JP4655507B2 - Ink set and recording method, recording system and recorded matter using the same - Google Patents

Description

  The present invention relates to an ink set having at least a specific yellow ink and excellent in color reproducibility of a recorded image.

  Conventionally, the yellow ink provided in the ink set for color inkjet recording has a relatively high brightness in order to prevent a state in which the dots can be visually recognized by the naked eye when the image is expressed by dots. It is used. For example, according to the Lab color system defined by the CIE (Commission Internationale d'Eclairage), the high brightness yellow ink is “high L * and a * is near zero and high b *”. .

  When yellow ink with “high L * and a * is near zero and high b *” is used, the graininess is improved, but the L * value (brightness) is about 60 or less in the middle lightness to low lightness region. There is a problem that the reproducibility of a color having a high b * value is insufficient.

  In order to solve such a problem, an ink set that further includes a low-lightness yellow ink called dark yellow in addition to the high-lightness yellow ink has been proposed (see, for example, Patent Document 1).

  In addition, a method of achieving a high b * value at medium to low brightness by increasing the pigment solid content contained in the yellow ink is also used (see, for example, Patent Document 2).

On the other hand, C.I. I. Pigment yellow 128 and C.I. I. A method for obtaining a wide range of color reproducibility in the yellow region by using a yellow ink composition containing two types of yellow pigments of CI Pigment Yellow 110 is also disclosed (for example, see Patent Document 3).
JP 2002-105368 A JP 2003-313480 A JP 2001-081369 A

  However, in the method using dark yellow, the number of ink colors increases, so that color creation becomes complicated and the cost tends to increase. In the method in which the pigment solid content is increased, the gloss may be deteriorated.

  C. I. Pigment yellow 128 and C.I. I. In the method of blending CI Pigment Yellow 110, it is possible to obtain a wider range of color reproducibility than ink containing one type of pigment, but the color reproducibility of the dark part in the yellow region is not sufficient. In addition, since the mixture of pigment types having different hue angles, the saturation of the secondary color tends to be lowered. I. Since Pigment Yellow 110 is reddish, green has low saturation.

  Therefore, the present invention includes a yellow ink that is excellent not only in a high lightness (high L *) region but also in a low lightness yellow region, that is, “low L * and a * is near zero and high b *”. An object is to provide an ink set.

  As a result of intensive research, the present inventors have found that an ink set including a yellow ink containing a metal complex pigment is not only in a high brightness region but also “low L * and a * is near zero and high b *”. It was found that the color reproducibility was excellent in this area.

  The present invention has been made on the basis of the above findings. When the Z value in the XYZ display system defined by the CIE is 23 calculated from the ultraviolet-visible transmission spectrum of a diluted aqueous solution having a weight of 10,000 times or less, the Y value The present invention provides an ink set including a yellow ink having an average of 86 or more.

  Since the ink set according to the present invention has the above-described configuration, even if there is only one type of yellow ink, low-lightness yellow can be expressed with good reproducibility. In addition, the color reproducibility of both the red region and the green region is excellent.

  The present invention also provides a recording method for forming an image using an ink set. According to this recording method, it is possible to obtain a high-quality recorded image with excellent color reproducibility between the low-lightness yellow region and the red region and the green region.

  The present invention also provides a recording system for forming an image using the ink set. According to this recording system, it is possible to obtain a high-quality recorded image that is excellent in color reproducibility between the low-lightness yellow region and the red region and the green region and in which the graininess due to dot expression is not conspicuous.

  Furthermore, the present invention provides a recorded matter in which an image is formed using the ink set. This recorded matter is excellent in color reproducibility between the low brightness yellow area and the red area and the green area, and has a high quality with no noticeable graininess due to dot expression.

[Ink set]
Hereinafter, the ink set of the present invention will be described based on preferred embodiments thereof.

  As described above, the ink set according to the present invention is calculated from the UV-visible transmission spectrum of a diluted aqueous solution having a weight of 10,000 times or less (for example, under the condition of a viewing angle of 2 degrees with a D65 light source) and is defined by XYZ. When the Z value in the display system is 23, yellow ink having a Y value of 86 or more is included. Here, when the yellow ink is diluted at a magnification of 10,000 times or less, when the Z value in the XYZ display system defined by the CIE is 23, the Y value may be 86 or more. The yellow ink contained in the ink set according to the present invention is preferably in a range of about 100 times to about 3000 times dilution, more preferably in a range of about 500 times to about 2500 times dilution. Even in the range where the weight is about 1000 times or more and about 2000 times or less, when the Z value in the XYZ display system defined by the CIE is 23, the Y value is 86 or more.

  The ink set according to the present invention preferably includes yellow ink having a Y value of 87 or more when the Z value in the XYZ display system defined by the CIE is 23, and a Y ink having a Y value of 88 or more. It is further preferable that it contains.

  Here, the Z value is measured using, for example, U3300 (manufactured by Hitachi, Ltd.) under the conditions of a scan speed of 600 nm / min, a measurement wavelength range of 380 to 800 nm, and a slit width of 2.0 nm, a D65 light source, and a viewing angle. It can be obtained by calculating at twice (hereinafter, the same applies to other inks).

  The yellow ink provided in the ink set of the present invention preferably contains a metal complex pigment. Examples of such metal complex pigments include C.I. I. Pigment Yellow 129 (hereinafter sometimes abbreviated as “PY129”), C.I. I. Pigment Yellow 117 and the like can be mentioned, and PY129 is particularly preferable. Examples of the metal complex pigment include complex pigments containing copper, aluminum, zinc and the like, and copper complex is particularly preferable. The yellow ink containing the metal complex pigment can express the low brightness yellow region with higher reproducibility, and the ink set including this yellow ink also has better color reproducibility in the red region and the green region. Further, by using an ink containing a metal complex pigment, an ink set excellent in image fastness of recorded matter can be obtained.

  The yellow ink provided in the ink set of the present invention preferably contains the metal complex pigment in an amount of 10% to 90% by weight, more preferably 10% to 60% by weight of the total pigment solid content. . In the case of dark ink (for example, ink in which the total pigment solid content is about 4% by weight with respect to the ink weight), the metal complex pigment is about 10% to 30% by weight of the total pigment solid content, light color In the case of an ink (for example, an ink containing about 2% by weight of the total pigment solid content with respect to the ink weight), the metal complex pigment should contain about 30% to 60% of the total pigment solid content. Is preferred. In particular, an ink in which PY129 is used as the metal complex pigment and PY74 is used as the other yellow pigment and mixed in the above weight ratio is particularly suitable, and a color balance with a better balance in a wide yellow region from high to low brightness is obtained. be able to.

  The yellow ink included in the ink set of the present invention is selected from the group consisting of PY74, 93, 109, 110, 128, 138, 150, 151, 154, 155, 180, 185 in addition to the metal complex pigment. It is preferable to include at least one other yellow pigment. By mixing these yellow pigments having relatively high lightness, the color reproducibility in the high lightness region of yellow can be improved, and the effect of making the graininess inconspicuous can be obtained. Accordingly, it is possible to obtain an ink set in which the reproducibility of the low brightness and the high brightness in the yellow region is improved in a balanced manner without using a plurality of types of yellow ink. In order to obtain such an effect, PY74 is particularly preferable among the above-mentioned yellow pigments.

  The ink set according to the present invention preferably includes a magenta ink (M) and a cyan ink (C) in addition to the yellow ink (Y). Such YMC ink is excellent in color reproducibility widely from high lightness to low lightness in the yellow region. Furthermore, the color reproducibility in the red area and the green area is excellent, and the graininess at the time of dot expression does not matter.

  In addition to the YMC ink, the ink set according to the present invention can also include black ink such as photo black ink (PK) and / or matte black ink (MK). As a result, in addition to the above effects, an ink set with better black color development can be obtained. Also, since black is generally used better than other colors, it is preferable to prepare it separately from the YMC ink because only the black ink can be replenished.

  The colorant (colorant) of each ink provided in the ink set according to the present invention is preferably a pigment from the viewpoint of excellent image fastness of recorded matter. As the pigment, inorganic pigments and organic pigments can be used, and each can be used alone or in combination. As the inorganic pigment, for example, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used in addition to titanium oxide and iron oxide. Examples of the organic pigment include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye-type chelates, acidic dye-type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used.

  For each color ink other than the yellow ink, specifically, various pigments are used as described below.

  The pigment of magenta ink is not particularly limited as long as the magenta ink has a predetermined Z value and a predetermined L * value. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 168, 184, 202, 207, 209; I. 1 type or 2 or more types, such as pigment violet 19, etc. are mentioned. Among them, C.I. I. Pigment violet 19 or C.I. I. Pigment Red 122 is preferable because a high-quality image with further reduced metamerism and graininess can be obtained.

  The pigment of the cyan ink is not particularly limited as long as the cyan ink has a predetermined L * value. I. Pigment Blue 1, 2, 3, 15: 3, 15: 4, 15:34, 16, 22, 60; I. 1 type or 2 types or more, such as bat blue 4,60, are mentioned. Among them, C.I. I. Pigment Blue 15: 3 is preferable.

  In the ink set of the present invention, in particular, the magenta ink pigment is C.I. I. Pigment violet 19 or C.I. I. Pigment Red 122, the yellow ink pigments are PY129 and PY74, and the cyan ink pigments are C.I. I. In the case of a combination of YMC inks having CI Pigment Blue 15: 3, a recorded image showing a smoother visible absorption spectrum can be obtained when printing is performed.

  The black ink used in the present invention includes, as a coloring material, for example, carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, and inorganic oxides such as iron oxide pigments. Pigments: those containing organic pigments such as aniline black (CI Pigment Black 1). Among these pigments, it is particularly preferable to use carbon black, and examples of preferable carbon black include No. 2300, No. 900, MCF 88, No. 33, No. 40, No. 52, MA7, manufactured by Mitsubishi Chemical. MA8, MA100, No.2200B etc., Colombia Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700 etc., Cabot Regal 400R, Regal 400R, Regal 1660R, Mogul 1, Monarch 700, Monarch 800, Monarch 880 , Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 etc., Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color, etc. Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 and so on. The pigment content in the black ink is preferably 0.1 to 10.0% by weight, more preferably 1.0 to 8.0% by weight.

  Furthermore, the ink set of the present invention may include one or more other inks such as a transparent ink and a white ink in addition to the above ink.

  Each of the inks included in the ink set of the present invention preferably uses a pigment as a coloring material and contains a dispersant for dispersing the pigment. As the dispersant, those similar to those in this type of pigment ink can be used without particular limitation, and examples thereof include a cationic dispersant, an anionic dispersant, a nonionic dispersant, and a surfactant. Examples of anionic dispersants include polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid. Copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-α-methylstyrene-acrylic acid copolymer Styrene-α-methylstyrene-acrylic acid-alkyl acrylate copolymer, styrene-maleic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene Copolymer, vinyl acetate-maleic ester Examples include copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and the like. Examples of anionic surfactants include sodium dodecylbenzenesulfonate, sodium laurate, ammonium salt of polyoxyethylene alkyl ether sulfate, and examples of nonionic surfactants include polyoxyethylene alkyl. Examples include ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, and the like, and one or more of these are used. In particular, it is preferable to use a styrene- (meth) acrylic acid copolymer from the viewpoint of enhancing the dispersion stability of the pigment.

  The dispersant is usually contained in each ink in an amount of 140% by weight or less in terms of solid content based on the weight of the pigment.

  In particular, in magenta ink, yellow ink, and cyan ink, the dispersant is preferably 10 to 140% by weight, more preferably 10 to 100% by weight, and still more preferably in terms of solid content based on the weight of the pigment. Is contained in an amount of 10 to 40% by weight.

  Further, the content of the dispersant with respect to each ink amount is preferably 0.1 to 10% by weight, more preferably 0.3 to 3% by weight in terms of solid content.

  In addition, each ink provided in the ink set of the present invention contains a high-boiling organic solvent from the viewpoint of preventing the ink from drying and clogging at the head of the inkjet printer when used for inkjet recording. preferable. Examples of the high boiling point organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, and trimethylol. Polyhydric alcohols such as ethane and trimethylolpropane; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tri Multivalent such as ethylene glycol monobutyl ether Alkyl ethers of alcohol; urea, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, organic alkalis such as triethanolamine, saccharides such as sugar alcohol, etc. These 1 type (s) or 2 or more types are used. In particular, it is preferable to add an organic alkali such as triethanolamine together with glycerin in order to improve the prevention of clogging, stabilize the dispersibility of the coloring material, and improve the gloss of the recorded image.

  The high-boiling organic solvent is preferably contained in each ink in an amount of 0.1 to 30% by weight, more preferably 0.5 to 25% by weight.

  Of these high-boiling organic solvents, triethanolamine also has a function as an ink pH adjuster and dispersion stabilizer. The ink is preferably used in the range of 0.1 to 10% by weight.

  Moreover, each ink with which the ink set of the present invention is provided can contain a penetration enhancer from the viewpoint of increasing the wettability to the recording medium and increasing the permeability of the ink. Examples of the penetration enhancer include alcohols such as methanol, ethanol, iso-propyl alcohol; ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol mono Examples include lower alkyl ethers of polyhydric alcohols such as butyl ether; diols such as 1,2-pentanediol and 1,2-hexanediol, and one or more of these are used. In particular, it is preferable to use diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, 1,2-hexanediol, or two or more thereof.

  The penetration enhancer is preferably contained in the ink in an amount of 1 to 20% by weight, more preferably 1 to 10% by weight.

  Further, each of the inks included in the ink set of the present invention is an anionic surfactant and a nonionic surfactant from the viewpoint of increasing the wettability to the recording medium and increasing the permeability of the ink, similarly to the penetration accelerator. Various surfactants such as a cationic surfactant and an amphoteric surfactant can also be used, and it is particularly preferable to use an acetylene glycol compound or a silicone compound. As the acetylene glycol-based compound, commercially available compounds can be used. For example, Olfin Y, Surfynol 82, 440, 465, 485 (all trade names, manufactured by Air Products and Chemicals), Orphine STG, Olphine E1010 (both are trade names, manufactured by Nissin Chemical Co., Ltd.) and the like are used, and one or more of these are used. In particular, it is preferable to use Olphine E1010 and Surfynol 465. Moreover, as this silicone type compound, polysiloxane type compounds, such as BYK347, 348 or BYKUV3510 (made by Big Chemie Japan), can be used as a commercial item. The acetylene glycol compound and / or the silicone compound is preferably 0.01 to 5% by weight, more preferably 0.1 to 1.0% by weight, and particularly preferably 0.1 to 0. 5% by weight is contained.

  Moreover, each ink with which the ink set of this invention is provided can contain the low boiling-point organic solvent from a viewpoint of shortening the drying time of an ink. Examples of the low boiling point organic solvent include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, sec-butanol, tert-butanol, iso-butanol, n-pentanol and the like. These 1 type (s) or 2 or more types are used. In particular, monohydric alcohol is preferable.

  Each ink provided in the ink set of the present invention contains components such as the pigment, dispersant, high boiling point organic solvent, penetration enhancer, acetylene glycol-based compound and / or silicone-based compound described above, and usually contains water as a balance. It contains. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria is prevented over a long period of time.

  Each ink provided in the ink set of the present invention further includes a fixing agent such as a water-soluble rosin, an antifungal agent or preservative such as sodium benzoate, an antioxidant or an ultraviolet absorber such as an allophanate, if necessary. Additives such as chelating agents, oxygen absorbers, and pH adjusting agents can be contained, and one or more of these can be used.

  Each ink included in the ink set of the present invention can be prepared in the same manner as the conventional pigment ink using a conventionally known apparatus, for example, a ball mill, a sand mill, an attritor, a basket mill, a roll mill or the like. In the preparation, it is preferable to remove coarse particles using a membrane filter, a mesh filter or the like.

  The ink set of the present invention is not particularly limited in its application, but is an inkjet which is a recording method in which ink droplets are ejected from nozzles and adhered to a recording medium to form images such as characters and figures. It is preferably used in a recording method, and particularly preferably used in an on-demand ink jet recording method. As an on-demand type ink jet recording method, for example, a piezoelectric element recording method that performs recording using a piezoelectric element disposed in a printer head, or a thermal energy generated by a heater of a heating resistance element disposed in the printer head is used. And a thermal jet recording method for recording, and can be suitably used for any ink jet recording method.

  The ink set of the present invention is highly reliable as an ink set for ink jet recording when used in the ink jet recording method as described above. In particular, each ink in the ink set is used as a nozzle of an ink jet printer. By setting the pigment concentration to such a level that does not cause clogging of the ink, the ink set for ink jet recording has higher reliability even though the color reproducibility is wide.

  The ink set of the present invention can be applied as a recording medium for forming an image without limitation to a recording medium usually used in an ink jet recording method or the like. It is preferably applied to an exposed recording medium). In particular, if the ink set of the present invention is applied to a medium having a coating layer, it is possible to significantly suppress the noticeability of graininess due to dot expression when an image is formed.

  In the present specification, the “media having a coating layer” means all of the surfaces on which an image is formed (recorded surface) using the ink set described above and covered with at least the coating layer. As the media having this coating layer, those having an 85 degree gloss of 120 or less are usually used. Here, the 85 degree glossiness is measured by using “PG1M” manufactured by Nippon Denshoku Industries Co., Ltd. In the measurement, the measuring apparatus is adjusted in advance so that the standard gloss plate 85 degree glossiness is 100.

  As media having a coating layer, specular tone media having a glossiness of 85 to 70 to 120, for example, when a fluorescent lamp is applied from a distance of 1 m or more, the contour of the fluorescent lamp can be visually confirmed. Examples of such media include a resin coating layer, and a typical example thereof is “PGPP (Premium Glossy Photo Paper)” manufactured by Seiko Epson Corporation having an 85 degree gloss of 81.

  Other examples of media having a coating layer include semi-glossy media having an 85 ° glossiness of 10 to 70, and matte media having an 85 ° glossiness of 10 or less.

  In addition, the ink set of the present invention can extremely suppress graininess due to dot expression even when recording at a low resolution on a relatively small size medium (preferably a medium having a coating layer) such as an L plate. For this reason, the ink set of the present invention is particularly useful for a medium having a relatively small size such as an L plate.

〔Recording method〕
Next, the recording method of the present invention will be described.

  The present invention provides a recording method for forming an image using the above-described ink set, that is, a Z value in an XYZ display system defined by CIE, which is calculated from an ultraviolet-visible transmission spectrum of a diluted aqueous solution having a weight of about 10,000 times or less. 23, a method of forming an image using an ink set containing yellow ink (Y) having a Y value of 87 or more, and a recording method using the ink set of the above-described embodiment is particularly suitable. The recording method of the present invention is carried out in the same manner as a normal ink jet recording method except that the ink set is used.

  As a recording method of the present invention, in particular, when one color (single color) is formed on a recording medium by ejecting droplets of a plurality of colors of ink, an image is formed with ink corresponding to the color. In the case of forming a mixed color portion of a secondary color or higher (a color that cannot be formed by each ink alone), an ink jet recording method that forms the mixed color portion with at least two of the inks included in the ink set is preferably used. It is to provide.

  According to the ink jet recording method of the present invention, it is possible to obtain an image with high brightness and low brightness in the yellow region and further improved color reproducibility, and further, an image having excellent color reproducibility in the red region and the green region. Obtainable. In addition to these, an ink jet recording method in which the mixed color portion is formed with black ink (PK and / or MK) can also be provided.

In the recording method of the present invention, it is preferable to form an image so that the ink weight of 100% duty is 7 to 13 mg / inch ² .

Further, it is preferable that the mixed color forms an image so that the ink weight of Duty 120% is 8 to 16 mg / inch ² .

  In this specification, “Duty” is defined by the following formula and indicates a unit of the calculated value D.

  D = [actual print dot number / (vertical resolution × horizontal resolution)] × 100 Duty 100% means the maximum ink weight of a single color for a pixel.

[Recording system]
The present invention is a recording system that forms an image using the above-described ink set, and in particular, a recording apparatus such as an ink jet printer that uses the ink set of the above-described embodiment and other recording systems are suitable.

[Recorded material]
The present invention is a recorded matter in which an image is formed using the ink set described above, and in particular, one using the ink set of the above-described embodiment is preferable.

[Modification]
The present invention suitably provides each of the embodiments described above, but is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and test examples of the present invention. However, the present invention is not limited to the examples.

〔Example〕
(Preparation of ink set)
Yellow inks (Y1), (Y2), (y1), (y2), magenta inks (M1), (M2), (M3), cyan inks of the following compositions provided in the ink sets of Examples and Comparative Examples ( C1), (C2), photo black ink (PK1), and matte black ink (MK1) were prepared according to conventional methods. That is, after the colorant component was dispersed together with the dispersant component, other components were added and mixed, and the insoluble component having a certain size or more was filtered to prepare an ink. The obtained inks were combined to form ink sets of Examples and Comparative Examples.

  The yellow inks (Y1) and (Y2) are C.I. I. Pigment Yellow 129, (y1) and (y2) are C.I. I. Pigment Yellow 129 is not included.

<Yellow ink (Y1)>
C. I. Pigment Yellow 129 1.0% by weight
C. I. Pigment Yellow 74 1.0% by weight
Dispersant (styrene-acrylic acid copolymer) 0.8% by weight
Glycerin 20.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Yellow ink (Y2)>
C. I. Pigment Yellow 129 1.0% by weight
C. I. Pigment Yellow 74 3.0% by weight
Dispersant (styrene-acrylic acid copolymer) 1.6% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Yellow ink (y1)>
C. I. Pigment Yellow 74 3.0% by weight
Dispersant (styrene-acrylic acid copolymer) 1.8% by weight
Glycerin 20.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Yellow ink (y2)>
C. I. Pigment Yellow 74 6.0% by weight
Dispersant (styrene-acrylic acid copolymer) 2.4% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Magenta ink (M1)>
C. I. Pigment Violet 19 2.0% by weight
Dispersant (styrene-acrylic acid copolymer) 0.8% by weight
Glycerin 20.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Magenta ink (M2)>
C. I. Pigment Violet 19 4.0% by weight
Dispersant (styrene-acrylic acid copolymer) 1.6% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Magenta ink (M3)>
C. I. Pigment Red 122 4.0% by weight
Dispersant (styrene-acrylic acid copolymer) 1.6% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Cyan ink (C1)>
C. I. Pigment Blue 15: 3 1.5% by weight
Dispersant (styrene-acrylic acid copolymer) 0.6% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Cyan ink (C2)>
C. I. Pigment Blue 15: 3 4.0% by weight
Dispersant (styrene-acrylic acid copolymer) 1.6% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Photo black ink (PK1)>
Carbon black 2.0% by weight
Dispersant (styrene-acrylic acid copolymer) 2.0% by weight
Glycerin 15.0% by weight
1,2-hexanediol 7.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

<Matte black ink (MK1)>
Self-dispersing carbon black 6.0% by weight
Glycerin 12.0% by weight
1,2-hexanediol 3.0% by weight
Triethanolamine 0.9% by weight
BYK348 0.1% by weight
Ultra pure water remaining
Total 100.0% by weight

(Measurement of X value, Y value and Z value of diluted aqueous solution of each ink)
Calculated from the UV-visible transmission spectrum of the diluted aqueous solutions of the yellow inks (Y1), (Y2), (y1), (y2), magenta inks (M1), (M2), cyan inks (C1), (C2) described above. The diluted solution was diluted with pure water so that the Z value in the XYZ display system defined by the CIE was 23.00, and a diluted aqueous solution having a pigment solid content concentration of 0.01 wt% or less was prepared.

  Specifically, first, for each ink, the pigment content is 0.0005 wt%, 0.0010 wt%, 0.0015 wt%, 0.0020 wt%, 0.0025 wt%, 0.0030 wt%, 0 Dilution aqueous solutions of .0040 wt%, 0.0060 wt%, and 0.0080 wt% were prepared. Next, each of these aqueous solutions was measured as follows using U3300 manufactured by Hitachi, Ltd. That is, two quartz cells with a capacity of 1 cm in length, 1 cm in width, and 4 cm in height are prepared, divided into a sample side cell and a reference side cell, pure water is added to both cells, and these cells are measured. Set to baseline, measure baseline and set as baseline. The measurement conditions are as follows: the slit width of the light source lamp is 2 mm, the scanning speed of the measurement interval is 600 nm / min, the transmittance is 0.0 to 100.0% T, the photovoltage is 200 V within the range of 380 to 800 nm, and the light source lamp. The UV-visible transmission spectrum was measured as a D2 lamp and a WI lamp by switching 340 nm.

  Next, while leaving the cell on the reference side as it is, the cells on the sample side are filled with the respective aqueous solutions described above in place of pure water, the ultraviolet visible transmission spectrum is measured, and the XYZ display system defined by the CIE is used. , X value, Y value, and Z value were calculated under the conditions of a D65 light source and a viewing angle of 2 degrees.

  These values were plotted on a graph and connected with a curve, and the X value and the Y value when the Z value was 23.00 were determined from this curve.

  Table 1 shows the pigments contained therein and their concentrations, dilution factors, and measurement results for each ink.

  The yellow inks (Y1) and (Y2) had Y values of 89.65 and 88.90, respectively, when the Z value was 23.00, and were 86 or more. In contrast, the yellow inks (y1) and (y2) both had a Y value of 85.33 when the Z value was 23.00.

(Evaluation of color reproducibility 1)
Next, as one of the color reproducibility evaluation methods for yellow inks (Y1), (Y2), (y1), and (y2), each yellow ink and photo black ink are printed on a medium having a coating layer. L * value and b * value specified by CIE were measured.

Specifically, each yellow ink and photo black ink are filled in an ink jet printer PM900C (manufactured by Seiko Epson) and printed on the above-described PGPP (manufactured by Seiko Epson) as an example of a medium having a coating layer. Each recorded matter was obtained. Printing a Duty120% (ink weight 10~11mg / inch ^2), each yellow ink and photo black ink was performed by discharging in the proportions shown in Table 2.

  The obtained printed matter was measured with a Macbeth SPM50 manufactured by Gretag Co., Ltd. with a D50 light source and a viewing angle of 2 degrees, and L * value and b * value defined by CIE were obtained.

  The results are shown in FIG. 1 and FIG. FIG. 1 shows the result of comparing Y1 (Example 1), which is relatively thin yellow ink, with y1 (Comparative Example 1), and FIG. 2 shows Y2 (Example 2), which is relatively dark ink. And y2 (Comparative Example 2).

  Respectively, compared with the comparative example, although it is a low pigment solid content, it is low L * value and high b * value. It was confirmed that the low brightness yellow area could be expressed with good reproducibility.

(Evaluation of color reproducibility in the red area)
As shown in Table 3, five types of ink sets were prepared, and each ink set was filled in an ink jet printer PM900C and printed on PGPP at a resolution of 720 × 720 to obtain a recorded matter.

Tables 4 to 6 show the approximate ink weight (mg / inch ² ) of each ink during printing. Tables 4 to 6 are matrices, and each cell defines a printing place. Table 4 represents yellow ink, Table 5 represents magenta ink, and Table 6 represents photo black ink.

  The obtained recorded matter was measured using a Gretag Macbeth SPM50 manufactured by Gretag Co., Ltd. with a viewing angle of 2 degrees and a D50 light source, and L * value, a * value, and b * value specified by CIE were obtained. Using this value, C * was calculated from the following formula, and plotted on a graph with C * on the horizontal axis and L * on the vertical axis.

^{Formula: C * = (a * 2} + b * 2) 1/2
The results are shown in FIG. 3 and FIG.

  Compared with the comparative example, it was confirmed that the example had less variation and was excellent in color reproducibility in the red region.

(Evaluation of color reproducibility in the green area)
Five types of ink sets similar to the above-described evaluation of the color reproducibility of the red region are prepared, each ink set is filled in each ink in the ink jet printer PM900C, printed on PGPP at a resolution of 720 × 720, and a recorded matter is printed. Obtained.

Tables 7 to 9 show the approximate ink weight (mg / inch ² ) of each ink during printing. Tables 7 to 9 are matrices, and each cell defines a printing place. Table 7 represents yellow ink, Table 8 represents cyan ink, and Table 9 represents photo black ink.

  The obtained recorded matter was measured using a Gretag Macbeth SPM50 manufactured by Gretag Co., Ltd. with a viewing angle of 2 degrees and a D50 light source, and L * value, a * value, and b * value specified by CIE were obtained. Using this value, C * was determined from the above equation and plotted on a graph with C * on the horizontal axis and L * on the vertical axis.

  The results are shown in FIG. 5 and FIG.

  Compared with the comparative example, it was confirmed that the example had less variation and was excellent in color reproducibility in the red region.

The evaluation result of the color reproducibility of the low L * high b * area | region by the ink set of this invention is shown. The evaluation result of the color reproducibility of the low L * high b * area | region by the ink set of this invention is shown. The color reproducibility evaluation result of the red area | region of the ink set of this invention is shown. The color reproducibility evaluation result of the red area | region of the ink set of this invention is shown. The color reproducibility evaluation result of the green area | region of the ink set of this invention is shown. The color reproducibility evaluation result of the green area | region of the ink set of this invention is shown.

Claims (13)

  An ink set including yellow ink, magenta ink, and cyan ink,
  The yellow ink is C.I. I. Pigment yellow 129 and C.I. I. When the Z value in the XYZ display system defined by CIE is 23, calculated from the ultraviolet-visible transmission spectrum of a diluted aqueous solution containing Pigment Yellow 74 and weighing 10,000 times or less, the Y value is 86 or more.
Ink set.   C. above. I. The ink set according to claim 1, wherein the pigment yellow 129 is contained at least 10% by weight of the total pigment solid content contained in the yellow ink. The magenta ink is C.I. I. Pigment violet 19 or C.I. I. Pigment Red 122, the cyan ink is C.I. I. Pigment Blue 15: 3, respectively comprise a pigment The ink set according to claim 1 or 2. The ink set according to any one of claims 1 to 3 , further comprising black ink. The ink set according to claim 4 , wherein the black ink contains carbon black as a pigment. The ink according to any one of claims 1 to 5 , wherein each of the inks contains a pigment as a coloring material and a dispersant for dispersing the pigment in an amount of 10 to 140% by weight based on the pigment. set. The ink set according to any one of claims 1 to 6 , wherein each ink contains 0.1 to 30% by weight of a high-boiling organic solvent. The ink set according to any one of claims 1 to 7 , wherein each of the inks contains 1 to 20% by weight of a penetration enhancer. Wherein each ink is an acetylene glycol compound and at least one 0.01-5 wt% of the silicone compound, the ink set according to any one of claims 1 to 8. An ink cartridge containing the ink set according to any one of claims 1 to 9. Recording method for forming images using the ink set according to any one of claims 1 to 9. Recording system for forming images using the ink set according to any one of claims 1 to 9. Recorded matter on which an image is formed using the ink set according to 9 any one of claims 1.

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