Inkjet ink composition and recording method

Abstract

To provide an ink jet ink composition having excellent conformability to a recording medium and also having excellent clogging resistance and adhesion.SOLUTION: An ink jet ink composition of the present disclosure is a water-based ink which includes: a colorant; a surfactant; a fixing resin; and an organic solvent, where the surfactant includes a silicone-based surfactant having an HLB value of 10.5 or less, the fixing resin includes an acrylic-based resin having a glass transition temperature of 35°C to 95°C, and the organic solvent includes a 1,2-alkanediol having 4 or less carbon atoms and an alkanediol having diols at both terminals and 3 to 5 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink-jet ink composition and a recording method. [Background technology]

[0002]

[0003] An inkjet recording method is known in which minute ink droplets are ejected from nozzles in a recording head of an inkjet recording apparatus to record an image on a recording medium, and its use in the fields of sign printing and high-speed label printing is also being considered. When recording an image on a recording medium with low ink absorption (e.g., art paper or coated paper) or a recording medium with no ink absorption (e.g., plastic film), the use of an aqueous inkjet ink composition containing a fixing resin (hereinafter also referred to as "aqueous ink," "ink composition," or "ink") has been considered as the ink from the viewpoints of environmental friendliness and safety to the human body.

[0003] For example, Patent Document 1 describes that propylene glycol, an organic solvent that acts as a moisturizer, is contained in an ink composition to prevent the ink composition from drying out. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-154014 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when such water-based inks are used, there are problems such as poor ink coverage on the recording medium, i.e., the ink does not wet and spread easily on the recording medium, and sufficient color development cannot be achieved. Furthermore, there are also problems such as poor clogging resistance and poor adhesion.

[0006] Therefore, it is desirable to have excellent filling ability on the recording medium, and also excellent clogging resistance and adhesion. [Means for solving the problem]

[0007] One embodiment of the inkjet ink composition according to the present invention comprises: The toner includes a colorant, a surfactant, a fixing resin, and an organic solvent, the surfactant comprises a silicone surfactant with an HLB value of 10.5 or less, the fixing resin contains an acrylic resin having a glass transition point of 35 to 95°C, the organic solvent contains a 1,2-alkanediol having 4 or less carbon atoms and an alkanediol having 3 to 5 carbon atoms at both ends, It is a water-based ink.

[0008] One aspect of the recording method according to the present invention is to The method further comprises a step of ejecting the ink-jet ink composition of the above embodiment by an ink-jet method and depositing it onto a recording medium. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an example of an inkjet recording apparatus. [Figure 2] FIG. 1 is a schematic diagram of the periphery of a carriage in an example of an inkjet recording apparatus. [Figure 3] FIG. 1 is a block diagram of an example of an inkjet recording apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described. The embodiments described below are examples of the present invention. The present invention is not limited to the following embodiments, and includes various modified forms that are implemented within the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

[0011] 1. Inkjet ink composition An inkjet ink composition according to one embodiment of the present invention comprises: The toner includes a colorant, a surfactant, a fixing resin, and an organic solvent, the surfactant comprises a silicone surfactant with an HLB value of 10.5 or less, the fixing resin contains an acrylic resin having a glass transition point of 35 to 95°C, the organic solvent contains a 1,2-alkanediol having 4 or less carbon atoms and an alkanediol having 3 to 5 carbon atoms at both ends, It is a water-based ink.

[0012] According to the above-mentioned constitution, it is possible to provide an inkjet ink composition that has excellent ink filling properties on a recording medium, and has excellent clogging resistance and adhesion properties.

[0013] When recording on a recording medium, there are problems such as poor ink coverage on the recording medium, i.e., the ink does not wet and spread easily on the recording medium, and sufficient color development cannot be achieved. This tendency is particularly pronounced when recording on low-absorbency or non-absorbency recording media (especially film). Now, by incorporating a silicone surfactant with an HLB value below a specified value into the ink, the ink easily wets and spreads, providing sufficient color development even when printing on low-absorbency or non-absorbency recording media.

[0014] On the other hand, silicone surfactants with a relatively low HLB value (below a predetermined value) tend to dissolve or swell the acrylic fixing resin when the ink dries. That is, when the water contained in the ink evaporates and the solids, such as the fixing resin, and the organic solvent are concentrated, silicone surfactants with a relatively low HLB value tend to dissolve or swell the fixing resin. As a result, when the ink dries inside the recording head, the fixing resin melts, causing clogging. In other words, inks containing a silicone surfactant with an HLB value below a predetermined value and an acrylic resin with a glass transition temperature within a predetermined range have excellent embedding properties on the recording medium, but when the ink dries, the fixing resin tends to melt inside the recording head, causing clogging. However, increasing the content of organic solvents that act as humectants or incorporating organic solvents with high humectant properties in order to prevent clogging due to drying results in poor drying of the ink and reduced adhesion. Thus, it has traditionally been difficult to achieve both clogging resistance and adhesion.

[0015] To improve clogging resistance, it is possible to use organic solvents in the ink, such as 1,2-alkanediols with four or fewer carbon atoms. However, as a humectant used in ink, 1,2-alkanediols having four or less carbon atoms have excellent drying properties in the drying process to complete recording, and tend to improve adhesion between the ink and the recorded matter. However, perhaps because the moisturizing properties are insufficient to prevent the silicone surfactants, which have a relatively low HLB value, from dissolving or swelling the acrylic fixing resin, the fixing resin melts and clogging occurs. On the other hand, simply increasing the content of organic solvents that act as humectants or adding organic solvents with high moisturizing properties in order to ensure moisturizing properties will result in poor drying of the ink and reduced adhesion to the recording medium.

[0016] As a result of extensive research by the present inventors, it has been found that 1,2-alkanediols having 4 or less carbon atoms and 1,2-alkanediols having 3 or less carbon atoms are It was found that by combining 1,2-alkanediols with 4 or less carbon atoms and alkanediols with 1,2- to 5-carbon atoms at both ends, both drying properties and moisture retention can be achieved. That is, 1,2-alkanediols with 4 or less carbon atoms do not have sufficient moisture retention to prevent silicone surfactants with relatively low HLB values ​​from dissolving or swelling acrylic fixing resins, but they have excellent drying properties. On the other hand, alkanediols with 3 to 5 carbon atoms at both ends have better moisture retention and can ensure sufficient clogging resistance, but they have poor drying properties and poor adhesion. By combining these two types, it was possible to achieve both clogging resistance and adhesion.

[0017] The components contained in the inkjet ink composition according to this embodiment and the components that can be contained therein will be described below.

[0018] 1.1 Colorants The inkjet ink composition according to this embodiment contains a coloring material, which may be at least one of a pigment and a dye.

[0019] <Pigments> The use of a pigment as a coloring material can improve the lightfastness of the ink composition. Both inorganic and organic pigments can be used as the pigment. Examples of the pigment include color pigments such as cyan, yellow, magenta, and black, as well as special color pigments such as white pigments and luster pigments.

[0020] Examples of organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxane pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, thioindigo pigments, isoindolinone pigments, azomethine pigments, dye chelates, dye lakes, nitro pigments, nitroso pigments, aniline black, and azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments.

[0021] Specific examples of organic pigments include the following:

[0022] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 16, 22, and 60; and CI Vat Blue 4 and 60. Preferably, the cyan pigment is selected from the group consisting of CI Pigment Blue 15:3, 15:4, and 60, either singly or in combination.

[0023] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, and CI Pigment Violet 19, and preferably a pigment selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19, either alone or in combination.

[0024] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, and 185, and preferably a single pigment selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, and 138, or a mixture of two or more pigments.

[0025] Orange pigments include CI Pigment Orange 36 or 43, or It is a mixture.

[0026] The green pigment is CI Pigment Green 7 or 36 or a mixture thereof.

[0027] Examples of black pigments include furnace black, lamp black, acetylene black, and channel black (CI Pigment Black 7). Commercially available products include No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B (trade names, manufactured by Mitsubishi Chemical Corporation), and color blacks FW1, FW2, FW2V, FW18, FW200, S150, S160, and S170, and Pretex 3. 5, U, V, 140U, Special Black 6, 5, 4A, 4, 250, etc. (trade names, manufactured by Degussa), Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, etc. (all trade names, manufactured by Columbia Carbon), Ligal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12, etc. (trade names, manufactured by Cabot Corporation). These carbon blacks may be used alone or in combination of two or more.

[0028] The luster pigment is not particularly limited as long as it can exhibit luster when attached to a medium, but examples include metal particles of one or more alloys (also called metal pigments) selected from the group consisting of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper, and pearl pigments with pearly luster. Representative examples of pearl pigments include pigments with pearly luster or interference luster, such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride. The luster pigment may also be surface-treated to suppress reaction with water.

[0029] Examples of white pigments include metal oxides, barium sulfate, calcium carbonate, and other metal compounds. Examples of metal oxides include titanium dioxide, zinc oxide, silica, alumina, magnesium oxide, and the like. The white pigment may also be a particle having a hollow structure.

[0030] The pigments may be used alone or in combination of two or more. From the viewpoint of storage stability such as light resistance, weather resistance, and gas resistance, the pigment is preferably an organic pigment.

[0031] (Distribution method) When a pigment is used as the colorant, the pigment is preferably added to the aqueous ink composition as a pigment dispersion obtained by dispersing the pigment in water with a dispersant, or as a pigment dispersion obtained by dispersing a self-dispersing surface-treated pigment in which hydrophilic groups have been introduced onto the pigment particle surfaces by utilizing a chemical reaction, or as a pigment dispersion obtained by dispersing a polymer-coated pigment in water.

[0032] The dispersant is not particularly limited, and examples thereof include polymer dispersants and surfactants. The polymer dispersant is not particularly limited, and examples thereof include proteins such as glue, gelatin, casein, and albumin, natural gums such as gum arabic and gum tragacanth, glucosides of saponin, alginic acid and propylene glycol ester, triethanolamine alginate, alginic acid fermentation product of ammonium alginate, methyl cellulose, carboxymethyl cellulose, cellulose derivatives of ethylhydroxycellulose, polyvinyl alcohols, polypyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, acrylic resin, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, Examples of the surfactant include a styrene-acrylic resin such as a styrene-m-methylstyrene-acrylic acid copolymer, a styrene-maleic acid copolymer, a styrene-maleic anhydride copolymer, a vinyl naphthalene-acrylic acid copolymer, a vinyl acetate-ethylene copolymer, a vinyl acetate-fatty acid vinyl ethylene copolymer, a vinyl acetate-maleic acid ester copolymer, a vinyl acetate-croton copolymer, and a vinyl acetate-acrylic acid copolymer, and salts thereof. Examples of the surfactant include, but are not limited to, anionic surfactants, nonionic surfactants, and amphoteric surfactants.

[0033] The self-dispersing surface-treated pigments having hydrophilic groups introduced therein are surface-treated to directly bond carboxyl groups and their salts to the pigment surface, thereby enabling them to be dispersed or dissolved in water without a dispersant. More specifically, they can be obtained by grafting functional groups or molecules containing functional groups onto the pigment surface through physical treatment using vacuum plasma or chemical treatment using an oxidizing agent such as sodium hypochlorite or ozone. A single or multiple types of functional groups may be grafted onto a single pigment particle. The type and degree of grafting of functional groups may be determined appropriately, taking into consideration dispersion stability in the aqueous ink composition, color density, and drying properties at the front of the recording head.

[0034] The above-described polymer-coated pigment can be obtained, for example, by dispersing the pigment using a dispersant having a polymerizable group, followed by emulsion polymerization in water using a monomer copolymerizable with the dispersant (copolymerizable monomer) and a photoradical polymerization initiator. Among these polymers, those polymerized by a known polymerization method using a photoradical polymerization initiator and a monomer or oligomer having at least one double bond selected from the group consisting of an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group are preferred. The emulsion polymerization can be performed using a conventional method, and the polymerization proceeds in the presence of an emulsifier by free radicals generated by thermal decomposition of a water-soluble photoradical polymerization initiator.

[0035] The pigment and dispersant constituting the pigment dispersion may each be used alone or in combination of two or more.

[0036] <dye> The ink composition may contain a dye as a colorant. The dye is not particularly limited, and may be an acid dye, a direct dye, a reactive dye, a basic dye, or a disperse dye. Examples of dyes include CI Acid Yellow 17, 23, 42, 44, 79, and 142, CI Acid Red 52, 80, 82, 249, 254, and 289, CI Acid Blue 9, 45, and 249, CI Acid Black 1, 2, 24, and 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, and 173. CI Direct Red 1, 4, 9, 80, 81, 132, 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, 141, 249; and CI Reactive Black 3, 4, 35.

[0037] These coloring materials may be used alone or in combination of two or more types, regardless of whether they are pigments or dyes.

[0038] The total content of the coloring materials is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1 to 10% by mass, and even more preferably 2 to 8% by mass, relative to the total mass (100% by mass) of the ink composition.

[0039] 1.2 Surfactants The inkjet ink composition according to this embodiment contains a surfactant, and the surfactant contains a silicone surfactant with an HLB value of 10.5 or less.

[0040] 1.2.1 Silicone surfactants with an HLB value of 10.5 or less The HLB value of a silicone surfactant having an HLB value of 10.5 or less is defined as follows.

[0041] In the present invention, the "HLB value (hydrophilic lipophilic balance)" refers to 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)

[0042] The HLB value is determined by the balance between the hydrophilic and lipophilic groups of a surfactant molecule; a high HLB value qualitatively indicates that the surfactant is highly hydrophilic, while a low HLB value qualitatively indicates that the surfactant is highly lipophilic.

[0043] The HLB value of the silicone surfactant contained in the inkjet ink composition according to this embodiment is preferably 2 to 10.5. The upper limit of the HLB value of the silicone surfactant may be 9 or less, 8 or less, 6 or less, or 5 or less. The lower limit of the HLB value of the silicone surfactant may be 2.5 or more, 3 or more, or 4 or more. Furthermore, it may be 6 or more, 7 or more, 8 or more, or 9 or more. When the upper limit of the HLB value of the silicone surfactant is within the above range, the ink wetting and spreading is further improved, and therefore filling tends to be better. Also, when the lower limit of the HLB value of the silicone surfactant is within the above range, adhesion of the acrylic resin tends to be reduced, and clogging resistance tends to be better. Therefore, when the HLB value of the silicone surfactant is within the above range, filling and clogging resistance tend to be improved in a balanced manner.

[0044] Commercially available silicone surfactants with an HLB value of 10.5 or less include KF-353 (HLB=10), KF-945 (HLB=4), KF-6020 (HLB=4), X-22-6191 (HLB=2), X-22-4515 (HLB=5), KF-6015 (HLB=5), KF-6017 (HLB=5), and KF-6038 (HLB=3) (all trade names, manufactured by Shin-Etsu Silicone Co., Ltd.), FZ-2116 (HLB=5), and FZ-2120 (HLB=6) (all trade names, manufactured by Toray Dow Corning Co., Ltd.), EMALEX-SS-5602 (HLB=9) (manufactured by Nippon Emulsion Co., Ltd.), Silface SAG005 (HLB=7) (manufactured by Nissin Chemical Industry Co., Ltd.), and Tego Wet 280 (HLB=3.5) (manufactured by Evonik Degussa).

[0045] The content of the silicone surfactant with an HLB value of 10.5 or less is preferably 0.01% by mass or more and 2.0% by mass or less, more preferably 0.05% by mass or more and 1.50% by mass or less, even more preferably 0.10% by mass or more and 1.3% by mass or less, and even more preferably 0.30 to 1.0% by mass, relative to the total mass of the ink composition.

[0046] 1.2.2 Other surfactants The surfactant contained in the inkjet ink composition according to this embodiment may also contain other surfactants, such as silicone surfactants with an HLB value of greater than 10.5, acetylene glycol surfactants, polyoxyalkylene alkyl ether surfactants, and fluorine-based surfactants.

[0047] Examples of commercially available silicone surfactants with an HLB value of more than 10.5 include BYK348 (HLB=14.6) (manufactured by BYK Japan), which is described in JP 2017-213797 A and the like.

[0048] Commercially available acetylene glycol surfactants include, for example, Surfynol SE (HLB=6), Surfynol 61 (HLB=6), Surfynol 104 (HLB=4), Surfynol 420 (HLB=4), Surfynol 82 (HLB=4), Surfynol DF110D (HLB=3), Surfynol 104S (HLB=4), Surfynol 104PG50 (HLB=4), Surfynol 420 (HLB=4), Surfynol 82 (HLB=4), and Surfynol MD-20 (HLB=4) (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.).

[0049] Examples of commercially available polyoxyalkylene alkyl ether surfactants include Noigen DH-0300 (HLB=4), Noigen ET-116B (HLB=12), Noigen DL-0415 (HLB=15), Noigen ET-106A (HLB=10.9), Noigen DH-0300 (HLB=4), Noigen YX-400 (HLB=18), Noigen EA-160 (HLB=15.4) (all trade names, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Newcol 1006 (trade name, polyoxyalkylene alkyl ether surfactant, manufactured by Nippon Nyukazai Co., Ltd.), and Emulgen 1108 (HLB=13.4) (trade name, polyoxyalkylene alkyl ether, manufactured by Kao Corporation).

[0050] The surfactants may be used alone or in combination of two or more.

[0051] The total content of the surfactants relative to the total mass of the ink composition is preferably 0.01% by mass to 2.0% by mass, more preferably 0.05% by mass to 1.50% by mass, even more preferably 0.10% by mass to 1.00% by mass, and even more preferably 0.30 to 1.00% by mass.

[0052] 1.3 Fixing resin The inkjet ink composition according to this embodiment contains a fixing resin, which contains an acrylic resin having a glass transition point of 35 to 95°C.

[0053] The fixing resin is a resin that, when incorporated into an ink composition, functions to improve the adhesion and abrasion resistance of the recorded material. This function is achieved by the fixing resin and other components, such as colorants, fusing together and adhering to the recording medium as the ink composition dries. The fixing resin can be formulated as a water-soluble resin or an emulsion of resin particles, with the latter being preferred.

[0054] 1.3.1 Acrylic resins with a glass transition temperature of 35 to 95°C The inkjet ink composition according to this embodiment contains a fixing resin that is an acrylic resin and has a glass transition point of 35 to 95°C.

[0055] Acrylic resin is a general term for polymers obtained by polymerizing at least an acrylic monomer such as (meth)acrylic acid or a (meth)acrylic acid ester as one component, and examples thereof include resins obtained from acrylic monomers and copolymers of acrylic monomers with other monomers. Examples of copolymers of acrylic monomers with other monomers include acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers. Examples of acrylic-vinyl resins include styrene-acrylic resins, which are copolymers of styrene monomers and acrylic monomers.

[0056] In this specification, the acrylic resin may be a styrene-acrylic resin as described above. In addition, in this specification, the term "(meth)acrylic" means at least one of acrylic and methacrylic.

[0057] Examples of acrylic monomers include (meth)acrylic acid; alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; amino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate; and glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate.

[0058] Examples of styrene-based monomers include styrene, α-methylstyrene, p-methoxystyrene, p-hydroxystyrene, and p-acetoxystyrene.

[0059] The styrene-acrylic resin may be a copolymer of a styrene-based monomer, an acrylic monomer, and other monomers. Examples of the other monomers include monomers copolymerizable with the styrene-based monomer and the acrylic monomer. More specifically, examples of the other monomers include nitrile-based monomers such as acrylonitrile, vinyl esters such as vinyl acetate, vinyl ethers such as vinyl ethyl ether, and unsaturated carboxylic acids or their anhydrides.

[0060] The acrylic resin may be one of these resins alone or a combination of two or more thereof, but preferably contains a styrene-acrylic resin, which tends to further improve adhesion.

[0061] The acrylic resin may be prepared by a known method, or a commercially available product such as JONCRYL 62J (Tg=85° C.) (product name, styrene acrylic resin, manufactured by BASF) may be used.

[0062] Known preparation methods include the following: A reactor equipped with a dropping device, thermometer, water-cooled reflux condenser, and stirrer is prepared, ion-exchanged water is charged into the reactor, and the polymerization initiator potassium persulfate is added at 70°C under a nitrogen atmosphere while stirring. Next, a monomer solution containing styrene and acrylic acid is prepared. The monomer solution is added dropwise to the reactor, allowing it to react and polymerize, resulting in a resin.

[0063] The glass transition temperature (Tg) of the acrylic resin can be adjusted, for example, by changing the mass ratio of each monomer in a monomer solution containing a styrene monomer and an acrylic monomer. More specifically, the Tg of the homopolymer of each monomer is confirmed, and the glass transition temperature of the acrylic resin can be adjusted by increasing the mass ratio of the monomer with a high Tg to increase the Tg, or by increasing the mass ratio of the monomer with a low Tg to decrease the Tg.

[0064] The glass transition point of the acrylic resin contained in the fixing resin is 35 to 95°C, and preferably 40 to 90°C. The upper limit of the glass transition point of the acrylic resin is preferably 85°C or lower, and may be 80°C or lower, 70°C or lower, or 65°C or lower. The lower limit of the glass transition point of the acrylic resin is more preferably 45°C or higher, even more preferably 50°C or higher, and particularly preferably 55°C or higher. When the glass transition point of the acrylic resin is within the above range, it tends to be possible to achieve both better clogging resistance and better adhesion. The object of the present invention is to provide a method for treating an acrylic resin that does not inherently cause clogging during the heating of the first heating step described below, by using a silicone surfactant having an HLB value of not more than a predetermined value. In other words, the problem that the present invention aims to solve occurs when the glass transition temperature of the acrylic resin is 35°C or higher.

[0065] The glass transition point of the acrylic resin can be measured by differential scanning calorimetry (DSC) in accordance with JIS K7121: 1987. An example of a commercially available differential scanning calorimetry (DSC) device is "DSC6220" (product name, manufactured by Seiko Electronics Corporation).

[0066] The content of the acrylic resin, as solid content, relative to the total mass of the ink composition is preferably 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 7% by mass, even more preferably 0.5% by mass to 5% by mass, particularly preferably 0.7% by mass to 3% by mass, and even more preferably 0.8 to 2% by mass.

[0067] 1.3.2 Other fixing resins The inkjet ink composition according to this embodiment may contain, as a fixing resin, a resin other than an acrylic resin having a glass transition point of 35 to 95° C. Examples of such fixing resins include urethane resins, fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, and ethylene vinyl acetate resins.

[0068] Urethane resin is a general term for resins having urethane bonds. In addition to urethane bonds, the urethane resin may be a polyether urethane resin containing ether bonds in the main chain, a polyester urethane resin containing ester bonds in the main chain, or a polycarbonate urethane resin containing carbonate bonds in the main chain. As the urethane-based resin, commercially available products may be used, and may be selected from commercially available products such as Superflex 210, 460, 460s, 840, and E-4000 (trade names, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, and D-6455 (trade names, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Takelac WS-6020, WS-6021, and W-512-A-6 (trade names, manufactured by Mitsui Chemicals Polyurethanes Inc.), Sancure 2710 (trade name, manufactured by Lubrizol), and Parmarin UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd.).

[0069] The vinyl chloride resin may be a vinyl chloride-vinyl acetate copolymer.

[0070] The polyolefin resin has an olefin such as ethylene, propylene, or butylene in its structural skeleton, and known polyolefin resins can be appropriately selected and used. As the olefin resin, commercially available products can be used, and for example, Arrowbase CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.), etc. may be selected and used.

[0071] The fixing resin may be supplied in the form of an emulsion. Examples of commercially available resin emulsions include Polysol SH-502 (vinyl acetate resin emulsion), Polysol AD-13, AD-2, AD-10, AD-96, AD-17, and AD-70 (ethylene-vinyl acetate resin emulsion), Polysol PSASE-6010 (ethylene-vinyl acetate resin emulsion) (trade name, manufactured by Showa Denko K.K.), Seikadyne 1900W (trade name, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and ethylene-vinyl acetate resin emulsion (trade name, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.). vinyl resin emulsion), Vinyblanc 700, 2586 (manufactured by Nissin Chemical Industry Co., Ltd.), Eliter KA-5071S, KT-8803, KT-9204, KT-8701, KT-8904, KT-0507 (trade name of Unitika Ltd., polyester resin emulsion), Hi-Tec SN-2002 (trade name of Toho Chemical Co., Ltd., polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (trade name of Mitsui Chemicals Polyurethanes, urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 620, 700 (product names of Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Permarin UA-150 (manufactured by Sanyo Chemical Industries, Ltd., urethane resin emulsion), Sancure 2710 (manufactured by The Lubrizol Corporation Japan, urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (manufactured by Kusumoto Chemicals Co., Ltd., urethane resin emulsion), Adekabontiter HUX-380, 290K (ADEKA Corporation, urethane resin emulsion), Mowinyl 966A, Mowinyl 7320 (Japan Coating Resins), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX The binder may be selected from the group consisting of BASF-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, and 7610 (all manufactured by BASF), NK Binder R-5HN (manufactured by Shin-Nakamura Chemical Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane manufactured by DIC Corporation), and Joncryl 7610 (manufactured by BASF).

[0072] The fixing resins may be used alone or in combination of two or more.

[0073] The content of the fixing resin, as solid content, relative to the total mass of the ink composition is preferably 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 7% by mass, even more preferably 0.5% by mass to 5% by mass, particularly preferably 0.7% by mass to 3% by mass, and even more preferably 0.8 to 2% by mass.

[0074] 1.4 Organic solvents The inkjet ink composition according to this embodiment contains an organic solvent, and the organic solvent contains a 1,2-alkanediol having 4 or less carbon atoms and an alkanediol having 3 to 5 carbon atoms at both ends.

[0075] 1.4.1 1,2-alkanediols with up to 4 carbon atoms

[0076] A 1,2-alkanediol having four or less carbon atoms is a straight-chain or branched alkane having four or less carbon atoms, with hydroxyl groups bonded to the 1st and 2nd positions of the main chain. The main chain refers to the longest sequence of bonded carbon atoms. The alkane is preferably straight-chain.

[0077] Examples of 1,2-alkanediols having 4 or less carbon atoms include 1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,2-butanediol, and 2-methyl-1,2-propanediol. Among these, from the viewpoint of further improving filling, adhesion, and drying properties, the 1,2-alkanediol having 4 or less carbon atoms preferably contains either propylene glycol or 1,2-butanediol, and particularly preferably contains propylene glycol. Furthermore, 1,2-alkanediols having 3 carbon atoms are preferred.

[0078] The normal boiling point of the 1,2-alkanediol having 4 or less carbon atoms is preferably 200°C or less, more preferably less than 200°C, and even more preferably 190°C or less, and further preferably 160 to 190°C. Many 1,2-alkanediols having 4 or less carbon atoms have a relatively low standard boiling point, which is presumably also a factor contributing to their excellent drying properties and adhesion. However, it is not just their relatively low standard boiling point that presumably contributes to the excellent drying properties and adhesion of 1,2-alkanediols having 4 or less carbon atoms.

[0079] The content of the 1,2-alkanediol having 4 or less carbon atoms relative to the total mass of the ink composition is The content is preferably 1 to 25% by mass, more preferably 3 to 20% by mass, further preferably 5 to 15% by mass, and particularly preferably 8 to 13% by mass.

[0080] 1.4.2 Alkanediols with 3 to 5 carbon atoms at both ends

[0081] The alkanediol having 3 to 5 carbon atoms and terminated at both ends is a straight-chain or branched alkane having 3 to 5 carbon atoms, with hydroxyl groups bonded to both ends of the main chain. The main chain refers to the longest sequence of bonded carbon atoms. The alkane is preferably straight-chain.

[0082] Examples of alkanediols having 3 to 5 carbon atoms at both ends include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,3-propanediol, and 2-methyl-1,4-butanediol. Among these, from the viewpoint of achieving both better clogging resistance and adhesion, the alkanediol having 3 to 5 carbon atoms at both ends preferably includes any of 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol. Furthermore, alkanediols having 3 or 4 carbon atoms are preferred, and 3 carbon atoms is more preferred.

[0083] The normal boiling point of the alkanediol having 3 to 5 carbon atoms and terminated at both ends is preferably 120°C or higher, and more preferably 200°C or higher, more preferably 200 to 260°C, more preferably 200 to 230°C, and even more preferably 200 to 220°C. The normal boiling point of the alkanediol having 3 to 5 carbon atoms at both ends is preferably higher than the normal boiling point of the 1,2-alkanediol having 4 or less carbon atoms, more preferably 5 to 60°C higher, even more preferably 10 to 40°C higher, and particularly preferably 20 to 30°C higher.

[0084] The content of the alkanediol having 3 to 5 carbon atoms at both ends relative to the total mass of the ink composition is preferably 1 to 25 mass%, more preferably 3 to 20 mass%, even more preferably 4 to 15 mass%, and particularly preferably 6 to 10 mass%.

[0085] In the inkjet ink composition according to this embodiment, the mass ratio (B / A) of the content A of the 1,2-alkanediol having 4 or less carbon atoms relative to the total mass of the ink composition to the content B of the alkanediol terminated at both ends and having 3 to 5 carbon atoms relative to the total mass of the ink composition is preferably 0.1 to 1.5. The lower limit of this mass ratio (B / A) is preferably 0.1 or greater, more preferably 0.2 or greater, even more preferably 0.3 or greater, particularly preferably 0.35 or greater, and even more particularly preferably 0.45 or greater. The upper limit of this mass ratio (B / A) is preferably 1.3 or less, more preferably 1.2 or less, even more preferably 1.0 or less, and more preferably less than 1.0. Furthermore, it is particularly preferably 0.8 or less, and even more preferably 0.6 or less. When the mass ratio (B / A) is within the above range, a better balance between moisture retention and drying properties can be achieved, and clogging resistance can be more preferably achieved along with adhesion and drying properties. Furthermore, from the viewpoint of further improving filling, adhesion, and drying properties, the mass ratio (B / A) is more preferably a mass ratio (B / A) where A is the amount of propylene glycol contained relative to the total mass of the ink composition, and B is the amount of alkanediol having 3 to 5 carbon atoms at both ends contained relative to the total mass of the ink composition.

[0086] 1.4.3 Other organic solvents The organic solvent may contain, in addition to the above, polyols (excluding 1,2-alkanediols having 4 or less carbon atoms and alkanediols having 3 to 5 carbon atoms at both ends), esters, cyclic esters, alkylene glycol ethers, nitrogen-containing solvents, etc.

[0087] <Polyols> Polyols can be divided into alkanediols and polyhydric alcohols. Polyols are alkane polyols in which alkanes are substituted with two or more hydroxyl groups, or intermolecular condensates in which alkane polyols are condensed together at their hydroxyl groups.

[0088] Examples of the alkanediols include 1,2-alkanediols having 5 or more carbon atoms, alkanediols having 6 or more carbon atoms at both ends, and other diols.

[0089] Examples of 1,2-alkanediols having 5 or more carbon atoms include 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol.

[0090] Examples of alkanediols having 6 or more carbon atoms at both ends include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 3-methyl-1,5-pentanediol.

[0091] Other diols include, for example, hexylene glycol (2-methyl-2,4-pentanediol), 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol; diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, and the like.

[0092] The alkanediols may be linear or branched. There is no particular upper limit on the number of carbon atoms, but it is preferably 10 or less, more preferably 8 or less, and particularly preferably 6 or less.

[0093] Polyhydric alcohols have a molecular structure in which three or more hydroxyl groups are bonded to an alkane. Examples of polyhydric alcohols include trimethylolpropane, glycerin, 1,2,6-hexanetriol, and pentaerythritol.

[0094] The polyhydric alcohols may be linear or branched. There is no particular upper limit on the number of carbon atoms, but it is preferably 10 or less, more preferably 6 or less, and particularly preferably 4 or less. There is no particular upper limit on the number of hydroxyl groups, but it is preferably 5 or less.

[0095] <Esters> Examples of esters include glycol monoacetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; Examples of glycol diesters include ethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, and dipropylene glycol acetate propionate.

[0096] <Cyclic esters> Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atom of the methylene group adjacent to the carbonyl group of these cyclic esters is substituted with an alkyl group having 1 to 4 carbon atoms.

[0097] <Alkylene glycol ethers> The alkylene glycol ethers may be monoethers or diethers of alkylene glycol, and alkyl ethers are preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, and the like. and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0098] The alkylene glycol constituting the alkylene glycol ethers preferably has 2 to 8 carbon atoms, more preferably 2 to 6, even more preferably 2 to 4, and particularly preferably 2 or 3. The alkylene glycol constituting the alkylene glycol ethers may be alkylene glycols in which hydroxyl groups are condensed together intermolecularly. The number of condensed alkylene glycols is preferably 1 to 4, more preferably 1 to 3, and even more preferably 2 or 3.

[0099] The ether constituting the alkylene glycol ether is preferably an alkyl ether, more preferably an ether of an alkyl having 1 to 4 carbon atoms, and more preferably an ether of an alkyl having 2 to 4 carbon atoms.

[0100] Alkylene glycol ethers are preferred because they have excellent permeability and wettability on the recording medium, resulting in excellent image quality. In this respect, monoethers are particularly preferred.

[0101] <Nitrogen-containing solvent> Examples of the nitrogen-containing solvent include acyclic amides, cyclic amides, etc. Examples of the acyclic amides include alkoxyalkyl amides.

[0102] Examples of alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, Examples include N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, and 3-tert-butoxy-N,N-methylethylpropionamide.

[0103] Examples of cyclic amides include lactams, such as pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone.

[0104] The organic solvents may be used alone or in combination of two or more.

[0105] The weighted average normal boiling point of the organic solvent contained in the inkjet ink composition according to this embodiment is preferably 160 to 260° C., more preferably 180 to 230° C., even more preferably 190 to 220° C., and particularly preferably 195 to 205° C. When the weighted average normal boiling point of the organic solvent is within the above range, a better balance between moisture retention and drying properties can be achieved, and adhesion and drying properties tend to be further improved while good clogging resistance is ensured.

[0106] Here, the weighted average value of the normal boiling points of the organic solvents contained in the ink composition refers to a weighted average value of the normal boiling points of each organic solvent, where the weight is the ratio of the mass of each organic solvent to the total mass of all organic solvents contained in the ink composition.

[0107] The weighted average of the normal boiling points of the organic solvents contained in the ink composition is calculated as follows: H All , the normal boiling point of each organic solvent is H N , the mass ratio of the organic solvent is Y N (% by mass). N is a number starting from 1 depending on the type of organic solvent contained in the ink composition. For example, if three types of organic solvents are used, H1, H2, and H3 are generated. H is the weighted average of the normal boiling points of the organic solvents contained in the ink composition. All is the normal boiling point H of each organic solvent N and mass ratio Y N Therefore, the following formula (A) holds: Mass ratio Y N is the ratio of the mass of organic solvent N to the total mass of all organic solvents contained in the ink composition, and is a value of 0 to 1.

[0108] H All =ΣH N ×Y N (A)

[0109] The weighted average of the normal boiling points can be adjusted by the normal boiling points of the organic solvents used and the content mass ratio of the organic solvents.

[0110] The total content of organic solvents relative to the total mass of the ink composition is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less. On the other hand, although there is no particular lower limit, it is preferably 10% by mass or more, more preferably 13% by mass or more, and even more preferably 15% by mass or more. When the total content of organic solvents relative to the total mass of the ink composition is within the above range, a better balance between moisture retention and drying properties can be achieved, and clogging resistance tends to be better compatible with adhesion and drying properties.

[0111] The inkjet ink composition according to this embodiment preferably contains no more than 1% by mass, more preferably no more than 0.5% by mass, even more preferably no more than 0.1% by mass, and particularly preferably no more than 0.05% by mass of polyol organic solvents having a normal boiling point of greater than 280° C. relative to the total mass of the ink composition. The lower limit of the amount of polyol organic solvents having a normal boiling point of greater than 280° C. is 0% by mass. Polyol organic solvents with a normal boiling point of more than 280° C. have excellent moisture retention, but may reduce the drying properties of the ink when applied to a recording medium. However, when the content is within the above range, a better balance between moisture retention and drying properties can be achieved, and clogging resistance, adhesion, and drying properties tend to be better achieved at the same time. As mentioned above, polyols include alkanediols and polyhydric alcohols. Examples of alkanediols having a standard boiling point of more than 280°C include 1,2-dodecanediol and triethylene glycol, and examples of polyhydric alcohols having a standard boiling point of more than 280°C include glycerin. It is also preferable that the content of the organic solvent having a normal boiling point of more than 280°C is within the above range.

[0112] 1.5 water The inkjet ink composition according to this embodiment is a water-based ink, and is a composition in which water is one of the main solvents.

[0113] The water is not particularly limited, but examples thereof include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water from which ionic impurities have been removed as much as possible. Furthermore, using water that has been sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can prevent the growth of mold and bacteria when the aqueous ink composition is stored for a long period of time. This tends to further improve storage stability.

[0114] The water content, relative to the total mass of the ink composition, is preferably 30.0% by mass or more, more preferably 40.0 to 90.0% by mass, even more preferably 40.0% to 85.0% by mass, and even more preferably 50.0% to 80.0% by mass.

[0115] 1.6 Wax The inkjet ink composition according to this embodiment may contain a wax to further improve abrasion resistance. Examples of waxes include, but are not limited to, hydrocarbon waxes and ester waxes, which are condensates of fatty acids with monohydric alcohols or dihydric or higher alcohols. Examples of hydrocarbon waxes include, but are not limited to, paraffin waxes and polyolefin waxes such as polyethylene waxes and polypropylene waxes. These waxes may be used alone or in combination of two or more.

[0116] Commercially available paraffin waxes include, for example, AQUACER 497 and AQUACER 539 (both product names, manufactured by BYK).

[0117] Commercially available polyolefin waxes include, for example, Chemipearl S120, S650, and S75N (product names, manufactured by Mitsui Chemicals, Inc.), AQUACER 501, AQUACER 506, AQUACER 513, AQUACER 515, AQUACER 526, AQUACER 593, and AQUACER 582 (product names, manufactured by BYK).

[0118] The melting point of the wax is preferably 50°C or higher and 200°C or lower, more preferably 60°C or higher and 180°C or lower, and even more preferably 70°C or higher and 180°C or lower.

[0119] The wax is preferably added as wax particles contained in an aqueous emulsion in which the wax is dispersed in water. The wax particles may contain, for example, a surfactant for dispersion.

[0120] The wax content is preferably 0.1% by mass to 5.0% by mass, more preferably 0.3% by mass to 4.0% by mass, and even more preferably 0.5% by mass to 3.0% by mass, relative to the total mass of the ink composition. By keeping the wax content within the above range, it may be possible to further improve the adhesion of the recorded matter.

[0121] 1.7 Other The inkjet ink composition according to this embodiment may contain various additives as other components, such as a pH adjuster (e.g., potassium hydroxide, triethanolamine, isopropanolamine), a solubilizing agent, a viscosity adjuster, an antioxidant, an anti-mold / preservative, an anti-fungal agent, a corrosion inhibitor, and a chelating agent (e.g., sodium ethylenediaminetetraacetate) for capturing metal ions that affect dispersion.

[0122] 1.8 Manufacturing method and properties of inkjet ink composition <Manufacturing method> The inkjet ink composition according to this embodiment can be obtained by mixing the above-described components (materials) in any order and, if necessary, performing filtration or the like to remove impurities. When the ink contains a pigment as a colorant, it is preferable to prepare the pigment in a uniformly dispersed state in a solvent before mixing, as this simplifies handling. When preparing the pigment in a dispersed state beforehand, it is preferable to disperse it using a dispersant such as a dispersing resin.

[0123] A suitable method for mixing the materials is to sequentially add the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer, and then stir and mix them. As a filtration method, for example, centrifugal filtration or filter filtration can be used as needed.

[0124] <Physical properties> The surface tension of the ink composition at 25°C is preferably 20 to 50 mN / m, and more preferably 20 to 40 mN / m. When the surface tension is within this range, ejection stability tends to be improved. The surface tension can be measured at a liquid temperature of 25°C by the Wilhelmy method using a surface tensiometer (such as the CBVP-Z surface tensiometer manufactured by Kyowa Interface Science Co., Ltd.).

[0125] The viscosity of the ink composition at 25°C is preferably 20 mPa·s or less, and more preferably 10 mPa·s or less. When the viscosity is within this range, ejection stability tends to be good. The viscosity can be measured using a viscometer.

[0126] 1.9 Usage In recording using the inkjet ink composition according to this embodiment, an image is formed. The recording medium is not particularly limited, and examples thereof include absorbent recording media such as paper, film, and cloth, low absorbent recording media such as printing paper, and non-absorbent recording media such as metal, glass, and polymers. However, the excellent effects of the inkjet ink composition according to this embodiment are even more pronounced when used for recording on low-absorbency or non-absorbency recording media. That is, low-absorbency and non-absorbency recording media tend to have poorer adhesion and drying properties because the ink is more difficult to dry on these media compared to absorbency recording media. However, the inkjet ink composition according to this embodiment can satisfactorily achieve both clogging resistance and good adhesion and drying properties even on such recording media. Therefore, the inkjet ink composition according to this embodiment is preferably used for recording on low-absorbency or non-absorbency recording media.

[0127] A low-absorbency recording medium or a non-absorbency recording medium refers to a recording medium that does not absorb liquid such as an ink composition at all or absorbs very little of it. Quantitatively, a low-absorbency recording medium or a non-absorbency recording medium is a recording medium that absorbs liquid such as an ink composition at all or absorbs very little of it within 30 msec from the start of contact in the Bristow method. 1 / 2 Water absorption up to 10mL / m 2 This refers to the recording medium described below. The Bristow method is the most widely used method for measuring the amount of liquid absorption in a short period of time, and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). Details of the test method are described in Standard No. 51 "Paper and Paperboard - Liquid Absorbency Test Method - Bristow Method" of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition." In contrast, absorbent recording media refers to recording media that do not fall under the category of non-absorbent or low-absorbent.

[0128] Non-absorbent recording media include those with a recording surface made of plastic. Here, the recording surface does not have an absorbing layer or a receiving layer for absorbing ink. Examples include those in which a plastic is coated on a substrate such as paper, those in which a plastic film is adhered to a substrate such as paper, and plastic films that do not have an absorbing layer or a receiving layer. Examples of plastics include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc.

[0129] Further, examples of low-absorbency recording media include recording media called coated paper, which has a coating layer on its surface. For example, recording media having a paper substrate include printing paper such as art paper, coated paper, and matte paper, and recording media having a plastic film substrate include those having a hydrophilic polymer or the like coated on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, or the like, or those having particles of silica, titanium, or the like coated together with a binder.

[0130] The inkjet ink composition according to this embodiment can also be suitably used for recording on flexible packaging films. Flexible packaging films are one embodiment of the non-absorbent recording media described above. More specifically, flexible packaging films are highly flexible film materials used for packaging food, toiletries, cosmetics, and the like. They contain anti-fogging and antistatic materials, antioxidants, and the like on their surface, and have a thickness of 5 to 70 μm, preferably 10 to 50 μm. When applying an ink composition to such films, the ink composition is more difficult to adhere to than to plastic films of normal thickness. Even if it does adhere, the ink composition is less likely to adhere to or adapt to the flexibility of the film, resulting in peeling. However, the inkjet ink composition according to this embodiment also tends to have excellent adhesion to flexible packaging films.

[0131] The material constituting the recording surface of the flexible packaging film includes at least one resin selected from olefin-based resins such as polyethylene and polypropylene, ester-based resins such as polyester, vinyl chloride-based resins such as polyvinyl chloride, and amide-based resins such as polyamide. These resins can be used. The film substrate, including the recording surface of the flexible packaging film, can be a film or sheet made from these resins. In the case of a film or sheet made from a resin, either an unstretched film or a uniaxially or biaxially stretched film can be used, with biaxially stretched films being preferred. Furthermore, if necessary, films or sheets made from these various resins can be used in a laminated state.

[0132] The inkjet ink composition according to this embodiment can also be suitably used for recording on recording media for sign graphics. Sign graphics recording media range widely in material, including banners, coated paper, matte paper, wallpaper, fabric, and plastic films such as PET and PVC. However, the inkjet ink composition according to this embodiment can be particularly suitable for use on transparent or translucent plastic films used for window displays, car wrapping, and the like. These films often have a flexible substrate made of polyolefin, PET, PVC, or the like, and an adhesive layer on the side opposite the printed surface. After printing, the adhesive surface is attached to the window glass, car body, or the like. When applying ink to such films, the ink tends to adhere more slowly, and even if it does adhere, the ink is less likely to adhere to the film's flexibility, resulting in peeling. However, the inkjet ink composition according to this embodiment also tends to have excellent adhesion to sign graphics films.

[0133] The material constituting the recording surface of the sign graphics film can contain at least one resin selected from olefin resins such as polyethylene and polypropylene, ester resins such as polyester, vinyl chloride resins such as polyvinyl chloride, and amide resins such as polyamide.

[0134] The recording medium may be colorless and transparent, semi-transparent, colored and transparent, colored and opaque, colorless and opaque, or the like.

[0135] 2. Recording method A recording method according to an embodiment of the present invention includes: The method includes a step of ejecting the ink-jet ink composition described above by an ink-jet method and depositing it onto a recording medium.

[0136] According to the above-mentioned configuration, it is possible to provide a recording method in which the ink is excellent in filling the recording medium, and is excellent in clogging resistance and adhesion.

[0137] A recording method using an ink containing a silicone surfactant with an HLB value below a predetermined value and an acrylic resin with a glass transition temperature within a predetermined range has excellent filling properties on the recording medium, but when the ink dries, the fixing resin tends to melt inside the recording head, causing clogging. However, increasing the content of organic solvents that act as humectants or adding organic solvents with high moisturizing properties to prevent clogging due to drying results in poor ink drying and reduced adhesion. As such, it has traditionally been difficult to achieve both clogging resistance and adhesion. As a result of extensive research, the present inventors have found that clogging resistance and adhesion can be both achieved by using an ink in a recording method that combines a 1,2-alkanediol having 4 or less carbon atoms with an alkanediol having 3 to 5 carbon atoms at both ends. That is, by combining two types of alkanediols, a 1,2-alkanediol having 4 or less carbon atoms that has excellent drying properties but does not have sufficient moisture retention to prevent a silicone surfactant with a relatively low HLB value from dissolving or swelling an acrylic fixing resin, and an alkanediol having 3 to 5 carbon atoms at both ends that has excellent moisture retention and can ensure sufficient drying properties, clogging resistance and adhesion can be both achieved.

[0138] An inkjet recording apparatus that can be used in the recording method according to this embodiment will be described below, followed by a description of each step of the recording method according to this embodiment.

[0139] 2.1 Inkjet recording device An example of an inkjet recording apparatus that can be suitably used to carry out each step in the recording method according to this embodiment will be described with reference to the drawings.

[0140] 2.1.1 Overview of the device FIG. 1 is a schematic cross-sectional view showing an inkjet recording apparatus. FIG. 2 is a perspective view showing an example of the configuration of the periphery of the carriage of the inkjet recording apparatus 1 of FIG. 1. As shown in FIGS. 1 and 2, the inkjet recording apparatus 1 includes a recording head 2, an IR heater 3, a platen heater 4, a heating heater 5, a cooling fan 6, a preheater 7, a ventilation fan 8, a carriage 9, a platen 11, a carriage movement mechanism 13, a transport means 14, and a control unit CONT. The operation of the entire inkjet recording apparatus 1 is controlled by the control unit CONT shown in FIG. 2.

[0141] 2.1.2 Recording head configuration The recording head 2 is configured to perform recording on the recording medium M by ejecting an inkjet ink composition from the nozzles of the recording head 2 by an inkjet method and depositing the ink on the recording medium M. The recording head 2 shown in Figures 1 and 2 is a serial type recording head that scans multiple times in the main scanning direction relative to the recording medium M to deposit the ink on the recording medium M. The recording head 2 is mounted on a carriage 9 shown in Figure 2. The recording head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of a carriage movement mechanism 13 that moves the carriage 9 in the medium width direction of the recording medium M. The medium width direction is the main scanning direction of the recording head 2. Scanning in the main scanning direction is also called main scanning.

[0142] Here, the main scanning direction is the direction in which the carriage 9 carrying the recording head 2 moves. In FIG. 1, this is the direction intersecting the sub-scanning direction, which is the transport direction of the recording medium M indicated by the arrow SS. In FIG. 2, the width direction of the recording medium M, i.e., the direction indicated by S1-S2, is the main scanning direction MS, and the direction indicated by T1→T2 is the sub-scanning direction SS. Note that scanning is performed in either the main scanning direction, i.e., the direction indicated by the arrow S1 or the arrow S2, in one scan. Then, recording is performed on the recording medium M by repeating the main scanning of the recording head 2 and the sub-scanning, which is the transport direction of the recording medium M, multiple times.

[0143] The cartridges 12 that supply ink to the recording head 2 include a plurality of independent cartridges. The cartridges 12 are detachably mounted on a carriage 9 that carries the recording head 2. Each of the plurality of cartridges can be filled with a different type of inkjet ink composition, and the inkjet ink composition is supplied from the cartridges 12 to each nozzle. Note that while FIGS. 1 and 2 show an example in which the cartridge 12 is mounted on the carriage 9, this is not limiting, and the cartridge 12 may be provided in a location other than the carriage 9 and the ink may be supplied to each nozzle by a supply pipe (not shown).

[0144] A conventionally known method can be used for ejecting ink from the recording head 2. In this example, a method of ejecting ink droplets using the vibration of a piezoelectric element, that is, an ejection method of forming ink droplets by the mechanical deformation of an electrostrictive element, is used.

[0145] 2.1.3 Primary heating mechanism The inkjet recording apparatus 1 may include a primary heating mechanism that heats the recording medium M when ink is ejected from the recording head 2 and adhered to the recording medium. The primary heating mechanism may be a heat transfer mechanism, a blower mechanism, a radiation mechanism, or the like. The conduction mechanism transfers heat to the recording medium from a member that comes into contact with the recording medium. An example of this is a platen heater. The blower mechanism sends room temperature or hot air to the recording medium to dry the ink, etc. An example of this is a blower fan. The radiation mechanism heats the recording medium by radiating heat-generating radiation to the recording medium. An example of this is IR radiation. Although not shown, a heater similar to the platen heater may be provided immediately downstream of the platen heater 4 in the SS direction. These primary heating mechanisms may be used alone or in combination. For example, the primary heating mechanism may include an IR heater 3 and a platen heater 4.

[0146] Note that, when the IR heater 3 is used, the recording medium M can be radiatively heated by radiating infrared rays from the recording head 2 side. This makes it easy for the recording head 2 to be heated at the same time, but compared to heating from the back side of the recording medium M using a platen heater 4 or the like, the temperature can be increased without being affected by the thickness of the recording medium M. Note that various fans (for example, ventilation fan 8) may be provided to blow warm air or air at the same temperature as the environment onto the recording medium M to dry the ink on the recording medium M.

[0147] The platen heater 4 is capable of heating the recording medium M via a platen 11 at a position facing the recording head 2. The platen heater 4 is capable of conductively heating the recording medium M, and is used as needed in the recording method.

[0148] The inkjet recording apparatus 1 may be provided with a preheater 7 that preheats the recording medium M before the ink is applied to the recording medium M.

[0149] 2.1.4 Post-heating mechanism A post-heating mechanism may be provided downstream of the primary heating mechanism to dry the recorded material sufficiently to enable it to be used and complete the recording.

[0150] The heater 5 used in the post-heating mechanism dries and solidifies the ink attached to the recording medium M. By heating the recording medium M on which an image has been recorded, the water contained in the ink evaporates and dissipates more quickly, and an ink film is formed by the resin contained in the ink. In this way, the ink film is firmly fixed or adhered to the recording medium M, providing excellent film-forming properties, and an excellent, high-quality image can be obtained in a short time.

[0151] 2.1.5 Other Configurations The inkjet recording apparatus 1 may have a cooling fan 6. After the ink recorded on the recording medium M has dried, the ink on the recording medium M is cooled by the cooling fan 6, thereby forming an ink coating film on the recording medium M with good adhesion.

[0152] Below the carriage 9, there are provided a platen 11 that supports the recording medium M, a carriage movement mechanism 13 that moves the carriage 9 relative to the recording medium M, and a conveying means 14 that is a roller that conveys the recording medium M in the sub-scanning direction. The operations of the carriage movement mechanism 13 and the conveying means 14 are controlled by a control unit CONT.

[0153] 2.1.6 Electrical Control FIG. 3 is a functional block diagram of the inkjet recording apparatus 1. The control unit CONT is a control unit for controlling the inkjet recording apparatus 1. The interface unit 101 (I / F) is for transmitting and receiving data between the computer 130 (COMP) and the inkjet recording apparatus 1. The CPU 102 is an arithmetic processing unit for controlling the entire inkjet recording apparatus 1. The memory 103 (MEM) is for securing an area for storing programs for the CPU 102, a working area, etc. The CPU 102 Each unit is controlled by a unit control circuit 104 (UCTRL). A detector group 121 (DS) monitors the status inside the inkjet recording apparatus 1, and the control unit CONT controls each unit based on the detection results.

[0154] The transport unit 111 (CONVU) controls the sub-scanning (transport) of inkjet recording, specifically, controls the transport direction and transport speed of the recording medium M. More specifically, the transport direction and transport speed of the recording medium M are controlled by controlling the rotation direction and rotation speed of a transport roller driven by a motor.

[0155] The carriage unit 112 (CARU) controls the main scan (pass) of inkjet printing, and more specifically, moves the print head 2 back and forth in the main scan direction. The carriage unit 112 includes a carriage 9 on which the print head 2 is mounted, and a carriage movement mechanism 13 for moving the carriage 9 back and forth.

[0156] The head unit 113 (HU) controls the amount of ink ejected from the nozzles of the print head 2. For example, if the nozzles of the print head 2 are driven by piezoelectric elements, the head unit 113 controls the operation of the piezoelectric elements in each nozzle. The head unit 113 controls the timing of ink deposition, ink dot size, etc. Furthermore, the amount of ink deposition per scan is controlled by a combination of the control of the carriage unit 112 and the head unit 113.

[0157] The drying unit 114 (DU) controls the temperatures of various heaters such as the IR heater 3, the preheater 7, the platen heater 4, and the heating heater 5.

[0158] The inkjet recording device 1 alternately repeats an operation of moving the carriage 9 carrying the recording head 2 in the main scanning direction and a transport operation (sub-scanning). During each pass, the control unit CONT controls the carriage unit 112 to move the recording head 2 in the main scanning direction, and controls the head unit 113 to eject ink droplets from predetermined nozzle holes in the recording head 2 and cause the ink droplets to adhere to the recording medium M. The control unit CONT also controls the transport unit 111 to transport the recording medium M in the transport direction by a predetermined transport amount (feed amount) during the transport operation.

[0159] In the inkjet recording device 1, the recording area onto which multiple droplets have been deposited is gradually transported by repeating main scanning (passes) and sub-scanning (transportation operations). Then, the droplets deposited on the recording medium M are dried by a heater 5, completing the image. Thereafter, the completed recording may be wound into a roll by a winding mechanism, or transported by a flatbed mechanism.

[0160] Each step of the recording method according to this embodiment will be described below.

[0161] 2.2 Ink deposition process The recording method according to this embodiment includes a step of ejecting the inkjet ink composition onto a recording medium by an inkjet method (ink deposition step). The "inkjet method" is a method of ejecting droplets using an inkjet head.

[0162] The amount of ink adhered is preferably 3 mg / inch as the amount of ink composition adhered per unit area of ​​the recording region of the recording medium. 2 More preferably, it is 5 mg / inch or more. 2 More preferably, it is 7 mg / inch or more. 2 The upper limit of the amount of ink adhered is preferably 15 mg / inch. 2 It is preferably 12 mg / inch or less. 2 It is more preferably 9 mg / inch or less. 2 The recording method according to this embodiment is as follows: According to the method, even when the amount of ink attached is within the above range, there is a tendency for excellent filling, clogging resistance, and adhesion to be excellent. It is also preferable that the maximum amount of ink composition deposited per unit area of ​​the recording region of the recording medium during recording be within the above range.

[0163] The recording medium is preferably a low-absorbency recording medium or a non-absorbency recording medium, similar to the recording media that can be used with the inkjet ink composition described above. Low-absorbency recording media and non-absorbency recording media tend to have poor adhesion and drying properties because the ink is more difficult to dry on these recording media than on absorbency recording media. However, the recording method according to this embodiment makes it possible to achieve good clogging resistance, adhesion, and drying properties even with such recording media.

[0164] Furthermore, in the recording method according to this embodiment, recording is performed by multiple main scans, and the number of main scans performed on the same scanning area is preferably 10 or less, more preferably 9 or less, even more preferably 7 or less, particularly preferably 5 or less, and even more particularly preferably 4 or less. The number of main scans is 1 or more, and although there is no particular lower limit, it is preferably 3 or more. When the resolution, which is the number of dots (ink droplets) per unit area, is fixed, a small number of main scans increases the number of dots ejected simultaneously, causing the ink droplets to cluster together and resulting in poor coverage. While a printing method using ink containing a silicone surfactant with an HLB value below a certain value can improve coverage on the printing medium, clogging is likely to occur, and achieving both good adhesion and good adhesion has been an issue in resolving clogging. Furthermore, a small number of main scans shortens the drying time in the primary heating process (described below), which can lead to insufficient drying and poor adhesion. Furthermore, a small number of main scans can increase the printing speed and shorten the time the same portion of the printing medium remains in the post-heating mechanism. However, according to the recording method of this embodiment, even if the number of main scans is small, it is possible to ensure good filling and tend to achieve both good clogging resistance and good adhesion. The number of main scans performed on the same scanning area refers to the total number of main scans performed when a main scan is performed again so that it at least partially overlaps the scan area on the recording medium of the print head that has performed one main scan. For example, if the distance of one sub-scan is shorter than the length of the nozzle row that ejects ink in the sub-scanning direction, the scan area of ​​one main scan will be scanned again. For example, if the distance of one sub-scan is one-eighth the length of the nozzle row that ejects ink in the sub-scanning direction, eight main scans will be performed on the same scanning area. In this case, the number of main scans is said to be eight.

[0165] 2.3 Primary heating process The recording method according to this embodiment includes a primary heating step of heating the inkjet ink composition adhered to the recording medium, and the surface temperature of the recording medium in the primary heating step is preferably 40° C. or higher. The surface temperature of the recording medium in the primary heating step is preferably 50° C. or lower, more preferably 47° C. or lower, even more preferably 45° C. or lower, and particularly preferably 43° C. or lower. The surface temperature of the recording medium in the primary heating step is preferably 28° C. or higher, more preferably 33° C. or higher, and even more preferably 38° C. or higher. 45° C. or higher is even more preferred.

[0166] The recording method having the above-mentioned configuration has excellent drying properties, and therefore can further improve the adhesion of the recorded matter. On the other hand, the ink tends to wet poorly on the recording medium, and the ink tends to be less dense. Therefore, if an ink containing a silicone surfactant with an HLB value of less than a predetermined value is used to improve the ink's density, clogging is likely to occur. However, according to the recording method of this embodiment, even when the above-described configuration is provided, it is possible to ensure good filling and tend to achieve both good clogging resistance and good adhesion.

[0167] The primary heating step is a step of heating and drying the ink adhered to the recording medium at an early stage. The primary heating step is a heating step for drying at least a portion of the ink solvent component to an extent that at least the ink flow is reduced. The primary heating step may be performed by adhering the ink to a heated recording medium, or by heating the ink early after adhering. In the primary heating step, it is preferable that heating of the ink droplets that have landed on the recording medium is initiated within 0.5 seconds at the latest after the ink droplets land on the recording medium.

[0168] The primary heating step is preferably performed by using an IR heater, microwave radiation, a platen heater, or blowing hot air onto the recording medium using a fan.

[0169] The heating in the primary heating step may be carried out at least one of before the ink application step, simultaneously with the application, and shortly after the application, and is preferably carried out simultaneously. The ink application step can be carried out in such a heating order. The heating temperature in the primary heating step is the surface temperature of the recording medium when ink is applied to the heated recording medium, or the surface temperature of the recording medium when heating is performed soon after ink application. It is also the maximum temperature during heating in the primary heating step.

[0170] 2.4 Post-heating process The recording method according to this embodiment preferably includes a post-heating step of heating the recording medium to which the inkjet ink composition has been applied, which is preferable because it tends to improve drying properties and result in a recorded product with better adhesion.

[0171] The post-heating step is a heating step in which the recording is completed and the recording material is heated sufficiently to be usable. The post-heating step is a heating step in which the solvent component of the ink is sufficiently dried and the resin contained in the ink is heated to form a flat ink coating. The post-heating step is preferably started more than 0.5 seconds after the ink is applied to the recording medium. For example, it is preferable to start heating a certain recording area of ​​the recording medium more than 0.5 seconds after the ink has been completely applied to that area. Furthermore, it is preferable that the temperature preferred in the primary heating step is different from the temperature preferred in the post-heating step.

[0172] The heating of the recording medium in the post-heating step can be performed using an appropriate heating means, for example, when an inkjet recording apparatus is used, or by any appropriate heating means, not limited to the heating means provided in the inkjet recording apparatus. In this case, the surface temperature of the recording medium is preferably 60° C. or higher, more preferably 70° C. or higher, even more preferably 80° C. or higher, and particularly preferably 85° C. or higher. The surface temperature of the recording medium heated in the post-heating step is preferably 120° C. or lower, more preferably 110° C. or lower, even more preferably 100° C. or lower, and particularly preferably 95° C. or lower. According to the recording method of this embodiment, even at a surface temperature of the recording medium within the above range, the ink tends to be dried sufficiently and a recorded product with excellent adhesion can be obtained.

[0173] 3. Working Example 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 is based on mass.

[0174] 3.1 Preparation of Inkjet Ink Composition Each inkjet ink composition was obtained by mixing the components in the amounts shown in Tables 1 and 2 below, stirring at room temperature for 2 hours, and then filtering through a membrane filter with a pore size of 5 μm. Note that the units of the contents of the components shown in Tables 1 and 2 below are % by mass, and water was added so that the total amount of the composition was 100% by mass. Note that in Tables 1 and 2 below, the pigment content is the pigment solid content amount, and the acrylic resin content is the resin solid content amount.

[0175] 3.1.1 Preparation of pigment dispersion The black pigment (CI Pigment Black 7) used in the preparation of the inkjet ink composition was prepared by mixing it in advance with a pigment dispersant (not shown in the table), which is a water-soluble styrene acrylic resin, in a mass ratio of 1:1 (pigment:pigment dispersant) in water and thoroughly stirring to form a pigment dispersion.

[0176] 3.1.2 Resin synthesis method <Example of synthetic resin 1 preparation> A reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer was charged with 100 parts by mass of ion-exchanged water, 0.4 parts by mass of potassium persulfate as a polymerization initiator, and 0.25 parts by mass of sodium lauryl sulfate, and heated to 70°C. A mixture of 144 parts by mass of the following monomers in the following mass ratio, 67 parts by mass of ion-exchanged water, and 0.52 parts by mass of t-dodecyl mercaptan was added dropwise to the mixture under stirring in a nitrogen atmosphere to carry out a polymerization reaction.

[0177] (monomer) 40 parts styrene Methyl methacrylate 2 parts Acrylic acid 15 parts Methyl acrylate 15 parts 2-Hydroxyethyl acrylate 2 parts Ethyl acrylate 8 parts 2-Ethylhexyl acrylate 18 parts

[0178] After the polymerization reaction, the mixture was neutralized with sodium hydroxide to adjust the pH to 8 to 8.5, and filtered through a 0.3 μm filter to obtain a resin. The obtained resin was in a dispersed form.

[0179] The obtained resin was subjected to differential scanning calorimetry (DSC) in accordance with JIS K7121 to determine the glass transition temperature Tg (°C) of the polymer. A differential scanning calorimeter, model "DSC6220" manufactured by Seiko Electronics Co., Ltd., was used. If the measured glass transition temperature of the obtained polymer differed from the values ​​in Tables 1 and 2 below, the mass ratio of each monomer was finely adjusted and polymerization was carried out again to obtain the glass transition temperature shown in Tables 1 and 2 below.

[0180] <Preparation example of synthetic resin 2 and synthetic resin 3> Synthetic Resins 2 and 3 were obtained by polymerization in the same manner as for Synthetic Resin 1, except that the mass ratio of each monomer in the monomer composition of Synthetic Resin 1 was adjusted so that the glass transition temperature would be the value shown in Tables 1 and 2 below. The glass transition temperature was adjusted by checking the Tg of the homopolymer of each monomer, and increasing the mass ratio of the monomer with a high Tg to increase the Tg, or by increasing the mass ratio of the monomer with a low Tg to decrease the Tg.

[0181] [Table 1]

[0182] [Table 2]

[0183] The following provides additional explanations for the descriptions in Tables 1 and 2 above.

[0184] <Composition> The following provides additional explanations for the pigments, acrylic resins, surfactants, and waxes shown in Tables 1 and 2 above. (pigment) Black pigment: CI Pigment Black 7 (acrylic resin) JONCRYL 62J: BASF brand name, styrene acrylic resin (surfactant) SAG503A: "Silface SAG503A", a product name manufactured by Nissin Chemical Industry Co., Ltd., a silicone surfactant KF-353: A silicone surfactant manufactured by Shin-Etsu Chemical Co., Ltd. SAG005: "Silface SAG005", a product name of Nissin Chemical Industry Co., Ltd., a silicone surfactant Tego Wet 280: Trade name of Evonik Degussa, silicone-based surfactant Surfynol 440: Trade name of Nissin Chemical Industry Co., Ltd., acetylene-based surfactant (wax) AQ513: BYK Japan product name, polyethylene wax

[0185] <Terminology> The meanings of the terms in Tables 1 and 2 above are as follows: "Tg": Glass transition temperature (℃) "bp": Standard boiling point (℃) "HLB": "HLB value (hydrophilic lipophilic balance)" calculated by the Griffin method "Total amount of organic solvents": Total amount of organic solvents "Average boiling point of organic solvents": Weighted average value (°C) of each solvent among all organic solvents contained in the inkjet ink composition

[0186] 3.2 Recording method An inkjet printer "SC-S80650" (product name, manufactured by Seiko Epson Corporation) was prepared by modifying it, and printing was performed using each of the inkjet ink compositions obtained above under the following printing conditions. During inkjet recording, a platen heater was operated as the primary heating mechanism, and the surface temperature of the recording medium on the recording side at a position facing the recording head (the highest temperature during recording within the relevant range) is shown as the primary drying temperature (primary heating temperature) in Table 3 below. Furthermore, the inkjet printers used in the examples and comparative examples were provided with a secondary heater as a post-heating mechanism downstream of the primary heating mechanism. An IR heater was used as the secondary heater, and secondary heating was performed with the maximum temperature of the recording surface side of the recording medium (the highest temperature during the post-heating process) set to 70°C.

[0187] (Printing conditions) Ink used: See Table 3 below Number of printing passes: See Table 3 below Nozzle density of the print head nozzle row: 360 dpi Primary drying temperature: See Table 3 below Secondary drying temperature: 70℃ Ink deposition amount: 7mg / inch 2 Recording resolution: 720 x 720 dpi (for any number of print passes, The number of ink droplets per print was thinned out to determine the recording resolution. Recording medium: Product name "PET50A", manufactured by Lintec Corporation, PET film

[0188] [Table 3]

[0189] 3.3 Evaluation method As shown in Table 3 above, the filling, clogging resistance, adhesion and drying properties were evaluated using the following evaluation methods.

[0190] 3.3.1 Filling evaluation The degree of color loss in the resulting print was visually observed and evaluated according to the following criteria: Color loss is when there are areas on the recording medium where no ink is attached and the background of the recording medium is visible. (Evaluation criteria) S: The ink has spread sufficiently and no color loss can be confirmed visually or with a magnifying glass. A: The ink spreads well and no color bleeding can be seen with the naked eye. B: Ink does not spread well, and slight color loss can be visually confirmed. C: Ink does not spread well, and color loss is visible and noticeable.

[0191] 3.3.2 Evaluation of clogging resistance The printer was operated under the printing conditions for the recording method described above, and with the recording head capped, it was positioned next to the platen where it would be exposed to the heat of the platen and left for one month. Suction cleaning was then performed to restore non-ejecting nozzles, and a nozzle inspection was conducted, evaluating clogging resistance according to the following evaluation criteria. Note that each suction cleaning cycle involved discharging 1 cc of ink from the nozzle row. (Evaluation criteria) S: All nozzles recovered within 3 cleanings A: All nozzles recovered within 6 cleanings B: Cleaning 6 times + leaving for 12 hours + cleaning 3 times to recover all nozzles C: Cleaning 6 times + leaving for 12 hours + cleaning 6 times to recover all nozzles D: Some nozzles do not recover

[0192] 3.3.3 Evaluation of adhesion The resulting prints were subjected to a rub fastness test (JIS P 8136:1994) using a Gakushin-type rub fastness tester "AB-301" (product name, manufactured by Tester Sangyo Co., Ltd.) in which a No. 3 gold-stripe cloth was rubbed back and forth 50 times with a load of 500 g. Adhesion was evaluated according to the following criteria. (Evaluation criteria) S: No peeling of the image is observed A: Less than 10% peeling B: 10% to less than 30% peeling C: 30% to less than 50% peeling D: More than 50% peeling

[0193] 3.3.4 Evaluation of drying properties Of the steps in the above-mentioned recording method, no secondary heating was performed, and the prints were dried for various times in an air oven at 70°C. The coating surface of the resulting prints was rubbed with a cloth, and the ink was visually observed to see if it adhered to the cloth, and the drying properties were evaluated according to the following evaluation criteria. (Evaluation criteria) S: No ink adheres to the fabric after drying for 1 minute A: After drying for 2 minutes, no ink is visible on the fabric. B: After drying for 3 minutes, no ink is seen on the fabric. C: After drying for 3 minutes, ink adhesion to the fabric is visible.

[0194] 3.4 Evaluation results The evaluation results are shown in Table 3 above.

[0195] A comparison of each example and each comparative example shows that the inkjet ink composition and recording method according to the present embodiment, which are examples, all provide excellent filling properties on the recording medium, as well as excellent clogging resistance and adhesion. On the other hand, all of the comparative examples were inferior in either filling on the recording medium, clogging resistance, or adhesion.

[0196] A comparison between Example 1 and Comparative Example 1 shows that excellent filling properties are achieved by setting the HLB value of the silicone surfactant to a specific value or less. Also, a comparison between Example 1 and Comparative Example 4 shows that excellent filling properties are achieved when the surfactant is a silicone surfactant. The results of Examples 1, 5, and 6 show that the HLB value of the silicone surfactant is in a predetermined wide range to provide excellent filling.

[0197] Comparison of Example 1 with Comparative Examples 5 and 6 reveals that when the glass transition point of the acrylic resin is within a specific range, clogging resistance and adhesion are excellent. The results of Examples 1 and 13 show that the acrylic resin has excellent clogging resistance and adhesion within a wide range of glass transition temperatures.

[0198] Comparison of Example 1 with Comparative Examples 2, 3, and 7 to 9 reveals that excellent clogging resistance is achieved when the organic solvent contains a specific alkanediol at both ends. The results of Examples 1, 3, 4 and 7 show that excellent clogging resistance is achieved when the carbon number of the alkanediol at both ends is in the range of 3 to 5.

[0199] Comparing Example 1 with Comparative Examples 10 and 11, it is clear that when the organic solvent contains a specific 1,2-alkanediol, the adhesiveness is excellent, and the drying property and filling property are also excellent. The results of Examples 1 and 12 show that when the carbon number of the 1,2-alkanediol is in the range of 4 or less, excellent filling is achieved.

[0200] The results of Examples 1, 2, 9, 10, and 15 show that when the mass ratio (B / A) of the content A of a specific 1,2-alkanediol relative to the total mass of the ink composition and the content B of a specific alkanediol at both ends relative to the total mass of the ink composition is within a specified range, clogging resistance, adhesion, and drying properties can be more favorably achieved.

[0201] The results of Examples 1 and 8 show that when the weighted average value of the normal boiling points of the organic solvents is within a predetermined range, the adhesiveness and drying properties are superior.

[0202] The results of Examples 1, 11, and 14 show that clogging resistance, adhesion, and drying properties can be more favorably achieved at the same time when the total content of organic solvents in the ink composition is within a predetermined range.

[0203] The results of Examples 1, 16, and 17 show that even when the number of printing passes is small, good filling can be ensured while good clogging resistance and good adhesion can both be achieved.

[0204] The results of Examples 1, 18, and 19 show that even when the primary drying temperature is low, the adhesiveness is excellent.

[0205] Comparison of Example 1 and Comparative Examples 9 and 12 reveals that when the ink contains an acrylic resin with a glass transition point of 35 to 95° C., adhesion is excellent, but clogging resistance becomes an issue.

[0206] The following can be derived from the above-described embodiment.

[0207] One embodiment of the inkjet ink composition comprises: The toner includes a colorant, a surfactant, a fixing resin, and an organic solvent, the surfactant comprises a silicone surfactant with an HLB value of 10.5 or less, the fixing resin contains an acrylic resin having a glass transition point of 35 to 95°C, the organic solvent contains a 1,2-alkanediol having 4 or less carbon atoms and an alkanediol having 3 to 5 carbon atoms at both ends, It is a water-based ink.

[0208] In one embodiment of the inkjet ink composition, The mass ratio (B / A) of the content A of the 1,2-alkanediol having 4 or less carbon atoms relative to the total mass of the ink composition to the content B of the alkanediol having 3 to 5 carbon atoms at both ends relative to the total mass of the ink composition may be 0.1 to 1.5.

[0209] In any of the above inkjet ink compositions, The total content of the organic solvents relative to the total mass of the ink composition may be 30 mass % or less.

[0210] In any of the above inkjet ink compositions, The 1,2-alkanediol having 4 or less carbon atoms may include either propylene glycol or 1,2-butanediol.

[0211] In any of the above inkjet ink compositions, The weighted average normal boiling point of the organic solvent contained in the ink composition may be 195 to 205°C.

[0212] In any of the above inkjet ink compositions, The silicone surfactant may have an HLB value of 2 to 10.5.

[0213] In any of the above inkjet ink compositions, The alkanediol having 3 to 5 carbon atoms at both ends may include any one of 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol.

[0214] In any of the above inkjet ink compositions, The ink composition may contain no more than 1% by mass of polyol organic solvents having a normal boiling point of more than 280°C relative to the total mass of the ink composition.

[0215] In any of the above inkjet ink compositions, The acrylic resin may have a glass transition point of 40 to 90°C.

[0216] In any of the above inkjet ink compositions, It may be used for recording on low-absorbency recording media or non-absorbency recording media.

[0217] In any of the above inkjet ink compositions, The acrylic resin may include a styrene-acrylic resin.

[0218] One aspect of the recording method is The ink-jet ink composition according to any one of the above embodiments is ejected by an ink-jet method. and adhering the adhesive to the recording medium.

[0219] In one aspect of the recording method, The recording medium may be a low-absorbency recording medium or a non-absorbency recording medium.

[0220] In any one of the above recording methods, Recording may be performed by a plurality of main scans, and the number of main scans performed on the same scanning area may be 10 or less.

[0221] In any one of the above recording methods, A primary heating step may be carried out to heat the inkjet ink composition attached to the recording medium, and the surface temperature of the recording medium in the primary heating step may be 40° C. or higher.

[0222] In any one of the above recording methods, The method may further include a post-heating step of heating the recording medium to which the inkjet ink composition has been attached.

[0223] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments, such as configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0224] 1...inkjet recording device, 2...recording head, 3...IR heater, 4...platen heater, 5...heating heater, 6...cooling fan, 7...preheater, 8...ventilation fan, 9...carriage, 11...platen, 12...cartridge, 13...carriage movement mechanism, 14...conveying means, 101...interface section, 102...CPU, 103...memory, 104...unit control circuit, 111...conveying unit, 112...carriage unit, 113...head unit, 114...drying unit, 121...detector group, 130...computer, CONT...control section, MS...main scanning direction, SS...sub-scanning direction, M...recording medium

Claims

1. The toner includes a colorant, a surfactant, a fixing resin, and an organic solvent, the surfactant comprises a silicone surfactant having an HLB value of 10.5 or less, the fixing resin contains an acrylic resin having a glass transition point of 35 to 95°C, the organic solvent contains a 1,2-alkanediol having 4 or less carbon atoms and an alkanediol having 3 to 5 carbon atoms at both ends, The weighted average normal boiling point of the organic solvent is 195 to 205°C, The ink-jet ink composition is a water-based ink.

2. 2. The inkjet ink composition according to claim 1, wherein a mass ratio (B / A) of a content A of the 1,2-alkanediol having 4 or less carbon atoms relative to the total mass of the ink composition to a content B of the alkanediol having 3 to 5 carbon atoms at both ends relative to the total mass of the ink composition is 0.1 to 1.

5.

3. 3. The ink-jet ink composition according to claim 1, wherein the total content of the organic solvents relative to the total mass of the ink composition is 30 mass % or less.

4. 4. The ink-jet ink composition according to claim 1, wherein the 1,2-alkanediol having 4 or less carbon atoms includes either propylene glycol or 1,2-butanediol.

5. An inkjet ink composition according to claim 1, wherein the acrylic resin is an acrylic-vinyl resin, which is a copolymer of a vinyl monomer and an acrylic monomer.

6. 6. The ink-jet ink composition according to claim 1, wherein the silicone surfactant has an HLB value of 2 to 10.

5.

7. The alkanediol having 3 to 5 carbon atoms at both ends is 1,3-propanediol, 1,4- 7. The ink-jet ink composition according to claim 1, further comprising either butanediol or 1,5-pentanediol.

8. 8. The ink-jet ink composition according to claim 1, wherein the ink composition contains no polyol organic solvents having a normal boiling point of more than 280°C in an amount of more than 1% by mass relative to the total mass of the ink composition.

9. 9. The ink-jet ink composition according to claim 1, wherein the acrylic resin has a glass transition temperature of 40 to 90°C.

10. The ink-jet ink composition according to any one of claims 1 to 9, which is used for recording on a low-absorbency recording medium or a non-absorbency recording medium by being applied to the recording medium.

11. The ink-jet ink composition according to claim 1 , wherein the acrylic resin comprises a styrene-acrylic resin.

12. A recording method comprising a step of ejecting the ink-jet ink composition according to claim 1 onto a recording medium by an ink-jet method.

13. 13. The recording method according to claim 12, wherein the recording medium is a low-absorbency recording medium or a non-absorbency recording medium.

14. 14. The printing method according to claim 12, wherein printing is performed by a plurality of main scans, and the number of main scans performed on the same scanning area is 10 or less.

15. 15. The recording method according to claim 12, wherein a primary heating step is performed to heat the inkjet ink composition adhered to the recording medium, and the surface temperature of the recording medium in the primary heating step is 40°C or higher.

16. The recording method according to claim 12 , further comprising a post-heating step of heating the recording medium to which the inkjet ink composition has been attached.

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