JP2009249446A - Aqueous inkjet ink and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inkjet ink obtaining an image of high quality compatibly having high print density and friction resistance of an image and having high glossiness without generating unevenness even when print is performed on a non-absorbing medium and greatly suppressing stain along fiber when print is performed on a cloth and to provide an ink jet recording method using the same. <P>SOLUTION: In the aqueous ink jet ink containing at least carbon black having 200 to 380 m<SP>2</SP>/g specific surface area and pH 6 to 8 measured by a JIS test method, a polymer dispersant, a fixing resin and a solvent, the fixing resin is an amine neutralization type water-soluble resin or a water-dispersible emulsion and the solvent contains at least a glycol ether or a ≥4C 1,2-alkane diol. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel water-based inkjet ink for a non-water-absorbing recording medium and an ink-jet recording method using the same, and more particularly, good image quality can be obtained even when printed on a non-water-absorbing recording medium or fabric. The present invention relates to an aqueous inkjet ink having high image abrasion resistance and an inkjet recording method using the same.

  In recent years, since an inkjet recording method can produce images easily and inexpensively, it has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters.

  Ink jet inks used in such ink jet recording methods include water-based ink-jet inks composed of water and a small amount of organic solvents, non-aqueous ink-jet inks that contain substantially no water, and heat-melt inks that are solid at room temperature. There are a plurality of ink-jet inks such as hot-melt ink for printing and actinic ray-curable ink-jet ink that is cured by actinic rays such as light after printing, and these are used properly depending on the application.

  On the other hand, non-water-absorbing recording media such as polyvinyl chloride are used in a wide range of applications such as outdoor postings that require long-term weather resistance and printed matter that requires adhesion to curved objects. There are many methods for printing on polyvinyl chloride. However, there is an ink jet recording method as a method suitable for the production of a small variety of products because there is no need to prepare a plate and the period until finishing is short.

  As an example of an inkjet ink system that can be recorded on the above-described polyvinyl chloride recording medium, an inkjet ink containing cyclohexanone is disclosed (see Patent Document 1). Cyclohexanone has a high solubility in polyvinyl chloride, and the pigment in the ink-jet ink penetrates into the polyvinyl chloride, so that good scratch resistance can be obtained. In addition, non-aqueous inkjet inks containing organic solvents such as N-methylpyrrolidone and amide are disclosed as organic solvents that have a weak odor compared to cyclohexanone and are preferable in the working environment (see Patent Documents 2 and 3). In addition, a non-aqueous ink jet ink to which a resin such as vinyl chloride-vinyl acetate copolymer or acrylic is added for the purpose of improving image fastness such as scratch resistance is disclosed (see Patent Documents 4 and 5).

  Although these odors can be suppressed to some extent by these ink-jet inks and ink-jet inks exhibiting excellent scratch resistance against polyvinyl chloride can be obtained, the environmental burden associated with the discharge of a large amount of organic solvent due to drying is a problem.

  Further, printing on a fabric using an ink jet method, that is, application of ink jet textile printing is also performed. Unlike conventional textile printing, ink jet textile printing does not require the production of a plate and can quickly form an image with excellent gradation. Furthermore, since only an amount of ink necessary for an image is required, the image forming method is excellent in terms of environment such as a small amount of waste liquid.

  In inkjet printing, it is common to perform a dedicated pretreatment on a fabric in advance. Without pre-treatment, the ink bleeds along the fibers and the image quality is greatly reduced, and the image fixability is insufficient.

  However, the known pretreatment is generally a method in which a solution containing fine particles such as silica and alumina and a water-soluble polymer such as PVA and CMC is dipped in a cloth and then pressed and dried. On the other hand, there are productivity problems such as complicated work and time required. Furthermore, after the printing on the fabric, it is necessary to perform a post-treatment for the purpose of fixing to the fiber, and environmental considerations such as a decrease in productivity and a problem of waste liquid treatment are necessary.

  Such complicated pre- and post-treatments and the associated high costs are major issues for inkjet printing, and unless these are overcome, further market expansion cannot be achieved.

  Pigment inks are inferior in color tone and sharpness compared to dye inks, but are excellent in light resistance and water resistance, are less likely to bleed even when there is no pretreatment, and have excellent fixability to fibers. There are various advantages such as simple post-treatment on the fabric, and no choice of pigment type depending on the type of fabric.

  For this reason, ink-jet textile printing methods using pigment inks are currently attracting attention, but when printed on fabrics that have not been pretreated, no ink that satisfies bleeding and fiber fixing properties has been obtained. There is a present situation. There is a need for an inkjet printing method that requires no pretreatment, has good image quality such as bleeding and fixing properties, and has high productivity and low cost even when printed on various fabrics.

  As an example of the ink jet textile printing method, a method of discharging a pigment ink after a step of attaching a reaction liquid containing a reactive agent to a fabric is disclosed (see Patent Document 6). In addition, a method of using a colorant including a pigment in a polymer having a crosslinked structure for inkjet printing is described (for example, see Patent Document 7). Furthermore, a method of using a hot melt ink containing a wax and a colorant for inkjet printing has been proposed (for example, see Patent Document 8).

As described above, various studies have been made on ink-jet textile printing, but it has not yet achieved a sufficient recording density, image quality, and image abrasion resistance. There is also a demand for a textile printing method capable of printing at a high speed with a simpler recording apparatus.
Japanese translation of PCT publication No. 2002-526631 JP 2005-15672 A Japanese Patent Laid-Open No. 2005-60716 JP 2005-36199 A WO2004 / 007626 pamphlet JP 2003-55886 A JP 2002-338859 A JP-A-9-3006066

  The present invention has been made in view of the above problems, and its purpose is to obtain a high-quality image that achieves both high print density and image abrasion resistance, and in particular, even when printed on a non-absorbent medium. An object of the present invention is to provide an ink-jet ink which is glossy and free from spots, and further has a remarkable suppression of bleeding along a fiber when printed on a cloth, and an ink-jet recording method using the same.

  The above object of the present invention is achieved by the following configurations.

1. In an aqueous inkjet ink containing at least a carbon black, a polymer dispersant, a fixing resin, and a solvent having a specific surface area of 200 m ² / g or more and 380 m ² / g or less and having a pH measured by a JIS test method in the range of 6 to 8. An aqueous inkjet ink, wherein the fixing resin is an amine-neutralized water-soluble resin or water-dispersible emulsion, and the solvent contains at least glycol ether or 1,2-alkanediol having 4 or more carbon atoms.

  2. 2. The water-based inkjet ink as described in 1 above, wherein the mass ratio of the fixing resin to carbon black (fixing resin / carbon black) is 0.8 or more and 4.0 or less.

  3. 3. The aqueous inkjet ink as described in 1 or 2 above, wherein the glycol ether is at least one selected from diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and propylene glycol monopropyl ether.

  4). 4. The water-based inkjet ink according to any one of 1 to 3, wherein carbon black is dispersed in the ink with a polydispersity index of 0.18 or more and 0.40 or less.

  5). 5. An ink jet recording method comprising recording an image on a non-water-absorbing recording medium or fabric using the water-based ink-jet ink according to any one of 1 to 4 above.

  6). 6. The ink jet recording method as described in 5 above, wherein the recording is carried out by heating the surface of the non-water-absorbing recording medium or fabric on the recording surface side to 35 ° C. or more and 80 ° C. or less.

  According to the present invention, a high-quality image that achieves both high print density and image abrasion resistance can be obtained. Particularly, when printed on a non-absorbent medium, high gloss and no spots are generated, and further when printed on a fabric. Can provide an ink-jet ink in which bleeding along fibers is greatly suppressed and an ink-jet recording method using the ink-jet ink.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  Conventionally, when printing on a non-water-absorbing recording medium such as a vinyl film using a water-based pigment ink-jet ink, the ink-jet ink penetrates and the recording medium has a high ink-absorbing ability such as a paper medium. Since there is no drying, the ink droplets that have landed on the recording medium are coalesced and it is difficult to generate spots or obtain sufficient gloss. In particular, when a recording medium having a low surface energy, such as a recording medium made of vinyl chloride, is used, the ink jet ink has low wettability with respect to the recording medium, and ink droplets are coalesced and spots are likely to occur. It was. On the other hand, in the cloth, there is a problem that if the pretreatment is not performed as described above, ink spreads along the fiber and the image quality is greatly deteriorated.

  In order to solve the above problems, a water-based inkjet ink containing at least a pigment dispersion dispersed with a polymer dispersant, a fixing resin as a requirement of the present invention, and a glycol ether or a 1,2-alkanediol having 4 or more carbon atoms as a solvent In view of the above, it has been clarified by the present inventors that a significant inhibitory effect can be obtained with respect to spots generated on a non-water-absorbent recording medium and bleeding on a fabric. It is interpreted that this effect is derived from the fact that the ink having the above configuration exhibits a high viscosity increase when dried. However, in subsequent studies, when at least a glycol ether or a 1,2-alkanediol having 4 or more carbon atoms is contained and carbon black is used as a pigment, the print density, gloss, and abrasion resistance are increased depending on the carbon black used. It was newly found that there is a problem that deteriorates significantly.

As a result of diligent investigations on this problem, the above problem was greatly improved by using carbon black having a specific surface area of 200 m ² / g or more and 380 m ² / g or less and a pH measured by the JIS test method in the range of 6 to 8. As soon as it has been found out that it can be improved, the present invention has been achieved.

  Hereinafter, a water-based inkjet ink (hereinafter also simply referred to as ink) and an inkjet recording method will be specifically described.

<Carbon black>
The carbon black according to the present invention is produced by a pyrolysis method or incomplete combustion using hydrocarbons such as oil and natural gas as raw materials. Thermal decomposition methods can be divided into thermal methods using natural gas and acetylene decomposition methods using acetylene gas. The incomplete combustion method is classified into a gas furnace method using natural gas as a raw material, an oil furnace method using aromatic hydrocarbon oil as a raw material, a contact method, and a lamp / pine smoke method. Carbon black produced by the currently mainstream furnace method is called “furnace black” and is preferably used in the present invention.

In the present invention, the specific surface area of carbon black needs to be in the range of 200 m ² / g or more and 380 m ² / g or less. By having a specific surface area of 200 m ² / g or more, it is easy to obtain a higher print density and gloss. The upper limit of the specific surface area is not limited to obtain the effects of the present invention, but can stably produce carbon black, and dispersion stability It is preferable that it is 380 m < ² > / g or less from a viewpoint which is easy to acquire property. In addition, the specific surface area said by this invention is a value measured by a nitrogen adsorption method, and is computed based on the test method shown by JIS-K-6217 (1997). The specific surface area is a factor that correlates with the primary particle diameter of carbon black, and the range of the specific surface area of 200 m ² / g or more and 380 m ² / g or less as defined in the present invention is the primary particle diameter of currently produced carbon black. Is in a relatively small range, and is preferable in various fields where a high concentration is required to be hardly affected by light scattering.

  However, as described above, when the glycol ether or the 1,2-alkanediol having 4 or more carbon atoms, which is a requirement of the present invention, is contained as a solvent, the print density can be obtained even if carbon black having a specific surface area in this range is used. As a result of various investigations, high print density and gloss can be obtained by using carbon black whose pH measured by the JIS test method is in the range of 6 to 8. I found out.

  This effect has not yet been clearly interpreted, but is presumed as follows. That is, polymer adsorption on the pigment surface is roughly divided into hydrophobic interaction and ionic interaction between the pigment surface and the polymer, and it is generally said that the hydrophobic interaction is dominant in aqueous dispersion. When acidic functional groups such as carboxyl groups (—COOH), phenolic hydroxyl groups (—OH), and quinone groups (> C═O) are present on the surface like acidic carbon black, hydrophobicity with polymers such as dispersants We believe that sexual interaction is inhibited. In particular, when glycol ether or 1,2-alkanediol is present in the solvent system, it becomes more hydrophobic than a system containing water or glycol, and the hydrophobic portion of the polymer is more easily dissolved in the system. It is estimated that the interaction decreases and the pigment dispersion function and fixing function deteriorate. Therefore, the use of carbon black having a pH of 6 to 8 having a low acidic functional group that inhibits hydrophobic interaction as described above results in an increase in the polymer adsorptivity to the pigment surface, resulting in an increase in scratch resistance. It is interpreted that gloss and density are improved by suppressing aggregation during the print drying process.

  Here, the pH measured by the JIS test method (JIS K6221) is a value measured as follows. That is, 100 ml of distilled water was added to 10 g of carbon black, boiled for 15 minutes on a hot plate, cooled to room temperature, the supernatant was removed with a centrifuge, and the pH of the mud was measured with a glass electrode pH meter. .

  The average particle diameter in the dispersed state of carbon black contained in the ink of the present invention is preferably 70 nm or more and less than 200 nm. If the average particle diameter is 70 nm or more, the storage stability of the ink can be kept relatively stable, and if it is less than 200 nm, a high print density and gloss can be easily obtained. The particle size of the pigment dispersion can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, or the like. Accurate and often used. It was also found that a higher print density can be obtained by adjusting the polydispersity index to 0.18 or more and 0.40 or less as the dispersion state of the carbon black contained in the ink of the present invention. The polydispersity index (PDI) in the present invention is based on the following definition. The polydispersity index (PDI) in the present invention is an index that defines the particle size distribution of the dispersion, and is defined by the following formula (1).

Formula (1)
PDI = (D ₉₀ -D ₁₀ ) / D ₅₀
In the formula (1), D ₉₀ , D ₅₀ , and D ₁₀ are integrals of the distribution function dG = F (D) × dD, respectively, and are 0.9 (90% by mass) and 0.5 of the total mass of the disperse dye fine particles. Represents a particle size equal to (50% by weight) and 0.1 (10% by weight). G represents the mass of the dispersed dye fine particles, and D represents the particle size of the dispersed dye fine particles.

The above relational expression will be further described with reference to the drawings. FIG. 1 shows a dispersion system in which the volume particle diameter (D) of a disperse dye particle is plotted on the abscissa and the particle mass function (G) of each disperse dye particle of a given size is plotted on the ordinate. The curve of the distribution function of the volume particle diameter of the dye fine particles is shown as a solid line 11. Further, in the same coordinate system, the points of 10%, 50% and 90% particle mass function and the related points 15 (D ₁₀ ), 14 (D ₅₀ ) and 13 (D ₉₀ ) of the volume particle diameter are represented by crosses. The integration of the distribution function is shown as a dashed curve 12. In the above relational expression, the narrower the particle size distribution is, the closer PDI is to zero. Conversely, the wider the particle size distribution, that is, the greater the polydispersity, the larger the PDI. The volume particle size can be measured by, for example, a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method, or the like. As a specific particle size measuring device, for example, manufactured by Shimadzu Corporation Laser diffraction particle size measuring device SLAD1100, particle size measuring device (HORIBA LA-920), Malvern Zetasizer 1000 and the like.

  We thought that the smaller the polydispersity index (the narrower the particle size distribution), the higher the print density, but we have not yet clarified that there is an optimal range as described above, but we think as follows ing. That is, since the ink of the present invention has a high viscosity when dried as described above, it is easy to make a structure in which carbon black is sparsely laminated in the drying process, and the carbon black filling rate is low unless there is a certain particle size distribution. It is thought that scattering between particles affects the print density.

  The carbon black according to the present invention is preferably used after being dispersed by a disperser together with a polymer dispersant and other additives necessary for various desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. In particular, the particle size distribution of the ink produced by dispersion with a sand mill is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Furthermore, the bead diameter is preferably 0.3 mm to 3 mm.

<Polymer dispersant>
The polymer dispersant according to the present invention is preferably a polymer having a molecular weight of 5000 or more and 200000 or less.

  The polymer dispersant is selected from styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid and fumaric acid derivatives. Examples thereof include a block copolymer comprising at least one kind of monomer, a random copolymer and salts thereof, polyoxyalkylene, and polyoxyalkylene alkyl ether.

  In the case of an acidic polymer dispersant, it is preferably added after neutralization with a neutralizing base. Here, the neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine.

  Moreover, in this invention, it is preferable that the addition amount of a polymer dispersing agent is 10-100 mass% with respect to carbon black.

  As a method of using the polymer dispersant used in the present invention, a so-called capsule pigment obtained by coating carbon black with a polymer dispersant is also preferably used. Various known methods can be used as a method of coating carbon black with a polymer dispersant. Preferably, in addition to the phase spreading emulsification method and the acid precipitation method, a pigment is used as a polymerizable surfactant. It is preferable to select from a method of dispersing, supplying a monomer thereto, and coating while polymerizing.

  As a more preferred method, the water-insoluble resin is dissolved in an organic solvent such as methyl ethyl ketone, and after partially or completely neutralizing the acidic group in the resin with a base, the pigment and ion-exchanged water are added and dispersed. After that, a production method in which the organic solvent is removed and is adjusted by adding water as necessary is preferable.

<Fixing resin>
One of the characteristics of the ink of the present invention is that it contains a fixing resin from the viewpoint of obtaining scratch resistance of the ink film to be formed.

  The fixing resin according to the present invention is preferably contained in the ink in a mass ratio of the fixing resin to carbon black in the range of 0.8 to 4.0, more preferably 1.0 to 2. Within the range of 5 or less, it is easy to achieve both scratch resistance and ejection stability.

  In the present invention, a preferable fixing resin is a water-soluble copolymer having a hydrophobic monomer as a polymerization component or water-dispersed polymer fine particles from the viewpoint of obtaining image scratch resistance even in a high-humidity environment or when moisture adheres. Preferably there is.

  Hereinafter, a water-soluble copolymer having a hydrophobic monomer as a polymerization component will be described.

  A water-soluble copolymer having a hydrophobic monomer as a polymerization component (hereinafter abbreviated as “water-soluble copolymer”) is stably dissolved in ink, but is given water resistance after drying on a recording medium. A resin is more preferable.

  As such a resin, a resin having a hydrophobic component and a hydrophilic component is designed and used. At this time, as the hydrophilic component, either an ionic or nonionic component may be used, but an ionic component is more preferable, and an anionic component is more preferable. In particular, those which are rendered water-soluble by neutralizing anionic substances with a volatile base component are preferred.

  In particular, at least one of the fixing resins is a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component, and the acid value is preferably in the range of 80 or more and less than 300 in view of the effect of the present invention.

  Examples of the hydrophobic monomer of the copolymer include acrylic acid ester (n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc.), methacrylic acid ester (ethyl methacrylate, butyl methacrylate, methacrylic acid). Glycidyl acid) and styrene.

  Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, acrylamide and the like, and those having an acidic group such as acrylic acid are preferably partially or completely neutralized with a base component after polymerization. In this case, as the neutralizing base, alkali metal-containing bases such as sodium hydroxide and potassium hydroxide, and amines (for example, ammonia, alkanolamine, alkylamine, etc.) can be used. In particular, neutralization with amines having a boiling point of less than 200 ° C. is particularly preferable from the viewpoint of improving image fastness.

  As a molecular weight of the copolymer, an average molecular weight of 3000 to 30000 can be used, and a more preferable molecular weight range is 7000 to 20000. Further, Tg of about -40 ° C to 100 ° C can be used, and a more preferable range of Tg is -20 ° C to 80 ° C.

  Next, water-based dispersed polymer fine particles that are preferably used in addition to the water-soluble copolymer having the hydrophobic monomer as a polymerization component as the fixing resin according to the present invention will be described.

  As the polymer fine particles, a dispersion polymerized in an aqueous system may be used as it is or may be treated, or a polymer polymerized in a solvent system may be dispersed in an aqueous system. For example, acrylic, urethane Styrene, vinyl acetate, vinylidene chloride, vinyl chloride, styrene-butadiene, styrene-acrylonitrile, polybutadiene, polyethylene, polyisobutylene, polyester, and the like.

  As the physical properties of the ink, it is preferable that there is no shear dependency on the viscosity. From this viewpoint, as a dispersion form of the polymer fine particles, an emulsifier such as a surfactant is made as low as possible, or a soap-free type dispersion polymer that does not use an emulsifier. Particles are preferred. A preferred aqueous dispersion polymer fine particle is a self-dispersion dispersion of a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component. For example, an acrylic monomer such as ethyl acrylate alone or an acrylic monomer is used. A dispersion obtained by emulsion polymerization or suspension polymerization of acrylic acid or maleic acid as a carboxylic acid monomer in a composition comprising an ethylenically unsaturated monomer copolymerizable with a monomer is mechanically swelled with an alkaline compound. An acrylic hydrosol obtained by dividing particles by shearing. Among acrylic hydrosols, it is preferable to contain styrene in the monomer composition from the viewpoint of increasing the refractive index of the resin and obtaining a high gloss feeling.

  Examples of the alkaline compound include ammonia, triethylamine, 2-dimethylaminoethanol, 2-di-n-butylaminoethanol, methyldiethanolamine, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, 2- An amine such as methylaminoethanol is preferable, and ammonia, 2-amino-2-methyl-1-propanol, and 2-methylaminoethanol are particularly preferable in terms of dispersion stability of the aqueous dispersion polymer fine particles.

  The acrylic hydrosol is commercially available, for example, as the John Crill series of Johnson Polymer Co., Ltd.

  The acid value of the aqueous dispersion polymer fine particles is preferably 44 mgKOH / g or more, more preferably 60 mgKOH / g or more, from the viewpoint of obtaining good redispersion / solubility of the ink dry film. The upper limit of the acid value is not particularly limited, but is preferably less than 110 mgKOH / g from the viewpoint of easily obtaining a more stable dispersion.

  The average particle size of the water-dispersed polymer fine particles is preferably 300 nm or less, more preferably 130 nm or less from the viewpoint that the nozzle of the head is not clogged and a good gloss feeling is obtained. The lower limit of the average particle diameter is preferably 30 nm or more from the viewpoint of the production stability of the fine particles. The average particle diameter of the water-dispersed polymer fine particles can be easily measured using a commercially available measuring device using a light scattering method or a laser Doppler method. Alternatively, the dispersion of the aqueous dispersion polymer fine particles can be freeze-dried, and the average particle diameter can be converted from the particles observed with a transmission microscope.

  As the fixing resin of the present invention, it is also preferable to use the water-soluble copolymer and water-dispersed polymer fine particles in combination, and the image bleeding and gloss can be improved in a balanced manner.

<Glycol ether and 1,2-alkanediol>
The glycol ether and 1,2-alkanediol having 4 or more carbon atoms according to the present invention will be described.

  The ink of the present invention has a water-solubility selected from at least glycol ether or 1,2-alkanediol having 4 or more carbon atoms in order to obtain a good image quality in which spots and particularly bleeding generated when printed on a fabric are suppressed. It is necessary to contain an organic solvent.

  Specifically, as glycol ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol Examples include monopropyl ether and tripropylene glycol monomethyl ether.

  Examples of the 1,2-alkanediol having 4 or more carbon atoms include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and the like. The 1,2-alkanediol having 4 or more carbon atoms preferably has 8 or less carbon atoms.

  These glycol ethers or 1,2-alkanediols having 4 or more carbon atoms may be used alone or in combination.

  The addition amount is preferably 5% to 30%, and more preferably 7% to 20%. By using in this range, it is possible to effectively suppress spots during printing and, in particular, bleeding that is likely to occur when printed on a fabric. Particularly preferred solvents are diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and propylene glycol monopropyl ether.

  In addition to glycol ether or 1,2-alkanediol having 4 or more carbon atoms, a solvent can be added to the ink of the present invention.

  Specifically, as the solvent according to the present invention, an aqueous liquid medium is preferably used, and examples include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol). , Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), amine (For example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine) , Morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N , N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides ( Examples thereof include dimethyl sulfoxide).

  The water, which is a requirement of the present invention, is preferably contained in an amount of 40% or more from the viewpoint of improving the drying property and the storage stability of the ink, and more preferably 50% or more.

<Surfactant etc.>
In the present invention, it is preferable to use a surfactant from the viewpoint of imparting higher wettability to a non-water-absorbing recording medium. In order to impart wettability, the surface tension of the ink is preferably 30 mN / m or less, and more preferably 28 mN / m or less.

  The surfactant that can be used in the present invention is not particularly limited as long as the surface tension of the ink can be adjusted to 30 mN / m or less, but an anionic compound is used as another component of the ink. In view of inclusion, the ionicity of the surfactant is preferably an anionic, nonionic or betaine type.

  In the present invention, a fluorine-based or silicon-based surfactant that preferably has a high ability to reduce static surface tension, an anionic surfactant such as dioctyl sulfosuccinate that has a high ability to reduce dynamic surface tension, and a relatively low Nonionic surfactants such as molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, acetylene glycols, pluronic surfactants, and sorbitan derivatives are preferably used. It is also preferable to use a fluorine-based or silicon-based active agent in combination with a surfactant having a high ability to reduce the dynamic surface tension.

  In the ink of the present invention, in addition to the above description, if necessary, the output stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performance improvement objectives are known. Various additives such as polysaccharides, viscosity modifiers, specific resistance regulators, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, antifungal agents, rust preventives, etc. may be appropriately selected and used. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicon oil, ultraviolet absorbers described in JP-A-57-74193, 57-87988, and 62-261476, As described in Kaisho 57-74192, 57-87989, 60-72785, 61-146591, JP-A-1-95091 and 3-13376, etc. Anti-fading agents, fluorescent whitening agents described in JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266 Can be mentioned.

  The ink of the present invention having the above-described configuration preferably has an ink viscosity of 1 to 40 mPa · s at 25 ° C., more preferably 5 to 40 mPa · s, and still more preferably 5 to 20 mPa · s. is there.

<Non-water-absorbing recording medium>
Next, the non-water absorbent recording medium according to the present invention will be described.

  The ink of the present invention is suitable not only for printing on a non-water-absorbing medium such as a vinyl chloride sheet, which is the object of the present invention, but also for printing on plain paper, coated paper, ink jet dedicated paper, and the like.

  Examples of the non-water-absorbing recording medium include a polymer sheet, a board (soft vinyl chloride, hard vinyl chloride, acrylic plate, polyolefin, etc.), glass, tile, rubber, synthetic paper and the like.

  Examples of the low absorption or absorption medium include plain paper (copy paper, plain paper for printing), coated paper, art paper, inkjet exclusive paper, inkjet glossy paper, cardboard, and wood.

  In particular, a preferable non-water-absorbing recording medium capable of obtaining a good image and high image fastness is a recording medium having at least polyvinyl chloride on the recording surface side.

  Specific examples of the recording medium made of polyvinyl chloride include SOL-371G, SOL-373M, SOL-4701 (manufactured by Big Technos Co., Ltd.), glossy vinyl chloride (manufactured by Systemgraph Co., Ltd.), KSM-VS, KSM. -VST, KSM-VT (above, manufactured by Kimoto Co., Ltd.), J-CAL-HGX, J-CAL-YHG, J-CAL-WWWG (above, manufactured by Kyo Show Osaka Co., Ltd.), BUS MARK V400 F vinyl, LITEcal V-600F vinyl (above, manufactured by Flexcon), FR2 (manufactured by Hanwha), LLBAU13713, LLSP20133 (above, manufactured by Sakurai Co., Ltd.), P-370B, P-400M (above, manufactured by Kambo Plus Co., Ltd.), S02P, S12P, S13P, S14P, S22P, S24P, 34P, S27P (manufactured by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (manufactured by Lintec Corporation), LKG-19, LPA-70, LPE-248, LPM-45 LTG-11, LTG-21 (manufactured by Shinsei Co., Ltd.), MPI 3023 (manufactured by Toyo Corporation), Napoleon Gloss PVC (manufactured by Futaki Electronics Co., Ltd.), JV-610, Y-114 ( As described above, manufactured by ICC Corporation), NIJ-CAPVC, NIJ-SPVCGT (hereinafter, manufactured by Nichie Corporation), 3101 / H12 / P4, 3104 / H12 / P4, 3104 / H12 / P4S, 9800 / H12 / P4, 3100 / H12 / R2, 3101 / H12 / R2, 3104 / H12 / R 2, 1445 / H14 / P3, 1438 / One Way Vision (manufactured by Intercoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829RM, JT5929PM (above, manufactured by Mactac, MP1100, MP1100, MP1100) MPI2001, MPI2002, MPI3000, MPI3021, MPI3500, MPI3501 (above, manufactured by Avery), AM-101G, AM-501G (above, manufactured by Ginichi Co., Ltd.), FR2 (manufactured by Hanwha Japan Co., Ltd.), AY-15P, AY-60P, AY-80P, DBSP137GGH, DBSP137GGL (above, manufactured by Insight Inc.), SJT-V200F, SJ T-V400F-1 (above, manufactured by Hiraoka Oryome Co., Ltd.), SPS-98, SPSM-98, SPSH-98, SVGL-137, SVGS-137, MD3-200, MD3-301M, MD5-100, MD5- 101M, MD5-105 (manufactured by Metamark), 640M, 641G, 641M, 3105M, 3105SG, 3162G, 3164G, 3164M, 3164XG, 3164XM, 3165G, 3165SG, 3165M, 3169M, 3451SG, 3551G, 3551M, 3631, 3641M , 3651G, 3651M, 3651SG, 3951G, 3641M (above, manufactured by Orafol), SVTL-HQ130 (manufactured by Lamy Corporation), SP300 GWF, SPCLEARAD vinyl l (above, made by Catalina), RM-SJR (made by Ryoyo Shoji Co., Ltd.), Hi Lucky, New Lucky PVC (above, made by LG), SIY-110, SIY-310, SIY-320 (above, Sekisui Chemical) Kogyo Co., Ltd.), PRINT MI Frontlit, PRINT XL Lightweight banner (above, manufactured by Endutex), RIJET 100, RIJET 145, RIJET165 (above, manufactured by Ritrama), NM-SG, NM-SM Co., Ltd. Manufactured), LTO3GS (manufactured by Lucio Co., Ltd.), easy print 80, performance print 80 (manufactured by Jetgraph Co., Ltd.), DSE 550, DSB 550, DSE 800G, DSE 802/137, V250WG, 300WG, V350WG (manufactured by Hexis Ltd.), Digital White 6005PE, 6010PE (or, Multifix Co., Ltd.).

<Fabric>
The fabric according to the present invention is preferably a fabric made of polyester, cotton, silk, hemp, rayon, or acetate fiber. In particular, a fabric mainly composed of polyester fibers is preferable, and fibers mainly composed of polyester fibers may be in any form such as woven fabric, knitted fabric, and non-woven fabric. As the fabric, it is preferable that the polyester fiber is 100%, but a blended woven fabric or a blended non-woven fabric with rayon, silk, polyurethane, acrylic, nylon, wool, or the like can also be used. Further, the thickness of the yarn constituting the fabric as described above is preferably in the range of 10 to 100d.

<Recording method>
In the ink jet recording method of the present invention, when an image is recorded on a recording medium using the ink according to the present invention, the surface temperature on the recording surface side of the recording medium is heated to 35 ° C. or higher and 80 ° C. or lower for recording. It is preferable to do.

  By heating the recording medium, the drying and thickening speed of the ink is remarkably improved, high image quality is obtained, and in addition, the durability of the formed image is also improved.

  By heating to 35 ° C or higher as the heating temperature of the recording medium, it is possible to effectively suppress spots that are likely to occur particularly on non-absorbent recording media and bleeding that is likely to occur on the fabric, and to easily obtain sufficient image durability. In addition, the drying time can be shortened, and if it is 80 ° C. or lower, it is possible to stably form an image without greatly affecting ink ejection. More preferably, the recording surface temperature of the recording medium is preferably heated to 35 ° C. or more and 60 ° C. or less.

  As a heating method of the recording medium, a heating heater is incorporated in the recording medium conveyance system or platen member of the ink jet recording apparatus and heated from the back side of the non-water-absorbing recording medium, or non-contact from below or above with a lamp or the like. The method of heating with can be selected.

  When forming an image by ejecting the ink of the present invention, the ink jet head to be used may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<Preparation of ink>
[Preparation of Ink-1]
(Preparation of carbon black dispersion)
As a polymer dispersant, 5 parts of a styrene-acrylic acid copolymer (John Cryl 678, molecular weight 8500, acid value 215 mgKOH / g), 2.1 parts of dimethylaminoethanol, and 77.9 parts of ion-exchanged water are stirred and mixed at 70 ° C. And dissolved. Next, 15 parts of carbon black (specific surface area: 370 m ^{2 /} g, pH 6.5) was added to this solution and premixed, and then a sand grinder filled with 50% by volume of 0.5 mm zirconia beads was used. Dispersion liquid having a carbon black content of 15% was prepared.

(Synthesis of fixing resin aqueous solution-1)
50 g of methyl ethyl ketone was added to a flask equipped with a dropping funnel, a nitrogen introducing tube, a reflux condenser, a thermometer and a stirring device, and heated to 75 ° C. while bubbling nitrogen. Thereto, a mixture of 40 g of n-butyl methacrylate, 40 g of styrene, 20 g of acrylic acid, 50 g of methyl ethyl ketone, and 500 mg of an initiator (AIBN) was dropped from a dropping funnel over 3 hours. It heated and refluxed for 6 hours after dripping. After allowing to cool, the mixture was heated under reduced pressure to distill off methyl ethyl ketone.

  Next, the polymer residue was dissolved in a solution in which dimethylaminoethanol corresponding to 1.05 mol of acrylic acid added as a monomer was dissolved in 450 ml of ion-exchanged water. Adjustment with ion exchange water gave a fixing resin aqueous solution-1 having a solid content of 20%.

(Preparation of ink)
[Preparation of Ink-1]
The ink composition shown below was prepared by mixing and stirring, and then filtered through a 0.8 μm filter to obtain ink-1. The obtained ink-1 had a viscosity of 9.3 mPa · s and a surface tension of 27.6 mN / m as measured at 25 ° C. The average particle size of carbon black dispersed in the prepared ink was 117 nm, and the polydispersity index was 0.19. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

Carbon black dispersion 33.3% by mass
Fixing resin aqueous solution-1 (solid content concentration 20%) 15.0 mass%
Fixing resin-2 6.5% by mass
(Johncrill 390, BASF water dispersible emulsion, solid content 46%)
Diethylene glycol monobutyl ether 15.0% by mass
Silicon-based surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass
Ion exchange water Amount required to finish to 100% by mass [Preparation of inks 2 to 24]
Inks-2 to 24 were prepared in the same manner as in the preparation of Ink-1, except that the specific surface area and pH of the carbon black used, the solvent, and the fixing resin were changed as shown in Table 1. However, the 0.5 mm zirconia beads used in the dispersion of carbon black were changed to 0.3 mm, 1.0 mm, and 1.5 mm zirconia beads in order for inks 22, 23, and 24. In addition, about the prepared inks 2-24, the viscosity measured on 25 degreeC conditions was the range of 9-10 mPa * s, and the surface tension was the range of 27-29 mN / m.

  In addition, the detail of each organic solvent described with the abbreviation in Table 1 is as follows.

DEGBE: Diethylene glycol monobutyl ether DPGPE: Dipropylene glycol monopropyl ether PGPE: Propylene glycol monopropyl ether 1,2-HDO: 1,2-hexanediol EG: Ethylene glycol PG: Propylene glycol Gly: Glycerol 1,5-PDO: 1 , 5-Pentanediol DEGEE: Diethylene glycol monoethyl ether << Evaluation of ink >>
Each ink set prepared above was evaluated according to the following method.

[Print image]
A shuttle type equipped with a piezo head having a nozzle diameter of 28 μm, a nozzle number of 512, a minimum liquid amount of 14 pl, a nozzle density of 180 dpi (dpi represents the number of dots per 2.54 cm), and a maximum recording density of 720 × 720 dpi. Each ink was loaded into an inkjet printer.

  Next, each ink was emitted to a recording medium under the conditions of a print resolution of 720 dpi × 720 dpi, a head conveyance speed: 200 mm / sec, and bidirectional scanning, and a solid image of 10 cm × 10 cm was printed to obtain a recorded image. As a recording medium, a fabric of 100% polyester fiber and a thread thickness of 50d and JT5929PM (manufactured by Mactac), which is a recording medium made of polyvinyl chloride, were used.

  The recording medium was heated from the back side by a flat panel heater installed on the platen portion during printing, and the heater temperature was controlled so that the surface temperature of the recording medium during image recording was 45 ° C. The surface temperature of the recording medium was measured using a non-contact thermometer (IT-530N type, manufactured by Horiba, Ltd.).

[Evaluation of recorded images]
Each of the formed recorded images was subjected to evaluation according to the following method after being left for 12 hours in an environment of 23 ° C. and humidity 55% RH after printing.

(Evaluation of spots)
About each recorded image, the occurrence state of the spot was visually evaluated, and the spot resistance was evaluated according to the following criteria.

○: generation of spots is not observed, and the quality is good. Δ: spots are partially seen, but is within a practical range. ×: spots are generated over the entire surface, and the quality is outside the acceptable range for practical use. Yes (Evaluation of reflection density)
The reflection density of each recorded image was measured using a reflection densitometer (X-rite).

(Glossiness measurement)
About the recording image produced using said vinyl chloride recording medium, the glossiness was measured using the Nippon Denshoku Industries Co., Ltd. variable angle glossiness meter (VGS-1001DP). The incident and reflection angles were measured at 20 °, and the glossiness was evaluated according to the following criteria based on the glossiness value.

◎: 91 or more ○: 75-90
Δ: 65-74
X: Less than 65 In the above evaluation rank, ◎ to Δ were judged to be practically preferable ranks.

(Evaluation of bleeding)
The occurrence of bleeding at the boundary between the recorded image portion and the non-image portion produced using the above fabric was visually evaluated according to the following criteria.

○: No blur is observed at the boundary between the image portion and the non-image portion △: Slight blur is observed at the boundary between the image portion and the non-image portion, but there is no practical problem ×: Appreciation at the boundary between the image portion and the non-image portion Bleeding at a level unbearable (evaluation of abrasion)
The surface of each recorded image was rubbed with dry cotton (Kanakin No. 3), and scratch resistance was evaluated according to the following criteria.

◎: Image hardly changes even after rubbing 50 times or more ○: Slight scratch remains at the stage of rubbing 50 times, but hardly affects the image density Δ: Image density decreases during rubbing 20 to 50 times × : Image density decreases while rubbing less than 20 times In the above evaluation ranks, Δ to ◎ were judged to be practically preferred ranks.

  Table 2 shows the results obtained as described above.

  As apparent from the results shown in Table 2, the ink satisfying the requirements of the present invention showed good results in all the evaluation items. On the other hand, the other inks were practically unacceptable in any of the evaluation items.

The particle size distribution function curve representing D ₁₀ , D ₅₀ , and D _{90 according} to the present invention.

Explanation of symbols

11 Particle size distribution function of pigment dispersion 12 Integral curve of particle size distribution function 13 D ₉₀ display 14 D ₅₀ display 15 D ₁₀ display

Claims (6)

In an aqueous inkjet ink containing at least a carbon black, a polymer dispersant, a fixing resin, and a solvent having a specific surface area of 200 m ² / g or more and 380 m ² / g or less and having a pH measured by a JIS test method in the range of 6 to 8. An aqueous inkjet ink, wherein the fixing resin is an amine-neutralized water-soluble resin or water-dispersible emulsion, and the solvent contains at least glycol ether or 1,2-alkanediol having 4 or more carbon atoms. 2. The water-based inkjet ink according to claim 1, wherein a mass ratio of the fixing resin to carbon black (fixing resin / carbon black) is 0.8 or more and 4.0 or less. The aqueous inkjet ink according to claim 1 or 2, wherein the glycol ether is at least one selected from diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and propylene glycol monopropyl ether. The water-based inkjet ink according to claim 1, wherein the carbon black is dispersed in the ink with a polydispersity index of 0.18 or more and 0.40 or less. An ink jet recording method comprising recording an image on a non-water-absorbing recording medium or a fabric using the water-based ink-jet ink according to claim 1. 6. The ink jet recording method according to claim 5, wherein recording is performed by heating the surface temperature of the non-water-absorbing recording medium or fabric to a recording surface side of 35 ° C. or more and 80 ° C. or less.

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