JP2015054489A - Image formation method, image formation apparatus and processing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation method which can suppress curling even when plain paper is used as a recording medium.SOLUTION: (1) An image formation method includes a processing liquid application step of applying a processing liquid onto a paper-made recording medium and an aqueous ink application step of applying an aqueous ink, and protective groups for the hydroxyl group of cellulose of the paper are introduced by the processing liquid application step. (2) Another image formation method is based on an ink jet recording system in which the aqueous ink application step comprises applying thermal energy or mechanical energy to the aqueous ink so as to discharge an ink.

Description

  The present invention relates to an inkjet image forming method, an image forming apparatus, and a processing liquid used for the image forming method, in which an aqueous ink is discharged from a head to form an image.

In conventional inkjet printers, when water-based ink is ejected onto a plain paper-based recording medium without an ink receiving layer, the cellulose fibers that make up the recording medium absorb water, which is the solvent for the water-based ink, and hydrogen bonds are broken. Swells. In particular, when the amount of water-based ink becomes extremely large when printing on the entire surface of the recording medium, a phenomenon that the recording medium curls occurs, and when the recording medium in which the curling phenomenon occurs is conveyed to a discharge tray by a conveyance roller or the like, There was a problem that a jam of the recording medium occurred. Further, when the recording medium is discharged to the paper discharge tray while curled, there is a problem that the recording medium stackability in the paper discharge tray is poor.
As a method for correcting this curl, a method is generally employed in which the recording medium is heated to evaporate and dry the moisture that has soaked into the recording medium, which is the cause of curling. The heating method is roughly divided into a contact heating method and a non-contact heating method. The contact heating method is a method in which, for example, a pair of heating rollers are directly in surface contact with a recording medium to perform heat treatment. Although drying by this contact heating method is efficient, the resin layer formed on the recording medium is melted to disturb the image, or a part of the molten resin layer adheres to the heating roller side, and the next recording medium is There were problems such as contamination.

In contrast, in the non-contact heating method, the heating means does not contact the recording medium and heats from a position facing away from the recording medium. Does not cause dirt.
As this non-contact heating method, those described in Patent Documents 1 to 3 are known. In Patent Document 1, the recording medium is heated by the non-contact heating means over the entire length of the recording medium in the direction orthogonal to the recording medium conveyance direction while feeding the recording medium by the feeding mechanism. In Patent Document 2, the entire printing surface of the recording medium after printing is heated by a number of heaters to evaporate moisture on the printing surface, and vapor is sucked from the surface opposite to the printing surface to adjust the moisture on the printing surface. The moisture difference between the front and back of the recording medium is made equal. In patent document 3, the recording medium after printing is heat-processed with the heater arrange | positioned along each diagonal of a recording medium.

In the above-mentioned patent document 1, since the recording medium to be conveyed is heated only when it passes through the heating range of the heating device, the temperature cannot be raised to a sufficient temperature for correcting the curl and the curl correction becomes insufficient. was there. Further, in Patent Document 2, since a portion other than the printing portion that does not contain moisture is heated, a moisture difference occurs between the front and back of the recording medium, and the surface of the recording medium becomes uneven and wavy. There was a problem that caused a phenomenon called. Further, in Patent Document 3, since the recording medium is not fixed at the time of heating, there is a problem that when the moisture in the recording medium evaporates and contracts, the image is arbitrarily contracted and the image is disturbed.
SUMMARY An advantage of some aspects of the invention is that it provides an image forming method capable of suppressing curling even when plain paper is used as a recording medium.

The above problem is solved by the following invention 1).
1) A treatment liquid application step for applying a treatment liquid onto a paper recording medium, and an aqueous ink application step for applying an aqueous ink following the treatment liquid application step, to the hydroxyl group of cellulose of the paper by the treatment liquid application step. An image forming method, wherein a protecting group is introduced on the surface.

  According to the present invention, it is possible to provide an image forming method capable of suppressing curling even when plain paper is used as a recording medium. That is, since a protective group is introduced into the hydroxyl group of the cellulose of paper, the hydrogen bond breakage can be suppressed even if water, which is a solvent of the aqueous ink, is absorbed, and the paper is difficult to swell. In the present invention, image disturbance is not caused.

(A) is a schematic diagram in which hydrogen bonds are formed between hydroxyl groups of cellulose in paper, (b) is a schematic diagram in which water penetrates and breaks hydrogen bonds between hydroxyl groups of cellulose, and (c) is paper. The schematic diagram which has couple | bonded with the intermolecular force between protective groups, when protecting the hydroxyl group of the cellulose of a cellulose with a protective group. 1 is a schematic view showing an example of an image forming apparatus for carrying out an image forming method of the present invention.

Hereinafter, the present invention 1) will be described in detail. However, since the following 2) to 6) are also included in the embodiment of the present invention 1), these will be described together.
2) The image forming method according to 1), wherein the water-based ink application step includes an ink jet recording method in which thermal energy or mechanical energy is applied to the water-based ink to perform ink ejection.
3) The protective group is any one of an acetyl group, an acetal group, a methyl group, a methoxymethyl group, a benzyl group, a p-methoxybenzyl group, a silyl group, and a tetrahydropyranyl group. ) Image forming method.
4) A processing liquid applying unit that applies the processing liquid to the recording medium and a head that discharges the aqueous ink are provided. After the processing liquid is applied to the recording medium by the processing liquid applying unit, the aqueous ink is discharged by the head. An image forming apparatus for use in the image forming method according to any one of 1) to 3), wherein
5) A treatment liquid drying means is further provided, the treatment liquid is applied to the recording medium by the treatment liquid application means, the treatment liquid is dried by the treatment liquid drying means, and then the aqueous ink liquid is discharged by the head. 4) The image forming apparatus as described in 4).
6) A processing solution used in the image forming method according to any one of 1) to 3), which comprises acetic anhydride and pyridine.

<Processing liquid>
The treatment liquid used in the present invention introduces a protecting group for the hydroxyl group of cellulose on paper. The kind of protecting group is not particularly limited as long as it is a functional group that does not hydrogen bond.
Specific examples include acetyl group, acetal group, methoxymethyl group, p-methoxybenzyl group, methyl group, silyl group, benzyl group, tetrahydropyranyl group, benzoyl group, tertiary butyl group, ethoxyethyl group, ethoxyethyl group. , Bivaloyl group, trimethylsilyl group, triethylsilyl group, tert-butyldimethylsilyl group, triisopropylsilyl group, tert-butyldiphenylsilyl group and the like.
The protective group is preferably hydrophobic because the paper does not swell even when water penetrates.
The material of the treatment liquid is not particularly limited, but preferably does not contain water in order not to curl the paper.

Examples of the material for introducing the acetyl group include acetic acid and acetic anhydride. Moreover, it is preferable to contain bases, such as a pyridine, at the point which accelerates | stimulates reaction.
The amount of acetic anhydride in the treatment liquid determines the amount by which the hydroxyl group of the cellulose of paper can be acetylated. However, in order to apply the treatment liquid satisfactorily, the content of acetic anhydride in the treatment liquid is 0.5-50. % By weight is preferred, more preferably 1-30% by weight.
The mixing ratio of acetic anhydride and pyridine when pyridine is used in combination is preferably 0.1: 1 to 1: 0.1 in terms of molar ratio, more preferably 0.5: 1 to 1: 0.5, Preferably it is 1: 1.1-1.1: 1. If it is this range, since the decomposition product of acetic anhydride can be neutralized satisfactorily, the reaction easily proceeds.

Examples of the material for introducing the acetal group include 2,2-dimethoxypropane and isopropenyl acetate. Further, it is preferable to contain an acid such as camphorsulfonic acid or pyridinium p-toluenesulfonate because the reaction is accelerated.
Examples of the material into which the methoxymethyl group is introduced include methyl chloride methyl ether, methyl bromide methyl ether, and methyl methyl iodide. Moreover, it is preferable to contain a base such as sodium hydride since the reaction is accelerated.
Examples of the material into which the p-methoxybenzyl group is introduced include -p-methoxybenzyl chloride and -p-methoxybenzyl bromide.
Examples of the material for introducing the methyl group include methyl chloride, methyl bromide, methyl iodide and the like. Moreover, it is preferable to contain a base such as potassium carbonate or sodium hydride because the reaction is accelerated.

Examples of the material for introducing the silyl group include chloride-t-butyldimethylsilane, bromide-t-butyldimethylsilane, iodide-t-butyldimethylsilane, chloride-t-triethylsilane, bromide-t-triethyl. Silane, iodide-t-triethylsilane, chloride-t-butyldiphenylsilane, bromide-t-butyldiphenylsilane, iodide-t-butyldiphenylsilane, chloride-t-triisopropylsilane, bromide-t-tri Examples thereof include isopropyl silane and iodinated t-triisopropyl silane. These materials are reacted with imidazole in N, N-dimethylformamide.
As another method for introducing a silyl group, t-butyldimethylsilyl triflate, t-triethylsilyl triflate, t-butyldiphenylsilyl triflate, t-triisopropylsilyl triflate may be allowed to act together with 2,6-lutidine. .

Examples of the material into which the benzyl group is introduced include benzyl chloride, benzyl bromide, benzyl iodide and the like. Moreover, it is preferable to contain a base such as sodium hydride since the reaction is accelerated.
Examples of the material into which the tetrahydropyranyl group is introduced include dihydropyran. Moreover, it is preferable to contain an acid catalyst since the reaction is accelerated.
Examples of the material into which the benzoyl group is introduced include benzoyl chloride and benzoyl bromide. Further, it is preferable to contain a base such as pyridine, triethylamine, sodium hydroxide, etc., because the reaction is accelerated.
Examples of the material for introducing the tertiary butyl group include isobutene. Moreover, it is preferable to contain a catalytic amount of an acid catalyst because the reaction is accelerated.

<Mechanism to prevent curling by treatment liquid>
The mechanism for preventing curling by the treatment liquid in the present invention will be described with reference to FIG.
As shown in FIG. 1A, the paper fibers in the paper recording medium are bonded by hydrogen bonds between the hydroxyl groups of cellulose of the paper.
However, when water penetrates into the paper, as shown in FIG. 1B, hydrogen bonds between the hydroxyl groups of the cellulose of the paper are broken, and the paper fibers are separated. Then, when the water between the hydroxyl groups is not dried or the like, hydrogen bonding occurs again between the hydroxyl groups. However, curling occurs because hydrogen bonding with other hydroxyl groups occurs during the recombination.
On the other hand, as shown in FIG. 1 (c), when the protective group R is introduced into the cellulose hydroxyl group of the paper by the treatment liquid, even if the paper absorbs water, the site where the protective group is introduced is intermolecular force. Can be combined. Therefore, the site where the protective group is introduced maintains the bond even when water penetrates, so when the hydroxyl group of another site is hydrogen-bonded again, it recombines with the hydroxyl group that was previously hydrogen-bonded. And curling can be suppressed.

<Water-based ink>
Examples of the colorant for the water-based ink include an anionic dye, a cationic dye, an anionic dispersant, a pigment dispersed with a cationic dispersant, a colored emulsion, and the like.
As the anionic dye, those containing three or more carboxyl groups or sulfonic acid groups in the molecule are particularly preferable in terms of ensuring the storage stability and anti-clogging properties of the water-based ink.
Examples of the anionic dye include dyes classified in the color index into acid dyes, food dyes, direct dyes, and reactive dyes.
Specific examples of acid dyes and food dyes include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289, C.I. I. Acid Blue 9, 29, 45, 92, 249, C.I. I. Acid Black 1, 2, 7, 24, 26, 94, C.I. I. Food Yellow 3, 4, C.I. I. Food Red 7, 9, 14, C.I. I. Food black 1, 2 etc. are mentioned.

Specific examples of direct dyes include C.I. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142, 144, C.I. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227, C.I. I. Direct Orange 26, 29, 62, 102, C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202, C.I. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 etc. are mentioned.
Specific examples of reactive dyes include C.I. I. Reactive. Black 3, 4, 7, 11, 12, 17, C.I. I. Reactive. Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67, C.I. I. Reactive. Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97, C.I. I. Reactive. Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95 etc. are mentioned. This reactive dye is preferable because of its high solubility, good color tone, and good water resistance.

Examples of the cationic dye include basic dyes and cationic dyes.
Specific examples of basic dyes include C.I. I. Basic Blue 9, 12, 26, C.I. I. Basic Red 2, 5, 9, C.I. I. Basic black 2 etc. are mentioned.
Specific examples of the cationic dye include G.I. Yellow GL 200, Red BL 200 R-46, Blue GRL-NB41, etc. are mentioned.

Examples of the pigment include inorganic pigments and organic pigments.
Examples of inorganic pigments include white pigments such as titanium oxide, zinc oxide, and barium sulfate, and black pigments such as iron oxide. Further, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method may be used.
Organic pigments include azo pigments (including azo lakes, 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, quinofullerone pigments, etc.), dye chelates (for example, basic dye chelates, acidic dye chelates, etc.), nitro pigments, nitroso pigments, aniline black and the like.

  More specifically, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 138, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 [Permanent Red 2B (Ba)], 48: 2 [Permanent Red 2B (Ca)], 48 : 3 [permanent red 2B (Sr)], 48: 4 [permanent red 2B (Mn)], 49: 1, 52: 2, 53: 1, 57: 1 (brilliant carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G Lake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, . I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue E), 16, 17: 1, 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

When an aqueous ink containing a pigment is used as a colorant, for example, carbon black having a carboxyl group introduced by an oxidation reaction, a radical generated from a diazonium salt containing a carboxyl group or a sulfonic acid group, and carbon black, phthalocyanine, quinacridone Self-dispersing pigments that have been reacted with pigments such as, self-dispersing pigments that have been reacted with radical initiators containing carboxyl groups or sulfonic acid groups, and pigments such as carbon black, phthalocyanine, quinacridone, etc. Preference is given to pigments in which ionic groups, in particular carboxyl groups, are covalently bonded, such as self-dispersing pigments reacted with acid anhydrides.
These pigments maintain an extremely stable dispersion state in a liquid medium mainly composed of water, and are excellent in storage stability and clogging resistance of water-based ink.

The pigment dispersed with an anionic dispersant or a cationic dispersant is preferably dispersed with a polymer dispersant having an anionic group or a polymer dispersant having a cationic group.
Examples of the polymeric dispersant having an anionic group include polyacrylic acid and a salt thereof, polymethacrylic acid and a salt thereof, an acrylic acid-acrylonitrile copolymer and a salt thereof, an acrylic acid-alkyl acrylate copolymer, and Salt thereof, styrene-acrylic acid copolymer and salt thereof, styrene-methacrylic acid copolymer and salt thereof, styrene-acrylic acid-acrylic acid alkyl ester copolymer and salt thereof, styrene-methacrylic acid-acrylic acid alkyl ester Copolymer and salt thereof, styrene-α-methylstyrene-acrylic acid copolymer and salt thereof, styrene-α-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymer and salt thereof, styrene-maleic acid copolymer Polymers and salts thereof, vinylnaphthalene-maleic acid copolymers and salts thereof, vinyl acetate Nyl-ethylene copolymer and its salt, vinyl acetate-crotonic acid copolymer and its salt, vinyl acetate-acrylic acid copolymer and its salt, β-naphthalenesulfonic acid formalin condensate and the like.
These polymer dispersants having an anionic group may be used in the form of an acid, but alkali metal salts such as sodium, potassium and lithium may be used.
Moreover, an aliphatic amine salt etc. are mentioned as an example of the polymer dispersing agent which has a cationic group.

Anionic surfactants are also preferably used as pigment dispersants.
Specific examples include oleic acid and salts thereof, lauric acid and salts thereof, behenic acid and salts thereof, stearic acid and salts thereof, other fatty acids and salts thereof, dodecylsulfonic acid and salts thereof, decylsulfonic acid and salts thereof, Other alkyl sulfonic acids and salts thereof, alkyl sulfates such as lauryl sulfate and oleyl sulfate, dodecylbenzene sulfonic acid and salts thereof, lauryl benzene sulfonic acid and salts thereof, other alkyl benzene sulfonic acids and salts thereof, dioctyl sulfo Succinic acid and its salt, dihexylsulfosuccinic acid and its salt, other dialkylsulfosuccinic acid and its salt, naphthylsulfonic acid and its salt, naphthylcarboxylic acid and its salt, other aromatic anionic surfactants, polyoxy Ethylene alkyl ether acetate, polyoxye Alkylether phosphates, polyoxyethylene alkyl ether sulfonates, fluorinated alkyl carboxylic acids and salts thereof, fluorine-based anionic surfactant such as a fluorinated alkyl sulfonic acid and its salts.

  The particle diameter of the pigment in the water-based ink is not particularly limited, but it is preferable to use a pigment ink having a particle diameter having a maximum frequency of 20 to 150 nm in terms of the maximum number. When the particle diameter exceeds 150 nm, not only the pigment dispersion stability as the water-based ink is lowered, but also the discharge stability of the water-based ink is lowered, and the image quality such as the image density is lowered, which is not preferable. On the other hand, when the particle size is less than 20 nm, the storage stability of the water-based ink, the ejection characteristics from the head are good, and high image quality can be obtained. However, it is not preferable to disperse to such a fine particle size because the dispersion operation and classification operation become complicated and it is difficult to reduce the cost of the water-based ink.

The colored emulsion is a colorant in which colored resin fine particles are suspended.
The colored resin fine particles are those obtained by coloring styrene-acrylic resin, polyester resin, polyurethane resin or the like with an oily dye, a disperse dye or a pigment. By forming the portion corresponding to the fine particle shell with a hydrophilic resin such as polyacrylic acid or polymethacrylic acid, for example, an aqueous ink in which anionic colored fine particles are suspended in a liquid medium mainly composed of water can be obtained. . A similar water-based ink can also be obtained by suspending the portion corresponding to the fine particle shell with an ionic surfactant such as a reactive surfactant. The colored emulsion may be nonionic.

Water-based ink uses water as the main liquid solvent, but uses water-soluble organic solvent as a wetting agent to make the water-based ink the desired physical properties or to prevent clogging of the head nozzle due to drying of the water-based ink. It is preferable.
The water-soluble organic solvents are used alone or in combination.
Although there is no restriction | limiting in particular in content of a water-soluble organic solvent, 1 to 60 weight% of the whole water-based ink is preferable, and 5 to 30 weight% is still more preferable.

  Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2,4-butanetriol Polyhydric alcohols such as 1,2,3-butanetriol and petriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono Polyhydric alcohol alkyl ethers such as chill ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; N- Nitrogen-containing heterocyclic compounds such as methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide, N-methylformamide, N, N- Amides such as dimethylformamide; Amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine; dimethyl Sulfur-containing compounds such as sulfoxide, sulfolane, thiodiethanol; propylene carbonate, ethylene carbonate, γ-butyrolactone, and the like.

In addition to the above materials, the water-based ink may contain additives such as a pH adjuster, a viscosity adjuster, a preservative, and an antioxidant.
Examples of the pH adjuster include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, Examples thereof include alkali metal carbonates such as sodium carbonate and potassium carbonate, amines such as diethanolamine and triethanolamine, boric acid, nitric acid, sulfuric acid and acetic acid.
The physical properties of the water-based ink are preferably in the range of pH 6-12, surface tension 10-60 mN / m, and viscosity 1-20 mPa · s around 25 ° C.

<Image forming apparatus>
FIG. 2 is a schematic view of an example of an image forming apparatus for carrying out the image forming method of the present invention.
The image forming apparatus 100 is an ink jet printer capable of forming a full-color image, and performs an image forming process based on an image signal corresponding to image information received from the outside. In addition to plain paper generally used for copying and the like, this apparatus can form an image on any of OHP sheets, cards, cardboard and other thick paper, envelopes and the like. 2 shows a single-sided image forming apparatus capable of forming an image on one side of a sheet S as a recording medium, but a double-sided image forming apparatus capable of forming an image on both sides of the sheet S may be used.

The image forming apparatus 100 includes recording heads 61Y, 61M, 61C, and 61BK that discharge water-based inks that can form images corresponding to yellow, magenta, cyan, and black. These recording heads are disposed at positions facing a guide plate 39 disposed at a substantially central portion of the main body 99 of the apparatus. The recording heads 61Y, 61M, 61C, and 61BK are arranged in this order from the upstream side in the paper conveyance direction, and image formation on the paper S is directly performed in the water-based ink ejection unit 53. Thus, this apparatus is a direct image forming apparatus.
The recording heads 61Y, 61M, 61C, and 61BK are provided in the ink ejection devices 60Y, 60M, 60C, and 60BK, which are yellow (Y), magenta (M), cyan (C), and black (BK) image forming units, respectively. ing. Each of the recording heads 61Y, 61M, 61C, 61BK is a line head provided in the ink ejection devices 60Y, 60M, 60C, 60BK in a form in which a plurality of recording heads 61Y, 61M, 61C, 61BK are arranged in parallel in the direction perpendicular to the paper surface of FIG. . In the figure, the case where the recording heads of four colors, which are basic colors, are shown, but recording heads of other colors may be provided.

The image forming apparatus 100 includes a carriage 62 as a head support that integrally supports the recording heads 61Y, 61M, 61C, and 61BK, a CPU that controls the overall operation of the image forming apparatus 100, a memory, and the like (not shown). A control unit 98 serving as a unit and an environment detection sensor 35 that detects an environmental temperature and an environmental humidity at which image formation is performed in the image forming apparatus 100 and inputs the detected environmental temperature and environmental humidity to the control unit 98 are provided.
The ink ejection devices 60Y, 60M, 60C, and 60BK and the control boards (not shown) of the recording heads 61Y, 61M, 61C, and 61BK provided in the control unit 98 constitute a printing unit.

The image forming apparatus 100 is a paper transport unit (not shown) that transports the paper S. A large number of paper S can be stacked, and only the topmost paper S among the stacked paper S is fed toward the transport unit. The paper feed unit 20 has a paper discharge tray 25 on which a large number of image-formed (printed) paper S conveyed by the conveyance unit can be stacked.
The transport unit temporarily transports the paper S fed from the paper feed unit 20 toward the printing unit, temporarily stops the paper S transported by the transport roller 32, and has a predetermined timing described later. In response to this, a registration roller 34 that feeds the paper S once stopped to the discharge unit 53 is provided.
The paper feed unit 20 is a paper feed tray 21 on which a large number of sheets S can be stacked, and a feed roller that feeds only the uppermost paper S among the papers S stacked on the paper feed tray 21 toward the transport unit. The paper feed roller 22, the paper feed tray 21, the housing 23 supporting the paper feed roller 22, and the paper feed roller 22 are rotationally driven so as to match the discharge timing of the water-based ink in the heads 61 Y, 61 M, 61 C, 61 BK. A motor or the like is provided as drive means (not shown) for feeding S.

In addition, the image forming apparatus 100 is disposed on the upstream side of the discharge unit 53 in the sheet conveyance direction so as to face the guide plate 39, and includes an applying device 73 as an applying unit that applies the processing liquid to the sheet S. Have. The applying device 73 functions as a processing liquid application unit that contacts the paper S and applies the processing liquid. The applying device 73 is a coating liquid 74 as a processing liquid coating member that contacts the paper S at this position to apply the processing liquid, and a processing liquid supply unit that stores the processing liquid and supplies the processing liquid to the coating roller 74. A treatment liquid tank 75 is provided.
The application roller 74 has at least a peripheral surface formed of an elastic member, and is provided in a state where a part thereof is immersed in the processing liquid stored in the processing liquid tank 75. The application roller 74 applies the processing liquid to the paper S with a width corresponding to the image formable region in the main scanning direction, that is, the direction perpendicular to the paper surface in FIG.
The applying device 73 may include a drive source such as a motor that drives the application roller 74 to rotate in the same direction as the sheet conveyance direction at a position facing the guide plate 39. The control unit 98 controls a configuration in which driving is controlled in the applying device 73 such as the driving source.
The treatment liquid application member is not limited to a member that performs roller application such as the application roller 74 as long as it applies the treatment liquid by contacting the paper S, and a wire bar, a flade coater, a foam impregnated with the treatment liquid, or the like. It may be.

The carriage 62 is integral with the heads 61Y, 61M, 61C, 61BK and is detachable from the main body 99. This is because the heads 61Y, 61M, 61C, 61BK can be replaced with new ones when deterioration or the like occurs, and maintenance is facilitated. The heads 61Y, 61M, 61C, and 61BK are also detachable from the main body 99 independently so that they can be replaced with new ones when deterioration or the like occurs and maintenance is facilitated. This facilitates replacement work and maintenance work.
The ink ejection devices 60Y, 60M, 60C, and 60BK have substantially the same configuration except for the color and composition of the water-based ink used. A plurality of heads 61Y, 61M, 61C, 61BK are arranged in parallel in the main scanning direction in the ink ejection devices 60Y, 60M, 60C, 60BK. Therefore, the ink ejection devices 60Y, 60M, 60C, 60BK and the image forming apparatus 100 are of a full line type.

The ink ejection devices 60Y, 60M, 60C, and 60BK include ink cartridges 81Y, 81M, 81C, and 81BK that contain water-based inks of the respective colors supplied to the plurality of heads 61Y, 61M, 61C, and 61BK. A supply pump (not shown) for pumping and feeding toward 61M, 61C, and 61BK, and a distributor that distributes and supplies the water-based ink supplied by the supply pump to each head 61Y, 61M, 61C, and 61BK A tank (not shown), an ink amount detection sensor (not shown) which is a water-based ink amount detecting means for detecting the water-based ink amount in order to detect a shortage of the water-based ink amount in the distributor tank, an ink cartridge 81Y, Aqueous water between 81M, 81C, 81BK and distributor tank A pipe (not shown) that forms a feeding path for the ink together with a pump, and a pipe (not shown) that forms a feeding path for aqueous ink between the distributor tank and each head 61Y, 61M, 61C, 61BK. Not shown).
The ink cartridges 81Y, 81M, 81C, 81BK are replaced with a new one when the water-based ink in the interior is consumed and the remaining amount is low or when the ink cartridge is used up. It is removable. The ink cartridges 81Y, 81M, 81C, 81BK function as water-based ink cartridges as main tanks.

  The operation of the pump is controlled by the control unit 98, and the aqueous ink stored in the ink cartridges 81Y, 81M, 81C, 81BK is supplied to the heads 61Y, 61M, 61C, 61BK. Specifically, the pump is stopped when the discharge of water-based ink by the heads 61Y, 61M, 61C, 61BK is stopped on condition that the ink amount detection sensor detects that the amount of water-based ink in the distributor tank is insufficient. Driven by. By this driving, the aqueous ink in the ink cartridges 81Y, 81M, 81C, 81BK is supplied to a distributor tank which is an aqueous ink supply unit. This driving is continued until such a shortage is no longer detected. That is, the control unit 98 functions as a water-based ink supply control unit. The control unit 98 also controls driving of other components driven in the image forming apparatus 100.

Each of the heads 61Y, 61M, 61C, 61BK has a nozzle plate (not shown), a minute nozzle (not shown) formed on the nozzle plate, and water-based ink droplets formed on the nozzle side on the water-based ink ejection side. And a piezo-type movable actuator (not shown) that is driven on the basis of an image signal for discharging and landing on the paper S.
This movable actuator applies a pressure to the aqueous ink in the liquid chamber by the displacement of the piezo element, and discharges the aqueous ink from the nozzle. However, the movable actuator may be another type of movable actuator.
Each of the heads 61Y, 61M, 61C, 61BK may use a heating film boiling method such as a thermal method in which the water-based ink in the liquid chamber is pressurized with bubbles generated by heater heating and the water-based ink is discharged from the nozzle. .
In any case, each of the heads 61Y, 61M, 61C, and 61BK is driven according to the image signal, and forms an image by applying water-based ink to the paper S. A number of nozzles are provided in each of the heads 61Y, 61M, 61C, 61BK.

The image forming apparatus 100 includes a pressure application unit 70 as a pressure application unit. However, the pressure application unit 70 can be omitted.
The pressure application unit 70 is disposed on the downstream side of the discharge unit 53 and on the upstream side of the paper discharge tray 25 in the transport direction of the paper S. The pressure application unit 70 includes pressure rollers 71 and 72 that are in pressure contact with each other, and a motor (not shown) that rotationally drives the pressure roller 71 and rotates the pressure roller 72 following the pressure roller 71. ing. The pressure application unit 70 is configured to pass the paper S to which the water-based ink is applied in the discharge unit 53 between the pressure rollers 71 and 72.

In the image forming apparatus 100 having such a configuration, one sheet S fed from the sheet feeding unit 20 is fed toward the applying device 73 in response to the input of a predetermined signal for starting image formation. After the sheet S passes through the transport roller 32, the application liquid is applied by the applying device 73 to the image-formable region on the side to which the water-based ink is applied in the discharge unit 53. Next, the sheet S is supplied to the discharge unit 53 at a timing by the registration roller 34. Then, in the process of passing through the ejection unit 53, the water-based ink is ejected from each of the heads 61Y, 61M, 61C, and 61BK to the image formable region where the processing liquid of the paper S is applied.
Each of the image forming apparatuses 100 described above employs a pre-coating configuration in which the processing liquid is applied to the paper S by the applying device 73, and then water-based ink is ejected and landed by the heads 61Y, 61M, 61C, and 61BK. doing.

  Although an example of the image forming apparatus has been described above, other types of image forming apparatuses may be used. That is, the image forming apparatus may be a copying machine, a single facsimile machine, or a multifunction machine such as these, a multifunction machine such as a monochrome machine related to these, or an image forming apparatus used for forming an electric circuit. Further, it may be an image forming apparatus used for forming a predetermined image in the biotechnology field. Further, the intermediate transfer member may be in the form of an endless belt instead of a roller. The number of heads is increased or decreased according to the use of the image forming apparatus, and may be one or more. When there are a plurality of heads, the number of heads is not limited to four as in the example of FIG. 2, and a head that discharges more types of water-based inks, for example, light-colored water-based inks such as light cyan and light magenta may be provided. Further, in the direct image forming apparatus, the sheet may be conveyed by an endless belt-like member.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these Examples. In the examples, “%” is “% by weight”.

[Preparation of treatment liquids 1 to 8]
The materials of the following prescription were mixed and stirred to prepare treatment liquids 1 to 8.

<Treatment liquid 1> (Introducing an acetyl group as a protective group)
Acetic anhydride: 4.2%
N, N-dimethyl-4-aminopyridine: 0.1%
・ Pyridine: 95.7%

<Treatment solution 2> (Introducing an acetal group as a protecting group)
・ 2,2-Dimethoxypropane: 84.3%
・ Camphorsulfonic acid: 2.5%
・ Dichloromethane: 13.2%

<Treatment solution 3> (Introducing a methyl group as a protecting group)
・ Methyl iodide: 15.0%
-Potassium carbonate: 33.0%
Acetone: 52.0%

<Treatment solution 4> (Introducing a methoxymethyl group as a protecting group)
・ Chloromethyl methyl ether: 8.0%
・ Sodium hydride: 4.5%
Tetrahydrofuran: 87.5%

<Treatment solution 5> (Introducing a benzyl group as a protecting group)
・ Benzyl chloride: 11.6%
・ Sodium hydride: 3.7%
Tetrahydrofuran: 84.7%

<Treatment liquid 6> (Introducing a p-methoxybenzyl group as a protecting group)
P-methoxybenzyltrichloroacetimidate: 4.2%
・ Dichloromethane: 95.8%

<Treatment solution 7> (Introducing a silyl group as a protective group)
-Chloride-t-butyldimethylsilane: 4.4%
-Imidazole: 4.2%
N, N-dimethylformamide: 91.4%

<Treatment solution 8> (Introducing a tetrahydropyranyl group as a protective group)
Dihydropyran: 30.5%
-Pyridinium p-toluenesulfonate: 4.4%
・ Dichloromethane: 65.1%

[Preparation of black aqueous ink]
After mixing and stirring the materials of the following formulation, the pH was adjusted to 9.1 with a 5% aqueous solution of lithium hydroxide, and pressure filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain a black aqueous ink.
<Ink prescription>
-Sulfonic acid group-bonded carbon black pigment dispersion: 35.0%
(CAB-O-JET-200, solid content 20%,
Cabot Specialty Chemicals, Inc.)
・ 2-Pyrrolidone: 10.0%
・ Glycerin: 14.0%
Propylene glycol monobutyl ether: 0.9%
・ Soda dehydroacetate: 0.1%
・ Distilled water: 40.0%

Examples 1-8, Comparative Example 1
<Treatment liquid application>
The treatment liquids 1 to 8 were applied to plain paper (My Paper, manufactured by Ricoh Co., Ltd.) with a roller so that the coating amount was 100 mg / A4, then dried, and used for image formation in Examples 1 to 8. Further, plain paper to which no treatment liquid was applied was used for image formation in Comparative Example 1.

<Image formation>
The black aqueous ink was applied as follows.
(1) Two rectangular holes of 2 cm × 5 cm are made in the PET film.
(2) Ordinary paper (My Paper, manufactured by Ricoh Co., Ltd.) cut to a size of 2 cm × 5 cm is set in one hole, and treated with the processing solution cut to a size of 2 cm × 5 cm in the other hole Load paper.
(3) Using a bar coater, apply so that the thickness of the black aqueous ink is 4 μm.

For each of the plain papers of Examples and Comparative Examples on which images were formed as described above, the degree of paper curl after 3 minutes was evaluated according to the following criteria. The results are summarized in Table 1.

<Evaluation criteria>
○: Paper curl is less than 20 mm ×: Paper curl is 20 mm or more

From Table 1 above, it can be seen that no curling occurs according to the image forming method of the present invention.
The image forming means used in the above embodiment is not an ink jet method but an application by a bar coater using a PET film. However, in view of the anti-curl mechanism of the present invention described with reference to FIG. However, it is clear that the same effect can be obtained.

S: paper 20: paper feed unit 21: paper feed tray 22: paper feed roller 23: housing 25: paper discharge tray 32: transport roller 34: registration roller 35: environment detection sensor 39: guide plate 53: ejection of water-based ink Section 60Y: Yellow ink ejection device 60M: Magenta ink ejection device 60C: Cyan ink ejection device 60BK: Black ink ejection device 61Y: Head for yellow ink 61M: Head for magenta ink 61C: Head for cyan ink 61BK: Head for black ink 62 : Carriage 70: Pressure application unit 71: Pressure roller 72: Pressure roller 73: Applying means 74: Application roller 75: Treatment liquid tank 81Y: Yellow ink cartridge 81M: Magenta ink cartridge 81C: Cyan ink cartridge 8 BK: Black ink cartridge 98: processing liquid amount control unit 99: body 100: Image forming apparatus

JP 2004-276551 A JP 2008-120072 A JP 2011-251791 A

Claims (6)

  A treatment liquid application step for applying a treatment liquid onto a paper-made recording medium; and an aqueous ink application step for applying an aqueous ink following the treatment liquid application step. An image forming method comprising introducing a protecting group.   The image forming method according to claim 1, wherein the water-based ink application step comprises an ink jet recording method in which ink is ejected by applying thermal energy or mechanical energy to the water-based ink.   The protective group is any one of an acetyl group, an acetal group, a methyl group, a methoxymethyl group, a benzyl group, a p-methoxybenzyl group, a silyl group, and a tetrahydropyranyl group. The image forming method described.   A processing liquid applying unit that applies the processing liquid to the recording medium and a head that discharges the aqueous ink are provided. After the processing liquid is applied to the recording medium by the processing liquid applying unit, the aqueous ink is discharged by the head. The image forming apparatus used for the image forming method according to claim 1, wherein   Further, a processing liquid drying unit is provided, the processing liquid is applied to the recording medium by the processing liquid applying unit, the processing liquid is dried by the processing liquid drying unit, and then the aqueous ink liquid is discharged by the head. The image forming apparatus according to claim 4.   The processing liquid used for the image forming method according to claim 1, comprising acetic anhydride and pyridine.

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