JP2015091660A - Inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording method which, when an image is recorded on an ink-non-absorbent or ink-low-absorbent recording medium using an aqueous ink composition, enables blurring in the image to be reduced and the image excellent in scratch resistance to be obtained.SOLUTION: The inkjet recording method is provided which comprises the steps of: heating an ink-non-absorbent or ink-low-absorbent recording medium at a temperature of 40°C or more to 60°C or less and ejecting droplets of an aqueous ink composition onto the recording medium; and heating the recording medium at a temperature of 50°C or more to 90°C or less and drying the droplets of the aqueous ink composition ejected onto the recording medium. In the inkjet recording method, recording is performed using the aqueous ink composition containing at least water insoluble colorant, thermoplastic resin particles, a first solvent made of glycol diethers having a boiling point ranging from 150°C or more to 220°C or less, a second solvent made of at least one kind selected from the group of 1,2-cyclohexanediol and 1,2-pentanediol, a third solvent made of glycols having a boiling point ranging from 170°C or more to 220°C or less and water.

Description

  The present invention relates to a recording method for performing inkjet recording with a water-based ink on a non-absorbing or low-absorbing recording medium whose recording surface does not absorb ink such as plastic.

  Conventionally, as a recording method for a recording medium that does not absorb ink or a low-absorbing recording medium, a non-aqueous ink mainly containing an organic solvent has been used. Non-aqueous inks have excellent advantages such as fast drying, water resistance, and prevention of image bleeding.However, since the solvent is volatilized on the surface of the recording medium, an image is formed. And toxicity was a problem. Furthermore, there were concerns about the environmental impact of organic solvents. Therefore, there is a demand for a recording method using water-based ink from the viewpoint of safety and environmental protection even for a non-ink-absorbing recording medium.

  For example, Patent Document 1 discloses an ink jet recording method in which a non-aqueous ink-jet ink is recorded on a recording medium having a resin base material that does not contain a plasticizer or a non-absorbing inorganic base material as a constituent element. An inkjet ink containing a pigment, a fixing resin, and a specific compound, which is excellent in work safety, has no odor problems, has excellent drying properties after recording, and records an image having sharp and sufficient scratch resistance. You can do that. However, the ink contains a total of 80% by mass or more of diethylene glycol diethyl ether, ethylene glycol diacetate, etc. as examples of the main solvent, and it is clear that the safety is remarkably lower than that of the water-based ink. Furthermore, the environmental impact of a large amount of volatilized solvent is also great.

  An aqueous heat-fixing ink that can be used with water-based ink-jet inks and has good high-speed print image quality that does not cause spots on non-absorbent recording media and can be used stably over a long period of time, and a heat-fixing ink-jet recording method using the same, for example, It is disclosed in Patent Document 2. The addition amount of the organic solvent is 10 to 35% by mass, and diethylene glycol diethyl ether is mentioned as an example of the organic solvent. The combination of a specific organic solvent and a water-soluble resin suppresses the occurrence of spots and provides good image quality. However, in the recording performed with the ink composition described in Patent Document 2, when recording with a water-based ink on a non-absorbent recording medium, it is not possible to obtain a sufficient strength with respect to scratch resistance which is inferior to that of a non-water-based ink.

JP 2008-303235 A JP 2008-260820 A

    One of the objects of some aspects of the present invention is to produce an image with less ink bleeding and high image quality and excellent scratch resistance on a recording medium having a non-absorbing or low-absorbing recording surface. It is to provide an ink jet recording method.

  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.

[Application Example 1] One aspect of the ink jet recording method according to the present invention is as follows.
A first step of heating a non-ink-absorbing or low-absorbing recording medium to a temperature range of 40 ° C. or higher and 60 ° C. or lower by an ink jet recording apparatus and discharging droplets of the aqueous ink composition; A second step of heating to a temperature range of 50 ° C. or higher and 90 ° C. or lower and drying the water-based ink composition ejected onto the recording medium,
The water-based ink composition is selected from water, at least one water-insoluble colorant, water-insoluble thermoplastic resin particles, a surfactant, and a glycol diether having a boiling point of 150 ° C. or higher and 220 ° C. or lower. At least one first solvent, at least one second solvent selected from 1,2-hexanediol and 1,2-pentanediol, and glycols having a boiling point in the range of 170 ° C. or higher and 220 ° C. or lower. Containing at least one third solvent selected from
The content of the first solvent in the aqueous ink composition (W ₁₎ is 5 to 20 wt%,
The content (W ₂ ) of the second solvent in the water-based ink composition is 3 to 10% by mass,
The content (W ₃ ) of the third solvent in the water-based ink composition is 5 to 15% by mass,
The total content (W ₂ + W ₃ ) of the second solvent and the third solvent is 22% by mass or less.

  According to the ink jet recording method of this application example, it is possible to reduce bleeding of an image formed on a non-ink-absorbing recording medium, and it is possible to obtain a record excellent in scratch resistance and quick drying of a recorded matter.

Application Example 2 In the ink jet recording method described in the application example,
The glycol diether as the first solvent is at least one selected from diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol butyl methyl ether, and triethylene glycol dimethyl ether.

Application Example 3 In the ink jet recording method described in the application example,
The glycol as the third solvent is at least one selected from propylene glycol and 1,3-propanediol.

Application Example 4 In the ink jet recording method described in the application example,
The water-insoluble colorant is a pigment and is characterized by being dispersed in a water-based ink composition with a water-soluble resin.

Application Example 5 In the ink jet recording method according to the application example,
The water-insoluble thermoplastic resin particles are an acrylic resin or a styrene-acrylic acid copolymer resin.

Application Example 6 In the ink jet recording method according to the application example,
The surfactant is a silicon-based surfactant.

Application Example 7 In the ink jet recording method according to the application example,
The recording medium is heated by a heater or hot air.

  Hereinafter, preferred embodiments of the present invention will be described. The embodiment described below describes an example of the present invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

1. Inkjet Recording Method An inkjet recording method according to an embodiment of the present invention is an aqueous ink composition in which an ink non-absorbing or low-absorbing recording medium is heated to a temperature range of 40 ° C. or more and 60 ° C. or less by an inkjet recording apparatus. And a second step of drying the water-based ink composition discharged on the recording medium by heating the recording medium to a temperature range of 50 ° C. or higher and 90 ° C. or lower. The water-based ink composition comprises water, at least one water-insoluble colorant, water-insoluble thermoplastic resin particles, a surfactant, and a boiling point of 150 ° C. or higher and 220 ° C. A first solvent consisting of at least one selected from the following glycol diethers and selected from 1,2-hexanediol and 1,2-pentanediol The first solvent in the water-based ink composition, and a second solvent selected from glycols having a boiling point of 170 ° C. or higher and 220 ° C. or lower. The content (W ₁ ) of the solvent is 5 to 20% by mass, the content (W ₂ ) of the second solvent in the aqueous ink composition is 3 to 10% by mass, and the aqueous ink composition The content (W ₃ ) of the third solvent is 5 to 15% by mass, and the total content (W ₂ + W ₃ ) of the second solvent and the third solvent is 22% by mass or less. It is characterized by being. In the present invention, “image” indicates a print pattern formed from a group of dots, and includes text printing and solid printing.

1.1. Inkjet Recording Process An inkjet recording method according to an embodiment of the present invention is a water-based ink composition in which an ink non-absorbing or low-absorbing recording medium is heated to a temperature range of 40 ° C. or more and 60 ° C. or less by an inkjet recording apparatus. And a second step of drying the water-based ink composition discharged on the recording medium by heating the recording medium to a temperature range of 50 ° C. or higher and 90 ° C. or lower. It is characterized by including.

  The inkjet recording apparatus is not particularly limited as long as it can perform recording by ejecting ink droplets and adhering the droplets onto the recording medium, but has a function of heating the recording medium during printing. It is preferable. Here, “when printing” means that after a recording medium is transported to a paper guide section of an ink jet recording apparatus, ink droplets are ejected by the ink jet recording apparatus and the liquid droplets are deposited on the recording medium. The time until the recording medium is transported to the ink drying mechanism.

  Functions that can heat the recording medium include, for example, a print heater function that heats the recording medium by directly contacting the heat source, and infrared rays and microwaves (electromagnetic waves having a maximum wavelength of about 2,450 MHz) without directly contacting the recording medium. Such as a dryer function that irradiates and blows warm air. The print heater function and the dryer function can be used independently or simultaneously. Thereby, the drying temperature at the time of printing can be adjusted.

  Alternatively, ink droplets may be ejected by an ink jet recording apparatus, and the recording medium to which the droplets are attached may be dried by a dryer or a thermostat set to a predetermined temperature.

  As the recording medium, a non-ink-absorbing or low-absorbing recording medium is used. As a non-ink-absorbing recording medium, for example, a plastic film coated on a substrate such as a plastic film or paper that has not been surface-treated for inkjet printing (that is, an ink-absorbing layer is not formed). And those having a plastic film adhered thereto. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. Examples of the recording medium having low ink absorption include printing paper such as art paper, coated paper, and matte paper.

Here, in this specification, “ink non-absorbing or low-absorbing recording medium” means “the amount of water absorption from the start of contact to 30 msec ^1/2 in the Bristow method is 10 mL / m ² or less. Recording medium ". 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".

  An ink jet recording method using an ink jet recording apparatus can be performed, for example, as follows. First, a water-based ink composition (described later) is ejected as droplets onto a recording medium heated to a temperature range of 40 ° C. to 60 ° C. As a result, an image can be formed on the recording medium. Any of the conventionally known methods can be used as the inkjet ejection method, and in particular, a method of ejecting droplets using the vibration of a piezoelectric element (using an inkjet head that forms ink droplets by mechanical deformation of an electrostrictive element). In the recording method, excellent image recording can be performed.

  Next, the recording medium is heated to a temperature range of 50 ° C. or more and 90 ° C. or less by a print heater and a dryer provided in the ink jet recording apparatus, and an aqueous ink composition (described later) discharged on the recording medium is dried. . By this step, moisture or the like contained in the aqueous ink composition discharged onto the recording medium is quickly evaporated and scattered, and a film is formed by resin particles (described later) contained in the aqueous ink composition. As a result, a high-quality image with little shading and blurring can be obtained in a short time on the recording medium, and the image is fixed because the dried ink adheres to the recording medium by forming a resin particle coating. To do.

  The heating temperature range of the recording medium is 50 ° C. or higher and 90 ° C. or lower. If the heating temperature of the recording medium is 50 ° C. or higher, it is possible to effectively promote evaporation and scattering of the liquid medium in the aqueous ink composition. As the heating temperature at this time, the higher the temperature, the faster drying, the abrasion resistance, and the reduction of image bleeding are more advantageous. However, when the heating temperature of the recording medium exceeds 90 ° C., deformation may occur depending on the type of the recording medium, and problems such as shrinkage of a recorded image may occur when the recording medium is heated and cooled. In addition, there are undesirable problems such as an increase in power consumption of the heater used for heating and an increase in exhaust heat from the ink jet printer due to the heating mechanism. Based on these problems, the upper limit of the heating temperature of the recording medium is 90 ° C. It is preferable that

  The heating time of the recording medium is not particularly limited as long as the liquid medium present in the water-based ink composition is evaporated and scattered, and a film of the resin fixing agent can be formed, taking into account the solvent used, resin particles, printing speed, and the like. And can be set as appropriate.

1.2. Hereinafter, the water-based ink composition used in the ink jet recording method according to the embodiment of the present invention will be described in detail.

1.2.1. Solvent The water-based ink composition used in the ink jet recording method according to the present embodiment includes a first solvent composed of at least one selected from glycol diethers having a boiling point of 150 ° C. or higher and 220 ° C. or lower, and 1,2-hexane. A second solvent composed of at least one selected from diols and 1,2-pentanediol; and a third solvent composed of at least one selected from glycols having a boiling point of 170 ° C. or higher and 220 ° C. or lower.

  The first solvent consisting of at least one selected from glycol diethers having a boiling point of 150 ° C. or higher and 220 ° C. or lower is selected from a solvent having a lower boiling point than the second solvent, and an aqueous ink composition for ink jet recording. As a result, the first solvent is volatilized together with the third solvent in the initial stage of the second step of heat drying, and the drying of the ink on the recording medium is accelerated. High ink drying properties can reduce the time and heating temperature required for heating and drying, and also improve the image quality by reducing unevenness and bleeding due to ink aggregation.

  In addition, the first solvent consisting of at least one selected from glycol diethers slowly dissolves or swells the thermoplastic resin particles, and the ink is adhered to the recording medium until the solvent volatilizes. It has an effect of fixing a solidified product mainly composed of a colorant which is a non-volatile component in the composition together with thermoplastic resin particles.

  The solubility of the thermoplastic resin particles of glycol diether can be determined by the following method. A glass plate on which 0.05 g of an emulsion in which thermoplastic resin particles are dispersed in water is dropped on a glass plate and left to stand at room temperature for one day to evaporate water, and then a residue of a solidified thermoplastic resin particle is adhered to the glass plate. Is immersed in a container containing glycol diether, and the state of the solidified product is observed. If there is no change in the state, there is no solubility, and if the solidified product is white turbid, cracked, softened, swollen, or melted out, it can be determined that the thermoplastic resin particles are soluble.

  The glycol diether having a boiling point of 150 ° C. or higher and 220 ° C. or lower having the thermoplastic resin particle solubility selected by the determination method is diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, or triethylene glycol dimethyl ether. . Of these, diethylene glycol diethyl ether and triethylene glycol dimethyl ether having a boiling point of 190 ° C. or higher and 220 ° C. or lower are particularly preferable.

The content (W ₁ ) of the first solvent is 5% by mass or more and 20% by mass or less with respect to the total mass of the aqueous ink composition. Further, the content (W ₁ ) of the first solvent is more preferably 7% by mass or more and 14% by mass or less with respect to the total mass of the aqueous ink composition.

By setting the content (W ₁ ) of the first solvent in the water-based ink composition to 5% by mass or more, an image formed on a non-ink-absorbing or low-absorbing recording medium has good abrasion resistance. Have Further, when the content (W ₁ ) of the first solvent in the aqueous ink composition is 7% by mass or more, an image formed on a non-ink-absorbing or low-absorbing recording medium is further improved. Shows abrasion resistance. Further, if the content (W ₁ ) of the first solvent in the aqueous ink composition is 20% by mass or less, the solvent odor generated in the heating process of the printed matter can be sufficiently reduced. Further, if the content (W ₁ ) of the first solvent in the aqueous ink composition is 14% by mass or less, the solvent odor generated in the heating step can be further reduced. On the other hand, when the content (W ₁ ) of the first solvent in the water-based ink composition exceeds 20% by mass, the solvent volatilizes in a short time in the heating step and the solvent odor increases, which is not preferable.

  The second solvent consisting of at least one selected from 1,2-hexanediol and 1,2-pentanediol further enhances the wettability of the aqueous ink composition with respect to the recording medium in synergy with the surfactant. It is a low surface tension solvent that has the effect of uniformly wetting the ink on the recording medium. Here, the solvent having a low surface tension refers to a solvent having a surface tension at room temperature of 40 mN / m or less. By uniformly wetting the ink on the recording medium, it is possible to reduce unevenness in color density and bleeding of the ink on the recording medium.

  Since the second solvent has an excellent effect of uniformly wetting the ink on the recording medium with respect to the recording medium made of non-absorbing plastic on the recording surface, bleeding of the formed image is reduced.

The content (W ₂ ) of the second solvent is 3% by mass or more and 10% by mass or less with respect to the total mass of the aqueous ink composition. Further, the content (W ₂ ) of the second solvent is more preferably 4% by mass or more and 8% by mass or less with respect to the total mass of the aqueous ink composition.

When the content (W ₂ ) of the first solvent in the aqueous ink composition is 7% by mass or more, the content (W ₂ ) of the second solvent in the aqueous ink composition is 4% by mass or more. By doing so, blurring of the image is further reduced. Further, when the content (W ₂ ) of the second solvent in the aqueous ink composition is 8% by mass or less, the image on the recording medium can be dried more quickly. On the other hand, when the content (W ₂ ) of the second solvent in the water-based ink composition is less than 3% by mass, the wettability of the ink with respect to the non-absorbing recording medium becomes poor, and good image quality is obtained. There may not be. On the other hand, when the content (W ₂ ) of the second solvent in the water-based ink composition exceeds 10% by mass, the solvent hardly evaporates and the image may not be sufficiently dried.

  The aqueous ink composition used in the printing method according to the present embodiment contains a third solvent selected from propylene glycol and 1,3-propanediol. One of the functions of the third solvent is to prevent the ink from being dried and solidified on the nozzle surface of the inkjet head to prevent nozzle clogging, ink ejection failure, and the like. Another function of the third solvent is to suppress the evaporation of water in the water-based ink composition and prevent aggregation and precipitation of solids such as pigments and resin components in the ink. Can be mentioned. The boiling point of propylene glycol is about 188 ° C, and the boiling point of 1,3-propanediol is about 213 ° C.

The content (W ₃ ) of the third solvent is 5% by mass or more and 15% by mass or less with respect to the total amount of the aqueous ink composition. If the content (W ₃ ) of the third solvent in the water-based ink composition is less than 5% by mass, nozzle clogging may easily occur. On the other hand, if the content (W ₃ ) of the third solvent in the aqueous ink composition exceeds 15% by mass, the image quality of the printed matter may be deteriorated due to a decrease in the drying speed of the ink. In some cases, the solidification / fixing of the ink is hindered and the rubbing resistance of the printed matter is lowered.

The total content (W ₂ + W ₃ ) of the second solvent and the third solvent in the aqueous ink composition is 22% by mass or less based on the total mass of the aqueous ink composition. When the total content of the second solvent and the third solvent (W ₂ + W ₃ ) exceeds 22% by mass, the solvent does not sufficiently evaporate in the heating step of drying the recording medium, and the image resistance is reduced. Reduces rubbing properties.

1.2.2. Colorant The aqueous ink composition used in the ink jet recording method according to the present embodiment contains a water-insoluble colorant. Water-insoluble colorants include water-insoluble dyes or pigments, with pigments being preferred. The pigment is not only insoluble or hardly soluble in water, but also has a property of not easily fading to light, gas, or the like. For this reason, a recorded matter printed with an ink composition using a pigment is excellent in water resistance, gas resistance, light resistance and the like, and has good storage stability.

  The water-based ink composition can contain any pigment conventionally used in water-based inkjet recording ink compositions. As the pigment, for example, an organic pigment or an inorganic pigment conventionally used in an ink composition for inkjet recording can be used.

  As the inorganic pigment, titanium oxide and iron oxide, or carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used.

  Examples of organic pigments include azo pigments (for example, azo lakes, insoluble azo pigments, condensed azo pigments, or chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, verinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, A thioindigo pigment, an isoindolinone pigment, or a quinophthalone pigment), a dye chelate (for example, a basic dye chelate or an acid dye chelate), a nitro pigment, a nitroso pigment, or aniline black can be used. Of these pigments, it is preferable to use a pigment having good affinity with water.

  More specifically, as a pigment for black ink, for example, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, or channel black, or copper oxide, iron oxide ( And CI pigment black 11), metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).

  Specific examples of suitable carbon black include carbon black manufactured by Mitsubishi Chemical Corporation, No. 2300, 900, MCF88, no. 20B, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B and the like. Examples of carbon blacks manufactured by Degussa include color blacks FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pretex 35, U, V, 140U, Special Black 6, 5, 4A, 4, 250, etc. It is done. Examples of carbon black manufactured by Columbia Carbon include Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, and the like. Examples of the carbon black manufactured by Cabot include Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 400, Elftex 12 and the like manufactured by Cabot.

  Examples of color ink pigments include C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 23, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 74, 81, 83 (Disazo Yellow HR), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 151, 154, 155, 180, 185, 213; I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 92, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, violet 1 (rhodamine lake), 3, 5: 1, 16, 1 (Quinacridone red), 23 and 38; or C. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 56 , 60, 63; and the like.

  The particle diameter of the pigment is not particularly limited, but the average particle diameter is preferably 25 μm or less, more preferably 2 μm or less. By using a pigment having an average particle diameter of 25 μm or less, the occurrence of clogging can be suppressed, and further sufficient ejection stability can be realized.

  The pigment content is preferably 0.5 to 15% by mass, more preferably 1.0 to 10.0% by mass, based on the entire ink composition.

  Various methods can be applied to the above pigment in order to make it more stably dispersed and retained in the aqueous ink composition. As the method, for example, a method of dispersing using a water-soluble resin, a method of dispersing using a surfactant, a hydrophilic functional group is chemically and physically introduced on the surface of pigment particles, and then dispersed and / or dissolved. The method etc. which make it possible are mentioned. Any of the above-described methods can be used for the water-based ink composition used in the printing method according to the present embodiment, and the methods can be used in a combined form as necessary. In particular, in a method in which a pigment is dispersed in a water-based ink composition by a water-soluble resin, when the water-based ink recording material adheres to the recording medium, the recording medium and the ink composition and / or solidification in the ink composition is performed. It may increase the adhesion between objects, which is preferable. In addition, a method in which a hydrophilic functional group is chemically and physically introduced on the surface of pigment particles to disperse the pigment in the aqueous ink composition improves the dispersion stability of the pigment, and the storage stability of the aqueous ink composition. Is preferable in terms of improving the quality.

  Water-soluble resins that can be used for pigment dispersion include polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylic acid ester copolymers, acrylic acid-acrylic acid ester copolymers. Polymer, 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, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, vinyl acetate-maleic acid Acid ester copolymer, vinyl acetate-crotonic acid copolymer , Vinyl acetate-acrylic acid copolymer, and salts thereof. Among these, a copolymer of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and a polymer comprising a monomer having both a hydrophobic functional group and a hydrophilic functional group are particularly 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.

  Examples of the salt include bases such as ammonia, ethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolamine, triethanolamine, tri-iso-propanolamine, aminomethylpropanol, and morpholine. And a salt with a functional compound. The addition amount of these basic compounds is not particularly limited as long as it is not less than the neutralization equivalent of the water-soluble resin.

  The molecular weight of the water-soluble resin that can be used for dispersing the pigment is preferably in the range of 1,000 to 100,000, more preferably in the range of 3,000 to 10,000, as the weight average molecular weight. When the molecular weight is in the above range, a stable dispersion of the colorant in water can be obtained, and viscosity control when applied to an aqueous ink composition is easy. Moreover, it is preferable that it is the range of 50-300 as an acid value, and it is more preferable that it is the range of 70-150. When the acid value is within this range, the dispersibility of the colorant particles in water can be stably secured, and the water resistance of the printed matter printed with the aqueous ink composition using the colorant particles is good.

  Commercially available products can also be used as the water-soluble resin that can be used for dispersing the pigment described above. Specifically, Joncryl 67 (weight average molecular weight: 12,500, acid value: 213), Joncryl 678 (weight average molecular weight: 8,500, acid value: 215), Joncryl 586 (weight average molecular weight: 4,600) , Acid value: 108), joncryl 611 (weight average molecular weight: 8,100, acid value: 53), joncryl 680 (weight average molecular weight: 4,900, acid value: 215), joncryl 682 (weight average molecular weight) : 1,700, acid value: 238), joncryl 683 (weight average molecular weight: 8,000, acid value: 160), joncryl 690 (weight average molecular weight: 16,500, acid value: 240) , Manufactured by BASF Japan Ltd.).

  Surfactants that can be used to disperse the pigments include alkane sulfonates, α-olefin sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, acylmethyl taurates, dialkyl sulfosuccinates Anionic surfactants such as alkyl sulfate ester salts, sulfated olefins, polyoxyethylene alkyl ether sulfate ester salts, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphate ester salts, monoglycerite phosphate ester salts, Amphoteric surfactants such as alkyl pyridium salts, alkyl amino acid salts, alkyl dimethyl betaines, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylenes Alkylene alkyl amides, glycerol alkyl esters, nonionic surfactants such as sorbitan alkyl esters.

  The amount of the water-soluble resin or the surfactant that can be used for dispersing the pigment to the pigment is preferably 1% by mass to 100% by mass, more preferably 5% by mass to 50% by mass with respect to 1% by mass of the pigment. %. By being in this range, the dispersion stability of the pigment in water can be ensured.

As a method of introducing a hydrophilic functional group into the pigment particle surface chemically and physically so that the pigment can be dispersed and / or dissolved, the hydrophilic functional group can be -OM, -COOM, -CO-, -SO as a hydrophilic functional group in the pigment. ₃ M, —SO ₂ NH ₂ , —RSO ₂ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NHCOR, —NH ₃ , —NR ₃ (wherein M is a hydrogen atom, an alkali Represents a metal, ammonium, or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group. The method to introduce is mentioned. These functional groups are physically and / or chemically introduced by grafting directly to the pigment particle surface and / or via other groups. Examples of the polyvalent group include an alkylene group having 1 to 12 carbon atoms, a phenylene group which may have a substituent, or a naphthylene group which may have a substituent.

Further, as the surface treatment method, a sulfur-containing treatment agent is used to cause -SO ₃ M and / or -RSO ₂ M (M is a counter ion, hydrogen ion, alkali metal ion, ammonium ion) on the pigment particle surface. Or an organic ammonium ion)) that has been surface-treated so as to chemically bond, that is, the pigment does not have an active proton, has no reactivity with sulfonic acid, and the pigment is insoluble or hardly soluble. In the solvent, the pigment is dispersed, and then surface treatment is performed so that —SO ₃ M and / or —RSO ₂ M are chemically bonded to the particle surface by amidosulfuric acid or a complex of sulfur trioxide and tertiary amine. More preferably, it can be dispersed and / or dissolved in water.

  Various known surface treatment means can be applied as the surface treatment means for grafting the functional group or a salt thereof directly on the surface of the pigment particles or via a polyvalent group. For example, means for treating a commercially available oxidized carbon black with ozone or a sodium hypochlorite solution to further oxidize the carbon black to make the surface more hydrophilic (for example, JP-A-7-258578, JP-A-H10-238707). 8-3498, JP-A-10-120958, JP-A-10-195331, JP-A-10-237349), means for treating carbon black with 3-amino-N-alkyl-substituted pyridium bromide ( For example, JP-A-10-195360 and JP-A-10-330665), an organic pigment is dispersed in a solvent in which the organic pigment is insoluble or hardly soluble, and a sulfone group is introduced onto the pigment particle surface by a sulfonating agent. Means (for example, JP-A-8-283596, JP-A-10-110110, JP-A-10-1101 No. 1), means for dispersing an organic pigment in a basic solvent that forms a complex with sulfur trioxide, treating the surface of the organic pigment by adding sulfur trioxide, and introducing a sulfone group or a sulfonamino group (For example, Unexamined-Japanese-Patent No. 10-110114) etc. are mentioned, However, The preparation means for the surface treatment pigment used by this invention is not limited to these means.

  The functional group grafted on one pigment particle may be single or plural kinds. The type and degree of the functional group to be grafted may be appropriately determined in consideration of the dispersion stability in the ink, the color density, the drying property on the front surface of the inkjet head, and the like.

  As a method of dispersing the pigment in water, the pigment, water, and water-soluble resin are used for the resin dispersant, the pigment, water, and surfactant are used for the surfactant, and the pigment and water are used for the surface-treated pigment. Add water-soluble organic solvent / neutralizer, etc. as necessary to ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc. Can be carried out with a disperser. In this case, as described above, the average particle size of the pigment is preferably 25 μm or less, more preferably 2 μm or less, as described above, from the viewpoint of ensuring dispersion stability of the pigment in water. .

1.2.3. Thermoplastic resin particles The water-based ink composition used in the ink jet recording method according to the present embodiment contains thermoplastic resin particles. The thermoplastic resin particles solidify the ink in the step of heating the recording medium to a temperature range of 50 ° C. or more and 90 ° C. or less, and drying the water-based ink composition ejected on the recording medium. It has the effect of firmly fixing the solidified material on the recording medium. Due to this action, a recorded matter recorded with an aqueous ink composition containing resin particles is excellent in abrasion resistance on a non-ink-absorbing or low-absorbing recording medium.

  The thermoplastic resin particles may be added so as to be completely dissolved in the water-based ink composition, or may be contained as particles that are dispersed as particles, that is, in an emulsion state or a suspension state. . The aqueous ink composition used in the ink jet recording method according to this embodiment is preferably contained as resin particles in an emulsion state or a suspension state. By containing the resin particles in an emulsion state or suspension state, the viscosity of the aqueous ink composition can be easily adjusted to an appropriate range in the ink jet recording method according to the present embodiment, so that storage stability and ejection stability are improved. Easy to secure.

  Examples of components of the thermoplastic resin particles include acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, vinyl pyrrolidone, Examples include vinyl pyridine, vinyl carbazole, vinyl imidazole, homopolymers or copolymers of vinylidene chloride, fluororesins, natural resins, and the like. The copolymer can be used in any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer. The thermoplastic resin particles are preferably acrylic resin or styrene-acrylic acid copolymer resin.

  As said resin particle, the thing obtained by a well-known material and method can also be used. For example, those described in JP-B-62-1426, JP-A-3-56573, JP-A-3-79678, JP-A-3-160068, JP-A-4-18462 and the like can be used. Good. Commercially available products can also be used. For example, Microgel E-1002, Microgel E-5002 (trade name, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001, Boncoat 5454 (trade name, Dainippon Ink and Chemicals, Inc.) Co., Ltd.), SAE1014 (trade name, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (trade name, manufactured by Seiden Chemical Co., Ltd.), Jongkrill 7100, Jongkrill 390, Jongkrill 711, Jongkrill 511, Jongkrill 7001, John Crill 632, John Crill 741, John Crill 450, John Crill 840, John Crill 74J, John Crill HRC-1645J, John Crill 734, John Crill 852, John Crill 7600, John Crill 775, John Crill 537J John Crill 1535, John Crill PDX-7630A, John Crill 352J, John Crill 352D, John Crill PDX-7145, John Crill 538J, John Crill 7640, John Crill 7641, John Crill 631, John Crill 790, John Crill 780, John Crill 7610 (trade name, manufactured by BASF Japan Ltd.) and the like.

1.2.4. Surfactant The water-based ink composition used in the ink jet recording method according to the present embodiment contains a surfactant. The surfactant has an action of uniformly spreading the ink so as not to cause unevenness of ink density and bleeding on the recording medium.

  The surfactant is preferably a silicon-based surfactant. As the silicon-based surfactant, a polysiloxane compound or the like is preferably used, and examples thereof include polyether-modified organosiloxane. Moreover, a commercial item can be used, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (above, trade name, manufactured by Big Chemie Japan Co., Ltd.) 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 (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

1.2.5. Water The water-based ink composition used in the ink jet recording method according to this embodiment contains water. Water is a main medium of the water-based ink composition, and is a component that is evaporated and scattered in the above-described drying step.

  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, when water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, it is preferable because the generation of mold and bacteria can be prevented when the pigment dispersion and the aqueous ink composition using the same are stored for a long period of time. is there.

1.2.6. Other Solvent Components The aqueous ink composition used in the ink jet recording method according to this embodiment can further contain a solvent having a moisturizing action or a low surface tension. For example, ethylene glycol monobutyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono -N-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene Glycol mono-n-propyl ether, propylene glycol mono-iso Propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, methanol, ethanol, n-propyl alcohol, iso -Propyl alcohol, 2,2-dimethyl-1-propanol, n-butanol, 2-butanol, tert-butanol, iso-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl- 2-butanol, n-pentanol, 2-pentanol, 3-pentanol, tert-pentanol, N-methyl-2-pyrrolidone, tetramethylurea, dimethyl sulfoxide, 2-pyrrolidone, 1,3-dimethyl - imidazolidinone, N, include water-soluble solvents such as N'- dimethylpropyleneurea.

1.2.7. Other Ingredients The aqueous ink composition used in the ink jet recording method according to the present embodiment can further contain a pH adjuster, an antiseptic / fungicide, a rust inhibitor, a chelating agent, and the like.

  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 (above trade name, manufactured by Avicia), Denside CSA, NS-500W (above trade name, manufactured by Nagase ChemteX Corporation), and the like.

  Examples of the rust inhibitor include benzotriazole.

  Examples of the chelating agent include ethylenediaminetetraacetic acid and salts thereof (such as ethylenediaminetetraacetic acid dihydrogen disodium salt).

1.2.7 Physical Properties The viscosity at 20 ° C. of the aqueous ink composition used in the ink jet recording method according to the present embodiment is preferably 2 mPa · s to 10 mPa · s, more preferably 3 mPa · s to 8 mPa · s. s or less. When the viscosity of the water-based ink composition at 20 ° C. is within the above range, an appropriate amount of droplets of the water-based ink composition is ejected from the nozzle, and the flying curve and scattering of the droplets can be further reduced. Can be suitably used. The viscosity of the water-based ink composition can be measured by maintaining the temperature of the water-based ink composition at 20 ° C. using a vibration viscometer VM-100AL (manufactured by Yamaichi Electronics Co., Ltd.).

2. Examples Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.

2.1. Preparation of aqueous ink composition 2.1.1 Preparation of pigment dispersion The aqueous ink composition used in this example used a water-insoluble pigment as a colorant. When adding the pigment to the water-based ink composition, the pigment was dispersed in advance with a water-soluble resin.

The pigment dispersion was prepared as follows. First, 84.4 parts by mass of ion-exchanged water in which 0.6 parts by mass of a 30% aqueous ammonia solution (neutralizing agent) was dissolved, 3.0 parts by mass of a styrene-acrylic acid copolymer (weight average) as a water-soluble resin. Molecular weight: 25,000, acid value: 180) was added and dissolved. Thereto, 12 parts by mass of the following pigment was added, and dispersion treatment was performed for 10 hours with zirconia beads. Thereafter, centrifugal filtration using a centrifugal separator was performed to remove impurities such as coarse particles and dust, and the pigment concentration was adjusted to 12% by mass. Below, the pigment kind used for manufacture of a pigment dispersion liquid is shown.
C. I. Pigment Black 7 (used for black pigment dispersion)
C. I. Pigment Yellow 74 (used for yellow pigment dispersion)
C. I. Pigment Red 122 (used for magenta pigment dispersion)
C. I. Pigment Blue 15: 3 (used for cyan pigment dispersion)

2.1.2. Preparation of Aqueous Ink Composition and Ink Set Using the pigment dispersion prepared in “2.1.1 Preparation of Pigment Dispersion” above, in the material compositions shown in Tables 1, 2 and 3, black, Ink sets of Examples 1 to 14 and Comparative Examples 1 to 8 having different compositions were obtained by using four ink compositions of yellow, magenta, and cyan as one ink set. Each water-based ink composition is prepared by placing the pigment dispersion and the materials shown in Tables 1, 2, and 3 in a container, stirring and mixing with a magnetic stirrer for 1 hour, and then filtering with a membrane filter having a pore size of 5 μm. It was prepared by removing impurities such as coarse particles and dust. The numerical values in Tables 1, 2 and 3 all indicate mass%, and ion-exchanged water was prepared such that the total amount of each water-based ink composition was 100 mass%.

  In Table 1, Table 2, and Table 3, as the surfactant, a silicon-based surfactant “BYK-348” (manufactured by Big Chemie Japan Co., Ltd.) was used.

2.2. Evaluation test 2.2.1. Evaluation of quick-drying (1) Creation of recorded matter A part of the inkjet printer PX-G930 (manufactured by Seiko Epson Corporation) is remodeled, and a heater capable of changing the temperature is attached to the paper guide unit, and a recording medium is recorded during image recording. The heating can be adjusted.
The ink jet printer was filled with the cyan inks of Examples 1 to 14 and Comparative Examples 1 to 7 prepared in 2.1. A solid pattern was recorded using plastic media (trade name “Cold Laminate Film PG-50L”, manufactured by Lamy Corporation, PET film) as a recording medium. The solid pattern image was formed so as to have a printing ink amount of 0.8 mg / cm ² at a resolution of 720 dpi in length and 720 dpi in width.
For the recorded matter, the heater for the paper guide section was prepared using the ink jet printer so that the recording medium would be 50 ° C. at the time of recording, and the recording medium was left in a constant temperature bath at 60 ° C. immediately after recording. Made by drying for a minute.
(2) Evaluation of recorded matter Regarding the quick-drying property of the obtained recorded matter, immediately after drying, the recorded matter is taken out from the thermostatic bath, and taken out and returned to room temperature. Judged by criteria. Tables 1 and 2 show the evaluation results as quick-drying properties.
○: No ink adheres to the finger.
Δ: Stickiness on the surface of the recorded matter remains, but no ink adheres to the finger, and stickiness is acceptable in actual use.
X: Ink adheres to the finger.

2.2.2. Evaluation of rubbing resistance (1) Preparation of recorded matter The inks of Examples 1 to 14 and Comparative Examples 1 to 7 prepared in 2.1 were respectively added to the ink jet printer used in 2.2.1. Filled. A solid pattern was recorded using a recording medium plastic medium (trade name “Cold Laminate Film PG-50L”, manufactured by Lamy Corporation, PET film). The solid pattern image was formed so as to have a printing ink amount of 1.0 mg / cm ² at a resolution of 720 dpi vertically and 720 dpi horizontally.
For the recorded matter, the heater of the paper guide unit is adjusted using the inkjet printer so that the recording medium becomes 50 ° C. during recording, and the recording medium is left in a constant temperature bath at 60 ° C. immediately after recording. Made by drying for a minute.
(2) Evaluation method of recorded matter After the obtained recorded matter was kept at 20 ° C. for 16 hours, a load of 500 g and a number of frictions of 10 times were obtained using a Gakushin type friction fastness tester AB-301 (made by Tester Sangyo Co., Ltd.). Under the conditions described above, the friction material attached with the white cotton cloth for friction and the recorded material were rubbed together, and the surface condition of the image was visually observed, and judged according to the following evaluation criteria. Shown as rubbing.
◯: No scratches even after rubbing 10 times. Δ: Rubbing remains on the surface after rubbing 10 times, but there are no scratches that expose the base, and the rubbing marks are acceptable in practical use.
X: There is a scratch that the base is exposed by rubbing 10 times.

2.2.3. Evaluation of image quality (1) Creation of recorded matter The black and yellow ink sets of Examples 1 to 14 and Comparative Examples 1 to 7 prepared in 2.1 were used in the inkjet printer used in 2.2.1. , Magenta, and cyan, respectively. A plastic medium (trade name “Cold Laminate Film PG-50L”, manufactured by Lamy Corporation, PET film) was used as a recording medium, and a solid pattern in which each color was in contact with another color was recorded. The solid pattern image was formed so as to have a printing ink amount of 1.2 mg / cm ² at a resolution of 720 dpi vertically and 720 dpi horizontally.
For the recorded matter, the heater of the paper guide unit is adjusted using the inkjet printer so that the recording medium becomes 50 ° C. during recording, and the recording medium is left in a constant temperature bath at 60 ° C. immediately after recording. Made by drying for a minute.
(2) Evaluation method of recorded matter About the obtained recorded matter, the bleeding of the contact part with other colors of each color was observed, and it determined with the following evaluation criteria. Tables 1 and 2 show the evaluation results as image quality.
○: No bleeding between colors.
Δ: Although there is a slight bend in the contact portion with other colors, there is no problem in practical use because it is not a clear blur.
X: There is bleeding between each color.

  When the water-based ink compositions of Examples 1 to 14 shown in Table 1 were used, it was confirmed from the results of the quick drying evaluation that all had good quick drying properties. In addition, the evaluation result of the scratch resistance showed that the surface of the image recorded on the non-absorbent recording medium is hardly scratched and has excellent scratch resistance. Further, it was confirmed from the image quality evaluation results that the image recorded on the non-absorbent recording medium is free from bleeding or has no problem in practical use.

When the aqueous ink compositions of Example 6, Example 12 and Example 14 having a first solvent content (W ₁ ) described in Table 1 of 14% by mass were used, I couldn't feel it. On the other hand, when the water-based ink compositions of Example 4, Example 8, Example 10, and Example 13 having the first solvent content (W ₁ ) shown in Table 1 of 20% by mass were used, heating was performed. Although there was a case where a solvent odor slightly occurred during printing, it was not a problem in practical use.

When the aqueous ink compositions of Comparative Example 1 and Comparative Example 2 shown in Table 2 were used, the total of the second solvent and the third solvent (W ₂ + W ₃ ) exceeded 22% by mass. A recorded matter having poor abrasion resistance was formed.

When the water-based ink composition of Comparative Example 3 shown in Table 2 was used, since the content (W ₂ ) of the second solvent was less than 3% by mass, there was a large amount of bleeding and a recorded material with poor image quality. Formed.

When the water-based ink composition of Comparative Example 4 shown in Table 2 was used, since the content (W ₂ ) of the second solvent exceeded 10% by mass, a recorded material having an excellent quick drying property was formed. .

When the water-based ink composition of Comparative Example 5 shown in Table 2 was used, since the third solvent (W ₃ ) exceeded 15% by mass, a recorded matter having an excellent quick drying property was formed.

When the water-based ink composition of Comparative Example 6 shown in Table 2 was used, the total amount (W ₂ + W ₃ ) of the second solvent and the third solvent exceeded 22% by mass. An inferior recording was formed. In addition, since the content (W ₃ ) of the third solvent exceeds 15% by mass, a recorded matter having an excellent quick drying property was formed.

When the water-based ink composition of Comparative Example 7 shown in Table 2 was used, since the first solvent (W ₁ ) was less than 5% by mass, a recorded material having excellent abrasion resistance was formed.

2.2.4. Evaluation of ejection stability (1) Preparation of recorded matter In the ink jet printer used in 2.2.1, the black, yellow, magenta, and cyan of Example 1, Example 2, and Comparative Example 8 prepared in 2.1 Each of the four colors was filled. The water-based ink composition was continuously ejected on plain paper for 10 minutes without heating plain paper (Fuji Xerox P paper or the like), and it was confirmed that all nozzles were ejected normally. Subsequently, continuous printing of a mixed pattern of text and graphics with an average duty of 10% was performed for a predetermined time on plain paper heated to 50 ° C. to obtain a recorded matter. The weight of ink ejected per dot was 20 ng, and the resolution was 720 dpi vertical and 720 dpi horizontal.
(2) Evaluation method of recorded matter “Dot missing” and “curvature” of the obtained recorded matter were observed and evaluated. Here, “bend” refers to a deviation of the ink landing position on the recorded matter. The recorded matter was judged according to the following evaluation criteria. Table 3 shows the evaluation results as ejection stability.
○: After 1 hour from the start of printing, there is no missing dot or bending.
Δ: After 1 hour from the start of printing, dot missing does not occur and some bending occurs, but this is acceptable in actual use.
X: After 1 hour from the start of printing, dot missing and bending frequently occur.

When the water-based ink compositions of Example 1 and Example 2 shown in Table 3 were used, no dot omission occurred and some bending occurred, but the results were acceptable in practical use. . On the other hand, when the water-based ink composition of Comparative Example 8 shown in Table 3 was used, the third solvent (W ₃ ) was less than 5% by mass, resulting in frequent dot omission and bending.

2.2.5. Evaluation of Heating Temperature (1) Heating temperature and abrasion resistance A recorded matter was prepared using the cyan ink of Example 1 by the same method as 2.2.2 (1). However, the recording medium was changed to a stationary drying for 10 minutes in a 50 ° C. thermostat only under the drying conditions immediately after recording.

  The obtained recorded matter was evaluated by the same method as 2.2.2 (2). Unlike the results of Example 1 shown in Table 1, generation of scratches was confirmed on the surface.

(2) Heating temperature and image quality With the black, yellow, magenta, and cyan ink sets of Example 1, recorded matter was created by the same method as 2.2.3 (1). However, the heating temperature during recording was changed to 35 ° C., 40 ° C., and 60 ° C.

  As for the obtained recorded matter, when the heating temperature at the time of recording was 40 ° C. and 60 ° C., as in the image quality evaluation result of Example 1 described in Table 1, no blur occurred between adjacent colors. Unlike the image quality evaluation result of Example 1 shown in Table 1, the heating temperature at the time of recording was 35 ° C., and bleeding occurred between adjacent colors.

  The present invention is not limited to the embodiments described above, and various modifications are possible. 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 achieves the same effect 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 (7)

A first step of heating a non-ink-absorbing or low-absorbing recording medium to a temperature range of 40 ° C. or more and 60 ° C. or less by an inkjet recording apparatus and discharging droplets of the aqueous ink composition;
A second step of heating the recording medium to a temperature range of 50 ° C. or higher and 90 ° C. or lower and drying the water-based ink composition ejected on the recording medium,
The water-based ink composition is selected from water, at least one water-insoluble colorant, water-insoluble thermoplastic resin particles, a surfactant, and a glycol diether having a boiling point of 150 ° C. or higher and 220 ° C. or lower. At least one first solvent, at least one second solvent selected from 1,2-hexanediol and 1,2-pentanediol, and glycols having a boiling point in the range of 170 ° C. or higher and 220 ° C. or lower. Containing at least one third solvent selected from
The content of the first solvent in the aqueous ink composition (W ₁₎ is 5 to 20 wt%,
The content (W ₂ ) of the second solvent in the water-based ink composition is 3 to 10% by mass,
The content (W ₃ ) of the third solvent in the water-based ink composition is 5 to 15% by mass,
The total content (W ₂ + W ₃ ) of the second solvent and the third solvent is 22% by mass or less. The inkjet recording method according to claim 1,
The ink jet recording method, wherein the glycol diether as the first solvent is at least one selected from diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol butyl methyl ether, and triethylene glycol dimethyl ether. The inkjet recording method according to claim 1 or 2,
The inkjet recording method, wherein the glycol as the third solvent is at least one selected from propylene glycol and 1,3-propanediol. The inkjet recording method according to any one of claims 1 to 3,
The ink jet recording method, wherein the water-insoluble colorant is a pigment and is dispersed in a water-based ink composition with a water-soluble resin. In the ink jet recording method according to any one of claims 1 to 4,
The inkjet recording method, wherein the water-insoluble thermoplastic resin particles are an acrylic resin or a styrene-acrylic acid copolymer resin. In the ink jet recording method according to any one of claims 1 to 5,
An ink jet recording method, wherein the surfactant is a silicon-based surfactant. In the ink jet recording method according to any one of claims 1 to 6,
An ink jet recording method, wherein the recording medium is heated by a heater or hot air.