JP2023041122A - Ink, ink container, recording device, and recording method - Google Patents

Abstract

To solve the problem in which: the use of ink containing crystalline polyester urethane resin gives ink having excellent dryability while causing a decrease in ink discharge stability.SOLUTION: An ink contains a resin, a colorant, and water, the resin being a crystalline polyester urethane resin, the resin having a melting peak temperature (Tm) of 30°C or more and 100°C or less, the ink further containing a compound represented by a predetermined general formula (1).SELECTED DRAWING: None

Description

The present invention relates to ink, an ink container, a recording apparatus, and a recording method.

2. Description of the Related Art Ink jet recording apparatuses have advantages such as low noise, low running costs, and easy color printing, and are widely used in general households as digital signal output devices. Moreover, in recent years, inkjet technology has been used not only for home use but also for commercial and industrial purposes as digital printing capable of printing a wide variety of designs in small quantities without the need for plates. In commercial applications, it is used for printing pamphlets, catalogs, posters, manuals, etc. In industrial applications, it is used for printing labels, packages, textiles, corrugated cardboard, etc. Especially in the field of industrial printing, high-mix, low-volume designs are preferred and used for product sales promotion.

An example of such small-lot, high-mix production is packaging printing applications for food and daily necessities. Scratch resistance is required.
In addition, since printed recording media are expected to be stacked and stored immediately after printing, ink drying property and scratch resistance immediately after ink drying are also required.

Patent Document 1 discloses the use of an ink containing a crystalline polyester urethane resin in order to improve the fixability of an image formed by the ink to a recording medium.

However, when an ink containing a polyester urethane resin having crystallinity is used, although an ink having excellent drying properties can be obtained, there is a problem that the ejection stability of the ink is lowered.

The present invention is an ink containing a resin, a coloring material, and water, wherein the resin is a polyester urethane resin having crystallinity, and the melting peak temperature (Tm) of the resin is 30° C. or more and 100° C. or less. and the ink further contains a compound represented by a given general formula (1).

ADVANTAGE OF THE INVENTION According to this invention, when the ink containing the polyester urethane resin which has crystallinity is used, the ink excellent in drying property and discharge stability can be provided.

FIG. 1 is a perspective explanatory view showing an example of a recording apparatus. FIG. 2 is a perspective explanatory view showing an example of the main tank.

An example of an embodiment of the present invention will be described below.

<<Ink>>
The ink of this embodiment contains a resin, a coloring material, and water, and may contain components such as an organic solvent and a surfactant, if necessary.
Further, the ink of the present embodiment contains a compound represented by general formula (1).
The ink of the present embodiment may also contain a dialkylsulfosuccinic acid or a salt of a dialkylsulfosuccinic acid, a siloxane compound, and the like.

<Resin>
The ink of this embodiment contains a polyester urethane resin having crystallinity as a resin, and may further contain other types of resins as necessary.
Other types of resins are not particularly limited and can be appropriately selected depending on the purpose. Examples include urethane resins other than polyester urethane resins having crystallinity, polyester resins, acrylic resins, vinyl acetate resins, Styrene-based resins, butadiene-based resins, styrene-butadiene-based resins, vinyl chloride-based resins, acrylic-styrene-based resins, acrylic-silicone-based resins, and the like can be mentioned. Moreover, these may be used individually by 1 type, or may be used in combination of 2 or more types.
Hereinafter, the polyester urethane resin having crystallinity will be described in detail.

-Polyester urethane resin with crystallinity-
“Crystalline polyester urethane resin (hereinafter simply referred to as “polyester urethane resin”)” is a resin having a structural unit containing a crystalline polyester structure, and other structural units may be added as necessary. may contain. In addition, a "structural unit" shows the partial structure in the polymer derived from the material used when polymerizing the resin. In addition, the polyester urethane resin “having crystallinity” refers to a polyester urethane resin having an endothermic peak when measured using a differential scanning calorimeter (DSC) under the measurement conditions described later, and the heat of fusion at the endothermic peak is 5 J. / g or more preferably represents a polyester urethane resin.
The polyester urethane resin melts or dissolves once when the ink is applied to the recording medium and then heated and dried to lower the viscosity, and then recrystallizes to form a tough film on the image formed by the ink. Form. This makes it possible to form an image that is excellent in drying property and abrasion resistance. In addition, since the polyester urethane resin has a structure in which crystalline polyester moieties are linked by urethane bonds, the resistance to organic solvents contained in the ink is improved. For example, the resin is contained in the ink in the form of resin particles. Improves stability when As a result, it is possible to prepare an ink having excellent storage stability even at high temperatures.

The polyester urethane resin has an endothermic peak when measured using a differential scanning calorimeter (DSC) under the following measurement conditions. It preferably has a melting peak temperature (Tm) (hereinafter also simply referred to as "melting point") at , more preferably has a melting peak temperature (Tm) in the range of 35 ° C. or higher and 90 ° C. or lower, and 42 ° C. or higher It is more preferable to have a melting peak temperature (Tm) in the range of 77°C or less. When the melting point is 30° C. or higher, an image having excellent mechanical strength can be formed. In addition, since the melting point is 100° C. or less, the adhesion between resins and the adhesion between the resin and the recording medium due to heat drying can be strengthened, and the fixability of the image to the recording medium can be improved. can.
(Measurement condition)
4 g of "aqueous dispersion of polyester urethane resin" or "aqueous dispersion of polyester urethane resin isolated from ink containing polyester urethane resin" is placed in a container so as to spread evenly. Next, it is dried at 70° C. for 1 hour, then at 130° C. for 1 hour, and further dried at 130° C. under reduced pressure to obtain a solid matter for measurement. After that, the thermal properties of the measurement sample are measured under the following conditions using, for example, a differential scanning calorimeter (DSC) (Q2000 manufactured by TA Instruments). A graph of the amount of endothermic heat and temperature is drawn from the obtained measurement results, and the temperature at the top of the melting (endothermic) peak obtained in the second heating process is defined as the melting point.
・Sample container: Aluminum sample pan (with lid)
・ Sample amount: 5 mg
・Reference aluminum sample pan (empty container)
・ Atmosphere: nitrogen (flow rate 50 mL / min)
・Starting temperature: -80°C
・Temperature increase rate: 10°C/min
・End temperature: 130°C
・Retention time: 1 min
・Temperature drop rate: 10°C/min
・End temperature: -80℃
・Retention time: 5 min
・Temperature increase rate: 10°C/min
・End temperature: 130°C

As an example, the melting peak temperature (Tm) of the crystalline polyester urethane resin in the ink can be measured as follows. That is, the ink is subjected to an ultracentrifuge (Optima Max-XP, manufactured by Beckman Coulter, Inc.) to separate into a supernatant liquid and a sediment. Next, the precipitate is collected, washed in 100 mL of tetrahydrofuran at 25° C., and separated into a solid and a filtrate by filtration. The supernatant liquid and filtrate obtained by centrifugation are combined and dried at 40° C. and 10 mPa using a vacuum dryer (manufactured by Kawata Co., Ltd., product name: Deco) to obtain a dry matter. A slurry is prepared using the obtained dried matter and water, and the slurry is sufficiently dispersed with a desktop disperser (manufactured by Joko Co., Ltd., device name: Nano Jet Pal JN5) and filtered. Water was added to the obtained filter cake, and after sufficient dispersion using the tabletop disperser, it was concentrated to a solid content concentration of 30% by mass using a rotary evaporator to obtain an aqueous resin dispersion (resin emulsion ). Using 4 g of an aqueous resin dispersion, the melting peak temperature (Tm) is measured under the same conditions as above.

The heat of fusion at the endothermic peak of the polyester urethane resin is preferably 5 J/g or more and 100 J/g or less, more preferably 10 J/g or more and 80 J/g or less, and 20 J/g or more and 50 J/g or less. It is even more preferable to have When the heat of fusion is 5 J/g or more, the degree of crystallinity of the crystalline portion is increased, so that the viscosity is sufficiently lowered during the heating and drying process, and the deterioration of image fixability is suppressed. Further, when it is 100 J/g or less, the ratio of the crystalline sites in the resin does not become too high, thereby suppressing deterioration of image strength and storage stability.
The crystallization peak temperature of the polyester urethane resin is preferably -30°C or higher and 80°C or lower.
In addition, the amount of heat of crystallization at the crystallization peak of the polyester urethane resin is preferably 5 J/g or more and 100 J/g or less.

The acid value of the polyester urethane resin is preferably 10 mgKOH/g or more and 40 mgKOH/g or less. Within this range, an image formed from the ink has excellent mechanical strength, and can form an image excellent in fixability and anti-blocking properties. Further, when the acid value is 10 mgKOH/g or more, the dispersion stability of the resin is improved, so that a uniform coating is formed and an image having excellent mechanical strength can be formed. Further, when the acid value is 40 mgKOH/g or less, in addition to being able to form a film with excellent mechanical strength, the hydrophilicity of the resin is appropriate, so that the water resistance is improved, and it is contained in the ink as resin particles. The stability of the case becomes good.
As a method for measuring the acid value of the polyester urethane resin, for example, the polyester urethane resin is placed in a tetrahydrofuran (THF) solution and titrated with a 0.1 M potassium hydroxide methanol solution.
The acid value of the polyester urethane resin may be calculated from the carboxyl group concentration in the resin constituent material when the resin is produced, or the polyester urethane resin is put in a tetrahydrofuran (THF) solution, and 0.1 M potassium hydroxide methanol is added. It can also be measured by titration with a solution.
Further, when the carboxyl groups in the polyester urethane resin are neutralized, for example, after adding an excess aqueous solution of hydrochloric acid to make an acidic solution, the resin is extracted with chloroform, and then the resin obtained after heating or drying under reduced pressure. can be measured by dissolving in THF and titrating with a 0.1 M potassium hydroxide methanol solution.

The polyester urethane resin is preferably a resin emulsion. A resin emulsion refers to a state in which resin particles are dispersed in water or ink, and it does not matter whether the resin particles are solid or liquid.
Examples of methods for dispersing resin particles containing a polyester urethane resin in water or ink include a forced emulsification method using a dispersant and a self-emulsification method using a resin having an anionic group. In the case of the forced emulsification method, the dispersant may remain in the image formed from the ink, which may reduce the strength of the image. Therefore, it is preferable to use the self-emulsification method.
Examples of anionic groups include carboxyl groups, carboxylate groups, sulfonic acid groups, sulfonate groups, and the like. Among these, it is preferable to use a carboxylate group or a sulfonate group partially or wholly, particularly preferably wholly, neutralized with a basic compound or the like.
Examples of neutralizing agents that can be used for neutralizing anionic groups include organic amines such as ammonia, triethylamine, pyridine and morpholine; basic compounds such as alkanolamines such as monoethanolamine; metal base compounds containing Ca and the like;

When a polyester urethane resin is used as the resin particles, the volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected according to the purpose. It is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, even more preferably 10 nm or more and 100 nm or less, and particularly preferably 10 nm or more and 50 nm or less. The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The content of the polyester urethane resin is not particularly limited and can be appropriately selected according to the purpose. % or less is preferable, and 5 mass % or more and 20 mass % or less is more preferable.

-Method for producing crystalline polyester urethane resin-
The following method is mentioned as an example of the manufacturing method of polyester urethane resin.
First, a crystalline polyester polyol (A), a short-chain polyhydric alcohol (B), a polyhydric alcohol having an anionic group (C), and a polyisocyanate (D) are reacted in the absence of a solvent or in the presence of an organic solvent. to produce an isocyanate-terminated urethane prepolymer.
Next, if necessary, the anionic groups in the isocyanate-terminated urethane prepolymer are neutralized with a neutralizing agent, then water is added to disperse, and finally, the organic solvent in the system is removed if necessary. A polyester urethane resin can be obtained by this. In addition, before removing the organic solvent, if necessary, by adding a divalent or higher polyamine (also referred to as a "polyvalent amine" in the following description), a terminal isocyanate group and a polyvalent amine form The urea bond in the urea bond can also extend or crosslink the polyester urethane resin.

Examples of organic solvents that can be used during the reaction include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetic esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; and amides such as methylpyrrolidone and 1-ethyl-2-pyrrolidone. These may be used individually by 1 type, and may use 2 or more types together.

As the composition ratio of each material used in the reaction, [the number of moles of C/(the number of moles of A + the number of moles of B + the number of moles of C)] is preferably 0.15 or more and 0.5 or less, and 0.2 or more and 0 0.5 or less is more preferable, and 0.25 or more and 0.4 or less is still more preferable.
When the composition ratio is 0.5 or less, excessive hydrophilicity can prevent the ink film from becoming extremely brittle and lowering the water resistance of the image. In addition, it is possible to suppress thickening of the ink due to excessive miniaturization of the resin particles. On the other hand, when the composition ratio is 0.15 or more, the dispersion stability of the resin particles is improved.

In addition, as the composition ratio of each material used in the reaction, [D equivalent number / (A equivalent number + B equivalent number + C equivalent number)] is preferably 1.05 or more and 1.6 or less, and 1.05 1.5 or less is more preferable, and 1.1 or more and 1.35 or less is still more preferable.
By setting the composition ratio within the above range, a film having excellent mechanical strength can be obtained, and an image having excellent blocking resistance and abrasion resistance can be formed.

--Crystalline polyester polyol (A)--
The crystalline polyester polyol has a hydroxyl value (OHV) of preferably 20 mgKOH/g to 200 mgKOH/g, more preferably 50 mgKOH/g to 150 mgKOH/g, and even more preferably 70 mgKOH/g to 120 mgKOH/g.
When the hydroxyl value is within the above range, the dispersion stability of the resin is improved, and by exhibiting appropriate crystallinity, a polyester urethane resin capable of forming an image with excellent fixability can be obtained.

The type of crystalline polyester polyol is not particularly limited and can be appropriately selected depending on the intended purpose, but aliphatic polyester polyols are preferred because they have high crystallinity.

The molecular weight of the crystalline polyester polyol is not particularly limited and can be appropriately selected depending on the intended purpose. 000 to 15,000 are more preferred, 3,000 to 10,000 are even more preferred, and 3,000 to 5,000 are particularly preferred.
When the weight-average molecular weight is within the above range, the dispersion stability of the resin is improved, and by exhibiting appropriate crystallinity, a crystalline polyester urethane resin emulsion capable of forming an image with excellent fixability is obtained. be able to.
The number average molecular weight (Mn) of the crystalline polyester polyol is preferably 1,000 to 4,000, more preferably 2,000 to 3,000.

The melting point (Tm) of the crystalline polyester polyol is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50°C or higher and 100°C or lower. The melting point can be measured by an endothermic peak value on a DSC chart in differential scanning calorimeter (DSC) measurement. The crystallinity, molecular structure, etc. of the crystalline polyester are confirmed by NMR measurement, differential scanning calorimeter (DSC) measurement, X-ray diffraction measurement, GC/MS measurement, LC/MS measurement, infrared absorption (IR) spectrum measurement, etc. can do.

Next, an example of a method for producing a crystalline polyester polyol will be described. The crystalline polyester polyol is preferably produced, for example, by polycondensation of a polyhydric alcohol and a polyhydric carboxylic acid in the absence of solvent or in the presence of an organic solvent. That is, the crystalline portion of the polyester urethane resin is derived from the polyhydric alcohol and polycarboxylic acid used in the production of the crystalline polyester polyol.

--- Polyhydric alcohol ---
The polyhydric alcohol is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include diols and trihydric or higher alcohols.
As diols, for example, aliphatic diols are preferable, and saturated aliphatic diols are more preferable.
Examples of saturated aliphatic diols include linear saturated aliphatic diols and branched saturated aliphatic diols. Among these, linear saturated aliphatic diols are preferable, and linear saturated aliphatic diols having 2 or more and 12 or less carbon atoms are more preferable. When the saturated aliphatic diol is linear, the crystallinity of the crystalline polyester does not decrease and the melting point does not easily decrease. When the carbon number of the saturated aliphatic diol is 12 or less, the material is easily available, so the carbon number is more preferably 12 or less.
Examples of saturated aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8 - octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18 -octadecanediol, 1,14-eicosandecanediol, and the like. These may be used individually by 1 type, and may use 2 or more types together.
Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. These may be used individually by 1 type, and may use 2 or more types together.

--- Polycarboxylic acid ---
The polyvalent carboxylic acid is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include divalent carboxylic acids and trivalent or higher carboxylic acids. preferable.
Divalent carboxylic acids include, for example, oxalic acid, succinic acid, glutaric acid, adipic acid, speriric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12 -saturated aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid; phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconine Aromatic dicarboxylic acids such as acids, anhydrides thereof, lower alkyl esters thereof (having 1 to 3 carbon atoms) and the like can be mentioned. These may be used individually by 1 type, and may use 2 or more types together.
Trivalent or higher carboxylic acids include, for example, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, anhydrides thereof, or lower alkyl esters (having 1 to 3 carbon atoms); These may be used individually by 1 type, and may use 2 or more types together.
In addition to the saturated aliphatic dicarboxylic acid and aromatic dicarboxylic acid, the polyvalent carboxylic acid may contain dicarboxylic acid having a sulfonic acid group, dicarboxylic acid having a double bond, and the like.

--Short-chain polyhydric alcohol (B)--
Examples of short-chain polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1, Polyhydric alcohols having 2 to 15 carbon atoms such as 4-cyclohexanedimethanol, diethylene glycol, glycerin, trimethylolpropane, and the like can be mentioned.

--Polyhydric alcohol (C) having an anionic group--
The polyhydric alcohol having an anionic group is not particularly limited, but a material having two or more hydroxyl groups and functional groups such as carboxylic acid and sulfonic acid as anionic groups can be used. For example, carboxylic acid groups such as dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolbutyric acid, dimethylolvaleric acid, trimethylolpropanoic acid, and trimethylolbutanoic acid, and sulfonic acids such as 1,4-butanediol-2-sulfonic acid bases.

-- Polyisocyanate (D) --
Examples of polyisocyanates include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, and 4,4′-diphenylmethane diisocyanate (MDI). , 2,4-diphenylmethane diisocyanate, 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanato Aromatic polyisocyanate compounds such as diphenylmethane, 1,5-naphthylene diisocyanate, 4,4′4″- and rephenylmethane triisocyanate, m-isocyanatophenylsulfonyl isocyanate, and p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate , tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate , bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate and other aliphatic polyisocyanate compounds; isophorone diisocyanate (IPDI) , 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4-dichlorohexene-1,2-dicarboxylate, alicyclic polyisocyanate compounds such as 2,5-norbornane diisocyanate and 2,6-norbornane diisocyanate; These may be used individually by 1 type, and may use 2 or more types together.
Among these, aliphatic polyisocyanate compounds and alicyclic polyisocyanate compounds are preferred, alicyclic polyisocyanate compounds are more preferred, and isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate are particularly preferred.

-- Divalent or higher polyamines --
Divalent or higher polyamines include, for example, ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 1, diamines such as 4-cyclohexanediamine; polyamines such as diethylenetriamine, dipropylenetriamine and triethylenetetramine; hydrazines such as hydrazine, N,N'-dimethylhydrazine and 1,6-hexamethylenebishydrazine; dihydrazide succinate, dihydrazides such as adipic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, and isophthalic acid dihydrazide;

（上記一般式（１）中、ｘ＋ｙは０以上１０以下の整数を表す。） <Compound Represented by Formula (1)>
The ink of this embodiment contains a compound represented by the following general formula (1).

(In the above general formula (1), x+y represents an integer of 0 or more and 10 or less.)

The compound represented by the general formula (1) has a high affinity for water contained in the ink, and is highly effective in lowering the surface tension of the ink. As a result, the film formed by applying the ink is uniform and smooth, and as a result, the scratch resistance of the image formed by the ink is improved, and density unevenness that may occur in the image is reduced.

In addition, the compound represented by the general formula (1) has a defoaming function against ink, and can suppress the generation of air bubbles inside an inkjet head of a recording apparatus using ink or in an ink supply path, for example. As a result, even when using an ink that is highly drying due to the polyester urethane resin having crystallinity as described above, the generation of air bubbles in the vicinity of the nozzle that ejects the ink is suppressed, Solidification of the ink due to the drying of the ink caused by the presence of air bubbles is suppressed, and as a result, the ejection stability of the ink can be improved. Note that if ink solidification occurs in the vicinity of the nozzle, it adversely affects ink meniscus control at the nozzle, leading to further generation of air bubbles and the formation of ink solidification. If such a problem occurs in a nozzle, it will have a chain reaction of adverse effects on the nozzles around the nozzle where the problem has occurred, accelerating the instability of ejection stability and leading to a deterioration in image quality. It is preferable to add a compound represented by general formula (1) having a foaming function.

In general formula (1), x+y preferably represents an integer of 0 or more and 3 or less. When x + y is 0 or more and 3 or less, the compound represented by the general formula (1) remaining in the ink film after printing evaporates in a short time, so it is difficult to remain on the recording medium, and the image surface immediately after printing. Even when rubbing occurs, image transfer and peeling are less likely to occur, and the rubbing resistance is improved.

The compound represented by the general formula (1) is not particularly limited, and either synthesized or commercially available compounds can be used. Examples of commercially available compounds represented by general formula (1) include Surfynol 104E, Surfynol 104PG-50, Surfynol 420, Surfynol 440, Surfynol 465, Surfynol 485, Surfynol PSA- 336 (Nissin Chemical Industry Co., Ltd.) and the like.
In general formula (1), commercially available products in which x + y represent an integer of 0 or more and 3 or less include Surfynol 104E, Surfynol 104PG-50, Surfynol 420, Surfynol 440, Surfynol PSA-336, and the like. is mentioned.

The content of the compound represented by general formula (1) is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 0.3% by mass or more and 3.0% by mass or less, relative to the mass of the ink. It is more preferably 0.5% by mass or more and 2.0% by mass or less.

In the ink, the mass ratio of the polyester urethane resin having crystallinity and the compound represented by general formula (1) is preferably 5:1 to 20:1. When the ratio is 5:1 to 20:1, the ink is more likely to wet and spread on the recording medium, the scratch resistance of the image formed by the ink is further improved, and the density unevenness that may occur in the image is further reduced. do. In addition, the generation of air bubbles in the vicinity of the nozzles that eject ink is further suppressed, and the ink ejection stability is further improved. Note that the boundary values of the mass ratio of 5:1 and 20:1 are within the range of 5:1 to 20:1.

<Dialkylsulfosuccinic acid or salt of dialkylsulfosuccinic acid>
The ink of the present embodiment preferably contains dialkylsulfosuccinic acid or a salt of dialkylsulfosuccinic acid.

A dialkylsulfosuccinic acid or a salt of a dialkylsulfosuccinic acid can make the ink easily wet and spread on a recording medium. This improves the abrasion resistance of the image formed by the ink. In addition, since the applied ink is likely to wet and spread on the recording medium, even if a small amount of ejection failure or the like occurs in the nozzle, the occurrence of streak-like defective images can be suppressed.

The dialkylsulfosuccinic acid or salt of dialkylsulfosuccinic acid is not particularly limited, and both synthesized and commercially available ones can be used. Examples of commercially available dialkylsulfosuccinic acid or salts of dialkylsulfosuccinic acid include bis(2-ethylhexyl) sodium sulfosuccinate (manufactured by Tokyo Chemical Industry Co., Ltd.), Sanmorin OT (manufactured by Sanyo Chemical Industries Co., Ltd.), and carabon. DA-72 (manufactured by Sanyo Chemical Industries, Ltd.), Pelex OT-P (manufactured by Kao Corporation), and the like.

The content of the compound represented by formula (1) is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.1% by mass or more and 3.0% by mass or less, based on the mass of the ink. It is more preferably 0.1% by mass or more and 1.0% by mass or less.

<Siloxane compound>
The ink of this embodiment preferably contains a siloxane compound. Examples of the siloxane compound include compounds having a hydrophilic group or a hydrophilic polymer chain in the side chain of a compound having a polysiloxane repeating structure such as polydimethylsiloxane, or a compound having a hydrophilic group or a hydrophilic polymer chain at the end. be done. In addition, the siloxane compound should just have a polysiloxane structure in the structure.

A siloxane compound has a defoaming function against ink, and can suppress, for example, the generation of air bubbles inside an inkjet head of a recording apparatus using ink or in an ink supply path. As a result, even when using an ink that is highly drying due to the polyester urethane resin having crystallinity as described above, the generation of air bubbles in the vicinity of the nozzle that ejects the ink is suppressed, Solidification of the ink due to the drying of the ink caused by the presence of air bubbles is suppressed, and as a result, the ejection stability of the ink can be improved. In addition, by improving the ejection stability of the ink, it is possible to suppress the occurrence of streak-like defective images due to nozzle clogging, etc., and it is possible to suppress the deterioration of scratch resistance caused by the streaks. .

The siloxane compound can be appropriately selected depending on the purpose, and examples thereof include side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, single terminal modified polydimethylsiloxane, side chain both terminal modified polydimethylsiloxane, and the like. A polyether-modified siloxane compound having a polyoxyethylene group or a polyoxyethylene-polyoxypropylene group as a modifying group is preferable because it exhibits good properties.

The siloxane compound is not particularly limited, and both synthesized and commercially available compounds can be used. Examples of commercially available siloxane compounds include BYK-019, BYK-024, BYK-025, BYK-028 (BYK-Chemie Corporation), DKQ1-1247, DOWSIL1313, DOWSIL8590 (Dow Toray Industries, Inc.), TEGOFoamex3062, Airase5355 (Evonik Japan Co., Ltd.) and the like.

The content of the siloxane compound is preferably 0.01% by mass or more and 1.0% by mass or less with respect to the mass of the ink. Within the above range, the generation of air bubbles in the vicinity of the nozzles for ejecting ink is further suppressed, the ejection stability of the ink is further improved, and the decrease in abrasion resistance can be further suppressed.

<Color material>
The coloring material is not particularly limited, and pigments and dyes can be used. An inorganic pigment or an organic pigment can be used as the pigment. These may be used individually by 1 type, and may use 2 or more types together. Mixed crystals may also be used as pigments.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy color pigments such as gold and silver, and metallic pigments.
As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as contact method, furnace method, thermal method, etc. can be used.
Organic pigments include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.). , dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments for black include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black and channel black, or copper and iron (C.I. Pigment Black 11). , metals such as titanium oxide, and organic pigments such as aniline black (C.I. Pigment Black 1).
Further, for color, C.I. I. Pigment yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52: 2, 53:1, 57:1 (brilliant carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (red red), 104, 105, 106, 108 ( cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (rhodamine lake), 3, 5:1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15:1, 15:2, 15:3, 15:4 (phthalocyanine blue), 16, 17:1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.
As dyes, acid dyes, direct dyes, reactive dyes, and basic dyes can be used without particular limitation, and may be used singly or in combination of two or more.
As a dye, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. and Reactive Black 3,4,35.

The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass, based on the total amount of the ink, from the viewpoints of improving image density, good fixability and ejection stability. It is more than mass % and below 10 mass %.

As a method of dispersing the pigment to obtain an ink, a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing the pigment, and a method of dispersing the pigment using a dispersant. method, etc.
As a method of making a self-dispersing pigment by introducing a hydrophilic functional group into a pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon) to make it dispersible in water. is mentioned.
As a method of coating the surface of a pigment with a resin and dispersing it, there is a method of encapsulating the pigment in microcapsules to make it dispersible in water. This can be rephrased as a resin-coated pigment. In this case, all the pigments mixed in the ink need not be coated with resin, and uncoated pigments or partially coated pigments may be dispersed in the ink.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant typified by surfactants.
As the dispersant, it is possible to use, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. depending on the pigment.
As a dispersant, RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as a dispersant.
A dispersing agent may be used individually by 1 type, or may use 2 or more types together.

<Organic solvent>
The organic solvent is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- 1,3-pentanediol, petriol and the like.
Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether and the like.
Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Nitrogen-containing heterocyclic compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone and the like. mentioned.
Amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide and the like.
Amines include monoethanolamine, diethanolamine, triethylamine, and the like.
Examples of sulfur-containing compounds include dimethylsulfoxide, sulfolane, thiodiethanol and the like.
Other organic solvents include propylene carbonate and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250° C. or less because it not only functions as a wetting agent but also provides good drying properties.

As the organic solvent, polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of glycol ether compounds include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, and the like.

A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve ink permeability when paper is used as a recording medium.

The content of the organic solvent in the ink is not particularly limited and can be appropriately selected according to the purpose. % by mass or less is preferable, and 20% by mass or more and 60% by mass or less is more preferable.

<Water>
The content of water in the ink is not particularly limited and can be appropriately selected according to the purpose. The following is preferable, and 20% by mass or more and 60% by mass or less is more preferable.

<Surfactant>
Any of fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used as surfactants. Examples of fluorine-based surfactants include perfluoroalkylsulfonic acid compounds, perfluoroalkylcarboxylic acid compounds, perfluoroalkylphosphoric acid ester compounds, perfluoroalkylethylene oxide adducts, and perfluoroalkyl ether groups in side chains. Polyoxyalkylene ether polymer compounds are particularly preferred due to their low foaming properties. Examples of perfluoroalkylsulfonic acid compounds include perfluoroalkylsulfonic acids, perfluoroalkylsulfonates, and the like. Examples of perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. Examples of polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains include sulfuric acid ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in side chains, and polyoxyalkylene ether polymers having perfluoroalkyl ether groups in side chains. Examples thereof include salts of oxyalkylene ether polymers. Counter ions _of salts _in these fluorosurfactants include Li, Na, _K , _NH4 , _NH3CH2CH2OH , _NH2 ( _CH2CH2OH ) _{2 ,} and NH( _CH2CH2OH ). ₃ and the like.
Examples of amphoteric surfactants include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, lauryldihydroxyethylbetaine and the like.
Nonionic surfactants include, for example, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates.
These may be used individually by 1 type, or may use 2 or more types together.

上記一般式（Ｆ－１）で表される化合物において、水溶性を付与するためにｍは０～１０の整数が好ましく、ｎは０～４０の整数が好ましい。

上記一般式（Ｆ－２）で表される化合物において、ＹはＨ、又はＣｍＦ_２ｍ＋１でｍは１～６の整数、又はＣＨ_２ＣＨ（ＯＨ）ＣＨ_２－ＣｍＦ_２ｍ＋１でｍは４～６の整数、又はＣｐＨ_２ｐ＋１でｐは１～１９の整数である。ｎは１～６の整数である。ａは４～１４の整数である。
上記のフッ素系界面活性剤としては市販品を使用してもよい。この市販品としては、例えば、サーフロンＳ－１１１、Ｓ－１１２、Ｓ－１１３、Ｓ－１２１、Ｓ－１３１、Ｓ－１３２、Ｓ－１４１、Ｓ－１４５（いずれも、旭硝子株式会社製）；フルラードＦＣ－９３、ＦＣ－９５、ＦＣ－９８、ＦＣ－１２９、ＦＣ－１３５、ＦＣ－１７０Ｃ、ＦＣ－４３０、ＦＣ－４３１（いずれも、住友スリーエム株式会社製）；メガファックＦ－４７０、Ｆ－１４０５、Ｆ－４７４（いずれも、大日本インキ化学工業株式会社製）；ゾニール（Ｚｏｎｙｌ）ＴＢＳ、ＦＳＰ、ＦＳＡ、ＦＳＮ－１００、ＦＳＮ、ＦＳＯ－１００、ＦＳＯ、ＦＳ－３００、ＵＲ、キャプストーンＦＳ－３０、ＦＳ－３１、ＦＳ－３１００、ＦＳ－３４、ＦＳ－３５（いずれも、Ｃｈｅｍｏｕｒｓ社製）；ＦＴ－１１０、ＦＴ－２５０、ＦＴ－２５１、ＦＴ－４００Ｓ、ＦＴ－１５０、ＦＴ－４００ＳＷ（いずれも、株式会社ネオス社製）、ポリフォックスＰＦ－１３６Ａ，ＰＦ－１５６Ａ、ＰＦ－１５１Ｎ、ＰＦ－１５４、ＰＦ－１５９（オムノバ社製）、ユニダインＤＳＮ－４０３Ｎ（ダイキン工業株式会社製）などが挙げられ、これらの中でも、良好な印字品質、特に発色性、紙に対する浸透性、濡れ性、均染性が著しく向上する点から、Ｃｈｅｍｏｕｒｓ社製のＦＳ－３１００、ＦＳ－３４、ＦＳ－３００、株式会社ネオス製のＦＴ－１１０、ＦＴ－２５０、ＦＴ－２５１、ＦＴ－４００Ｓ、ＦＴ－１５０、ＦＴ－４００ＳＷ、オムノバ社製のポリフォックスＰＦ－１５１Ｎ及びダイキン工業株式会社製のユニダインＤＳＮ－４０３Ｎが特に好ましい。 As the fluorosurfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.
Examples of fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain is preferable because of its low foamability, and in particular, fluorine-based compounds represented by general formulas (F-1) and (F-2) Surfactants are preferred.

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.

In the compound represented by the above general formula (F-2), Y is H, or CmF _2m+1 and m is an integer of 1 to 6, or CH ₂ CH(OH)CH ₂ -CmF _2m+1 and m is 4 to 6 Integer, or CpH _2p+1 where p is an integer from 1-19. n is an integer of 1-6. a is an integer from 4 to 14;
Commercially available products may be used as the fluorosurfactant. Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fleurard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (both manufactured by Sumitomo 3M); Megafac F-470, F -1405, F-474 (both manufactured by Dainippon Ink and Chemicals); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT-250, FT-251, FT-400S, FT-150, FT- 400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) Among these, Chemours FS-3100, FS-34, FS- 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omnova Co., Ltd. and Unidyne DSN- manufactured by Daikin Industries, Ltd. 403N is particularly preferred.

The content of the surfactant in the ink is not particularly limited and can be appropriately selected according to the purpose. 0.001% by mass or more and 5% by mass or less is preferable, and 0.05% by mass or more and 5% by mass or less is more preferable.

<Antifoaming agent>
The antifoaming agent is not particularly limited, and examples thereof include silicone antifoaming agents, polyether antifoaming agents, and fatty acid ester antifoaming agents. These may be used individually by 1 type, or may use 2 or more types together. Among these, silicone-based antifoaming agents are preferred because of their excellent foam breaking effect.

<Preservative and antifungal agent>
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Antirust agent>
The rust inhibitor is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

<pH adjuster>
The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

<<Pre-treatment liquid>>
The pretreatment liquid is a liquid composition that is applied to a recording medium or the like, and causes aggregation or thickening in the ink by coming into contact with the ink that is applied later to the area to which the pretreatment liquid has been applied. is.
The pretreatment liquid preferably contains other components such as a polyvalent metal salt, water, an organic solvent, and a surfactant. As for other components such as water, an organic solvent, and a surfactant, since the same components as those of the above ink can be used, description thereof is omitted.

<Polyvalent metal salt>
The polyvalent metal salt associates with the colorant in the ink by a charge-like action to form an aggregate of the colorant, separate the colorant from the liquid phase, and promote fixation onto the recording medium. This suppresses the occurrence of density unevenness in an image formed with ink.

The polyvalent metal salt is not particularly limited and can be appropriately selected depending on the purpose. Examples include titanium compounds, chromium compounds, copper compounds, cobalt compounds, strontium compounds, barium compounds, iron compounds, aluminum compounds, calcium compounds, salts of magnesium compounds, zinc compounds, nickel compounds, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among these, salts of calcium compounds, magnesium compounds, and nickel compounds are preferable, and alkaline earth metal salts such as calcium and magnesium are more preferable, since they can effectively agglomerate colorants such as pigments.
The polyvalent metal salt is preferably ionic. In particular, the polyvalent metal salt is preferably magnesium salt or calcium salt.

The magnesium compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include magnesium chloride, magnesium acetate, magnesium sulfate, magnesium nitrate and magnesium silicate.
The calcium compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include calcium carbonate, calcium nitrate, calcium chloride, calcium acetate, calcium sulfate and calcium silicate.
The barium compound is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include barium sulfate.
The zinc compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include zinc sulfide and zinc carbonate.
The aluminum compound is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include aluminum silicate and aluminum hydroxide.

The content of the polyvalent metal salt is preferably 1.0% by mass or more and 30.0% by mass or less, and 4.0% by mass or more and 15.0% by mass or less with respect to the mass of the pretreatment liquid. is more preferred. When the content of the polyvalent metal salt is within the above range, the occurrence of density unevenness in the image formed by the ink is further suppressed, and the storage stability of the pretreatment liquid is also improved.

<<Recording medium>>
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, and the like can be used, but impermeable substrates may also be used.
A non-permeable substrate refers to a substrate that has a surface with low water permeability, water absorption, or water adsorption, and includes substrates that have many internal cavities but are not open to the outside. . More quantitatively, it refers to a substrate having a water absorption of 10 mL/m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method.
As the impermeable substrate, for example, plastic films such as vinyl chloride resin films, polyethylene terephthalate (PET) films, polypropylene, polyethylene and polycarbonate films can be suitably used.

<<Ink container>>
The ink storage container includes an ink storage portion that stores ink, and may have other members appropriately selected as necessary.
The shape, structure, size, material, etc. of the ink storage container can be appropriately selected according to the purpose. An ink tank or the like is suitable.

<< Pretreatment liquid storage container >>
The pretreatment liquid storage container includes a pretreatment liquid storage section that stores the pretreatment liquid, and may further have other members appropriately selected as necessary.
The shape, structure, size, material, etc. of the pretreatment liquid storage container can be appropriately selected according to the purpose. , a large-capacity pretreatment liquid tank, and the like are suitable.

<<Recording Device, Recording Method>>
The ink of the present embodiment can be suitably used for various recording apparatuses using an inkjet recording method, such as printers, facsimile machines, copiers, printer/fax/copier complex machines, stereolithography machines, and the like.
A recording apparatus and a recording method refer to a device capable of ejecting ink, a pretreatment liquid, and the like onto a recording medium, and a method of performing recording using the device. A recording medium means a medium to which ink or a pretreatment liquid can adhere even temporarily.
This recording apparatus can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices called pre-processing devices and post-processing devices. .
The recording apparatus and the recording method may have pretreatment liquid drying means for use in a pretreatment liquid drying process performed between the pretreatment liquid applying process and the ink applying process. By performing the pretreatment liquid drying process, the ink can be applied while the components of the pretreatment liquid are fixed on the recording medium. can be obtained. The pretreatment liquid drying step and the pretreatment liquid drying means include, for example, means for heating and drying the printing surface and the back surface of the recording medium. Although the pretreatment liquid drying means is not particularly limited, for example, a hot air heater or an infrared heater can be used.
Also, the recording apparatus and recording method are not limited to those that visualize significant images such as characters and graphics with ink. For example, it includes those that form patterns such as geometric patterns, and those that form three-dimensional images.
In addition, unless otherwise specified, the recording apparatus includes both a serial type apparatus in which the ejection head is moved and a line type apparatus in which the ejection head is not moved.
Furthermore, this recording device can be used not only as a desktop type, but also as a wide recording device that can print on A0 size recording media, and for example, can use continuous paper wound into a roll as a recording medium. A continuous feed printer is also included.
An example of a recording apparatus will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. An image forming apparatus 400 as an example of a recording apparatus is a serial image forming apparatus. A mechanical unit 420 is provided inside the exterior 401 of the image forming apparatus 400 . Each ink container 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminated film. It is made up of members. The ink containing portion 411 is housed, for example, in a container case 414 made of plastic. Thus, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided on the far side of the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404 . As a result, each ink discharge port 413 of the main tank 410 communicates with the ejection head 434 for each color via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 onto the printing medium.

It should be noted that the method of using the ink is not limited to the ink jet recording method, and can be widely used. In addition to the inkjet recording method, for example, a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method and a spray coating method can be used.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

First, methods for measuring various physical properties in Synthesis Examples, Production Examples, and Preparation Examples described below will be described.

<Glass transition temperature (Tg), melting point (Tm), crystallization temperature (Tc)>
4 g of resin dispersion liquid (resin emulsion) is placed in a container so as to spread uniformly, dried at 70 ° C. for 1 hour, then dried at 130 ° C. for 1 hour, and further dried at 130 ° C. under reduced pressure to obtain a measurement sample. A solid was obtained.
The thermal properties of each measurement sample were measured using a differential scanning calorimeter (DSC) (Q2000 manufactured by TA Instruments) under the following conditions. Specifically, it was measured as follows.
(Measurement condition)
Sample container: Aluminum sample pan (with lid)
Sample amount: 5mg
Reference aluminum sample pan (empty container)
Atmosphere: nitrogen (flow rate 50 mL/min)
Start temperature: -80°C
Heating rate: 10°C/min
End temperature: 130°C
Holding time: 1 min
Temperature drop rate: 10°C/min
End temperature: -80°C
Holding time: 5min
Heating rate: 10°C/min
End temperature: 130°C
Measurement was performed under the above measurement conditions, and a graph of "heat absorption and heat release" versus "temperature" was created.
A characteristic inflection observed in the first heating process was taken as the glass transition temperature (Tg). For Tg, the value obtained by the midpoint method from the DSC curve was used.
The melting point was the temperature at the top of the melting (endothermic) peak obtained in the second heating process. Further, the heat of fusion was calculated by taking the endotherm in the heating process as the melting region.
The crystallization peak temperature was defined as the temperature at the apex of the crystallization (exothermic) peak obtained during the cooling process. The amount of heat of crystallization was calculated by taking the heat generated in the process of cooling down as the crystallization area.

<Volume average particle size>
The volume average particle size was measured by dynamic light scattering using a zeta potential/particle size measuring system (ELSZ-1000, manufactured by Otsuka Electronics Co., Ltd.).
First, 0.2 g of a resin dispersion (resin emulsion) was taken, then ion-exchanged water was added to dilute it 100 times. . Then, measurement was performed under the conditions of temperature: 25° C., dust cut (number of times: 5, upper: 5, lower: 100), and number of accumulations: 70 to obtain the volume average particle size of the solid content in the ink.

<Preparation Example of Black Pigment Dispersion>
After premixing the following formulation mixture, a disk-type bead mill (manufactured by Shinmaru Enterprises Co., Ltd., KDL type, media: using zirconia balls with a diameter of 0.3 mm) is used to circulate and disperse for 7 hours to obtain a black pigment dispersion (pigment concentration : 15% by mass).
・Carbon black pigment (trade name: Monarch800, manufactured by Cabot Corporation): 15.0 parts by mass ・Acrylic polymer dispersant (trade name: Disperbyk-2010, manufactured by BYK Japan): 5.0 parts by mass ・Ion-exchanged water: 80.0 parts by mass

<Synthesis Example of Crystalline Polyester Polyol 1>
A 5 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple was charged with 1,4-butanediol as the diol, sebacic acid as the dicarboxylic acid, and a molar ratio of diol to dicarboxylic acid of OH. /COOH=1.40. Then, after the inside of the reaction vessel is sufficiently replaced with nitrogen gas, 300 ppm of titanium tetraisopropoxide is added to the monomer, and the temperature is raised to 200° C. in about 4 hours under a nitrogen gas stream. The temperature was raised to 230° C. over a period of time, and the reaction was carried out until no outflow water occurred. After that, the mixture was reacted for 1 hour under a reduced pressure of 10 mmHg to 30 mmHg to obtain "Crystalline polyester polyol 1".

<Synthesis Example of Crystalline Polyester Polyol 2>
A 5 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple was charged with 1,4-butanediol as the diol and dodecanedioic acid as the dicarboxylic acid with a molar ratio of diol to dicarboxylic acid of It charged so that it might be set to OH/COOH=1.40. Then, after the inside of the reaction vessel is sufficiently replaced with nitrogen gas, 300 ppm of titanium tetraisopropoxide is added to the monomer, and the temperature is raised to 200° C. in about 4 hours under a nitrogen gas stream. The temperature was raised to 230° C. over a period of time, and the reaction was carried out until no outflow water occurred. After that, the mixture was reacted for 1 hour under a reduced pressure of 10 mmHg to 30 mmHg to obtain "Crystalline Polyester Polyol 2".

<Synthesis Example of Amorphous Polyester Polyol 3>
A 2 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple was charged with propylene glycol as a diol and terephthalic acid and succinic acid as dicarboxylic acids in a molar ratio (terephthalic acid/succinic acid) = It was prepared so that it might become 80/20 and OH/COOH=1.4. Then, after the inside of the reaction vessel is sufficiently replaced with nitrogen gas, 300 ppm (relative to the monomer) of titanium tetraisopropoxide is added, and the temperature is raised to 200° C. in about 4 hours under a nitrogen gas stream. The temperature was raised to 230° C. over 2 hours, and the reaction was carried out until no outflow occurred. After that, the mixture was reacted for 1 hour under a reduced pressure of 10 mmHg to 30 mmHg to obtain "amorphous polyester polyol 3".

<Synthesis Example of Crystalline Polyester Polyol 4>
A 5 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple was charged with 1,4-butanediol as the diol, sebacic acid as the dicarboxylic acid, and a molar ratio of diol to dicarboxylic acid of OH. /COOH=1.10. Then, after the inside of the reaction vessel is sufficiently replaced with nitrogen gas, 300 ppm of titanium tetraisopropoxide is added to the monomer, and the temperature is raised to 200° C. in about 4 hours under a nitrogen gas stream. The temperature was raised to 230° C. over a period of time, and the reaction was carried out until no outflow water occurred. After that, the reaction was carried out for 4 hours under a reduced pressure of 10 mmHg to 30 mmHg. Next, the temperature was lowered to 180° C., trimellitic anhydride was added as an acid value adjuster so that the acid value was 17, and the mixture was reacted for 1 hour to obtain “Crystalline Polyester Polyol 4”.

<Synthesis Example of Crystalline Polyester Polyol 5>
A 5 L four-necked flask equipped with a nitrogen inlet, a dehydration tube, a stirrer and a thermocouple was charged with ethylene glycol as the diol and dodecanedioic acid as the dicarboxylic acid with a molar ratio of diol to dicarboxylic acid of OH/COOH= It was prepared so that it might be set to 1.40. Then, after the inside of the reaction vessel is sufficiently replaced with nitrogen gas, 300 ppm of titanium tetraisopropoxide is added to the monomer, and the temperature is raised to 200° C. in about 4 hours under a nitrogen gas stream. The temperature was raised to 230° C. over a period of time, and the reaction was carried out until no outflow water occurred. After that, the mixture was reacted for 1 hour under a reduced pressure of 10 mmHg to 30 mmHg to obtain "Crystalline Polyester Polyol 5".

<Preparation Example of Crystalline Polyester Urethane Resin Dispersion A>
50 g of crystalline polyester polyol 1, 2.8 g of 2,2-bis(hydroxymethyl)propionic acid, 4,4′-dicyclohexylmethane diisocyanate 19 were placed in a 1 L separable flask equipped with a stirrer, thermometer, and reflux tube. .3 g, 2.1 g of triethylamine, and 39 g of methyl ethyl ketone as an organic solvent were charged while introducing nitrogen, one drop of the catalyst (di(2-ethylhexanoic acid) tin (II) was added, and then the temperature was raised to 60°C. After refluxing for 2 hours, the temperature was lowered to 40° C. and maintained at that temperature.After confirming the NCO% present in the system, 138 g of water was slowly added while stirring at a rate of 500 rpm to make fine particles, followed by heating for 30 minutes. After stirring, 0.33 g of diethylenetriamine was added, and the mixture was heated and stirred for 1 hour.Finally, by removing methyl ethyl ketone, the solid content was 35% and the volume average particle diameter (D50) was 34 nm. The resin obtained after drying the obtained resin dispersion had a melting point (heat of fusion) of 42° C. (20 J/g) and a crystallization temperature (heat of crystallization) of −16° C. (11 J/g). , oxidation (AV) was 16 mg KOH/g.

<Preparation Example of Crystalline Polyester Urethane Resin Dispersion B>
50 g of crystalline polyester polyol 2, 2.9 g of 2,2-bis(hydroxymethyl)propionic acid, 4,4′-dicyclohexylmethane diisocyanate 23 were placed in a 1 L separable flask equipped with a stirrer, thermometer, and reflux tube. .5 g, 2.2 g of triethylamine, and 41 g of methyl ethyl ketone as an organic solvent were charged while introducing nitrogen, one drop of the catalyst (di(2-ethylhexanoic acid) tin (II) was added, and then the temperature was raised to 60°C. After refluxing for 2 hours, the temperature was lowered to 40° C. and maintained at that temperature.After confirming the NCO% present in the system, 146 g of water was slowly added while stirring at a rate of 500 rpm to make fine particles, followed by heating for 30 minutes. After stirring, 0.63 g of diethylenetriamine was added, and the mixture was heated and stirred for 1 hour.Finally, by removing methyl ethyl ketone, a solid content of 35% and a volume average particle diameter (D50) of 34 nm were obtained. The resin obtained after drying the obtained resin dispersion has a melting point (heat of fusion) of 45° C. (24 J/g) and a crystallization temperature (heat of crystallization) of −5° C. (15 J/g). , oxidation (AV) was 16 mg KOH/g.

<Preparation Example of Amorphous Polyester Urethane Resin Dispersion Liquid C>
140 g of amorphous polyester polyol 3, 10.2 g of 2,2-bis(hydroxymethyl)propionic acid, and 4,4′-dicyclohexylmethane diisocyanate were placed in a 1 L separable flask equipped with a stirrer, thermometer, and reflux tube. 64.0 g of triethylamine, 6.5 g of triethylamine, and 115 g of methyl ethyl ketone as an organic solvent were charged while introducing nitrogen, one drop of the catalyst (di(2-ethylhexanoic acid) tin (II) was added, and then the temperature was raised to 60°C. After that, the temperature was lowered to 40° C. and maintained at this temperature, and after confirming the NCO% present in the system, 410 g of water was slowly added while stirring at a speed of 500 rpm to make fine particles, and the mixture was stirred for 30 minutes. After heating and stirring, 4.25 g of diethylenetriamine was added, and the mixture was heated and stirred for 1 hour.Finally, methyl ethyl ketone was removed to obtain an amorphous polyester urethane resin dispersion having a solid content of 35% and a volume average particle diameter (D50) of 170 nm. Liquid C” was obtained. The resin obtained after drying the obtained resin dispersion had a glass transition temperature of 78° C. and an oxidation (AV) of 20 mg KOH/g.

<Preparation Example of Crystalline Polyester Resin Dispersion D>
50 g of crystalline polyester polyol 4 and 50 g of methyl ethyl ketone were mixed in a 300 mL four-necked flask equipped with a nitrogen inlet tube, a stirrer and a thermocouple, and dissolved at 40° C. under a stream of nitrogen, and then 1.53 g of triethylamine was added. added. After stirring for 1 hour, 166.7 g of ion-exchanged water was added dropwise at 7.5 g/min. After stirring for 30 minutes, methyl ethyl ketone was removed under reduced pressure. A "crystalline polyester resin dispersion liquid D" was obtained. The resin obtained after drying the obtained resin dispersion has a melting point (heat of fusion) of 60° C. (94 J/g), a crystallization temperature (heat of crystallization) of 40° C. (92 J/g), and an oxidation (AV) of 17 mg KOH. /g.

<Preparation Example of Crystalline Polyester Urethane Resin Dispersion E>
50 g of crystalline polyester polyol 5, 2.4 g of 2,2-bis(hydroxymethyl)propionic acid, 4,4′-dicyclohexylmethane diisocyanate 18 were placed in a 1 L separable flask equipped with a stirrer, thermometer, and reflux tube. .5 g, 1.9 g of triethylamine, and 40 g of methyl ethyl ketone as an organic solvent were charged while introducing nitrogen, and one drop of the catalyst (di(2-ethylhexanoic acid) tin (II) was added, and then the temperature was raised to 60°C. After refluxing for 2 hours, the temperature was lowered to 40° C. and maintained at that temperature.After confirming the NCO% present in the system, 136 g of water was slowly added while stirring at a speed of 500 rpm to make fine particles, followed by heating for 30 minutes. After stirring, 2.4 g of isophorone diamine was added, and the mixture was heated and stirred for 1 hour.Finally, by removing methyl ethyl ketone, a "crystalline polyester urethane resin dispersion liquid having a solid content of 30% and a volume average particle diameter (D50) of 76 nm was obtained. E" was obtained. The resin obtained after drying the obtained resin dispersion had a melting point (heat of fusion) of 77°C (24 J/g) and a crystallization temperature (heat of crystallization) of 52°C (13 J/g). , oxidation (AV) was 17 mg KOH/g.

<Preparation Example of Ink 1>
Ink 1 was prepared by mixing and stirring the following formulation and filtering through a polypropylene filter with an average pore size of 0.8 μm.
・Black pigment dispersion: 20.0 parts by mass ・Compound represented by the general formula (1) (Surfinol 420, manufactured by Nissin Chemical Industry Co., Ltd.): 0.5 parts by mass ・Bis(2-ethylhexyl sulfosuccinate) ) Sodium: 0.5 parts by mass Siloxane compound (BYK-019): 0.1 parts by mass Crystalline polyester urethane resin dispersion A: 10.0 parts by mass (solid content)
1,2-propanediol: 15.0 parts by mass 1,3-butanediol: 10.0 parts by mass Proxel LV (manufactured by Avecia, antiseptic): 0.1 parts by mass Ion-exchanged water: remaining amount (Total: 100 parts by mass)

<Preparation Examples of Inks 2 to 22>
Inks 2 to 22 were prepared in the same manner as in Ink 1, except that the ink formulation was changed to those shown in Tables 1 to 3 below. The unit for the content of each component in Tables 1 to 3 is "parts by mass", and the total amount of each ink is 100 parts by mass. The resin content in Tables 1 to 3 indicates the solid content.

<Preparation example of pretreatment liquid 1>
After mixing and stirring with the following formulation, pretreatment liquid 1 was prepared by filtering through a 5 μm filter (Minisart manufactured by Sartorius).
1,2-propanediol: 15.0 parts by mass Ethylene glycol monobutyl ether: 13.0 parts by mass Emulgen LS-106 (surfactant manufactured by Kao Corporation): 0.5 parts by mass Calcium acetate: 6.0 Part Proxel LV (manufactured by Avecia, antiseptic): 0.1 parts by mass Ion-exchanged water: remaining amount (total: 100 parts by mass)

<Preparation example of pretreatment liquids 2 to 3>
In the preparation example of pretreatment liquid 1, pretreatment liquids 2 and 3 were prepared in the same manner as in preparation example of pretreatment liquid 1, except that the formulation of the pretreatment liquid was changed to that shown in Table 4 below. The unit for the content of each component in Table 4 is "parts by mass", and the total amount of each pretreatment liquid is 100 parts by mass.

<Formation of solid image>
A coated white ball JET STAR (basis weight: 270 g/m ² , manufactured by Nippon Paper Industries Co., Ltd.) was prepared by pre-coating the pretreatment liquid with a bar coater so that the coating amount was 10 g/m ² . Next, using an image forming apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) filled with ink under environmental conditions adjusted to 23° C.±0.5° C. and 50±5% RH, a solid image is formed by an inkjet method. printed. In the case where the pretreatment liquid drying step is provided between the pretreatment liquid application step and the ink application step, a drying step for 2 minutes at 70° C. is interposed between the pretreatment liquid application step and the ink application step. is.

<Evaluation of dryness>
The solid image formed as described above was allowed to stand for a predetermined time in an environment of 23° C.±0.5° C. to dry. A filter paper was pressed against the solid image area after drying, and the drying property of the ink was evaluated according to the following criteria based on how the ink was transferred to the filter paper. Table 5 shows the evaluation results. Note that up to C is the allowable range.
〔Evaluation criteria〕
A: Transfer to filter paper disappears after drying for 15 minutes B: Transfer to filter paper disappears after drying for 30 minutes C: Transfer to filter paper disappears after drying for 60 minutes D: Transfer to filter paper disappears even after drying for 60 minutes won't go away

<Evaluation of abrasion resistance>
Immediately after printing, the solid image formed as described above is dried at 80° C. for 30 seconds. Thereafter, the sample is returned to room temperature, and after 10 seconds, dry cotton (Kanakin No. 3) is rubbed back and forth 30 times with a weight of 100 g applied to the solid image area. The abrasion resistance was visually evaluated according to the following evaluation criteria. Table 5 shows the evaluation results. Note that up to C is the allowable range.
〔Evaluation criteria〕
A: Almost no scratches are observed at the stage of rubbing 30 times B: Some scratches remain at the stage of rubbing 30 times, but there is no problem in practical use C: Some scratches remain at the stage of rubbing 15 times, but actual use No problem D: The image density is reduced by rubbing 15 times or less, causing a problem in actual use.

<Evaluation of density unevenness>
The solid image formed as described above is dried at 80° C. for 2 minutes. This was visually observed, and image density unevenness was evaluated according to the following evaluation criteria. Table 5 shows the evaluation results. Note that up to C is the allowable range.
〔Evaluation criteria〕
A: Density unevenness is not observed B: Density unevenness is slightly observed, but no problem in practical use C: Density unevenness is observed, but it is not a problem in practical use D: Obvious density unevenness is observed, causing problems in actual use

<Evaluation of ejection stability>
Under the environmental conditions adjusted to 23°C ±0.5°C and 50±5% RH, an inkjet method using an image forming device (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) was used, and head cleaning was executed from the printer maintenance command. After that, I printed a test chart. After confirming with the test chart that all the nozzle channels are in the ejection state, a solid image is printed continuously for 3 minutes, then the head cap is removed and the test chart is printed again after leaving it for 1 minute, and the following evaluation is performed. The ejection stability was judged according to the standard. Table 5 shows the evaluation results. Note that up to C is the allowable range.
〔Evaluation criteria〕
A: The number of non-ejection channels is 5 or less B: The number of non-ejection channels is 6 or more and 10 or less C: The number of non-ejection channels is 11 or more and 20 or less D: The number of non-ejection channels is 21 or more

400 Image forming apparatus 401 Exterior of image forming apparatus 401c Cover of apparatus main body 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For black (K), cyan (C), magenta (M), and yellow (Y) main tank 411 ink storage unit 413 ink discharge port 414 storage container case 420 mechanism unit 434 ejection head 436 supply tube

Japanese Unexamined Patent Application Publication No. 2020-143189

Claims (11)

An ink containing a resin, a coloring material, and water,
The resin is a polyester urethane resin having crystallinity,
The melting peak temperature (Tm) of the resin is 30° C. or higher and 100° C. or lower,
An ink characterized by further containing a compound represented by the following general formula (1).

(In the general formula (1), x+y represents an integer of 0 or more and 10 or less.) 2. The ink according to claim 1, wherein x+y represents an integer of 0 or more and 3 or less in the general formula (1). 3. The ink according to claim 1, wherein the polyester urethane resin having crystallinity and the compound represented by the general formula (1) have a mass ratio of 5:1 to 20:1 in the ink. 4. The ink according to any one of claims 1 to 3, further comprising a dialkylsulfosuccinic acid or a salt of a dialkylsulfosuccinic acid. 5. The ink according to any one of claims 1 to 4, further comprising a siloxane compound. 6. The ink according to claim 5, wherein the content of the siloxane compound is 0.01% by mass or more and 1.0% by mass or less with respect to the mass of the ink. An ink container containing the ink according to any one of claims 1 to 6. 8. A recording apparatus comprising: the ink container according to claim 7; and ink applying means for applying the contained ink. A recording method comprising an ink application step of applying the ink according to claim 1 . 10. The recording method according to claim 9, further comprising a pretreatment liquid applying step of applying a pretreatment liquid containing a polyvalent metal salt to at least a region to which the ink is to be applied, prior to the ink applying step. 11. The recording method according to claim 10, further comprising a pretreatment liquid drying step of drying the applied pretreatment liquid between the pretreatment liquid application step and the ink application step.

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