JP2020056000A - Ink set - Google Patents

Abstract

To provide an ink set that allows a pigment contained in ink to flocculate without using polyvalent metal ions or cationic substance.SOLUTION: An ink set has an ink containing a pigment, a dispersant, and a first solvent, and a liquid containing a second solvent that can cause solvent shock when contacting the ink.SELECTED DRAWING: None

Description

  The present invention relates to an ink set.

  In recent years, there has been a shift from using dye inks to using pigment inks for the purpose of improving the weather resistance of ink-jet recorded materials. Further, there is an increasing demand for ink-jet recordings to have the same image quality as silver halide photographs, and there is an extremely high demand for increasing image density and improving image uniformity.

  Under such circumstances, various proposals have been made so far in order to improve the quality of the ink jet recorded matter.

  As one of proposals regarding a recording medium, a method of applying a filler or a sizing agent on the surface of a base paper has been proposed. For example, as a filler, there is a technique of coating a base paper with porous particles that adsorb a pigment to form an ink receiving layer. As a recording medium using these techniques, a coated paper for inkjet or the like is sold. ing.

  However, there is a high demand for forming an image equivalent to ink-coated paper or the like on so-called plain paper, which is relatively inexpensive and easily available, and many studies have been made.

  Patent Document 1 discloses an ink set for inkjet recording for performing white recording, an ink containing an inorganic oxide pigment and a resin as a dispersant, and a second liquid containing an aggregating agent for aggregating the inorganic oxide pigment. Are disclosed. Here, a polyvalent metal ion or a cationic substance is used as the coagulant.

  On the other hand, conventionally, in electrochemical devices such as lithium ion secondary batteries, electric double layer capacitors, lithium ion capacitors and redox capacitors, paper, nonwoven fabric, porous Film is used.

  In recent years, instead of these separators, separator-integrated electrodes in which a separator containing insulating particles is formed on an electrode have been used (for example, see Patent Documents 2 and 3).

  However, in the ink set of Patent Literature 1, there is a problem that the cost increases because the inorganic oxide pigment is aggregated by using a polyvalent metal ion or a cationic substance.

  Therefore, an object of the present invention is to provide an ink set that can aggregate pigments contained in ink without using a polyvalent metal ion or a cationic substance.

  One embodiment of the present invention, in an ink set, includes an ink including a pigment, a dispersant, and a first solvent, and a liquid including a second solvent capable of generating a solvent shock when contacted with the ink.

  ADVANTAGE OF THE INVENTION According to this invention, the ink set which can agglomerate the pigment contained in ink without using a polyvalent metal ion or a cationic substance can be provided.

It is a schematic diagram explaining a solvent shock. FIG. 1 is a perspective view illustrating a schematic configuration of an example of an inkjet printing apparatus. It is sectional drawing which shows schematic structure of an example of a separator integrated electrode.

  Hereinafter, embodiments for implementing the present invention will be described.

[Ink set]
The ink set according to an aspect of the present embodiment includes an ink including a pigment, a dispersant, and a first solvent, and a liquid including a second solvent capable of generating a solvent shock when contacted with the ink.

  In the present specification and the claims, the solvent shock refers to a solvent A and an ink containing a pigment B dispersed by a dispersant (see FIG. 1A) and a solvent A having a polarity (for example, HSP). By adding a solvent C having different values) to form a mixed solvent A + C, it means a phenomenon that the pigment B dispersed by the dispersant aggregates to form an aggregated pigment D (see FIG. 1B). Here, when the solvent C is added to the solvent A, the polarity of the mixed solvent A + C changes abruptly, so that the surface charge of the pigment B dispersed by the dispersant and the dispersant such as the three-dimensional structure of the dispersant are dispersed. It is presumed that the surface physical properties of Pigment B change rapidly. As a result, it is considered that the dispersion stability of the pigment B dispersed by the dispersant decreases, and the generation of the aggregated pigment D is promoted.

In the present specification and claims, the term "aggregation of pigments" means a phenomenon in which dispersed pigments associate with each other to increase the particle size. The aggregation of the pigment is remarkably observed in the particle diameter (D ₉₀ ) when the cumulative distribution is 90% by volume, as measured by laser scattering, dynamic light scattering, or the like.

D ₉₀ of the aggregate pigment D is, as compared with the pores of the porous body, if comparable size or larger, it is considered possible to inhibit the penetration into the porous body of agglomerated pigment D.

  The distance Ra between the HSP values of the first solvent and the second solvent is preferably 10 or more. When the distance Ra between the HSP value of the first solvent and the HSP value of the second solvent is 10 or more, the pigment contained in the ink is more easily aggregated. Note that the upper limit of the distance Ra between the HSP values of the first solvent and the second solvent is not particularly limited.

The HSP value is a solubility parameter of Hansen, energy δ _d [MPa ^0.5 ] due to intermolecular dispersive force, energy δ _p [MPa ^0.5 ] due to intermolecular dipole interaction, and hydrogen bonding between molecules. Δ _h [MPa ^0.5 ], which is a numerical value unique to each substance.

The distance Ra [MPa ^0.5 ] between the HSP values between the two substances is given by the formula (Ra) ² = 4 (δ _d2 −δ _d1 ) ² + (δ _p2 −δ _p1 ) ² + (δ _h2 ) −δ _h1 ) ²
Is required. Here, the subscripts 1 and 2 in δ _d , δ _p and δ _h mean that they are the first substance and the second substance, respectively.

  The second solvent preferably contains a hydroxyl group or an ester bond. Thereby, the pigment contained in the ink is more easily aggregated.

  Examples of the first solvent include dimethyl sulfoxide (DMSO), 1-methyl-2-pyrrolidone (NMP), ethyl lactate (EL), 2-butanone (MEK), butyl acetate, 2-heptanone, and ethyl hexanoate. Is mentioned.

  Examples of the second solvent include isopropyl alcohol (IPA), ethanol, n-butanol, ethyl acetate, butyl acetate, ethylene glycol (EG), propylene glycol (PG), hexylene glycol (HG), styrene, and dimethyl sulfoxide. (DMSO), water and the like.

  The pigment means a coloring material having low solubility in a solvent. Here, the solubility of the pigment in the solvent is usually less than 0.1% by mass.

  Specific examples of the material constituting the pigment include, for example, inorganic oxides such as carbon, calcium carbonate, calcium phosphate, aluminum oxide, silica, titanium oxide, silicon oxide, and zirconium oxide; and inorganic nitrides containing metals similar to metal oxides. Materials, inorganic materials such as metal sulfides, organic materials such as azo compounds, phthalocyanines, quinacridones, resin materials such as polystyrene, melanin resin, polyvinylidene fluoride (PVDF), polyvinylpyrrolidone (PVP), polypropylene, and polyethylene; And an organic-inorganic composite material combining the above. Among them, inorganic oxides such as aluminum oxide and silica are preferable because they have high insulation and heat resistance and can be used for manufacturing a separator-integrated electrode. Here, aluminum oxide can function as a scavenger for "junk" species, ie, species that cause capacity fade in lithium ion secondary batteries. In addition, since aluminum oxide has excellent wettability to the electrolyte, the absorption rate of the electrolyte increases, and the cycle performance of the lithium ion secondary battery can be improved.

  The median diameter of the pigment contained in the ink is preferably about 50 nm to about 1,000 nm, more preferably about 50 nm to about 800 nm, and particularly preferably about 100 nm to about 600 nm.

  Examples of the shape of the pigment include a rectangular shape, a spherical shape, an elliptical shape, a columnar shape, an egg shape, a dog bone shape, and an amorphous shape.

  The pigment may be in the form of a fiber.

  In the ink set of the present embodiment, the liquid may be ink. For example, the ink may include inorganic particles and the liquid may include resin particles, or vice versa. Further, the ink may include an inorganic pigment and resin particles, and the liquid may include an inorganic pigment and resin particles.

  The dispersant is not particularly limited as long as it can generate a solvent shock. For example, DISPERBYK-103, DISPERBYK-118, DISPERBYK-2155 (all manufactured by Big Chemie), NOPCOSPERSE-092, SN-SPERSE- 2190, SN-DISPERSANT-9228 (manufactured by San Nopco), ESREAM AD-3172M, ESREAM 2093, Marialim AKM-0513, Marialim HKM-50A, Marialim HKM-150A, Marialim SC-0505K, Marialim SC-1015F, Marialim SC- 0708A (all manufactured by NOF Corporation) and the like.

  When the second solvent is water, the dispersant is preferably a non-aqueous dispersant.

  The mass ratio of the dispersant to the pigment is usually from 0.01 to 10, preferably 0.1 to 10 in consideration of the dispersibility of the pigment, and in consideration of the liquid-collecting property of the separator-integrated electrode. , 0.1 to 1, and more preferably about 0.1 to 0.5.

  Ink is used for the purpose of adjusting viscosity, adjusting surface tension, controlling solvent evaporation, improving solubility of additives, improving dispersibility of pigments, disinfecting, etc., with a surfactant, a pH adjuster, a rust inhibitor, and a preservative. , A fungicide, an antioxidant, a reduction inhibitor, an evaporation promoter, a chelating agent, and the like.

  The ink can be manufactured using a known dispersing device. In addition, the liquid can be produced by using a known dispersing device, if necessary.

  Specific examples of the dispersing device include, for example, a stirrer, a ball mill, a bead mill, a ring mill, a high-pressure disperser, a rotary high-speed shearing device, and an ultrasonic disperser.

  The ink set of the present embodiment may have a plurality of inks or a plurality of liquids.

[How to use ink set]
The ink set of the present embodiment is used by applying ink and liquid substantially simultaneously to a medium to be coated. Therefore, the ink and the liquid come into contact with each other, and the mixed liquid of the ink and the liquid in which the pigment is aggregated is applied to the medium to be applied.

  Examples of the method of bringing the ink into contact with the liquid include a method of bringing the ink into contact with the adjacent ink, a method of dropping the liquid droplet on the ink droplet, and a method of placing the ink droplet on the liquid droplet. Dropping method and the like can be mentioned.

  Specific examples of the coating method include dip coating, spray coating, spin coating, bar coating, slot die coating, doctor blade coating, curtain coating, offset printing, gravure printing, flexographic printing, Examples include letterpress printing, screen printing, ink jet printing, and electrophotographic printing using a liquid developing method. Among them, the spray coating method and the ink jet printing method are preferable in that the ink and the liquid can be efficiently mixed, and the ink jet printing method is further preferable in that the position at which the droplet is ejected can be controlled. preferable.

  In the case of using the ink jet printing method, ink and liquid are ejected almost simultaneously from an ink jet type recording head, and a mixed liquid of ink and liquid in which a pigment is aggregated is printed on a medium to be coated.

  Examples of the method of discharging ink or liquid include a method of applying mechanical energy to the ink or liquid, a method of applying thermal energy to the ink or liquid, and the like. Among them, a method of applying mechanical energy to ink or liquid is preferable.

  In the case where an inkjet printing method is used, a known inkjet printing apparatus can be used.

  FIG. 2 shows a schematic configuration of an example of the inkjet printing apparatus.

  In the inkjet printing apparatus 11, a cartridge 20 in which ink and liquid are individually stored is stored in a carriage 18 in the main body housing 12. In this state, the ink and the liquid are supplied from the cartridge 20 to the recording head 18a mounted on the carriage 18, respectively. The recording head 18a can eject ink and liquid substantially simultaneously.

  The recording head 18a mounted on the carriage 18 moves while being guided by guide shafts 21 and 22 by a timing belt 23 driven by a main scanning motor 24. On the other hand, the medium to be coated is placed at a position facing the recording head 18a by the platen 19. In the figure, 16 indicates a gear mechanism, 17 indicates a sub-scanning motor, and 26 indicates a main scanning motor.

  The application medium is a medium (porous body) that can absorb a mixed liquid of ink and liquid.

  Specific examples of the medium to be coated include a medium in which an ink receiving layer is formed by applying porous particles to plain paper or base paper.

  When an electrode in which an electrode mixture layer containing an electrode active material is formed on an electrode substrate is used as a medium to be coated, a separator-integrated electrode can be manufactured.

  Examples of the negative electrode active material include a carbon material capable of absorbing or occluding lithium ions, such as lithium metal, a lithium alloy, carbon, and graphite, and a conductive polymer doped with lithium ions.

As the positive electrode active material, a general formula (CF _x ) _n
And metal oxides such as CoLiO ₂ , MnO ₂ , V ₂ O ₅ , CuO and Ag ₂ CrO ₄ , and metal sulfides such as TiO ₂ and CuS.

  FIG. 3 shows a schematic configuration of an example of the separator-integrated electrode.

  In the separator-integrated electrode 30, an electrode mixture layer 32 and a separator 33 are laminated in this order on an electrode substrate 31, and the ink set of the present embodiment is used when the separator 33 is formed.

  The use of the separator-integrated electrode 30 eliminates the need for separately winding and laminating the electrode and the separator when manufacturing an electrochemical device, thereby significantly improving the manufacturing efficiency of the electrochemical device. It is expected to be.

  Examples of the medium to be coated other than those described above include a base used for a reflective display element, an electrode layer used for printed electronics, and the like.

  EXAMPLES Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Note that “parts” and “%” are based on mass unless otherwise specified.

[D ₅₀ and D _{90 of} particles contained in the ink]
After dilution with the first solvent so that the solid content of the ink was 1% or less, the ink was ultrasonicated for 3 minutes using an ultrasonic homogenizer US-300T (manufactured by Nippon Seiki Seisakusho). Next, after diluting with the first solvent until the concentration becomes optically measurable, the volume-based median diameter (D) of the particles contained in the ink is measured using a laser diffraction particle size distribution analyzer Mastersizer 3000 (manufactured by Malvern). ₅₀ ) and the particle size (D ₉₀ ) when the cumulative distribution was 90% by volume.

[Example 1]
Using a bead mill Labostar mini LMZ015 (manufactured by Ashizawa), 31.5% of alumina particles, 67.555% of DMSO as a first solvent, and 0.945% of a dispersant were dispersed to prepare an ink. Incidentally, particles contained in the _{ink, D 50} is 0.5 [mu] _{m, D 90} was 0.9 .mu.m.

  IPA was used as the liquid (second solvent).

  An ink set was obtained by combining the ink and the liquid.

[Examples 2 to 6, Comparative Examples 1 to 3]
As the second solvent, ethanol (Example 2), n-butanol (Example 3), ethyl acetate (Example 4), butyl acetate (Example 5), water (Example 6), NMP (Comparative Example 1) ), 4-butyrolactone (Comparative Example 2), and MEK (Comparative Example 3), and an ink set was obtained in the same manner as in Example 1.

[Example 7]
An ink set was obtained in the same manner as in Example 1, except that NMP was used as the first solvent. Incidentally, particles contained in the _{ink, D 50} is 0.05 _{.mu.m, D 90} was 0.5 [mu] m.

[Examples 8, 9 and Comparative Examples 4 to 8]
As the second solvent, n-butanol (Example 8), water (Example 9), ethyl acetate (Comparative Example 4), butyl acetate (Comparative Example 5), DMSO (Comparative Example 6), MEK (Comparative Example 7) ) And EL (Comparative Example 8), except that an ink set was obtained in the same manner as in Example 7.

[Comparative Example 9]
An ink set was obtained in the same manner as in Example 1, except that EL was used as the second solvent.

[Example 10]
An ink set was obtained in the same manner as in Example 1, except that EL was used as the first solvent and PG was used as the second solvent. Incidentally, particles contained in the _{ink, D 50} is 0.5 [mu] _{m, D 90} was 1.0 .mu.m.

[Examples 11 to 13, Comparative Examples 10 to 14]
As the second solvent, EG (Example 11), styrene (Example 12), water (Example 13), IPA (Comparative Example 10), MEK (Comparative Example 11), ethyl acetate (Comparative Example 12), acetic acid An ink set was obtained in the same manner as in Example 10, except that butyl (Comparative Example 13) and HG (Comparative Example 14) were used.

[Example 14]
An ink set was obtained in the same manner as in Example 1, except that MEK was used as the first solvent and IPA was used as the second solvent. Incidentally, particles contained in the _{ink, D 50} is 0.5 [mu] _{m, D 90} was 1.0 .mu.m.

[Examples 15 to 18, Comparative Examples 15 to 17]
As the second solvent, PG (Example 15), EG (Example 16), HG (Example 17), water (Example 18), styrene (Comparative Example 15), NMP (Comparative Example 16), DMSO ( An ink set was obtained in the same manner as in Example 14, except that Comparative Example 17) was used.

[Example 19]
An ink set was obtained in the same manner as in Example 1, except that butyl acetate was used as the first solvent and IPA was used as the second solvent. Incidentally, particles contained in the _{ink, D 50} is 0.5 [mu] _{m, D 90} was 1.0 .mu.m.

[Examples 20 to 24, Comparative Example 18]
As the second solvent, DMSO (Example 20), EG (Example 21), PG (Example 22), HG (Example 23), water (Example 24), and EL (Comparative Example 18) were used. Except for the above, an ink set was obtained in the same manner as in Example 19.

[Example 25]
An ink set was obtained in the same manner as in Example 1, except that 2-heptanone was used as the first solvent and EG was used as the second solvent. Incidentally, particles contained in the _{ink, D 50} is 0.5 [mu] _{m, D 90} was 1.0 .mu.m.

[Examples 26 to 28, Comparative Examples 19 and 20]
Example 25 was repeated except that PG (Example 26), DMSO (Example 27), water (Example 28), NMP (Comparative Example 19), and HG (Comparative Example 20) were used as the second solvent. Similarly, an ink set was obtained.

[Example 29]
An ink set was obtained in the same manner as in Example 1, except that ethyl hexanoate was used as the first solvent and EG was used as the second solvent. Incidentally, particles contained in the _{ink, D 50} is 0.5 [mu] _{m, D 90} was 1.0 .mu.m.

[Examples 30 to 33, Comparative Examples 21 and 22]
As the second solvent, PG (Example 30), IPA (Example 31), HG (Example 32), DMSO (Example 33), NMP (Comparative Example 21), and styrene (Comparative Example 22) were used. Except for the above, an ink set was obtained in the same manner as in Example 29.

  Next, the aggregation of the pigment was evaluated using the ink set.

[Coagulation of pigment]
After mixing the ink and the liquid at a mass ratio of 1: 1 and then diluting with a mixed solvent so that the solid content becomes 1% or less, using an ultrasonic homogenizer US-300T (manufactured by Nippon Seiki Seisakusho) for more than 3 minutes Sonicated. Then, after diluting with a solvent mixture until the optical measurable concentrations, measured D ₉₀ of the particles contained in the liquid mixture of the ink and the liquid was evaluated flocculation of the pigment. Here, the mixed solvent is a solvent obtained by mixing the first solvent and the second solvent so as to correspond to the mass ratio of the ink and the liquid.

  The criteria for determining the cohesiveness of the pigment are shown below.

〇: 6 μm ≦ D90
Δ: 2 μm ≦ D90 <6 μm
×: D90 <2 μm
Table 1 shows the evaluation results of the cohesiveness of the pigment.

表１から、実施例１〜３３のインクセットは、顔料の凝集性が高いことがわかる。

Table 1 shows that the ink sets of Examples 1 to 33 have high pigment cohesiveness.

  On the other hand, in the ink sets of Comparative Examples 1 to 22, when the ink and the liquid come into contact with each other, the solvent shock does not occur, and thus the aggregation of the pigment is low.

In the ink sets of Examples 1 to 33, after the ink and the liquid were spray-applied almost simultaneously, the cross section was observed using SEM, and it was confirmed that the particles were aggregated. Here, when the ink and the liquid were spray-applied almost simultaneously, the basis weight was 0.5 mg / cm ² and the application amounts of the ink and the liquid were equal.

  In addition, in the ink sets of Comparative Examples 1 to 22, after the ink and the liquid were spray-applied almost simultaneously, the cross section was observed using an SEM. As a result, it was confirmed that no particles were aggregated.

JP 2007-223112 A JP 2000-277386 A JP 2006-173001 A

Claims (6)

An ink containing a pigment, a dispersant, and a first solvent;
An ink set comprising a liquid containing a second solvent capable of generating a solvent shock when contacted with the ink.   The ink set according to claim 1, wherein a distance Ra between the HSP value of the first solvent and the HSP value of the second solvent is 10 or more.   The ink set according to claim 1, wherein the second solvent contains a hydroxyl group or an ester bond.   The ink set according to any one of claims 1 to 3, wherein the first solvent or the second solvent contains water. The second solvent includes water,
The ink set according to any one of claims 1 to 4, wherein the ink contains a non-aqueous dispersant.   The ink set according to claim 1, which is used for manufacturing a separator-integrated electrode.

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