JP2022062680A - Water-based inkjet ink, water-based inkjet ink set, and inkjet recording method - Google Patents

Abstract

To provide an active energy ray-curable water-based inkjet ink that has excellent dischargeability and can be, therefore, discharged with high efficiency and left to stand with high stability, and that can form a cured film having excellent properties such as scratch resistance and water resistance, and an inkjet recording method using the same.SOLUTION: The water-based inkjet ink is an active energy ray-curable water-based inkjet ink including a water-soluble monomer having a polymerizable group. The water-based inkjet ink further includes a hydrazide compound. The water-soluble monomer is a curable substance having a ketone structure. The ink jet recording method includes the steps of: discharging the water-based inkjet ink from an inkjet recording head to a recording medium, to form a first uncured image; and curing the first uncured image by an active energy ray curing reaction and a chemical crosslinking reaction to form an image.SELECTED DRAWING: None

Description

The present invention relates to an active energy ray-curable water-based inkjet ink, a water-based inkjet ink set, and an inkjet recording method using them.

Conventionally, a method of irradiating a liquid composition applied onto a recording medium with active energy rays to cure a curable substance in the liquid composition to form a cured film and recording an image is known. In this method, for example, a liquid composition (curable emulsion paint) obtained by adding a coloring material to an aqueous vehicle in which a non-aqueous active energy ray-curable substance is emulsified and dispersed is applied to a medium, and then irradiated with ultraviolet rays to obtain an image. It is classified as a technology for recording.

In recent years, active energy ray-curable liquid compositions and various paints have been widely applied in fields such as graphic arts, sign arts, display panel manufacturing, label recording, package recording, and electronic circuit board manufacturing. Among them, a technique of applying a liquid composition containing an active energy ray-curable substance to an inkjet recording method using an ink as an ink is known.

A non-aqueous or aqueous compound is used as a curable substance in the active energy ray-curable ink applied to the inkjet recording method. Active energy ray-curable inks using non-aqueous curable substances are roughly classified into two types. One is a so-called oil-based ink in which a pigment is dispersed in an organic solvent such as toluene or methyl ethyl ketone. The other is a so-called 100% curable ink (non-solvent ink) that does not use an organic solvent and contains liquid monomers, oligomers, and pigment dispersions.

When using oil-based ink, the organic solvent easily volatilizes into the atmosphere, so sufficient consideration for the environment is required. Further, when 100% curable ink is used, all the components applied on the recording medium are used as a cured film, so that a step (unevenness) is likely to occur between the recording portion and the non-recording portion, and the glossiness of the image is improved. Is difficult. Therefore, it is difficult to develop an active energy ray-curable ink using a non-aqueous curable substance into applications that require high image quality.

On the other hand, in the case of an ink using an aqueous curable substance, since an aqueous solvent containing water as a main component is used, the addition to the environment due to the volatilization of the solvent is extremely small. In addition, since the image is less likely to have irregularities, the glossiness of the image can be improved. For the above reasons, it can be said that it is extremely useful to apply an active energy ray-curable water-based ink liquid composition using a water-based curable substance to an inkjet recording method. In addition to such active energy ray-curable water-based inks, various water-soluble curable substances used therein have been studied.

For such water-soluble curable substances, for example, they are highly water-soluble in the state before curing, do not deteriorate the performance of the ink even if they coexist with a coloring material, and are stable even under normal temperature conditions. It is required to have characteristics such as being present and not deteriorating the ejection property of ink. Furthermore, it exhibits high sensitivity to water-soluble curable substances with respect to light of a predetermined wavelength, can form a cured film having excellent scratch resistance, and has high resistance to various organic solvents and water. It is also required to have characteristics such as being resistant to yellowing even in various environments.

Various curable substances used for active energy ray-curable water-based inks have been proposed so far. For example, an ink using a polyfunctional acrylamide compound having both water solubility and photocurability as a curable substance has been proposed (Patent Document 1). Further, monofunctional acrylamide, which is used in combination with the curable substance proposed in Patent Document 1, has been proposed (Patent Document 2). On the other hand, various types of inks that can be cured without using active energy rays have also been studied. For example, an ink containing a polymer compound having an acrylamide structure and a crosslinkable functional group and which can be cured by a crosslink reaction has been proposed (Patent Document 3).

Japanese Unexamined Patent Publication No. 2013-018846 Japanese Unexamined Patent Publication No. 2012-214561 Japanese Patent No. 6015913

However, since the curable substance proposed in Patent Document 1 is a polyfunctional compound, there is a problem that the crosslink density of the formed cured film becomes too high and the cured film tends to become brittle. Further, by using the acrylamide compound proposed in Patent Document 2, the characteristics of the cured film are improved, but there is a problem that the water resistance is lowered because the crosslink density is lowered.

Further, even with the polymer compound proposed in Patent Document 3, since the absolute amount of the cross-linking component is small, there still has a problem that the water resistance is lowered. In addition, it is necessary to contain a solvent component in order to stably eject the ink containing the polymer compound by the inkjet method. However, since the solvent component tends to affect the water resistance of the formed cured film, it is difficult to achieve both the ink ejection property and the water resistance of the formed cured film.

Therefore, an object of the present invention is an active energy ray-curable type capable of forming a cured film having excellent ejection performance such as ejection property and leaving stability, and also excellent characteristics such as scratch resistance and water resistance. To provide water-based inkjet inks. Further, an object of the present invention is an active energy ray-curable type capable of forming a cured film having excellent ejection performance such as ejection property and leaving stability, and also excellent characteristics such as scratch resistance and water resistance. To provide a water-based inkjet ink set. Further, an object of the present invention is to provide an inkjet recording method using the above-mentioned water-based inkjet ink and water-based inkjet ink set, respectively.

That is, according to the present invention, it is an active energy ray-curable water-based inkjet ink containing a water-soluble monomer having a polymerizable group, further containing a hydrazide compound, and the water-soluble monomer is cured having a ketone structure. A water-based inkjet ink characterized by being a sex substance is provided.

According to the present invention, an active energy ray-curable water-based product capable of forming a cured film having excellent ejection performance such as ejection property and leaving stability, as well as excellent properties such as scratch resistance and water resistance. Inkjet ink can be provided. Further, according to the present invention, an active energy ray-curable type capable of forming a cured film having excellent ejection performance such as ejection property and leaving stability and also excellent characteristics such as scratch resistance and water resistance. Aqueous inkjet ink set can be provided. Further, according to the present invention, it is possible to provide an inkjet recording method using the above-mentioned water-based inkjet ink and water-based inkjet ink set, respectively.

It is a perspective view which shows an example of the structure of the inkjet recording apparatus schematically. It is a schematic diagram which shows the positional relationship between the ink cartridge mounting position in a recording head, and the UV-LED irradiation apparatus.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. Further, the water-based ink for inkjet may be simply referred to as "ink". Further, the water-based ink set for inkjet may be simply referred to as "ink set". The physical characteristic values are values at room temperature (25 ° C.) unless otherwise specified.

<Water-based inkjet ink, water-based inkjet ink set>
The ink of the present invention is an active energy ray-curable water-based inkjet ink containing a water-soluble monomer having a polymerizable group. The ink of the present invention further contains a hydrazide compound, and the water-soluble monomer is a curable substance having a ketone structure. The water-soluble monomer is a curable substance that is cured by an active energy ray curing reaction. Further, since the water-soluble monomer has a ketone structure in its molecular structure, it is also a curable substance that is cured by a chemical cross-linking reaction with a hydrazide compound. Therefore, if the ink of the present invention is used, both the active energy ray curing reaction and the chemical cross-linking reaction proceed while maintaining the ejection performance at a high level, and the cured film has excellent properties such as scratch resistance and water resistance. Image) can be formed.

The ink set of the present invention is an active energy ray-curable first water-based inkjet ink (first ink) containing a water-soluble monomer having a polymerizable group, and a second water-based inkjet ink (first ink) containing a hydrazide compound. The combination with the second ink) is included. The water-soluble monomer is a curable substance having a ketone structure. The water-soluble monomer in the first ink is a curable substance that is cured by an active energy ray curing reaction. Further, since the water-soluble monomer has a ketone structure in its molecular structure, it is also a curable substance that is cured by a chemical cross-linking reaction with the hydrazide compound in the second ink. Therefore, if the ink set of the present invention is used, both the active energy ray curing reaction and the chemical cross-linking reaction proceed while maintaining the ejection performance at a high level, and the cured film has excellent properties such as scratch resistance and water resistance. (Image) can be formed. Hereinafter, the ink of the present invention, and the first ink and the second ink constituting the ink set of the present invention are simply collectively referred to as "each ink".

(Water-soluble monomer)
The water-soluble monomer is a curable substance having a polymerizable group and a ketone structure. The molecular weight of the water-soluble monomer is preferably 5,000 or less, more preferably 3,000 or less, and particularly preferably 1,000 or less. By using a water-soluble monomer whose molecular weight is within the above range, it is possible to achieve both discharge performance and cured film characteristics at a higher level. The curable substance which is a water-soluble monomer is preferably an acrylamide-based compound. Further, the acrylamide compound is preferably at least one selected from the group consisting of diacetoneacrylamide and diacetonemethacrylamide. The term "water-soluble" as used herein means a property of being dissolved in water at 25 ° C. in an amount of 1% by mass or more.

The second ink constituting the ink set may contain a curable substance having a ketone structure. The content of the curable substance having a ketone structure in each ink is preferably 5% by mass or more and 80% by mass or less, and preferably 10% by mass or more and 60% by mass or less, based on the total mass of each ink. More preferred. By setting the content of the curable substance having a ketone structure in each ink within the above range, the ejection characteristics of the ink and the characteristics of the formed cured film can be further improved.

In addition to the curable substance having a ketone structure described above, a curable substance (other curable substance) other than the curable substance having a ketone structure can also be used. Examples of other curable substances include reactive functional compounds such as surfactants, curing accelerators, water-soluble auxiliaries, and viscosity modifiers. Specific examples of other curable substances include acryloylmorpholine, N-vinylpyrrolidone, acrylamide, hydroxyethylacrylamide, methylenebisacrylamide, monoacrylic acid ester of oligoethylene oxide, and monoacrylic acid ester of dibasic acid. be able to. Further, as commercially available products of other curable substances, FOM-3008 (water-soluble bifunctional acrylamide), FOM-3007 (water-soluble trifunctional acrylamide), FOM-3006 (water-soluble tetrafunctional acrylamide) are listed below under the trade names. , And FOM-3009 (water-soluble tetrafunctional acrylamide) (both manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and the like.

If the content of other curable substances in each ink is too high, the desired effect may be slightly insufficient. Therefore, the content of the other curable substance in each ink is preferably 0.01 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the curable substance having a ketone structure. Further, it is more preferably 0.1 part by mass or more and 75 parts by mass or less, and particularly preferably 1 part by mass or more and 50 parts by mass or less.

(Polymer initiator)
Each ink can contain a polymerization initiator. As the polymerization initiator, for example, a compound that produces an active species that initiates curing (polymerization) of a curable substance having a ketone structure by exchanging light can be used. Among them, since the curing reaction of a curable substance having a ketone structure proceeds remarkably by the generation of radicals, it is preferable to use a polymerization initiator that generates radicals by exchanging light.

The polymerization initiator is preferably a compound having a water-soluble group. Examples of the water-soluble group include a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a carboxylic acid base, a sulfonic acid base, a phosphoric acid base, an ether group, and an amide group. When the ink contains a coloring material having an anionic group, it is preferable to use a polymerization initiator having no ester group in order to suppress hydrolysis. Specific examples of the polymerization initiator include compounds represented by the following structural formulas (A) to (C) (polymerization initiators A to C). The polymerization initiator A is an example of an acylphosphine-based active energy ray polymerization initiator. The polymerization initiator B is an example of an α-hydroxyketone-based active energy ray polymerization initiator. Further, the polymerization initiator C is an example of a thioxanthone-based active energy ray polymerization initiator.

The content of the polymerization initiator in each ink is preferably 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less, based on the total mass of each ink. It is more preferably 0.01% by mass or more and 5% by mass or less. If the amount of the polymerization initiator is too large, the unreacted polymerization initiator tends to remain in the cured film, and the strength of the cured film may be slightly lowered.

It is also possible to use a polymerization initiator and a sensitizer in combination, or to use two or more kinds of polymerization initiators in combination. By using two or more kinds of polymerization initiators in combination, further generation of radicals is expected by utilizing light having a wavelength that cannot be effectively used by only one kind of polymerization initiator. The polymerization initiator may not be contained when the electron beam curing method using an electron beam as an active energy ray is adopted.

(Hydrazide compound)
The hydrazide compound is a component that functions as a cross-linking agent that cures a curable substance having a ketone structure, which is a water-soluble monomer, by a chemical cross-linking reaction. As the hydrazide compound, a polyfunctional hydrazide compound is preferable. Specific examples of the hydrazide compound include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutarate dihydrazide, adipic acid dihydrazide, pimelliate dihydrazide, suberic acid dihydrazide, azelinate dihydrazide, and sebacic acid dihydrazide. , Hexadecanediohydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4'-bisbenzenedihydrazide, 1,4-cyclohexanedihydrazide, tartaric acid dihydrazide, apple acid dihydrazide, iminodiacetate dihydrazide, N, N'-hexamethylenebis semi-hydrazide, itaconic acid dihydrazide, ethylenediamine tetraacetate tetrahydrazide, citrate trihydrazide, butanetricarbohydrazide, 1,2,3-benzenetrihydrazide, 1,4,5,8-naphthoic acid tetrahydrazide , Nitriloacetate trihydrazide, cyclohexanetricarboxylic acid trihydrazide, pyromellitic acid tetrahydrazide, and polyacrylic acid hydrazide (ie, N-aminopolyacrylamide), 1,3-bis (hydrazinocarboethyl) -5-isopropylhydrandin, etc. Can be mentioned. Further, a polyfunctional hydrazide derivative obtained by reacting these polyfunctional hydrazide compounds with ketones such as acetone and methyl ethyl ketone can also be used. As the hydrazide compound, adipic acid dihydrazide is preferable in terms of handleability and reactivity with a ketone structure (carbonyl group).

The content of the hydrazide compound in the ink of the present invention and in the second ink constituting the ink set of the present invention shall be 0.5% by mass or more and 50% by mass or less based on the total mass of each ink. It is preferable that it is 1% by mass or more and 30% by mass or less.

(solvent)
Each ink is a water-based ink containing water as a main solvent. The content of water in each ink is preferably 30% by mass or more, more preferably 50% by mass or more, based on the total mass of each ink.

Further, various organic solvents may be further contained for the purpose of improving various performances and as long as the original characteristics are not impaired. For example, certain organic solvents can impart non-volatility to the ink. Further, various organic solvents can be contained in each ink for the purpose of adjusting the viscosity, adjusting the surface tension, and imparting wettability to the recording medium.

Examples of the organic solvent include glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, and propylene glycol monomethyl ether; and monohydric alcohols such as methanol, ethanol, propanol, butanol, and pentanol. Can be mentioned.

The curable substance having a ketone structure may be contained in each ink in the form of an emulsified and dispersed emulsion without being completely dissolved in a solvent such as water. Moreover, the encapsulation technique may be applied.

(Color material)
Each ink can contain a coloring material. As the coloring material, pigments and dyes can be used. Examples of the pigment include magnetic fine particles such as magnetite and ferrite, inorganic pigments such as titanium black and carbon black, and organic pigments. Examples of carbon black include furnace black, lamp black, acetylene black, and channel black.

Organic pigments include azo pigments such as toluidine red and Hansa yellow; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; quinacridone pigments such as quinacridone red and quinacridone magenta; perylene pigments such as perylene red and perylene carlet; isoind Isoindolinone pigments such as linon yellow and isoindolinone orange; imidazolone pigments such as benzimidazolone yellow and benz imidazolone orange; pyranthron pigments such as pyranthron red and pyranthron orange; and the like can be mentioned.

When the organic pigment is indicated by a color index (CI) number, C.I. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 55, 74, 83, 86, 93, 97, 98, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185; C.I. I. Pigment Orange 16, 36, 43, 51, 55, 59, 61, 71; C.I. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 192, 202, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 272; C.I. I. Pigment Violet 19, 23, 29, 30, 37, 40, 50; C.I. I. Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64; C.I. I. Pigment Green 7, 36; C.I. I. Pigment Brown 23, 25, 26; and the like.

When the pigment is contained in each ink, it is preferable to use a pigment dispersion in which the pigment is uniformly dispersed in an aqueous medium. As the pigment dispersion, conventionally known pigment dispersions used in water-based gravure inks, pigment dispersions for water-based writing tools, ink jet inks, and the like can be preferably used. Of these, a pigment dispersion in which the pigment is stably dispersed in an aqueous medium due to an anionic group is preferable. Examples of the pigment dispersion in which the pigment is stably dispersed in the aqueous medium by the anionic group are JP-A-8-14382, JP-A-8-209048, JP-A-10-140065, and US Pat. No. 5,837. , 045, and US Pat. No. 5,851,280.

When a pigment is used, a dispersant may be used in combination. As the dispersant, a block polymer, a random polymer, a graft polymer and the like can be used. More specific dispersants include styrene-acrylic acid copolymer, styrene-maleic acid copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, and benzyl methacrylate-methacrylic acid copolymer. Coalescence and salts thereof can be mentioned. Further, as the pigment, a so-called self-dispersing pigment, which has an ionic group bonded to the particle surface of the pigment and can be dispersed in a medium without using a dispersant, can also be used.

As a dye, when indicated by a color index (CI) number, C.I. I. Acid Yellow 11, 17, 23, 25, 29, 42, 49, 61, 71; C.I. I. Direct Yellow 12, 24, 26, 44, 86, 87, 98, 100, 130, 132, 142; C.I. I. Acid Red 1, 6, 8, 32, 35, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 254, 256, 289, 315, 317; C.I. I. Direct Red 1, 4, 13, 17, 23, 28, 31, 62, 79, 81, 83, 89, 227, 240, 242, 243; C.I. I. Acid Blue 9, 22, 40, 59, 93, 102, 104, 113, 117, 120, 167, 229, 234, 254; C.I. I. Direct Blue 6, 22, 25, 71, 78, 86, 90, 106, 199; C.I. I. Direct black 7, 19, 51, 154, 174, 195; and the like can be mentioned.

Each ink can also be used as a so-called transparent ink that does not substantially contain a coloring material. When a transparent ink is used, a substantially colorless and transparent cured film can be formed. Applications of such transparent ink include, for example, an undercoat for imparting various aptitudes to a recording medium; a surface protection of an image recorded with ordinary ink; an overcoat for the purpose of decoration, glossing, etc. Can be mentioned. In addition, each ink may contain a colorless pigment, fine particles, or the like that are not intended for coloring in a dispersed state, depending on the intended use such as oxidation prevention and fading prevention. By containing these pigments, fine particles, and the like, various characteristics such as image quality, fastness, and workability (handleability) can be improved.

(others)
Each ink can also be used as a so-called transparent ink that does not substantially contain a coloring material. When a transparent ink is used, a substantially colorless and transparent cured film can be formed. Applications of such transparent ink include, for example, an undercoat for imparting various aptitudes to a recording medium; a surface protection of an image recorded with ordinary ink; an overcoat for the purpose of decoration, glossing, etc. Can be mentioned. Further, the ink may contain a colorless pigment, fine particles, or the like that are not intended for coloring in a dispersed state, depending on the application such as oxidation prevention and fading prevention. By containing these pigments, fine particles, and the like, various characteristics such as image quality, fastness, and workability (handleability) can be improved.

(others)
Each ink is a water-based ink for inkjet. Above all, it is suitable as an ink used in an inkjet recording apparatus provided with a recording head of a type that ejects ink by the action of heat energy. Further, each ink is suitable as a liquid contained in a cartridge (liquid cartridge) having a liquid accommodating portion or as a filling liquid of the liquid cartridge.

<Inkjet recording method>
The first inkjet recording method of the present invention includes a step of ejecting the above-mentioned water-based inkjet ink from an inkjet recording head and applying it to a recording medium to form a first uncured image. The first inkjet recording method further includes a step of curing the first uncured image by an active energy ray curing reaction and a chemical cross-linking reaction to form an image as a cured film.

Further, the second inkjet recording method of the present invention includes a step of forming a second uncured image. In this step, the first water-based inkjet ink and the second water-based inkjet ink constituting the above-mentioned water-based inkjet ink set are ejected from the inkjet recording head, respectively, and applied to the recording medium so that at least a part thereof overlaps. do. This forms a second uncured image. The second inkjet recording method further includes a step of curing the second uncured image by an active energy ray curing reaction and a chemical cross-linking reaction to form an image as a cured film.

As described above, the ink of the present invention and the first ink constituting the ink set of the present invention are curable substances that are cured by an active energy ray curing reaction by irradiation with active energy rays and a chemical cross-linking reaction by a hydrazide compound, respectively. Contains a water-soluble monomer that is. Therefore, the active energy ray curing is performed by irradiating the first uncured image formed by using the ink of the present invention and the second uncured image formed by using the ink set of the present invention with active energy rays. A chemical cross-linking reaction can occur together with the reaction. Thereby, the first uncured image and the second uncured image can be cured, respectively, to form an image which is a cured film having excellent cured film characteristics such as scratch resistance and water resistance.

Both the step of forming the first uncured image and the step of forming the second uncured image can be carried out according to the procedure of the conventional inkjet recording method. Conventional inkjet recording devices can be used to carry out these steps.

Further, both the step of curing the first uncured image to form an image and the step of curing the second uncured image to form an image are inkjet recordings provided with means for irradiating active energy rays. It can be carried out using the device. Hereinafter, the inkjet recording apparatus that can be used for the first inkjet recording method and the second inkjet recording method will be described.

<Inkjet recording device>
The inkjet recording device includes a recording head that ejects ink by an inkjet method. As the inkjet method, a method of applying thermal energy to eject ink, which can easily realize a high-density multi-orifice of a recording head and can record high-resolution and high-quality images at high speed, is preferable.

As a recording head of a method of applying thermal energy to eject ink, for example, the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796. Is preferable. Such a method can be applied to both the so-called on-demand type and the continuous type. In the case of the on-demand type, at least one that corresponds to the recorded information and gives a rapid temperature rise exceeding nucleate boiling to the electric heat converter arranged corresponding to the sheet or liquid passage in which the ink is held. It is preferable to apply one drive signal. As a result, heat energy is generated in the electric heat converter, film boiling is generated on the heat action surface of the recording head, and as a result, this drive signal is dealt with one-to-one, and bubbles can be formed in the ink. It is effective because it can be done.

Ink is ejected from the ejection port by the growth and contraction of bubbles to form at least one drop. When this drive signal has a pulse shape, bubbles grow and contract immediately and appropriately, and it is particularly preferable because ink can be ejected with good responsiveness. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. It is preferable to adopt the conditions relating to the temperature rise rate of the heat acting surface described in US Pat. No. 4,313,124.

As the configuration of the recording head, a combination configuration (linear liquid flow path or right-angled liquid flow path) of a discharge port, a liquid passage, and an electric heat converter as disclosed in each of the above-mentioned specifications is suitable. In addition, the configuration disclosed in US Pat. No. 4,558,333 and US Pat. No. 4,459,600 in which the heat acting portion is bent is also suitable. Further, the atmospheric communication type discharge method described in Japanese Patent No. 2962880, Japanese Patent No. 3246949, and Japanese Patent Application Laid-Open No. 11-188870 is also effective. In addition, for a plurality of electric heat converters, a configuration in which a common discharge hole is used as a discharge portion of the electric heat converter (Japanese Patent Laid-Open No. 59-123670, etc.) is also effective.

The following can be used as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording device. For example, it may be configured to satisfy the length by a combination of a plurality of recording heads as disclosed in the above specification, or may be configured as one integrally formed recording head. Furthermore, a replaceable chip-type recording head that can be electrically connected to the device body and supplied with ink from the device body by being attached to the recording device, and a cartridge provided integrally with the recording head. A type of recording head is also useful.

It is also preferable to add recovery means for the recording head, preliminary auxiliary means, and the like. Specific examples thereof include a recording head capping means, a cleaning means, a pressurizing or suction means, an electric heat converter, a heating element, a preheating means, a pre-discharging mode, and the like.

FIG. 1 is a perspective view schematically showing an example of the configuration of an inkjet recording device. The inkjet recording device shown in FIG. 1 is a recording device that uses a short serial head and employs a shuttle system for recording while scanning the head in the width direction of the recording medium. The carriage 100 is connected to the endless belt 101 and is movable along the guide shaft 102. The endless belt 101 is bridged between the pulleys 103 and 104. The drive shaft of the motor 105 is connected to the pulley 103. Therefore, the carriage 100 reciprocates along the guide shaft 102 in the main scanning direction of the arrow A by the rotational drive of the motor 105.

A recording head (not shown) in which a plurality of ink ejection nozzles are arranged side by side and an ink tank IT as a container for storing ink are mounted on the carriage 100. An active energy ray irradiation unit 20 is provided at at least one end of the carriage 100 in the main scanning direction A. Therefore, it is possible to irradiate the recording surface with the active energy ray from the active energy ray irradiation unit 20 immediately after applying the ink on the recording medium. Examples of the active energy ray include electron beam, ultraviolet ray, α ray, β ray, γ ray, X-ray and the like. Of these, ultraviolet rays are preferable.

The recording head is formed with a plurality of ink ejection ports arranged in the transport direction of the paper P (the sub-scanning direction of the arrow B) on the ejection port surface facing the paper P as a recording medium. The recording head is provided with an ink passage that communicates with each of the plurality of ejection ports. An electric heat converter that generates heat energy for ejecting ink is provided corresponding to each ink path.

The electric heat converter generates heat by applying an electric pulse corresponding to the drive data, causes the ink to boil the film by the heat, and discharges the ink from the ejection port with the generation of bubbles. A common liquid chamber is communicated with each ink passage in common, and the common liquid chamber is connected to the ink tank IT.

The inkjet recording device shown in FIG. 1 is provided with a linear encoder 106 for detecting the moving position of the carriage 100. That is, slits are formed in the linear scale 107 provided along the moving direction of the carriage 100 at equal intervals of, for example, 1,200 in 1 inch. On the other hand, on the carriage 100 side, for example, a slit detection system 108 having a light emitting unit and a light receiving sensor and a signal processing circuit are provided. Therefore, the linear encoder 106 outputs the ejection timing signal indicating the ink ejection timing and the information on the moving position of the carriage 100 according to the movement of the carriage 100. By ejecting ink each time the slit of the linear scale 107 is detected, an image having a resolution of 1,200 dpi can be recorded in the main scanning direction.

The paper P as a recording medium is intermittently conveyed in the sub-scanning direction of the arrow B orthogonal to the operation direction of the carriage 100. The paper P is supported by a pair of roller units 109 and 110 on the upstream side in the transport direction and a pair of roller units 111 and 112 on the downstream side in the transport direction. Then, a constant tension is applied, and the recording head 10 is conveyed in a state where the flatness is ensured. The driving force for the roller units 111 and 112 is supplied from a paper transfer motor (not shown).

In the inkjet recording apparatus shown in FIG. 1, an image is recorded on the entire paper P by alternately repeating recording of a width corresponding to the arrangement width of the ejection port of the recording head and feeding of the paper P while moving the carriage 100. can do. The carriage 100 stops at the home position as needed at the start of recording or during recording. At this home position, a cap member 113 for capping the discharge surface side of each recording head is provided. A suction recovery means (not shown) for forcibly absorbing ink from the ejection port to prevent clogging of the ejection port is connected to the cap member 113.

In addition to the shuttle method described above, there is a line method using a line head in which recording elements are arranged corresponding to the entire area of one side of the recording medium. In the line method, images can be recorded on the entire surface of the recording medium by scanning the recording medium in a direction orthogonal to the arrangement direction of the recording elements. This eliminates the need for a transport system such as a carriage that scans the short head. Further, since the movement of the carriage and the complicated scanning control between the recording medium and the recording medium are not required and only the recording medium is moved, the recording speed can be increased as compared with the shuttle method.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. Items described as "part" and "%" regarding the amount of components are based on mass unless otherwise specified.

<Manufacturing of ink (1)>
(Ink 1)
Pigment (CI Pigment Red 122) and dispersant (random copolymer of styrene / acrylic acid / ethyl acrylate, weight average molecular weight = 3,500, acid value = 150 mgKOH / g) are mixed and then dispersed in a bead mill. Processed. As a result, a magenta pigment dispersion having a pigment solid content of 10% and a pigment: dispersant (mass ratio) = 3: 1 was obtained. Then, each component shown below was mixed and sufficiently stirred, and then pressure-filtered with a filter having a pore size of 0.5 μm to obtain ink 1. The pH of the obtained ink 1 was 9. Among the components shown below, "acetylenol E100" is a trade name of a nonionic surfactant (ethylene oxide adduct of acetylene glycol) manufactured by Kawaken Fine Chemicals. Further, "FOM-3006" is a trade name of a curable substance (water-soluble tetrafunctional acrylamide) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[Composition of ink 1]
・ Magenta pigment dispersion 40%
・ Diacetone acrylamide 10%
・ FOM-3006 5%
-Polymer initiator A 2%
・ Adipic acid dihydrazide 1%
・ Acetyrenol E100 1%
・ Triethanolamine 0.5%
・ Ion-exchanged water 40.5%

(Ink 6)
Ink 6 was prepared in the same manner as ink 1 described above, except that the same amount of ion-exchanged water was used instead of adipic acid dihydrazide.

(Ink 10)
Ink 10 was prepared in the same manner as in ink 1 described above, except that the same amount of carbodiimide compound (trade name “Carbodilite SV-02”, manufactured by Nisshinbo Chemical Co., Ltd.) was used instead of adipic acid dihydrazide.

(Inks 2, 3, 7, and 11)
Inks 2, 3, 7, and 11 were prepared in the same manner as ink 1 described above, except that the formulations were as shown below. Among the components shown below, "FOM-3008" is a trade name of a curable substance (water-soluble bifunctional acrylamide) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[Composition of ink 2]
・ Magenta pigment dispersion 40%
・ Diacetone Acrylamide 25%
・ FOM-3008 5%
-Polymer initiator A 3%
・ Acetyrenol E100 1%
・ Ion-exchanged water 26%

[Composition of ink 3]
・ FOM-3008 20%
-Polymerization photoinitiator A 2%
・ Adipic acid dihydrazide 6%
・ Carbohydrazide 14%
・ Acetyrenol E100 1%
・ Ion-exchanged water 57%

[Composition of ink 7]
・ FOM-3008 20%
-Polymer initiator A 2%
・ Acetyrenol E100 1%
・ Ion-exchanged water 77%
[Composition of ink 11]
・ FOM-3008 20%
-Polymerization photoinitiator A 2%
・ Magnesium nitrate 15%
・ Acetyrenol E100 1%
・ Ion-exchanged water 62%

<Recording of images (formation of cured film) (1)>
We have prepared an on-demand recording device (trade name "Pro-10", manufactured by Canon) that applies heat energy according to the recording signal to the ink and ejects it. A UV-LED irradiation device (trade name "M30", manufactured by Ushio, Inc., 395 nm) mounted on a portion adjacent to the recording head of this recording device was used as an inkjet recording device. Specifically, as shown in FIG. 2, the UV-LED irradiation device 30 is mounted at a position adjacent to the mounting position (10) (GY cartridge mounting position) in the ink cartridge mounting position 50 of the recording head 10. The integrated irradiation energy of the active energy rays (ultraviolet rays) under the drawing condition of one pass in one direction was 2,000 mJ / cm2. In this inkjet recording device, the recording duty of an image recorded under the condition that the resolution is 600 dpi × 600 dpi and 8 drops of 3.8 ng of ink is applied to a unit area of 1/600 inch × 1/600 inch is 100%. Define. Using this inkjet recording device, an image was recorded on a PET film (trade name "Easy Adhesive White PET", manufactured by Teijin).

(Example 1)
The ink cartridge filled with ink 1 was mounted at the mounting position (3) (Y cartridge mounting position) shown in FIG. A solid image of 1,200 dpi and 100% duty was recorded in one pass (drawing condition 1), and then UV irradiation was continuously performed to record an image (cured film).

(Comparative Example 1)
An image (cured film) was recorded in the same manner as in Example 1 described above, except that the ink 6 was used instead of the ink 1.

(Comparative Example 2)
An image (cured film) was recorded in the same manner as in Example 1 described above, except that the ink 10 was used instead of the ink 1.

(Example 2)
The ink cartridge filled with ink 2 was mounted at the mounting position (3) (Y cartridge mounting position) shown in FIG. Further, the ink cartridge filled with the ink 3 was mounted at the mounting position (6) (PBK cartridge mounting position) shown in FIG. Ink 2 is ejected from the cartridge at the mounting position (3) with a discharge rate of 90% duty (1 pass), and ink 3 is continuously ejected from the cartridge at the mounting position (6) with a discharge rate of 10% duty (1 pass). Discharged. As a result, a solid image of 1,200 dpi and 100% duty was recorded (drawing condition 2). Then, UV irradiation was continuously performed and an image (cured film) was recorded. The ratio (mass ratio) of the curable substance having a ketone structure to the hydrazide compound was: curable substance: hydrazide compound = 22.5: 2.

(Example 3)
The image is the same as in Example 2 above, except that the discharge amount from the cartridge at the mounting position (3) is set to 80% duty and the discharge amount from the cartridge at the mounting position (6) is set to 20% duty. (Cursed film) was recorded. The ratio (mass ratio) of the curable substance having a ketone structure to the hydrazide compound was: curable substance: hydrazide compound = 5: 1.

(Comparative Example 3)
An image (cured film) was recorded in the same manner as in Example 2 described above, except that the ink 7 was used instead of the ink 3.
(Comparative Example 4)
An image (cured film) was recorded in the same manner as in Example 2 described above, except that the ink 11 was used instead of the ink 3.

(Example 4)
The ink cartridge filled with the ink 3 was mounted at the mounting position (3) (Y cartridge mounting position) shown in FIG. Further, the ink cartridge filled with the ink 2 was mounted at the mounting position (6) (PBK cartridge mounting position) shown in FIG.
Ink 3 is ejected from the cartridge at the mounting position (3) with a discharge rate of 20% duty (1 pass), and ink 2 is continuously ejected from the cartridge at the mounting position (6) with a discharge rate of 80% duty (1 pass). Discharged. As a result, a solid image of 1,200 dpi and 100% duty was recorded (drawing condition 3). Then, UV irradiation was continuously performed and an image (cured film) was recorded.

<Manufacturing of ink (2)>
(Inks 8 and 9)
Inks 8 and 9 were prepared according to the procedure shown below, with reference to the method described in "Example 1" of Patent Document 3 (Japanese Patent No. 6015913).

[Synthesis of Comparative Compound 1]
Put 30 parts of diacetone acrylamide (diacetone acrylamide), 70 parts of methacrylic acid, and 50 parts of ethanol in a flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, and after replacing the inside of the system with nitrogen, the system The internal temperature was raised to 80 ° C. 0.5 part of 2,2'-azoisobutyrylonitrile was added with a dropping funnel to initiate polymerization, and the polymerization was carried out for 6 hours. After the polymerization, ethanol vapor was blown into the mixture to obtain a 50% ethanol solution of the diacetone acrylamide-methacrylic acid copolymer. After washing with ethanol, it was dried to obtain a diacetone acrylamide-methacrylic acid copolymer (Comparative Compound 1, Diacetone Acrylamide: Methacrylic Acid = 30: 70). Distilled water was added and sodium hydroxide was added to obtain a 20% aqueous solution (pH 7) of Comparative Compound 1.

[Manufacturing of pigment dispersion]
A magenta pigment dispersion having a pigment solid content of 10% and a pigment: dispersant (mass ratio) = 3: 1 as in the case of the ink 1 described above, except that the comparative compound 1 was used as the dispersion resin. Got Then, inks 8 and 9 were prepared in the same manner as in the above-mentioned ink 1 except that the obtained magenta pigment dispersion liquid was used and the composition shown below was used.

[Composition of ink 8]
・ Magenta pigment dispersion 40%
・ Glycerin 20%
・ Acetylenol E-100 1%
・ Ion-exchanged water 39%

[Composition of ink 9]
・ Magenta pigment dispersion 40%
・ Glycerin 5.5%
・ Acetylenol E-100 1%
・ Ion-exchanged water 53.5%

<Recording of images (formation of cured film) (2)>
(Comparative Example 5)
An image (cured film) was recorded in the same manner as in Example 1 described above, except that the ink 8 was used instead of the ink 1 and the UV irradiation was not performed.

(Comparative Example 6)
An image (cured film) was recorded in the same manner as in Example 1 described above, except that the ink 9 was used instead of the ink 1 and UV irradiation was not performed.

<Manufacturing of ink (3)>
(Inks 4 and 5)
C. I. A black pigment dispersion having a pigment solid content of 10% was obtained in the same manner as in the case of Ink 1 described above, except that carbon black was used as a pigment instead of Pigment Red 122. Then, inks 4 and 5 were prepared in the same manner as ink 1 described above, except that the obtained black pigment dispersion was used and the composition shown below was used.

[Composition of ink 4]
・ Black pigment dispersion 30%
・ Diacetone Acrylamide 25%
・ FOM-3008 5%
-Polymer initiator A 5%
・ Acetyrenol E100 1%
・ Ion-exchanged water 34%

[Composition of ink 5]
・ Hydroxyethyl acrylamide 15%
・ Diacetone acrylamide 10%
・ Methylene bisacrylamide 5%
・ Polymerization photoinitiator A 3%
・ Adipic acid dihydrazide 2%
・ Acetyrenol E100 1%
・ Ion-exchanged water 64%

<Recording of images (formation of cured film) (3)>
(Example 5)
The ink cartridge filled with the ink 4 was mounted at the mounting position (3) (Y cartridge mounting position) shown in FIG. Further, the ink cartridge filled with the ink 5 was mounted at the mounting position (6) (PBK cartridge mounting position) shown in FIG.
Ink 4 was ejected from the cartridge at the mounting position (3) with a discharge amount of 100% duty (1 pass) to record a solid image, and then UV irradiation was continuously performed. Next, after the ink 5 was ejected from the cartridge at the mounting position (6) with an ejection amount of 100% duty (1 pass), UV irradiation was continuously performed and an image (cured film) was recorded. The ratio (mass ratio) of the curable substance having a ketone structure to the hydrazide compound was: curable substance: hydrazide compound = 35: 2.

<Evaluation>
(1) Discharge performance (basic discharge)
An ink cartridge filled with each ink was attached to an inkjet recording device. A suction recovery operation was performed, and after leaving it for 1 minute, a solid image of 1,200 dpi and 100% duty was recorded in one pass. The state of the recorded solid image was visually confirmed, and the basic ejection property was evaluated according to the evaluation criteria shown below. The results are shown in Table 1.
A: It was a uniform solid image.
B: Less than 10% of the writing part was faint.
C: The faintness of the writing part was 10% or more and less than 20%.
D: The faintness of the writing part was 20% or more.

(Stability left unattended)
An ink cartridge filled with each ink was attached to an inkjet recording device. A suction recovery operation was performed, and after leaving it for 3 days, a solid image of 1,200 dpi and 100% duty was recorded in one pass. The state of the recorded solid image was visually confirmed, and the basic ejection property was evaluated according to the evaluation criteria shown below. The results are shown in Table 1.
A: It was a uniform solid image.
B: Less than 10% of the writing part was faint.
C: The faintness of the writing part was 10% or more and less than 20%.
D: The faintness of the writing part was 20% or more.

(2) Hardened film characteristics (scratch resistance)
One day after the image (cured film) was formed, a pencil hardness test based on JIS K 5600-5-4: 1999 was carried out, and the scratch resistance of the cured film was evaluated according to the evaluation criteria shown below. The results are shown in Table 1.
A: No scratches or scrapes were observed with a pencil hardness of 2H.
B: No scratches or peeling were observed when the pencil hardness was H or less.
C: No scratches or peeling were observed when the pencil hardness was HB or less and B or more.
D: Scratches and peeling were observed even when the pencil hardness was 2B or less.

(water resistant)
One day after the image (cured film) was formed, 0.2 mL of ion-exchanged water was dropped onto the cured film, and one minute later, Sylbon paper was placed. After pulling the Sylbon paper under a load of 40 g / cm ² , the non-recording portion (white background portion) and the Sylbon paper were visually observed, and the water resistance of the cured film was evaluated according to the evaluation criteria shown below. The results are shown in Table 1.
A: The area of the area where no stain was found was 90% or more of the area of the Sylbon paper.
B: The area of the area where no stain was found was 70% or more of the area of the Sylbon paper.
C: The area of the area where no stain was found was 50% or more of the area of the Sylbon paper.
D: The area of the area where no stain was found was less than 20% of the area of the Sylbon paper.

Claims (8)

An active energy ray-curable water-based inkjet ink containing a water-soluble monomer having a polymerizable group.
Further containing a hydrazide compound,
A water-based inkjet ink, wherein the water-soluble monomer is a curable substance having a ketone structure. The water-based inkjet ink according to claim 1, wherein the curable substance is an acrylamide-based compound. The water-based inkjet ink according to claim 2, wherein the acrylamide-based compound is at least one selected from the group consisting of diacetone acrylamide and diacetone methacrylamide. An active energy ray-curable first water-based inkjet ink containing a water-soluble monomer having a polymerizable group, and
Including a combination with a second aqueous inkjet ink containing a hydrazide compound,
A water-based inkjet ink set, wherein the water-soluble monomer is a curable substance having a ketone structure. The water-based inkjet ink set according to claim 4, wherein the curable substance is an acrylamide-based compound. The aqueous inkjet ink set according to claim 5, wherein the acrylamide compound is at least one selected from the group consisting of diacetone acrylamide and diacetone methacrylamide. A step of ejecting the water-based inkjet ink according to any one of claims 1 to 3 from an inkjet recording head and applying the ink to a recording medium to form a first uncured image.
A step of curing the first uncured image by an active energy ray curing reaction and a chemical cross-linking reaction to form an image, and a step of forming an image.
An inkjet recording method characterized by having. The first water-based inkjet ink and the second water-based inkjet ink constituting the water-based inkjet ink set according to any one of claims 4 to 6 are ejected from the inkjet recording head, respectively, and at least a part thereof is overlapped. The process of forming a second uncured image by applying it to a recording medium so as to be performed.
A step of curing the second uncured image by an active energy ray curing reaction and a chemical cross-linking reaction to form an image, and a step of forming an image.
An inkjet recording method characterized by having.

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