JP2013049786A - Ink composition, inkjet recording method, and recorded matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition excellent in storage stability, by which an image excellent in abrasion resistance, producing great colors and reduced in irregular gradation can be obtained even if recording is conducted on any of ink-absorptive, low ink-absorptive and non-ink absorptive media to be recorded, and to provide an inkjet recording method using the same; and a recorded matter on which the image is formed by using the same.SOLUTION: The ink composition is used for the media to be recorded selected from a non-ink absorptive or low ink absorptive recording medium and plain paper and includes: a resin dispersant and a resin-dispersed pigment formed of a color material dispersed by the resin dispersant; and an ethylene-polar monomer copolymer resin having an average particle diameter of 1 μm or lower. Meanwhile, the ink composition does not substantially contain a solvent having a boiling point of 280°C at 1 atmosphere pressure.

Description

  The present invention relates to an ink composition and an ink jet recording method using the same. The present invention also relates to a recorded matter formed from the ink composition.

  A so-called ink jet recording method for recording images and characters with fine ink droplets ejected from nozzles of an ink jet recording head has been conventionally used mainly for recording on the surface of a recording medium that absorbs water, such as paper. . As an ink composition used in such an ink jet recording method, a solution in which a coloring material such as various dyes and / or pigments is dissolved or dispersed in a mixture having a high boiling point organic solvent and water is widely used. Such a high boiling point organic solvent is excellent in low volatility and water retention ability, and thus contributes to prevention of drying of the nozzles of the inkjet recording head.

  On the other hand, not only water-absorbing recording media such as paper, but also ink compositions that can be recorded by ink jet recording methods on non-ink-absorbing or low-absorbing recording media such as printing paper, synthetic paper, and films. Is required. In response to such demands, several ink compositions that can be recorded on a non-ink-absorbing or low-absorbing recording medium have been proposed (see, for example, Patent Documents 1 to 3).

JP 2007-217671 A JP 2008-101192 A JP 2009-67909 A

  However, the conventionally proposed ink composition contains a high-boiling organic solvent, so that the ink drying tends to be slow when recording on a non-ink-absorbing or low-absorbing recording medium. . As a result, the rubbing resistance of recorded images and characters is lowered, and there is a tendency that uneven density tends to occur in a portion with a large amount of ink such as a solid portion.

  On the other hand, an ink composition that does not contain a high-boiling organic solvent cannot prevent the nozzles of an inkjet recording head from being dried, tends to cause nozzle clogging, and tends to reduce the storage stability of the ink. was there.

  Therefore, the present invention is excellent in abrasion resistance when recording on any recording medium that is ink-absorbing, ink-low-absorbing, or non-ink-absorbing, and has high color development and reduced shading unevenness. Another object of the present invention is to provide an ink composition excellent in storage stability and an ink jet recording method using the same. Another object of the present invention is to provide a recorded matter on which an image is formed using the ink composition.

The present invention has been made in view of the above problems, and is as follows.
(1) An ink composition used for a recording medium selected from a non-ink-absorbing or low-absorbing recording medium and plain paper,
A resin-dispersed pigment formed from a resin dispersant and a colorant dispersed by the resin dispersant, and an ethylene-polar monomer copolymer resin having an average particle size of 1 μm or less,
An ink composition containing substantially no solvent having a boiling point of 280 ° C. or higher at 1 atm.
(2) The ink composition according to (1), wherein the ratio of the colorant: resin dispersant is 2: 1 to 5: 1 in the resin dispersion type pigment.
(3) The ink composition according to (1) or (2), wherein the resin dispersant is an acrylic resin.
(4) The ink composition according to (3), wherein the acrylic resin has an acid value of 40 or more and 100 or less.
(5) The ink composition according to any one of (1) to (4), wherein the resin-dispersed pigment has an average particle size of 20 nm to 500 nm.
(6) The ink composition according to any one of (1) to (5), wherein the copolymer resin is an ethylene-vinyl acetate copolymer resin having an MFT of less than 100 ° C.
(7) The ink composition according to any one of (1) to (6), further including polymer particles having an average particle diameter of 5 nm or more and less than 200 nm.
(8) The ink composition according to (7), wherein the polymer particles are polyethylene wax particles having an MFT of 100 ° C. or higher.
(9) The ink composition according to any one of (1) to (8), further including glycol ethers having an HLB value calculated by the Davis method in the range of 4.2 to 8.0. .
(10)
An image is formed on the recording medium selected from non-ink-absorbing or low-absorbing recording medium and plain paper using the ink composition according to any one of (1) to (9) above. Inkjet recording method.
(11) A recorded matter recorded with the ink composition according to any one of (1) to (10) above.

  The ink composition of the present invention can be applied to an ink jet recording method, and when recording on any recording medium of ink absorptivity, ink low absorptivity, and ink non-absorptivity by the ink jet recording method. In addition, an image having excellent abrasion resistance, high color development and reduced density unevenness is obtained, and storage stability is also excellent.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The embodiment described below describes an example of the present invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

1. Ink composition The ink composition according to the present embodiment is an ink composition used for a recording medium selected from non-ink-absorbing or low-absorbing recording medium and plain paper, and includes a resin dispersant and the resin dispersant. A resin-dispersed pigment formed from a colorant dispersed with a resin dispersant and an ethylene-polar monomer copolymer resin having an average particle size of 1 μm or less and a boiling point of 280 ° C. under 1 atm. It is characterized by not containing the above solvent substantially.

  The ink composition according to the present embodiment further includes polymer particles having an average particle size of 5 nm or more and less than 200 nm, and glycol ethers having an HLB value calculated by the Davis method in the range of 4.2 to 8.0. It is preferable to comprise one or more selected from the above.

  As described above, the ink composition according to the present embodiment does not substantially contain a solvent having a boiling point of 280 ° C. or higher under 1 atm. When a solvent having a boiling point of 280 ° C. or higher at 1 atm is included, the drying property of the ink composition is significantly lowered. As a result, not only the density unevenness of the image is noticeable but also the fixing property of the image cannot be obtained on various recording media, particularly non-ink-absorbing or low-absorbing recording media. Examples of the solvent having a boiling point of 280 ° C. or higher at 1 atm include glycerin having a boiling point of 290 ° C. at 1 atm.

  In the present invention, “substantially does not contain A” means that A is not intentionally added when the ink composition is produced, and does not contain more than an amount that fully exhibits the significance of adding A. Show. Specific examples of “substantially free” include, for example, 1.0% by mass or more, preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0% by mass. 0.05% by mass or less, particularly preferably 0.01% by mass or less, and most preferably 0.001% by mass or less.

  In the present specification, the “average particle size” means a volume-based average particle size unless otherwise specified. The average particle diameter can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. As the laser diffraction type particle size distribution measuring device, for example, a particle size distribution meter (for example, “Microtrack UPA Series” manufactured by Nikkiso Co., Ltd.) based on the dynamic light scattering method can be used.

Hereinafter, each component used for this Embodiment is demonstrated in detail.
1.1. Color Material The ink composition according to the present embodiment includes a color material. Examples of the color material include dyes and pigments, and pigments are preferable from the viewpoint of water resistance, gas resistance, light resistance, and the like.

  As such a pigment, any of known inorganic pigments, organic pigments, and carbon black can be used. These pigments are preferably contained in the range of 0.5% by mass or more and 20% by mass or less, more preferably in the range of 1% by mass or more and 10% by mass or less, based on the total amount of the ink composition. It is most preferable that it is contained in the range of 8% by mass or more.

  In order to apply the pigment to the ink composition, the pigment needs to be stably dispersed and held in water. As the method, it is dispersed with a resin dispersant such as a water-soluble resin and / or a water-dispersible resin (hereinafter, the pigment treated by this method is referred to as “resin-dispersed pigment”).

  Examples of the resin dispersant used for the resin dispersion pigment include polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, and styrene. -Acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid- Acrylate ester copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer Polymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic Examples thereof include acid copolymers and salts thereof. Among these, a copolymer of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and a polymer composed of a monomer having both a hydrophobic functional group and a hydrophilic functional group are preferable. As the form of the copolymer, any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer can be used. Among them, the resin dispersant is preferably an acrylic resin from the viewpoint of achieving both dispersion stability and fixability.

  Examples of the salt include basic compounds such as ammonia, ethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolamine, triethanolamine, triisopropanolamine, aminomethylpropanol, and morpholine. Of the salt. The addition amount of these basic compounds is not particularly limited as long as it is equal to or more than the neutralization equivalent of the resin dispersant.

  The molecular weight of the resin dispersant is preferably in the range of 1,000 to 100,000 as the weight average molecular weight, and more preferably in the range of 3,000 to 10,000. When the molecular weight is in the above range, the pigment is stably dispersed in water, and viscosity control when applied to the ink composition is easy.

  The acid value is preferably in the range of 20 to 300, more preferably in the range of 30 to 150, and most preferably in the range of 40 to 100. When the acid value is within this range, the dispersibility of the pigment particles in water can be stably ensured, and the water resistance and color development of the recorded matter recorded with the ink composition using the pigment particle are good. Become.

  In the resin-dispersed pigment, the ratio of the colorant: resin dispersant is preferably 2: 1 to 5: 1 by mass ratio, and particularly preferably 2: 5 to 4: 1. When the ratio of the colorant and the resin dispersant is within the above range, both the dispersion stability of the colorant and the high color developability of the printed image can be achieved, and excellent ink jet discharge characteristics can be secured.

  Commercially available products can be used as the resin dispersant described above. Specifically, Joncryl 67 (weight average molecular weight: 12,500, acid value: 213), Joncryl 678 (weight average molecular weight: 8,500, acid value: 215), Joncryl 586 (weight average molecular weight: 4,600) , Acid value: 108), joncryl 611 (weight average molecular weight: 8,100, acid value: 53), joncryl 680 (weight average molecular weight: 4,900, acid value: 215), joncryl 682 (weight average molecular weight) : 1,700, acid value: 238), joncryl 683 (weight average molecular weight: 8,000, acid value: 160), joncryl 690 (weight average molecular weight: 16,500, acid value: 240) , Manufactured by BASF Japan Ltd.).

  The resin-dispersed pigments described above are dispersed in water as follows: for resin-dispersed pigments, pigment, water, and resin dispersant, for surfactant-dispersed pigments, pigment, water, surfactant, and surface-treated pigment Surface treatment pigment, water, and water-soluble organic solvent / neutralizing agent, etc. are added to each as necessary. Ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill In addition, it can be performed by a conventionally used disperser such as an ang mill. In this case, the particle size of the pigment is more preferably in the range of 30 nm to 300 nm, more preferably in the range of 50 nm to 180 nm, and most preferably in the range of 50 nm to 130 nm, until the average particle size is in the range of 20 nm to 500 nm. It is preferable to disperse the pigment until it reaches the desired level in order to ensure the dispersion stability of the pigment in water and the color development of the recorded image.

1.2. Ethylene-Polar Monomer Copolymer Resin The ink composition according to the present embodiment includes an ethylene-polar monomer copolymer resin. When the copolymer resin is in the form of particles, the average particle diameter is in the range of 1 μm or less from the viewpoint of ensuring the storage stability and ejection stability of the aqueous ink composition. More preferably, it is the range of 50 nm-600 nm, More preferably, they are 150 nm or more and 350 nm or less.

  The ethylene-polar monomer copolymer resin is preferably in the form of particles, and particularly preferably contained in a fine particle state (that is, an emulsion state or a suspension state). By containing the ethylene-polar monomer copolymer resin in a fine particle state, it is easy to adjust the viscosity of the ink composition to an appropriate range in the ink jet recording method, and it is easy to ensure storage stability and ejection stability.

  As the ethylene-polar monomer copolymer resin, those obtained by known materials and methods can be used. Commercially available products can also be used, such as (Evaflex 220; made by Mitsui DuPont Polychemical), Polysol S-5, S-6, S-5500 (above trade names, Showa Polymer Co., Ltd.), Bond Vinyl acetate polymer resin such as CH2, CH3, CH5, CH7, CH18 (above trade name, manufactured by Konishi Co., Ltd.), or Panflex OM-4000, OM-4200 (above trade name, manufactured by Kuraray Co., Ltd.), Sumika Flex 201HQ, 305HQ, 355HQ, 400HQ, 401HQ, 408HQ, 410HQ, 450HQ, 455HQ, 456HQ, 460HQ, 465HQ, 467HQ, 470HQ, 510HQ, 520HQ, 752, 755 (above trade name, manufactured by Sumitomo Chemical Co., Ltd.), Denka EVA tex 50, 55N, 59 60, 65, 70, 75, 80, 81, 82, 88, 90, 100, 170 (above trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.), Chemipearl V100, V200, V300, EV210H (above trade name, Mitsui Chemicals, Inc.) Made by company), ViniBran 3302, 1570, 1570J, 1570K, 1570L, 1540K, 1540L, A20J2, A23J1, A23J2, A34G2, A68J1, 4495LL, A23P2E, A68J1N, A70J9, B90J9, TLE-383, 4018, A22J7 , 1157, 1502B, 1588C, 1588CL, 1588C, 1588FD, 1080, 1087, 1090B, 1571, A22J7-F2, 4470, 4485LL, 4495LL, 1042F, 1008 Ethylene-vinyl acetate copolymer resins such as GV-6170, GV-6181, 1002, 1017-AD, KM-01, 1225, 1245L (above trade names, manufactured by Nissin Chemical Industry Co., Ltd.), or SUMIKAFLEX 900HL , 950HQ, 951HQ (trade names, manufactured by Sumitomo Chemical Co., Ltd.) and other ethylene / vinyl acetate / (meth) acrylic acid copolymer resins; or SUMIKAFLEX 850HQ (trade name, manufactured by Sumitomo Chemical Co., Ltd.) Examples thereof include commercially available ethylene-polar monomer copolymer resins such as ethylene / vinyl acetate / vinyl chloride copolymer resins.

The ethylene-polar monomer copolymer resin may be either a homopolymer or a copolymer, and may have a single phase structure or a multiphase structure (core-shell type).
In the present invention, an ethylene-vinyl acetate copolymer resin obtained by mixing about 8 to 35% by mass of an ethylene monomer with a polar monomer and emulsion-polymerizing the mixture under high pressure is preferable. It is superior in water resistance, weather resistance, and alkali resistance to vinyl acetate resin alone, and also improves adhesion to polyolefin films such as polypropylene and polyethylene, and abrasion resistance. The ethylene-vinyl acetate copolymer resin preferably has a vinyl acetate content of 8 to 35% by mass, particularly 12 to 30% by mass from the standpoints of media adhesion, abrasion resistance, water resistance and the like.

  The copolymer resin is preferably an ethylene-polar monomer copolymer resin having an MFT of less than 100 ° C. By including an ethylene-polar monomer copolymer resin having an MFT of less than 100 ° C., it is possible to efficiently fix a printed image on a recording medium by a drying process described later. The MFT of the ethylene-polar monomer copolymer resin is preferably in the range of −40 ° C. to 80 ° C., more preferably in the range of 5 ° C. to 40 ° C.

  The content of the ethylene-polar monomer copolymer resin described above is preferably in the range of 0.5% by mass to 5% by mass in terms of solid content with respect to the total amount of the ink composition. By being within this range, even on a non-ink-absorbing or low-absorbing recording medium, the ink composition according to the present embodiment and a second step (drying step) to be described later as a preferred inkjet recording method, In combination, the ink composition can be solidified and fixed.

1.3. Resins other than ethylene-polar monomer copolymer resin The ink composition according to the present embodiment may contain a resin other than the above-described ethylene-polar monomer copolymer resin. Such resins mainly include polymer particles that impart lubricity to the surface of the recorded matter recorded in the second step (drying step) in the ink jet recording method described later and improve the scratch resistance, and an ethylene-polar monomer. And polymer particles having a function of assisting the formation of a resin film by the polymer resin and promoting the fixing effect of the coloring material on the recording medium. Hereinafter, the polymer particles will be described in detail.

1.3.1 Polymer Particles The ink composition according to the present embodiment includes polymer particles. The average particle diameter of the polymer particles is preferably in the range of 5 nm to less than 200 nm, more preferably in the range of 20 nm to 100 nm, from the viewpoint of ensuring the storage stability and ejection stability of the aqueous ink composition.
Hereinafter, the polymer particles will be described in detail.

  Examples of the components constituting the polymer particles include plant and animal waxes such as carnauba wax, candeli wax, beeswax, rice wax, lanolin; paraffin wax, microcrystalline wax, polyethylene wax, polyethylene oxide wax, polytetrafluoroethylene. Petroleum waxes such as wax and petrolatum; mineral waxes such as montan wax and ozokerite; natural waxes such as carbon wax, Hoechst wax, polyolefin wax and stearamide, and natural such as α-olefin / maleic anhydride copolymer Synthetic wax emulsions and blended waxes can be used alone or in combination. Among these, preferred wax types are paraffin wax and polyolefin wax, particularly polyethylene wax and polypropylene wax. Paraffin wax and polyolefin wax may be used in combination. As the wax particles, commercially available products can be used as they are. For example, Nopcoat PEM17 (trade name, manufactured by San Nopco), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals), AQUACER 515, AQUACER 539, AQUACER 507 (trade names, Big Chemie Japan Co., Ltd.).

  It is preferable that MFT contains polymer particles having a temperature of 100 ° C. or higher. By adding such polymer particles, synergistically with the ethylene-polar monomer copolymer resin having the effect of forming a resin film and fixing it on the recording medium mainly in the second step (drying step) in the ink jet recording method described later. Thus, there is an effect of imparting lubrication to the surface of the recorded matter and improving the abrasion resistance. It is preferable that the MFT is 100 ° C. or higher because the frictional heat generated when the surface is rubbed does not cause melting or deformation of the polymer particles, and sufficient lubrication can be imparted.

  The content of the polymer particles described above is preferably in the range of 0.1% by mass to 5% by mass in terms of solid content with respect to the total amount of the ink composition. By being within this range, even on a non-ink-absorbing or low-absorbing recording medium, in synergy with the above-described ethylene-polar monomer copolymer resin, the ink composition according to the present embodiment, By combining a second step (drying step) described later as a preferred ink jet recording method, the ink composition can be solidified and fixed.

  The reason why the recorded image has good abrasion resistance when the above-described ethylene-polar monomer copolymer resin and polymer particles are used in combination is not clear yet, but is presumed as follows. The component constituting the ethylene-polar monomer copolymer resin has a good affinity for non-ink-absorbing or low-absorbing recording media and water-insoluble colorants, so the second step (drying step) When the resin film is formed, the colorant is wrapped and firmly fixed on the recording medium. On the other hand, the component of the polymer particles is also present on the surface of the resin film and has a characteristic of reducing the frictional resistance on the surface of the resin film. This makes it possible to form a resin film that is less likely to be scraped off by external rubbing and that is difficult to peel off from the recording medium, and is thus presumed to improve the abrasion resistance of the recorded image.

  When the ethylene-polar monomer copolymer resin and the polymer particles are used in combination, the content ratio is in the range of ethylene-polar monomer copolymer resin: polymer particles = 1: 1 to 5: 1 on a mass basis in terms of solid content. Preferably there is. Within this range, the above-described mechanism works well, and the recorded image has good abrasion resistance.

1.3.2 Resin Particles The present invention includes resin particles other than the ethylene-polar monomer copolymer resin or polymer particles in order to further improve the fixing property and abrasion resistance of the coloring material to the recording medium. You may go out.
Preferred resin particles include those selected from the group consisting of acrylic resins, methacrylic resins, styrene resins, urethane resins, acrylamide resins, epoxy resins, and mixtures thereof. These resins may be used as homopolymers or copolymers, and may be used as either a single-phase structure or a multi-phase structure (core-shell type). More specifically, for example, a polyacrylate ester or a copolymer thereof is used. Polymer, polymethacrylic acid ester or copolymer thereof, polyacrylonitrile or copolymer thereof, polycyanoacrylate, polyacrylamide, polyacrylic acid, polymethacrylic acid, polyethylene, polypropylene, polybutene, polyisobutylene, polystyrene or copolymers thereof Polymer, petroleum resin, chroman indene resin, terpene resin, polyvinyl alcohol, polyvinyl acetal, polyvinyl ether, polyvinyl chloride or copolymer thereof, polyvinylidene chloride, fluororesin, fluororubber, polyvinyl chloride Carbazole, polyvinyl pyridine, polyvinyl imidazole, polybutadiene or a copolymer, polychloroprene, polyisoprene, natural resins. Of these, those having both a hydrophobic part and a hydrophilic part in the molecular structure are particularly preferred.
As the resin particles as described above, those obtained by known materials and methods can be used. For example, commercially available products can be used. For example, Microgel E-1002, Microgel E-5002 (trade name, manufactured by Nippon Paint Co., Ltd.), Boncourt 4001, Boncourt 5454 (tradename, Dainippon Ink Chemical Co., Ltd.) SAE 1014 (trade name, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (trade name, manufactured by Seiden Chemical Co., Ltd.), Jongkrill 7100, Jongkrill 390, Jongkrill 711, Jongkrill 511, Jongkrill 7001 , John Krill 632, John Krill 741, John Krill 450, John Krill 840, John Krill 74J, John Krill HRC-1645J, John Krill 734, John Krill 852, John Krill 7600, John Krill 775, John Krill 53 J, John Crill 1535, John Crill PDX-7630A, John Crill 352J, John Crill 352D, John Crill PDX-7145, John Crill 538J, John Crill 7640, John Crill 7641, John Crill 631, John Crill 790, John Crill 780, Jonkrill 7610 (trade name, manufactured by BASF Japan Ltd.) and the like.

  Said resin particle is obtained by the method shown below, Any method may be sufficient and it may combine a some method as needed. As the method, a polymerization catalyst (polymerization initiator) and a dispersing agent are mixed in a monomer of a component constituting a desired polymer particle, and polymerization (that is, emulsion polymerization) is performed. A method of obtaining particles by dissolving in a water-soluble organic solvent and mixing the solution in water and then removing the water-soluble organic solvent by distillation, etc., dissolving the polymer in a water-insoluble organic solvent and dissolving the solution together with the dispersant in an aqueous solution And the like to obtain particles by mixing. Said method can be suitably selected according to the kind and characteristic of the polymer to be used. The dispersant that can be used for dispersing the polymer in a fine particle state is not particularly limited, but anionic surfactants (for example, sodium dodecylbenzenesulfonate, sodium lauryl phosphate, polyoxyethylene alkyl ether sulfate) Ammonium salts, etc.), nonionic surfactants (for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers). These may be used alone or in combination of two or more. It can be used by mixing.

  The minimum film-forming temperature (hereinafter referred to as “MFT”) of the components constituting the resin particles described above preferably includes at least one of those having a temperature of 0 ° C. or higher. By including the component whose MFT is 0 degreeC or more, the effect in which a stronger resin film is formed in the 2nd process (drying process) mentioned later is high. Therefore, the rub resistance of the recorded image is further improved. Also, ink clogging at the nozzle tip of the ink jet recording head is unlikely to occur. On the other hand, when resin particles composed only of components having an MFT of less than 0 ° C. are used, it is difficult to form a strong resin film even after the second step (drying step) described below, and the recorded image has poor abrasion resistance. It may become. Further, ink solidified material is generated at the nozzle tip, and clogging is likely to occur.

1.4. Glycol ethers The ink composition according to the present embodiment preferably contains glycol ethers having an HLB value calculated by the Davis method in the range of 4.2 to 8.0. The ink composition according to the present embodiment includes the glycol ethers satisfying the above-described HLB value range, so that the wettability / penetration speed can be controlled without being significantly affected by the recording medium type. As a result, a clear image with little density unevenness can be recorded on various recording media, in particular, non-ink-absorbing or low-absorbing recording media.

  Here, the HLB value of the glycol ethers used in the present embodiment is a value for evaluating the hydrophilicity of the compound proposed by Davis et al., For example, the document “JT Davies and EK Rideal,“ It is a numerical value obtained by the Davis method defined in Interface Phenomena “2nd ed. Academic Press, New York 1963”, which is a value calculated by the following equation (1).

HLB value = 7 + Σ [1] + Σ [2] (1)
(However, [1] represents the number of hydrophilic groups and [2] represents the number of hydrophobic groups.)

  Table 1 below exemplifies the number of representative hydrophilic groups and hydrophobic groups.

  The glycol ethers contained in the ink composition according to the present embodiment have an HLB value calculated by the Davis method in the range of 4.2 to 8.0, and in the range of 5.8 to 8.0. Preferably there is. When the HLB value is 4.2 or more, the hydrophobicity of the glycol ethers is not increased, and the affinity with water as the main solvent is improved, so that the storage stability of the ink is improved. When the HLB value is 8.0 or less, the effect of wettability / penetration to the recording medium becomes sufficient, and unevenness in the density of the image is suppressed, which is preferable. In particular, the effect of wettability on a non-ink-absorbing or low-absorbing recording medium that is a hydrophobic surface tends to be significant.

  Specific examples of such glycol ethers include ethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monoisohexyl ether, diethylene glycol monohexyl ether, triethylene glycol monohexyl ether, diethylene glycol monoisohexyl ether, triethylene glycol Ethylene glycol monoisohexyl ether, ethylene glycol monoisoheptyl ether, diethylene glycol monoisoheptyl ether, triethylene glycol monoisoheptyl ether, ethylene glycol monooctyl ether, ethylene glycol monoisooctyl ether, diethylene glycol monoisooctyl ether, triethylene glycol Monoisooctylate , Ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, triethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono -2-methylpentyl ether, diethylene glycol mono-2-methylpentyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl Examples include ether. These can be used individually by 1 type or in mixture of 2 or more types.

  Among the glycol ethers exemplified above, the alkyl group contained in the glycol ethers preferably has a branched structure. By containing a glycol ether having an alkyl group having a branched structure, it is possible to record a clear image with little shading unevenness, particularly on a non-ink-absorbing or low-absorbing recording medium. Specifically, ethylene glycol monoisobutyl ether, ethylene glycol monoisohexyl ether, diethylene glycol monoisohexyl ether, triethylene glycol monoisohexyl ether, ethylene glycol monoisoheptyl ether, diethylene glycol monoisoheptyl ether, triethylene glycol monoiso Heptyl ether, ethylene glycol monoisooctyl ether, diethylene glycol monoisooctyl ether, triethylene glycol monoisooctyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, triethylene glycol mono-2-ethylhexyl ether , Diethylene glycol mono-2-ethyl Inch ether, ethylene glycol mono-2-ethyl pentyl ether, ethylene glycol mono-2-methylpentyl ether, diethylene glycol mono-2-methylpentyl ether, and the like.

  Among the branched structures of the alkyl group contained in the glycol ethers, a 2-methylpentyl group, a 2-ethylpentyl group, and a 2-ethylhexyl group are more preferable, and a 2-ethylhexyl group is particularly preferable from the viewpoint of further improving color developability. preferable. Specifically, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, triethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylpentyl ether, ethylene glycol mono-2-ethylpentyl ether , Ethylene glycol mono-2-methylpentyl ether, diethylene glycol mono-2-methylpentyl ether, etc., ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, triethylene glycol mono-2-ethylhexyl ether Etc. are particularly preferred.

  The content of the glycol ethers is based on the total amount of the ink composition from the viewpoint of improving the wettability and penetrability to the recording medium and reducing unevenness in density, and ensuring ink storage stability and ejection reliability. On the other hand, it is preferably contained in the range of 0.05 mass% or more and 6 mass% or less. When it is 0.05% by mass or more, the wettability, penetrability, and drying property of the ink composition are sufficient, and a clear image can be obtained, and the printing density (coloring property) is sufficient, which is preferable. On the other hand, if it is 6% by mass or less, the viscosity of the ink is not increased and the clogging of the head does not occur, and it is completely dissolved in the ink composition and storage stability is obtained.

1.5. Alkyl polyols The ink composition according to the present embodiment preferably contains an alkyl polyol having a boiling point within the range of 180 to 230 ° C. at 1 atm. The ink composition according to the present embodiment includes alkyl polyols satisfying the above-described boiling range, thereby controlling the wettability, penetrability, and drying properties of the ink composition without being significantly affected by the type of recording medium. Can do. As a result, it is possible to record images having excellent fixability on various recording media, and it is possible to reduce clogging of the nozzles of the inkjet recording head.

  Further, the alkyl polyols in the ink composition according to the present embodiment are incorporated into an ink vehicle of a glycol ether having an HLB value calculated by the Davis method in the range of 4.2 to 8.0. It has the characteristics of a solubilizer.

The alkyl polyols contained in the ink composition according to the present embodiment have a boiling point within a range of 180 to 230 ° C. under 1 atm, and contain at least one kind of polyols within a range of 190 to 220 ° C. It is preferable.
When the boiling point of the alkyl polyols contained in the ink composition under 1 atm is 180 ° C. or higher, the drying property of the ink composition does not become too high, and clogging of the nozzles of the inkjet recording head hardly occurs. preferable. When the boiling point at 1 atm is 230 ° C. or lower, the drying property of the ink composition does not become too low, and unevenness of image density is not noticeable, and the fixability of the image is improved.

  Specific examples of the alkyl polyols having a boiling point within the range of 180 to 230 ° C. under 1 atm include 1,2-propanediol [188 ° C.], 1,3-propanediol [210 ° C.], 1,2 -Butanediol [194 ° C], 1,3-butanediol [208 ° C], 1,4-butanediol [230 ° C], 1,2-pentanediol [210 ° C], 3-methyl-1,3-butane Diol [203 ° C.], 2-ethyl-2-methyl-1,3-propanediol [226 ° C.], 2-methyl-1,3-propanediol [214 ° C.], 2-methyl-2-propyl-1, 3-propanediol [230 ° C], 2,2-dimethyl-1,3-propanediol [210 ° C], 2-methylpentane-2,4-diol [197 ° C], dipropylene glycol [230 ° C] ], 1,2-heptanediol [227 ° C.] and the like. In addition, the numerical value in a parenthesis represents the boiling point under 1 atmosphere.

  The content of the alkyl polyols is based on the total amount of the ink composition from the viewpoint of improving the wettability and penetrability to the recording medium and reducing unevenness in density, and ensuring ink storage stability and ejection reliability. On the other hand, it is preferably contained in the range of 5 mass% or more and 20 mass% or less. When the content is 5% by mass or more, the storage stability of the ink composition does not decrease, and the drying property of the ink composition does not increase, so that the nozzles of the inkjet recording head are not clogged, which is preferable. . On the other hand, if it is 20% by mass or less, the drying property of the ink composition does not decrease, the uneven density of the image does not stand out, and the fixing property of the image does not decrease, which is preferable. Moreover, it becomes difficult to adjust the viscosity of the ink composition to a range suitable for the ink jet recording method.

  Among the above alkyl polyols, 1,2-linear alkyldiols having a carbon number in the range of 3 to 7 (hereinafter sometimes abbreviated as “C3-7”) have the above functions. In addition, in synergy with the glycol ethers that can be contained in the ink composition according to the present embodiment, the wettability of the ink composition with respect to the recording medium is further increased and the wettability is uniformly increased, and the permeability is further increased. Have For this reason, the ink composition can be further reduced in density unevenness by adding C3-7 1,2-linear alkyldiols to the ink composition. Further, C3-7 1,2-linear alkyldiols are excellent in compatibility with the glycol ethers described above. Here, “compatible” means that among the components constituting the ink composition, in the ink composition using water as the main solvent, the glycol ethers and C3-7 1,2-linear alkyldiols The combination of each material and the ratio of each material is such that the mixture of the materials is completely dissolved. By including a C3-7 1,2-linear alkyldiol having excellent compatibility with the glycol ethers in the ink composition, the solubility of the glycol ether in the ink composition can be increased, and the ink Improvement of storage stability and discharge stability can be realized. Moreover, since it becomes easy to increase the content of the glycol ethers in the ink composition, it is possible to contribute to further improving the quality of the recorded image.

  Specific examples of C3-7 1,2-linear alkyldiols having such characteristics include 1,2-bropandiol [188 ° C.], 1,2-butanediol [194 ° C.], 1,2 -Pentanediol [210 ° C], 1,2-hexanediol [224 ° C], 1,2-heptanediol [227 ° C] and the like can be mentioned. Among these, in particular, C2-C6 (carbon number is 4-6) 1,2-linear alkyldiol such as 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol is water. From the viewpoint of solubility in water and compatibility with the glycol ethers, moisture retention against nozzle clogging, and drying of printed images, 50% by mass or more of alkyl polyols in the ink is preferably C4. It is preferably a 1,2-linear alkyl diol having ˜6 (having 4 to 6 carbon atoms).

  The addition amount of C3-7 1,2-linear alkyldiols is selected from the viewpoints of compatibility with the glycol ethers, storage stability of the ink composition, and ejection stability, particularly from the viewpoint of preventing clogging. Preferably it is the range of 5 mass%-30 mass% with respect to the composition whole quantity, Most preferably, it is the range of 10 mass%-15 mass%. In particular, in the second step (drying step) of the ink jet recording method to be described later using the ink composition, the evaporation and scattering rate of C3-7 1,2-linear alkyldiols is sufficiently high. There is an extraordinary effect that the recorded matter is dried quickly and the recording speed is improved. There is no problem in terms of odor in each process.

1.6. Pyrrolidone derivative The ink composition according to the present embodiment may further contain a pyrrolidone derivative. The ink composition containing the ink composition, particularly when using a film-based non-ink-absorbing recording medium made of polyvinyl chloride, polyethylene terephthalate, polyethylene, polypropylene, etc. Thus, the wet spread is uniform and a clear and clear image with little shading unevenness and bleeding can be obtained even in a solid image. The reason for this is not clear, but the pyrrolidone structure contained in the molecular skeleton structure of the pyrrolidone derivative has a high affinity for the recording medium of the film system, so that the wettability to the film is improved even in the ink composition containing it. Inferred. In addition, since the pyrrolidone derivative is excellent in compatibility with the glycol ethers and alkyl polyols, the ink composition according to the present embodiment can achieve both excellent storage stability and ejection stability. Furthermore, since the pyrrolidone derivative functions as a film component after drying, it contributes to improving the abrasion resistance of the recorded image.

  Examples of pyrrolidone derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, and 5-methyl-2-pyrrolidone. Is mentioned.

  The pyrrolidone derivative described above can be added as much as necessary to give desired characteristics to the ink composition according to the present embodiment, but the preferable addition amount is 0.1% by mass with respect to the total amount of the ink composition. It is the range of 10 mass%, More preferably, it is the range of 1 mass%-8 mass%. Within this range, the above-described characteristics can be imparted to the ink composition, and the viscosity of the ink composition can be easily adjusted to an appropriate range in the ink jet recording system.

1.7. Surfactant The ink composition according to the present embodiment may further contain a surfactant. By containing a surfactant in the ink composition, an action of uniformly spreading on the recording medium is imparted. This makes it possible to record a clear image with little shading unevenness.

  The surfactant having such an effect is preferably a nonionic surfactant. Among the nonionic surfactants, silicone surfactants and / or those having excellent compatibility and synergistic effect between the glycol ethers and the alkyl polyols included in the ink composition according to the present embodiment are particularly preferable. An acetylene glycol surfactant is more preferred.

  As the silicone surfactant, a polysiloxane compound or the like is preferably used, and examples thereof include polyether-modified organosiloxane. More specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (above trade names, manufactured by Big Chemie Japan Co., Ltd.), KF-351A, KF- 352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF- 6012, KF-6015, KF-6017 (above trade names, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. The content of the silicone surfactant is preferably 1.0% by mass or less based on the total amount of the ink composition.

  The acetylene glycol-based surfactant is superior to other nonionic surfactants in its ability to keep the surface tension and the interfacial tension properly, and has almost no foaming property. As a result, the ink composition containing the acetylene glycol surfactant can appropriately maintain the surface tension and the interfacial tension with the printer member in contact with the ink such as the head nozzle surface. When applied, ejection stability can be improved. In addition, since the acetylene glycol surfactant acts as a good wettability / penetrant for the recording medium in the same manner as the glycol ethers and the alkyl polyols, recording is performed with an ink composition containing the same. The resulting image is a high-definition image with little shading and blurring. The content of the acetylene glycol surfactant is preferably 1.0% by mass or less based on the total amount of the ink composition.

  As acetylene glycol surfactants, for example, Surfinol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37 , CT111, CT121, CT131, CT136, TG, GA, DF110D (all trade names, manufactured by Air Products and Chemicals Inc.), Olfin B, Y, P, A, STG, SPC, E1004, E1010, PD- 001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all trade names, Kawaken Fine Chemical Co., Ltd.).

1.8. Water The ink composition according to the present embodiment comprises water. Water is a main medium of the ink composition, and is a component that is evaporated and scattered in a second step (drying step) described later. The water is preferably water from which ionic impurities such as pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water or ultrapure water are removed as much as possible. Further, when water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, it is preferable because generation of mold and bacteria can be prevented when the pigment dispersion and the ink composition using the same are stored for a long period of time. .

1.9. Other Additives In addition to the constituents described above, the ink composition according to the present embodiment further improves the properties of the ink composition according to need, such as a penetrating solvent, a humectant, and an antiseptic / antifungal agent. , PH adjusting agents, chelating agents and the like can be added.

1.10. Physical Properties of Ink Composition The pH of the ink composition is preferably neutral or alkaline, and more preferably in the range of 7.0 to 10.0. If the pH is acidic, the storage stability and dispersion stability of the ink composition may be impaired. In addition, problems such as corrosion of metal parts used in the ink flow path in the ink jet recording apparatus are likely to occur. The pH can be adjusted to neutral or alkaline using the pH adjusting agent described above.

  The viscosity of the ink composition is preferably in the range of 1.5 mPa · s to 15 mPa · s at 20 ° C. Within this range, ink ejection stability can be ensured in the first step described later.

  The surface tension of the ink composition is preferably 20 mN / m to 40 mN / m, more preferably 25 mN / m to 35 mN / m at 25 ° C. Within this range, ink ejection stability can be ensured in the first step described later, and appropriate wettability with respect to a non-ink-absorbing or low-absorbing recording medium can be secured.

1.11. Method for Producing Ink Composition The ink composition according to the present embodiment can be obtained by mixing the materials described above in an arbitrary order, and removing impurities by filtering or the like as necessary. Here, the colorant is preferably prepared in advance in a state of being uniformly dispersed in an aqueous medium and then mixed in view of ease of handling and the like.

  As a method for mixing the respective materials, a method in which the materials are sequentially added to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is preferably used. As a filtration method, centrifugal filtration, filter filtration, or the like can be performed as necessary.

2. Inkjet Recording Method The inkjet recording method according to the present embodiment includes a first step of forming an image by ejecting droplets of the ink composition described above onto a recording medium, the first step, and / or the first step. It is preferable to include a second step of heating the recording medium after one step and drying the ink composition on the recording medium. Hereinafter, each step will be described in detail.

2.1. First Step The first step in the ink jet recording method according to the present embodiment is a step of forming an image by ejecting droplets of the ink composition described above onto a recording medium by an ink jet recording method.

  As the ink jet recording method, any method can be used as long as it is a method in which the above-described ink composition is ejected as droplets from a fine nozzle and the droplets are attached to a recording medium. As the ink jet recording method, for example, the following four methods can be mentioned.

  The first method is called an electrostatic attraction method. A strong electric field is applied between a nozzle and an acceleration electrode placed in front of the nozzle, and ink is continuously ejected from the nozzle in the form of droplets. Is a method in which a print information signal is applied to the deflection electrode while it is flying between the deflection electrodes and recorded, or an ink droplet is ejected corresponding to the print information signal without being deflected.

  The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element, in which a pressure and a print information signal are simultaneously applied to an ink liquid using a piezoelectric element, and ink droplets are ejected and recorded.

  The fourth method is a method in which the ink liquid is rapidly expanded in volume by the action of thermal energy, and the ink liquid is heated and foamed with a microelectrode in accordance with a print information signal, and ink droplets are ejected and recorded.

Any recording medium may be used as desired, and any of non-ink-absorbing or low-absorbing recording media and plain paper may be used. Among these, in the ink jet recording method according to the present embodiment, a non-ink-absorbing or low-absorbing recording medium can be suitably used. In the present specification, “non-ink-absorbing and low-absorbing recording medium” means “recording in which the water absorption from the start of contact to 30 msec ^1/2 in the Bristow method is 10 mL / m ² or less. Medium ". This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method". Plain paper is paper that is widely used for recording in inkjet printers, laser printers, copiers, etc., and is recognized by, for example, paper that is displayed as “plain paper” under the trade name or the name “plain paper”. The paper is mainly composed of cellulose fibers or the like, and is substantially free of a swelling layer made of a resin such as urethane resin and a void layer made of inorganic particles such as silica and alumina. Typical examples of plain paper include double-sided high-quality plain paper <recycled paper> (manufactured by Seiko Epson Corporation), XeroxP (manufactured by Fuji Xerox Co., Ltd.), Canon plain paper / white (manufactured by Canon Inc.), and plain plain paper finish FUJIFILM Corporation), BROTHER exclusive A4 fine plain paper (Brother Co., Ltd.), KOKUYO KB paper (co-paper) (Kokuyo Corporation), and the like.

As a non-ink-absorbing recording medium, for example, a plastic film coated on a base material such as a plastic film or paper that is not surface-treated for ink jet printing (that is, not formed with an ink absorbing layer) is used. And those having a plastic film adhered thereto. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. Examples of the recording medium having low ink absorption include printing paper such as art paper, coated paper, and matte paper.
In the present invention, the effect is more preferably exerted particularly on a non-ink-absorbing or low-absorbing recording medium.

2.2. Second Step The second step in the ink jet recording method according to the present embodiment is a step of drying the ink composition on the recording medium during the first step and at least one after the first step. . By incorporating the second step, the liquid medium contained in the ink composition deposited on the recording medium is quickly evaporated and scattered, and a resin component film is formed in the ink composition. As a result, even on a non-ink-absorbing recording medium such as a plastic film having no ink absorbing layer, it is possible to obtain in a short time an image with excellent image fixability while having high image quality with little shading unevenness. .

  The second step is not particularly limited as long as it is a method of promoting evaporation and scattering of the liquid medium present in the ink composition. As a method used in the second step, a method of applying heat to the recording medium at least one time after the first step and after the first step, and a method of blowing air on the ink composition on the recording medium after the first step In addition, a method of combining them can be mentioned. Specifically, forced air heating, radiation heating, conductive heating, high frequency drying, microwave drying, and the like are preferably used.

  The temperature range for applying heat in the second step is not particularly limited as long as it can promote evaporation and scattering of the liquid medium present in the ink composition. Is 40 ° C to 80 ° C, more preferably in the range of 40 ° C to 60 ° C. If the temperature exceeds 80 ° C., a problem such as deformation may occur depending on the type of recording medium, which may hinder the conveyance of the recording medium after the second step, or may shrink when the recording medium cools to room temperature. May fail.

  The heating time in the second step is not particularly limited as long as the liquid medium existing in the ink composition can be evaporated and scattered, and a film of pyrrolidone derivatives and / or resin particles that are preferably used can be formed. The liquid medium type, the resin particle type, and the printing speed can be set as appropriate.

3. Examples Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to these examples.

3.1. Preparation of ink composition 3.1.1. Preparation of Pigment Dispersion Preparation of Pigment Dispersion 1 The ink composition used in this example used a water-insoluble pigment (carbon black: CI pigment black 7) as a coloring material. When the pigment was added to the ink composition, a pigment dispersion in which the pigment was previously dispersed with a resin dispersant was used.

The pigment dispersion was prepared as follows. 75 parts by mass of color black S170 (trade name: manufactured by Degussa Huls) as carbon black, 30 parts by mass of Jonkrill 611 (trade name: manufactured by BASF Japan Ltd.), which is a styrene-acrylic acid dispersion resin, and potassium hydroxide 1 70 parts by mass, 250 parts by mass of ultrapure water purified by the ion exchange method and reverse osmosis method were mixed and dispersed for 10 hours by a ball mill using zirconia beads. The obtained dispersion undiluted solution was filtered through glass fiber filter paper GA-100 (trade name: manufactured by Advantech Toyo Co., Ltd.) to remove coarse particles, and the pigment concentration was adjusted to 15% by mass.
The average particle size of the pigment in this dispersion was measured by measuring the particle size distribution of MicrotracUPA150 (manufactured by Microtrac) and found to be 110 nm. Further, the acid value of the acrylic resin (measured based on “JIS K 2501-2003 Petroleum products and lubricants—neutralization test method”) was 60.
Further, “MFT” described in the examples was measured as follows.
In a room controlled at an appropriate temperature, thinly apply polymer particles (emulsion) to an aluminum plate equipped with a heater and thermometer. Immediately after application, a basket containing silica gel (with a transparent window) is placed on the aluminum plate. Apply and dry the coating. After the coating film was dried, the temperature at which the clouded portion of the coating film became a uniform continuous film was visually confirmed while heating the aluminum plate, and MFT was obtained.

Preparation of Pigment Dispersion 2 Pigment Dispersion 2 was prepared as follows. As carbon black, 100 g of MA100 (trade name: manufactured by Mitsubishi Chemical Corporation) was mixed with 1 kg of water and pulverized with a ball mill using zirconia beads. 1400 g of sodium hypochlorite (effective chlorine concentration 12%) was added dropwise to the pulverized stock solution, reacted for 5 hours while pulverizing with a ball mill, and further boiled for 4 hours with stirring to perform wet oxidation. The obtained dispersion stock solution was filtered with glass fiber filter paper GA-100 (trade name: manufactured by Advantech Toyo Co., Ltd.) and further washed with water. The obtained wet cake was re-dispersed in 5 kg of water, desalted and purified with a reverse osmosis membrane until the conductivity reached 2 mS / cm, and further concentrated until the pigment concentration reached 15% by mass to obtain a pigment dispersion. 2 was prepared.
The average particle size of the pigment in this dispersion was measured by measuring the particle size distribution of MicrotracUPA150 (manufactured by Microtrac) and found to be 110 nm.

3.1.2. Preparation of vinyl acetate emulsion Production of ethylene-vinyl acetate emulsion A Ethylene-vinyl acetate copolymer (Evaflex 220; made by Mitsui DuPont Polychemical, vinyl acetate content 28% by weight) 90 parts by mass, potassium oleate 10 parts by mass Are fed at a rate of 3000 g / hr from a hopper of a twin screw extruder (Ikegai Iron Works PCM-30, L / D = 40), and hydroxylated from a feed port provided at the vent portion of the extruder. A 1% aqueous solution of potassium was continuously supplied at a rate of 150 g / hour and continuously extruded at a heating temperature of 160 ° C. The extruded resin mixture was cooled to 90 ° C. with a jacketed static mixer installed at the same extruder port, and then poured into warm water at 80 ° C. to obtain an ethylene-vinyl acetate emulsion A having a solid content of 40% and pH 9. Obtained. When the particle size distribution of the obtained aqueous dispersion ethylene-vinyl acetate resin particles A was measured with Microtrac UPA (manufactured by Honeywell), the average particle size was 180 nm.

Production of ethylene-vinyl acetate emulsion B Ethylene-vinyl acetate copolymer (Evaflex 220; made by Mitsui DuPont Polychemicals, vinyl acetate content 28% by weight) 120 parts by mass and 8 parts by mass of potassium oleate were mixed and biaxial A 1% aqueous solution of potassium hydroxide is supplied from a hopper of a screw extruder (Ikegai Iron Works PCM-30, L / D = 40) at a speed of 2000 g / hour and from a supply port provided in a vent portion of the extruder. It was continuously fed at a rate of 150 g / hour and continuously extruded at a heating temperature of 160 ° C. The extruded resin mixture is cooled to 90 ° C. with a jacketed static mixer installed at the extruder port, and further poured into warm water at 80 ° C., and an ethylene-vinyl acetate emulsion B having a solid content of 40% and pH 9 is obtained. Obtained. When the particle size distribution of the obtained aqueous dispersion ethylene-vinyl acetate emulsion B was measured with Microtrac UPA (manufactured by Honeywell), the average particle size was 230 nm.

3.1.3. Preparation of Ink Composition Using the pigment dispersions 1-2 prepared in “3.1.1. Preparation of Pigment Dispersion” above, the black color composition of the material composition shown in Tables 2-3 was used. Different ink compositions were prepared. For each ink composition, the materials shown in Tables 2 to 3 are placed in a container, mixed and stirred for 2 hours with a magnetic stirrer, and then filtered with a membrane filter having a pore size of 10 μm to remove impurities such as dust and coarse particles. It was prepared by doing. The numerical values in Tables 2 to 3 all indicate mass%, and ion exchange water was added so that the total amount of ink was 100 mass%.

Each material described in Tables 2 to 3 by trade name is as follows.
・ BYK-348 (Bic Chemie Japan, silicone surfactant)
・ Surfinol DF110D (Nisshin Chemical Co., Ltd., acetylene glycol surfactant)
・ Ethylene-vinyl acetate emulsion A (40% dispersion)
・ Ethylene-vinyl acetate emulsion B (40% dispersion)
-Sumikaflex 752 (Sumitomo Chemical Co., Ltd., ethylene-vinyl acetate emulsion (50% dispersion) average particle size 500 nm
・ Sumikaflex 465HQ (manufactured by Sumitomo Chemical Co., Ltd., ethylene-vinyl acetate emulsion (65% dispersion))
・ Superflex 740 (Daiichi Kogyo Seiyaku Co., Ltd., urethane emulsion (40% dispersion)
AQUACER 515 (manufactured by Big Chemie Japan Co., Ltd., polyethylene wax emulsion (35% dispersion))
-AQUACER 507 (manufactured by Big Chemie Japan Co., Ltd., polyethylene wax emulsion (35% dispersion))
・ AQUACER 539 (produced by Big Chemie Japan Co., Ltd., mixed wax emulsion (35% dispersion))
-Chemipearl W4005 (manufactured by Mitsui Chemicals, polyethylene wax emulsion (40% dispersion))

3.2. Evaluation of ink composition 3.2.1. Storage Stability of Ink Composition Each ink composition shown in Tables 2 to 3 was sealed in a sample bottle and allowed to stand in a 60 ° C. environment for 2 weeks. The storage stability of the ink composition was evaluated by observing changes in the viscosity of the ink after standing and the state of separation, sedimentation, and aggregation of the ink components. The evaluation criteria are shown below, and the evaluation results are shown in Table 4.

<Viscosity change>
A: Change rate is less than ± 5% compared to the viscosity immediately after preparation B: Change rate is ± 5% or more and less than ± 10% compared to the viscosity immediately after preparation C: Change rate compared to the viscosity immediately after preparation Is ± 10% or more and less than ± 20% D: The rate of change is ± 20% or more compared to the viscosity immediately after preparation <Separation, sedimentation, and aggregation of ink components>
A: No ink component separation / sedimentation / aggregation B: Ink component separation / sedimentation / aggregation slightly observed C: Ink component separation / sedimentation / aggregation clearly observed D: Ink component separation / sedimentation / aggregation is remarkable

  As shown in Table 4, the ink compositions of the examples were excellent in storage stability with no problems in viscosity change and separation / sedimentation / aggregation of ink components.

3.2.2. Evaluation of density unevenness of recorded matter High-quality ink-absorbing high-quality paper (trade name “55PW8R” manufactured by Lintec Corporation), low-absorptive printing paper (trade name “POD gloss coat”, manufactured by Oji Paper Co., Ltd.) Ink-absorbing polypropylene film (trade name “SY51M 2.6 mil. PPWhite TC RP37 2.2 mil. HIGH DENITY WHITE”, manufactured by UPM RAFLATA, hereinafter abbreviated as “SY51M”) was used. In addition, as an ink jet recording type printer, an ink jet printer (product name “PX-G930”, manufactured by Seiko Epson Corporation, nozzle resolution: 180 dpi) in which a heater capable of changing the temperature is attached to the paper guide unit was used.
An ink jet printer was filled with one of the ink compositions, and an image was recorded on one of the recording media. As the image pattern, a fill pattern that can be recorded in 10% increments with a duty in the range of 50 to 100% at a resolution of 720 dpi in the horizontal direction and 720 dpi in the vertical direction was used. As the recording condition, the heater setting of the printer was set to “setting at which the temperature of the recording surface is 40 ° C.” Furthermore, a drying process was performed by blowing air at a temperature of 80 ° C. on the recorded matter during and immediately after recording. The intensity of the air blowing was such that the wind speed on the surface of the recording medium was about 2 to 5 m / sec. The blowing time immediately after recording was 1 minute. The density unevenness of the recorded material when recorded under such conditions was visually confirmed. The evaluation criteria are shown below, and the evaluation results are shown in Tables 5 to 7. Table 5 shows the evaluation results when high-quality paper (55PW8R) is used as the recording medium, and Table 6 shows the evaluation results when printing paper (POD gloss coat) is used as the recording medium. Table 7 shows the evaluation results when a polypropylene film (SY51M) is used as the recording medium.

A: Density unevenness was not observed even when the duty was 80% or higher. B: No uneven density was observed until the duty was 70%. C: Density unevenness was not observed until the duty was 60%. D: Density unevenness was observed even when the duty was 60% or less.

  As shown in Tables 5 to 7, with the ink compositions of the examples, recorded matter with less density unevenness was obtained. On the other hand, with the ink composition of Comparative Example 2, a recorded matter having particularly large shading unevenness was obtained. In the ink composition of Comparative Example 2, since the colorant is a self-dispersing pigment, the resin concentration in the ink composition is low, so that the fixing property is low at the time of landing, and it is estimated that density unevenness occurs.

3.2.3. Evaluation of Abrasion Resistance of Recorded Material First, images were recorded on various recording media in exactly the same manner as in “3.2.2. Thereafter, the recording surface of the recorded material left for 5 hours in a laboratory at room temperature (25 ° C.) was used with a Gakushin type friction fastness tester (product name “AB-301”, manufactured by Tester Sangyo Co., Ltd.). The rubbing resistance was evaluated by confirming the state of peeling of the recording surface and the state of ink transfer to the cotton cloth when rubbed 20 times with a cotton cloth under a load of 200 g. The evaluation criteria are shown below, and the evaluation results are shown in Tables 5 to 7. Table 5 shows the evaluation results when high-quality paper 55PW8R (Lintec) is used as the recording medium, and Table 6 shows the evaluation results when printing paper (POD gloss coat) is used. Table 7 shows the evaluation results when a polypropylene film (SY51M) is used as the recording medium.

A: Ink peeling or ink transfer to cotton cloth was not recognized even after rubbing 20 times B: Ink peeling or slight ink transfer to cotton cloth was observed after rubbing 20 times C: Ink peeling after rubbing 20 times Or, ink transfer to the cotton cloth was recognized. D: Ink peeling or ink transfer to the cotton cloth was recognized before rubbing 20 times.

  As shown in Tables 5 to 7, with the ink compositions of Examples, recorded matter having excellent abrasion resistance was obtained. Further, when Examples 3 and 7 were compared, the ink composition of Example 3 was effective for a non-absorbent recording medium. On the other hand, in Comparative Examples 1 and 2, an unsatisfactory recorded matter was obtained. Since the ink composition of Comparative Example 1 was not added with the ethylene-polar monomer copolymer resin, it was presumed that the rubbing resistance of the fine paper was not particularly good. Further, in the ink composition of Comparative Example 2, since the colorant is a self-dispersing pigment, the resin concentration in the ink composition is low, so that a recorded matter having low fixing property upon landing and inferior abrasion resistance can be obtained. Presumed to be easy.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (11)

An ink composition used for a recording medium selected from a non-ink-absorbing or low-absorbing recording medium and plain paper,
A resin-dispersed pigment formed from a resin dispersant and a colorant dispersed by the resin dispersant, and an ethylene-polar monomer copolymer resin having an average particle size of 1 μm or less,
An ink composition containing substantially no solvent having a boiling point of 280 ° C. or higher at 1 atm.   2. The ink composition according to claim 1, wherein the ratio of the colorant: resin dispersant is 2: 1 to 5: 1 in the resin dispersed pigment.   The ink composition according to claim 1, wherein the resin dispersant is an acrylic resin.   The ink composition according to claim 3, wherein the acid value of the acrylic resin is 40 or more and 100 or less.   The ink composition according to any one of claims 1 to 4, wherein the resin-dispersed pigment has an average particle size of 20 nm to 500 nm.   The ink composition according to any one of claims 1 to 5, wherein the copolymer resin is an ethylene-vinyl acetate copolymer resin having an MFT of less than 100 ° C.   The ink composition according to any one of claims 1 to 6, further comprising polymer particles having an average particle diameter of 5 nm or more and less than 200 nm.   The ink composition according to claim 7, wherein the polymer particles are polyethylene wax particles having an MFT of 100 ° C. or higher.   The ink composition according to any one of claims 1 to 8, further comprising glycol ethers having an HLB value calculated by the Davis method in the range of 4.2 to 8.0.   An ink jet recording method for forming an image on a recording medium selected from non-ink-absorbing or low-absorbing recording medium and plain paper using the ink composition according to claim 1. . A recorded matter recorded by the ink composition according to claim 1.