WO2019239923A1

WO2019239923A1 - Image forming method

Info

Publication number: WO2019239923A1
Application number: PCT/JP2019/021774
Authority: WO
Inventors: 伊丹　明彦; 拓己石渡
Original assignee: コニカミノルタ株式会社
Priority date: 2018-06-13
Filing date: 2019-05-31
Publication date: 2019-12-19
Also published as: JPWO2019239923A1; JP7367672B2

Abstract

The purpose of the present invention is to provide an image forming method by which a greater variety of metallic glazes can be expressed. This purpose is attained by an image forming method including: a step for, by providing a pre-coating agent to a surface of a base material, forming a pre-coating layer; and a step for, by providing a brilliant ink including a brilliant pigment to a surface of the pre-coating layer by an inkjet method, forming an ink layer obtained by aggregation of dots formed by the brilliant ink. In this method, a film thickness of the ink layer or the pre-coating layer corresponding to one dot included in the ink layer is made different from a film thickness of the ink layer or the pre-coating layer corresponding to another dot included in the ink layer. Values of the height of a baseline and the height of a peak of reflection intensity or the brightness of reflected light reflected on the formed image are made different between a region including the one dot and a region including the other dot.

Description

Image forming method

The present invention relates to an image forming method.

Aluminum pigments and pearl pigments are used for the purpose of expressing metallic luster in recorded materials such as labels, packages, printed announcements and photographs. These pigments are applied on the substrate as an ink composition by analog printing techniques including offset printing, gravure printing, screen printing, and the like, and form a region that emits a metallic gloss color in the image formed product.

In recent years, nano-sized particles containing metal such as gold, silver, and copper (hereinafter, also simply referred to as “metal nanoparticles”) are used to produce a recorded material with a high-definition region that emits a metallic luster color. A method has been developed in which a metallic luster layer containing the above-mentioned metal nanoparticles is formed on a substrate by being applied to the substrate surface.

Further, Patent Document 1 describes a method of forming a plurality of metallic glosses having different glossiness on one image formed product in one printing process by an inkjet method. According to Patent Document 1, an ink composition ejected by an ink jet method is deposited on a base material to change the arithmetic roughness (Ra) of the base material surface for each region, thereby reducing the surface to a different extent for each region. By attaching a glossy ink composition containing tabular grains to the base material, it is said that different glossiness can be expressed for each region.

JP 2010-030139 A

According to the method described in Patent Document 1, as the amount of the ink composition (precoat agent) applied to the substrate surface is increased, the substrate surface is more roughened and the glossiness of the image-formed product is lowered. It is said that. However, metal gloss has various levels of gloss from bright gloss to dull gloss. Even if the gloss level is changed by the method described in Patent Document 1, the above various levels of gloss are sufficiently reproduced. It wasn't clear.

Further, in the method of roughening the surface of the substrate as in the method described in Patent Document 1, the degree of gloss can be changed only to the extent corresponding to the thickness of one dot, and an image that can be formed by an image forming apparatus. The surface roughness of the substrate cannot be finely adjusted more finely than the resolution. Therefore, when it is desired to finely adjust the surface roughness, there is no choice but to use a substrate having a fine surface roughness. However, if the surface roughness is adjusted by the base material, the gloss cannot be changed for each region in the image. As described above, conventionally, it has been difficult to form an image formed product in which gloss is finely changed in an image.

The present invention has been made in view of the above-mentioned problems, and can form an image formed product that can express more various metallic luster and finely change the gloss in images formed on the same substrate surface. It is an object of the present invention to provide a possible image forming method.

In one embodiment of the present invention for solving the above-described problems, a step of applying a precoat agent to the surface of a substrate to form a precoat layer, and ink jetting a glitter ink containing a glitter pigment on the surface of the precoat layer are performed. And an ink layer formed by gathering dots formed by the glitter ink and forming an ink layer. In the above method, the film thickness of the precoat layer or the ink layer corresponding to one dot included in the ink layer and the film thickness of the precoat layer or the ink layer corresponding to another dot included in the ink layer. And the peak height of the reflected light reflected from the formed image and the height of the baseline, and the areas including the one dot and the other dots, with different thicknesses. And different values.

Another embodiment of the present invention for solving the above problem is that a glittering ink containing a glittering pigment is applied to the surface of a substrate by an ink jet method, and dots formed by the glittering ink gather. And forming an overcoat layer by applying an overcoat agent to the surface of the dots constituting the ink layer, and forming an overcoat layer. In the above method, the thickness of the ink layer and the overcoat layer corresponding to one dot included in the ink layer, and the thickness of the ink layer and the overcoat layer corresponding to other dots included in the ink layer The thickness of the film is different from the thickness, and the peak height of the reflected light or the reflected intensity reflected by the formed image and the half width of the peak are set to the region including the one dot and the other. The value differs depending on the area including the dot.

According to the present invention, there is provided an image forming method capable of forming a variety of metallic luster and capable of forming an image formed product in which gloss is finely changed in images formed on the same substrate surface.

FIG. 1A is a schematic diagram illustrating a state in which a part of incident light incident on an object is specularly reflected light, and another part is diffusely reflected light. FIG. 1B is a diagram illustrating the state of FIG. FIG. 6 is a schematic diagram illustrating a distribution information graph in which the light reception angle (θ) is plotted on the vertical axis and the lightness (L ^* ) is plotted on the vertical axis. FIG. 2 is a flowchart of the image forming method according to the first embodiment of the present invention. FIG. 3 is a flowchart of an image forming method according to the second embodiment of the present invention. FIG. 4 is a flowchart of another image forming method according to the second embodiment of the present invention.

The present inventors have intensively studied in view of the above problems, and the gloss perceived from the image formation is perceived by each of the regular reflection component and the diffuse reflection component when the light reflected by the image formation is perceived. It was found to be influenced by the contributions that contribute to

That is, as compared with a general color, the glossy color directionally reflects more of the light incident on the object as regular reflection light. For this reason, a large directivity occurs in the spatial distribution of the light reflected and perceived by the glossy color, and it is considered that the influence of this directivity is great on the color tone of the glossy color that humans feel visually.

Specifically, the degree of gloss of an object perceived by an observer is a degree in which the brightness or reflection intensity of reflected light obtained by reflecting light incident on the object is concentrated and distributed at regular reflection angles ( It is influenced by the directivity of the spatial distribution. As shown in FIG. 1A, the incident light I incident on the object is partly specularly reflected light P and partly diffusely reflected light B (in FIG. 1A, specularly reflected light P and diffusely reflected The brightness or reflection intensity of the light B is determined by the distance from the point L where the incident light I is incident (the length of the solid arrow indicating the specularly reflected light P and the length of the broken arrow indicating the diffusely reflected light B). (Note that the lightness or reflection intensity of the light P and the light B is adjusted for easy understanding, and does not accurately reflect the lightness or reflection intensity actually measured and calculated.)

FIG. 1B shows distribution information of brightness or reflection intensity (reflectance or luminance) based on data of a plurality of different light reception angles and radiation intensity measured at the light reception angles. It is the graph which plotted the lightness or the reflection intensity on the vertical axis. At this time, the directivity of the spatial distribution is expressed by the peak height (H), the baseline height (B), and the peak half-value width (W) in the distribution information shown in FIG. The gloss can also be expressed by the peak height (H), baseline height (B), and peak half-value width (W). For example, the larger the difference between the peak height (H) and the baseline height (B), the stronger the perception of gloss, and the smaller the peak half width (W), the sharper the perception of gloss. According to the above knowledge, if an image is formed such that the height (H) of the peak, the height (B) of the baseline, and the half width (W) of the peak are changed, it is perceived from the formed image. The gloss to be applied can be changed accordingly.

According to further studies by the present inventors, in an image formed product having a precoat layer and an ink layer containing a bright pigment, by independently changing the film thickness of the precoat layer and the film thickness of the ink layer. , Peak height (H) and baseline height (B) can be varied. In addition, in an image formed product having a precoat layer, an ink layer containing a glitter pigment, and an overcoat layer, by changing the film thickness of the overcoat layer independently, the peak height (H) and The half width (W) of the peak can be further changed.

The present invention has been made on the basis of the above-mentioned new knowledge. By independently changing the film thicknesses of the precoat layer, the ink layer, and the overcoat layer, the height of the peak (H), the baseline The height (B) and the full width at half maximum (W) of the peak are changed to change the gloss perceived from the formed image.

1. First Embodiment In the first embodiment of the present invention, a precoat layer is formed on the surface of a base material using a precoat agent, and ink is applied to the surface of the precoat layer using a glitter ink containing a glitter pigment. The present invention relates to an image forming method for forming a layer. The precoat agent may be any precoat agent such as water-based, solvent-based, and actinic ray curable types, but the film thickness can be easily controlled by curing before the precoat agent is too wet and spread. From the viewpoint of facilitating thickening, it is preferably an actinic ray curable precoat agent capable of forming a plurality of layers by repeating the step of applying and curing the surface of the substrate. The glitter ink may be any ink such as a water-based ink, a solvent-based ink, and an actinic ray curable ink, but the viewpoint of suppressing a decrease in gloss due to the inclusion of components other than the glitter pigment in the ink layer. Is preferably water-based ink.

The method for applying the precoat agent is not particularly limited, and the precoat agent may be applied to the surface of the substrate using a roll coater, a spin coater, or the like, spray coating, dipping method, screen printing, gravure printing, offset. The precoat agent may be applied to the surface of the substrate by a method such as printing, or the precoat agent may be landed on the surface of the substrate by an inkjet method. Among these, from the viewpoint of forming a finer recorded matter, screen printing and an inkjet method are preferable, and an inkjet method is more preferable.

Meanwhile, the glitter ink is applied to the surface of the precoat layer by an inkjet method. Thereafter, the glitter ink is dried to remove a liquid component, or an actinic ray is applied to the glitter ink to cure the glitter ink, thereby forming dots formed by the glitter ink. An ink layer formed by gathering is formed.

At this time, by changing the film thickness of the precoat layer or ink layer formed by the applied precoat agent or glitter ink independently for each dot constituting the ink layer, the gloss of the image formed product is increased. Change independently for each dot. In this way, the precoat layer corresponding to one dot included in the ink layer (specifically, the portion of the precoat layer located immediately below the one dot) or the film thickness of the ink layer The thickness of the precoat layer corresponding to other dots contained in the ink layer (specifically, the portion of the precoat layer located immediately below the other dots) or the thickness of the ink layer is different. By making the peak height (H) and the baseline height (B) in the distribution information different between the area including the one dot and the area including the other dots, Different degrees of gloss can be perceived from each of the above areas. By applying the glitter ink by the ink jet method, it is possible to change the thickness of the ink layer for each dot and form an image in which the perceived gloss is changed with higher accuracy. Furthermore, when the precoat agent is also applied by the ink jet method, it is possible to change the thickness of the precoat layer for each dot and form an image in which the perceived gloss is changed with higher accuracy. The one dot and the other dots are included in the ink layer formed on the same surface of the same substrate. At that time, it is also possible to form an image having a fine glossy gradation by forming a region formed by a plurality of the above-mentioned one dots and a region formed by a plurality of other dots adjacent to each other. It is.

Specifically, the film thickness of the precoat layer includes the solid content concentration (concentration of resin, etc.) in the precoat agent, the number of times the precoat agent is applied to form the precoat layer, and the precoat agent discharged from the nozzle of the inkjet head. When the above droplets are applied to the surface of the substrate, the size can be adjusted by the size of the droplets (droplet amount), the number of droplets to be applied to each dot (number of droplets), and the like. For example, the film thickness of the precoat layer can be changed for each corresponding dot included in the ink layer by changing the number of times the precoat layer is formed or the number of droplets and the number of droplets for each region in the image. it can. The thickness of the ink layer is determined by the size of the droplet (droplet amount) and the solid in the glitter ink when the droplet of the glitter ink ejected from the nozzle of the inkjet head is applied to the surface of the precoat layer. It can be adjusted by the partial concentration (concentration of glitter pigment, fixing resin, etc.).

In order to form a high-definition image, it is preferable that the precoat agent (when applied by the ink jet method) or the droplet amount of the glitter ink is adjusted in the range of 0.5 pl to 50 pl. Is more preferably adjusted within a range of 0.5 pl to 20 pl, and further preferably adjusted within a range of 0.5 pl to 10 pl.

The number of droplets of the precoat agent (when applied by the inkjet method) is preferably adjusted in the range of 0 to 10 drops, more preferably adjusted in the range of 0 to 5 drops. .

When an embossed image is formed, the precoat agent is applied by an ink jet method and a region in which the number of droplets of the precoat agent applied by the ink jet method is adjusted in the range of 0 to 5 drops. By forming in the image a region in which the number of droplets of the agent is adjusted in the range of 6 to 10 droplets, it is possible to form minute irregularities on the image.

The drive frequency when discharging the precoat agent (when applied by the ink jet method) or the glitter ink from the nozzle of the ink jet head is preferably adjusted in the range of 5 kHz to 100 kHz, and adjusted in the range of 5 kHz to 20 kHz. More preferably.

When forming an image including a plurality of regions having different densities, the number of dots formed per unit area included in each region is changed by independently changing the drive frequency for each region. It may be changed. When the drive frequency is increased to increase the number of dots formed per unit area, a lighter density region is formed, and the drive frequency is decreased to increase the number of dots formed per unit area. When the size is reduced, a region having a higher density is formed.

Further, the substrate is not particularly limited, and art paper, coated paper, lightweight coated paper, coated paper including fine coated paper and cast paper, and absorbent medium including non-coated paper, polyester, polyvinyl chloride, Non-absorbent recording media (plastic substrates) composed of plastics including polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate and polybutadiene terephthalate, and metals and A non-absorbable inorganic recording medium such as glass can be obtained. Of these, substrates with low surface smoothness (substrates with a rough surface) such as the above-mentioned absorbent medium have conventionally been difficult to align glitter pigments and have a significantly increased diffuse reflection component. Since it is easy (the height (B) of the baseline tends to be significantly high), it is difficult to adjust the degree of gloss. However, according to this embodiment, even with such a substrate having a low surface smoothness, the diffuse reflection component can be adjusted by adjusting the surface smoothness, and the degree of gloss can be easily adjusted.

In the present embodiment, the distribution information is obtained by independently changing the film thickness of the precoat layer to which the precoat agent is applied and the film thickness of the ink layer to which the glitter ink is applied, for each dot. The height (H) of the peak and the height (B) of the baseline are changed for each dot.

Specifically, in the case of a substrate having a low surface smoothness such as the above-mentioned absorbent medium, the surface roughness of the substrate can be adjusted to be smoother by increasing the film thickness of the precoat layer. This makes it possible to arrange the glitter pigment more precisely, increase the specular reflection component to increase the peak height (H), and decrease the diffuse reflection component to reduce the baseline height (B). The gloss can be adjusted to be low.

The film thickness of the precoat layer may be set for each region (or for each dot included in the region) according to the degree of gloss to be formed in each region of the image formed product. In addition, in the base material with low surface smoothness such as the above-described absorbent medium, it is preferable to adjust the application amount of the precoat agent so that the precoat layer does not completely cover the surface of the base material. In this manner, in the region including the one dot or the other dots, the precoat layer does not completely cover the surface of the base material, and a part of the surface of the base material is exposed, so that the base material is exposed. The peak height (H) and the baseline height (B) are adjusted in a wider range by adjusting the roughness of the substrate surface with the precoat layer while leaving the surface roughness to some extent. be able to.

In addition, by increasing the film thickness of the ink layer, the amount of the glitter pigment contained in the dots is increased, and the peak height (H) and the base height (B) are adjusted to be increased. Can do.

The film thickness of the ink layer may be set for each dot included in the region according to the degree of gloss to be formed in each region of the image formed product.

The film thicknesses of the precoat layer and the ink layer are the composition of the precoat agent and the glitter ink, and the time from when the actinic ray curable precoat agent is ejected and landed on the surface of the substrate until irradiation with actinic rays. , Etc. can also be changed. Based on these conditions, the application amount of the precoat agent and the glitter ink may be adjusted so that a desired degree of gloss can be obtained.

According to the method described in Patent Document 1, a plurality of regions having different glossinesses are obtained by changing the surface roughness of the substrate by changing the amount of the ink composition (precoat agent) applied to the substrate surface. Can be formed into an image-formed product. Specifically, as the application amount of the ink composition is increased, the surface of the substrate is roughened and the glossiness of the image formed product is decreased. However, the applicable substrate of the method is almost limited to a substrate having a smooth surface (for example, a resin sheet such as vinyl chloride). For a substrate having a rough surface such as a paper substrate, the applied amount of the ink composition does not always correspond to the glossiness of the image formed product, and an image having a desired glossiness cannot be formed. On the other hand, according to the present invention, it is possible to form an image having a desired degree of gloss regardless of the surface roughness of the substrate.

Further, in the method of roughening the surface of the substrate as in the method described in Patent Document 1, the degree of gloss can be changed only to the extent corresponding to the thickness of one dot, and an image that can be formed by an image forming apparatus. The surface roughness of the substrate cannot be finely adjusted more finely than the resolution. Therefore, when it is desired to finely adjust the surface roughness, there is no choice but to use a substrate having a fine surface roughness. However, if the surface roughness is adjusted by the base material, the gloss cannot be changed for each region in the image. As described above, conventionally, it has been difficult to form an image formed product in which gloss is finely changed in an image. On the other hand, in the present invention, it is possible to adjust the gloss more finely by changing the film thickness of each layer. In addition, according to the present invention, since the expression of the metallic luster can be controlled without depending only on the surface roughness of the substrate, different metallic luster can be expressed on the surface with the same surface roughness, or different surface roughness can be expressed. It is possible to express the same metallic luster on the surface.

1-1. Pre-coating agent The pre-coating agent may be an ink composition that is applied to the surface of the substrate and can form a layer on the surface.

For example, when the precoat agent is a water-based ink, it can contain water, a resin, and optionally a water-soluble organic solvent. Further, when the precoat agent is a solvent-based ink, it can contain an organic solvent and a resin. Further, when the precoat agent is an actinic ray curable ink, it can contain a photopolymerizable compound that polymerizes and crosslinks upon irradiation with actinic rays and optionally a photopolymerization initiator.

The precoat agent may further contain a surfactant, a polymerization inhibitor, an ultraviolet absorber, and the like as necessary. As for the above-mentioned other components, only one kind may be contained in the precoat agent, or two or more kinds may be contained.

The precoat agent is applied to the surface of the base material and cured from the viewpoint of facilitating the control of the film thickness by curing before the precoat agent is too wet and spreading, and also facilitating the thickening of the film thickness. An actinic ray curable pre-coating agent capable of forming a plurality of layers by repeating the process is preferred.

Examples of the water-soluble organic solvent when the precoat agent is a water-based ink include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, alcohols containing sec-butanol and t-butanol, ethylene glycol, diethylene glycol, triethylene Glycerol, hexanetriol, thiodiglycol, 1,2-butanediol, 1,3-butanediol, including glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, and pentanediol , 2-pentanediol, 1,2-hexanediol and polyhydric alcohols containing 1,2-heptanediol, ethanolamine, diethanolamine , Triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine and tetramethylpropylenediamine Amides including amines, formamide, N, N-dimethylformamide and N, N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone and 1,3-dimethyl-2-imidazolide Non-containing heterocyclic compounds, dimethyl sulfoxide-containing sulfoxides, ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, ethylene glycol monobutyl ether, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol monomethyl ether , Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol dimethyl ether Chill ether, dipropylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether, ethylene glycol monomethyl acetate, ethylene glycol monoethyl acetate, ethylene glycol monobutyl acetate, diethylene glycol monomethyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether Contains acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl acetate, triethylene glycol monobutyl ether Include glycol ethers.

The content of the water-soluble organic solvent when the precoat agent is water-based ink can be, for example, 5.0% by mass or more and 30% by mass or less with respect to the total mass of the precoat agent.

In addition, when applying the precoat agent to the substrate by the inkjet method, from the viewpoint of suppressing the occurrence of nozzle clogging due to drying of the water-based ink in the vicinity of the nozzle during ejection from the inkjet head, the water-soluble organic solvent is A polyhydric alcohol is preferably included. At this time, it is preferable that content of the polyhydric alcohol in a precoat agent is 1 to 10 mass% with respect to the total mass of a precoat agent.

Examples of the resin when the precoat agent is a water-based ink include polyester resins, polyurethane resins, acrylic resins, polyurethane-acrylic resins, vinyl chloride resins, and vinyl acetate resins. The resin may be a latex that is dispersed in ink to form a dispersion, or is a soluble resin (water-soluble resin or organic solvent-soluble resin) that is dissolved in ink with water or an organic solvent. Also good.

The content of the resin when the precoat agent is water-based ink can be, for example, 1% by mass to 20% by mass with respect to the total mass of the precoat agent as a solid content. In addition, what is necessary is just to adjust the content of the said resin according to the film thickness of the precoat layer formed by the film thickness of the precoat layer formed by one application | coating, and the liquid applied once by the inkjet method. .

Examples of the organic solvent when the precoat agent is a solvent-based ink include a water-soluble organic solvent and a water-insoluble organic solvent that can be used for the water-based ink.

Examples of the water-insoluble organic solvent include pentane, hexane, i-hexane, heptane, i-heptane, octane, i-octane, and aliphatic hydrocarbons having 5 to 15 carbon atoms and cyclopentane. , Cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, cycloheptane, and cycloaliphatic hydrocarbons having 5 to 15 carbon atoms, cyclohexene, cycloheptene, cyclooctene, 1,1,3,5,7 —Cyclooctatetraene, cyclododecene-containing cyclic unsaturated hydrocarbons having 5 to 15 carbon atoms, benzene, toluene, ethylbenzene, cumene, o-xylene, m-xylene and p-xylene having 6 to 12 carbon atoms The following aromatic hydrocarbons, heptanol, hexano , Methyl hexanol, ethyl hexanol, heptanol, octanol, decanol, undecyl alcohol, and monohydric alcohol having 5 to 15 carbon atoms, methyl-i-butyl ketone, di-i-butyl ketone, cyclohexanone, An alicyclic ketone having 5 to 15 carbon atoms, including methylcyclohexanone, cycloheptanone, and cyclooctanone, methyl acetate, ethyl acetate, propyl acetate, i-propyl acetate, butyl acetate, hexyl acetate, amyl acetate, Acetic acid-i-amyl, 2-ethylhexyl acetate, methyl propionate, ethyl propionate, butyl propionate, hexyl propionate, amyl propionate, ethyl valerate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, decane Ester compounds including ethyl, cyclohexyl acetate, cyclooctyl acetate, phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, butyl benzoate, dimethyl phthalate, diethyl phthalate, and dibutyl phthalate, nitroethane, nitropropane, Nitro compounds including nitropentane, nitrobenzene, dinitrobenzene, nitrotoluene, and nitroxylene, nitrites including acetonitrile, benzonitrile, and lactones including γ-butyrolactone and ε-caprolactone.

The content of the water-insoluble organic solvent when the precoat agent is a solvent-based ink can be, for example, 1.0% by mass or more and 98% by mass or less, and 20% by mass with respect to the total mass of the precoat agent. It is more preferable to set it as 95 mass% or less, and it is still more preferable to set it as 40 mass% or more and 90 mass% or less.

Examples of the resin when the precoat agent is a solvent-based ink include polyester resins, polyurethane resins, acrylic resins, polyurethane-acrylic resins, vinyl chloride resins, and vinyl acetate resins. The resin may be a latex that is dispersed in ink to form a dispersion, or is a soluble resin (water-soluble resin or organic solvent-soluble resin) that is dissolved in ink with water or an organic solvent. Also good.

The content of the resin when the precoat agent is a solvent-based ink can be, for example, 1% by mass or more and 20% by mass or less as a solid content with respect to the total mass of the precoat agent. In addition, what is necessary is just to adjust the content of the said resin according to the film thickness of the precoat layer formed by the film thickness of the precoat layer formed by one application | coating, and the liquid applied once by the inkjet method. .

Examples of the photopolymerizable compound when the precoat agent is an actinic ray curable ink include a radical polymerizable compound and a cationic polymerizable compound. The photopolymerizable compound may be any of a monomer, a polymerizable oligomer, a prepolymer, or a mixture thereof.

The radical polymerizable compound is preferably an unsaturated carboxylic acid ester compound, and more preferably (meth) acrylate. In the present specification, “(meth) acrylate” means acrylate or methacrylate, “(meth) acryl” means acryl or methacryl, and “(meth) acryloyl” means acryloyl or methacryloyl. means.

Examples of monofunctional (meth) acrylates include isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isomustyl (meth) acrylate, isostearyl (Meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meta ) Acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, phenoxye (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl-2-hydroxyethyl-phthalic acid and t-butylcyclohexyl (meth) Acrylate is included.

Examples of polyfunctional (meth) acrylates include triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (Meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Dimethylol-tricyclodecane di (meth) acrylate, PO adduct di (meth) acrylate of bisphenol A, neopentyl glycol di (meth) acrylate hydroxypivalate, polytetramethylene glycol di ( A) bifunctional (meth) acrylates including polyethylene acrylate, polyethylene glycol diacrylate and tripropylene glycol diacrylate, and trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate , Tri- or higher functional (meth) acrylates including dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxytri (meth) acrylate and pentaerythritol ethoxytetra (meth) acrylate.

The radical polymerizable compound preferably contains (meth) acrylate modified with ethylene oxide or propylene oxide (hereinafter also simply referred to as “modified (meth) acrylate”). The modified (meth) acrylate has higher photosensitivity. Further, the modified (meth) acrylate is more compatible with other components even at high temperatures. Furthermore, since the modified (meth) acrylate has little curing shrinkage, curling of the printed matter during irradiation with actinic rays is less likely to occur.

Examples of the cationic polymerizable compound include an epoxy compound, a vinyl ether compound, and an oxetane compound.

Examples of the epoxy compounds include 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene monoepoxide, ε-caprolactone modified 3, 4-epoxycyclohexylmethyl 3 ', 4'-epoxycyclohexanecarboxylate, 1-methyl-4- (2-methyloxiranyl) -7-oxabicyclo [4,1,0] heptane, 2- (3,4 -Epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexanone-cycloaliphatic epoxy resins such as meta-dioxane and bis (2,3-epoxycyclopentyl) ether, diglycidyl ether of 1,4-butanediol 1,6-hexanediol One kind of aliphatic polyhydric alcohols such as glycidyl ether, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, diglycidyl ether of polyethylene glycol, diglycidyl ether of propylene glycol, ethylene glycol, propylene glycol, and glycerin Aliphatic epoxy compounds containing polyglycidyl ethers of polyether polyols obtained by adding two or more types of alkylene oxides (such as ethylene oxide and propylene oxide), and di- or poly- of bisphenol A or its alkylene oxide adducts Di- or polyglycidyl ether of glycidyl ether, hydrogenated bisphenol A or its alkylene oxide adduct And aromatic epoxy compounds including novolac-type epoxy resins and the like.

Examples of the vinyl ether compounds include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl. Monovinyl ether compounds including ether-o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether, and the like, as well as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol dibi Ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, and the like di- or tri-vinyl ether compounds containing a cyclohexane dimethanol divinyl ether and trimethylolpropane trivinyl ether.

Examples of the oxetane compound include 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3-normalbutyloxetane, 3 -Hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane, 3 -Hydroxyethyl-3-phenyloxetane, 3-hydroxypropyl-3-methyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl-3-phenyl Xetane, 3-hydroxybutyl-3-methyloxetane, 1,4bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane and di [1-ethyl (3-oxetanyl)] methyl ether and the like are included.

Content of the said photopolymerizable compound in a precoat agent can be 1.0 mass% or more and 97 mass% or less with respect to the total mass of a precoat agent, for example, is 30 mass% or more and 90 mass% or less. It is preferable.

The precoat agent may further contain a photopolymerization initiator. The photopolymerization initiator may be any one that can initiate the polymerization of the photopolymerizable compound. For example, when the precoat agent has a radically polymerizable compound, the photopolymerization initiator can be a photoradical initiator, and when the precoat agent has a cationically polymerizable compound, the photopolymerization initiator is a photocationic initiator ( Photoacid generator).

The content of the photopolymerization initiator can be arbitrarily set within a range where the curing of the precoat agent is started by irradiation with actinic rays. For example, the content of the photopolymerization initiator is 0.1% by mass relative to the total mass of the precoat agent. It can be made 20 mass% or less, preferably 1.0 mass% or more and 12 mass% or less. In addition, when hardening of a precoat agent is started even if there is no photopolymerization initiator, such as when a precoat agent is semi-cured by irradiation of an electron beam, a photopolymerization initiator is unnecessary.

The precoat agent may contain a component that precipitates or aggregates the glitter pigment contained in the glitter ink, such as polyvalent metal ions and polyvalent organic acids. These components can precipitate or aggregate the glitter pigment in the glitter ink, and can further stabilize the dot diameter of the glitter ink.

When applying the precoat agent to the substrate by the inkjet method, the viscosity of the precoat agent is preferably 1 cP or more and less than 100 cP, from the viewpoint of further improving the ejection stability from the nozzles of the inkjet head, and is 1 cP or more and 50 cP or less. More preferably, it is 1 cP or more and 15 cP or less.

1-2. Glittering ink The glittering ink may be any ink composition that contains a glittering pigment and can be ejected by an inkjet method.

For example, when the glitter ink is a water-based ink, it can contain water and optionally a water-soluble organic solvent. The glitter ink can contain an organic solvent when it is a solvent-based ink. Further, when the glitter ink is an actinic ray curable ink, it can contain a photopolymerizable compound that polymerizes and crosslinks upon irradiation with an actinic ray and optionally a photopolymerization initiator. The kind and content of the water, water-soluble organic solvent, organic solvent, photopolymerizable compound and photopolymerization initiator that can be contained in the glitter ink can be the same as those of the precoat agent described above.

The glitter ink further includes a dispersant for dispersing the glitter pigment, a fixing resin for fixing the glitter pigment to the substrate, a surfactant, a polymerization inhibitor, an ultraviolet absorber, and the like, if necessary. You may contain. In the glitter ink, only one kind of the other component may be contained, or two or more kinds thereof may be contained.

The glitter pigment may be a known pigment used to develop gloss in an image, such as an aluminum pigment and a pearl pigment, but from the viewpoint of controlling the reflection of light more precisely by aligning the pigments. The metal particles are preferable.

The metal particles are particles having a metal as a main component and are not particularly limited as long as the particles can exhibit a metallic luster. Examples of metals constituting the metal particles include gold, silver, copper, nickel, palladium, platinum, aluminum, zinc, chromium, iron, cobalt, molybdenum, zirconium, ruthenium, iridium, tantalum, mercury, indium, tin, lead , And tungsten. Among these, gold, silver, copper, nickel, cobalt, tin, lead, chromium, zinc, and aluminum are preferable because they can exhibit high gloss and are inexpensive. Gold, silver, copper, tin Chrome, lead and aluminum are more preferred, gold and silver are more preferred, and silver is particularly preferred. These metals can be used singly or in combination of two or more as an alloy or a mixture. Further, two or more kinds of metal particles having different kinds or compositions of metals may be used in combination. The metal particles only need to have these metals as the main component, may contain a small amount of other components inevitably included, and may be surface-treated with citric acid or the like to improve dispersion stability. Good. Moreover, these metals may contain an oxide.

The average particle diameter of the metal particles is not particularly limited, but from the viewpoint of improving the dispersion stability and storage stability in the metal ink, and from the viewpoint of improving the visibility of gradation, the metal particles have an average particle diameter of nano-size. Certain metal nanoparticles are preferred. The average particle size of the metal particles is preferably 3 nm or more and 100 nm or less, more preferably 5 nm or more and 80 nm or less, further preferably 10 nm or more and 60 nm or less, and particularly preferably 15 nm or more and 55 nm or less. .

The average particle diameter of the metal particles is determined by observing the metal particle dispersion with an SEM and determining the volume average particle diameter of the nanoparticles, and specifically, the following procedure is performed.

1) After applying the dispersion on a glass plate, vacuum degassing to volatilize the solvent component to obtain a sample. The obtained sample dispersion is subjected to SEM observation using a scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.), and the particle diameters of arbitrary 300 metal particles are measured.
2) Based on the obtained measurement data, a volume-based particle size distribution is obtained using image processing software Image J, and its D50 (median diameter) is defined as an average particle diameter in terms of volume (volume average particle diameter).

The content of the metal nanoparticles in the glitter ink is not particularly limited, but is preferably 0.5% by mass to 15% by mass with respect to the total mass of the glitter ink, and is 0.75% by mass to 12. It is more preferably 5% by mass or less, and further preferably 1% by mass or more and 10% by mass or less.

The dispersing agent only needs to be able to sufficiently disperse the glitter pigment. In particular, when the glitter pigment is metal nanoparticles, the dispersant is preferably a polymer dispersant.

The polymer dispersant is a compound having an adsorbing group that can be adsorbed on the surface of the metal nanoparticles and a hydrophilic structure. Examples of the adsorbing group include a carboxyl group and a thiol group.

The resin constituting the polymer dispersant is preferably a homopolymer or copolymer of a hydrophilic monomer. The copolymer of hydrophilic monomers may be a copolymer of hydrophilic monomers and hydrophobic monomers.

Examples of hydrophilic monomers include monomers containing carboxyl groups or acid anhydride groups (such as (meth) acrylic acid, unsaturated polyvalent carboxylic acids such as maleic acid, and maleic anhydride), and alkylene oxide modified (meta). ) Acrylic acid ester monomers (such as ethylene oxide-modified (meth) acrylic acid alkyl esters). In the present invention, (meth) acryl means both or one of acrylic and methacrylic.

Examples of hydrophobic monomers include (meth) acrylate monomers such as methyl (meth) acrylate and ethyl (meth) acrylate, styrene monomers such as styrene, α-methylstyrene and vinyltoluene, ethylene, propylene And α-olefin monomers such as 1-butene, and vinyl carboxylate monomers such as vinyl acetate and vinyl butyrate.

When the polymer dispersant is a copolymer, it can be a random copolymer, an alternating copolymer, a block copolymer, a comb copolymer, or the like. Among these, from the viewpoint of further improving the dispersibility of the metal nanoparticles, the polymer dispersant is preferably a comb block copolymer.

The comb-type block copolymer means a copolymer containing a linear polymer that forms a main chain and another type of polymer that is graft-polymerized to a structural unit derived from a monomer that forms the main chain. A preferable example of the comb block copolymer is a long chain in which the main chain includes a structural unit derived from (meth) acrylic acid ester, and the side chain includes a polyalkylene oxide group (such as an ethylene oxide-propylene oxide copolymer group). Comb-type block copolymers containing a chain polyalkylene oxide group). In the comb-type block copolymer, since the graft-polymerized side chain causes steric hindrance, aggregation of metal nanoparticles can be further suppressed. Thereby, the dispersibility of the metal nanoparticles is increased, and thus it is easier to suppress ejection failure due to the aggregated metal nanoparticles.

The content of the polymer dispersant in the glitter ink is not particularly limited, but from the viewpoint of sufficiently enhancing the dispersibility of the metal nanoparticles in the glitter ink and the adhesion to the substrate, It is preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 10% by mass or less, and further preferably 3% by mass or more and 8% by mass or less with respect to the total mass.

Examples of the fixing resin include (meth) acrylic resin, epoxy resin, polysiloxane resin, maleic acid resin, vinyl resin, polyamide resin, nitrocellulose, cellulose acetate, ethyl cellulose, ethylene-vinyl acetate copolymer, urethane resin, Polyester resins and alkyd resins are included.

Among these, the fixing resin is an anionic resin emulsion from the viewpoint of increasing the adhesion of the metal nanoparticles to the substrate by interacting with the polymer dispersant adsorbed on the surface of the metal nanoparticles. Is preferred.

The anionic resin is preferably a resin having high affinity with the polymer dispersant, and is a (meth) acrylic resin, urethane resin, polyolefin resin, polyester resin, polyvinyl chloride resin (for example, polyvinyl chloride polymer, Vinyl chloride-vinylidene chloride copolymer), epoxy resin, polysiloxane resin, fluororesin, styrene copolymer (eg, styrene-butadiene copolymer, styrene- (meth) acrylate copolymer), and vinyl acetate A copolymer (for example, ethylene-vinyl acetate copolymer) can be appropriately selected and used. From the viewpoint of further improving the water resistance of the formed image, the anionic resin is composed of (meth) acrylic resin, urethane resin, polyolefin resin, polyvinyl chloride resin, epoxy resin, polysiloxane resin, fluorine resin, styrene copolymer. It is preferably selected from a coalescence, a vinyl acetate copolymer and the like, and preferably selected from a urethane resin and a (meth) acrylic resin.

The average particle size of the anionic resin emulsion is preferably 10 nm or more and 200 nm or less, and more preferably 30 nm or more and 100 nm or less. The average particle size of the emulsion can be a volume average particle size determined using a particle size distribution measuring apparatus based on a dynamic light scattering method.

The solid content of the emulsion in the glitter ink is preferably 0.01% by mass or more and 0.1% by mass or less based on the total mass of the metal nanoparticles and the polymer dispersant. When the solid content is 0.01% by mass or more, the abrasion resistance of the formed image can be further improved. When the solid content is 0.1% by mass or less, the glitter (reflectance) of the formed image can be further increased. From the above viewpoint, the solid content of the emulsion in the glitter ink is more preferably 0.02% by mass or more and 0.1% by mass or less, and 0.03% by mass or more and 0.1% by mass or less. More preferably.

Examples of such surfactants include anionic surfactants, including dialkyl sulfosuccinates, alkyl naphthalene sulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols and poly (ethylene glycols). Includes nonionic surfactants including oxyethylene / polyoxypropylene block copolymers, cationic surfactants including alkylamine salts and quaternary ammonium salts, silicone surfactants, and fluorine surfactants It is.

The content of the surfactant is preferably 0.001% by mass or more and less than 1.0% by mass with respect to the total mass of the glitter ink.

From the viewpoint of further increasing the reflectance of the ink layer, the glitter ink is composed of metal nanoparticles substantially adsorbed with the polymer dispersant, an emulsion and solvent of the anionic resin, and optionally a necessary amount of a surfactant. Preferably it consists of. The total content of the metal nanoparticles adsorbed by the polymer dispersant, the emulsion of the anionic resin, and the solvent is preferably 90% by mass or more and 100% by mass or less based on the total mass of the glitter ink. More preferably, it is 95 mass% or more and 100 mass% or less.

From the viewpoint of further improving the ejection stability from the nozzles of the inkjet head, the viscosity of the glitter ink is preferably 1 cP or more and less than 100 cP, more preferably 1 cP or more and 50 cP or less, and 1 cP or more and 15 cP or less. Is more preferable.

1-3. Image Forming Method FIG. 2 is a flowchart of the image forming method according to this embodiment. In the present embodiment, a precoat layer is formed in contact with the surface of the substrate using the precoat agent (step S110), and an ink layer is formed in contact with the surface of the precoat layer formed using the glitter ink. (Step S120).

1-3-1. Formation of precoat layer (step S110)
First, the said precoat agent is provided to the surface of a base material, and a precoat layer is formed.

For example, droplets of the precoat agent are ejected from the nozzles of the ink jet head onto the surface of the substrate that is transported and moved in the transport path. The discharged droplets land on the surface of the substrate. Alternatively, a precoat agent is applied to the surface of the substrate by a known method such as screen printing.

At this time, the film thickness of the precoat layer to be formed is expressed in a region including corresponding dots included in the ink layer (specifically, dots of the ink layer formed in contact with the portion of the precoat layer). Adjust according to the degree of gloss. The film thickness of the precoat layer is determined in advance according to the relationship between the degree of gloss to be developed and the film thickness of the precoat layer and the ink layer to be formed, which are determined in advance according to the type of the precoat agent and the glitter ink used. It can be determined by referring to the obtained correspondence table. Alternatively, the film thickness of the precoat layer is determined by causing a processing device that has undergone machine learning to calculate the relationship between the degree of gloss to be developed and the film thickness of the precoat layer and the ink layer to be formed. can do.

Specifically, when the droplets of the precoat agent ejected from the nozzles of the inkjet head are applied to the surface of the substrate, the size of the droplets (the amount of droplets) and the number of droplets applied to each dot (liquid The film thickness of the precoat layer formed may be adjusted by the number of droplets) or the number of times screen printing is repeated.

Although the conveyance speed of a base material is not specifically limited, For example, it may be set between 1 m / s or more and 1000 m / s or less. The higher the conveying speed, the faster the image forming speed.

When the precoat agent is applied to the substrate by the inkjet method, the ejection method from the inkjet head may be either an on-demand method or a continuous method. On-demand inkjet heads include electro-mechanical conversion methods such as single cavity type, double cavity type, bender type, piston type, shear mode type and shared wall type, as well as thermal inkjet type and bubble jet. Any of electric-thermal conversion methods such as Canon Inc. registered trademark) may be used.

At this time, the temperature of the precoat agent to be discharged may be adjusted by heating the ink flow path. The temperature of the precoat agent to be discharged is not particularly limited, but is preferably 50 ° C. or higher and 90 ° C. or lower.

Also, the resolution of the formed image can be adjusted by adjusting the discharge conditions of the precoat agent. The resolution of the formed image can be 600 dpi or more and 1440 dpi or less, but from the viewpoint of forming a higher-definition image, it is preferably 1200 dpi or more and 1440 dpi or less.

Thereafter, a precoat layer formed by curing the precoat agent is formed by irradiating the droplets of the precoat agent applied to the substrate with actinic rays or drying the precoat agent applied to the substrate.

The actinic light is preferably ultraviolet light from an ultraviolet LED. A metal halide lamp or the like is known as a general ultraviolet light source. However, by using an ultraviolet LED as a light source, it is possible to suppress the occurrence of curing failure on the surface of the cured film due to melting of the cured film by the radiant heat of the light source. From the viewpoint of appropriately curing the droplets, the peak wavelength of the ultraviolet LED is preferably 385 nm or more and 400 nm or less. An example of a light source having an ultraviolet LED includes a water-cooled ultraviolet irradiation unit (peak wavelength: 395 nm) manufactured by Phoseon Technology.

The irradiation conditions of actinic rays can be appropriately set according to the composition of the precoat agent. For example, a light source having a UV LED, the maximum illuminance on the surface of the droplet on the substrate is 0.5 W / cm ² or more 10.0 W / cm ² or less, more preferably 1W / cm ² or more 5W / cm ² or less and It can be installed so that.

1-3-2. Formation of ink layer (step S120)
Next, the glitter ink is applied to the surface of the dots on which the precoat agent constituting the precoat layer has been cured by an inkjet method for each dot. Thereafter, depending on the type of the glitter ink, for example, when the glitter ink is a water-based ink or a solvent-based ink, the liquid component is removed by drying or the like, or when the glitter ink is an actinic ray curable ink The glitter ink is cured by irradiation with actinic rays, and an ink layer formed by gathering dots formed by the glitter ink is formed. The drying conditions and the actinic ray irradiation conditions may be appropriately determined according to the composition of the glitter ink. For example, the actinic ray irradiation conditions may be the same as the conditions for curing the droplets of the precoat agent.

Also, the ejection method from the inkjet head is not particularly limited, and may be the same as the conditions for forming the precoat layer.

At this time, the film thickness of the ink layer to be formed is adjusted in accordance with the degree of gloss to be developed in the region including the dots formed by the applied glittering ink. The thickness of the ink layer is determined in advance according to the relationship between the degree of gloss to be developed and the thickness of the precoat layer and the ink layer to be formed, which are predetermined according to the type of precoat agent and glitter ink to be used. It can be determined by referring to the obtained correspondence table. Alternatively, the thickness of the ink layer is determined by causing a processing device that has undergone machine learning to calculate the relationship between the degree of gloss to be developed and the thickness of the precoat layer and the ink layer to be formed. can do.

Specifically, depending on the solid content concentration of the glitter ink, the size of the dots to be formed, and the like, when applying a droplet of the precoat agent discharged from the nozzle of the inkjet head to the surface of the substrate, The thickness of the ink layer to be formed may be adjusted by changing the size of the droplet (droplet amount), the number of droplets applied to each dot (number of droplets), and the like.

Further, at this time, the amount of the glitter ink applied may be adjusted so that the size of the dots formed by the glitter ink applied is substantially the same as the size of the dots formed by the precoat agent.

2. Second Embodiment In the second embodiment of the present invention, after a precoat layer and an ink layer are formed in the same manner as in the first embodiment described above, an overcoat agent is used on the surface of the ink layer. The present invention relates to an image forming method for forming a coat layer. The overcoat agent may be any overcoat agent such as water-based, solvent-based, and actinic ray curable types, but facilitates control of the film thickness by curing before the overcoat agent is too wet and spreads, and From the viewpoint of facilitating the thickening of the film thickness, it is an actinic ray curable overcoat agent capable of forming a plurality of layers by repeating the step of applying to the surface of the substrate and curing. Is preferred.

The method for applying the overcoat agent is not particularly limited, and the overcoat agent may be applied to the surface of the ink layer using a roll coater or a spin coater, or spray coating, dipping method, screen printing, gravure printing. The overcoat agent may be applied to the surface of the ink layer by a method such as offset printing, or the overcoat agent may be landed on the surface of the ink layer by an inkjet method. Among these, from the viewpoint of forming a finer recorded matter, screen printing and an inkjet method are preferable, and an inkjet method is more preferable.

At this time, by changing the film thickness of the overcoat layer formed by the applied overcoat agent independently for each dot, the gloss of the image formation can be further changed independently for each dot. Further, it is possible to form an image in which the gloss is changed with higher accuracy. Thus, the film thickness of the overcoat layer corresponding to one dot contained in the ink layer (specifically, the portion of the overcoat layer located immediately below the one dot) and the above By setting the thickness of the overcoat layer corresponding to other dots contained in the ink layer (specifically, the portion of the overcoat layer located immediately below the other dots) to a different thickness. The peak height (H) and the peak half-value width (W) in the distribution information are different between the area containing the one dot and the area containing the other dot, , Different degrees of gloss can be perceived. In addition, by applying the overcoat agent by an ink jet method, it is possible to change the thickness of the overcoat layer for each dot and form an image in which the perceived gloss is changed with higher accuracy.

Specifically, the film thickness of the overcoat layer is determined by the number of times the precoat agent is applied to form the precoat layer, and when the droplets of the overcoat agent discharged from the nozzles of the inkjet head are applied to the surface of the ink layer. The droplet size (droplet amount) and the number of droplets applied to each dot (number of droplets) can be adjusted. For example, the film thickness of the precoat layer can be changed for each corresponding dot included in the ink layer by changing the number of times the precoat layer is formed or the number of droplets and the number of droplets for each region in the image. it can.

The amount of droplets of the overcoat agent (when applied by the ink jet method) is preferably adjusted in the range of 0.5 pl to 50 pl, and in order to form a high-definition image, 0.5 pl or more It is more preferable to adjust in the range of 20 pl or less, and it is still more preferable to adjust in the range of 0.5 pl or more and 10 pl or less.

The number of droplets of the overcoat agent (when applied by the inkjet method) is preferably adjusted in the range of 0 to 10 drops, more preferably adjusted in the range of 0 to 5 drops. preferable.

The drive frequency when discharging the overcoat agent (when applied by the inkjet method) from the nozzle of the inkjet head is preferably adjusted in the range of 5 kHz to 100 kHz, and adjusted in the range of 5 kHz to 20 kHz. Is more preferable.

In the present embodiment, the peak height (H) in the distribution information is obtained by independently changing the film thickness of the overcoat layer provided with an overcoat agent and cured by irradiation with actinic rays for each dot. In addition, the half width (W) of the peak is changed for each dot.

Specifically, by increasing the film thickness of the overcoat layer, the amount of specularly reflected light emitted from the dots can be reduced, and the gloss can be adjusted to slightly reduce the peak height (H). Furthermore, by increasing the film thickness of the overcoat layer, the surface of the dots is adjusted to be rougher, making it less likely to concentrate the light emitted from the dots due to the specularly reflected light, thereby increasing the peak half-value width (W). Can be adjusted to widen.

The film thickness of the overcoat layer may be set according to the degree of gloss to be formed by the dots.

The film thickness of the overcoat layer can also be changed by the time from when the overcoat agent is ejected and landing on the surface of the substrate until irradiation with actinic rays, the composition of the precoat agent and the glitter ink, and the like. it can. Based on these conditions, the application amount of the overcoat agent may be adjusted so that a desired level of gloss can be obtained.

The overcoat layer may contain a non-brilliant color material. The non-brilliant colorant can be a known pigment or dye used to form an image exhibiting yellow, red or magenta, blue or cyan and black, and other features. When the overcoat layer contains a non-brilliant color material, a color can be imparted to the gloss formed, and various gloss colors such as red silver, blue silver, and gold can be expressed.

2-1. Precoat agent and overcoat agent Since the precoat agent and the overcoat agent can be the same as the precoat agent used in the first embodiment, detailed description thereof is omitted.

Note that the precoat agent and the overcoat agent used to form the same dot may have the same composition or different compositions.

The overcoat agent may contain a non-brilliant color material.

The non-brilliant color material includes a non-brilliant dye and a non-brilliant pigment.

From the viewpoint of obtaining an image having good weather resistance, the non-brilliant colorant is preferably a non-brilliant pigment. The non-brilliant pigment can be selected from, for example, a yellow (yellow) pigment, a red or magenta pigment, a blue or cyan pigment, a green pigment, and a black pigment depending on the color of an image to be formed. In addition, pigments such as pink, green and orange for forming other special colors may be used.

Examples of yellow pigments include C.I. I. Pigment Yellow (hereinafter, also simply referred to as “PY”) , PY110, PY137, PY138, PY139, PY153, PY154, PY155, PY157, PY166, PY167, PY168, PY180, PY185, and PY193.
Examples of red or magenta pigments include C.I. I. Pigment Red (hereinafter also referred to simply as “PR”) 3, PR5, PR19, PR22, PR31, PR38, PR43, PR48: 1, PR48: 2, PR48: 3, PR48: 4, PR48: 5, PR49: 1 PR53: 1, PR57: 1, PR57: 2, PR58: 4, PR63: 1, PR81, PR81: 1, PR81: 2, PR81: 3, PR81: 4, PR88, PR104, PR108, PR112, PR122, PR123 PR144, PR146, PR149, PR166, PR168, PR169, PR170, PR177, PR178, PR179, PR184, PR185, PR208, PR216, PR226, and PR257, C.I. I. Pigment Violet (hereinafter also simply referred to as “PV”) 3, PV19, PV23, PV29, PV30, PV37, PV50, and PV88, and C.I. I. Pigment Orange (hereinafter, also simply referred to as “PO”) 13, PO16, PO20, and PO36.
Examples of blue or cyan pigments include C.I. I. Pigment Blue (hereinafter also referred to simply as “PB”) 1, PB15, PB15: 1, PB15: 2, PB15: 3, PB15: 4, PB15: 6, PB16, PB17-1, PB22, PB27, PB28, PB29 , PB36, and PB60.
Examples of green pigments include C.I. I. Pigment Green (hereinafter also simply referred to as “PG”) 7, PG26, PG36, PG50, and the like.
Examples of black pigments include C.I. I. Pigment Black (hereinafter also simply referred to as “PBk”) 7, PBk26, PBk28, and the like.

2-2. Glossy ink As the glitter ink, the same glitter ink as that used in the first embodiment can be used.

2-3. Image Forming Method FIG. 3 is a flowchart of the image forming method according to this embodiment. In the present embodiment, a precoat layer is formed in contact with the surface of the substrate using the precoat agent (step S110), and an ink layer is formed in contact with the surface of the precoat layer using the glitter ink (step S120). Further, an ink layer is formed using the overcoat agent (step S130).

2-3-1. Formation of precoat layer (step S110)
Since the precoat layer can be formed in the same manner as in the first embodiment, detailed description thereof is omitted.

At this time, the film thickness of the precoat layer to be formed is adjusted according to the degree of gloss to be developed in the region including the corresponding dots included in the ink layer. The film thickness of the precoat layer is determined in advance according to the kind of precoat agent, glitter ink and overcoat agent to be used, the degree of gloss to be expressed, and the precoat agent, glitter ink and overcoat agent to be formed. It is possible to determine by referring to a correspondence table obtained in advance for the relationship between the amount and the amount to be added. Alternatively, the film thickness of the precoat layer is calculated by calculating the relationship between the degree of gloss to be developed and the film thickness of the precoat agent, glitter ink, and overcoat agent to be formed by a processing device that has undergone machine learning or the like. Then, the application amount of the precoat agent for forming the precoat layer having the film thickness can be calculated or determined.

2-3-2. Formation of ink layer (step S120)
Since the ink layer can be formed in the same manner as in the first embodiment, detailed description thereof is omitted.

At this time, the film thickness of the ink layer to be formed is adjusted according to the degree of gloss to be developed in the region including the dots formed by the applied glittering ink. The thickness of the ink layer is determined according to the type of precoat agent, glitter ink and overcoat agent used, the degree of gloss to be expressed, and the precoat agent, glitter ink and overcoat agent to be formed. It is possible to determine by referring to a correspondence table obtained in advance for the relationship between the given amount and. Alternatively, the film thickness of the ink layer is calculated by calculating the relationship between the degree of gloss to be developed and the film thickness of the precoat agent, glitter ink and overcoat agent to be formed by a processing device that has undergone machine learning or the like. Then, the application amount of the precoat agent for forming the precoat layer having the film thickness can be calculated or determined.

2-3-3. Formation of overcoat layer (step S130)
Thereafter, the overcoat agent is applied to the surface of the dots formed by the glitter ink constituting the ink layer to form an overcoat layer.

At this time, the film thickness of the overcoat layer to be formed is adjusted according to the degree of gloss to be developed in the region including the corresponding dots included in the ink layer. The film thickness of the overcoat layer is determined in accordance with the type of precoat agent, glitter ink and overcoat agent used, the degree of gloss to be expressed, the precoat agent to be formed, glitter ink and overcoat. It can be determined by referring to a correspondence table in which the relationship between the applied amount of the agent and the agent is obtained in advance. Alternatively, the film thickness of the overcoat layer is calculated by calculating the relationship between the degree of gloss to be developed and the film thickness of the precoat agent, glitter ink, and overcoat agent to be formed on a machine that has undergone machine learning. Then, the application amount of the precoat agent for forming the precoat layer having the film thickness can be calculated or determined.

Specifically, when the droplet of the overcoat agent discharged from the nozzle of the inkjet head is applied to the surface of the substrate, the size of the droplet (droplet amount) and the number of droplets to be applied to each dot ( The film thickness of the overcoat layer formed may be adjusted by the number of droplets) or the number of times screen printing is repeated.

When the overcoat agent is applied to the substrate by the inkjet method, the ejection method from the inkjet head may be either an on-demand method or a continuous method. On-demand inkjet heads include electro-mechanical conversion methods such as single cavity type, double cavity type, bender type, piston type, shear mode type and shared wall type, as well as thermal inkjet type and bubble jet. Any of electric-thermal conversion methods such as Canon Inc. registered trademark) may be used.

At this time, the temperature of the overcoat agent to be discharged may be adjusted by heating the ink flow path. The temperature of the overcoat agent to be discharged is not particularly limited, but is preferably 50 ° C. or higher and 90 ° C. or lower.

Also, the resolution of the formed image can be adjusted by adjusting the discharge condition of the overcoat agent. The resolution of the formed image can be 600 dpi or more and 1440 dpi or less, but from the viewpoint of forming a higher-definition image, it is preferably 1200 dpi or more and 1440 dpi or less.

Thereafter, the overcoat layer is formed by irradiating the droplets of the overcoat agent landed on the surface of the ink layer with actinic rays or drying the precoat agent applied to the substrate to cure the overcoat agent. Form.

The irradiation conditions of actinic rays can be appropriately set according to the composition of the overcoat agent. For example, a light source having a UV LED, the maximum illuminance on the surface of the droplet on the substrate is 0.5 W / cm ² or more 10.0 W / cm ² or less, more preferably 1W / cm ² or more 5W / cm ² or less and It can be installed so that.

In this embodiment, an image having a precoat layer, an ink layer, and an overcoat layer is formed. However, according to the gloss of the image to be formed, the precoat layer is not formed and the ink layer and the overcoat layer are provided. An image may be formed (see FIG. 4). Also in this case, by changing the film thickness of the overcoat layer independently for each dot, the peak height (H) and peak half-value width (W) in the distribution information can be changed for each dot. .

Hereinafter, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited thereto.

1. 1. Preparation of glitter ink 1-1. Preparation of silver nanoparticle dispersion liquid To a 1 L separable flask having a flat stirring blade and baffle plate, 8.6 g of DISPERBYK-190 (manufactured by BYK Chemie) and 269 g of ion-exchanged water were added and stirred. Go to dissolve DISPERBYK-190. Subsequently, 55 g of silver nitrate dissolved in 269 g of ion exchange water was added to the separable flask while stirring. Further, 70 g of ammonia water was added and stirred, and then the separable flask was placed in a water bath and heated and stirred until the temperature of the solution was stabilized at 80 ° C. Thereafter, 144 g of dimethylaminoethanol was added to the separable flask, and the mixture was further stirred for 6 hours while maintaining at 80 ° C. to obtain a reaction solution containing silver nanoparticles.

The obtained reaction solution was put into a stainless cup, and 2 L of ion exchange water was further added, and then the pump was operated to perform ultrafiltration. When the solution in the stainless cup decreased, ion-exchanged water was added again, and purification was repeated until the filtrate had a conductivity of 100 μS / cm or less. Thereafter, the filtrate was concentrated to obtain a silver nanoparticle dispersion having a solid content of 30 wt%.

The ultrafiltration device used was an ultrafiltration module AHP1010 (manufactured by Asahi Kasei Co., Ltd., molecular weight cut-off: 50000, number of membranes used: 400) and a tube pump (manufactured by Masterflex) connected by a Tygon tube .

1-2. Preparation of emulsion resin particle dispersion 10 parts by weight of terephthalic acid as acid component, 190 parts by weight of isophthalic acid and 170 parts by weight of adipic acid, and 32 parts by weight of ethylene as glycol component in a flask equipped with a dehydrator After adding glycol and 510 parts by mass of neopentyl glycol and adding 0.2 parts by mass of tetraisopropyl titanate as a reaction catalyst, the condensation reaction is carried out at 220 ° C. until the acid value is 1.0 or less and the water content is 0.05% or less. To obtain polyester glycol.

In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 488 parts by mass of the obtained polyester glycol, 13 parts by mass of trimethylolpropane, 88 parts by mass of dimethylolpropionic acid, 252 Part by mass of isophorone diisocyanate and 670 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer. The solution was cooled to 40 ° C. and neutralized by adding 40 parts by mass of triethylamine. Thereafter, 1850 parts by mass of ion-exchanged water was gradually added, emulsified and dispersed using a homogenizer, and stirred for 1 hour. The solvent was removed at 50 ° C. under reduced pressure, and ion-exchanged water was further added to obtain an emulsion resin particle dispersion made of polyurethane having a nonvolatile content of about 20%.

1-3. Preparation of glitter ink 1 to glitter ink 3 (shin glitter ink 1)
The following components were mixed in the following composition to obtain glitter ink 1.
Silver nanoparticle dispersion 5 parts by weight Emulsion resin particle dispersion 0.35 parts by weight Water 59.2 parts by weight Propylene glycol 10 parts by weight Triethylene glycol monomethyl ether 25.4 parts by weight Surfactant (BYK-348: manufactured by Big Chemie) 0.1 parts by mass

(Bright ink 2)
A glittering ink 2 was obtained in the same manner as the glittering ink 1 except that the blending amount of the silver nanoparticle dispersion was 2.5 parts by mass and the blending amount of the emulsion resin particle dispersion was 0.18 parts by weight. .

(Bright ink 3)
The glittering ink 3 was obtained in the same manner as the glittering ink 1 except that the blending amount of the silver nanoparticle dispersion was 1.2 parts by mass and the blending amount of the emulsion resin particle dispersion was 0.09 parts by weight. .

(Glitter ink 4)
A glittering ink 4 containing an aluminum pigment was obtained by the method described in JP-A-2005-123456.

2. Preparation of precoat agent and overcoat agent (Precoat agent 1 and overcoat agent 1)
The following components were mixed in the following composition to obtain Precoat Agent 1 and Overcoat Agent 1. The precoat agent 1 and the overcoat agent 1 have the same composition.
Polyethylene glycol # 400 diacrylate 34 parts by weight 4EO-modified pentaerythritol tetraacrylate 23 parts by weight 6EO-modified trimethylolpropane triacrylate 31 parts by weight Photopolymerization initiator (diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (DAROCUR TPO, BASF)))
7 parts by weight Sensitization aid (p-dimethylaminobenzoic acid ethyl ester (Kayacure EPA, Nippon Kayaku Co., Ltd.))
2 parts by weight Surfactant (KF-352: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1 parts by weight

(Precoat agent 2)
The following components were mixed in the following composition to obtain Precoat Agent 2.
Polyester emulsion (Toyobo Co., Ltd., Vironal MD1500 (solid content 30 wt%))
17.5 parts by weight Triethylene glycol monomethyl ether 8 parts by weight Propylene glycol 2 parts by weight Water 12.5 parts by weight

(Overcoat agent 2)
9 parts by mass of Ajisper PB824 and 71 parts by mass of tripropylene glycol diacrylate were placed in a stainless beaker and dissolved by heating and stirring for 1 hour while heating on a 65 ° C. hot plate.

After cooling the above solution to room temperature, 20 parts by mass of Pigment Yellow 180 (Chromofine Yellow 6280JC, manufactured by Dainichi Seika Co., Ltd.) was added and sealed in a glass bottle with 200 g of zirconia beads having a diameter of 0.5 mm. This was subjected to a dispersion treatment for a predetermined time (pigment 1: 5 hours) with a paint shaker, and then the zirconia beads were removed to obtain a pigment dispersion.

12 parts by weight of the obtained pigment dispersion was added to the overcoat agent 1, heated to 80 ° C. and stirred. The obtained solution was filtered through a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVATEC under heating to obtain an overcoat agent 2.

3. Image formation 3-1. Substrate Images were formed on the following substrates.
Base material 1: OK top coat paper (surface roughness Ra: 0.25 μm)
Base material 2: coated paper (surface roughness Ra: 0.43 μm)
Base material 3: PET film (surface roughness Ra: 0.05 μm)

3-2. Formation of Precoat Layer Precoat Agent 1 or Precoat Agent 2 was loaded into an ink jet recording apparatus having an ink jet head equipped with a piezo ink jet nozzle. The ink jet recording apparatus has an ink tank, an ink supply pipe, an ink supply tank immediately before the ink jet head, a filter, and a piezo type ink jet head in this order from the upstream side to the downstream side where the ink flows. . Using an ink jet head having a droplet amount of 7 pl, it was driven under the conditions of a printing speed of 0.5 m / sec and an injection frequency of 10.5 kHz, and droplets of the precoat agent were discharged and landed on the substrate.

For the precoat agent 1, after landing, an actinic ray (395 nm, 8 W / cm ² ) was irradiated from an LED lamp with a water cooling unit manufactured by Phoseon Technology to form a precoat layer formed by gathering dots with the precoat agent cured. . The distance from the lamp to the surface of the landed precoat agent was 20 mm.

For the precoat agent 2, after landing, the precoat layer was dried at 60 ° C. for 1 minute to form a precoat layer in which dots with the cured precoat agent were gathered.

At this time, the number of times the droplets of the precoat agent were ejected (number of droplets) was varied between 0 and 7 times. When the number of droplets of the precoat agent ejected (number of droplets) was 0, irradiation with actinic rays was not performed.

3-3. Formation of ink layer Any one of the glitter ink 1 to glitter ink 3 was loaded in the same ink jet recording apparatus used when the precoat layer was formed. Using an inkjet head with a droplet volume of 7 pl, driven under the conditions of a printing speed of 0.5 m / sec and an ejection frequency of 10.5 kHz, droplets of glitter ink are ejected once and landed on the precoat layer. It was.

After landing, the glittering ink was dried at 60 ° C. for about 10 minutes to form an ink layer in which dots formed by the glittering ink were gathered.

3-4. Formation of Overcoat Layer One of the overcoat agent 1 and the overcoat agent 2 was loaded into the same ink jet recording apparatus used when the precoat layer was formed. Using an ink jet head having a droplet amount of 7 pl, driving was performed under conditions of a printing speed of 0.5 m / sec and an ejection frequency of 10.5 kHz, droplets of an overcoat agent were ejected and landed on the ink layer.

After landing, an active ray (395 nm, 8 W / cm ² ) was irradiated from an LED lamp equipped with a water cooling unit manufactured by Phoseon Technology to form an overcoat layer in which dots over which the overcoat agent was cured gathered. The distance from the lamp to the surface of the landed overcoat agent was 20 mm.

3-5. Formation conditions of each layer 3-5-1. Sample 1 to Sample 4
The glitter ink 1 is used as the glitter ink, the substrate 1 is used as the substrate, the thickness of the ink layer is fixed to 0.2 μm, and the discharge conditions of the precoat agent 1 are 4 levels from 0 drop (not discharged) to 3 drops. Then, image formation was carried out by changing the number of samples, and Samples 1 to 4 were obtained, respectively.

3-5-2. Sample 5 to Sample 6
Sample 5 and Sample 6 were obtained in the same manner as Sample 3, except that the thickness of the ink layer was changed using the glitter ink 2 and the glitter ink 3 as the glitter ink.

3-5-3. Sample 7 to Sample 8
Sample 7 and Sample 8 were obtained in the same manner as Sample 3, except that the overcoat agent 1 was used as the overcoat agent and the overcoat agent discharge conditions were 1 drop and 2 drop.

3-5-4. Sample 9 to Sample 10
Sample 9 and Sample 10 were obtained in the same manner as Sample 1, except that the overcoat agent 1 was used as the overcoat agent and the overcoat agent discharge conditions were 1 drop and 2 drop.

3-5-5. Sample 11 to Sample 14
Samples 11 to 14 were obtained in the same manner as Samples 1 to 4 except that the substrate 2 was used as the substrate.

3-5-6. Sample 15 to Sample 17
Samples 15 to 17 were obtained in the same manner as Samples 1 to 3, except that the substrate 3 was used as the substrate.

3-5-7. Sample 18 to Sample 20
In three regions set on the same surface of the same base material (base material 1), images were formed adjacent to each other in the same manner as Samples 1 to 3, and a gradation image was obtained. Of the three regions on which the image is formed on the same substrate, the region where the image is formed in the same manner as in sample 1 is the sample 18, and the region where the image is formed in the same manner as in sample 2 is the same as in sample 19 and sample 3. The area where the image was formed was designated as Sample 20.

3-5-8. Sample 21 to Sample 23
Samples 21 to 23 were obtained in the same manner as Sample 2, Sample 3 and Sample 7, except that the glitter ink 4 was used as the glitter ink.

3-5-9. Sample 24 to Sample 25
Samples 24 to 25 are the same as Sample 9 except that the overcoat agent 2 is used as the overcoat agent, the discharge conditions of the precoat agent 1 are 1 drop and 2 drop, and the discharge conditions of the overcoat agent 2 are 2 drops. Got.

3-5-10. Sample 26
Sample 26 was obtained in the same manner as Sample 1, except that the precoat agent 1 was discharged at 9 drops.

3-5-11. Sample 27 to Sample 28
Samples 27 to 28 were obtained in the same manner as Samples 5 to 6 except that the drive frequency was 21 kHz.

3-5-12. Sample 29
Sample 29 was obtained in the same manner as Sample 1, except that a precoat layer having a thickness of 10 μm was formed by screen printing.

3-5-13. Sample 30 to Sample 31
Sample 30 and sample 31 were obtained in the same manner as in sample 2, except that precoat agent 2 was used as the precoat agent and the discharge conditions of precoat agent 1 were 1 drop and 2 drop.

Note that Sample 1 to Sample 17 and Sample 21 to Sample 31 are samples in which one image is formed on the surface of a different base material. Samples 18 to 20 are samples in which images are formed in different regions set on the surface of one base material, and three images (samples) are formed on one base material.

4). Evaluation The image in each sample was cut into a size of 15 mm × 50 mm. Using a variable angle photometer (product name: GCMS-4, manufactured by Murakami Color Research Laboratory Co., Ltd.), illuminate each gloss value measurement method sample with incident light at an incident angle of 45 ° while changing the light receiving angle. Then, the reflection intensity from 0 ° to 50 ° was measured every 5 °. The reflectance was calculated from the obtained reflection intensity at each light receiving angle, and a spatial distribution profile of reflection indicating the relationship between the light receiving angle and the reflectance was obtained.

The shape of the spatial distribution profile of the obtained reflection is fitted to one Lorentz function, and the peak height (H), peak is determined by the least square method and Solver (registered trademark) of Microsoft Excel (registered trademark). The full width at half maximum (W) and the height of the baseline (B) were determined.

Table 1 and Table 2 show the formation conditions and evaluation results for each sample. In Tables 1 and 2, “PC agent” is the type of precoat agent used for image formation, “ink” is the type of glitter ink used for image formation, and “OC agent” is used for image formation. The types of overcoat agents made are shown respectively.

In the distribution information of the lightness or reflection intensity with respect to the light receiving angle obtained by measuring the reflected light formed by reflecting the measurement light irradiated on the formed image by changing the film thickness of the precoat layer and the ink layer, The peak height (H) and baseline height (B) of brightness or reflection intensity could be varied. Specifically, when the applied amount of the precoat agent is changed to increase the thickness of the precoat layer to be formed, the peak height (H) in the distribution information is increased, and the base height (B) is increased. It could be lowered (Sample 1 to Sample 4). Further, when the solid content concentration of the glitter ink is changed to increase the thickness of the ink layer to be formed, the peak height (H) in the distribution information is increased, and the base height (B) is increased. High (Sample 3, Sample 5, Sample 6).

Furthermore, by changing the film thickness of the overcoat layer, it was possible to change the peak height (H) and peak half-value width (W) of the lightness or reflection intensity in the distribution information. Specifically, when the applied amount of the overcoat agent is changed to increase the thickness of the overcoat layer to be formed, the peak height (H) in the above distribution information is lowered, and the peak half width (W ) Could be made wider. This tendency was the same when the precoat layer was formed (Sample 3, Sample 7, Sample 8) and when the precoat layer was not formed (Sample 1, Sample 9, Sample 10).

Even if images are similarly formed on substrates having different surface roughness Ra, the peak height in the above distribution information can be increased by changing the applied amount of the precoat agent and increasing the thickness of the precoat layer to be formed. (H) was higher and the base height (B) was lower (Sample 11 to Sample 17).

In addition, by forming a plurality of regions having different thicknesses of the precoat layer adjacent to different regions included in the same surface of the same substrate, a plurality of regions having different glosses can be formed adjacent to each other. (Sample 18 to Sample 20).

Further, not only in the case of using metal nanoparticles but also when using a known aluminum pigment, if the thickness of the precoat layer formed is increased, the peak height (H) in the above distribution information is increased, and the height of the base is increased. (B) can be made lower (sample 21, sample 22), and when the overcoat layer formed is made thicker, the peak height (H) in the above distribution information becomes lower, and the peak half The value width (W) could be made wider (Sample 22, Sample 23).

Furthermore, by adding a color material to the overcoat layer, a yellow colored glossy image could be formed. Also at this time, if the applied amount of the precoat agent is changed to increase the thickness of the precoat layer to be formed, the peak height (H) in the distribution information is increased, and the base height (B) is increased. It could be lowered (Sample 24, Sample 25).

Also, by changing the thickness of the precoat layer, the height from the base material to the image surface could be changed to form an embossed image (Sample 26).

In addition, by changing the emission frequency and changing the number of dots formed per unit area, it was possible to form an image in which the gloss was changed while changing the density (sample 3, sample). 27, sample 28).

In addition, even when the precoat layer was formed by screen printing, an image having the same glossiness as that obtained when the precoat layer having substantially the same film thickness was prepared by the inkjet method (sample 14) could be obtained (sample 29). .

In addition, when a precoat layer is formed by an ink jet method using a precoat agent as a water-based ink, increasing the thickness of the precoat layer to be formed increases the peak height (H) in the above distribution information and increases the base height. (B) could be further reduced (Sample 30 to Sample 31). Note that the gloss index (particularly the peak height (H) and the base height in the above distribution information) between the sample 30 and the sample 31 using the precoat agent 2 and the sample 2 and the sample 3 using the precoat agent 1 is used. (B)) is different because the thickness of the precoat layer formed per drop of these precoat agents is different.

This application claims priority based on Japanese Patent Application No. 2018-1212756 filed on June 13, 2018, and the contents described in the claims, specification and drawings of this application are Incorporated into the application.

The image forming method of the present invention can express various metallic luster depending on the formed image. Therefore, the present invention is expected to expand the range of application of glittering recorded materials and contribute to the advancement and spread of technology in the same field.

Claims

Applying a precoat agent to the surface of the substrate and forming a precoat layer;
A step of applying a glittering ink containing a glittering pigment to the surface of the precoat layer by an inkjet method to form an ink layer in which dots formed by the glittering ink are assembled;
An image forming method comprising:
The film thickness of the precoat layer or the ink layer corresponding to one dot contained in the ink layer,
The thickness of the precoat layer or the ink layer corresponding to the other dots contained in the ink layer is different from the thickness,
The height of the lightness or reflection intensity peak reflected by the formed image and the height of the baseline are set to different values in the region including the one dot and the region including the other dot,
Image forming method.
The image forming method according to claim 1, wherein the film thickness of the ink layer is changed independently for each dot included in the ink layer.
The step of forming the precoat layer is a step of applying the precoat agent to the surface of the substrate by an ink jet method and forming a precoat layer in which dots formed by the applied precoat agent are gathered. ,
The step of forming the ink layer is a step of applying the glitter ink to the surface of the dots constituting the precoat layer.
The image forming method according to claim 1.
4. The image forming method according to claim 3, wherein the film thickness of the precoat layer is changed independently for each of the dots constituting the precoat layer.
The image forming method according to any one of claims 1 to 4, wherein the precoat agent is an actinic ray curable precoat agent.
Furthermore, it includes a step of forming an overcoat layer by applying an overcoat agent to the surface of the dots constituting the ink layer,
A film thickness of the overcoat layer corresponding to forming the one dot;
The thickness of the overcoat layer corresponding to the formation of the other dots, and a different thickness,
The height of the lightness or reflection intensity peak and the half width of the peak are different values in the region including the one dot and the region including the other dot,
The image forming method according to any one of claims 1 to 5.
Applying a glittering ink containing a glittering pigment to the surface of the substrate by an inkjet method, and forming an ink layer in which dots formed by the glittering ink are assembled; and
Providing an overcoat agent on the surface of the dots constituting the ink layer, and forming an overcoat layer;
An image forming method comprising:
The film thickness of the ink layer and the overcoat layer corresponding to one dot contained in the ink layer,
The thicknesses of the ink layer and the overcoat layer corresponding to other dots included in the ink layer are different thicknesses,
The value of the peak of the brightness or reflection intensity of the reflected light reflected by the formed image and the half-value width of the peak are different values for the region including the one dot and the region including the other dot. And
Image forming method.
In the step of forming the overcoat layer, the overcoat agent is applied to the surface of the dots constituting the ink layer by an inkjet method, and the dots formed by the applied overcoat agent are assembled. A step of forming an overcoat layer;
The image forming method according to claim 6 or 7.
The image forming method according to claim 8, wherein the film thickness of the overcoat agent is independently changed for each of the dots constituting the overcoat layer.
The image forming method according to any one of claims 6 to 9, wherein the overcoat agent is an actinic ray curable overcoat agent.
The image forming method according to any one of claims 6 to 10, wherein the overcoat agent contains a non-brilliant color material.
12. The image forming method according to claim 1, wherein the one dot and the other dot are applied to the same surface of the same substrate.
Forming a plurality of regions having different numbers of dots formed per unit area;
The image forming method according to any one of claims 1 to 12.
A plurality of the one dots are formed, and one region having gloss expressed by the plurality of the one dots;
A plurality of the other dots are formed, and other regions having gloss expressed by the plurality of other dots,
Forming adjacent to each other,
The image forming method according to any one of claims 1 to 13.
The image forming method according to any one of claims 1 to 14, wherein the glitter pigment is a metal nanoparticle.