JP2017109485A - Ink set and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording method capable of forming an image obtained by overlap printing of a plurality of inks in which bleeding and cracking are suppressed.SOLUTION: The inkjet recording method of the present invention includes: a step of forming a first ink layer by ejecting a first ink composition comprising water, a water-soluble organic solvent, and a solid content containing at least a coloring material on a recording medium by an inkjet process; a first drying step of evaporating 80% by mass or more of water included in the first ink composition in the first ink layer; a step of forming a second ink layer by ejecting, by an inkjet process, a second ink composition comprising water, a water-soluble organic solvent, and a solid content containing at least a coloring material on the first ink layer subjected to the first drying step; and a second drying step of evaporating a volatile component on the recording medium after the step of forming the second ink layer. When a ratio of (water-soluble organic solvent content)/(solid content) of the first ink composition and a ratio of (water-soluble organic solvent content)/(solid content) of the second ink composition are represented by r1 and r2, respectively, a ratio r2/r1 is 2 or less.SELECTED DRAWING: None

Description

  The present invention relates to an ink jet recording method.

  The ink jet recording method is a method of recording by ejecting small ink droplets from fine nozzles and attaching them to a recording medium. This method has a feature that a high-resolution and high-quality image can be recorded at a high speed with a relatively inexpensive apparatus.

  In recent years, it has been studied to directly record (print) a product label or the like on a flexible packaging film such as a PET film by an inkjet recording method. In addition, the flexible packaging film has an application for packaging food and the like, and in such an application, high safety is required. Therefore, it is desirable to use water-based ink for the above-described printing. When water-based ink is used, a heat drying process may be performed after printing.

  In addition, the recording surface of the flexible packaging film is made of a plastic material such as polyolefin, nylon, or polyester, and is often transparent or translucent. Therefore, when ink jet recording is performed, a predetermined image with color ink may be formed on a layer formed of white ink called an underlayer that hides the background (see, for example, Patent Document 1). Patent Document 2 proposes a white ink for inkjet recording that can be applied to such an underlayer.

JP 2014-0944495 A JP2013-177526A

  When forming a base layer using white ink and recording (overprinting) an ink that forms an image using color ink on top of it, the upper layer should have a large amount of solvent in the lower layer. When ink is applied, bleeding may occur in the image. Therefore, it is conceivable that the upper layer ink is adhered after the lower layer is dried. However, although drying is improved by drying the lower layer ink, there are cases where cracks and peeling occur in the obtained image.

  According to the inventor's investigation, it has been found that the crack is partly due to the difference between the shrinkage rate of the lower layer image and the shrinkage rate of the upper layer image when the formed overstrike image is finally dried. I came. The shrinkage rate of the image of each layer is considered to depend on the amount of the solvent remaining in the image of each layer when the overstrike process is completed. Therefore, it can be expected to reduce cracks by adjusting the amount of the solvent remaining in each layer.

  However, the overstrike image has a laminated structure of two or more images and is not a simple structure. Therefore, it is difficult to stably prevent cracking by simply adjusting the amount of solvent remaining in each layer by simply drying each layer. By the inventors' investigation based on such knowledge, in order to suppress cracks in the overstrike image, including the composition of the ink forming each layer, the control of the residual solvent amount in the lower layer when forming the upper layer, etc. It has been found that balancing many factors is important.

  One of the objects according to some embodiments of the present invention is to provide an ink jet recording method capable of forming an image obtained by overprinting a plurality of inks and suppressing bleeding and cracking. There is.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

One aspect of the inkjet recording method according to the present invention is:
Forming a first ink layer by ejecting a first ink composition containing water, a water-soluble organic solvent, and a solid content containing at least a coloring material on a recording medium by an inkjet method;
A first drying step of evaporating 80% by mass or more of water contained in the first ink composition in the first ink layer;
A second ink composition containing water, a water-soluble organic solvent, and a solid content containing at least a coloring material is ejected onto the first ink layer that has undergone the first drying step by an inkjet method to form a second ink layer. Forming an ink layer;
A second drying step of evaporating volatile components on the recording medium after the step of forming the second ink layer;
With
The “water-soluble organic solvent content / solid content” of the first ink composition is “r1”, and the “water-soluble organic solvent content / solid content” of the second ink composition is “r2”. In this case, the value of “r2 / r1” is 2 or less.

  In such an ink jet recording method, since the value of “r2 / r1” is 2 or less, the balance between the composition of the first ink composition and the second ink composition is good, and crack resistance and the like are excellent. Then, in the state where the amount of water in the first ink layer is removed by 80% by mass or more by the first drying step, the second ink layer is formed on the first ink layer, and the first ink layer and the first ink layer The distribution and residual amount of the solvent in the laminated structure of the two ink layers are improved. Therefore, according to the ink jet recording method, bleeding at the time of forming the second ink layer is suppressed, and cracking of the image in the second drying process is suppressed. According to such an ink jet recording method, it is possible to form an image that is obtained by overprinting a plurality of inks and in which bleeding and cracking are suppressed.

In the inkjet recording method according to the present invention,
The recording medium may be an ink low-absorbing or non-ink-absorbing recording medium.

  According to such an ink jet recording method, for example, an image in which bleeding or cracking is suppressed can be easily formed on a soft packaging film.

In the inkjet recording method according to the present invention,
The first ink composition is a background image ink composition containing at least one of metal compound particles and metal particles as a colorant,
The second ink composition may be a colored ink composition containing a non-white color material.

  According to such an ink jet recording method, an image with good image quality can be formed by the background hiding property of at least one of the metal compound particles and the metal particles.

In the inkjet recording method according to the present invention,
The first drying step may be performed at a surface temperature of the recording medium of 25 ° C. or more and 50 ° C. or less.

  In this way, the water in the first ink layer can be evaporated more easily.

In the inkjet recording method according to the present invention,
The first ink composition may include resin particles as a solid content.

  According to such an ink jet recording method, an image having better adhesion to a recording medium can be formed.

In the inkjet recording method according to the present invention,
The second ink composition may include resin particles as a solid content.

  According to such an ink jet recording method, an image with better adhesion between the first ink layer and the second ink layer can be formed.

In the inkjet recording method according to the present invention,
The resin particles may be at least one of urethane resin particles, ester resin particles, and acrylic resin particles.

  According to such an ink jet recording method, at least one of the adhesion to the recording medium and the adhesion between the stacked ink layers can be further improved.

In the inkjet recording method according to the present invention,
The first ink composition includes at least one of urethane resin particles and ester resin particles,
The second ink composition may include at least one of ester resin particles and acrylic resin particles.

  According to such an ink jet recording method, at least one of the adhesion to the recording medium and the adhesion between the stacked ink layers can be further improved.

In the inkjet recording method according to the present invention,
The ester resin particles are
A polyester resin which is a graft polymer composed of a main chain segment (A1) made of a polyester resin and a side chain segment (A2) made of an addition polymerization resin may be included.

  According to such an ink jet recording method, it is possible to further improve at least one of the adhesion to the recording medium and the adhesion between the stacked ink layers.

In the inkjet recording method according to the present invention,
The “r2 / r1” may be 0.5 or more and 2 or less.

  According to such an ink jet recording method, since the balance of the composition of the first ink composition and the second ink composition is further improved, an image in which bleeding and cracking are further suppressed can be easily formed.

In the inkjet recording method according to the present invention,
The first drying step may be performed such that the evaporation amount of the water-soluble organic solvent contained in the first ink composition in the first ink layer is 20% by mass or less. That is, it is performed so as to be in such a state.

  According to such an ink jet recording method, an image in which bleeding is further suppressed can be easily formed.

In the inkjet recording method according to the present invention,
The first drying step may be performed by at least one of heat conduction, radiation irradiation, and air blowing.

  According to such an ink jet recording method, the amount of water in the first ink layer can be reduced more easily.

In the inkjet recording method according to the present invention,
The second drying step may be performed at a surface temperature of the recording medium of 70 ° C. or higher.

  According to such an ink jet recording method, the recorded image can be dried to a state sufficient for use in a shorter time.

In the inkjet recording method according to the present invention,
After performing the second drying step, a third ink layer is formed by discharging a clear ink composition containing resin particles, a water-soluble organic solvent, and water to the second ink layer by an inkjet method. You may have a process.

  According to such an ink jet recording method, it is possible to further improve the abrasion resistance of the recorded image.

In the inkjet recording method according to the present invention,
When the “water-soluble organic solvent content / solid content” of the clear ink composition is “r3”, the value of “r3 / r1” may be 2 or less.

  According to such an ink jet recording method, since the balance of the composition of the first ink composition and the clear ink composition is further improved, an image in which bleeding and cracking are further suppressed can be easily formed.

In the inkjet recording method according to the present invention,
The step of forming the third ink layer is performed after evaporating 80% by mass or more of the total water contained in the first ink composition and the second ink composition in the second drying step. May be.

  According to such an ink jet recording method, since the clear ink composition is attached to the laminated structure of the first ink layer and the second ink layer from which 80% by mass or more of water has been removed, bleeding is further suppressed. An image can be formed.

In the inkjet recording method according to the present invention,
After the step of forming the third ink layer, a third drying step for evaporating volatile components on the recording medium may be performed.

  According to such an ink jet recording method, it is possible to form an image in which bleeding and cracking are suppressed and the abrasion resistance is further improved in a shorter time.

In the inkjet recording method according to the present invention,
In the first ink composition and the second ink composition, the resin particles are 1% by mass to 15% by mass, the water-soluble organic solvent is 3% by mass to 40% by mass, and the coloring material is 0.5% by mass or more. You may include 15 mass% or less.

  According to such an ink jet recording method, since the balance of the composition of the first ink composition and the second ink composition is further improved, an image in which bleeding and cracking are further suppressed can be easily formed.

In the inkjet recording method according to the present invention,
The water-soluble organic solvent may include a water-soluble organic solvent having a boiling point of 250 ° C. or lower.

  According to such an ink jet recording method, it is possible to easily form an image having good drying properties and further suppressing bleeding and cracking.

  Several embodiments of the present invention will be described below. Embodiment described below demonstrates an example of this invention. The present invention is not limited to the following embodiments, and includes various modified embodiments that are implemented within a range that does not change the gist of the present invention. Note that not all of the configurations described below are essential configurations of the present invention.

  The ink jet recording method according to this embodiment includes a step of forming a first ink layer, a first drying step, a step of forming a second ink layer, and a second drying step. Thereby, a recorded matter having an image recorded on the recording surface of the recording medium is obtained.

1. The process of forming a 1st ink layer The process of forming a 1st ink layer is an inkjet recording the 1st ink composition containing water, the water-soluble organic solvent, and the solid content which contains a coloring material at least on a recording medium. The method is performed by discharging. The step of forming the first ink layer according to this embodiment is performed by discharging the first ink composition onto a recording medium using an ink jet method. Then, a first ink layer (image) is formed in the recording area of the recording medium. The recording area in the recording medium is not particularly limited, but is an area where a second ink layer (image) is planned to be formed by the second ink composition, and the second ink composition is attached to the area. Hereinafter, the recording medium and the first ink composition will be described in this order, and the ink jet method will be described later in another section.

1.1. Recording Medium The recording medium on which an image is formed by the ink jet recording method according to the present embodiment may have a recording surface that absorbs ink or may not have a recording surface that absorbs ink. Accordingly, the recording medium is not particularly limited. For example, ink-absorbing recording media such as paper, film, and cloth, ink-absorbing recording media such as printing paper, and ink non-absorbing recording such as metal, glass, and polymer. Examples include media. However, the excellent effect of the ink jet recording method of the present embodiment becomes more prominent when an image is recorded on a recording medium with low ink absorption or non-ink absorption.

An ink low-absorbing or non-absorbing recording medium refers to a recording medium having a property of not absorbing or hardly absorbing an ink composition. Quantitatively, a non-ink-absorbing or low-absorbing recording medium is a “recording medium having a water absorption of 10 mL / m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method”. Point to. This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method". On the other hand, an ink-absorbing recording medium refers to a recording medium that does not fall under ink non-absorbing property or low absorbing property.

  Examples of non-ink-absorbing recording media include plastic films that do not have an ink absorbing layer, those that are coated with plastic on a substrate such as paper, and those that have a plastic film adhered thereto. . Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

  In addition, examples of the low-ink-absorbing recording medium include a recording medium provided with a coating layer for receiving ink on the surface. For example, as the base material is paper, art paper, coated paper Printing paper such as matte paper, and when the substrate is a plastic film, hydrophilic polymer is coated on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc. And particles in which particles such as silica and titanium are coated together with a binder.

  The ink jet recording method according to this embodiment can be suitably used for a flexible packaging film. The flexible packaging film is an embodiment of the above-described ink non-absorbing recording medium. More specifically, a soft packaging film is a flexible film material used for food packaging, toiletries, cosmetics packaging, etc., and an anti-fogging or antistatic material, an antioxidant or the like is a film. It is a film material which exists on the surface and has a thickness in the range of 5 to 70 μm (preferably 10 to 50 μm). When recording an ink composition on this film, it is difficult to fix the ink as compared to a plastic film having a normal thickness, and even if the ink is fixed, the ink cannot cope with the flexibility of the film, and peeling easily occurs. The ink jet recording method according to this embodiment is more suitable for a flexible packaging film.

  Materials that make up the recording surface of flexible packaging films include olefin resins (polyethylene, polypropylene, etc.), ester resins (polyester, etc.), vinyl chloride resins (polyvinyl chloride, etc.), and amide resins (polyamide, etc.) Those containing at least one resin selected from the above can be used. As the film base including the recording surface of the flexible packaging film, those obtained by processing these resins into a film or a sheet can be used. In the case of a film or sheet using a resin, any of an unstretched film or a stretched film stretched in a uniaxial direction or a biaxial direction can be used. It is preferable to use it. Moreover, it can also be used in the laminated state which bonded together the film and sheet | seat which consist of these various resin as needed.

  The recording medium may be colorless and transparent, translucent, colored and transparent, chromatic color opaque, achromatic color opaque, and the like. Further, the recording medium itself may be colored or translucent or transparent. In such a case, by using the first ink composition as the background image ink composition, the first ink layer can function as a concealing layer that conceals the color of the recording medium itself. For example, when a color image is recorded as the second ink layer using the second ink composition, the color image can be obtained by recording the background image with the background image ink composition in advance in the color image recording area. In some cases, the color developability of can be improved.

1.2. First ink composition The first ink composition contains at least water, a water-soluble organic solvent, and a solid content including a coloring material. When the first ink composition is used as the background image ink composition, for example, a white ink composition or a glitter ink composition can be used.

The white ink composition is an ink (ink) capable of recording a color called “white” by social wisdom, and includes a slightly colored one. Moreover, the ink (ink) containing the pigment includes an ink (ink) which is named and sold under a name such as “white ink (ink), white ink (ink)”. Further, for example, when ink (ink) is recorded on Epson genuine photographic paper <Glossy> (manufactured by Seiko Epson Corporation) with an amount of 100% duty or more or an amount sufficient to cover the surface of the photographic paper, The lightness (L ^* ) and chromaticity (a ^* , b ^* ) were measured using a spectrophotometer Spectrolino (trade name, manufactured by GretagMacbeth), the measurement conditions were D50 light source, the observation field was 2 °, the density was DIN NB, When the white reference is set to Abs, the filter is set to No, and the measurement mode is set to Reflectance, measurement is performed with 70 ≦ L ^* ≦ 100, −4.5 ≦ a ^* ≦ 2, −6 ≦ b ^* ≦ 2.5, Ink (ink) indicating the range of

  The glitter ink composition refers to an ink composition that exhibits glitter when attached to a recording medium. The glitter is a property characterized by, for example, the specular gloss of an obtained image (see Japanese Industrial Standard (JIS) Z8741). For example, the types of glitter include glitter that reflects light in a specular manner and so-called matte glitter, and can be characterized by, for example, high or low specular gloss.

1.2.1. Water The first ink composition contains water. Water is a main medium of the first ink composition, and is a component that evaporates and scatters when dried. The water is preferably water from which ionic impurities such as pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water or ultrapure water are removed as much as possible. In addition, it is preferable to use water sterilized by ultraviolet irradiation or addition of hydrogen peroxide because the generation of mold and bacteria can be suppressed when the ink is stored for a long period of time.

  The first ink composition is preferably a so-called aqueous ink containing water as a main solvent. The water-based ink has an advantage that it is good for the environment because odor is suppressed and 40% by mass or more of its composition is water. The content of water in the ink is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass or more. The upper limit is not limited, but 95% by mass or less is preferable.

1.2.2. Water-soluble organic solvent The first ink composition contains a water-soluble organic solvent. The water-soluble organic solvent is not particularly limited, and examples thereof include alkyl polyols, pyrrolidone derivatives, glycol ethers and the like. These water-soluble organic solvents may be used alone or in combination of two or more. In the present specification, “water-soluble” means having a property that the solubility in 100 g of water at 20 ° C. is 0.1 g or more.

  Examples of the alkyl polyols include propylene glycol, dipropylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,3-butylene glycol, 3-methyl-1,3-butanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propane Examples include diol, 2,2-dimethyl-1,3-propanediol, 2-methylpentane-2,4-diol, and 3-methyl-1,5-pentanediol. Alkyl polyols have a function of improving the wettability of the ink with respect to the recording medium and suppressing the solidification drying of the ink. When the alkyl polyol is contained, the content thereof can be 1% by mass or more and 50% by mass or less with respect to the total mass of the first ink composition.

  Examples of pyrrolidone derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, and 5-methyl-2-pyrrolidone. Etc. The pyrrolidone derivative can act as a good solubilizer for the resin component. When the pyrrolidone derivative is contained, the content thereof can be 0.5% by mass or more and 30% by mass or less with respect to the total mass of the first ink composition.

  Examples of glycol ethers include ethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monoisohexyl ether, diethylene glycol monohexyl ether, triethylene glycol monohexyl ether, diethylene glycol monoisohexyl ether, triethylene glycol monoisopropyl ether. Hexyl ether, ethylene glycol monoisoheptyl ether, diethylene glycol monoisoheptyl ether, triethylene glycol monoisoheptyl ether, ethylene glycol monooctyl ether, ethylene glycol monoisooctyl ether, diethylene glycol monoisooctyl ether, triethylene glycol monoisooctyl ether , Ethile Glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, triethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono-2 -Ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol mono-2-methylpentyl ether, diethylene glycol mono-2-methylpentyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol Monopropyl ether, dipropylene glycol Propyl ether, and tripropylene glycol monomethyl ether, and the like. These can be used individually by 1 type or in mixture of 2 or more types. Glycol ethers can control the wettability and permeation rate of the ink to the recording medium. When glycol ethers are contained, the content thereof can be 0.05% by mass or more and 6% by mass or less with respect to the total mass of the first ink composition.

  The total content of the water-soluble organic solvent is 1% by mass or more and 50% by mass or less, preferably 2% by mass or more and 45% by mass or less, more preferably 3% by mass or more with respect to the total mass of the first ink composition. It is 40 mass% or less, More preferably, it can be 10 mass% or more and 35 mass% or less.

  In the first ink composition, the content of the water-soluble organic solvent having a standard boiling point of 280 ° C. or higher is preferably 3% by mass or less, more preferably 1% by mass or less, and 0.5% by mass. More preferably, it is as follows. In this case, the ink may or may not contain a water-soluble organic solvent having a standard boiling point of 280 ° C. or higher. When the content of the water-soluble organic solvent having a standard boiling point of 280 ° C. or higher is below the above range, it is possible to prevent the ink drying property from being greatly lowered. As a result, for example, recording on a soft packaging film It is possible to prevent the image fixability from being deteriorated. Further, sufficient drying can be performed even if the temperature of the recording medium in the drying process is relatively low. Examples of the water-soluble organic solvent having a standard boiling point of 280 ° C. or higher include glycerin (standard boiling point 290 ° C.).

  Further, the water-soluble organic solvent contained in the first ink composition may be one kind or a combination of two or more kinds, and among them, it preferably contains a water-soluble organic solvent having a standard boiling point of 250 ° C. or less. . The content of the water-soluble organic solvent having a standard boiling point of more than 250 ° C. among the water-soluble organic solvents contained in the ink is preferably 3% by mass or less, more preferably 1% by mass or less. More preferably, it is 5 mass% or less. In this case, the drying property of the ink can be kept high. The lower limit of the content of the water-soluble organic solvent having a standard boiling point exceeding 250 ° C. is preferably 0% by mass or more, that is, it may not be contained.

1.2.3. Color material Examples of the color material include white color materials and glitter pigments.

  Examples of the white color material include metal compounds such as metal oxide, barium sulfate, and calcium carbonate. Examples of the metal compound include titanium dioxide, zinc oxide, silica, alumina, magnesium oxide and the like. The white color material includes particles having a hollow structure, and the particles having a hollow structure are not particularly limited, and known ones can be used. As the particles having a hollow structure, for example, particles described in specifications such as US Pat. No. 4,880,465 can be preferably used. Among these, titanium dioxide is preferably used as the white color material from the viewpoint of good whiteness and abrasion resistance.

  When a white color material is used, the content (solid content) of the white color material is 0.5% by mass or more and 20% by mass or less, preferably 1% by mass with respect to the total mass of the first ink composition. % To 20% by mass, more preferably 5% to 15% by mass, and still more preferably 7% to 15% by mass. When the content of the white color material is within the above range, nozzle clogging or the like of the ink jet recording apparatus hardly occurs, and the color density such as whiteness can be sufficiently satisfied.

  Further, the volume-based average particle diameter (hereinafter referred to as “average particle diameter”) of the white color material is preferably 30 nm or more and 600 nm or less, and more preferably 200 nm or more and 400 nm or less. If the average particle diameter of the white color material is within the above range, the particles are less likely to settle, the dispersion stability can be improved, and nozzle clogging is less likely to occur when applied to an inkjet recording apparatus. can do. Moreover, if the average particle diameter of the white color material is within the above range, the color density such as whiteness can be sufficiently satisfied.

  The average particle diameter of the white color material can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. Examples of the particle size distribution measuring apparatus include a particle size distribution meter (for example, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle.

  The glitter pigment is not particularly limited as long as it can exhibit glitter when attached to a medium. For example, aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and Examples thereof include metal particles of one or more alloys (also referred to as metal pigments) selected from the group consisting of copper, and pearl pigments having pearly luster. Representative examples of pearl pigments include pigments having pearly luster and interference gloss such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride. Further, the glitter pigment may be subjected to a surface treatment for suppressing reaction with water. By including a glitter pigment in the ink, an image having excellent glitter can be formed.

  When the bright pigment is used, the content of the bright pigment is preferably 0.5% by mass or more and 30% by mass or less, and preferably 1% by mass or more and 15% by mass or less with respect to the total mass of the first ink composition. Is more preferable. When the content of the glitter pigment is within the above range, the ejection stability from the nozzle of the ink jet recording apparatus and the storage stability of the glitter ink composition can be improved.

1.2.4. Resin Particles The first ink composition may include resin particles. The resin particles have a function of improving the adhesion and rubbing resistance of the formed image.

  The Tg (glass transition temperature) of the resin particles contained in the first ink composition is not particularly limited, but the upper limit is preferably 150 ° C. or less. If the Tg of the resin particles is 25 ° C. or higher, good abrasion resistance can be obtained while sufficiently securing the adhesion of the image to the recording medium. In addition, since the Tg of the resin particles is 150 ° C. or lower, it is possible to suppress the occurrence of cracks when the first ink layer is dried, and the film formation of the resin can be promoted. Good images can be obtained.

  Resins constituting the resin particles contained in the first ink composition include acrylic resins, fluorene resins, urethane resins, olefin resins, rosin modified resins, terpene resins, ester resins, amide resins, and epoxy resins. Resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene vinyl acetate resin and the like can be used. These resins can be used singly or in combination of two or more. Among these resins, the material of the resin particles contained in the first ink composition is a urethane resin, an ester resin, and an acrylic resin from the viewpoint that the adhesion of the first ink layer to the recording medium can be further improved. It is more preferable that it is at least one selected from series resins. The urethane-acrylic resin and ester-urethane resin may be classified into any of urethane resin, acrylic resin, and ester resin from the main components and characteristics. Preferably, these may be classified as urethane resins.

  Urethane resin is a polymer synthesized by reacting polyisocyanate and polyol. The synthesis of the urethane resin can be carried out by a known method.

  Examples of the polyisocyanate include linear aliphatic isocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4. -Aliphatic isocyanates having a cyclic structure such as cyclohexylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate, 4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-biphenylene diisocyanate, 3,3′-dimethoxy-4, Aromatic isocyanates such as 4′-biphenylene diisocyanate, 3,3′-dichloro-4,4′-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate Is mentioned. When synthesizing a urethane resin, the above polyisocyanate may be used alone or in combination of two or more.

  Examples of the polyol include polyether polyol and polycarbonate polyol. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of the polycarbonate polyol include diols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol, Examples thereof include dialkyl carbonates such as phosgene and dimethyl carbonate, and reaction products with cyclic carbonates such as ethylene carbonate.

  The urethane resin is preferably an emulsion type. Commercially available products can be used for the resin emulsion containing the urethane resin. For example, Superflex 740 (Tg: -34 ° C), (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Bondick 1940NE (Tg : Less than 5 ° C.) (trade name, manufactured by DIC Corporation), Takelac W-6061 (Tg: 25 ° C.) (trade name, manufactured by Mitsui Chemicals, Inc.) and the like.

  The ester resin is more preferably an emulsion type. Commercially available products may be used for the resin emulsion containing the ester resin, for example, Elitel KA-5034 (Tg: 67 ° C.), KA-5071S (Tg: 67 ° C.), KZA-1734 (Tg: 66 ° C.). , KZA-6034 (Tg: 72 ° C.), KZA-3556 (Tg: 80 ° C.) (all trade names, manufactured by Unitika Ltd.) and the like. In addition, the numerical value in a parenthesis is a glass transition temperature (Tg).

  Furthermore, the ester-based resin as the resin particles used in the first ink composition is a main chain segment (A1) (hereinafter referred to as “polyester resin”) from the viewpoint of ejection properties, adhesion to a recording medium, and image storage stability at high temperatures. , “Polyester resin segment (A1)” or “segment (A1)”) and side chain segment (A2) (hereinafter referred to as “addition polymerization resin segment (A2)” or “segment (A2)”. More preferably, the graft polymer is also referred to as “)”. The synthesis of the ester resin can be performed by a known method, for example, as follows.

  The main chain segment (A1) made of a polyester resin means that the main chain segment (A1) is derived from the polyester resin. Further, the side chain segment (A2) made of an addition polymerization resin means that the side chain segment (A2) is derived from the addition polymerization resin. Furthermore, the graft polymer may have other segments in addition to the segment (A1) and the segment (A2). However, the content of the segment (A1) and the segment (A2) in the graft polymer is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably substantially 100% by mass. .

  The mass ratio [segment (A1) / segment (A2)] of the segment (A1) and the segment (A2) constituting the graft polymer is the ink ejection property, the adhesion to the recording medium, and the image storability at high temperature. From the viewpoint, it is preferably 50/50 or more, more preferably 55/45 or more, further preferably 65/35 or more, and from the viewpoint of fixability after drying of the ink, preferably 95/5 or less. More preferably, it is 85/15 or less. Moreover, Preferably it is 50 / 50-95 / 5, More preferably, it is 55 / 45-95 / 5, More preferably, it is 65 / 35-85 / 15, More preferably, it is 65 / 35-75 / 25.

  The polyester resin segment (A1) constituting the graft polymer is a resin segment obtained by condensation polymerization of an alcohol component and a carboxylic acid component. The alcohol component that is a raw material monomer of the segment (A1) preferably contains an alkylene oxide adduct of bisphenol A.

  The alkylene oxide adduct of bisphenol A means the entire structure in which an oxyalkylene group is added to 2,2-bis (4-hydroxyphenyl) propane. The alkylene oxide adduct of bisphenol A may be used alone or in combination of two or more. The alkylene oxide adduct of bisphenol A is preferably a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A, more preferably a propylene oxide adduct of bisphenol A, and more preferably combined use.

  The content of the alkylene oxide adduct of bisphenol A in the alcohol component that is the raw material monomer of the segment (A1) is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol%. That's it. The content of the bisphenol A alkylene oxide adduct is preferably 90 mol% or less, more preferably 85 mol% or less, and still more preferably 80 mol% or less.

  In addition to the alkylene oxide adduct of bisphenol A, the following alcohol components can be contained in the alcohol component which is a raw material monomer of the segment (A1).

  Specifically, examples of the alcohol component of the raw material monomer derived from the structural unit of the segment (A1) (hereinafter also simply referred to as “raw material monomer of the segment (A1)”) include ethylene glycol, propylene glycol (1,2 -Propanediol), glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, or their alkylene (2 to 4 carbon) oxide adduct (average number of added moles 1 to 16). You may use the said alcohol component individually or in combination of 2 or more types. Among these, from the viewpoint of initial fixing properties, preferably 1, 2-propanediol and hydrogenated bisphenol A are one or two, and from the viewpoint of ejection properties, 1,2-propanediol is more preferable. From the viewpoint of image storage stability at high temperatures, hydrogenated bisphenol A is more preferable. Among the above alcohol components, it is preferable to use an alkylene oxide adduct of bisphenol A and hydrogenated bisphenol A from the viewpoint of fixability, and it is more preferable to use a propylene oxide adduct of bisphenol A and hydrogenated bisphenol A together. Preferably, the propylene oxide adduct of bisphenol A and the ethylene oxide adduct of bisphenol A and hydrogenated bisphenol A are more preferably used in combination.

  The segment (A1) is a polyester resin, and a carboxylic acid component is used in addition to the alcohol component as a raw material monomer. Examples of the carboxylic acid component that is a raw material monomer of the segment (A1) include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; adipic acid, succinic acid, succinic acid having an alkyl group and / or alkenyl group, Aliphatic dicarboxylic acids such as allyl alcohol; alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acids and decalin dicarboxylic acids; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, and anhydrides of these acids; These alkyl (C1-C3) ester etc. are mentioned.

  Aromatic dicarboxylic acids and alicyclic dicarboxylic acids are preferred, and cyclohexanedicarboxylic acid and isophthalic acid are more preferred from the viewpoints of ink ejection properties, fixing properties to recording media, and improvement in image storage stability at high temperatures. Among these, aromatic dicarboxylic acid is preferable and isophthalic acid is more preferable from the viewpoint of image storability at high temperature of ink and fixability after drying. The said carboxylic acid component may be individual or 2 or more types may be contained.

  The carboxylic acid component preferably contains a carboxylic acid having a non-aromatic carbon-carbon unsaturated bond, such as an unsaturated aliphatic carboxylic acid and / or an unsaturated alicyclic carboxylic acid.

  The portion of the carbon-carbon unsaturated bond can be a binding portion with the segment (A2) in the graft polymer, in which case the unsaturated bond becomes a saturated bond.

  Examples of carboxylic acids having a non-aromatic carbon-carbon unsaturated bond (unsaturated aliphatic carboxylic acid, unsaturated alicyclic carboxylic acid) include unsaturated acids such as fumaric acid, maleic acid, acrylic acid, and methacrylic acid. Aliphatic carboxylic acid; unsaturated alicyclic carboxylic acid such as tetrahydrophthalic acid. From the viewpoint of reactivity, fumaric acid, maleic acid and tetrahydrophthalic acid are preferable, and fumaric acid is more preferable.

  The content of the carboxylic acid having a non-aromatic carbon-carbon unsaturated bond in the carboxylic acid component is preferably 5 mol% or more, more preferably 7 mol% or more, from the viewpoint of fixability after drying the ink. More preferably, it is 8 mol% or more, more preferably 12 mol% or more, and from the viewpoint of the initial fixability of the ink, it is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol%. Hereinafter, it is more preferably 18 mol% or less, and while maintaining the effect of improving the fixability by the segment (A1), the segment (A2) is sufficiently grafted and the dischargeability by the segment (A2) and at high temperature are increased. From the viewpoint of developing the effect of improving the image storage stability, preferably 5 to 30 mol%, more preferably 7 to 25 mol%, still more preferably 8 to 20 mol%. Le%, even more preferably 12 to 18 mol%.

  In the carboxylic acid component, the content of the aromatic dicarboxylic acid is preferably 50 mol% or more, more preferably 70 mol% or more, and more preferably 70 mol% or more, from the viewpoint of improving image storability at high temperatures and fixing properties after drying. Preferably it is 80 mol% or more, More preferably, it is 82 mol% or more, Preferably it is 95 mol% or less, More preferably, it is 92 mol% or less, More preferably, it is 88 mol% or less.

  In the segment (A1), the molar ratio of the hydroxyl group of the alcohol component to the carboxy group of the carboxylic acid component (hydroxyl group / carboxy group) from the viewpoint of adjusting the particle size of the resin particles and improving the adhesion and image storage stability at high temperature. ) Is preferably 100/90 to 100/120, more preferably 100/95 to 100/110, and still more preferably 100/100 to 100/105.

  The segment (A2) constituting the graft polymer is a segment made of an addition polymerization resin composed of a structural unit derived from the addition polymerizable monomer (a2) (hereinafter also referred to as “monomer (a2)”). The segment (A2) is a side chain in the graft polymer. Examples of the addition polymerizable monomer (a2) include styrenes such as styrene, methylstyrene, α-methylstyrene, β-methylstyrene, t-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, or a salt thereof. ; (Meth) acrylic acid esters such as alkyl (meth) acrylate (C1-18), benzyl (meth) acrylate, dimethylaminoethyl (meth) acrylate; olefins such as ethylene, propylene, butadiene; Halovinyls such as vinyl; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as vinyl methyl ether; Vinylidene halides such as vinylidene chloride; N-vinyl compounds such as N-vinylpyrrolidone; More than species.

  Among these, one or two of styrenes and (meth) acrylic acid esters are preferable, and two are more preferable, from the viewpoint of improving fixability to a recording medium and image storage stability at high temperatures.

  The addition polymerizable monomer having an aromatic group is preferably one or more of styrene, methylstyrene, phenoxyethylene glycol (meth) acrylate, benzyl methacrylate, and benzyl acrylate. Among these, one or two of styrene and phenoxyethylene glycol (meth) acrylate are preferable, and from the viewpoint of the raw material price of the monomer, styrene is more preferable, and styrene is more preferable.

  The (meth) acrylic acid ester preferably has an alkyl group having 1 to 22 carbon atoms, preferably 6 to 18 carbon atoms. For example, methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meta) ) Acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) Examples include decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (iso) stearyl (meth) acrylate, lauryl acrylate, and the like, preferably one or two of 2-ethylhexyl (meth) acrylate and lauryl acrylate is there.

  The addition polymerizable monomer (a2) is preferably a combination of at least one of the above (meth) acrylic acid esters and styrene, more preferably one or two of 2-ethylhexyl (meth) acrylate and lauryl acrylate. And styrene.

  The content of the structural unit derived from the addition-polymerizable monomer having an aromatic group is preferably 40% by mass in the segment (A2) from the viewpoints of dischargeability, fixability to a recording medium, and image storage stability at high temperatures. Or more, more preferably 45% by mass or more, more preferably 50% by mass or more, more preferably 51% by mass or more, preferably 100% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass. Hereinafter, it is more preferably 80% by mass or less.

  In addition, the structural unit derived from the (meth) acrylic acid ester is preferably used in combination with styrene from the viewpoint of initial fixability and fixing property after drying, and the content of the structural unit derived from the (meth) acrylic acid ester is In the segment (A2), it is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 35% by mass or more, from the viewpoints of ejection properties, fixing properties to a recording medium, and image storage stability at high temperatures. Yes, preferably 60% by mass or less, more preferably 55% by mass or less, and still more preferably 50% by mass or less.

  Mass ratio of the total amount of unsaturated aliphatic carboxylic acid and unsaturated alicyclic carboxylic acid among the raw material monomers of segment (A2) and segment (A1) [segment (A2) / unsaturated group of segment (A1) The total of the above-mentioned components] is preferably 1/1 to 40/1, more preferably 5/1 to 30/1, and still more preferably 10/1 to 15 /, from the viewpoint of initial fixability and fixability after drying. 1.

  The acrylic resin refers to a polymer obtained by using at least one of (meth) acrylic acid, (meth) acrylic acid ester, acrylonitrile, cyanoacrylate, and acrylamide as a monomer (hereinafter also referred to as “acrylic monomer”). . The acrylic resin may be a homopolymer of an acrylic monomer or a monomer other than an acrylic monomer (for example, olefin, styrene, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, vinyl pyrrolidone, vinyl pyridine, vinyl carbazole, And a copolymer with vinyl imidazole, vinylidene chloride, etc.). In addition, said copolymer may be any form among a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer. In this specification, “(meth) acryl” means at least one of acrylic and methacryl corresponding thereto. The acrylic resin can be synthesized by a known method.

  Among the above, the acrylic resin is preferably at least one of a (meth) acrylic resin and a styrene- (meth) acrylic acid copolymer resin from the viewpoint that the adhesion of the first ink layer can be further improved. At least one of acrylic resin and styrene-acrylic acid copolymer resin is more preferable, and styrene-acrylic acid copolymer resin is more preferable. The acrylic resin is more preferably supplied as an emulsion type.

  Commercially available products may be used for the resin emulsion containing the acrylic resin, for example, Movinyl 972 (Tg: 101 ° C.), 7180 (Tg: 53 ° C.) (all trade names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Joncryl 530 (Tg: 75 ° C.), 538 (Tg: 64 ° C.), 1908 (Tg: 98 ° C.), 1925 (Tg: 75 ° C.), 1992 (Tg: 78 ° C.) (all trade names, manufactured by BASF) ) And the like. In addition, the numerical value in a parenthesis is a glass transition temperature (Tg).

  The resin particle content (solid content) is preferably 0.5% by mass or more and 20% by mass or less, based on the total mass of the first ink composition, when a plurality of types are used. It is more preferable to set the mass to 15% by mass or less. When the resin particle content is 0.5% by mass or more, the adhesion of the first ink layer to the recording medium and the adhesion to the second ink layer are further improved. Further, when the content of the resin particles is 20% by mass or less, the dischargeability of the first ink composition from the recording head tends to be good.

1.2.5. Other ingredients <Wax>
The first ink composition may contain a wax. Since the wax has a function of imparting lubrication to the first ink layer, it is possible to reduce peeling of the first ink layer.

  Examples of the components constituting the wax include plant and animal waxes such as carnauba wax, candeli wax, beeswax, rice wax, and lanolin; petroleum oils such as paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, and petrolatum. Wax; Mineral waxes such as montan wax and ozokerite; synthetic waxes such as carbon wax, Hoechst wax, polyolefin wax, stearamide, natural / synthetic wax emulsions such as α-olefin / maleic anhydride copolymer and blended wax Etc. can be used alone or in admixture of plural kinds. Among these, it is preferable to use polyolefin wax (especially polyethylene wax, polypropylene wax) and paraffin wax from the viewpoint of being excellent in the effect of improving fixability to the soft packaging film described later.

  As the wax, commercially available products can be used as they are, for example, Nopcoat PEM-17 (trade name, manufactured by San Nopco Co., Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals, Inc.), AQUACER 515, 539, 593 (above products) Name, manufactured by Big Chemie Japan Co., Ltd.).

  From the viewpoint of suppressing the performance of the wax from being excessively melted in the drying step, the melting point is preferably 50 ° C. or higher and 200 ° C. or lower, more preferably 70 ° C. or higher and 180 ° C. or lower, and still more preferably the melting point. It is preferable to use a wax having a temperature of 100 ° C. or higher and 180 ° C. or lower.

  The wax may be supplied in the form of an emulsion, in which case it can be considered as a kind of resin particles. The content of the wax is 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, more preferably 5% by mass or less in terms of solid content with respect to the total mass of the first ink composition. It is preferable that they are 1 mass% or more and 4 mass% or less. When the content of the wax is within the above range, the function of the wax can be satisfactorily exhibited.

<Resin dispersant>
Since the first ink composition contains a white color material and a bright pigment as the color material, the white color material and the bright pigment can be stably dispersed and retained in water for application to the ink jet method. It is preferable to make it. As the method, a method of dispersing with a resin dispersant such as a water-soluble resin and / or a water-dispersible resin, a method of dispersing with a dispersant, and chemically and physically adding a hydrophilic functional group to the surface of the colorant particles. Introducing a method that enables dispersion and / or dissolution in water without the resin or dispersant, among others, a method of dispersing using a resin dispersant (resin-dispersed pigment) is particularly preferred in ink compositions. It is preferable because of its excellent dispersion stability, ejection stability from the head nozzle holes by the ink jet method, durability such as adhesion and rubbing resistance of the obtained image, and the like.

  Examples of the resin dispersant include polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, and styrene-acrylic acid copolymer. Styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer Styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-croton Acid copolymers, vinyl acetate-acrylic acid copolymers, and the like Salt. Among these, a copolymer of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and a polymer composed of a monomer having both a hydrophobic functional group and a hydrophilic functional group are preferable. As the form of the copolymer, any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer can be used.

  The content ratio of the resin dispersant can be appropriately selected depending on the color material to be dispersed, but is preferably 5 parts by mass or more and 200 parts by mass with respect to 100 parts by mass of the color material in the first ink composition. Hereinafter, it is more preferably 20 parts by mass or more and 120 parts by mass or less.

<Surfactant>
The first ink composition may contain a surfactant. The surfactant has a function of reducing the surface tension and improving the wettability with the recording medium. Among the surfactants, for example, acetylene glycol surfactants, silicone surfactants, and fluorine surfactants can be preferably used.

  Although it does not specifically limit as acetylene glycol type surfactant, For example, Surfynol 104,104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50,104S, 420,440,465,485, SE, SE- F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D (all are trade names, manufactured by Air Products and Chemicals. Inc.), Olphin B, Y, P, A, STG, SPC , E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all trade names, river Ken Fine Chemical Co., Ltd.).

  Although it does not specifically limit as a silicone type surfactant, A polysiloxane type compound is mentioned. Although it does not specifically limit as the said polysiloxane type compound, For example, polyether modified organosiloxane is mentioned. Commercially available products of the polyether-modified organosiloxane include, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (all trade names, BYK Chemie Japan KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X- 22-4515, KF-6011, KF-6012, KF-6015, KF-6017 (all are trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

  As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples include BYK-340 (trade name, manufactured by BYK Japan).

  When the surfactant is contained, the content thereof is 0.1% by mass or more and 2% by mass or less, preferably 0.2% by mass or more and 1.5% by mass with respect to the total mass of the first ink composition. % Or less, more preferably 0.5 mass% or more and 1.2 mass% or less.

<Other ingredients>
The first ink composition may contain a pH adjuster, an antiseptic / antifungal agent, a chelating agent, an antirust agent and the like as necessary. Examples of the pH adjuster include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate, Examples thereof include sodium hydrogen carbonate. Examples of antiseptics and fungicides include sodium benzoate, sodium pentachlorophenol, 2-pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3-one Etc. Examples of commercially available products include Proxel XL2, Proxel GXL (all trade names, manufactured by Avisia), Denicide CSA, NS-500W (all trade names, manufactured by Nagase ChemteX Corporation), and the like. Examples of chelating agents include ethylenediaminetetraacetate and iminodisuccinate. Examples of the rust inhibitor include benzotriazole.

1.3. Solid content The solid content in the first ink composition is a colorant, a resin dispersant, resin particles, a chelating agent, a rust preventive agent, etc. present in the ink composition. Represents ingredients that do not evaporate during the drying process. That is, it represents components other than volatile components such as water and water-soluble organic solvents. On the other hand, the volatile component is a component that is not a solid content, but is a component that evaporates in the second drying step as a post-drying step, and other components such as water, water-soluble organic solvents, surfactants and pH adjusters. It is a component which evaporates in the 2nd drying process as a post-drying process among components.

1.4. Water-soluble organic solvent content / solid content r1
As described above, the first ink composition of the present embodiment includes a water-soluble organic solvent and a solid content. Therefore, “r1” can be defined as “water-soluble organic solvent content / solid content”. “R1” has a specific relationship described later with “r2” of the second ink composition described later.

2. First Drying Process The ink jet recording method according to this embodiment includes a first drying process for drying the first ink layer.

The first drying step is a step of drying the first ink composition (image) on the recording medium after the step of forming the first ink layer. The first drying step is a step of evaporating 80% by mass or more of water contained in the first ink composition (first ink layer) adhered on the recording medium. The evaporation amount (evaporated amount) of water contained in the first ink layer in the first drying step is preferably 85% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. . Further, the evaporation amount of water contained in the first ink layer in the first drying step is 100% by mass or less, preferably less than 100% by mass, and more preferably 98% by mass or less. Moreover, 95 mass% or less is preferable, 90 mass% or less is more preferable, and 85 mass% or less is further more preferable at the point which the discharge stability of a head is excellent, or the time of the 1st drying process can be shortened.
When the water evaporation rate of the 1st ink in a 1st drying process is high, it is preferable at the point which is excellent in crack resistance. On the other hand, when the water evaporation rate of the first ink in the first drying process is low, the surface temperature of the recording medium in the first drying process can be relatively lowered, and ejection defects of the inkjet head can be reduced, and the first drying process is required. This is preferable in terms of shortening the time. Accordingly, the recording method of the present embodiment is particularly useful when reducing ejection failure of the inkjet head or shortening the time required for the first drying process.

  Here, the evaporation amount of water or the water-soluble organic solvent in the present embodiment can be measured as follows, for example. That is, the mass of the ink droplets of the first ink composition ejected to form the first ink layer is 100%, and the sample is immediately after the first drying process is completed on the formed first ink layer. Collect and measure, for example, by thermogravimetric analysis (TGA), gas chromatography (GC), liquid chromatography (LC), or in the case of water, analysis using a moisture meter alone or in combination. Can do.

  In the first drying step, volatile components other than water, specifically, a water-soluble organic solvent in the first ink composition may be evaporated. For example, the first drying step is preferably performed so that the evaporation amount of the water-soluble organic solvent contained in the first ink composition in the first ink layer is 50% by mass or less. In this case, in the first drying step, the evaporation amount of the water-soluble organic solvent contained in the first ink composition in the first ink layer is preferably 30% by mass or less, more preferably It may be 25% by mass or less, more preferably 20% by mass or less, particularly preferably 15% by mass or less, still more preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. In the first drying step, the lower limit of the evaporation amount of the water-soluble organic solvent contained in the first ink composition in the first ink layer is 0% by mass. In this case, a water-soluble organic solvent such as water is used. Other volatile components will volatilize. Thereby, a high-quality image can be obtained in a short time even on a non-ink-absorbing recording medium such as a plastic film having no ink absorbing layer. Even when the surface temperature of the recording medium in the first drying step is relatively low, the amount of water evaporation tends to be 80% by mass or more. In this case, in the step of forming the first ink layer, It is preferable that the nozzle holes receive heat from the recording medium and are adversely affected such as clogging.

  The first drying step is not particularly limited as long as it is a method for promoting the evaporation of water present in the ink. Examples of the method used in the first drying step include a method of applying heat to the recording medium, a method of blowing air on the image on the recording medium after the step of forming the first ink layer, and a method of combining them. Specifically, forced air heating, radiant heating, conductive heating, high frequency drying, microwave drying and the like are preferably used as means used in these methods. It may be dried by leaving.

  Further, the first drying step may be performed by blowing with heating (that is, warm air), or may be performed by combining the blowing unit and the heating unit. As a means for blowing air, for example, a known drying device such as a dryer can be used.

  In the first drying step, air may be blown while heating the recording surface as necessary. The air blowing in the first drying step is a wind speed of 0.1 m / second to 5 m / second, preferably a wind speed of 0.2 m / second to 3 m / second, more preferably a wind speed of 0.3 m / second to 2 m / second, and more. The wind speed is preferably 0.5 m / second or more and 1 m / second or less. Within this range, image disturbance due to wind can be reduced while drying is proceeding. Within such a range, the water contained in the first ink layer can be easily evaporated by 80% by mass or more.

  In addition, the “air blowing” in the present embodiment includes those that blow air on the ink layer provided on the recording surface, and those that allow air to pass through the surface of the recording surface without blowing air directly on the ink layer. (That is, those that generate an air flow near the surface of the recording surface).

  The first drying step can be performed at at least one timing before, during, and after discharge of the first ink composition.

  It is preferable that a 1st drying process contains ventilation, and it can evaporate (volatilize) the water contained in a 1st ink layer effectively by this.

  The surface temperature of the recording medium in the first drying step is preferably 50 ° C. or less, more preferably 45 ° C. or less, and still more preferably 40 ° C. or less. The surface temperature of the recording medium in the first drying step is preferably 25 ° C. or higher, more preferably 30 ° C. or higher, and further preferably 35 ° C. or higher. Within such a range, the water contained in the first ink layer can be easily evaporated by 80% by mass or more. Further, the surface temperature of the recording medium in the first drying step is preferably lower than the surface temperature of the recording medium in the second drying step described later. By doing in this way, the flow of the resin component in a 2nd drying process can be suppressed. In this embodiment, when the first drying process is performed using a plurality of mechanisms, such as when a plurality of forced air heating, radiation heating, conductive heating, high frequency drying, microwave drying, and the like are combined, The temperatures achieved can also be set differently. In such a case, the highest surface temperature of the recording medium is defined as the temperature of the first drying step. The same applies to the second drying step and the third drying step.

  Further, the drying time in the first drying step (that is, the time for performing blowing and heating) is not particularly limited as long as the drying rate of each layer is set in the range described later. However, the drying time of the first drying step (that is, the time for performing air blowing, heating, etc.) depends on the composition of the first ink composition, but is, for example, not less than 0.1 seconds and not more than 100 seconds, preferably 0.8. The range is from 2 seconds to 50 seconds, more preferably from 0.5 seconds to 30 seconds, and still more preferably from 1 second to 10 seconds. Within such a range, the water contained in the first ink layer can be easily evaporated by 80% by mass or more.

  In the first drying step, “80% by mass or more of water is evaporated”, but at this time, most of the water-soluble organic solvent may remain without being evaporated. In particular, when the first drying step is performed under a relatively low temperature condition of 50 ° C. or less, preferably 40 ° C. or less, water mainly evaporates rather than the water-soluble organic solvent, and the water-soluble organic solvent is slightly present. In many cases, it does not evaporate at all. However, performing the first drying step at the above temperature and time is advantageous in terms of simplifying the drying mechanism provided in the apparatus and shortening the time required for recording.

3. The step of forming the second ink layer The step of forming the second ink layer includes, on the first ink layer that has undergone the first drying step, water, a water-soluble organic solvent, and a solid content containing at least a coloring material, The second ink composition containing is discharged by an inkjet method.

  The first ink layer that has undergone the first drying step has a water content of less than 20% by mass. For this reason, even if the second ink composition is adhered, the obtained image is difficult to blur. In this step, the second ink composition is ejected by an ink jet method. The inkjet method is the same as the above-described step of forming the first ink layer, and thus the description thereof is omitted. The ink jet recording apparatus to which the second ink composition is attached and the ink jet recording apparatus to which the first ink composition is attached may be the same or different. In the case of the same, each ink composition can be ejected from the recording heads and / or nozzles of the inkjet recording apparatus used at an appropriate timing. Hereinafter, the second ink composition will be described.

3.1. Second ink composition The second ink composition contains at least water, a water-soluble organic solvent, and a solid content including a coloring material. When the second ink composition is a coloring ink composition containing a non-white color material, for example, a color ink composition or a black ink composition can be used.

3.1.1. Water The second ink composition contains water. Water is a main medium of the second ink composition, and is a component that is evaporated and scattered by drying. Since the description of water is the same as that of the first ink composition, the description thereof is omitted.

  The second ink composition can be preferably used as the above-mentioned water-based ink.

3.1.2. Water-soluble organic solvent The second ink composition contains a water-soluble organic solvent. The water-soluble organic solvent is not particularly limited, and examples thereof include alkyl polyols, pyrrolidone derivatives, glycol ethers and the like. These organic solvents may be used alone or in combination of two or more. Note that specific examples, effects, content ranges, and the like of each organic solvent are the same as the contents shown in the first ink composition, and thus description thereof is omitted.

  As in the first ink composition, the content of the water-soluble organic solvent having a standard boiling point of 280 ° C. or higher is preferably 3% by mass or less, and the second ink composition is more preferably 1% by mass or less. Preferably, it is 0.5 mass% or less. When the content of the water-soluble organic solvent having a standard boiling point exceeding 280 ° C. is in the above range, the drying property of the ink layer can be kept high.

3.1.3. Colorant The second ink composition contains a non-white (color) colorant. The non-white color material refers to a color material other than the above-mentioned white color material and glitter pigment. Examples of the non-white color material include dyes and pigments.

  As the dye and the pigment, those described in US Patent Application Publication No. 2010/0086690, US Patent Application Publication No. 2005/0235870, International Publication No. 2011/027842, and the like can be suitably used. Of the dyes and pigments, it is more preferable to include a pigment. The pigment is preferably an organic pigment from the viewpoint of storage stability such as light resistance, weather resistance, and gas resistance.

  Specifically, the pigment is an insoluble azo pigment, condensed azo pigment, azo lake, chelate azo pigment or other azo pigment, phthalocyanine pigment, perylene and perinone pigment, anthraquinone pigment, quinacridone pigment, dioxane pigment, thioindigo pigment, isoindolinone pigment, Polycyclic pigments such as quinophthalone pigments, dye chelates, dye lakes, nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments, carbon black and the like are used. The above pigments can be used alone or in combination of two or more.

  Examples of the dye include various dyes used for normal inkjet recording such as direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes, vat dyes, soluble vat dyes, and reactive disperse dyes. Can be used.

  The content of the non-white color material is preferably 0.3% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, with respect to the total mass of the second ink composition. is there.

3.1.4. Resin Particles The second ink composition may contain at least one resin particle described in the first ink composition. The resin constituting the resin particles contained in the second ink composition includes acrylic resin, fluorene resin, urethane resin, olefin resin, rosin modified resin, terpene resin, ester resin, amide resin, epoxy Resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene vinyl acetate resin and the like can be used. These resins can be used singly or in combination of two or more. Of these resins, the material of the resin particles contained in the second ink composition is at least one of the adhesion of the second ink layer to the first ink layer and the abrasion resistance of the second ink layer. From the viewpoint that it can be further improved, it is more preferable to be at least one selected from ester resins and acrylic resins. Furthermore, when the material of the resin particles contained in the first ink composition is the same as the material of the resin particles contained in the second ink layer, the adhesion between the second ink layer and the first ink layer is further improved. From the viewpoint of being possible, it is more preferable.

3.1.5. Other Components The second ink composition may contain a resin dispersant, a wax, a surfactant, a pH adjuster, an antiseptic / fungicide, a chelating agent, a rust inhibitor, and the like. In the second ink composition, the resin dispersant is effectively used for the pigment. In addition, the second ink composition can be any of a resin dispersed pigment, a dispersant dispersed pigment, and a surface-treated pigment, and can be used in the form of a mixture of a plurality of types if necessary. It is preferable.

  Specific examples of components such as resin dispersants, waxes, surfactants, pH adjusters, preservatives / fungicides, and rust inhibitors that can be used in the second ink composition, effects of each agent, range of contents, etc. Since is the same as that shown in the first ink composition, the description thereof is omitted.

3.2. Solid content The solid content in the second ink composition is a colorant, a resin dispersant, a resin particle, a chelating agent, a rust inhibitor, etc. present in the ink composition, as in the first ink composition described above. In the second drying step, which will be described later, a component that does not evaporate, that is, a component other than a volatile component such as water or a water-soluble organic solvent.

3.3. Water-soluble organic solvent content / solid content r2
As described above, the second ink composition of the present embodiment includes a water-soluble organic solvent and a solid content. Therefore, “r2” can be defined as “water-soluble organic solvent content / solid content”. “R2” has a specific relationship described later with “r1” of the first ink composition.

4). Second Drying Step The ink jet recording method according to the present embodiment has a second drying step for evaporating volatile components on the recording medium after the step of forming the second ink layer. In the second drying step, volatile components (water, alkyl polyol, glycol ether, etc.) contained in the first ink layer and the second ink layer are evaporated, but other ink layers (for example, a third ink layer described later) are formed. Then, a final drying step of evaporating volatile components remaining on the entire recording medium may be employed. For example, the second drying step may have the same drying function as the first drying step, and may be performed under the same conditions as the first drying step. In addition, for example, the second drying process may function as a final drying process, which is easier to dry than the first drying process, for example, a condition where the surface temperature of the recording medium is higher, or the time of the drying process. May be performed under longer conditions. That is, the second drying step may be a second first drying step (sometimes referred to as “first drying step 2” in this specification), or a final drying step (in this specification, It may be referred to as “post-drying step”).

4.1. Post-drying step When the second drying step is a post-drying step, in the second drying step, volatile components (water, alkyl polyol, glycol ether, etc.) contained in the first ink layer and the second ink layer are evaporated and recorded. Dry the product until it can be used.

  Even if the second drying step is a post-drying step, the drying performed in the second drying step is the second because at least the first ink layer has been dried to a predetermined amount of water by the first drying step. The flow of ink droplets that form the ink layer can be suppressed. Accordingly, the ink droplets of the second ink composition can be kept at the location where the ink droplets are adhered, so that it is possible to suppress image bleeding (bleeding) caused by excessive mixing of components contained in each layer.

  When the second drying step is a post-drying step, the second drying step is performed under conditions that make it easier to dry the volatile component than the first drying step. In this case, the method used in the second drying step and the means used are not particularly limited as long as the method promotes evaporation of volatile components present in the ink, but the same method as the method used in the first drying step. (E.g., a method of applying heat to a recording medium, a method of blowing air on an image on a recording medium, and a method of combining them), a higher temperature than the first heating step, and / or It is preferable to carry out with a high air volume.

  For example, when the second drying process is a post-drying process, air may be blown while heating the recording surface. The air blowing in the second drying step in this case is preferably performed at a wind speed of 5 m / second or more, preferably 6 m / second or more and 50 m / second or less, preferably 6 m / second or more and 40 m / second or less, more preferably 7 m / second or more. It is preferable to carry out at a speed of not less than seconds and not more than 30 m / second. By drying at a wind speed of 6 m / second or more, the evaporation speed of the liquid medium can be improved, and by performing at 50 m / second or less, image disturbance due to wind can be reduced while maintaining the drying property. In this case, the surface temperature of the recording medium in the second drying step is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and still more preferably 80 ° C. or higher. Further, in this case, the surface temperature of the recording medium in the second drying step is preferably higher than the surface temperature of the recording medium in the first drying step. When the second drying process is a post-drying process, the surface temperature of the recording medium in the second drying process is preferably 150 ° C. or less, more preferably 130 ° C. or less.

  When the second drying step is a post-drying step, the drying time of the second drying step (that is, the time for performing blowing and heating) is preferably at least twice the drying time in the first drying step, It is more preferably 3 times or more, and further preferably 3 times or more and 30 times or less. In this way, by setting the drying time of the second drying step to be twice or more the drying time of the first drying step, the volatile components are sufficiently evaporated, so that an image having excellent abrasion resistance can be obtained. it can. Moreover, by setting it as 30 times or less, it is possible to shorten the drying time while sufficiently evaporating the liquid medium.

4.2. First drying step 2
When the second drying step is the second first drying step (first drying step 2), in the second drying step, the volatile components (water, alkyl polyol, Glycol ether, etc.) is evaporated to prevent bleeding when other ink layers (for example, a third ink layer described later) are formed, and the volatile components remaining on the entire recording medium are reduced to the extent that cracks are less likely to occur. Evaporate.

  Even if the second drying step is the first drying step 2, the drying performed in the second drying step is because at least the first ink layer has been dried to a predetermined moisture amount by the first drying step. The flow of ink droplets forming the second ink layer can be suppressed. Accordingly, the ink droplets of the second ink composition can be kept at the location where the ink droplets are adhered, so that it is possible to suppress image bleeding (bleeding) caused by excessive mixing of components contained in each layer.

  When the second drying step is the first drying step 2, the second drying step may be performed under the same conditions as the first drying step. That is, after the step of forming the second ink layer, the first ink composition and the second ink composition (image) on the recording medium are dried to prepare for the adhesion of the third ink composition. it can. In this case, in the second drying step, it is preferable to evaporate 80% by mass or more of water contained in the first ink composition and the second ink composition deposited on the recording medium. In this case, the evaporation amount of water contained in the first ink layer and the second ink layer in the second drying step is preferably 85% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. It is. Even in this case, the evaporation amount of water contained in the first ink layer and the second ink layer in the second drying step is preferably less than 100%.

  When the second drying step is the first drying step 2, in the second drying step, volatile components other than water, specifically, the first ink composition and the water-soluble organic solvent in the second ink composition, etc. May be evaporated. For example, when the second drying step is the first drying step 2, similarly to the first drying step described above, the second drying step includes the first ink composition and the first ink layer in the first ink layer and the second ink layer. It is preferable that the total amount of water-soluble organic solvents contained in the two-ink composition be 50% by mass or less. In this case, in the second drying step, the total amount of the water-soluble organic solvent contained in the first ink composition and the second ink composition is preferably 30% by mass or less. More preferably 25% by mass or less, further preferably 20% by mass or less, particularly preferably 15% by mass or less, more preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. Good. In this case as well, the lower limit of the total evaporation amount of the water-soluble organic solvent contained in the first ink composition and the second ink composition in the second drying step is 0% by mass. Volatile components other than water-soluble organic solvents and the like will volatilize. Thereby, a high-quality image can be obtained in a short time even on a non-ink-absorbing recording medium such as a plastic film having no ink absorbing layer.

  Even if the second drying step is the first drying step 2, the second drying step is not particularly limited as long as it is a method for promoting the evaporation of water present in the ink. Examples of the method used in the first drying step include a method of applying heat to the recording medium, a method of blowing air on the image on the recording medium after the step of forming the first ink layer, and a method of combining them. Specifically, forced air heating, radiant heating, conductive heating, high frequency drying, microwave drying and the like are preferably used as means used in these methods.

  Moreover, when a 2nd drying process is the 1st drying process 2nd, a 2nd drying process may be performed by the ventilation (namely, warm air) accompanying a heating, and combines a ventilation means and said heating means. You may go. As a means for blowing air, for example, a known drying device such as a dryer can be used. In this case, in the second drying process, air may be blown while heating the recording surface as necessary. The wind speed, the surface temperature of the recording medium, the drying time, and the like are the same as in the first drying step described above.

  In addition, when the second drying process is the first drying process 2, “80% by mass or more of water is evaporated”, but at this time, most of the water-soluble organic solvent may remain without being evaporated. In particular, when the second drying step (first drying step 2) is performed at a relatively low temperature of 50 ° C. or less, preferably 40 ° C. or less, water mainly evaporates rather than the water-soluble organic solvent. In many cases, the organic organic solvent evaporates little or not at all. However, performing the second drying step at the above temperature and time is advantageous in terms of simplifying the drying mechanism provided in the apparatus and shortening the time required for recording.

  Further, when the second drying process is the first drying process 2, this may be a final drying process, and thereafter, it may be naturally dried to dry the recorded material, A post-drying step may be performed to dry the recorded material to a usable state.

5). Value of “r2 / r1” In the ink jet recording method of the present embodiment, “water-soluble organic solvent content / solid content” of the first ink composition is “r1”, and “water-soluble property of the second ink composition is set. When “organic solvent content / solid content” ”is“ r2 ”, the value of“ r2 / r1 ”is 2 or less. By doing in this way, the balance of the composition of the 1st ink composition and the 2nd ink composition is good. That is, since the value of “r2 / r1” is 2 or less, the distribution and residual amount of the solvent in the laminated structure of the lower layer image (for example, the first ink layer) and the upper layer (for example, the second ink layer) are improved, When the formed image is finally dried (for example, in the second drying step), the shrinkage ratio of the lower layer image (for example, the first ink layer) and the shrinkage ratio of the upper layer (for example, the second ink layer) are It is not so different. Thereby, the crack in the image obtained is suppressed.

  Such an effect is obtained when the value of “r2 / r1” is 2 or less, and the value of “r2 / r1” is preferably 1.8 or less, more preferably 1.5 or less. Further, the lower limit of the value of “r2 / r1” may be a value exceeding 0, preferably 0.5 or more, more preferably 0.7 or more, and further preferably 1 or more.

6). Effects In such an ink jet recording method, since the value of “r2 / r1” is 2 or less, the composition balance between the first ink composition and the second ink composition is good. Then, the amount of water in the first ink layer is reduced by the first drying step, the second ink layer is formed on the first ink layer, and in the laminated structure of the first ink layer and the second ink layer. The distribution of the solvent and the remaining amount are improved. Therefore, according to the ink jet recording method, bleeding at the time of forming the second ink layer is suppressed, and cracking of the image in the second drying process is suppressed. According to such an ink jet recording method, it is possible to form an image obtained by overprinting a plurality of inks, in which both bleeding and cracking are suppressed.

7). Other steps 7.1. Step of Forming Third Ink Layer After performing the second drying step (the above-mentioned “second first drying step (first drying step 2)”), the ink jet recording method of the present embodiment is followed by the second ink layer. In addition, a step of forming a third ink layer by discharging a clear ink composition containing resin particles, a water-soluble organic solvent, and water by an inkjet method may be included. The first ink layer may be formed on a region of the first ink layer where the second ink layer is not formed, or on the recording medium, where the first ink layer is formed. It may be formed on a region that is not.

  The third ink layer is formed of a clear ink composition and has a function of a protective layer that protects an image formed on the recording medium. By forming the third ink layer, it is possible to further improve the abrasion resistance of the image.

  When this step is performed, the clear ink composition is ejected by an ink jet method. The inkjet method is the same as the above-described step of forming the first ink layer, and thus the description thereof is omitted. The ink jet recording apparatus to which the clear ink composition is attached and the ink jet recording apparatus to which the first ink composition and / or the second ink composition are attached may be the same or different. In the case of the same, each ink composition can be ejected from the recording heads and / or nozzles of the inkjet recording apparatus used at an appropriate timing.

  Further, when performing the step of forming the third ink layer, the second drying step is the second first drying step (first drying step 2), and the first ink composition, the second ink composition, It may be performed after evaporating 80% by mass or more of the total water contained in. By doing in this way, the object (the recording medium, at least one kind of the first ink layer and the second ink layer) to which the clear ink is attached has a water content of less than 20% by mass. Therefore, even if the clear ink composition is attached, the resulting image is less likely to bleed.

7.1.1. Clear ink composition The clear ink composition contains at least resin particles, a water-soluble organic solvent, and water. The clear ink composition can be a topcoat ink composition that does not contain a coloring material. The clear ink composition is not an ink composition that is used by coloring the recording medium, but an ink composition that is used to adjust the quality of the recorded material, such as gloss, abrasion resistance, and adhesion, and contains a coloring material. The amount is preferably 0.1% by mass or less, and more preferably 0.05% by mass or less. Most preferred is 0% by mass, that is, a form containing no coloring material.

7.1.2. Resin Particles The clear ink composition contains at least one resin particle described in the first ink composition. The resin constituting the resin particles contained in the clear ink composition includes acrylic resins, fluorene resins, urethane resins, olefin resins, rosin-modified resins, terpene resins, ester resins, amide resins, and epoxy resins. Resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, ethylene vinyl acetate resins, and the like can be used. These resins can be used singly or in combination of two or more. Of these resins, the material of the resin particles contained in the clear ink composition includes the third ink layer recording medium, the adhesion to at least one of the first ink layer and the second ink layer, and the third. From the viewpoint that at least one of the rub resistance of the ink layer can be further improved, it is more preferable that the ink layer is at least one selected from ester resins and acrylic resins. Furthermore, if the material of the resin particles contained in the clear ink composition is the same as the material of the resin particles contained in the first ink layer or the second ink layer that contacts the third ink layer, the material contacts the third ink layer. It is more preferable from the viewpoint that the adhesiveness with the ink layer can be further improved.

7.1.3. Water-soluble organic solvent The clear ink composition contains a water-soluble organic solvent. The water-soluble organic solvent is not particularly limited, and examples thereof include alkyl polyols, pyrrolidone derivatives, glycol ethers and the like. These organic solvents may be used alone or in combination of two or more. Note that specific examples, effects, content ranges, and the like of each organic solvent are the same as the contents shown in the first ink composition, and thus description thereof is omitted.

  As with the first ink composition, the clear ink composition preferably does not substantially contain a water-soluble organic solvent having a standard boiling point of 280 ° C. or higher. In addition, the water-soluble organic solvent contained in the clear ink composition is preferably a water-soluble organic solvent having a standard boiling point of 250 ° C. or lower, whether used alone or in combination of two or more. By not containing a water-soluble organic solvent having a standard boiling point exceeding 250 ° C., it is possible to maintain high drying properties of the ink.

7.1.4. Water The clear ink composition contains water. Water is a main medium of the clear ink composition, and is a component that evaporates and scatters when dried. Since the description of water is the same as that of the first ink composition, the description thereof is omitted.

  The clear ink composition can be preferably used as the above-mentioned water-based ink.

7.1.5. Other Components The clear ink composition may contain a wax, a surfactant, a pH adjuster, an antiseptic / fungicide, a chelating agent, a rust inhibitor, and the like. Specific examples of these components, effects of the respective agents, content ranges, and the like are the same as the contents shown in the first ink composition, and thus the description thereof is omitted.

7.1.6. Solid content The solid content in the clear ink composition is the resin particles, the chelating agent, the rust preventive agent, etc. present in the ink composition, as in the first ink composition described above. It represents components other than volatile components such as water and water-soluble organic solvents.

7.1.7. Water-soluble organic solvent content / solid content r3
As described above, the clear ink composition includes a water-soluble organic solvent and resin particles as a solid content. Therefore, “r3” can be defined as “water-soluble organic solvent content / solid content”. “R3” preferably has a specific relationship described later with “r1” of the first ink composition.

7.1.8. Value of “r3 / r1” When performing the step of forming the third ink layer in the ink jet recording method of this embodiment, “water-soluble organic solvent content / solid content” of the first ink composition is set. When “r1” is set and “water-soluble organic solvent content / solid content” of the clear ink composition is “r3”, the value of “r3 / r1” is preferably 2 or less. By doing so, the balance of the composition of the first ink composition and the clear ink composition is good. That is, since the value of “r3 / r1” is 2 or less, the distribution of the solvent and the remaining amount in the laminated structure of the lower layer image (for example, the first ink layer) and the uppermost layer (for example, the third ink layer) are improved. When the formed image is finally dried (for example, in the second drying step), the contraction rate of the lower layer image (for example, the first ink layer) and the contraction rate of the uppermost layer (for example, the second ink layer). However, it is not so different. Thereby, the crack in the image obtained is suppressed.

  Such an effect is obtained when the value of “r3 / r1” is 2 or less, and the value of “r3 / r1” is preferably 1.8 or less, more preferably 1.5 or less. Further, the lower limit of the value of “r3 / r1” is 0.5 or more, more preferably 0.7 or more, and further preferably 1 or more.

7.2. Third Drying Step When the inkjet recording method of the present embodiment includes a step of forming a third ink layer, a third drying step may be further included. In the third drying step, volatile components (water, alkyl polyol, glycol ether, etc.) contained in the first ink layer, the second ink layer, and the third ink layer are evaporated.

  The method and means used in the third drying step are the same as those in the post-drying step described in the second drying step. That is, in the third drying step, volatile components (water, alkyl polyol, glycol ether, etc.) contained in the first ink layer, the second ink layer, and the third ink layer are evaporated, and the recorded matter is dried to a usable state. .

  Since the drying performed in the third drying step is performed through the second drying step (first drying step 2), at least the first ink layer and the second ink layer are dried to a predetermined moisture amount. The flow of ink droplets forming one ink layer, the second ink layer, and the third ink layer can be suppressed. Accordingly, the ink droplets of the third ink composition can be kept at the location where the ink droplets are adhered, and thus bleeding (bleeding) of an image caused by excessive mixing of components contained in each layer can be suppressed.

8). Inkjet Method The inkjet recording method according to the present embodiment can be performed using an inkjet recording apparatus having a recording head. An ink jet recording apparatus used in the ink jet recording method according to the present embodiment will be described.

  The ink jet recording apparatus can be either a serial type or a line type. These types of ink jet recording apparatuses are equipped with a recording head. While changing the relative positional relationship between the recording medium and the recording head, droplets of the ink composition are ejected from the nozzle holes of the recording head. A predetermined image can be formed by ejecting the first ink composition on the recording medium at a timing and in a predetermined volume (mass).

  For the ink jet recording apparatus used in the present embodiment, for example, known configurations such as a drying unit, a roll unit, and a winding device can be employed without limitation. The ink jet recording apparatus also includes a transport unit that transports a recording medium, an ink layer forming unit that records an image (ink layer) using an ink composition, an ink layer drying unit, and an overall drying unit that heats and blows the recording surface. Etc.

  A conveyance means can be comprised with a roller, for example. The conveying means may have a plurality of rollers. As long as the conveyance means can convey the recording medium, the position and the number of the conveyance means are arbitrary. The transport unit may include a paper feed roll, a paper feed tray, a paper discharge roll, a paper discharge tray, and various platens.

  The ink layer forming means discharges the first ink composition, the second ink composition of the present embodiment, and the clear ink composition as necessary to the recording surface of the recording medium, so that the first to third inks are discharged. Record the layer. The ink layer forming means includes a recording head having nozzles, and the recording head may be different for each ink, or a nozzle row may be assigned for each ink.

  The ink layer drying means can perform at least one of the first to third drying steps. The ink layer drying means is used for drying the ink layer formed on the recording surface or removing volatile components on the recording medium. The ink layer drying means may be provided at any position in consideration of the timing for performing the first to third drying steps, the conveyance path of the recording medium, and the like. Examples of the ink layer drying means include a method of applying heat to the recording medium by heating the platen, a method of blowing air on the image on the recording medium, and a method of combining them. Specifically, means used in these methods may be forced air heating, radiation heating, conductive heating, high frequency drying, microwave drying, or the like.

9. Ink preparation method The first ink composition, the second ink composition, and the clear ink composition described above are prepared by mixing the components described above in an arbitrary order and removing impurities by filtering or the like as necessary. can get. As a method for mixing the components, a method in which materials are sequentially added to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is suitably used. As a filtration method, centrifugal filtration, filter filtration, or the like can be performed as necessary.

10. Ink physical properties The first ink composition, the second ink composition, and the clear ink composition described above have a surface tension of 15 mN / m or more at 20 ° C. from the viewpoint of a balance between image quality and reliability as an inkjet ink. It is preferably 50 mN / m, more preferably 20 mN / m or more and 40 mN / m or less. The surface tension is measured, for example, by using an automatic surface tension meter CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) and the surface when the platinum plate is wetted with the ink composition in an environment of 20 ° C. It can be measured by checking the tension.

  From the same viewpoint, the viscosity of each ink composition described above at 20 ° C. is preferably 2 mPa · s or more and 15 mPa · s or less, and more preferably 2 mPa · s or more and 10 mPa · s or less. The viscosity can be measured, for example, by using a viscoelasticity tester MCR-300 (trade name, manufactured by Pysica) under a 20 ° C. environment.

11. Examples and Comparative Examples Hereinafter, the embodiments of the present invention will be described in more detail by way of examples. However, the present embodiments are not limited to these examples.

11.1. Preparation of first ink composition, second ink composition, and clear ink composition First ink compositions 1- (1) to 1- (4), second materials having different material compositions in the material compositions shown in Table 1. Ink compositions 2- (1) to 2- (5) and clear ink compositions 3- (1) to 1- (5) were obtained. For each ink composition, the materials shown in Table 1 are put into a container, mixed with stirring with a magnetic stirrer for 2 hours, and then filtered with a membrane filter having a pore size of 5 μm to remove impurities such as dust and coarse particles. It was prepared by. The numerical values in Table 1 all indicate mass%, and ion exchange water was added so that the total mass of the clear ink composition was 100 mass%. The pigment dispersion was prepared in advance as follows. The numbers in parentheses in the table indicate the solid content in the pigment dispersion and the solid content of the resin particles supplied in the form of an emulsion. The r1, r2, and r3 shown in Table 1 were dried in the post-drying step of Example 1 after adhering each ink composition to the recording medium used in the production of the recorded material described later at an adhesion amount of 10 mg / inch ^2. The solid content of the ink composition was determined from the mass spectrometry after the measurement, and the value calculated from this and the content of the water-soluble organic solvent in the ink composition. Note that the resin dispersant contained in the cyan pigment dispersion actually includes a low molecular weight dispersant, and this may not remain as a solid content.
The values of r1, r2, and r3 in Table 1 are values obtained by rounding off the second decimal place of r1, r2, and r3. On the other hand, the values of r2 / r1 and r3 / r1 in Tables 2 to 6 are obtained by rounding the values of the third decimal place after using the values of r1, r2, and r3 having the third decimal place. It is a value obtained by calculating r2 / r1 and r3 / r1 from the obtained values having the second decimal place and rounding off the second decimal place.

<Preparation of pigment dispersion>
The first ink composition (white ink composition) used in Examples and Comparative Examples used a water-insoluble pigment (white color material) as a colorant. The second ink composition used in Examples and Comparative Examples used a water-insoluble color pigment (cyan pigment) as a colorant. When the pigment was added to each ink composition, a resin-dispersed pigment in which the pigment was previously dispersed with a resin dispersant was used. Specifically, a pigment dispersion was prepared as follows.

<Preparation of white color material dispersion>
First, 155 parts by mass of ion-exchanged water in which 1 part by mass of a 30% aqueous ammonia solution (neutralizing agent) was dissolved, an acrylic acid-acrylic acid ester copolymer (weight average molecular weight: 25,000, acid value) as a resin dispersant. : 180) 4 parts by mass was added and dissolved. Thereto, 40 parts by mass of titanium oxide (CI Pigment White 6), which is a white pigment, was added and dispersed for 10 hours in a ball mill using zirconia beads. Thereafter, centrifugal filtration using a centrifugal separator was performed to remove impurities such as coarse particles and dust, and the white pigment concentration was adjusted to 20% by mass to obtain a white color material dispersion. The particle size of the white pigment was 350 nm in terms of average particle size.

<Preparation of cyan pigment dispersion>
First, an acrylic acid-acrylic acid ester copolymer (weight average molecular weight: 25,000, as a resin dispersant) was added to 160.5 parts by mass of ion-exchanged water in which 2 parts by mass of a 30% aqueous ammonia solution (neutralizing agent) was dissolved. Acid value: 180) 7.5 parts by mass was added and dissolved. As a cyan pigment, C.I. I. 30 parts by mass of Pigment Blue 15: 3 was added, and dispersion treatment was performed for 10 hours by a ball mill using zirconia beads. Thereafter, centrifugal filtration with a centrifugal separator was performed to remove impurities such as coarse particles and dust, and the cyan pigment concentration was adjusted to 15% by mass to obtain a cyan pigment dispersion. The particle diameter of the cyan pigment at that time was 100 nm in terms of average particle diameter.

  In Table 1, materials described other than the compound names are as follows.

・ JONCRYL 1992 (trade name, manufactured by BASF Japan Ltd., styrene-acrylic acid copolymer emulsion, Tg: 78 ° C., 43% dispersion)
-Takelac W-6061 (trade name, manufactured by Mitsui Chemicals, polyurethane resin emulsion, Tg: 25 ° C., 30% dispersion)
・ Ester resin particle emulsion A
The ester resin particle emulsion A was prepared as follows. Polyoxypropylene (2.2) adduct of bisphenol A, polyoxyethylene (2.0) adduct of bisphenol A, hydrogenated bisphenol A, isophthalic acid, fumaric acid, and dibutyltin oxide as raw material monomers for polyester resin , And polymerized to obtain a polyester resin.

  10 g of this polyester resin was mixed with 200 g of methyl ethyl ketone using an anionic surfactant (trade name: “Neopelex G-15” manufactured by Kao Corporation) as a solid content, and dissolved at 25 ° C. Thereafter, 600 g of ion-exchanged water and 3.0 g of 25% ammonia water were mixed in a 2000 mL stainless steel beaker made of SUS304, and an ultrasonic homogenizer (product name: UP-400S manufactured by Dr. Heelscher) was used at 30 ° C. Distributed processing. Thereafter, the temperature was raised to 50 ° C., and methyl ethyl ketone was distilled off under reduced pressure. Thereafter, the solid content was adjusted to 30% by mass with ion-exchanged water to obtain an ester resin particle emulsion A (Tg: 60 ° C.), which was used.

・ Movinyl 972 (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Tg 101 ° C., 50% dispersion)
AQUACER 515 (trade name, manufactured by Big Chemie Japan, polyethylene wax emulsion, melting point 135 ° C., 35% dispersion)
Nopcoat PEM-17 (trade name, manufactured by San Nopco, polyethylene wax emulsion, melting point 103 ° C., 40% dispersion)
・ BYK-348 (trade name, manufactured by BYK Japan, Inc., silicone surfactant)
Surfynol DF-110D (trade name, manufactured by Air Products and Chemicals, Inc., acetylene glycol surfactant)

11.2. Preparation of recorded material Recorded materials used for each evaluation were prepared as follows.

  Recording media (soft packaging film: biaxially stretched OPP <polypropylene film>, manufactured by Futamura Chemical Co., Ltd., trade name: FOS-BT, film) The recording head was filled with the first ink composition, the second ink composition, and the clear ink composition. The printer was equipped with a blowing mechanism, a heat conduction mechanism, and a radiation heating mechanism (specifically, a blowing fan, a back platen heater, and an infrared irradiation device, respectively) as a drying mechanism.

The first ink layer was inkjet-coated on a recording medium with the ink composition described in Tables 2 to 6 (see Table 1) at a resolution of 720 × 720 dpi and an adhesion amount of 10.0 mg / inch ² to form a pattern. Formed. During and after ejection, the first ink layer was dried by heating under the drying conditions described in Tables 2-6. In Example 10, the second ink composition (color ink composition) was used for the first ink layer, and the first ink composition (white ink composition) was used for the second ink layer.

  When the moisture evaporation rate (moisture drying rate) of the first ink layer reached the value in the table by the first drying step, the second ink layer was formed to be smaller than the pattern of the first ink layer and overlapped. . In addition, the moisture evaporation rate analyzed the ink layer on the recording medium at the time of a 1st drying process with the thermal mass spectrometry (TGA: TA Instruments make, brand name: Q500). Furthermore, the analysis of the ink layer sample collected from the recording medium by liquid chromatography (trade name: XevoG2-SQTof, manufactured by Waters) was also performed. In this way, water and water-soluble organic solvent contained in the ink composition used for recording were quantified, and the evaporation amount of water and water-soluble organic solvent was calculated from comparison with the initial ink composition. At this time, the evaporation rate (drying rate) of the water-soluble organic solvent in the first ink layer was about 0% by mass when the water evaporation rate was 90% by mass or less, and about 3% by mass when the water evaporation rate was more than 90% by mass. . In addition, about the comparative example 11, 30 mass% of the water-soluble organic solvent had evaporated by setting the temperature of a 1st drying process to 70 degreeC.

  The recording resolution and adhesion amount of the second ink layer were the same as those of the first ink layer. After the adhesion, all the examples and comparative examples were subjected to the first drying step 2 (corresponding to one aspect of the second drying step of the above embodiment) under the same heating and drying conditions as the first drying step of Example 3. went.

  The total moisture evaporation rate of the first ink layer and the second ink layer in the pattern composed of the laminate of the first ink layer and the second ink layer thus dried was measured to be 95% by mass. there were.

Moreover, in the example which forms a 3rd ink layer, when the evaporation rate of the water-soluble organic solvent of the sum total of a 1st ink layer and a 2nd ink layer will be 3 mass%, it is described in Tables 3-6. The clear ink composition (see Table 1) was applied. The application amount was set to a resolution of 720 × 720 dpi and an adhesion amount of 7.0 mg / inch ² . And the 1st drying process 2 (equivalent to the one aspect | mode of the 2nd drying process of the said embodiment) was performed on the same heating conditions as the 1st drying process of Example 3. FIG.

  In the example in which the third ink layer was not formed, the recording medium was discharged from the printer after the first drying step and the second drying step (first drying step 2) were performed as described above.

  In the example in which the third ink layer was formed, the recording medium was discharged from the printer after performing the first drying step and the second drying step (first drying step 2) as described above.

  In the example in which the third ink layer is not formed, the second drying step (post-drying step: corresponding to one aspect of the second drying step in the above embodiment) is performed, and in the example in which the third ink layer is formed. The 3rd drying process (post-drying process) was performed on the conditions in a table.

  The surface temperature of the recording medium in the table was measured with a non-contact type thermometer. In the case of using a plurality of mechanisms, the temperature was measured for each place to be heated by each mechanism and listed in the table.

  In the first drying step in the table, the air blowing conditions are as follows: wind at a temperature of 40 ° C. with respect to the recorded matter being recorded, and the wind speed on the recording surface of the recording medium is 0.5 m / second or 1 m / second. The air was adjusted and adjusted. In Example 2, the heater setting of the printer paper guide (platen) at the time of recording was set to “setting at which the surface temperature of the recording surface is 40 ° C.”. Further, for the infrared irradiation, the setting of the irradiation apparatus was “a setting at which the surface temperature of the recording surface is 50 ° C. or 70 ° C.”.

  The conditions for blowing air in the second drying step (post-drying step) and the third drying step in the table are as follows. The air was adjusted to be 1 second. In addition, for the infrared irradiation, the setting of the irradiation apparatus was “a setting at which the surface temperature of the recording surface becomes 80 ° C.”.

11.3. Evaluation of recorded matter The recorded matter of each Example and Comparative Example obtained was evaluated according to the following criteria. The results are shown in Tables 2-6.

11.3.1. Bleeding evaluation Bleeding was evaluated as one of the image quality evaluations by visual observation from the recording surface side of the recorded matter. The evaluation criteria are as follows.

A: There is no bleeding / color mixing in any of the ink layers B: There is slight bleeding / color mixing in any of the ink layers C: Bleeding / color mixing is conspicuous in any of the ink layers D: Each Significant bleeding or color mixing between ink layers

11.3.2. Evaluation of cracks Cracks were evaluated visually as one of the image quality evaluations from the recording surface side of the recorded matter. The evaluation criteria are as follows. In Example 10, since the first ink layer is a color image portion and the second ink layer is a white image portion, the “second ink layer (color image portion)” of the following evaluation criteria is set to “second”. The result of evaluating by replacing “ink layer (white image portion)” and “first ink layer (white image portion)” with “first ink layer (color image portion)” is shown.

A: The second ink layer (color image portion) is not cracked at all. B: The first ink layer (white image portion) below the surface is visible due to the crack of the surface of the second ink layer (color image portion). C: There is a considerable portion where the first ink layer (white image portion) underneath is cracked on the surface of the second ink layer (color image portion). D: Second ink layer (color image) The first ink layer (white image part) under the part) is also cracked and there are places where the recording medium is visible

11.3.3. Evaluation of adhesion After leaving the recorded material in a laboratory at 20 ° C. to 25 ° C./40% RH to 60% RH for 5 hours, a transparent adhesive tape (trade name: product name: on the recording surface of the recorded material) A transparent beautiful color, manufactured by Sumitomo 3M Limited) was attached. And the adhesive tape (durability) was evaluated based on the tape peelability (peeling resistance) by peeling off the attached tape by hand and checking the ink peeling on the recording surface and the ink transfer state to the tape. . The evaluation criteria for adhesion are as follows.

A: No image peeling and no ink adhesion on the tape B: No image peeling and slight ink adhesion on the tape C: Image peeling / ink adhesion on the tape is observed D: All images are peeled off

11.3.4. Evaluation of rubbing resistance After the recorded material was left in a laboratory at 20 ° C. to 25 ° C./40% RH to 60% RH for 5 hours, the recorded surface (image forming portion) of the recorded material was subjected to Gakushin type friction fastness. By using tester AB-301 (trade name, manufactured by Tester Sangyo Co., Ltd.) by confirming the ink peeling state of the recording surface and the ink transfer state to the cotton cloth when rubbed 20 times with a cotton cloth under a load of 200 g. The rub resistance (durability) was evaluated. The evaluation criteria for abrasion resistance are as follows.

A: The image has no rubbing marks and no ink adheres to the cloth. B: The image has rubbing marks or slightly ink adhering to the cloth. C: The image rubbing marks or ink adheres to the cloth. D: The image peels off. The ink adheres to the cloth

11.4. Evaluation results The above evaluation results are shown in Tables 2 to 6.
As shown in the evaluation results of the examples in Tables 2 to 5, all the recorded materials according to the examples were excellent in the evaluation of bleeding and cracking. This is because the value of “r2 / r1” is 2 or less, the balance between the composition of the first ink composition and the second ink composition is good, and the first drying step and / or the second drying step. This is considered to be due to the fact that 80% by mass or more of the water on the recording medium at the end of (first drying step 2) was evaporated.
In Example 10, although the value of “r2 / r1” was as small as 0.6, it was found that a high-quality recorded matter was obtained although the crack evaluation was slightly inferior.
Further, in Example 38, although the crack evaluation is slightly inferior, a high-quality recorded material is obtained, but this is because the content of the water-soluble organic solvent (and the solid content) of the first ink composition is increased. However, since the value of “r2 / r1” with the second ink layer on the first ink layer is in the range of 0.5 or more and 2 or less, it is considered that cracking was good.
Moreover, when Examples 1-3 were compared, when the water evaporation rate of the 1st ink in the 1st drying process was comparatively low, it turned out that crack resistance falls a little, On the other hand, in the 1st drying process It was found that the surface temperature of the recording medium can be lowered. In addition, in the order of Examples 1, 2, and 3, it was found that the ejection stability of the recording head used in the first ink layer forming step was excellent. For ejection stability, after performing a recorded matter production test for 60 minutes continuously, a test for confirming the flying bending of the recording head used in the first ink layer forming process and the generation of defective nozzles of non-ejection nozzles is performed. Judged from the rate. For this reason, when the surface temperature of the recording medium is relatively low, there is a problem that less heat is applied to the recording medium in the first drying process, and discharge failure is generated by applying heat generated in the first drying process to the nozzle. It turned out to be preferable. Moreover, it turned out that the time which a 1st drying process requires can also be shortened. From this, it can be seen that the recording method of this embodiment is excellent in that it can perform recording with excellent crack resistance even when the water evaporation rate of the first ink in the first drying step is relatively low. It was.

  On the other hand, in the recorded matter according to Comparative Example 1 to Comparative Example 10 in Table 6, the value of “r2 / r1” exceeds 2 or the water on the recording medium at the end of the first drying step However, since less than 80% by mass was evaporated, the evaluation of bleeding and cracks (particularly cracks) was insufficient.

  In the recorded matter according to Comparative Example 11, the initial value of “r2 / r1” in the ink composition itself is more than 2, but in the first drying step after the first ink layer is printed, The amount of evaporation is higher than in the other examples, and the liquid component is reduced, so that the bleeding of the second ink layer is improved. On the other hand, the evaporation of some water-soluble organic solvents is also more than in the other examples. The value of r1 after the first drying step is expected to be lower than the initial value of the first ink itself, and therefore, the “r2 / r1” of each ink layer on the recording medium The value is higher than the initial value, and it is assumed that cracks occurred more remarkably in the second drying step (post-drying step).

Next, when the durability evaluation result is seen, from the comparison of Examples 4 and 10, the result of the abrasion resistance test was particularly improved by using an ink composition using an acrylic resin for the second ink layer.
Further, by using the recorded matter having the third ink layer, the rub resistance test result was generally better than that of the recorded matter not having the third ink layer.

  In addition, from the comparison of Examples 3, 4, and 7 among the examples, the example in which urethane resin particles or ester resin particles are used for the ink composition used for the first ink layer has the abrasion resistance. It was very good.

  Since Comparative Example 10 uses urethane resin particles in the ink composition used in the first ink layer of Example, the adhesion of the recorded material after the third drying step (post-drying step) is good. Since the second ink layer was printed at a stage where the drying of the first ink layer was insufficient (moisture evaporation rate was 5% by mass) in one drying process, the bleeding occurred remarkably.

  In addition, from the comparison of 3, 4 and 7 in the examples, when the ink composition used for the first ink layer in the examples contains urethane resin particles or ester resin particles, the adhesion is B. It turns out that it becomes the above. This is considered to be because these resin particles showed excellent adhesion to the film for soft packaging, and the adhesion of the entire image was good.

  Further, when the second ink layer is overprinted on the first ink layer (first ink composition 1- (2)) containing resin particles having a low Tg, or the second ink layer and the third ink. When the layers were overlaid, the second ink layer or the third ink layer was formed of an ink composition containing resin particles having a high Tg, whereby a tendency to improve the abrasion resistance was observed (Example 4, 5, 6, 12, 15, 18, 21, 24, 27, 30, 33, 36 and Comparative Example 10).

  Such a tendency shows that the second ink layer or the third ink layer is different from the first ink layer (first ink composition 1- (3), 1- (4)) containing resin particles having a low Tg. The same tendency was observed when the ink composition containing resin particles having a higher Tg was included, and it was found that the abrasion resistance was improved (Examples 7, 13, 16, 19, 22, 31, 38).

  From these, it is suggested that the abrasion resistance is improved by forming the ink layer on the surface side with resin particles having a higher Tg.

  Further, when the resin particles of the first ink layer are ester resin particles, and the second ink layer or the third ink layer is formed of an ink composition containing the same type of ester resin particles against the iron. However, the durability tends to be improved (see Examples 8, 9, 16, 19, 22, 25, 28, 31, 34, 37). From this, it was suggested that the bonding force between the ink layers was strengthened by overlapping the ink compositions containing the ester resin particles.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (19)

Forming a first ink layer by ejecting a first ink composition containing water, a water-soluble organic solvent, and a solid content containing at least a coloring material on a recording medium by an inkjet method;
A first drying step of evaporating 80% by mass or more of water contained in the first ink composition in the first ink layer;
A second ink composition containing water, a water-soluble organic solvent, and a solid content containing at least a coloring material is ejected to the first ink layer that has undergone the first drying step by an ink jet method. Forming a step;
A second drying step of evaporating a volatile component of the recording medium on the recording medium that has undergone the step of forming the second ink layer;
With
The “water-soluble organic solvent content / solid content” of the first ink composition is “r1”, and the “water-soluble organic solvent content / solid content” of the second ink composition is “r2”. In the inkjet recording method, the value of “r2 / r1” is 2 or less. In claim 1,
The inkjet recording method, wherein the recording medium is an ink low-absorbing or non-ink-absorbing recording medium. In claim 1 or claim 2,
The first ink composition is a background image ink composition containing at least one of metal compound particles and metal particles as a colorant,
The inkjet recording method, wherein the second ink composition is a colored ink composition containing a non-white color material. In any one of Claims 1 to 3,
The said 1st drying process is an inkjet recording method performed by the surface temperature of the said recording medium being 25 degreeC or more and 50 degrees C or less. In any one of Claims 1 thru | or 4,
The ink-jet recording method, wherein the first ink composition contains resin particles as the solid content. In any one of Claims 1 thru | or 5,
The ink jet recording method, wherein the second ink composition contains resin particles as the solid content. In claim 5 or claim 6,
The ink jet recording method, wherein the resin particles are at least one of urethane resin particles, ester resin particles, and acrylic resin particles. In any one of Claims 5 thru | or 7,
The first ink composition includes at least one of urethane resin particles and ester resin particles,
The inkjet recording method, wherein the second ink composition contains at least one of ester resin particles and acrylic resin particles. In claim 7 or claim 8,
The ester resin particles are
An inkjet recording method comprising a polyester resin which is a graft polymer comprising a main chain segment (A1) made of a polyester resin and a side chain segment (A2) made of an addition polymerization resin. In any one of Claims 1 thru | or 9,
The inkjet recording method, wherein the “r2 / r1” is 0.5 or more and 2 or less. In any one of Claims 1 thru | or 10,
The ink jet recording method, wherein the first drying step is performed with an evaporation amount of a water-soluble organic solvent contained in the first ink composition in the first ink layer being 20% by mass or less. In any one of Claims 1 thru | or 11,
The first drying step is performed by at least one of heat conduction, radiation irradiation, and air blowing.
Inkjet recording method. In any one of Claims 1 thru | or 12,
The second drying step is an ink jet recording method in which a surface temperature of the recording medium is 70 ° C. or higher. In any one of Claims 1 thru | or 12,
After performing the second drying step, a third ink layer is formed by discharging a clear ink composition containing resin particles, a water-soluble organic solvent, and water to the second ink layer by an inkjet method. An inkjet recording method comprising a step. In claim 14,
The inkjet recording method, wherein “r3 / r1” is 2 or less when “water-soluble organic solvent content / solid content” of the clear ink composition is “r3”. In claim 14 or claim 15,
The step of forming the third ink layer is performed after evaporating 80% by mass or more of the total water contained in the first ink composition and the second ink composition in the second drying step. Inkjet recording method. In any one of claims 14 to 16,
An ink jet recording method, wherein a third drying step of evaporating volatile components on the recording medium is performed after the step of forming the third ink layer. In any one of Claims 1 thru | or 17,
In the first ink composition and the second ink composition, the resin particles are 1% by mass to 15% by mass, the water-soluble organic solvent is 3% by mass to 40% by mass, and the coloring material is 0.5% by mass or more. An ink jet recording method comprising 15% by mass or less. In any one of Claims 1-18,
The inkjet recording method, wherein the water-soluble organic solvent includes a water-soluble organic solvent having a boiling point of 250 ° C. or less.