JP2012210764A - Inkjet recording method and printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording method capable of obtaining an image having superior metallic appearance (photoluminescence) and having superior abrasion durability, and to provide the printed matter obtained by the above method.SOLUTION: The inkjet recording method includes, in order: an image forming step of forming an image by discharging an effect pigment ink on a recording medium; a transparent ink application step of applying a transparent ink on the recording medium; and a curing step of curing the effect pigment ink and the transparent ink on the recording medium. The inkjet recording method does not have a step of curing the transparent ink between the image forming step and the transparent ink application step, or if it has, the curing rate of the transparent ink is ≤85%. The transparent ink includes a polymerization initiator and a polymerizable compound, and the effectively includes no pigments, and the effect pigment ink includes an effect pigment, a polymerization initiator and a polymerizable compound.

Description

  The present invention relates to an inkjet recording method and a printed matter.

  An ink jet system that ejects an ink composition as droplets from an ink ejection port is small and inexpensive, and is used in many printers because it can form an image without contact with a recording medium. Among these inkjet methods, the piezo inkjet method that ejects ink using deformation of a piezoelectric element and the thermal inkjet method that ejects droplets of an ink composition using the boiling phenomenon of the ink composition due to thermal energy are high resolution. It has a feature that it is excellent in high-speed printability.

Recently, not only photo printing and document printing for home use or office use, but also commercial printing equipment and industrial printing equipment using an ink jet printer have been developed. In particular, the demand for wide format inkjet printers suitable for printing large format advertisements to be attached to show windows, station passages, and walls such as buildings is growing rapidly.
Compared to conventional inkjet ink for home or office use, ink used in wide format inkjet printers also has adhesion to non-permeable recording media such as plastic, and during processing such as bending and cutting There is a strong demand for prints to be free from failures such as cracking and peeling. In addition, since the printed material may be installed outdoors, the pigment used is required to have excellent weather resistance. In addition, wide format inkjet printers are often used for advertising and display applications compared to small inkjet printers widely used for conventional photo printing and document printing. Characteristics are required. For example, inkjet printers capable of printing with metallic and pearl effects are attracting attention.

  On the other hand, techniques for imparting gloss to ink have been proposed. Patent Document 1 discloses a metallic ink composition containing a metal pigment, and at least one photocurable ink composition selected from the group consisting of a chromatic ink composition, a black ink composition, and a white ink composition; , An ink set is disclosed. Patent Document 2 discloses a liquid that hardens when irradiated with light, and forms dots by ejecting a liquid containing a metal pigment onto a medium, and applies an electric field to the dots. A liquid jet recording method is disclosed that includes irradiating light to the dot on which the electric field is applied.

JP 2008-239951 A JP 2010-214804 A

  An object of the present invention is to provide an ink jet recording method capable of obtaining an image having excellent metallic feeling (brightness) and excellent scratching properties. Furthermore, the other object of this invention is to provide the printed matter obtained by the said method.

The above-described problems of the present invention have been solved by means described in the following <1> and <19>. It is described below together with <2> to <18> which are preferred embodiments.
<1> An image forming step of forming an image by ejecting an effect pigment ink on a recording medium, a transparent ink applying step of applying a transparent ink on the recording medium, and an effect pigment ink and a transparent on the recording medium A curing process for curing the ink in this order, and there is no or no effect pigment ink curing process between the image forming process and the transparent ink application process. The transparent ink contains a polymerization initiator and a polymerizable compound and does not substantially contain a pigment. The effect pigment ink contains an effect pigment and a polymerization start. An ink jet recording method comprising an agent and a polymerizable compound,
<2> Between the image forming step and the transparent ink application step, the step of curing the effect pigment ink is not included, or when it is included, the curing rate of the effect pigment ink is 60% or less. <1> the inkjet recording method according to
<3> The inkjet recording method according to <1> or <2>, wherein in the transparent ink application step, the transparent ink is applied so as to overlap with the effect pigment ink applied on the recording medium,
<4> The transparent ink application step according to any one of <1> to <3>, wherein the transparent ink is applied so as to cover a region to which the effect pigment ink is applied on the recording medium. Inkjet recording method,
<5> The inkjet recording method according to any one of <1> to <4>, wherein the effect pigment is a tabular particle, and the shape of the effect pigment satisfies the following formulas (1) and (2):
0.5 μm ≦ R ₅₀ ≦ 5 μm (1)
R ₅₀ / d> 5 (2)
(In Formula (1) and Formula (2), R ₅₀ is the 50% average particle diameter in the equivalent circle diameter determined from the plane area of the particles, and d is the plate thickness.)
<6> The inkjet recording method according to any one of <1> to <5>, wherein the effect pigment is a metal pigment or a pearl pigment,
<7> The inkjet recording method according to any one of <1> to <6>, wherein the effect pigment is a tabular grain formed from a thin multilayer.
<8> The inkjet recording method according to any one of <1> to <7>, wherein a material of the effect pigment is aluminum or an aluminum alloy.
<9> The inkjet according to any one of <1> to <8>, wherein the following effect is satisfied when the surface tension of the effect pigment ink is γk and the surface tension of the transparent ink is γs. Recording method,
−10 mN / m ≦ γs−γk ≦ 5 mN / m (3)
<10> The inkjet according to any one of <1> to <9>, which satisfies the following formula (4) when the surface tension of the effect pigment ink is γk and the surface tension of the transparent ink is γs: Recording method,
30 mN / m ≦ γs <γk ≦ 40 mN / m (4)
<11> The effect pigment ink according to any one of <1> to <10>, wherein the effect pigment ink contains a polymerizable compound selected from the group consisting of the following group 1 in an amount of 40% by weight or more of the total polymerizable compound. An inkjet recording method,
(Group 1)
N-vinylcaprolactam, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide, tetrahydrofurfuryl acrylate, cyclic trimethylolpropane formal acrylate, 2-phenoxyethyl acrylate, triethylene glycol diacrylate , Tetraethylene glycol diacrylate, trimethylolpropane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate <12> The polymerizable compound selected from the group consisting of the following group 2 is a polymerizable compound selected from the group consisting of 45 below. The inkjet recording method according to any one of <1> to <11>, which is contained by weight% or more,
(Group 2)
N-vinylcaprolactam, 2-phenoxyethyl acrylate <13> The transparent ink contains a polymerizable compound selected from the group consisting of the following group 3 in an amount of 60% by weight or more of the total polymerizable compound: <1> to <1. 12>, the inkjet recording method according to any one of
(Group 3)
Octyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, isophoryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, 1,6-hexanediol diacrylate, 3-methyl-1,5- Pentanediol diacrylate, dipropylene glycol diacrylate, propylene oxide modified trimethylolpropane triacrylate <14> The transparent ink is a polymerizable compound selected from the group consisting of the following group 4: 60% by weight of the total polymerizable compound The inkjet recording method according to any one of <1> to <13>, which is contained above,
(Group 4)
Isobornyl acrylate, isophoryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate <15> The transparent ink further contains a surfactant, according to any one of <1> to <14>. An inkjet recording method,
<16> The inkjet recording method according to <15>, wherein the surfactant is a nonionic surfactant.
<17> The inkjet recording method according to <15> or <16>, wherein the surfactant is a polymer having a poly (meth) acrylate skeleton.
<18> The transparent ink is provided in an upper layer of the effect pigment ink, and a part of the polymerizable compound in the effect pigment ink diffuses into the transparent ink, so that the effect pigment is higher than the initial state of the effect pigment ink. The inkjet recording method according to any one of <1> to <17>, which has a function of maintaining a density state;
<19> Printed matter obtained by the inkjet recording method according to any one of <1> to <18>.

  According to the present invention, it is possible to provide an ink jet recording method capable of obtaining an image excellent in metallic feeling (brightness) and excellent in scratching properties. Furthermore, the printed matter obtained by the above method could be provided.

It is a schematic diagram of a top view and a cross-sectional view when the transparent ink is ejected with overlapping with the cured pigment ink. 1 is a schematic configuration diagram of a shuttle scan type ink jet recording printer. FIG. It is a schematic structure perspective view of the head unit part for inkjet recording. 1 is a schematic configuration diagram of a single-pass inkjet recording printer.

The inkjet recording method of the present invention includes an image forming step of forming an image by ejecting an effect pigment ink on a recording medium, a transparent ink applying step of applying a transparent ink on the recording medium, and a recording medium When there is a curing step for curing the effect pigment ink and the transparent ink in this order, and there is no or no step for curing the effect pigment ink between the image forming step and the transparent ink application step. The curing rate of the effect pigment ink is 85% or less, the transparent ink contains a polymerization initiator and a polymerizable compound, and substantially contains no pigment,
The effect pigment ink contains an effect pigment, a polymerization initiator, and a polymerizable compound.
In the present invention, the description of “A to B” (where A <B) representing a numerical range represents A or more and B or less, and the description of “X to Y” (where X> Y) is X Hereinafter, Y or more is represented. That is, it represents a numerical range including the end points.
Further, in the present invention, the simple description of “ink” includes transparent ink, effect pigment ink, and, if necessary, colored ink.

1. Inkjet recording method The inkjet recording method of the present invention comprises (1) an image forming step of discharging effect pigment ink to form an image, (2) a transparent ink applying step of applying a transparent ink on a recording medium, and ( 3) It has a curing process for curing the effect pigment ink and the transparent ink on the recording medium in this order. The steps (1) to (3) may be repeated a plurality of times.
When ink containing conventional solvent-type effect pigments is used, metallic feeling and pearly feeling (glossiness) can be obtained, but it is not sufficient in terms of scratch resistance. With the ink composition, although scratch resistance was obtained, the metallic feeling and the pearly feeling (glossiness) were not sufficient.
Although the mechanism of action is not clear, the orientation of the effect pigment in the effect pigment ink is enhanced by applying the transparent ink after ejecting the effect pigment ink to form an image, and the metallic feeling and the pearly feeling (glossy feeling). ) And an image excellent in scratch resistance was found.
The presumed mechanism of action is that a part of the polymerizable compound in the effect pigment ink diffuses into the transparent ink due to the transparent ink layer provided on the upper layer of the effect pigment ink, which is higher than the initial state of the effect pigment ink. It is considered that the effect pigment can be maintained in a high concentration state, the arrangement state of the effect pigment is improved, and the glossiness can be improved.

In the present invention, the transparent ink is preferably applied so as to overlap with the effect pigment ink ejected on the recording medium.
FIG. 1 is a schematic diagram of a top view and a cross-sectional view when a transparent ink is applied in an overlapping manner with an effect pigment ink.
In FIG. 1A, the transparent ink droplet S completely covers the effect pigment ink droplet K, and the effect pigment ink droplet K is completely inside the transparent ink droplet S.
On the other hand, in FIGS. 1B and 1C, although there are portions where the effect pigment ink droplet K and the transparent ink droplet S overlap, a part of the effect pigment ink droplet K is transparent. Part of the effect pigment ink is exposed without being covered by the ink droplets S.
Since the portion where the effect pigment ink droplet K and the transparent ink droplet S overlap is excellent in the optical effect (glossiness), as shown in FIG. It is preferable to apply the effect pigment ink and the transparent ink on the recording medium so that the effect pigment ink droplet K is included in the transparent ink droplet S. That is, it is preferable that the transparent ink is applied so as to cover the area where the effect pigment ink is applied on the recording medium.

In order to make the droplets overlap as shown in FIG. 1A, a method of appropriately adjusting the ejection droplet amount of the effect pigment ink and the transparent ink or changing the number of ejection droplets is selected. . It is also effective to adjust so that the center of the droplet on the recording medium on which the effect pigment ink is discharged and the center of the droplet on the recording medium on which the transparent ink is discharged are in the same position.
A method of providing a transparent ink coating layer after discharging the effect pigment ink is also preferable.

In the present invention, it is necessary that the effect pigment ink and the transparent ink overlap with each other in a fluid state. By overlapping in a state having fluidity, an image excellent in optical effects such as metallic feeling and pearl feeling can be obtained.
Therefore, it is preferable not to include a curing process (for example, an ultraviolet irradiation process) of the effect pigment ink between the image forming process and the transparent ink application process. Even when the effect pigment ink is cured, the effect pigment ink has a curing rate of 85% or less, preferably 60% or less, more preferably 50% or less, and 30%. More preferably, it is as follows. By lowering the curing rate and making it more uncured, the fluidity of the effect pigment ink is maintained, the time until the effect pigment is arranged can be shortened, and the printing speed can be improved. Moreover, the image obtained is preferable because it is excellent in optical effect.
Here, the curing rate can be determined as follows by discharging the effect pigment ink onto a non-permeable recording medium and performing a transfer test immediately before the transparent ink application step.
Curing rate = weight remaining on the recording medium immediately before the transparent ink application step / weight on the recording medium immediately after the image forming step × 100
The transfer test is performed by pressing the plain paper against the effect pigment ink on the recording medium for 5 to 10 seconds by applying a force of 5 kg per A4 size and peeling the plain paper.

  Hereinafter, each process will be described.

(1) Image forming step In the present invention, the effect pigment ink is preferably ejected with a droplet size of 0.1 pL (picoliter; the same applies hereinafter) to 100 pL (preferably by an ink jet nozzle). When the droplet size is within the above range, it is effective in that an image with high sharpness can be drawn at a high density and high optical characteristics can be obtained. More preferably, it is 0.5 pL or more and 50 pL or less.
Further, the maximum liquid amount of the effect pigment ink applied on the recording medium is preferably 0.01 g / cm ² or more and 0.200 g / cm ² or less from the viewpoints of glossiness, curability, image surface smoothness, and the like. , preferably 0.02 g / cm ² or more 0.150 g / cm ² or less, 0.03 g / cm ² or more 0.100 g / cm ² or less is particularly preferred.

There is no restriction | limiting in particular as an inkjet recording device used for an image formation process, The well-known inkjet recording device which can achieve the target resolution can be selected arbitrarily and can be used. That is, any known ink jet recording apparatus including a commercially available product can eject the effect pigment ink onto the recording medium in the image forming step of the ink jet recording method of the present invention.
Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and an actinic radiation source.
The ink supply system includes, for example, an original tank containing ink, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type ink jet head is preferably 1 to 100 pL, more preferably 3 to 42 pL, and still more preferably 8 to 30 pL, preferably 300 × 300 to 4,000 × 4,000 dpi, more preferably 400. It can drive so that it can discharge with the resolution of * 400-1600 * 1,600 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

  In the present invention, since it is preferable to set the ejected ink to a constant temperature, an image forming apparatus capable of performing heat insulation and heating is preferably used from the ink supply tank to the inkjet head portion. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping site and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  A radiation curable ink such as the ink of the present invention generally has a higher viscosity than a water-based ink that is usually used as an ink for ink jet recording, and therefore has a large viscosity fluctuation due to a temperature fluctuation during ejection. The ink viscosity fluctuation has a great influence on the change of the droplet size and the change of the droplet discharge speed, and causes the image quality deterioration. Therefore, it is preferable to keep the temperature of the ink during ejection as constant as possible. Therefore, the control range of the ink temperature is preferably ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and still more preferably ± 1 ° C. of the set temperature.

  As means for discharging the effect pigment ink, an ink jet head is preferably used. As an inkjet head, for example, a charge control method that ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezo element, an electric signal is converted into an acoustic beam, and ink is used. A head of an acoustic ink jet method in which ink is ejected by using radiation pressure by irradiating the ink, or a thermal ink jet (bubble jet (registered trademark)) method in which ink is heated to form bubbles and the generated pressure is used is suitable. It is.

(2) Transparent ink application step In the transparent ink application step, the transparent ink is preferably applied to the same region as the image formed by discharging the droplets of effect pigment ink or a region wider than the image.
Further, the application amount (weight ratio per unit area) of the transparent ink is preferably in the range of 0.05 to 5 when the maximum application amount of the effect pigment ink is 1, and 0.07 or more. A range of 4 or less is more preferable, and a range of 0.1 or more and 3 or less is particularly preferable.
Note that “on the recording medium” may be an upper part of the recording medium, and is not necessarily in contact with the recording medium.
It is preferable that the interval from application of the droplet of the effect pigment ink to application of the transparent ink is in the range of 5 μs or more and 10 seconds or less. When the interval until the application of the transparent ink is within the above range, it is effective in that the effect of the present invention can be remarkably exhibited. The interval until the application of the transparent ink is more preferably 10 μs to 5 seconds, and particularly preferably 20 μs to 5 seconds.

In the inkjet recording method of the present invention, a coating device, an inkjet nozzle, or the like can be used as means for applying a transparent ink on a recording medium.
The coating apparatus is not particularly limited and can be appropriately selected from known coating apparatuses according to the purpose, for example, an air doctor coater, a blade coater, a lot coater, a knife coater, a squeeze coater, and an impregnation coater. , Reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, extrusion coater and the like. For details, see Yuji Harasaki's “Coating Engineering”.
Among them, from the viewpoint of the apparatus cost, the application of the transparent ink onto the recording medium is preferably performed by application using a relatively inexpensive bar coater or spin coater, or the ink jet method.

(3) Curing step In the curing step, it is preferable to cure the effect pigment ink and the transparent ink on the recording medium by applying an active energy ray or heat.
As described above, a curing process may be provided after the image forming process, but in order to maintain the fluidity of the effect pigment ink, it may not have a curing process after the image forming process. Preferably, after the image forming step and the transparent ink applying step, it is preferable to have a curing step of curing the effect pigment ink and the transparent ink in a lump.

As the curing means, a light source for irradiating active energy rays, a heater such as an electric heater or an oven, and the like can be selected according to the purpose.
As the active energy ray, in addition to ultraviolet rays, for example, visible light, α ray, γ ray, X ray, electron beam and the like can be used. Of these, the active energy rays are preferably electron beams, ultraviolet rays and visible rays, and ultraviolet rays are particularly preferred from the viewpoint of cost and safety.
Amount of energy required for the curing reaction, the composition, in particular depends on the type and content of the polymerization initiator, it is generally preferred is the extent 100 mJ / cm ² or more 10,000 / cm ² or less.
Suitable devices for irradiating active energy rays include metal halide lamps, mercury lamps, LED light sources and the like.

When using a colored ink in addition to the transparent ink and the effect pigment ink, the color ink may be applied on the recording medium before the image forming process with the effect pigment ink, depending on the desired image. Colored ink may be applied onto the recording medium after the transparent ink application step. Among these, it is preferable to have an image forming step with colored ink before the image forming step with effect pigment ink or after the transparent ink applying step. Among these, it is preferable to discharge the colored ink after the transparent ink application step.
When the colored ink is ejected after the transparent ink applying step, the image forming step with the colored ink is provided after the image forming step with the effect pigment ink and the transparent ink applying step. The effect pigment ink and the transparent ink curing step may be performed after the transparent ink application step, and then the image formation step with the colored ink and the color ink curing step may be performed. The pigment ink, the transparent ink, and the colored ink can be cured at once. It is also preferable to set the curing rate of the transparent ink and effect pigment ink to 10 to 80%. When a plurality of colored inks are used, they may be cured for each color, or may be cured after all the colors have been ejected.

In addition, when using colored ink, it is preferable to use a plurality of colored inks. For example, the colored ink includes four colored inks of yellow, cyan, magenta, and black, and further includes five colored inks including white ink. A colored ink set can also be used. The order of the color inks to be ejected is not particularly limited, but it is preferable to apply the color inks having low brightness to the recording medium. When four colors of yellow, cyan, magenta and black are used, It is preferable to apply on the recording medium in the order of cyan → magenta → black. Further, when using five colored inks in which white is added to the ink, it is preferably applied on the recording medium in the order of white → yellow → cyan → magenta → black.
In order to obtain a full-color image, it is preferable to use four colored inks of yellow, cyan, magenta, and black or five colored inks of yellow, cyan, magenta, black, and white. Furthermore, the present invention is not limited to this, and eight colored inks of cyan, light cyan, magenta, light magenta, gray, black, white, and yellow can also be used.

<Recording medium>
In the present invention, the material used for the recording medium is not particularly limited, and any material may be used. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or deposited. A preferable support includes a polyester film and an aluminum plate. In the present invention, a non-absorbable recording medium is preferably used as the recording medium.

2. Ink set for ink jet recording Hereinafter, an ink set (also referred to as an ink set of the present invention) used in the ink jet recording method of the present invention will be described. The ink set includes at least a transparent ink and an effect pigment ink. The ink set may further include a colored ink, and examples of the colored ink include black, yellow, magenta, cyan, and white inks. The colored ink is not limited to the above-described colors, and may be light color ink such as light cyan and light magenta.

(1) Transparent ink In this invention, a transparent ink contains a polymerization initiator and a polymeric compound, and does not contain a pigment substantially.
Here, the phrase “substantially does not contain a pigment” does not exclude the inclusion of a colorless and transparent pigment or a very small amount that cannot be visually recognized. The allowable amount is preferably 1% by weight or less, particularly preferably not contained, based on the total weight of the transparent ink.
As will be described later, the transparent ink preferably contains a sensitizer, and particularly preferably contains a sensitizer represented by the formula (I) described later. The transparent ink preferably contains a surfactant.

(2) Effect pigment ink In the present invention, the effect pigment ink contains an effect pigment, a polymerization initiator, and a polymerizable compound.

(3) Colored ink In the inkjet recording method of the present invention, in addition to the transparent ink and the effect pigment ink, a colored ink may be used as necessary.
The colored ink contains a colorant, a polymerizable compound, and a polymerizable compound. In addition, the said colorant means the colorant except an effect pigment.

(Relationship between surface tension of transparent ink and effect pigment ink)
If the surface tension of the effect pigment ink is too low than the surface tension of the transparent ink, the optical effect is reduced. Therefore, the surface tension of the effect pigment ink is preferably set high. When the surface tension of the effect pigment ink is lower than the surface tension of the transparent ink, the difference is preferably 5 mN / m or less, more preferably the surface tension of the effect pigment ink is higher than the surface tension of the transparent ink. .
That is, when the surface tension of the transparent ink at 25 ° C. is γs and the surface tension of the effect pigment ink at 25 ° C. is γk, γs−γk ≦ 5 mN / m is preferable, and γs−γk <0. More preferred.
The lower limit of γs-γk is not particularly limited, but is preferably −10 mN / m or more, more preferably −8 mN / m or more, and further preferably −5 mN / m or more.
The surface tension is a value measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a commonly used surface tension meter (for example, surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.). is there.

The surface tension (γs) at 25 ° C. of the transparent ink is preferably 30 to 40 mN / m, and preferably 30 to 38 mN / m from the viewpoint of forming a uniform film with the transparent ink on the effect pigment ink. Is more preferable, and it is still more preferable that it is 30-36 mN / m.
The surface tension (γk) at 25 ° C. of the effect pigment ink is 30 to 40 mN / m from the viewpoint of preventing the repelling on the recording medium and maintaining the surface tension with the transparent ink appropriately. It is preferably 32 to 40 mN / m, and more preferably 32 to 38 mN / m.
It is preferable to appropriately adjust the surface tension to a desired level by selecting a polymerizable compound to be used, adding a surfactant, or the like.

(Ink physical properties)
The ink of the present invention, particularly the effect pigment ink and the colored ink, preferably has a viscosity at 25 ° C. of 40 mPa · s or less, more preferably 5 to 40 mPa · s, more preferably 7 to More preferably, it is 30 mPa · s. Moreover, it is preferable that the viscosity in discharge temperature (Preferably 25-80 degreeC, More preferably, 25-50 degreeC) is 3-15 mPa * s, and it is more preferable that it is 3-13 mPa * s. The composition ratio of the ink of the present invention is preferably adjusted as appropriate so that the viscosity is in the above range. By setting the viscosity at room temperature (25 ° C.) high, even when a porous recording medium is used, ink penetration into the recording medium can be avoided and uncured monomers can be reduced, which is preferable. . Furthermore, it is preferable because ink bleeding at the time of ink droplet landing can be suppressed, and as a result, the image quality is improved.

Hereinafter, components contained in the transparent ink, the effect pigment ink, and the colored ink will be described.
(Polymerizable compound)
In the present invention, the polymerizable compound contained in the ink (transparent ink, effect pigment ink, and colored ink) is preferably a radical polymerizable compound.
The reason why the radically polymerizable compound is suitably used for the effect pigment ink is that (1) an image forming process for ejecting the effect pigment ink on the recording medium, and (2) a transparent ink for applying the transparent ink on the recording medium. When a step of curing the effect pigment ink is provided between the ink application steps, the effect pigment ink has a fluidity of 85% or less while maintaining the fluidity of the effect pigment ink by inhibiting oxygen polymerization peculiar to radical polymerization. This is because it is easy.
On the other hand, the reason why the radical polymerizable compound is suitably used for the transparent ink is that the storage stability of the transparent ink is better than that of the cationic polymerizable compound when the radical polymerizable compound is used.
The radical polymerizable compound is not particularly limited as long as it is a compound that causes radical polymerization reaction by some energy application and cures, and can be used regardless of the type of monomer, oligomer, or polymer. Various known radically polymerizable monomers known as photoradical polymerizable monomers that cause a polymerization reaction with an initiation species generated from a radical polymerization initiator can be used. Moreover, the radically polymerizable compound may be a monofunctional compound or a polyfunctional compound.

  Examples of the radical polymerizable compound include (meth) acrylates, (meth) acrylamides, aromatic vinyls, N-vinyl compounds and the like. In this specification, “(meth) acrylate” and “(meth) acrylate” and “acrylic” and “methacryl” are used when referring to “acrylate” and / or “methacrylate”. And may be described respectively.

  The radical polymerizable compound in the present invention is preferably (meth) acrylates from the viewpoint of curability and viscosity. In particular, it is more preferable that it is at least one selected from monofunctional (meth) acrylate and bifunctional (meth) acrylate from the viewpoint of viscosity.

Hereinafter, the radically polymerizable compound applicable to the present invention will be described in detail.
Examples of the (meth) acrylate used in the present invention include the following.
Monofunctional (meth) acrylates include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) ) Acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, isophoryl (meth) acrylate (3,5,5-trimethylcyclohexyl (meth) acrylate), benzyl (meth) acrylate, 2-ethylhexylglycol (meth) acrylate, butoxyethyl ( ) Acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, cyanoethyl (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl ( (Meth) acrylate, alkoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, 2- (2-butoxyethoxy) ethyl (meth) ) Acrylate, 2,2,2-tetrafluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecyl (meth) acrylate, 4-butylphenyl (meth) acrylate, phenyl (meth) acrylate 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate, glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate , Glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, hydroxyalkyl (meth) acrylate, 2-hydroxyethyl (Meth) acrylate, 3-hydroxypropyl (meth) acrylate,

  2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate , Dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether (meth) acrylate, Polyethylene oxide (meth) acrylate, oligoethylene oxide (meth) acrylate, oligoethyleneoxy Monoalkyl ether (meth) acrylate, polyethylene oxide monoalkyl ether (meth) acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, oligopropylene oxide monoalkyl ether (meth) acrylate, 2-methacrylate Leuoxytyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl ( (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, ethylene oxide (EO) modified phenol (meth) ) Acrylate, EO-modified cresol (meth) acrylate, EO-modified nonylphenol (meth) acrylate, propylene oxide (PO) modified nonylphenol (meth) acrylate, EO-modified 2-ethylhexyl (meth) acrylate.

  Specific examples of the bifunctional (meth) acrylate include 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 3-methyl-1 , 5-pentanediol di (meth) acrylate, 2,4-dimethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol (meth) acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol Cold di (meth) acrylate, oligoethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, 2-ethyl-2-butyl-butanediol di (meth) acrylate, hydroxypivalate neopentyl glycol di (me ) Acrylate, EO-modified bisphenol A di (meth) acrylate, bisphenol F polyethoxydi (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di (meth) acrylate, 1,4 -Butanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di (meth) acrylate, 1,9-nonanedi (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, tricyclodecanedi (Meth) acrylate etc. are mentioned.

Specific examples of trifunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, and trimethylolpropane alkylene oxide modified (eg, EO modified, PO modified) tri (meth). Acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, dipentaerythritol tripropionate (Meth) acrylate, tri ((meth) acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate Sorbitol tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and ethoxylated glycerin triacrylate.
Specific examples of tetrafunctional (meth) acrylates include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, propionate dipentaerythritol tetra (meth) acrylate, ethoxylated penta Examples include erythritol tetra (meth) acrylate.
Specific examples of the pentafunctional (meth) acrylate include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.
Specific examples of hexafunctional (meth) acrylate include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, captolactone modified dipentaerythritol hexa (meth) acrylate Etc.

  Examples of (meth) acrylamides used in the present invention include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, Nn-butyl ( (Meth) acrylamide, Nt-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N , N-diethyl (meth) acrylamide, (meth) acryloylmorpholine.

  Specific examples of aromatic vinyls used in the present invention include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromo Styrene, vinyl benzoic acid methyl ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3- Hexyl styrene, 4-hexyl styrene, 3-octyl styrene, 4-octyl styrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isopropenyl styrene, butenyls Ren, octenyl styrene, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, and a 4-t-butoxystyrene.

  Specific examples of the N-vinyl compound used in the present invention include N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide, N-methyl-N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylvalerolactam, N-vinylimidazole and the like can be mentioned.

  Furthermore, as the radical polymerizable monomer in the present invention, vinyl esters [vinyl acetate, vinyl propionate, vinyl versatate, etc.], allyl esters [allyl acetate, etc.], halogen-containing monomers [vinylidene chloride, vinyl chloride, etc.] , Vinyl ether [methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy vinyl ether, 2-ethylhexyl vinyl ether, methoxyethyl vinyl ether, cyclohexyl vinyl ether, chloroethyl vinyl ether, etc.], vinyl cyanide [(meth) acrylonitrile, etc.], olefins [ethylene, propylene Etc.].

  In addition, polymerizable oligomers can be blended in the same manner as the monomer. Examples of the polymerizable oligomer include epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, polyester acrylate, and linear acrylic oligomer.

The following group 1 can be illustrated as a polymeric compound used suitably for an effect pigment ink. As described above, the effect pigment ink preferably has a relatively high surface tension as compared with the transparent ink. The polymerizable compound shown in Group 1 has a relatively high surface tension, and the effect pigment ink using the polymerizable compound is excellent in curability and further excellent in the properties of the resulting cured film.
(Group 1)
N-vinylcaprolactam, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide, tetrahydrofurfuryl acrylate, cyclic trimethylolpropane formal acrylate, 2-phenoxyethyl acrylate, triethylene glycol diacrylate , Tetraethylene glycol diacrylate, trimethylolpropane triacrylate, and EO-modified trimethylolpropane triacrylate Among these, the following group 1 ′ is more preferable, and group 2 is more preferable.
(Group 1 ')
N-vinylcaprolactam, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate and cyclic trimethylolpropane formal acrylate (Group 2)
N-vinylcaprolactam and 2-phenoxyethyl acrylate The polymerizable compounds exemplified in Group 1, Group 1 ′ and Group 2 may be used alone or in combination of two or more.

The effect pigment ink preferably contains a polymerizable compound selected from the group consisting of Group 1 in an amount of 20% by weight or more, more preferably 30% by weight or more, and more preferably 40% by weight or more of the total polymerizable compound. It is more preferable to contain.
The polymerizable compound selected from the group consisting of Group 2 is preferably contained in an amount of 25% by weight or more, more preferably 35% by weight, and more preferably 45% by weight or more of the entire polymerizable compound. Further preferred.
The content of the polymerizable compound in the effect pigment ink is preferably 50 to 99% by weight of the entire effect pigment ink, more preferably 60 to 98% by weight, and 70 to 97% by weight. Further preferred.
The polymerizable compounds other than Group 1, Group 1 ′ and Group 2 are not particularly limited, and may be appropriately selected from the above-mentioned monofunctional monomers, polyfunctional monomers and monomers exemplified in Group 1 below.

Examples of the polymerizable compound suitably used for the transparent ink include the following group 3. As described above, it is preferable that the transparent ink has a relatively low surface tension as compared with the effect pigment ink. The polymerizable compound shown in Group 3 has a relatively low surface tension, and the transparent ink using the polymerizable compound is excellent in curability and further excellent in the properties of the resulting cured film.
(Group 3)
Octyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, isophoryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, 1,6-hexanediol diacrylate, 3-methyl-1,5- Pentanediol diacrylate, dipropylene glycol diacrylate, and PO-modified trimethylolpropane triacrylate The polymerizable compounds exemplified in Group 1 may be used alone or in combination of two or more. Among these, a polymerizable compound selected from the group consisting of the following group 4 is more preferable.
(Group 4)
Isobornyl acrylate, isophoryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate

The transparent ink preferably contains a polymerizable compound selected from the group consisting of Group 3 in an amount of 40% by weight or more, more preferably 50% by weight or more, and more preferably 60% by weight or more of the total polymerizable compound. More preferably.
The transparent ink preferably contains a polymerizable compound selected from the group consisting of the group 4 in an amount of 40% by weight or more, more preferably 50% by weight or more, and more preferably 60% by weight based on the total polymerizable compound. More preferably, it is contained.

The content of the polymerizable compound in the transparent ink is preferably 20 to 80% by weight of the whole transparent ink, more preferably 30 to 70% by weight, and further preferably 40 to 60% by weight. .
It does not specifically limit as polymerizable compounds other than the said groups 3 and 4, What is necessary is just to select suitably from the monomer illustrated by the monofunctional monomer mentioned above, a polyfunctional monomer, and the group 2 mentioned later.

As the polymerizable compound of the colored ink, the above-mentioned (meth) acrylate monomer is preferable, but is not limited thereto, and monomers exemplified in the above groups 1 to 4 may be used, and particularly limited. Not.
The content of the polymerizable compound in the colored ink is preferably 50 to 95% by weight of the entire colored ink, more preferably 60 to 90% by weight, and still more preferably 70 to 85% by weight. .

(Polymerization initiator)
The ink (transparent ink, effect pigment ink, and colored ink) of the present invention contains a polymerization initiator.
The polymerization initiator is a compound that absorbs external energy such as the actinic radiation to generate a polymerization initiating species. A polymerization initiator may be used individually by 1 type, and may use 2 or more types together.
The polymerization initiator that can be used in the present invention preferably includes a radical polymerization initiator, more preferably includes a photo radical polymerization initiator, an α-aminoacetophenone compound, an α-hydroxyketone compound, an acylphosphine oxide compound, More preferred are aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, and compounds having a carbon halogen bond. Can be mentioned. Specific examples of these polymerization initiators include radical polymerization initiators described in JP2008-208190A and JP2010-013574A.

As the polymerization initiator for the transparent ink, an α-aminoacetophenone compound, an α-hydroxyketone compound, and an acylphosphine oxide compound are more preferable from the viewpoint of curability and coloring. In addition, when a compound represented by the formula (I) described later is added, it is preferable to use an acyl phosphine oxide compound and / or an α-aminoacetophenone compound as a polymerization initiator, and at least one acyl phosphine oxide. More preferably, the compound and at least one α-aminoacetophenone compound are used in combination.
From the viewpoint of curability and uniform curability, the total content of the polymerization initiator in the transparent ink is preferably 15 to 2% by weight, more preferably 12 to 4% by weight, based on the entire transparent ink. 10 to 5% by weight is more preferable. One polymerization initiator may be used alone, or two or more polymerization initiators may be used in combination.

As the polymerization initiator for the effect pigment ink, an α-aminoacetophenone compound, an α-hydroxyketone compound, and an acylphosphine oxide compound are more preferable from the viewpoint of curability and uniform curability. Further, it is more preferable to use an acylphosphine oxide compound in combination with a compound represented by the formula (I) described later or a thioxanthone compound.
From the viewpoints of curability and curing uniformity, the total content of the polymerization initiator in the effect pigment ink is preferably 20 to 4% by weight, and preferably 18 to 5% by weight, based on the entire effect pigment ink. More preferably, it is more preferably 16 to 6% by weight. A polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

The polymerization initiator for the colored ink may be appropriately selected according to the polymerizable compound to be used, and is not particularly limited.
From the viewpoint of curability, the total content of the polymerization initiator in the colored ink is preferably 20 to 4% by weight, more preferably 18 to 5% by weight, and more preferably 16 to 6% by weight. More preferably. A polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

In addition, when using a sensitizer, the total content of a polymerization initiator is a weight ratio of a polymerization initiator: sensitizer with respect to the content of a sensitizer, preferably 200: 1 to 1: 200, More preferably, it is the range of 50: 1 to 1:50, More preferably, it is the range of 20: 1 to 1: 5.
When a sensitizer is used, the content of the sensitizer in the ink is preferably 0.01 to 20% by weight, preferably 0.1 to 15% by weight, based on the total weight of the ink, from the viewpoint of colorability of the ink. Is more preferable, and 0.5 to 10% by weight is still more preferable.

(Sensitizer)
In the present invention, the transparent ink preferably contains a compound represented by the following formula (I) as a sensitizer. By containing the compound represented by the formula (I), sensitivity is improved, and coloring derived from a polymerization initiator or the like can be suppressed, which is preferable.
In addition, it does not exclude that the effect pigment ink and / or the colored ink contains a compound represented by the following formula (I).

In the formula (I), X represents O, S or NR. R represents a hydrogen atom, an alkyl group or an acyl group, and is preferably an alkyl group or an acyl group.
In the formula (I), n represents 0 or 1.
X is preferably O or S, and more preferably S.
When n is 0, there is no carbon atom bonded to R ⁷ and R ^8, and X containing a hetero atom and a carbon atom bonded to R ⁵ and R ⁶ are directly bonded to form X. A 5-membered heterocycle containing it.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represents a hydrogen atom or a monovalent substituent.
Examples of the monovalent substituent in R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ include a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, Hydroxy group, nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureido group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamide group Carbamoyl group, sulfamoyl group, sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryloxycarbonylamino group, imide group, heterocyclic thio group , Sulfinyl group, phosphoryl group, acyl group, carboxyl group or sulfo group And so on. Among these, an alkyl group or a halogen atom is preferable.

The alkyl group in the case where R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ in formula (I) represent a monovalent substituent, Alkyl groups are preferable, and those having 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group, n-butyl group, sec-butyl group and t-butyl group are more preferable.
Similarly, alkoxy groups include those having 1 to 4 carbon atoms such as methoxy, ethoxy, hydroxyethoxy, propoxy, n-butoxy, isobutoxy, sec-butoxy, and t-butoxy. Preferably mentioned.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

R ¹ , R ² , R ³ and R ⁴ may be linked to each other (for example, condensed) to form a ring.
Examples of the ring structure in the case where these form a ring include a 5- or 6-membered aliphatic ring, an aromatic ring, etc., and may be a heterocyclic ring containing an element other than a carbon atom. The rings may be further combined to form a binuclear ring, for example, a condensed ring. Further, these ring structures may further have a substituent exemplified when R ^{1 to} R ⁸ represent a monovalent substituent in the formula (I). Examples of heteroatoms when the formed ring structure is a heterocycle include N, O and S.

When n = 1, R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring, but do not form an aromatic ring. The aliphatic ring is preferably a 3- to 6-membered ring, and more preferably a 5- or 6-membered ring.

  The compound represented by the formula (I) is preferably a compound represented by the following formula (IA).

In the formula (IA), X represents O or S, n represents 0 or 1, and R ^1A , R ^2A , R ^3A , R ^4A , R ^5A , R ^6A , R ^7A and R ^8A are each Independently represents a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a cyano group, a nitro group, an amino group, an alkylthio group, an alkylamino group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, a carboxyl group, or a sulfo group. . Two adjacent R ^1A , R ^2A , R ^3A and R ^4A may be linked (condensed) with each other to form a ring. R ^5A or R ^6A and R ^7A or R ^8A may ^combine with each other to form an aliphatic ring, but do not form an aromatic ring.
Further, these ring structures are the examples shown in the above formula (I) when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent. It may further have a substituent. When the ring structure is a heterocyclic ring, examples of the hetero atom include N, O, and S.

  The compound represented by the formula (I) is more preferably a compound represented by the following formula (IB).

In the formula ( ^IB ), X represents O or S, and R ^1B , R ^2B , R ^3B , R ^4B , R ^5B , R ^6B , R ^7B and R ^8B are each independently a hydrogen atom or an alkyl group Represents a halogen atom, hydroxyl group, cyano group, nitro group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxyl group or sulfo group. R ^1B , R ^2B , R ^3B and R ^4B may be linked (condensed) with each other adjacent two to form a ring. R ^5B or R ^6B and R ^7B or R ^8B may ^combine with each other to form an aliphatic ring, but do not form an aromatic ring.
Further, these ring structures are the examples shown in the above formula (I) when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent. It may further have a substituent. When the ring structure is a heterocyclic ring, examples of the hetero atom include N, O, and S.

  Furthermore, the compound represented by the formula (I) is more preferably a compound represented by the following formula (IC).

In the formula ( ^IC ), R ^1C , R ^2C , R ^3C , R ^4C , R ^5C , R ^6C , R ^7C and R ^8C are each independently a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, or a cyano group. Nitro group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxyl group or sulfo group.
R ^1C , R ^2C , R ^3C and R ^4C may be formed by condensing two adjacent groups to form a 5- or 6-membered aliphatic ring or aromatic ring. Heterocycles containing other elements may be used, and the formed rings may be further combined to form a binuclear ring, for example, a condensed ring. R ^5C or R ^6C and R ^7C or R ^8C may ^combine with each other to form an aliphatic ring, but do not form an aromatic ring.
Further, these ring structures are the examples shown in the above formula (I) when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent. It may further have a substituent. When the ring structure is a heterocyclic ring, examples of the hetero atom include N, O, and S.

Moreover, it is preferable that at least one of R ^1C , R ^2C , R ^3C , R ^4C , R ^5C , R ^6C , R ^7C and R ^8C is a halogen atom. Preferred substitution positions include R ^1C , R ^2C , R ^3C and R ^4C , with R ^2C being most preferred. The number of halogen atoms in R ^{1C to} R ^8C is preferably 1 or 2, and more preferably 1.

R ^2C is preferably a substituent other than hydrogen. Among them, an alkyl group, a halogen atom, an acyloxy group, or an alkoxycarbonyl group is preferable because of good matching with a light source and high sensitivity, and an alkyl group or a halogen atom is preferable. More preferred.

Either R ^7C or R ^8C is preferably a substituent other than hydrogen, and more preferably both are substituents other than hydrogen. Preferable substituents include an alkyl group, a halogen atom, a carboxyl group, and an alkoxycarbonyl group. Among them, an alkyl group and an alkoxycarbonyl group are preferable, and an alkyl group is most preferable.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a chlorine atom, a bromine atom and an iodine atom are preferable.

  The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and has 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, or a t-butyl group. Are more preferred.

The acyloxy group is preferably an aliphatic acyloxy group having 2 to 10 carbon atoms, and more preferably an aliphatic acyloxy group having 2 to 5 carbon atoms.
As the alkoxycarbonyl group, an aliphatic alkoxycarbonyl group having 2 to 10 carbon atoms is preferable, and an alkoxycarbonyl group having 2 to 5 carbon atoms is more preferable.

Specific examples of the compounds represented by formula (I) that can be suitably used in the present invention [Exemplary compounds (I-1) to (I-133)] are shown below, but the present invention is limited to these. It is not a thing. In some of the chemical formulas in the present invention, the hydrocarbon chain may be described by a simplified structural formula in which symbols of carbon (C) and hydrogen (H) are omitted. Further, in the following specific examples, Me represents a methyl group, Bu ^t represents a t- butyl group, Pr ⁱ represents an isopropyl group.

  Among these, exemplary compounds (I-2), (I-4), (I-5), (I-14) and (I-15) are preferable, and exemplary compound (I-14) is particularly preferable.

  Examples of the method for synthesizing the compound represented by the formula (I) include Japanese Patent Application Laid-Open No. 2004-189695, Tetrahedron, Vol. 49, p939 (1993), Journal of Organic Chemistry, p893 (1945), and It can be synthesized by a known method described in Journal of Organic Chemistry, p4939 (1965).

The compound represented by the formula (I) is a curable and non-curable component, and from the standpoint of preventing crying from the cured film of the compound, the additive concentration to the ink is relative to the total weight of the ink. 0.5 wt% or more and 25.0 wt% or less is preferable, 1.0 wt% or more and 20.0 wt% or less is more preferable, 1.0 wt% or more and 15.0 wt% or less. It is particularly preferred that
In addition, since the compound represented by the formula (I) has almost no absorption in the visible light region, there is no concern that the hue of the ink is affected even if an amount capable of exhibiting the effect as a sensitizer is added. It also has advantages. In particular, in the case of a transparent ink, there is a problem that the hue of the ink tends to change when a sensitizer is used. However, the compound represented by the above formula (I) is transparent without causing such a hue change. High curability (high sensitivity) can be imparted to the ink.

<Other sensitizers>
The ink (transparent ink, effect pigment ink, and colored ink) of the present invention may contain other sensitizers in order to absorb specific active energy rays and promote decomposition of the polymerization initiator.
Examples of other sensitizers include polynuclear aromatics (eg, pyrene, perylene, triphenylene, 2-ethyl-9,10-dimethoxyanthracene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine). B, rose bengal, etc.), cyanines (eg, thiacarbocyanine, oxacarbocyanine, etc.), merocyanines (eg, merocyanine, carbomerocyanine, etc.), thiazines (eg, thionine, methylene blue, toluidine blue, etc.), acridines (For example, acridine orange, chloroflavin, acriflavine, etc.), anthraquinones (for example, anthraquinone, etc.), squariums (for example, squalium), coumarins (for example, 7-diethylamino-4-methylcoumarin, etc.), thio Sandton compound (such as thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, etc.) and the like.
Among these, thioxanthones can be preferably exemplified.
Moreover, a sensitizer may be used individually by 1 type and may use 2 or more types together.

(Effect pigment)
In the present invention, effect pigments mean all pigments that have a lamellar structure and provide a special decorative color effect for the surface coating. The effect pigments include, for example, pure metal pigments such as aluminum, iron or copper, mica coated with titanium dioxide, mica coated with iron oxide, mica coated with mixed oxides (for example, dioxide) Interference pigments or liquid crystal pigments such as aluminum coated with a metal oxide, and those coated with titanium dioxide and Fe ₂ O ₃ or with titanium dioxide and Cr ₂ O ₃ .
Among these, the effect pigment is preferably a metal pigment or a pearl pigment.

  Especially as a metal pigment, an aluminum material is preferable and aluminum powder, an aluminum paste, aluminum flakes, etc. are illustrated. The aluminum powder is a metallic pigment that does not contain a solvent component, and includes a material in which aluminum particles are coated with a resin such as an acrylic resin. The aluminum paste is a material obtained by surface-treating aluminum scaly fine particles and pasting them with an organic solvent or the like. Furthermore, as an example of the aluminum flakes, a material of a type obtained by pigmenting an aluminum vapor deposition film can be exemplified.

  Examples of the pearl pigment include white pearl obtained by pulverizing mica and performing surface treatment.

In the present invention, the effect pigment is preferably a tabular particle, and the shape of the effect pigment preferably satisfies the following formulas (1) and (2).
0.5 μm ≦ R ₅₀ ≦ 5 μm (1)
R ₅₀ / d> 5 (2)
(In Formula (1) and Formula (2), R ₅₀ is the 50% average particle diameter in the equivalent circle diameter determined from the plane area of the particles, and d is the plate thickness.)

The tabular grains are grains having a substantially flat surface (XY plane) and a substantially uniform thickness (Z). Here, the major axis on the plane of the tabular grains is defined as X, the minor axis is defined as Y, and the thickness is defined as Z.
When the major axis on the plane of the tabular grain is X, the minor axis is Y, and the thickness is Z, R ₅₀ is the 50% average grain diameter of the equivalent circle diameter determined from the area of the XY plane of the tabular grain. is there.
The equivalent circle diameter is the diameter of the circle when assuming that the substantially flat surface (XY plane) of the tabular grain is a circle having the same projected area as the projected area of the grain. When the substantially flat surface (XY plane) of a tabular grain is a polygon, the diameter of the circle obtained by converting the projected surface of the polygon into a circle is the equivalent circle diameter of the tabular grain. It is said.

R ₅₀ of the effect pigment is preferably from 0.5 μm to 5 μm, more preferably from 0.7 to 4 μm, and further preferably from 1 to 3 μm from the viewpoints of glossiness and ejection stability. preferable.

Moreover, the R ₅₀ of the tabular grains, the relationship between the thickness d, in order to ensure a high gloss, it is preferable that R ₅₀ / d> 5. R ₅₀ / d is more preferably 6 or more, and still more preferably 8 or more.

The R ₅₀ can be measured using a particle image analyzer, and examples thereof include a flow particle image analyzer FPIA-2100, FPIA-300, and FPIA-3000S manufactured by Sysmex Corporation.
The thickness d can be measured by an SEM image.

In the present invention, the effect pigment is preferably a tabular particle satisfying the formulas (1) and (2), more preferably a metal pigment or a pearl pigment satisfying the formulas (1) and (2). .
Examples of the pearl pigment that is a tabular particle include clay minerals having a layered structure such as mica, talc, kaolin, bentonite, smectite, sepiolite, bamicurite, montmorillonite, and sericite. In addition, it is possible to improve the pearly luster by forming a flat processed material such as mica processed into a flat plate with titanium dioxide or iron oxide to form a thin film of multiple layers. A flat pigment is also preferably used.

  The metal pigment that is a tabular grain is preferably aluminum or an aluminum alloy. When using an aluminum alloy, the other metal element or non-metal element added to aluminum is not particularly limited as long as it has a metallic luster, silver, gold, platinum, nickel, chromium, tin, Zinc, indium, titanium, copper and the like can be mentioned, and one or more selected from the group consisting of these simple substances or alloys thereof and mixtures thereof can be used.

The method for producing the effect pigment which is the tabular grain is not particularly limited. (1) A composite pigment base material having a structure in which a release resin layer and a metal or metal compound layer are sequentially laminated on a sheet-like substrate surface. (2) A method in which the metal or metal compound layer is peeled from the sheet-like substrate at the interface between the metal or metal compound layer and the peeling resin layer as a boundary, and is pulverized and refined to obtain tabular grains. ) Aluminum is melted and then sprayed (atomized), and the resulting spherical particles are ground using a pearl mill, a ball mill, or the like. JP-A-2008-239951, JP-T 2010-533747 Reference can be made to publications and the like.
In the method (1), a plurality of metal or metal alloy layers can be laminated. In the methods (1) and (2), another layer can be laminated on the metal or metal alloy layer, and a protective layer can be exemplified as the other layer. Examples of the protective layer include metal oxides such as silicon oxide, alumina, and titanium oxide, and / or layers formed from organic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, and cellulose derivatives.

In the present invention, the effect pigment is preferably a tabular grain formed from a thin multilayer, and examples thereof include the effect pigment obtained by the above-described method. It is preferable that the effect pigment is formed of thin multilayers in that remarkable optical characteristics can be obtained.
Moreover, it is preferable that the material of an effect pigment is aluminum or aluminum alloy from a viewpoint of an availability and a glitter.

(Surfactant)
In the present invention, the transparent ink, effect pigment ink, and colored ink may contain a surfactant. In particular, since the transparent ink preferably has a relatively low surface tension with respect to the effect pigment ink, the transparent ink preferably contains a surfactant.
Examples of the surfactant used in the present invention include the following surfactants. Examples thereof include those described in JP-A Nos. 62-173463 and 62-183457. Specifically, for example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene -Nonionic surfactants such as polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used as the known surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.
In particular, the surfactant used in the present invention is not limited to the above-described surfactant, and may be any additive capable of efficiently reducing the surface tension with respect to the added concentration.

In the present invention, when an ionic surfactant such as a nonionic surfactant or an anionic surfactant is used, the stability of the transparent ink and the effect pigment ink may be lowered. For this reason, a nonionic surfactant is preferable, and a nonionic hydrocarbon surfactant is preferably used.
Examples of nonionic hydrocarbon surfactants include long-chain alkyl acrylate polymers, polyoxyethylene alkyl ethers, carboxylic acid alkanolamides, and the like, from the viewpoint of excellent compatibility with polymerizable monomers. Polymers are preferably used.

  The addition amount of the surfactant is not particularly limited, but is preferably 2.0 to 0.01% by weight based on the whole ink from the viewpoint of achieving stable discharge properties and surface tension within a desired range, and 0.5 to It is more preferably 0.05% by weight, particularly preferably 0.2 to 0.05% by weight.

(Coloring agent)
In the present invention, the colored ink contains at least a colorant.
There is no restriction | limiting in particular in the coloring agent which can be used in this invention, According to a use, well-known various pigments and dyes can be selected suitably and can be used. Among them, the colorant contained in the colored ink is preferably a pigment from the viewpoint of excellent light resistance. The colorant contained in the color ink means a colorant other than the effect pigment.

In the present invention, pigments preferably used for the colorant will be described.
The pigment is not particularly limited, and all commercially available organic pigments and inorganic pigments, and those obtained by dyeing resin particles with a dye can be used. Further, commercially available pigment dispersions and surface-treated pigments such as those obtained by dispersing pigments in an insoluble resin or the like using a dispersion medium, or those obtained by grafting a resin on the pigment surface, etc., impair the effects of the present invention. It can be used as long as it is not.
As these pigments, for example, edited by Seijiro Ito, “Dictionary of Pigments” (published in 2000), W. Herbst, K. Hunger, Industrial Organic Pigments, JP 2002-12607 A, JP 2002-188025 A, Examples thereof include pigments described in JP2003-26978A and JP2003-342503A.

  Specific examples of organic pigments and inorganic pigments that can be used in the present invention include C.I. I. Pigment Yellow 1 (Fast Yellow G, etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Pigment yellow 180, C.I. I. Non-benzidine type azo pigments such as C.I. Pigment Yellow 200 (Novoperm Yellow 2HG); I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  C. As a thing which exhibits red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment Violet 19 (unsubstituted quinacridone, CINQUASIA Magenta RT-355T; manufactured by Ciba Specialty Chemicals), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

As a pigment exhibiting blue or cyan, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Pigment blue 15, C.I. I. Phthalocyanine pigments such as C.I. Pigment Blue 15: 3 (IRGALITE BLUE GLO; manufactured by Ciba Specialty Chemicals) (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).
As a pigment exhibiting green, C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
As a pigment exhibiting an orange color, C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

Examples of the black pigment include carbon black, titanium black, and aniline black. Examples of the carbon black include SPECIAL BLACK 250 (manufactured by Degussa).
Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.
Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, and thus has a high hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

Dispersing colorants, for example, bead mill, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. Can be used.
When dispersing the colorant, a dispersant such as a surfactant can be added.
Moreover, when adding a coloring agent, it is also possible to use the synergist according to various coloring agents as a dispersing aid as needed. The dispersion aid is preferably added in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the colorant.

  As a dispersion medium for various components such as a colorant in the colored ink, a solvent may be added, or the polymerizable compound which is a low molecular weight component without solvent may be used as the dispersion medium. Is preferably an active energy ray-curable liquid, and is preferably solvent-free in order to cure the colored ink after it is applied to the recording medium. This is because if the solvent remains in the image formed from the cured colored ink, the solvent resistance is deteriorated or a problem of VOC (Volatile Organic Compound) of the remaining solvent occurs. From such a viewpoint, it is preferable to use a polymerizable compound as the dispersion medium, and in particular, to select a polymerizable compound having a low viscosity from the viewpoint of improving dispersion suitability and ink handling properties.

The average particle size of the colorant used here is preferably 0.01 μm or more and 0.4 μm or less, and more preferably 0.02 μm or more and 0.2 μm or less, because the finer the particle, the better the color developability. It is preferable to set the colorant, dispersant, dispersion medium, dispersion conditions, and filtration conditions so that the maximum particle diameter is 3 μm or less, preferably 1 μm or less. By controlling the particle size, clogging of the head nozzle can be suppressed, and the storage stability of the colored ink, the transparency of the colored ink, and the curing sensitivity can be maintained.
The particle size of the colorant in the colored ink can be measured by a known measurement method. Specifically, it can be measured by a centrifugal sedimentation light transmission method, an X-ray transmission method, a laser diffraction / scattering method, and a dynamic light scattering method. In the present invention, a value obtained by measurement using a laser diffraction / scattering method is employed.

(Dispersant)
In the present invention, the ink, particularly the effect pigment ink and the colored ink, preferably contain a dispersant. In particular, when a pigment is used, it is preferable to contain a dispersant in order to stably disperse the pigment in the ink. As the dispersant, a polymer dispersant is preferable. The “polymer dispersing agent” in the present invention means a dispersing agent having a weight average molecular weight of 1,000 or more.

Examples of the polymer dispersant include DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-166, and DISPERBYK-166. , DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (manufactured by BYK Chemie); EFKA7462, EFKA7500, EFKA7570, EFKA7575, EFKA7580 (manufactured by Efka Additive); Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (manufactured by Sannopco); Solsperse (SOLSPERSE) 3000 Various Solsperse dispersants (manufactured by Noveon) such as 5000, 9000, 12000, 13240, 13940, 17000, 22000, 24000, 26000, 28000, 32000, 36000, 39000, 41000, 71000; Adeka Pluronic L31, F38, L42, L44 , L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, -123 (manufactured by ADEKA Co., Ltd.), Ionette S-20 (manufactured by Sanyo Chemical Industries, Ltd.); Disparon KS-860, 873SN, 874 (polymer dispersant), # 2150 (aliphatic polycarboxylic acid), # 7004 (polyether ester type) (manufactured by Enomoto Kasei Co., Ltd.).
As the dispersant for the effect pigment, an acidic dispersant and a basic dispersant can be preferably used, but it is more preferable to use them appropriately depending on the acid and base value of the surface of the effect pigment to be used. That is, a basic dispersant is particularly preferably used when the surface acid number is relatively high, and an acidic dispersant can be particularly preferably used when the surface base number is relatively high.
In the present invention, the content of the dispersant in the ink is appropriately selected depending on the purpose of use, but is preferably 0.05 to 15% by weight with respect to the weight of the whole ink.

(Other additives)
In addition to the polymerizable compound and the polymerization initiator, various additives can be used in combination with the ink in the invention according to the purpose. For example, from the viewpoint of improving weather resistance, an ultraviolet absorber can be used. In addition, an antioxidant can be added to improve stability.
Furthermore, various organic and metal complex anti-fading agents, conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, dimethylamine hydrochloride for the purpose of controlling ejection properties, ink and recording medium In order to improve the adhesiveness, an extremely small amount of an organic solvent can be added.
Moreover, various polymer compounds can be added to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination.
In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, tackifiers that do not inhibit polymerization in order to improve adhesion to polyolefins, PET, etc. Can be contained.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these.
“Parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.

(Preparation of aluminum pigment dispersion)
Liquid A shown in Table 1 was stirred for 3 minutes with a mixer manufactured by SILVERSON (1,000 to 1,500 rpm) to obtain a uniform preliminary dispersion. Then, dispersion | distribution was implemented using the circulation type bead mill apparatus (Laboratory Mini Mill) made from EIGER. Dispersion conditions were such that 100 cc of zirconia beads having a diameter of 0.65 mm were filled, the peripheral speed was 9 m / s, and the dispersion time was 5 hours.

In Table 1, the aluminum pigment solvent dispersion A and the acidic dispersant A are as follows.
Aluminum pigment solvent dispersion A: Aluminum pigment 20 wt% IPA (isopropyl alcohol) dispersion, METALURE W-52012 IL (manufactured by ECKART)
Acidic dispersant A: Solsperse 36000 (manufactured by Luburizol)
The dispersion after dispersion is diluted with IPA and measured with a laser diffraction / scattering particle size distribution analyzer (manufactured by Horiba, Ltd., LA-950), and R ₅₀ = 3.5 μm. confirmed. On the other hand, the sample washed with Seton and then dried was observed with a scanning electron microscope (JEOL 6500, manufactured by JEOL Ltd.) and confirmed that d = 56 nm.

  30 g of PEA (2-phenoxyethyl acrylate, SR339C; manufactured by Sartomer) was added to 100 g of the liquid A subjected to the dispersion treatment, and the mixture was stirred for 3 minutes (1,000 to 1,500 rpm) with a mixer manufactured by SILVERSON. A liquid was obtained. This liquid was subjected to an evaporator treatment to remove isopropanol. This treatment was performed until the total weight of the liquid reached 50 g, and an aluminum pigment dispersion A was obtained. The content of isopropanol in the aluminum pigment dispersion A after the treatment was 2 wt% or less.

(Production of metallic ink and transparent ink)
The composition shown in Table 2 was stirred for 15 minutes with a mixer manufactured by SILVERSON (1,000 to 1,500 rpm) to obtain a uniform effect pigment ink (metallic ink). The results of measuring the surface tension are shown in Table 2.
Further, the composition shown in Table 3 was stirred for 10 minutes with a mixer manufactured by SILVERSON (1,000 to 1,500 rpm) to obtain a uniform transparent ink. The results of measuring the surface tension are shown in Table 3.

Each component used in Table 2 and Table 3 is as follows.
HDDA: 1,6-hexanediol diacrylate (SR238, manufactured by SARTMER)
3MPDDA: 3methyl-1,5-pentanediol diacrylate (SR341, manufactured by SARTMER)
DPGDA: Dipropylene glycol diacrylate (ST508, manufactured by SARTMER)
(PO) TMPTA: PO-modified trimethylolpropane triacrylate (SR492, manufactured by SARTMER)
EOEOEA: 2 (2-ethoxyethoxy) ethyl acrylate (SR256, manufactured by SARTMER)
PEA: 2-phenoxyethyl acrylate (SR339, manufactured by SARTMER)
IBOA: isobornyl acrylate (SR506, manufactured by SARTMER)
・ ODA: Octyl / decyl acrylate (SR484, manufactured by SARTMER)
NVC: N-vinylcaprolactam (NVC, manufactured by BASF)
THFA: tetrahydrofurfuryl acrylate (SR506, manufactured by SARTMER)
CTFA: cyclic trimethylolpropane formal acrylate (SR531, manufactured by SARTMER)
TEGDA: triethylene glycol diacrylate (SR268, manufactured by SARTMER)
TMPTA: trimethylolpropane triacrylate (SR351, manufactured by SARTMER)
-(EO) TMPTA: EO modified trimethylolpropane triacrylate (SR454, manufactured by SARTMER)
TPO: Lucirin TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide, manufactured by BASF)
Irg819: Irgacure 819 (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, manufactured by BASF)
Irg184: Irgacure 184 (1-hydroxycyclohexyl phenyl ketone, manufactured by BASF)
Irg907: Irgacure 907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, manufactured by BASF)
-ITX: Mixture of 2-isopropylthioxanthone and 4-isopropylthioxanthone (Lambson, trade name: Speedcure ITX)
Cl-thiochromanone: Compound A shown below
M-thiochromanone: the following compound B
Acrylic polymer A: poly (2-ethylhexyl acrylate), MW = 96,000
ST-1: FIRSTCURE ST-1 (manufactured by Albemarle, polymerization inhibitor)
BYK307: Polyether-modified polydimethylsiloxane (BY307, manufactured by Big Chemie)

(Image recording device (shuttle scan type))
FIG. 2 shows a schematic configuration diagram of the shuttle scan type inkjet recording printer 1 used for printing. FIG. 3 shows a schematic perspective view of the inkjet recording head unit 2.
The ink was stored in the ink tank 8. Ink was supplied from the ink tank 8 to the inkjet recording head unit 2 through an ink supply tube (not shown).
The inkjet recording head unit 2 is fixed by a fixed shaft 5 made of a long metal shaft, and reciprocates at a variable speed by a power unit 4 capable of reciprocating. The power unit 4 capable of reciprocating motion incorporates an ink supply tube (not shown) and a head control electrical wiring (not shown).
At both ends of the fixed shaft 5 of the head unit 2 for ink jet recording, a maintenance unit 3 for carrying out head maintenance and cleaning is provided. Further, a control unit 6 (for example, a personal computer) for controlling the ink jet recording printer and an ink tank 8 are arranged outside these.
Inkjet recording head unit 2 has seven commercially available headsets (21 to 27 in FIG. 3) with two commercially available heads (head CA4 manufactured by TOSHIBA TEC CO., LTD.) Arranged in two for each color. And two ultraviolet curing lamps (metal halide lamps) (28 and 29 in FIG. 3). In addition, the headset includes inkjet heads 21 and 27 for transparent ink, inkjet head 22 for cyan ink, inkjet head 23 for magenta ink, inkjet head 24 for yellow ink, inkjet head 25 for black ink, metallic ink (effect pigment ink). The ink jet heads 26 were arranged in this order.
A commercially available head (Toshiba TEC Co., Ltd. head CA4) used for an ink jet head for metallic ink (effect pigment ink) has a mesh filter removed, and a disk filter 30 (Pall's LastChanceFilterAcro37 (LCF-23100)) head. And installed between the tanks.

A recording medium suction stage 7 capable of sucking and fixing the recording medium is disposed immediately below the head. The recording medium 9 has a mechanism for conveying the recording medium in a direction perpendicular to the reciprocation of the head by a plurality of recording medium conveying rollers 10 and a recording medium winding roller 11.
The ejection frequency of the head and the speed of the head reciprocation were controlled, and it was set to always print an image with a droplet ejection density of 300 × 600 dpi in one scan. The irradiation intensity from the metal halide lamp, on the recording medium, when the slit opening of about 1,000 mW / cm ^2, when the slit closed is about 0 mW / cm ^2,.

(Image recording device (single pass type))
FIG. 4 shows a schematic configuration diagram of a single-pass type ink jet recording printer used for printing.
The head units for inkjet recording 33, 35, 37, 39, and 40 were composed of headsets in which two commercially available heads (head CA4 manufactured by TOSHIBA TEC CO., LTD.) Were arranged per color and 600 npi full line was arranged. Remove the mesh filter attached to the commercially available head (Toshiba Tec Corporation head CA4) used for the metallic ink inkjet head 33 and install a disk filter (Pall's LastChanceFilterAcro37 (LCF-23100)) between the head and the tank. did.
The head unit portion is fixed to the machine body in the order of metallic ink 33, cyan 35, magenta 37, yellow 39, and black 40 in the order from the upstream side of the recording medium conveyance direction, and is transparent upstream of the metallic ink head unit portion 33. An ink roll coater 31 was installed. The recording medium 44 is configured to be movable directly under the head, and the light sources 32, 34, 36, and 38 (365 nm ultraviolet LEDs) are arranged in the traveling direction of the recording medium with respect to each head, and the black ink. A metal halide lamp 41 (light intensity 3,000 mW / cm ² ) was installed downstream of the head.
The recording medium is conveyed by roll conveyance, and is conveyed by a feeding machine 42 and a winder 43. An image of 600 dpi × 600 dpi was formed on the recording medium.

Example 1
The shuttle scan type ink jet recording printer 1 was filled with the ink set of the combinations shown in Table 4 in the ink jet head Me for metallic ink and the ink jet heads T1 and T2 for transparent ink, respectively, and printing was performed according to the following procedure. As the recording medium, PET (Bueful, manufactured by Kimoto Co., Ltd.) and coated paper (OK Top Coat, manufactured by Oji Paper Co., Ltd.) were used.
1) First feed scan: the head moves in the direction of arrow A in the figure. First, metallic ink was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head Me for metallic ink (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. ) Subsequently, transparent ink was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T2 for transparent ink (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. )
Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp.
Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center points of the dots from the inkjet head Me and the dots from the inkjet head T2 coincide.
2) First return scan: the head moves in the direction of arrow B in the figure. Metallic ink was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the metallic ink inkjet head Me (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. .) Subsequently, transparent ink was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. ) Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV1 ultraviolet irradiation lamp.
Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide.
3) Feed of recording medium: The recording medium was fed by 52.6 mm, which is 1 cm less than the head width (53.6 mm).
4) The above procedures 1) to 3) were repeated to produce a printed matter having an area of about 30 cm × about 30 cm.
5) After printing, metallic feeling, coating, and scratch resistance were evaluated according to the following evaluation criteria.

(Metallic feeling)
The presence or absence of a metallic feeling can be expressed by measuring the glossiness of 20 degrees, 60 degrees, and 85 degrees (gloss meter: Tri-Glossmaster u (Shen)).
A: Gloss value (60 degrees)> Gloss value (20 degrees)> Gloss value (85 degrees), and
Gloss value (60 degrees)> 100 is satisfied. ○: Gloss value (60 degrees)> Gloss value (20 degrees)> Gloss value (85 degrees)
Gloss value (60 degrees)> 80 is satisfied. Δ: Gloss value (60 degrees)> Gloss value (20 degrees)> Gloss value (85 degrees)
Gloss value (60 degrees)> 80 is satisfied ×: The above is not satisfied

(Uniformity)
Visual evaluation was performed to confirm whether or not the portion where the metallic feeling was obtained was uniform. In this case, it is preferable to be uniform.

(Abrasion)
10 reciprocating surfaces were rubbed with a Kimwipe, and the case where the surface did not peel off was marked with ◯, and the case where the surface was peeled off was marked with X.

(Comparative Example 1)
The shuttle ink type inkjet recording printer 1 was filled with the metallic ink D in the metallic ink jet head Me, and printing was performed according to the following procedure. As recording media, PET (Bueful, manufactured by Kimoto Co., Ltd.) and coated paper (OK Top Coat, manufactured by Oji Paper Co., Ltd.) were used.
1) First feed scan: the head moves in the direction of arrow A in FIG. First, metallic ink was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head Me for metallic ink (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. )
Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp.
2) First return scan: the head moves in the direction of arrow B in FIG. Metallic was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the metallic ink inkjet head Me (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. ). Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV1 ultraviolet irradiation lamp.
3) Feed of recording medium: The recording medium was fed by 52.6 mm, which is 1 cm less than the head width (53.6 mm).
4) The above procedures 1) to 3) were repeated to produce a printed matter having an area of about 30 cm × about 30 cm.
5) After printing, metallic feeling, uniformity, and scratching were evaluated according to the above evaluation criteria.

(Comparative Example 2)
The shuttle scan type ink jet recording printer 1 was filled with the metallic ink D and the transparent ink F, and printing was performed according to the following procedure. Note that PET (Buyfull, manufactured by Kimoto Co., Ltd.) was used as the recording medium.
1) First feed scan: the head moves in the direction of arrow A in FIG. First, metallic D was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head Me for metallic ink (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. ) The recording medium was irradiated with ultraviolet rays with a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set so that the curing rate at this time would be over 85%.
2) First return scan: the head moves in the direction of arrow B in FIG. Transparent In F was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. is there.). Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide. Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set wide so that the curing rate at this time would be 90% or more.
3) Second feed scan: The head moves in the direction of arrow A in FIG. The metallic ink D was ejected onto the recording medium from the metallic ink inkjet head Me at a droplet ejection density of 300 dpi × 1,200 dpi (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. is there.). The recording medium was irradiated with ultraviolet rays with a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set so that the curing rate at this time would be over 85%.
4) Second return scan: the head moves in the direction of arrow B in FIG. Transparent ink F was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (by adjusting the voltage and the number of pulses so that the ejection amount from one nozzle was 42 pL. is there.). Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide. Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set wide so that the curing rate at this time would be 90% or more.
5) Feed of recording medium: The recording medium was fed by 52.6 mm, which is 1 cm less than the head width (53.6 mm).
6) The above procedures 1) to 5) were repeated to produce a printed material having an area of about 30 cm × about 30 cm.
7) After printing, metallic feeling, uniformity, and scratching were evaluated according to the above evaluation criteria.

(Example 2)
The shuttle scan type ink jet recording printer 1 was filled with the metallic ink D and the transparent ink F, and printing was performed according to the following procedure. Note that PET (Buyfull, manufactured by Kimoto Co., Ltd.) was used as the recording medium.
1) First feed scan: the head moves in the direction of arrow A in FIG. First, metallic ink D was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the metallic ink inkjet head Me (the voltage and the number of pulses were set so that the ejection amount from one nozzle was 42 pL. Adjusted). The recording medium was irradiated with ultraviolet rays with a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set narrow so that the curing rate at this time would be 80 to 85%.
2) First return scan: the head moves in the direction of arrow B in FIG. Transparent ink F was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (by adjusting the voltage and the number of pulses so that the ejection amount from one nozzle was 42 pL. is there.). Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide. Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set wide so that the curing rate at this time would be 90% or more.
3) Second feed scan: The head moves in the direction of arrow A in FIG. The metallic ink D was ejected onto the recording medium from the metallic ink inkjet head Me at a droplet ejection density of 300 dpi × 1,200 dpi (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. is there.). The recording medium was irradiated with ultraviolet rays with a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set narrow so that the curing rate at this time would be 80 to 85%.
4) Second return scan: the head moves in the direction of arrow B in FIG. Transparent ink F was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (by adjusting the voltage and the number of pulses so that the ejection amount from one nozzle was 42 pL. is there.). Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide. Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set wide so that the curing rate at this time would be 90% or more.
5) Feed of recording medium: The recording medium was fed by 52.6 mm, which is 1 cm less than the head width (53.6 mm).
6) The above procedures 1) to 5) were repeated to produce a printed material having an area of about 30 cm × about 30 cm.
7) After printing, metallic feeling, uniformity, and scratching were evaluated according to the above evaluation criteria.

(Example 3)
The shuttle scan type ink jet recording printer 1 was filled with the metallic ink D and the transparent ink F, and printing was performed according to the following procedure. Note that PET (Buyfull, manufactured by Kimoto Co., Ltd.) was used as the recording medium.
1) First feed scan: the head moves in the direction of arrow A in FIG. First, metallic ink D was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the metallic ink inkjet head Me (the voltage and the number of pulses were set so that the ejection amount from one nozzle was 42 pL. Adjusted). The recording medium was irradiated with ultraviolet rays with a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set to be further narrow so that the curing rate at this time was 50 to 60%.
2) First return scan: the head moves in the direction of arrow B in FIG. Transparent ink F was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (by adjusting the voltage and the number of pulses so that the ejection amount from one nozzle was 42 pL. is there.). Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide. Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set wide so that the curing rate at this time would be 90% or more.
3) Second feed scan: The head moves in the direction of arrow A in FIG. The metallic ink D was ejected onto the recording medium from the metallic ink inkjet head Me at a droplet ejection density of 300 dpi × 1,200 dpi (the voltage and the number of pulses were adjusted so that the ejection amount from one nozzle was 42 pL. is there.). The recording medium was irradiated with ultraviolet rays with a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set to be further narrow so that the curing rate at this time was 50 to 60%.
4) Second return scan: the head moves in the direction of arrow B in FIG. Transparent ink F was ejected onto the recording medium at a droplet ejection density of 300 dpi × 1,200 dpi from the inkjet head T1 for transparent ink (by adjusting the voltage and the number of pulses so that the ejection amount from one nozzle was 42 pL. is there.). Note that the nozzle position and angle in the sub-scanning direction and the ejection time are adjusted so that the center point of the dot from the inkjet head T1 and the dot from the inkjet head Me coincide. Immediately thereafter, the recording medium was irradiated with ultraviolet rays using a UV2 ultraviolet irradiation lamp. In addition, the opening width of the slit was set wide so that the curing rate at this time would be 90% or more.
5) Feed of recording medium: The recording medium was fed by 52.6 mm, which is 1 cm less than the head width (53.6 mm).
6) The above procedures 1) to 5) were repeated to produce a printed material having an area of about 30 cm × about 30 cm.
7) After printing, metallic feeling, uniformity, and scratching were evaluated according to the above evaluation criteria.

Example 4
The single-pass printer shown in FIG. 4 was filled with metallic ink D and transparent ink F, and printing was performed according to the following procedure. Here, the transparent ink F was filled in 40 black ink heads. PET (Bueful, manufactured by Kimoto Co., Ltd.) was used as the recording medium.
Further, cyan 35, magenta 37 and yellow 39 were filled with cyan KO215, magenta KO867, and yellow KI052 from the UVJet series manufactured by FUJIFILM Specialty Ink Systems, respectively.
1) The recording medium is transported by rotating the feeder 42 and the winder 43 in the direction of the arrow in FIG.
2) Metallic ink D was ejected onto the recording medium at a droplet ejection density of 600 dpi × 1,200 dpi from the inkjet head unit 33 for metallic ink (the voltage and the number of pulses so that the ejection amount from one nozzle is 21 pL) Have been adjusted.)
3) The transparent ink F was ejected onto the recording medium at a droplet ejection density of 600 dpi × 1,200 dpi from the black ink inkjet head unit 40 filled with the transparent ink F (the ejection amount from one nozzle was 21 pL). The voltage and the number of pulses are adjusted so that The position and angle in the nozzle array direction and the droplet ejection timing are adjusted so that the centers of the metallic ink dots and the transparent ink dots overlap.
4) Irradiated with a metal halide lamp 41 to cure the metallic ink / transparent ink layer.
5) According to the above procedure, a printed matter having an area of about 10 cm × 30 cm was prepared.
6) After printing, metallic feeling, uniformity, and scratching were evaluated according to the above evaluation criteria.
Note that cyan, magenta, and yellow inks were recorded from the head unit portions of cyan 35, magenta 37, and yellow 39 at a droplet ejection density of 600 dpi × 1,200 dpi between steps 3) and 4). On the medium, each was ejected so as to partially overlap the area where the metallic ink was ejected.

(Comparative Example 3)
In the procedure of Example 5, printing was performed without applying transparent ink.

DESCRIPTION OF SYMBOLS 1 Shuttle scan type inkjet recording printer, 2 Inkjet recording head unit, 3 Maintenance unit, 4 Power unit, 5 Fixed shaft, 6 Control unit, 7 Recording medium suction stage, 8 Ink tank, 9 Recording medium, 10 Roller for recording medium conveyance, 11 Roller for recording medium winding, 21-27 Headset, 28, 29 UV curable lamp, 30 Disc filter, 31 Roll coater for transparent ink, 32, 34, 36, 38 Light source, 33, 35, 37, 39, 40 Head unit section, 41 Metal halide lamp, 42 Feeder, 43 Winder, 44 Recording medium

Claims (19)

An image forming process for forming an image by discharging effect pigment ink onto a recording medium;
A transparent ink applying step for applying a transparent ink on a recording medium; and
A curing process for curing the effect pigment ink and the transparent ink on the recording medium in this order,
Between the image forming step and the transparent ink application step, there is no step of curing the effect pigment ink, or when it has, the curing rate of the effect pigment ink is 85% or less,
The transparent ink contains a polymerization initiator and a polymerizable compound, and contains substantially no pigment,
The ink-jet recording method, wherein the effect pigment ink contains an effect pigment, a polymerization initiator, and a polymerizable compound.   2. The curing rate of the effect pigment ink is 60% or less when the effect pigment ink is not included or is included between the image forming step and the transparent ink application step. The ink jet recording method described in 1.   The inkjet recording method according to claim 1 or 2, wherein in the transparent ink application step, the transparent ink is applied so as to overlap with the effect pigment ink applied on the recording medium.   The ink-jet recording method according to any one of claims 1 to 3, wherein in the transparent ink applying step, the transparent ink is applied so as to cover a region to which the effect pigment ink is applied on the recording medium. The inkjet recording method according to any one of claims 1 to 4, wherein the effect pigment is a tabular particle, and the shape of the effect pigment satisfies the following formulas (1) and (2).
0.5 μm ≦ R ₅₀ ≦ 5 μm (1)
R ₅₀ / d> 5 (2)
(In Formula (1) and Formula (2), R ₅₀ is the 50% average particle diameter in the equivalent circle diameter determined from the plane area of the particles, and d is the plate thickness.)   The ink jet recording method according to claim 1, wherein the effect pigment is a metal pigment or a pearl pigment.   The ink jet recording method according to any one of claims 1 to 6, wherein the effect pigment is a tabular grain formed from a multi-layer of thin layers.   The ink jet recording method according to claim 1, wherein a material of the effect pigment is aluminum or an aluminum alloy. The inkjet recording method according to claim 1, wherein the following formula (3) is satisfied when the surface tension of the effect pigment ink is γk and the surface tension of the transparent ink is γs.
−10 mN / m ≦ γs−γk ≦ 5 mN / m (3) The inkjet recording method according to any one of claims 1 to 9, wherein when the surface tension of the effect pigment ink is γk and the surface tension of the transparent ink is γs, the following formula (4) is satisfied.
30 mN / m ≦ γs <γk ≦ 40 mN / m (4) The inkjet recording method according to any one of claims 1 to 10, wherein the effect pigment ink contains a polymerizable compound selected from the group consisting of the following group 1 in an amount of 40% by weight or more based on the total polymerizable compound.
(Group 1)
N-vinylcaprolactam, N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide, tetrahydrofurfuryl acrylate, cyclic trimethylolpropane formal acrylate, 2-phenoxyethyl acrylate, triethylene glycol diacrylate , Tetraethylene glycol diacrylate, trimethylolpropane triacrylate, ethylene oxide modified trimethylolpropane triacrylate The inkjet recording method according to any one of claims 1 to 11, wherein the effect pigment ink contains a polymerizable compound selected from the group consisting of the following group 2 in an amount of 45% by weight or more based on the total polymerizable compound.
(Group 2)
N-vinylcaprolactam, 2-phenoxyethyl acrylate The inkjet recording method according to claim 1, wherein the transparent ink contains a polymerizable compound selected from the group consisting of the following group 3 in an amount of 60% by weight or more based on the total polymerizable compound.
(Group 3)
Octyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, isophoryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, 1,6-hexanediol diacrylate, 3-methyl-1,5- Pentanediol diacrylate, dipropylene glycol diacrylate, propylene oxide modified trimethylolpropane triacrylate The inkjet recording method according to claim 1, wherein the transparent ink contains a polymerizable compound selected from the group consisting of the following group 4 in an amount of 60% by weight or more based on the total polymerizable compound.
(Group 4)
Isobornyl acrylate, isophoryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate   The inkjet recording method according to claim 1, wherein the transparent ink further contains a surfactant.   The inkjet recording method according to claim 15, wherein the surfactant is a nonionic surfactant.   The inkjet recording method according to claim 15 or 16, wherein the surfactant is a polymer having a poly (meth) acrylate skeleton.   The transparent ink is provided in an upper layer of the effect pigment ink, and a part of the polymerizable compound in the effect pigment ink diffuses into the transparent ink, thereby bringing the effect pigment into a higher concentration state than the initial state of the effect pigment ink. The inkjet recording method according to claim 1, which has a holding function.   A printed matter obtained by the ink jet recording method according to claim 1.

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