JP6977248B2 - Recording method and recording device - Google Patents

Description

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

The inkjet recording method is a relatively simple device that can record high-definition images, and is rapidly developing in various fields. Among them, various studies have been made on obtaining more stable and high-quality recorded materials.

For example, Patent Document 1 describes an ink for inkjet, which is an ink for inkjet, for the purpose of providing an ink having excellent drying property of the ink and excellent storage stability of the ink during quick printing. It is intended to be used together with a reaction solution for curing, and contains 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 covering the core portion, and is a shell portion. Disclosed is an ink for inkjet, which has a reactive group that reacts with a reaction solution on the surface of the ink, and has a MFT (minimum film forming temperature) of a shell portion higher than that of an MFT of a core portion.

Japanese Unexamined Patent Publication No. 2013-204525

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

Therefore, the present invention has been made to solve at least a part of the above-mentioned problems, and while maintaining excellent ejection stability when the coagulant and the ink composition are adhered to the recording medium. The first object is to provide an ink composition having excellent scratch resistance and suppressing bleeding of recorded matter. The present invention also provides a recording method in which bleeding of a recorded material is suppressed while maintaining excellent ejection stability when the aggregated liquid and the ink composition are adhered to a recording medium at 38 ° C. or lower. That is the second purpose. Bleed is a state in which when the ink droplets of the ink composition adhered to the recording medium in the form of dots come into contact with each other, the ink between the ink droplets flows and the image becomes unclear, or the ink droplets have different colors from each other. In the case of the ink composition of No. 1, the image becomes unclear due to further color mixing between dots.

As a result of diligent studies to solve the above problems, the present inventors have included a coloring material, water, an organic solvent, and polymer particles, and the organic solvent contains an organic solvent having a standard boiling point within a predetermined range, and an alkyl polyol. The content of the organic solvent is not more than a predetermined amount, 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 a high-quality ink composition in a recording method for recording using the ink composition and a coagulant containing a coagulant capable of coagulating or thickening the components of the ink composition, ejection stability is achieved. The present invention has been completed by finding excellent properties, scratch resistance and image quality.

That is, the present invention is an ink composition containing a coloring material, water, an organic solvent, and polymer particles, and the organic solvent contains an organic solvent having a standard boiling point of 150 ° C. or higher and 250 ° C. or lower, and has a standard boiling point. The content of the organic solvent, which is an alkyl polyol at 280 ° C. or higher, is 2.0% by mass or less with respect to the total amount of the ink composition, and the polymer particles are core-shells comprising a core polymer and a shell polymer. A flocculant having a structure, having a glass transition temperature of the shell polymer higher than the glass transition temperature of the core polymer, and capable of aggregating or thickening the ink composition and the components of the ink composition. It is an ink composition used in a recording method for recording using a coagulating liquid contained therein. The factors by which such an ink composition can solve the problem of the present invention are considered as follows. However, the factors are not limited to this. That is, the ink composition of the present invention mainly contains polymer particles in which the glass transition temperature of the shell polymer is higher than the glass transition temperature of the core polymer, so that the recording is recorded using the ink composition and the agglomerate. When used in the method, it is excellent in ejection stability because it suppresses the welding of polymer particles to the ink jet head (a state in which the polymer particles adhere to the surface and are difficult to be easily removed. Sticking). Further, the ink composition of the present invention is excellent in abrasion resistance mainly because the core polymer in the polymer particles landed on the recording medium flows out due to the impact or heating of the landing. Further, in this ink composition, the content of an alkyl polyol having a standard boiling point of an organic solvent of 150 ° C. or higher and 250 ° C. or lower and a standard boiling point of 280 ° C. or higher is 2.0 with respect to the total amount of the ink composition. When the mass is less than% by mass, the dryness of the ink composition landed on the recording medium is improved, so that the abrasion resistance is further improved and the bleeding of the recorded material is suppressed.

Further, in the ink composition of the present invention, the content of the organic solvent having a standard boiling point of 280 ° C. or higher is preferably 0.5% by mass or less with respect to the total amount of the ink composition, and the acid of the shell polymer. The value is preferably higher than the acid value of the core polymer, and the acid value of the shell polymer is at least 20 mgKOH / g or less, and the acid value of the core polymer is at least 15 mgKOH / g or less. On the other hand, it is more preferable that the shell polymer contains at least an aromatic monomer unit as a constituent 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 higher. It is more preferable that the flocculant is one or more selected from the group consisting of polyvalent metal salts, organic acids, and cationic compounds.

Further, in one aspect of the recording method of the present invention, the ink composition and a coagulating liquid containing a coagulant capable of coagulating or thickening the components of the ink composition are adhered to the recording medium. It has an adhesion step, and it is preferable that the adhesion step is at least a step of adhering the ink composition to a recording medium by an inkjet method, and the adhesion step is a step of adhering the ink composition to a heated recording medium. It is preferable that it is a step of adhering.

In addition, another aspect of the recording method of the present invention includes a coagulant adhering step of adhering a coagulant containing a coagulant capable of agglomerating or thickening the components of the ink composition to the recording medium, and a color. The ink composition comprises an ink composition adhering step of 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 lower. The organic solvent contains an organic solvent having a standard 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 based on the total amount of the ink composition. It is preferably 0.5% by mass or less, and the polymer particles preferably contain at least an aromatic monomer unit as a constituent unit.
Further, in another aspect of the recording method of the present invention, the adhesion step of adhering the ink composition to the recording medium is a step of heating the ink composition to adhere it to the recording medium having a temperature of 30 to 50 ° C. It is preferable to use a recording method.

It is a side view which shows the whole outline of the example of the inkjet recording apparatus which can be used in this embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiments”) will be described in detail with reference to the drawings as necessary, but the present invention is not limited thereto and is a gist thereof. Various deformations are possible within the range that does not deviate from. In the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

[Ink composition]
The ink composition of the present embodiment contains a coloring material, water, an organic solvent, and polymer particles, and agglomerates containing the ink composition and a coagulant capable of coagulating or thickening the components of the ink composition. It is used as a recording method for recording with liquid. Further, the organic solvent contains an organic solvent having a standard 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 based on the total amount of the ink composition. , 2.0% by mass or less. Further, 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. It is excellent to use such an ink composition in a recording method for recording using the ink composition and a coagulant containing a coagulant capable of coagulating or thickening the components of the ink composition. While maintaining the ejection stability, the scratch resistance and image quality (bleed suppression) of the obtained recorded material are improved. The ink composition of the present embodiment is excellent in glossiness in addition to excellent ejection stability, abrasion resistance, and image quality (bleeding suppression).

<Color material>
Pigments can be used as the coloring material. The pigment is not particularly limited, and examples thereof include the following.

The carbon black used for the black ink is not particularly limited, but for example, No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B, etc. (above, manufactured by Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. , Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color Black Def Examples thereof include Black 4A and Special Black 4 (all manufactured by Degussa).

The pigment used for the white ink is not particularly limited, but 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.

The pigment used for the yellow ink is not particularly limited, but 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 can be mentioned.

The pigment used in the magenta ink is not particularly limited, but 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.

The pigment used for the cyan ink is not particularly limited, but 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 can be mentioned.

The pigments other than the above are not particularly limited, but for example, C.I. 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 coloring material preferably contains one or more pigments selected from the group consisting of self-dispersion pigments and polymer dispersion pigments. As a result, the coloring material tends to be more excellent in gloss due to being uniformly dispersed in the recorded material.

The self-dispersion pigment is a pigment having a hydrophilic group on its surface. Hydrophilic groups include -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, a phenyl group which may have a substituent, or an organic ammonium, and R is an alkyl group or a substituent having 1 to 12 carbon atoms. Represents a naphthyl group which may have a group. Further, the above M and R are selected independently of each other.

Specifically, the self-dispersion pigment is produced by subjecting the pigment to a physical treatment and / or a chemical treatment to bond (graft) the hydrophilic group to the surface of the pigment. Specific examples of the physical treatment include vacuum plasma treatment. In addition, specific examples of the chemical treatment include a wet oxidation method in which oxidation is carried out in water with an oxidizing agent, 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. Be done.

The above-mentioned polymer-dispersed pigment is a pigment that can be dispersed in a liquid by a polymer. The content of the polymer with respect to the pigment can be expressed as the coverage of the polymer that coats the pigment. The coverage of the polymer is preferably 1.0% or more and 50% or less, more preferably 1.0% or more and 10% or less, and further preferably 1.0% or more and 5.0% or less. When this coverage is 1.0% or more, the dispersibility tends to be good. Further, when the coverage is 50% or less, the color-developing property tends to be further improved, and when the coverage is 5.0% or less, the color-developing property tends to be further improved. be.

It is preferable that 70% by mass or more of the constituent components of the polymer is a polymer obtained by copolymerizing (meth) acrylate and (meth) acrylic acid. As a result, the fixability and glossiness of the ink tend to be further improved. Further, 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. Specific examples of the monomer component include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth). Meta) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, lauryl (meth) acrylate, isobolonyl (meth) acrylate , Cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetramethylpiperidyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxy ( Examples thereof include meth) acrylate and behenyl (meth) acrylate. Further, as other monomer components for polymerization, hydroxy (meth) acrylate having a hydroxyl group such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and diethylene glycol (meth) acrylate, urethane (meth) acrylate, and epoxy (meth). ) Acrylate and the like can also be mentioned. In addition, in this 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 with respect to the total amount (100% by mass) of the ink composition. It is 0.0% by mass or less, more preferably 1.0% by mass or more and 3.0% by mass or less. When the content of the coloring material is within the above range, the color-developing property tends to be further improved.

<Water>
Examples of the water of the present embodiment include pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water, and water in which ionic impurities such as ultrapure water are removed as much as possible. .. Further, when water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide or the like is used, it is possible to prevent the growth of mold and bacteria when the aggregated liquid is stored for a long period of time. This tends to further improve storage stability. The content of water in the ink composition is preferably 40 to 97% by mass, more preferably 45 to 90% by mass, and even more preferably 50 to 80% by mass. Further, it is preferable that the ink composition of the present embodiment is a water-based ink composition containing at least water as a main solvent component contained in the ink composition in terms of excellent drying property of the ink in a recording medium and low addition to the environment. ..

〔Organic solvent〕
The organic solvent of the present embodiment preferably contains an organic solvent having a standard boiling point of 150 ° C. or higher and 250 ° C. or lower, and preferably contains an organic solvent having a standard boiling point of 180 ° C. or higher and 250 ° C. or lower.
Further, the content of the organic solvent which 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. It is more preferably 0.5% by mass or less, and more preferably 0.2% by mass or less. As a result, excellent abrasion resistance and image quality (suppression of bleeding) can be obtained because the drying property of the ink composition landed on the recording medium can be obtained at a higher level.

The type of the organic solvent is not particularly limited, and examples thereof include cyclic nitrogen compounds, aprotic polar solvents, monoalcohols, alkyl polyols, and glycol ethers. As the organic solvent of the present embodiment, various organic solvents having a standard boiling point of 150 ° C. or higher and 250 ° C. or lower can be appropriately selected from these organic solvents and used. Further, the ink composition preferably does not contain an organic solvent which is an alkyl polyol having a standard boiling point of 280 ° C. or higher, but if the content thereof is 2.0% by mass or less with respect to the total amount of the ink composition. It is more preferably 1.0% by mass or less, further 0.5% by mass or less, and further preferably 0.2% by mass or less. Further, from the viewpoint of scratch resistance and glossiness, it is more preferable that the ink composition 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 polyol). It is more preferable if the content is 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 even more preferable. Further, it is more preferable to set the content of the organic solvent having a standard boiling point of more than 250 ° C. in the above range. For example, the content thereof 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. By containing a cyclic nitrogen compound or an aprotic polar solvent, the ink composition can shift the apparent glass transition temperature of the polymer particles to the lower temperature side, and softens the core polymer and the shell polymer at a lower temperature than originally intended. Therefore, there is a tendency that the fixability of the ink composition on the recording medium can be improved. This makes it possible to improve the fixability of the ink composition on the recording medium, particularly when the recording medium is made of polyvinyl chloride.

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-based, imidazolidinone-based, sulfoxide-based, lactone-based, and amide ether-based 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.

The monoalcohol is not particularly limited, but is, for example, methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pen. Examples include tanol, 3-pentanol, and tert-pentanol.

The alkyl polyol is not particularly limited, and is, for example, glycerin, 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-Pentinediol, 1,5-Pentanediol, 2-Methyl-2,4-Pentanediol, 1,2-Hexanediol, 1,6-Hexylenediol, 2-Ethyl-1,3-Hexanediol, 1 , 7-Heptanediol, and 1,8-octanediol.

The glycol ether is not particularly limited, but 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 mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-propyl ether, and dipropylene glycol mono-iso-propyl ether. ..

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, and further, the content of the organic solvent is preferably 5.0% by mass or more and 50% by mass or less with respect to the total amount (100% by mass) of the ink composition. Preferably, it is 13% by mass or more and 25% by mass or less. When the content of the organic solvent is 50% by mass or less, the drying property of the ink composition adhering to the recording medium tends to be further improved. Further, 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. Further, the content of the organic solvent having a standard boiling point of 150 ° C. or higher and 250 ° C. or lower is preferably 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 preferably 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, the ejection stability can be improved, and the core resin is increased when the recording medium is heated after the adhesion step. It is easy to form a film and the scratch resistance of the recorded material can be made excellent, and the ejection stability and the scratch resistance of the ink composition can be made excellent as a whole. In this respect, it is advantageous to lower the Tg of the core polymer and increase the Tg of the shell polymer.
The "core-shell structure" refers to a structure in which the core polymer is formed inside the voids of the shell polymer. Therefore, not only the structure in which the surface of the core polymer is covered with the shell polymer but also the structure in which the core polymer is filled in a part of the voids of the three-dimensional network structure by the shell polymer is included. Therefore, the “core-shell structure” as used herein also includes polymer particles in which the boundary between the core portion and the shell portion is not strictly clear. However, in the second recording method described later, the polymer particles of the present embodiment are not limited to the polymer particles having a core-shell structure, and may be single-layer particles containing only one kind of polymer. The particles may be a mixture of two or more kinds of polymers (however, they do not have a core-shell structure). Of course, the polymer particles of the present 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 the above-mentioned polymer particles made of only the core resin or the 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 a (meth) acrylic monomer as a constituent unit at least. Examples thereof include polyurethane resin, polyether resin, polyester resin, and composite resins thereof.

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 the scratch resistance tends to be better. Further, when the glass transition temperature of the core polymer is 0 ° C. or higher, the storage stability of the ink composition tends to be more excellent.

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, the method described in Examples described later is used. Further, it can be calculated from Tg of a known homopolymer of a polymerizable monomer using a calculation formula and 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 formula.

Here 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 if 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 formula. For example, the resin may be designed according to the above formula, and the prepared resin may be redesigned by measuring the actual Tg and feeding it back so as to approach the target Tg.

More preferably, the core polymer has no acid value. Further, the core polymer preferably contains at least an aromatic monomer unit as a constituent unit. As a result, the core polymer becomes more hydrophobic than the polymer containing no aromatic monomer unit, so that a more hydrophobic film can be formed on the recording medium. As a result, the scratch resistance of the recorded material tends to be further improved. Here, the "constituent unit" is a unit constituting the polymer, and the "monomer unit" means a constituent 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.

The aromatic monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, and divinylbenzene.

The core polymer is not particularly limited, but as a constituent 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, and a hydrophobic having a cyclic structure. It preferably contains at least one of a sex (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, and for example, methyl (meth) acrylate, ethyl (meth) acrylate, α-hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (poly). Examples thereof include ethylene glycol (meth) acrylate, methoxy (poly) ethylene glycol (meth) acrylate, ethoxy (poly) ethylene glycol (meth) acrylate, and (poly) propylene glycol (meth) acrylate. Of these, methyl (meth) acrylate and ethyl (meth) acrylate are preferable. Here, "hydrophilic" means that the solubility in 100 mL (20 ° C.) of water is 0.3 g or more. Since the core polymer contains a hydrophilic (meth) acrylate monomer as a monomer unit, the polymerization reactivity in producing the core polymer tends to be excellent.

The hydrophobic (meth) acrylate monomer having an alkyl group having 3 or more carbon atoms is not particularly limited, and is, for example, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl. (Meta) 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 (meth) acrylate having an alkyl group having 3 or more carbon atoms such as acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cetyl (meth) acrylate, neopentyl (meth) acrylate, and behenyl (meth) acrylate Can be mentioned. Of these, lauryl (meth) acrylate is preferable. Here, "hydrophobicity" means that the solubility in 100 mL (20 ° C.) of water is less than 0.3 g.

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

The (meth) acrylamide monomer or its N-substituted derivative is not particularly limited, and is, for example, (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, diacetone acrylamide, and N, N-dimethylacrylic (meth) amide. Etc. (meth) acrylamide or N-substituted derivatives thereof.

As described above, it is preferable not to use a carboxylic acid monomer for the core polymer, but it is also possible to use a carboxylic acid monomer to the extent that the abrasion resistance of the recorded material can be maintained at a predetermined level or higher. The carboxylic acid monomer is not particularly limited, and examples thereof include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. Of these, (meth) acrylic acid is preferable. Here, the "carboxylic acid monomer unit" means a polymerizable monomer unit having a carboxyl group and a polymerizable unsaturated group.

The above-mentioned monomers may be used alone or in combination of two or more.

When the core polymer contains hydrophobic monomer units, the content of the hydrophobic monomer units is preferably 60% by mass or more among all the constituent 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 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 ink composition is ejected in a high temperature environment because 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 type structure. Is possible. As a result, the adhesion of polymer particles in the nozzle can be further suppressed, so that clogging of the nozzle tends to be further suppressed. Further, when the glass transition temperature of the shell polymer is 150 ° C. or lower, the shell polymer is easily softened on the recording medium, and therefore tends to be more excellent in abrasion resistance. After the ink composition is landed on the recording medium, the ink composition on the recording medium is heated to a temperature higher than the glass transition temperature of the shell polymer, so that the core polymer flows out from the softened shell polymer and the core is formed. A polymer and shell polymer coating is formed on the recording medium. At this time, the softened core polymer spreads and adheres to the recording medium, so that 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, it is preferable that the difference between the glass transition temperature of the shell polymer and the glass transition temperature of the core polymer is 10 ° C. or more.

The shell polymer is preferably hydrophilic and more preferably has an acid value. As a result, even when the water dries in the recording head and on the recording medium and the occupancy rate of the organic solvent becomes high, 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 secure more sufficient hydrophilicity as a shell polymer.

The acid value of the shell polymer is preferably higher than the acid value of the core polymer. As a result, the shell polymer tends to be more hydrophilic than the core polymer, so that the aggregation of the polymers can be further suppressed and the abrasion resistance can be further improved. 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 of them. The acid value of the core polymer and the acid value of the shell polymer are calculated from the type and amount of the monomer used for each. Specifically, it is obtained in the same manner as the method described in Examples described later.

From the same viewpoint as 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. It is less than or equal to g.

The shell polymer preferably contains at least an aromatic monomer unit as a constituent unit. Since the shell polymer contains an aromatic monomer as a constituent unit, although the detailed mechanism of action is unknown, the discharge bending tends to be suppressed. In particular, since the ink droplets tend to bend when the dots are small, this ejection bending is suppressed according to one aspect of the present embodiment. Therefore, one aspect of the ink composition of the present embodiment is particularly suitable for a recording head capable of ejecting ink dots in multiple sizes from one nozzle. Further, since 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.

Further, the shell polymer preferably contains a (meth) acrylate monomer unit and a carboxylic acid monomer unit as constituent units. 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, and is, 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 (meth) acrylate monomer having a cyclic structure. Meta) acrylate monomers can be mentioned. Specific examples of the (meth) acrylate monomer and the carboxylic acid monomer include the same monomers constituting the resin contained in the core polymer, and even if one type of monomer is used alone, two or more types are used. It may be used 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. Is. As a result, an ink composition having an excellent balance between the improvement in scratch resistance due to the aromatic monomer and the redispersibility due to 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 in the total constituent units of the shell polymer is 20% by mass or more is preferable, 30% by mass or more is more preferable, and 35% by mass or more is further 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 among all the constituent units of the shell polymer is preferably 20% by mass or more and 90% by mass or less, and 30% by mass or more and 80% by mass or less. More preferably, it is more preferably 35% by mass or more and 70% by mass or less. When the content of the hydrophilic monomer unit is at least the above lower limit value, the shell polymer has hydration property, so that the dispersion stability of the polymer particles in the ink composition tends to be further improved. Further, since the polymer particles can be more effectively suppressed from adhering to the nozzle, the ejection stability of the recording head from the nozzle tends to be better. On the other hand, when the content of the hydrophilic monomer unit is not more than the above upper limit value, the polymer particles are dispersed even when the water dries in the recording head and on the recording medium and the occupancy rate of the organic solvent becomes high. Is stable, and there is a tendency that the aggregation of polymer particles can be further suppressed.

When the shell polymer contains a hydrophobic monomer unit, the content of the hydrophobic monomer unit among all the constituent units of the shell polymer is preferably 10% by mass or more and 80% by mass or less, and 20% by mass or more and 70% by mass or less. More preferably, it is more preferably 30% by mass or more and 65% by mass or less. When the content of the hydrophobic monomer unit is at least the above lower limit, the dispersion of the polymer particles is stable even when the water dries in the recording head and on the recording medium and the occupancy of the organic solvent increases. However, there is a tendency that the aggregation of the polymer particles can be further suppressed. 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 property, so that the dispersion stability of the polymer particles in the ink composition tends to be further improved. Further, since the polymer particles can be more effectively suppressed from adhering to the nozzle, the ejection stability of the recording head from the nozzle tends to be better.

Preferably, the polymer particles, together with the core polymer and the shell polymer, contain 10% by mass or more and 80% by mass or less (based on the mass of the entire polymer particles) the aromatic monomer as a constituent unit. By containing 10% by mass or more of a relatively hard aromatic monomer, the scratch resistance of the recorded material formed on the recording medium tends to be further improved. Further, by containing 80% by mass or less of the aromatic monomer, the discharge stability tends to be further improved.

The average particle size 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. When the average particle size of the polymer particles is 100 nm or less as described above, it is easy to obtain excellent glossiness of the recorded material, and the ink composition tends to be more excellent in film forming property on the recording medium. Further, since the average particle size of the polymer particles is 100 nm or less, it is difficult for large lumps to be formed even if they are aggregated, so that clogging of the nozzle tends to be further suppressed. Furthermore, since the average particle size 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 ejection property is poor. There is a tendency to prevent the viscosity from decreasing as it becomes stable. On the other hand, when the average particle size of the polymer particles is 10 nm or more, the preparation of the polymer particles tends to be easier.

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

The relationship between the mass of the core polymer and the mass of the shell polymer in the polymer particles is preferably such that (mass of the core-shell polymer) ≤ (mass of the shell polymer), and more preferably (mass of the core-shell polymer) <(shell). It is a relationship that becomes the mass of the 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. As a result, the balance between the mass of the core polymer and the mass of the shell polymer becomes better, so that the fixing property of the ink composition becomes better, the ejection stability is further improved, and the vertical alignment failure tends to be less likely to occur. Here, the "vertical alignment defect" is a phenomenon in which, in continuous ink ejection, the ink is partially solidified around the nozzle due to long-term ejection, and the ejection direction is bent to make it impossible to print a clean vertical line.

The content (in terms of solid content) of the polymer particles in the ink composition 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. It is more preferably 5% by mass or less, and further preferably 1.5% by mass or more and 5.0% by 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. Further, when the content of the polymer particles is 20% by mass or less, the ejection stability tends to be better.

<Manufacturing method of polymer particles>
The method for producing 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 using substantially no emulsifier. preferable. Soap-free polymerization refers to a polymerization method for producing a core-shell polymer without substantially using an emulsifier. The "emulsifier" here means a surfactant used in synthesis. In addition, examples of soap-free polymerization include polymerizing polymer particles in the presence of an emulsifier content of 1% by mass or less in a solution. 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. Further, when the polymer particles are produced by using soap-free polymerization, the average particle size becomes very small, and the ejection stability and glossiness of the ink composition tend to be further improved.

The surfactant used for the synthesis is not particularly limited, but an anionic surfactant and a nonionic surfactant are suitable. The anionic surfactant is not particularly limited, and examples thereof include sodium dodecylbenzylsulfonate, sodium laurate, and ammonium salts of polyoxyethylene alkyl ether sulfate. The nonionic surfactant is not particularly limited, and is, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, and polyoxy. Examples include ethylene alkyl amide.

The polymerization initiator used in the polymerization is not particularly limited, but a hydrophilic initiator is used, and examples thereof include potassium persulfate, ammonium persulfate, and hydrogen peroxide solution.

An example of the soap-free polymerization method will be described below, but the polymerization method is not limited to the following. For example, ion-exchanged water and a polymerization initiator are put in a polymerization reaction tank with a jacket, the inside of the polymerization tank is depressurized to remove oxygen, and then the pressure is returned to atmospheric pressure with nitrogen to make the inside of the polymerization reaction tank a nitrogen atmosphere. .. Under the nitrogen atmosphere, the inside of the polymerization reaction tank is first brought to a predetermined temperature, and then a pre-emulsion solution containing a monomer which is a component of the shell polymer is dropped in a fixed amount to carry out a polymerization reaction to synthesize a shell polymer. .. Next, the core polymer is polymerized using the voids of the obtained shell polymer as a polymerization field to synthesize the polymer particles according to the present 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 obtain polymer particles. As described above, when the shell polymer is used as the polymerization field of the core polymer, it is not necessary to use an emulsifier for the monomer mixture.

<Wax>
The ink composition of the present embodiment preferably further contains wax. When the recording head is heated, the polymer particles are aggregated and fixed as the water evaporates, which may cause nozzle clogging of the recording head and hinder stable ejection. On the other hand, the inclusion of wax tends to suppress the aggregation of polymer particles during water evaporation. As a result, it is possible to suppress ejection defects and clogging due to the sticking of the polymer particles to the nozzle of the recording head, and the ink composition is excellent in recording stability. Further, at the time of high temperature recording, the wax tends to prevent the coating film due to the polymer particles from becoming too brittle. Therefore, 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., and more preferably 80 ° C. or higher and 110 ° C. or lower. When the melting point is in the above range, it tends to be possible to obtain a recorded material which is superior in recording stability and whose abrasion resistance is less likely to deteriorate even at high temperature recording. The melting point can be measured by a differential scanning calorimeter (DSC). Further, the melting point of the wax can be controlled, for example, by adjusting the ratio of a plurality of constituent units constituting the wax.

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 size is in the above range, the recording stability is more excellent, and the abrasion resistance tends to be less likely to deteriorate even at high temperature recording. The average particle size 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. The polyethylene wax is not particularly limited, but for example, AQUACER593 polyolefin wax (manufactured by BYK), Nopcoat PEM-17 (manufactured by San Nopco) Polylon L787, Polylon L788 (all manufactured by Chukyo Oil & Fat Co., Ltd.), and Chemipearl W4005 (Mitsui Chemicals). (Manufactured by the company). The wax may be synthesized by a conventional method. The wax may be used alone or in combination of two or more.

The content of wax in the ink composition (in terms of solid content) is preferably 0.1% by mass or more and 2.5% by mass or less, more preferably 0, with respect to 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 is more excellent, and the abrasion resistance tends to be less likely to deteriorate even at the time of high temperature recording.

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

The acetylene glycol-based surfactant is not particularly limited, but is 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-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol. The above is preferable. Commercially available products of acetylene glycol-based surfactants are not particularly limited, but for example, E series such as Orfin 104 series and Orfin E1010 (trade name manufactured by Air Products Japan, Inc.), Surfinol 104, and the like. 465, 61, DF110D (trade name manufactured by Nissin Chemical Industry CO., Ltd.) can be mentioned. The acetylene glycol-based surfactant may be used alone or in combination of two or more.

The fluorosurfactant is not particularly limited, and is, for example, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate ester, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, and the like. Perfluoroalkylamine oxide compounds can be mentioned. The commercially available product of the fluorine-based surfactant is not particularly limited, but for example, S-144, S-145 (trade name, manufactured by Asahi Glass Co., Ltd.); FC-170C, FC-430, Florard-FC4430 (the above product). Name: FSO, FSO-100, FSN, FSN-100, FS-300 (trade name, manufactured by DuPont); FT-250, 251 (trade name, manufactured by Neos Co., Ltd.) Can be mentioned. The fluorine-based surfactant may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited, and examples thereof include polysiloxane-based compounds and polyether-modified organosiloxanes. The commercially available silicone-based surfactant is not particularly limited, but specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK. -348, BYK-349 (trade name, manufactured by Big Chemie), 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 name, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like can be mentioned. The silicone-based surfactant may be used alone or in combination of two or more.

The content of the surfactant is preferably 0.05% by mass or more and 2.5% by mass or less, and more preferably 0.05% by mass or more and 1.5% by mass, based on the total amount (100% by mass) of the ink composition. It is less than mass%. When the content of the surfactant is within the above range, the wettability of the ink composition adhering to the recording medium tends to be further improved. Here, the content of the component in the present embodiment is not limited to the surfactant, but for example, when a plurality of types of the surfactant are contained in the ink composition, the content of the surfactant is the total amount thereof. be. The same applies to other ingredients.

Other components of the ink composition include solubilizers, viscosity regulators, pH regulators, antioxidants, preservatives, fungicides, corrosion inhibitors, and chelate to capture metal ions that affect dispersion. Various additives such as an agent (for example, sodium ethylenediaminetetraacetate) can also be appropriately contained.

[Coagulant]
The coagulant of the present embodiment contains a coagulant capable of coagulating or thickening the above-mentioned ink composition. The ink composition of the present embodiment exhibits the effects of the present invention when used together with the coagulated liquid in a recording method described later. The coagulant causes the coagulant in the coagulant to interact with the ink composition to agglomerate the components contained in the ink composition and thicken or insolubilize the ink composition. As a result, it is possible to prevent landing interference and bleeding of the ink composition to be adhered thereafter, and it is possible to uniformly draw lines, fine images, and the like.

<Coagulant>
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. As a result, betamura and bleeding tend to be more suppressed. Among the components contained in the ink composition, examples of the components that are aggregated by the flocculant include the core polymer and shell polymer used for the above-mentioned pigment and polymer particles, and 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 preferable. By containing such a carboxylic acid, the agglutination effect of the polymer and the wax is further improved, and by extension, the color-developing property tends to be more excellent. The organic acid may be used alone or in combination of two or more.

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 surely exerting the effect of the present invention. Such polyvalent metal salts are not particularly limited, but are, for example, group 2 alkaline earth metals in the periodic table (for example, magnesium and calcium), and transition metals of the third group in the periodic table (for example, lanthanum). , Salts of earth metals (eg, aluminum) from Group 13 of the Periodic Table, and salts of lanthanides (eg, neodym). Further, as the salt of these polyvalent metals, a carboxylate (for example, formic acid, acetic acid, benzoate), a sulfate, a nitrate, a chloride, and a thiocyanate are suitable. Among them, the polyvalent metal salt includes calcium salt or magnesium salt of carboxylic acid (artic acid, acetic acid, benzoate, etc.), calcium salt or magnesium salt of sulfuric acid, calcium salt or magnesium salt of nitrate, calcium chloride, magnesium chloride, etc. And one or more selected from the group consisting of calcium salt or magnesium salt of thiocyan acid are preferable. The polyvalent metal salt may be used alone or in combination of two or more.

The cationic compound is not particularly limited, and examples thereof include a cationic polymer and a water-soluble metal compound. From the viewpoint of more effectively and surely exerting the effect of the present invention, examples of the cationic polymer include allylamine-based resins such as polyethyleneimine, polydiallylamine and polyallylamine, alkylamine polymers, JP-A-59-20696, JP-A-59-. 33176, 59-33177, 59-155088, 60-11389, 60-49990, 60-83882, 60-109894, 62-1984943, 63-49478. , No. 63-115780, No. 63-280681, No. 1-4371, No. 6-234268, No. 7-125411, No. 10-193776, 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, and 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 material.

The content of the aggregating agent 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, based on the total amount of the agglomerating liquid (100% by mass). It is more preferably 0.0% by mass or more and 15% by mass or less. When the content of the flocculant is within the above range, betamla and bleeding tend to be more suppressed.

The coagulant used in the present embodiment may contain the same surfactant, organic solvent and water as those used in the above-mentioned ink composition. In addition, the agglomerate liquid captures solubilizing agents, viscosity regulators, pH regulators, antioxidants, preservatives, fungicides, corrosion inhibitors, and metal ions that affect dispersion as other components. Various additives such as the chelating agent of the above can be appropriately added.

〔Recording method〕
The recording method of this embodiment can be roughly divided into two forms. One embodiment of the recording method of the present embodiment (hereinafter referred to as “first recording method”) has an adhesion step of adhering the ink composition of the present embodiment and the above-mentioned agglomerated liquid to the recording medium. Here, it is preferable that the adhesion step includes a coagulation liquid adhering step of adhering the coagulant liquid to the recording medium and an ink composition adhering step of adhering the ink composition to the recording medium. In the adhesion step, the ink composition adhesion step may be provided after the coagulation liquid adhesion step, or the coagulation liquid adhesion step may be provided after the ink composition adhesion step, and the coagulation liquid adhesion step and the ink composition adhesion step may be performed at the same time. It may be provided. By using the first recording method, it is possible to improve the scratch resistance and image quality (bleed suppression) of the obtained recorded material while maintaining excellent ejection stability. According to the first recording method of the present embodiment, it is possible to obtain a recorded material having excellent glossiness in addition to excellent ejection stability, abrasion resistance, and image quality (bleeding suppression).

Another embodiment of the recording method of the present embodiment (hereinafter referred to as "second recording method") includes a coagulation liquid adhering step of adhering the coagulation liquid to the recording medium, a coloring material, water, an organic solvent, and polymer particles. It has an ink composition adhering step of adhering an ink composition containing the above to a recording medium having a surface temperature of 38 ° C. or lower. Further, in the above ink composition used in the second recording method, the organic solvent contains an organic solvent having a standard 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 the ink 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 scratch resistance and image quality (bleed suppression) of the obtained recorded material while maintaining excellent ejection stability. According to the second recording method of the present embodiment, it is possible to obtain a recorded material having excellent glossiness in addition to excellent ejection stability, abrasion resistance, and image quality (bleeding suppression). That is, the second recording method includes an organic solvent having a standard boiling point of 150 ° C. or higher and 250 ° C. or lower and an alkyl polyol having a standard boiling point of 280 ° C. or higher in the ink composition used. The amount is 2.0% by mass or less, preferably 0.5% by mass or less with respect to 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. -It is possible to improve the abrasion resistance and image quality (bleed suppression) of the obtained recorded matter while maintaining excellent ejection stability as compared with the conventional recording method, even if it is not limited to those having a shell structure. can.

The polymer particles in the second recording method preferably contain at least an aromatic monomer unit as a constituent unit. Since the shell polymer contains an aromatic monomer as a constituent unit, it tends to be more excellent in discharge stability.
The coloring material, water, organic solvent, polymer particles, and optionally used components contained in the ink composition of the second recording method may be the same as the ink composition of the present embodiment except for the above. A detailed description here will be omitted. Further, the second recording method can be the same as that for the first recording method except for the configuration characteristic of the above-mentioned second recording method, but may be independent of the first recording method. can.

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

[Coagulation liquid adhesion process]
The coagulation liquid adhesion step is a step of adhering the coagulation liquid to the recording medium. The means for adhering the agglomerate is not particularly limited, but for example, roller coating, spray coating, or an inkjet method can be used. Among these, it is preferable to attach by the inkjet method. By adhering the agglomerate by the inkjet method, there is a tendency that the surface quality change of the media is suppressed and the abrasion resistance is further improved.

The amount of aggregated liquid adhered to the recording medium is preferably 0.01 mg / inch ² or more and 1.0 mg / inch ² or less, and more preferably 0.01 mg / inch ² or more and 0.50 mg / inch in terms of solid content. ^{It is 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 betamura and the ruled line balls of the obtained recorded matter tend to be more suppressed.

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

[Ink composition adhesion step]
The ink composition adhering step is a step of adhering the ink composition to the recording medium, and can be provided at the same time as the coagulating liquid adhering step described above or before and after the coagulating liquid adhering step. It is preferable to provide after the coagulating liquid adhering step from the viewpoint of more effectively and surely performing. The means for adhering the ink composition is not particularly limited, and for example, roller coating, spray coating, and an inkjet method can be used. Among these, it is preferable to attach by the inkjet method. By adhering the ink composition by an inkjet method, there is a tendency that the surface quality change of the medium is suppressed and the scratch resistance is further improved.

From the viewpoint of further enhancing the scratch resistance, the ink composition adhesion step is preferably a step of adhering the ink composition to the heated recording medium. That is, it is preferable to have a step of heating the recording medium during the ink composition adhering step and / or before the ink composition adhering step. Further, the above step is preferable in order to dry the ink composition adhering to the recording medium at an early stage to suppress bleeding and improve the image quality. The step of heating the recording medium in the step of adhering the ink composition is also referred to as a primary heating step. The surface temperature of the heated recording medium is not limited to the lower limit, but is preferably 25 ° C. (normal temperature) or higher, more preferably 30 ° C. or higher, and further preferably 32 ° C. or higher. It is more preferable that the temperature is 35 ° C. or higher. The surface temperature is not limited to an upper limit, 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, and it is more preferable that the temperature is 38 ° C. or lower. The second recording method may be the same as the first recording method except that the surface temperature in the ink composition adhesion step is 38 ° C. or lower. In the second recording method, excellent ejection stability, abrasion resistance, image quality (bleeding suppression), and even in a recording medium in which the above-mentioned ink composition and agglomerated liquid are used and the surface temperature to be recorded is 38 ° C. or lower are used. Glossiness is obtained.

The film thickness of the dried film after drying the recording region to which the ink composition and the agglomerated liquid are attached 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 betamura and the ruled line balls of the obtained recorded matter tend to be more suppressed. Further, when the film thickness of the dry film is 3.0 μm or less, the change in glossiness of the obtained recorded material tends to be further suppressed. Here, the "recording area" means an area on the surface of the recording medium on which an image is formed.

The amount of polymer particles adhered to the recording medium is preferably 0.01 mg / inch ² or more and 0.75 mg / inch ² or less, and 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 betamura and the ruled line ball of the obtained recorded matter tend to be more suppressed. Further, when the amount of polymer particles adhered to the recording region is 0.75 mg / inch ² or less, the glossiness of the obtained recorded material tends to be more excellent.

[Recorded medium]
Examples of the recording medium include an absorbable, low-absorbent, or non-absorbable recordable medium. Among these, it is preferable that the recording medium is a low-absorption recording medium or a non-absorbable recording medium. When a low-absorption recording medium or a non-absorbable recording medium is used, the agglomerating liquid is repelled on the surface thereof and it is difficult to uniformly apply the aggregating agent, so that betamla and bleeding are more likely to occur. However, in the present embodiment, it is particularly useful because it can prevent the aggregated liquid from being repelled by the ink composition. Further, when a low-absorption recording medium or a non-absorbable recording medium is used, the flocculant does not permeate the recording medium and tends to remain on the surface of the recording medium, so that the stickiness and scratch resistance of the recording surface deteriorate. Tend to do. However, in the present embodiment, since the amount of the agglomerated liquid used can be reduced by using the above-mentioned ink composition, the stickiness of the recording surface can be improved, which is particularly advantageous.

Here, the "low-absorbing recording medium" or "non-absorbable recording medium" refers to a recording medium having a water absorption amount 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 Technical Association of the Pulp and Paper (JAPAN TAPPI). For details of the test method, refer to the standard No. of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition". 51 is described in "Paper and Paperboard-Liquid Absorption Test Method-Bristow Method".

Further, the non-absorbable recording medium or the low-absorbent recording medium can be classified according to the wettability of the recording surface with water. Specifically, 0.5 μL of water droplets are dropped on the recording surface of the recording medium, and the reduction rate of the contact angle (comparison between the contact angle at 0.5 msec and the contact angle at 5 seconds after landing) is measured. The recording medium can be characterized by. More specifically, as a property of the recording medium, the non-absorbability of the "non-absorbable recording medium" means that the above-mentioned reduction rate is less than 1%, and the low absorption of the "low absorption recording medium". Gender refers to the above-mentioned reduction rate of 1% or more and less than 5%. Further, the absorbability means that the above-mentioned reduction rate is 5% or more. The contact angle can be measured using a portable contact angle meter PCA-1 (manufactured by Kyowa Interface Science Co., Ltd.) or the like.

The absorbent recording medium is not particularly limited, but is, for example, plain paper such as electrophotographic paper having high permeability of the ink composition, inkjet paper (ink absorbing layer composed of silica particles or alumina particles, or polyvinyl). Ink-only paper with an ink absorbing layer composed of hydrophilic polymers such as alcohol (PVA) and polyvinylpyrrolidone (PVP)), art paper used for general offset printing with relatively low penetration of ink compositions. , Coated paper, cast paper and the like.

The low-absorbency recording medium is not particularly limited, and examples thereof include coated paper provided with a coating layer for receiving oil-based ink on the surface. The coated paper is not particularly limited, and examples thereof include printed paper such as art paper, coated paper, and matte paper.

The non-absorbent recording medium is not particularly limited, but is, for example, a plastic film having no ink absorbing layer, a medium having a plastic coated on a substrate such as paper, or a medium having a plastic film adhered to the substrate. And so on. Examples of the plastic mentioned here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

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

In particular, the recording medium is preferably in the form of a roll. When recording, the roll-shaped recording medium can be used in such a manner that the recording head is scanned once relative to the recording medium and wound by a take-up roller. When such a recording medium is used, all colors cannot be recorded by one feeding due to the large number of types of colored inks used, and when recording is performed many times, the recording medium is used multiple times. On the other hand, a recorded object can be obtained by scanning the recording head relatively once and repeating the operation of winding with the take-up roller. However, due to the roll shape, the layer formed of the polymer in the recorded material tends to be cracked. When cracks occur, the image quality of the obtained recorded material tends to deteriorate due to reasons such as the coagulation liquid permeating the cracks. However, the film formed by the ink composition obtained by the recording method of the present embodiment is less likely to cause cracks. Therefore, the present invention is particularly useful when a recording medium having such a shape is used.

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

Of these, the drying device 90 has a first drying unit 40 for drying the aggregated liquid and a second drying unit 50 for drying the recorded material obtained by the recording method according to the present embodiment.

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

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

Further, the recording unit 30 is provided so that the aggregated liquid can be applied to the recording medium F sent from the transport unit 20 and the ink composition can be ejected and recorded. Specifically, the recording unit 30 includes heads 31 and 32 for performing the coagulation liquid adhering step, a recording head 33 for performing the ink composition adhering step, and a platen 34 as a medium support part.

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

Further, the second drying unit 50 is configured to be able to further dry the aggregate 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 portion 50. The third feed roller 65 is arranged 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 feed direction Y. The step of further drying the aggregate liquid adhering to the recording medium F and the ink composition adhering to the recording medium F is called a secondary heating step of heating the recording medium. The surface temperature of the recorded medium in the secondary heating step is preferably 50 to 200 ° C, more preferably 60 to 150 ° C, in terms of improving the abrasion resistance of the recorded material and preventing thermal deformation of the recorded medium. It is more preferably 70 to 120 ° C.

Further, the discharge unit 70 is provided so that the recorded 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 device 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. Of these, the fourth feed roller 71 and the fifth feed roller 72 are arranged so as to be in contact with the surface of the recording medium F. Further, the sixth feed roller 73 and the seventh feed roller 74 are arranged so as to form a roller pair. The recorded medium F discharged by the 6th feed roller 73 and the 7th feed roller 74 is provided so as to be wound by the take-up roller 75.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples. In the following, "polymer particles having a core-shell structure" are referred to as "core-shell type polymer particles".

[Material for aqueous dispersion of core-shell type 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 type 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 above reaction vessel and reacted to polymerize the shell polymer. Then, 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 added dropwise to the reaction vessel, and the polymerization reaction was carried out while stirring at 70 ° C. Then, the mixture was neutralized with sodium hydroxide, the pH was adjusted to the range of 8 to 8.5, and the mixture was filtered through a 0.3 μm filter to prepare an aqueous dispersion of core-shell type polymer particles (polymer particles A).

Further, the polymer particles B to the same method as for preparing the polymer particles A, except that the content ratios (units: parts by mass) of the monomers constituting the shell polymer and the core polymer were changed as shown in Table 1. I was prepared. The polymer particles (E, G) in which the components constituting the shell polymer or the core polymer are not described are polymer particles of a single layer, which are polymerized in one step without being prepared by polymerizing the shell polymer. Was prepared.

[Average particle size]
The polymer particles obtained above were measured by "Microtrac UPA" (Nikkiso Co., Ltd.) to determine the average particle diameter φ (nm) of the core-shell type polymer particles.

[Acid value]
For the polymer particles, the acid value of the core polymer was calculated from the following formula.
Acid value of core polymer (mgKOH / g) = Acrylic acid used for core polymer (parts by mass) / Total core polymer (parts by mass) / 72.06 x 56.11 x 1000
Further, the acid value of the shell polymer was obtained 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 to determine the glass transition temperature (Tg, unit: ° C.) of the polymer constituting the core polymer and the polymer constituting the shell polymer, respectively. I asked. As the differential scanning calorimeter, a model "DSC6220" manufactured by Seiko Electronics Co., Ltd. was used.

Table 1 also shows the content ratio, average particle size, acid value, and Tg of each monomer in the polymer particles A to I.

[Preparation of pigment dispersion]
First, the reaction vessel equipped with a stirrer, a thermometer, a reflux tube and a dropping funnel was replaced with nitrogen. Then, 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 added to the above reaction. It was placed in a container and heated to 70 ° C. Next, 150 parts by mass of benzyl methacrylate, 15 parts by mass of acrylic acid, 50 parts by mass of butyl methacrylate, 1.0 part by mass of t-dodecyl mercaptan, 20 parts by mass of methyl ethyl ketone and 1.0 part by mass of azobisisobutyronitrile prepared separately. The mixed solution was placed in a dropping funnel and dropped into the reaction vessel over 4 hours to carry out a polymerization reaction of the dispersed polymer. Next, methyl ethyl ketone was added to the reaction vessel to prepare a dispersed 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 (manufactured by Dainichiseika Kogyo Co., Ltd., trade name) 30 parts by mass, 100 parts by mass of 0.1 mol / L sodium hydroxide aqueous solution, and 30 parts by mass of methyl ethyl ketone are mixed, and Ultimateizer 25005 (Sugino Machine Limited) is mixed. 8 passes were distributed with (manufactured by the company). 300 parts by mass of ion-exchanged water was added to the obtained mixture, and the total amount of methyl ethyl ketone and a part of the water were distilled off using a rotary evaporator, which was then neutralized with 0.1 mol / L sodium hydroxide to pH 9. Adjusted to. Next, while measuring the volume average particle size of the cyan pigment with a particle size distribution meter, it is dispersed until the volume average particle size becomes 100 nm, and then filtered with a 3.0 μm membrane filter to obtain a solid content (with a dispersed polymer). A pigment dispersion having a pigment content of 20% by volume was obtained.

[Material for ink composition]
The main materials for the ink composition used in the preparation of the following recordings are as follows.
[Color material]
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]
Water dispersions of core-shell type polymer particles A to I
〔wax〕
AQUACER593 (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 sufficiently stirred to obtain an ink composition. In Table 2 below, the unit of the numerical value is mass%, and the total is 100.0 mass%.

[Material for coagulant]
The main materials for the agglomerate used in the preparation of the following recordings are as follows.
[Coagulant]
Magnesium Sulfate Allylamine Resin (manufactured by Nittobo Chemical Co., Ltd., trade name "PAA-HCL-01")
〔solvent〕
Propylene glycol 2-pyrrolidone [surfactant]
BYK348 (trade name, manufactured by Big Chemie)

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

[Creation of recorded material]
We prepared an inkjet printer, which is a modified PX-G930 (trade name manufactured by Epson) with a heater attached to the platen, and the surface temperature of the recording medium on the platen is the primary heating temperature shown in Tables 4 and 5. I adjusted it with a heater so that it would be. Next, the recording medium was transferred to the printer, and the coagulated liquid filled in the head was applied by an inkjet method at ^{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-coated on the coagulated liquid adhering surface at a resolution of 720 × 720 dpi and ^{an adhering amount of 12 mg / inch 2} to obtain a recorded material on a recording medium. Then, the recording medium was ejected from the printer, and the recording medium was allowed to stand in an environment of 80 ° C. for 10 minutes to dry (secondary heating). However, in Recording Example 19, the condition of the secondary heating was changed from 80 ° C. to 25 ° C. (normal temperature). As the recording medium, coated paper (trade name "PET50A PL Thin" manufactured by Lintec Corporation) was used.

[Abrasion resistance]
The obtained recorded material is a friction element with a white cotton cloth (JIS L 0803 compliant) attached to the 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 material. Rubbed 30 times back and forth until it peeled off. Then, the peeling of the recorded material on the recording medium was visually observed, and the abrasion resistance was evaluated according to the following evaluation criteria. The results obtained are shown in Tables 4 and 5.
(Evaluation criteria)
A: No scratches or peeling of the recorded material was observed.
B: Scratches or peeling of the recorded material was observed in less than 20% of the rubbed area (stroke area).
C: Scratches or peeling of the recorded material was observed in 20% or more and less than 50% of the rubbed area (stroke area).
D: Scratches or peeling of the recorded material was observed in 50% or more and less than 90% of the rubbed area (stroke area).
E: Scratches or peeling of the recorded material was observed in 90% or more of the rubbed area (stroke area).

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

[Image quality (bleed)]
Except for producing a solid pattern of 10 × 10 mm, the bleeding of the recorded material obtained by producing by the same method as the above [Production of recorded material] is visually confirmed, and the image quality (image quality according to the following evaluation criteria). Bettamura) was evaluated. The results obtained are shown in Tables 4 and 5.
(Evaluation criteria)
A: No bleeding was observed inside or in the contour of the solid pattern.
B: No bleeding was observed inside the solid pattern, but bleeding was observed in the contour portion.
C: Some bleeding was observed not only in the outline of the solid pattern but also in the inside.
D: Bleed was observed in the contour of the solid pattern, and bleed was observed in a slightly larger amount inside.

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

As a result of the evaluation, in 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, the ink composition dries slowly and is resistant. It was inferior in rubbing property and image quality. Similarly, in Recording Example 10 using the ink composition 4, the image quality was relatively improved by raising the primary heating temperature considerably, but the ejection stability was inferior as an adverse effect. It should be noted that raising the primary heating temperature considerably is not preferable 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 the present embodiment, excellent image quality of the recorded material is the most important issue, and in this respect, each of the above examples is inferior in that the image quality cannot be improved without any harmful effect.

Further, the recording examples 12, 13, and 17 in which the coagulating liquid was not used were inferior in image quality as in the above recording examples.
On the other hand, Record Examples 1 to 3, 5 to 9, 11 using an ink composition having an organic solvent content of 2.0% by mass or less, which is an alkyl polyol having a standard boiling point of 280 ° C. or higher, and using a coagulant. , 14 to 16 and 19 are superior to the above-mentioned recording examples in which the image quality is inferior, at least in that the image quality is excellent.
Among them, Recording Examples 5, 16 and 19 using the ink composition 5 containing the polymer particles E, which 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 polymer particles on the above were inferior in film thickening property and inferior in abrasion resistance.

Further, the recording example 7 using the ink composition 7 containing the polymer particles G which are polymer particles which are not core-shell type polymer particles and whose polymer particles are made of a resin having a relatively low Tg is inferior in ejection stability. It is presumed that the polymer particles contained in the ink were welded to each other in the head and became foreign matter, which caused the ejection failure. This can be inferred from the fact that the ink adhering to the nozzle plate after recording was inspected with a microscope and welding of polymer particles in the ink was observed.

Similarly, the recording example 15 in which the primary heating temperature is 35 ° C. using the ink composition 7 and the recording example 16 in which the primary heating temperature is 35 ° C. using the ink composition 5 are not core-shell type polymer particles. Despite using an ink composition containing polymer particles, the ejection stability was excellent. From this, even when an ink composition containing polymer particles other than 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 coagulant. It is presumed that bleeding could be suppressed even if the primary heating temperature was relatively low due to the effect of suppressing ink bleeding by using the coagulant.

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

Although not described in the table, the primary heating temperature was set to 25 ° C. when the platen heater was turned off and the coagulant adhered and the ink composition adhered. When each recording was performed in the same manner, the image quality was D in each case. From this, it was found that it is preferable to perform the primary heating step and set the primary heating temperature to at least 25 ° C. in terms of improving the image quality.

1 ... Inkjet recording device, 10 ... Feeding unit, 11 ... Roll medium holder, 20 ... Conveying unit, 21 ... First feed roller, 30 ... Recording unit, 31 ... Head, 32 ... Head, 33 ... Recording head, 34 ... Platen, 40 ... 1st drying section, 43 ... 2nd feed roller, 50 ... 2nd drying section, 64 ... outlet, 65 ... 3rd feed roller, 70 ... discharge section, 71 ... 4th feed roller, 72 ... 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 (16)

A coagulation liquid adhering step of adhering a coagulation liquid containing a coagulant capable of coagulating or thickening the components of the ink composition to the recording medium, and a coagulation liquid adhering step.
A heating process that heats the recording medium,
An ink composition attaching step of attaching an ink composition containing a coloring material, water, an organic solvent, and polymer particles to a recording medium heated by the heating step and having a surface temperature of 38 ° C. or lower.
Have,
In the ink composition, the organic solvent contains an organic solvent having a standard 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. With respect to 2.0% by mass or less,
The polymer particles are made of a resin having a (meth) acrylic monomer as a constituent unit at least.
A recording method in which the ink composition adhesion step is a step of adhering to a recording medium by an inkjet method. The recording method according to claim 1, wherein the polymer particles contain at least an aromatic monomer unit as a constituent unit. The adhesion step of adhering the ink composition to the recording medium is a step of adhering the ink composition to the recording medium heated by the heating step and having a surface temperature of 30 to 38 ° C. The recording method according to 2. Any one of claims 1 to 3, wherein the polymer particles have a core-shell structure comprising 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. The recording method described in the section. The recording method according to any one of claims 1 to 4, wherein the content of the organic solvent having a standard boiling point of 280 ° C. or higher is 0.5% by mass or less with respect to the total amount of the ink composition. The acid value of the shell polymer is higher than the acid value of the core polymer.
The recording method according to claim 4, wherein the acid value of the shell polymer is 20 mgKOH / g or more, and the acid value of the core polymer is 15 mgKOH / g or less. The polymer particles contain at least an aromatic monomer unit as a constituent unit, and the aromatic monomer contains at least one of styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, and divinylbenzene. The recording method according to any one of claims 1 to 6. The recording method according to claim 4, wherein the difference between the glass transition temperature of the core polymer and the glass transition temperature of the shell polymer is 10 ° C. or higher. The recording method according to any one of claims 1 to 8, wherein the flocculant is one or more selected from the group consisting of polyvalent metal salts, organic acids, and cationic compounds. The recording method according to any one of claims 1 to 9, wherein the coagulating liquid adhering step is a step of adhering to a recording medium by an inkjet method. The polymer particles have a core-shell structure including a core polymer and a shell polymer, the glass transition temperature of the shell polymer is 60 ° C. or higher and 150 ° C. or lower, and the glass transition temperature of the core polymer is 0 ° C. or higher and 60 ° C. or higher. The recording method according to any one of claims 1 to 10, wherein the temperature is lower than ° C. The recording method according to any one of claims 1 to 11, wherein the content of the organic solvent having a standard boiling point of 150 ° C. or higher and 250 ° C. or lower is 5 to 50% by mass with respect to the total amount of the ink composition. .. The recording method according to any one of claims 1 to 12, wherein the polymer particles are 0.5 to 20% by mass with respect to the total amount of the ink composition. The recording method according to any one of claims 1 to 13, wherein the polymer particles contain an aromatic monomer unit as a constituent unit and contain 10 to 80% by mass of the aromatic monomer unit with respect to the entire polymer particles. The recording method according to any one of claims 1 to 14, wherein the content of the flocculant is 10% by mass or less with respect to the total amount of the flocculant. A recording device for recording by the recording method according to any one of claims 1 to 15.

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