JP7356533B1 - ink set - Google Patents

Abstract

The present invention provides an ink set with excellent visibility and gradation and a wide color reproduction range. [Solution] In an ink set including at least cyan ink, magenta ink, and yellow ink, regarding the hiding rate (%) of a dry film with a thickness of 10 μm formed from each ink, the hiding rate in the case of cyan ink is Ch , where Mh is the hiding rate for magenta ink and Yh is the hiding rate for yellow ink, Ch, Mh, and Yh are all 10% or more, and the following relational expressions (1) to (3) are satisfied. ) is an ink set that satisfies all of the following. Formula (1) 0 ≦ |Ch-Mh| ≦ 25% Formula (2) 0 ≦ |Mh-Yh| ≦ 25% Formula (3) 0 ≦ |Yh-Ch| ≦ 25% [Selection diagram] None

Description

The present invention relates to an ink set, and particularly to an ink set that has excellent visibility and gradation, and has a wide color reproduction range.

The scope of application of inkjet printing is not limited to printing paper and film, but demands are increasing for various media and applications, such as decoration of three-dimensional objects and durability that can withstand long-term outdoor use. In order to improve the design of printed matter, various methods have been proposed to widen the color reproduction range (gamut).

JP-A-2011-116876 (Patent Document 1) describes an invention relating to an ink set including cyan ink, magenta ink, yellow ink, light magenta ink, light cyan ink, orange ink, and green ink. Patent Document 1 discloses an ink set in which the color reproduction range (gamut) is expanded by limiting the pigment used in each ink to a specific pigment type, and in particular, the color reproduction range in the blue region of dark areas is expanded. , it is stated that an ink set with excellent color reproducibility in other color areas can be provided. Further, the ink set described in Patent Document 1 is described as being an ink set that has excellent graininess in a high brightness region where graininess is easily noticeable.

Japanese Unexamined Patent Publication No. 2014-159525 (Patent Document 2) describes an invention relating to an active energy ray-curable inkjet recording ink set containing at least magenta ink, cyan ink, and yellow ink. In Patent Document 2, by setting the ratio of the median diameter of pigments used in each ink within a specific range, the color development property of multi-order colors, especially the color development properties of orange, green, and violet multi-order colors, is excellent. It is described that an active energy ray-curable inkjet recording ink set can be provided.

Japanese Unexamined Patent Publication No. 2015-218218 (Patent Document 3) describes an invention related to an ink set for building materials including cyan ink, magenta ink, yellow ink, and green ink. Patent Document 3 states that since ink for building materials is mainly used outdoors, it suffers from fading and discoloration due to wind, rain and sunlight, and there is a problem in which color reproducibility cannot be maintained immediately after production, and it is necessary to improve weather resistance. By using Pigment Red 101 as the magenta inorganic pigment, we improved weather resistance, and by using green ink, we compensated for the narrow color gamut caused by Pigment Red 101 and improved color reproducibility. It is stated that it has been improved.

JP 2021-6615 A (Patent Document 4) describes an invention related to an ink set for single-pass printing that includes at least cyan ink, magenta ink, yellow ink, and gray ink. In Patent Document 4, when reproducing a gray color, from the viewpoint of graininess, it is preferable to reproduce using three colors of CMY or four colors of CMYK rather than using only K. There was a problem that metamerism occurred when reproducing using gray ink, and by using gray ink, metamerism was improved compared to reproducing gray colors with cyan, magenta ink, and yellow ink. It is stated that graininess is improved compared to the case where gray color is reproduced using only black.

International Publication No. 2002/100959 (Patent Document 5) describes in addition to three color inks of yellow, magenta and cyan whose hue angle ∠H° defined in the CIELAB color space on the recording medium is within a specific range. The invention relates to an ink set that includes one or two special color inks whose hue angle ∠H° defined in the CIELAB color space on a recording medium falls within a specific range. In Patent Document 5, there was a problem that the color development of secondary colors was significantly reduced in YMC three-color ink in which the pigment solid content in the ink was reduced in order to improve graininess and gloss. It is stated that by using special color ink, it is possible to widen the reproduction range of chroma without causing a decrease in graininess and gloss.

Further, within the scope of application of inkjet printing, examples of application to articles that are used outdoors for a long time include building material applications such as ceramic siding, metal siding, and ceramic tiles.

Japanese Unexamined Patent Publication No. 2013-49813 (Patent Document 6) describes an invention relating to a method for manufacturing a decorative building material, which includes a step of forming an ink layer using an inkjet ink containing a specific black pigment. Patent Document 6 describes that by using a specific black pigment, it is possible to suppress the temperature rise of the building material even when exposed to sunlight, and to provide a decorative building material with excellent durability.

Japanese Patent Application Publication No. 2011-116876 Japanese Patent Application Publication No. 2014-159525 Japanese Patent Application Publication No. 2015-218218 JP 2021-6615 Publication International Publication No. 2002/100959 JP2013-49813A

As described in Patent Documents 1 and 3 to 5, although it is possible to expand the color reproduction range by increasing the number of ink colors that make up the ink set, there is an increase in the initial installation cost of the recording device, a print head, etc. This increases the initial cost, such as an increase in the cost of consumable parts, and a significant increase in the amount of ink required to obtain an image with the same density as when using CMY three-color ink when light color ink is used together. There are major disadvantages in terms of both running costs.

In addition, as described in Patent Documents 1 to 3, 5, and 6, the method of individually selecting the type, particle size, and hue angle of pigments does not necessarily produce printed matter with excellent gradation when mixing inks. You may not be able to get it. In particular, Patent Document 6 discloses an ink set that uses an organic pigment with excellent coloring properties and an inorganic pigment with poor coloring properties. is difficult to obtain.

Furthermore, conventional chromatic inks have low hiding power and transmit light, so when printing on transparent substrates or colored substrates other than white, image visibility is required. , it was necessary to provide a concealing layer such as white ink or other base coat layer as a base to supplement visibility.

Therefore, there is a need for a method that can obtain a wide color reproduction range with a smaller number of ink colors and can be used with a wide range of media.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ink set that has excellent visibility and gradation and a wide color reproduction range.

In order to achieve the above object, the present inventors conducted intensive studies and found that while increasing the hiding rate of each of the three color inks of cyan, magenta, and yellow, the difference in hiding rate among the inks was reduced to a specific range. By suppressing this, it is possible to provide printed matter with excellent visibility even on transparent substrates and colored substrates other than white, and it also improves the color development of each color alone and the gradation when mixed colors, and improves color reproducibility. The inventors have discovered that it is possible to provide printed matter with excellent quality, and have completed the present invention.

Therefore, one aspect of the present invention is an ink set including at least cyan ink, magenta ink, and yellow ink, wherein the hiding rate (%) of a dry film with a thickness of 10 μm formed from each ink is If Ch is the concealing rate for magenta ink, Mh is the concealing rate for magenta ink, and Yh is the concealing rate for yellow ink, then Ch, Mh, and Yh are all 10% or more, and the following relational expression is satisfied. This ink set is characterized by satisfying all of (1) to (3).
Formula (1) 0 ≦ |Ch−Mh| ≦ 25%
Formula (2) 0 ≦ |Mh-Yh| ≦ 25%
Formula (3) 0 ≦ |Yh-Ch| ≦ 25%

In a preferred example of the ink set of the present invention, the hue angle ∠H° of a 10 μm thick dry film formed from cyan ink is in the range of 230° to 270°, and the 10 μm thick dry film formed from magenta ink is in the range of 230° to 270°. The hue angle ∠H° of the dried film is in the range of 26° to 42°, and the hue angle ∠H° of the dried film formed from the yellow ink with a thickness of 10 μm is in the range of 75° to 110°, The hue angle ∠H° of a 10 μm thick dry film formed from cyan, magenta and yellow inks is obtained on a white base.

In another preferred example of the ink set of the present invention, the hue angle ∠H° of a 10 μm thick dry film formed by mixing cyan ink and magenta ink at a volume ratio of 1:1 is −20° to 25°. In addition, the hue angle ∠H° of a 10 μm thick dry film formed by mixing magenta ink and yellow ink at a volume ratio of 1:1 is in the range of 43° to 74°. The hue angle ∠H° of a 10 μm thick dry film formed by mixing cyan ink at a volume ratio of 1:1 is in the range of 111° to 160°, and the hue angle ∠H° is in the range of 111° to 160°. The hue angle ∠H° of a dry film with a thickness of 10 μm formed by color mixing in a 1:1 volume ratio of magenta ink and yellow ink and color mixture of yellow ink and cyan ink in a 1:1 volume ratio is Obtained on a white base.

In another preferred embodiment of the ink set of the present invention, Ch, Mh, and Yh are all within the range of 55±25%.

In another preferred embodiment of the ink set of the present invention, one or more of the cyan ink, magenta ink and yellow ink contains a white pigment.

According to the present invention, it is possible to provide an ink set that is excellent in visibility and gradation and has a wide color reproduction range.

The present invention will be explained in detail below.

One aspect of the present invention is an ink set that includes at least cyan ink, magenta ink, and yellow ink. In this specification, this ink set is also referred to as the "ink set of the present invention."

The ink set of the present invention is an ink set that includes at least three colors of CMY, cyan ink (Y), magenta ink (M), and yellow ink (Y), but is not limited to this, and includes black Other inks such as ink (K), special color inks such as orange ink, green ink, violet ink, light cyan ink, light magenta ink, bright color ink such as metallic or pearl, and even clear ink not intended for coloring. May include.

In the ink set of the present invention, regarding the hiding rate (%) of a dry film with a thickness of 10 μm formed from each ink, the hiding rate is Ch for cyan ink, Mh for magenta ink, and Mh for yellow ink. When the concealment rate in the case is Yh, Ch, Mh, and Yh are all 10% or more, and all of the following relational expressions (1) to (3) are satisfied.
Formula (1) 0 ≦ |Ch−Mh| ≦ 25%
Formula (2) 0 ≦ |Mh-Yh| ≦ 25%
Formula (3) 0 ≦ |Yh-Ch| ≦ 25%

According to the ink set of the present invention, although the number of colors is small, that is, the three color inks of cyan, magenta, and yellow, the concealment rate of each of the three color inks of CMY is increased, and the difference in the concealment rate between the inks is reduced. By keeping it within a specific range, it is possible to provide printed materials with excellent visibility even on transparent substrates and colored substrates other than white, and the color development of each color alone and the gradation when mixed colors are improved. We can also provide printed matter with excellent color reproducibility. As a result, various designs can be applied to various base materials in vivid colors.

In the ink set of the present invention, Ch, Mh and Yh are all 10% or more, preferably 20% or more. By increasing the hiding rate, color development can be improved. On the other hand, when the hiding rate is less than 10%, the color reproduction area when colors are mixed becomes small. In addition, if the hiding rate is too high, the saturation will decrease and the color will become dull, and when ejecting ink from an inkjet printer to create a mixed color expression, the second ink droplet will be placed on top of the first ink droplet. When the droplets overlap, if the first ink droplet is covered up by the second ink droplet to the extent that it affects the color development of the first ink droplet, the color reproducibility of mixed colors is not excellent. Therefore, Ch, Mh and Yh are all preferably within the range of 55±25% (30% to 80%), and preferably within the range of 55±20% (35% to 75%). More preferably, it is within the range of 55±15% (40% to 70%).

In the ink set of the present invention, Ch, Mh and Yh satisfy all of the relational expressions (1) to (3). If there is a combination in which the difference in concealment rate is 26% or more among the three CMY color inks, it will be difficult to express mixed colors, and the color reproduction area will become smaller.

In the ink set of the present invention, it is preferable that Ch, Mh and Yh satisfy all of the relational expressions (4) to (6).
Formula (4) 0 ≦ |Ch−Mh| ≦ 23%
Formula (5) 0 ≦ |Mh-Yh| ≦ 23%
Formula (6) 0 ≦ |Yh-Ch| ≦ 23%

In this specification, the hiding rate of a dry film is measured according to method B (hiding rate test paper) of JIS K-5600-4-1:1999. A specific measurement example is shown below.
After printing a monochrome solid image on the white and black areas of the hiding rate test paper using an inkjet printer, each L ^* value is measured using a spectrophotometer, and it is derived by taking the ratio of the two values.
Example: When the L ^* value of the ink dry film on the white printed area is Lw, and the L ^* value of the ink dry film on the black background printed area is Lb, the hiding rate of the dry film can be calculated using the following equation (7). .
Concealment rate (%) = 100 x Lb / Lw...Formula (7)
Note that the dry ink film thickness when measuring the hiding rate is 10 μm.
In this specification, an ink dry film is produced by the method shown below.
(Example) Using an inkjet printer (for example, an inkjet printer equipped with a KM1024-LHB head (42 pl droplets, manufactured by Konica Minolta)), print each CMY monochrome solid image (resolution 360 x 360 dpi) on a concealment rate test paper. Print on white and black backgrounds. Thereafter, the ink is cured using a metal halide lamp to obtain a dried ink film. The thickness of the dried ink film is measured with a micrometer (for example, MDC-25MJ, manufactured by Mitutoyo Co., Ltd.).

Examples of means for adjusting the hiding rate of cyan ink, magenta ink, and yellow ink include selection of pigment type and pigment particle size. The pigments contained in each ink may be used alone or in combination of two or more. Furthermore, as a means to increase the hiding rate, it is also effective to use a white pigment in cyan ink, magenta ink, and yellow ink. In particular, since it is often difficult to ensure a good hiding rate with cyan ink and yellow ink, it is preferable to use a white pigment.

The pigment used in the present invention is not particularly limited as long as it is a pigment normally used in inkjet inks, and any known pigment can be used.

The pigment used for cyan ink is C. I. Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 16, 17:1, 24, 24:1, 25, 26, 27, 28, 29, 36, 56, 60, 61, 62, 63, 75, 79, 80 and the like.
Among these, preferred pigments are C.I. I. Pigment Blue 15:3, 15:4, 28 and the like.

The pigment used for magenta ink is C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 31, 32, 38, 41, 48, 48:1, 48:2, 48:3, 48:4, 48:5, 49, 52, 52:1, 52:2, 53:1, 54, 57:1, 58, 60: 1, 63, 64:1, 68, 81:1, 83, 88, 89, 95, 101, 104, 105, 108, 112, 114, 119, 122, 123, 136, 144, 146, 147, 149, 150, 164, 166, 168, 169, 170, 171, 172, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 187, 188, 190, 193, 194, 200, 202, 206, 207, 208, 209, 210, 211, 213, 214, 216, 220, 220, 221, 224, 226, 237, 238, 239, 242, 245, 247, 248, 251, 253, 254, 255, 256, 257, 258, 260, 262, 263, 264, 266, 268, 269, 270, 271, 272, 279, 282 and the like.
Among these, preferred pigments are C.I. I. Pigment Red 101 and the like.

The pigment used for yellow ink is C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 14, 15, 16, 17, 24, 32, 34, 35, 36, 37, 41, 42, 43, 49, 53, 55, 60, 61, 62, 63, 65, 73, 74, 75, 77, 81, 83, 87, 93, 94, 95, 97, 98, 99, 100, 101, 104, 105, 106, 108, 109, 110, 111, 113, 114, 116, 117, 119, 120, 123, 124, 126, 127, 128, 129, 130, 133, 138, 139, 150, 151, 152, 153, 154, 155, 165, 167, 168, 169, 170, 172, 173, 174, 175, 176, 179, 180, 181, 182, 183, 184, 185, 191, 193, 194, 199, 205, 206, 209, 212, 213, 214, 215, 219 and the like.
Among these, preferred pigments are C.I. I. Pigment Yellow 42, 120, 138, 150, 151, 155, 184, 213 and the like.

In the ink set of the present invention, the pigments are not limited to the above-mentioned preferred pigments, and other pigments can also be used in the cyan ink, magenta ink, and yellow ink.

Although both organic pigments and inorganic pigments can be used for cyan ink, magenta ink, and yellow ink, it is preferable to use inorganic pigments because they have excellent weather resistance.

The amount of pigment in each of the cyan ink, magenta ink and yellow ink is, for example, 5 to 25% by weight, preferably 6 to 20% by weight. If the amount of pigment is small, even if the pigment has excellent hiding properties, it may not be able to exhibit sufficient hiding properties, and there may be problems in color reproducibility. Moreover, if the amount of pigment is large, the hiding power becomes too high, which may cause difficulty in color reproducibility of mixed colors.

In the ink set of the present invention, it is preferred that one or more of the cyan ink, magenta ink, and yellow ink contain a white pigment. White pigments are preferable from the viewpoint of increasing the hiding rate. Furthermore, when the cyan ink, magenta ink, and yellow ink contain an inorganic pigment, it is preferable to use a white pigment in combination, especially when the cyan ink and the yellow ink contain an inorganic pigment. Examples of the white pigment include inorganic pigments such as titanium oxide and zinc sulfide. The amount of white pigment in each of the cyan ink, magenta ink, and yellow ink is, for example, 1 to 25% by mass, preferably 5 to 15% by mass, of the total amount of pigment contained in the ink. If the amount of white pigment is small, sufficient improvement in hiding property cannot be obtained. Furthermore, if the white pigment is too large, the hiding power becomes too high and it also affects the color of the ink.

As a white pigment, C. I. Pigment White 1, 2, 4, 5, 6, 7, 11, 12, 18, 19, 21, 22, 23, 26, 27, 28, hollow particles, and the like.
Among these pigments, C.I. I. Pigment White 6 and the like.

The average dispersed particle diameter D50 of the pigment used in cyan ink, magenta ink and yellow ink is preferably within the range of 20 to 500 nm, more preferably within the range of 30 to 450 nm, and preferably within the range of 40 to 400 nm. More preferably, it is within the range.

The average dispersed particle diameter D50 of the white pigment in each of the cyan ink, magenta ink and yellow ink is preferably within the range of 50 to 400 nm, more preferably within the range of 80 to 350 nm, and 100 nm. More preferably, it is 300 nm.

In this specification, the average dispersed particle size D50 of the pigment refers to the 50% particle size ( _D50 ) of the volume-based particle size distribution of the pigment dispersed in the ink, and is measured using a particle size distribution measuring device (e.g. laser diffraction/scattering type It can be determined from the particle size distribution measured using a particle size distribution measuring device. The particle size is expressed as a sphere-equivalent diameter determined by laser diffraction/scattering method.

In the ink set of the present invention, it is preferable that the L ^* value of the cyan ink expressed in CIE (1976) L ^* a ^* b ^* color space is within the range of 50 to 85, and the L ^* value of the magenta ink is 40. The L ^* value of the yellow ink is preferably within the range of 50 to 90. L ^* indicates the brightness (lightness) of the color, where L ^* =0 indicates black and L ^* =100 indicates white. The above L ^* value is obtained, for example, on a white background portion of a hiding rate test paper. When the L ^* value of each ink is within the range specified above, the brightness and darkness of each color are balanced, and the color mixture expression of light to dark colors is excellent. Note that a ^* and b ^* indicate chromaticity indicating hue and saturation. a ^* represents the position of the color between red and green, with negative values indicating green and positive values indicating red. b ^* represents the position of the color between yellow and blue, with negative values indicating blue and positive values indicating yellow.

To give an example of values other than the L ^* value, the a ^* value and b ^* value of cyan ink are -1 to -23 and -48 to -18, respectively, and the a ^* value and b ^* value of magenta ink are respectively 25 to 65 and -13 to 58, and the a ^* value and b ^* value of yellow ink are -20 to 8 and 38 to 88, respectively, and the above a ^* value and b ^* value are, for example, Obtained on a white background.

Examples of means for adjusting L ^* a ^* b ^* of cyan ink, magenta ink, and yellow ink include selection of pigment types. In particular, as means for adjusting the L ^* value of cyan ink, magenta ink, and yellow ink to the range specified above, in addition to selecting the pigment type, adjustment of the average dispersed particle diameter of the pigment, adjustment of the pigment concentration in the ink, For example, a white pigment may be used in combination.

In this specification, the L ^* value, a ^* value, and b ^* value of an ink are defined as a specific value in the CIE (1976) L ^* a ^* b ^* color space as defined in JIS Z 8781-4:2013. It is a color coordinate calculated by the formula, and can be measured without particular limitation by a method commonly used in the art, for example, using a spectrophotometer (for example, SpectroEye, manufactured by X-Rite). can be measured.

In the ink set of the present invention, the hue angle ∠H° of the 10 μm thick dry film formed from the cyan ink is preferably within the range of 230° to 270°, and preferably within the range of 235° to 270°. It is more preferable that the angle is within the range of 235° to 265°. Further, the hue angle ∠H° of a 10 μm thick dry film formed from magenta ink is preferably within the range of 26° to 42°, more preferably within the range of 28° to 42°. , more preferably within the range of 30° to 42°. The hue angle ∠H° of a dry film with a thickness of 10 μm formed from yellow ink is preferably within the range of 75° to 110°, more preferably within the range of 78° to 110°, and 78° More preferably, the hue angle ∠H° is within the range of 108° to 108°, and the hue angle ∠H° is obtained, for example, on a white background portion of a hiding rate test paper. By setting the hue angle ∠H° of each ink within the range specified above, it becomes easy to improve the color reproducibility of single colors and mixed colors.

Examples of means for adjusting the hue angle of a dry film formed from cyan ink, magenta ink, and yellow ink include selection of pigment species, adjustment of pigment particle size, and adjustment of pigment concentration in the ink.

In this specification, the hue angle ∠H° of a dry film formed from ink is also referred to as CIELAB 1976 ab hue angle, h _ab (CIE 1976 a,b hue-angle), and is defined in JIS Z 8781-4:2013. As specified, it is the amount of hue correlation calculated by Equation (11) in 4.2 in the CIE (1976) L ^* a ^* b ^* color space, and for example, the a of the ink calculated as above ^* value and b ^* value. Further, the hue angle ∠H° of the dry film formed by mixing colors can also be determined in the same manner as above.

In the ink set of the present invention, the hue angle ∠H° of a 10 μm thick dry film formed by mixing cyan ink and magenta ink at a volume ratio of 1:1 is within the range of -20° to 25°. The angle is preferably within the range of -15° to 25°, more preferably within the range of -10° to 25°. Further, the hue angle ∠H° of a 10 μm thick dry film formed by mixing magenta ink and yellow ink at a volume ratio of 1:1 is preferably within the range of 43° to 74°, and is 43°. It is more preferably within the range of ~70°, and even more preferably within the range of 43° ~ 68°. The hue angle ∠H° of a 10 μm thick dry film formed by mixing yellow ink and cyan ink at a volume ratio of 1:1 is preferably within the range of 111° to 160°, and 111° to 159°. More preferably, the angle is within the range of 111° to 158°. The hue angle ∠H° is obtained, for example, on a white background portion of a hiding rate test paper. When the hue angle ∠H° of the dry film formed by mixed colors is within the range specified above, a printed matter with excellent color reproducibility of mixed colors can be obtained.
Here, color mixing refers to a method of printing monochrome solid images one on top of the other. For example, a dry film formed by mixing cyan ink and magenta ink at a volume ratio of 1:1 is a monochrome solid image printed from cyan ink and a monochrome image printed from magenta ink at a volume ratio of 1:1. Refers to a dry film obtained by overlapping printing with a solid image.

Means for adjusting the hue angle of the dry film formed when cyan ink and magenta ink, magenta ink and yellow ink, and yellow ink and cyan ink are mixed include selection of pigment type and adjustment of pigment concentration in ink. etc.

Next, preferred embodiments of ink that can be used in the ink set of the present invention will be described. What is described herein applies to any of the cyan, magenta, and yellow inks described above, as well as other inks that may be used, unless otherwise specified.

The ink used in the present invention is preferably an ink for printing with a droplet discharge type printing device, and is particularly preferably an inkjet ink, but is not limited thereto, and includes gravure printing, offset It is also possible to perform the printing using various printing methods such as a printing method, a flexo printing method, a screen printing method, and a coater method.

A droplet ejection type printing device is a printing device that ejects ink droplets from a printing device (particularly a print head) and makes them land on a base material, and includes an inkjet printer and the like. Note that in this specification, inkjet ink means ink used in inkjet printers.

Examples of the inkjet printer include an inkjet printer that ejects an ink composition using a charge control method or a piezo method. Furthermore, large-sized inkjet printers, specifically inkjet printers intended for printing on articles produced on industrial lines, can also be suitably used.

The ink used in the present invention is preferably an ink that can be cured by irradiation with active energy rays such as ultraviolet rays, visible light, and electron beams. Such ink is generally referred to as "active energy ray curable ink." Furthermore, an ink set including an active energy ray curable ink may be referred to as an "active energy ray curable ink set."

The ink used in the present invention preferably contains a polymerizable compound and a photopolymerization initiator.

A polymerizable compound undergoes a polymerization reaction via a functional group exhibiting radical polymerizability (for example, a photopolymerizable unsaturated group such as a carbon-carbon double bond constituting an acryloyl group, a methacryloyl group, a vinyl group, or an allyl group). It is a compound that causes A carbon-carbon double bond exhibiting radical polymerizability is also referred to as an "ethylenic unsaturated double bond." The polymerizable compounds may be used alone or in combination of two or more.

Polymerizable compounds are classified as monofunctional polymerizable compounds or polyfunctional polymerizable compounds. Here, the monofunctional polymerizable compound includes a monofunctional polymerizable monomer having one functional group exhibiting radical polymerizability (for example, a monofunctional polymerizable monomer having one polymerizable unsaturated group) and a monofunctional polymerizable monomer having one functional group exhibiting radical polymerizability. Examples include monofunctional polymerizable oligomers having one functional group (for example, monofunctional polymerizable oligomers having one polymerizable unsaturated group). Examples of polyfunctional polymerizable compounds include polyfunctional polymerizable monomers that have two or more functional groups that exhibit radical polymerizability (e.g., polyfunctional polymerizable monomers that have two or more polymerizable unsaturated groups), and those that exhibit radical polymerizability. Examples include polyfunctional polymerizable oligomers having two or more functional groups (for example, polyfunctional polymerizable oligomers having two or more polymerizable unsaturated groups).

In the ink used in the present invention, the amount (mass %) of the monofunctional polymerizable compound contained in the ink is A, and the amount (mass %) of the polyfunctional polymerizable compound contained in the ink is B. , 0.03≦B/A≦0.30, and 50% by mass≦A+B≦95% by mass. In an ink in which the total amount of polymerizable compounds is 50 to 95% by mass, by setting the ratio of polyfunctional polymerizable compounds to monofunctional polymerizable compounds to 0.30 or less, curing shrinkage of the film can be suppressed, and the film It can improve its adhesion. This makes it possible to ensure adhesion to various base materials and coatings. Furthermore, by setting the amounts of the monofunctional polymerizable compound and the polyfunctional polymerizable compound contained in the ink at the ratios specified above, curability and film strength can be ensured. Here, B/A is preferably 0.10 to 0.30. Further, A+B is preferably 60 to 95% by mass.

The polymerizable compound contained in the ink preferably has an average number of functional groups of 1.2 or less, more preferably 1.05 to 1.2. In order to reduce the number of reaction points in the entire system to suppress curing shrinkage and provide an appropriate crosslinked structure to ensure film strength, we investigated the optimal number of reaction points and crosslinking density, and found that the polymerization contained in the ink When the average number of functional groups of the functional compound is 1.2 or less, particularly 1.05 to 1.2, it is highly effective in suppressing curing shrinkage of the film, greatly improving the adhesion of the film itself, and increasing the film strength. can be retained. This makes it possible to ensure adhesion and film strength to various substrates and coatings.

In this specification, the average number of functional groups of the polymerizable compound contained in the ink can be calculated as follows.
Average number of functional groups = [total number of ethylenically unsaturated double bonds contained in the polymerizable compound] / [total number of molecules of the polymerizable compound] ... Calculation formula (1)
Here, regarding the "total number of ethylenically unsaturated double bonds contained in the polymerizable compound" in calculation formula (1), the number of ethylenically unsaturated double bonds per molecule of the polymerizable compound is It is calculated by multiplying the total number of molecules of the compound. When multiple types of polymerizable compounds are blended into the ink, calculate the number of ethylenically unsaturated double bonds for each type, and calculate the total number of ethylenically unsaturated double bonds. To tell.
(Example of how to determine the average number of functional groups of a polymerizable compound)
The total amount of the polymerizable compound is 100 parts by mass.
Polymerizable compound A: Number of ethylenically unsaturated double bonds = 1, molecular weight X _A , 30 parts by mass Polymerizable compound B: Number of ethylenically unsaturated double bonds = 2, molecular weight X _B , 70 parts by mass Average number of functional groups = {(1×30/X _A )+(2×70/X _B )}/{(30/X _A )+(70/X _B )}

In order to adjust the average number of functional groups to 1.05 to 1.2, it is useful to use a polyfunctional polymerizable compound having a large ethylenically unsaturated double bond equivalent. The ethylenically unsaturated double bond equivalent is the value obtained by dividing the molecular weight by the number of ethylenically unsaturated double bonds contained in one molecule. When the ethylenically unsaturated double bond is derived from a (meth)acryloyl group, it is also referred to as "acrylic equivalent". Generally, the larger this value is, the wider the distance between crosslinking points is and the lower the crosslinking density, which can contribute to reducing curing shrinkage as a result.

The polymerizable compound contained in the ink preferably contains 55 to 85% by mass of a monofunctional polymerizable compound. When the amount of the monofunctional polymerizable compound is 55% by mass or more based on the entire polymerizable compound, adhesion and flexibility can be improved. Furthermore, if the proportion of the monofunctional polymerizable compound is too high, the film strength and curability will decrease, so the proportion of the monofunctional polymerizable compound to the total polymerizable compound is preferably 85% by mass or less.

The polymerizable compound contained in the ink preferably contains 1 to 20% by weight, particularly 3 to 20% by weight of a bifunctional polymerizable compound having a molecular weight of 300 to 1,500. From the viewpoint of achieving both adhesion and curability, it is preferable to use a polymerizable compound having two functional groups exhibiting radical polymerizability (bifunctional polymerizable compound). Further, from the viewpoint of suppressing curing shrinkage, it is preferable to use a polymerizable compound having a relatively high molecular weight, and the molecular weight of the bifunctional polymerizable compound is preferably 300 to 1,500, more preferably 300 to 1,300. It is more preferable that the amount of the bifunctional polymerizable compound having a molecular weight of 300 to 1,500 is 5 to 20% by mass based on the entire polymerizable compound.

In the present specification, when the polymerizable compound is an oligomer, its molecular weight can be measured as a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography.

Examples of the bifunctional polymerizable compound include bifunctional polymerizable monomers and bifunctional polymerizable oligomers. The amount of the bifunctional polymerizable compound in the ink is preferably 3 to 25% by weight, more preferably 5 to 23% by weight.

The ink used in the present invention preferably contains a polymerizable compound having a heterocyclic skeleton. By using a polymerizable compound having a heterocyclic skeleton, curability can be improved. Further, the polymerizable compound having a heterocyclic skeleton is preferably a nitrogen-containing polymerizable compound, and more preferably a polymerizable compound whose heterocyclic skeleton contains a nitrogen atom. In particular, a nitrogen-containing polymerizable compound as a polymerizable compound having a heterocyclic skeleton is highly effective in reducing polymerization inhibition caused by oxygen during curing, and can improve the curability of the ink. The amount of the polymerizable compound having a heterocyclic skeleton in the ink is preferably 1 to 10% by mass.

The ink used in the present invention preferably contains a polymerizable compound having a hydroxyl group. By using a polymerizable compound having a hydroxyl group, adhesion to the substrate and film strength can be improved by hydrogen bonds and chemical bonds via the hydroxyl group. Furthermore, like the polymerizable compound having a heterocyclic skeleton, it has the effect of reducing oxygen inhibition during curing, and can be expected to improve curability. Further, in one embodiment of the present invention, the ink contains at least one of a polymerizable compound having a hydroxyl group and a silane compound described below, and preferably contains both a polymerizable compound having a hydroxyl group and a silane compound. The amount of the polymerizable compound having a hydroxyl group in the ink is preferably 1 to 10% by mass.

〔構造式（１）中、ｎは１～３であり、Ｙはメトキシ基またはエトキシ基であり、ＲはＣ３より選ばれるアルキレン基であり、Ｚは（メタ）アクリロキシ基である。〕 The ink used in the present invention preferably contains a polymerizable compound having a silicon atom, and more preferably contains a polymerizable compound represented by the following structural formula (1). By using a polymerizable compound having a silicon atom as the silane compound, adhesion to the base material can be improved. In particular, the polymerizable compound represented by Structural Formula (1) is excellent in the effect of improving adhesion. In the ink, the amount of the polymerizable compound having a silicon atom is preferably 1 to 5% by mass.

[In structural formula (1), n is 1 to 3, Y is a methoxy group or ethoxy group, R is an alkylene group selected from C3, and Z is a (meth)acryloxy group. ]

The polymerizable compound is P. I. I. Preferably, the weighted average of the values is less than 2.00. P. I. I. is an abbreviation for Primary Irritation Index, which is translated as primary skin irritation index. The higher the primary skin irritation (P.I.I.), the more chemical irritation is caused to the skin, and the more likely symptoms such as rash will occur. This can make the work environment and personnel dangerous and difficult to handle. Furthermore, monomers that are highly irritating to the primary skin may remain in the film even after the curing process, which may pose a problem. Therefore, P. I. I. A safe ink design with low oxidation is desired. The Antibacterial Products Technology Association (SIAA) lists no irritation or mild irritation (P.I.I. (Primary Irritation Index): less than 2.00) as a safety standard. It is being

P of the polymerizable compound. I. I. The method for calculating the weighted average of values is as follows.
Polymerizable compound A: P. I. I. =P _A , mass ratio = T _A
Polymerizable compound B: P. I. I. = P _B , mass ratio = T _B
P. I. I. Weighted average of = P _A × T _A + P _B × T _B ...Formula (2)

Specific examples of monofunctional polymerizable monomers include isoamyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and tridecyl (meth)acrylate. ) acrylate, stearyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, 2-(2'-vinyloxyethoxy)ethyl (meth)acrylate ) acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4- t-Butylcyclohexyl (meth)acrylate, cyclohexyl (meth)acrylate, N-(meth)acryloylmorpholine, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl) Methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, γ-butyrolactone (meth)acrylate, N-vinylcaprolactam, N-(meth)acryloyloxyethylhexahydrophthalimide, 1-(meth)acryloylpyrrolidine- 2-one, 1-(meth)acryloylpiperidin-2-one, N-vinyl-2-pyrrolidone, N-vinylimidazole, dimethylacrylamide, hydroxyethyl(meth)acrylamide, diethylacrylamide, isopropylacrylamide, dimethylaminopropyl(meth) ) acrylamide, diacetone acrylamide, Nn-butoxymethylacrylamide, N-isobutoxymethylacrylamide, N-methoxymethylacrylamide, N-methylolacrylamide, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, benzyl (meth)acrylate ) acrylate, neopentyl glycol (meth)acrylic acid benzoate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, γ- (meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-( Meta)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, γ-(meth)acryloxypropyldiethylmethoxysilane β-(meth) Acryloxyethyltrimethoxysilane, β-(meth)acryloxyethyltriethoxysilane, polyoxyethylene mono(meth)acrylate, polyoxypropylene mono(meth)acrylate, polyoxybutylene mono(meth)acrylate, etc. Examples include those modified with alkylene glycol. Among these, monofunctional polymerizable monomers with extended alkyl chains or alkylene glycol chains are preferable because odor is reduced due to increased molecular weight compared to before chain extension.

Among polyfunctional polymerizable monomers, specific examples of polyfunctional polymerizable monomers (bifunctional polymerizable monomers) having two radically polymerizable functional groups include 1,3-butylene glycol di(meth)acrylate, 1 , 4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8 -Octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 2-butyl-2 -Ethyl-1,3-propanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, diethylene glycol di( meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxy Neopentyl glycol di(meth)acrylate pivalate, PO (propylene oxide) modified neopentyl glycol di(meth)acrylate, cyclohexanedimethanol diacrylate, tricyclodecane dimethanol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate , dicyclopentanyl diacrylate, bisphenol A di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and the like.

Specific examples of polyfunctional polymerizable monomers having three or more functional groups exhibiting radical polymerizability (trifunctional or higher functional polyfunctional polymerizable monomers) include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri( meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, EO-modified diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, EO-modified dipentaerythritol hexa(meth)acrylate, glycerin triacrylate Examples include (meth)acrylate.

As used herein, the term (meth)acrylate means methacrylate or acrylate. For example, 2-hydroxyethyl (meth)acrylate is 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate. In addition, when a prefix indicating plurality is attached to a (meth)acrylate, such as di(meth)acrylate, tri(meth)acrylate, etc., each (meth)acrylate may be the same or different. good.

The polymerizable oligomer is preferably an acrylic oligomer. An acrylic oligomer is an oligomer having an acryloyl group or a methacryloyl group as a functional group exhibiting radical polymerizability.

The polymerizable oligomer is preferably a polyfunctional polymerizable oligomer, more preferably a polyfunctional acrylic oligomer. The number of functional groups of the polymerizable oligomer is preferably 2 to 6, and the molecular weight of the polymerizable oligomer is preferably 800 to 20,000. The molecular weight of the polymerizable oligomer is the weight average molecular weight in terms of polystyrene.

Specific examples of acrylic oligomers include polyurethane acrylic oligomers [acrylic oligomers with multiple urethane bonds (-NHCOO-)], polyester acrylic oligomers [acrylic oligomers with multiple ester bonds (-COO-)], polyamino acrylic oligomers [amino group (-NH ₂ )], polyepoxy acrylic oligomer [acrylic oligomer having multiple epoxy groups], silicone acrylic oligomer [acrylic oligomer having multiple siloxane bonds (-SiO-)], polybutadiene acrylic oligomer [butadiene unit] Acrylic oligomers having multiple .

Additionally, the following are known as acrylic oligomers.
Beam set 502H, beam set 505A-6, beam set 550B, beam set 575, beam set AQ-17 (manufactured by Arakawa Chemical Industries),
AH-600, UA-306H, UA-306T, UA-306I, UA-510H, UF-8001G (manufactured by Kyoeisha Chemical Co., Ltd.),
CN910, CN959, CN963, CN964, CN965NS, CN966NS, CN969NS, CN980NS, CN981NS, CN982, CN983NS, CN985, CN991NS, CN996NS, CN2920, CN2921, CN8881N S, CN8883NS, CN9001NS, CN9004, CN9005, CN9009, CN9011, CN9021NS, CN9023, CN9028, CN9030, CN9178NS, CN9290, CN9893NS, CN929, CN989NS, CN968NS, CN9006NS, CN9010NS, CN9025, CN9026, CN9039, CN9062, CN9110NS, CN902 9, CN8885NS, CN9013NS, CN973, CN978NS, CN992, CN9167, CN9782, CN9783, CN970, CN971, CN972, CN975NS, CN9165 (manufactured by Sartomer),
U-2PPA, U-6LPA, U-10HA, U-10PA, UA-1100H, U-15HA, UA-53H, UA-33H, U-200PA, UA-200PA, UA-160TM, UA-290TM, UA- 4200, UA-4400, UA-122P (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.),
New Frontier R-1235, R-1220, RST-201, RST-402, R-1301, R-1304, R-1214, R-1302XT, GX-8801A, R-1603, R-1150D (Daiichi Kogyo Seiyaku company),
EBECRYL204, EBECRYL205, EBECRYL210, EBECRYL215, EBECRYL220, EBECRYL230, EBECRYL244, EBECRYL245, EBECRYL264, EBECRYL265, EBECRYL270, EBECRYL280/15IB, EBECRYL284, EBECRYL285, EBECRYL294/25HD, EBECRYL1259, EBECRYL1290, KRM8200, EBECRYL4820, EBECRYL4858, EBECRYL5129, E BECRYL7100, EBECRYL8210, EBECRYL8254, EBECRYL8301R, EBECRYL8307, EBECRYL8402, EBECRYL8405, EBECRYL8411, EBECRYL8465, EBECRYL8800, EBECRYL8804, EBECRYL8807, EBECRYL9260, EBECRYL9270, EBECRYL7735, EBECRYL8296, EBECRYL8452, EBECRYL8904, EBECRYL8311, EBECRYL8701, EBECRYL8667 (manufactured by Daicel Allnex),
UV-1700B, UV-6300B, UV-7550B, UV-7600B, UV-7605B, UV-7610B, UV-7630B, UV-7640B, UV-7650B, UV-6630B, UV-7000B, UV-7510B, UV- 7461TE,
UV-2000B, UV-2750B, UV-3000B, UV-3200B, UV-3300B, UV-3310B, UV-3700B, UV6640B (manufactured by Nippon Gosei Kagaku Co., Ltd.),
Art Resin UN-333, UN-350, UN-1255, UN-2600, UN-2700, UN-5590, UN-6060PTM, UN-6200, UN-6202, UN-6300, UN-6301, UN-7600, UN-7700, UN-9000PEP, UN-9200A, UN-3320HA, UN-3320HC, UN-904, UN-906S (manufactured by Negami Kogyo Co., Ltd.),
Aronix M-6100, M-6250, M-6500, M-7100, M-7300K, M-8030, M-8060, M-8100, M-8530, M-8560, M-9050 (manufactured by Toagosei Co., Ltd.)

Specific examples of polymerizable compounds having hydroxyl groups include 2-hydroxyethyl (meth)acrylate, 2-hydroxykipropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6 - Hydroxyhexyl (meth)acrylate, polyoxyethylene mono(meth)acrylate, polyoxypropylene mono(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified hydroxyethyl acrylate, etc. Can be mentioned. In addition, the polymerizable compound having a hydroxyl group also includes a polymerizable compound that generates a hydroxyl group by thermal decomposition, such as N-methylolacrylamide. Further, as the polymerizable compound having a hydroxyl group, a synthesized one or a commercially available product may be used.

Specific examples of polymerizable compounds having silicon atoms include γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, β-(meth)acryloxyethyltrimethoxysilane, β -(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ -(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, γ-(meth)acryloxypropyldiethylmethoxysilane, and the like. Among these, examples of the polymerizable compound represented by structural formula (1) include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, and γ-methacryloxypropyldimethylmethoxysilane. It will be done.

Specific examples of polymerizable compounds having a heterocyclic skeleton include N-acryloylmorpholine, N-methacryloylmorpholine, γ-butyrolactone (meth)acrylate, N-vinylcaprolactam, N-acryloyloxyethylhexahydrophthalimide, N-methacryloyloxy Ethylhexahydrophthalimide, 1-acryloylpyrrolidin-2-one, 1-methacryloylpyrrolidin-2-one, 1-acryloylpiperidin-2-one, 1-methacryloylpiperidin-2-one, N-vinyl-2-pyrrolidone, N - Vinylimidazole, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, etc. It will be done. Among these, those containing nitrogen are preferred, and N-acryloylmorpholine is particularly preferred.

The photopolymerization initiator has the effect of starting the polymerization of the above-described polymerizable compound when irradiated with active energy rays. The amount of photopolymerization initiator in the ink is preferably 1 to 15% by weight, more preferably 1 to 12% by weight, and even more preferably 1 to 10% by weight. If the content of the polymerization initiator is less than 1% by mass, the film may be poorly cured, and if it exceeds 15% by mass, precipitates may be generated at low temperatures, making ink ejection unstable. Furthermore, in order to accelerate the initiation reaction of the polymerization initiator, it is also possible to use an auxiliary agent such as a photosensitizer.

Examples of photopolymerization initiators include benzophenone compounds, acetophenone compounds, thioxanthone compounds, and acylphosphine oxide compounds. It is preferable that the wavelengths overlap as much as possible. In particular, the photopolymerization initiator preferably contains an acylphosphine oxide initiator from the viewpoint of coloring during curing and curability when forming a thick film. The photopolymerization initiators may be used alone or in combination of two or more.

Regarding the photopolymerization initiator, it is preferable to use two or more types of initiators having different wavelength ranges. Thereby, the polymerizability of the compound can be improved. In addition, by combining those with two cleavage points and those with one cleavage point, the starting radical concentration can be increased, and the polymerization property and degree of curing can be further improved.

As the acylphosphine oxide initiator, it is preferable to use a monoacylphosphine oxide initiator and a bisacylphosphine oxide initiator in combination. Here, the mass ratio (C:D) of the monoacylphosphine oxide initiator (C) and the bisacylphosphine oxide initiator (D) is particularly preferably from 1:1 to 5:1.

Specific examples of photoinitiators include:
2,2-dimethoxy-1,2-diphenylethan-1-one,
1-hydroxy-cyclohexyl-phenyl-ketone,
2-hydroxy-2-methyl-1-phenylpropan-1-one,
Benzophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy- 2-Methylpropionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, phenylglyoxylic acid methyl ester, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane -1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholine-4 -yl-phenyl)-butan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone, 1-[9- Examples include ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetyloxime), 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, etc. .

Among these, from the viewpoint of ink curability, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl -phosphine oxide and 2,4-diethylthioxanthone are preferable, and from the viewpoint of coloration during curing and curability when forming a thick film, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, (2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide are preferred, with 2,4,6-trimethylbenzoyl-diphenyl - Particular preference is given to phosphine oxide.

〔構造式（２）中、ｎは１～３であり、Ｙはメトキシ基またはエトキシ基であり、ＲはＣ３より選ばれるアルキレン基であり、Ｘはグリシドキシ基またはエポキシシクロヘキシル基である。〕
なお、エポキシシクロヘキシル基とは、シクロヘキシル環を構成する２つの炭素原子と酸素原子でエポキシ基を形成しているシクロヘキシル基であり、エポキシ環とシクロヘキシル環の縮合環構造を有する基である。 The ink used in the present invention preferably contains a silane coupling agent, and more preferably contains a silane coupling agent represented by the following structural formula (2). By using a silane coupling agent as the silane compound, adhesion to the base material can be improved. Further, the silane compound represented by the structural formula (2) also has excellent pigment dispersibility and can improve the storage stability of the ink. The amount of silane coupling agent in the ink is preferably 1 to 10% by mass. The silane coupling agents may be used alone or in combination of two or more.

[In Structural Formula (2), n is 1 to 3, Y is a methoxy group or ethoxy group, R is an alkylene group selected from C3, and X is a glycidoxy group or an epoxycyclohexyl group. ]
The epoxycyclohexyl group is a cyclohexyl group in which two carbon atoms and an oxygen atom forming the cyclohexyl ring form an epoxy group, and is a group having a condensed ring structure of an epoxy ring and a cyclohexyl ring.

Specific examples of silane coupling agents include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, and γ-glycidoxysilane. Xypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyldimethylmethoxysilane Sidoxypropyl(ethyl)dimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexylethyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxy Epoxy group-containing silane coupling agents such as octylmethyldimethoxysilane and 8-glycidoxyoctylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane , N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane Isopropoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane Methoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-8-aminooctyltrimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethyl-butylidene) Examples include amino group-containing silane coupling agents such as propylamine.

Among these, as the silane coupling agent represented by structural formula (2), γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxy Examples include silane.

The ink used in the present invention preferably contains a silane compound. By using a silane compound, the adhesion to the substrate and the dispersibility of the pigment can be improved. In one embodiment of the present invention, the ink contains at least one of a silane compound and the aforementioned polymerizable compound having a hydroxyl group, and preferably contains both the silane compound and the polymerizable compound having a hydroxyl group. In the ink, the amount of the silane compound is preferably 0.5 to 10% by mass. The silane compounds may be used alone or in combination of two or more.

Examples of the silane compound include a polymerizable compound having a silicon atom, preferably a polymerizable compound represented by Structural Formula (1), a silane coupling agent, and preferably a silane coupling agent represented by Structural Formula (2). etc.

The ink used in the present invention preferably contains at least one of a polymerizable compound represented by Structural Formula (1) and a silane coupling agent represented by Structural Formula (2) as a silane compound; It is more preferable to include both the polymerizable compound represented by (1) and the silane coupling agent represented by Structural Formula (2). When the polymerizable compound represented by Structural Formula (1) and the silane coupling agent represented by Structural Formula (2) are used together, the polymerizable compound (E) represented by Structural Formula (1) and the Structural Formula ( The mass ratio (E:F) to the silane coupling agent (F) represented by 2) is particularly preferably from 1:2 to 2:1.

The ink used in the present invention may contain coloring materials such as dyes and pigments, but in that case, from the viewpoint of weather resistance, it is preferable to contain pigments, particularly inorganic pigments. The content of the coloring material is, for example, 1 to 20% by mass in the ink. The coloring materials may be used alone or in combination of two or more. Here, for the cyan ink, magenta ink, and yellow ink, it is preferable to select the pigment type from the viewpoint of adjusting the hiding rate of the ink.

The ink used in the present invention may further contain a dispersant, if necessary, in order to disperse the pigment. The content of the dispersant is, for example, 0.1 to 5% by mass in the ink. Dispersants may be used alone or in combination of two or more.

The dispersant preferably contains a dispersant having a base value of 30 to 70 mgKOH/g and/or an acid value of 10 to 150 mgKOH/g. By using a dispersant having such a base value and/or acid value, the dispersion stability of the pigment can be improved.

In this specification, "base value" is also referred to as "amine value", and is equivalent to milligrams of potassium hydroxide equivalent to hydrochloric acid or perchloric acid required to neutralize the basic component contained in 1 g of sample. number (unit: mgKOH/g), and can be measured by the method specified in JIS K2501:2003. In addition, "acid value" refers to the number of milligrams of potassium hydroxide (unit: mgKOH/g) required to neutralize the acidic components present in 1 g of sample, and is defined in JIS K2501:2003. It can be measured by

Specific examples of pigment dispersants include:
ANTI-TERRA-U, ANTI-TERRA-U100,
ANTI-TERRA-204, ANTI-TERRA-205,
DISPERBYK-101, DISPERBYK-102,
DISPERBYK-103, DISPERBYK-106,
DISPERBYK-108, DISPERBYK-109,
DISPERBYK-110, DISPERBYK-111,
DISPERBYK-112, DISPERBYK-116,
DISPERBYK-130, DISPERBYK-140,
DISPERBYK-142, DISPERBYK-145,
DISPERBYK-161, DISPERBYK-162,
DISPERBYK-163, DISPERBYK-164,
DISPERBYK-166, DISPERBYK-167,
DISPERBYK-168, DISPERBYK-170,
DISPERBYK-171, DISPERBYK-174,
DISPERBYK-180, DISPERBYK-182,
DISPERBYK-183, DISPERBYK-184,
DISPERBYK-185, DISPERBYK-2000,
DISPERBYK-2001, DISPERBYK-2008,
DISPERBYK-2009, DISPERBYK-2020,
DISPERBYK-2025, DISPERBYK-2050,
DISPERBYK-2070, DISPERBYK-2096,
DISPERBYK-2013, DISPERBYK-2150,
DISPERBYK-2155, DISPERBYK-2163,
DISPERBYK-2164,
BYK-P104, BYK-P104S, BYK-P105,
BYK-9076, BYK-9077, BYK-220S, BYKJET-9150, BYKJET-9151 (manufactured by BYK-Chemie Japan),
Solsperse3000, Solsperse5000,
Solsperse9000, Solsperse11200,
Solsperse13240, Solsperse13650,
Solsperse13940, Solsperse16000,
Solsperse17000, Solsperse18000,
Solsperse20000, Solsperse21000,
Solsperse24000SC, Solsperse24000GR,
Solsperse26000, Solsperse27000,
Solsperse28000, Solsperse32000,
Solsperse32500, Solsperse32550,
Solsperse32600, Solsperse33000,
Solsperse34750, Solsperse35100,
Solsperse35200, Solsperse36000,
Solsperse36600, Solsperse37500,
Solsperse38500, Solsperse39000,
Solsperse41000, Solsperse54000,
Solsperse55000, Solsperse56000,
Solsperse71000, Solsperse76500,
Solsperse J180, Solsperse J200,
SolsperseX300 (manufactured by Lubrizol),
Disparon DA-7301, Disparon DA-325, Disparon DA-375, Disparon DA-234 (manufactured by Kusumoto Kasei Co., Ltd.),
Floren AF-1000, Floren DOPA-15B, Floren DOPA-15BHFS, Floren DOPA-17HF, Floren DOPA-22, Floren DOPA-33, Floren G-600, Floren G-700, Floren G-700AMP, Floren G-700DMEA, Floren G-820, Floren G-900, Floren GW-1500, Floren KDG-2400, Floren NC-500, Floren WK-13E, (manufactured by Kyoeisha Chemical Co., Ltd.),
TEGO Dispers610, TEGO Dispers610S,
TEGO Dispers630, TEGO Dispers650,
TEGO Dispers652, TEGO Dispers655,
TEGO Dispers662C, TEGO Dispers670,
TEGO Dispers685, TEGO Dispers700,
TEGO Dispers710, TEGO Dispers740W,
LIPOTIN A, LIPOTIN BL,
LIPOTIN DB, LIPOTIN SB (manufactured by Evonik Degussa),
PB821, PB822, PN411, PA111 (manufactured by Ajinomoto Fine Techno),
Texahole 963, Texahole 964, Texahole 987, Texahole P60, Texahole P61, Texahole P63, Texahole 3250, Texahole SF71, Texahole UV20, Texahole UV21 (manufactured by Cognis),
Examples include BorchiGenSN88 and BorchiGen0451 (both manufactured by Beaucious).

The ink used in the present invention may further contain a surface conditioner from the viewpoint of improving wettability. As used herein, the surface conditioning agent refers to a substance that has a hydrophilic site and a hydrophobic site in its molecular structure, and can adjust the surface tension of the ink composition by adding it.

Specific examples of surface conditioning agents include dialkyl sulfosuccinates, alkylnaphthalene sulfonates, anionic surface conditioning agents such as fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, Nonionic surface conditioning agents such as polyoxyethylene/polyoxypropylene block copolymers, cationic surface conditioning agents such as alkylamine salts and quaternary ammonium salts, acrylic surface conditioning agents, silicone surface conditioning agents, and fluorine-based surface conditioning agents. Examples include surface conditioning agents. Particularly preferred are silicone surface conditioners and acrylic surface conditioners, and commercially available products from Bikkemie, Evonik, Dow Corning Toray, etc. can be used. Furthermore, in the case of a silicone-based surface conditioner, it is preferable to use a polyether-modified silicone oil having an HLB of 7.6 to 12.

The amount of the surface conditioner can be appropriately selected depending on the purpose of use, but it is preferably 0.01 to 1% by mass in the ink, for example. The surface conditioning agents may be used alone or in combination of two or more.

Specific examples of surface conditioning agents include:
BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315N, BYK-320, BYK-322, BYK-323, BYK-325, BYK-326, BYK- 330, BYK-331, BYK-333, BYK-342, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-350, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-361N, BYK-370, BYK-375, BYK-377, BYK-378, BYK-381, BYK-392, BYK-394, BYK-399, BYK-3440, BYK-3441, BYK- 3455, BYK-3550, BYK-3560, BYK-3565, BYK-3760, BYK-DYNWET 800N, BYK-SILCLEAN 3700, BYK-SILCLEAN 3701, BYK-SILCLEAN 3720, BYK-UV3500 , BYK-UV3505, BYK-UV3510, BYK-UV3530, BYK-UV3535, BYK-UV3570, BYK-UV3575, BYK-UV3576 (manufactured by BYK Chemie Japan),
TEGO Flow 300, TEGO Flow 370, TEGO Flow 425, TEGO Flow ATF 2, TEGO Flow ZFS 460, TEGO Glide 100, TEGO Glide 110, TEGO Glide 13 0, TEGO Glide 406, TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 482, TEGO GlideA 115, TEGO GlideB 1484, TEGO GlideZ G 400 (manufactured by Evonik Japan),
501W ADDITIVE, FZ-2104, FZ-2110, FZ-2123, FZ-2164, FZ-2191, FZ-2203, FZ-2215, FZ-2222, FZ-5609, L-7001, L-7002, L-7 604 , OFX-0193, OFX-0309 FLUID, OFX-5211 FLUID, SF 8410 FLUID, SH3771, SH 3746 FLUID, SH 8400 FLUID, SH 8700 FLUID, Y-7006 (all manufactured by Toray Dow Corning) ,
KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-640, KF-642, KF-643, KF-644, KF-945, KF-6004, KF- 6011, KF-6012, KF-6015, KF-6017, KF-6020, KF-6204, X-22-2516, and X-22-4515 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The ink used in the present invention may also contain a UV absorber. Ultraviolet absorbers have the effect of absorbing ultraviolet rays and preventing deterioration caused by ultraviolet rays. Examples of the ultraviolet absorber include cyanoacrylate compounds, benzophenone compounds, benzoate compounds, benzotriazole compounds, hydroxyphenyltriazine compounds, benzylidenecamphor compounds, and inorganic fine particles.

Specific examples of ultraviolet absorbers include:
2,4-dihydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone,
2-hydroxy-4-methoxybenzophenone-5-sulfonic acid,
2-hydroxy-4-octoxybenzophenone,
2-hydroxy-4-dodecyloxybenzophenone-2-hydroxy-4-benzyloxybenzophenone,
bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane,
2,2'-dihydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone,
2,2',4,4'-tetrahydroxybenzophenone,
2-hydroxy-4-methoxy-2'-carboxybenzophenone,
2-(2'-hydroxy-5'-methylphenyl)benzotriazole 2-[2'-hydroxy-3',5'-bis(α,α-(dimethylbenzyl)phenyl]benzotriazole,
2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole,
2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole,
2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole,
2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole,
2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole,
2,2'-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazol-2-yl)phenol],
A condensate of methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate and polyethylene glycol,
2-(2-hydroxyphenyl)benzotriazole,
2-(2'-hydroxy-5'-methylphenyl)benzotriazole,
2,6-di-t-butylphenyl-3',5'-di-t-butyl-4'-hydroxybenzoate,
Examples include hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate.

In the ink, the amount of ultraviolet absorber is preferably in the range of 0.1 to 15% by weight, more preferably 0.5 to 10% by weight, even more preferably 1 to 5% by weight. If the amount of ultraviolet absorber is too large, the film may not be sufficiently cured. The ultraviolet absorber may be used alone or in combination of two or more types, but it is preferable that the ultraviolet absorber contains at least two types of ultraviolet absorbers. By using multiple types of ultraviolet absorbers with different structures, the effects of the ultraviolet absorbers can be further sustained.

The ink used in the present invention may also contain a radical scavenger. A radical scavenger can capture free radicals and the like and improve photostability. Further, substances that react with free radicals and have a function of preventing polymerization reactions (so-called polymerization inhibitors) are also included in radical scavengers.

Examples of the radical scavenger include hindered amine compounds, hydroquinone compounds, phenol compounds, phenothiazine compounds, nitroso compounds, N-oxyl compounds, and particularly preferred are hindered amine light stabilizers (HALS).

Specific examples of radical scavengers include bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1-{2-(3-(3,5-di-t-butyl-4- hydroxyphenyl)propionyloxy)ethyl}-2,2,6,6-tetramethylpiperidine, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro{4. 5} Hindered amine compounds such as decane-2,4-dione, phenol, o-, m- or p-cresol, 2-t-butyl-4-methylphenol, 6-t-butyl-2,4-dimethylphenol , 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4- Phenolic compounds such as t-butyl-2,6-dimethylphenol, hydroquinone, hydroquinone monomethyl ether, methylhydroquinone, 2,5-di-t-butylhydroquinone, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone , trimethylhydroquinone 4-methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, benzoquinone, t-butyl-p - Hydroquinone compounds such as benzoquinone, 2,5-diphenyl-p-benzoquinone, phenothiazine compounds such as phenothiazine, nitroso compounds such as N-nitroso-N-phenylhydroxylamine ammonium, N-nitroso-N-phenylhydroxylamine aluminum salt, etc. system compounds, 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-methoxy-2 , 2,6,6-tetramethyl-piperidine-N-oxyl and other N-oxyl compounds.

In the ink, the amount of the radical scavenger is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less. If the amount of radical scavenger is too large, it may cause poor curing. The lower limit of the content of the radical scavenger in the ink is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. The radical scavengers may be used alone or in combination of two or more.

The ink used in the present invention may also contain a resin. The resin has the role of forming a film on the substrate while capturing solid components such as pigments, and contributes to improving the adhesion of the ink to the substrate.

Specific examples of resins include polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, chlorinated rubber, chlorinated polyethylene resin, chlorinated polypropylene resin, chlorinated ethylene-vinyl acetate resin, acrylic resin, and polystyrene resin. , polyamide resin, polyurethane resin, polyolefin resin, silicone resin, fluororesin, epoxy resin, polyester resin, ketone resin, phenolic resin, polyvinyl alcohol, polyvinyl alcohol derivative (anion-modified polyvinyl alcohol, etc.), cellulose, cellulose derivative (hydroxymethyl cellulose, Hydroxyethyl cellulose, cellulose acetate, etc.), rosin resins, alkyd resins, alginic acid, alginic acid derivatives (alginic acid propylene glycol ester, etc.). Also included are modified products of these resins. For example, in the case of a resin having a hydroxyl group, modifications such as hydroxyalkyl etherification modification and carboxylic acid modification can be mentioned.

The amount of resin in the ink is preferably in the range of 25% by weight or less, particularly 10% by weight or less, more preferably 8% by weight or less. Too much resin may cause poor curing. The lower limit of the resin content in the ink is, for example, 1% by mass or more, preferably 3% by mass or more. One type of resin may be used alone, or two or more types may be used in combination.

The ink used in the present invention contains, as other ingredients, antioxidants, plasticizers, rust preventives, solvents, antibacterial agents, antiviral agents, viscosity modifiers, fillers, antifoaming agents, charge control agents, stress Additives such as a relaxing agent, a penetrating agent, a light guiding material, a glittering material, a magnetic material, and a fluorescent material may be included as necessary.

The ink used in the present invention can be prepared by mixing various components that are appropriately selected as necessary. Furthermore, in order to prevent head nozzles from clogging due to impurities, it is preferable to filter the ink using a filter.

The ink used in the present invention preferably has a viscosity of 5 to 25 mPa·s, more preferably 5 to 20 mPa·s, at 35°C to 55°C. Since the temperature at which the ink is ejected is preferably 35° C. to 55° C., good ejection stability can be obtained if the ink viscosity is within the range specified above. Ink viscosity can be measured using a cone-plate viscometer.

The ink used in the present invention preferably has a surface tension of 20 to 35 mN/m at 25°C, more preferably 23 to 33 mN/m. If the ink surface tension at 25° C. is within the range specified above, good ejection stability can be obtained. Ink surface tension can be measured by the plate method.

It is particularly preferable that printing using the ink set of the present invention be performed by an inkjet printing method. Various inkjet printers can be used for inkjet printing. Examples of inkjet printers include inkjet printers that eject ink using a charge control method or a piezo method. Furthermore, large-sized inkjet printers, specifically inkjet printers intended for printing on articles produced on industrial lines, can also be suitably used.

When the ink set of the present invention is an active energy ray curable ink set, the layer formed by printing is cured by irradiation with active energy rays such as ultraviolet rays. As a light source for active energy rays, a high-pressure mercury lamp, a metal halide lamp, an LED lamp, etc. can be used. Furthermore, the wavelength of the active energy rays irradiated to cure this layer preferably overlaps with the absorption wavelength of the photopolymerization initiator, and the main wavelength of the active energy rays is preferably 350 to 400 nm. The cumulative amount of active energy rays is preferably in the range of 100 to 2000 mJ/cm ² .

In printing using the ink set of the present invention, by appropriately selecting the ejection conditions and the subsequent curing conditions, surface finishing processing such as glossy or matte can be achieved. For example, if the ink spreads and then hardens after some time, it will become glossy, and if the ink droplets harden while remaining lens-shaped, it will become matte.

The substrate on which printing is performed using the ink set of the present invention is not particularly limited, and specific examples thereof include paper, coated paper, plastic materials, building boards, and the like. The shape of the base material includes, for example, a film shape, a sheet shape, a plate shape, and the like. Examples of the base material include epoxy resin, ABS resin, polycarbonate, polyvinyl chloride, polystyrene, acrylic resin, and especially plastics such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polypropylene (PP). Examples include metals such as iron, stainless steel, aluminum, copper, titanium, and their alloys, wood, cement, concrete, plaster, calcium silicate, calcium carbonate, marble, artificial marble, glass, ceramics, etc. Two types of these materials A combination of the above may also be used. The surface of the base material may be subjected to pretreatment such as degreasing treatment, chemical conversion treatment, polishing, etc., or coating with a sealer or primer. The surface of the base material may be smooth, uneven, or three-dimensional. Specific examples of base materials include plastic materials such as PVC sheets, tarpaulin, plastic cardboard (plastic cardboard), and acrylic boards; coated paper (specifically, resin coated paper), art paper, cast paper, slightly coated paper, Paper such as high-quality paper, synthetic paper, and inkjet paper; Wooden building materials made from wood such as veneer, plywood, particle board, and medium density fiberboard (MDF); Ceramic siding boards, flexible boards, calcium silicate boards, Inorganic building materials such as gypsum slag barlite boards, wood chip cement boards, pulp cement boards, precast concrete boards, lightweight aerated concrete (ALC) boards, and gypsum boards; metal building materials such as aluminum, iron, and stainless steel, tiles, glass boards, etc. It will be done.

A layer (for example, a coating film or a printed film) may be formed on a part or the entire surface of the base material. For example, a coating film formed from a paint, a printed film formed from an ink, a printed film formed from a powder toner, or the like may be formed on the base material. The layer formed on the base material includes resin, coloring materials such as dyes and pigments, ultraviolet absorbers, radical scavengers, antioxidants, plasticizers, rust preventives, fillers, charge control agents, light guide materials, It can include glitter materials, magnetic materials, phosphors, wax, and the like.

Paints and inks used to form layers on substrates include organic solvent-based paints and inks that use organic solvents as the main solvent, water-based paints and inks that use water as the main solvent, and light-based paints and inks that use polymerizable compounds. Examples include various paints and inks such as curable paints and inks and powder paints. Here, examples of components that can be used in the case of ink include the components that can be used in the ink used in the present invention described above.

The means for forming the layer on the base material is not particularly limited. For example, in the case of paint, various coating means such as air spray, airless spray, roll coater, flow coater, and electrostatic coating can be used. In the case of ink, various printing means such as gravure printing, offset printing, flexographic printing, screen printing, coater printing, and inkjet printing can be used. In the case of powder toner, an electrophotographic printing method (specifically, an image forming apparatus such as a copying machine or a laser printer) can usually be used.

Another layer (for example, a coating film or a printed film) may be formed on the layer formed by printing using the ink set of the present invention. For example, a coating film formed from paint, a printed film formed from ink, etc. may be formed. Other layers that can be placed on the layer formed by printing using the ink set of the present invention include resins, coloring materials such as dyes and pigments, ultraviolet absorbers, radical scavengers, antioxidants, plasticizers, and antiseptics. It can contain a rust agent, an anti-algae agent, an anti-mold agent, an anti-bacterial agent, an anti-viral agent, a filler, a charge control agent, a light guiding material, a bright material, a magnetic material, a phosphor, a wax and the like.

When forming another layer after printing using the ink set of the present invention, paints and inks for forming the other layer include organic solvent-based paints and inks that use an organic solvent as the main solvent; Examples include various paints and inks such as water-based paints and inks that use water, photocurable paints and inks that use polymerizable compounds, and powder paints. Here, examples of components that can be used in the case of ink include the components that can be used in the ink used in the present invention described above.

The means for forming another layer after printing using the ink set of the present invention is not particularly limited. For example, in the case of paint, various coating means such as air spray, airless spray, roll coater, flow coater, and electrostatic coating can be used. In the case of ink, various printing means such as gravure printing, offset printing, flexographic printing, screen printing, coater printing, and inkjet printing can be used.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the Examples below.

The pigments used in producing the inks used in Examples and Comparative Examples are as shown below.
・DAIPYROXIDE TM Blue #3490 (C.I. Pigment Blue 28, manufactured by Dainichiseika Industries Co., Ltd.)
・LIONOGENBLUE 7921 (C.I. Pigment Blue 15:4, manufactured by Toyocolor Co., Ltd.)
・DAIPYROXIDE Blue #9410 (C.I. Pigment Blue 28, manufactured by Dainichiseika Industries Co., Ltd.)
・DAIPYROXIDE TM RED 8270 (C.I. Pigment Red 101, manufactured by Dainichiseika Kogyo Co., Ltd.)
・FASTGEN SUPER MAGENTA RGT (C.I. Pigment Red 122, manufactured by DIC Corporation)
・BAYFERROX 130M (C.I. Pigment Red 101, manufactured by LANXESS)
・SICOTRANS YELLOW L1916 (C.I. Pigment Yellow 42, manufactured by DIC Corporation)
・Yellow pigment LEVA SCREEN YELLOW G01 (C.I. Pigment Yellow 150, manufactured by LANXESS)
・TAROX synthetic iron oxide HY-100 (C.I. Pigment Yellow 42, manufactured by Titan Kogyo Co., Ltd.)
・Lysopac Yellow 6616B (C.I. Pigment Yellow 184, manufactured by Ferro Inc.)
・TITONE R-11P (C.I. Pigment White 6, manufactured by Sakai Chemical Industry Co., Ltd.)

An inkjet ink was prepared by obtaining a mixture according to the formulation shown in Tables 1 to 3, kneading it in a bead mill to make it homogeneous, and filtering it using a filter.
Next, ink sets were prepared using the combinations shown in Tables 4 to 7.

The annotations in Tables 1 to 3 are as follows.
a) Pigment dispersant TEGO-Dispers 685 (manufactured by Evonic)

Further, regarding the compositions in the table, the numerical value of each component is expressed in parts by mass. The item “Number of ethylenically unsaturated double bonds (A) = 1, (B)≧2 (B)/(A)” indicates the amount (mass%) of the monofunctional polymerizable compound contained in the ink. The B/A value is shown where A is the amount (mass %) of the polyfunctional polymerizable compound contained in the ink and B is the amount (mass %) of the polyfunctional polymerizable compound contained in the ink. The item "average number of functional groups of polymerizable compound" indicates the average number of functional groups of the polymerizable compound contained in the ink. The item "Ink composition P.I.I. value" includes the P.I.I. value of the polymerizable compound contained in the ink. I. I. A weighted average of the values is shown.

The item "White area" of "L value" in the table shows the L ^* value of the ink dry film printed on the white area of the hiding rate test paper, and the item "Black area" shows the hiding rate. The L ^* value of the dried ink film printed on the black background portion of the test paper is shown. The item "hiding rate %" shows the hiding rate (%) of a 10 μm thick dry film determined from the L ^* value of the ink dry film printed on the white and black areas of the hiding rate test paper. The item "Hue angle ∠H°" indicates the hue angle (°) of a 10 μm thick dry film formed from the ink.

"Difference in hiding rate (maximum value)" in Tables 4 to 7 indicates the difference in hiding rate found by subtracting the maximum value and the minimum value among the hiding rates shown by each ink in the ink set. It will be done. If this difference in concealment rate (outermost value) is 25% or less, all of the relational expressions (1) to (3) are satisfied.

Below, a method for producing a printed matter for evaluation, a method for measuring a hiding rate and a hue angle, an evaluation method and evaluation criteria for color reproducibility of mixed colors, mixed color gradation, ink ejection property, visibility, and color development are explained.

<Method for producing printed matter for evaluation>
Using an inkjet printer equipped with an inkjet head (KM1024-LHB set) manufactured by Konica Minolta, Inc., fill each ink into the inkjet printer, and then print each of the white and black areas on concealment rate test paper (JIS standard product). A single-color solid image of each ink was printed on the paper. In addition, for color mixing, a monochrome solid image was adjusted using the CMY printing density ratio according to each evaluation, and the adjusted image was printed overlapping the white background part and the black background part on the hiding rate test paper.
After printing, the ink was cured using a metal halide lamp to obtain a dried ink film with a dry film thickness of 10 μm.
The dry film thickness of the above dried ink film was measured using a micrometer (MDC-25MJ, manufactured by Mitutoyo Co., Ltd.).

<Measurement method of concealment rate>
Using a spectrophotometer (SpectroEye, manufactured by X-Rite), the printed matter (ink dry film thickness 10 μm) produced by the above <Method for producing printed matter for evaluation> The L ^* value of the dried film was measured. The obtained values were applied to the following formula (7) to calculate the hiding rate (%) of each ink.
Concealment rate (%) = 100 x Lb / Lw...Formula (7)
The results are shown in Tables 1 to 3.

<How to measure hue angle ∠H°>
As described in the above <Method for producing printed matter for evaluation>, a single color solid image was printed on the white background part of the hiding rate test paper, and the dried ink films with a film thickness of 10 μm for each of the single color and mixed color were measured using a spectrophotometer (SpectroEye). , manufactured by X-Rite), the hue angle ∠H° of the ink dry film was measured. The results of the hue angle ∠H° for single colors are shown in Tables 1 to 3, and the results of the hue angle ∠H° for mixed colors are shown in Tables 4 to 7.

<Evaluation method of color reproducibility of mixed colors>
The theory of the hue angle calculated from the measured value of the hue angle of each mixed color print and the colorimetric value of each single color of CMY by producing mixed color prints with the printing density ratio (volume ratio) shown in "1" in Tables 4 to 7. The color reproducibility of the mixed color was evaluated from the difference (referred to as x). The theoretical value of the hue angle can be calculated from Equation (10) or Equation (11) using the a ^* _(CMY) and b ^* _(CMY) values obtained from Equation (8) and Equation (9).

a ^* _(CMY) value = a _C × C density ratio + a _M × M density ratio + a _Y × Y density ratio...Equation (8)
b ^* _(CMY) value = b _C × C density ratio + b _M × M density ratio + b _Y × Y density ratio...Equation (9)
In formula (8), the a ^* _(CMY) value is the theoretical value of a ^* of the mixed color printed matter calculated from the colorimetric values of each single color of CMY, and a C is the theoretical value of a * of the mixed color printed matter calculated from the colorimetric values of each single color of CMY, and a _C is the This is the a ^* value of the dry cyan ink film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) on a monochrome solid image prepared on the white background part of the hiding rate test paper, and a _M is the above evaluation. It is the a ^* value of the dry magenta ink film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) on a monochrome solid image prepared on the white background part of the hiding rate test paper in a _Y is the yellow ink dry film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) on a monochrome solid image produced on the white background part of the hiding rate test paper in the above <Method for producing printed matter for evaluation> The ^density ratios of C, M, and Y are the density ratios (volume %) of cyan ink, magenta ink, and yellow ink, respectively.
In formula (9), the b ^* _(CMY) value is the theoretical value of b ^* of the mixed color print calculated from the colorimetric values of each single color of CMY, and b _C is the This is the b ^* value of the dry cyan ink film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) on a monochrome solid image prepared on the white background part of the hiding rate test paper, and b _M is the above evaluation. It is the b ^* value of the dry magenta ink film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) for a monochrome solid image prepared on the white background part of the hiding rate test paper in b _Y is the yellow ink dry film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) on a monochrome solid image produced on the white background part of the hiding rate test paper in the above <Method for producing printed matter for evaluation> b ^* value, and the density ratios of C, M, and Y are the density ratios (volume %) of cyan ink, magenta ink, and yellow ink, respectively.

h=tan ^-1 (b ^* _(CMY) value/a ^* _(CMY) value) + 180° (a ^* _(CMY) value < 0)...Equation (10)
h=tan ^-1 (b ^* _(CMY) value/a ^* _(CMY) value)+360°(a ^* _(CMY) value>0)...Equation (11)
h = 90° (a ^* _(CMY) value = 0, b ^* _(CMY) value > 0), h = 270° (a ^* _(CMY) value = 0, b ^* _(CMY) value < 0)
If the a ^* _(CMY) value < 0, use equation (10) to find the theoretical value of the hue angle (°); if the a ^* _(CMY) value > 0, use equation (11) to find the hue angle. Find the theoretical value of the angle (°). If a ^* _(CMY) value = 0, the theoretical value of the hue angle (°) is 90 ° (b ^* _(CMY) value > 0) or the theoretical value of the hue angle (°) is 270 ° (b ^* (CMY) value > 0 _{). CMY)} value < 0).
In equations (10) and (11), h is the theoretical value (°) of the hue angle of a mixed color print calculated from the colorimetric values of each single color of CMY, and the a ^* _(CMY) value is calculated from equation (8). The a ^* _(CMY) value is obtained from Equation (9), and the b ^* _(CMY) value is the b ^* _(CMY) value obtained from Equation (9).

<Evaluation of color reproducibility of mixed colors>
Each mixed color printed matter was produced for each ink set shown in Tables 4 to 7 using the printing density ratio (volume ratio) of the three patterns shown in "1" in Tables 4 to 7, and the above <Method for evaluating color reproducibility of mixed colors> Tables 4 to 7 show x calculated for each mixed color print according to the above. Further, the color reproducibility of mixed colors was evaluated for each ink set by applying the above calculated x to the evaluation criteria below. The evaluation results of color reproducibility of mixed colors are shown in Tables 4 to 7.
If ◎, close to ideal color mixture reproduction is possible and the color reproduction range is wide. If it is ○, the reproducibility is not as good as ◎, but it is possible to reproduce colors that are sufficient for practical use. If it is Δ, mixed color expression is possible, but the influence of the specific color is large and the mixed color reproduction area is narrowed. If it is ×, the influence of the specific color is large and color mixture cannot be expressed.
(Evaluation criteria)
◎=x calculated for each mixed color printed matter all satisfies 0≦x≦10.
◯ = All x calculated for each mixed color printed matter satisfies x≦20, but at least a part of the range of x satisfies 10<x≦20.
Δ=All x calculated for each mixed-color printed matter satisfies x≦30, but at least a part of the range of x satisfies 20<x≦30.
×=x calculated for each mixed color printed matter partially or completely satisfies x>30.

<Evaluation method of mixed color gradation>
Mixed color prints were produced using the color combinations and print density ratios (volume ratios) shown in "2" and "3" in Tables 4 to 7, and the hue angle and L ^* value were measured for each. For each color combination, the maximum change in hue angle (y to be described later) and the difference between the L ^* value (z to be described later) were determined.

y is the hue angle of the ink dry film measured using a spectrophotometer (SpectroEye, manufactured by X-Rite) for the mixed color print produced on the white background part of the hiding rate test paper in the above <Method for producing printed matter for evaluation> It can be calculated from equation (12) using the minimum value (∠H° _MIN ) and maximum value (∠H° _MAX ).
y = ∠H° _MAX - ∠H° _MIN ...Formula (12)

z is the L ^* value (L ₀ ) of the white background part of the hiding rate test paper, the L ^* value (L _25:25 ) of the print density ratio pattern 25:25 prepared on the white background part of the hiding rate test paper, and the print density ratio pattern. After determining the L ^* value (L _50:50 ) of 50:50, it can be calculated using equation (13). The above L ^* value is the spectrophotometric value of the mixed color print of each print density ratio pattern produced on the white background part of the hiding rate test paper in the above <Method for producing printed matter for evaluation> and the L ^* value of each of the white background part of the hiding rate test paper. It is measured and calculated using a spectrometer (SpectroEye, manufactured by X-Rite).
z = | (L _25:25 - L ₀ ) - (L _50:50 - L _25:25 ) |
...Formula (13)

<Evaluation of mixed color gradation 1>
Mixed color prints were produced for each color combination shown in "2" in Tables 4 to 7 using each of the ink sets shown in Tables 4 to 7, and y calculated according to the <method for evaluating mixed color gradation> above was calculated from Tables 4 to 7. 7. Furthermore, gradation was evaluated by applying the above-calculated y to the following evaluation criteria. The results are shown in Tables 4-7.
If it is ○, it is an ink combination that can express dark to light colors while exhibiting a nearly constant hue angle. If it is Δ, the hue angle shows discrete values and does not have smooth color mixing gradation. If it is ×, the graininess becomes more noticeable as the print density ratio decreases, making it difficult to reproduce not only the gradation but also mixed colors.
(Evaluation criteria)
○=y calculated for each mixed color printed matter all satisfies 0≦y≦15.
Δ=The y calculated for each mixed color printed matter all satisfy y≦25, but at least a part of y satisfies 15<y≦25.
×=y calculated for each mixed color printed matter partially or completely satisfies y>25.

<Evaluation of mixed color gradation 2>
Mixed color prints were produced for each color combination shown in "3" in Tables 4 to 7 using each of the ink sets shown in Tables 4 to 7, and z calculated according to the <method for evaluating mixed color gradation> above was calculated as shown in Tables 4 to 7. 7. Furthermore, gradation was evaluated by applying the above calculated z to the following evaluation criteria. The results are shown in Tables 4-7.
If it is ○, the base is hidden according to the print density ratio, so it is a combination of inks that can express dark to light colors. If it is Δ, it indicates that there is a sudden change in concealment and does not have smooth color mixing gradation. If it is ×, the graininess becomes more noticeable as the print density ratio decreases, making it difficult to reproduce not only the gradation but also mixed colors.
(Evaluation criteria)
○=Z calculated for each mixed color printed matter all satisfies 0≦z≦15.
Δ=The z calculated for each mixed color printed matter all satisfy z≦25, but at least a part of z satisfies 15<z≦25.
x=z calculated for each mixed color printed matter partially or completely satisfies z>25.

<Evaluation of ink ejectability>
The ejection suitability of each CMY ink was evaluated for each ink set listed in Tables 4 to 7 using a droplet flight observation device equipped with an inkjet head KM1024-LHB manufactured by Konica Minolta, Inc. The results are shown in Tables 4-7. The evaluation criteria are as follows, and if it is ◎, printing can be performed stably without any problems. If ○, maintenance such as preliminary ejection is required when restarting printing after the machine is stopped, but it is at a level that is possible in actual operation. If it is △, poor printing appearance occurs or maintenance frequency increases, which is undesirable in terms of productivity in actual operation. If it is ×, it is difficult to use it in actual operation.
(Evaluation criteria)
◎=The flying condition of ink droplets is good for all inks in the ink set, and no non-ejecting nozzles occur when printing is restarted 10 minutes after the machine is stopped.
○=The flying condition of ink droplets is good for all the inks in the ink set, but non-discharging nozzles occur with some inks when printing is restarted 10 minutes after the machine is stopped. However, by performing 100 preliminary discharges, the non-discharge nozzles will be resolved.
△= The flying state of ink droplets is unstable for some of the inks in the ink set, or a non-ejecting nozzle occurs when printing is resumed after 10 minutes of machine stoppage, and nozzles fail even after 100 preliminary ejections. The discharge nozzle does not clear up.
× = The flying state of ink droplets is unstable for all inks in the ink set, and non-discharging nozzles occur when printing is resumed after 10 minutes of machine shutdown. Even after 100 preliminary discharges, non-discharging nozzles remain. It doesn't resolve.

<Evaluation of visibility and color development>
Using an inkjet printer equipped with an inkjet head (KM1024-LHB set) manufactured by Konica Minolta, Inc., each ink was filled into the inkjet printer, and then 5. Print the image identification number N3 fruit basket (basket) described in the data expression method and definition on each of the white and black areas of concealment rate test paper (JIS standard product), and harden it using a metal halide lamp. After that, the visibility and color development of the printed matter were visually evaluated. The results are shown in Tables 4-7.
If it is ◎, the texture is expressed down to the details of the fruit basket (basket) on both the white and black areas of the concealment rate test paper, and the colors are vivid. If it is ○, it is not as good as ◎, but it has visibility and vividness that allows it to be recognized as a fruit basket on both the white and black parts of the concealment rate test paper. If it is △, the images printed on the white and black parts of the concealment rate test paper look different, and especially on the black parts, the boundaries in the image are vague and the colors look dull. . If it is ×, the colors of the images printed on the white background part and the black background part of the hiding rate test paper are completely different, and the image cannot be recognized as a fruit basket (basket) on the black background part.
(Evaluation criteria)
◎ = There is no difference in color development and visibility between the white background part and the black text part.
○=Color development is poorer on a black background than on a white background, but the image can be recognized sufficiently.
△=Compared to the white background area, the image border line is difficult to discern on the black background area, and the image becomes dull in color.
×=The image cannot be reproduced on the black background part.

<Overall evaluation of examples>
Examples 1 to 3, 5, and 6 are ink sets that satisfy mixed color reproducibility, mixed color gradation, ink ejectability, visibility, and color development in a well-balanced manner. Example 4 is particularly excellent in color reproducibility of mixed colors, but has some difficulty in ink ejection performance.
Examples 7 to 12 are ink sets in which the difference in concealment rate is within the range of 55 ± 25%, and in addition to being particularly excellent in mixed color reproducibility, visibility, and color development, the gradation and ink ejection properties are also good. It is.

Claims (5)

Regarding the hiding rate (%) of a dry film with a thickness of 10 μm formed from each ink in an ink set containing at least cyan ink, magenta ink, and yellow ink, the hiding rate in the case of cyan ink is Ch, and the hiding rate in the case of magenta ink is Ch. Ch, Mh and Yh are all 10% or more, and satisfy all of the following relational expressions (1) to (3) An ink set characterized by:
Formula (1) 0 ≦ |Ch−Mh| ≦ 25%
Formula (2) 0 ≦ |Mh-Yh| ≦ 25%
Formula (3) 0 ≦ |Yh-Ch| ≦ 25% The hue angle ∠H° of a 10 μm thick dry film formed from cyan ink is in the range of 230° to 270°, and the hue angle ∠H° of a 10 μm thick dry film formed from magenta ink is 26°. The hue angle ∠H° of a 10 μm thick dry film formed from the yellow ink is in the range 75° to 110°, and The ink set according to claim 1, characterized in that the hue angle ∠H° of a dry film with a thickness of 10 μm is obtained on a white base. The hue angle ∠H° of a 10 μm thick dry film formed by mixing cyan ink and magenta ink at a volume ratio of 1:1 is in the range of -20° to 25°, and the hue angle ∠H° is in the range of -20° to 25°. The hue angle ∠H° of a 10 μm thick dry film formed by mixing colors at a volume ratio of :1 is in the range of 43° to 74°, and is formed by mixing colors from yellow ink and cyan ink at a volume ratio of 1:1. The hue angle ∠H° of the dry film with a thickness of 10 μm is in the range of 111° to 160°, and the cyan ink and magenta ink are mixed at a volume ratio of 1:1, and the magenta ink and yellow ink are mixed at a volume ratio of 1:1. The hue angle ∠H° of a dry film with a thickness of 10 μm formed by mixing colors in a volume ratio of 1:1 and yellow ink and cyan ink in a volume ratio of 1:1 is obtained on a white base, The ink set according to claim 1 or 2. The ink set according to any one of claims 1 to 3, wherein the Ch, Mh, and Yh are all within a range of 55±25%. The ink set according to any one of claims 1 to 4, characterized in that one or more of the cyan ink, magenta ink, and yellow ink contains a white pigment.