JPWO2016132858A1 - Aqueous pigment ink composition for inkjet, image forming method, image formed product, ink set, and inkjet printer - Google Patents

Abstract

An aqueous pigment ink composition for inkjet, comprising a pigment, a dispersant, an emulsion resin, water and an aqueous organic solvent, wherein the average particle size of the emulsion resin is smaller than the average particle size of the pigment and not more than 70 nm; The content of the emulsion resin is not less than the content of the pigment and not less than 2% by mass and not more than 10% by mass with respect to the entire aqueous pigment ink composition for inkjet. The aqueous organic solvent is 3-methoxy A water-based pigment ink composition for ink-jet, comprising -3-methylbutanol and a pyrrolidone-based solvent in a range of 2% by mass or more and 18% by mass or less, respectively, with respect to the whole water-based ink pigment ink composition.

Description

  The present invention relates to an aqueous pigment ink composition for inkjet, and more specifically, excellent storage stability, ejection stability, etc., and high quality images on a non-ink-absorbing substrate or a low-ink-absorbing substrate even under low temperature drying. It is related with the aqueous pigment ink composition for inkjet which can form.

  Conventionally, even in industrial applications, the field of application of ink jet technology has expanded as a digital printout system that is characteristic of ink jet technology. Particularly in recent years, development of water-based pigment ink has been promoted from the viewpoint of environment, safety, and the like while having one aspect as an alternative to solvent-based pigment ink.

  In addition to water-based pigment ink compositions for inkjet forming images on highly ink-absorbing substrates such as paper, non-ink-absorbing substrates such as metal, glass and polyethylene terephthalate, or low inks such as vinyl chloride Development of an aqueous pigment ink composition for inkjet that can form an image on an absorbent substrate is also underway.

  Among these, many proposals have been made for ink-jet ink compositions using an emulsion resin as a binder resin because the ink film on the printing substrate is excellent in physical properties such as water resistance and chemical resistance.

For example, Patent Document 1 discloses a water-based ink and a water-resistant ink that can be directly printed on a low-ink-absorbing substrate such as a metal by combining a specific emulsion resin and an organic solvent having a specific chemical structure. An aqueous pigment ink composition with excellent friction is described.
Further, Patent Document 2 can provide an aqueous pigment ink composition excellent in friction resistance, storage stability, and ejection stability by using a water-soluble solvent that does not inhibit the hydration stability of emulsion particles and has moisture retention. Have been described.

Patent Document 3 describes an aqueous pigment ink composition that achieves high print production performance while maintaining ejection stability by a combination of a specific emulsion and an organic solvent having a chemical structure.
Patent Document 4 discloses a coating film that is excellent in ejection stability by low-temperature drying by limiting the boiling point range of the aqueous solvent used from the balance between prevention of clogging of the nozzles of the print head and drying property of the ink film. An aqueous pigment ink composition with excellent properties is described.

  However, the demand for water-based pigment ink compositions for inkjet has been increasing in recent years, and such known technologies have room for improvement in performance such as storage stability, ejection stability, and low-temperature drying properties. . In particular, the aqueous pigment ink composition for inkjet used for forming an image on a non-ink-absorbing substrate or a low ink-absorbing substrate is still insufficient and further improvement has been demanded.

JP 2010-111741 A JP 2012-251049 A JP 2012-070443 A JP 2014-177516 A

  The present invention has been made in view of the above-mentioned background art, and its problem is to solve the above-mentioned problems, and is excellent in storage stability, ejection stability, cleaning characteristics, low-temperature drying properties, etc., and high-quality images. It is an object to provide an aqueous pigment ink composition for ink jet.

  As a result of intensive studies to solve the above problems, the present inventor has found that an average of the emulsion resin in an aqueous pigment ink composition for inkjet including at least a pigment, a dispersant, an emulsion resin, water, and an aqueous organic solvent. By defining the particle size, further defining the content of the emulsion resin, and containing a specific amount of at least 3-methoxy-3-methylbutanol and a pyrrolidone-based solvent as the aqueous organic solvent, The present invention has been completed by finding that the above-mentioned problems can be solved by solving the problems.

That is, the present invention is an aqueous pigment ink composition for inkjet comprising a pigment, a dispersant, an emulsion resin, water and an aqueous organic solvent,
The average particle size of the emulsion resin is smaller than the average particle size of the pigment and 70 nm or less;
The content of the emulsion resin is not less than the content of the pigment and not less than 2% by mass and not more than 10% by mass with respect to the entire aqueous pigment ink composition for inkjet.
The aqueous organic solvent contains 3-methoxy-3-methylbutanol (3-methyl-3-methoxy-1-butanol) and a pyrrolidone solvent in an amount of 2% by mass or more based on the total aqueous pigment ink composition for inkjet. It is intended to provide an aqueous pigment ink composition for inkjet which is contained in the range of 18% by mass or less.

  The present invention also provides an ejection step of ejecting the above-described aqueous pigment ink composition for inkjet from an inkjet head and landing the ejected liquid droplets on a substrate, and an aqueous pigment ink composition for ink jet landed on the substrate. The image forming method characterized by including the heating process of heating at 40 degreeC or more and 80 degrees C or less.

  In addition, the present invention provides an image formed product that is formed on a substrate using the above-described aqueous pigment ink composition for inkjet.

According to the present invention, the above-mentioned problems and the above-mentioned problems are solved, and there is no viscosity over time, no separation / sedimentation / aggregation of each component, etc., excellent dispersion stability, and excellent storage stability.
In addition, the ink has excellent discharge stability such as ink re-dissolution, continuous discharge, and head clogging.

In particular, even under low temperature drying, it is resistant to non-ink-absorbing substrates (non-ink-absorbing recording media) or low-ink-absorbing substrates (low ink-absorbing recording media) due to its quick drying. It is possible to provide an aqueous pigment composition for inkjet that can realize a high-quality printed image having excellent rubbing properties.
In other words, an image with good coating properties (rubbing resistance, water resistance, flexibility, stretchability, etc.) is achieved even when dried at low temperatures, even on non-ink-absorbing substrates or low-ink absorbing substrates. An aqueous pigment composition for inkjet that can be provided can be provided.

  The present invention includes, as an aqueous organic solvent, at least 3-methoxy-3-methylbutanol and a pyrrolidone-based solvent in a specific amount and a specific amount related to the average particle size and content of the emulsion resin. In combination with the above requirements, the “water-based organic solvent” and “mean particle-size” synergistically act to provide an aqueous pigment composition for inkjet that is excellent in the above performance.

The aqueous pigment composition for inkjet according to the present invention contains water and an aqueous organic solvent as a solvent (dispersion medium). In particular, as the aqueous organic solvent, at least 3-methoxy-3-methylbutanol and a pyrrolidone-based solvent are used in specific amounts. Contains.
By containing 3-methoxy-3-methylbutanol, the resolubility of the emulsion resin is improved, and as a result, the emulsion resin adhering to the nozzle is easily redissolved during cleaning for sucking ink (improves cleaning characteristics). In addition, the ejection stability is improved when ink is ejected.

Further, by containing a specific amount of 3-methoxy-3-methylbutanol, the drying speed of the ink after image formation is remarkably improved, and the low temperature drying property is improved. As a result, low image quality such as image blur due to undried is obtained. (Even with excellent abrasion resistance), drying is fast even when ejected onto non-ink-absorbing substrates such as metal, glass, and polyethylene terephthalate, and low-ink absorbing substrates such as vinyl chloride. Low temperature drying property is good, and high quality images can be realized.
Since 3-methoxy-3-methylbutanol easily evaporates specifically with water (easily azeotropes), 3-methoxy-3-methylbutanol and water tend to disappear from the substrate almost simultaneously. Even on the substrate, the drying property and abrasion resistance are improved.

In order to achieve low-temperature drying on a low-absorbing substrate or a non-ink-absorbing substrate, the ink droplets that land on the substrate quickly evaporate volatile components, contrary to ejection stability. It is important to prevent dot fusion with droplets that land with a time difference and to form a high-quality image.
For this reason, since 3-methoxy-3-methylbutanol has the property of evaporating at a constant rate with water at a relatively low temperature, the aqueous pigment ink composition for inkjet according to the present invention has a low external energy supply. Thus, it is possible to form a good ink film on a low-absorbing substrate or a non-ink-absorbing substrate.

  Furthermore, since it contains a specific content of “pyrrolidone-based solvent such as 2-pyrrolidone”, it is possible to improve both the cleaning characteristics and ejection stability, and the low-temperature drying property and high drying speed described above. Even when ejected onto an ink-absorbing substrate or a low-ink-absorbing substrate, a high-quality image can be obtained.

  In order for the ejection stability to be good, it is premised that the storage stability of the aqueous pigment ink composition for inkjet is good, and further, the emulsion resin particles are formed into a dry film at the nozzle part of the printer head. In order to prevent this, it is necessary for the ink to have good redispersion and resolvability. In order to maintain the re-dispersion and re-dissolvability of the ink even if most of the water in the ink evaporates, each of the 3-methoxy-3-methylbutanol and / or pyrrolidone solvents is synergistic. It is extremely effective.

Furthermore, after image formation by the inclusion of “another aqueous organic solvent (for example, having a high boiling point of 200 ° C. or higher) blended to ensure moisture retention” (hereinafter simply referred to as “other solvent”). This can prevent a decrease in the drying speed of the ink.
In general, when “other solvents” such as 1,2-hexanediol reduce the evaporation rate of water as if it contains too much water to ensure moisture retention, 3-methoxy-3-methylbutanol is water and Easily azeotrope, water evaporates and 3-methoxy-3-methylbutanol also evaporates (even if high-boiling “other solvents” such as 1,2-hexanediol are contained) after image formation The drying speed of the ink on the substrate (for example, the time until substantially all the components of the solvent are evaporated) can be kept good.
As a result of the above effects, and the content of “other solvents” having a high boiling point such as 1,2-hexanediol may be reduced, on a non-ink-absorbing substrate or a low-ink-absorbing substrate. Even when an image is formed by discharging, a high-quality image can be realized with excellent drying and abrasion resistance.

Further, since the average particle diameter of the emulsion resin is smaller than the average particle diameter of the pigment and 70 nm or less, the emulsion resin having a smaller average particle diameter is uniformly surrounded around the dispersant present around the pigment, Since it behaves like one particle as a whole, the storage stability of the ink is good.
For example, when the surface of the “pigment having a dispersant on the surface” is on the “+” side, the emulsion resin on the “−” surface having a small average particle diameter surrounds it uniformly and uniformly, and the surface as a whole Since the particles become “-” particles, the storage stability of the ink over time, the dispersion stability in the container and in the nozzles, and the like are improved due to repulsion and steric hindrance due to the “−” charge.

  In other words, the aqueous pigment ink composition for inkjet according to the present invention includes two types of particles: emulsion resin particles and pigment particles. Rather than having these two types of particles dispersed separately, the charge of the dispersant covering the surface of the pigment is opposite to the charge of the emulsion resin particles, resulting in the surroundings of the pigment Can be stably dispersed in a solvent in an arrangement in which fine emulsion resin particles having an average particle diameter of 70 nm or less are surrounded, whereby the long-term storage stability of the ink of the present invention can be obtained.

  An aqueous organic solvent containing a specific amount of 3-methoxy-3-methylbutanol and a pyrrolidone solvent (particularly 3-methoxy-3-methylbutanol) has a structure of the above “particle” during storage of ink or in the vicinity of a nozzle. In order not to break, ink storage stability and ejection stability are maintained well. That is, the requirement of the specific emulsion resin of the present invention and the requirement of the specific aqueous organic solvent of the present invention have the above synergistic effect.

It is a block diagram which shows the inkjet printer which discharges the aqueous pigment ink composition for inkjets of this invention.

  Hereinafter, the present invention will be described, but the present invention is not limited to the following specific embodiments, and can be arbitrarily modified within the scope of the technical idea.

The aqueous pigment ink composition for inkjet according to the present invention is an aqueous pigment ink composition for inkjet including a pigment, a dispersant, an emulsion resin, water and an aqueous organic solvent,
The average particle size of the emulsion resin is smaller than the average particle size of the pigment and 70 nm or less;
The content of the emulsion resin is not less than the content of the pigment and not less than 2% by mass and not more than 10% by mass with respect to the entire aqueous pigment ink composition for inkjet.
The aqueous organic solvent contains 3-methoxy-3-methylbutanol and a pyrrolidone solvent in a range of 2% by mass or more and 18% by mass or less, respectively, with respect to the entire aqueous pigment ink composition for inkjet. To do.

In the present invention, the “water-based pigment ink composition for inkjet” may be simply abbreviated as “ink”.
In addition, the “water and aqueous organic solvent” contained in the aqueous pigment ink composition for inkjet according to the present invention may be simply abbreviated as “solvent”. Although there are pigments, emulsion resins, and the like that are not dissolved but dispersed, the “water and aqueous organic solvent” contained in the ink is simply abbreviated as “solvent”.

  The ink of the present invention contains at least a pigment, a dispersant, an emulsion resin, water, and an aqueous organic solvent.

(Pigment)
The kind of pigment used in the present invention is not particularly limited, and known inorganic pigments and organic pigments can be used. Also, the color is not limited, and pigments of other colors can be used in addition to the three primary colors of cyan, magenta or yellow; black; A pigment may be used individually by the same system color and / or between different system colors, and may use 2 or more types together.

  Examples of the inorganic pigment include, but are not limited to, oxides such as titanium oxide, iron oxide, zinc oxide, aluminum oxide, chromium oxide, and silicon oxide; sulfides such as iron sulfide and cobalt sulfide; calcium carbonate and barium sulfate. Metal hydroxides such as aluminum hydroxide; metals; cobalt blue, ultramarine, mica, cobalt green, manganese violet, bitumen, clay and the like.

  Examples of the organic pigment include, but are not limited to, azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, and aniline black. Among these, azo pigments and polycyclic pigments are preferable for process colors or intermediate colors.

Among these, the azo pigment is not limited, and examples thereof include insoluble azo pigments, condensed azo pigments, and chelate azo pigments.
Examples of the polycyclic pigment include, but are not limited to, quinacridone pigment, phthalocyanine pigment, perylene pigment, anthraquinone pigment, dioxazine pigment, isoindoline pigment, indigo pigment, thioindigo pigment, benzimidazolone pigment, quinophthalone pigment, diketo Examples include pyrrolopyrrole pigments.

When such a pigment is indicated by a color index number,
Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 98, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 154, 155, 168, 180, 181, 185, 213;
Pigment red 48, 53, 57, 97, 112, 122, 123, 168, 176, 177, 184, 188, 202, 206, 209, 242, 254, 255;
Pigment Violet 19, 23, 29, 30, 37, Pigment Blue 15: 1, 15: 3, 15: 4, 15: 6, 60, Pigment Orange 36, 43, 51, 55, 59, 61, 71, 74;
Pigment Green 7, 36, Pigment Black 7;
Etc. These may be used alone or in combination of two or more.

The black color pigment is not limited, but carbon black is used. As the carbon black, various types such as neutral, acidic, and basic can be used.
Specifically, for example, “Legal” and “Monarch” manufactured by Cabot Corporation; “Raven” manufactured by Columbia Co., Ltd .; “Blintex” and “Special Black” manufactured by Degussa Huls Co., Ltd .; Mitsubishi Chemical Corporation “HCF”, “MCF”, “RCF”, “RFF”, “SCF”, and the like manufactured by the same company are included. These may be used alone or in combination of two or more.

The average particle size of the pigment is not particularly limited as long as it is larger than the average particle size of the emulsion resin described later, but is preferably 20 nm to 500 nm, more preferably 40 nm to 300 nm, and particularly preferably 70 nm to 150 nm.
When the lower limit of the average particle size is not less than the above, aggregation of the pigment is suppressed; there is an effect that the average particle size of the emulsion resin is easily made smaller than the average particle size of the pigment for stable dispersion of the pigment. Further, when used as an aqueous pigment ink composition for inkjet, the optical density value of the ink film can be easily increased.
On the other hand, when the upper limit of the average particle diameter is not more than the above, there are effects such as improved dispersion stability of the pigment and improved color tone and brightness. Further, when used as an aqueous pigment ink composition for inkjet, the ejection stability is improved.

In the present application, the “average particle diameter of the pigment” is measured by a method capable of directly comparing the magnitude relationship with the “average particle diameter of the emulsion resin” described later.
In the present invention, the average particle diameter of the pigment means a numerical value of the average particle diameter (D50) of the pigment particles in the filtrate obtained after filtering the pigment dispersion (mill base) with a 1 μm filter. Specifically, it is measured by a dynamic light scattering method according to a conventional method, and is, for example, an average particle diameter measured by “Zetersizer Nano S” of Spectris Co., Ltd.

Although content with respect to the whole ink of a pigment does not have limitation in particular, 0.5-8 mass% is preferable, 2-5 mass% is more preferable, 3-4 mass% is especially preferable.
If the pigment content is too low, the density of the printed matter may be light.On the other hand, if the pigment content is too high, it will be difficult to adjust the viscosity, the optical density value of the ink film will be saturated, and the pigment will be wasted. There may be cases.

(Dispersant)
In the present invention, the “dispersant” is used to disperse the pigment. When dispersing a pigment in an aqueous organic solvent, use a polymer dispersant that disperses a self-dispersing pigment with a functional group added to the pigment itself, or disperses the pigment as an encapsulated pigment covered with a resin. Any method can be used in the present invention.

Among these, self-dispersing pigments are less likely to cause dispersion instability, but cost is high, and fixing properties to a substrate may be poor unless a binder or the like is used during use.
In addition, the encapsulated pigment can have the same surface structure regardless of the pigment type, but the amount of resin used is very large, and a technique for dispersing the encapsulated pigment itself in an aqueous organic solvent is required.

  In contrast, in a system using a polymer dispersant, it is possible to introduce a new segment to satisfy "requests other than dispersion performance" such as fixability to a substrate, and the resin amount can be adjusted to the minimum necessary. A method (system) using a polymer dispersant is preferable from the viewpoints of being available and available in many types and having versatility.

The polymer dispersant is not limited, and known ones can be used, and those obtained by known materials and methods can be used.
Moreover, a commercial item can also be used, and as a commercial item, for example,
DISPERBYK-180, 184, 185, 187, 190, 191, 193, 194N, 198, 199, 2010, 2012, 2012, 2091, 2096, BYKJET-9151, BYKJET-9170 (above trade name, manufactured by Big Chemie Co., Ltd.) BYKJET is a registered trademark);
Efka PX-4550, 4560, 4585, 4701 (above trade names, manufactured by Wilber Ellis Co., Ltd.);
DA-703-50 (trade name, manufactured by Enomoto Kasei Co., Ltd.);
Aron A-6330 (trade name, manufactured by Toagosei Co., Ltd.);
TEGO Dispers 750W, 755W (trade names, manufactured by Evonik Tego Chemie, TEGO is a registered trademark);
SOLPERSE-41000, 43000, 44000, 46000, 47000 (above trade name, manufactured by Lubrizol Corporation, SOLPERSE is a registered trademark);
Etc.
These may be used individually by 1 type and may use 2 or more types together.

  The content of the dispersant with respect to the entire ink is not particularly limited, but is preferably 0.2 to 8% by mass, more preferably 0.5 to 4% by mass, and particularly preferably 0.8 to 2.5% by mass. If the content of the dispersant is too small, the dispersibility of the pigment, the storage stability of the ink, the re-dissolvability, the ejection stability, etc. may deteriorate. On the other hand, if the content of the dispersant is too large, the ink There are cases where the water resistance, abrasion resistance, and drying properties of the film are inferior or the dispersant is wasted.

(Dispersing aid)
In order to disperse a pigment having a hydrophobic surface in an aqueous organic solvent and obtain sufficient dispersion stability, a polymer dispersant is preferable as described above. However, it may be difficult to obtain sufficient dispersion stability with the polymer dispersant alone. Better dispersion stability can be achieved by using a pigment derivative (synergist) with a hydrophilic group introduced in the pigment and the above polymer dispersant. May be obtained, and in that case, a synergist is preferably used.

As a combination of such synergists,
Solsperse-5000, 12000, 22000 (above trade name, manufactured by Lubrizol Corporation);
Synergist Yellow-8020, 8404, 9043, 4827 (above trade name, manufactured by Dispersion Materials Laboratory Co., Ltd.);
Synergist Red-33953, 4327, 4474, 4858, 4966, 5507, 5525, 5909, 6006, 6547 (above trade name, manufactured by Dispersion Materials Laboratory Co., Ltd.);
Synergist Blue-6831, 7215, 7438, 7854, 0785, 0785A (above trade name, manufactured by Dispersion Materials Laboratory Co., Ltd.);
Synergist Violet-6965, 7349, 7572, 7988 (above trade name, manufactured by Dispersion Materials Laboratory Co., Ltd.);
Etc.
These may be used individually by 1 type and may use 2 or more types together.

(Emulsion resin)
The aqueous pigment ink composition for inkjet according to the present invention contains an emulsion resin as an essential component. In the present invention, the “emulsion resin” refers to a resin that is a solid component in the “emulsion as a dispersion”. “Emulsion resin content” also means the content of “resin (solid content)” (converted) in the emulsion.

The type of the emulsion resin is not particularly limited, and specifically, for example, (meth) acrylic type, styrene / (meth) acrylic type, vinyl acetate type, vinyl chloride type, olefin type, polyamide type, urethane type And the like.
Among these, a more preferable emulsion resin for the ink of the present invention is a urethane-based, (meth) acrylic-based or vinyl chloride-based emulsion resin from the viewpoint of excellent flexibility and stretchability of the printed film, and is particularly preferable. The emulsion resin is a vinyl chloride emulsion resin because it is particularly excellent in the flexibility and stretchability of the printed film.

Some emulsion resins are commercially available in the “emulsion” state, and others can be suitably used in the present invention.
Specific examples of commercially available “emulsions containing an emulsion resin” that exhibit good storage stability and excellent stretchability include, for example, VINYBRAN 700,701,711,985 (trade name, Nissin Chemical Co., Ltd.). Manufactured by Kogyo Co., Ltd., Vinyblan is a registered trademark); Acrit WAN-6000 (trade name, manufactured by Taisei Fine Chemical Co., Ltd., Acrit is a registered trademark), and the like.

  The average particle size of the emulsion resin used in the ink of the present invention is not particularly limited as long as it is 70 nm or less and smaller than the average particle size of the pigment described above, but is preferably 60 nm or less, more preferably 10 nm or more and 50 nm or less. 20 nm or more and 40 nm or less is particularly preferable.

  In the present invention, the “average particle diameter of the emulsion resin” is measured by a dynamic light scattering method using a dense particle analyzer FPAR-1000 (FPAR is a registered trademark) manufactured by Otsuka Electronics Co., Ltd. Is defined as

  When the lower limit of the average particle diameter is not less than the above, there are effects such that aggregation of emulsion resin particles is suppressed and viscosity stability is easily obtained. Moreover, when preparing the aqueous pigment ink composition for inkjet, it becomes a property which is not so much influenced by the blending order of each component.

  On the other hand, when the upper limit of the average particle diameter is not more than the above, it becomes easier to set smaller than the average particle diameter of the pigment, and the pigment can be more stably dispersed for the reasons described above; the dispersibility stability of the pigment is good. It has excellent effects such as easy to obtain the uniformity of the ink film and high gloss.

In order to improve the storage stability of the pigment in the ink, the average particle diameter of the emulsion resin is not more than the above upper limit in order to easily form an arrangement in which the periphery of the pigment particles is surrounded by particles of the emulsion resin having a surface charge. This is advantageous because there is no steric hindrance in arrangement and repulsive force due to charges of the same polarity works. The measurement result of the zeta potential (ζ potential) between the pigment particles in the ink also supports the existence of an embodiment in which the emulsion resin particles surround the pigment particles.
If the upper limit of the average particle diameter is not more than the above, the emulsion resin having a smaller average particle diameter is uniformly surrounded around the dispersant present around the pigment for the above reasons, and as a whole, like one particle. Behavior and ink storage stability are improved.

Although not limited, when an emulsion resin having a smaller average particle diameter is uniformly surrounded around the pigment, if the pigment particles and the emulsion resin particles are present alone, two zeta potentials (ζ potentials) are generated. As a result, a single zeta potential ([zeta] potential) is integrated to show one zeta potential ([zeta] potential). Therefore, a form showing one zeta potential ([zeta] potential) is preferable in the present invention.
In addition, when the “pigment in which the dispersant is present on the surface” is, for example, the “+” surface, it is uniformly surrounded by the emulsion resin on the “−” surface, and it becomes easy to form particles on the “−” surface as a whole. Due to the repulsion and steric hindrance, the ink storage stability, the dispersion stability in the nozzle, and the like are improved.

In order to exhibit the effect, the average particle diameter of the emulsion resin is essential to be 70 nm or less, and the upper limit of the average particle diameter of the emulsion resin is desirably the above or less.
Further, it is essential that the average particle size of the emulsion resin is smaller than the average particle size of the pigment.
Average particle size ratio = average particle size of emulsion resin [nm] / average particle size of pigment defined by average particle size [nm] of pigment is preferably 0.05 to 0.8 in order to exert the above-mentioned effect. 0.1 to 0.6 is more preferable, and 0.15 to 0.4 is particularly preferable.

  If the average particle size ratio is too large, it will be difficult to form an arrangement in which the emulsion resin particles surround the pigment particles, and the storage stability of the ink and the dispersion stability in the nozzles may be poor. . On the other hand, if the average particle size ratio is too small, the emulsion resin particles may become too small and the emulsion resin particles may be aggregated, which may make synthesis of the emulsion resin particles difficult or economical.

The content of the emulsion resin is required to be 2% by mass or more and 10% by mass or less, and preferably in the range of 3% by mass or more and 9% by mass or less, with respect to the entire aqueous pigment ink composition for inkjet. The range of mass% or less is more preferable, and the range of 5 mass% or more and 7 mass% or less is particularly preferable.
When the content of the emulsion resin is not less than the above lower limit, the effects of the present invention are exhibited, and the storage stability of the ink, the abrasion resistance of the ink film on the substrate, the water resistance, the gloss, etc. are improved.
On the other hand, when the content of the emulsion resin is not more than the above upper limit, the drying property of the landed ink does not become too large, and the ejection stability is excellent.

In the present invention, it is essential that the content of the emulsion resin with respect to the entire ink is greater than or equal to the content of the pigment.
The content ratio defined by [content ratio] = [content of emulsion resin (mass%)] / [content of pigment (mass%)] must be 1 or more in order to exert the above-described effect. 1.0 to 2.6 is preferable, 1.2 to 2.3 is more preferable, and 1.4 to 2 is particularly preferable.

When the content ratio is too small, the emulsion resin is too small, and the particles may not completely cover the periphery of the pigment, and the dispersibility of the pigment particles is deteriorated. The storage stability of the ink, the ejection stability, The water resistance, rubbing resistance, stretchability, etc. of the ink film may be deteriorated.
On the other hand, if the content ratio is too large, the optical density value of the ink film may be decreased, the drying property may be too fast, and the ejection stability may be deteriorated.
When the emulsion resin particles are arranged so as to completely cover the periphery of the pigment, and further combined with 3-methoxy-3-methylbutanol or a pyrrolidone solvent as an aqueous organic solvent, the effect of the present invention is synergistic. Played. This is considered to be because 3-methoxy-3-methylbutanol is an aqueous organic solvent having a molecular structure that does not break the stability of the hydration configuration of the emulsion resin particles.

(Aqueous organic solvent)
In the present invention, the ink contains water and an aqueous organic solvent as a solvent. By containing the aqueous organic solvent, ink viscosity, drying property after landing of the ink, control of MFT (minimum film-forming temperature), improvement of resolubility and the like can be obtained.
As an aqueous organic solvent, 3-methoxy-3-methylbutanol and a pyrrolidone solvent are contained as essential components.

<3-methoxy-3-methylbutanol>
By containing 3-methoxy-3-methylbutanol as the aqueous organic solvent, the re-solubility of the emulsion resin is improved, the cleaning characteristics are improved, and the ejection stability is improved during ink ejection.
In addition, the drying speed after ink landing is significantly improved, the low-temperature drying property is improved and the abrasion resistance is improved, and images are formed by discharging onto a non-ink-absorbing base forest or a low ink-absorbing substrate. However, the drying is fast, the low temperature drying property is good, and a high quality image can be realized.

  In order to obtain high-quality images on low-absorbing substrates or non-ink-absorbing substrates, it is necessary to realize rapid volatilization of ink droplets and prevent dot fusion with droplets that land at time differences. is there. Although these properties are contrary to ejection stability, 3-methoxy-3-methylbutanol is completely compatible with water and evaporates at a certain ratio with water at a relatively low temperature. Therefore, 3-methoxy-3-methylbutanol and water are likely to disappear from the base material almost simultaneously (to make the solvent composition disappear), so that the above-mentioned base material is maintained while maintaining the re-dissolution property and the discharge stability. Even so, the drying property and abrasion resistance are improved.

The content of 3-methoxy-3-methylbutanol is essential to be contained in the range of 2% by mass or more and 18% by mass or less with respect to the whole ink.
Preferably, they are 3 mass% or more and 15 mass% or less, More preferably, they are 4 mass% or more and 12 mass% or less, Especially preferably, they are 5 mass% or more and 9 mass% or less.
When the content of 3-methoxy-3-methylbutanol is in the above range, the above-described effect of containing 3-methoxy-3-methylbutanol is likely to be achieved, and compatibility of physical properties on the contrary is easily achieved. In particular, when the lower limit is not less than the above, the ink ejected from the nozzle and landed on the substrate is excellent in drying property, and excellent in abrasion resistance, water resistance, and the like. If the upper limit is less than or equal to the above, drying is not too fast and clogging is unlikely to occur at the nozzle.

<Pyrrolidone solvent>
The ink of the present invention contains 3-methoxy-3-methylbutanol and a pyrrolidone-based solvent as essential components as an aqueous organic solvent. Among them, the effect of the present invention described above is exhibited by containing a pyrrolidone-based solvent. To do. The pyrrolidone-based solvent has an effect of increasing adhesion to a base material, a MFT lowering effect, etc., which are peculiar to a strong polar organic solvent, and is high even when ejected onto a non-ink-absorbing base material or a low ink-absorbing base material A quality image can be obtained.
Therefore, especially in combination with 3-methoxy-3-methylbutanol, it is synergistic in that it can find a well-balanced formulation for ink re-dissolvability, ejection stability, drying properties, and adhesion to substrates. Demonstrate the effect.

  Specific examples of the pyrrolidone-based solvent include 2-pyrrolidone, N-methylpyrrolidone, N-ethyl-pyrrolidone, and the like. Among them, 2-pyrrolidone is preferable from the viewpoint of safety and environmental load. Particularly preferred.

The content of the pyrrolidone solvent is essential to be contained in the range of 2% by mass or more and 18% by mass or less with respect to the whole ink.
Preferably, they are 3 mass% or more and 15 mass% or less, More preferably, they are 4 mass% or more and 12 mass% or less, Especially preferably, they are 5 mass% or more and 9 mass% or less.
When the content of the pyrrolidone solvent is in the above range, the effect of containing the pyrrolidone solvent is easily achieved, and particularly when the lower limit is the above or more, the adhesion of the ink discharged from the nozzle and landed on the substrate is excellent. Abrasion resistance, water resistance, etc. are improved. In addition, the re-dissolvability of the ink is excellent, and as a result, clogging hardly occurs at the nozzle. On the other hand, when the upper limit is not more than the above, the storage stability of the ink is excellent.

<Total of 3-methoxy-3-methylbutanol and pyrrolidone solvent>
The ink of the present invention preferably contains 3-methoxy-3-methylbutanol and a pyrrolidone-based solvent in a total amount of 4% by mass or more and 25% by mass or less based on the ink. The total amount is more preferably in the range of 5% by mass to 22% by mass, and particularly preferably in the range of 7% by mass to 18% by mass. When the total amount is within the above range, the effects described in the respective sections of 3-methoxy-3-methylbutanol and pyrrolidone solvent are exhibited.

<1,2-alkanediol>
The ink of the present invention may further contain other solvents than the above as the aqueous organic solvent.
Among them, it is preferable to contain 1,2-alkanediol, more preferably 1,2-butanediol, 1,2-pentanediol or 1,2-hexanediol, and 1,2-hexanediol. It is particularly preferable to contain
When 1,2-alkanediol is contained, the moisture retention property, head clogging property, permeability to the base material, and the like are improved, and the effect of reducing solid density unevenness is obtained.

  "Other solvents" with high boiling points such as 1,2-alkanediol generally reduce the evaporation rate of water, but 3-methoxy-3-methylbutanol is easy to azeotrope with water, eliminating this problem it can. That is, even if a high-boiling point “other solvent” such as 1,2-alkanediol is contained, if 3-methoxy-3-methylbutanol is contained, the solvent after the ink landing is evaporated. You can save time. As a result, it exhibits a synergistic effect, and even when it is formed on a non-ink-absorbing substrate or a low-ink-absorbing substrate to form an image, it is excellent in dryness and abrasion resistance and can realize a high quality image. .

  The content of 1,2-alkanediol is not particularly limited, but is preferably 3 to 12% by mass, particularly preferably 5 to 10% by mass, based on the entire ink.

(water)
The ink of the present invention contains water.
The content of water with respect to the entire ink is not limited, but is preferably 60 to 80% by mass, and particularly preferably 65 to 75% by mass.

(Other ingredients)
The aqueous pigment ink composition for inkjet according to the present invention is known to be contained in an ink such as an antifoaming agent, a surface tension adjusting agent, a thickening agent, a pH adjusting agent, a preservative, etc., if necessary. These components may be further contained.

(Ink production method)
The method for producing the aqueous pigment ink composition for inkjet according to the present invention is not particularly limited, but after premixing, the pigment is dispersed in a mixture of water, an aqueous organic solvent and a dispersant by a paint shaker, a sand mill disperser, or the like. The pigment dispersion obtained is preferably produced by mixing with water, the aqueous organic solvent in the present invention, an emulsion resin or the like. Then, it is preferable to manufacture by removing coarse particles using a filter or the like and degassing as necessary.

(Image forming method)
The aqueous pigment ink composition for inkjet according to the present invention is used for forming an image by discharging from a nozzle and landing on a substrate. The image forming method (the type of substrate, the method of drying the landed ink, etc.) is not particularly limited, but the following method is preferred.
The type of the substrate is not particularly limited, but in order to obtain the (synergistic) effect of the above-mentioned 3-methoxy-3-methylbutanol and the pyrrolidone solvent, the substrate is a non-ink such as metal, glass, polyethylene terephthalate, etc. An absorbent base material or a low ink absorbent base material such as vinyl chloride is preferable.

  Regarding the image forming method using the ink of the present invention, the above-described aqueous pigment ink composition for inkjet is ejected from an inkjet head, and the ejected droplets are landed on a substrate, and landed on the substrate. An image forming method comprising heating a water-based pigment ink composition for inkjet at 40 ° C. or higher and 80 ° C. or lower is preferable.

For the discharge, a known ink jet printer or the like can be suitably used. The configuration of the ink jet printer will be described later.
The heating temperature in the heating step is more preferably 50 ° C. or higher and 70 ° C. or lower, and particularly preferably 55 ° C. or higher and 60 ° C. or lower.
By heating in the above temperature range, the abrasion resistance, water resistance and the like are improved, and a high-quality printed image can be formed in which the occurrence of solid portion density unevenness is suppressed.
Further, when the non-ink-absorbing substrate or the low ink-absorbing substrate is used as the substrate, the image forming method is further preferable in order to exhibit the above effects.

(Image formation)
The present invention is an image formed product formed on a substrate using the ink.
Here, examples of the substrate include those described above. The image-formed product is excellent in abrasion resistance, water resistance, stretchability, flexibility, solid portion density unevenness, and the like.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.
Moreover, in the following description, "part" shows a mass part and "%" shows the mass%.
The “emulsion resin dispersion” means an aqueous solution (dispersion) containing an emulsion resin.
In addition, a “base material” that is an object (medium) to be printed may be expressed as a “recording medium”.

Example 1
<Preparation of pigment dispersion>
First, the following materials were weighed in the following proportions, and dispersed for 80 minutes using a bead mill test disperser using zirconia beads having a diameter of 0.3 mm as a dispersion medium, to obtain pigment dispersion A.
The average particle diameter of the pigment in the pigment dispersion A was 140 nm.

(1) Pigment (manufactured by BASF Japan Ltd., trade name “Heliogen Blue D7088”, Heliogen is a registered trademark, average particle diameter 140 nm)
: 20.0 parts (2) Dispersant (BIC Chemie Japan Co., Ltd., trade name “BYKJET-9170”, BYKJET is a registered trademark)
10.0 parts (3) aqueous organic solvent 3-methoxy-3-methylbutanol: 10.0 parts (4) antifoaming agent (manufactured by Nissin Chemical Industry Co., Ltd., trade name “Surfinol 104E”, Surfinol is Registered trademark)
: 0.3 part (5) ion-exchanged water: 59.7 parts

<Preparation of water-based pigment ink composition for inkjet>
Next, the pigment dispersion A obtained above and the following materials were mixed and stirred at the following ratio to obtain an aqueous pigment ink composition for inkjet of Example 1.
(1) Pigment dispersion A (pigment concentration: 20.0%)
: 18.0 parts (2) Emulsion resin dispersion: Vinyl chloride emulsion resin (manufactured by Nissin Chemical Industry Co., Ltd., product name “Viniblanc 701”, Vinibrand is a registered trademark, solid content 30%, average particle size 30 nm)
: 20.0 parts (3) Aqueous organic solvent 1: 3-methoxy-3-methylbutanol: 4.0 parts (4) Aqueous organic solvent 2: 2-pyrrolidone: 5.0 parts (5) Aqueous organic solvent 3: EVONIK, 1,2-hexanediol, etc .: 7.0 parts (6) Various additives (antifoaming agent, surface tension adjusting agent, etc.)
: 0.5 part (7) ion-exchanged water: 45.5 parts

Example 2
An aqueous pigment ink composition for inkjet of Example 2 was prepared in the same manner as in Example 1 except that the emulsion resin dispersion was changed to the trade name “Viniblanc 711” (manufactured by Nissin Chemical Industry Co., Ltd.). .
“Vinyl Blanc 711” is a vinyl chloride emulsion resin having a solid content of 30% and an average particle size of 70 nm.

Example 3
The emulsion resin dispersion was changed from 20.0 parts of “Vinibran 701” to 15.7 parts of “Acryt WAN-6000” (manufactured by Taisei Fine Chemical Co., Ltd., Acryt is a registered trademark), and the amount of ion-exchanged water was changed. An ink-jet aqueous pigment ink composition of Example 3 was produced in the same manner as Example 1 except that the amount was changed to 49.8 parts.
“Acryt WAN-6000” is an acrylic emulsion resin having a solid content of 38.3% and an average particle size of 30 nm.

Example 4
The amount of 3-methoxy-3-methylbugnol, which is “aqueous organic solvent 1” in preparing the aqueous pigment ink for inkjet, is changed from 4.0 parts to 2.0 parts, and “aqueous organic solvent 2” is 2 -Implemented in the same manner as in Example 1 except that the amount of pyrrolidone was changed from 5.0 parts to 2.0 parts and the amount of ion-exchanged water was changed from 45.5 parts to 50.5 parts. The aqueous pigment ink composition for inkjet of Example 4 was prepared.

Example 5
Example 1 except that the amount of 2-pyrrolidone “Aqueous organic solvent 2” was changed from 5.0 parts to 15.0 parts and the amount of ion-exchanged water was changed to 35.5 parts. Similarly, an aqueous pigment ink composition for inkjet of Example 5 was produced.

Example 6
The blending amount of 3-methoxy-3-methylbutanol, which is “aqueous organic solvent 1” in preparing the aqueous pigment ink for inkjet, was changed from 4.0 parts to 15.0 parts, and the blending amount of ion-exchanged water was 34. A water-based pigment ink composition for inkjet of Example 6 was prepared in the same manner as Example 1 except that the amount was changed to 5 parts.

Example 7
The amount of 3-methoxy-3-methylbutanol, which is “aqueous organic solvent 1” in preparing the aqueous pigment ink for inkjet, was changed from 4.0 parts to 10.0 parts, and “aqueous organic solvent 2”. In the same manner as in Example 1, except that the amount of 2-pyrrolidone was changed from 5.0 parts to 10.0 parts and the amount of ion-exchanged water was changed to 34.5 parts. An aqueous pigment ink composition for inkjet was prepared.

Example 8
The same procedure as in Example 1 was performed except that the amount of the emulsion resin dispersion “Viniblanc 701” was changed from 20.0 parts to 13.3 parts and the amount of ion-exchanged water was changed to 52.2 parts. Thus, an aqueous pigment ink composition for ink jets of Example 8 was produced.

Example 9
The same procedure as in Example 1 was conducted except that the amount of the emulsion resin dispersion “Viniblanc 701” was changed from 20.0 parts to 30.0 parts and the amount of ion-exchanged water was changed to 35.5 parts. Thus, an aqueous pigment ink composition for inkjet of Example 9 was produced. In Example 9, the emulsion resin content was 9.0 parts.

Example 10
The blending amount of 3-methoxy-3-methylbutanol, which is “aqueous organic solvent 1” in preparing the aqueous pigment ink for inkjet, was changed from 4.0 parts to 0.7 parts, and the blending amount of ion-exchanged water was 48. A water-based pigment ink composition for inkjet of Example 10 was prepared in the same manner as Example 1 except that the amount was changed to 8 parts.

Comparative Example 1
The emulsion resin dispersion was changed from 20.0 parts of “ViniBran 701” to 12.0 parts of the trade name “ViniBran 603” (manufactured by Nissin Chemical Industry Co., Ltd.), and the amount of ion-exchanged water was 53.5 parts. A water-based pigment ink composition for inkjet of Comparative Example 1 was produced in the same manner as in Example 1 except that it was changed to. “ViniBran 603” is a vinyl chloride / vinyl acetate emulsion resin having a solid content of 50% and an average particle size of 150 nm.

Comparative Example 2
Example 1 except that the emulsion resin dispersion was changed from 20.0 parts of “Viniblanc 701” to 20.0 parts of the trade name “Polysol AP6730” (manufactured by Showa Denko KK, Polysol is a registered trademark). Thus, an aqueous pigment ink composition for inkjet of Comparative Example 2 was produced.
“Polysol AP6730” is a styrene / acrylic emulsion resin having a solid content of 30% and an average particle size of 100 nm.

Comparative Example 3
Among the formulations shown in <Preparation of aqueous pigment ink composition for inkjet> in Example 1 above,
(3) Aqueous organic solvent 1: 3-methoxy-3-methylbutanol: not blended (4) Aqueous organic solvent 2: 2-pyrrolidone: Not blended (5) Aqueous organic solvent 3: EVONIK, 1, 2 -Hexanediol and the like: An aqueous pigment ink composition for inkjet of Comparative Example 3 was produced in the same manner as in Example 1 except that the amount was changed to 16.0 parts.

Comparative Example 4
Among the formulations shown in <Preparation of aqueous pigment ink composition for inkjet> in Example 1 above,
(3) Aqueous organic solvent 1: 3-methoxy-3-methylbutanol: not blended (4) Aqueous organic solvent 2: 2-pyrrolidone: 5.0 parts (no change from Example 1)
(5) Aqueous organic solvent 3: EVONIK Co., 1,2-hexanediol, etc .: 1. Ink-jet aqueous pigment ink composition of Comparative Example 4 in the same manner as in Example 1 except that it was changed to 11.0 parts. Was made.

Comparative Example 5
Among the formulations shown in <Preparation of aqueous pigment ink composition for inkjet> in Example 1 above,
(3) Aqueous organic solvent 1: 3-methoxy-3-methylbutanol: 4.0 parts (no change from Example 1)
(4) Aqueous organic solvent 2: 2-pyrrolidone: Not blended (5) Aqueous organic solvent 3: EVONIK, 1,2-hexanediol, etc .: Same as Example 1 except for changing to 12.0 parts Thus, an aqueous pigment ink composition for inkjet of Comparative Example 5 was produced.

Comparative Example 6
Among the formulations shown in <Preparation of aqueous pigment ink composition for inkjet> in Example 1 above,
(3) Aqueous organic solvent 1: 3-methoxy-3-methylbutanol: 4.0 parts (no change from Example 1)
(4) Aqueous organic solvent 2: 2-pyrrolidone: 20.0 parts (5) Aqueous organic solvent 3: EVONIK, 1,2-hexanediol, etc .: 7.0 parts (no change from Example 1)
The aqueous pigment ink composition for inkjet of Comparative Example 6 was produced in the same manner as in Example 1 except that the amount of ion-exchanged water was changed to 30.5 parts.

Comparative Example 7
Among the formulations shown in <Preparation of aqueous pigment ink composition for inkjet> in Example 1 above,
(3) Aqueous organic solvent 1: 3-methoxy-3-methylbutanol: 20.0 parts (4) Aqueous organic solvent 2: 2-pyrrolidone: 5.0 parts (no change from Example 1)
(5) Aqueous organic solvent 3: EVONIK, 1,2-hexanediol, etc .: 7.0 parts (no change from Example 1)
A water-based pigment ink composition for inkjet of Comparative Example 7 was prepared in the same manner as in Example 1 except that the amount of ion-exchanged water was changed to 29.5 parts.

Comparative Example 8
Except for changing the blending amount of the vinyl resin 701, which is an emulsion resin dispersion, from 20.0 parts to 35.0 parts and changing the blending amount of ion-exchanged water to 30.5 parts, the same as in Example 1. Then, an aqueous pigment ink composition for inkjet of Comparative Example 8 was produced.
In Comparative Example 8, the content of the emulsion resin was 10.5 parts.

Comparative Example 9
The same procedure as in Example 1 was conducted except that the blending amount of the vinyl resin 701 as an emulsion resin dispersion was changed from 20.0 parts to 6.0 parts and the blending amount of ion-exchanged water was changed to 74.5 parts. Then, an aqueous pigment ink composition for inkjet of Comparative Example 9 was produced.
In this comparative example 9, the content of the emulsion resin was 1.8 parts.

  The component compositions of Examples 1 to 10 are shown in Table 1 below, and the component compositions of Comparative Examples 1 to 9 are shown in Table 2 below. The numerical value in the table is the final content (% by mass) of each component with respect to the entire ink composition, including the content of each component in the pigment dispersion used for preparing the ink composition.

  Evaluation methods and criteria are shown below.

<Emulsion resin particle size>
The cumulant average particle diameter was measured by a dynamic light scattering method using a dense particle analyzer FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.

<Solid content of emulsion resin>
The emulsion resin dispersion was dried at 150 ° C. for 2 hours and weighed to obtain a “solid content”.

<Method for evaluating storage stability>
Each ink was sealed in a sample bottle and left in a 45 ° C. environment for 3 months.
The storage stability of the ink was evaluated by observing the change in the viscosity of the ink after standing and the separation / sedimentation / aggregation state of the ink components.

<< Criteria for "viscosity change" in storage stability >>
A: The rate of change is less than ± 5% compared to the viscosity immediately after preparation. B: The rate of change is more than ± 5% and less than ± 10% compared to the viscosity immediately after preparation. C: Compared with the viscosity immediately after preparation. The rate of change is ± 10% or more and less than ± 20%. D: The rate of change is ± 20% or more compared to the viscosity immediately after preparation.

<< Criteria for separation, sedimentation, and aggregation of ink components in storage stability >>
A: None of ink component separation, sedimentation, and aggregation is observed. B: One of ink component separation, sedimentation, and aggregation is slightly observed. C: Ink component separation, sedimentation, and aggregation. , One can be clearly seen D: separation, sedimentation and aggregation of ink components are all remarkably seen

<Method for evaluating re-solubility>
Each color ink was applied on an aluminum plate with a bar coater # 3 and left at room temperature for 1 month.
Drop a drop of the same color ink on the coating plate after standing (spread in a circle). After 3 minutes, fold a paper waste (using Kimwipe (registered trademark)) in 1/8, and lightly from just above the ink drop Hold with your finger. This operation was performed three times on a new surface of the paper waste, and the coated surface from which ink was sucked was observed.

<< Re-solubility criteria >>
A: The ink component on the coated surface dissolves in a circle and is absorbed by a paper waste, and the surface of the aluminum plate is exposed in a circular shape. B: The ink component on the coated surface partially dissolves in a circle and forms a paper waste. C: Residue remains on the surface of the aluminum plate C: Ink component on the coated surface swells in a circle but hardly dissolves and is hardly absorbed by paper waste D: Ink component on the coated surface swells and dissolves in a circle No change (no change), not absorbed by paper waste, leaving no trace of ink drops

<Evaluation of ejection stability>
<Method for evaluating continuous discharge>
As an ink jet recording type printer, an ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) is filled with ink, and a recording medium VJ-MF-3G (trade name, genuine recording medium of Muto Kogyo Co., Ltd.) is used. The nozzle check patterns before and after the filling pattern was printed were compared, and if the nozzle check pattern after the filling pattern was printed had a new defect, it was judged good.
The printing pattern is 100% duty for each color of Bk, Cy, Ma, and Ye. When printing at 2 pass of 720 dpi horizontal and 720 dpi vertical, without setting the platen heater, printing at 16 pass of 1440 dpi horizontal and 1440 dpi vertical Set the platen heater to 50 ° C.

<Continuous discharge criteria>
A: No defect in the nozzle check pattern for each color occurs after printing the filled pattern B: One to four defects occur in the nozzle check pattern for each color after printing the painted pattern C: Each color after printing the filled pattern 5 to 9 defects occur in the nozzle check pattern of D: 10 or more defects occur in the nozzle check pattern for each color after the filling pattern is printed

<Head clogging evaluation method>
Ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) as an ink jet recording type printer is filled with ink so that the nozzle is not clogged, and then a nozzle check pattern is printed, and the print head cap is attached. The power was turned off in the mounted state and left at room temperature for one week.
After one week, the nozzle check pattern is printed again, the nozzle check patterns before and after being left at room temperature for one week are compared, and whether there is no defect in the pattern after one week has passed, or whether ejection is normal after the cleaning operation. Observed.

<< Head clogging criteria >>
A: No nozzle check pattern defect or nozzle check pattern defect after standing at room temperature for 1 week, but ink is normally ejected from all nozzles by cleaning operation within 3 times B: After standing at room temperature for 1 week Nozzle check pattern defect occurs, but ink is normally ejected from all nozzles in 4 to 6 cleaning operations C: Nozzle check pattern defect occurs after standing at room temperature for 1 week Ink is normally ejected from all nozzles in the cleaning operation D: After leaving at room temperature for 1 week, a missing nozzle check pattern occurs, and no matter how much cleaning operation is performed, ink is not normally ejected from all nozzles.

<Evaluation of printed matter>
<Dryness evaluation method>
As an ink jet recording type printer, an ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) is filled with ink, and a recording medium VJ-MF-3G (trade name, genuine recording medium of Muto Kogyo Co., Ltd.) is used. A solid pattern was printed under the conditions of 720 dpi horizontal, 720 dpi vertical, 8 pass, platen heater set to 50 ° C.
The printed matter was left in a constant temperature bath at 60 ° C. for a predetermined time, and then taken out. A cotton kanakin No. 3 was attached to a JIS L 0849 type I friction tester and rubbed 100 times with a load of 900 g. This operation was repeated several times, and the time for obtaining sufficient strength was recorded.
The print pattern is 100% duty, and each Bk, Cy, Ma, Ye, R (Ye 100% + Ma 100%), G (Ye 100% + Cy 100%), B (Cy 100% + Ma 100%), 3K (cy 100% + Ma 100% + Ye 100%) ) Fill pattern was used.

<Drying criteria>
A: In each color painting pattern of 100% duty, sufficient frictional strength can be obtained by heating in a thermostat set at 60 ° C. for less than 6 minutes. B: In each color painting pattern of 100% duty, it was set to 60 ° C. Sufficient frictional strength can be obtained by heating in a thermostatic bath in the range of 6 to 8 minutes C: In each color coating pattern of 100% duty, heating in the range of 8 to 10 minutes in a thermostatic bath set at 60 ° C Sufficient friction strength can be obtained D: In each color coating pattern of 100% duty, sufficient friction strength cannot be obtained by heating up to 10 minutes in a thermostatic bath set at 60 ° C.

<Rubbing resistance evaluation method>
As an ink jet recording type printer, an ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) is filled with ink, and a recording medium VJ-MF-3G (trade name, genuine recording medium of Muto Kogyo Co., Ltd.) is used. A solid pattern was printed under the conditions of 720 dpi horizontal, 720 dpi vertical, 8 pass, platen heater set to 50 ° C.
The printed matter was left in a constant temperature bath at 60 ° C. for 10 minutes and then taken out, and a cotton cloth No. 7 Kin No. 3 was attached to a JIS L 0849 I type friction tester and rubbed 100 times with a load of 900 g.
As the print pattern, a fill pattern of Bk, Cy, Ma, and Ye was used at 100% duty.

〈〈 Criteria for rubbing resistance 〉〉
A: There is no scratch on the printed surface after the test, and there is almost no color transfer to the test cloth. B: There is a small scratch on the printed surface after the test, and there is a color transfer to the test cloth. C: On the printed surface after the test. There is a scratch, and the recording medium is exposed at that portion. D: The printing surface after the test is peeled off, and the recording medium is largely exposed.

<Water resistance evaluation method>
As an ink jet recording type printer, an ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) is filled with ink, and a recording medium VJ-MF-3G (trade name, genuine recording medium of Muto Kogyo Co., Ltd.) is used. A solid pattern was printed under the conditions of 720 dpi horizontal, 720 dpi vertical, 8 pass, platen heater set to 50 ° C.
The printed matter was left in a constant temperature bath at 60 ° C. for 10 minutes and then taken out, and a cotton kanakin No. 3 moistened with water was attached to a JIS L 0849 type I friction tester and subjected to 10 reciprocating frictions with a load of 900 g.
As the print pattern, a fill pattern of Bk, Cy, Ma, and Ye was used at 100% duty.

<Water resistance criteria>
A: There is no scratch on the printed surface after the test, and there is almost no color transfer to the test cloth. B: There is a small scratch on the printed surface after the test, and there is a color transfer to the test cloth. C: On the printed surface after the test. There is a scratch, and the recording medium is exposed at that portion. D: The printing surface after the test is peeled off, and the recording medium is largely exposed.

<Evaluation method of stretchability>
As an ink jet recording type printer, an ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) is filled with ink, and a recording medium VJ-MF-3G (trade name, genuine recording medium of Muto Kogyo Co., Ltd.) is used. After printing a solid pattern under the conditions of 720 dpi in width, 720 dpi in length, and a platen heater set to 50 ° C., the release paper portion of VJ-MF-3G was peeled off and stretched to a stretch ratio of 2 times.

〈〈 Criteria for stretchability 〉〉
A: A printing film with a stretching ratio of 2 times follows the stretching of the recording medium, and no abnormality is observed on the surface. B: The surface gloss of the printing film with a stretching ratio of 2 times decreases. C: A stretching ratio of 2 times. A crack visible to the naked eye is observed on the printed film of D: D: The printed film is hardly stretched and the printed film is partially peeled off

<< Evaluation method for solid portion shading unevenness >>
As an ink jet recording type printer, an ink jet printer VJ-1304 (trade name, manufactured by Muto Kogyo Co., Ltd.) is filled with ink, and a recording medium Vj-MF-3G (product name, Muto Kogyo Co., Ltd. genuine recording medium) is filled. The color chart and JISx9204 N7RGB were printed at a horizontal of 720 dpi, vertical of 720 dpi, 8 pass, or vertical of 1440 dpi, horizontal of 1440 dpi, with a platen heater set at 50 ° C., and the presence or absence of density unevenness was visually confirmed.

<Judgment criteria for solid color shading>
A: There is no mottling at duty 160% or more in the color chart, and there is no shading unevenness in JISx9204 N7RGB B: There is mottling at duty 160% or more in the color chart, and there is some shading unevenness in the dark part of JISx9204 N7RGB C: In the color chart, there is a mottling at a duty of 100% to 160%, and in JISx9204 N7RGB, there is a clear shading unevenness in a dark portion.
D: In the color chart, there is a mottling when the duty is 100% or less, and in JISx9204 N7RGB, there is a shading unevenness in the entire printing range.

〈〈 Evaluation criteria for comprehensive evaluation 〉〉
All the determination results of the above evaluation items were combined and comprehensively evaluated according to the following determination criteria.

<Judgment criteria for comprehensive evaluation>
A4: No more than “B” and one or less “A to B” A3: No more than “B” and two or more “A to B” A2: No “C” or less and one “B” A1: “C” is not less than 2 “B” is B: “C” is not less than 3 “B” is 3 C: “D” is not present and “C” is 1 or more, or “B” is 4 or more D: One or more “D”

  The results of Examples 1 to 10 are shown in Table 3 below, and the results of Comparative Examples 1 to 9 are shown in Table 4 below.

As is apparent from the results in Tables 3 and 4 above, the inks of the examples using a predetermined amount of 3-methoxy-3-methylbutanol and pyrrolidone-based solvent are ink storage stability, ink re-solubility, ejection stability, And it was excellent in all the evaluation items of evaluation of printed matter with good balance, and the comprehensive evaluation was also excellent with A1 to A4.
On the other hand, the ink of the comparative example that did not satisfy the requirements of the present invention was inferior to any of the evaluation items, and the overall evaluation was inferior to B to D.

  As described above, the present invention has been described with reference to examples. However, “re-solubility” and “stretchability” listed here as evaluation items are further supplemented with respect to “overall evaluation”.

In the above-described embodiment, re-solubility is evaluated by observing the state in which each ink is applied on an aluminum plate, and the ink of the same color is dropped again and dissolved after being left for one month. The purpose of this evaluation is to indirectly evaluate the degree of clogging during running in the inkjet head of the printer. In other words, the inkjet head is always moist as long as it is continuously printed, but when printing is stopped and left for a long time, it dries. Deteriorate. When the dry film covers the discharge holes, if the red ink is not re-dissolved by the new ink supplied at the time of printing (if the re-dissolvability is extremely poor), the discharge holes are clogged, and printing dots are not formed. In addition, if a portion is dissolved, dots will not be lost, but the landing position will not be displaced, and a normal dot shape will not be formed, so the print quality will deteriorate. On the other hand, when the re-dissolvability is extremely high, the ink is immediately dissolved by the new ink, and a high print quality is reproduced. In order to observe such a tendency in a prominent manner, an evaluation by drying, dripping and wiping on an aluminum plate is used instead of an inkjet head.
In other words, when the re-solubility evaluation result is D, the print reproducibility is poor when resuming printing after being left for a long time, and when the evaluation result is A, printing is resumed when printing is resumed. It means that reproducibility is good. That is, the evaluation result A is excellent in the durability of the printer (inkjet head) for drying in the atmosphere and is excellent in durability in the actual cycle of printing use-unused (leaving in the atmosphere) -printing use. It is.

  Regarding the stretchability, after printing on the base material first using an ink jet printer, the base material is stretched to a length of 2 times (stretch ratio is 2 times), and the surface state is observed. This evaluation means evaluation of both the adhesion of the printed coating and the flexibility of the coating. That is, this evaluation is A. In addition to being in a state where the adhesion between the printed coating film and the substrate is high and does not easily peel, the printed coating film itself has flexibility and is stretched about twice. Means that no cracks occur and the coating does not break and separate. This means that it can withstand the dynamic load and stress when printing the printed material, when winding the printed material, and when printing the printed material outdoors. It is an index that represents the durability of the material.

The “comprehensive evaluation” is evaluated in seven stages from A4 to D. A1 to A4 in the comprehensive evaluation are excellent in balance in ink storage stability, ink re-dissolvability, ejection stability, and evaluation of printed matter. In other words, not only the print quality at the time of printing but also winding and cutting after printing, etc. It has the durability to withstand actual use such as processing, transportation, distribution and posting, and the actual use durability of the printer. In particular, since it is excellent in stretchability, water resistance, and abrasion resistance, it means that the printed material has the ability to withstand tough use such as advertisement posting in an outdoor exposure environment.
On the other hand, B to D in the comprehensive evaluation are inferior to any of the evaluation items. In other words, they have some drawbacks in the image quality immediately after printing or the use environment, and thus cannot withstand the actual use. Is. That is, it can be said that the comprehensive evaluations A1 to A4 and BD are completely different performances, and it can be said that Examples 1 to 10 having the comprehensive evaluations A1 to A4 have a remarkable effect corresponding to this problem.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

For example, in the above-described embodiment, VJ-MF-3G (trade name, genuine recording medium manufactured by Muto Kogyo Co., Ltd.) is used as the base material (recording medium) in the examples. However, the present invention is not limited to this. . VJ-MF-3G is sold as a sheet made of vinyl chloride (PVC, polyvinyl chloride resin), but the same effect can be obtained with another brand as long as the sheet is also made of vinyl chloride. be able to.
Further, as described above, the type of the substrate used in the present invention is not particularly limited, and in addition to vinyl chloride, non-ink-absorbing substrates such as metals, glass, polyethylene terephthalate (PET), and the like, An ink-absorbing substrate can be used.

Next, specific examples of the present invention on base materials other than VJ-MF-3G are introduced. As vinyl chloride, “ORAJET 3620” (manufactured by ORAFOL, ORAJET is a registered trademark) was used in addition to VJ-MF-3G. "Panlite" (manufactured by Teijin Ltd., Panlite is a registered trademark) as polycarbonate, "Comoglass transparent" (manufactured by Kuraray Co., Ltd., registered trademark), and "Lumirror T188" (manufactured by Toray Industries, Inc.) as polyethylene terephthalate Lumiller was a registered trademark, and “FL3 (float)” (manufactured by Nippon Sheet Glass Co., Ltd.) and aluminum alloy “A5052” were used as glass. In particular, the results of printing and evaluation on various substrates in the same manner as in the previous examples, represented by “rubbing resistance” and “water resistance (immersion)”, are shown below. Table 5 uses the ink composition of Example 1 and prints on each non-absorbent recording medium by an ink jet printer, and forms the coating film at a temperature of MFT or higher (in a thermostatic bath at 60 ° C. for 10 minutes). It is the result of having been allowed to stand at room temperature for 24 hours after being dried) and performing each test.
The evaluation method of “rub resistance” in this test is to evaluate the appearance of the coating film after reciprocating the coating film 100 times with a load of 900 g of cotton cloth Kanakin No. 3 in a friction tester.
As for the evaluation method for “water resistance (immersion)”, the appearance and color fading of the coating film after the test piece applied to each non-absorbent recording medium was immersed in room temperature tap water for 24 hours and left at room temperature were evaluated. Has been implemented.
Here, as a criterion, “Abrasion resistance” evaluation A means “the printed surface after the test is not scratched and there is almost no color transfer to the test cloth”, and “water resistance (immersion) ")" Means that "the printed surface after the test is hardly discolored or discolored".

  As described above, the ink composition of the present invention is not limited to the case where vinyl chloride is used as a base material (recording medium), and exhibits excellent properties for various base materials. It can be said that the ink composition can be widely applied to materials and low ink-absorbing substrates.

  Moreover, in said embodiment, although Heliogen Blue D7088 (color: cyan) was mentioned as a pigment in an Example, it is not limited to this. As described above, the same effect can be obtained if the pigment has an average particle diameter of 20 to 500 nm. Further, the color of the pigment is not limited to cyan, and for example, magenta, yellow or black can be selected. Furthermore, it is possible to combine four types of inks of magenta, yellow, cyan, and black, or to combine seven types of ink having two types of magenta, yellow, and cyan in shades of color. In addition, orange and green can be combined with these configurations. Therefore, the present invention is not limited to a specific color, and an ink set composed of a plurality of colors is also included in an equivalent range.

Next, an ink jet printer that discharges the ink composition of the present invention will be described. FIG. 1 is a block diagram showing an ink jet printer 10 according to the present invention.
The ink jet printer 10 includes a roller 11, an ink jet head 14, drivers 13 and 16, a control unit 15, and an image processing unit 17. The control unit 15 controls a driver 13 for driving the roller 11 and moves the base material (recording medium) 12 by the roller 11. Further, the control unit supplies image data sent from a network line, a memory, an external device, or the like to the image processing unit 17. The image processing unit converts the image data into image recording data for recording an image by causing the ink composition 20 to land on the substrate 12 by the inkjet head 14, and outputs the image recording data to the inkjet head 14.
The inkjet head 14 is arranged so that the ejection direction of the ink composition 20 faces the substrate, and the entire inkjet head 14 can be moved by a driver 16. The inkjet head 14 includes an ink tank (not shown) that is a holding unit for the ink composition 20. The driver 16 has a drive source such as a motor, and the drive source is driven by a drive signal from the control unit 15 to move the ink jet head 14 in a direction along the surface of the substrate 12, so that the ink composition 20 Is ejected to land on the substrate 12. The landed ink composition 20 is heated by a heating step (not shown), whereby the image formed product according to the present invention can be obtained. In addition, although the platen heater was used in the Example as an example of a heating process, it is not restricted to this, An air heater (heat air blow), an infrared lamp, etc. can be used individually or in combination.

  The water-based pigment ink composition for inkjet using the 3-methoxy-3-methylbutanol and pyrrolidone solvent of the present invention is used in printers, copiers, printing presses, etc., and has storage stability, ink re-dissolvability, and ejection stability. In order to give excellent printed matter with excellent properties and the like, it is widely used in such fields.

10 Inkjet printer 11 Roller 12 Base material (recording medium)
13, 16 Driver 14 Inkjet head 15 Control unit 17 Image processing unit 20 Ink composition

Claims (9)

An aqueous pigment ink composition for inkjet, comprising a pigment, a dispersant, an emulsion resin, water and an aqueous organic solvent,
The average particle size of the emulsion resin is smaller than the average particle size of the pigment and 70 nm or less;
The content of the emulsion resin is not less than the content of the pigment and not less than 2% by mass and not more than 10% by mass with respect to the entire aqueous pigment ink composition for inkjet.
The aqueous organic solvent contains 3-methoxy-3-methylbutanol and a pyrrolidone solvent in a range of 2% by mass or more and 18% by mass or less, respectively, with respect to the entire aqueous pigment ink composition for inkjet. An aqueous pigment ink composition for inkjet.   2. The aqueous inkjet ink according to claim 1, comprising 3-methoxy-3-methylbutanol and a pyrrolidone-based solvent in a total amount of 4% by mass or more and 25% by mass or less with respect to the entire aqueous pigment ink composition for inkjet. Pigment ink composition.   The aqueous pigment ink composition for inkjet according to claim 1 or 2, wherein the emulsion resin is a vinyl chloride, (meth) acrylic or urethane emulsion resin.   The aqueous pigment ink composition for inkjet according to any one of claims 1 to 3, wherein the pyrrolidone-based solvent is 2-pyrrolidone.   The aqueous pigment ink composition for inkjet according to any one of claims 1 to 4, which is used for forming an image on a non-ink-absorbing substrate or a low ink-absorbing substrate.   An ejection step of ejecting the aqueous pigment ink composition for inkjet according to any one of claims 1 to 5 from an inkjet head and landing the ejected droplets on a substrate, and landing on the substrate And a heating step of heating the water-based pigment ink composition for inkjet at 40 ° C. or higher and 80 ° C. or lower.   An image-formed product formed on a substrate using the aqueous pigment ink composition for inkjet according to any one of claims 1 to 5.   An ink set comprising the aqueous pigment ink composition for inkjet according to any one of claims 1 to 5. An inkjet head;
A driver for driving the inkjet head;
An image processing unit;
With a control unit,
An ink jet printer that discharges the aqueous pigment ink composition for ink jet according to any one of claims 1 to 5 from the ink jet head.

Images