JP2006096933A - Inkjet ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink excellent in water resistance, scratch resistance, and bleeding resistance of a character or an image formed on a various kind of recording medium, and excellent in inkjet stability. <P>SOLUTION: The inkjet ink comprises at least a pigment, a polymer compound A and a polymer compound B, wherein the polymer compound A is an amphipathic polymer compound and the polymer compound B has a glass transition temperature (Tg) of -30-60°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet ink that is excellent in continuous ejection properties and excellent in color bleed resistance and fixability.

  The ink jet recording method is capable of high-definition image recording with a relatively simple device, and has been rapidly developed in various fields. In addition, there are various uses, and an ink jet recording medium or ink jet ink suitable for each purpose is used.

  Ink jet inks used for ink jet recording are roughly classified into dye inks in which a color material is dissolved in a solvent and dispersed inks in which a color material is dispersed in a solvent. Since the dye ink is dissolved in a solvent, it tends to have good color developability and high chroma and is preferably used for outputting silver salt photographic images and the like. However, dye inks are basically prone to light fading, and when posted over a period of time, such as a signboard or poster, there is a problem that if the surface is not laminated, it will fade immediately. It was.

  On the other hand, the dispersed ink generally does not easily cause light fading and is preferably used for producing a poster or the like. Dispersion inks were previously unsuitable for silver salt photographic printing because the particle size of the dispersion particles was set large mainly from the viewpoint of ensuring dispersion stability. As a result, the dispersed particle size was reduced, and silver salt photographic printing was also performed. Currently, examples of the color material used in the dispersion ink include organic pigments, inorganic pigments, and colored fine particles. However, when a dispersion ink is used to print on glossy paper exclusively for inkjet or an inkjet film having high smoothness, the colorant does not penetrate into the inside of the support, and thus there is a problem of poor scratch resistance and water resistance.

  Various methods for solving the above problems have been proposed, and one of the methods is hot-melt ink. This hot-melt type ink is a wax that is solid at room temperature and melts to lower its viscosity when heated. The ink that has been melted by heating with an ink jet recording head is ejected and landed on the recording paper. After that, it is cooled and solidified to form a printed image. In this hot melt ink, since it is solid at room temperature, it is not soiled during handling, and the ink solvent does not evaporate at the time of melting, so that the nozzles are not clogged. Furthermore, since it solidifies immediately after adhesion, it has the advantage of less color bleeding. For example, US Pat. Nos. 4,391,369 and 4,484,948 propose hot-melt ink compositions that provide good print quality regardless of paper quality. However, since hot-melt ink uses wax as the main component, scratches and the like tend to occur when the formed image surface is rubbed, and there is a problem with scratch resistance, and it should be applied to permanent printed matter. Is difficult. Further, since the solid content ratio of wax or the like as the ink component is high, there is a drawback that formed characters, images, and the like are raised on the recording medium.

  As another method, an ultraviolet curable ink-jet ink is known. This ultraviolet curable ink-jet ink is an ink mainly composed of a monomer curable by ultraviolet rays and an ultraviolet curing initiator, and is printed on a recording medium and then cured by irradiating the landed ink droplets with ultraviolet rays. is there. For example, an example in which an epoxy-modified acrylic resin and a urethane-modified acrylic resin are used as a binder and a pigment having an average particle diameter of 5.0 μm or less is used as a coloring component is disclosed (for example, see Patent Document 1). However, since the ultraviolet curable ink-jet ink has a high solid content ratio, there is a drawback that formed characters, images, and the like are raised on the recording medium. Furthermore, when applied to pigment-based inks that do not sufficiently transmit ultraviolet rays, the amount of ultraviolet rays required for curing in the ink is insufficient, resulting in problems such as poor scratch resistance.

As other methods, many latex-containing sinks containing polymer fine particles have been disclosed and proposed (see, for example, Patent Documents 2 to 7). In this latex-containing ink, by adding polymer fine particles to an ink containing water as a main component, it is excellent in water resistance and scratch resistance. When printed on various recording media, the formed characters and images are recorded on the recording medium. It is said that a printed matter that does not rise above is obtained. However, when such a polymer fine particle contains an amount sufficient for fixing the pigment in the ink, continuous printing or intermittent printing is performed in an environment where the ink represented by a low humidity environment is very dry. And, due to the increase in ink viscosity accompanying the drying of the ink, it causes the ejection failure from the recording head and has a problem that stable ejection cannot be performed, and the content of the polymer fine particles is naturally limited, The current situation is that sufficient image durability required for printed matter cannot be obtained.
U.S. Pat. No. 4,228,438 Japanese Patent Publication No. 60-32663 JP-A-4-18462 JP-A-9-87560 JP-A-9-176533 Japanese Patent Laid-Open No. 10-60353 JP 2000-85238 A

  The present invention has been made in view of the above problems, and its purpose is to have excellent water resistance, scratch resistance, bleed resistance of characters and images formed on various recording media, and good ink ejection stability. It is to provide an inkjet ink.

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

(Claim 1)
Containing at least a pigment, a polymer compound A, and a polymer compound B, the polymer compound A is an amphiphilic polymer compound, and the polymer compound B has a glass transition point (Tg) of −30 ° C. or higher, An ink-jet ink comprising a polymer compound of 60 ° C. or lower.

(Claim 2)
The inkjet ink according to claim 1, wherein the amphiphilic polymer compound is at least one copolymer selected from N-substituted acrylamide, modified vinyl ether, and modified vinyl alcohol.

(Claim 3)
The average molecular weight of the amphiphilic polymer compound is 1,000 or more and 100,000 or less, and the ratio Mw / Mn between the weight average molecular weight Mw and the number average molecular weight Mn is 1.0 or more and 4.0 or less. The inkjet ink according to claim 1 or 2, wherein

(Claim 4)
The inkjet ink according to any one of claims 1 to 3, wherein the amphiphilic polymer compound has an average particle size of 20 nm or more and 1.0 µm or less.

(Claim 5)
The inkjet ink according to claim 1, wherein the polymer compound B has an average particle size of 20 nm or more and 1.0 μm or less.

(Claim 6)
6. The inkjet ink according to claim 1, wherein the total solid content is 3.0% or more and 40% or less.

  According to the present invention, it is possible to provide an ink-jet ink which is excellent in water resistance, scratch resistance and bleeding resistance of characters and images formed on various recording media and has good ink ejection stability.

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

  As a result of intensive studies in view of the above problems, the present inventor contains at least a pigment, a polymer compound A, and a polymer compound B, the polymer compound A is an amphiphilic polymer compound, and the high compound The molecular compound B is a high molecular compound having a glass transition point (Tg) of −30 ° C. or higher and 60 ° C. or lower, and the water resistance and water resistance of characters and images formed on various recording media using an inkjet ink. As soon as the present invention has been found, it has been found that an ink jet ink having excellent scratch resistance and bleeding resistance and good ink ejection stability can be realized.

  Details of the present invention will be described below.

  The inkjet of the present invention is characterized by containing the polymer compound A and the polymer compound B together with the pigment.

  First, the amphiphilic polymer compound which is the polymer compound A according to the present invention will be described.

  The amphiphilic polymer according to the present invention is a polymer compound having a hydrophilic group and a hydrophobic group in the molecule, and the hydrophobic part and the hydrophilic part are preferably a block copolymer. The average molecular weight of the amphiphilic polymer compound is 1,000 or more and 100,000 or less, and the ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn is 1.0 or more and 4.0 or less. Is more preferable and 1.0 or more and 2.5 or less are more preferable.

  In addition, the amphiphilic polymer compound according to the present invention is preferably at least one copolymer selected from N-substituted acrylamide, modified vinyl ether and modified vinyl alcohol. Examples of such a polymer compound include poly N-substituted acrylamides such as isopropyl acrylamide, hydrophobized pullulan, polyethylene oxide, amphiphilic star polymers described in JP-A No. 2002-146256, and JP-A No. 11-322866. No., JP-A-11-322942, JP-A-2000-319473, JP-A-2001-19770, and the like, and the form thereof is linear. The polymer may be a star-shaped polymer emulsion having a polymer nucleus.

  In the present invention, it is more preferable that the amphiphilic polymer compound has a core-shell structure. For example, (meth) acrylic described in JP-A-7-33224, JP-A-2003-40916, and the like. Examples thereof include polymer fine particles having a core-shell structure having a core portion made of a polymer and an outer shell portion made of an N-alkylacrylamide polymer.

  In such an amphiphilic polymer compound, a relatively hydrophilic segment and a relatively hydrophobic segment coexist in one molecule. On the other hand, in an inkjet ink, water or a mixed solvent of water and an organic solvent can be the solvent of the ink. In the amphiphilic polymer compound according to the present invention, a mixed solvent containing water as a main component becomes a poor solvent for any one segment, and the other becomes both solvents.

  The average particle size of the amphiphilic polymer compound according to the present invention is preferably 20 nm or more and 1.0 μm or less. If the average particle size is 20 nm or more, an increase in viscosity due to drying of the ink can be suppressed, and if it is 1.0 μm or less, stable emission can be achieved without causing clogging during emission from the recording head. Can be preferable. The average particle size of the amphiphile can be determined by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, or a laser Doppler method.

  In the ink-jet ink of the present invention, the content of the amphiphilic polymer compound according to the present invention is preferably 1% by mass or more and 30% by mass or less.

  In the vicinity of the nozzle of the ink jet recording head, the ink solvent such as water evaporates from the tip of the nozzle and the water content in the ink decreases (decap). As a result, the surrounding pigments and polymer compounds are embraced and aggregated. However, since the other one segment is still dissolved in the solvent, the dispersed state is maintained. As a result, an increase in viscosity due to evaporation of moisture and the like is suppressed, and continuous ink discharge performance is not impaired.

  This phenomenon is reversible, and when the ink in the nozzle is agitated by ink ejection or the like and the moisture content in the system is recovered, it becomes a redispersed state, and the nozzle clogging due to aggregation is also suppressed.

  In addition, after discharge, water and organic solvent are excluded from the system by permeation and drying, so that at the time of landing, the pigment is first embraced by aggregation of the solubility, and then the film is formed to fix the pigment to some extent. Good scratch resistance can be obtained.

  Next, the polymer compound B according to the present invention will be described.

  The polymer compound B according to the present invention is a polymer compound having a glass transition point (Tg) of −30 ° C. or more and 60 ° C. or less, preferably −20 ° C. or more and 60 ° C. or less, More preferably, it is -10 degreeC or more and 60 degrees C or less. If the glass transition point is too low, the scratch resistance is improved, but conversely, if the images are left on top of each other, adhesion occurs and the image portion is peeled off. Further, if the glass transition point is too high, the scratching property is inferior. The glass transition point (Tg) can be measured by a known method utilizing the fact that the coefficient of thermal expansion and specific heat change discontinuously in the process of changing the temperature.

  The polymer compound B according to the present invention is not particularly limited as long as the glass transition point (Tg) is −30 ° C. or higher and 60 ° C. or lower, but preferably styrene-butadiene, polyacrylic ester, polyurethane, polycarbonate, Polyacrylonitrile, polystyrene, polybutadiene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyamide, polyether, polystyrene-maleic acid, silicon-acrylic, acrylic-modified fluororesin, or These copolymers and salts thereof may be mentioned, and among them, a copolymer selected from at least one of polyester, polystyrene-acryl, polystyrene-butadiene, styrene maleic acid, and SBR latex may be mentioned. The polymer compound B may be obtained by dispersing polymer particles using an emulsifier, or may be dispersed without using an emulsifier. A surfactant is often used as an emulsifier, but a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer in which a solubilizing group is graft-bonded, a single group having a solubilizing group). It is also preferable to use a polymer obtained from a monomer and a monomer having an insoluble part.

  Moreover, soap-free latex can be used in the inkjet ink of the present invention. Soap-free latex is a latex that does not use an emulsifier and a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer in which a solubilizing group is graft-bonded, a solubilizing group) A polymer obtained from a monomer having an insoluble part and a monomer having an insoluble part).

  In recent years, as latex polymer particles, there are also latexes in which core-shell type polymer particles having different compositions at the center and outer edge of the particles are dispersed in addition to the latex in which the polymer particles are uniform throughout. However, this type of latex can also be preferably used.

  In the inkjet ink of the present invention, the average particle size of the polymer compound B is preferably 20 nm or more and 1.0 μm or less, and more preferably 20 nm or more and 600 nm or less from the viewpoint of ink stability and ejection stability. If the average particle size of the polymer fine particles is 1.0 μm or less, a good glossiness of the formed image can be obtained, and if it is 20 nm or more, good water resistance and scratch resistance can be obtained. . The average particle size of the polymer compound B can be determined by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, a laser Doppler method, or the like.

  In the ink-jet ink of the present invention, the content of the polymer compound B according to the present invention is preferably 3% by mass or more and 30% by mass or less. If the content of the polymer compound B according to the present invention is 3% by mass or more, sufficient scratch resistance can be obtained, and if it is 30% by mass or less, the ink viscosity is in an appropriate range and stable ink ejection. Sex can be obtained.

  The polymer compound B according to the present invention has an effect of fixing a pigment by forming a film after being discharged onto a recording medium and then removing water and an organic solvent to some extent from the system by drying and permeation.

  Next, the pigment will be described.

  As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include polycyclic pigments, dye lakes such as basic dye lakes, and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  As a method for dispersing the pigment, for example, various dispersing machines such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used. It is also preferable to use a centrifugal separator or a filter for the purpose of removing the coarse particles of the pigment dispersion.

  In the inkjet ink of the present invention, it is preferable to use a polymer dispersant for dispersing the pigment. There is no restriction | limiting in particular as a polymer dispersing agent which can be used by this invention, Water-soluble resin or water-insoluble resin is used. Examples of these polymers include styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, methacrylic acid, methacrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid. Examples thereof include a polymer composed of a single monomer selected from acid derivatives, a copolymer composed of two or more monomers, and salts thereof. Water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, gelatin, and polyethylene glycol can also be used.

  The content of these water-soluble resins with respect to the total amount of ink is preferably 0.1 to 10% by mass, and more preferably 0.3 to 5% by mass. These water-soluble resins can be used in combination of two or more.

  In the present invention, it is also preferable to use a centrifugal separator or a filter for the purpose of removing coarse particles in the pigment dispersion. The average particle size of the pigment dispersion used in the pigment dispersion type ink jet ink of the present invention is preferably 500 nm or less, more preferably 200 nm or less, and particularly preferably 100 nm or less.

  The content of the pigment used in the inkjet ink of the present invention is preferably 1 to 10% by mass, and more preferably 0.3 to 5% by mass with respect to the total mass of the ink.

  In the inkjet ink of the present invention, water and a water-soluble organic solvent can be preferably used as the aqueous liquid medium.

  Examples of the water-soluble organic solvent preferably used 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), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether, ethylene Glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, propylene glycol monophenyl ether), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenete) Lamin, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2 -Pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), sulfoxides (for example, dimethyl sulfoxide) and the like.

  In the inkjet ink of the present invention, various surfactants can be used from the viewpoint of adjusting the surface tension of the ink or improving the dispersion stability of the pigment.

  The surfactant that can be used in the present invention is not particularly limited, and examples thereof include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl ethers. Nonionic surfactants such as oxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

  In the present invention, a polymer surfactant can also be used. For example, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester. Copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-acrylic acid copolymer Examples thereof include vinyl compounds and vinyl naphthalene-maleic acid copolymers.

  In addition to the above description, the inkjet ink of the present invention is publicly known depending on the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Various additives, such as viscosity modifiers, specific resistance regulators, film forming agents, UV absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust inhibitors, etc. can be appropriately selected and used, For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, 57-74192, 57-87989, 60-72785, 61-146591, JP-A-1-95091 and 3-13376. Fluorescent whitening described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, JP-A-4-219266 and the like An agent etc. can be mentioned.

  The ink-jet ink of the present invention having the above-described configuration preferably has an ink viscosity at 25 ° C. of 10 mPa · s or more and 300 mPa · s or less, more preferably 10 mPa · s or more and 200 mPa · s or less. By setting the ink viscosity to 10 mPa · s or more, preferable ink fluidity at the time of image recording can be obtained, and high image sharpness can be realized. Further, by setting it to 300 mPa · s or less, an appropriate ink viscosity can be obtained, and stable emission from the recording head can be performed.

  Next, the recording method of the present invention will be described.

  In the recording method using the inkjet ink of the present invention, for example, an inkjet recording image is formed by ejecting ink as droplets from an inkjet head based on a digital signal and adhering to a recording medium by a printer loaded with inkjet ink. It is formed.

  The ink jet recording head that can be used in the recording method using the ink jet ink of the present invention may be an on-demand system or a continuous system. In addition, as an ink ejection 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, Any ejection method such as a thermal ink jet type or a bubble jet (registered trademark) type may be used.

  In the recording method of the present invention, the discharge amount of the inkjet ink discharged from the inkjet recording head is set to 0.1 to 1.5 pl per droplet from the viewpoint that the object and effects of the present invention can be fully exhibited. preferable.

  As a recording medium that can be used in the recording method using the ink-jet ink of the present invention, for example, plain paper, coated paper, cast-coated paper, glossy paper, glossy film, OHP film, ink jet dedicated paper, etc. are widely used. Among them, the effect can be exhibited by inkjet image recording using plain paper, coated paper, cast coated paper, glossy paper or the like which is an absorbent support.

The paper, coated paper, there is a non-coated paper, as the coated paper, the coating amount per 1m ² is one side 20g before and after of art paper, 1m ² per coated amount on one side 10g before and after the coated paper Examples include a light-weight coated paper having a coating amount per 1 m ^{2 of} about 5 g on one side, a finely coated paper, a mat-like finished mat-coated paper, a dull-like finished dull-coated paper, and a newsprint. Non-coated paper includes printing paper A using 100% chemical pulp, printing paper B using 70% or more chemical pulp, printing paper C using 40% or more and less than 70% chemical pulp, and printing using less than 40% chemical pulp. Examples thereof include paper D, gravure paper containing mechanical pulp and subjected to calendar treatment. More details are described in detail in “Latest Paper Processing Handbook” edited by the Paper Processing Handbook Editorial Committee, published by Tech Times, “Printing Engineering Handbook” edited by the Japan Printing Society.

  The plain paper is 80 to 200 μm uncoated paper belonging to a part of uncoated paper, special printing paper and information paper. The plain paper used in the present invention includes, for example, high-grade printing paper, intermediate-grade printing paper, low-grade printing paper, thin-like printing paper, fine-coating printing paper, special printing paper such as fine-quality printing paper, foam paper, PPC paper, and others There are information sheets and the like. Specifically, there are the following sheets and various modified / processed sheets using these sheets, but the present invention is not particularly limited thereto. High quality paper and colored high quality paper, recycled paper, copy paper / colored paper, OCR paper, carbonless paper / colored paper, synthetic paper such as YUPO 60, 80, 110 microns, YUPO COAT 70, 90 microns, etc. Coated paper 90kg, Foam mat paper 70, 90, 110kg, Foamed PET 38 microns, Mitsuori-kun (above, Kobayashi recording paper), OK fine paper, New OK fine paper, Sunflower, Phoenix, OK Royal White, Export fine paper ( NPP, NCP, NWP, Royal White) OK Book Paper, OK Cream Book Paper, Cream Premium Paper, OK Map Paper, OK Ishikari, Cucumber, OK Foam, OKH, NIP-N (above, Shin Oji Paper), Gold Wang, Toko, export quality paper, special demand quality paper, book paper, book paper L, light cream book paper, elementary textbook Paper, continuous slip paper, high quality NIP paper, silver ring, gold yang, gold yang (W), bridge, capital, silver ring book, harp, harp cream, SK color, securities paper, opera cream, opera, KYP medical record, silvia HN, Excellent Foam, NPI Foam DX (Nippon Paper), Pearl, Kinryo, Uscream fine paper, Special Book Paper, Super Book Paper, Book Paper, Diamond Foam, Inkjet Foam (Mitsubishi Paper), Carpet V, carpet SW, white elephant, luxury publication paper, cream carpet, cream white elephant, securities / voucher paper, book paper, map paper, copy paper, HNF (above, Hokuetsu), phone book cover, Book paper, cream shirairai, cream shirairaifu, cream shirairaifu, DSK (above, Daishowa Paper), Sendai MP fine paper, Jiang, Thunderbird fine, hanging paper, colored paper base, dictionary paper, cream book, white book, cream fine paper, map paper, continuous slip paper (above, Chuetsu Pulp), OP gold cherry (Chuetsu), gold sand, reference book paper, Replacement certificate paper (white), form printing paper, KRF, white foam, color foam, (K) NIP, fine PPC, Kishu inkjet paper (above, made by Kishu Paper), Taiou, Bright Foam, Kant, Kant White, Dante , CM paper, Dante Comic, Heine, paperback book paper, Heine S, New AD paper, Utrilo Excel, Excel Super A, Kant Excel, Excel Super B, Dante Excel, Heine Excel, Excel Super C, Excel Super D, AD Excel, Excel Super E, New Bright Foam, New Bright NI P (above, made by Daio Paper), Sun Ring, Moon Ring, Cloud Pass, Galaxy, Baiyun, Wyeth, Moon Ring Ace, Baiyun Ace, Cloud Pass Ace (above, Nippon Paper Industries), Taiou, Bright Foam, Bright Nip (Nagoya Pulp), Peony A, Golden Pigeon, Special Peony, White Peony A, White Peony C, Silver Pigeon, Super White Peony A, Light Cream White Peony, Special Medium Quality Paper, White Pigeon, Super Medium Quality Paper, Blue Pigeon, Red Pigeon, Gold Pigeon M Snow Vision, Snow Vision, Gold Pigeon Snow Vision, White Pigeon M, Super DX, Hamanasu O, Red Pigeon M, HK Super Printing Paper (above, Honshu Paper), Stalinden (A・ AW), Star Elm, Star Maple, Star Laurel, Star Poplar, MOP, Star Cherry I, Cherry I Super, Cherry II Super, Star Cherry III, Star Cherry IV, Cherry III Super, Cheri -IV Super (above, made by Maruzumi Paper), SHF (above, made by Toyo Pulp), TRP (above, made by Tokai Pulp) and the like.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, “%” and “part” represent “% by mass” and “part by mass”, respectively, unless otherwise specified.

<< Polymer Compound A: Preparation of Amphiphilic Polymer >>
[Preparation of Amphiphilic Polymer A]
A monomer liquid 1 was prepared by mixing 10 parts of styrene, 10 parts of butyl methacrylate, 10 parts of 2-hydroxyethyl acrylate, and 0.5 part of ethylene glycol dimethacrylate. To a four-necked flask, 0.2 part of dodecyl sulfate and 180 parts of ion-exchanged water were added and dissolved, and then purged with nitrogen. In this, 5 parts of monomer liquid 1 was added, and it heated up at 60 degreeC, stirring. After raising the temperature, 3 parts of a 2% aqueous ammonium persulfate solution was added dropwise, and the temperature was further raised to 80 ° C., and the remaining monomer solution 1 (25.5 parts) and 40 parts of a 2% aqueous ammonium persulfate solution were added over 6 hours. The core part was prepared by dripping and aging for 4 hours.

  While maintaining the above reaction liquid at 80 ° C., a mixture of 120 parts of N-isopropylacrylamide and 1000 parts of ion-exchanged water and 240 parts of 0.4% ammonium persulfate were added dropwise over 4 hours. After aging for a period of time, centrifugal separation was performed to remove coarse particles to prepare a block polymer amphiphilic polymer A having a core-shell structure with an average particle diameter of 200 nm. The average particle diameter was measured using a Zetasizer 1000HS manufactured by Malvern.

[Preparation of Amphiphilic Polymer B]
In the preparation of the amphiphilic polymer A, an average was similarly obtained except that the dropping rate, aging time, and reaction temperature of a mixture of N-isopropylacrylamide, ion-exchanged water and 0.4% ammonium persulfate were appropriately changed. A random polymer amphiphilic polymer B having a core-shell structure with a particle size of 220 nm was prepared.

[Preparation of Amphiphilic Polymer C]
In the preparation of the amphiphilic polymer A, an average was similarly obtained except that the dropping rate, aging time, and reaction temperature of a mixture of N-isopropylacrylamide, ion-exchanged water and 0.4% ammonium persulfate were appropriately changed. A block polymer amphiphilic polymer C having a core-shell structure with a molecular weight of 40,000 was prepared.

[Preparation of Amphiphilic Polymer D]
In the preparation of the amphiphilic polymer A, a block polymer amphiphile having a core-shell structure with an average particle size of 180 nm was used except that 70 parts of the following compound A was used instead of N-isopropylacrylamide. Polymer D was prepared.

(Preparation of Compound A)
In a glass container fitted with a three-way stopcock, 0.38 mol of 2-methoxyethyl vinyl ether, 1.0 mol of ethyl acetate, 4 mmol of 1-butoxyethyl acetate and toluene are added, and the temperature inside the system is lowered to 0 degree. Polymerization was initiated by adding a toluene solution containing 20 mmol of Et1.5AlCl1.5. Two hours later, a saponified product of polyvinyl acetate was added to terminate the polymerization reaction. Next, saponification reaction of the obtained graft polymer was performed to obtain Compound A.

[Preparation of Amphiphilic Polymer E]
In a glass container fitted with a three-way stopcock, 20 mmol of 2-methoxyethyl vinyl ether, 20 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate and 11 ml of toluene were added, and the temperature in the system was 0 degree. Then, 0.5 mmol of Et1.5AlCl1.5 was added and reacted for 6 hours. Next, 20 mmol of 2-ethoxyethyl vinyl ether was added and reacted for 4 hours. Then, the polymerization reaction was stopped with a 0.3% ammonia / ethanol solution, and then diluted with dichloromethane to obtain 0.6 mol / L. Washed with hydrochloric acid and ion-exchanged water. Next, the obtained organic layer was concentrated and dried by an evaporator, and then further vacuum-dried to obtain a water-soluble amphiphilic polymer E.

[Measurement of weight average molecular weight Mw and number average molecular weight Mn]
About each prepared amphiphilic polymer, the average molecular weight, the weight average molecular weight Mw, and the number average molecular weight Mn are measured by GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a solvent, and Mw / Mn is calculated. The results obtained are shown in Table 1.

<Preparation of ink set>
(Preparation of pigment dispersion)
(Preparation of magenta pigment dispersion)
The following additives were mixed and dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads to prepare a magenta pigment dispersion having a magenta pigment content of 15%. The average particle diameter of the magenta pigment particles contained in this magenta pigment dispersion was 83 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I Pigment Red 12 15 parts Jonkrill 61 (acrylic styrene resin, manufactured by Johnson) 9 parts Glycerin 15 parts Ion-exchanged water 61 parts (Preparation of black pigment dispersion)
Carbon black self-dispersion product Cabot-jet 300 manufactured by Cabot was diluted with ion-exchanged water to prepare a black pigment dispersion liquid having a carbon black content of 15%. Obtained. The average particle diameter of the carbon black particles contained in this black pigment dispersion was 153 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

[Preparation of ink set 1]
(Preparation of magenta ink 1)
Magenta pigment dispersion 50 parts Polymer compound A: Amphiphilic polymer A (average molecular weight 80,000, Mw / Mn = 1.4) 1 part Polymer compound B: Takelac W-605 (manufactured by Takeda Pharmaceutical, urethane system) Soap-free latex, solid content 30%, Tg = 25 ° C., average particle size = 150 nm) 15 parts Triethylene glycol monoethyl ether 15 parts 1,2-hexanediol 5 parts Ion-exchanged water 14 parts The solid content of magenta ink 1 is 13%.

(Preparation of black ink 1)
Black pigment dispersion 50 parts Polymer compound A: Amphiphilic polymer A (average molecular weight 80,000, Mw / Mn = 1.4) 1 part Polymer compound B: Takelac W-605 (manufactured by Takeda Pharmaceutical, urethane system) Soap-free latex, solid content 30%, Tg = 25 ° C., average particle size = 150 nm) 15 parts Triethylene glycol monoethyl ether 15 parts 1,2-hexanediol 5 parts Ion-exchanged water 14 parts Magenta ink 1 and black ink 1 constitutes ink set 1.

  The solid content of the black ink 1 is 13%.

[Preparation of ink set 2]
An ink set 2 was obtained in the same manner as in the ink set 1 except that the amphiphilic polymer A used for the preparation of the magenta ink 1 and the black ink 1 was changed to the same amount of the amphiphilic polymer D. .

[Preparation of ink set 3]
Ink set 3 was similarly prepared except that polystyrene maleic acid (molecular weight 10,000, Tg = 40 ° C.) was used in place of Takelac W-605 used for the preparation of magenta ink and black ink. [Preparation of ink set 4]
Ink set 4 was obtained in the same manner as in ink set 1, except that amphiphilic polymer A used for preparing magenta ink 1 and black ink 1 was changed to amphiphilic polymer E of the same amount. .

[Preparation of ink set 5]
Ink set 5 was obtained in the same manner as in ink set 1, except that amphiphilic polymer A used for preparing magenta ink 1 and black ink 1 was changed to amphiphilic polymer B of the same amount. .

[Preparation of ink set 6]
Ink set 6 was obtained in the same manner as in ink set 1 except that the amount of ion-exchanged water used for preparing magenta ink 1 and black ink 1 was adjusted to change the total solid content to 30%. .

[Preparation of ink set 7]
In the ink set 1 described above, a urethane emulsion (Tg = 100 ° C., average particle size: 1.1 μm) was used in place of the bamboo rack W-605 used for the preparation of the magenta ink 1 and the black ink 1. Ink set 7 was obtained.

[Preparation of ink set 8]
In the above ink set 1, the amphiphilic polymer A used for the preparation of the magenta ink 1 and the black ink 1 was changed to the same amount of the amphiphilic polymer C, and Takelac W-605 was removed. Ink set 8 was obtained in the same manner except that the same amount of ion-exchanged water was added.

[Preparation of ink set 9]
Ink set 9 was obtained in the same manner as in ink set 1 except that amphiphilic polymer A used for preparation of magenta ink 1 and black ink 1 was used, except that the same amount of ion-exchanged water was added instead. It was.

[Preparation of ink set 10]
Ink set 9 was obtained in the same manner as in ink set 3 except that the amphiphilic polymer D used for the preparation of the magenta ink and the black ink was used, except that the same amount of ion-exchanged water was added instead.

[Preparation of ink set 11]
(Preparation of magenta ink)
Magenta pigment dispersion 50 parts Triethylene glycol monoethyl ether 15 parts 1,2-hexanediol 5 parts Ion-exchanged water 30 parts (Preparation of black ink)
Black pigment dispersion 50 parts Triethylene glycol monoethyl ether 15 parts 1,2-hexanediol 5 parts Ion-exchanged water 30 parts Ink set 11 was composed of the magenta ink and the black ink.

[Preparation of ink set 12: hot melt ink]
(Preparation of magenta ink)
C. I. Disperse Red 9 2 parts Imidazole 50 parts Octadecyl alcohol 20 parts Cholesterol stearyl ester 20 parts 2,6-tert-butyl-p-cresol 2 parts Each additive is mixed and filled with 0.5% zirconia beads by 50% by volume. A hot melt type magenta ink was prepared by dispersing using a sand grinder.

(Preparation of black ink)
Carbon black 2 parts Imidazole 50 parts Octadecyl alcohol 20 parts Cholesterol stearyl ester 20 parts 2,6-tert-butyl-p-cresol 2 parts Each additive was mixed and filled with 0.5% zirconia beads by 50% by volume. A hot melt type black ink was prepared by dispersing using a sand grinder.

  An ink set 12 was composed of the hot melt type magenta ink and the black ink. In addition, when printing was performed by the method described later using the hot melt type ink set 12, the ink liquid, the ink jet recording head, and the ink flow path were heated and used.

[Preparation of ink set 13: actinic ray curable ink]
(Preparation of magenta ink)
C. I. Pigment Red22 10 parts Azisper PB821 (manufactured by Ajinomoto Fine Techno) 3 parts Aronix M5700 (manufactured by Toagosei Co., Ltd.) 7 parts Ethylene oxide added 1,6 hexanediol acrylate 72 parts 3-methoxybutyl acrylate 8 parts Irgacure 369 (manufactured by Ciba Specialty Chemicals) 5 parts After mixing and stirring each of the above compositions, the resulting solution was filtered with a filter to prepare an actinic ray curable magenta ink.

(Preparation of black ink)
Carbon black (manufactured by Mitsubishi Chemical Corporation, MA-7) 10 parts Ajisper PB821 (manufactured by Ajinomoto Fine Techno) 3 parts Aronix M5700 (manufactured by Toagosei Co., Ltd.) 7 parts Ethylene oxide added 1,6 hexanediol acrylate 72 parts 3-methoxybutyl acrylate 8 Part Irgacure 369 (manufactured by Ciba Specialty Chemicals) 5 parts After mixing and stirring each of the above compositions, the resulting solution was filtered through a filter to prepare an actinic radiation curable black ink.

  The ink set 13, which is an actinic ray curable ink set, was emitted onto a recording medium and then irradiated with ultraviolet rays to cure the ink.

<< Formation and evaluation of inkjet image >>
(Evaluation of decapability)
No cleaning is performed under the condition of using a piezo-type head with a nozzle diameter of 25 microns, a drive frequency of 12 kHz, a nozzle count of 128, and a nozzle density of 180 dpi in an environment of 20 ° C. and 30 RH% and ejecting 8 picoliters per drop. Thereafter, the discharge state of the nozzle was visually observed, and the decapability was evaluated according to the following criteria. The hot melt ink set 12 was evaluated by heating the ink liquid, the inkjet recording head, and the ink flow path to 50 ° C. In the present invention, dpi represents the number of dots per 2.54 cm.

◎: Normal emission from all nozzles ○: Clogging is observed in 1 to 3 nozzles, but recovered by suction cleaning from the nozzle surface △: Clogging is observed in 4 to 10 nozzles, but nozzle surface X: Clogged at 11 nozzles or more, or clogging that could not be recovered by suction cleaning occurred at 1-3 nozzles xx: Clogged at 20 nozzles or more, Or, there are more than 4 nozzles that cannot be recovered by suction cleaning.

  If the evaluation rank was Δ or more, it was judged that the quality was practically acceptable.

(Evaluation of bleed resistance)
<Ink sets 1 to 11>
Using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, using a piezo head with a nozzle diameter of 25 microns, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, art paper (NK Art Kanto, manufactured by Oji Paper) N) and fine paper (FirstClass paper manufactured by Konica Minolta Business Technology Co., Ltd.) were printed and visually observed on a magenta solid surface with a black fine line having a width of 100 μm, and bleed resistance was evaluated according to the following criteria.

◎: The boundary between the fine line and the solid is clear. ○: The boundary is slightly blurred, but there is no problem in practical use. △: The boundary is blurred, but practically acceptable. X: Obvious blurring is observed at the boundary, the line width is about 1.5 times, and this is a quality that is a practical problem. XX: The boundary between the fine line and the solid part is unclear. Quality and extremely low bleed resistance <Ink set 12: Hot melt ink>
In the printing methods of the ink sets 1 to 11, evaluation was performed in the same manner except that the ink liquid, the ink jet recording head, and the ink flow path were heated to 50 ° C.

<Ink set 13: UV curable ink>
An ink jet recording apparatus equipped with a piezo type ink jet nozzle is loaded with the ink set 13 prepared above, and image recording is performed on art paper (NK Art Kanto N manufactured by Oji Paper) and fine paper (FirstClass paper manufactured by Konica Minolta Business Technology). went. The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, and a piezo head. The temperature of the piezo head was adjusted to 60 ° C. The piezo head unit was driven so that multi-size dots of 2 to 15 pl could be ejected at a resolution of 720 × 720 dpi, and each ink was ejected continuously. After landing, 0.1 seconds later, 120 W / cm metal halide lamp (manufactured by Nippon Battery Co., Ltd., MAL 400NL, power supply power 3 kW · hr) was applied to perform a curing treatment.

(Evaluation of scratch resistance)
In the same manner as in the evaluation of bleed resistance, a black fine line having a width of 100 μm was printed on each recording paper, and after 3 minutes, the black fine line image was rubbed with a finger five times, and scratch resistance was evaluated according to the following criteria.

◎: No change in the printed image ○: Slight scratches are observed when observed in detail, but there is no problem in practical use △: A small amount of scratches is observed, but the quality is within the practically acceptable limit ×: Image density decreases with the occurrence of scratches, and is a quality that is a problem in practical use. XX: The formed black thin line image peels off from the recording paper, and is an unacceptable quality (evaluation of water resistance).
In the same manner as in the evaluation of bleed resistance, a black fine line having a width of 100 μm is printed on each recording paper, pure water is dropped after 3 minutes, and after 15 seconds, the black fine line image is rubbed 5 times with a finger, and the following criteria are applied. The water resistance was evaluated according to

◎: No change in the printed image ○: Slight scratches are observed when observed in detail, but there is no problem in practical use △: A small amount of scratches is observed, but the quality is within the practically acceptable limit ×: Image density decreases with the occurrence of scratches, and is a quality that is a problem in practice. XX: The formed black thin line image peels off from the recording paper, and the quality is not acceptable at all. It shows in Table 2.

  As is apparent from the results shown in Table 2, the ink set of the present invention comprising an amphiphilic polymer compound and an ink containing a polymer compound having a glass transition point (Tg) of −30 ° C. or more and 60 ° C. or less. It can be seen that the decapability is improved and images formed on various recording papers are excellent in water resistance, scratch resistance, and bleed resistance.

Claims (6)

Containing at least a pigment, a polymer compound A, and a polymer compound B, the polymer compound A is an amphiphilic polymer compound, and the polymer compound B has a glass transition point (Tg) of −30 ° C. or higher, An ink-jet ink comprising a polymer compound of 60 ° C. or lower. The inkjet ink according to claim 1, wherein the amphiphilic polymer compound is at least one copolymer selected from N-substituted acrylamide, modified vinyl ether, and modified vinyl alcohol. The average molecular weight of the amphiphilic polymer compound is 1,000 or more and 100,000 or less, and the ratio Mw / Mn between the weight average molecular weight Mw and the number average molecular weight Mn is 1.0 or more and 4.0 or less. The inkjet ink according to claim 1 or 2, wherein The inkjet ink according to any one of claims 1 to 3, wherein the amphiphilic polymer compound has an average particle size of 20 nm or more and 1.0 µm or less. The inkjet ink according to claim 1, wherein the polymer compound B has an average particle size of 20 nm or more and 1.0 μm or less. 6. The inkjet ink according to claim 1, wherein the total solid content is 3.0% or more and 40% or less.