JP2017141388A - Ink for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink for inkjet recording having good storage stability, water resistance of a printed matter, and good discharge stability.SOLUTION: The ink for inkjet recording comprises: a coloring material; an antifoam agent selected from glycol-based or glycol ether-based compounds having a water-octanol distribution coefficient of 2.0 or more and 5.0 or less; a first solvent selected from glycol-based or glycol ether-based compounds having a water-octanol distribution coefficient of 0.0 or more and 2.0 or less; a glycol-based second solvent different from the first solvent; and resin particles having a zeta potential of -65 mV or more and -15 mV or less and having a polyoxyethylene chain.SELECTED DRAWING: None

Description

  The present invention relates to an inkjet recording ink.

  The ink jet recording method is a method of recording by ejecting small ink droplets from fine nozzles and attaching them to a recording medium. This method has a feature that a high-resolution and high-quality image can be recorded at a high speed with a relatively inexpensive apparatus.

  In the ink jet recording method, there are a large number of examination factors including the properties of ink used, the stability in recording, and the quality of the obtained image, and not only the ink jet recording apparatus but also the research on the ink to be used is active.

  For example, Patent Document 1 discloses an ink-jet ink that contains latex particles that are covalently bonded to a reactive surfactant and that contain a crosslinking agent, and is good for a recording medium by stably ejecting ink droplets. Attempts have been made to form images.

  Further, Patent Document 2 discloses a water-based ink containing a colorant / resin composite particle obtained by dispersing a molecular color former with a reactive dispersant and then polymerizing a resin. Attempts have been made to improve fixability and ink ejection stability.

  Further, Patent Document 3 discloses a water-insoluble organic polymer particle obtained by emulsion polymerization in the presence of a reactive surfactant and a log P value (logarithm of 1-octanol / water partition coefficient of an organic compound) of −1 to 11. An aqueous dispersion for inkjet recording containing a compound has been disclosed, and attempts have been made to improve printing density and marker resistance.

Special table 2006-520405 gazette JP 2003-128976 A JP 2006-282899 A

  In the techniques described in Patent Documents 1 to 3, latex particles, colorant / resin composite particles, or polymer particles are prepared by emulsion polymerization using a reactive surfactant or a reactive dispersant. Such particles have a function of improving the fixability of an image to be recorded. However, no antifoaming agent is added when the ink is formed using these latex particles or colorant / resin composite particles.

  Here, in the emulsion polymerization method, an emulsifier is essential at the time of polymerization, and the emulsifier after the polymerization remains in the system, so that the obtained aqueous dispersion has a tendency to easily foam. Then, when such an aqueous dispersion is used for ink for ink jet recording that intermittently ejects (sprays) droplets, for example, the ink easily foams due to a cleaning operation, and the generated bubbles are also eliminated. It becomes difficult to do. For this reason, minute bubbles are likely to be taken into the flow path of the recording head or the like, and the ink dischargeability may deteriorate.

  As a technique for making bubbles less likely to occur, it is conceivable to reduce the amount of the emulsifier during the polymerization of the resin particles. However, when the addition amount of the emulsifier during the emulsion polymerization is reduced in this way, the dispersibility of the resin particles becomes insufficient, and it becomes difficult to obtain storage stability when used in ink.

  Further, as a technique for making it difficult for bubbles to occur without reducing the emulsifier, it is conceivable to employ a reactive surfactant that can function as an emulsifier during the reaction, and to incorporate the emulsifier into the particles after polymerization. However, in order to reduce the remaining emulsifier, it is necessary to reduce the amount of unreacted (free) reactive surfactant, but the reaction yield (conversion rate) in the polymerization of the reactive surfactant is 100. % Is still difficult.

  Under such circumstances, it is considered to use an antifoaming agent as a technique to make it difficult to generate bubbles without reducing the amount of unreacted reactive surfactant or added emulsifier, and to easily break the generated bubbles. It is done. There are many types of antifoaming agents, and their materials and antifoaming mechanisms are diverse. In many cases, the antifoaming agent is highly hydrophobic, and depending on the combination, the dispersed state of the resin particles dispersed in water may be destroyed to generate an aggregate. When such an antifoaming agent is used, the aggregates may become a certain size or more, clogging the recording head and the ink flow path, which may cause ejection failure. Also, depending on the type of the antifoaming agent, the printed surface may be repelled, and if the antifoaming agent is selected without considering the combination with other materials in the ink, problems often occur.

  Patent Document 2 describes the use of an antifoaming agent, but there is no suggestion of specific materials or combinations thereof, and log P as described in Patent Document 2 is particularly used in ink for inkjet recording. The use of a water-insoluble organic compound having a value of about −1 to 11 as an antifoaming agent causes the resin particles and the colorant to aggregate from a combination with other materials in the ink, as with a highly hydrophobic antifoaming agent. There is concern.

  As described above, there are a large number of examination elements even considering only the storage stability and ejection stability of the ink for inkjet recording. In addition, there is a need for ink jet recording ink with a good balance including improvement in the quality of the obtained image.

  One of the objects according to some embodiments of the present invention is to provide an ink for ink jet recording having good storage stability, water resistance of printed matter, and good ejection stability.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

One aspect of the inkjet recording ink according to the present invention is as follows.
Color materials,
An antifoaming agent selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient of 2.0 to 5.0;
A first solvent selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient of 0.0 or more and 2.0 or less;
A glycol-based second solvent different from the first solvent;
Resin particles having a zeta potential of −65 mV to −15 mV and having a polyoxyethylene chain;
including.

  The ink for ink jet recording has a relatively high hydrophobicity (water-octanol distribution coefficient (log P) of 2.0 or more and 5.0 or less) and a relatively low hydrophobicity (water-octanol distribution). And a first solvent selected from glycol-based and glycol ether-based compounds having a coefficient of 0.0 or more and 2.0 or less, so that the defoaming agent has good solubilization and bubbles are suppressed, and the discharge Good stability. The ink for inkjet recording has a zeta potential of resin particles of −65 mV or more and −15 mV or less and has a polyoxyethylene chain. Therefore, it has dispersion stability due to the zeta potential and dispersion stability due to the second solvent having high affinity with the polyoxyethylene chain. Thereby, the resin particles hardly aggregate and the storage stability is good. Furthermore, since the ink for inkjet recording has at least a polyoxyethylene chain bonded to the resin particles by a covalent bond, the fixability and water resistance of the recorded matter are good.

In the inkjet recording ink according to the present invention,
You may contain the said 1st solvent 0.5 mass% or more and 15 mass% or less.

  Such an ink for ink jet recording can further solubilize the antifoaming agent and is more suitable for ink jet recording.

In the inkjet recording ink according to the present invention,
You may contain the said defoamer 0.005 mass% or more and 0.5 mass% or less.

  Such an ink for ink jet recording can sufficiently obtain an antifoaming effect by the antifoaming agent.

In the inkjet recording ink according to the present invention,
The second solvent may be selected from ethylene glycol, propylene glycol, 1,3-propanediol and multimers thereof.

  According to such an ink for ink jet recording, the second solvent has a high affinity with the polyoxyethylene chain of the resin particles, and further has good storage stability.

In the inkjet recording ink according to the present invention,
You may contain 2 mass% or more and 30 mass% or less of said 2nd solvent.

  Such an ink for ink jet recording has a better storage stability and is more suitable for ink jet recording.

In the inkjet recording ink according to the present invention,
The resin particles may have an anionic functional group.

  According to such an ink for ink jet recording, since the resin particles have two types of an anionic functional group and a polyoxyethylene chain, the dispersion is stabilized by the anionic functional group in a state where there is a lot of moisture, and the moisture is dried. When the solvent concentration is increased, the dispersion is stabilized by the affinity between the polyoxyethylene chain and the glycol-based second solvent. Thereby, for example, even when the ink for ink jet recording is dried near the nozzle of the recording head, it is difficult to solidify and re-ejection by a cleaning operation or the like is easy. Further, after printing, the second solvent permeates or evaporates and volatilizes into the recording medium and separates from the resin particles, so that deterioration of the water resistance of the recorded matter is suppressed.

In the inkjet recording ink according to the present invention,
You may use for the inkjet recording apparatus of a heat drying system.

  According to such an ink jet recording ink, in an ink jet recording apparatus in which the ink jet recording ink easily dries near the nozzle of the recording head, even when the ink jet recording ink dries near the nozzle of the recording head, it is difficult to solidify, The effect that re-ejection by a cleaning operation or the like is easy is remarkable.

In the inkjet recording ink according to the present invention,
The resin particles are synthesized by a polymerization method including emulsion polymerization using a monomer containing an anionic reactive emulsifier and subsequent emulsion polymerization using a monomer containing a reactive emulsifier having a polyoxyethylene chain. May be.

  According to such an ink for ink jet recording, since the polyoxyethylene chain of the resin particle is enriched in the outer shell of the resin particle, the glycol-based second solvent that is structurally similar to the polyoxyethylene chain includes: Furthermore, it is easily compatible with the polyoxyethylene chain of the resin particles, and further has good storage stability.

  Several embodiments of the present invention will be described below. Embodiment described below demonstrates an example of this invention. The present invention is not limited to the following embodiments, and includes various modified embodiments that are implemented within a range that does not change the gist of the present invention. Note that not all of the configurations described below are essential configurations of the present invention.

1. Ink for inkjet recording The ink for inkjet recording according to the present embodiment includes a color material, an antifoaming agent, a first solvent, a second solvent, and resin particles.

1.1. Color Material The ink for inkjet recording according to the present embodiment includes a color material. Examples of the color material include organic pigments, carbon black, oil-soluble dyes, and disperse dyes as color materials that are insoluble or hardly soluble in an aqueous solvent. Carbon black, organic pigments, oil-soluble dyes, and disperse dyes are more preferred because of good color development and low precipitation due to low specific gravity. In the ink for ink jet recording of the present embodiment, the color material may be dispersed by a dispersion resin. Further, as the coloring material, a water-soluble acid dye, a direct dye, a reactive dye, a basic dye, or the like may be used.

  Specific examples of carbon black include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, iron oxide, titanium oxide, zinc oxide, silica, and the like. . Further, as carbon black, No. manufactured by Mitsubishi Chemical Corporation. 2300, 900, MCF88, no. 20B, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B and the like. Color blacks FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pretex 35, U, V, 140U, Special Black 6, 5, 4A, 4, 250, etc. manufactured by Degussa. Examples thereof include CONDUCTEX SC manufactured by Columbia Carbon Co., Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, and the like. Examples include Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12 manufactured by Cabot Corporation. In addition, these are description of an example of suitable carbon black, and this invention is not limited by these. These carbon blacks may be used singly or as a mixture of two or more.

  Organic pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ansanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolo Examples include pyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

  Any oil-soluble dye or disperse dye can be used as long as it is a colorant that does not dissolve in the ink vehicle and can be dispersed. Azo, metal complex azo, anthraquinone, phthalocyanine, triallylmethane And the like.

  Specific examples of organic pigments used in ink jet recording inks include the following.

  Examples of cyan pigments include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15: 4, 15:34, 16, 22, 60, etc .; C.I. I. Bat blue 4, 60 and the like, preferably C.I. I. And one or a mixture of two or more selected from the group consisting of CI Pigment Blue 15: 3, 15: 4, and 60.

  Examples of magenta pigments include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, C.I. I. Pigment violet 19 and the like, preferably C.I. I. Pigment red 122, 202, and 209, C.I. I. Examples thereof include one or a mixture of two or more selected from the group consisting of CI Pigment Violet 19.

  Examples of the pigment used in the yellow ink jet recording ink include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc., preferably C.I. I. And one or a mixture of two or more selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, and 138.

  Examples of the pigment used in the orange inkjet recording ink include C.I. I. Pigment orange 36 or 43, or a mixture thereof. Examples of the pigment used in the green inkjet recording ink include C.I. I. And CI Pigment Green 7 or 36 or a mixture thereof.

  Examples of the dye that can be used in the inkjet recording ink of the present embodiment include disperse dyes and oil-soluble dyes. More specifically, examples of the disperse dye include C.I. I. Disperse thread 60, 82, 86, 86: 1, 167: 1, 279, C.I. I. Disperse yellow 64, 71, 86, 114, 153, 233, 245, C.I. I. Disperse Blue 27, 60, 73, 77, 77: 1, 87, 257, 367, C.I. I. Disperse violet 26, 33, 36, 57, C.I. I. Examples of oil-soluble dyes such as disperse orange 30, 41 and 61 include C.I. I. Solvent Yellow 16, 21, 25, 29, 33, 51, 56, 82, 88, 89, 150, 163, C.I. I. Solvent Red 7, 8, 18, 24, 27, 49, 109, 122, 125, 127, 130, 132, 135, 218, 225, 230, C.I. I. Solvent Blue 14, 25, 35, 38, 48, 67, 68, 70, 132, C.I. I. Solvent black 3, 5, 7, 27, 28, 29, 34 etc. are mentioned.

  As the dye, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid black 1, 2, 24, 94, etc. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Direct Black 19, 38, 51, 71, 154, 168, 195, C.I. I. Direct Blue 2, 3, 8, 10, 12, 31, 35, 63, 116, 130, 149, 199, 230, 231 and the like, such as C.I. I. Reactive Yellow 2, 7, 15, 22, 37, 42, 57, 69, 76, 81, 95, 102, 125, 135, C.I. I. Reactive Red 2, 14, 24, 32, 55, 79, 106, 111, 124, C.I. I. Reactive Blue 2, 13, 21, 38, 41, 50, 69, 72, 109, 120, 143, C.I. I. Reactive Black 3, 4, 5, 8, 13, 14, 31, 34, 35, 39, etc. I. Basic Yellow 1, 2, 13, 19, 21, 25, 32, 36, 40, 51, C.I. I. Basic Red 1, 5, 12, 19, 22, 29, 37, 39, 92, C.I. I. Basic Blue 1, 3, 9, 11, 16, 17, 24, 28, 41, 45, 54, 65, 66, C.I. I. Basic black 2, 8 etc. are mentioned.

  In the inkjet recording ink of the present embodiment, when the color material is dispersed with a dispersion resin, the ratio of the color material to the dispersion resin is preferably 10: 1 to 1:10, and more preferably 4: 1 to 1: 3. preferable. Further, the volume average particle diameter of the colorant at the time of dispersion is such that the maximum particle diameter when measured by a dynamic light scattering method is less than 500 nm and the average particle diameter is 300 nm or less, more preferably the average particle diameter is 200 nm or less. is there.

  The colorant may be used by dispersing a pigment using a dispersant selected from water-soluble resins, water-dispersible resins and surfactants, or may be colored by ozone, hypochlorous acid, fuming sulfuric acid, or the like. The surface of the material may be oxidized or sulfonated and used as a self-dispersing pigment.

  A color material may be used individually by 1 type and may use 2 or more types together. Furthermore, you may mix and use dye and a pigment.

  The content of the color material can be appropriately adjusted according to the use, but is preferably 0.10% by mass or more and 20.0% by mass or less, more preferably 0.20% by mass or more and 15.0% by mass. It is below, More preferably, they are 1.0 mass% or more and 10.0 mass% or less.

1.2. Antifoaming agent The ink for inkjet recording of this embodiment contains an antifoaming agent. In the present embodiment, the antifoaming agent is selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient (log P value) of 2.0 or more and 5.0 or less. From the viewpoint of the balance between the high defoaming effect and the high solubility in the ink, the log P value of the antifoaming agent is more preferably 2.3 or more and 4.5 or less, and 2.5 or more and 4.2 or less. Is more preferable.

  Here, the water-octanol partition coefficient, that is, the logP value, is a value defined by OECD Test Guideline 107. The higher the logP value, the higher the hydrophobicity, and the lower the logP value, the higher the hydrophilicity.

  One of the functions of the antifoaming agent in the present embodiment is to make it difficult for bubbles to be generated when the ink for ink jet recording is shaken, for example, in an ink container or a recording head. In addition, as one of the functions of the antifoaming agent, when bubbles are generated in the ink for inkjet recording, it is possible to easily eliminate the bubbles. In the present specification, these functions and actions may be referred to as an antifoaming effect. Due to the defoaming effect of the antifoaming agent, when the ink for ink jet recording is used in the ink jet recording apparatus, for example, it is difficult to clog the ink flow path of the recording head or the pressure applied to the ink for ink jet recording is reduced. Loss can be suppressed, and the ejection stability of ink for inkjet recording from the recording head can be improved.

  The antifoaming agent is not limited as long as it is selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient (log P value) of 2.0 or more and 5.0 or less. As a specific example, 3- (2- Ethylhexyloxy) -1,2-propanediol (log P: 2.53), 3-menthyloxy-1,2-propanediol (log P: 2.60), 2,4,7,9-tetramethyl-5- And decyne-4,7-diol (log P: 3.11) and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol (log P: 4.18). The log P value is indicated in the inside.). Moreover, you may use an antifoamer in mixture of multiple types.

  Note that a glycol-based compound is a compound having two hydroxyl groups (hydroxy groups), one at each of two carbon atoms of an aliphatic hydrocarbon or a cycloaliphatic hydrocarbon, or at least one of the hydrogen atoms of the compound. Is a compound having a group in which one becomes a bond. The number of hydroxy groups in the glycol compound may be 3 or more.

  The glycol ether compound is a compound having an ether structure in which the hydroxy group of a glycol compound is dehydrated and condensed with the hydroxy group of the same or another type of glycol compound. The number of ether groups (ether structure) of the glycol ether compound is not particularly limited.

  The blending amount of the antifoaming agent is 0.001% by mass or more and 1% by mass or less, preferably 0.003% by mass or more and 0.8% by mass or less, more preferably 0.005%, based on the total amount of the ink for inkjet recording. It is not less than 0.5% by mass. When the blending amount of the antifoaming agent is within this range, the defoaming effect in the ink jet recording ink can be sufficiently obtained.

1.3. First Solvent The ink for inkjet recording of the present embodiment contains a first solvent. The first solvent is selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient of 0.0 or more and 2.0 or less. The log P value of the first solvent is more preferably 0.01 or more and 1.9 or less, and further preferably 0.02 or more and 1.7 or less.

  One of the functions of the first solvent is to solubilize the antifoaming agent. The above-mentioned antifoaming agent is a glycol-based and glycol ether-based compound having a log P value of 2.0 or more and 5.0 or less, and has a relatively high hydrophobicity. On the other hand, the first solvent is a glycol-based or glycol ether-based compound having a log P value of 0.0 or more and 2.0 or less, and as shown by the log P value, is less hydrophobic and more water-soluble than an antifoaming agent. is there. In the ink for ink jet recording of this embodiment, the antifoaming agent that is relatively difficult to dissolve due to relatively high hydrophobicity is easily dissolved by the first solvent having relatively low hydrophobicity. That is, the 1st solvent has the function to make an antifoamer and water make affinity. Therefore, the first solvent also has a function of increasing the amount of the antifoaming agent added to the ink jet recording ink. Furthermore, in this embodiment, since the first solvent is a glycol-based or glycol ether-based compound, the affinity of the resin particles (described later) with the polyoxyethylene chain is high, and the first solvent suppresses aggregation of the resin particles. It also has a function to do.

  The first solvent is not limited as long as it is selected from glycol and glycol ether compounds having a log P value of 0.0 or more and 2.0 or less, but 1,2-pentanediol (log P: 0.01), butyl triglycol (Triethylene glycol monobutyl ether) (log P: 0.02), butyl diglycol (diethylene glycol monobutyl ether) (log P: 0.56), dipropylene glycol monopropyl ether (log P: 0.60), 1,2- Hexanediol (log P: 0.70), 1,2-heptanediol (log P: 1.0), 2-methyl-3-phenoxy-1,2-propanediol (log P: 1.10), 3- (3 -Methylphenoxy) -1,2-propanediol (log P: 1.21), 3-he Siloxy-1,2-propanediol (log P: 1.36), 2-hydroxymethyl-2-phenoxymethyl-1,3-propanediol (log P: 1.69) and the like (log P in parentheses) Values are listed.) Moreover, you may use a 1st solvent in mixture of multiple types.

  The blending amount of the first solvent is 0.2% by mass or more and 30% by mass or less, preferably 0.4% by mass or more and 20% by mass or less, more preferably 0.5% by mass with respect to the total amount of the ink for inkjet recording. It is 15 mass% or less, More preferably, it is 0.7 mass% or more and 10 mass% or less. If the blending amount of the first solvent is within this range, the antifoaming agent can be sufficiently solubilized and the aggregation of the resin particles can be suppressed, and the ink for ink jet recording is more suitable for the ink jet recording apparatus. It can be.

1.4. Second Solvent The ink for ink jet recording of the present embodiment contains a second solvent. The second solvent is a glycol-based compound different from the first solvent. That is, the second solvent is a glycol-based compound having a log P value of less than 0.0, preferably less than 0.01, more preferably less than 0.02, or more than 2.0, preferably The compound is more than 1.9, more preferably more than 1.7. The second solvent is a glycol-based compound, and is more preferably a compound having a log P value of less than 0.02 from the viewpoint of solubility in water.

  One of the functions of the second solvent is to make the first solvent compatible with water. Moreover, the ink for inkjet recording of this embodiment can raise the compounding quantity of a 1st solvent by containing a 2nd solvent, Furthermore, the compounding quantity of an antifoamer can also be raised. Further, in this embodiment, since the second solvent is a glycol compound, the resin particles (described later) have high affinity with the polyoxyethylene chain, and the second solvent also has a function of suppressing aggregation of the resin particles. doing.

  Specific examples of the second solvent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol, 1,3-propanediol, 1,2- Examples include glycols such as butanediol, 1,2-pentanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. Among these, the second solvent is ethylene glycol, propylene glycol, 1,3-propanediol and its multimer (for example, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol). Etc.). A 2nd solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The blending amount of the second solvent is 0.2% by mass or more and 30% by mass or less, preferably 0.4% by mass or more and 20% by mass or less, more preferably 0.5% by mass with respect to the total amount of the ink for inkjet recording. It is 15 mass% or less, More preferably, it is 0.7 mass% or more and 10 mass% or less. If the blending amount of the first solvent is within this range, the solubility of the first solvent can be increased, whereby the antifoaming agent can be further sufficiently solubilized and the aggregation of the resin particles can be suppressed. Can do.

1.5. Resin Particles The ink for ink jet recording of the present embodiment contains resin particles. The resin particles have a zeta potential of −65 mV to −15 mV and have a polyoxyethylene chain. From the viewpoint of resin particle dispersibility (aggregation inhibition) and the storage stability of the ink accompanying these, the zeta potential is more preferably from −60 mV to −20 mV, and even more preferably from −55 mV to −25 mV.

  Here, the zeta potential refers to an electrokinetic potential and is an index indicating a potential difference at the interface between the resin particles and the medium. The zeta potential can be exhibited by a method such as electroosmosis or electrophoresis. The zeta potential can be measured by, for example, a commercially available measuring device such as Zeta Sizer Nano ZS (trade name: manufactured by Malven Instruments Ltd.).

  One of the functions of the resin particles is to fix (fix) the color material to the recording medium. The resin particles are in the form of particles in the ink for ink jet recording, and as a result, the viscosity of the ink for ink jet recording can be kept lower than when the fixing resin is blended as a solution.

  The resin particles can be directly synthesized as a dispersion by emulsion polymerization or suspension polymerization using an addition polymerization monomer. The mode of emulsion polymerization or suspension polymerization is not particularly limited, and all monomers used for polymerization are mixed to prepare a monomer composition in an emulsion state, and this is added dropwise to an initiator solution. It is possible to divide the type and / or amount into a plurality of methods to prepare a plurality of monomer compositions in an emulsified state and add them dropwise to the initiator solution. Through the polymerization reaction, the monomers are covalently bonded to each other to become a polymer (polymer), which takes a particulate form.

  Monomers used for polymerization include acrylic acid esters such as methyl acrylate and ethyl acrylate, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, vinyl acetate, ethylene, propylene, isobutylene, butadiene, styrene, methyl styrene, and chloride. A compound having a carbon-carbon double bond such as vinyl, maleic anhydride, or divinylbenzene can be used.

  Moreover, the polyoxyethylene chain of the resin particle of this embodiment is introduce | transduced by using the reactive emulsifier which has a polyoxyethylene chain as a monomer. Examples of the reactive emulsifier having a polyoxyethylene chain include compounds containing a polyoxyethylene chain and a carbon-carbon double bond such as polyoxyalkylene alkenyl ether, alkoxy polyethylene glycol methacrylate, and alkoxy polyethylene glycol methacrylate. Specific examples of reactive emulsifiers include Latemul PD-420, Latemuru PD-430, Latemuru PD-430S (above trade name: Kao Corporation), Aqualon RN (trade name: Daiichi Kogyo Seiyaku Co., Ltd.), Anne Tox LMA-10, Antox LMA-20, Antox LMA-27 (above trade name: Nippon Emulsifier Co., Ltd.) and the like can be mentioned.

  Moreover, although the resin particle of this embodiment has a zeta potential of −65 mV or more and −15 mV or less, such a zeta potential indicates that the resin particle is negatively charged.

  As a method for imparting such a zeta potential to the resin particles, an anionic group may be bonded to the resin particles. Such an anionic group is not particularly limited, and examples thereof include a carboxyl group, a sulfonic acid group, and a phosphoric acid group.

  As a method for bonding an anionic group to a resin particle, a compound containing an anionic group and a carbon-carbon double bond is blended as a monomer and emulsion polymerization is performed. Such a monomer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, and salts thereof. Furthermore, an anionic reactive emulsifier may be blended as a monomer as a technique for bonding an anionic group to the resin particles.

  Examples of anionic reactive emulsifiers include polyoxyalkylene alkenyl ether ammonium sulfate, ether sulfate type ammonium, phosphate ester, bis (polyoxyethylene polycyclic phenyl ether) methacrylate sulfate ester, 2-sodium sulfoethyl methacrylate, alkoxy Examples thereof include polyethylene glycol maleate esters and salts thereof.

  Specific examples of the anionic reactive emulsifier include Latemul PD-104, Latemuru PD-105 (trade name: manufactured by Kao Corporation), Aqualon KH, Aqualon HS, Aqualon BC (all trade names: Daiichi Kogyo Seiyaku Co., Ltd.) Made by company), Eleminol JS-20, Eleminol RS-3000 (trade name: Sanyo Kasei Kogyo Co., Ltd.), Adeka Soap SR-10, Adeka Soap SR-20, Adeka Soap SE-10N, Adeka Soap PP-70 (above trade name: manufactured by ADEKA Corporation), Antox MS-60, Antox MS-2N, Antox EMH-20 (above trade name: manufactured by Nippon Emulsifier Co., Ltd.) and the like can be mentioned.

  When a reactive emulsifier having both an anionic functional group and a polyoxyethylene chain, such as polyoxyalkylene alkenyl ether ammonium sulfate, is used as a monomer, the polyoxyethylene chain and the anionic functional group are added to the resin particles. Both of them can be introduced by one polymerization, and a resin particle having a zeta potential of −65 mV to −15 mV and having a polyoxyethylene chain may be more easily synthesized.

  The polymerization initiator for emulsion polymerization or suspension polymerization is not particularly limited, but water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, and dibutyl peroxide are preferable. .

  Thus, when the resin particle has an anionic functional group, it has two types of functional groups, an anionic functional group and a polyoxyethylene chain. In the state where the moisture is dried and the solvent concentration is increased, the dispersion is stabilized by the affinity between the polyoxyethylene chain and the glycol-based second solvent. Thereby, for example, even when the ink for ink jet recording is dried near the nozzle of the recording head, it is difficult to solidify and re-ejection by a cleaning operation or the like is easy. Further, after printing, the second solvent permeates or evaporates and volatilizes into the recording medium and separates from the resin particles, so that deterioration of the water resistance of the recorded matter is suppressed.

  Generally, in emulsion polymerization or suspension polymerization, an emulsifier having no reactivity (surfactant) is added in order to emulsify or suspend the monomer. In that case, after completion of the polymerization reaction, the emulsifier remains in the system in a free state. In many cases, the emulsion or suspension thus formed tends to foam easily.

  On the other hand, in the emulsion polymerization or suspension polymerization, when the above-described reactive emulsifier is used, the compound that can be emulsified or suspended before and during the polymerization, and also functions as an emulsifier as the polymerization reaction proceeds. (Reactive emulsifier) will decrease. Therefore, when the polymerization reaction is completed, the amount of the emulsifier (reactive emulsifier) remaining in the system in a free state can be sufficiently reduced. The emulsion or suspension thus formed is less likely to produce bubbles. The group that functions as an emulsifier is bonded to the resin particles, and even if the amount of the emulsifier (reactive emulsifier) remaining in the system is small, the dispersibility of the resin particles is not greatly impaired. Even when a reactive emulsifier is used as a monomer, polymerization can be carried out in the presence of a non-reactive emulsifier in order to supplement the emulsifying power. In this case, the amount of the emulsifier can be reduced. Furthermore, in emulsion polymerization or suspension polymerization, it can also superpose | polymerize in coexistence of a chain transfer agent, an oligomer, and a macromer.

  Thus, the resin particles may be synthesized by emulsion polymerization using a monomer containing both an anionic reactive emulsifier and a reactive emulsifier having a polyoxyethylene chain. The resin particles are sequentially subjected to emulsion polymerization using a monomer composition containing an anionic reactive emulsifier and emulsion polymerization using a monomer composition containing a reactive emulsifier having a polyoxyethylene chain. May be synthesized.

  In the case of synthesizing resin particles by sequential polymerization, the emulsion polymerization using a monomer composition containing an anionic reactive emulsifier is performed first, and then the reactive emulsifier having a polyoxyethylene chain is added. It may be synthesized by a polymerization method including carrying out emulsion polymerization using the monomer composition.

  When the resin particles are formed by such a polymerization method, the polyoxyethylene chains of the resin particles are easily enriched in the outer shell of the resin particles. Therefore, the glycol-based second solvent that is structurally similar to the polyoxyethylene chain is likely to have an affinity for the polyoxyethylene chain of the resin particles, and can further improve the storage stability of the ink for ink jet recording.

  When synthesizing resin particles by sequential polymerization, a monomer containing a reactive emulsifier having a polyoxyethylene chain after emulsion polymerization using a monomer containing an anionic reactive emulsifier is advanced to a conversion rate of 100%. The emulsion polymerization used may be performed, and the emulsion polymerization using the monomer including the preceding anionic reactive emulsifier includes the subsequent reactive emulsifier having a polyoxyethylene chain before the conversion reaches 100%. Emulsion polymerization using monomers may be performed. It may take a reaction time or may be difficult to make the emulsion polymerization using a monomer containing a preceding anionic reactive emulsifier a conversion rate of 100%. Therefore, at the start of emulsion polymerization using a monomer containing a reactive emulsifier having a subsequent polyoxyethylene chain, the monomer in the system includes both an anionic reactive emulsifier and a reactive emulsifier having a polyoxyethylene chain. May coexist. By performing such sequential emulsion polymerization, the polyoxyethylene chains of the resin particles can be concentrated on the surface side of the resin particles.

  The compounding amount of the reactive emulsifier when synthesizing the resin particles is 0.5% by mass or more and 5% by mass or less, preferably 1% by mass or more and 4% by mass or less, based on 100% by mass of all monomers. Preferably they are 1.5 mass% or more and 3 mass% or less, More preferably, they are 2 mass% or more and 2.5 mass% or less. Further, even when sequential polymerization is performed, the amount of the reactive emulsifier used when synthesizing the resin particles is preferably within the above range in the total amount of monomers used for each polymerization reaction.

  In addition, the amount (solid content) of the resin particles in the ink for ink jet recording is 0.5% by mass or more and 20% by mass with respect to the total mass of the ink for ink jet recording as a total amount, including the case where a plurality of types are used. Preferably, the content is 1% by mass or more and 15% by mass or less, more preferably 5% by mass or more and 15% by mass or less. When the content of the resin particles is 0.5% by mass or more, the adhesion of the inkjet recording ink to the recording medium is further improved. Further, when the content of the resin particles is 20% by mass or less, the ejectability of the ink for ink jet recording from the recording head tends to be good.

  Moreover, the volume-based average particle diameter of the resin particles of this embodiment is 100 nm or more and 500 nm or less, preferably 150 nm or more and 400 nm or less, more preferably 200 nm or more and 300 nm or less. Such a particle diameter can be appropriately set according to various conditions (stirring conditions, temperature, etc.) during emulsion polymerization, for example. The volume-based average particle diameter of the resin particles can be measured by, for example, a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. Examples of the particle size distribution measuring apparatus include a particle size distribution meter (for example, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle.

1.6. Water The ink for ink jet recording according to this embodiment contains water. Examples of water include water from which ionic impurities have been removed as much as possible, such as pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, and distilled water, and ultrapure water. Further, when water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, generation of bacteria and fungi can be prevented when the ink for inkjet recording is stored for a long period of time.

The water content is 30% by mass or more, preferably 40% by mass or more, more preferably 45% by mass or more, and further preferably 50% by mass or more, based on the total amount of the ink for inkjet recording. The water in the ink for inkjet recording includes, for example, a pigment dispersion used as a raw material, a resin particle dispersion, and water to be added. When the water content is 30% by mass or more, the inkjet recording ink can have a relatively low viscosity. Further, the upper limit of the water content is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less with respect to the total amount of the ink for inkjet recording. In the present specification, the term “water-based ink” refers to an ink containing 30% by mass or more of water with respect to the total mass (100% by mass) of the ink.
1.7. Other Components The ink for inkjet recording of the present embodiment may contain components such as a humectant, a surface tension adjuster, and a pH adjuster.

1.7.1. Humectant The ink for ink jet recording of the present embodiment may contain a humectant. The humectant is not particularly limited and can be used as long as it is generally used for ink jet ink jet recording. The boiling point of the humectant is preferably 180 ° C. or higher, and more preferably 200 ° C. or higher. When the boiling point is within the above range, good water retention and wettability can be imparted to the ink for inkjet recording.

  Specific examples of the humectant include diethylene glycol, triethylene glycol, tetraethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, and 2-methyl. -2,4-pentanediol, tripropylene glycol, isobutylene glycol, glycerin, diglycerin, mesoerythritol, trimethylolpropane, pentaerythritol, dipentaerythritol and other polyols, 2-pyrrolidone, N-methyl-2-pyrrolidone, Lactams such as ε-caprolactam and hydroxyethylpyrrolidone, urea derivatives such as urea, thiourea, ethyleneurea and 1,3-dimethylimidazolidinone, glucose, mannose, fructose, ribond , Monosaccharides such as xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, disaccharides, oligosaccharides and polysaccharides and derivatives of these saccharides, glycine, Examples include betaines of trimethylglycine.

  Of the humectants exemplified above, polyols (glycol compounds) that are different from the first solvent described above are classified as the second solvent.

  The blending amount when the moisturizing agent is blended with the ink for ink jet recording of the present embodiment is 0.2% by mass or more and 30% by mass or less, preferably 0.4% by mass or more with respect to the total amount of the ink for ink jet recording. It is 20 mass% or less, More preferably, it is 0.5 mass% or more and 15 mass% or less, More preferably, it is 0.7 mass% or more and 10 mass% or less.

1.7.2. Surface Tension Adjusting Agent The ink for ink jet recording of the present embodiment may contain a surface tension adjusting agent. The surface tension adjuster is used to adjust the wettability of the ink to the printing substrate and discharge flow path by reducing the surface tension when dissolved in water, and is selected from water-soluble solvents and surfactants with low surface tension. It is. Examples of the water-soluble solvent system include lower alcohols such as ethanol, propanol and butanol, diols such as butylene glycol, 1,3-pentanediol, 2-ethyl-1,3-propanediol and 1,6-hexanediol. And glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether.

  Among the water-soluble solvent-based surface tension modifiers exemplified above, diols (glycol compounds) or glycol monoethers (glycol ether compounds), and log P values of 0.0 or more and 2.0 or less. Are classified as the first solvent, and are diols (glycol compounds), and those different from the first solvent described above are classified as the second solvent.

  As the surfactant system, for example, a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant can be appropriately selected. Of these, acetylene glycol surfactants and silicone surfactants having high surface activity and low foaming properties are more preferred.

  Although it does not specifically limit as an acetylene glycol type surfactant, For example, Olfin E1004, E1010, E1020, PD-001, PD-002W, PD-004, PD-005, EXP. 4200, EXP. 4123, EXP. 4300 (trade name: manufactured by Nissin Chemical Industry Co., Ltd.), Surfinol 440, 465, 485, CT111, CT121, TG, GA, Dynol 604, 607 (trade name: Air Products Japan, Inc.) )), Acetylenol E40, E60, E100 (product names: manufactured by Kawaken Fine Chemical Co., Ltd.), E series such as Olfine 104 series and Olfine E1010 (trade name: manufactured by Air Products Japan, Inc.) And Surfynol 465 (trade name: manufactured by Nissin Chemical Industry CO., Ltd.).

  Examples of silicone surfactants include polysiloxane compounds and polyether-modified organosiloxanes. Although it does not specifically limit as a commercial item of a silicone type surfactant, Specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK -348, BYK-349 (trade name: manufactured by Big Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640 , KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012 (above trade names: manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG002, 005, 503A, 008 (above Product name: manufactured by Nissin Chemical Industry Co., Ltd.).

1.7.3. pH adjuster The ink for inkjet recording of the present embodiment may contain a pH adjuster for the purpose of adjusting the pH. Although it does not specifically limit as a pH adjuster, For example, sulfuric acid, hydrochloric acid, nitric acid, etc. as an inorganic acid, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc. as an inorganic base, triethanolamine, diethanolamine as an organic base Monoethanolamine, triisopropanolamine, diisopropanolamine, trishydroxymethylaminomethane, and organic acids such as adipic acid, citric acid, succinic acid, and lactic acid.

1.7.4. Other Components The ink for ink jet recording according to the present embodiment maintains its storage stability and ejection stability from the head, is for improving clogging, or for preventing deterioration of the ink for ink jet recording. In addition, various additives such as preservatives, dissolution aids, viscosity modifiers, antioxidants, antifungal agents, and chelating agents for capturing metal ions that affect dispersion can be added as appropriate. .

1.8. Effect The ink for ink jet recording according to the present embodiment has a relatively high hydrophobicity (water-octanol partition coefficient (logP) is 2.0 or more and 5.0 or less) and an antifoaming agent that is relatively hydrophobic. A low solvent (water-octanol partition coefficient is 0.0 or more and 2.0 or less) and a first solvent selected from glycol-based and glycol ether-based compounds, so that the defoaming agent has good solubilization, Air bubbles are suppressed and ejection stability is good. Moreover, the ink for inkjet recording of this embodiment has a zeta potential of resin particles of −65 mV or more and −15 mV or less, and has a polyoxyethylene chain. Therefore, it has dispersion stability due to the zeta potential and dispersion stability due to the second solvent having high affinity with the polyoxyethylene chain. Thereby, the resin particles hardly aggregate and the storage stability is good. Furthermore, since the ink for inkjet recording of this embodiment has at least a polyoxyethylene chain bonded to the resin particles by a covalent bond, the fixing property and water resistance of the recorded matter are good.

2. Inkjet recording apparatus The inkjet recording ink of the present embodiment can be suitably used in an inkjet recording apparatus. The ink jet recording apparatus has at least an ink container (cartridge, tank, etc.) for storing the ink for ink jet recording described above and a recording head connected to the ink container, and performs recording by discharging the ink for ink jet recording from the recording head. There is no particular limitation as long as an image can be formed on the medium.

  As the ink jet recording apparatus of this embodiment, either a serial type or a line type can be used. These types of ink jet recording apparatuses are equipped with a recording head, and droplets of ink for ink jet recording are predetermined from nozzle holes of the recording head while changing the relative positional relationship between the recording medium and the recording head. (Intermittently) and at a predetermined volume (mass), and a predetermined image can be formed by adhering ink jet recording ink to a recording medium.

  In general, in a serial type ink jet recording apparatus, the recording medium conveyance direction and the reciprocation direction of the recording head intersect, and the reciprocation operation of the recording head and the recording medium conveyance operation (including the reciprocation operation) The relative positional relationship between the recording medium and the recording head is changed by the combination. In this case, generally, a plurality of nozzle holes (holes for ejecting ink for ink jet recording) are arranged in the recording head, and an array of nozzle holes (nozzle array) is formed along the conveyance direction of the recording medium. ing. Also, a plurality of nozzle rows may be formed on the recording head depending on the type and number of ink jet recording inks.

  In general, in a line-type ink jet recording apparatus, the recording head does not reciprocate, and the relative positional relationship between the recording medium and the recording head is changed by conveying the recording medium, so that the recording medium and the recording head Change the relative positional relationship. Also in this case, generally, a plurality of nozzle holes are arranged in the recording head, and the nozzle hole array (nozzle array) is formed along the direction intersecting the recording medium conveyance direction.

  The ink jet recording method uses a serial type or line type ink jet recording apparatus as described above, but the method is to eject the ink for ink jet recording as a droplet from a fine nozzle hole and record the droplet. There is no particular limitation as long as it can be attached to the medium. For example, the ink jet recording method includes an electrostatic suction method, a method of ejecting ink droplets by pump pressure, a method of using a piezoelectric element, a method of heating and foaming an ink liquid with a microelectrode, and ejecting ink droplets, and the like. it can.

  For the ink jet recording apparatus used in the present embodiment, for example, known configurations such as a heating unit, a drying unit, a roll unit, and a winding device can be employed without limitation.

  In an aspect in which the ink jet recording apparatus includes a heating unit, the heating unit heats the ink (image) for ink jet recording in the recording head, the recording medium, and / or the recording medium at least during image formation and after image formation. can do. Thereby, the liquid medium (specifically, water, alkyl polyol, glycol ether, etc.) contained in the ink for ink jet recording deposited on the recording medium can be quickly evaporated. Thereby, a high-quality image can be obtained in a short time even on the recording medium. The heating unit may be a unit that heats the ink jet recording ink in the recording head for the purpose of reducing the viscosity of the ink jet recording ink. Thereby, the aspect which improves the discharge property by reducing the viscosity of the ink for inkjet recording may be sufficient. As specific heating means, forced air heating, radiation heating, conductive heating, high-frequency drying, microwave drying, or the like is preferably used.

  The ink for ink jet recording according to the present embodiment can be suitably used for an ink jet recording apparatus, but has an excellent effect particularly in an ink jet recording apparatus including a heating unit (of a heat drying method).

  That is, when the ink jet recording apparatus includes a heating unit, the ink for ink jet recording near the nozzle holes of the recording head may be dried by heating the recording head or the recording medium. In this case, the ink jet recording ink usually becomes highly viscous or solidified due to aggregation of the resin and clogs the nozzle holes.

  On the other hand, in the ink for ink jet recording of the above embodiment, the zeta potential of the resin particles is −65 mV or more and −15 mV or less and has a polyoxyethylene chain. For this reason, the dispersibility of the resin particles is stabilized mainly by the effect of a specific range of zeta potential in a state where there is a lot of moisture, and in the state where the concentration of the solvent is increased by drying the moisture, the affinity between the polyoxyethylene chain and the second solvent is mainly used. The dispersibility of the resin particles can be stabilized depending on the properties. As a result, even if the drying progresses to a certain extent, the resin is less likely to agglomerate and the ink for inkjet recording from the nozzle holes can be easily re-discharged. After printing, the second solvent permeates or evaporates and volatilizes into the recording medium and separates from the resin particles, so that the water resistance and fixability of the recorded matter are sufficiently ensured.

3. Examples and Comparative Examples Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

3.1. Preparation of resin particle dispersion 3.1.1. Resin particle dispersion 1
50 g of methyl methacrylate as a monomer, 100 g of 2-ethylhexyl methacrylate, 3.5 g of Eleminol RS-3000 (trade name: manufactured by Sanyo Kasei Kogyo Co., Ltd.) as an anionic reactive emulsifier and 100 g of ion-exchanged water are mixed with a homomixer Monomer emulsion 1 was prepared.

  100 g of methyl methacrylate as the monomer, 50 g of 2-ethylhexyl methacrylate, 1 g of methacrylic acid, 3.5 g of Antox LMA-10 (trade name: manufactured by Nippon Emulsifier Co., Ltd.) as the polyoxyethylene-based reactive agent emulsifier A monomer emulsion 2 was prepared by mixing 100 g with a homomixer.

  An initiator solution in which 0.5 g of ammonium persulfate was dissolved in 20 g of ion-exchanged water as a polymerization initiator was prepared.

  Next, a reactor equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and three dropping funnels was charged with 150 g of ion-exchanged water, 0.2 g of sodium bicarbonate and 50 g of monomer emulsion 1, Stirring was performed at 80 ° C. for 30 minutes while ventilating nitrogen. Subsequently, the initiator solution is charged from the dropping funnel over 15 minutes, and the remaining total amount of the monomer emulsion 1 is charged from the dropping funnel over 1.5 hours. Subsequently, the total amount of the monomer emulsion 2 is added from the dropping funnel to 2 The polymerization was carried out over a period of time. After aging for 3 hours, the mixture was cooled, and ion-exchanged water was added and the pH was adjusted to 7.5 with aqueous ammonia to prepare resin particle dispersion 1 having a solid content of 40%.

  It was 250 nm when the particle diameter of the obtained resin particle was measured using Microtrac UPA (made by Nikkiso Co., Ltd.). Further, the resin particles were diluted with water so as to be 0.1 wt%, and the zeta potential was measured with Zeta Sizer Nano ZS (trade name: manufactured by Malvern Instruments Ltd.). As a result, it was −45 mV. Furthermore, qualitative analysis of the polyoxyethylene chain was performed by chemical decomposition gas chromatography. The resin particles were decomposed with hydroiodic acid and analyzed by gas chromatography. As a result, ethyl iodide, which was a decomposition product of the polyoxyethylene portion, was detected, and it was confirmed that the resin contained polyoxyethylene chains. . In addition, the chemical decomposition gas chromatography method was performed according to the method as described in literature "The TRC News No.115 pp.35-38".

3.1.2. Resin particle dispersions 2-4
Resin particle dispersions 2 and 3 were prepared in the same manner as in the preparation of the resin particle dispersion 1, except that the amounts and types of reactive emulsifiers and polymerization initiators were changed as shown in Table 1. The average particle diameter of each resin particle is shown in Table 1. Further, the zeta potentials of the resin particles of the resin particle dispersions 2, 3, and 4 were −55 mV, −50 mV, and −60 mV, respectively.

  Further, in place of the reactive emulsifier, polyoxyethylene aryl ether sulfate ester salt (New Coal B4-SN: manufactured by Nippon Emulsifier Co., Ltd.) and polyoxyethylene alkyl ether (New Coal 2330: Japan Emulsifier Stock) are used as non-reactive emulsifiers. The resin particle dispersion 4 was prepared in the same manner as the resin particle dispersion 1 except that the amount and type of the polymerization initiator were changed as shown in Table 1. The average particle diameter of the resin particles is shown in Table 1.

3.2. Preparation of ink 1020 g of a separately prepared cyan pigment dispersion (pigment concentration 15% by mass), Surfynol DF110D (trade name: manufactured by Air Products Japan Co., Ltd.) (2,5,8,11-tetramethyl-) as an antifoaming agent 6-dodecin-5,8-diol) (log P = 4.18) (acetylene glycol type), 2 g of 1,2-hexanediol (log P = 0.7) as the first solvent, 2 g 5 g of polyethylene glycol 200 as a solvent, 25 g of resin particle dispersion 1, 15 g of glycerin as a humectant, 0.5 g of Silface SAG503A (trade name: manufactured by Nissin Chemical Industry Co., Ltd.) as a surface tension adjuster, pH Mix 0.4g of triisopropanolamine as a regulator and add ion exchange water to make the total amount 100g. It was. Thereafter, the ink was filtered through a membrane filter having a pore diameter of 1.2 μm to prepare the ink of Example 1.

  The types and amounts of the antifoaming agent, the first solvent, the second solvent, the resin particle dispersion, the humectant and the surface tension adjusting agent were changed as shown in Table 2, and the ink of Example 2-6 was used in the same manner as above. Ink and Comparative Example 1-3 were prepared.

表２中、「ＫＳ−６６」は、シリコーン系消泡剤であり、信越化学工業株式会社から入手した。「ＢＹＫ−３４８」は、表面張力調整剤であり、ビックケミー・ジャパン株式会社から入手した。また、２，４，７，９−テトラメチル−５−デシン−４，７−ジオールのｌｏｇＰ（水−オクタノール分配係数）は３．１１、３−（２−エチルヘキシルオキシ）−１，２−プロパンジオールのｌｏｇＰは２．５３である。ブチルトリグリコールのｌｏｇＰは０．０２である。さらに、プロピオン酸は、ｌｏｇＰが０．２５でありｌｏｇＰが０．０−２．０の範囲である化合物ではあるが、構造がグリコール及び／又はグリコールエーテル系ではない化合物である。

In Table 2, “KS-66” is a silicone-based antifoaming agent and was obtained from Shin-Etsu Chemical Co., Ltd. “BYK-348” is a surface tension adjuster and was obtained from Big Chemie Japan Co., Ltd. The log P (water-octanol partition coefficient) of 2,4,7,9-tetramethyl-5-decyne-4,7-diol is 3.11, 3- (2-ethylhexyloxy) -1,2-propane. The log P of the diol is 2.53. The log P of butyl triglycol is 0.02. Further, propionic acid is a compound whose log P is 0.25 and whose log P is in the range of 0.0-2.0, but whose structure is not glycol and / or glycol ether.

3.3. Ink evaluation 3.3.1. Storage Stability Each ink of Examples and Comparative Examples was placed in a sample bottle and stored for one week at two levels of 60 ° C. and −20 ° C., and then each ink was filtered to collect precipitates. The storage stability was evaluated based on the number and appearance of precipitates in two levels. The evaluation criteria are shown below.
A: 50 precipitates / less than 1 mL B: 50 precipitates / 1 mL or more and less than 200 mL / mL C: 200 precipitates / 1 mL or more D: Separation into ink

3.3.2. Antifoaming property Each ink of Examples and Comparative Examples is put in a sample bottle up to 1/10 the height of the sample bottle, stirred for 1 minute and allowed to stand, and defoamed at the height of the remaining foam after 10 minutes. Sex was evaluated. The evaluation criteria are shown below.
A: Less than 10% of the ink height B: 10% or more and less than 100% of the ink height C: 100% or more and less than 500% of the ink height D: 500% or more of the ink height

3.3.3. Discharge stability Inkjet printer EM-930C (trade name: manufactured by Seiko Epson Corporation) was filled with each of the inks of Examples and Comparative Examples, and immediately after cleaning was repeated 3 times, 20 nozzles were discharged while discharging all nozzles. Continuous printing was performed, and the number of nozzles that were missing or bent was determined based on the following criteria.
A: Missing or bent 0 nozzle B: Missing or bent 1 to 5 nozzles C: Missing or bent 6 nozzles or more

3.4. Evaluation results The above evaluation results are shown in Table 2. From the evaluation results, an antifoaming agent selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient of 2.0 or more and 5.0 or less, and a water-octanol partition coefficient of 0.0 or more and 2.0 or less. A first solvent selected from the glycol-based and glycol ether-based compounds, a glycol-based second solvent, and resin particles having a zeta potential of −65 mV to −15 mV and having a polyoxyethylene chain. The inks of the respective examples had very good results in all of storage stability, antifoaming property and ejection stability. As a result, at least, the antifoaming agent is sufficiently solubilized by the first solvent, the resin particles are not agglomerated, and sufficient antifoaming property and discharge stability are obtained. I support that.

  On the other hand, the ink of Comparative Example 1 using the resin particle dispersion 4 produced without using a reactive emulsifier resulted in insufficient defoaming properties and ejection stability. This is considered to be due to the fact that the antifoaming effect was reduced because the antifoaming agent was solubilized, but the non-reactive emulsifier remained in the resin particle dispersion 4 and the foaming property was increased. .

  Further, in Comparative Example 2 in which the antifoaming agent was a silicone compound, the storage stability was insufficient. This is considered due to the fact that the antifoaming agent could not be sufficiently solubilized. Furthermore, the ink of Comparative Example 3 using propionic acid that is not a glycol-based or glycol ether-based compound as the first solvent was inferior in all of storage stability, antifoaming property, and ejection stability. Even if propionic acid is in the range of log P of 0.0-2.0, the antifoaming agent can be used sufficiently due to the structural difference between the antifoaming agent of glycol type and glycol ether type compound. This is considered to be due to the fact that it could not be solubilized.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (7)

Color materials,
An antifoaming agent selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient of 2.0 to 5.0;
A first solvent selected from glycol-based and glycol ether-based compounds having a water-octanol partition coefficient of 0.0 or more and 2.0 or less;
A glycol-based second solvent different from the first solvent;
Resin particles having a zeta potential of −65 mV to −15 mV and having a polyoxyethylene chain;
An ink for inkjet recording, comprising: In claim 1,
An ink for inkjet recording, comprising the first solvent in an amount of 0.5% by mass to 15% by mass. In claim 1 or claim 2,
An ink for ink jet recording containing the antifoaming agent in an amount of 0.005% by mass to 0.5% by mass. In any one of Claims 1 to 3,
The ink for ink jet recording, wherein the second solvent is selected from ethylene glycol, propylene glycol, 1,3-propanediol and a multimer thereof. In any one of Claims 1 thru | or 4,
An ink for inkjet recording, comprising the second solvent in an amount of 2% by mass to 30% by mass. In any one of Claims 1 thru | or 5,
The ink for ink jet recording, wherein the resin particles have an anionic functional group. In claim 6,
Ink for ink jet recording used in a heat drying type ink jet recording apparatus.