JP2017110182A - Ink composition and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition that has excellent abrasion resistance and suppresses bleeding of a recorded matter while maintaining excellent discharge stability when an aggregating liquid and the ink composition are adhered to a recording medium.SOLUTION: The ink composition comprises a coloring material, water, an organic solvent and polymer particles. The organic solvent comprises an organic solvent having a standard boiling point of 150°C or higher and 250°C or lower, in which the content of an organic solvent that is an alkyl polyol having a standard boiling point of 280°C or higher is 2.0 mass% or less with respect to the whole amount of the ink composition. The polymer particles have a core-shell structure including a core polymer and a shell polymer, in which a glass transition temperature of the shell polymer is higher than a glass transition temperature of the core polymer. The ink composition is to be used for a recording method for recording by use of the ink composition together with an aggregating liquid comprising an aggregating agent capable of aggregating or thickening components of the ink composition.SELECTED DRAWING: None

Description

  The present invention relates to an ink composition and a recording method.

  The ink jet recording method is capable of recording high-definition images with a relatively simple device, and has been rapidly developed in various fields. Among them, various studies have been made on obtaining a more stable and high-quality recorded matter.

  For example, Patent Document 1 discloses an ink jet ink, which is excellent in ink drying property at the time of high-speed printing and is excellent in ink storage stability. It is for use with a reaction solution for curing, and includes water, a water-soluble organic solvent, a colorant, and a binder resin. The binder resin is composed of a core portion and a shell portion that covers the core portion. An ink-jet ink is disclosed, which has a reactive group that reacts with the reaction liquid on the surface of the surface, and has an MFT (minimum film-forming temperature) of the shell portion higher than that of the core portion.

JP2013-204025A

  The ink composition as disclosed in Patent Document 1 is used together with the reaction liquid, but by including a specific binder resin, a certain degree of drying property of the ink composition can be obtained. Moreover, this ink composition is excellent also in discharge stability by containing a specific binder resin. However, such an ink composition has a higher level of dryness after landing on the recording medium due to the content of the alkyl polyol having a normal boiling point of 280 ° C. or higher exceeding a predetermined amount. In such a case, the abrasion resistance may not be sufficient, and bleeding may occur in the obtained recorded matter.

  Accordingly, the present invention has been made to solve at least a part of the above-described problems, and maintains excellent ejection stability when an aggregating liquid and an ink composition are adhered to a recording medium. The first object of the present invention is to provide an ink composition which is excellent in abrasion resistance and suppresses bleeding of recorded matter. The present invention also provides a recording method in which bleeding of a recorded matter is suppressed while maintaining excellent ejection stability when an aggregating liquid and an ink composition are adhered to a recording medium of 38 ° C. or lower. This is the second purpose. Bleed is a state in which ink droplets of ink composition that adheres to the recording medium in a dot shape flow to each other and the ink flows between the ink droplets, resulting in a blurred image, or colors that are different from each other. In the case of this ink composition, color mixing between dots further occurs, resulting in a state where the image becomes unclear.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention include a coloring material, water, an organic solvent, and polymer particles, and the organic solvent includes an organic solvent having a standard boiling point within a predetermined range, and an alkyl polyol. And the polymer particles have a core-shell structure including a core polymer and a shell polymer, and the glass transition temperature of the shell polymer is higher than the glass transition temperature of the core polymer. Discharge stability by using a high ink composition in a recording method for recording using the ink composition and an aggregating liquid containing an aggregating agent capable of aggregating or thickening the components of the ink composition. As a result, the present invention was completed.

  That is, the present invention is an ink composition containing a coloring material, water, an organic solvent, and polymer particles, wherein the organic solvent includes an organic solvent having a standard boiling point of 150 ° C. or more and 250 ° C. or less, and the standard boiling point is The content of the organic solvent which is an alkyl polyol of 280 ° C. or higher is 2.0% by mass or less based on the total amount of the ink composition, and the polymer particles include a core polymer and a shell polymer. A glass transition temperature of the shell polymer that is higher than that of the core polymer, and a flocculant capable of aggregating or thickening the components of the ink composition and the ink composition. An ink composition used in a recording method for recording using an aggregating liquid. The reason why such an ink composition can solve the problems of the present invention is considered as follows. However, the factor is not limited to this. That is, the ink composition of the present invention is a recording that uses the ink composition and the aggregation liquid to record, mainly by containing polymer particles having a glass transition temperature of the shell polymer higher than the glass transition temperature of the core polymer. When used in the method, the discharge stability is excellent due to the suppression of the polymer particles being welded to the ink jet head (a state where the polymer particles adhere to the surface and are not easily removed. The ink composition of the present invention is excellent in abrasion resistance mainly due to the core polymer in the polymer particles landed on the recording medium flowing out due to impact or heat of landing. In this ink composition, the content of the alkyl polyol having a standard boiling point of the organic solvent of 150 ° C. or more and 250 ° C. or less and a standard boiling point of 280 ° C. or more is 2.0% relative to the total amount of the ink composition. When the content is less than or equal to mass%, the drying property of the ink composition that has landed on the recording medium is improved, so that the abrasion resistance is further improved and bleeding of the recorded matter is also suppressed.

  In the ink composition of the present invention, the content of the organic solvent having a normal boiling point of 280 ° C. or more is preferably 0.5% by mass or less based on the total amount of the ink composition, and the acid of the shell polymer is Preferably, the acid value of the core polymer is higher than the acid value of the core polymer, the acid value of the shell polymer is 20 mgKOH / g or more, and the acid value of the core polymer is at least 15 mgKOH / g or less. More preferably, the shell polymer preferably contains at least an aromatic monomer unit as a structural unit, and the difference between the glass transition temperature of the core polymer and the glass transition temperature of the shell polymer is 10 ° C. or more. More preferably, the flocculant is one or more selected from the group consisting of polyvalent metal salts, organic acids, and cationic compounds. Preferably a two or more.

  Furthermore, according to one aspect of the recording method of the present invention, the ink composition and an aggregation liquid containing an aggregating agent capable of aggregating or thickening the components of the ink composition are attached to a recording medium. Preferably, the attaching step is a step of attaching at least the ink composition to a recording medium by an inkjet method, and the attaching step is performed on a recording medium heated with the ink composition. The step of attaching is preferable.

In addition, another aspect of the recording method of the present invention includes an aggregation liquid adhesion step in which an aggregation liquid containing an aggregating agent capable of aggregating or thickening the components of the ink composition is adhered to a recording medium; An ink composition adhering step for adhering an ink composition containing a material, water, an organic solvent, and polymer particles to a recording medium having a surface temperature of 38 ° C. or less, wherein the ink composition comprises: The organic solvent includes an organic solvent having a normal boiling point of 150 ° C. or higher and 250 ° C. or lower, and the content of the organic solvent that is an alkyl polyol having a standard boiling point of 280 ° C. or higher is based on the total amount of the ink composition. The content is preferably 0.5% by mass or less, and the polymer particles preferably include at least an aromatic monomer unit as a constituent unit.
In another aspect of the recording method of the present invention, the step of attaching the ink composition to the recording medium is a step of heating the ink composition to the recording medium having a temperature of 30 to 50 ° C. It is preferable to use a recording method.

1 is a side view showing an outline of an example of an inkjet recording apparatus that can be used in the present embodiment.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. However, the present invention is not limited to this, and the gist thereof is described below. Various modifications are possible without departing from the scope. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[Ink composition]
The ink composition of this embodiment includes a colorant, water, an organic solvent, and polymer particles, and includes an aggregating agent that can aggregate or thicken the ink composition and the components of the ink composition. It is used for the recording method which records using a liquid. The organic solvent includes an organic solvent having a normal boiling point of 150 ° C. or higher and 250 ° C. or lower, and the content of the organic solvent that is an alkyl polyol having a standard boiling point of 280 ° C. or higher is based on the total amount of the ink composition. 2.0% by mass or less. Furthermore, the polymer particles have a core-shell structure including a core polymer and a shell polymer, and the glass transition temperature of the shell polymer is higher than the glass transition temperature of the core polymer. By using such an ink composition in a recording method for recording using the ink composition and an aggregation liquid containing an aggregating agent capable of aggregating or thickening the components of the ink composition, the ink composition is excellent. In addition, the rubbing resistance and image quality (bleed suppression) of the recorded matter obtained are improved while maintaining the discharge stability. The ink composition of the present embodiment is excellent in glossiness in addition to excellent ejection stability, rubbing resistance, and image quality (bleed suppression).

<Color material>
A pigment can be used as the color material. Although it does not specifically limit as a pigment, For example, the following are mentioned.

  The carbon black used for the black ink is not particularly limited. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B, etc. (Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. (above, Columbia Carbon, Carbon 1 Rubbi 400, Carbon Co. Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. (Cabot Corp. CA Kol. , Color B lack FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A , Special Black 4 (manufactured by Degussa).

  Although it does not specifically limit as a pigment used for white ink, For example, C.I. I. Pigment white 6, 18, 21, titanium oxide, zinc oxide, zinc sulfide, antimony oxide, zirconium oxide, white hollow resin particles and polymer particles.

  Although it does not specifically limit as a pigment used for yellow ink, For example, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180.

  Although it does not specifically limit as a pigment used for a magenta ink, For example, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48: 2, 48: 5, 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50.

  Although it does not specifically limit as a pigment used for cyan ink, For example, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat Blue 4, 60.

  The pigments other than those described above are not particularly limited. I. Pigment green 7,10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

  The color material preferably contains one or more pigments selected from the group consisting of self-dispersing pigments and polymer-dispersed pigments. Thereby, the color material tends to be more excellent in glossiness due to the uniform dispersion in the recorded matter.

The self-dispersing pigment is a pigment having a hydrophilic group on its surface. As the hydrophilic group, -OM, -COOM, -CO -, - SO 3 M, -SO 2 M, -SO 2 NH 2, -RSO 2 M, -PO 3 HM, -PO 3 M 2, -SO 2 It is preferably at least one hydrophilic group selected from the group consisting of NHCOR, —NH ₃ , and —NR ₃ .

  In these chemical formulas, M represents a hydrogen atom, an alkali metal, ammonium, an optionally substituted phenyl group, or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms or a substituted group. A naphthyl group which may have a group is represented. The above M and R are selected independently of each other.

  Specifically, the self-dispersing pigment is produced by subjecting the pigment to physical treatment and / or chemical treatment to bond (graft) the hydrophilic group to the surface of the pigment. Specific examples of the physical treatment include vacuum plasma treatment. Further, as the chemical treatment, specifically, a wet oxidation method in which oxidation is performed with an oxidizing agent in water, a method in which p-aminobenzoic acid is bonded to the pigment surface to bond a carboxyl group via a phenyl group, and the like can be mentioned. It is done.

  The polymer-dispersed pigment is a pigment that can be dispersed in a liquid by a polymer. The polymer content relative to the pigment can be expressed as the coverage of the polymer that coats the pigment. The polymer coverage is preferably 1.0% to 50%, more preferably 1.0% to 10%, and still more preferably 1.0% to 5.0%. When the coverage is 1.0% or more, the dispersibility tends to be good. Further, when the coverage is 50% or less, the color developability tends to be further improved, and when it is 5.0% or less, the color developability tends to be even better. is there.

  70 mass% or more of the said polymer is preferable in it being a polymer by the copolymerization of (meth) acrylate and (meth) acrylic acid among the structural components. Thereby, it tends to be further excellent in the fixing property and glossiness of the ink. Moreover, it is more preferable that at least one of the alkyl (meth) acrylate having 1 to 24 carbon atoms and the cyclic alkyl (meth) acrylate having 3 to 24 carbon atoms is polymerized from a monomer component of 70% by mass or more. Specifically, as the monomer component, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl ( (Meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate Cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetramethylpiperidyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dis Ropenteniru (meth) acrylate, dicyclopentenyloxy (meth) acrylate, and behenyl (meth) acrylate. In addition, as other monomer components for polymerization, hydroxy (meth) acrylate having a hydroxyl group such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, diethylene glycol (meth) acrylate, urethane (meth) acrylate, epoxy (meth) ) Acrylate and the like. In the present specification, “(meth) acrylate” is a concept including both “methacrylate” and “acrylate”.

  In the ink composition, the content of the coloring material is preferably 0.2% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less with respect to the total amount (100% by mass) of the ink composition. It is 0.0 mass% or less, More preferably, it is 1.0 mass% or more and 3.0 mass% or less. When the content of the color material is within the above range, the color developability tends to be further improved.

<Water>
Examples of the water in this embodiment include water from which ionic impurities are 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. . In addition, when water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, generation of mold and bacteria can be prevented when the aggregated liquid is stored for a long period of time. This tends to improve the storage stability. The water content in the ink composition is preferably 40 to 97% by mass, more preferably 45 to 90% by mass, and still more preferably 50 to 80% by mass. In addition, the ink composition of the present embodiment is preferably a water-based ink composition containing at least water as a main solvent component contained in terms of excellent drying properties of the ink on a recording medium and low addition to the environment. .

〔Organic solvent〕
The organic solvent of this embodiment includes an organic solvent having a normal boiling point of 150 ° C. or higher and 250 ° C. or lower, and preferably includes an organic solvent having a standard boiling point of 180 ° C. or higher and 250 ° C. or lower.
The content of the organic solvent that is an alkyl polyol having a standard boiling point of 280 ° C. or higher is 2.0% by mass or less, preferably 1.0% by mass or less, based on the total amount of the ink composition. More preferably, it is 0.5 mass% or less, More preferably, it is 0.2 mass% or less. As a result, the ink composition that has landed on the recording medium can be obtained at a higher level of dryness, and therefore excellent abrasion resistance and image quality (suppression of bleeding) can be obtained.

  Although it does not specifically limit as a kind of organic solvent, For example, a cyclic nitrogen compound, an aprotic polar solvent, a monoalcohol, an alkyl polyol, and glycol ether are mentioned. As the organic solvent of the present embodiment, various organic solvents having a normal boiling point of 150 ° C. or more and 250 ° C. or less can be appropriately selected from these organic solvents. In addition, the ink composition preferably does not contain an organic solvent that is an alkyl polyol having a normal boiling point of 280 ° C. or higher, but if its content is 2.0% by mass or less with respect to the total amount of the ink composition It is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.2% by mass or less. Further, from the viewpoint of abrasion resistance and glossiness, the ink composition preferably does not contain an organic solvent having a standard boiling point of 280 ° C. or higher (all organic solvents including but not limited to the above alkyl polyols). The content is more preferably 2.0% by mass or less with respect to the total amount of the ink composition, more preferably 1.0% by mass or less, 0.5% by mass or less, and further 0.2% by mass. The following is more preferable. Furthermore, it is more preferable that the content of the organic solvent having a normal boiling point of more than 250 ° C. is within the above range. For example, the content is more preferably 2.0% by mass or less, and further preferably 0.2% by mass or less with respect to the total amount of the ink composition.

  The organic solvent preferably contains at least one of a cyclic nitrogen compound and an aprotic polar solvent. The ink composition contains a cyclic nitrogen compound or an aprotic polar solvent, so that the apparent glass transition temperature of the polymer particles can be shifted to a lower temperature side, and the core polymer and shell polymer are softened at a lower temperature than the original. Therefore, the fixability of the ink composition to the recording medium tends to be improved. Thereby, particularly when the recording medium is made of polyvinyl chloride, the fixability of the ink composition to the recording medium can be improved.

  The aprotic polar solvent is not particularly limited, and examples thereof include a cyclic ketone compound, a chain ketone compound, and a chain nitrogen compound. Typical examples of the cyclic nitrogen compound and the aprotic polar solvent include pyrrolidone, imidazolidinone, sulfoxide, lactone, and amide ether solvents. Specifically, among these, 2-pyrrolidone, N-alkyl-2-pyrrolidone, 1-alkyl-2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, imidazole, 1 -Methylimidazole, 2-methylimidazole, and 1,2-dimethylimidazole are preferred.

  Although it does not specifically limit as monoalcohol, For example, methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pen Examples include butanol, 3-pentanol, and tert-pentanol.

  Although it does not specifically limit as an alkyl polyol, For example, glycerol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol (1,2-propanediol), dipropylene glycol, 1,3-propylene glycol (1,3-propane) Diol), isobutylene glycol (2-methyl-1,2-propanediol), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butene-1,4-diol, 1 , 2-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1 , 7-Heptanediol and 1,8-octanediol And the like.

  Although it does not specifically limit as glycol ether, For example, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t -Butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether , Propylene glycol mono-iso-propyl ether, propylene glycol Call mono -n- butyl ether, dipropylene glycol mono -n- butyl ether, dipropylene glycol mono -n- propyl ether, and dipropylene glycol monomethyl -iso- propyl ether and the like.

  The content of the organic solvent is preferably 5.0% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 30% by mass or less, with respect to the total amount (100% by mass) of the ink composition. Preferably, it is 13 mass% or more and 25 mass% or less. When the content of the organic solvent is 50% by mass or less, the drying property of the ink composition attached to the recording medium tends to be further improved. Moreover, when the content of the organic solvent is 5.0% by mass or more, the ejection stability of the ink composition tends to be ensured. Furthermore, the content of the organic solvent having a normal boiling point of 150 ° C. or higher and 250 ° C. or lower is preferably set in the above range, and the content of the organic solvent having a standard boiling point of 180 ° C. or higher and 250 ° C. or lower is set in the above range. More preferred.

<Polymer particles>
The polymer particles of the present embodiment have a core-shell structure including a core polymer and a shell polymer, and the glass transition temperature of the shell polymer is higher than the glass transition temperature of the core polymer. By doing so, the shell resin is difficult to melt, the polymer particles are prevented from being welded to each other and the ejection stability is excellent, and the core resin is increased when the recording medium is heated after the attaching process. It is easy to form a film, and the recorded material can be excellent in abrasion resistance. Overall, the ink composition can be excellent in both ejection stability and abrasion resistance. In this respect, it is advantageous to lower the Tg of the core polymer and increase the Tg of the shell polymer.
“Core-shell structure” refers to a structure in which a core polymer is formed inside voids of a shell polymer. Accordingly, not only a structure in which the surface of the core polymer is covered with the shell polymer but also a structure in which the core polymer is filled in part of the voids of the three-dimensional network structure formed by the shell polymer is included. Therefore, the “core-shell structure” in the present specification includes polymer particles in which the boundary between the core part and the shell part is not strictly clear. However, in the second recording method to be described later, the polymer particles of the present embodiment are not limited to polymer particles having a core-shell structure, and may be single-layer particles containing only one kind as a polymer, Particles containing a mixture of two or more polymers (but not having a core-shell structure) may be used. Of course, the polymer particles of this embodiment used in the second recording method may be polymer particles having a core-shell structure. Examples of the polymer particles other than the polymer particles having a core-shell structure include polymer particles made of only the above-described core resin or shell resin. The types of resins constituting the polymer particles (polymer particles having a core-shell structure and polymer particles other than the polymer particles having a core-shell structure) include resins having at least a (meth) acrylic monomer as a structural unit. In addition, polyurethane resins, polyether resins, polyester resins, composite resins thereof and the like can be mentioned.

  The glass transition temperature of the core polymer is preferably 0 ° C. or higher and lower than 60 ° C. When the glass transition temperature of the core polymer is less than 60 ° C., the core polymer can easily flow out after the shell polymer is softened, so that it tends to be more excellent in abrasion resistance. Moreover, when the glass transition temperature of the core polymer is 0 ° C. or higher, the storage stability of the ink composition tends to be superior.

ここで Ｗｎ ；各単量体の質量分率
Ｔｇｎ；各単量体のホモポリマーのＴｇ（単位：Ｋ）
Ｔｇ ；共重合体のＴｇ（単位：Ｋ） The glass transition point (hereinafter also referred to as “Tg”) is measured by differential scanning calorimetry (DSC). Specifically, it is based on the method described in Examples described later. Further, it can be calculated from the Tg of a known homopolymer of a polymerizable monomer using a calculation formula, and can be used as an index for controlling the glass transition point. When the resin contained in the core polymer and the shell polymer described later is a copolymer, the glass transition temperature (Tg) of the copolymer is the Tgn (unit: K) of various homopolymers and the mass fraction of the monomer. It can be calculated from the rate (Wn) by the following FOX equation.

Where Wn: mass fraction of each monomer
Tgn: Tg of homopolymer of each monomer (unit: K)
Tg: Tg of copolymer (unit: K)

  In other words, the glass transition point of the core polymer or shell polymer can be controlled by selecting the homopolymer when the polymer is a homopolymer. When the polymer is a copolymer, it can be controlled by considering (calculating) the Tg of the homopolymer and the FOX equation. For example, the resin may be designed by the above formula, and the prepared resin may be redesigned by measuring the actual Tg and feeding it back to the target Tg.

  More preferably, the core polymer does not have an acid value. Moreover, it is preferable that a core polymer contains an aromatic monomer unit at least as a structural unit. As a result, the core polymer becomes more hydrophobic than a polymer that does not contain an aromatic monomer unit, so that a more hydrophobic film can be formed on the recording medium. As a result, the rub resistance of the recorded matter tends to be further improved. Here, “structural unit” is a unit constituting a polymer, and “monomer unit” refers to a structural unit derived from the monomer. The acid value of the core polymer is not particularly limited, but from the above viewpoint, it is preferably 0 mgKOH / g or more and 20 mgKOH / g or less, more preferably 0 mgKOH / g or more and 15 mgKOH / g or less, and further preferably 0 mgKOH / g or more. It is 13 mgKOH / g or less.

  Although it does not specifically limit as an aromatic monomer, For example, styrene, (alpha) -methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, and divinylbenzene are mentioned.

  Further, the core polymer is not particularly limited, but as a structural unit, for example, a hydrophilic (meth) acrylate monomer unit, a hydrophobic (meth) acrylate monomer unit having an alkyl group having 3 or more carbon atoms, or a hydrophobic having a cyclic structure It is preferable to contain at least one of a functional (meth) acrylate monomer unit, a (meth) acrylamide monomer unit or an N-substituted derivative unit thereof, and a carboxylic acid monomer unit.

  The hydrophilic (meth) acrylate monomer is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, α-hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (poly) Examples include ethylene glycol (meth) acrylate, methoxy (poly) ethylene glycol (meth) acrylate, ethoxy (poly) ethylene glycol (meth) acrylate, and (poly) propylene glycol (meth) acrylate. Among these, methyl (meth) acrylate and ethyl (meth) acrylate are preferable. Here, “hydrophilic” means that the solubility in 100 mL of water (20 ° C.) is 0.3 g or more. When the core polymer contains a hydrophilic (meth) acrylate monomer as a monomer unit, the polymerization reactivity tends to be excellent when the core polymer is produced.

  Although it does not specifically limit as a hydrophobic (meth) acrylate monomer which has a C3 or more alkyl group, For example, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (Meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) ) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cetyl (meth) acrylate, neopentyl (meth) acrylate, and (meth) acrylate having an alkyl group having 3 or more carbon atoms such as behenyl (meth) acrylate. Relate and the like. Among these, lauryl (meth) acrylate is preferable. Here, “hydrophobic” means that the solubility in 100 mL of water (20 ° C.) is less than 0.3 g.

  The hydrophobic (meth) acrylate monomer having a cyclic structure is not particularly limited, and examples thereof include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl ( Examples include meth) acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate.

  Although it does not specifically limit as a (meth) acrylamide monomer or its N-substituted derivative, For example, (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, diacetone acrylamide, and N, N-dimethylacryl (meth) amide (Meth) acrylamide or an N-substituted derivative thereof.

  As described above, it is preferable not to use a carboxylic acid monomer in the core polymer, but it is also possible to use a carboxylic acid monomer to such an extent that the rub resistance of the recorded matter can be maintained at a predetermined level or more. Although it does not specifically limit as a carboxylic acid monomer, For example, (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid are mentioned. Among these, (meth) acrylic acid is preferable. Here, the “carboxylic acid monomer unit” refers to a polymerizable monomer unit having a carboxyl group and a polymerizable unsaturated group.

  The said monomer may be used individually by 1 type, or may use 2 or more types together.

  When the core polymer contains a hydrophobic monomer unit, the content of the hydrophobic monomer unit is preferably 60% by mass or more among all the structural units of the core polymer. When the content of the hydrophobic monomer unit is in the above range, a hydrophobic film is formed on the surface of the image recorded on the recording medium by performing a heat treatment or the like, so that the abrasion resistance is further improved. There is a tendency.

  The glass transition temperature of the shell polymer is preferably 60 ° C. or higher and 150 ° C. or lower. When the glass transition temperature of the shell polymer is 60 ° C. or higher, the polymer particles are ejected from the recording head without destroying the core-shell structure when the ink composition is ejected in a high-temperature environment. Is possible. As a result, since the adhesion of polymer particles in the nozzle can be further suppressed, clogging of the nozzle tends to be further suppressed. In addition, when the glass transition temperature of the shell polymer is 150 ° C. or lower, the shell polymer tends to soften on the recording medium, and therefore, it tends to be more excellent in abrasion resistance. After landing the ink composition on the recording medium, the core polymer flows out of the softened shell polymer by heating the ink composition on the recording medium to a temperature higher than the glass transition temperature of the shell polymer. A film made of a polymer and a shell polymer is formed on the recording medium. At this time, the softened core polymer spreads and adheres onto the recording medium, whereby a film having better abrasion resistance after drying tends to be formed.

  From the viewpoint of making the ink composition of the present embodiment excellent in ejection stability, the glass transition temperature of the shell polymer is higher than the glass transition temperature of the core polymer. From the same viewpoint, the difference between the glass transition temperature of the shell polymer and the glass transition temperature of the core polymer is preferably 10 ° C. or higher.

  The shell polymer is preferably hydrophilic, and more preferably has an acid value. Thereby, even when the drying of water progresses in the recording head and on the recording medium and the occupation ratio of the organic solvent increases, the dispersion of the polymer particles is stable, and the aggregation of the polymer particles tends to be further suppressed. . The acid value of the shell polymer is preferably 20 mgKOH / g or more and 120 mgKOH / g or less. By having an acid value in this numerical range, it is possible to ensure sufficient hydrophilicity as a shell polymer.

  The acid value of the shell polymer is preferably higher than the acid value of the core polymer. Thereby, since the shell polymer tends to have higher hydrophilicity than the core polymer, aggregation of the polymers can be further suppressed and the abrasion resistance can be further increased. From the same viewpoint, it is preferable that the acid value of the shell polymer is 20 mgKOH / g or more, the acid value of the core polymer is 15 mgKOH / g or less, or both. The acid value of the core polymer and the acid value of the shell polymer are determined by calculating from the type and amount of monomers used for each. Specifically, it calculates | requires similarly to the method as described in the Example mentioned later.

  From the same viewpoint as described above, the acid value of the shell polymer is preferably 20 mgKOH / g or more and 100 mgKOH / g or less, more preferably 35 mgKOH / g or more and 80 mgKOH / g or less, and further preferably 50 mgKOH / g or more and 60 mgKOH / g. g or less.

  The shell polymer preferably contains at least an aromatic monomer unit as a constituent unit. When the shell polymer contains an aromatic monomer as a structural unit, the detailed action mechanism is unknown, but the discharge bending tends to be suppressed. In particular, since ink droplets are likely to bend when they are small dots, according to one aspect of the present embodiment, this discharge bend is suppressed. Therefore, one aspect of the ink composition of the present embodiment is particularly suitable for a recording head that can eject ink dots in multiple sizes from one nozzle. In addition, when the shell polymer contains a relatively hard aromatic monomer unit, the abrasion resistance of the film formed on the recording medium tends to be further improved.

  Moreover, it is preferable that a shell polymer contains a (meth) acrylate monomer unit and a carboxylic acid monomer unit as a structural unit. By using such a polymer, a carboxyl group can be present on the surface of the shell polymer. As a result, the dispersion stability of the polymer particles is further improved, and the viscosity of the ink composition is relatively low, so that the ejection stability tends to be further improved. The (meth) acrylate monomer is not particularly limited. For example, a hydrophilic (meth) acrylate monomer, a hydrophobic (meth) acrylate monomer having an alkyl group having 3 or more carbon atoms, and a hydrophobic ( And (meth) acrylate monomers. Specific examples of the (meth) acrylate monomer and the carboxylic acid monomer include the same ones as described above for the monomer constituting the resin contained in the core polymer, and the monomers may be used alone or in combination of two or more. You may use together.

  When the shell polymer contains a carboxylic acid monomer unit and an aromatic monomer unit, the ratio of the aromatic monomer unit to the carboxylic acid monomer unit (aromatic monomer / carboxylic acid monomer) in the shell polymer is preferably 0.15 or more. It is. As a result, an ink composition having an excellent balance between improvement in abrasion resistance by the aromatic monomer and redispersibility by the carboxylic acid monomer can be obtained.

  When the shell polymer contains a (meth) acrylate monomer unit and an unsaturated carboxylic acid monomer unit, the total content of the (meth) acrylate monomer unit and the unsaturated carboxylic acid monomer unit among all the structural units of the shell polymer is: 20 mass% or more is preferable, 30 mass% or more is more preferable, and 35 mass% or more is further more preferable. As a result, the dispersion stability of the polymer particles is further improved, and the viscosity of the ink composition is further lowered, so that the ejection stability tends to be further improved.

  When the shell polymer contains a hydrophilic monomer unit, the content of the hydrophilic monomer unit is preferably 20% by mass or more and 90% by mass or less, and preferably 30% by mass or more and 80% by mass or less among all the structural units of the shell polymer. More preferably, it is 35 mass% or more and 70 mass% or less. When the content of the hydrophilic monomer unit is not less than the above lower limit value, the shell polymer has hydration properties, so that the dispersion stability of the polymer particles in the ink composition tends to be further improved. Moreover, since it can suppress more effectively that a polymer particle adheres to a nozzle, it exists in the tendency for the discharge stability from the nozzle of a recording head to become more favorable. On the other hand, when the content of the hydrophilic monomer unit is not more than the above upper limit value, the dispersion of polymer particles can be achieved even when the drying rate of water in the recording head and on the recording medium increases and the occupation ratio of the organic solvent increases. Is stable, and the aggregation of polymer particles tends to be further suppressed.

  When the shell polymer contains a hydrophobic monomer unit, the content of the hydrophobic monomer unit is preferably 10% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 70% by mass or less among all the structural units of the shell polymer. More preferably, 30 mass% or more and 65 mass% or less are more preferable. Dispersion of polymer particles is stable even when the content of hydrophobic monomer units is above the above lower limit and the drying rate of water in the recording head and on the recording medium increases and the occupation ratio of the organic solvent increases. And it exists in the tendency which can suppress aggregation of polymer particles more. On the other hand, when the content of the hydrophobic monomer unit is not more than the above upper limit value, the shell polymer has hydration properties, and thus the dispersion stability of the polymer particles in the ink composition tends to be further improved. Moreover, since it can suppress more effectively that a polymer particle adheres to a nozzle, it exists in the tendency for the discharge stability from the nozzle of a recording head to become more favorable.

  Preferably, the polymer particle includes the core polymer and the shell polymer, and includes 10% by mass to 80% by mass (based on the mass of the entire polymer particle) of an aromatic monomer as a structural unit. By containing 10% by mass or more of a relatively hard aromatic monomer, the rub resistance of the recorded matter formed on the recording medium tends to be further improved. Moreover, it is in the tendency which can improve discharge stability more by containing an aromatic monomer 80 mass% or less.

  The average particle diameter of the polymer particles is preferably 10 nm or more and 100 nm or less, and more preferably 20 nm or more and 50 nm or less. Thus, when the average particle diameter of the polymer particles is 100 nm or less, excellent glossiness of the recorded material is easily obtained, and the film forming property of the ink composition on the recording medium tends to be excellent. In addition, since the polymer particles have an average particle diameter of 100 nm or less, it is difficult to form a large lump even when agglomerating, and thus nozzle clogging tends to be further suppressed. Furthermore, when the average particle diameter of the polymer particles is 100 nm or less, the viscosity of the ink composition can be relatively increased, and even if the temperature of the ink composition rises in the recording head, the ink discharge performance is not good. It tends to be able to suppress the viscosity from decreasing as it becomes more stable. On the other hand, when the average particle size of the polymer particles is 10 nm or more, the polymer particles tend to be more easily prepared.

  The average particle diameter in this specification is based on volume unless otherwise specified. As a measuring method, for example, it can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. Examples of the particle size distribution measuring device include a particle size distribution meter (for example, Microtrac UPA manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle.

  The relationship between the mass of the core polymer and the mass of the shell polymer in the polymer particles is preferably (core-shell polymer mass) ≦ (mass of shell polymer), and more preferably (mass of core-shell polymer) <(shell (Mass of polymer). More preferably, when the mass of the shell polymer is 100% by mass, the mass of the core polymer is preferably 40% by mass or more and 80% by mass or less. Thereby, since the balance between the mass of the core polymer and the mass of the shell polymer becomes better, the fixability of the ink composition becomes better, the ejection stability is further improved, and the vertical alignment defect tends not to occur. Here, “longitudinal alignment failure” is a phenomenon in which, in continuous ink ejection, ink is partially solidified around the nozzles by ejecting for a long time, the ejection direction is bent, and clean vertical lines cannot be printed.

  The content of the polymer particles in the ink composition (in terms of solid content) is preferably 0.5% by mass or more and 20% by mass or less, and 1.0% by mass or more and 10% by mass with respect to the total amount (100% by mass) of the ink composition. More preferably, it is 1.5 mass% or less, and more preferably 1.5 mass% or more and 5.0 mass% or less. When the content of the polymer particles is 0.5% by mass or more, it tends to be more excellent in abrasion resistance and adhesion. Moreover, it exists in the tendency which is more excellent in discharge stability because content of a polymer particle is 20 mass% or less.

<Method for producing polymer particles>
The production method of the polymer particles of the present embodiment is not particularly limited, and examples thereof include an emulsion polymerization method using an emulsifier and a method of forming by soap-free polymerization substantially using no emulsifier, and a method of forming by soap-free polymerization. preferable. Soap-free polymerization refers to a polymerization method in which a core-shell polymer is produced without substantially using an emulsifier. As used herein, “emulsifier” means a surfactant used in synthesis. Moreover, as soap-free polymerization, for example, polymer particles are polymerized in the presence of an emulsifier content in the solution of 1% by mass or less. In soap-free polymerization, for example, a shell polymer containing a (meth) acrylic acid monomer unit is formed, and a core is formed in the shell polymer. In addition, when polymer particles are produced using soap-free polymerization, the average particle diameter becomes very small, and the ejection stability and glossiness of the ink composition tend to be further improved.

  Although it does not specifically limit as surfactant used for a synthesis | combination, Anionic surfactant and a nonionic surfactant are suitable. Although it does not specifically limit as an anionic surfactant, For example, the ammonium salt of sodium dodecyl benzan sulfonate, sodium laurate, and polyoxyethylene alkyl ether sulfate is mentioned. The nonionic surfactant is not particularly limited, and examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, and polyoxyethylene An ethylene alkylamide is mentioned.

  Although it does not specifically limit as a polymerization initiator used by superposition | polymerization, A hydrophilic initiator is used, For example, potassium persulfate, ammonium persulfate, and hydrogen peroxide water are mentioned.

  Although an example of the method of soap free polymerization is demonstrated below, the polymerization method is not restrict | limited to the following. For example, ion-exchanged water and a polymerization initiator are put in a jacketed polymerization reaction tank, the inside of the polymerization tank is depressurized to remove oxygen, and then returned to atmospheric pressure with nitrogen, and the polymerization reaction tank is filled with a nitrogen atmosphere. . Under the nitrogen atmosphere, first, the temperature inside the polymerization reaction tank is set to a predetermined temperature, and then a pre-emulsion solution containing a monomer that is a constituent element of the shell polymer is dropped at a constant rate to synthesize a shell polymer. . Next, using the voids of the obtained shell polymer as a polymerization field, the core polymer is polymerized to synthesize polymer particles according to this embodiment. Specifically, a monomer mixture containing the above-mentioned hydrophobic monomer is dropped into an aqueous dispersion medium containing a shell polymer, and the core polymer is polymerized to form polymer particles. Thus, when the shell polymer is used as the polymerization site for the core polymer, it is not necessary to use an emulsifier in the monomer mixture.

<Wax>
The ink composition of this embodiment preferably further contains a wax. When the recording head is heated, the polymer particles are aggregated and fixed as the water evaporates, causing nozzle clogging of the recording head and possibly preventing stable ejection. On the other hand, the inclusion of wax tends to suppress aggregation of polymer particles during water evaporation. Thereby, ejection failure and clogging due to the adhesion of the polymer particles to the nozzle of the recording head can be suppressed, and as a result, the ink composition is excellent in recording stability. Also, during high temperature recording, the wax tends to suppress the coating with polymer particles from becoming too brittle. For this reason, the ink composition is less likely to deteriorate in abrasion resistance even when recorded at a high temperature.

  The melting point of the wax is preferably 70 ° C. or higher and lower than 110 ° C., more preferably 80 ° C. or higher and 110 ° C. or lower. When the melting point is in the above range, there is a tendency to obtain a recorded material that is more excellent in recording stability and is less susceptible to deterioration in abrasion resistance even during high temperature recording. The melting point can be measured with a differential scanning calorimeter (DSC). Further, the melting point of the wax can be controlled by adjusting the ratio of a plurality of structural units constituting the wax, for example.

  The average particle size of the wax particles is preferably 0.02 μm or more and 0.5 μm or less, and more preferably 0.04 μm or more and 0.3 μm or less. When the average particle diameter is in the above range, the recording stability is excellent, and the abrasion resistance tends to be more difficult to deteriorate even at high temperature recording. The average particle diameter can be measured by the same method as described for the polymer particles.

  The wax is not particularly limited, and examples thereof include (meth) acrylic wax, polyolefin wax such as polyethylene wax, and paraffin wax. Although it does not specifically limit as polyethylene wax, For example, AQUACER593 polyolefin wax (made by BYK), Nopcoat PEM-17 (made by San Nopco) Polylon L787, Polylon L788 (above, Chukyo Yushi Co., Ltd.), and Chemipearl W4005 (Mitsui Chemicals) For example). The wax may be synthesized by a conventional method. Waxes may be used alone or in combination of two or more.

  The wax content (in terms of solid content) in the ink composition is preferably 0.1% by mass or more and 2.5% by mass or less, more preferably 0%, based on the total amount (100% by mass) of the ink composition. .2% by mass or more and 1.0% by mass or less. When the wax content is within the above range, the recording stability tends to be excellent, and the abrasion resistance tends to be more difficult to deteriorate even during high temperature recording.

<Surfactant>
The ink composition preferably further contains a surfactant from the viewpoint of glossiness. The surfactant is not particularly limited, and examples thereof include acetylene glycol surfactants, fluorine surfactants, and silicone surfactants.

  The acetylene glycol surfactant is not particularly limited, but 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne- One selected from alkylene oxide adducts of 4,7-diol and alkylene oxide adducts of 2,4-dimethyl-5-decyn-4-ol and 2,4-dimethyl-5-decyn-4-ol The above is preferable. Although it does not specifically limit as a commercial item of an acetylene glycol type surfactant, For example, E series (A product made by Air Products Japan (Inc)) (Surfinol 104, etc.), such as Olfine 104 series and Olfine E1010, 465, 61, DF110D (trade name manufactured by Nissin Chemical Industry CO., Ltd.). One acetylene glycol surfactant may be used alone, or two or more acetylene glycol surfactants may be used in combination.

  Although it does not specifically limit as a fluorine-type surfactant, For example, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate ester, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, and A perfluoroalkylamine oxide compound is mentioned. Although it does not specifically limit as a commercial item of a fluorochemical surfactant, For example, S-144, S-145 (above brand name, Asahi Glass Co., Ltd. product); FC-170C, FC-430, Fluorard-FC4430 (above product) Name, manufactured by Sumitomo 3M Limited); FSO, FSO-100, FSN, FSN-100, FS-300 (above trade name, manufactured by Dupont); FT-250, 251 (above trade name, manufactured by Neos Co., Ltd.) Can be mentioned. A fluorine-type surfactant may be used individually by 1 type, and may use 2 or more types together.

  Although it does not specifically limit as a silicone type surfactant, For example, a polysiloxane type compound and a polyether modified organosiloxane are mentioned. 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 (above trade name, manufactured by Big Chemie), 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, KF-6015, KF-6017 (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. A silicone type surfactant may be used individually by 1 type and may use 2 or more types together.

  The surfactant content is preferably 0.05% by mass to 2.5% by mass and more preferably 0.05% by mass to 1.5% by mass with respect to the total amount (100% by mass) of the ink composition. It is below mass%. When the content of the surfactant is within the above range, the wettability of the ink composition attached to the recording medium tends to be further improved. Here, when referring to the content of the components in the present embodiment, it is not limited to the surfactant. For example, when a plurality of surfactants are included in the ink composition, the content of the surfactant is the total amount thereof. is there. The same applies to the other components.

  The ink composition includes, as other components, a dissolution aid, a viscosity modifier, a pH adjuster, an antioxidant, an antiseptic, an antifungal agent, a corrosion inhibitor, and a chelate for capturing metal ions that affect dispersion. Various additives such as an agent (for example, sodium ethylenediaminetetraacetate) can be appropriately contained.

[Aggregating liquid]
The aggregation liquid of this embodiment contains an aggregating agent that can aggregate or thicken the ink composition described above. The ink composition of the present embodiment is used in the recording method described later together with the aggregation liquid, and thereby exhibits the effects of the present invention. The aggregating liquid thickens or insolubilizes the ink composition by aggregating components contained in the ink composition when the aggregating agent in the aggregating liquid interacts with the ink composition. Thereby, landing interference and bleeding of the ink composition to be subsequently attached can be prevented, and lines, fine images, and the like can be drawn uniformly.

<Flocculant>
The flocculant is not particularly limited, but is preferably one or more selected from the group consisting of organic acids, polyvalent metal salts, and cationic compounds. Thereby, it is in the tendency for a bethamra and a bleed to be suppressed more. Among the components contained in the ink composition, examples of the component that aggregates with the aggregating agent include the above-described pigment, the core polymer and the shell polymer used for the polymer particles, and the wax.

  The organic acid is not particularly limited, but is preferably a carboxylic acid, and examples thereof include maleic acid, acetic acid, phosphoric acid, oxalic acid, malonic acid, and citric acid. Of these, monovalent or divalent or higher carboxylic acids are preferred. By including such a carboxylic acid, the aggregation effect of the polymer and the wax is further improved, and as a result, the color developability tends to be more excellent. In addition, an organic acid may be used individually by 1 type, and may use 2 or more types together.

  The polyvalent metal salt is not particularly limited, but a polyvalent metal salt of an inorganic acid or a polyvalent metal salt of an organic acid is preferable from the viewpoint of more effectively and reliably achieving the effects of the present invention. Such a polyvalent metal salt is not particularly limited, but examples thereof include alkaline earth metals belonging to Group 2 of the periodic table (eg, magnesium, calcium), and transition metals belonging to Group 3 of the periodic table (eg, lanthanum). And salts of earth metals from group 13 of the periodic table (eg, aluminum) and lanthanides (eg, neodymium). Moreover, as a salt of these polyvalent metals, carboxylate (for example, formic acid, acetic acid, benzoate), sulfate, nitrate, chloride, and thiocyanate are suitable. Among them, as polyvalent metal salts, calcium salts or magnesium salts of carboxylic acids (formic acid, acetic acid, benzoates, etc.), calcium salts or magnesium salts of sulfuric acid, calcium salts or magnesium salts of nitric acid, calcium chloride, magnesium chloride, And one or more selected from the group consisting of calcium salts or magnesium salts of thiocyanate are preferred. In addition, a polyvalent metal salt may be used individually by 1 type, and may use 2 or more types together.

  Although it does not specifically limit as a cationic compound, For example, a cationic polymer and a water-soluble metal compound are mentioned. From the viewpoint of more effectively and reliably achieving the effects of the present invention, examples of the cationic polymer include allylamine resins such as polyethyleneimine, polydiallylamine and polyallylamine, alkylamine polymers, JP-A-59-20696, and 59- 33176, 59-33177, 59-1555088, 60-11389, 60-49990, 60-83882, 60-109894, 62-198493, 63-49478 63-115780, 63-280681, JP-A-1-40371, 6-234268, 7-125411, 10-193976, and the like, A polymer having a quaternary ammonium base is preferably used. From the same viewpoint, the weight average molecular weight of these cationic polymers is preferably 5000 or more, more preferably about 5000 to 100,000. The weight average molecular weight of the cationic polymer is measured by gel permeation chromatography using polystyrene as a standard substance.

  The content of the flocculant is preferably 1.0% by mass or more and 20% by mass or less, more preferably 3.0% by mass or more and 17.5% by mass or less, with respect to the total amount (100% by mass) of the aggregation liquid. More preferably, the content is 0.0 mass% or more and 15 mass% or less. When the content of the flocculant is within the above range, betalam and bleed tend to be further suppressed.

  The aggregating liquid used in this embodiment may contain the same surfactant, organic solvent, and water as those used in the ink composition described above. In addition, the agglomerated liquid captures, as other components, dissolution aids, viscosity modifiers, pH adjusters, antioxidants, preservatives, antifungal agents, corrosion inhibitors, and metal ions that affect dispersion. Various additives such as chelating agents can be appropriately added.

〔Recording method〕
The recording method of this embodiment can be roughly divided into two forms. One form of the recording method of the present embodiment (hereinafter referred to as “first recording method”) includes an attaching step of attaching the ink composition of the present embodiment and the above-described aggregate liquid to a recording medium. Here, the adhering step preferably includes an aggregating liquid adhering step for adhering the aggregating liquid to the recording medium and an ink composition adhering step for adhering the ink composition to the recording medium. In the adhesion process, the ink composition adhesion process may be provided after the aggregation liquid adhesion process, or the aggregation liquid adhesion process may be provided after the ink composition adhesion process, and the aggregation liquid adhesion process and the ink composition adhesion process are performed simultaneously. It may be provided. By using the first recording method, it is possible to improve the rubbing resistance and image quality (bleed suppression) of the obtained recorded matter while maintaining excellent ejection stability. According to the first recording method of this embodiment, in addition to excellent ejection stability, abrasion resistance, and image quality (bleed suppression), it is possible to obtain a recorded matter that is excellent in glossiness.

  Other forms of the recording method of the present embodiment (hereinafter referred to as “second recording method”) include an aggregating liquid attaching step for adhering the aggregating liquid to a recording medium, a colorant, water, an organic solvent, and polymer particles. And an ink composition attaching step for attaching the ink composition containing the ink composition to a recording medium having a surface temperature of 38 ° C. or lower. In the ink composition used in the second recording method, the organic solvent includes an organic solvent having a normal boiling point of 150 ° C. or higher and 250 ° C. or lower, and is an alkyl polyol having a standard boiling point of 280 ° C. or higher. The content of is 2.0% by mass or less, preferably 0.5% by mass or less, based on the total amount of the ink composition. By using the second recording method, it is possible to improve the rubbing resistance and image quality (bleed suppression) of the obtained recorded matter while maintaining excellent ejection stability. According to the second recording method of the present embodiment, in addition to excellent ejection stability, abrasion resistance, and image quality (bleed suppression), it is possible to obtain a recorded matter that is excellent in glossiness. That is, the second recording method includes, in the ink composition used, an organic solvent having an organic solvent whose standard boiling point is 150 ° C. or more and 250 ° C. or less and which is an alkyl polyol having a standard boiling point of 280 ° C. or more. In addition to the amount being 2.0% by mass or less, preferably 0.5% by mass or less, based on the total amount of the ink composition, the surface temperature of the recording medium is 38 ° C. or less, and the polymer particles are the core described above -Even if it is not limited to the one having a shell structure, it is possible to improve the abrasion resistance and image quality (bleed suppression) of the recorded matter while maintaining excellent ejection stability as compared with the conventional recording method. it can.

The polymer particles in the second recording method preferably contain at least an aromatic monomer unit as a constituent unit. When the shell polymer contains an aromatic monomer as a structural unit, the discharge stability tends to be more excellent.
Since the color material, water, organic solvent, polymer particles, and optionally used components included in the ink composition of the second recording method may be the same as those of the ink composition of the present embodiment except for the above, Detailed description here is omitted. The second recording method can be the same as that related to the first recording method except for the configuration characteristic of the second recording method described above, but can be independent of the first recording method. it can.

  Hereinafter, the aggregation liquid adhesion step and the ink composition adhesion step in the first and second recording methods will be described together.

[Aggregating liquid adhesion process]
The aggregation liquid attaching step is a step of attaching the aggregation liquid to the recording medium. The means for attaching the aggregating liquid is not particularly limited, and for example, roller coating, spray coating, or an ink jet method can be used. Among these, it is preferable to make it adhere by an inkjet system. By adhering the aggregating liquid by an ink jet method, there is a tendency that the surface quality change of the media is suppressed and the abrasion resistance is further improved.

The adhesion amount of the aggregate liquid to the recording medium is preferably 0.01 mg / inch ^{2 to} 1.0 mg / inch ² and more preferably 0.01 mg / inch ^{2 to} 0.50 mg / inch in terms of solid content. ² or less, more preferably 0.01 mg / inch ² or more and 0.1 mg / inch ² or less. When the amount of adhesion is within the above range, the resulting printed matter tends to be more suppressed from the sticky lines and the ruled line balls.

  When the ink composition adhesion step is provided after the aggregation liquid adhesion step, the time interval from the end of the aggregation liquid adhesion step to the start of the ink composition adhesion step is preferably 10 seconds or less, more preferably 0.10 seconds. 10 seconds or less, more preferably 0.10 seconds or more and 8.0 seconds or less, particularly preferably 0.10 seconds or more and 5.0 seconds or less, and very preferably 0.10 seconds or more and 3.0 seconds or less. Less than a second. Since the time interval from the end of the aggregation liquid adhesion process to the start of the ink composition adhesion process is 10 seconds or less, the reaction efficiency between the aggregation liquid and the ink composition is further improved, and the image quality of the obtained recorded matter is further improved. It tends to improve. In particular, when the film thickness of the film made of the ink composition is small, it is preferable that the time interval is short. The aggregation liquid may be adhered to the heated recording medium in the same manner as the primary heating process performed in the ink composition adhesion process described later in the aggregation liquid adhesion process. In this case, the surface temperature of the recording medium is preferably set to the same temperature as in the primary heating step.

[Ink composition adhesion process]
The ink composition attaching step is a step of attaching the ink composition to the recording medium, and can be provided simultaneously with or before or after the above-described aggregated liquid attaching step. From the viewpoint of more effectively and surely providing, it is preferable to provide after the aggregation liquid adhesion step. The means for attaching the ink composition is not particularly limited, and for example, roller coating, spray coating, and an ink jet method can be used. Among these, it is preferable to make it adhere by an inkjet system. By attaching the ink composition by an ink jet method, there is a tendency that the surface quality change of the media is suppressed and the abrasion resistance is further improved.

  From the viewpoint of further improving the abrasion resistance, the ink composition attaching step is preferably a step of attaching the ink composition to a heated recording medium. That is, it is preferable to include a step of heating the recording medium during the ink composition attaching step and / or before the ink composition attaching step. In addition, the above process is also preferable in order to dry the ink composition adhering to the recording medium at an early stage to suppress bleeding and improve image quality. The step of heating the recording medium in the step of attaching the ink composition is also called a primary heating step. The surface temperature of the heated recording medium is not limited to a lower limit, but is preferably 25 ° C. (normal temperature) or higher, more preferably 30 ° C. or higher, and further 32 ° C. or higher. Preferably, the temperature is 35 ° C. or higher. Further, the upper limit of the surface temperature is not limited, but is preferably 80 ° C or lower, more preferably 60 ° C or lower, further preferably 50 ° C or lower, and 40 ° C or lower. It is particularly preferable that the temperature is 38 ° C. or less. The second recording method may be the same as the first recording method except that the surface temperature in the ink composition attaching step is 38 ° C. or lower. In the second recording method, excellent discharge stability, abrasion resistance, image quality (bleed suppression), and even on a recording medium using the above-described ink composition and aggregating liquid and having a recording surface temperature of 38 ° C. or less, and Glossiness is obtained.

  The film thickness of the dried film after drying the recording area to which the ink composition and the aggregating liquid are adhered is preferably 0.10 to 3.0 μm, more preferably 0.10 to 2.0 μm, More preferably, it is 0.10 to 1.0 μm. When the film thickness of the dry film is 0.10 μm or more, the resulting printed matter tends to be further suppressed from being sticky and ruled lines. Moreover, when the film thickness of the dry film is 3.0 μm or less, the change in glossiness of the obtained recorded product tends to be further suppressed. Here, the “recording area” refers to an area where an image on the surface of the recording medium is formed.

The adhesion amount of the polymer particles to the recording medium is preferably 0.01 mg / inch ² or more and 0.75 mg / inch ² or less, more preferably 0.02 mg / inch ² or more and 0.6 mg / inch in terms of solid content. ² or less, more preferably not more than 0,05mg / inch ² or more 0.5 mg / inch ^2. When the adhesion amount is 0.01 mg / inch ² or more, the resulting printed matter tends to be more suppressed in the printed matter. Further, when the adhesion amount of the polymer particles to the recording area is 0.75 mg / inch ² or less, the glossiness of the obtained recorded matter tends to be more excellent.

[Recording medium]
Examples of the recording medium include an absorptive, low-absorbing, and non-absorbing recording medium. Among these, the recording medium is preferably a low absorption recording medium or a non-absorbing recording medium. When a low-absorbing recording medium or a non-absorbing recording medium is used, since the aggregating liquid is repelled on the surface and the aggregating agent is difficult to be applied uniformly, betalam and bleeding are more likely to occur. However, the present embodiment is particularly useful because the aggregation liquid can be prevented from being repelled by the ink composition. In addition, when a low-absorbing recording medium or a non-absorbing recording medium is used, the flocculant does not penetrate into the recording medium and tends to remain on the surface of the recording medium. Tend to. However, in the present embodiment, since the amount of the aggregation liquid used can be reduced by using the above-described ink composition, the stickiness of the recording surface can be improved, which is particularly advantageous.

Here, the “low-absorbing recording medium” or “non-absorbing recording medium” refers to a recording medium having a water absorption of 10 mL / m ² or less from the start of contact to 30 msec in the Bristow method. . This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method".

  Further, the non-absorbent recording medium or the low-absorbing recording medium can be classified by the wettability of the recording surface with respect to water. Specifically, a 0.5 μL water droplet is dropped on the recording surface of the recording medium, and the contact angle reduction rate (comparison of the contact angle at 0.5 milliseconds after the landing and the contact angle at 5 seconds) is measured. Can be used to characterize the recording medium. More specifically, as a property of the recording medium, the non-absorbing property of the “non-absorbing recording medium” indicates that the above-described reduction rate is less than 1%, and the low absorption of the “low-absorbing recording medium”. The property indicates that the decrease rate is 1% or more and less than 5%. Moreover, absorptivity means that said reduction rate is 5% or more. In addition, a contact angle can be measured using portable contact angle meter PCA-1 (made by Kyowa Interface Science Co., Ltd.) etc.

  The absorbent recording medium is not particularly limited. For example, plain paper such as electrophotographic paper having a high penetrability of the ink composition, inkjet paper (an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl chloride). Art paper used for general offset printing in which the ink composition has a relatively low permeability from an alcohol (PVA) or polyvinyl pyrrolidone (PVP) or other hydrophilic polymer such as an ink-absorbing layer. , Coated paper and cast paper.

  Although it does not specifically limit as a low absorptive recording medium, For example, the coated paper by which the coating layer for accepting oil-based ink was provided in the surface is mentioned. The coated paper is not particularly limited, and examples thereof include printing paper such as art paper, coated paper, and matte paper.

  The non-absorbable recording medium is not particularly limited. For example, a plastic film that does not have an ink absorbing layer, a substrate such as paper coated with plastic, or a plastic film bonded thereto Etc. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

  In addition to the above recording medium, a non-ink-absorbing or low-absorbing recording medium such as a plate of metals such as iron, silver, copper, and aluminum, or glass can also be used.

  In particular, the recording medium is preferably in the form of a roll. The roll-shaped recording medium can be used in such a manner that when recording, the recording head is scanned once relative to the recording medium and wound by a winding roller. When such a recording medium is used, when all the colors cannot be recorded by one feeding due to a large number of types of colored ink to be used, and the recording medium is recorded many times, the recording medium is recorded multiple times. On the other hand, a recorded matter can be obtained by repeating the operation of scanning the recording head relatively once and winding it with a winding roller. However, because of the roll shape, cracks tend to occur in the layer formed of the polymer in the recorded matter. When a crack occurs, the image quality of the obtained recorded matter tends to deteriorate due to the reason that the aggregate liquid penetrates into the crack. However, the coating film made of the ink composition obtained by the recording method of the present embodiment is less susceptible to cracking. Therefore, the present invention is particularly useful when a recording medium having such a shape is used.

[Recording device]
Next, a recording apparatus that can be used in the recording method of the present embodiment will be described. 1 is a side view showing an outline of an example of an inkjet recording apparatus 1 that can be used in the present embodiment. As shown in FIG. 1, the inkjet recording apparatus 1 includes a recording medium feeding unit 10, a transport unit 20, a recording unit 30, a drying device 90, and a discharge unit 70.

  Among these, the drying device 90 includes a first drying unit 40 that dries the aggregation liquid, and a second drying unit 50 that dries the recorded matter obtained by the recording method according to the present embodiment.

  Further, the feeding unit 10 is provided so that the roll-shaped recording medium F can be fed to the transport unit 20. Specifically, the feeding unit 10 includes a roll medium holder 11, and the roll medium holder 11 holds a roll-shaped recording medium F. Then, by rotating the roll-shaped recording medium F, the recording medium F can be fed to the conveyance unit 20 on the downstream side in the feeding direction Y.

  Further, the transport unit 20 is provided so that the recording medium F sent from the feeding unit 10 can be transported to the recording unit 30. Specifically, the transport unit 20 includes a first feed roller 21 and is configured to be able to transport the sent recording medium F further to the recording unit 30 on the downstream side in the feed direction Y.

  The recording unit 30 is provided so that the recording medium F sent from the transport unit 20 is coated with an aggregating liquid, and an ink composition can be discharged and recorded. Specifically, the recording unit 30 includes heads 31 and 32 that perform an aggregation liquid attaching step, a recording head 33 that performs an ink composition attaching step, and a platen 34 as a medium support portion.

  Among these, the platen 34 is provided so that the recording medium F can be supported from the back surface. The platen 34 is provided with a first drying unit 40 that dries the agglomerated liquid adhering to the recording medium F and the ink composition adhering to the recording medium F. Further, a second feed roller 43 is provided downstream of the platen 34 in the feed direction Y. The second feed roller 43 is configured to send the recorded recording medium F to the second drying unit 50 on the downstream side in the feed direction Y.

  The second drying unit 50 is configured to further dry the aggregating liquid adhering to the recording medium F and the ink composition adhering to the recording medium F. Further, a third feed roller 65 is provided in the vicinity of the outlet 64 of the second drying unit 50. The third feed roller 65 is disposed so as to be in contact with the back surface of the recording medium F, and is configured to be able to feed the recording medium F to the discharge unit 70 on the downstream side in the feeding direction Y. The process of further drying the agglomerated liquid adhering to the recording medium F and the ink composition adhering to the recording medium F is referred to as a secondary heating process. The surface temperature of the recording medium in the secondary heating step is preferably 50 to 200 ° C., more preferably 60 to 150 ° C., in order to improve the abrasion resistance of the recorded material and prevent thermal deformation of the recording medium. More preferably, it is 70-120 degreeC.

  Further, the discharge unit 70 is provided so that the recording medium F sent from the second drying unit 50 can be further sent downstream in the feed direction Y and discharged to the outside of the inkjet recording apparatus 1. Specifically, the discharge unit 70 includes a fourth feed roller 71, a fifth feed roller 72, a sixth feed roller 73, a seventh feed roller 74, and a take-up roller 75. Among these, the 4th feed roller 71 and the 5th feed roller 72 are arrange | positioned so that the surface of the recording medium F may be contacted. Moreover, the 6th feed roller 73 and the 7th feed roller 74 are arrange | positioned so that a roller pair may be comprised. The recording medium F discharged by the sixth feed roller 73 and the seventh feed roller 74 is provided so as to be taken up by the take-up roller 75.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited in any way by the following examples. In the following, “polymer particles having a core-shell structure” are referred to as “core-shell polymer particles”.

[Material for aqueous dispersion of core-shell polymer particles]
Styrene (Tg: 80 ° C)
n-Butyl acrylate (Tg: -55 ° C)
Methyl acrylate (Tg: 10 ° C)
Methyl methacrylate (Tg: 105 ° C)
Acrylic acid (Tg: 106 ° C)

[Preparation of aqueous dispersion of core-shell polymer particles]
A reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer was prepared in the reaction vessel. 100 parts by mass of ion-exchanged water was placed in the reaction vessel, and 0.2 part of ammonium persulfate as a polymerization initiator was added at 70 ° C. under a nitrogen atmosphere while stirring. Next, a monomer solution containing 13.5 parts by mass of styrene, 12.0 parts by mass of methyl acrylate, 21.0 parts by mass of methyl methacrylate, and 3.5 parts by mass of acrylic acid was prepared. The monomer solution was dropped into the reaction vessel and reacted to polymerize and prepare a shell polymer. Thereafter, a mixed solution of 0.2 parts by mass of potassium persulfate, 35.0 parts by mass of styrene, and 15.0 parts by mass of n-butyl acrylate was dropped into the reaction vessel, and a polymerization reaction was performed while stirring at 70 ° C. Then, the aqueous dispersion (polymer particle A) of the core-shell type polymer particle was prepared by neutralizing with sodium hydroxide, adjusting pH to the range of 8-8.5, and filtering with a 0.3 micrometer filter.

  Further, as shown in Table 1, except that the content ratio (unit: part by mass) of the monomers constituting the shell polymer and the core polymer was changed, the polymer particles B to I was prepared. The polymer particles (E, G) in which the components constituting the shell polymer or the core polymer are not described are polymerized in a single step without polymerizing the shell polymer to prepare single layer polymer particles. Was prepared.

[Average particle size]
The polymer particles obtained above were measured by “Microtrack UPA” (Nikkiso Co., Ltd.), and the average particle diameter φ (nm) of the core-shell type polymer particles was determined.

[Acid value]
For the polymer particles, the acid value of the core polymer was determined from the following formula.
Acid value of core polymer (mgKOH / g) = acrylic acid (parts by mass) used for core polymer / total core polymer (parts by mass) /72.06×56.11×1000
Further, the acid value of the shell polymer was determined from the same formula except that the core polymer was replaced with the shell polymer in the above formula.

[Tg]
The polymer particles obtained above are subjected to differential scanning calorimetry (DSC) in accordance with JIS K7121, and the glass transition temperature (Tg, unit: ° C) of the polymer constituting the core polymer and the polymer constituting the shell polymer are respectively determined. Asked. A model “DSC 6220” manufactured by Seiko Denshi Co., Ltd. was used as the differential scanning calorimeter.

  In Table 1, the content ratio, average particle diameter, acid value, and Tg of each monomer in the polymer particles A to I are also shown.

[Preparation of pigment dispersion]
First, a reaction vessel equipped with a stirrer, a thermometer, a reflux tube and a dropping funnel was replaced with nitrogen. Thereafter, 20 parts by mass of benzyl methacrylate, 5.0 parts by mass of 2-ethylhexyl methacrylate, 15 parts by mass of butyl methacrylate, 10 parts by mass of lauryl methacrylate, 2.0 parts by mass of methacrylic acid, and 0.3 parts by mass of t-dodecyl mercaptan were reacted. Heated to 70 ° C. in a container. Subsequently, 150 parts by weight of benzyl methacrylate, 15 parts by weight of acrylic acid, 50 parts by weight of butyl methacrylate, 1.0 part by weight of t-dodecyl mercaptan, 20 parts by weight of methyl ethyl ketone and 1.0 part by weight of azobisisobutyronitrile were prepared. The mixed polymer was put into a dropping funnel and the dispersion polymer was polymerized while being dropped into the reaction vessel over 4 hours. Next, methyl ethyl ketone was added to the reaction vessel to prepare a dispersion polymer solution having a concentration of 40% by mass.

  40 parts by mass of the dispersed polymer solution, Chromofine Blue as a cyan pigment C.I. I. Pigment Blue 15: 3 (trade name, manufactured by Dainichi Seika Kogyo Co., Ltd.) 30 parts, 100 parts by weight of a 0.1 mol / L sodium hydroxide aqueous solution, and 30 parts by weight of methyl ethyl ketone were mixed to obtain an optimizer 25005 (Sugino Machine Co., Ltd.). (Manufactured by the company) 8 pass distributed processing. After adding 300 parts by mass of ion-exchanged water to the obtained mixture and distilling off the total amount of methyl ethyl ketone and a part of the water using a rotary evaporator, the mixture was neutralized with 0.1 mol / L sodium hydroxide to pH 9 Adjusted. Next, while measuring the volume average particle size of the cyan pigment with a particle size distribution meter, the particles are dispersed until the volume average particle size becomes 100 nm, and then filtered through a 3.0 μm membrane filter to obtain a solid content (with the dispersed polymer). A pigment dispersion having a pigment) of 20% by mass was obtained.

[Material for ink composition]
The main materials for the ink composition used in the preparation of the following recorded matter are as follows.
[Color material]
The pigment dispersion (organic solvent)
1,2-hexanediol (standard boiling point: 223 ° C)
Propylene glycol (standard boiling point: 188 ° C)
2-pyrrolidone (standard boiling point: 245 ° C)
Glycerin (standard boiling point: 290 ° C)
[Polymer particles]
Aqueous dispersions A to I of core-shell polymer particles
〔wax〕
AQUACER 593 (trade name, manufactured by Big Chemie)
[Surfactant]
BYK348 (trade name, manufactured by Big Chemie)

[Preparation of ink composition]
Each material was mixed with the composition shown in Table 2 below, and stirred sufficiently to obtain an ink composition. In Table 2 below, the numerical unit is mass%, and the total is 100.0 mass%.

[Material for flocculant]
The main materials for the aggregating liquid used in the production of the following recorded matter are as follows.
[Flocculant]
Magnesium sulfate allylamine resin (product name “PAA-HCL-01” manufactured by Nitto Bo Chemical Co., Ltd.)
〔solvent〕
Propylene glycol 2-pyrrolidone [surfactant]
BYK348 (trade name, manufactured by Big Chemie)

[Preparation of flocculant]
Each material was mixed with the composition shown in Table 3 below and stirred sufficiently to obtain an agglomerated liquid. In Table 3 below, the numerical unit is mass%, and the total is 100.0 mass%.

[Preparation of recorded material]
An ink jet printer, which is a modified machine of PX-G930 (trade name, manufactured by Epson) with a heater attached to the platen, is prepared, and the surface temperature of the recording medium in the platen is the primary heating temperature shown in Tables 4 and 5 Adjusted with a heater. Next, the recording medium was transferred to a printer, and the aggregate liquid filled in the head was applied by an inkjet method with a resolution of 720 × 720 dpi and an adhesion amount of 1.7 mg / inch ² . Next, the ink composition filled in the recording head was inkjet-applied to the aggregated liquid adhesion surface with a resolution of 720 × 720 dpi and an adhesion amount of 12 mg / inch ² to obtain a recorded material on the recording medium. Thereafter, the recording medium was discharged from the printer, and the recording medium was left standing in an environment of 80 ° C. for 10 minutes and dried (secondary heating). However, in Recording Example 19, the secondary heating condition was changed from 80 ° C. to 25 ° C. (room temperature). Note that coated paper (trade name “PET50A PL Thin” manufactured by Lintec Corporation) was used as the recording medium.

[Abrasion resistance]
The obtained recorded matter is a friction material in which a white cotton cloth (JIS L 0803 compliant) is attached to a Gakushin type friction fastness tester AB-301 (trade name, manufactured by Tester Sangyo Co., Ltd.), and a load of 300 g is applied to the recorded matter. Rubbing was performed until the film was peeled off or 30 reciprocations. And the peeling of the recorded matter of the recording medium was observed visually, and the abrasion resistance was evaluated according to the following evaluation criteria. The obtained results are shown in Tables 4 and 5.
(Evaluation criteria)
A: No scratches or peeling of recorded material was observed.
B: Scratches or peeling of the recorded matter was observed in less than 20% of the rubbed area (stroke area).
C: Scratches or peeling of recorded matter was observed in 20% or more and less than 50% of the rubbed area (stroke area).
D: Scratches or peeling of the recorded matter was observed in 50% or more and less than 90% of the rubbed area (stroke area).
E: Scratches or peeling of the recorded matter was observed in 90% or more of the rubbed area (stroke area).

[Glossiness]
Glossiness measuring instrument (GM-268Plus, manufactured by Konica Minolta Co., Ltd.) for the recorded material obtained by the same method as in [Preparation of recorded material] except that a 10 × 10 mm solid pattern was prepared. Was used to measure the glossiness at 20 ° based on JIS Z8741, and the glossiness was evaluated. Higher gloss value means better gloss. The obtained results (glossiness) are shown in Tables 4 and 5.

[Image quality (bleed)]
Except for producing a 10 × 10 mm solid pattern, the bleed of the recorded matter produced by the same method as in the above [Preparation of recorded matter] was confirmed visually, and the image quality ( (Bethamra) was evaluated. The obtained results are shown in Tables 4 and 5.
(Evaluation criteria)
A: No bleed was observed in the solid pattern and in the outline.
B: No bleed was observed inside the solid pattern, but bleed was observed in the contour portion.
C: Slight bleed was observed not only in the outline of the solid pattern but also in the inside.
D: Bleed was observed in the outline portion of the solid pattern, and the bleed was recognized slightly exceeding the amount inside.

(Discharge stability)
After the above [Preparation of recorded matter], nozzle clogging was confirmed, and ejection stability was evaluated according to the following evaluation criteria. The obtained results are shown in Tables 4 and 5.
(Evaluation criteria)
A: There was no clogging or clogging disappeared by performing head cleaning once.
B: Clogging did not disappear even after one head cleaning, but disappeared by two or three head cleanings.
C: The clogging did not disappear even after performing the head cleaning three times.

  As a result of the evaluation, the recording examples 4 and 18 using the ink composition 4 in which the content of the organic solvent, which is an alkyl polyol having a standard boiling point of 280 ° C. or higher, exceeds 2.0% by mass are slow in drying of the ink composition. It was inferior to rubbing and image quality. Similarly, in the recording example 10 using the ink composition 4, the image quality was relatively improved by considerably increasing the primary heating temperature, but the discharge stability was inferior as an adverse effect. Note that it is not preferable to raise the primary heating temperature considerably from the viewpoint of causing thermal damage to the head and reducing the durability of the head during long-term use of the head. Further, in this embodiment, it is the most important issue that the image quality of the recorded matter is excellent. In this respect, each of the above examples is inferior in that the image quality cannot be improved without any harmful effect.

In addition, the recording examples 12, 13, and 17 that did not use the aggregation liquid were inferior in image quality as in the above recording examples.
On the other hand, recording examples 1-3, 5-9, and 11 using an ink composition having an organic solvent content of 2.0 mass% or less, which is an alkyl polyol having a standard boiling point of 280 ° C. or more, and using an aggregate liquid. , 14-16, and 19 were superior to the above-described recording examples with inferior image quality in that the image quality was at least excellent.
Among them, recording examples 5, 16, and 19 using the ink composition 5 including polymer particles E that are polymer particles that are not core-shell type polymer particles and the polymer particles are made of a resin having a relatively high Tg are recorded media The film thickness of the polymer particles was inferior and the abrasion resistance was inferior.

  In addition, the recording example 7 using the ink composition 7 including polymer particles G which are polymer particles that are not core-shell type polymer particles and the polymer particles are made of a resin having a relatively low Tg is inferior in ejection stability. Is presumed that the polymer particles contained in the ink are welded to each other in the head and become a foreign matter, causing a discharge failure. This is also inferred from the fact that the ink adhering to the nozzle plate after recording was observed with a microscope and the polymer particles in the ink were welded.

  Similarly, Recording Example 15 in which the primary heating temperature was set to 35 ° C. while using the ink composition 7 and Recording Example 16 in which the primary heating temperature was set to 35 ° C. using the ink composition 5 were not core-shell type polymer particles. Despite the use of an ink composition containing polymer particles, the ejection stability was excellent. Therefore, even when an ink composition containing polymer particles that are not core-shell type polymer particles is used, recording with particularly excellent ejection stability can be performed by setting the primary heating temperature to less than 40 ° C. It was found that the image quality can be improved by using the aggregating liquid. It is presumed that the bleeding can be suppressed even when the primary heating temperature is relatively low due to the effect of suppressing the bleeding of the ink by using the aggregation liquid.

  Also, Recording Examples 1 to 3, 6, 8, and 9 using ink compositions containing core-shell type polymer particles and containing an organic solvent that is an alkyl polyol having a standard boiling point of 280 ° C. or higher is 2.0% by mass or less. 11 and 14 were particularly excellent in both abrasion resistance and ejection stability.

  Although not described in the table, recording examples 11, 15, and 16 except that the platen heater was turned off and the primary heating temperature at the time of adhering the aggregation liquid and the ink composition was 25 ° C. When recording was performed in the same manner, the image quality was D. From this, it was found that the primary heating step was performed and the primary heating temperature was preferably at least over 25 ° C. from the viewpoint of improving the image quality.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Feed part, 11 ... Roll medium holder, 20 ... Conveyance part, 21 ... 1st feed roller, 30 ... Recording part, 31 ... Head, 32 ... Head, 33 ... Recording head, 34 ... Platen, 40 ... 1st drying part, 43 ... 2nd feed roller, 50 ... 2nd drying part, 64 ... Exit, 65 ... 3rd feed roller, 70 ... Discharge part, 71 ... 4th feed roller, 72 ... 1st 5 feed roller, 73 ... 6th feed roller, 74 ... 7th feed roller, 75 ... take-up roller, 90 ... drying device, F ... recording medium, Y ... feed direction.

Claims (13)

An ink composition comprising a coloring material, water, an organic solvent, and polymer particles,
The organic solvent includes an organic solvent having a normal boiling point of 150 ° C. or more and 250 ° C. or less, and the content of the organic solvent that is an alkyl polyol having a standard boiling point of 280 ° C. or more is 2. 0% by mass or less,
The polymer particles have a core-shell structure including a core polymer and a shell polymer, and the glass transition temperature of the shell polymer is higher than the glass transition temperature of the core polymer,
An ink composition for use in a recording method for recording using the ink composition and an aggregating liquid containing an aggregating agent capable of aggregating or thickening the components of the ink composition.   2. The ink composition according to claim 1, wherein the content of the organic solvent having a standard boiling point of 280 ° C. or more is 0.5% by mass or less based on the total amount of the ink composition.   The ink composition according to claim 1, wherein an acid value of the shell polymer is higher than an acid value of the core polymer.   The acid value of the shell polymer is 20 mgKOH / g or more, and the acid value of the core polymer is at least one of 15 mgKOH / g or less, according to any one of claims 1 to 3. The ink composition as described.   The ink composition according to claim 1, wherein the shell polymer contains at least an aromatic monomer unit as a constituent unit.   The ink composition according to any one of claims 1 to 5, wherein a difference between a glass transition temperature of the core polymer and a glass transition temperature of the shell polymer is 10 ° C or higher.   The ink composition according to claim 1, wherein the flocculant is one or more selected from the group consisting of a polyvalent metal salt, an organic acid, and a cationic compound.   An aggregating liquid containing an adhesion step for adhering the ink composition to a recording medium and an aggregating agent capable of aggregating or thickening the components of the ink composition according to claim 1. A recording method comprising: an attaching step of attaching the material to a recording medium.   The recording method according to claim 8, wherein the attaching step is a step of attaching at least the ink composition to a recording medium by an inkjet method.   The recording method according to claim 8 or 9, wherein the attaching step of attaching the ink composition to a recording medium is a step of attaching the ink composition to a heated recording medium. An aggregating liquid adhering step for adhering an aggregating liquid containing an aggregating agent capable of aggregating or thickening the components of the ink composition to a recording medium;
An ink composition attaching step for attaching an ink composition containing a colorant, water, an organic solvent, and polymer particles to a recording medium having a surface temperature of 38 ° C. or less,
In the ink composition, the organic solvent includes an organic solvent having a normal boiling point of 150 ° C. or higher and 250 ° C. or lower, and the content of the organic solvent which is an alkyl polyol having a standard boiling point of 280 ° C. or higher is the total amount of the ink composition. The recording method which is 2.0 mass% or less with respect to.   The recording method according to claim 11, wherein the polymer particles contain at least an aromatic monomer unit as a constituent unit.   The recording method according to claim 10, wherein the attaching step of attaching the ink composition to a recording medium is a step of heating the ink composition to attach to a recording medium having a temperature of 30 to 50 ° C. .

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