JP2006239915A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method which ensures good ejection stability when inkjet recording is performed by using an ink composition for inkjet recording, containing each of a self-dispersion pigment and a resin particle in a high concentration. <P>SOLUTION: This inkjet recording method is characterized by using the ink composition for inkjet recording, containing 6 wt% or more of the self-dispersion pigment and 3 wt% or more of the resin particles, and by using an inkjet recording apparatus which has a recording-head capping means equipped with an ink absorber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording method.

  An ink jet recording apparatus is used for many printings including color printing because noise during printing is relatively small and small dots can be formed with high density. Such an ink jet recording apparatus includes an ink jet recording head that receives ink supplied from an ink cartridge, and a paper feeding unit that moves the recording paper relative to the recording head. Recording is performed by ejecting ink droplets onto the recording paper while moving in the width direction.

  The recording head mounted on the ink jet recording apparatus performs printing by ejecting the ink pressurized in the pressure generating chamber onto the recording paper as ink droplets from the nozzle opening, thereby evaporating the ink solvent from the nozzle opening. There is inherently a problem that printing failure occurs due to an increase in ink viscosity, solidification of ink, adhesion of dust, and mixing of air bubbles into the ink flow path.

  For this reason, in this type of ink jet recording apparatus, capping means for sealing the nozzle forming surface of the recording head during non-printing (during rest) and cleaning by wiping the nozzle forming surface as necessary A wiping member is provided.

  This capping unit functions as a lid for preventing ink drying of the nozzle opening at the time of printing suspension, and suppresses clogging due to drying of the nozzle opening of the recording head. One of the purposes is to ensure the reliability. Further, the capping unit is configured to force the ink to be sucked and discharged from the nozzle opening by the negative pressure from the suction pump as the negative pressure generating unit in a state where the nozzle forming surface is sealed. It also has a function as a cleaning means for eliminating clogging or ink ejection failure due to air bubbles entering the ink flow path.

  It is also known to enhance the function as a lid for preventing ink drying of the nozzle opening by storing an ink absorbing material inside the capping means (Patent Document 1, etc.). Since the ink absorbing material is formed of a porous foam, the internal space of the capping means in a state where the nozzle forming surface is sealed can be maintained in a wet state.

A typical aspect of the capping means provided with such an ink absorbing material will be described with reference to FIG.
FIG. 1 is a schematic partial sectional view of a cap part 1 (cross section) as a capping unit and a recording head part 2 (partial cross section) sealed by the cap part 1. The cap unit 1 includes a cap holder 11, a closing member 12 housed in the cap holder 11, an ink absorbing material 13 housed in a recess provided in the closing member 12, and a protruding part for fixing and holding the ink absorbing material 13. 14 and the like. The closing member 12 has a storage portion 12a and a protruding wall portion 12b, and the storage portion 12a stores the ink absorbing material 13 in a recess provided in a central portion. Further, the protruding wall portion 12b is in airtight contact with the surface 22 of the recording head portion 2 at the tip portion 12c, and the entire region including the nozzle openings 21 provided on the surface 22 of the recording head portion 2. Is sealed from 4 rounds. In the schematic diagram of FIG. 1, five nozzle openings 21 are shown, and all of the five nozzle openings 21 are sealed by the protruding wall portion 12 b of the closing member 12. Moreover, the nozzle opening is not provided in the outer side area | region 22a of the area | region sealed with the protrusion wall part 12b of the closure member 12. As shown in FIG. Further, in FIG. 1, the direction in which ink droplets are ejected from each nozzle opening 21 is indicated by an arrow A.

  In the capping means as shown in FIG. 1, the inner space of the capping means is wetted by sealing the nozzle forming surface in a state where the ink is held in a wet state by the ink absorbing material made of porous foam. The ink can be prevented from drying at the nozzle opening.

  On the other hand, in addition to moisture, polyhydric alcohols such as glycerin or diethylene glycol are generally mixed in the ink jet recording ink. Since these polyhydric alcohols have the property of absorbing moisture in the air, the use of these polyhydric alcohols as ink solvents suppresses ink thickening and solidification, and is mainly used for recording. Care is taken to prevent clogging of fine nozzle openings in the head.

  However, if an ink jet recording apparatus that uses ink containing a humectant (polyhydric alcohol) is provided with a capping unit that includes the ink absorbing material, the capping unit is in an open state when printing is performed. At the same time, moisture evaporates one after another from the ink absorbing material, whereas the humectant (polyhydric alcohol) remains in the ink absorbing material. As a result, the ratio of the humectant (polyhydric alcohol) in the ink held by the ink absorbing material gradually increases as the usage time of the recording apparatus elapses.

  As described above, when the ink is held on the ink absorbing material in a state where the humectant composition ratio is increased, when the capping unit is in the sealed state, the humectant is contained in the internal space of the recording head in the sealed environment. Rather, it acts to absorb moisture and promotes drying of the ink at the nozzle openings of the recording head. That is, it is necessary to consider the use of an ink absorbing material depending on the type and composition of the ink to be used, and the ink absorbing material may prevent the ink from drying at the nozzle opening or vice versa.

Japanese Patent Publication No. 3-43066

  As a result of studying the case where printing is performed by a recording apparatus including the capping unit using an ink composition for ink jet recording containing a high concentration of a self-dispersing pigment and resin particles, the present inventors have found an ink absorbing material. It has been found that the discharge stability becomes extremely good when a capping means having the above is used.

Accordingly, the present invention is an ink jet recording method using an ink composition for ink jet recording containing 6% by weight or more of a self-dispersing pigment and 3% by weight or more of resin particles,
The present invention relates to the above-described ink jet recording method, characterized in that an ink jet recording apparatus having a recording head capping unit provided with an ink absorbing material is used.

In a preferred embodiment of the method of the present invention, an ink composition having a self-dispersing pigment content of 6% to 15% by weight is used.
In another preferred embodiment of the method of the present invention, an ink composition having a resin particle content of 3 wt% to 15 wt% is used.
In still another preferred embodiment of the method of the present invention, the ink absorbing material comprises a porous foam or a fibrous porous body.
The present invention also relates to a recorded matter formed by the ink jet recording method.

  According to the method of the present invention, when ink-jet recording is performed using an ink composition for ink-jet recording containing a high concentration of a self-dispersing pigment and resin particles, when a capping means equipped with an ink absorbing material is used, Good ejection stability can be obtained.

The self-dispersing pigment used in the method of the present invention has one or more functional groups selected from the group consisting of —COOH, —CHO, —OH, —SO ₃ H, and salts thereof on the surface of the pigment ( The pigment is treated so as to have a dispersibility-imparting group, and can be uniformly dispersed in the water-based ink composition without separately adding a dispersant. The term “dispersed” as used herein refers to a state in which the self-dispersing pigment is stably present in water without a dispersant, and not only in a dispersed state but also in a dissolved state. Shall also be included. The ink composition containing the self-dispersing pigment has higher dispersion stability than the normal ink composition containing a non-self-dispersing pigment and a dispersant other than the self-dispersing pigment, and the ink composition Since the viscosity of the composition becomes moderate, it is possible to contain a larger amount of pigment, and it is possible to form images such as letters and figures with excellent color developability, especially on plain paper. Furthermore, since an ink composition containing a self-dispersing pigment does not cause a decrease in fluidity even when a penetrant (described later) effective in improving print quality is blended, the penetrant is used in combination. As a result, the print quality can be improved.

  As the pigment capable of forming a self-dispersing pigment, the same pigments as those used in ordinary ink jet recording ink compositions are used. For example, carbon black, azo lake, insoluble azo pigment, condensed azo pigment, chelate azo pigment, phthalocyanine pigment Perylene pigment, perinone pigment, quinacridone pigment, thioindigo pigment, isoindolinone pigment, quinofullerone pigment, dioxazine pigment, anthraquinone pigment, nitro pigment, nitroso pigment, organic pigments such as aniline black, titanium white, zinc white, lead white, carbon Mention may be made of inorganic pigments such as black, bengara, vermilion, cadmium red, yellow lead, ultramarine, cobalt blue, cobalt violet, and zinc chromate. Further, any pigment that is not described in the color index can be used as long as it can be dispersed in the aqueous phase. Of these, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, dioxazine pigments, and anthraquinone pigment systems are used. It is preferable. The “pigment” means a particulate solid that is usually insoluble in water, solvent, oil, or the like.

  In order to prepare a self-dispersing pigment, a functional group or a molecule containing a functional group is coordinated to the surface of the pigment or a chemical bond such as a graft is formed by physical treatment or chemical treatment such as vacuum plasma. It can be obtained. For example, it can be obtained by the method described in JP-A-8-3498. Moreover, as a self-dispersion type pigment, it is also possible to use a commercially available product. Preferred examples include “Microjet CW1” manufactured by Orient Chemical Co., Ltd. and “CAB-O-JET 200” manufactured by Cabot Corporation. Or “CAB-O-JET 300”.

The self-dispersing pigment can be prepared, for example, as follows. As an example of a method for preparing a self-dispersing pigment, embodiments of the pigment surface oxidation treatment and sulfonation treatment will be described below.
A pigment is added to the solvent, and this is subjected to high-speed shearing dispersion with a high-speed mixer or the like, or impact-dispersed with a bead mill or jet mill to obtain a slurry-like pigment dispersion. While slowly stirring the pigment dispersion, a treatment agent containing sulfur (sulfamic acid, fuming sulfuric acid, sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, amidosulfuric acid, etc.) is added, and the pigment dispersion is heated to 60 to 200 ° C. The dispersibility-imparting group is introduced into the pigment surface by treatment. After removing the solvent from the pigment dispersion, the treatment agent containing sulfur is removed by repeating washing with water, ultrafiltration, reverse osmosis, centrifugation, and / or filtration to obtain a self-dispersing pigment.

  The self-dispersing pigment preferably has an average particle size of 10 to 300 nm, and more preferably 40 to 150 nm, from the viewpoint of improving the storage stability of the ink and preventing nozzle clogging.

  The content of the self-dispersing pigment is 6% by weight or more, preferably 6 to 15% by weight, more preferably 6 to 10% by weight, based on the total weight of the ink composition used in the present invention. When the content of the self-dispersing pigment is less than 6% by weight, a sufficient OD value cannot be obtained. A content of the self-dispersing pigment is preferably 15% by weight or less from the viewpoint of the stability of the ink composition.

  Examples of the resin that can be applied to the resin particles used in the method of the present invention include acrylic resin, urethane resin, epoxy resin, and polyolefin resin, but are not particularly limited. These resins are used singly or in combination when used, and in the case of using a plurality of resins, at least one of them is an emulsion of resin particles obtained by emulsion polymerization of unsaturated monomers (for example, so-called It is preferably blended in the ink composition in the form of “acrylic emulsion”). The reason is that the resin particles may be insufficiently dispersed even if they are added to the ink composition as they are, so that the emulsion form is preferable for the production of the ink composition. The emulsion is preferably an acrylic emulsion from the viewpoint of storage stability of the ink composition.

  An emulsion of resin particles (such as an acrylic emulsion) can be obtained by a known emulsion polymerization method. For example, it can be obtained by emulsion polymerization of an unsaturated monomer (such as an unsaturated vinyl monomer) in water containing a polymerization initiator and a surfactant.

  Examples of unsaturated monomers include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyl cyanide compounds generally used in emulsion polymerization. Examples thereof include monomers, halogenated monomers, olefin monomers, and diene monomers. Furthermore, specific examples include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate. Acrylic acid esters such as dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl Methacrylate, n-hexyl methacrylate, 2-ethyl Xyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, methacrylic esters such as phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, and vinyl esters such as vinyl acetate; vinyl such as acrylonitrile and methacrylonitrile Cyanides; halogenated monomers such as vinylidene chloride and vinyl chloride; simple aromatic vinyl such as styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene Forms; Olefins such as ethylene and propylene; Dienes such as butadiene and chloroprene; Vinyl ether, vinyl ketone, vinyl pyrrolidone Vinyl monomers such as; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; acrylamides such as acrylamide, methacrylamide and N, N′-dimethylacrylamide; 2-hydroxyethyl Examples include hydroxyl group-containing monomers such as acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and the like. These may be used alone or in admixture of two or more. it can.

  A crosslinkable monomer having two or more polymerizable double bonds can also be used. Examples of the crosslinkable monomer having two or more polymerizable double bonds include polyethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4-acryloxypropyloxyphenyl) propane, 2,2 ′ -Diacrylate compounds such as bis (4-acryloxydiethoxyphenyl) propane, triacrylate compounds such as trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate , Tetraacrylate compounds such as ditrimethylol tetraacrylate, tetramethylol methane tetraacrylate, pentaerythritol tetraacrylate, hexaacrylate compounds such as dipentaerythritol hexaacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol Dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol Dimethacrylate, , 2'-bis (4-methacryloxydiethoxyphenyl) propane, and the like, trimetholyl compounds such as trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, methylenebisacrylamide, and divinylbenzene. These can be used alone or in admixture of two or more.

  In addition to the polymerization initiator and surfactant used in the emulsion polymerization, a chain transfer agent, further a neutralizing agent, and the like may be used according to a conventional method. In particular, ammonia and inorganic alkali hydroxides such as sodium hydroxide and potassium hydroxide are preferred as the neutralizing agent.

  In the method of the present invention, the resin particles may be mixed with other components of the ink composition as fine particle powder. Preferably, the resin particles are dispersed in an aqueous medium to form an emulsion (polymer emulsion), and then the ink is used. It is preferably mixed with the other components of the composition.

In the ink composition for ink jet recording used in the method of the present invention, the content of the resin particles is 3% by weight or more, preferably 3 to 15% by weight, more preferably 3%, based on the total weight of the ink composition. -10% by weight.
When the content of the resin particles is less than 3% by weight, it becomes difficult to obtain a high OD value and sufficient fixability. When the content of the resin particles is 15% by weight or less, it is preferable from the viewpoint of ink jet proper physical properties and reliability (clogging, ejection stability, etc.).

  The resin particles preferably have an average particle size of 50 to 250 nm, more preferably 60 to 200 nm, from the viewpoint of dispersion stability in the ink composition. Moreover, as a resin particle, any of a single phase structure and a multiphase structure (core shell type) can be used.

  The resin particles are preferably blended as an emulsion in the ink composition used in the method of the present invention from the viewpoint of ink adjustment for adjusting uniform ink and ink stability.

  In the present specification, “resin particles” are those in which a resin insoluble in water is dispersed in a particle form in a dispersion medium mainly composed of water, or a resin insoluble in water is mainly dispersed in a dispersion medium composed mainly of water. It means what is dispersed in the form of particles, and further includes the dried product. In the present specification, the term “emulsion” is intended to include a solid / liquid dispersion called dispersion, latex, or suspension.

  The emulsion is preferably anionic from the viewpoint of improving the dispersion stability of the self-dispersing pigment described above. From the same point of view, when a pigment having a cationic surface (for example, one dispersed with a cationic group by surface treatment) is used, the emulsion is preferably cationic.

The emulsion can be produced, for example, as follows.
In a reaction vessel equipped with a dropping device, a thermometer, a water-cooled reflux condenser, and a stirrer, 100 parts of ion-exchanged water is added, and 0.2 part of a polymerization initiator is added while stirring at a temperature of 70 ° C. in a nitrogen atmosphere. . To this, a separately prepared monomer solution is dropped and subjected to a polymerization reaction to prepare a primary substance. Thereafter, at a temperature of 70 ° C., 2 parts of a 10% aqueous solution of a polymerization initiator is added to the primary substance and stirred. Further, a separately prepared reaction solution is added and stirred to cause a polymerization reaction. obtain. The polymerization reaction product is neutralized with a neutralizing agent and adjusted to have a pH of 8 to 8.5, and then filtered through a 0.3 μm filter to remove coarse particles, and resin particles are used as dispersoids. To obtain an emulsion.

  As the polymerization initiator, the same compounds as those used in normal radical polymerization are used. For example, potassium persulfate, ammonium persulfate, hydrogen peroxide, azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, Examples thereof include peracetic acid, cumene hydroperoxide, t-butyl hydroxy peroxide, paramentane hydroxy peroxide and the like. In particular, as described above, when the polymerization reaction is performed in water, a water-soluble polymerization initiator is preferable.

  Examples of the emulsifier used in the polymerization reaction include those generally used as an anionic surfactant, a nonionic surfactant or an amphoteric surfactant in addition to sodium lauryl sulfate.

  Examples of the chain transfer agent used in the polymerization reaction include t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, xanthogens such as dimethylxanthogen disulfide, diisobutylxanthogen disulfide, dipentene, indene, 1,4- Examples include cyclohexadiene, dihydrofuran, and xanthene.

  The ink composition used in the method of the present invention is usually a water-based ink composition containing water as a solvent, preferably ion-exchanged water.

  In addition, the ink composition used in the method of the present invention can also use an organic solvent in addition to water as a solvent. Such an organic solvent has compatibility with water, improves the penetrability of the ink composition into the recording medium and prevents clogging of the nozzles, and components in the ink composition such as a penetrant described later. Are preferable, for example, ethanol, methanol, butanol, propanol, isopropanol and other C1-C4 alkyl alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene Glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol Cole mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether Propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, Glycol ethers such as dipropylene glycol mono-iso-propyl ether, 2-pyrrolidone, Examples thereof include lumamide, acetamide, dimethyl sulfoxide, sorbite, sorbitan, acetin, diacetin, triacetin, sulfolane and the like, and one or more of these are preferably used in the ink composition used in the method of the present invention. It can be used in% by weight.

  The ink composition used in the method of the present invention preferably contains an acetylene glycol surfactant from the viewpoint of improving printing quality. Examples of such acetylene glycol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 3,6-dimethyl-4-octyne-3,6-diol. 3,5-dimethyl-1-hexyne-3ol, or substances obtained by adding an average of 1 to 30 ethyleneoxy groups or propyleneoxy groups to each of a plurality of hydroxyl groups in each of these substances. In addition, as the acetylene glycol surfactant, commercially available products can be used, and examples thereof include “Olfin E1010” and “Olfin STG” (both are trade names, manufactured by Nissin Chemical Industry Co., Ltd.). Can do. These 1 type (s) or 2 or more types can be used.

  The content of the acetylene glycol surfactant in the ink composition used in the method of the present invention is preferably 0.1 to 3% by weight, more preferably 0.5 to 1.5% by weight.

The ink composition used in the method of the present invention preferably contains a penetrating agent in order to further improve the fixability to a recording medium and to improve the abrasion resistance of images such as characters and figures to be recorded. Examples of such penetrants include diethylene glycol mono-n-butyl ether (DEGmBE), diethylene glycol mono-t-butyl ether (DEGMTBE), triethylene glycol mono-n-butyl ether (TEGmBE), propylene glycol mono-n-butyl ether (PGmBE). Dipropylene glycol mono-n-butyl ether (DPGmBE) and the following general formula (I):
RO- (PO) _m- (EO) _n- H (I)
(In the formula, R represents an alkyl group having 4 to 10 carbon atoms, PO represents a propyleneoxy group, and EO represents an ethyleneoxy group. M ≧ 1, n ≧ 0, m + n ≦ 20.)
1 type or 2 or more chosen from the group which consists of a compound represented by these is preferable, and DEGmBE, TEGmBE, and DPGmBE are especially preferable. In the general formula (I), m and n represent the presence in the system, and PO and EO may be added in blocks or randomly.

  The penetrant content is preferably 1 to 20% by weight in the ink composition used in the method of the present invention in that the penetrability and quick drying of the ink composition can be improved to effectively prevent the occurrence of ink bleeding. is there.

  In addition, the ink composition used in the method of the present invention contains a surfactant other than the acetylene glycol surfactant in order to improve the abrasion resistance of images such as characters and figures, similar to the penetrant. You can also Examples of such surfactants include, as amphoteric surfactants, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine. Polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, non-ionic surfactants such as polyoctyl polyaminoethylglycine and other imidazoline derivatives Ethers such as ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxy Tylene oleic acid, polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate, etc. Examples thereof include silicon-based surfactants such as esters and dimethylpolysiloxane, and other fluorine-containing surfactants such as fluorine alkyl esters and perfluoroalkyl carboxylates, and one or more of these are used. be able to.

  The ink composition used in the method of the present invention preferably contains a water-soluble glycol in order to prevent clogging of the nozzle and improve reliability. Examples of such water-soluble glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of 2000 or less, trimethylene glycol, isobutylene glycol, Divalent alcohols such as 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, glycerin, mesoerythritol, pentaerythritol, etc. And trivalent or higher alcohols, and one or more of these can be used.

  The content of the water-soluble glycol is preferably 1 to 30% by weight in the ink composition used in the method of the present invention.

  In addition, the ink composition used in the method of the present invention may contain a saccharide, an antifungal agent, and an antiseptic agent in order to prevent clogging of the nozzle, similarly to the water-soluble glycols.

  Examples of the saccharide include glucose, mannose, fructose, ribose, xylose, arabinose, lactose, galactose, aldonic acid, glucosose, maltose, cellobiose, sucrose, trehalose, maltotriose, alginic acid and salts thereof, cyclodextrins, and celluloses. One or more of these can be used in the ink composition used in the method of the present invention, preferably at 0 to 15% by weight.

  Examples of the antifungal agent / preservative include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3 -On (AVECIA's Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN) and the like, and one or more of these may be used in the ink composition used in the method of the present invention. Preferably, it can be used at 0.01 to 0.5% by weight.

  The ink composition used in the method of the present invention preferably contains a chelating agent such as EDTA from the viewpoint of ensuring reliability such as clogging prevention and ejection stability, and preferably in the ink composition used in the method of the present invention. It can be used at 0.01 to 0.5% by weight.

  When the surface of the self-dispersing pigment is anionic, the ink composition used in the method of the present invention preferably has a pH of 6 to 11 from the viewpoint of improvement in printing density and liquid stability. More preferably. In order to set the pH of the ink composition within the above range, as a pH adjuster, inorganic alkalis such as sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, triethanolamine, ethyldiethanolamine, diethylethanolamine, It is preferable to contain tertiary amines having 6 to 10 carbon atoms such as tripropanolamine. One or more pH adjusters can be used in the ink composition used in the method of the present invention, preferably at 0.01 to 2% by weight.

  The ink composition used in the method of the present invention may further contain various additives such as a surface tension adjusting agent, a viscosity adjusting agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, and an oxygen absorber as necessary. One or two or more of these can be used.

  The ink composition used in the method of the present invention can be prepared using a conventionally known apparatus such as a ball mill, a sand mill, an attritor, a basket mill, or a roll mill. In preparing the ink composition used in the method of the present invention, it is preferable to remove coarse particles. For example, particles (300 nm or more) are removed by filtering a mixture (ink) obtained by blending the above-described components with a filter such as a metal filter or a membrane filter. By performing such treatment, a highly reliable ink composition that does not clog the nozzle can be obtained.

  The ink composition used in the method of the present invention is not limited to the color type and the like, and various color ink compositions (cyan, magenta, yellow, light cyan, light magenta, dark yellow, red, green, blue, Orange, violet, etc.), black ink composition, light black ink composition and the like. In use, the ink composition used in the method of the present invention is used alone or as an ink set composed of a plurality of types thereof, or one or more types of ink compositions used in the method of the present invention and one type of other ink compositions or It can be used as an ink set comprising a plurality of types.

  The ink composition used in the method of the present invention is not particularly limited as a recording medium for forming the image, and can be applied to various recording media such as plain paper, inkjet special paper, plastic, film, metal and the like. be able to.

  According to the present invention, there is provided a recording method for forming an image on a recording medium using the ink composition described above. In one embodiment of the recording method of the present invention, printing is performed by ejecting the droplets of the ink composition described above by an inkjet recording method and attaching the droplets to a recording medium. By carrying out the recording method of the present invention, the ink composition can be ejected with high reliability, the print quality of the formed image is good, the OD value is high, the fixability is good, and the resistance is high. An image having excellent rubbing properties can be obtained.

  According to the present invention, there is also provided a recorded matter in which an image is formed on a recording medium using the ink composition described above. The recorded matter of the present invention has an image having good print quality, high OD value, good fixability and excellent abrasion resistance.

In the ink jet recording method of the present invention, an ink jet recording apparatus having a recording head capping unit provided with an ink absorbing material is used.
As the ink jet recording apparatus having the recording head capping means, a conventionally known apparatus can be used. For example, the ink jet recording apparatus having the capping means shown in FIG. 1 can be used.

  The ink absorbing material is not particularly limited as long as it is a material capable of holding ink in a wet state, and is a porous foam, for example, a synthetic resin foam (particularly, polyurethane foam) or a fibrous porous body (particularly, non-woven fabric). Woven fabric or woven fabric sheet). In addition, it is preferable that the closing member including the accommodating portion for accommodating the ink absorbing material and the protruding wall portion capable of hermetically sealing the surface of the recording head portion is made of an elastic material.

  In order to ensure that the surface of the ink absorbing material does not come into contact with the nozzle openings, for example, a suppressing member as described in JP 2000-62202 A can be provided on the surface of the ink absorbing material. Although not shown in the schematic diagram of FIG. 1, the closing member 12 is provided with an ink suction port for discharging the ink ejected by the pump to the outside of the cap portion 1. An opening can be provided that can communicate with or be blocked from the outside atmosphere.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

(1) Preparation of ink composition Each of the following blending components was mixed and stirred at the following blending amounts, filtered through a metal filter having a pore size of 5 μm, and degassed using a vacuum pump to prepare an ink composition. .
6% by weight pigment,
Emulsion A 4% by weight,
Emulsion B 1% by weight,
TEGmBE 3% by weight,
GL 5% by weight,
TEG 10% by weight,
1,2-HD 5% by weight,
1% by weight of TPA,
Olfin E1010 1% by weight,
Olfine STG 0.1% by weight,
EDTA 0.02% by weight,
Proxel XL2 0.3 wt%,
The amount of the ion-exchanged water is 100% by weight. The pigment is a self-dispersing pigment (“CAB-O-JET 300” (trade name) manufactured by Cabot Corporation; average particle size: 130 nm). Emulsion A and Emulsion B are both aqueous dispersions of resin particles in which the dispersion medium is water and the dispersoid is resin particles. The weight% of the emulsion represents the concentration as resin particles. Their preparation methods will be described later.

Abbreviations have the following meanings.
TEGmBE; triethylene glycol monobutyl ether GL; glycerin TEG; triethylene glycol 1,2-HD; 1,2-hexanediol TPA; tripropanolamine orphine E1010; acetylene glycol surfactant (Nisshin Chemical Co., Ltd.) Made)
Orphine STG: Acetylene glycol surfactant (manufactured by Nissin Chemical Industry Co., Ltd.)
EDTA; ethylenediaminetetraacetic acid sodium dihydrogen acetate (chelating agent)
Proxel XL2: Antifungal agent (Avisia Co., Ltd.)

(2) Production method of emulsion A A reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer was charged with 900 g of ion-exchanged water and 1 g of sodium lauryl sulfate, and the temperature was raised to 70 ° C. while purging with nitrogen under stirring. Warm up. Maintaining the internal temperature at 70 ° C., adding 4 g of potassium persulfate as a polymerization initiator, dissolving, and previously stirring 450 g of ion exchange water, 3 g of sodium lauryl sulfate, 20 g of acrylamide, 365 g of styrene, 545 g of butyl acrylate, and 30 g of methacrylic acid The emulsion prepared in addition to the chemical conversion was continuously dropped into the reaction solution over 4 hours. After completion of the dropwise addition, aging was performed for 3 hours. The obtained aqueous emulsion was cooled to room temperature, and then ion-exchanged water and an aqueous sodium hydroxide solution were added to adjust the solid content to 40% by weight and pH 8. The glass transition temperature of the resin particles in the obtained aqueous emulsion was −6 ° C. Tg is a value measured by differential thermal analysis using a thermal analyzer SSC5000 (manufactured by Seiko Electronics Co., Ltd.).

(3) Production method of emulsion B In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer, 900 g of ion-exchanged water and 1 g of sodium lauryl sulfate were charged, and the temperature was raised to 70 ° C. while purging with nitrogen under stirring. Warm up. Maintaining the internal temperature at 70 ° C., adding 4 g of potassium persulfate as a polymerization initiator, dissolving, and previously stirring 450 g of ion exchange water, 3 g of sodium lauryl sulfate, 20 g of acrylamide, 615 g of styrene, 295 g of butyl acrylate, and 30 g of methacrylic acid The emulsion prepared in addition to the chemical conversion was continuously dropped into the reaction solution over 4 hours. After completion of the dropwise addition, aging was performed for 3 hours. The obtained aqueous emulsion was cooled to room temperature, and then ion-exchanged water and an aqueous sodium hydroxide solution were added to adjust the solid content to 40% by weight and pH 8.
The glass transition temperature of the resin particles in the obtained aqueous emulsion was 36 ° C. Tg is a value measured by differential thermal analysis using a thermal analyzer SSC5000 (manufactured by Seiko Electronics Co., Ltd.).

<Example 1 and Comparative Example 1>
Regarding the ink composition prepared in the preceding item (1), an ink jet recording apparatus having a recording head capping means provided with an ink absorbing material (Example 1), and an ink jet recording apparatus having a recording head capping means not provided with an ink absorbing material. Using (Comparative Example 1), the ejection stability was evaluated based on the number of cleanings.
A printer (PX-V700; manufactured by Seiko Epson Corporation) was used as the ink jet printer of Example 1, and a printer (Stylus C80; manufactured by Seiko Epson Corporation) was used as the ink jet printer of Comparative Example 1.

The ejection stability evaluation based on the number of cleanings was performed by continuously printing solid and ruled line patterns in a 40 ° C. environment. A nozzle check was performed before continuous printing, and evaluation was started after confirming the fillability. After that, cleaning was performed each time as a recovery operation when there was a disorder due to missing dots or ink splattering or bending during printing. Determination was made based on the following criteria by the number of cleanings required for 100 pages of continuous printing in A4 size.
Evaluation A: Zero cleaning times.
Evaluation B: Number of cleanings 1 or 2 times.
Evaluation C: Number of cleanings is 3 times or more.
The evaluation results are shown in Table 1.

<Example 2 and Comparative Example 2>
Regarding the ink composition prepared in the preceding item (1), an ink jet recording apparatus having a recording head capping means provided with an ink absorbing material (Example 2) and an ink jet recording apparatus having a recording head capping means not provided with an ink absorbing material. Using (Comparative Example 2), the ejection stability was evaluated based on the capping time.
A printer (PX-V700; manufactured by Seiko Epson Corporation) was used as the ink jet printer of Example 2, and a printer (Stylus C80; manufactured by Seiko Epson Corporation) was used as the ink jet printer of Comparative Example 2.

The ejection stability evaluation by the capping time was carried out by printing A4 size solid and ruled line patterns in a 40 ° C. environment. A nozzle check was performed before printing, and evaluation was started after confirming the filling properties. After filling confirmation, after capping the head at the home position and sealing it, the printing stability (disturbance due to missing dots or ink scattering or bending) with respect to the time to start printing (= capping time) is as follows. Judgment based on.
Evaluation A: No disturbance in printing after 5 seconds of capping time.
Evaluation B: No disturbance in printing after 10 seconds of capping time.
Evaluation C: No disturbance in printing with capping time of 60 seconds or more.
The evaluation results are shown in Table 1.

<Example 3 and Comparative Example 3>
Regarding the ink composition prepared in the preceding item (1), an ink jet recording apparatus having a recording head capping means provided with an ink absorbing material (Example 3), and an ink jet recording apparatus having a recording head capping means not provided with an ink absorbing material. (Comparative Example 3) was used to evaluate clogging recovery.
A printer (PX-V700; manufactured by Seiko Epson Corporation) was used as the ink jet printer of Example 3, and a printer (Stylus C80; manufactured by Seiko Epson Corporation) was used as the ink jet printer of Comparative Example 3.

Each of the printers was filled with the ink composition, and after confirming that normal printing could be performed, printing was stopped. Thereafter, the printer was left at room temperature (25 ° C.) for 6 months. Printing was resumed after being allowed to stand for 6 months, and cleaning operation was carried out until there was no ejection failure and printing equivalent to that before being left. The number of cleaning operations was evaluated according to the following criteria.
Evaluation A: Printing equivalent to that before standing was obtained by 0 to 5 cleaning operations.
Evaluation B: Printing equivalent to that before standing was obtained by 6 to 10 cleaning operations.
Evaluation C: Prints equivalent to those before standing were not obtained in 11 cleaning operations. Table 1 shows the evaluation results.

  An ink jet recording method is provided that ensures very good ejection stability.

FIG. 3 is a schematic partial cross-sectional view of a cap portion and a recording head portion sealed by the cap portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cap part; 2 ... Recording head part;
11 ... Cap holder; 12 ... Closure member;
12a ... receiving part; 12b ... projecting wall part; 12c ... tip part of projecting wall part;
13 ... ink absorbing material; 14 ... protrusions;
21 ... Nozzle opening; 22 ... Surface of the recording head;
22a ... Outer region of the sealing region.

Claims (5)

An ink jet recording method using an ink composition for ink jet recording containing 6% by weight or more of a self-dispersing pigment and 3% by weight or more of resin particles,
The inkjet recording method described above, comprising using an inkjet recording apparatus having a recording head capping unit provided with an ink absorbing material.   The ink jet recording method according to claim 1, wherein an ink composition having a self-dispersing pigment content of 6 wt% to 15 wt% is used.   The ink jet recording method according to claim 1 or 2, wherein an ink composition having a resin particle content of 3 wt% to 15 wt% is used.   The ink jet recording method according to any one of claims 1 to 3, wherein the ink absorbing material comprises a porous foam or a fibrous porous body.   A recorded matter formed by the inkjet recording method according to claim 1.

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