JP2015209535A - Ink set and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set which enables recording of an image excellent in color development and suppresses occurrence of contamination inside a recording apparatus or on a recording medium even when borderless recording is conducted.SOLUTION: An ink set has a deep ink, a light ink and a clear ink. The deep ink contains a water-soluble organic solvent of a relative dielectric constant of 9.0 or higher and lower than 28.5, and the ratio of the content of the water-soluble organic solvent of a relative dielectric constant of 9.0 or higher and lower than 28.5 to the total content of all the water-soluble organic solvents in the deep ink is 50.0 mass% or higher. The clear ink contains a water-soluble organic solvent of a relative dielectric constant of 28.5 or higher and lower than 70.0, and the ratio of the content of the water-soluble organic solvent of a relative dielectric constant of 28.5 or higher and lower than 70.0 to the total content of all the water-soluble organic solvents in the clear ink is 50.0 mass% or higher.

Description

  The present invention relates to an ink set and an ink jet recording method.

  In recent years, in an ink jet recording method, pigment ink containing a pigment as a color material has been widely used in order to improve fastness such as light resistance of a recorded image. The dye ink is characterized in that the dye, which is a coloring material, is dissolved in a liquid medium in a molecular state, whereas the pigment ink is characterized in that the pigment, which is a coloring material, is dispersed in the liquid medium in the form of particles. . Due to this feature, there is a problem that an image recorded with pigment ink is inferior in gloss as compared with an image recorded with dye ink. Further, there is a problem that a difference in glossiness (gloss unevenness) becomes remarkable between the area where the pigment ink is applied and the area where the pigment ink is not applied on the recording medium. In order to reduce this uneven glossiness, there is a proposal for applying a clear ink containing resin fine particles and not containing a color material in a region where no ink containing a color material is applied (see Patent Document 1).

  On the other hand, in the ink jet recording method, by applying ink to a region slightly larger than the size of the recording medium, an image is recorded over the entire surface of the recording medium, and no margin is generated at the edge of the recording medium (edgeless). Recording). When performing borderless recording, an ink absorbing member that absorbs ink ejected to the outside of the recording medium is provided with a predetermined amount so that the ink ejected to the outside of the recording medium does not contaminate the inside of the recording apparatus or the recording medium. Place in place. A sponge-like member is used as the ink absorbing member.

  Since the pigment ink is in the form of particles, the pigment ink has lower permeability to the ink absorbing member than the dye ink. For this reason, in an ink jet recording apparatus equipped with pigment ink, when the pigment deposited on the surface of the ink absorbing member stains the back surface of the recording medium, or when the amount of pigment deposits increases, it contacts the ejection port surface of the recording head. The recorded image may be affected. In order to suppress this accumulation, among a plurality of inks constituting the ink set, an ink containing more humectant is applied to an adjacent portion of the region of the ink absorbing member to which the ink has been previously applied, There is a proposal about dissolving a deposit (refer to patent documents 2).

JP 2007-291399 A JP 2006-103310 A

  The present inventors have studied a technique using a clear ink as described in Patent Document 1 in order to improve the glossiness of an image, and applied the technique of Patent Document 2 to this clear ink to form an ink absorbing member. I tried to use it to suppress the accumulation of water. Then, although the deposition was certainly improved, it was found that the amount of ink used increased where there was nothing to do with the original use and was wasted. In addition, by applying the technique described in Patent Document 1, an attempt was made to add a large amount of moisturizing agent to each ink constituting the ink set. In this case as well, the deposition was certainly improved, but the permeability of the ink to the recording medium also increased, and it was found that another problem arises that the color developability of the image decreases in the recording medium such as plain paper. It was.

  Accordingly, an object of the present invention is to provide an ink set that can record an image with excellent color developability and that suppresses the occurrence of stains in the recording apparatus and the recording medium even when borderless recording is performed. Is to provide. Another object of the present invention is to provide an ink jet recording method using the ink set.

  The above object is achieved by the present invention described below. That is, the ink set according to the present invention is an ink jet ink set having a dark ink having a relatively large pigment content, a light ink having a relatively small pigment content, and a clear ink not containing a coloring material. The dark ink contains a water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5, and occupies a total content of all the water-soluble organic solvents in the dark ink. The ratio of the content of the water-soluble organic solvent having a dielectric constant of 9.0 or more and less than 28.5 is 50.0% by mass or more, and the clear ink has a relative dielectric constant of 28.5 or more and less than 70.0. Containing a water-soluble organic solvent containing a water-soluble organic solvent and occupying the total content of all water-soluble organic solvents in the clear ink and having a relative dielectric constant of 28.5 or more and less than 70.0 The proportion of the amount is 50.0% by mass Characterized in that it is a top.

  According to the present invention, there is provided an ink set capable of recording an image having excellent color developability and suppressing the occurrence of stains in the recording apparatus and the recording medium even when borderless recording is performed. can do. According to another embodiment of the present invention, an ink jet recording method using the ink set can be provided.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. Hereinafter, the ink set for inkjet is simply referred to as “ink set”.

  First, the inventors examined a technique for suppressing deposition on the ink absorbing member. In order to suppress deposition on the ink absorbing member, it is necessary to delay solid-liquid separation between the pigment and the liquid component in the ink after the ink is applied to the ink absorbing member. That is, by delaying solid-liquid separation, the pigment can be prevented from penetrating into the ink absorbing member together with the liquid component and being deposited on the surface thereof. On the contrary, when the solid-liquid separation is fast, only the liquid component in the ink penetrates into the ink absorbing member, and the pigment is likely to be deposited on the surface of the ink absorbing member.

  Therefore, an ink composition for suppressing solid-liquid separation was examined. As a result, it was found that solid-liquid separation can be delayed by containing a large amount of a water-soluble organic solvent having a high relative dielectric constant in the ink, and deposition on the ink absorbing member is suppressed. The reason is presumed as follows. Since the pigment is inherently hydrophobic, a hydrophilic functional group is bonded to the surface of the pigment particle or a resin dispersant is used for dispersion in the liquid medium. In either case, the surface of the pigment particles is in a state having high affinity with the liquid medium, that is, in a state of high polarity, and therefore has high affinity with a water-soluble organic solvent having a high relative dielectric constant. Therefore, it is considered that the ink containing a large amount of the water-soluble organic solvent having a high relative dielectric constant is difficult to cause solid-liquid separation, and the pigment penetrates into the ink absorbing member, thereby suppressing the deposition.

  Next, the present inventors examined a technique for improving the color developability of an image. In order to improve color developability, it is necessary to make more pigments exist on the surface of the recording medium. For this purpose, it is necessary to promote solid-liquid separation between the pigment and the liquid component in the ink after the ink is applied to the recording medium. Contrary to the above-described suppression of deposition, in order to improve the color development of the image, it is necessary to contain a large amount of a water-soluble organic solvent having a low relative dielectric constant in the ink.

  In other words, in order to suppress deposition on the ink absorbing member, it is necessary to contain a large amount of a water-soluble organic solvent having a high relative dielectric constant. On the other hand, in order to improve the color developability of the image, the water solubility is low. It is necessary to contain a large amount of organic solvent. From this, it was found that it is difficult to achieve both suppression of deposition and improvement of color developability with one ink. Therefore, the present inventors do not make these performances compatible with one ink, but separate the ink that suppresses deposition from the ink that improves color development, that is, it is only necessary to satisfy the above problems as an ink set. As a result, various studies were made and the present invention was completed. The ink set of the present invention includes a dark ink having a relatively large pigment content, a light ink having a relatively small pigment content, and a clear ink not containing a color material. Hereinafter, the requirements for each ink will be described.

  First, it is necessary to contain a large amount of a water-soluble organic solvent having a low relative dielectric constant in a dark ink that is required to improve the color developability of an image. As a result of the study by the present inventors, the ratio of the content of the water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5 to the total content of all the water-soluble organic solvents in the dark ink is 50. It was found that the color developability of the image is sufficiently enhanced when the content is 0.0 mass% or more. However, in this case, although the color developability is excellent, it is impossible to suppress accumulation as dark ink for the above-described reason. Therefore, as a result of studies for suppressing the accumulation of dark ink, a configuration has been achieved in which clear ink having no coloring material has the function.

  The clear ink is used for complementing a plurality of dots formed on the recording medium with pigment ink, or for reducing uneven glossiness of the entire image. Accordingly, the dots are formed so as to overlap the dots formed by the pigment ink. For this reason, when performing borderless recording, the ink absorbing member is in a state where the pigment ink and the clear ink are sufficiently mixed. The inventors of the present invention have considered that it is possible to achieve both color development and deposition suppression by providing the clear ink with a function of suppressing the deposition of pigment ink.

  In order to suppress the deposition of the pigment ink, it is necessary that the clear ink contains a large amount of a water-soluble organic solvent having a high relative dielectric constant. As a result of the study by the present inventors, the ratio of the content of the water-soluble organic solvent having a relative dielectric constant of 28.5 or more and less than 70.0 to the total content of all the water-soluble organic solvents in the clear ink is 50. It was found that the pigment ink deposition can be suppressed when the content is 0.0 mass% or more. That is, even if a pigment ink containing a large amount of a water-soluble organic solvent having a low relative dielectric constant is used to improve color development, the clear ink containing a large amount of a water-soluble organic solvent having a high relative dielectric constant is used in the ink absorbing member. What is necessary is just to mix. As a result, solid-liquid separation of the pigment derived from the pigment ink and the liquid component can be delayed, and deposition can be suppressed. In addition, when the clear ink contains a resin, an incidental effect that gloss uniformity is improved can be obtained. That is, since the clear ink contains a large amount of a water-soluble organic solvent having a high relative dielectric constant, solid-liquid separation of the resin and the liquid component is delayed, so that the recording medium is leveled by the resin.

  Since dark ink is mainly used for recording an image with high color developability, in the present invention, not a light ink but a dark ink that contains a large amount of a water-soluble organic solvent having a low relative dielectric constant. I have to. Therefore, a water-soluble organic solvent in the light ink may have any specific dielectric constant.

<Ink set>
Hereinafter, the components of the dark ink, the light ink, and the clear ink constituting the ink set of the present invention and the physical properties of each ink will be described in detail.

(Water-soluble organic solvent)
The relative dielectric constant of the water-soluble organic solvent can be measured with a general dielectric constant meter. In Examples described later, the relative permittivity of a water-soluble organic solvent was measured using a relative permittivity meter (trade name “BI-870”, manufactured by Brookhaven) at a temperature of 20 ° C. and a frequency of 10 kHz.

  The dark ink contains a water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5. The ratio of the water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5 to the total content of the water-soluble organic solvent in the dark ink is required to be 50.0% or more. When the ratio is less than 50.0%, the color developability of the image becomes insufficient. Note that all water-soluble organic solvents in the dark ink may be water-soluble organic solvents having a relative dielectric constant of 9.0 or more and less than 28.5.

  Examples of the water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5 include 1,2-propanediol (30.1), 2-pyrrolidone (28.0), and 1,2,6-hexane. Examples include triol (27.5), 1,5-pentanediol (27.0), 1,2-hexanediol (14.8), triethylene glycol monobutyl ether (9.8), and the like. Of these, 2-pyrrolidone, 1,5-pentanediol, and 1,2-hexanediol are preferable. These water-soluble organic solvents are suitable for dark inks that are required to improve the color development of recorded images.

  The clear ink contains a water-soluble organic solvent having a relative dielectric constant of 28.5 or more and less than 70.0. And the ratio of the water-soluble organic solvent whose relative dielectric constant is 28.5 or more and less than 70.0 in the total content of the water-soluble organic solvent in the clear ink is required to be 50.0% or more. If the ratio is less than 50.0%, the effect of suppressing deposition on the ink absorbing member cannot be obtained. Note that all water-soluble organic solvents in the clear ink may be water-soluble organic solvents having a relative dielectric constant of 28.5 or more and less than 70.0.

  Examples of the water-soluble organic solvent having a relative dielectric constant of 28.5 or more and less than 70.0 include glycerin (42.3), ethylene glycol (40.4), diethylene glycol (32.5), and 1,2-propanediol. (30.1). Of these, glycerin, ethylene glycol, and 1,2-propanediol are preferable. When these water-soluble organic solvents are contained in the clear ink, the effect of suppressing deposition on the ink absorbing member is excellent.

  On the other hand, any water-soluble organic solvent contained in the light ink may be selected regardless of the relative dielectric constant.

(Pigment)
The dark ink and light ink constituting the ink set, Ru is contained pigment as a coloring material. The kind of pigment that can be used in the present invention is not particularly limited, and any known inorganic pigment or organic pigment can be used. Specific examples include inorganic pigments such as calcium carbonate, titanium oxide, and carbon black; organic pigments such as azo, phthalocyanine, and quinacdrine. The content (% by mass) of the pigment in the dark ink is 0.1% by mass or more and 15.0% by mass or less, and further 1.0% by mass or more and 10.0% by mass or less based on the total mass of the ink. It is preferable. The content (% by mass) of the pigment in the light ink is 0.1% by mass or more and 10.0% by mass or less, and further 0.1% by mass or more and 5.0% by mass or less based on the total mass of the ink. It is preferable to use a resin dispersion type pigment (resin dispersion pigment) in which a pigment is dispersed using a resin as a resin dispersant. In addition, a resin-bonded pigment in which an organic group containing a polymer is chemically bonded to the surface of the pigment particle, a microcapsule pigment in which at least a part of the surface of the pigment particle is coated with a resin, or the like can be used. . Of course, these pigments having different dispersion methods may be used in combination.

(Clear ink resin)
The clear ink constituting the ink set preferably contains a water-soluble resin or resin fine particles as a component for controlling the glossiness of the recorded image. In the present invention, a resin that does not form particles whose particle size can be measured when neutralized with an alkali equivalent to its acid value is a “water-soluble resin”, and a resin that forms particles whose particle size can be measured. Is defined as “resin particles”.

  As the resin, those having at least a hydrophilic unit and a hydrophobic unit as listed below as constituent units are preferable. In addition, (meth) acryl in this specification shall show acryl and methacryl.

  Examples of the monomer that becomes a hydrophilic unit by polymerization include, for example, a monomer having a carboxy group such as (meth) acrylic acid, itaconic acid, maleic acid, and fumaric acid, a monomer having a sulfonic acid group such as styrenesulfonic acid, (meth) Examples include acid monomers such as monomers having a phosphonic acid group such as ethyl acrylate-2-phosphonate, and anionic monomers such as anhydrides and salts of these acid monomers. Examples of the cation constituting the salt of the acid monomer include ions such as lithium, sodium, potassium, ammonium, and organic ammonium.

  As a monomer that becomes a hydrophobic unit by polymerization, for example, a monomer having an aromatic ring such as styrene, α-methylstyrene, vinylnaphthalene, benzyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, (Meth) acrylic acid (iso) propyl, (meth) acrylic acid (n-, iso-, t-) butyl, (meth) acrylic acid (meth) acrylic acid esters such as 2-ethylhexyl, etc. Can be mentioned.

  In the present invention, it is preferable to use an acrylic resin having at least an acrylic component such as a hydrophilic unit derived from (meth) acrylic acid or a unit derived from a (meth) acrylic acid ester of an aliphatic alcohol. Furthermore, a copolymer having at least a hydrophilic unit derived from (meth) acrylic acid and a hydrophobic unit derived from a monomer having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth) acrylate is used. It is particularly preferred.

  In the present invention, it is particularly preferable to use resin fine particles among the resins. Among these, acrylic resin fine particles are preferably used because of excellent discharge characteristics as an ink. Further, it is preferable to use resin fine particles synthesized by an emulsion polymerization method or a soap-free polymerization method.

  The resin content (% by mass) in the clear ink is preferably 0.20% by mass or more and 5.0% by mass or less based on the total mass of the ink. When the content is less than 0.20% by mass, the glossiness of the image may not be sufficiently controlled, and when it exceeds 5.0% by mass, the ink ejection characteristics may be slightly deteriorated. .

(Aqueous medium)
Each ink can contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, it is preferable to use deionized water or ion-exchanged water. In the present invention, a water-based ink containing at least water as the aqueous medium is particularly preferable. The content (% by mass) of water in the ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink. The content (% by mass) of the water-soluble organic solvent in the ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. As the water-soluble organic solvent, any of inks that can be used in ink jet inks such as alcohols, (poly) alkylene glycols, glycol ethers, nitrogen-containing compounds can be used, and one or more of them can be used. Can be contained in the ink. As described above, the dark ink and the clear ink need to contain a water-soluble organic solvent having a specific dielectric constant in a predetermined ratio.

(Other ingredients)
In addition to the above components, each ink may contain a water-soluble organic compound that is solid at room temperature, such as urea and its derivatives; trimethylolpropane, trimethylolethane; The content (% by mass) of the water-soluble organic compound that is solid at normal temperature in the ink is 0.1% by mass or more and 20.0% by mass or less, and further 3.0% by mass or more and 10.0% by mass based on the total mass of the ink. It is preferable to set it as mass% or less. In addition, various additives such as antifoaming agents, surfactants, pH adjusters, preservatives, antifungal agents, antioxidants, anti-reducing agents, etc. are used to obtain inks having desired physical property values as necessary. May be included.

<Inkjet recording method>
The ink jet recording method of the present invention is a method of recording an image on a recording medium by ejecting the dark ink, light ink and clear ink constituting the ink set of the present invention described above from an ink jet recording head. Examples of the method for ejecting ink include a method for imparting mechanical energy to the ink and a method for imparting thermal energy to the ink. In the present invention, it is particularly preferable to employ a method in which thermal energy is applied to the ink and the ink is ejected. Other than using the ink of the present invention, the steps of the ink jet recording method may be known.

  Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited by the following Example, unless the summary is exceeded. In the text, “parts” and “%” are based on mass unless otherwise specified.

<Preparation of pigment dispersion>
Each pigment dispersion was prepared by the following procedure. The aqueous solution of the resin dispersant is a resin (solid content) content obtained by neutralizing a styrene acrylic acid copolymer having an acid value of 170 mgKOH / g and a weight average molecular weight of 8,000 with an aqueous sodium hydroxide solution. Is a 10.0% aqueous solution.

(Pigment dispersion 1)
A pigment (CI Pigment Blue 15: 3, trade name “Toner Cyan BG”, manufactured by Clariant) 10.0 parts, an aqueous solution of a resin dispersant 20.0 parts, and ion-exchanged water 70.0 parts are mixed and batch The dispersion was carried out for 3 hours using a vertical sand mill. Further, after removing coarse particles by centrifugal separation, pressure filtration is performed with a cellulose acetate filter (manufactured by Advantech) having a pore size of 3.0 μm, the pigment content is 10.0%, and the resin dispersant Pigment Dispersion Liquid 1 having a content of 2.0% was obtained.

(Pigment dispersion 2)
The pigment is C.I. I. Pigment Red 122 (trade name “Toner Magenta E02”, manufactured by Clariant) was used in the same procedure as Pigment Dispersion Liquid 1, but the pigment content was 10.0% and the resin dispersant content was 2.0. % Pigment dispersion 2 was prepared.

(Pigment dispersion 3)
The pigment content is 10.0% and the resin dispersant content is 2. in the same procedure as Pigment Dispersion Liquid 1 except that the pigment is carbon black (trade name “Black Pearls 880”, manufactured by Cabot). A pigment dispersion 3 of 0% was prepared.

<Preparation of resin fine particles>
After adding 100.0 parts of ethylene glycol monobutyl ether to a four-necked flask equipped with a stirrer, a reflux condenser, and a nitrogen gas inlet tube, nitrogen gas was introduced into the reaction system, and the temperature was increased to 110 ° C. with stirring. The temperature was raised. In this flask, a mixture of 38.0 parts of 2-ethylhexyl acrylate, 34.0 parts of methyl methacrylate and 28.0 parts of acrylic acid, and 1.3 parts of t-butyl peroxide were dissolved in ethylene glycol monobutyl ether. The liquid was dropped over 3 hours. Then, aging was performed for 2 hours, and ethylene glycol monobutyl ether was removed under reduced pressure to obtain a solid resin. The resin thus obtained was neutralized at a temperature of 80 ° C. by adding potassium hydroxide equivalent to its acid value and an appropriate amount of ion-exchanged water, so that the content of shell polymer (solid content) was 30.0. % Aqueous solution of shell polymer was obtained. The acid value of the shell polymer was 216 mgKOH / g, and the weight average molecular weight was 15,000.

  Next, 52.5 parts of the aqueous solution of the shell polymer obtained above was added to a four-necked flask equipped with a stirrer, a reflux cooling device, and a nitrogen gas introduction tube. Thereafter, nitrogen gas was introduced into the reaction system, and the temperature was raised to 80 ° C. with stirring. A mixture of 28.0 parts of styrene and 7.0 parts of ethyl methacrylate was added to the flask, and then a liquid in which 1.0 part of potassium persulfate was dissolved in 16.7 parts of water was added dropwise over 3 hours. And after performing aging for 2 hours, solid content was adjusted with the appropriate amount of ion-exchange water, and the resin fine particle (solid content) content dispersion of the resin fine particle whose content is 10.0% was obtained. The resin fine particles thus obtained had a structure in which a core polymer was coated with a shell polymer.

<Preparation of ink>
After mixing the components shown in the upper part of Table 1 (unit:%) and stirring sufficiently, pressure filtration was performed using a cellulose acetate filter (manufactured by Advantech) having a pore size of 0.8 μm to prepare each ink. . Note that EMALEX 712 (trade name, manufactured by Nippon Emulsion) was used as the surfactant 1, and acetylenol E100 (trade name, manufactured by Kawaken Fine Chemical) was used as the surfactant 2. Each value shown in the lower part of Table 1 is as follows.
・ "Total content of solvent A (%)": Total content of water-soluble organic solvent (%)
・ “Low Dielectric Constant Solvent Content B (%)”: Content of water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5 (%)
-"High C dielectric solvent content C (%)": Water-soluble organic solvent content (%) having a relative dielectric constant of 28.5 or more and less than 70.0

<Evaluation>
A combination of dark ink, light ink, and clear ink shown on the left side of Table 3 was used as an ink set. Then, each of the following evaluations was performed using an ink jet recording apparatus (trade name “PIXUS Pro 9500”, manufactured by Canon Inc.) that discharges ink with thermal energy. In this embodiment, a solid image recorded by applying 8 drops of ink having a mass per drop of 3.5 ng (nanogram) to a unit area of 1/600 inch × 1/600 inch is recorded with a recording duty of 100. It is defined as%. In the present invention, in the evaluation criteria for the following items, A and B are acceptable levels, and C is an unacceptable level. The evaluation results are shown on the right side of Table 3.

(Deposition suppression)
Each ink constituting the ink set was filled in an ink cartridge and mounted on the ink jet recording apparatus. The positions where the dark ink, the light ink, and the clear ink constituting the ink set are mounted are cyan ink, magenta ink, and yellow ink, respectively. A4 size recording with a recording duty of 25% for dark ink, light ink, and clear ink on a recording medium (glossy paper, product name “Canon Photo Paper Glossy Gold GL-101”, manufactured by Canon) A borderless recording was made on the entire surface of the medium. After performing this recording for 500 sheets, the state of the ink absorbing member of the ink jet recording apparatus was visually confirmed, and deposition suppression was evaluated according to the following evaluation criteria.

A: There was no deposit on the ink absorbing member. B: There was a deposit on the ink absorbing member, but the ink was absorbed. C: There was a deposit on the ink absorbing member, and the ink was not absorbed.

(Color development)
The dark ink constituting the ink set was filled in the ink cartridge, and attached to the cyan ink position of the ink jet recording apparatus. Then, a solid image having a recording duty of 100% using only dark ink was recorded on a recording medium (plain paper, product name “PB PAPER”, manufactured by Canon). After the obtained image was naturally dried for 24 hours, the optical density of the solid image was measured using a spectrophotometer (Spectorolino; manufactured by Gretag Macbeth), and the color developability was evaluated according to the evaluation criteria shown in Table 2.

Claims (4)

An inkjet ink set having a dark ink having a relatively large pigment content, a light ink having a relatively small pigment content, and a clear ink not containing a coloring material,
The relative dielectric constant, wherein the dark ink contains a water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5, and occupies a total content of all the water-soluble organic solvents in the dark ink. Is a ratio of the content of the water-soluble organic solvent of 9.0 or more and less than 28.5 is 50.0% by mass or more
The clear ink contains a water-soluble organic solvent having a relative dielectric constant of 28.5 or more and less than 70.0, and occupies a total content of all the water-soluble organic solvents in the clear ink. An ink set, wherein a content ratio of a water-soluble organic solvent having a dielectric constant of 28.5 or more and less than 70.0 is 50.0% by mass or more.   The water-soluble organic solvent having a relative dielectric constant of 9.0 or more and less than 28.5 in the dark ink is at least selected from the group consisting of 2-pyrrolidone, 1,5-pentanediol, and 1,2-hexanediol. The ink set according to claim 1, wherein the ink set is one type.   The water-soluble organic solvent having a relative dielectric constant of 28.5 or more and less than 70.0 in the clear ink is at least one selected from the group consisting of glycerin, ethylene glycol, and 1,2-propanediol. The ink set according to 1. An ink jet recording method in which ink is ejected by an ink jet method and applied to a recording medium,
An ink jet recording method, wherein the ink is each ink constituting the ink set according to any one of claims 1 to 3.