JP2018083299A - Image forming method, inkjet image forming apparatus, and inkjet image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method capable of reducing tackiness and fingerprint adhesion to a base-material surface while enhancing scratch resistance and water resistance of an image without excessive heating by a reaction between a crosslinking agent and a resin.SOLUTION: The present invention relates to an image forming method, including: causing droplets of a water-based ink to be discharged from an inkjet head and the droplets to land on a region on a base material; applying a first treatment liquid containing a crosslinking agent onto the base material; and applying a second treatment liquid containing a resin having a reactive functional group or structure which reacts with the crosslinking agent onto the base material. Both of the first treatment liquid and the second treatment liquid are applied to a region wider than a region on the base material on which droplets of the water-based ink land.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming method, an inkjet image forming apparatus, and an inkjet image forming system.

  Inkjet methods can be used to produce images easily and inexpensively, and thus have been applied to various printing fields including special printing such as photographs, various printing, marking, and color filters.

  Ink-jet inks used in the ink-jet method include water-based inks composed of water and a small amount of organic solvents, non-aqueous inks that contain organic solvents but do not substantially contain water, and hot inks that heat and melt solid inks at room temperature. There are a plurality of types, such as melt ink and actinic ray curable ink that is cured by irradiation with actinic rays after printing, and these inks are properly used depending on the application. Among these, water-based inks are widely used for home printers because they generally have low odor and high safety.

  In order to improve the scratch resistance and water resistance of an image formed using an aqueous ink, a method of adding an aqueous dispersion resin to the aqueous ink is known. When this water-based ink is landed on the substrate and then the substrate is heated, the aqueous dispersion resin is formed into a film, and an image having high scratch resistance and high water resistance is obtained. However, it is difficult to form an image by the above method on a substrate that is easily deformed by heating.

  Therefore, an image is formed using the aqueous ink on a substrate pre-treated with a processing liquid containing a crosslinking agent that crosslinks the aqueous dispersion resin, or the image formed using the aqueous ink is overcoated with the processing liquid. Thus, a technology has been developed that can form a film by cross-linking a resin in a substrate state even when heating or non-heating at a lower temperature (Patent Document 1, Patent Document 2, etc.). In order to prevent the aqueous dispersion resin and the crosslinking agent from reacting before image formation, one of the aqueous dispersion resin and the crosslinking agent is usually added to the water-based ink and the other is added to the treatment liquid.

  With regard to the precoat or overcoat, Patent Document 1 describes that it can be applied to a substrate by ejection from an inkjet head, spraying, application by a roller, or the like. In addition, the above-mentioned precoat or overcoat is described in Patent Document 2 that it may be applied only to a solid image portion or the like, or may be applied to the entire surface of the substrate.

  It is known that when a resin and a crosslinking agent that crosslinks the resin are mixed in the same treatment liquid, the resin and the crosslinking agent react immediately after mixing (Patent Document 3, Patent Document 4, etc.) ).

International Publication No. 2003/43825 Japanese Patent Laying-Open No. 2015-4503 JP 7-26226 A JP-A-2014-14106

  From the viewpoint of further improving the scratch resistance and water resistance of the formed image, it is desirable that the water-based ink droplets land on the region to which the precoat or overcoat is applied.

  However, in the inkjet method, very small droplets are ejected and discretely landed on the substrate, so that it is not possible to accurately land the ejected droplets on the originally planned droplet landing positions. difficult. For this reason, when both the precoat or overcoat droplets and the water-based ink droplets are ejected by the ink jet method, the positions where they both land are likely to shift. In addition, since the transport path is usually designed wider than the base material, the base material may meander during the transport, causing the base material position to shift. When the position of the substrate is shifted, a shift between the position where the precoat or overcoat lands and the position where the ink lands is more likely to occur.

  On the other hand, if the precoat or overcoat is applied by spraying or rollers, or applied to the entire surface of the substrate, water-based ink droplets are landed on the area where the precoat or overcoat is applied. It becomes easy. However, in this method, a region where the water-based ink droplets have not landed (hereinafter, also referred to as “image non-forming region”) is formed widely even though the precoat or overcoat is applied. Thus, an unreacted cross-linking agent remains in the non-image forming area. From the viewpoint of suppressing the stickiness on the surface of the base material or reducing the adhesion of fingerprints to the surface of the base material, it is desirable that the amount of the unreacted crosslinking agent is smaller.

  The present invention has been made in view of the above problems, and improves adhesion and adhesion of fingerprints to the surface of a substrate while improving the scratch resistance and water resistance of an image without excessive heating due to the reaction between a crosslinking agent and a resin. It is an object of the present invention to provide an image forming method capable of lowering an image quality, and an ink jet image forming apparatus and an ink jet image forming system capable of executing such an image forming method.

The above-described problems of the present invention are solved by the following means.
[1] A step of ejecting water-based ink droplets from an inkjet head to land on a region on a substrate, a step of applying a first treatment liquid containing a crosslinking agent on the substrate, and the crosslinking agent A step of applying a second treatment liquid containing a resin having a reactive functional group or structure that reacts with the substrate onto the substrate, and the first treatment liquid and the second treatment liquid are either And an image forming method in which the water-based ink droplets are applied to an area wider than an area on the substrate on which the water-based ink droplets are landed.
[2] The image forming method according to [1], wherein after the second processing liquid is applied, landing of droplets of the water-based ink and application of the first processing liquid are performed.
[3] The image forming method according to [1] or [2], wherein the application of the second processing liquid, the landing of the droplets of the water-based ink, and the application of the first processing liquid are performed in this order. .
[4] The region to which the second treatment liquid is applied is a region that substantially coincides with the region to which the first treatment liquid is applied, or is a wider region. [1] to [3] The image forming method according to any one of the above.
[5] The crosslinking agent according to [1] to [4], wherein the crosslinking agent is a compound selected from the group consisting of (poly) carbodiimide compounds, (poly) isocyanate compounds, epoxy compounds, silyl compounds, oxazoline compounds, and hydrazine compounds. The image forming method according to any one of the above.
[6] The reactive functional group or structure is any one of [1] to [5], which is a functional group or structure selected from the group consisting of a carboxyl group, a polyol structure, a urethane bond, and an amide group. Image forming method.
[7] The image forming method according to any one of [1] to [6], wherein the substrate is a film.
[8] An inkjet head that discharges water-based ink droplets to land on a region on a substrate, a first treatment liquid application unit that applies a first treatment liquid containing a crosslinking agent onto the substrate, and the crosslinking An inkjet image forming apparatus comprising: a second treatment liquid application unit that applies a second treatment liquid containing a resin having a reactive functional group or structure that reacts with an agent on the substrate.
[9] An inkjet image forming system comprising: the inkjet image forming apparatus according to [8]; and a drying device that dries a substrate on which an image is formed by the inkjet image forming apparatus.

  According to the present invention, there is provided an image forming method capable of reducing stickiness and fingerprint adhesion to a substrate surface while enhancing the scratch resistance and water resistance of an image without excessive heating due to the reaction between a crosslinking agent and a resin. In addition, an inkjet image forming apparatus and an inkjet image forming system capable of performing such an image forming method are provided.

FIG. 1A is a schematic diagram illustrating a state in which droplets of a treatment liquid containing a crosslinking agent and aqueous ink droplets containing a crosslinking resin are discharged from an inkjet head and landed on a substrate. FIG. 1B is a schematic diagram showing a state in which droplets of a water-based ink containing a crosslinking resin are ejected from an inkjet head and landed on the substrate after a treatment liquid containing a crosslinking agent is applied on the substrate. is there. FIG. 2 is a schematic diagram showing the application of the first treatment liquid, the application of the second treatment liquid, and the landing of the water-based ink droplets in the present invention. FIG. 3 is a schematic diagram showing an outline of the inkjet image forming apparatus according to the present invention. FIG. 4 is a schematic diagram showing an outline of the ink jet recording system according to the present invention.

  The present inventor diligently studied the above-mentioned problems and forms an image using two liquids of normal ink and processing liquid, and is also referred to as a processing liquid containing a crosslinking agent (hereinafter simply referred to as “first processing liquid”). ), And a resin having a reactive functional group or structure that reacts with the crosslinking agent (hereinafter, the functional group or structure is also simply referred to as “crosslinking group”, and the resin is also simply referred to as “crosslinking resin”). A treatment liquid (hereinafter, also simply referred to as “second treatment liquid”) is provided separately from the water-based ink, and both of the first treatment liquid and the second treatment liquid are landed by droplets of the water-based ink. The present inventors have conceived an image forming method in which a wider area than an area on a substrate to be applied is applied.

  The above-mentioned “region on the base material on which the water-based ink droplets are landed” refers to a region on the base material targeted for landing when water-based ink is ejected from the inkjet head. Is the area that will be landed. By making the area to which the first treatment liquid and the second treatment liquid are applied wider than the area where the water-based ink droplets are landed, the displacement of the landing positions of the ejected liquid droplets and the conveyance are reduced. Even when the position of the base material in the medium is displaced, water-based ink droplets can be reliably landed on the region to which the cross-linking agent and the cross-linking resin are applied. Therefore, the scratch resistance and water resistance of the image formed by the landed water-based ink can be easily improved. On the other hand, by including the crosslinking agent and the crosslinking resin in the first treatment liquid and the second treatment liquid, respectively, and separately imparting them on the substrate, the region to which the crosslinking agent and the crosslinking resin are imparted, It can be easily adjusted according to the area where the water-based ink droplets land.

  FIG. 1A shows that after a droplet 12 of a treatment liquid containing a crosslinking agent is discharged from an inkjet head and landed on a substrate, a droplet 14 of a water-based ink containing a crosslinked resin is placed at the same position from another inkjet head. It is a schematic diagram which shows a mode when it discharges | controls so that it may land on, and it makes it land on a base material. As shown in FIG. 1A, even if the droplet 14 of the water-based ink is made to land at the same position as the droplet 12 of the processing liquid, the deviation of the landing position of the discharged droplet, the position of the substrate being conveyed, It is difficult to cause the water-based ink droplet 14 to land at the same position as the treatment liquid droplet 12 due to misalignment or the like. At this time, the cross-linked resin is cross-linked at the position where the water-based ink droplets 14 land, and the film is not formed, so that the scratch resistance and water resistance of the formed image may be difficult to increase.

  FIG. 1B shows that after applying a treatment liquid 22 containing a cross-linking agent to a wider area, water-based ink droplets 24 containing a cross-linking resin are discharged from the inkjet head so as to land in the area. It is a schematic diagram which shows a mode when it is made to land on a base material. As shown in FIG. 1B, the water-based ink droplets 24 can land in the region to which the treatment liquid 22 has been applied, but the water-based ink droplets 24 have not landed despite the treatment liquid 22 being applied. A non-image forming area is formed widely, and an unreacted crosslinking agent or the like contained in the non-image forming area causes stickiness on the surface of the base material, or fingerprints are likely to adhere to the surface of the base material.

  On the other hand, in the present invention, as shown in FIG. 2, the application of the first treatment liquid 32 and the application of the second treatment liquid 36 are separate steps from the landing of the water-based ink, Both the treatment liquid 32 and the second treatment liquid 36 are applied to an area wider than the area on the substrate on which the water-based ink droplets 34 land. As a result, the water-based ink droplet 34 is landed in the region to which the first processing liquid and the second processing liquid are applied, and the first processing liquid 32 and the second processing liquid 36 are discharged. It is easy to adjust the area to be given to substantially the same range. As a result, the cross-linked resin is cross-linked at the position where the water-based ink landed to form a film, so that the scratch resistance and water resistance of the formed image are easily increased, and unreacted cross-linking agent remains on the substrate. Since it is difficult, stickiness on the surface of the substrate is less likely to occur, and fingerprints are less likely to adhere to the surface of the substrate. In addition, since the unreacted crosslinking agent does not easily remain on the substrate, it is possible to suppress a decrease in tactile sensation, yellowing during image storage, deterioration of surface gloss, and the like.

  In FIG. 2, the application of the second treatment liquid 36, the landing of the water-based ink droplet 34, and the application of the first treatment liquid 32 are performed in this order. The order is not particularly limited, and may be performed in any order.

  When the crosslinking agent and the crosslinking resin are mixed in the same processing solution, the crosslinking agent and the crosslinking resin react immediately after mixing, and therefore it is necessary to use up the processing solution immediately after the preparation. In addition, the viscosity and surface tension of the treatment liquid containing the cross-linking agent and the cross-linking resin change with time, and when the cross-linking agent and the cross-linking resin react with each other, the effect of the pigment flocculant described later also changes. For this reason, when images are formed continuously, there is a possibility that the color tone and sharpness of the image may change between the initial and late stages of image formation. On the other hand, it is possible to stably form an image with high image quality by using different processing solutions for the cross-linking agent and the cross-linking resin.

  Hereinafter, the present invention will be described by way of exemplary embodiments, but the present invention is not limited to the following embodiments.

1. Image Forming Method The image forming method of the present invention includes a step of discharging water-based ink from an inkjet head to land on a region on a substrate, a step of applying a first treatment liquid containing a crosslinking agent on the substrate, and Providing a second treatment liquid containing a resin having a reactive functional group or structure that reacts with the crosslinking agent on the substrate. At this time, the first treatment liquid and the second treatment liquid are both applied to a wider area than the area on the substrate on which the water-based ink is landed.

  The application amounts of the first treatment liquid and the second treatment liquid are not particularly limited. However, the coating layer formed by applying the first treatment liquid and the second treatment liquid and drying it has a thickness of 0. It is preferable to adjust so that it may become 1 micrometer or more and 6.0 micrometers or less. When the film thickness of the coating layer is 0.1 μm or more, the scratch resistance formed by the crosslinked resin is sufficiently increased. When the film thickness of the coating layer is 6.0 μm or less, the unevenness of the formed image can be made harder to feel.

  The image forming method of the present invention can be performed on a film stored in a roll shape. At this time, the image forming method of the present invention includes a step of developing a roll-shaped film into a flat shape before each of the above steps, and a step of winding the film into a roll after each of the above steps.

1-1. Step of landing water-based ink droplets In this step, water-based ink droplets are ejected from an inkjet head to land on a region on a substrate.

  The ejection method from the ink jet head may be either an on-demand method or a continuous method. On-demand inkjet heads include electro-mechanical conversion systems such as single cavity type, double cavity type, bender type, piston type, shear mode type and shared wall type, and thermal inkjet type and bubble jet. Any of electric-thermal conversion methods such as Canon Inc. (registered trademark) type may be used.

  Among these, the ink jet head is preferably a piezo ink jet head having a nozzle diameter of 30 μm or less from the viewpoint of increasing the types of ink that can be used and making the image quality more precise.

  From the viewpoint of recording an image at a high speed, the ink jet recording method is preferably a one-pass type. The one-pass type ink jet recording method is a method in which when a substrate passes under one ink jet head unit, water-based ink droplets are ejected and landed on all pixels where dots should be formed in one pass. Means method.

  From the viewpoint of recording an image by a one-pass ink jet recording method, the ink jet head is preferably a line head type. The line head type ink jet head means an ink jet head having a length equal to or greater than the width of the printing range in a direction orthogonal to the substrate transport direction. The line head type inkjet head may be composed of a single head having a length longer than the width of the printing range, or a combination of a plurality of heads so as to be longer than the width of the printing range. But you can. From the viewpoint of higher definition of the formed image, the plurality of heads form a plurality of rows in a direction perpendicular to the conveyance direction of the substrate, and the heads in each row are nozzles for the substrate. It is preferable to arrange so that the emission positions are different.

[Water-based ink]
The water-based ink may be an ink containing a coloring material and containing an amount of water larger than an unavoidable amount. The water-based ink may further contain an organic solvent. The water-based ink may contain other components that are usually used in water-based inks for inkjet printing, as long as the effects of the present invention are not significantly impaired.

  Water-based inks are preferable because they are safer to the human body than non-aqueous inks, hot melt inks, actinic ray curable inks, and the like. Since water has the highest vapor pressure among the solvents usually used in water-based inks, in the image forming method of the present invention, the larger the amount of water contained in the water-based ink, the easier the substrate is dried. From the above viewpoint, the water-based ink preferably contains 60% by mass or more of water with respect to the total mass of the ink.

1-1-1. Coloring material The coloring material may be a pigment or a dye.

  From the viewpoint of obtaining an image having good weather resistance, the color material is preferably a pigment. The pigment can be selected from, for example, a yellow pigment, a red or magenta pigment, a blue or cyan pigment, and a black pigment depending on the color of the image to be formed.

  The pigment can be a known pigment for recording an image by being contained in water-based ink. The pigment may be a water-dispersible pigment or a solvent-dispersible pigment that is dispersed by adding a solvent to the water-based ink. Examples of pigments include organic pigments including insoluble pigments and lake pigments, and inorganic pigments including carbon black. Only one kind of these pigments may be contained, or two or more kinds may be contained in combination.

  Examples of insoluble pigments include azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine and diketo. Pigments having a structure such as pyrrolopyrrole are included.

  Examples of preferred pigments include pigments represented by the following color index.

  Examples of pigments exhibiting magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, and C.I. I. Pigment Red 222 is included.

  Examples of pigments exhibiting orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 94, and C.I. I. Pigment Yellow 138 is included.

  Examples of pigments exhibiting green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, and C.I. I. Pigment Green 7 is included.

  Examples of pigments exhibiting black include C.I. I. Pigment black 1, C.I. I. Pigment black 6, and C.I. I. Pigment Black 7 is included.

  When displaying an intermediate color on the image, the water-based ink may contain a pigment for the special color ink. Examples of pigments for spot color inks include C.I. I. Pigment red 177, C.I. I. Pigment red 194, C.I. I. Pigment red 209, and C.I. I. Pigment red 224, C.I. I. Pigment orange 43, C.I. I. Bat Violet 3, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, and C.I. I. Pigment violet 37, C.I. I. Pigment green 7, C.I. I. Pigment green 36, and C.I. I. Pigment Blue 15: 6 is included.

  The pigment is preferably dispersed together with a dispersant and other necessary additives depending on other desired purposes. Dispersion can be performed by a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like. Examples of the dispersant include a dispersion resin described later.

  From the viewpoint of stably dispersing the pigment in the water-based ink for a long period of time, the average particle diameter of the dispersed pigment is preferably 10 nm to 200 nm, more preferably 10 nm to 100 nm, and more preferably 10 nm. More preferably, it is 50 nm or less.

  The average particle size can be measured by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, a laser Doppler method or the like. Moreover, the above average is also obtained by performing particle image photographing with a transmission electron microscope on at least 100 particles and statistically processing this image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). The particle size can be determined.

1-1-2. Organic solvent The type of the organic solvent is not particularly limited as long as the effects of the present invention are exhibited. From the viewpoint of increasing the compatibility with water, the organic solvent is preferably water-soluble. Examples of the water-soluble organic solvent include alcohols, polyhydric alcohols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms. Only one kind of these organic solvents may be contained, or two or more kinds thereof may be contained in combination.

  Examples of the alcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol and tertiary butanol.

  Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having 5 or more ethylene oxide groups, propylene glycol, dipropylene glycol, tripropylene glycol, and propylene oxide groups. Polypropylene glycol having a number of 4 or more, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol and the like are included.

  Examples of the amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine Pentamethyldiethylenetriamine and tetramethylpropylenediamine.

  Examples of the amides include formamide, N, N-dimethylformamide, N, N-dimethylacetamide and the like.

  Examples of the glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether and tripropylene glycol. Monomethyl ether and the like are included.

  Examples of 1,2-alkanediols having 4 or more carbon atoms include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol and 1,2-heptanediol. It is.

  Among these, when the organic solvent is a polyhydric alcohol, bleeding during high-speed printing can be suitably suppressed. Examples of preferable polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol.

  When the ink jet recording ink contains two or more organic solvents, the mass ratio of the polyhydric alcohols relative to the total mass of the organic solvent is set higher than the mass ratio of the other organic solvents, thereby preventing bleeding of the formed image. It can be made more difficult to occur. Preferably, the mass ratio of the polyhydric alcohol to the mass of the whole organic solvent is 50% or more. When two or more kinds of polyhydric alcohols are included, the total mass ratio of all the polyhydric alcohols only needs to be higher than the mass ratio of any other kind of organic solvent. For example, the mass of the whole organic solvent The mass ratio of the polyhydric alcohol to the suffices is 50% or more.

  The content of the organic solvent in the recording ink can be, for example, in the range of 5% by mass to 60% by mass.

  According to the knowledge of the present inventors, the content of the organic solvent in the recording ink is in the range of 10% by mass or more and 40% by mass or less, so that it is difficult to cause cracks in the image. When an image is recorded using water-based ink, water as a solvent evaporates from ink droplets that have landed on the base material, which may cause ink droplets to contract and crack the image. On the other hand, by setting the content of the organic solvent in the above range, the resin is appropriately swollen and dissolved by the polyhydric alcohols. The swelled / dissolved resin is re-formed in an image formed by increasing the viscosity. It is considered that the resin film formed in this way makes it difficult for the ink droplets to shrink when the formed image is dried, and the image does not easily crack.

1-1-3. Other components As long as the effects of the present invention are exhibited, the water-based ink is a resin, a surfactant, a pH adjuster, oil droplet fine particles, an ultraviolet absorber, a discoloration inhibitor, a fluorescent whitening agent, a polysaccharide, a viscosity adjustment. An agent, a specific resistance adjusting agent, a film forming agent, an ultraviolet absorber, an antioxidant, a fungicide, a rust inhibitor and the like may be contained. Only one kind of these components may be contained, or two or more kinds may be contained in combination.

  Examples of the resin include a dispersion resin for imparting dispersion stability to the pigment, a fixing resin for imparting fixing property to the substrate to the pigment, and a thickener for adjusting the viscosity of the ink. Resins and other resins are included. Only one kind of these resins may be contained, or two or more kinds may be contained in combination.

  From the viewpoint of further increasing the aggregation action of the pigment by reacting the pigment flocculant applied on the substrate with the resin in the ink, the resin is preferably anionized. Further, the resin preferably has an amine value from the viewpoint of facilitating the aggregation of the pigment when the pH of the landed ink is lowered by the pigment flocculant on the substrate.

  Examples of the anionized resin include a resin containing an anionic functional group such as a sulfonic acid group, a carboxylic acid group, and a phosphoric acid group. From the viewpoint of enhancing the aggregation action of the pigment and not reducing the storage stability of the ink, the anionic functional group may be contained in the resin in an amount such that the acid value is 10 mg / KOH or more and 350 mg / KOH or less. preferable. From the viewpoint of further enhancing the aggregating action of the pigment, the anionic functional group is preferably a carboxylic acid group or a phosphoric acid group.

  When the resin has an amine value, if the amine is a primary amine or a secondary amine, the viscosity can be sufficiently increased due to the above pH variation to aggregate the pigment. The amine value of the resin at this time is preferably in the range of 10 mg / KOH to 200 mg / KOH. On the other hand, when the amine is a tertiary amine, the viscosity can be sufficiently increased by a salting-out reaction to aggregate the pigment. The amine value of the resin at this time is preferably in the range of 10 mg / KOH to 500 mg / KOH.

  These resins may be contained in a copolymer or may be dispersed in an emulsion state. In the case of dispersing in an emulsion state, the particle diameter is preferably 300 nm or less from the viewpoint of not impairing the jetting property by inkjet. In the case of a soluble polymer, the composition and molecular weight are not particularly limited. However, since a polymer having a higher degree of polymerization tends to deteriorate injection properties, the molecular weight is preferably 50,000 or less, although it depends on the composition of the polymer.

  The surfactant may be any of cationic, anionic, amphoteric and nonionic.

  Examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.

  Examples of anionic surfactants include fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-N-methyl-β-alanine salt, N-acyl glutamate, acylated peptide, alkyl sulfonic acid Salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl sulfoacetate, α-olefin sulfonate, N-acylmethyl taurine, sulfated oil, higher alcohol sulfate, secondary Higher alcohol sulfate, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate, polyoxyethylene alkylphenyl ether sulfate, monoglyculate, fatty acid alkylolamide sulfate, alkyl ether phosphate, alkyl phosphate S Tell salt is included.

  Examples of amphoteric surfactants include carboxybetaine type, sulfobetaine type, aminocarboxylate, and imidazolinium betaine.

  Examples of nonionic surfactants include polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin Fatty acid ester, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide , Polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, alkylamine oxide, Cetirizine glycol, and the like acetylene alcohol.

  From the viewpoint of reducing the surface tension of the water-based ink, it is preferable that some of these surfactants are substituted with fluorine atoms or silicon atoms.

  Examples of pH adjusting agents include known acids, bases and buffers. Of these, ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, methylethylamine, monoethanolamine, diethanolamine, triethanolamine are difficult to inhibit the reaction between the crosslinked resin and the crosslinking agent. , Ethylenediamine, methylaminoethanol, and dimethylaminoethanol and salts thereof are preferred.

1-1-4. Physical Properties From the viewpoint of improving the ejection stability from the nozzles of the inkjet head, the viscosity of the water-based ink is preferably 1 cP or more and less than 100 cP. From the viewpoint of further improving the discharge stability, the viscosity of the water-based ink is preferably 1 cP or more and 50 cP or less, and more preferably 1 cP or more and 15 cP or less.

  From the viewpoint of improving the ejection stability from the nozzles of the inkjet head, the surface tension of the water-based ink is preferably 20 mN / m or more and 50 mN / m or less. From the viewpoint of improving the wettability with respect to the base material and making the formed image higher definition, the surface tension of the water-based ink is more preferably 20 mN / m or more and 35 mN / m or less. The surface tension of the water-based ink can be adjusted to the above range by changing the type or amount of the surfactant and the organic solvent.

1-2. Step of applying the first treatment liquid In this step, the first treatment liquid is applied onto the substrate.

  The first treatment liquid may be applied to an area wider than the area where the water-based ink droplets land. The first treatment liquid is formed by, for example, roll coating using a bar coater, anilox roller, slit coater, die coater, spraying, offset printing, curtain coating, gravure coating, and the above-described inkjet method. It can be applied on the material.

  The application amount of the first treatment liquid is not particularly limited, and can be appropriately adjusted according to the film thickness of the coating layer described above and the adhesion amounts of a crosslinking agent, a pigment flocculant, and the like.

  After the first treatment liquid is applied, the first treatment liquid may be dried by heating the substrate. Drying can be performed by a known method such as spraying of hot air, irradiation with infrared rays, and irradiation with ionizing radiation. These drying methods can be performed by any dryer (hot air dryer or the like) which is a means for drying. The blowing of the hot air and the irradiation of infrared rays or ionizing radiation may be performed on the surface of the substrate to which the first treatment liquid is applied, or a surface (hereinafter referred to as the back side of the applied surface). It may be simply performed on the “back surface”. Only one of these drying methods may be performed, two may be combined at the same time, or one method may be switched to another method during the drying process.

  Among these, hot air blowing is preferable because the configuration of the apparatus is simple and the drying apparatus can be further downsized. On the other hand, from the viewpoint of preventing damage to the substrate, infrared irradiation and ionizing radiation irradiation are preferable.

[First treatment liquid]
The first treatment liquid contains a crosslinking agent. The first treatment liquid may further include a pigment flocculant when the water-based ink includes a pigment. The first treatment liquid may contain other components as long as the effects of the present invention are not significantly impaired. The solvent of the first treatment liquid is preferably water because of its high safety, but may contain an organic solvent as described for the water-based ink. The first treatment liquid may further contain a known surfactant, thickener, antifungal agent, bactericidal agent, moisturizing agent and the like.

1-2-1. Crosslinking agent The crosslinking agent should just be a thing which can bridge | crosslink the crosslinking resin mentioned later, and can be suitably selected according to the kind of crosslinking | crosslinked group which crosslinking resin has.

  Examples of the crosslinking agent include carbodiimide compounds, isocyanate compounds, epoxy compounds, silyl compounds, hydrazine compounds and oxazoline compounds. Only one kind of these crosslinking agents may be contained, or two or more kinds may be contained in combination.

  Specific examples of crosslinking agents include: Carbodilite manufactured by Nisshinbo Chemical Co., Ltd. ("Carbodilite" is a registered trademark of the company), Meikanate series manufactured by Meisei Chemical Co., Ltd., Epocross manufactured by Nippon Shokubai Co., Ltd. ("Epocross" The company's registered trademark) series and WACKER SILANE ("WACKER" is a registered trademark of Wacker) manufactured by Asahi Kasei Wacker Silicone Co., Ltd. are included.

  From the viewpoint of sufficiently spreading the crosslinking agent in the region to which the first treatment liquid is applied, the crosslinking agent is preferably water-soluble.

  Moreover, as long as it has reactivity with the crosslinkable group, the crosslinking agent may be an oligomer or a polymer, and is a pendant polymer in which a functional group capable of crosslinking the crosslinkable group is added as a side chain to another resin. Also good.

The amount (attachment amount) of the crosslinking agent applied to the substrate may be 10 ⁻⁶ mol or more with respect to 1 g of the crosslinked resin. When the amount of the crosslinking agent applied is at least the above amount, the crosslinked resin is sufficiently crosslinked, and the scratch resistance of the formed image is further increased. Although the quantity of the crosslinking agent provided to a base material is based also on the combination of resin and a crosslinking agent, it can be 10 ^<-2 > mol or less with respect to 1g crosslinked resin, for example. However, when the crosslinking agent is an oligomer or polymer, the effect of increasing the scratch resistance of the formed image is also imparted by the crosslinking agent, so the amount of the crosslinking agent can be reduced.

1-2-2. Pigment flocculant The pigment flocculant is a compound having the effect of aggregating the pigment. The pigment flocculant aggregates the pigment on the base material to reduce the solubility of the pigment in water, and can suppress deterioration in image quality due to bleeding of aqueous ink. In particular, it is preferable to use a pigment flocculant when an image is formed at a high speed.

  From the viewpoint of further improving the diffusibility to the vicinity of the pigment and further suppressing bleeding, the pigment flocculant is preferably water-soluble.

  Any pigment aggregating agent may be used as long as it has an action of aggregating the pigment. For example, when the pigment is an anionic dispersed pigment, the pigment flocculant can be an acid or a cationic compound. Only one type of these pigment flocculants may be contained, or two or more types may be contained in combination.

  The acid can agglomerate the anionic dispersed pigment by pH fluctuation. Examples of such acids include formic acid, acetic acid, propionic acid, isobutyric acid, oxalic acid, fumaric acid, malic acid, citric acid, malonic acid, succinic acid, maleic acid, benzoic acid, 2-pyrrolidone-5-carboxylic acid. Examples include acid, lactic acid, acrylic acid and derivatives thereof, methacrylic acid and derivatives thereof, acrylamide and derivatives thereof, sulfonic acid derivatives, and phosphoric acid and derivatives thereof. The acid is preferably an organic acid. An organic acid is highly compatible with other components (such as a cross-linking agent) contained in the first treatment liquid, and is difficult to become a salt even when the first treatment liquid is dried on the substrate. It has excellent transparency and is difficult to discolor the formed image.

  The cationic compound can agglomerate the anionic dispersion pigment by salting out. Examples of the cationic compound include polyvalent metal salts, cationic surfactants, and cationic resins. Preferred examples of the polyvalent metal salt include water-soluble salts such as calcium salts, magnesium salts, aluminum salts, and zinc salts. As the cationic surfactant (also referred to as cationic surfactant), for example, aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts and the like are preferable. Can be mentioned. Examples of the cationic resin include polyallylamine, polyvinylamine, polyethyleneimine, and polydiallyldimethylammonium chloride.

  Of these, polyvalent metal salts and polyvalent metal salts are preferred because they have a low molecular weight, are easily diffused into water-based ink, and cause the pigment to aggregate more rapidly. Furthermore, an acid is more preferable because of higher safety and compatibility with a crosslinked resin.

  A pigment flocculant may be used individually by 1 type, and may use multiple types together.

  The range of the content (amount) of the pigment flocculant applied to the substrate is not limited, and can be set as appropriate according to the amount of water-based ink, the type of pigment, the type of pigment flocculant, and the like. For example, the mass of the pigment flocculant is preferably 3% by mass to 50% by mass with respect to the mass of the image to be formed.

  In addition, when using an acid, it is preferable that the addition amount of an acid is an amount which adjusts the pH of a process liquid to below the neutralization equivalent of the anion component contained in aqueous ink. Further, when the anionic component is an acrylic acid group, the first dissociation constant of the acid is preferably 3.5 or less from the viewpoint of making image bleeding more difficult.

1-3. Step of applying the second treatment liquid In this step, the second treatment liquid is applied on the substrate.

  The second treatment liquid may be applied to an area wider than the area where the water-based ink droplets land. The first treatment liquid can be applied onto the substrate by, for example, coating with a bar coater and a roll coater, spraying with a spray, offset printing, and the inkjet method described above.

  The application amount of the second treatment liquid is not particularly limited, and can be appropriately adjusted according to the film thickness of the coating layer and the adhesion amount of the pigment flocculant.

  After the second treatment liquid is applied, the second treatment liquid may be dried by heating the substrate. The drying of the second treatment liquid can be performed by the method exemplified for the drying of the first treatment liquid described above. At this time, it is preferable that the second treatment liquid is not completely dried, and is kept in an incomplete film formation state leaving room for film formation with a crosslinked resin.

[Second treatment liquid]
The second treatment liquid contains a crosslinked resin. The second treatment liquid may further include the above-described pigment flocculant when the water-based ink includes a pigment. In addition, the second processing liquid may contain other components as long as the effects of the present invention are not significantly impaired. The solvent of the second treatment liquid is preferably water because of its high safety, but may contain an organic solvent as described for the water-based ink. The second treatment liquid may further contain the above-described pigment flocculant. The second treatment liquid may further contain a known surfactant, thickener, antifungal agent, bactericidal agent, moisturizing agent and the like.

1-3-1. Crosslinked resin The crosslinked resin is a resin having a crosslinkable group and crosslinked by the above-described crosslinking agent. Only one type of the crosslinked resin may be contained, or two or more types may be contained in combination.

  From the viewpoint of increasing the compatibility with the water-based ink and further improving the scratch resistance of the formed image, the crosslinked resin is preferably a water-soluble or water-dispersible resin. From the viewpoint of further improving the water resistance of the formed image, the crosslinked resin is preferably a water-dispersible latex resin. Since the latex resin is highly compatible with the pigment flocculant, when the pigment flocculant is applied on the substrate, it is possible to more easily suppress image bleeding.

  The structure of the crosslinked resin is not particularly limited as long as a crosslinkable group can be included in the molecule. Examples of the crosslinked resin include urethane resin, acrylic resin, olefin resin, vinyl chloride resin, polyester resin, polyamine resin, and polyvinyl alcohol. As the structure of the crosslinked resin, a material having high affinity with the material constituting the substrate can be selected as appropriate.

  A crosslinkable group can be suitably selected according to the kind of crosslinking agent mentioned above. Examples of the crosslinkable group include an amine group, a urethane bond, a urea bond, a polyol having an adjacent carbon molecule having a hydroxyl group, and a carboxyl group.

  When the crosslinked resin is a latex resin, the latex resin may be a hybrid resin. Examples of the hybrid resin include latex resins having a core-shell structure having a hydrophobic portion in the core portion and a hydrophilic portion in the shell portion. Since the latex resin having such a core-shell structure can be made hydrophobic after being crosslinked on the base material, it is possible to further improve the scratch resistance while improving the water resistance of the formed image.

  The hydrophobic part and the hydrophilic part only have to have a known structure constituting the hybrid resin. The hydrophobic portion can be, for example, urethane, acrylic, styrene, polyester, polystyrene, polycarbonate, urea resin, polyol, and copolymer resins thereof. The hydrophilic portion can be, for example, urethane, acrylic, urea resin, polyol, and copolymer resin thereof.

  The latex resin may be anionic, cationic, or nonionic, but it is preferable that a group that reacts with a crosslinking agent is present on the surface of the latex resin, in other words, anionic and cationic. Latex resins are more preferred, and non-emulsifiable latex resins are preferred.

  The cross-linked resin is preferably resin fine particles. The average particle diameter of the resin fine particles is preferably in the range of 10 nm to 10 μm. The average particle size can be measured by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, etc., but the measurement by the dynamic light scattering method is simple and the particle size region is Accurate measurement.

  From the viewpoint of further improving the scratch resistance and water resistance of the formed image, the amount of the crosslinking agent applied to the substrate (attachment amount) is such that the resin solid content of the crosslinked resin is relative to the mass of the formed image. The amount is preferably 50% by mass or more.

1-4. Area to be Applied Both the first processing liquid and the second processing liquid are applied to an area wider than an area on the base material on which the water-based ink droplets are landed. By doing in this way, even if the landing position of the discharged droplets is shifted or the position of the substrate being transported is shifted, the crosslinking agent (first treatment liquid) and the crosslinked resin (second Water-based ink droplets can be landed on the region to which the (treatment liquid) is applied, thereby further improving the scratch resistance and water resistance of the formed image.

  At this time, it is preferable that the area to which the first treatment liquid and the second treatment liquid are applied is wider than the area where the ink is landed. For example, when the substrate is a film, the shift due to the meandering of the film may occur up to about 50 μm in the left-right direction. For this reason, if the first processing liquid and the second processing liquid are applied to a region spread by 50 μm or more around the position where the ink is landed, even if the position of the substrate being transported is displaced, etc. In addition, it becomes easier to land the ink on the region to which the first processing liquid and the second processing liquid are applied.

  In addition, it is desirable that the region to which the second processing liquid is applied be a region that substantially matches the region to which the first processing liquid is applied, or a wider region. By doing in this way, the stickiness of the base-material surface and the adhesiveness of a fingerprint by the crosslinking agent which did not react with crosslinked resin remain | survive in an image non-formation area | region can be suppressed. For example, it is preferable to apply the second treatment liquid to an area wider than 0 μm and smaller than 300 μm around the area to which the first treatment liquid is applied. At this time, the cross-linking agent contained in the first treatment liquid migrates in the cross-linked resin applied to the base material by the second resin, so that the second treatment liquid is applied. It is considered that the effect of improving the water resistance by the crosslinked resin can be seen in the entire region. In addition, from the viewpoint of making it less likely to cause stickiness and fingerprint adhesion due to the unreacted crosslinking agent, the region to which the second treatment liquid is applied substantially coincides with the region to which the first treatment liquid is applied. A region is preferable.

1-5. Order of Each Step The step of landing water-based ink droplets, the step of applying the first treatment liquid, and the step of applying the second treatment liquid can be performed in any order.

  For example, if the second processing liquid is applied last and the crosslinked resin is crosslinked on the outermost layer of the formed image, the crosslinked resin can sufficiently improve the scratch resistance and water resistance.

  Further, when the second treatment liquid is applied after the droplets of the water-based ink are landed, both can dry the water-based ink and accelerate the crosslinking of the cross-linked resin by heating, so that an image can be formed at a higher speed. it can.

  On the other hand, when the second treatment liquid is applied first, the wet spread of the water-based ink is moderately suppressed, possibly by a crosslinked resin having a hydrophilic tendency, so that the liquid (beading, etc.) and bleeding are suppressed from the liquid. A higher definition image can be formed.

  In particular, when the second treatment liquid containing the pigment flocculant is first applied, the pigment flocculant hardly deposits on the substrate, and a higher-definition image is likely to be formed.

  Therefore, a second treatment liquid (preferably a second treatment liquid containing a pigment flocculant) is applied first, then water-based ink droplets are landed, and the first treatment liquid is applied last to crosslink. It is preferable to crosslink the resin. At this time, from the viewpoint of improving the surface of the base material and facilitating the formation of a higher-definition image, the water-based ink droplets are landed after the second treatment liquid applied to the base material is dried. It is preferable.

  Even if the second treatment liquid is first applied, the cross-linked resin and the components contained in the water-based ink are sufficiently mixed, and thus the scratch resistance and water resistance are sufficiently increased.

1-6. Film Forming Step After performing the above-described step of landing water-based ink droplets, the step of applying the first treatment liquid, and the step of applying the second treatment liquid, the substrate is heated to cross-link the cross-linked resin. It is preferable to form a film. The heating for the crosslinking and film formation may be performed simultaneously with the drying of the ink after ink landing performed at the time of printing with the water-based ink.

  The heating is preferably performed at a temperature higher than the highest film forming temperature (MFT) of the resin applied to the substrate. When the MFT of the resin is lowered by a solvent or the like, the temperature is preferably higher than the highest temperature among the lowered MFT. MFT can be measured using a known minimum film-forming temperature measuring device.

  However, the heating is preferably performed at a temperature lower than the heat resistant temperature of the substrate.

  From the viewpoint of sufficiently crosslinking and forming a film of the crosslinked resin, while suppressing the increase in the size of the drying apparatus, the heating time is preferably 1 second or more and 120 seconds or less.

  Further, from the viewpoint of sufficiently crosslinking the crosslinked resin, it is preferable that the substrate is allowed to stand at 20 ° C. or higher for 1 hour or longer after the heating.

1-7. Substrate The substrate is not particularly limited, and may be a paper substrate with high water absorption, or a substrate with low water absorption such as a gravure or coated paper for offset printing, or a film, plastic board (soft vinyl chloride, hard Non-water-absorbing substrates such as vinyl chloride, acrylic plates, polyolefins, etc.), glass, tiles and rubbers may be used. Of these, low-water-absorbing substrates and non-water-absorbing substrates, particularly preferably films, are difficult to remove unreacted cross-linking agent by washing. The effect of reducing the adherence of fingerprints is significantly achieved.

  Examples of the film include known plastic films. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polyethylene films including high-density polyethylene films and low-density polyethylene films, polypropylene films, polyamide films such as nylon, polystyrene films, ethylene / vinyl acetate copolymer Includes biodegradable films such as coalescence (EVA) film, polyvinyl chloride (PVC) film, polyvinyl alcohol (PVA) film, polyacrylic acid (PAA) film, polycarbonate film, polyacrylonitrile film, and polylactic acid film . In order to impart gas barrier properties, moisture proof properties, and fragrance retention properties, polyvinylidene chloride may be coated on one or both surfaces of the film, or a metal oxide may be deposited. Further, the film may be subjected to an antifogging process. The film may be subjected to corona discharge and ozone treatment.

  The film may be an unstretched film or a stretched film.

  The film may be a multilayer substrate in which a layer such as a PVA coat is provided on the surface of an absorbent substrate such as paper so that a region to be recorded is non-absorbable.

  The film preferably has a heat resistant temperature of 60 ° C. or higher.

  The thickness of the film is preferably less than 0.25 mm.

2. Inkjet image forming apparatus As shown in FIG. 3, an inkjet image forming apparatus 100 according to the present invention includes a head carriage 110 having an inkjet head that discharges water-based ink droplets to land on an area on a substrate, and the first carriage described above. It has the 1st process liquid provision part 120 which provides the 1st process liquid to a base material, and the 2nd process liquid provision part 130 which provides the 2nd process liquid mentioned above to a base material. The inkjet image forming apparatus 100 may further include a dryer 140 that dries the first treatment liquid or the second treatment liquid applied to the substrate surface.

  In FIG. 3, the second treatment liquid application unit 130, the head carriage 110, and the first treatment liquid application unit 120 are arranged in this order from the upstream side along the substrate conveyance direction (the arrow direction in the drawing). These arrangement orders are not limited to this order, and can be arbitrarily set.

  However, it is preferable that the second treatment liquid application unit 130 is disposed on the most upstream side or the most downstream side of these, and the second treatment liquid application unit 130, the head carriage 110, and the first treatment liquid application unit 120 are arranged in this order. Preferably they are arranged.

  The head carriage 110 includes, for example, four ink jet heads 111, and yellow, magenta, cyan, and black inks are ejected from the nozzles 112 of the respective ink jet heads 111, so that the water-based ink of the base material 150. The droplet is landed on the region to be landed.

  The 1st process liquid provision part 120 should just be the structure which can provide a 1st process liquid to the area | region wider than the area | region on the base material 150 where the droplet of a water-based ink lands. For example, the 1st process liquid provision part 120 can be set as the structure containing the dispenser 122 which supplies a treatment liquid to the application roller 121, and the application roller 121 which apply | coats the supplied process liquid to a film form.

  The 2nd process liquid provision part 130 should just be the structure which can provide a 2nd process liquid to the area | region wider than the area | region on the base material 150 where the droplet of an aqueous ink is landed. For example, the 2nd process liquid provision part 130 can be set as the structure containing the dispenser 132 which supplies a treatment liquid to the application roller 131, and the application roller 131 which apply | coats the supplied process liquid to a film form.

  The configurations of the first treatment liquid application unit 120 and the second treatment liquid application unit 130 are not limited to this, and the first treatment liquid and the second treatment liquid are discharged from the inkjet head, and land on the substrate. The structure to be made may be sufficient.

  The dryer 140 may be a known dryer such as a hot air dryer that blows hot air and an irradiator that emits infrared rays or ionizing radiation. The dryer 140 may be provided downstream of the second processing liquid application unit 130 and upstream of the head carriage 110, and may dry the second processing liquid before discharging water-based ink droplets (FIG. 3). The first processing liquid may be provided downstream of the first processing liquid application unit 120 and upstream of the head carriage 110, and the first processing liquid may be dried before discharging the water-based ink droplets (not shown).

3. Inkjet Recording System An inkjet recording system 600 according to the present invention is configured by connecting the inkjet image forming apparatus 100 and the drying apparatus 200 described above from the upstream side along the conveyance direction of the substrate, as shown in FIG. The The ink jet recording system 600 according to the present invention may have a delivery device 300 on the upstream side of the recording device 100. The inkjet recording system 100 according to the present invention may have a recovery device 400 on the downstream side of the drying device 200. The ink jet recording system 600 according to the present invention may further include a control unit 500.

  The drying device 200 dries the water-based ink that has landed on the base material to evaporate water, and causes the image to adhere to the base material. At the same time, the drying apparatus 200 causes the crosslinked resin and the crosslinking agent to react to form a film of the crosslinked resin. The drying apparatus 200 includes, for example, a dryer 210 such as a hot air dryer, a transport path 220 that transports the base material, and a reversing unit 230 that reverses the base material that has been transported through the transport path 220. The water-based ink landed on the substrate is dried while being moved.

  The orientation of the substrate in the drying apparatus 200 can be arbitrarily set. However, after the substrate is dried with the surface of the substrate on which the water-based ink has landed facing upward in the vertical direction, the surface of the substrate is vertical. It is preferable to include a step of inverting the base material so as to face downward in the direction and drying the base material with the surface of the base material facing downward in the vertical direction.

  The delivery device 300 is a device that delivers a base material 150 such as a film to the recording device 100. In the case of the delivery device 300, as shown in FIG. 4, a roll-shaped base material 150 is wound around a support shaft and held rotatably. The delivery device 300, for example, conveys the substrate 150 such as a film wound around a support shaft to the outside at a constant speed via a plurality of rollers (for example, a delivery roller and a paper feed roller).

  The collection device 400 is a device that collects the base material 150 such as a film conveyed from the drying device 200. In the housing of the collection device 400, for example, as shown in FIG. 4, a roll-shaped base material 150 is wound around a support shaft and held in a roll shape. The collection device 400 winds the substrate 150 such as a film conveyed from the drying device 200 around a support shaft at a constant speed via a plurality of rollers (for example, a feeding roller and a paper discharge roller).

  The control unit 500 controls the delivery operation of the delivery device 300, the recording operation of the recording device 100, the drying operation of the drying device 200, and the recovery operation of the recovery device 400.

  For example, the control unit 500 changes the rotation speed of the roller included in the delivery apparatus 300 and the rotation speed of the roller included in the collection apparatus 400 to send out the base material 150 from the delivery apparatus 300 and the base in the collection apparatus 400. The collection speed of the material 150 is adjusted.

  Further, the control unit 500 controls the ink jet head 111 of the recording apparatus 100 according to the content to be recorded, and discharges water-based ink droplets from the nozzles 112.

  Further, the control unit 500 controls the first treatment liquid application unit 120 and the second treatment liquid application unit 130, and the first treatment liquid application unit 120 and the second treatment liquid application unit 130 are arranged in a region wider than the region on the substrate 150 on which the water-based ink droplets are landed. A treatment liquid and a second treatment liquid are applied. At this time, the control unit makes the first processing so that the region to which the second processing liquid is applied is substantially the same as the region to which the first processing liquid is applied or a wider region. The liquid application unit 120 and the second treatment liquid application unit 130 may be controlled. At this time, for example, the control unit 500 changes the supply amount of the processing liquid from the dispenser 122 and the dispenser 132 and the rotation speed of the coating roller 121 and the coating roller 131 to change the first processing liquid and the second processing liquid. You may adjust the provision amount.

  In addition, the control unit 500 controls the dryer 210 of the drying device 200 according to the conveyance speed of the base material 150 and the amount of ejected aqueous ink to sufficiently dry the aqueous ink that has landed on the base material 150.

  At this time, the inkjet image forming apparatus 100 is not provided with the dryer 140, and the drying apparatus 200 may dry the water-based ink, the first treatment liquid, and the second treatment liquid, and crosslink the crosslinked resin. Good.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Example 1]
1-1. Preparation of material 1-1-1. Preparation of first treatment liquid The following materials were mixed and the resulting composition (first treatment liquid) was used as treatment liquid A.
Crosslinking agent (manufactured by Nisshinbo Chemical Co., Ltd., Carbodilite V-02, “Carbodilite” is a registered trademark of the company): 20 parts by weight Organic solvent (diethylene glycol monobutyl ether): 5 parts by weight Organic solvent (ethylene glycol): 20 parts by weight Surface activity Agent (BIC Chemie, BYK333 ("BYK") is a registered trademark of the company): 0.1 part by weight Water: remaining part

1-1-2. Preparation of second treatment liquid The following materials were mixed and the resulting composition (second treatment liquid) was designated as treatment liquid B.
Cross-linked resin (Daiichi Kogyo Kagaku Co., Ltd., Superflex 650 ("Superflex") is a registered trademark of the company): 30 parts by weight Organic solvent (ethylene glycol): 10 parts by weight Surfactant (by BYK Chemy, BYK333): 0.3 parts by weight Water: remaining

1-1-3. Preparation of other treatment liquids The following materials were mixed and the resulting composition was used as treatment liquid C.
Cross-linking agent (Nisshinbo Chemical Co., Ltd., Carbodilite V-02, “Carbodilite” is a registered trademark of the company): 20 parts by mass Cross-linked resin (Daiichi Kogyo Kagaku Co., Ltd., Superflex 650 (“Superflex”) is registered by the company) Trademark): 30 parts by weight Organic solvent (diethylene glycol monobutyl ether): 5 parts by weight Organic solvent (ethylene glycol): 10 parts by weight Surfactant (BYK333, BYK333): 0.3 part by weight Water: remainder

1-1-4. Preparation of water-based ink After 77.4 parts by mass of water and 20 parts by mass of a dispersant (product of BASF, Jonkrill 819 (“Jonkrill” is a registered trademark of the company)) were sufficiently stirred in a beaker, 2 .6 parts by mass of an organic solvent (dimethylaminoethanol) was added to obtain a mixed solution thereof. Thereafter, the mixed liquid was heated at 80 ° C. with stirring to obtain an ink dispersion.

  6 parts by mass of the ink dispersant, 4.4 parts by mass of an organic solvent (ethylene glycol), 4 parts by mass of a cyan pigment (manufactured by DIC Corporation, TGR-SD) and 7.8 parts by mass of water The mixture was stirred for 2 hours with a bead mill to which 5 mm zirconia beads were added, and after each component was sufficiently dispersed, the beads were removed to obtain a pigment dispersion. 22.2 parts by mass of the above pigment dispersion, 10.6 parts by mass of an organic solvent (ethylene glycol), 5 parts by mass of an organic solvent (diethylene glycol monobutyl ether), 1 part by mass of a nonionic surfactant (Nisshin Chemical Industry) Olufin E1010), 0.2 parts by mass of a surfactant (BYK333, manufactured by BYK Chemie) and water in an amount of 100 parts by mass were mixed. After mixing for 10 minutes, the mixture was filtered through a 3500 mesh metal filter to obtain a water-based ink.

1-2. Image formation Inkjet image forming apparatus has independent drive type inkjet heads (manufactured by Konica Minolta Co., Ltd.) with 360 dpi and discharge amount of 14 pL arranged in pairs so that nozzles are staggered, and 720 dpi × 720 dpi images are one-pass type A head unit that can be printed with is formed. Three sets of the head units were installed on a 1 μm precision transfer stage. A polyethylene film (Futamura Chemical Co., Ltd., Taiho Polyester Film FE # 50-FE2001) cut into a sheet was fixed on the transfer stage. The ink tanks provided in the respective head units were filled with any one of the processing liquid A, the processing liquid B, the processing liquid C, and the water-based ink.

  Any one of the processing liquid A, the processing liquid B, the processing liquid C, and the water-based ink was ejected from the inkjet head to form an image of the following pattern 1 or pattern 2.

Pattern 1: An image including a 0.1 mm (3 pixel) thick thin line and a cyan solid image formed adjacent to the thin line and having a printing rate of 20%, 50% and 100% Pattern 2: Pattern 100% cyan solid image formed in an area of a size that includes all the fine lines and solid images of 1

  In the following experiment, the pattern 2 is formed in a region including the pattern 1 formed in the same experiment, and the plurality of patterns 1 and 2 in the same experiment are formed from the inkjet head so as to be formed at the same position. The movement of the polyethylene film by the discharge and the transfer stage was controlled.

1-2-1. Experiment 1
After pattern 2 is formed with treatment liquid A containing a crosslinking agent and dried with hot air using a dryer, pattern 1 is formed with the aqueous ink, and then pattern 2 is formed with treatment liquid B containing resin. It dried with hot air until drying was confirmed.

1-2-2. Experiment 2
After pattern 2 is formed with treatment liquid B containing resin and dried with hot air using a dryer, pattern 1 is formed with the aqueous ink, and then pattern 2 is formed with treatment liquid A containing a crosslinking agent. It dried with hot air until drying was confirmed.

1-2-3. Experiment 3
After pattern 1 is formed with the water-based ink and dried with hot air using a dryer, pattern 2 is formed with treatment liquid B containing resin, and then pattern 2 is formed with treatment liquid A containing a crosslinking agent. It dried with hot air until drying was confirmed.

1-2-4. Experiment 4
The treatment liquid A containing a crosslinking agent is applied with a # 8 bar coater, dried with hot air using a dryer, and then the pattern 1 is formed on the applied and dried treatment liquid A with the aqueous ink. And dried with hot air until drying was confirmed.

1-2-5. Experiment 5
After pattern 1 is formed with treatment liquid B containing resin and dried with hot air using a dryer, pattern 1 is formed with the aqueous ink, and then pattern 1 is formed with treatment liquid A containing a crosslinking agent. It dried with hot air until drying was confirmed.

1-2-6. Experiment 6
A treatment liquid C containing a crosslinking agent and a resin is applied with a # 8 bar coater, dried with hot air using a dryer, and then a pattern 1 is formed on the applied and dried treatment liquid C with the aqueous ink. It was dried with hot air until dryness was confirmed visually.

1-3. Evaluation A plurality of images were formed in accordance with the methods of Experiments 1 to 6, respectively, and the obtained images were further heated in an oven at 80 ° C. for 1 hour. Thereafter, the samples 1 to 6 were obtained by leaving them in an environment of 35 ° C. for 3 days.

  Sample 1 to Sample 6 were evaluated for image quality, water resistance and tactile sensation according to the following criteria.

1-3-1. Image quality Check the status of Sample 1 to Sample 6, and there is an image with large unevenness, the thickness of the line or the density of the solid varies among multiple images included in the same sample, and it does not print correctly Samples that generate images were evaluated as “x”. Slight graininess may be observed, but samples with no overall homogeneity and repeated prints of equivalent quality are evaluated as “◯”, and images with strong graininess and poor sharpness are included. The sample was evaluated as “Δ”.

1-3-2. Water resistance The surfaces of Samples 1 to 6 were rubbed 10 times with a non-woven fabric (made by Asahi Kasei Co., Ltd., Bencott, “Bencot” is a registered trademark of the company) that was sufficiently squeezed after sufficiently absorbing water. After rubbing, it is confirmed whether or not there is a dot defect in the fine line or 20% solid image formed with the above water-based ink. Evaluated as “x”.

1-3-3. Tactile sensation The surface of Sample 1 to Sample 6 was palpated, and it was confirmed whether stickiness or fingerprint adhesion was observed.

  The evaluation results of Sample 1 to Sample 6 are shown in Table 1.

  Using a water-based ink, a first treatment liquid containing a crosslinking agent (treatment liquid A), and a second treatment liquid containing a resin having a reactive functional group or structure that reacts with the crosslinking agent (treatment liquid B). Then, when the first treatment liquid and the second treatment liquid were applied to a wider area than the water-based ink, the formed image with higher image quality and water resistance was obtained (Sample Nos. 1 to 3).

  In particular, when the second treatment liquid, the water-based ink, and the first treatment liquid were applied in this order, an image with higher image quality was obtained (Sample No. 2).

  On the other hand, the image formed without using the second treatment liquid was likely to have fingerprints attached thereto, and the stickiness was large (Sample No. 4). This is presumably because unreacted crosslinking agent remained in the image.

  Further, the image formed by ejecting the first treatment liquid, the second treatment liquid and the water-based ink at the same position by the ink jet method had low image quality, water resistance, and large stickiness (Sample No. 5). This is thought to be because the fixability and water resistance effect of the cross-linked resin did not increase because the respective landing positions were shifted.

  Moreover, the image formed using the processing liquid (processing liquid C) containing a cross-linking agent and a resin did not easily improve the image quality (Sample No. 6). This is presumably because the reaction between the crosslinking agent and the resin progressed in the treatment liquid C, and the fixing effect by the resin did not increase particularly after a certain time had elapsed from the start of printing.

[Example 2]
2-1. Experiment 7
When 3 parts by mass of a pigment flocculant (calcium acetate) was further added to the treatment liquid A described above to form an image in the same manner as in Experiment 1, the obtained sample was evaluated in the same manner. Became high. However, the overall image quality was not so high.

2-2. Experiment 8
Further, 3 parts by mass of a pigment flocculant (calcium acetate) was added to the treatment liquid B described above to form an image in the same manner as in Experiment 2, and the obtained sample was evaluated in the same manner. An image having higher sharpness than any of Samples 1 to 6 was obtained.

  According to the image forming method of the present invention, it is possible to reduce stickiness and fingerprint adhesion to the substrate surface while increasing the scratch resistance and water resistance of the image without excessive heating due to the reaction between the crosslinking agent and the resin. it can. For this reason, the present invention is expected to expand the range of application of water-based ink by the ink jet method and contribute to the advancement and spread of technology in the same field.

DESCRIPTION OF SYMBOLS 12 Treatment liquid droplet 14 Water-based ink droplet 22 Processing liquid 24 Water-based ink droplet 32 First treatment liquid 34 Water-based ink droplet 36 Second treatment liquid 100 Inkjet image forming apparatus 110 Head carriage 111 Inkjet head DESCRIPTION OF SYMBOLS 112 Nozzle 120 1st process liquid provision part 121 Application roller 122 Dispenser 130 2nd process liquid application part 131 Application roller 132 Dispenser 140 Dryer 150 Base material 200 Drying apparatus 210 Dryer 220 Conveyance path 230 Inversion part 300 Delivery apparatus 400 Recovery apparatus 500 Control unit 600 Inkjet recording system

Claims (9)

A step of ejecting water-based ink droplets from an inkjet head and landing on a region on a substrate;
A step of applying a first treatment liquid containing a crosslinking agent onto the substrate; and a second treatment liquid containing a resin having a reactive functional group or structure that reacts with the crosslinking agent on the substrate. The step of applying to
Including
The first treatment liquid and the second treatment liquid are both applied to an area wider than the area on the substrate on which the water-based ink droplets land.
Image forming method.   The image forming method according to claim 1, wherein after the second treatment liquid is applied, landing of the droplets of the water-based ink and application of the first treatment liquid are performed.   The image forming method according to claim 1, wherein the application of the second processing liquid, the landing of the droplets of the water-based ink, and the application of the first processing liquid are performed in this order.   The region to which the second treatment liquid is applied is a region that substantially matches the region to which the first treatment liquid is applied, or is a wider region. The image forming method described in 1.   5. The compound according to claim 1, wherein the crosslinking agent is a compound selected from the group consisting of (poly) carbodiimide compounds, (poly) isocyanate compounds, epoxy compounds, silyl compounds, oxazoline compounds, and hydrazine compounds. The image forming method described.   The image forming according to claim 1, wherein the reactive functional group or structure is a functional group or structure selected from the group consisting of a carboxyl group, a polyol structure, a urethane bond, and an amide group. Method.   The image forming method according to claim 1, wherein the substrate is a film. An inkjet head that discharges water-based ink droplets and lands on an area on a substrate;
A first treatment liquid application portion for applying a first treatment liquid containing a crosslinking agent on the substrate; and a second treatment liquid containing a resin having a reactive functional group or structure that reacts with the crosslinking agent. Having a second treatment liquid application unit applied on the substrate;
Inkjet image forming apparatus. An inkjet image forming system comprising: the inkjet image forming apparatus according to claim 8; and a drying device that dries a substrate on which an image is formed by the inkjet image forming apparatus.

Images