AU2017202189B2

AU2017202189B2 - Ink jet ink set, ink cartridge set, ink jet recording device, and ink jet recording method

Info

Publication number: AU2017202189B2
Application number: AU2017202189A
Authority: AU
Inventors: Takuma Ishihara; Yukari Motosugi; Akira Sakamoto; Takeshi Zengo
Original assignee: Fujifilm Business Innovation Corp
Current assignee: Fujifilm Business Innovation Corp
Priority date: 2016-09-01
Filing date: 2017-04-03
Publication date: 2018-06-14
Anticipated expiration: 2037-04-03
Also published as: CN107793840A; AU2017202189A1; JP2018035295A

Abstract

Abstract Provided is an ink jet ink set including: a first ink that contains an infrared absorbent and water; and a second ink that contains an infrared absorbent and water. A expression (1) y = a x exp(lOx) + b is a relational expression between viscosity and an evaporation rate of the ink. A value of coefficient a of the expression (1) in the second ink is 1.5 times or greater than the coefficient a in the first ink. In the expression (1), x is a weight evaporation rate in the ink and expresses a value which is from 0 to 0.6, y expresses viscosity (mPa-s) of the ink at 300C, and b expresses a y-intercept. C) (D C'4 C\j OD C\l 04 C) co C%4 00 (14 C'4 C) C) 04 co \1 0

Description

Technical Field [0001] The present invention relates to an inkjet ink set, an ink cartridge set, an inkjet recording device, and an inkjet recording method.

Related Art [0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0003] Since it is easy to achieve a wide width and a high speed of printing, in recent years, the share of an inkjet printing technology in the printing field has largely increased.

[0004] As ink jet recording methods of the related art, for example, methods described in JP2013-188920A, JP2015-150695A, and JP2011-201037A are known.

[0005] For example, in JP2013-188920A, there is suggested “an inkjet recording device including: a transporting unit that transports a recording medium; plural ink jet heads that are disposed to be aligned along a transport direction of the recording medium, and discharge ink of each color containing a coloring agent and an infrared absorbent onto the transported recording medium; and plural laser irradiating units of which the number is the same as that of the plural ink jet heads, are disposed further on the downstream side in the transport direction of the recording medium than each of the plural inkjet heads, and irradiate each color of ink discharged onto the recording medium with infrared laser by the plural inkjet heads, which satisfies

2017202189 16 May 2018 all of the following conditions (1) to (3) or satisfies the following conditions (1) and (4), in which (1): the infrared absorbent contained in each color of the ink has a maximum absorption wavelength which is the same as or similar to an oscillation wavelength of the infrared laser irradiated first after the ink is discharged, (2): (a) the ink containing the infrared absorbent having the same or similar maximum absorption wavelength in each color of the ink, and (b) infrared absorptivity with respect to the oscillation wavelength of the infrared laser irradiated first after the ink is discharged increases in order of being discharged by the ink jet head across the downstream side from the upstream side in the transport direction of the recording medium, in the ink, (3): (a) the laser irradiating unit which irradiates the infrared laser having the same oscillation wavelength exists among the plural laser irradiating units, and (b) irradiating energy by the infrared laser of the laser irradiating unit decreases in order across the downstream side from the upstream side in the transport direction of the recording medium, and (4): the laser irradiating unit which irradiates the infrared laser having different oscillation wavelength exists among the plural laser irradiating units”.

[0006] In addition, in JP2015-150695A, there is suggested “an image recording method including: an ink supplying process of supplying plural aqueous inks to each of recording mediums; and a drying process of drying the recording medium to which the ink is supplied, in which an absorption coefficient Ka with respect to water of the recording medium is equal to or less than 0.3 mL/m²-ms^1/2, viscosity of moisture-removed ink in which the water is removed from the ink is low as much as viscosity of the ink is high in the plural aqueous inks, and the ink is supplied to the recording medium in order from the ink having high viscosity among the plural inks in the ink supplying process”.

2017202189 16 May 2018 [0007] Furthermore, in JP2011-201037A, there is suggested “an inkjet recording method of forming an image having combination colors on a recording sheet by discharging droplets of ink from orifice of the recording head in accordance with a recording signal, in which the type of ink is equal to or greater than two of which colors are different from each other that thicken by heating, and printing is performed in order from ink having low viscosity at 70°C by heating the recording sheet to be equal to or higher than 70°C before the droplets of the ink land on the recording sheet or when the droplets land on the recording sheet”.

SUMMARY [0008] The invention provides an ink jet ink set in which inter-color blur in an obtained image is prevented and discharge stability of ink is excellent.

[0009] [1] According to an aspect of the invention, an ink jet ink set including: a first ink that contains an infrared absorbent and water; and a second ink that contains an infrared absorbent and water is provided. In the inkjet ink set, a value of coefficient a of the following expression (1) in the second ink is 1.5 times or greater than the coefficient a in the first ink.

Expression (1) is a relational expression between viscosity and an evaporation rate of each ink.

Expression (1): y = a * exp(10x) + b

In expression (1), ‘x’ is a weight evaporation rate in the ink and expresses a value which is from 0 to 0.6, ‘y’ expresses viscosity (mPa-s) of the ink at 30°C, ‘a’ is a coefficient indicating an increase trend in viscosity that corresponds to the evaporation rate in the ink and ‘b’ expresses a y-intercept.

2017202189 16 May 2018 [0010] [2] In the ink jet ink set of [1], the viscosities at 30°C of all of the inks included in the ink jet ink set are from 4 mPa-s to 10 mPas.

[0011] [3] In the ink jet ink set of [1] or [2], each of the first ink and the second ink further contain an organic solvent.

[0012] [4] According to another aspect of the invention, an ink cartridge set including: a first ink cartridge that stores the first ink of the ink jet ink set of any one of [1] to [3], and a second ink cartridge that stores the second ink of the ink jet ink set therein.

[0013] [5] According to another aspect of the invention, an ink jet recording device which houses the ink jet ink set of any one of [1] to [3] therein, including: a first discharge head that discharges the first ink onto a recording medium; a second discharge head that discharges the second ink onto the recording medium; and an infrared irradiating unit that dries at least one of the first ink and the second ink which are discharged onto the recording medium are provided.

[0014] [6] According to another aspect of the invention, an ink jet recording device which houses the inkjet ink set according to any one of [1] to [3] therein, including: a first discharge head that discharges the first ink onto a recording medium; a second discharge head that discharges the second ink onto the recording medium; a first infrared irradiating unit that dries the first ink discharged onto the recording medium;

and a second infrared irradiating unit that dries the second ink discharged onto the recording medium.

[0015] [7] According to another aspect of the invention, an ink jet recording method including: a process of discharging the first ink of the ink jet ink set according to any one of [1] to [3] onto a recording medium; a process of discharging the second ink of the inkjet ink set onto the recording medium; and a process of

2017202189 16 May 2018 drying at least one of the first ink and the second ink which are discharged onto the recording medium by irradiating infrared light is provided.

[0016] According to the inkjet ink set of [1], inter-color blur in an obtained image is prevented and discharge stability of ink is excellent compared to a case where an ink jet ink set in which the largest value of coefficient a of an expression (1) in all of the inks is less than 1.5 times with respect to the smallest value of coefficient a in all inks, is used.

[0017] According to the inkjet ink set of [2], inter-color blur in an obtained image is further prevented and discharge stability of each ink is excellent compared to a case where the ink set includes a ink in which the viscosity at 30°C is less than 4 mPas or exceeds 10 mPas.

[0018] According to the inkjet ink set of [3], the inks in which the largest value of coefficient a of the expression (1) in the inks is 1.5 times larger than the smallest value of the coefficient a are easily prepared and discharge stability of each ink is more excellent compared to a case where each ink of the ink set does not contain an organic solvent.

[0019] According to the ink cartridge set of [4], inter-color blur in an obtained image is prevented and discharge stability of ink is excellent compared to a case where an ink cartridge set including inks in which the largest value of coefficient a of the expression (1) in all of the inks is less than 1.5 times with respect to the smallest value of the coefficient a, is used.

[0020] According to the ink jet recording device of [5] or [6], inter-color blur in an obtained image is prevented and discharge stability of ink is excellent compared to a case where an inkjet recording device which houses an ink set in which the largest

2017202189 16 May 2018 value of coefficient a of the expression (1) in all of the inks is less than 1.5 times with respect to the smallest value of the coefficient a, is used.

[0021] According to the inkjet recording method of [7], inter-color blur in an obtained image is prevented and discharge stability of ink is excellent compared to a case where an ink set in which the largest value of the coefficient a of the expression (1) in all of the inks is less than 1.5 times with respect to the smallest value of the coefficient a, is provided.

[0022] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

BRIEF DESCRIPTION OF THE DRAWINGS [0023] Exemplary embodiment(s) of the present invention will be described in detail based on the following figure, wherein Fig. 1 is a configuration diagram illustrating an example of a recording device according to the exemplary embodiment.

DETAILED DESCRIPTION [0024] Hereinafter, the exemplary embodiment will be described.

[0025] In addition, descriptions of “parts by mass” and “% by mass” are respectively the same as “parts by weight” and “% by weight”.

[0026] An ink jet ink set (hereinafter, also simply referred to as “ink set) according to the exemplary embodiment includes a first ink that contains an infrared

2017202189 16 May 2018 absorbent and water; and a second ink that contains an infrared absorbent and water. A value of coefficient a of the following expression (1) in the second ink is

1.5 times or greater than the coefficient a in the first ink. Expression (1) is a relational expression between viscosity and an evaporation rate of each ink.

Expression (1): y = a * exp(10x) + b

In expression (1), x is a weight evaporation rate (hereinafter, also simply referred to as “evaporation rate”) in the ink and expresses a value which is from 0 to 0.6, y expresses viscosity (mPa-s) of the ink at 30°C, and b expresses a y-intercept.

[0027] In the ink jet ink set according to the exemplary embodiment, as described above, inter-color blur in an obtained image is prevented and discharge stability of each ink is excellent. The reasons thereof are not defined, but the reasons may be estimated as the reasons described in the following.

[0028] In recent years, an inkjet recording method for recording an image on printing paper which is a hardly infiltrating recording medium, or glass, plastic, ora film which is a non-infiltrating recording medium, by using aqueous ink, has been investigated.

[0029] The inter-color blur is a phenomenon in which a linear shape of an end portion (edge part) between two colors roughly disturbed in the image to be formed on the recording medium. The inter-color blur is generated when the discharged ink wets and spreads on the recording medium and an ink droplet discharged in advance moves by surface tension, or when the discharged ink droplet is integrated with other ink droplets discharged in advance or when the discharged ink droplet comes into contact with other ink droplets discharged in advance on the condition that the ink supplied onto the recording medium is not sufficiently dried.

2017202189 16 May 2018 [0030] In a case where the hardly infiltrating or non-infiltrating recording medium is used, even when the process of drying ink is provided, many inter-color blurs are seen.

[0031] In a case where the ink having high viscosity is used in order to simply prevent the inter-color blur, the discharge stability deteriorates when the ink jet discharge the ink.

[0032] In the aqueous ink, the viscosity of the ink exponentially increases in accordance with evaporation of ink components, and in particular, evaporation of water or an organic solvent which is likely to be volatilized. A relationship between the viscosity and the evaporation rate of the ink is expressed by an approximation.

The relationship is expressed by the following expression (1).

Expression (1): y = a * exp(10x) + b [0033] In the expression (1), x is a weight evaporation rate in the ink and expresses a value which is from 0 to 0.6, y expresses viscosity (mPas) of the ink at

30°C, and b expresses a y-intercept.

[0034] In addition, it is needless to say that exp(10x) = e^10x. e expresses Napier’s constant which is a base of natural logarithm.

[0035] In addition, since a region in which the ink evaporation rate exceeds 60% by weight depends on a solid content or the like of the ink, the region is not considered in the expression (1) in the exemplary embodiment.

[0036] Furthermore, since the expression (1) is an approximation, there is also a case where the value of b and the viscosity (viscosity of 0% by weight of the evaporation rate) at 30°C of the ink are different values.

[0037] The value of a is a coefficient of exp(1 Ox) in the expression (1). The coefficient a indicates an increase trend in viscosity that corresponds to the

2017202189 16 May 2018 evaporation rate in the ink. It is described that, as the value of coefficient a increases, an increase amount of the viscosity that corresponds to the increase in evaporation rate increases, and as the value of coefficient a decreases, the increase amount of the viscosity that corresponds to the increase of the evaporation rate decreases.

[0038] By using an ink jet ink set including: a first ink that contains an infrared absorbent and water; and a second ink that contains an infrared absorbent and water a value of coefficient a in the second ink of the above-described expression (1), which is an approximation in a range of 0% by weight to 60% by weight of the evaporation rate of the ink, is 1.5 times or greater than the coefficient a in the first ink, by irradiating the ink on the recording medium with the infrared laser after discharging one ink, and by discharging the other ink after this, the wet-spread of the ink discharged in advance is prevented and the inter-color blur is prevented.

[0039] In addition, the first ink and the second ink are inks having different increase trends of the viscosity, there is no influence on viscosity during the discharge which is viscosity at the time of 0% by weight of the evaporation rate, the inter-color blur is prevented without using the ink having high viscosity, and thus, discharge stability in the inkjet discharge is also excellent.

[0040] Hereinafter, the ink jet ink set according to the exemplary embodiment will be described in detail.

[0041] A calculation method of the coefficient a and the y-intercept b in the expression (1) in the inkjet ink set according to the exemplary embodiment is calculation by the following method.

[0042] By using RHEOMETER HAAKE MARS (manufactured by Thermo Fisher

Scientific), the viscosity of the ink at 1/750 s of a shearing speed is calculated at

2017202189 16 May 2018

30°C of a stage temperature at least at five points including 0% by weight of the evaporation rate of the ink, a range of 15% by weight ± 5% by weight, a range of

30% by weight ± 5% by weight, a range of 45% by weight ± 5% by weight, and a range of 60% by weight ± 5% by weight.

[0043] The values of a and b in the expression (1) are calculated by regression using a least-squares method and the measured values at the five points.

[0044] Each ink (unless otherwise noted, all of the inks included in the ink jet ink set according to the exemplary embodiment) preferably contains the water, and more preferably is aqueous ink.

[0045] In addition, from the viewpoint of discharge stability and drying speed, in each ink, the water is preferably from 50% by weight to 95% by weight, more preferably from 60% by weight to 90% by weight, and particularly preferably from

70% by weight to 85% by weight.

[0046] From the viewpoint of particularly preventing mixing of impurities or generation of microorganism, appropriate examples of water include ion exchange water, pure water, ultrapure water, distilled water, and ultrafiltered water.

[0047] From the viewpoint of discharge stability and preparation ease of the ink, each ink in the inkjet ink set according to the exemplary embodiment preferably contains an organic solvent.

[0048] The organic solvent is not particularly limited, but an organic solvent which is dissolved in water is preferable, and an aqueous organic solvent which will be described later is more preferable.

[0049] A method of preparing the first ink and the second ink in which the value of coefficient a of the expression (1) in the second ink is 1.5 times or greater than the coefficient a in the first ink is not particularly limited, but examples thereof include a

2017202189 16 May 2018 method of changing a content of a resin, a method of changing a content ratio of resins having different glass transition temperatures, a method of changing a content ratio of organic solvents having different boiling points, a method of changing a content ratio ofwater and an organic solvent, or a method in which two or more methods are combined with each other.

[0050] Among these, a method of changing a content ratio of organic solvents having different boiling points, a method of changing a content ratio ofwater and an organic solvent, or a method in which the methods are combined with each other, is particularly preferable.

[0051] The ink jet ink set according to the exemplary embodiment may include one or more inks other than the first ink and the second ink.

[0052] The ink other than the first ink and the second ink may be ink in which the value of coefficient a in the expression (1) corresponds to the coefficient a of the first ink or the second ink, or may be ink in which the value of a does not correspond to those of the first ink and the second ink, but the ink in which the value of the coefficient a corresponds to the coefficient a of the first ink or the second ink is preferable.

[0053] From the viewpoint of inter-color blur and discharge stability, the viscosity at 30°C of all of the inks of the ink jet ink set according to the exemplary embodiment is preferably from 4 mPa s to 10 mPas, and particularly preferably from mPas to 7 mPa-s.

[0054] In addition, from the viewpoint of inter-color blur and discharge stability, in all of the inks of the ink jet ink set according to the exemplary embodiment, a difference between the viscosity of the ink having high viscosity at 30°C and the viscosity of the ink having low viscosity at 30°C is preferably equal to or less than 3

2017202189 16 May 2018 mPa-s, more preferably equal to or less than 2 mPa-s, and particularly preferably equal to or less than 1 mPa-s.

[0055] As described above in the expression (1), the viscosity of the ink in the exemplary embodiment is measured at 30°C of a stage temperature and at 1/750 s of a shearing speed by using RHEOMETER HAAKE MARS (manufactured by

Thermo Fisher Scientific).

[0056] The first ink and the second ink (each ink) in the ink jet ink set according to the exemplary embodiment preferably respectively contain a coloring agent as will be described later.

[0057] The first ink and the second ink in the ink set according to the exemplary embodiment are preferably inks of different colors, and more preferably at least two types of ink selected from a group configured of cyan ink, magenta ink, and yellow ink.

[0058] In addition, from the viewpoint of forming a full-color image, the ink jet ink set according to the exemplary embodiment preferably includes cyan ink, magenta ink, and yellow ink, and more preferably includes cyan ink, magenta ink, yellow ink, and black ink.

[0059] From the viewpoint of inter-color blur and discharge stability, the ink jet ink set according to exemplary embodiment preferably includes cyan ink in which the value of coefficient a of the expression (1) is greater than those of magenta ink and yellow ink 1.5 times or greater, and more preferably includes cyan ink in which the value of coefficient a of the expression (1) is greater than those of magenta ink, yellow ink, and black ink 1.5 times or greater.

2017202189 16 May 2018 [0060] In the ink set according to the exemplary embodiment, in the ink irradiated with the laser, it is preferable that light absorptivity decrease as increasing in printing order and light absorptivity increase as decreasing in printing order.

[0061] The light absorptivity of the ink in the exemplary embodiment is measured by the following method.

[0062] Absorbance A in a laser wavelength of the ink diluted by pure water is measured by using ultraviolet visible near-infrared spectrophotometer V-560 (manufactured by JASCO Corporation) and a quartz cell having an angle of 10 mm, and absorptivity in the ink film thickness during the printing is acquired from a conversion expression based on Lambert-Beer law. In other words, the absorbance

A of a solution into which 1 g of ink weight Wink and 200 g of pure water W_water are mixed is measured, and the absorptivity % A = 1 _1 o^{_((Wink/Wwater}>^x(d/1O)xA> of the ink film thickness d = 5 χ 10'³ mm is calculated.

[0063] In addition, even when the ink jet ink set according to the exemplary embodiment includes ink having high light absorptivity, such as black ink in which deterioration of image density due to high temperature or blister (bulging) is likely to be generated, the ink temperature does not increase during the drying, deterioration of image density is prevented, and generation of blister is prevented.

[0064] Each ink used in the exemplary embodiment preferably contains an infrared absorbent, a coloring agent, and a solvent including water and an aqueous organic solvent, more preferably contains an infrared absorbent, a coloring agent, a polymer particle, and a solvent including water and an aqueous organic solvent, and particularly preferably contains an infrared absorbent, a coloring agent, a polymer particle, a polymer dispersing agent, a surfactant, and a solvent including water and an aqueous organic solvent.

2017202189 16 May 2018 (Infrared Absorbent) [0065] The first ink and the second ink which are used in the exemplary embodiment contain the infrared absorbent. As the infrared absorbent is contained, drying by irradiation of infrared light by infrared laser or the like is also used in drying the ink.

[0066] In addition, ink other than the first ink and the second ink which are used in the exemplary embodiment preferably contains the infrared absorbent from the viewpoint of drying speed and space saving in an inkjet recording device.

[0067] “Infrared absorbent” is referred to as a compound which absorbs the infrared light and generates heat.

[0068] “Infrared light” is referred to as light having a wavelength region of 700 nm to 1 mm, and the infrared absorbent used in the exemplary embodiment preferably contains maximum absorption in the wavelength region of 800 nm to 1,500 nm.

[0069] The infrared absorbent used in the exemplary embodiment is not particularly limited, and a known infrared absorbent is used. In addition, black pigment, such as carbon black, may function as an infrared absorbent.

[0070] In addition, as the infrared absorbent, it is preferable to use an inorganic material or organic dye, it is preferable to use an inorganic material from the viewpoint of heat generation amount, and it is preferable to use organic dye from the viewpoint that a near-infrared absorbent is decomposed by irradiation of nearinfrared light, color of the near-infrared absorbent itself becomes thin, and forming of an image by the ink is not interrupted.

[0071] As the inorganic material, metal oxide is preferable, and antimony tin oxide (ATO), indium tin oxide (ITO) or the like is preferably illustrated as an example.

2017202189 16 May 2018 [0072] Examples of the organic dye include cyanine dye, phthalocyanine dye, merocyanine dye, squarylium dye, onium compound, indolenine cyanine, pyrylium salt, and nickel thiolate complex. Among these, at least one type of organic dye selected from a group configured of cyanine dye, phthalocyanine dye, merocyanine dye, and squarylium dye is preferable.

[0073] Each ink used in the exemplary embodiment may contain one type of infrared absorbent independently, or may use two or more types thereof together.

[0074] A content of the infrared absorbent in each ink is preferably from 0.001% by weight to 3% by weight with respect to the entire weight of the ink, and more preferably from 0.005% by weight to 2% by weight. According to the range, the heat generation amount is also sufficient, and influence on forming the image by the ink is small.

[0075] As the infrared absorbent, it is also possible to use a commercially available infrared absorbent, and examples thereof include NIR series (manufactured by Nagase ChemteX Corporation), KAYASORB series (manufactured by Nippon Kayaku Co., Ltd.), and T-1 series (manufactured by

Mitsubishi Materials Electronic Chemicals Co., Ltd.).

(Aqueous Organic Solvent) [0076] Examples of the aqueous organic solvent include polyhydric alcohol, a derivative of polyhydric alcohol, nitrogen-containing solvent, alcohol, and sulfurcontaining solvent. In addition, examples of the aqueous organic solvent include propylene carbonate and ethylene carbonate.

[0077] As the aqueous organic solvent, an aqueous organic solvent of which a boiling point is equal to or greater than 150°C is preferable.

2017202189 16 May 2018 [0078] Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2hexanediol, 1,2,6-hexanetriol, and glycerine.

[0079] Examples of the derivative of polyhydric alcohol include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and ethylene oxide adduct of diglycerine.

[0080] Examples of nitrogen-containing solvent include pyrrolidone, N-methyl-2pyrrolidone, cyclohexylpyrrolidone, and triethanolamine.

[0081] Examples of alcohol include ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol.

[0082] Examples of sulfur-containing solvent include thiodiethanol, thiodiglycerol, sulfolane, and dimethyl sulfoxide.

[0083] One type of the aqueous organic solvent may be used or two or more types thereof may be used together.

[0084] Among these, it is preferable that each of the inks include polyhydric alcohol as the aqueous organic solvent from the viewpoint of adjustment of drying speed and clogging resistance properties of a head, it is more preferable to include the aqueous organic solvent selected from a group configured of propylene glycol and 1,2-hexanediol, and it is particularly preferable to include propylene glycol and

1,2-hexanediol.

[0085] A content of the aqueous organic solvent in each ink is preferably from 1% by weight to 60% by weight with respect to water, and more preferably from 1 % by weight to 40% by weight.

2017202189 16 May 2018 (Coloring Agent) [0086] Each ink used in the exemplary embodiment preferably contains the coloring agent.

[0087] As the coloring agent, an agent which corresponds to the ink of target color may be used, and specific examples include pigment and dye. Examples of pigment include organic pigment and inorganic pigment.

[0088] Specific examples of cyan pigment include C.l. Pigment Blue-1,-2, -3, -15,

-15:1, -15:2, -15:3, -15:4, -16, -22, and -60, but the invention is not limited thereto.

[0089] Specific examples of magenta pigment include C.l. Pigment Red-5, -7, -12,

-48, -48:1, -57, -112, -122, -123, -146, -168, -177, -184, -202, and C.l. Pigment

Violet -19, but the invention is not limited thereto.

[0090] Specific examples of yellow pigment include C.l. Pigment Yellow-1, -2, -3,

-12, -13, -14, -16, -17, -73, -74, -75, -83, -93, -95, -97, -98, -114, -128, -129, -138, 151, -154, and -180, but the invention is not limited thereto.

[0091] Examples of black pigment include carbon black, copper oxide, manganese dioxide, active carbon, nonmagnetic ferrite, and magnetite, but the invention is not limited thereto.

[0092] In addition, in addition to this, known pigment and dye are used.

[0093] Here, in a case where the pigment is used as the coloring agent, it is preferable to use a pigment dispersing agent together. Examples of pigment dispersing agent to be used include a polymer dispersing agent, an anionic surfactant which will be described later, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.

[0094] As the polymer dispersing agent, a polymer including a hydrophilic structure portion and a hydrophobic structure portion is appropriately used. As a

2017202189 16 May 2018 polymer including a hydrophilic structure portion and a hydrophobic structure portion, for example, a condensed polymer and an addition polymer are used. An example of the condensed polymer includes a known polyester dispersing agent.

An example of the addition polymer includes an addition polymer of a monomer having an α,β-ethylenically unsaturated group. A target polymer dispersing agent is obtained by combining and copolymerizing a monomer having an α,β-ethylenically unsaturated group including a hydrophilic group and a monomer having an α,βethylenically unsaturated group including a hydrophobic group. In addition, a homopolymer of a monomer having an α,β-ethylenically unsaturated group including a hydrophilic group is also used.

[0095] Examples of the monomer having an α,β-ethylenically unsaturated group including a hydrophilic group include a monomer having a carboxyl group, a sulfonate group, a hydroxyl group, and a phosphate group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonate, styrenesulfonic acid, sulfonated vinylnaphthalene, vinyl alcohol, acrylic amide, methacryloxy ethyl phosphate, bismethacryloxy ethyl phosphate, methacryloxy ethylphenyl acid phosphate, ethylene glycol dimethacrylate, and diethylene glycol dimethacrylate.

[0096] Examples of the monomer having an α,β-ethylenically unsaturated group including a hydrophobic group include styrene, α-methylstyrene, a styrene derivative, such as vinyltoluene, vinylcyclohexane, vinylnaphthalene, a vinylnaphthalene derivative, acrylic acid alkyl ester, methacrylic acid alkyl ester, methacrylic acid phenyl ester, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl ester, and maleic acid dialkyl ester.

2017202189 16 May 2018 [0097] Examples of a copolymer that is preferable as a polymer dispersing agent include a styrene-styrenesulfonic acid copolymer, a styrene-maleic acid copolymer, a styrene-methacrylic acid copolymer, a styrene-acrylic acid copolymer, a vinylnaphthalene-maleic acid copolymer, a vinylnaphthalene-methacrylic acid copolymer, a vinylnaphthalene-acrylic acid copolymer, an acrylic acid alkyl esteracrylic acid copolymer, a methacrylic acid alkyl ester-methacrylic acid copolymer, a styrene-methacrylic acid alkyl ester-methacrylic acid copolymer, a styrene-acrylic acid alkyl ester-acrylic copolymer, a styrene-methacrylic acid phenyl estermethacrylic acid copolymer, a styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, or salt thereof. In addition, a monomer having a polyoxyethylene group and a hydroxyl group may be copolymerized with respect to the polymers.

[0098] Among these, a polymer dispersing agent selected from a group configured of a styrene-acrylic acid copolymer and a styrene-acrylate copolymer is preferable, the styrene-acrylate copolymer is more preferable, and a styrene-alkali metal acrylate copolymer is particularly preferable.

[0099] A weight average molecular weight of the polymer dispersing agent which is from 2,000 to 50,000 is preferable. In addition, unless otherwise noted, the weight average molecular weight in the exemplary embodiment is a value which is measured by a gel permeation chromatography (GPC) and converted by standard polystyrene.

[00100] The polymer dispersing agents may be used independently or two or more types thereof may be used together. The content of the polymer dispersing agent cannot be said definitely since the content largely varies according to the pigment, but the content with respect to the pigment may be from 0.1% by weight to 100% by weight.

2017202189 16 May 2018 [00101] An example of the pigment also includes pigment (hereinafter, referred to as a self-dispersion type pigment) which self-disperses by the water.

[00102] The self-dispersion type pigment indicates a pigment which has a group soluble to water on a surface of pigment and disperses in water even when the polymer dispersing agent does not exist. The self-dispersion type pigment can be obtained by performing surface modification treatment, such as acid-base treatment, coupling agent treatment, polymer-graft treatment, plasma treatment, or redox treatment, with respect to the pigment.

[00103] Examples of the self-dispersion type pigment also include commercially available self-dispersion type pigments, such as Cab-o-jet-200, Cab-o-jet-300, Cabo-jet-400, IJX-157, IJX-253, IJX-266, IJX-273, IJX-444, IJX-55, Cab-o-jet-250C,

Cab-o-jet-260M, Cab-o-jet-270Y, Cab-o-jet-450C, Cab-o-jet-465M, Cab-o-jet-470Y, and Cab-o-jet-480M which are manufactured by Cabot Corporation, and Microjet

Black CW-1 or CW-2 manufactured by Orient Chemical Industries Co., Ltd., in addition to the pigment obtained by performing the surface modification treatment with respect to the above-described pigment.

[00104] As the self-dispersion type pigment, pigment having at least sulfonic acid, sulfonate, carboxylic acid, or carboxylate as a functional group on a surface thereof is preferable, and pigment having at least carboxylic acid or carboxylate as a functional group on a surface thereof is more preferable.

[00105] Here, an example of the pigment also includes pigment coated with a resin. The pigment is called microcapsule pigment, and is a commercially available microcapsule pigment manufactured by DIC Corporation, Toyo Ink SC Holdings Co.,

Ltd., and the like. In addition, the invention is not limited to the commercially

2017202189 16 May 2018 available microcapsule pigment, and may use microcapsule pigment prepared in accordance with the goal.

[00106] In addition, an example of the pigment also includes resin dispersion type pigment obtained by physically suctioning or by chemically coupling a polymer compound to the pigment.

[00107] In addition, examples of the pigment include specific color pigment, such as red, green, blue, brown, white, or black, metal glossy pigment, such as gold or silver, extender pigment, such as colorless or hypochromic, or a plastic pigment, and plastic pigment, in addition to three primary color pigments, such as cyan, magenta, and yellow.

[00108] In addition, examples of the pigment also include particles in which dye or pigment is fixed to the surface thereof, an insolubilized (laked) material of dye, coloring emulsion, or coloring latex, considering silica, alumina, or polymer bead as a core.

[00109] Examples of the coloring agent also include dye type, such as hydrophilic anionic dye, direct dye, cationic dye, reactive dye, polymer dye, or oil-soluble dye, wax powder colored by dye, resin powder, emulsion, or fluorescent dye or fluorescent pigment, in addition to the pigment.

[00110] A volume average particle diameter of the coloring agent is, for example, from 10 nm to 1,000 nm.

[00111] The volume average particle diameter of the coloring agent is a particle diameter of the coloring agent itself or is a particle diameter by which an additive adheres in a case where the additive, such as a dispersing agent, adheres to the coloring agent.

2017202189 16 May 2018 [00112] Measurement of the volume average particle diameter is performed by

UPA-UT151 (manufactured by Microtrac) which is a microtrack UPA particle size analyzer. The measurement is performed by inputting the ink diluted by 1,000 times into a measurement cell. In addition, as an input value during the measurement, viscosity of ink diluted solution is employed as viscosity, and a refraction factor of the coloring agent is employed as a particle refraction factor.

[00113] A content (density) of the coloring agent is preferably, for example, from

1% by weight to 25% by weight with respect to the ink, and more preferably from 2% by weight to 20% by weight.

(Polymer Particles) [00114] Polymer particles will be described.

[00115] Each ink used in the exemplary embodiment preferably contains polymer particles.

[00116] The polymer particles are components having high fixability of an image obtained by the ink with respect to the recording medium.

[00117] In addition, the polymer particles are components obtained by making the polymer component in a shape of a particle, and is different from the abovedescribed polymer dispersing agent.

[00118] Examples of polymer particles include particles (latex particles), such as a styrene-acrylic acid copolymer, styrene-acrylic acid-sodium acrylate copolymer, a styrene-butadiene copolymer, polystyrene, an acrylonitrile-butadiene copolymer, an acrylic acid ester copolymer, polyurethane, polyester, a silicone-acrylic copolymer, and acrylate-modified fluororesin.

2017202189 16 May 2018 [00119] In addition, an example of the polymer particles also include core shell type polymer particles of which compositions are different in the center portion of the particles and in an outer edge portion.

[00120] The polymer particles may disperse in the ink by using an emulsifying agent, and may disperse in the ink without using the emulsifying agent.

[00121] Examples of the emulsifying agent include a surfactant, a sulfonate group, and polymer (for example, a polymer to which the hydrophilic group is graft-coupled, and a polymer configured of a hydrophilic monomer and a hydrophobic monomer) having hydrophilic group, such as a carboxyl group.

[00122] From the viewpoint of glossiness and scratch resistance of the image, the volume average particle diameter of the polymer particle is preferably from 10 nm to

300 nm, and more preferably from 10 nm to 200 nm.

[00123] The measurement of the volume average particle diameter of the polymer particle is performed by UPA-UT151 (manufactured by Microtrac) which is a microtrack UPA particle size analyzer. The measurement is performed by inputting the ink diluted by 1,000 times into a measurement cell. In addition, as an input value during the measurement, viscosity of ink diluted solution is employed as viscosity, and a refraction factor of the polymer particles is employed as a particle refraction factor.

[00124] From the viewpoint of preventing landing unevenness, a glass transition temperature of the polymer particle is preferably from 40°C to 90°C, and more preferably from 70°C to 90°C. Meanwhile, from the viewpoint of scratch resistance of the image, the glass transition temperature of the polymer particle is preferably from -20°C to 80°C, and more preferably from -10°C to 60°C.

2017202189 16 May 2018 [00125] The glass transition temperature of the polymer particle is acquired by a

DSC curve obtained by a differential scanning calorimetry (DSC), and more specifically, is acquired by “extrapolated glass transition starting temperature” described in a method of acquiring the glass transition temperature of JIS K7121 1987 “transition temperature measuring method of plastic”.

[00126] From the viewpoint of increasing fixability of the image, and from the viewpoint of discharge stability and film forming properties, the content of the polymer particles is preferably from 0.1% by weight to 10% by weight with respect to the ink, and more preferably from 0.5% by weight to 5% by weight.

(Surfactant) [00127] A surfactant will be described.

[00128] Each ink used in the exemplary embodiment preferably contains a surfactant.

[00129] It is preferable that the ink contain, for example, a surfactant of which “hydrophile-lipophile balance (HLB)” is equal to or less than 14, as a surfactant. By adjusting an amount of a surfactant of which HLB is equal to or less than 14, or by using plural types of surfactants having different HLBs, the adjustment of surface tension of the ink becomes easy.

[00130] In addition, the “hydrophile-lipophile balance (HLB)” is defined by the following expression (Griffin method).

[00131] HLB = 20 x (Total formula weight of hydrophilic portion/molecular weight).

[00132] An example of the surfactant includes at least one type selected from a group configured of an ethylene oxide adduct of acetylenic glycol and polyethermodified silicone.

2017202189 16 May 2018 [00133] The ethylene oxide adduct of acetylenic glycol is, for example, a compound having a -O-(CH2CH2O)_n-H structure (for example, n indicates an integer from 1 to 30) obtained by adding ethylene oxide to at least one hydroxyl group of acetylenic glycol.

[00134] Examples of a commercially available ethylene oxide adduct of acetylenic glycol (numbers in parentheses indicate catalogue numbers of HLB) include Olfine

E1004 (7 to 9), Olfine E1010 (13 to 14), Olfine EXP. 4001 (8 to 11), Olfine EXP.

4123 (11 to 14), Olfine EXP. 4300 (10 to 13), Surfynol 104H(4), Surfynol 420(4),

Surfynol 440(4), and Dynol 604(8) (which are manufactured by Nissin Chemical

Industry Co., Ltd.).

[00135] Polyether-modified silicone is, for example a compound obtained by coupling a polyether group to a silicone chain (polysiloxane main chain) in a grafted shape, or a compound obtained by performing the coupling in a blocked shape.

Examples of the polyether group include a polyoxyethylene group and a polyoxypropylene group. An example of the polyether group may include, for example, a polyoxyalkylene group to which an oxyethylene group and an oxypropylene group are added in a blocked shape or randomly.

[00136] Examples of commercially available polyether-modified silicone (numbers in parentheses indicate catalogue numbers of HLB) include Silface SAG002 (12),

Silface SAG503A (11), and Silface SAG005(7) (which are manufactured by Nissin

Chemical Industry Co., Ltd.).

[00137] In addition to the ethylene oxide adduct of acetylenic glycol and the polyether-modified silicone, other surfactants may be used in the ink.

2017202189 16 May 2018 [00138] Examples of the other surfactants include an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant, and the anionic surfactant and the nonionic surfactant are preferable.

[00139] Examples of the anionic surfactant include alkylbenzenesulfonate, alkylphenylsulfonate, alkylnaphthalenesulfonate, higher fatty acid salt, surlfuric acid ester salt of higher fatty acid ester, sulfonate of higher fatty acid ester, surlfuric acid ester salt and sulfonate of higher alcohol ether, higher alkylsulfosuccinate, polyoxyethylene alkyl ether carboxylic acid salt, polyoxyethylene alkyl ether sulfate, alkyl phosphate, and polyoxyethylene alkyl ether phosphate.

[00140] Among these, as the anionic surfactant, dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenyl phenol monosulfonate, monobutylbiphenylsulfonate, and dibutylphenylphenoldisulfonate, may be employed.

[00141] Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerine fatty acid ester, polyoxyethylene glycerine fatty acid ester, polyglyceryl fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, alkylalkanolamide, polyethylene glycol polypropylene glycol block copolymer, and acetylenic glycol.

[00142] Among these, as the nonionic surfactant, polyoxyethylene nonyl phenyl ether, polyoxyethylene octylphenylether, polyoxyethylenedodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, polyethylene glycol polypropylene glycol block copolymer, and acetylenic glycol, may be employed.

2017202189 16 May 2018 [00143] In addition to this, examples of the nonionic surfactant also include: a silicone-based surfactant, such as a polysiloxane oxyethylene adduct; a fluorochemical surfactant, such as perfluoroalkyl carboxylate, perfluoroalkylsulphonate, or oxyethylene perfluoroalkyl ether; and biosurfactant, such as spiculisporic acid, rhamnolipid, or lysolecithin.

[00144] When considering solubility or the like, hydrophile-lipophile balance (HLB) of the other surfactants may be, for example in a range from 3 to 20.

[00145] One type of surfactant may be used or two or more types thereof may be used together.

[00146] Among these, as a surfactant, the ethylene oxide adduct of acetylenic glycol is preferable, and more preferably, each ink contains two or more types of ethylene oxide adduct of acetylenic glycol.

[00147] A total content of the surfactant in each ink is preferably from 0.1% by weight to 10% by weight, more preferably from 0.1% by weight to 5% by weight, and still more preferably from 0.2% by weight to 3% by weight, with respect to the ink.

(Other Additives) [00148] Other additives will be described.

[00149] Each ink used in the exemplary embodiment may include other additives.

[00150] Examples of the other additives include an ink discharge properties improvement agent (polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethyl cellulose, carboxymethyl cellulose, and the like), a conductivity/pH adjusting agent (compound of alkali metal, such as potassium hydroxide, sodium hydroxide, or lithium hydroxide), an organic solvent other than the aqueous organic solvent, a reactive diluent solvent, a penetrating agent, a pH

2017202189 16 May 2018 buffer, an antioxidant, an antifungal agent, a viscosity modifier, a conductive material, a chelating agent, and an ultraviolet absorbent.

(Physical Properties of Each Ink) [00151] Appropriate physical properties of each ink will be described.

[00152] In a case where each ink is aqueous ink, pH of each aqueous ink is preferably in a range from 4 to 10, and more preferably in a range from 5 to 9.

[00153] Here, as pH of aqueous ink, a value measured by a pH/conductivity meter (MPC227 manufactured by Mettler Toledo, Inc.) under the condition that temperature is 23 ± 0.5°C and humidity is 55 ± 5% R.H.

[00154] In addition, in a case where each ink is aqueous ink, the conductivity of each aqueous ink is preferably in range from 0.01 S/m to 0.5 S/m, more preferably in a range from 0.01 S/m to 0.25 S/m, and still more preferably in a range from 0.01

S/m to 0.20 S/m.

[00155] The measurement of conductivity is performed by MPC227 (pH/conductivity meter manufactured by Mettler Toledo, Inc.).

(Application) [00156] Here, examples of each ink used in the exemplary embodiment include cyan ink, magenta ink, yellow ink, black ink, white ink, neutral color ink other than these colors, spot color ink, such as green ink, orange ink, and violet ink, and metallic ink.

[Recording Medium] [00157] A recording medium which is a target to be recorded using the inkjet ink set according to the exemplary embodiment is not particularly limited, and every known recording medium can be employed.

2017202189 16 May 2018 [00158] According to the inkjet recording method according to the exemplary embodiment and the inkjet recording device according to the exemplary embodiment, inter-color blur with respect to the recording medium having low infiltration properties or non-infiltration properties by which inter-color blur is likely to be generated, is prevented.

[00159] In addition, an example of the infiltrating recording medium includes plain paper or the like. Specifically, the infiltrating recording medium means a recording medium of which the maximum liquid adsorption amount of the ink when contact time measured by a dynamic scanning photometer is equal to or less than 500 ms exceeds 15 ml/m².

[00160] Meanwhile, examples of the non-infiltrating recording medium include a film and a plate which are made of a material, such as a resin, metal, glass, ceramics, silicon, or rubber. Specifically, the non-infiltrating recording medium means a recording medium of which the maximum liquid adsorption amount of the ink when contact time measured by a dynamic scanning photometer is equal to or less than 500 ms is less than 3 ml/m².

[00161] An example of the recording medium having low infiltration properties includes processed paper, such as coated paper, art paper, or cast paper.

Specifically, the recording medium having low infiltration properties means a recording medium of which the maximum liquid adsorption amount of the ink when the contact time measured by a dynamic scanning photometer is equal to or less than 500 ms is in a range from 3 ml/m² to 15 ml/m².

[00162] As the recording medium, the processed paper and the resin film are preferable, and the processed paper is more preferable.

[Ink Cartridge Set]

2017202189 16 May 2018 [00163] An ink cartridge set according to the exemplary embodiment includes: a first ink cartridge that stores the first ink of the ink jet ink set according to the exemplary embodiment; and a second ink cartridge that stores the second ink of the ink jet ink set according to the exemplary embodiment.

[00164] It is preferable that each ink cartridge in the ink cartridge set according to the exemplary embodiment be provided, for example, in an aspect of being attachable to and detachable from the inkjet type recording device.

[00165] The ink cartridge set according to the exemplary embodiment may include an ink cartridge in addition to the first ink cartridge and the second ink cartridge.

[Ink Jet Recording Device and Ink Jet Recording Method] [00166] The inkjet recording device according to the exemplary embodiment houses the inkjet ink set according to the exemplary embodiment therein, and includes: a first discharge head that discharges the first ink onto the recording medium; a second discharge head that discharges the second ink onto the recording medium; and an infrared irradiating unit that dries at least one of the first ink and the second ink which are discharged onto the recording medium.

[00167] In addition, an aspect of the ink jet recording device according to the exemplary embodiment that houses the ink set according to the exemplary embodiment therein, and includes a yellow ink discharge head that discharges yellow ink onto the recording medium; a magenta ink discharge head that discharges magenta ink onto the recording medium; a cyan ink discharge head that discharges cyan ink onto the recording medium; a black ink discharge head that discharges black ink onto the recording medium; a first infrared irradiating unit that dries the yellow ink discharged onto the recording medium; a second infrared

2017202189 16 May 2018 irradiating unit that dries the magenta ink discharged onto the recording medium;

and a third infrared irradiating unit that dries the cyan ink discharged onto the recording medium, and in which each of the first ink and the second ink is at least one type of ink selected from a group configured of yellow ink, magenta ink, cyan ink, and black ink, is preferable.

[00168] In the inkjet recording device according to the exemplary embodiment, the inkjet recording method (inkjet recording method according to the exemplary embodiment) including: a process of discharging the first ink onto the recording medium in the inkjet ink set according to the exemplary embodiment; a process of discharging the second ink onto the recording medium in the inkjet ink set according to the exemplary embodiment; and a process of drying at least one of the first ink and the second ink which are discharged onto the recording medium by irradiation of the infrared light, is realized.

[00169] The discharge head used in discharging the ink droplets is not particularly limited, a known inkjet head is used, and examples thereof include a piezo type ink jet head or a thermal type ink jet head.

[00170] A discharge temperature of each ink is not particularly limited, and can be adjusted in accordance with the ink to be used.

[00171] In the inkjet recording device and the inkjet recording method according to the exemplary embodiment, the discharge of each ink may be performed plural times as necessary. For example, one type of ink may be discharged plural times at the same location of the recording medium, two or more types of ink may be respectively discharged one time, or two or more types of ink may be respectively discharged plural times.

2017202189 16 May 2018 [00172] In the inkjet recording device according to the exemplary embodiment, from the viewpoint of inter-color blur, it is preferable to dispose the discharge head that discharges ink having low light absorptivity on the upstream side in the recording medium transport direction, and the discharge head that discharges ink having high light absorptivity on the downstream side in order in accordance with the light absorptivity of each ink.

[00173] The infrared irradiating unit is not particularly limited, but a unit which can irradiate the recording medium with the infrared light of which a wavelength region is at least from 760 nm to 1,500 nm is preferable, and for example, an infrared laser irradiating device is appropriate.

[00174] In addition, examples of the infrared irradiating unit include an infrared laser irradiating device and an infrared light-emitting diode (infrared LED). Among these, the infrared laser irradiating device is preferable.

[00175] Furthermore, as an infrared irradiating unit, it is also possible to use an infrared laser irradiating unit of which plural infrared laser light-emitting elements are disposed along the width direction of the recording medium.

[00176] In the infrared laser irradiating unit, irradiation timing, irradiation positions, and irradiation amounts of the laser of each infrared laser light-emitting element are, for example, preferably adjusted for each infrared laser light-emitting element in accordance with a current value supplied to each infrared laser light-emitting element. The infrared laser irradiating unit includes an adjustment mechanism of the current value as described above, and a sensor which measures the irradiation amount of the infrared laser, and accordingly, it is possible to include a mechanism which controls irradiation timing of the infrared laser, or a mechanism which corrects unevenness of the irradiation amount of the infrared laser.

2017202189 16 May 2018 [00177] An example of the infrared laser irradiating unit includes a laser drying unit described in JP-A-2015-112792.

[00178] The irradiation of the infrared laser may be performed on the entire surface of the recording medium or may be performed at a part thereof, but it is preferable to irradiate a region including at least a location to which the ink is discharged.

[00179] The irradiation amount of the infrared amount may be an amount appropriate for drying the ink, but preferably from 1,000 J/m² to 100,000 J/m², more preferably from 3,000 J/m² to 70,000 J/m², and still more preferably from 5,000 J/m²to 50,000 J/m². In addition, the irradiation amount of the infrared light is an irradiation amount of the infrared light on the front surface of the recording medium.

[00180] The irradiation time of the infrared light is not particularly limited, the ink may be irradiated until being dried, but the irradiation time is preferably from 100 με to 1 s, more preferably from 500 με to 0.5 s, and still more preferably from 0.1 ms to

0.3 s.

[00181] In addition, from the viewpoint of inter-color blur, it is preferable that the ink jet recording device according to the exemplary embodiment include the infrared irradiating unit respectively between each of the discharge heads (discharge units).

[00182] Furthermore, from the viewpoint of inter-color blur, it is preferable that the ink jet recording device according to the exemplary embodiment include a drying unit in addition to the infrared irradiating unit on the downstream side in the recording medium transport direction of all of the discharge heads (discharge units).

The drying unit is not particularly limited, a known unit is used, and examples thereof include a drying drum, a warm air blowing device, or a near-infrared heater.

[00183] The inkjet recording device and the inkjet recording method according to the exemplary embodiment use the inkjet ink set according to the exemplary

2017202189 16 May 2018 embodiment, and accordingly, the discharge stability of the ink is excellent, and an image in which the inter-color blur is prevented is formed.

[00184] The inkjet recording device according to the exemplary embodiment may include an ink cartridge set that includes ink cartridges each stores each ink in the ink jet ink set according to the exemplary embodiment therein, and made in a shape of a cartridge that is configured to attach to and detach from the recording device.

[00185] Hereinafter, an example of the recording device according to the exemplary embodiment will be described with reference to the drawings.

[00186] Fig. 1 is a configuration diagram illustrating an example of the inkjet recording device according to the exemplary embodiment.

[00187] As illustrated in Fig. 1, an inkjet recording device 10 includes discharge heads 122Y, 122M, 122C, and 122K which discharge each ink onto a recording medium P. The ink jet recording device 10 includes the discharge unit that discharges aqueous ink onto the recording medium P. Accordingly, an image obtained by the aqueous ink is recorded on the recording medium P.

[00188] Specifically, the inkjet recording device 10 includes, for example, an image recording unit 12 which records an image on a continuous form paper as the recording medium P (hereinafter, also referred to as “continuous form paper P”).

[00189] The inkjet recording device 10 includes: a preprocessing unit 14 which houses the continuous form paper P therein; a buffer unit 16 which adjusts a transport amount or the like of the continuous form paper P supplied to the image recording unit 12 from the preprocessing unit 14. The buffer unit 16 is disposed between the image recording unit 12 and the preprocessing unit 14.

[00190] The recording device 10 includes, for example, a postprocessing unit 18 which stores the continuous form paper P output from the image recording unit 12

2017202189 16 May 2018 therein, and a buffer unit 20 which adjusts the transport amount or the like of the continuous form paper P output to the postprocessing unit 18 from the image recording unit 12. The buffer unit 20 is disposed between the image recording unit and the postprocessing unit 18.

[00191] The ink jet recording device 10 includes a cooling unit 22 which is disposed between the image recording unit 12 and the buffer unit 20 and cools the continuous form paper P transported from the image recording unit 12.

[00192] The image recording unit 12 includes, for example, a roll member (reference numeral is omitted) which guides the continuous form paper P along a transport path 124 of the continuous form paper P, and a discharge device 121 which discharges aqueous ink (droplets of the aqueous ink) to the continuous form paper P transported along the transport path 124 of the continuous form paper P and records the image.

[00193] The discharge device 121 includes discharge heads 122Y, 122M, 122C, and 122K which discharge each ink to the continuous form paper P. The discharge head is, for example, a long recording head in which a valid recording region (disposition region of a nozzle which discharges the ink) is equal to or greater than a width (length in the direction that intersects with (for example, orthogonal to) the transport direction of the continuous form paper P) of the continuous form paper P.

[00194] In addition, the discharge head is not limited thereto, is a discharge head that is shorter than the width of the continuous form paper P, and may be a discharge head of a type of moving in the width direction of the continuous form paper P and discharging the aqueous ink (so-called carriage type).

[00195] The discharge heads 122Y, 122M, 122C, and 122K may be a so-called thermal type that discharges droplets of the ink by heat, or may be a so-called piezo

2017202189 16 May 2018 type that discharges droplets of the ink by pressure, and a known discharge head is employed.

[00196] The inkjet recording device 10 includes, for example, the discharge head

122Y which discharges the ink to the continuous form paper P and records an image having Y (yellow) color; the discharge head 122M which records an image having M (magenta) color; the discharge head 122C which records an image having C (cyan) color; and the discharge head 122K which records an image having K (black) color.

In addition, the discharge head 122Y, the discharge head 122M, the discharge head

122C, and the discharge head 122K are aligned from the upstream side to the downstream side along the transport direction of the continuous form paper P (hereinafter, there is a case of being simply described as “paper transport direction”) in this order to oppose the continuous form paper P. In expressing the discharge head, in a case where Y, M, C, and K are not distinguished, Y, M, C, and K attached to the reference numerals are omitted.

[00197] The discharge device 121 is not limited to an aspect in which four first discharge heads and four second discharge heads which respectively correspond to each of the four colors, and in accordance with the goal, an aspect in which four or more first discharge heads and four or more second discharge heads which respectively correspond to each of four or more colors to which other neutral colors are added, may be employed.

[00198] Here, as the discharge heads 122Y, 122M, 122C, and 122K, for example, any of a discharge head for low resolution that discharges ink within a range in which the ink droplet amount is equal to or less than 15 pi (for example, a discharge head having 600 dpi), and a discharge head for high resolution that discharges ink within a range in which the ink droplet amount is less than 10 pi (for example, a

2017202189 16 May 2018 discharge head having 1,200 dpi), may be provided. In addition, the discharge device 121 may be provided with both the discharge head for low resolution and the discharge head for high resolution. In addition, dpi means “dot per inch”.

[00199] Between each of the discharge heads 122Y, 122M, 122C, and 122K, infrared laser irradiating devices 128A, 128B, and 128C are respectively provided as the drying units. In addition, on the downstream side in the paper transport direction of the discharge head 122K, an infrared laser irradiating device may further be provided.

[00200] In the discharge device 121, on the downstream side in the paper transport direction with respect to the discharge heads 122Y, 122M, 122C, and

122K, for example, a drying drum 126 (an example of a drying device) around which a rear surface of the continuous form paper P is wound, and which dries the image (ink) on the continuous form paper P while being in contact with the transported continuous form paper P and being rotated to be driven.

[00201] On the inside of the drying drum 126, a heat source (for example, a halogen heater or the like, not illustrated) is embedded. The drying drum 126 dries the image (aqueous ink) on the continuous form paper P by heating performed by the heat source.

[00202] A warm air blowing device 128 (an example of a drying device) which dries the image (ink) on the continuous form paper P is disposed around the drying drum

126. The image (ink) on the continuous form paper P wound around the drying drum 126 is dried by the warm air generated by the warm air blowing device 128.

[00203] Meanwhile, the preprocessing unit 14 includes a supply roller 14B around which the continuous form paper P supplied to the image recording unit 12 is

2017202189 16 May 2018 wound, and the supply roller 14B is supported to be rotatable by a frame member that is not illustrated.

[00204] In the buffer unit 16, for example, a first pass roller 16A, a dancer roller

16B, and a second pass roller 16C are disposed along the paper transport direction.

The dancer roller 16B adjusts tension of the continuous form paper P transported to the image recording unit 12 and adjusts the transport amount of the continuous form paper P by moving vertically in Fig. 1.

[00205] The postprocessing unit 18 includes a winding roll 18A as an example of a transport portion which winds the continuous form paper P on which the image is recorded. As the winding roll 18A rotates receiving a rotational force from a motor which is not illustrated, the continuous form paper P is transported along the transport path 124.

[00206] In the buffer unit 20, for example, a first pass roller 20A, a dancer roller

20B, and a second pass roller 20C are disposed along the paper transport direction.

The dancer roller 20B adjusts the tension of the continuous form paper P output to the postprocessing unit 18 and adjusts the transport amount of the continuous form paper P by moving vertically in Fig. 1.

[00207] In the cooling unit 22, plural cleaning rollers 22A are disposed. The continuous form paper P is cooled by transporting the continuous form paper P between the plural cleaning rollers 22A.

[00208] Next, an operation (recording device) by the inkjet recording device 10 according to the exemplary embodiment will be described.

[00209] In the inkjet recording device 10 according to the exemplary embodiment, first, the continuous form paper P is transported to the image recording unit 12 through the buffer unit 16 from the supply roller 14B of the preprocessing unit 14.

2017202189 16 May 2018 [00210] Next, in the image recording unit 12, the ink is discharged onto the recording medium from each of the discharge heads 122Y, 122M, 122C, and 122K of the discharge device 121. Accordingly, the image is formed by the aqueous ink on the continuous form paper P. The ink discharqed by the discharqe head 122Y is irradiated with the infrared liqht by the infrared laser irradiatinq device 128A, and at least a part of the solvent, such as water, is volatilized. In addition, the ink discharqed by the discharqe head 122M is irradiated with the infrared liqht by the infrared laser irradiatinq device 128B, and at least a part of the solvent, such as water, is volatilized. Furthermore, the ink discharqed by the discharqe head 122C is irradiated with the infrared liqht by the infrared laser irradiatinq device 128C, at least a part of the solvent, such as water, is volatilized. In addition, the ink discharqed by the discharqe head 122K may be irradiated with the infrared liqht by the infrared laser irradiatinq device, and in this case, at least a part of the solvent, such as water, of the ink discharqed by the discharqe head 122K is volatilized. After this, the imaqe (aqueous ink) on the continuous form paper P is dried from the rear surface side (surface on a side opposite to a recordinq surface) of the continuous form paper P is dried by the dryinq drum 126. In addition, the aqueous ink (imaqe) discharqed to the continuous form paper P is dried from the front surface side (recordinq surface) of the continuous form paper P by the warm air blowinq device

128. In other words, the ink discharqed onto the continuous form paper P is dried by the dryinq drum 126 and the warm air blowinq device 128. The warm air blowinq device 128 may not be provided, but there is also an effect of removinq the evaporated moisture.

[00211] Next, in the coolinq unit 22, the continuous form paper P on which the imaqe is recorded is cooled by the cleaninq roller 22A.

2017202189 16 May 2018 [00212] Next, the postprocessing unit 18 winds the continuous form paper P on which the image is recorded by the winding roll 18A through the buffer unit 16.

[00213] The image is recorded by the aqueous ink on the continuous form paper P which is the recording medium P according to the above-described means.

[00214] In addition, in the ink jet recording device 10, a type which directly discharges the droplets of the ink to the front surface of the recording medium P by the discharge device 121 is described, but the invention is not limited thereto, and for example, a type which transfers the droplets of the ink on the intermediate transfer member to the recording medium P after the droplets of the ink are discharged to an intermediate transfer member, may be employed.

[00215] In addition, in the inkjet recording device 10, a type which records the image by discharging the ink to the continuous form paper P which is the recording medium P is described, but a type which records the image by discharging the ink to a paper sheet which is the recording medium P, may be employed.

[00216] The above-described exemplary embodiment is not interpreted to a limited extent only to the aspect, and it is needless to say that the exemplary embodiment is realized within a range that satisfies the conditions of the invention. For example, the drying may be performed by an infrared lamp instead of the drying drum 126 and the warm air blowing device 128.

[Examples] [00217] The invention will be described in more detail using the examples hereinafter, but the invention is not limited to the examples. In addition, unless otherwise noted, “part” indicates “part by weight”, and “%” indicates “% by weight”.

(Example 1)

Preparation of Cyan Ink 2>

2017202189 16 May 2018 [00218] Pigment Blue 15:4 (cyan pigment, manufactured by DIC Corporation):

4.0% by weight [00219] Styrene-acrylate copolymer (pigment dispersing agent, manufactured by

BASF): 0.4% by weight [00220] Propylene glycol (manufactured by Wako Pure chemical Industries, Ltd.):

10% by weight [00221] Diethylene glycol monoisopropyl ether: 5% by weight [00222] 1,2-hexanediol (manufactured by Wako Pure chemical Industries, Ltd.):

% by weight [00223] Polyacrylate emulsion (25% of solid content, manufactured by Nippon

Synthetic Chemical Industries Co., Ltd.): 4% by weight [00224] Infrared absorbent dispersing element (here, 2% by weight of squarylium component, 18% by weight of styrene/ethyl methacrylate/acrylic acid-2-carboxyethyl copolymer (30/60/10), and 80% by weight of aqueous solvent): 5% by weight [00225] Olfine E1010 (surfactant, manufactured by Nissin Chemical Industry Co.,

Ltd.): 0.5% by weight [00226] Olfine E1004 (surfactant, manufactured by Nissin Chemical Industry Co.,

Ltd.): 0.5% by weight [00227] Pure water: 69.6% by weight [00228] After mixing the above-described components with each other, filtration is performed by a filter having a size of 5 μίτι, and cyan ink 2 is obtained.

Preparation of Magenta Ink 2>

[00229] Pigment Red 122 (magenta pigment, manufactured by DIC Corporation):

6.0% by weight

2017202189 16 May 2018 [00230] Styrene-acrylate copolymer (pigment dispersing agent, manufactured by

BASF): 0.6% by weight [00231] Propylene glycol (manufactured by Wako Pure chemical Industries, Ltd.):

10% by weight [00232] Diethylene glycol monoisopropyl ether: 5% by weight [00233] 1,2-hexanediol (manufactured by Wako Pure chemical Industries, Ltd.):

% by weight [00234] Polyacrylate emulsion (25% of solid content, manufactured by Nippon

Synthetic Chemical Industries Co., Ltd.): 4% by weight [00235] Infrared absorbent dispersing element (here, 2% by weight of squarylium component, 18% by weight of styrene/ethyl methacrylate/acrylic acid-2-carboxyethyl copolymer (30/60/10), and 80% by weight of aqueous solvent): 4% by weight [00236] Olfine E1010 (surfactant, manufactured by Nissin Chemical Industry Co.,

Ltd.): 0.6% by weight [00237] Olfine E1004 (surfactant, manufactured by Nissin Chemical Industry Co.,

Ltd.): 0.4% by weight [00238] Pure water: 68.4% by weight

Preparation of Yellow Ink 2>

[00239] Yellow ink 2 is obtained in a manner similar to preparation of the cyan ink except that Pigment Yellow 74 (yellow pigment, manufactured by DIC Corporation) is used instead of Pigment Blue 15:4 as a coloring agent.

Preparation of Black Ink 2>

[00240] Carbon black (carbon black pigment, manufactured by Cabot Corporation):

5.3% by weight

2017202189 16 May 2018 [00241] Styrene-methacrylate copolymer (pigment dispersing agent, manufactured by BASF): 0.53% by weight [00242] Propylene glycol: 15% by weight [00243] Diethylene glycol monoisopropyl ether: 4% by weight [00244] 1,2-hexanediol: 1.5% by weight [00245] Polyacrylate emulsion (25% of solid content, manufactured by Nippon

Synthetic Chemical Industries Co., Ltd.): 5% by weight [00246] Olfine E1010 (surfactant, manufactured by Nissin Chemical Industry Co.,

Ltd.): 0.6% by weight [00247] Olfine E1004 (surfactant, manufactured by Nissin Chemical Industry Co.,

Ltd.): 0.4% by weight [00248] Pure water: 67.67% by weight <Calculation Method of above-described Expression (1) which is Approximation in which Evaporation Rate of Ink is 0% to 60%>

[00249] By using RHEOMETER HAAKE MARS (manufactured by Thermo Fisher

Scientific), the viscosity of each ink is measured at 30°C at five points including 0%, approximately 15%, approximately 30%, approximately 45%, approximately 60% and 60% or lower of the evaporation rate of the ink. The values of coefficient a and y-intercept b in the expression (1) in each ink are calculated by regression using a least-squares method and the measured values at the five points.

[00250] In the cyan ink 2, the value of the coefficient a is 1.2 and the value of the y-intercept b is 4.55. The viscosity (0% of evaporation rate) of the cyan ink 2 at

30°C is 5.7 mPa-s.

2017202189 16 May 2018 [00251] In the magenta ink 2, the value of the coefficient a is 1.27 and the value of the y-intercept b is 4.23. The viscosity (0% of evaporation rate) of the magenta ink at 30°C is 5.5 mPa-s.

[00252] In the yellow ink 2, the value of the coefficient a is 1.15 and the value of the y-intercept b is 4.45. The viscosity (0% of evaporation rate) of the yellow ink 2 at 30°C is 5.6 mPa-s.

[00253] In the black ink 2, the value of the coefficient a is 1.16 and the value of the y-intercept b is 4.54. The viscosity (0% of evaporation rate) of the black ink 2 at

30°C is 5.7 mPa s.

Preparation of Cyan Ink 1, 3, and 4>

[00254] In the cyan ink 1, the amounts of the polyacrylate emulsion and the pure water are increased and the amount of the propylene glycol is decreased with respect to the cyan ink 2 such that a becomes approximately a target value illustrated in Table 1. In the cyan ink 3, the amount of the polyacrylate emulsion is decreased and the amounts of the propylene glycol and the pure water are increased with respect to the cyan ink 2 such that a becomes approximately a target value illustrated in Table 1. In the cyan ink 4, the amount of the polyacrylate emulsion is decreased and the amounts of the pure water, the propylene glycol, and the 1,2-hexanediol are increased with respect to the cyan ink 2 such that a becomes approximately a target value illustrated in Table 1.

[00255] In addition, the viscosity (0% of evaporation rate) of the cyan ink 1 at 30°C is 5.8 mPa s.

[00256] The viscosity (0% of evaporation rate) of the cyan ink 3 at 30°C is 5.7 mPa-s.

2017202189 16 May 2018 [00257] The viscosity (0% of evaporation rate) of the cyan ink 4 at 30°C is 5.4 mPa-s.

Preparation of Magenta Ink 1,3, and 4>

[00258] In the magenta ink 1, the amounts of the polyacrylate emulsion and the pure water are increased and the amount of the propylene glycol is decreased with respect to the magenta ink 2 such that a becomes approximately a target value illustrated in Table 1. In the magenta ink 3, the amount of the polyacrylate emulsion is decreased and the amounts of the propylene glycol and the pure water are increased with respect to the magenta ink 2 such that a becomes approximately a target value illustrated in Table 1. In the magenta ink 4, the amount of the polyacrylate emulsion is decreased and the amounts of the pure water, the propylene glycol, and the 1,2-hexanediol are increased with respect to the magenta ink 2 such that a becomes approximately a target value illustrated in Table 1.

[00259] In addition, the viscosity (0% of evaporation rate) of the magenta ink 1 at

30°C is 5.6 mPa-s.

[00260] The viscosity (0% of evaporation rate) of the magenta ink 3 at 30°C is 5.5 mPa-s.

[00261] The viscosity (0% of evaporation rate) of the magenta ink 4 at 30 °C is 5.2 mPa-s.

Preparation of Yellow Ink 1, 3, and 4>

[00262] In the yellow ink 1, the amounts of the polyacrylate emulsion and the pure water are increased and the amount of the propylene glycol is decreased with respect to the yellow ink 2 such that a becomes approximately a target value illustrated in Table 1. In the yellow ink 3, the amount of the polyacrylate emulsion is decreased and the amounts of the propylene glycol and the pure water are

2017202189 16 May 2018 increased with respect to the yellow ink 2 such that a becomes approximately a target value illustrated in Table 1. In the yellow ink 4, the amount of the polyacrylate emulsion is decreased and the amounts of the pure water, the propylene glycol, and the 1,2-hexanediol are increased with respect to the yellow ink 2 such that a becomes approximately a target value illustrated in Table 1.

[00263] In addition, the viscosity (0% of evaporation rate) of the yellow ink 1 at

30°C is 5.5 mPa-s.

[00264] The viscosity (0% of evaporation rate) of the yellow ink 3 at 30 °C is 5.3 mPas.

[00265] The viscosity (0% of evaporation rate) of the yellow ink 4 at 30 °C is 5.4 mPas.

«Preparation of Black Ink 1,3, and 4>

[00266] In the black ink 1, the amounts of the polyacrylate emulsion and the pure water are increased and the amount of the propylene glycol is decreased with respect to the black ink 2 such that a becomes approximately a target value illustrated in Table 1. In the black ink 3, the amount of the polyacrylate emulsion is decreased and the amounts of the propylene glycol and the pure water are increased with respect to the black ink 2 such that a becomes approximately a target value illustrated in Table 1. In the black ink 4, the amount of the polyacrylate emulsion is decreased and the amounts of the pure water, the propylene glycol, and the 1,2-hexanediol are increased with respect to the black ink 2 such that a becomes approximately a target value illustrated in Table 1.

[00267] In addition, the viscosity (0% of evaporation rate) of the black ink 1 at 30°C is 5.8 mPa-s.

2017202189 16 May 2018 [00268] The viscosity (0% of evaporation rate) of the black ink 3 at 30°C is 5.7 mPas.

[00269] The viscosity (0% of evaporation rate) of the black ink 4 at 30°C is 5.5 mPas.

[00270] The values of coefficient a and y-intercept b in the expression (1) in each ink are calculated by the above-described Calculation Method. The calculated values of a and b are described in Table 1.

[1	fable T
Target value of a	Ink No.	Value of a	Value of b
C	M	Y	K	C	M	Y	K
3.6	1	3.3	3.7	3.5	4.0	2.5	1.9	1.9	1.8
1.2	2	1.2	1.3	1.2	1.2	4.6	4.2	4.5	4.5
0.73	3	0.72	0.76	0.69	0.74	5.0	4.7	4.6	4.9
0.36	4	0.33	0.34	0.35	0.40	5.1	4.9	5.1	5.1

[00271] In Table 1, “C” indicates cyan ink, “M” indicates magenta ink, “Y” indicates yellow ink, and “K” indicates black ink. Hereinafter, the indications are the same.

[00272] The light absorptivity of the ink is measured by the following method.

[00273] Absorbance A0 in a laser wavelength of the ink diluted by pure water is measured using ultraviolet visible near-infrared spectrophotometer V-560 (manufactured by JASCO Corporation) and a 10x10 mm square shaped quartz cell and absorptivity in the ink film thickness printed onto a recording medium is calculated from a conversion expression based on Lambert-Beer law. In other words, the absorbance A0 of a solution into which 1 g of ink weight Wh and 200 g of pure water Wwater are mixed is measured, and the absorptivity % A1 = 1-10' ((wink/wwater)x(d/io)xAO) _of fi|_m thickness d = 5 x 10³ mm is calculated.

[00274] Any light absorptivity of the cyan, magenta, and yellow ink 1 to 4 is 0.7 and the light absorptivity of the black ink 1 to 4 is 0.8.

2017202189 16 May 2018 [00275] In addition, the light absorptivity is adjusted by changing a ratio of the infrared absorbent and a dispersing resin which are included in the infrared absorbent dispersion.

[00276] By preparing an inkjet recording system which is illustrated in Fig. 1 and includes a piezo type ink jet head (1,200 x 1,200 dpi of resolution, 5 pL of maximum ink droplet), and the infrared laser and the heating roller which are drying devices, each color of ink (cyan ink, magenta ink, yellow ink, and black ink) described in

Table 2 are charged. The transport speed of the recording medium is set to be 50 m/min.

[00277] As the recording medium, OK top coat + paper (manufactured by Oji Paper

Co, Ltd.) is prepared.

[00278] A recorded image is obtained by discharging each color of ink from the ink jet head onto the recording medium, and by drying the ink by the infrared laser and the heating roller.

As a recorded image, an image that corresponds to each evaluation which will be described later is formed.

[Inter-Color Blur] [00279] In the above-described image forming method, by overlapping a patch having 100% of a monochromatic printing rate and a patch having 100% of a secondary color printing rate, and by using a chart that draws eight monochromatic dot lines, the drying is performed by the ink jet discharge, the infrared laser or the like, and the recorded image is obtained. A value of raggedness (the size of disturbance of a line edge portion) of eight dot lines in the obtained recorded image

2017202189 16 May 2018 is measured by PIASII (manufactured by Quality Engineering Associate, Inc.), and is evaluated according to the following standard.

[00280] A: Any raggedness value is less than 15 pm [00281] B: There are seen locations at which the raggedness value is equal to or greater than 15 pm and less than 30 pm, but any raggedness value is less than 30 pm.

[00282] C: There are seen locations at which the raggedness value is equal to or greater than 30 pm.

[00283] The printing order of the ink which are described in Table 2. Infrared irradiation energy is set to be 3.08 J/cm² with respect to the first color, 1.05 J/cm²with respect to the second color, 0.57 J/cm² with respect to the third color, and 0.65 J/cm² with respect to the fourth color. The evaluation result is illustrated in Table 2. [Problem due to High Temperature (High Temperature Problem (Deterioration of

Image Density and Blister))] [00284] In the above-described image forming method, the ink jet discharge which draws the patch having 100% of monochromatic printing rate is performed, the drying is performed by the infrared laser and the heating roller, and the recorded image for evaluation is obtained. By using X-Rite 504 (manufactured by X-Rite

Inc.), optical density (OD) of the recorded image for evaluation is measured, and further, by using a loupe having 10 times of magnification, the recorded image for evaluation is visually observed, and the presence or absence of blister (bulging) on the recorded image is confirmed.

[00285] In addition, another recorded image for comparison is obtained in a manner similar to the method described above except that natural drying is performed instead of drying using the above-described infrared laser and the

2017202189 16 May 2018 heating roller, and the optical density of the recorded image for comparison is measured. Then the difference between the optical density of the recorded image for evaluation and optical density of the recorded image for comparison (AOD) is calculated.

[00286] The evaluation standard is as follows.

[00287] A: AOD, which means deterioration of optical density compared to the natural drying, is 0.3 or less (AOD < 0.3), and the blister is not confirmed.

[00288] B: AOD > 0.3, and the blister is not confirmed.

[00289] C: AOD > 0.3, and the blister is confirmed.

[00290] The evaluation result is illustrated in Table 2.

[Discharge Stability] [00291] By using Material Printer DMP2891 manufactured by FUJIFILM Dimatix,

Inc., consecutive dots for reference and consecutive dots for evaluation are printed using each ink. The consecutive dots for reference are discharged via inkjet at intervals of 0.0015 seconds.

[00292] Consecutive dots for evaluation are printed in a manner similar to the consecutive dots for reference, except that a number of the dots corresponding to down time are thinned out (consecutive dots are not printed during the down time, and another consecutive dots are printed again after the down time). The down time for evaluation is set to be 0.8 seconds.

[00293] An initial dot for evaluation after the down time is enlarged and observed by an optical microscope, and a landing position shift amount of the initial dot (difference between the initial dot position and a reference dot position in the printing direction) is measured.

[00294] The evaluation standard is as follows.

2017202189 16 May 2018 [00295] A: The landing position shift amount is less than 10 μίτι in any ink used.

[00296] B: The landing position shift amount is equal to or greater than 10 μιη and less than 20 μίτι at least in one ink used, and the landing position shift amount is less than 20 μίτι in any ink used.

[00297] C: The landing position shift amount is equal to or greater than 20 μίτι at least in one ink used.

[00298] The evaluation result is illustrated in Table 2.

[Table 2]

	Ink used No.	Inter- color blur	High tempera ture problem	Discharge stability
First	Second	Third	Fourth
Y	M	C	K
Comparative Example 1	1	1	1	1	C	A	C
Comparative Example 2	2	2	2	2	C	A	B
Comparative Example 3	3	3	3	3	c	B	A
Comparative Example 4	4	4	4	4	c	B	A
Example 1	3	3	2	3	A	A	A
Example 2	4	3	2	3	A	A	A

[00299] In a configuration in which the printing order and the ink which are described in Table 3 are employed, when infrared irradiation energy is set to be 1.59 J/cm² with respect to the first color, 1.31 J/cm² with respect to the second color, 0.88 J/cm² with respect to the third color, and 0.77 J/cm² with respect to the fourth color, the following result is obtained. The evaluation result is illustrated in Table 3.

2017202189 16 May 2018 [Table 3]

	Ink used No.	Inter-color blur	High temperature problem	Discharge stability
First	Second	Third	Fourth
C	M	Y	K
Comparative Example 5	1	1	1	1	C	A	C
Comparative Example 6	2	2	2	2	C	A	B
Comparative Example 7	3	3	3	3	C	C	A
Comparative Example 8	4	4	4	4	C	C	A
Example 3	2	3	3	3	A	A	A
Example 4	2	3	3	4	A	A	A
Example 5	2	3	4	3	A	A	A

2017202189 16 May 2018

Claims

1. An ink jet ink set comprising:

a first ink that contains an infrared absorbent and water; and a second ink that contains an infrared absorbent and water, a value of coefficient a of the following expression (1) in the second ink being different from that of the first ink 1.5 times or greater, the expression (1) being a relational expression between viscosity and an evaporation rate of each ink

Expression (1): y = a * exp(10x) + b in which ‘x’ is a weight evaporation rate in the ink and expresses a value which is from 0 to 0.6, ‘y’ expresses viscosity (mPa-s) ofthe ink at 30°C, ‘a’ is a coefficient indicating an increase trend in viscosity that corresponds to the evaporation rate in the ink and ‘b’ expresses a y-intercept.

2. The ink jet ink set according to claim 1, wherein the viscosities at 30°C of all of the inks included in the ink jet ink set are from 4 mPas to10 mPa-s.

3. The ink jet ink set according to claim 1 or 2, wherein each of the first ink and the second ink further contain an organic solvent.

4. An ink cartridge set comprising:

2017202189 16 May 2018 a first ink cartridge that stores the first ink of the ink jet ink set according to any one of claims 1 to 3 therein; and a second ink cartridge that stores the second ink of the ink jet ink set therein

5. An ink jet recording device which houses the ink jet ink set according to any one of claims 1 to 3 therein, comprising:

a first discharge head that discharges the first ink onto a recording medium;

a second discharge head that discharges the second ink onto the recording medium; and an infrared irradiating unit that dries at least one of the first ink and the second ink which are discharged onto the recording medium.

6. An ink jet recording device which houses the ink jet ink set according to any one of claims 1 to 3 therein, comprising:

a first discharge head that discharges the first ink onto a recording medium;

a second discharge head that discharges the second ink onto the recording medium;

a first infrared irradiating unit that dries the first ink discharged onto the recording medium; and a second infrared irradiating unit that dries the second ink discharged onto the recording medium.

7. An inkjet recording method comprising:

a process of discharging the first ink in the ink jet ink set according to any one of claims 1 to 3 onto a recording medium;

2017202189 16 May 2018 a process of discharging the second ink in the ink jet ink set onto the recording medium; and a process of drying at least one of the first ink and the second ink which are discharged onto the recording medium by irradiating infrared light.

1/1

I

2017202189 03 Apr 2017

< /1 CN CN r> < -CN kJ kJ CN

CN

FIG. 1