JP2013173235A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording device that forms high-quality images by performing high-speed printing by using water-based ink jet ink while suppressing curls of a paper medium.SOLUTION: An ink jet recording device includes: a pretreatment part forming a precoat layer by applying precoat liquid to a paper medium; and a recording ink jet head discharging water-based ink jet ink toward a paper medium with a precoat layer formed thereon to form an image. The precoat liquid contains 0.1-1 mass% of the total of polysaccharide selected from pectin and carrageenan and a solvent. The water-based ink jet ink contains 1-10 mass% of the total of a pigment and a dispersion medium. Each of the solvent and the dispersion medium contains in the total: 40-60 mass% of water; polyoxyalkylene diglyceryl ether occupying 30-50 mass% and having 1,000 or less of weight-average molecular weight; and 1-5 mass% of glycol ether.

Description

  Embodiments described herein relate generally to an ink jet recording apparatus.

  An aqueous inkjet ink is known as an ink for performing inkjet recording on a paper medium. In order to improve the quality of color images, it has been proposed to treat a paper medium with a quick-drying pretreatment liquid (precoat liquid) prior to recording with a water-based inkjet ink (see, for example, Patent Document 1). In the pretreatment, a pretreatment liquid containing pectins and glycol ethers is used.

  When ink jet recording is performed, the paper medium may be deformed such as curling. In particular, when the amount of water-based inkjet ink discharged onto a paper medium increases, the occurrence of curling becomes significant. At present, an ink jet recording apparatus capable of forming an image of excellent quality at a high speed while sufficiently suppressing curling of a paper medium even when using an aqueous ink jet ink has not yet been obtained.

JP 2010-69749 A

  The problem to be solved by the present invention is to provide an inkjet ink recording apparatus capable of forming an image of excellent quality by performing printing at high speed using an aqueous inkjet ink while suppressing curling of a paper medium. .

  The inkjet recording apparatus according to the embodiment includes a pretreatment unit that applies a precoat liquid to a paper medium to form a precoat layer, and discharges aqueous inkjet ink toward the paper medium on which the precoat layer is formed, and the precoat layer And a recording inkjet head for forming an image thereon. The precoat liquid occupies 40 to 60% by mass of the total amount of water and 30 to 50% by mass of the total amount, and the polyoxyethylene diglyceryl ether having a weight average molecular weight of 1000 or less and the polyoxypropylene having a weight average molecular weight of 1000 or less. Polyoxyalkylene diglyceryl ether selected from diglyceryl ether, glycol ether of 1 to 5% by mass of the total amount, and 0.1 to 1% by mass of the total amount, and at least one selected from pectin and carrageenan Polysaccharides. The water-based inkjet ink occupies 40 to 60% by mass of the total amount of water and 30 to 50% by mass of the total amount, and the polyoxyethylene diglyceryl ether having a weight average molecular weight of 1000 or less and the polyoxyethylene having a weight average molecular weight of 1000 or less. It contains polyoxyalkylene diglyceryl ether selected from propylene diglyceryl ether, 1 to 5% by mass of glycol ether of the total amount, and 1 to 10% by mass of pigment of the total amount.

1 is a schematic diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment. The illustrated ink jet recording apparatus includes paper cassettes 100 and 101 that contain paper P of different sizes. In order to take out the paper P corresponding to the selected paper size, the paper cassettes 100 and 101 are provided with paper feed rollers 102 and 103, respectively. Conveying roller pairs 104 and 105 are provided in the path along which the sheet P taken out from each sheet cassette is conveyed, and a registration roller pair 106 is disposed in the vicinity of the conveying belt 107.

  The conveyor belt 107 is tensioned by a driving roller 108 and two driven rollers 109. Through holes are provided in the conveyor belt 107 at predetermined intervals, and a negative pressure chamber 111 connected to the fan 110 is installed inside the conveyor belt 107. The sheet P can be attracted to the transport belt 107 by the action of the fan 110 and the negative pressure chamber 111. A pair of conveyance rollers 112, 113, and 114 are sequentially installed downstream of the conveyance belt 107 in the sheet conveyance direction.

  Five rows of inkjet heads are arranged above the conveyor belt 107. From the upstream in the transport direction, an inkjet head 115S that ejects a precoat liquid, an inkjet head 115C that ejects cyan (C) ink, an inkjet head 115M that ejects magenta (M) ink, and an inkjet head 115Y that ejects yellow (Y) ink. And the inkjet head 115Bk that discharges black (Bk) ink. The ink jet heads 115C, 115M, 115Y, and 115Bk discharge the respective inks onto the paper according to the image data. These inkjet heads that eject ink can be referred to as recording inkjet heads.

  The precoat liquid discharged from the inkjet head 115S is accommodated in the precoat liquid cartridge 116S, and is fed to the inkjet head 115S via the tube 117S. The pre-processing unit 120 is configured by the inkjet head 115S, the tube 117S, and the precoat liquid cartridge 116S. The supply of the precoat liquid from the precoat liquid cartridge 116S to the inkjet head 115S is controlled by an ink supply controller (not shown), and the discharge of the precoat liquid from the inkjet head 115S is controlled by an inkjet head drive controller (not shown). ).

  Each ink ejected from each inkjet head 115C, 115M, 115Y, and 115Bk is a water-based inkjet ink, and a cyan (C) ink cartridge 116C, a magenta (M) ink cartridge 116M, and a yellow (Y) ink cartridge 116Y. , And black (Bk) ink cartridge 116Bk. Each ink is supplied to the corresponding inkjet heads 115C, 115M, 115Y, and 115Bk via the tubes 117C, 117M, 117Y, and 117Bk, respectively. As in the case of the precoat liquid, the supply of ink from the ink cartridge to the inkjet head is controlled by an ink supply controller (not shown), and the ejection of ink from the inkjet head is controlled by an inkjet head drive controller (not shown). ).

  In the illustrated ink jet recording apparatus, the precoat liquid is applied to a predetermined region of the paper P using the ink jet head 115S, but the method of applying the precoat liquid is not limited to this. The precoat liquid can also be applied to the entire sheet P using a cylindrical application roller.

  An image forming operation of the illustrated ink jet recording apparatus will be described below.

  First, image processing for recording is started by an image processing means (not shown), and image data for recording is transferred to each of the inkjet heads 115S, 115C, 115M, 115Y, and 115Bk. The paper P of the selected paper size is taken out from the paper cassette 100 or 101 one by one by the paper feed roller 102 or 103. The paper P passes through the conveying roller pair 104 or 105, and after the skew is corrected by the registration roller pair 106, is fed onto the conveying belt 107 at a predetermined timing.

  Since the negative pressure chamber 111 sucks air through the through-hole of the conveyance belt 107, the sheet P is adsorbed by the conveyance belt 107, and the lower side of the inkjet heads 115S, 115C, 115M, 115Y, and 115Bk. Be transported. A constant interval is maintained between each inkjet head 115S, 115C, 115M, 115Y and 115Bk and the paper P.

  In synchronism with the timing when the paper P is conveyed from the registration roller pair 106, first, the precoat liquid is discharged from the inkjet head 115S. A precoat layer is formed on the surface of the paper P, whereby the paper P is pretreated. The precoat liquid used here has a specific composition as described in detail below.

  The paper P on which the precoat layer is formed is transported below the recording inkjet head, and each inkjet head 115C, 115M, 115Y, and 115Bk discharges each color aqueous inkjet ink. After a color image is formed at a predetermined position, the paper P is discharged onto the paper discharge tray 118 by the transport roller pairs 112, 113, and 114. The water-based inkjet ink used for recording has a specific composition as described in detail below.

  The paper P on which ink jet recording is performed in the apparatus shown in FIG. 1 can be referred to as a paper medium. A paper medium generally refers to a paper medium used for the purpose of printing. Paper media are broadly classified into coated paper such as art paper or coated paper coated with a material for enhancing printing characteristics, and non-coated paper utilizing the characteristics of the paper itself. Paper media are used for various applications such as books, books, newspapers, packaging, and printer paper. Cardboard, paper containers, and cardboard such as cardboard are also included in the paper medium. For example, a so-called plain paper such as a copying machine used in an office or home or a copy paper used in a printer is a typical paper medium.

  By using the inkjet recording apparatus of the present embodiment, it is possible to perform printing at high speed using a water-based inkjet ink and to form an image of excellent quality on a paper medium. In addition, deformation of the paper medium such as curling is also suppressed after printing. Such an effect is obtained by pre-processing a paper medium with a pre-coating liquid having a specific composition in a pre-processing section, and then performing recording using a water-based inkjet ink having a specific composition.

  The precoat solution contains a solvent and a polysaccharide. Specifically, the solvent is 40-60 mass% of the total amount of the precoat liquid, 30-50 mass% of the polyoxyalkylene diglyceryl ether of the total amount of the precoat liquid, and 1-5 mass% of the glycol ether of the total amount of the precoat liquid. including.

  One aqueous inkjet ink contains a dispersion medium and a pigment. Specifically, the dispersion medium is 40 to 60% by mass of water based on the total amount of the aqueous inkjet ink, 30 to 50% by mass of polyoxyalkylene diglyceryl ether based on the total amount of the aqueous inkjet ink, and 1 to 5% by mass based on the total amount of the aqueous inkjet ink. % Glycol ether. That is, the solvent in the precoat liquid described above is used as a dispersion medium in the aqueous inkjet ink.

  The polyoxyalkylene diglyceryl ether is selected from polyoxyethylene diglyceryl ether having a weight average molecular weight of 1000 or less and polyoxypropylene diglyceryl ether having a weight average molecular weight of 1000 or less.

  It has been found by the present inventors that a curl suppressing effect can be obtained by combining 30 to 50% by mass of polyoxyalkylene diglyceryl ether and 40 to 60% by mass of water. In addition, the dispersion medium normally used for the water-based inkjet ink is, for example, a mixed liquid of a glycol solvent and 60% by mass or more of water. The precoat liquid and the water-based inkjet ink having the above composition are considered to suppress a decrease in paper strength due to swelling of paper fibers because the solubility parameter is shifted to the hydrophobic side as compared with a normal water-based inkjet ink. As a result, the curl of the paper medium is estimated to be reduced.

  In both the precoat liquid and the water-based inkjet ink, when the amount of water is less than 40% by mass of the total amount, the viscosity increases and the dischargeability from the inkjet head decreases. On the other hand, when the amount of water exceeds 60% by mass of the total amount, curling of the paper medium cannot be suppressed. In any case of the precoat liquid and the water-based inkjet ink, the amount of water is preferably 40 to 55% by mass of the total amount. As water, for example, pure water, ion-exchanged water or the like can be used.

  Further, in both the precoat liquid and the water-based inkjet ink, when the amount of polyoxyalkylene diglyceryl ether is less than 30% by mass of the total amount, curling of the paper medium cannot be sufficiently suppressed. On the other hand, when the amount of the polyoxyalkylene diglyceryl ether exceeds 50% by mass of the total amount, the viscosity becomes so high that it cannot be stably discharged from the inkjet head. In any case of the precoat liquid and the water-based inkjet ink, the amount of polyoxyalkylene diglyceryl ether is preferably 30 to 45% by mass of the total amount.

  If water and polyoxyalkylene diglyceryl ether are blended so as to have a predetermined concentration with respect to the total amount of the precoat liquid or the water-based inkjet ink, a desired effect can be obtained. Therefore, there is no particular limitation between the amount of water and the amount of polyoxyalkylene diglyceryl ether.

  In addition, when the weight average molecular weight of polyoxyalkylene diglyceryl ether exceeds 1000, the discharge stability from an inkjet head will fall. When a polyoxyalkylene diglyceryl ether having a weight average molecular weight of 1000 or less is contained, viscosity and storage stability are also appropriate. On the other hand, considering the curl suppressing effect, the weight average molecular weight of the polyoxyalkylene diglyceryl ether is desirably 400 or more. The weight average molecular weight of polyoxyethylene diglyceryl ether is more preferably 450 to 700, and the weight average molecular weight of polyoxypropylene diglyceryl ether is more preferably 400 to 700.

  Since water is contained in a predetermined amount together with the specific polyoxyalkylene diglyceryl ether, the precoat liquid and the water-based inkjet ink used in this embodiment are excellent in quick drying when attached to a paper medium, Curling of the medium can be suppressed as much as possible. In addition, there is very little risk of clogging of the inkjet head, and the inkjet head can be stably ejected.

  The precoat liquid and aqueous inkjet ink used in the present embodiment further contain a predetermined amount of glycol ether. Glycol ethers can be referred to as penetrants because they increase the permeability of liquids such as precoat liquids or water-based inkjet inks to paper media and further improve drying properties. Glycol ether also has the effect of reducing the curl of the paper medium.

  Examples of glycol ethers include 3-methoxy-3-methyl-1-butanol, dipropylene glycol-n-propyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether. Since there is little odor, 3-methoxy-3-methyl- 1-butanol is preferable as glycol ether.

  The amount of glycol ether in the precoat solution is 1 to 5% by mass of the total amount. When the amount of glycol ether is less than 1% by mass of the total amount, the effect of penetrating into the paper medium is insufficient. On the other hand, when the amount of glycol ether exceeds 5% by mass of the total amount, the storage stability of the precoat solution is lowered. The amount of glycol ether is preferably 1 to 3% by mass of the total amount of the precoat solution. For the same reason, the glycol ether is contained in the same amount in the water-based inkjet ink.

  A mixture of water, polyoxyalkylene diglyceryl ether, and glycol ether blended in a predetermined amount constitutes a solvent for the precoat liquid used in the ink jet recording apparatus of the present embodiment. This mixture is used as a dispersion medium in the aqueous inkjet ink used in the inkjet recording apparatus of the present embodiment.

  The precoat liquid used in this embodiment contains the solvent and polysaccharide as described above.

  The polysaccharide is selected from pectin and carrageenan, and either one may be used alone, or two may be used in combination. When such a precoat solution containing polysaccharides is applied to a paper medium, a precoat layer is formed on the surface of the paper medium and a pretreatment is performed. Since the precoat layer formed is excellent in capturing pigment particles, when recording is performed on a paper medium after pretreatment with a water-based inkjet ink, bleeding of the ink printed on the paper medium, image Can be prevented from passing through.

  The content of the polysaccharide is 0.1 to 1% by mass of the total amount of the precoat solution. When the amount of polysaccharide is less than 0.1% by mass of the total amount of the precoat liquid, the effect of suppressing ink bleeding and back-through is insufficient. On the other hand, if the content of polysaccharide exceeds 1% by mass of the total amount of the precoat liquid, the viscosity of the precoat liquid becomes high and cannot be stably discharged from the inkjet head. As for content of the polysaccharide in a precoat liquid, 0.2-1 mass% is preferable.

  Water, polyoxyalkylene diglyceryl ether, glycol ether, and polysaccharide are blended in predetermined amounts, respectively, to obtain a precoat solution used in this embodiment.

  On the other hand, the water-based inkjet ink used in the present embodiment contains a dispersion medium and a pigment as described above. An ink using a pigment as a colorant can form an image having higher fastness than an ink using a dye.

  The pigment is not particularly limited, and any of an inorganic pigment and an organic pigment may be used. Examples of inorganic pigments include titanium oxide and iron oxide. Furthermore, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used.

  Examples of the organic pigment include azo pigments (including azo lake pigments, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, Dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (eg, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used.

  Specifically, as carbon black used as black ink, 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B, etc. (Mitsubishi Chemical), Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc. (Colombia), Regal 400R, Regal 330R, Regal 660R, Morgan Ch 700, M 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. (manufactured by Cabot Corporation), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW2V, Color Black FW2V, Color Black FW2V, Color Black FW2V, Color Black FW2V, Color Black FW2V r Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, PrintexV, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, and Special Black 4, etc. (manufactured by Degussa) and the like.

  Specific examples of the pigment used for the yellow ink include C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14C, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment Yellow 109, C.I. I. Pigment Yellow 110, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 180, and C.I. I. Pigment Yellow 185 and the like.

  Specific examples of the pigment used in the magenta ink include C.I. I. Pigment Red 5, C.I. I. Pigment Red7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 168, C.I. I. Pigment Red 184, C.I. I. Pigment Red 202, and C.I. I. Pigment Violet 19 and the like.

  Specific examples of the pigment used in the cyan ink include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 15:34, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60, C.I. I. Vat Blue 4, and C.I. I. Vat Blue 60 is an example.

  Since it is for inkjet inks, the average particle size of the pigment is preferably in the range of about 10 to 300 nm. Furthermore, the average particle diameter of the pigment is more preferably in the range of about 10 to 200 nm.

  The average particle diameter of the pigment can be measured using a particle size distribution meter using a dynamic light scattering method. An example of the particle size distribution meter is HPPS (Malvern).

  The pigment can be used in the state of a pigment dispersion. The pigment dispersion can be prepared, for example, by dispersing the pigment in water or alcohol using a dispersant. Examples of the dispersant include a surfactant, a water-soluble resin, and a water-insoluble resin. Alternatively, a self-dispersing pigment may be used. The self-dispersing pigment is a pigment that can be dispersed in water or the like without a dispersant. The pigment is subjected to a surface treatment, and at least one functional group of a carbonyl group, a carboxyl group, a hydroxyl group, and a sulfone group or a salt thereof is obtained. It is a combined pigment. Examples of the surface treatment include vacuum plasma treatment, diazo coupling treatment, and oxidation treatment. A self-dispersed pigment can be obtained by grafting a functional group or a molecule containing a functional group onto the surface of the pigment by such surface treatment.

  The pigment content in the ink is 1 to 10% by mass of the total ink. An ink-jet ink containing a pigment within this range can form an image having a necessary density without causing any inconvenience in terms of ink storage stability and ejection performance. The content of the pigment is preferably 3 to 8% by mass of the total amount of ink.

  The pigment dispersion is mixed with a dispersion medium containing water, polyoxyalkylene diglyceryl ether, and glycol ether so as to have a predetermined composition, whereby the aqueous inkjet ink used in the present embodiment is obtained.

  Since the ink is used for ink jet recording, the ink used in the present embodiment needs to have an appropriate viscosity for ejection from the nozzle of the head in the ink jet printer. Specifically, the viscosity at 25 ° C. is preferably 6 to 15 mPa · s. If it is 10 mPa · s or less, the temperature of the inkjet head during the ejection operation can be set relatively low (for example, about 20 ° C. or less).

  The precoat liquid or the water-based inkjet ink as described above may contain a humectant for preventing drying.

  Examples of the humectant include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, glycerin, 1,5-pentanediol, 1,6-hexanediol, 1 Polyhydric alcohols such as 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, and petriol; N-methyl-2-pyrrolidone, N-hydroxyethyl-2 Nitrogen-containing heterocyclic compounds such as pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamino And amines such as triethylamine; dimethyl sulfoxide, sulfolane, and sulfur-containing compounds such as thiodiethanol. Furthermore, propylene carbonate, ethylene carbonate, γ-butyrolactone, or the like can also be used as a humectant.

  In any case of the precoat liquid and the water-based inkjet ink, it is desirable that the content of the humectant is 5% by mass or less of the total amount. If it exceeds 5 mass%, the curl suppressing ability may be reduced.

  In the precoat liquid and the water-based inkjet ink, an additive selected from a surface tension adjusting agent, a viscosity adjusting agent, a pH adjusting agent, an antiseptic / fungicide, and the like may be blended as necessary.

  Examples of the surface tension adjusting agent include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, and polyoxyethylene alkyl ether sulfate salt.

  Water-soluble surfactants also act as surface tension modifiers. Here, water solubility means that 1% by mass or more dissolves in water, and any of nonionic surfactants, acetylene glycol surfactants and fluorine surfactants may be used.

  Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkylamine, and polyoxyethylene alkylamide. Is mentioned.

  Examples of acetylene glycol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5. -Dimethyl-1-hexyn-3-ol and the like. Specifically, Surfynol 104, 82, 465, 485, TG, or the like (manufactured by Air Products) is used.

  Examples of the fluorosurfactant include perfluoroalkyl ethylene oxide adduct, perfluoroalkyl amine oxide, perfluoroalkyl carboxylate, and perfluoroalkyl sulfonic acid. Specifically, MegaFuck F-443, F-444, F-470, F-494 (Dainippon Ink Chemical Co., Ltd.), Novec FC-430, FC-4430 (3M Company), Surflon S-141, S- 145, S-111N, S-113 (Seimi Chemical Co.).

  These surfactants are desirably added to such an extent that the dispersion stability of the ink is not deteriorated. In any case of the precoat liquid and the water-based inkjet ink, the surfactant can exhibit an effect without any inconvenience if it is contained in a weight of about 0.2 to 3% by mass of the total amount. it can.

  Examples of the viscosity modifier include water-soluble resins such as polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, water-soluble acrylic resin, polyvinyl pyrrolidone, gum arabic, dextrin, casein, alginic acid, and peptin.

  Among these water-soluble resins, for example, a water-soluble acrylic resin can be used as a dispersant for preparing a pigment dispersion.

  Examples of the pH adjuster include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, and triethanolamine.

  Examples of antiseptics and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, and 1,2-dibenzisothiazoline-3- ON (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN from ICI) and the like can be used.

  By blending these additives, the storage stability of the precoat liquid and the aqueous inkjet ink is further improved. Moreover, the quality of the obtained image is even higher.

  Hereinafter, specific examples of ink jet recording on a paper medium using an ink jet recording apparatus will be shown.

Each component was mix | blended with the prescription shown in following Table 1, and five types of precoat liquids (Pre-1, Pre-2, Pre-3, Pre-4, and Pre-5) were obtained.

  POE1 represents polyoxyethylene diglyceryl ether, POE2 represents polyoxypropylene diglyceryl ether, and MMB represents 3-methoxy-3-methyl-1-butanol. The weight average molecular weight of polyoxyethylene diglyceryl ether (POE1) is 450, and the weight average molecular weight of polyoxypropylene diglyceryl ether (POE2) is 400.

  In the table, the amount of each component is mass% with respect to the total amount of the precoat solution. To all the precoat solutions, 1% by mass of the total amount of surfactant and 0.2% by mass of the preservative were further added. Surfactol 465 was used as the surfactant, and Proxel XL-2 (S) was used as the preservative.

  In preparing the precoat solution, each component was first mixed according to each formulation and stirred with a stirrer for 1 hour. Then, it filtered with a 1.0 micrometer membrane filter and obtained each precoat liquid. All of the five types of precoat liquid contain 40 to 60% by mass of the total amount of water and 30 to 50% by mass of the total amount of polyoxyalkylene diglyceryl ether (POE1 and / or POE2). . In addition, all the precoat liquids contain 3-methoxy-3-methyl-1-butanol (MMB) as a glycol ether in an amount of 1 to 5% by mass of the total amount. Further, all precoat liquids contain a polysaccharide selected from pectin and carrageenan in an amount of 0.1 to 1% by mass of the total amount.

Each component was blended according to the formulation shown in Table 2 below, and seven types of water-based inkjet inks (I-1, I-2, I-3, I-4, I-5, I-6 and I-7) Got. In the table, the amount of each component is mass% with respect to the total amount of inkjet ink. POE1, POE2, and MMB are the same as the above-mentioned precoat liquid. DPGPE represents dipropylene glycol-n-propyl ether, GLC represents glycerin, and DPG represents dipropylene glycol.

  In the column of the pigment in the table, the type of the pigment dispersion used and the solid content (mass%) of the pigment in the inkjet ink are shown. The pigment dispersion is a Cabot self-dispersion type carbon black dispersion (CB1) or a Fuji dye resin dispersion carbon black dispersion (CB2), and 15% by mass of carbon black is dispersed in water. The average particle size of carbon black is about 100 nm. The amount of water contained in such a pigment dispersion is included in the amount of water in Table 2 above.

  As shown in Table 2 above, in any water-based inkjet ink, the pigment dispersion was blended in such an amount that the solid content of the pigment was 5% by mass of the total amount of the ink.

  All water-based inkjet inks were added with a total amount of 0.8% by weight surfactant and a total amount of 0.2% by weight preservative. Surfactol 465 was used as the surfactant, and Proxel XL-2 (S) was used as the preservative.

  In preparing the water-based inkjet ink, first, each component was mixed according to each formulation, and stirred with a stirrer for 1 hour. Then, it filtered with a 1.0 micrometer membrane filter, and obtained each water-based inkjet ink.

  In all seven types of water-based ink-jet inks, 3-methoxy-3-methyl-1-butanol (MMB) or dipropylene glycol-n-propyl ether (DPGPE) as a glycol ether is 1 to 5% by mass of the total amount. In any case, the amount of the pigment is 5% by mass of the total amount. In the inks of I-1 to I-5, the amount of water is in the range of 40 to 60 mass% of the total amount, and the amount of polyoxyalkylene diglyceryl ether (POE1 and / or POE2) is 30 to 50 mass of the total amount. %, But the I-6 and I-7 inks contain more than 60% by weight of the total amount of water. Moreover, the I-6 and I-7 inks do not contain polyoxyalkylene diglyceryl ether (POE1 and / or POE2).

In an inkjet recording apparatus equipped with a TOSHIBA TEC piezo head, inkjet recording was performed on plain paper as a paper medium using a combination of a precoat liquid and an aqueous inkjet ink as shown in Table 3 below. Since the precoat liquid (Pre-1 to Pre-5) having a predetermined composition and the water-based inkjet ink (I-1 to I-5) having a predetermined composition are used, no. 1-No. Reference numeral 9 denotes recording using the ink jet recording apparatus of the present embodiment. No. Nos. 10 and 11 do not correspond to recording using the inkjet recording apparatus of the present embodiment because the aqueous inkjet ink (I-6, I-7) containing water exceeding 60% by mass of the total amount is used. No. No precoat liquid having a predetermined composition is used. Neither 12 nor 13 corresponds to recording using the ink jet recording apparatus of the present embodiment.

  Specifically, using the inkjet recording apparatus shown in FIG. 1, Toshiba TEC piezo heads were mounted as inkjet heads 115S, 115C, 115M, 115Y, and 115Bk. A predetermined aqueous inkjet ink was stored in the black (Bk) ink cartridge 116Bk, and a predetermined precoat liquid was stored in the precoat liquid cartridge 116S as necessary.

  First, after the precoat liquid was adhered to plain paper at 100 duty, solid printing was performed at 100 duty, and the state of the paper after recording was examined. As the plain paper, five types of paper, Toshiba copy paper, Xerox 4024 paper, Ricoh high grade plain paper (type E), Tidal MP paper, and NEUSEDEDLER paper were used. The printed paper was placed on a flat desk, and after 1 minute, the height at which the four corners of the paper were lifted from the surface of the desk was measured. The average height of the five types of paper was taken as the curl height, and the determination was made according to the following criteria.

A: Less than 10 mm B: 10 mm or more and less than 20 mm C: 20 mm or more and less than 60 mm D: 60 mm or more If the curl height is less than 10 mm, the paper state after recording is good.

  Next, the same plain paper as described above was pretreated in the same manner, and then a solid image was printed to examine the image density. Specifically, the density of the solid image was measured using an X-Rite image density measuring device, and the image density on the front and back of the plain paper was determined.

Further, the same plain paper as described above was pretreated in the same manner, and then character printing was performed to calculate the dot shape factor of the printed image. The shape factor is an evaluation value obtained by quantifying the degree of bleeding, and is calculated by (circumferential length) ² / (4π × area). Circumference length and area were determined by image analysis using a dot analyzer. When the irregularity of the dot shape is small, the value of the shape factor is close to 1.

The average values of five types of plain paper were determined for the image density (D _F ), the back image density (D _B ), and the shape factor (SC) of the table, and evaluated according to the criteria shown in Table 4 below.

  Furthermore, quick drying property was examined by the following method. First, a pre-coating solution was applied to a 10 mm × 10 mm region of Toshiba copy paper paper at 100 duty and pre-treated, and then a solid image was printed at 100 duty. After printing, the sheet was left for a predetermined time, and a new same paper was placed on the solid image portion and a 300 g weight was placed thereon. After 10 seconds, the weight was removed, and it was visually examined whether ink had adhered to the new paper.

  The time for leaving the sheet on which the solid image was printed was set to four types of 5 seconds, 10 seconds, 30 seconds, and 60 seconds. The degree of ink adhesion to the stacked paper was visually confirmed, and the determination was made according to the following criteria based on the standing time and the state of ink adhesion. If the ink does not adhere even after being left for a short time, it can be said that the quick drying property is good. This is advantageous in that high-speed printing is possible.

A: No adhesion after leaving for 5 seconds B: No adhesion after leaving for 10 seconds C: No adhesion after leaving for 30 seconds D: Adhesion even after leaving for 60 seconds The paper condition after printing, print quality, and quick-drying The results are summarized in Table 5 below. If all these three evaluations are “A”, it is acceptable, and if one evaluation is “B”, it is also acceptable. If any one of the evaluations is “C” or “D” and if “B” is two or more, it is NG.

  As shown in Table 5 above, No. 1 in which the ink jet recording apparatus of this embodiment was used. Nos. 1 to 9 are satisfactory in terms of the paper state after recording, print quality, and quick-drying properties. No. In Nos. 1 to 9, water-based inkjet inks (I-1 to I-5) having a predetermined composition are prepared after pretreatment of a paper medium with a precoat liquid (Pre-1 to Pre-5) having a predetermined composition. Recording is performed using.

  When the ink jet recording apparatus of the present embodiment is not used (Nos. 10 to 13), it is not possible to satisfy all of the paper state after recording, the print quality, and the quick drying property simultaneously.

  In Nos. 10, 11, the state of the paper after recording is extremely inferior. In these, the amount of water contained in the water-based inkjet ink is large although the pretreatment liquid (Pre-1, Pre-2) having a predetermined composition is pretreated. Ink (I-6, I-7) containing water exceeding 60% by mass of the total amount of ink and containing no polyoxyalkylene diglyceryl ether cannot suppress curling of plain paper.

  By using the water-based inkjet ink having a predetermined composition, curling of plain paper is suppressed, and the paper state after recording is good. However, if the pretreatment with the precoat liquid having a predetermined composition is not performed, it is impossible to satisfy the conditions for quick drying as well as print quality. 12 and 13.

  By using the ink jet recording apparatus of this embodiment, it is possible to perform printing at high speed using a water-based ink-jet ink while suppressing curling of a paper medium, and to form an image of excellent quality.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

P ... paper; 100 ... paper cassette; 101 ... paper cassette; 102 ... feed roller 103 ... feed roller; 104 ... conveying roller pair; 105 ... conveying roller pair 106 ... registration roller pair; 107 ... conveying belt; 110 ... Fan; 111 ... Negative pressure chamber 112 ... Conveying roller pair; 113 ... Conveying roller pair; 114 ... Conveying roller pair 115S ... Inkjet head; 116S ... Precoat liquid cartridge 115C, 115M, 115Y, 115Bk ... Recording ink-jet heads 116C, 116M, 116Y, 116Bk ... ink cartridge 117 ... tube; 118 ... discharge tray; 120 ... pre-processing unit.

Claims (6)

A pretreatment unit for forming a precoat layer by applying a precoat liquid to a paper medium;
An inkjet recording apparatus comprising: a recording inkjet head that discharges aqueous inkjet ink toward a paper medium on which the precoat layer is formed to form an image on the precoat layer;
The precoat liquid is
40-60 mass% water of the total amount,
A polyoxyalkylene diglyceryl ether occupying 30-50% by mass of the total amount and selected from polyoxyethylene diglyceryl ether having a weight average molecular weight of 1000 or less and polyoxypropylene diglyceryl ether having a weight average molecular weight of 1000 or less;
1-5% by weight of the total amount of glycol ether,
Occupying 0.1-1 mass% of the total amount, containing at least one polysaccharide selected from pectin and carrageenan,
The water-based inkjet ink is
40-60 mass% water of the total amount,
A polyoxyalkylene diglyceryl ether occupying 30-50% by mass of the total amount and selected from polyoxyethylene diglyceryl ether having a weight average molecular weight of 1000 or less and polyoxypropylene diglyceryl ether having a weight average molecular weight of 1000 or less;
1-5% by weight of the total amount of glycol ether,
An ink jet recording apparatus comprising 1 to 10% by mass of the pigment in the total amount. The pre-processing unit is
2. A precoat liquid cartridge that contains the precoat liquid, and a precoat liquid inkjet head that discharges the precoat liquid fed from the precoat liquid cartridge toward the paper medium. The ink jet recording apparatus described.   The inkjet recording apparatus according to claim 1, wherein the glycol ether contained in the precoat liquid is 3-methoxy-3-methyl-1-butanol.   The inkjet recording apparatus according to claim 1, wherein the glycol ether contained in the aqueous inkjet ink is 3-methoxy-3-methyl-1-butanol.   The inkjet recording apparatus according to claim 1, wherein the water-based inkjet ink further contains a polyhydric alcohol having a mass of 5% or less.   6. The ink jet recording apparatus according to claim 5, wherein the polyhydric alcohol is selected from the group consisting of glycerin and dipropylene glycol.

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