21) A: No nozzles causing omission/bending B: 1 to 5 nozzles causing omission/bending C: 6 or more nozzles causing omission/bending

(22) TABLE-US-00002 TABLE 2 Comparative Example Example 1 2 3 4 1 Coloring material 2.0 2.0 2.0 2.0 2.0 Dispersant Dispersion resin A 0.75 Dispersion resin B 0.75 Dispersion resin C 0.75 Dispersion resin D 0.75 SMA2000 0.75 pH adjuster Triethanolamine 0.5 0.5 0.5 0.5 0.5 Surfactant BYK348 0.5 0.5 0.5 0.1 0.1 Olfine E1010 0.5 0.5 0.5 0.5 0.5 Water- Propylene glycol 5.0 5.0 5.0 5.0 5.0 soluble Triethylene glycol 5.0 5.0 5.0 5.0 5.0 organic monobutyl ether solvent Glycerin 7.0 7.0 7.0 7.0 7.0 Diethylene glycol 5.0 5.0 5.0 5.0 5.0 Water Balance Balance Balance Balance Balance Total 100 100 100 100 100 Evaluation Re-dispersibility A A B A C Ejection stability A A A B C Dry rejection A B A B C property BYK-348: Silicone-based surfactant manufactured by BYK Chemie Co., Ltd. Olfine E1010: Acetylene glycol-based surfactant, manufactured by Nisshin Chemical Industry Co., Ltd.

(23) As described above, it is found that the ink compositions of the examples using the dispersion liquid of the present disclosure have excellent re-dispersibility, more improved dry ejection characteristics, and excellent ejection stability as compared with the comparative example.