JP6044217B2 - Ink jet recording ink, and ink cartridge, ink jet recording apparatus, ink jet recording method and ink recorded matter using the ink - Google Patents

Description

  The present invention relates to an inkjet recording ink, and an ink cartridge, an inkjet recording apparatus, an inkjet recording method, and an ink recorded matter using the ink.

In recent years, as an image forming method, since the process is simple and full color can be easily obtained as compared with other recording methods, there is an advantage that a high-resolution image can be obtained even with an apparatus having a simple configuration. The method has become widespread.
Inkjet recording method is a method of causing a small amount of ink to fly with pressure generated using bubbles generated by heat, piezo or static electricity, and to adhere to a recording medium such as paper, and to dry quickly, or recording medium In this method, an image is formed by penetrating into the printer, and its application has been expanded to personal and industrial printers and printing.

In the ink jet recording apparatus, a water-based ink using a water-soluble dye as a colorant is mainly used. However, the dye ink has a defect that it is inferior in weather resistance and water resistance. Therefore, in recent years, research on pigment inks using pigments instead of water-soluble dyes has been advanced. However, the pigment ink is still inferior in color development, ink ejection stability, and storage stability to the dye ink.
In addition, with the improvement of image quality improvement technology for OA printers, image density equivalent to that of dye ink is required for both pigment ink and plain paper as a recording medium. However, when plain paper is used as a recording medium, the pigment ink has a problem that the pigment density on the paper surface is lowered by penetrating into the paper and the image density is lowered.

  In recent years, demand for industrial applications has been increasing, and high-speed printing is desired. Ink jet printers equipped with line heads have been proposed along with high-speed printing. In order to increase the drying speed of the ink adhering to the recording medium for high-speed printing, a means is taken to accelerate drying by adding a penetrant to the ink and allowing water to penetrate into the recording medium. In addition to this, the penetrability of the pigment into the recording medium is increased, and the image density is further lowered.

Various methods have been proposed for improving the image density. For example, by adjusting the surface tension of the ink higher than 35 mN / m and slowing the penetration of the ink into the paper, the ink is highly effective in improving the image density and reducing the back-through by keeping the ink on the paper surface. It is on the market. However, as a result of decreasing the permeability to paper, the drying property after printing on plain paper is remarkably deteriorated, resulting in deterioration of fixing property and bleeding between colors when multiple colors are used.
In order to improve the drying property of the ink, a printing apparatus having a device that heats the paper surface with a heater before and after printing to accelerate the drying of the ink has been proposed. The advantage of the ink jet recording method is lost because the energy is consumed for heating and the energy is wasted for heating.

Patent Document 1 discloses that the rate of increase in viscosity (mPa · s /%) accompanying water evaporation of ink is 5.0 or less and the amount of water evaporation is 30% by weight or less with respect to the total ink weight. There has been proposed an ink configured to have a viscosity increase rate exceeding 50 between 30 and 45% by weight.
According to this proposed ink, when the ink lands on the plain paper and the water evaporates, the viscosity rapidly increases. Therefore, even if printing is performed at high speed, the penetration of the pigment into the paper is suppressed and high image density is indicated. Yes. However, since the proposed ink rapidly thickens when the water evaporates, if the water evaporates in the ink jet recording apparatus, particularly in the nozzle, the ink ejection stability decreases due to the thickening, or the ink around the nozzle There was a problem of sticking.

Various proposals have been made to deal with the above problems.
For example, Patent Document 1 proposes a copolymer composed of various monomers as a resin dispersant by improving the image density by defining the characteristics of carbon black. However, only the styrene-acrylic resin is used as an example in Patent Document 1, and there is a problem that none of ink storage stability, high image density, and ejection stability can be satisfied sufficiently. It was.
Patent Document 2 discloses an invention relating to an ink containing a water-dispersible pigment coated with a polymer dispersant. From the viewpoint of dispersion stability and cohesiveness of the pigment, A styrene-maleic acid copolymer has been proposed as a polymer compound containing a group is preferred. However, even when the proposal according to Patent Document 2 is used, when an image is formed on plain paper, there is a problem that the pigment does not stay so much on the paper surface and a sufficient image density cannot be obtained.

This invention makes it a subject to solve the said various problems in the past and to achieve the following objectives.
That is, the present invention provides an ink for ink jet recording having good ink storage stability, high image density on plain paper, good ink ejection stability from a recording head, and no ink sticking around the nozzle, and An object of the present invention is to provide an ink cartridge, an ink jet recording apparatus, an ink jet recording method, and an ink recorded matter using the ink.

As a result of intensive studies, the present inventors have used a copolymer of a monomer having a specific structural unit as a composition of an ink for ink jet recording, so that the ink for ink jet recording landed on a recording medium such as plain paper. In addition, it has been found that a high image density can be obtained by causing aggregation and thickening due to water insolubilization in response to a change in pH (change to the acidic side) and suppressing penetration of ink into paper.
Therefore, an ink jet recording ink according to the present invention for solving the above-described problems contains water, a wetting agent, a colorant, and a copolymer, and is ejected onto plain paper. The inkjet recording ink has a pH of 9 to 11, and the copolymer is represented by at least a structural unit represented by the following formula (1) and the following general formula (2). It consists of a copolymer with a structural unit.

[In the general formula (2), R represents an alkyl group having 1 to 4 carbon atoms, M ⁺ represents at least half or all of them are alkali metal ions and organic amine ions, and the rest represent protons. ]

  According to the present invention, ink for ink jet recording having good ink storage stability, high image density on plain paper, good ink ejection stability from the recording head, and no ink sticking around the nozzle, and An ink cartridge, an ink jet recording apparatus, an ink jet recording method, and an ink recorded matter using the ink can be provided.

It is a schematic plan view for explaining an example of the ink cartridge of the present invention. FIG. 2 is a schematic plan view including a case (exterior) of the ink cartridge of the present invention shown in FIG. 1. 1 is a perspective view showing an example of a serial type ink jet recording apparatus of the present invention. FIG. 4 is a partially enlarged sectional view of the ink jet recording apparatus shown in FIG. 3. FIG. 4 is another partially enlarged sectional view of the ink jet recording apparatus shown in FIG. 3.

  The ink for ink jet recording according to the present invention is an ink for ink jet recording containing water, a wetting agent, a colorant, and a copolymer, wherein the copolymer is represented by at least the following formula (1). It consists of a copolymer of the structural unit represented and the structural unit represented by following General formula (2).

[In the general formula (2), R represents an alkyl group having 1 to 4 carbon atoms, M ⁺ represents at least half or all of them are alkali metal ions and organic amine ions, and the rest represent protons. ]

  Moreover, it is preferable that the structural unit represented by the general formula (2) is a structural unit represented by the following general formula (3).

[In the general formula (3), M ⁺ is a half or more or all of them are alkali metal ions and organic amine ions, and the rest represent protons. ]

Here, the general formulas (2) and (3) are preferably ionized by neutralizing a part or all of them with a base. Examples of the base used for neutralization include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium, mono, di or trimethylamine, mono, di or triethylamine, monoethanolamine, diethanolamine and triethanol. Amine, methylethanolamine, methyldiethanolamine, dimethylethanolamine, choline, aminoethanepropanediol, monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, trishydroxymethylaminomethane, aminoethylpropanediol, tetramethylammonium, Organic amines such as tetraethylammonium and tetrabutylammonium, monophorin, N-methylmonoformin, N-methyl-2pi Pyrrolidone, organic amine and cyclic amine 2-pyrrolidone, and the like.
In addition, you may add another polymer component to the said copolymer.

Next, the ink for ink jet recording according to the present invention, and the ink cartridge, ink jet recording apparatus, ink jet recording method and ink recorded matter using the ink will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

<Ink for inkjet recording>
The ink for ink jet recording of the present embodiment (hereinafter sometimes referred to as “ink”) includes water, a wetting agent, a colorant, and a copolymer that causes aggregation and thickening as the pH decreases. It contains at least, and further contains other components as required.
The ink for ink-jet recording according to the present invention causes aggregation and thickening due to water insolubility when the copolymer is landed on a recording medium such as plain paper, and the penetration of the ink into the paper is suppressed, resulting in a high image density. Can be obtained.
As described above, the copolymer in which aggregation and thickening occur with a decrease in pH is a copolymer of the structural unit represented by the formula (1) and the structural unit represented by the general formula (2). It is a polymer.
Hereinafter, the components constituting the ink jet recording ink of the present invention will be described in more detail.

(Copolymer)
The copolymer used in the present invention has the property that when ink for ink jet recording lands on a recording medium such as plain paper, the coagulation thickening due to water insolubilization occurs in response to a change in pH (change to the acidic side). It is what you have. By this function, it is possible to obtain a high image density by suppressing the penetration of the ink into the paper.
In the present invention, in particular, by using the copolymer as a dispersant, it is possible to provide an ink having a high image density and good ejection stability from a nozzle.

The polymerization method of the compound used in the present invention is not particularly limited, and a known polymerization method can be used.
For example, a monomer represented by the following formula (4) and a monomer represented by the following general formula (5) using water as a medium, and a polymerization initiator and a chain transfer agent, if necessary, Polymerization is performed at 100 ° C. to obtain a copolymer of the structural unit represented by the formula (1) and the structural unit represented by the general formula (2), but the present invention is not particularly limited thereto.

[In said general formula (5), R shows a C1-C4 alkyl group. ]

The ink for inkjet recording according to the present invention is preferably adjusted to have an initial pH of 9 to 11, preferably 9.5 to 10. By setting the initial pH of the ink within this range, the viscosity of the ink (initial viscosity) can be lowered, and the ink can have sufficient fluidity and storage stability.
The ink for inkjet recording according to the present invention is characterized in that when the pH of the ink is 8.5 or lower, the hydrophobicity of the polymer becomes high and the resin becomes difficult to dissolve in water, so that the resin precipitates and agglomerates and thickens. This is a feature of the present invention not found in conventional inks.

  In the image formation using the inkjet recording ink according to the present invention, plain paper can be suitably used as a recording medium. The pH of plain paper (paper surface) is generally in the range of 6.5 to 7.5. When ink lands on such a paper surface, the ink is affected by the pH of the paper surface. That is, it is affected by the surface of the paper itself and / or an acidic component present on the paper surface. When ink having an initial pH of 9 to 11 before ejection reaches the surface of plain paper, the pH of the ink falls to a value between the initial pH of the ink and the pH value of the paper. It is considered that the pH of the ink after landing falls to 8.5 or less.

  For this reason, when the ink for ink jet recording according to the present invention lands on the paper surface, it agglomerates and thickens, whereby penetration into the paper is suppressed, and a large amount of colorant (pigment) remains on the paper surface. According to the present invention, it is possible to leave a large amount of colorant (pigment) on the paper surface. Therefore, it is possible to provide an ink that can provide a high image density when an image is formed.

The ink for ink jet recording according to the present invention can be made into an ink having a low viscosity and sufficient fluidity and storage stability by increasing the pH before discharging, and ejecting it onto the paper surface. After landing and lowering the pH of the ink, the ink thickens.
Therefore, the ink for ink jet recording according to the present invention has a high rate of change in viscosity accompanying a decrease in pH. Here, the viscosity change rate measured by the following method is preferably 30% or more, and more preferably 50% or more. If the viscosity change rate is too small, the ink penetrates into the paper and a sufficient image density cannot be obtained.

  In the present invention, the viscosity change rate can be determined by the following method, which is defined as the viscosity change rate in the present invention.

(Viscosity change rate)
The viscosity change rate is obtained from the following equation as the viscosity change rate when the pH of the ink is adjusted to 8.5 with an aqueous HCl solution or the like with respect to the initial ink viscosity.

  Viscosity change rate (%) = [(viscosity viscosity-initial viscosity) / initial viscosity] × 100

Measurement method: After adjusting the ink liquid temperature to 25 ° C. and measuring the initial viscosity, the viscosity when the HCL aqueous solution (20 wt%) is dropped to pH 8.5 is measured, and the rate of change in viscosity is calculated by the above formula. To do.
Viscometer: Viscometer MODEL RC-500 manufactured by Toki Sangyo Co., Ltd.

  In the present invention, the ratio of the structural unit represented by the formula (1) constituting the copolymer and the structural unit represented by the general formula (2) is not particularly limited, but aggregation due to water insolubilization accompanying a decrease in pH. From the viewpoint of thickening, the ratio of the structural unit represented by the formula (1) and the repeating unit of the structural unit represented by the general formula (2) is preferably in the range of 40:60 to 80:20, and 50: 50-75: 25 is more preferable.

What is necessary is just to select suitably the quantity of the copolymer in the case of using the copolymer used for this invention as a dispersing agent by the kind of coloring agent (pigment), and 0.005-5 weight with respect to 1 weight part of coloring agents. Part. Preferably it is 0.01-2 weight part with respect to 1 weight part of coloring agents, More preferably, it is 0.02-0.5 weight part with respect to 1 weight part of coloring agents. When it is in the range of 0.005 to 5 parts by weight, the dispersibility of the colorant is improved and the stability of the ink with time is improved, and when it is in the range of 0.01 to 2 parts by weight, these effects are further enhanced. In particular, in the range of 0.02 to 0.5 parts by weight, the ink stability over time is further improved.
Moreover, you may use together the dispersing agent described later with a copolymer in the range which does not impair the said effect.

(water)
As water used in the present invention, pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used.
The water content is preferably 20 to 60% by weight based on the total amount of ink.

(Wetting agent)
The wetting agent used in the present invention is necessary for improving ejection stability by providing a moisturizing effect in the ink composition. The content is preferably 10 to 50% by weight based on the total amount of ink. When the content is less than 10% by weight, the ink easily evaporates, and thickened ink may be clogged due to evaporation of the ink in the ink supply system in the ink jet recording apparatus. When the content is more than 50% by weight, clogging of thickened ink is less likely to occur in the ink jet recording apparatus, but it is necessary to reduce the amount of solids such as pigments and resins in order to make the ink have a desired viscosity. In this case, the image density of the recorded matter may be lowered.

Although the following are illustrated as a wetting agent used by this invention, It is not limited to these. For example, ethylene glycol, diethylene glycol, 1,3-butanediol, 3-methyl-1,3-butyl glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,2,4-butanetriol, 1,2,3 -Polyhydric alcohols such as butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetra Polyhydric alcohol alkyl ethers such as tylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, γ-butyrolactone, amides such as formamide, N-methylformamide, N, N-dimethylformamide , Amines such as monoethanolamine, diethanolamine, triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol, propylene carbonate, ethylene carbonate, etc. That.
These wetting agents can be used alone or in admixture of two or more. Among these, the inclusion of 1,3-butanediol, diethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol and / or glycerin is excellent in preventing discharge failure due to moisture evaporation. Effect.

(Coloring agent)
The content of the pigment as a colorant used in the present invention in the recording ink is preferably 0.1% by weight or more and 20.0% by weight or less. The volume average particle diameter (D50) of the pigment is preferably 150 nm or less.
Here, the volume average particle diameter (D50) of the pigment is measured by a dynamic light scattering method using Microtrac UPA manufactured by Nikkiso Co., Ltd. in an environment of 23 ° C. and 55% RH.
There is no restriction | limiting in particular as these pigments, According to the objective, it can select suitably, For example, any of an inorganic pigment and an organic pigment may be sufficient. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, metal powder, and carbon black. Among these, carbon black is preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

Examples of the organic pigment include azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable.
Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include a phthalocyanine pigment, a perylene pigment, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxazine pigment, an indigo pigment, a thioindigo pigment, an isoindolinone pigment, a quinofullerone pigment, and a rhodamine B lake pigment. It is done. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

Examples of black materials include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI pigment black 11), titanium oxide, and the like. And organic pigments such as aniline black (CI Pigment Black 1).
As the carbon black, a furnace method, a carbon black produced by the channel method, primary particle diameter of, 15Nm～40nm, specific surface area by BET ^{method, 50m 2 / g~300m 2 / g} , DBP oil absorption amount 40ml / 100 g to 150 ml / 100 g, those having a volatile content of 0.5% to 10% and a pH value of 2 to 9 are preferred.
A commercially available product can be used as the carbon black. Examples of commercially available products include No. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (all manufactured by Mitsubishi Chemical Corporation); Raven700, 5750, 5250, 5000, 3500, 1255 (all manufactured by Columbia); Regal400R, 330R, 660R, Mogu L, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (all manufactured by Cabot); Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, and 4 (all manufactured by Degussa).

  The pigment that can be used for the yellow ink for color is not particularly limited and can be appropriately selected according to the purpose. I. Pigment yellow 1, C.I. I. Pigment yellow 2, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 174, C.I. I. Pigment yellow 180, and the like.

  The pigment that can be used in the magenta ink for color is not particularly limited and may be appropriately selected depending on the intended purpose. I. Pigment red 5, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment red 48 (Ca), C.I. I. Pigment red 48 (Mn), C.I. I. Pigment red 57 (Ca), C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 146, C.I. I. Pigment red 168, C.I. I. Pigment red 176, C.I. I. Pigment red 184, C.I. I. Pigment red 185, C.I. I. Pigment red 202, pigment violet 19, and the like.

  The pigment that can be used for the cyan ink for the color is not particularly limited and may be appropriately selected according to the purpose. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 3, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15:34, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. Pigment blue 60, C.I. I. Pigment blue 63, C.I. I. Pigment blue 66; C.I. I. Bat Blue 4, C.I. I. Bat Blue 60 and the like.

In addition, the pigment contained in each ink used in the present invention may be newly produced for the present invention.
By using Pigment Yellow 74 as the yellow pigment, Pigment Red 122, Pigment Bio Red 19 as the magenta pigment, and Pigment Blue 15: 3 as the cyan pigment, an ink with excellent color tone and light fastness and balanced can be obtained. Can be obtained.
Furthermore, the pigment used in the present invention can be a grafted or encapsulated product coated with a surfactant such as a dispersant or a resin, but the compound of the present invention is used as a dispersant. Is more preferable.
Moreover, you may use together the pigment mentioned above in the range which does not impair an effect.

(Other ingredients)
There is no restriction | limiting in particular as another component used for the composition of the ink for inkjet recording of this invention, It can select suitably as needed. Other components include, for example, dispersants, penetrants, pH adjusters, water-dispersible resins, antiseptic / antifungal agents, chelating reagents, rust inhibitors, antioxidants, UV absorbers, oxygen absorbers, and light stabilizers. Agents, etc.

(Dispersant)
Examples of the dispersant include various surfactants such as an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant, and polymer-type dispersants. These may be used alone or in combination of two or more.

  Examples of the anionic surfactant include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acyl amino acids and salts thereof, N-acyl methyl taurate, polyoxyalkyl ether sulfates. Salt, polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester salt, lauryl alcohol sulfate ester salt, alkylphenol type phosphate ester, naphthalenesulfonate formalin condensate, alkyl type phosphate ester, alkylallylsulfone hydrochloride, diethyl Examples include sulfosuccinate, diethylhexyl sulfosuccinate, and dioctyl sulfosuccinate.

  Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

  Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, imidazoline. Derivatives and the like.

Examples of nonionic surfactants include the following.
Ether-based interfaces such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyallylalkyl alkyl ether Active agent;
Polyoxyethylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate Ester surfactants such as
2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyn-3-ol Examples thereof include acetylene glycol surfactants.

(Penetration agent)
The penetrant preferably contains either a polyol compound having 8 to 11 carbon atoms or a glycol ether compound having 8 to 11 carbon atoms.
The penetrating agent is different from the wetting agent and has a relatively low wetting property than the wetting agent, and thus can be referred to as a “non-wetting agent-based medium”. These non-wetting agent penetrants preferably have a solubility of between 0.2 and 5.0% by weight in water at 25 ° C.
Among these, 2-ethyl-1,3-hexanediol [solubility: 4.2% by weight (25 ° C.)], 2,2,4-trimethyl-1,3-pentanediol [solubility: 2.0% by weight] (25 ° C.)] is particularly preferred.
As other polyol compounds, as aliphatic diols, for example, 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1, 3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene- 1,2-diol and the like can be mentioned.

  Other penetrants that can be used in combination are not particularly limited as long as they can be dissolved in the ink and adjusted to the desired physical properties, and can be appropriately selected according to the purpose. For example, diethylene glycol monophenyl ether, ethylene Glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, alkyl and aryl ethers of polyhydric alcohols such as tetraethylene glycol chlorophenyl ether, lower alcohols such as ethanol, etc. Is mentioned.

  The content of the penetrant in the ink-jet ink is preferably 0.1 to 4.0% by weight. If the content is less than 0.1% by weight, a fast-drying property cannot be obtained and a blurred image may be obtained. If the content exceeds 4.0% by weight, the dispersion stability of the colorant is impaired, and the nozzle May become clogged, the permeability to a recording medium (recording medium) may become higher than necessary, or the image density may be lowered or the image may be broken through.

(PH adjuster)
The pH adjuster is not particularly limited as long as the pH can be adjusted to 8.5 to 11 and preferably 9 to 11 without adversely affecting the ink jet ink to be prepared. For example, alcohol amines, hydroxides of alkali metal elements, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like can be used. If the pH is less than 8.5 or more than 11, the amount of the ink-jet head or ink supply unit that melts out is large, and problems such as ink deterioration, leakage, and ejection failure may occur. When it is less than 8.5, the ink pH may decrease during storage of the ink, and the polymer fine particles may aggregate due to an increase in the particle diameter.
The pH can be measured by, for example, a pH meter HM-30R (manufactured by TOA-DKK).

  Examples of the alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the ammonium hydroxide include ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

(Water dispersible resin)
The water-dispersible resin has excellent film-forming properties (image formability), high water repellency, high water resistance, and high weather resistance, and has high water resistance and high image density (high color development). Useful for.
Specific examples of the water-dispersible resin include condensation-type synthetic resins, addition-type synthetic resins, natural polymer compounds, and the like.
Examples of the condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, poly (meth) acrylic resin, acrylic-silicone resin, and fluorine-based resin. Examples of the addition type synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like. Examples of the natural polymer compound include celluloses, rosins, and natural rubber.
Among these, polyurethane resin fine particles, acrylic-silicone resin fine particles, and fluorine-based resin fine particles are particularly preferable.

The volume average particle diameter (D50) of the water-dispersible resin is related to the viscosity of the dispersion, and for the same composition, the viscosity at the same solid content increases as the particle diameter decreases. The volume average particle diameter (D50) of the water-dispersible resin is preferably 50 nm or more so that the ink does not have an excessively high viscosity. Further, when the particle size is several tens of μm, it becomes larger than the nozzle opening of the ink jet head and cannot be used. If particles having a large particle diameter are present in the ink even though they are smaller than the nozzle opening, the ejection stability is deteriorated. Therefore, the volume average particle diameter (D50) is more preferably 200 nm or less in order not to disturb the ink ejection stability.
Here, the volume average particle diameter (D50) of the water-dispersible resin is measured by a dynamic light scattering method using Microtrac UPA manufactured by Nikkiso Co., Ltd. in an environment of 23 ° C. and 55% RH.

The water-dispersible resin has a function of fixing the water-dispersed colorant on the paper surface, and is preferably formed into a film at room temperature to improve the fixability of the color material. Therefore, it is preferable that the minimum film-forming temperature (MFT) of the water-dispersible resin is 30 ° C. or less.
Further, when the glass transition temperature of the water-dispersible resin is -40 ° C. or lower, the resin film becomes more viscous and the printed matter is tacky. Therefore, the water-dispersible resin has a glass transition temperature of −30 ° C. or higher. It is preferable. The content of the water-dispersible resin in the ink-jet ink is preferably 1 to 15% by weight, more preferably 2 to 7% by weight in terms of solid content.

(Antiseptic and antifungal agent)
Examples of the antiseptic / antifungal agent include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, and the like.

(Chelating reagent)
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.

(Rust inhibitor)
Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

(Antioxidant)
Examples of the antioxidant include phenolic antioxidants (including hindered phenolic antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

(UV absorber)
Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a nickel complex ultraviolet absorber.

(Inkjet ink manufacturing method)
The ink-jet ink of this embodiment is obtained by dispersing or dissolving water, a wetting agent, a colorant, a copolymer in which aggregation and thickening occur with a decrease in pH , and, if necessary, other components in an aqueous medium. Further, it is produced by stirring and mixing as necessary.
In addition, as described above, the copolymer in which aggregation and thickening occur with a decrease in pH is a copolymer of the monomer represented by the formula (1) and the monomer represented by the general formula (2). It is.
The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, and the like. be able to.

There is no restriction | limiting in particular as a physical property of the inkjet ink of this invention, According to the objective, it can select suitably, For example, it is preferable that viscosity, surface tension, etc. are the following ranges.
The viscosity of the inkjet ink at 25 ° C. is preferably 3 mPa · s to 20 mPa · s. By setting the ink viscosity to 3 mPa · s or more, the effect of improving the printing density and the character quality can be obtained. On the other hand, by suppressing the ink viscosity to 20 mPa · s or less, it is possible to ensure the discharge performance.
The viscosity can be measured at 25 ° C. using, for example, a viscometer (RL-550, manufactured by Toki Sangyo Co., Ltd.).
The surface tension of the inkjet ink is preferably 40 mN / m or less at 25 ° C. When the surface tension exceeds 40 mN / m, leveling of the ink on the recording medium is difficult to occur and the drying time may be prolonged.

(ink cartridge)
The ink cartridge of the present invention accommodates the ink for ink jet recording of the present invention in a container, and can also constitute other members appropriately selected as necessary.
The shape, structure, size, and material of the container are not particularly limited and can be appropriately selected according to the purpose. Preferred examples include those having at least an ink bag formed of an aluminum laminate film, a resin film, or the like.

  One embodiment of the ink cartridge of the present invention will be described with reference to FIGS. FIG. 1 is a schematic plan view for explaining an example of the ink cartridge of the present invention. FIG. 2 is a schematic plan view including a case (exterior) of the ink cartridge of FIG.

  As shown in FIG. 1, the ink cartridge 200 is filled into the ink bag 241 from the ink inlet 242 and exhausted, and then the ink inlet 242 is closed by fusion. In use, the needle of the apparatus main body is pierced into the ink discharge port 243 made of a rubber member and supplied to the apparatus. The ink bag 241 is formed of a packaging member such as a non-permeable aluminum laminate film. As shown in FIG. 2, the ink bag 241 is usually housed in a plastic cartridge case 244 and is detachably mounted on various ink jet recording apparatuses.

(Inkjet recording apparatus and inkjet recording method)
The ink jet recording apparatus of the present invention includes at least ink flying means, and further includes other means appropriately selected as necessary, for example, stimulus generation means, control means, and the like.
The inkjet recording method of the present invention includes at least an ink flying process, and further includes other processes appropriately selected as necessary, for example, a stimulus generation process, a control process, and the like.
The ink jet recording method of the present invention can be preferably carried out by the ink jet recording apparatus of the present invention, and the ink flying step can be suitably carried out by the ink flying means. Moreover, the said other process can be suitably performed by the said other means.

The ink flying step is a step of forming an image by applying a stimulus to the ink jet ink of the present invention and causing the ink jet ink to fly.
The ink flying means is means for forming an image by applying a stimulus to the ink-jet ink of the present invention and causing the ink-jet ink to fly. The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.

  The stimulus can be generated, for example, by the stimulus generating means, and the stimulus is not particularly limited and can be appropriately selected according to the purpose, such as heat (temperature), pressure, vibration, light, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable. Examples of the stimulus generating means include a superheater, a pressurizer, a piezoelectric element, a vibration generator, an ultrasonic oscillator, and a light. Specifically, a piezoelectric actuator such as a piezoelectric element such as a piezoelectric element, a thermal actuator that uses a phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, a shape that uses a metal phase change due to a temperature change Memory alloy actuators, electrostatic actuators using electrostatic force, and the like can be mentioned.

  There is no particular limitation on the mode of the ink flying, and it varies depending on the type of the stimulus. For example, when the stimulus is “heat”, the thermal energy corresponding to the recording signal is output to the ink in the recording head. For example, using a thermal head or the like, generating bubbles in the ink by the thermal energy, and ejecting and ejecting the ink as droplets from the nozzle holes of the recording head by the pressure of the bubbles. It is done. Further, when the stimulus is “pressure”, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the recording head, the piezoelectric element bends and the volume of the pressure chamber is increased. And a method of ejecting and ejecting the ink as droplets from the nozzle holes of the recording head.

  The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

Here, one aspect of carrying out the ink jet recording method of the present invention by the ink jet recording apparatus of the present invention will be described with reference to the drawings.
FIG. 3 is a perspective view showing an example of the serial type ink jet recording apparatus of the present invention.
The ink jet recording apparatus shown in FIG. 3 stocks an apparatus main body 101, a paper feed tray 102 for loading paper loaded on the apparatus main body 101, and paper on which an image is recorded (formed) mounted on the apparatus main body 101. A paper discharge tray 103 and an ink cartridge loading unit 104 protruding forward from the front surface 112 and lower than the upper cover 111 are provided at one end of the front surface 112 of the apparatus main body 101. On the upper surface of the ink cartridge loading unit 104, an operation unit 105 such as operation keys and a display is arranged. The ink cartridge loading unit 104 has a front cover 115 that can be opened and closed for attaching and detaching the ink cartridge 200.

  As shown in FIGS. 4 and 5 (partially enlarged sectional view of the ink jet recording apparatus shown in FIG. 3), a guide which is a guide member horizontally mounted on left and right side plates (not shown) is provided in the apparatus main body 101. The carriage 133 is slidably held in the main scanning direction by the rod 131 and the stay 132, and is moved and scanned in the direction of the arrow as shown in FIG. 5 by the main scanning motor.

The carriage 133 is provided with a recording head 134 composed of four ink jet recording heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward.
As the ink jet recording head constituting the recording head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator using phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, a metal phase due to temperature change, etc. A shape memory alloy actuator using a change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used. In addition, the carriage 133 is equipped with a sub tank 135 for each color for supplying ink of each color to the recording head 134. The sub tank 135 is supplied with the ink from the ink cartridge 200 of the present invention loaded in the ink cartridge loading unit 104 via an ink supply tube (not shown) and is replenished.

On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 103, a half-moon roller (feeding) that separates and feeds the paper 142 one by one from the paper stacking unit 141. A separation pad 144 made of a material having a large coefficient of friction is provided facing the paper roller 143) and the paper feed roller 143, and the separation pad 144 is urged toward the paper feed roller 143 side.
As a transport unit for transporting the paper 142 fed from the paper feed unit below the recording head 134, a transport belt 151 for transporting the paper 142 by electrostatic adsorption and a guide 145 from the paper feed unit. The counter roller 152 for transporting the paper 142 fed via the transport belt 151 with the transport belt 151 and the paper 142 fed substantially vertically upward are changed by approximately 90 ° to follow the transport belt 151. For this purpose, a conveyance guide 153 and a tip pressure roller 155 urged toward the conveyance belt 151 by a pressing member 154 are provided.

In addition, a charging roller 156 that is a charging unit for charging the surface of the conveyance belt 151 is provided. The conveyance belt 151 is an endless belt, is stretched between the conveyance roller 157 and the tension roller 158, and can circulate in the belt conveyance direction. The transport belt 151 includes, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), and the surface layer. It has a back layer (medium resistance layer, earth layer) that is made of the same material and has resistance controlled by carbon. On the back side of the conveyance belt 151, a guide member 161 is arranged corresponding to a printing area by the recording head 134.
Note that, as a paper discharge unit for discharging the paper 142 recorded by the recording head 134, a separation claw 171 for separating the paper 142 from the conveyance belt 151, a paper discharge roller 172, and a paper discharge roller 173 are provided. The paper discharge tray 103 is disposed below the paper discharge roller 172.

A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101.
The double-sided paper feeding unit 181 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 152 and the transport belt 151. A manual paper feed unit 182 is provided on the upper surface of the duplex paper feed unit 181.

  In this ink jet recording apparatus, the paper 142 is separated and fed one by one from the paper feed unit, and the paper 142 fed substantially vertically upward is guided by the guide 145 and between the transport belt 151 and the counter roller 152. It is sandwiched and conveyed. Further, the leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure roller 155, and the conveying direction is changed by approximately 90 °. At this time, the conveyance belt 157 is charged by the charging roller 156, and the sheet 142 is conveyed by being electrostatically attracted to the conveyance belt 151. Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133, ink droplets are ejected onto the stopped paper 142 to record one line, and after the paper 142 is conveyed by a predetermined amount, Record the next line.

  Upon receiving a recording end signal or a signal that the trailing edge of the sheet 142 has reached the recording area, the recording operation is terminated and the sheet 142 is discharged onto the discharge tray 103. When the ink remaining amount near end in the sub tank 135 is detected, a required amount of ink is supplied from the ink cartridge 200 to the sub tank 135.

In this ink jet recording apparatus, when the ink in the ink cartridge 201 of the present invention is used up, the casing of the ink cartridge 200 can be disassembled and only the ink bag inside can be replaced. Further, the ink cartridge 200 can supply ink stably even when the ink cartridge 200 is installed vertically and has a front loading configuration. Therefore, the ink cartridge 200 is installed even when the upper portion of the apparatus main body 101 is closed, for example, when stored in a rack, or when an object is placed on the upper surface of the apparatus main body 101. Can be easily exchanged.
In addition, although it demonstrated in the example applied to the serial type (shuttle type) inkjet recording device which a carriage scans, it can apply similarly to the line type inkjet recording device provided with the line type head.

  The ink jet recording apparatus of the present invention can be applied to various types of recording by the ink jet recording method, and is particularly preferably applied to, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. Can do.

(Ink record)
The ink recorded matter recorded by the ink jet recording method of the present invention is the ink recorded matter of the present invention. That is, the ink recorded matter of the present invention has an image recorded with the ink for ink jet recording of the present invention on a recording medium (recording medium).
The recording medium is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plain paper, coated paper for printing, glossy paper, special paper, cloth, film, and OHP sheet. It is done. These may be used individually by 1 type and may use 2 or more types together. Among these, at least one of plain paper and coated paper for printing is preferable. The plain paper is advantageous in that it is inexpensive. The coated paper for printing is advantageous in that it provides a smooth glossy image at a relatively low cost as compared with glossy paper. However, although the drying property is poor and it is generally difficult to use for inkjet, the drying property is improved by the ink of the present invention.
The ink recorded matter of the present invention has high image quality, no bleeding, excellent stability with time, and can be suitably used for various purposes as materials on which various prints or images are recorded.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further, this invention is not limited to these examples. The% used in the examples is based on weight.

<Example>
(Preparation of compound A)
A four-necked flask is equipped with a thermometer, stirrer, and reflux condenser, charged with 500 g of water and 15 g of ammonium persulfate, and heated at 80 to 90 ° C., 100 g of styrene, maleic acid (N, N-dimethylpropylenediamine monoamide) 100 g was slowly added dropwise with stirring. The ratio (%) of styrene and maleic acid (N, N-dimethylpropylenediamine monoamide) is 50:50.
Subsequently, after reacting for 4 hours, the mixture was cooled, neutralized with NaOH, and distilled water was added to adjust the solid content to 20%. Styrene-maleic acid (N, N-dimethylpropylenediamine monoamide) An aqueous solution of a copolymer Na salt (Compound A) was obtained.

(Preparation of compound B)
Compound B was obtained in the same manner as in the preparation of Compound A except that the ratio (% by weight) of styrene and maleic acid (N, N-dimethylpropylenediamine monoamide) in the preparation of Compound A was changed to 67:33.

(Preparation of compound C)
Compound C was obtained in the same manner as in the preparation of Compound A except that the ratio (% by weight) of styrene and maleic acid (N, N-dimethylpropylenediamine monoamide) in the preparation of Compound A was changed to 75:25.

(Preparation of compound D)
Compound D was obtained in the same manner as in the preparation of Compound C, except that maleic acid (N, N-dimethylpropylenediamine monoamide) in the preparation of Compound C was changed to maleic acid (N, N-dibutylpropylenediamine monoamide).

(Preparation of compound E)
Compound E was obtained in the same manner as in the preparation of Compound C except that NaOH in the preparation of Compound C was changed to KOH.

(Preparation of compound F)
Compound F was obtained in the same manner as in the preparation of Compound C, except that NaOH in the preparation of Compound C was changed to triethanolamine.

(Preparation of compound G)
Compound G was obtained in the same manner as in the preparation of Compound D except that NaOH in the preparation of Compound D was changed to triethanolamine.

(Preparation of compound H)
Compound H was obtained in the same manner as in the preparation of Compound B, except that the neutralization rate was changed to 85% by changing the amount of the neutralizing agent in the preparation of Compound B.

<Preparation of pigment dispersion>
(Adjustment Example 1): Pigment dispersion A
After premixing the following carbon black pigment, copolymer and pure water mixture according to the following prescription (1), a disk type bead mill (Shinmaru Enterprises KDL type, media: using zirconia balls having a diameter of 0.1 mm) ) Was circulated and dispersed at a peripheral speed of 10 m / s for 10 minutes to obtain a black pigment dispersion.

Formula (1)
Carbon black pigment NIPEX150 20 parts by weight (Degussa: gas black)
-Aqueous solution of Compound A (solid content: 12.5% by weight) 64 parts by weight-16 parts by weight of pure water

(Adjustment Examples 2 to 10): Pigment dispersions B to H
Pigment dispersions B to H were obtained in the same manner as in Preparation Example 1 except that the aqueous solution of Compound A of Preparation Example 1 was changed to the aqueous solutions of Compounds B to H.

(Adjustment Example 11): Cyan Pigment Dispersion A cyan pigment dispersion was obtained in the same manner as in Adjustment Example 1, except that the carbon black pigment of Adjustment Example 1 was changed to Pigment Blue 15: 3.

(Adjustment Example 12): Magenta Pigment Dispersion A magenta pigment dispersion was obtained in the same manner as in Adjustment Example 1 except that the carbon black pigment of Adjustment Example 1 was changed to Pigment Red 122.

(Adjustment Example 13): Yellow Pigment Dispersion Liquid A yellow pigment dispersion liquid was obtained in the same manner as in Adjustment Example 1 except that the carbon black pigment of Adjustment Example 1 was changed to Pigment Yellow 74.

<Comparative example>
(Preparation of Compound I)
Similar to the preparation of Compound D, except that styrene and maleic acid (N, N-dimethylpropylenediamine monoamide) in the preparation of Compound A were changed to styrene and acrylic acid, and the weight ratio of styrene and acrylic acid was set to 43:57. Compound I was obtained.

(Preparation of compound J)
Similar to the preparation of compound D, except that styrene and maleic acid (N, N-dimethylpropylenediamine monoamide) in the preparation of compound C were changed to styrene and maleic acid, and the weight ratio of styrene and maleic acid was 43:57. Compound I was obtained.

<Preparation of pigment dispersion>
(Comparative Adjustment Example 1): Pigment dispersion liquid I
A pigment dispersion I was obtained in the same manner as in Preparation Example 1 except that the aqueous solution of Compound A in Preparation Example 1 was changed to an aqueous solution of Compound I.

(Comparative Adjustment Example 2): Pigment dispersion liquid J
A pigment dispersion J was obtained in the same manner as in Preparation Example 1 except that the aqueous solution of Compound A in Preparation Example 1 was changed to an aqueous solution of Compound J.

(Comparative Adjustment Example 3): Pigment dispersion K
A pigment dispersion K was obtained in the same manner as in Preparation Example 1 except that the aqueous solution of Compound A of Preparation Example 1 was changed to an aqueous solution of naphthalenesulfonic acid formalin condensate.

[Examples 1 to 11 and Comparative Examples 1 to 3]
<Inkjet ink manufacturing method>
The materials having the following formulation were mixed and stirred for 30 minutes to prepare ink.

Example 1
-Pigment dispersion A in Preparation Example 1 (pigment concentration 20%) 40.0 parts by weight-5.5 parts by weight of glycerin-16.5 parts by weight of 1,3-butanediol-2-ethyl-1,3-hexanediol 2.0 parts by weight · Fluorosurfactant (solid content 40%) 2.5 parts by weight (DuPont: Zonyl FS-300)
Fluoroethylene / vinyl ether alternating copolymer (solid content 50%) 6.0 parts by weight (Asahi Glass Co., Ltd .: Lumiflon FE4300, average particle size 150 nm,
MFT 30 ℃ or less)
-1.5 parts by weight of 2-amino-2-ethyl-1,3-propanediol aqueous solution (solid content 40%)
・ Pure water 26.0 parts by weight

(Examples 2 to 8)
Inks of Examples 2 to 8 were obtained in the same manner as in Example 1, except that the pigment dispersion A was changed to the pigment dispersions B to H.

Example 9
In Example 3, the ink of Example 9 was similarly used except that the pigment dispersion A was changed to a cyan pigment dispersion, the cyan pigment dispersion was 33.0 parts by weight, and pure water was 33.0 parts by weight. Obtained.

(Example 10)
In Example 3, the ink of Example 10 was similarly used except that the pigment dispersion A was changed to the cyan pigment dispersion, the magenta pigment dispersion was 33.0 parts by weight, and the pure water was 33.0 parts by weight. Obtained.

(Example 11)
In Example 3, the ink of Example 11 was similarly used except that the pigment dispersion A was changed to the cyan pigment dispersion, the yellow pigment dispersion was changed to 33.0 parts by weight, and the pure water was changed to 33.0 parts by weight. Obtained.

(Comparative Examples 1-3)
Inks of Comparative Examples 1 to 3 were obtained in the same manner except that the pigment dispersion A of the ink A of Example 1 was changed to the pigment dispersions I to K.

  Next, the inkjet inks of Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated by the following evaluation method. The results are shown in Table 1 below.

<Image density>
In a 23 ° C. and 50% RH environment, an ink jet printer (IPSiO GX5000 manufactured by Ricoh) was filled with ink prepared, and a chart with a 64 point character “■” created by Microsoft Word 2000 (manufactured by Microsoft Corporation) was written on MyPaper (stock) (Ricoh Co., Ltd.), the “■” portion of the printed surface was measured with X-Rite 938, and judged according to the following evaluation criteria.
The printing mode used was a driver attached to the printer, in which the "plain paper-standard fast" mode was changed to "no color correction" from the user setting for plain paper.

〔Evaluation criteria〕
A: Black: 1.2 or more, Magenta: 0.95 or more,
Cyan: 0.95 or more, yellow: 0.8 or more,
○: Black: 1.15 or more, Magenta: 0.9 or more,
Cyan: 0.9 or more, yellow: 0.75 or more,
Δ: Black: 1.1 or more, Magenta: 0.85 or more,
Cyan: 0.85 or more, yellow: 0.7 or more,
X: Black: less than 1.1, magenta: less than 0.85,
Cyan: less than 0.85, yellow: less than 0.7,

<Ink storage stability>
Each ink was filled in an ink cartridge and stored at 60 ° C. for 2 weeks, and the change in viscosity after storage relative to the viscosity before storage was evaluated according to the following criteria.

[Evaluation criteria]
◎: Change in viscosity is less than ± 5% ○: Change in viscosity is ± 5% or more and less than ± 10% Δ: Change in viscosity is ± 10% or more and less than ± 30% ×: Change in viscosity is 30% or more

<Ink ejection stability>
Regarding ejection stability, after printing a printed matter, the printer was left in a 50 ° C. environment for one month with the printer head capped. Whether or not the discharge state of the printer after being left is restored to the initial discharge state was evaluated according to the following evaluation criteria by the following number of cleaning operations.

○: Printing was possible without cleaning.
Δ: Recovered by 1 to 5 operations.
X: No recovery was observed even after 6 or more operations.

  In all of the above three items, ◎ and ○ are acceptable and Δ and × are unacceptable.

(Content of Example)
Examples 1 to 3 were obtained by changing the ratio of styrene and maleic acid (N, N-dimethylpropylenediamine monoamide) of the present invention, using Na as the salt, and using a carbon black pigment.
In Example 4, the alkyl group of the maleic acid amide compound was changed to butyl.
In Examples 5 to 7, salts were changed to K or triethanolamine.
In Example 8, the neutralization rate of Example 2 was changed from 100% to 85%.
Examples 9, 10, and 11 are those using a cyan pigment dispersion, a magenta pigment dispersion, and a yellow pigment dispersion, respectively.

From the above evaluation results, all the images of the ink of the present invention containing, as an ink composition, a copolymer of at least the monomer represented by the formula (1) and the monomer represented by the general formula (2). Concentration, ink storage stability, and ink ejection stability are excellent, and characteristics that cause problems in practical use are not observed.
For example, it can be seen from the comparison between Examples 1 to 8 and Comparative Examples 1 to 3 that the ink of the present invention has a high image density and storage stability and ejection stability are equivalent or higher.
Moreover, it turns out from the comparison with Example 3 and 4 and the comparison with Example 6 and 7 that the methyl group is excellent in storage stability as alkyl.
From Examples 5 to 7, it can be seen that the same effect is obtained even if the type of salt is changed.
Furthermore, from Examples 9 to 11, it can be seen that even if the copolymer of the present invention is used as a color pigment, the same effect as that of carbon black can be obtained.
In the ink of the present invention, it can be seen that, due to the effect of aggregation and thickening due to water insolubilization due to pH reduction, the image density is clearly excellent for each color ink, and the ink storage stability and ink ejection stability are equivalent or better.

  That is, the present invention has good ink storage stability, good drying properties, high image density on plain paper and coated paper for printing, and good ink ejection stability from the recording head. In addition, since there is no ink sticking around the nozzle, it can be applied to various recordings by the ink jet recording method. The ink recorded matter of the present invention has high image quality, no bleeding, excellent stability over time, and can be suitably used for various purposes as materials on which various prints or images are recorded. As the recording apparatus using the ink jet recording method, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like can be applied.

101 apparatus main body 102 paper feed tray 103 paper discharge tray 104 ink cartridge loading unit 105 operation unit 111 upper cover 112 front surface 115 front cover 131 guide rod 132 stay 133 carriage 134 recording head 135 sub tank 141 paper placement unit 142 paper 143 paper supply roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Pressing member 155 Tip pressure roller 156 Charging roller 157 Conveying roller 158 Densation roller 161 Guide member 171 Separating claw 172 Discharging roller 173 Discharging roller 181 Double-sided feeding Paper unit 182 Manual paper feed unit 200 Ink cartridge 241 Ink bag 242 Ink inlet 243 Ink outlet 244 Cartridge exterior

JP-T-2006-503313 JP 2003-202708 A

Claims (11)

An ink for ink jet recording which contains water, a wetting agent, a colorant, and a copolymer, and is ejected onto plain paper,
The pH of the inkjet recording ink is 9 to 11,
An ink for ink jet recording, wherein the copolymer comprises a copolymer having at least a structural unit represented by the following formula (1) and a structural unit represented by the following general formula (2).

[In the general formula (2), R represents an alkyl group having 1 to 4 carbon atoms, M ⁺ represents at least half or all of them are alkali metal ions and organic amine ions, and the rest represent protons. ] The ink for inkjet recording according to claim 1, wherein the structural unit represented by the general formula (2) is a structural unit represented by the following general formula (3).

[In the general formula (3), M ⁺ is a half or more or all of them are alkali metal ions and organic amine ions, and the rest represent protons. ]   The ink for inkjet recording according to claim 1 or 2, wherein 0.005 to 5 parts by weight of the copolymer is contained with respect to 1 part by weight of the colorant.   The inkjet according to any one of claims 1 to 3, wherein 20 to 60% by weight of the water, 10 to 50% by weight of the wetting agent, and 0.1 to 20% by weight of the colorant are contained. Recording ink.   The ink for inkjet recording according to any one of claims 1 to 4, wherein the plain paper has a pH of 6.5 to 7.5. The ink for ink jet recording according to any one of claims 1 to 5, wherein the ink for ink jet recording has a viscosity change rate calculated by the following measuring method of 30% or more.
Measuring method: After adjusting the liquid temperature of the ink for ink jet recording to 25 ° C. and measuring the initial viscosity, the viscosity when the HCL aqueous solution (20 wt%) is dropped to pH 8.5 is measured, and the following formula is used. Viscosity change rate is calculated.
Formula: Viscosity change rate (%) = [(viscosity after adjustment of viscosity−initial viscosity) / initial viscosity] × 100   The weight ratio of the structural unit represented by the formula (1) and the structural unit represented by the general formula (2) in the copolymer is 40:60 to 80:20. Item 7. The ink for inkjet recording according to any one of Items 1 to 6.   An ink cartridge comprising the ink for ink jet recording according to claim 1 contained in a container.   An ink flying step of recording an image on a recording medium by applying a stimulus to the ink jet recording ink according to any one of claims 1 to 7 via an ink flying means and causing the ink jet recording ink to fly from a recording head. An ink jet recording method comprising:   8. An ink jet recording apparatus comprising ink jetting means for recording an image on a recording medium by causing the ink jet recording ink according to claim 1 to fly from a recording head. An ink recorded matter comprising an image recorded with the ink for ink jet recording according to any one of claims 1 to 7 on a recording medium.

Images