Recording method, processing solution ink set, and recording device

Abstract

This invention provides a recording method that improves the color reproduction of printed materials. [Solution] A recording method comprising: a processing liquid adhesion step of ejecting a processing liquid containing a coagulant from an inkjet head and adhering it to a recording medium; and an ink adhesion step of ejecting an ink composition, which is an aqueous ink containing a colorant, from an inkjet head and adhering it to the recording medium, wherein the recording medium is an absorbent recording medium, the processing liquid contains a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C and an acetylene glycol-based surfactant with an HLB value of 5 or more, the content of the 1,2-alkanediol is 3% by mass or more of the total amount of the processing liquid, and the coagulant contains a calcium salt, the content of the calcium salt is 5% by mass or more of the total amount of the processing liquid.

Description

[Technical Field]

[0001] The present invention relates to a recording method, a treatment liquid ink set, and a recording apparatus. [Background Art]

[0002] Recording methods using the inkjet method can record high-quality images with a relatively simple apparatus, and thus have been researched in various fields. In particular, in the field of light printing using plain paper, high color developability of recorded matter is required, so improvement of color developability is a subject attracting attention.

[0003] Regarding improvement of color developability, for example, a method of obtaining a high-quality recorded matter by depositing a reaction liquid on a recording medium has been disclosed (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2016-068306 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, in absorbent recording media such as plain paper, the deposited ink and the like easily permeate, and there has been a problem that the color developability of the recorded matter is still insufficient compared to other recording media.

[0006] Therefore, there is a demand for a recording method that allows a recorded matter to exhibit good color developability even when an absorbent recording medium is used. [Means for Solving the Problem]

[0007] One aspect of the recording method according to the present invention is a treatment liquid deposition step of ejecting a treatment liquid containing an aggregating agent from an inkjet head to deposit the treatment liquid on a recording medium; The process includes an ink application step in which an ink composition, which is a water-based ink containing a colorant, is ejected from an inkjet head and attached to the recording medium, The recording medium is an absorbent recording medium, The aforementioned treatment solution contains a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C, and an acetylene glycol-based surfactant with an HLB value of 5 or more. The content of the 1,2-alkanediol is 3% by mass or more relative to the total amount of the treatment solution. The aforementioned flocculant contains a calcium salt, The calcium salt content is 5% by mass or more relative to the total volume of the treatment solution.

[0008] One embodiment of the processing liquid ink set according to the present invention is: This is used in the recording method described above. The system comprises the aforementioned processing liquid and the aforementioned ink composition.

[0009] One aspect of the recording device according to the present invention is: This is used in the recording method described above. The aforementioned processing liquid, The aforementioned ink composition, An inkjet head that performs the processing liquid application step, It includes an inkjet head that performs the aforementioned ink application process. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of a recording device according to the embodiment. [Figure 2] Table 1 shows the composition of the ink compositions for the examples and comparative examples. [Figure 3] Table 2 shows the composition of the treatment solution used in the example and the evaluation results. [Figure 4] Table 3 shows the composition of the treatment solution and evaluation results for the examples and reference examples. [Figure 5] Table 4 shows the composition of the treatment solution and the evaluation results for the comparative example. MODE FOR CARRYING OUT THE INVENTION

[0011] Embodiments of the present invention are described below. The embodiments described below are illustrative examples of the present invention. The present invention is not limited to the following embodiments in any way, and also includes various modifications implemented within the scope that does not alter the gist of the present invention. Furthermore, not all of the configurations described below are necessarily essential configurations of the present invention.

[0012] In the present specification, a numerical range represented using "~" means a range that includes the numerical values described before and after "~" as the lower limit and upper limit.

[0013] In the present invention, a recording medium having an ink composition adhered thereto is referred to as a "recorded matter" or a "printed matter".

[0014] In the present specification, when the term "white" is used for referring to a white pigment or the like, the term does not refer only to pure white, and also includes colors slightly tinted with chromatic or achromatic colors and glossy colors, as long as they can be visually recognized as white. For example, in CIELAB, L * is preferably 80 or more, and L * is more preferably 85 or more.

[0015] 1. Recording Method A recording method according to an embodiment of the present invention includes: a treatment liquid adhering step of discharging a treatment liquid containing an aggregating agent from an inkjet head to adhere the treatment liquid to a recording medium; and an ink adhering step of discharging an aqueous ink composition containing a coloring material from an inkjet head to adhere the ink composition to the recording medium. The recording medium is an absorptive recording medium. The treatment liquid contains 1,2-alkanediol having a surface tension of 30 mN / m or less at 25° C. and an acetylene glycol-based surfactant having an HLB value of 5 or more. The content of the 1,2-alkanediol is 3% by mass or more relative to the total amount of the treatment liquid. The aggregating agent includes a calcium salt, and the content of the calcium salt is 5% by mass or more relative to the total amount of the treatment liquid.

[0016] Conventionally, in inkjet printing, which uses an inkjet head to eject ink compositions, there has been a demand for improved color reproduction of printed materials. However, in printing on plain paper, which is an absorbent recording medium, it has been difficult to obtain better color reproduction because the ink penetrates the recording medium when it adheres to it.

[0017] In contrast, according to the recording method of this embodiment, by applying a processing liquid to the recording medium, the penetration of the ink composition to be applied to the recording medium can be reduced, and the color development of the recorded material can be improved.

[0018] The steps of the recording method according to this embodiment and the recording medium used in the recording method according to this embodiment will be described in detail below.

[0019] 1.1. Process of applying treatment liquid The recording method according to this embodiment discharges a processing liquid containing a coagulant from an inkjet head. The process includes a step of applying a processing liquid to a recording medium. The processing liquid application step can be performed before or simultaneously with the ink composition application step, which will be described later. If the processing liquid application step is performed before the ink composition application step, the processing liquid composition is applied to a predetermined area of ​​the recording medium by the main scan of the recording device, and then the ink composition is applied to the same area by another main scan. If the processing liquid composition application step and the ink composition application step are performed simultaneously, the processing liquid and the ink composition are applied to a predetermined area of ​​the recording medium by the same main scan of the recording device.

[0020] The following describes the treatment liquid used in the treatment liquid application process.

[0021] 1.1.2. Treatment solution 1.1.2.1. Flocculants The processing solution used in the recording method according to this embodiment contains a coagulant. The coagulant contains a calcium salt. The presence of the coagulant in the processing solution reacts with the ink composition attached to the recording medium, coagulating components such as colorants, thereby improving the color development of the recorded material. In addition, the presence of the coagulant reduces the proportion of water in the reaction solution, which reduces the occurrence of curling, or warping of the recording medium, during recording. Hereinafter, curling that occurs during recording will be referred to as primary curling.

[0022] If primary curling occurs, secondary curling will occur during the drying process of the recording medium, as described later, so the occurrence of secondary curling is also a concern.

[0023] When the processing solution is applied to the recording medium in addition to the ink composition, the total amount of water adhering to the recording medium increases, which tends to increase the occurrence of curl. However, in this embodiment, the content of calcium salt, which is a coagulant, in the processing solution is above a predetermined level, so the relative content of water in the processing solution tends to be low, resulting in excellent curl suppression.

[0024] Furthermore, the processing solution used in the recording method according to this embodiment has excellent color development properties, which tends to reduce the need to excessively increase the amount of processing solution adhering to the recording medium to enhance color development, and thus provides excellent curl suppression.

[0025] The calcium salts contained in the coagulant have high solubility in water, meaning they can be included in large quantities in the treatment solution, thereby improving the reactivity between the treatment solution and the ink composition. Furthermore, even when large amounts of polyvalent metal salts such as calcium salts are included, the viscosity does not increase significantly.

[0026] The calcium salt preferably dissolves in 100g or more of water at 20°C, more preferably in 50g or more, and even more preferably in 100g or more. When the water solubility of the calcium salt in 100g of water is within the above range, the reaction between the processing solution and the components in the ink composition is carried out sufficiently, resulting in good color development of the recorded material.

[0027] Examples of calcium salts include organic calcium salts and inorganic calcium salts. Inorganic calcium salts are preferred because they have higher water solubility and higher reactivity with the ink composition. When the calcium salt has high water solubility, even if the processing solution dries at the nozzle of the inkjet head when it is ejected from the head, less of the dissolved calcium salt precipitates. In other words, the calcium salt is less likely to become a foreign substance and less likely to hinder ink ejection. Also, because the calcium salt has high water solubility, it is easily ionized in the reaction solution, and a large amount of calcium ions are generated, resulting in high reactivity with the ink composition. For these reasons, inorganic calcium salts are preferred. Examples of inorganic calcium salts include calcium chloride and calcium nitrate.

[0028] The calcium salt content is 5% by mass or more, preferably 8% by mass or more, more preferably 9% by mass or more, and even more preferably 10% by mass or more, relative to the total amount of the processing solution. Furthermore, 15% by mass or more is preferred, and 17% by mass or more is even more desirable. When the calcium salt content is above the above range, the calcium salt contributes more easily to the reaction with the ink composition, even in recording media that are easily permeated by the processing solution, such as absorbent recording media, resulting in good color development of the recorded material. Moreover, when the content is above the above range, curl suppression is better and therefore preferable.

[0029] The calcium salt content is preferably 25% by mass or less, more preferably 22% by mass or less, and even more preferably 20% by mass or less, relative to the total volume of the processing solution. When the content is below the above range, the calcium salt dissolves sufficiently easily, resulting in better discharge stability.

[0030] 1.1.2.2. Organic Solvents <1,2-alkanediol> The processing solution used in the recording method according to this embodiment contains an organic solvent, and the organic solvent contains a 1,2-alkanediol. The 1,2-alkanediol contained in the processing solution includes a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C. Note that the above surface tension at 25°C refers to the static surface tension.

[0031] The processing solution contains 1,2-alkanediols with a surface tension of 30 mN / m or less at 25°C, which makes it easier to separate the droplets ejected by the inkjet method. Furthermore, the trail of the ejected droplets becomes longer, increasing the coverage area on the recording medium. In other words, the recording medium is sufficiently coated by the processing solution, reducing the areas where the processing solution does not adhere. This sufficient coating of the recording medium by the processing solution, i.e., improved embedding of the processing solution into the recording medium, reduces the penetration of the ink composition, resulting in better color development of the recorded material.

[0032] Furthermore, the presence of 1,2-alkanediols with a surface tension of 30 mN / m or less at 25°C in the processing solution improves the water solubility of the acetylene glycol-based surfactant described later, making it less likely to become a foreign substance during nozzle discharge.

[0033] The surface tension of 1,2-alkanediol at 25°C is 30 mN / m or less, preferably 29 mN / m or less, more preferably 28 mN / m or less, and even more preferably 27 mN / m or less. Furthermore, the surface tension of 1,2-alkanediol at 25°C is preferably 10 mN / m or more, more preferably 15 mN / m or more, and even more preferably 20 mN / m or more. When the surface tension of 1,2-alkanediol at 25°C is within the above range, the wetting spread onto the recording medium is good, and the filling of the processing solution is good.

[0034] Regarding the measurement method for surface tension, a commonly used method is to measure it using the Wilhelmy method at a liquid temperature of 25°C with a surface tension meter (for example, the CBVP-Z surface tension meter manufactured by Kyowa Interface Science Co., Ltd.).

[0035] Hereafter, unless otherwise specified, "1,2-alkanediols with a surface tension of 30 mN / m or less at 25°C" will be referred to as "1,2-alkanediol" or "specific 1,2-alkanediol".

[0036] The specific 1,2-alkanediol preferably has 5 or more carbon atoms, and more preferably 5 to 7 carbon atoms. Examples of specific 1,2-alkanediols include 1,2-pentanediol, 1,2-hexanediol, and 1,2-heptanediol. Among these, 1,2-hexanediol is particularly preferred.

[0037] The content of specific 1,2-alkanediols shall be 3% by mass or more relative to the total volume of the treatment solution. Preferably, the content of the specific 1,2-alkanediol is 4% by mass or more, and more preferably 5% by mass or more. When the content of the specific 1,2-alkanediol is within the above range, the processing solution fills the recording medium well. Also, if the content of the specific 1,2-alkanediol is too high, the dynamic surface tension of the processing solution decreases, and trailing and splashing when the processing solution is discharged increases. Therefore, the content of the specific 1,2-alkanediol is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, relative to the total amount of the processing solution.

[0038] <Other organic solvents> The treatment solution may contain organic solvents other than specific 1,2-alkanediols. Examples of such organic solvents include esters, alkylene glycol ethers, cyclic esters, amides, alcohols, and polyhydric alcohols other than specific 1,2-alkanediols.

[0039] Examples of esters include glycol monoacetates and glycol diesters.

[0040] The alkylene glycol ethers can be monoethers or diethers of alkylene glycols, with alkyl ethers being preferred. Specific examples include alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monobutyl ether, and tetraethylene glycol monomethyl ether; and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0041] Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone, as well as compounds in which the hydrogen atoms of the methylene group adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0042] Examples of amides include cyclic amides and acyclic amides. Examples of acyclic amides include alkoxyalkylamides.

[0043] Examples of cyclic amides include lactams. Examples of lactams include pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone.

[0044] Examples of alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, and 3-methoxy-N,N-methylethylpropionamide.

[0045] Examples of alcohols include compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group. Alkanes with 10 or fewer carbon atoms are preferred, those with 6 or fewer carbon atoms are more preferred, and those with 3 or fewer carbon atoms are even more preferred. Alkanes have 1 or more carbon atoms, and preferably 2 or more. Alkanes may be linear or branched.

[0046] Examples of alcohols include methanol, ethanol, n-propanol, iso-propanol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol. Examples include phenoxyethanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0047] Polyhydric alcohols are molecules that contain two or more hydroxyl groups. Examples of polyhydric alcohols include alkanediols and other polyhydric alcohols.

[0048] Alkanediols include, for example, compounds in which an alkane is substituted with two hydroxyl groups. Examples of alkanediols include 1,2-alkanediols, which are a general term for compounds in which hydroxyl groups are substituted at the 1st and 2nd positions of an alkane, and alkanediols other than 1,2-alkanediols. Of these, specific 1,2-alkanediols are described above and will therefore be omitted.

[0049] Examples of alkanediols other than specific 1,2-alkanediols include 1,3-propanediol, 1,3-butylene glycol (also known as 1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-butanediol, and propylene glycol.

[0050] Other polyhydric alcohols include, for example, condensates formed by the intermolecular condensation of two or more alkanediol molecules via hydroxyl groups, and compounds having three or more hydroxyl groups.

[0051] Examples of condensates formed by the intermolecular condensation of two or more alkanediol molecules at their hydroxyl groups include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0052] Compounds having three or more hydroxyl groups are compounds with an alkane or polyether structure as their backbone and containing three or more hydroxyl groups. Examples of compounds having three or more hydroxyl groups include glycerin, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0053] The total content of the organic solvent, including the specific 1,2-alkanediol, is preferably 3 to 30% by mass, more preferably 6 to 25% by mass, and even more preferably 8 to 20% by mass, relative to the total volume of the treatment solution. In this case, better filling, curl suppression, and discharge stability are preferable.

[0054] 1.1.2.3. Acetylene glycol-based surfactants The processing solution used in the recording method according to this embodiment contains an acetylene glycol-based surfactant with an HLB value of 5 or higher.

[0055] The processing solution contains an acetylene glycol-based surfactant with an HLB value of 5 or higher, which improves the wettability and spreadability of the processing solution on the recording medium, resulting in better embedding of the processing solution into the recording medium and superior color development. In addition, the processing solution is more easily droplet-formed when discharged from the nozzle, resulting in good discharge stability.

[0056] Furthermore, having an HLB value of 5 or higher for the acetylene glycol-based surfactant reduces the likelihood of the treatment solution penetrating the absorbent recording medium too much, thereby inhibiting the reaction with the ink, while maintaining excellent wetting and droplet formation properties. This results in superior color development of the ink composition.

[0057] Furthermore, if the HLB value of the acetylene glycol-based surfactant is 5 or higher, it has high water solubility. Therefore, it is less prone to phase separation in the processing liquid and less likely to become foreign matter when the processing liquid is discharged.

[0058] Acetylene glycol-based surfactants tend to produce less foam than other surfactants such as silicone-based surfactants. Therefore, when filling inkjet printer cartridges with the processing solution, less air bubbles are generated. In other words, the initial filling of the cartridges is excellent.

[0059] Furthermore, acetylene glycol-based surfactants with an HLB value of less than 5 have too high a penetration rate of the processing solution into the absorbent recording medium. This causes the processing solution to penetrate the absorbent recording medium, inhibiting the reaction with the ink composition and resulting in poor color development of the ink composition.

[0060] Here, the HLB value is a value determined by the balance between hydrophilic and lipophilic groups in a surfactant molecule. A high HLB value indicates a highly hydrophilic surfactant, while a low HLB value qualitatively indicates a highly lipophilic surfactant.

[0061] In this specification, the HLB value is defined as follows: The "HLB value (hydrophilic lipophilic balance)" is a value calculated by the Griffin method. Specifically, the HLB value of a surfactant can be calculated according to the following formula (H). HLB value = 20 × (mass of hydrophilic groups) ... (H)

[0062] The HLB value of the acetylene glycol-based surfactant is preferably 6 or higher, more preferably 7 or higher, even more preferably 10 or higher, even more preferably 12 or higher, and particularly preferably 13 or higher. When the value is above the above range, the color development and water solubility are better.

[0063] Furthermore, the HLB value of the acetylene glycol-based surfactant is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. It is even more preferably 10 or less, and even more preferably 9 or less. When the value is within the above range, the burrowing and discharge stability are better.

[0064] Acetylene glycol-based surfactants with an HLB value of 5 or higher may be used individually or in combination of two or more types.

[0065] The acetylene glycol-based surfactant may contain an acetylene glycol-based surfactant with an HLB value of 10 or higher (hereinafter also referred to as "high HLB value") and an acetylene glycol-based surfactant with an HLB value of 5 or higher but less than 10 (hereinafter also referred to as "low HLB value"). By using a high HLB value acetylene glycol-based surfactant and a low HLB value acetylene glycol-based surfactant in combination, the wettability of the processing solution becomes more favorable, and the color development of the applied ink composition becomes better.

[0066] Low-HLB acetylene glycol-based surfactants are preferably HLB values ​​of 5 or more and less than 10, and more preferably HLB values ​​of 6 or more and less than 9. When the HLB value is within the above range, the wetting spread of the treatment solution is better.

[0067] Acetylene glycol-based surfactants with a high HLB value preferably have an HLB value of 10 or higher, and more preferably have an HLB value of 12 or higher. Furthermore, while not particularly limited, acetylene glycol-based surfactants with a high HLB value preferably have an HLB value of 20 or lower, and more preferably have an HLB value of 18 or lower.

[0068] Examples of commercially available acetylene glycol-based surfactants include Orfin EXP4300, Orfin E1004 (HLB value 7-9), Surfinol SE (HLB value 6), Examples include Surfinol 440 (HLB value 8), Orphine E1010 (HLB value 13-14), Orphine E1020 (HLB value 15-16), Orphine E1030W (HLB value 15-16), and Surfinol 485 (HLB value 17) (all are brand names, manufactured by Nisshin Chemical Industry Co., Ltd.).

[0069] The total content of acetylene glycol-based surfactants is preferably 0.05% to 2.0% by mass, more preferably 0.1% to 1.8% by mass, and even more preferably 0.2% to 1.5% by mass, relative to the total amount of the treatment solution. Furthermore, 0.5 to 1.4% by mass is preferred, 0.8 to 1.4% by mass is preferred, and 1.0 to 1.4% by mass is preferred.

[0070] The content of the high-HLB acetylene glycol surfactant is preferably 0.05 to 2.0% by mass, more preferably 0.2 to 1.8% by mass, even more preferably 0.4 to 1.5% by mass, even more preferably 0.5 to 1.3% by mass, and most preferably 0.7 to 1.2% by mass, based on the total amount of the treatment solution.

[0071] The content of the low-HLB acetylene glycol surfactant is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 0.8% by mass, even more preferably 0.2 to 0.6% by mass or less, and even more preferably 0.3 to 0.5% by mass, relative to the total amount of the treatment solution.

[0072] When the acetylene glycol-based surfactant content is within the above range, the embedding of the processing solution into the recording material and the discharge stability of the processing solution are good.

[0073] The mass ratio (w1 / w2) of the content of low-HLB acetylene glycol-based surfactants (w1) to the total content of acetylene glycol-based surfactants (w2) is preferably 0.05 to 0.6, more preferably 0.1 to 0.5, and even more preferably 0.2 to 0.4. When the mass ratio of acetylene glycol-based surfactants is within the above range, the discharge stability during recording is improved.

[0074] The acetylene glycol-based surfactant contained in the treatment solution may or may not contain further acetylene glycol-based surfactants with an HLB value of less than 5, but a lower content is preferable in terms of color development and water solubility, and is preferably not more than 0.4% by mass, preferably not more than 0.2% by mass, preferably not more than 0.1% by mass, and preferably not more than 0.05% by mass of the total amount of the treatment solution. The lower limit of the content is 0% by mass.

[0075] 1.1.2.4. Moisturizers The processing solution used in the recording method according to this embodiment preferably contains a humectant.

[0076] Examples of humectants include liquid humectants such as glycerin and solid humectants such as betaine. Liquid humectants can be those organic solvents with particularly high moisturizing properties, and these are also organic solvents.

[0077] Examples of moisturizers include betaine and glycerin.

[0078] <Betaine> The processing solution preferably contains betaine. Betaine is a compound that has charged and negative charges at non-adjacent positions within the same molecule, where the positively charged atom does not have any dissociable hydrogen atoms bonded to it, and which can form an intramolecular salt, and the molecule as a whole has no charge. In this embodiment, the betaine is preferably one in which the positively charged site is a quaternary ammonium cation.

[0079] The inclusion of betaine in the processing solution reduces curling that occurs on the recording medium. In particular, curling that occurs after recording, when the ink composition etc. dries and the edges of the recording medium lift off the contact surface (hereinafter also referred to as "secondary curling") is reduced.

[0080] Furthermore, the presence of betaine in the treatment solution reduces phase separation of acetylene glycol-based surfactants, thereby suppressing the formation of foreign matter.

[0081] The betaine is not particularly limited, but examples include trialkylglycines such as trimethylglycine and triethylglycine, γ-butyrobetaine, fomarin, trigonelline, carnitine, homoserine betaine, valine betaine, lysine betaine, ornithine betaine, alanine betaine, staquidrine, and glutamate betaine. Among these, it is preferable that the glycines contained in the treatment solution be selected from trialkylglycines, and it is preferable that the trialkylglycines have three or fewer C3 atoms in each alkyl group, and it is more preferable that trimethylglycine is included. Trialkylglycines are compounds in which three alkyl groups are substituted on the nitrogen atom of glycine. This tends to further improve the clogging recovery performance. The betaine may be used alone or in combination of two or more types.

[0082] The number of carbon atoms in the betaine is preferably 4 to 12, more preferably 4 to 7, and even more preferably 4 to 6. When the number of carbon atoms in the betaine is within the above range, the stability of the treatment solution is improved.

[0083] The betaine content is preferably 0.5% to 20% by mass, more preferably 1% to 15% by mass, even more preferably 2% to 10% by mass, even more preferably 3% to 9% by mass, and particularly preferably 4% to 7% by mass, based on the total amount of the processing liquid. When the betaine content is within the above range, the discharge stability of the processing liquid is improved, and the occurrence of secondary curl of the recorded material can be reduced.

[0084] <Glycerin> The processing solution may contain glycerin as a humectant. The inclusion of glycerin in the processing solution reduces drying and improves discharge stability during recording. It also has the effect of improving the water solubility of acetylene glycol-based surfactants.

[0085] If glycerin is present in excess, primary curl of the recorded material is likely to occur. Therefore, the glycerin content is preferably 0.1% to 9% by mass, more preferably 0.5% to 7% by mass, and even more preferably 1% to 5% by mass, relative to the total volume of the processing solution. When the glycerin content is within the above range, the occurrence of primary curl is reduced.

[0086] Furthermore, glycerin is a polyhydric alcohol with a standard boiling point exceeding 280°C, and the content of polyhydric alcohols with a standard boiling point exceeding 280°C, not limited to glycerin, may also be set within the above range, which is preferable in the above respect.

[0087] <Other> The treatment solution may contain other humectants besides those mentioned above. These other humectants are not particularly limited, but examples include ureas. Specific examples of ureas include urea, ethylene urea, tetramethylurea, thiourea, and 1,3-dimethyl-2-imidazo. Examples include Lysinone.

[0088] 1.1.2.5.Water The processing solution used in the recording method according to this embodiment may contain water. Examples of water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, which has reduced ionic impurities. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can suppress the growth of bacteria and fungi when the ink composition is stored for a long period of time.

[0089] The water content is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, relative to the total amount of the treatment liquid. Furthermore, the water content is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. Moreover, 75% by mass or less is preferred, and 70% by mass or less is even more preferred. When the water content is below the above range, it is preferable in terms of suppressing curling.

[0090] 1.1.2.6. Other Ingredients The processing liquid used in the recording method according to this embodiment may further contain, if necessary, components such as preservatives, antifungal agents, rust inhibitors, chelating agents, viscosity modifiers, and antioxidants.

[0091] 1.2. Ink composition application process The recording method according to this embodiment includes an ink application step in which an ink composition, which is an aqueous ink containing a colorant, is ejected from an inkjet head and adhered to the recording medium. The ink composition application step can be performed after or simultaneously with the processing liquid application step described above.

[0092] The ink compositions used in the ink composition application process will be described below.

[0093] 1.2.1. Ink Composition 1.2.1.1. Colorants The ink composition used in the recording method according to this embodiment contains a colorant. The colorant is not particularly limited, but examples include dyes and pigments. Among these, it is preferable to use a pigment because it has the property of being resistant to fading even when exposed to light and gas. Records recorded with ink using a pigment have good water resistance, gas resistance, light resistance, and storage stability.

[0094] The colorant content is preferably 0.5% by mass or more, more preferably 1.0% by mass or more and 14% by mass or less, even more preferably 2.0% by mass or more and 12% by mass or less, even more preferably 4.0% by mass or more and 10% by mass or less, and particularly preferably 6% by mass or more and 8% by mass or less, relative to the total amount of the ink composition.

[0095] When the colorant content is within the above range, the ink composition exhibits good color development and good storage stability.

[0096] <Pigments> Both inorganic and organic pigments can be used as pigments. Examples of inorganic pigments include carbon black; compounds such as metal oxides, metal sulfides, and metal chlorides; and inorganic particles such as kaolin, talc, and calcium carbonate.

[0097] Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelated azo pigments, as well as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, and isoindolinone pigments. Polycyclic pigments such as quinophthalone pigments, dye chelates, dye lakes, nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments are used. These pigments can be used individually or in combination of two or more.

[0098] The pigment may be a self-dispersing pigment or a resin-dispersible pigment. A self-dispersing pigment is a pigment that can be dispersed and / or dissolved in an aqueous medium without a dispersant such as a resin or surfactant. Here, "dispersible and / or dissolved in an aqueous medium without a dispersant" refers to a state in which the pigment is stably present in the aqueous medium due to the hydrophilic groups on its surface, even without the use of a dispersant to disperse the pigment.

[0099] Examples of self-dispersing pigments include pigments in which hydrophilic groups are directly or via other atomic groups bonded to the pigment surface. These include pigments in which functional groups containing anionic groups are bonded to the surface of pigment particles, or pigments in which anionic resins are chemically bonded to the surface of pigment particles.

[0100] Examples of hydrophilic groups on the surface of self-dispersing pigments include -OM, -COOM, -CO-, -SO3M, -SO2M, -SO2NH2, -RSO2M, -PO3HM, -PO3M2, -SO2NHCOR, -NH3, -NR3, and groups in which some of the hydrogen atoms of the propylene oxy chain are substituted with M. In the formula, M represents a hydrogen atom, alkali metal, ammonium, or organic amine, and R represents an alkyl group having 1 to 12 carbon atoms or a naphthyl group which may have substituents.

[0101] Other atomic groups include linear or branched alkylene groups, phenylene groups, naphthylene groups, amide groups, sulfonyl groups, amino groups, carbonyl groups, ester groups, ether groups, and groups that combine these groups, with a total of 1 to 12 carbon atoms.

[0102] Resin-dispersed pigments are pigments dispersed by a resin. The resin used to disperse the pigment is also called a resin dispersant.

[0103] Examples of resin dispersants used in resin-dispersed pigments include polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylic acid ester copolymers, acrylic acid-acrylic acid ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinylnaphthalene-acrylic acid copolymers, vinylnaphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and salts thereof. Among these, copolymers of monomers having hydrophobic functional groups and monomers having hydrophilic functional groups, and polymers consisting of monomers having both hydrophobic and hydrophilic functional groups are preferred. The copolymer can be used in any form, such as a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer. The resin dispersant may be used alone or in combination of two or more types.

[0104] The pigment preferably contains one or more of the following: self-dispersing pigments and resin-dispersed pigments, and more preferably contains self-dispersing pigments.

[0105] <dye> While not particularly limited, acid dyes, direct dyes, reactive dyes, and basic dyes can be used as dyes. Examples of such dyes include CI Acid Yellow 17, 23, 42, 44, 79, 142 and CI Acid Red 52, 80, 82, 249, 254. Examples include CI Acid Blue 9, 45, 249, CI Acid Black 1, 2, 24, 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Direct Black 19, 38, 51, 71, 154, 168, 171, 195, CI Reactive Red 14, 32, 55, 79, 249, CI Reactive Black 3, 4, 35, etc.

[0106] Dyes may be used individually or in combination of two or more types.

[0107] 1.2.1.2. Resin The ink composition used in the recording method according to this embodiment may contain a resin. The inclusion of a resin in the ink composition improves the adhesion of the ink components to the recording medium, reducing transfer to other recording materials when recordings are stacked. In other words, the contained resin acts as a fixing resin. As the resin, a water-soluble resin or an emulsion of resin particles can be used.

[0108] The water-soluble resin is not particularly limited, but examples include urethane resins, acrylic resins, polyalkylene oxide resins, polyvinyl alcohol resins, and carboxymethylcellulose resins. Urethane resins or acrylic resins are preferred as the water-soluble resin.

[0109] The resin particles may be in powder form, but from the viewpoint of discharge stability during recording, they are preferably in emulsion form.

[0110] The resin particles are not particularly limited, but examples include water-dispersible resins consisting of urethane resins, acrylic resins including styrene-acrylic resins, fluorene resins, olefin resins, rosin-modified resins, terpene resins, ester resins, amide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, ethylene vinyl acetate resins, and the like. Among these, acrylic resins and urethane resins are more preferred as resin particles. The resin may be used alone or in combination of two or more types.

[0111] Urethane resins are a general term for resins that contain urethane bonds. In addition to urethane bonds, urethane resins can also include polyether-type urethane resins containing ether bonds in the main chain, polyester-type urethane resins containing ester bonds in the main chain, and polycarbonate-type urethane resins containing carbonate bonds in the main chain. As the resin particles of the urethane resin, commercially available products may be used, for example, Superflex 460, 460s, 840, E-4000 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (product name, manufactured by Dainichi Seika Kogyo Co., Ltd.), Takelac WS-6021, W-512-A-6 (product name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), SanCure 2710 (product name, manufactured by LUBRIZOL), Permarin UA-150 (product name, manufactured by Sanyo Chemical Industries, Ltd.).

[0112] Acrylic resins are a general term for polymers obtained by polymerizing at least one acrylic monomer, such as (meth)acrylic acid or (meth)acrylic acid ester. Examples include resins obtained from acrylic monomers and copolymers of acrylic monomers with other monomers. For example, acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers, are examples. Furthermore, copolymers with vinyl monomers such as styrene are also examples.

[0113] Acrylic monomers such as acrylamide and acrylonitrile can also be used. Commercially available water-dispersible resins made from acrylic resins include, for example, FK-854 (trade name, manufactured by Chuo Rika Kogyo Co., Ltd.), Movinyl 952B, 718A (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Nipol LX852, LX874 (trade name, manufactured by Nippon Zeon Corporation).

[0114] Styrene-acrylic resins are copolymers obtained from styrene monomers and acrylic monomers, and examples include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers. As the styrene-acrylic resin, commercially available products may be used, for example, Joncryl 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (product names, manufactured by BASF), Movinyl 966A, 975N (product names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Vinibran 2586 (manufactured by Nisshin Chemical Industry Co., Ltd.), etc.

[0115] The glass transition temperature (Tg) of the resin particles is preferably between -50°C and 70°C, more preferably between -10°C and 50°C, and even more preferably between 0°C and 40°C. When the glass transition temperature of the resin particles is within the above range, the ejection stability during recording is good.

[0116] The glass transition temperature (Tg) of a resin can be confirmed by standard methods such as differential scanning calorimetry (DSC).

[0117] The resin content is preferably 0.1% to 5% by mass, more preferably 0.2% to 3% by mass, and even more preferably 0.2% to 2% by mass, relative to the total amount of the ink composition. Furthermore, 0.3 to 1% by mass is preferred, and even more preferably 0.4 to 0.8% by mass.

[0118] 1.2.1.3. Organic Solvents The ink composition used in the recording method according to this embodiment may contain an organic solvent. The organic solvent is preferably water-soluble. Functions of the organic solvent include improving the wettability of the ink composition on the recording medium and enhancing the moisture retention of the ink composition.

[0119] The organic solvent is not particularly limited, but should conform to the section "1.1.2.2. Organic Solvents". Examples include those listed in the section "1.1.2.2. Organic Solvents", and among these, it is preferable that it contains polyhydric alcohols, and more preferably that it contains alkanediols or polyhydric alcohols with a standard boiling point greater than 280°C.

[0120] The inclusion of polyhydric alcohols with a standard boiling point exceeding 280°C improves the moisture retention of the ink composition and enhances the ejection stability of the ink composition during recording. Furthermore, if the ink composition contains an acetylene glycol-based surfactant as described later, it improves the water solubility of the acetylene glycol-based surfactant and reduces the occurrence of phase separation.

[0121] Among polyhydric alcohols, glycerin is an example of one with a standard boiling point exceeding 280°C. Examples include triethylene glycol and tetraethylene glycol. Examples of polyols with a standard boiling point of 280°C or lower include ethylene glycol, diethylene glycol, pentaethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0122] The content of polyhydric alcohols with a standard boiling point above 280°C is preferably 0.1% to 25% by mass, more preferably 0.5% to 23% by mass, even more preferably 1.0% to 20% by mass, and particularly preferably 5.0% to 15% by mass, relative to the total amount of the ink composition. When the content of polyols with a standard boiling point above 280°C is within the above range, the discharge stability of the ink composition is improved. Furthermore, if the ink composition contains an acetylene glycol-based surfactant, the water solubility of the acetylene glycol-based surfactant is improved.

[0123] 1.2.1.4. Moisturizers The ink composition used in the recording method according to this embodiment may contain a humectant. The humectant is as specified in section "1.1.2.4. Humidifier".

[0124] The ink composition preferably contains betaine as a humectant. The inclusion of betaine in the ink composition improves its discharge stability.

[0125] The betaine content is preferably 1.0% by mass or more and 15.0% by mass or less, more preferably 3.0% by mass or more and 13.0% by mass or less, even more preferably 5.0% by mass or more and 10.0% by mass or less, and even more preferably 6.0% by mass or more and 9.0% by mass or less, based on the total amount of the ink composition.

[0126] Furthermore, it is preferable that the ink composition contains glycerin as a humectant. The inclusion of glycerin in the ink composition improves the discharge stability of the ink composition.

[0127] The glycerin content is preferably 1.0% to 15.0% by mass, more preferably 2.0% to 12.0% by mass, and even more preferably 3.0% to 10% by mass, relative to the total amount of the ink composition. When the glycerin content is within the above range, the ejection stability of the ink composition is improved, and the occurrence of secondary curling of the recorded material is also reduced.

[0128] 1.2.1.5. Surfactants The ink composition used in the recording method according to this embodiment may contain a surfactant. Examples of surfactants include acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants, but among these, it is preferable to include an acetylene glycol-based surfactant. The inclusion of an acetylene glycol-based surfactant in the ink composition improves the ejection stability of the ink composition. Furthermore, the inclusion of an acetylene glycol-based surfactant in the ink composition improves the wetting spread of the ink composition onto the recording medium. In addition, compared to other surfactants, the ink composition produces less foam, resulting in better initial filling of the inkjet printer cartridge.

[0129] For acetylene glycol-based surfactants, refer to section "1.1.2.3. Acetylene Glycol-Based Surfactants".

[0130] The content of acetylene glycol-based surfactants is preferably in proportion to the total amount of the ink composition. The amount is 0.05% by mass or more and 5.0% by mass or less, more preferably 0.1% by mass or more and 4.0% by mass or less, even more preferably 0.2% by mass or more and 3.0% by mass or less, even more preferably 0.3% by mass or more and 2.0% by mass or less, and particularly preferably 0.4% by mass or more and 1.0% by mass or less.

[0131] When the content of acetylene glycol-based surfactants is within the above range, the acetylene glycol-based surfactants are less likely to undergo phase separation, and the ejection stability of the ink composition is further improved.

[0132] 1.2.1.6.Water The ink composition used in the recording method according to this embodiment is an aqueous ink, and preferably contains water. "Aqueous" means that it contains at least water as a solvent component, and may contain water as the main solvent component. Examples of water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, which has reduced ionic impurities. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can suppress the growth of bacteria and fungi when the ink composition is stored for a long period of time.

[0133] The water content is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, relative to the total amount of the ink composition. Furthermore, the water content is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

[0134] 1.2.1.7. Other Ingredients The ink composition used in the recording method according to this embodiment may further contain, if necessary, components such as preservatives, antifungal agents, rust inhibitors, chelating agents, viscosity modifiers, and antioxidants.

[0135] 1.3. Recording media The recording medium used in the recording method according to this embodiment is an absorbent recording medium. The absorbent recording medium is not particularly limited, but examples include plain paper such as electrophotographic paper with high ink permeability, inkjet paper, art paper, coated paper, cast paper, or fabric used in general offset printing with relatively low ink permeability. The inkjet paper is not particularly limited, but specifically, examples include paper equipped with an ink-absorbing layer composed of silica particles or alumina particles, or an ink-absorbing layer composed of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP). Plain paper is preferred as the absorbent recording medium.

[0136] Furthermore, an absorbent recording medium is defined as "a recording medium that, in the Bristow method, is used from the start of contact for 30 msec." 1 / 2 Up to 10 mL / m² of water absorption capacity 2 This refers to a "recording medium that is extremely resistant to liquids." The Bristow method is the most widely used method for measuring liquid absorption in a short time and is also adopted by the Japan Paper & Pulp Technology Association (JAPAN TAPPI). Details of the test method are described in standard No. 51 "Paper and cardboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper & Pulp Test Methods 2000 Edition."

[0137] By applying the processing solution to the absorbent recording medium using the recording method according to this embodiment, the penetration of the ink composition into the recording medium can be reduced, resulting in improved color development of the recorded material.

[0138] 2. Processing solution ink set A processing liquid ink set according to one embodiment of the present invention comprises the processing liquid described above and the ink composition described above.

[0139] The processing solution ink set, having the processing solution and the ink composition described above, reduces the penetration of the ink composition into the recording medium during recording, resulting in a recording with better color development.

[0140] Furthermore, a processing solution ink set is defined as a set in which the processing solution and the ink composition are used together during recording, and is not limited to cases where they are manufactured, sold, etc., as an integrated unit. If the processing solution and the ink composition are intended to be used together, or if their combined use is substantially encouraged, they are included in the set.

[0141] 3. Recording device A recording device according to one embodiment of the present invention is used in the recording method described above and comprises the processing liquid described above, the ink composition described above, an inkjet head that performs a processing liquid application step, and an inkjet head that performs an ink application step.

[0142] According to the recording device of this embodiment, the above-described recording method can be performed, and a recording with good color development can be obtained.

[0143] An example of a recording device capable of implementing the recording method according to this embodiment will be described.

[0144] Figure 1 is a schematic diagram of the recording device. In Figure 1, the XYZ coordinate system shows the length direction of the recording medium in the X direction, the width direction of the recording medium in the transport path within the inkjet recording device in the Y direction, and the height direction of the device in the Z direction.

[0145] The recording device 10 shown in Figure 1 is a line-type inkjet printer (hereinafter also referred to as a "line printer") capable of high-speed and high-density printing. As shown in Figure 1, the recording device 10 includes a feeding unit 12 for storing a recording medium P such as paper, a transport unit 14, a belt transport unit 16, a recording unit 18, a face-down (Fd) discharge unit 20 as an "discharge unit", an Fd placement unit 22 as a "placement unit", a reversal path unit 24 as a "reversal transport mechanism", a face-up (Fu) discharge unit 26, and a Fu placement unit 28.

[0146] The feeding unit 12 is located at the bottom of the recording device 10. The feeding unit 12 includes a feeding tray 30 for storing recording media P and a feeding roller 32 for sending the recording media P stored in the feeding tray 30 to the transport path 11.

[0147] The recording medium P stored in the feeding tray 30 is fed along the transport path 11 to the transport unit 14 by the feeding roller 32. The transport unit 14 is equipped with a transport drive roller 34 and a transport driven roller 36. The transport drive roller 34 is rotationally driven by a drive source (not shown). In the transport unit 14, the recording medium P is held between the transport drive roller 34 and the transport driven roller 36 and transported to the belt transport unit 16 located downstream of the transport path 11.

[0148] The belt conveying unit 16 includes a first roller 38 located upstream in the conveying path 11, a second roller 40 located downstream, an endless belt 42 rotatably mounted on the first roller 38 and the second roller 40, and a support 44 that supports the upper section 42a of the endless belt 42 between the first roller 38 and the second roller 40.

[0149] The endless belt 42 is driven by a first roller 38 or a second roller 40, driven by a drive source (not shown), to move in the upper section 42a from the +X direction to the -X direction. As a result, the recording medium P conveyed from the conveying section 14 is further conveyed downstream of the conveying path 11 in the belt conveying section 16.

[0150] The recording unit 18 includes a line-type inkjet head 48 and the inkjet head 48 The recording unit 18 is equipped with a head holder 46 that holds the recording medium. The recording unit 18 may be a serial type in which an inkjet head is provided on a carriage that moves back and forth in the Y-axis direction. The inkjet head 48 is positioned to face the upper section 42a of an endless belt 42 supported by a support 44. When the recording medium P is transported in the upper section 42a of the endless belt 42, the inkjet head 48 ejects ink or the like towards the recording medium P and performs recording. The recording medium P is transported downstream of the transport path 11 by the belt transport unit 16 while recording is being performed.

[0151] The inkjet head 48 may be provided in multiple locations; for example, it may have an inkjet head for applying ink and an inkjet head for applying processing liquid.

[0152] Here, a "line-type inkjet head" refers to a head used in a recording device where the nozzle area formed in a direction intersecting the transport direction of the recording medium P is provided to cover the entire intersecting direction of the recording medium P, and an image is formed by fixing either the head or the recording medium P and moving the other. Note that the nozzle area in the intersecting direction of the line head does not necessarily have to cover the entire intersecting direction of all recording medium P supported by the recording device.

[0153] Furthermore, a first branching section 50 is provided downstream of the transport path 11 of the belt transport section 16. The first branching section 50 is configured to switch between a transport path 11 that transports the recording medium P to the Fd discharge section 20 or the Fu discharge section 26, and an inversion path 52 of an inversion path section 24 that inverts the recording surface of the recording medium P and transports the recording medium P back to the recording section 18. When the recording medium P is transported after being switched to the inversion path 52 by the first branching section 50, the recording surface is inverted during the transport process in the inversion path 52, and it is transported back to the recording section 18 so that the side opposite to the original recording surface faces the inkjet head 48.

[0154] A second branching section 54 is provided downstream of the first branching section 50 along the transport path 11. The second branching section 54 is configured to switch the transport direction of the recording medium P so as to transport the recording medium P toward the Fd discharge section 20 or toward the Fu discharge section 26.

[0155] The recording medium P transported toward the Fd discharge section 20 at the second branching section 54 is discharged from the Fd discharge section 20 and placed on the Fd mounting section 22. At this time, the recording surface of the recording medium P is placed facing the Fd mounting section 22. The recording medium P transported toward the Fu discharge section 26 at the second branching section 54 is discharged from the Fu discharge section 26 and placed on the Fu mounting section 28. At this time, the recording surface of the recording medium P is placed facing away from the Fu mounting section 28.

[0156] In this embodiment, the recording apparatus may apply the processing liquid and ink composition by scanning while moving the relative positions of the inkjet head performing the processing liquid application process and the inkjet head performing the ink application process with respect to the recording medium. Alternatively, the inkjet head performing the processing liquid application process and the inkjet head performing the ink application process may be line heads having a length greater than or equal to the recording width in a direction intersecting the scanning direction of the recording medium, and recording may be performed by performing a single scan.

[0157] Line printers have a high recording speed and immediately transport ink-coated recording media to stack many of them on the output tray. Therefore, if the ink-coated recording media curls, the line printer may not be able to transport them properly, causing paper jams. Also, if cut paper is used as the recording medium, curling makes it difficult to stack them on the output tray. In the recording method according to this embodiment, the processing solution of this embodiment is applied to the recording medium. This reduces the occurrence of primary and secondary curls, making it effective and particularly useful in line printers.

[0158] Although an example using a line-type inkjet head has been described, the recording device according to this embodiment may also be a serial printer using a serial-type inkjet head. When using a serial printer, printing is performed by moving the inkjet head in a direction intersecting the transport direction while transporting the recording medium in the transport direction. Even when using a serial printer, recording on an absorbent recording medium presents challenges in the color development of the recorded material, so the above-described recording method can be used to improve the color development of the recorded material.

[0159] 4. Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" below refers to mass.

[0160] 4.1. Preparation of Ink Composition The ink compositions used in each example and comparative example are obtained by the following procedure.

[0161] Figure 2 (Table 1) is a table showing the composition of the ink composition. Each component is placed in a container to obtain the composition shown in Table 1, mixed and stirred with a magnetic stirrer for 2 hours, and then filtered through a 5 μm pore size membrane filter to obtain the ink composition used in each example and comparative example. The numerical values ​​for each component in the table represent mass percent.

[0162] The abbreviations and other product names used in Table 1 are explained below.

[0163] <Pigments> • Self-dispersing pigment: Product name "CAB-O-JET300", manufactured by Cabot Corporation, solids content 15% <Resin> • Resin emulsion: A styrene-acrylic resin emulsion is prepared using styrene monomer and acrylic monomer. The temperature (Tg) is 10°C and the acid value is 33 mg KOH / g. <Surfactants> • E1010: Product name "Olefin E1010", manufactured by Nisshin Chemical Industry Co., Ltd., acetylene glycol-based surfactant.

[0164] 4.2. Preparation of the treatment solution The processing solutions used in each example and comparative example are obtained by the following procedure.

[0165] Figure 3 (Table 2) is a table showing the composition of the treatment solution. Similar to section 5.1, "Preparation of Ink Composition," each component is placed in a container to obtain the composition shown in Table 2. The mixture is then mixed and stirred with a magnetic stirrer for 2 hours, and finally filtered through a 5 μm pore size membrane filter to obtain the treatment solution used in each example and comparative example. The values ​​in the table represent mass percent.

[0166] The abbreviations and other product names used in Table 2 are explained below.

[0167] <Agglutinant> Calcium nitrate: Solubility in water at 20°C = 121.2g / 100g water Calcium formate: Water solubility at 20°C = 16.6g / 100g water <Moisturizer> Trimethylglycine:betaine <Organic solvents> • 1,2-Hexanediol: Surface tension at 25°C = 26.4 mN / m • 1,2-Pentanediol: Surface tension at 25°C = 27.7 mN / m • 1,2-Butanediol: Surface tension at 25°C = 31.6 mN / m The surface tension is measured using a surface tension meter (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.) by the Wilhelmy method at a temperature of 25°C. <Surfactants> • E1010: Product name "Olefin E1010", manufactured by Nisshin Chemical Industry Co., Ltd., acetylene glycol-based surfactant, HLB value 13-14 • E1004: Product name "Orphine E1004", manufactured by Nisshin Chemical Industry Co., Ltd., acetylene glycol-based surfactant, HLB 7-9 • Surfinol 420: Product name "Surfinol 420", manufactured by Nisshin Chemical Industry Co., Ltd., acetylene glycol-based surfactant, HLB value 4 • BYK-348: Product name, manufactured by Big Chemie Japan, silicone-based surfactant

[0168] 4.3. Evaluation Method 4.3.1. Recording Conditions The recording device used is a modified LX-10050 (Seiko Epson Corporation, line printer). This recording device has a recording resolution of 600 x 2400 dpi and a processing fluid density of 4.5 mg / inch at 100% duty cycle. 2 Set it so that it becomes like this.

[0169] The recording medium is A4 size business plain paper (manufactured by Seiko Epson Corporation, copy paper) (hereinafter also referred to as "business plain paper"), or A4 size Xerox P paper (manufactured by Fuji Xerox Co., Ltd., copy paper, basis weight 64 g / m²). 2 Use paper with a thickness of 88 μm (hereinafter also referred to as "thick paper").

[0170] 4.3.2. Color development The recording device is filled with processing solution, and a solid pattern with a duty cycle of 100% is printed onto plain business paper. Then, the recording device is filled with an ink composition, and a recording is obtained by printing onto the plain business paper to which the processing solution has adhered. The optical density (OD value) of the obtained recording is measured using a fluorescence spectrophotometer ("FD-7", manufactured by Konica Minolta, Inc.). The evaluation criteria are as follows, and the results are shown in Figures 3-5 (Tables 2-4).

[0171] (Evaluation Criteria) A: OD value of 1.53 or higher B: OD value is 1.49 or higher and less than 1.53 C:OD value is 1.45 or higher and less than 1.49 D:OD value is less than 1.45

[0172] 4.3.3. Filling of the treatment solution A processing solution containing 5% dye was filled into the recording device, with a resolution of 600 x 1200 dpi, a duty cycle of 50%, and a dosing rate of 2.25 mg / inch. 2 A solid pattern is printed as shown. Business plain paper is used as the recording medium. The dye used is a water-soluble blue dye. The resulting recording is observed under a microscope to evaluate the coating area of ​​the processing solution. The evaluation criteria are as follows, and the results are shown in Tables 2 to 4.

[0173] (Evaluation Criteria) A: The coverage area of ​​the treatment solution is 50% or more. B: The coverage area of ​​the treatment solution is 45% or more but less than 50%. C: The coverage area of ​​the treatment solution is less than 45%.

[0174] 4.3.4. Secondary curl The recording device is filled with processing liquid, and a solid pattern with a duty cycle of 100% is printed onto thick paper at a temperature of 25°C and a humidity of 50%. Then, the recording device is filled with an ink composition, and a solid pattern with a duty cycle of 100% is printed onto the thick paper to which the processing liquid has adhered to obtain a recorded material. The obtained recorded material is placed with the printed side facing up and left for one week, after which the amount by which the edge of the recorded material rises from the floor surface (hereinafter also referred to as "rising amount") is measured. The evaluation criteria are as follows, and the results are shown in Tables 2 to 4.

[0175] (Evaluation Criteria) A: The amount of buoyancy is less than 10 mm. B: The amount of buoyancy is 10 mm or more but less than 20 mm. C: The amount of buoyancy is 20 mm or more.

[0176] 4.3.5.Cloud point The treatment solutions prepared in section 4.2, "Preparation of Treatment Solution," for each example and comparative example were sealed in 100 mL bottles and left in a 60°C constant temperature bath for 24 hours. After 24 hours, the condition of the treatment solution was visually inspected. The evaluation criteria were as follows, and the results are shown in Figures 3-5 (Tables 2-4).

[0177] (Evaluation Criteria) A: No oil separation B: Slightly cloudy C: Separates into oily substance.

[0178] 4.3.6.Initial filling property When the recording device is filled with a processing fluid cartridge and the initial filling is performed, a nozzle check pattern is printed after the initial filling sequence. If there are gaps or distortions in the nozzle check pattern of the recording material, the nozzle check pattern is printed again manually. The number of times until no gaps or distortions are found in the nozzle check pattern, that is, until all nozzles are able to eject, is measured. A gap refers to a non-ejected area confirmed by printing the nozzle check pattern, and distortion refers to an area where the droplet flight is bent, confirmed by printing the nozzle check pattern. The evaluation criteria are as follows, and the results are shown in Tables 2 to 4.

[0179] (Evaluation Criteria) A: All nozzles can dispense using only the initial filling sequence. B: Initial filling sequence and all nozzles can dispense within 3 manual operations. C: The initial filling sequence and manual operation must be performed more than three times before all nozzles can dispense.

[0180] 4.3.7.Discharge stability A cartridge is installed in the recording device and filled with processing fluid. Confirm that the processing fluid is ejected from multiple nozzles connected to the cartridge, and then print a test pattern continuously on 30 sheets of plain business paper. After printing 30 sheets, perform a nozzle check to verify the nozzle ejection status. The evaluation criteria are as follows, and the results are shown in Tables 2-4. Wrinkling is defined as a point of impact deviation of more than half the distance between nozzles.

[0181] (Evaluation Criteria) A: No nozzle clogging or wrinkling. B: Nozzle clogging or unevenness is limited to 5 lines or less, and can be resolved with one head cleaning. C: No more than 10 nozzle clogs or misaligned prints, and these can be resolved with two or more head cleanings.

[0182] 4.4. Evaluation Results The recording method, comprising a processing liquid adhesion step of ejecting a processing liquid containing a coagulant from an inkjet head and adhering it to a recording medium, and an ink adhesion step of ejecting an ink composition, which is an aqueous ink containing a colorant, from an inkjet head and adhering it to the recording medium, wherein the recording medium is an absorbent recording medium, the processing liquid contains a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C and an acetylene glycol-based surfactant with an HLB value of 5 or more, the content of the 1,2-alkanediol is 3% by mass or more of the total amount of the processing liquid, and the coagulant contains a calcium salt, the content of the calcium salt is 5% by mass or more of the total amount of the processing liquid, all of the examples relating to this recording method show good results in the evaluation items for color development. Furthermore, filling, secondary curl suppression, water solubility, initial filling, and ejection stability also tend to be excellent.

[0183] In contrast, the comparative examples that do not meet the above conditions do not yield good results in the color development evaluation item.

[0184] A comparison of Example 1 with Comparative Examples 1, 5, and 7 shows that when the processing solution contains a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C, the color development of the recorded material is improved. The filling of the processing solution during recording is also improved. Furthermore, in the evaluation item for cloud point, oily separation of the processing solution does not occur. Moreover, when the content of the 1,2-alkanediol mentioned above is 3% by mass or more relative to the total amount of the processing solution, the color development of the recorded material is further improved.

[0185] A comparison between Example 1 and Comparative Examples 2 and 3 demonstrates that the inclusion of an acetylene glycol-based surfactant in the processing solution improves the color development of the recorded material. Furthermore, the ejection stability during recording is improved, and the processing solution fills the record well. Additionally, the HLB value of the contained acetylene glycol-based surfactant is 5 or higher, preventing oily separation of the processing solution.

[0186] A comparison of Example 1 with Comparative Examples 4 and 6 shows that when the treatment solution contains a flocculant, and the flocculant is a calcium salt, the color development of the recorded material is improved. Furthermore, when the calcium salt content is 5% by mass or more relative to the total amount of the treatment solution, the color development of the recorded material is even better.

[0187] Examples 1-3 show that the presence of betaine in the processing solution tends to reduce the occurrence of secondary curl in the recorded material. Furthermore, when the betaine content is within a predetermined range relative to the total volume of the processing solution, the ejection stability during recording is improved.

[0188] Examples 1, 4, and 5 show that when the acetylene glycol-based surfactant contained in the treatment solution includes an acetylene glycol-based surfactant with an HLB value of 10 or higher, the color development and water solubility are excellent, and when it includes an acetylene glycol-based surfactant with an HLB value of 5 or higher and less than 10, the filling of the treatment solution is even better. It is preferable to include an acetylene glycol-based surfactant with an HLB value of 10 or higher and an acetylene glycol-based surfactant with an HLB value of 5 or higher and less than 10.

[0189] Examples 6 and 10 show that when the content of 1,2-alkanediols with a surface tension of 30 mN / m or less at 25°C in the processing solution is within a predetermined range relative to the total amount of the processing solution, the ejection stability during recording is improved, the filling of the recording medium by the processing solution is better, and the color development of the recorded material is improved.

[0190] Examples 7 and 9 show that the calcium salt content in the treatment solution is, relative to the total volume of the treatment solution. Within the specified range, the color reproduction of the recorded material is improved. Furthermore, secondary curl suppression is enhanced.

[0191] From Example 8, it was found that when the calcium salt contained in the processing solution is an inorganic calcium salt, the color development of the recorded material is improved.

[0192] Example 11 shows that regardless of the type of 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C, its inclusion in the processing solution results in good color development of the recorded material.

[0193] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0194] From the embodiments and modifications described above, the following can be derived.

[0195] One method of recording is: A processing liquid application step in which a processing liquid containing a coagulant is ejected from an inkjet head and adhered to a recording medium, The process includes an ink application step in which an ink composition, which is a water-based ink containing a colorant, is ejected from an inkjet head and attached to the recording medium, The recording medium is an absorbent recording medium, The aforementioned treatment solution contains a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C, and an acetylene glycol-based surfactant with an HLB value of 5 or more. The content of the 1,2-alkanediol is 3% by mass or more relative to the total amount of the treatment solution. The aforementioned flocculant contains a calcium salt, The calcium salt content is 5% by mass or more relative to the total volume of the treatment solution.

[0196] This recording method ensures good penetration of the processing solution into the recording medium, suppresses the penetration of the ink composition attached by the processing solution, and improves the color development of the recorded material. Furthermore, it improves initial filling of the recording device and enhances ejection stability during recording.

[0197] In the recording method described above, the processing liquid may contain betaine, and the betaine content may be 2% by mass or more and 10% by mass or less of the total amount of the processing liquid.

[0198] This recording method reduces the occurrence of secondary curl in the recorded material.

[0199] In the recording method described above, the calcium salt content may be 8% by mass or more and 25% by mass or less with respect to the total volume of the processing solution.

[0200] According to this recording method, the colorants in the ink composition are suitably aggregated, resulting in good color development of the recorded material.

[0201] In the recording method described above, the content of the 1,2-alkanediol may be 3% by mass or more and 9% by mass or less with respect to the total amount of the processing solution.

[0202] This recording method results in improved ejection stability during recording. Furthermore, better immersion of the recording medium by the processing solution enhances the color development of the recorded material.

[0203] In the recording method described above, the acetylene glycol-based surfactant may include an acetylene glycol-based surfactant with an HLB value of 10 or more, and an acetylene glycol-based surfactant with an HLB value of 5 or more and less than 10.

[0204] This recording method results in better immersion of the recording medium by the processing solution and improved color development of the recorded material.

[0205] In the recording method described above, the recording medium may be plain paper.

[0206] According to this recording method, even with materials that are easily permeated by the ink composition, the penetration of the ink composition is reduced by the processing solution, resulting in a recording with good color development.

[0207] In the recording method described above, the calcium salt may be an inorganic calcium salt.

[0208] This recording method results in better color reproduction of the recorded material.

[0209] One embodiment of a processing solution ink set is: This is used in the recording method described above and comprises the processing liquid and the ink composition.

[0210] This processing solution ink set allows for the creation of recordings exhibiting good color development.

[0211] One embodiment of a recording device is: This is used in the recording method described above. The aforementioned processing liquid, The aforementioned ink composition, An inkjet head that performs the processing liquid application step, It includes an inkjet head that performs the aforementioned ink application process.

[0212] This recording device allows the above-described recording method to be performed effectively, and a recording exhibiting good color development can be obtained.

[0213] In the above recording device, The processing liquid and the ink composition are applied by scanning while moving the relative positions of the inkjet head performing the processing liquid application step and the inkjet head performing the ink application step and the recording medium. The inkjet head performing the processing liquid application step and the inkjet head performing the ink application step are line heads having a length greater than or equal to the recording width in a direction intersecting the scanning direction of the recording medium. Recording may be performed by performing the aforementioned scan once.

[0214] This recording device allows for the acquisition of recordings with good color reproduction. [Explanation of symbols]

[0215] 10...Recording device, 11...Conveying path, 12...Feeding unit, 14...Conveying unit, 16...Belt conveying unit, 18...Recording unit, 20...Fd discharge unit, 22...Fd placement unit, 24...Reversing path unit, 26...Fu discharge unit, 28...Fu placement unit, 30...Feeding tray, 32...Feeding roller, 34...Conveying drive roller, 36...Conveying driven roller, 38...First roller, 40...Second roller, 42...Endless Belt, 42a... Upper section of endless belt, 44... Support, 46... Head holder, 48... Inkjet head, 50... First branching section, 52... Reversal path, 54... Second branching section, 56... Discharge roller pair, 64... Discharge drive roller, 68... Drive shaft, 76... Mounting surface, 78... Convex portion, 80... First biasing member, 82... Second biasing member, 84, 86... Support shaft, P... Recording medium

Claims

1. A processing liquid application step in which a processing liquid containing a coagulant is ejected from an inkjet head and adhered to a recording medium, The process includes an ink application step in which an ink composition, which is a water-based ink containing a colorant, is ejected from an inkjet head and attached to the recording medium, The recording medium is an absorbent recording medium, The aforementioned treatment solution contains a 1,2-alkanediol with a surface tension of 30 mN / m or less at 25°C, and an acetylene glycol-based surfactant with an HLB value of 5 or more. The content of the 1,2-alkanediol is 3% by mass or more relative to the total amount of the treatment solution. The aforementioned flocculant contains a calcium salt, A recording method wherein the calcium salt content is 5% by mass or more relative to the total volume of the treatment solution.

2. The aforementioned processing solution contains betaine, The recording method according to claim 1, wherein the betaine content is 2% by mass or more and 10% by mass or less with respect to the total amount of the processing liquid.

3. The recording method according to claim 1, wherein the content of the calcium salt is 8% by mass or more and 25% by mass or less with respect to the total amount of the processing liquid.

4. The recording method according to claim 1, wherein the content of the 1,2-alkanediol is 3% by mass or more and 9% by mass or less with respect to the total amount of the processing solution.

5. The recording method according to claim 1, wherein the acetylene glycol-based surfactant comprises an acetylene glycol-based surfactant with an HLB value of 10 or more, and an acetylene glycol-based surfactant with an HLB value of 5 or more and less than 10.

6. The recording method according to claim 1, wherein the recording medium is plain paper.

7. The recording method according to claim 1, wherein the calcium salt is an inorganic calcium salt.

8. This is used in the recording method described in any one of claims 1 to 7, A processing liquid ink set comprising the processing liquid and the ink composition.

9. This is used in the recording method described in any one of claims 1 to 7, The aforementioned processing liquid, The aforementioned ink composition, An inkjet head that performs the processing liquid application step, A recording device having an inkjet head that performs the aforementioned ink application process.

10. A recording device according to claim 9, The processing liquid and the ink composition are applied by scanning while moving the relative positions of the inkjet head performing the processing liquid application step and the inkjet head performing the ink application step and the recording medium. The inkjet head performing the processing liquid application step and the inkjet head performing the ink application step are line heads having a length greater than or equal to the recording width in a direction intersecting the scanning direction of the recording medium. A recording device that performs recording by performing the aforementioned scan once.

Images