JP2013241565A - Ink and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink maintaining discharge stability of the ink, and capable of preventing blots of the ink on a recording medium.SOLUTION: An ink is one in which a particle of a binder resin 1 is dispersed as a dispersoid in a dispersion solution, and a colorant 2 is dispersed or dissolved in the particle of the binder resin, wherein the average particle diameter of the particle of the binder resin 1 is ≥50 nm, and further ≥80 nm; and the particle of the binder resin 1 is formed by emulsion polymerizing or suspension polymerizing a monomer of the binder resin material and the colorant.

Description

  The present invention relates to ink and use thereof.

  As an ink used in an ink jet recording apparatus, an ink containing a pigment coated with a resin and microencapsulated is described in Patent Documents 1 and 2.

JP 2010-180419 A (released on August 19, 2010) JP 2010-84066 A (released on April 15, 2010)

  In general, the smaller the diameter of the pigment particles in the ink is about 1/10 or less than the nozzle diameter of the inkjet head, the better the ejection stability in inkjet printing. On the other hand, if the pigment particles have a large diameter, the ink is difficult to bleed on the print medium, but the solvent due to the presence of the pigment before the ink comes out in a columnar shape from the nozzle and becomes spherical due to the surface tension during ink ejection. Due to the discontinuity, the ink is easily cut off at the interface between the pigment and the solvent, and the ejection stability is lowered.

  As described in Patent Documents 1 and 2, even when a pigment-encapsulated microcapsule is used, the particle diameter of the microcapsule is the structure in which the core pigment particle is coated with a shell resin. Is small and causes ink to spread on the print medium.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink capable of preventing ink bleeding on a print medium while maintaining ink ejection stability. is there.

  In order to solve the above problems, the ink according to the present invention is such that the binder resin particles are dispersed in a dispersion solution as a dispersoid, and the colorant is dispersed or dissolved in the binder resin particles. It is a feature.

  In general, in the case of an ink that contains pigment particles as they are in the ink, the discharge stability decreases when the particle size of the pigment particles exceeds 200 nm. However, according to the ink according to the present invention, the colorant is contained inside by the above configuration. Even if the particles of the binder resin dispersed or dissolved in the resin are enlarged, the particles are easily formed into a substantially spherical shape or a substantially elliptical shape, so that the surface area is minimized. By ensuring lyophilicity, it is possible to ensure ejection stability without being affected by nonuniformity due to the colorant. That is, by increasing the resin particles encapsulating the colorant contained in the ink, it is possible to prevent ink bleeding on the print medium while maintaining ink ejection stability without being affected by the colorant. Is possible. In addition, since the ink according to the present invention evaporates quickly on the print medium, it is possible to prevent the ink from bleeding.

  In the ink according to the present invention, the average particle diameter of the binder resin particles is preferably 50 nm or more.

  With the above configuration, even when the average particle size of the binder resin particles is 50 nm or more, the discharge stability can be ensured, so that the ink bleeding on the print medium and the binder resin Particle aggregation and colorant alteration can be further prevented.

  In the ink according to the present invention, the average particle size of the binder resin particles is preferably 80 nm or more.

  With the above configuration, even when the average particle size of the binder resin particles is 80 nm or more, the discharge stability can be ensured, so that the ink bleeding on the print medium and the binder resin can be ensured while ensuring the discharge stability. Particle aggregation and colorant alteration can be further prevented.

  In the ink according to the present invention, the binder resin particles are preferably formed by emulsion polymerization or suspension polymerization of a binder resin material monomer and the colorant.

  With the above configuration, the binder resin particles are easily formed into a substantially spherical shape or a substantially elliptical shape, so that the discharge stability is ensured even when the diameter of the binder resin particles is increased.

  In the ink according to the present invention, in the binder resin particles, an average content ratio of the binder resin and the colorant is preferably 20:80 to 95: 5 by weight.

  With the above configuration, the precipitation of the binder resin particles can be further suppressed.

  In the ink according to the present invention, the binder resin particles preferably have a substantially spherical shape, a substantially elliptical shape, or a substantially disk shape.

  With the above configuration, ink ejection stability is further improved.

  In the ink according to the present invention, the average particle diameter of the colorant is preferably 50 nm or less.

  With the above configuration, the colorability of the ink is further improved, and high-definition printing is possible. Moreover, since the colorant is included in the particles of the binder resin, the light resistance of the ink can be improved even if the average particle diameter of the colorant is reduced to 50 nm or less.

  In the ink according to the present invention, the colorant comprises an organic pigment, an inorganic pigment, a disperse dye, an acid dye, a reactive dye, titanium oxide, magnetic particles, alumina, silica, ceramic, carbon black, metal nanoparticles, and an organic metal. It is preferably at least one selected from the group. Further, the surface of the colorant may be coated with a polymer or a surfactant in order to improve the dispersibility in the binder resin.

  With the above configuration, ink that can be used for various purposes can be provided.

  In the ink according to the present invention, the binder resin is preferably at least one resin that is cured by light or heat or selected from a cured polymer compound.

  With the above configuration, ink that can be used for various purposes can be provided.

  In the ink according to the present invention, the binder resin is preferably an ultraviolet curable polymer compound.

  With the above configuration, it is possible to provide an ink that fixes a highly glossy and high-strength ink film on a print medium.

  In the ink according to the present invention, the dispersion solution is water or a hydrophilic solvent, and the binder resin particles are preferably emulsion or suspended in the water or the hydrophilic solvent. Thereby, more suitable printing is possible.

  In the ink according to the present invention, the main component of the dispersion solution is preferably at least one of water and a hydrophilic solvent, and the surface of the binder resin particles is preferably subjected to a hydrophilic treatment.

  According to the above configuration, since the surface of the binder resin particles in contact with water or a hydrophilic solvent has an affinity for water or the hydrophilic solvent, the binder resin particles are suitably dispersed in the dispersion solution. . Further, even if the particle diameter of the binder resin particles is increased, the ink is not separated in the nozzle, and a predetermined amount of ink can be reliably discharged from the nozzle. Furthermore, since the affinity with the dispersion is ensured on the surface of the hydrophilic binder resin, it is not necessary to select hydrophilic binder resin materials and colorants, and various binder resin materials and colorants can be used. Can be used.

  In the ink according to the present invention, the hydrophilization treatment is preferably an emulsification treatment in which the surface is emulsified using a surfactant or a dispersant, or an introduction treatment in which a hydrophilic group is introduced into the surface. Thereby, the surface of a binder resin particle can be hydrophilized suitably.

  In the ink according to the present invention, the average particle size of the binder resin particles is preferably 800 nm or more.

  According to the above configuration, it is possible to more reliably prevent bleeding on the print medium, so even when ink is ejected onto paper, fabric, etc., where bleeding is likely to occur, Printing can be performed without causing any bleeding without causing any pretreatment. Accordingly, it is possible to provide an ink particularly suitable for paper and textile printing.

  In the ink according to the present invention, the colorant is preferably particles containing a rare earth metal.

  According to said structure, it can use suitably as what is called stealth ink. By using an ink containing particles containing a rare earth metal as the stealth ink, the ink is more stable and a printed matter with high brightness can be obtained. Further, since the particles containing rare earth metal are encapsulated in the binder resin particles and the ink is rapidly evaporated on the print medium, it is possible to prevent the ink from bleeding on the print medium. By using a simple ink, even on a print medium that easily bleeds, such as fabric and leather, printing can be performed without causing any pretreatment without causing any pretreatment. That is, using the ink of the present invention as stealth ink, it can be suitably printed on fabric, leather, etc., and ink suitable for printing a mark for authenticity identification on fabric and leather products is used. Can be provided.

  In the ink according to the present invention, it is preferable that a resin different from the binder resin is dissolved in the dispersion solution.

  According to said structure, it is possible to adjust the viscosity of an ink. Further, when moisture in the ink flies by drying, the binder resin can be further strongly bonded as a binder when the other resin is formed into a film by bonding between the binder resins. Then, by using the other resin as a binder and binding the binder resins strongly, it is possible to prevent ink bleeding on the print medium.

  In the ink according to the present invention, the surface of the binder resin particles is preferably coated with a surfactant such as a polymer or a monomer.

  According to the above configuration, in the ink of the present invention, the binder resin particles are microencapsulated with the surfactant. When the particle diameter of the binder resin particles is reduced, the colorant may be exposed from the surface of the binder resin particles. As described above, when the colorant is exposed from the surface of the binder resin particles, the ejection stability of the ink is lowered. By coating the surface of the binder resin particles with a surfactant, the colorant is not exposed from the surface of the binder resin particles even when the particle diameter of the binder resin particles is reduced.

  Also, by coating the surface of the binder resin particles with a surfactant, the dispersibility of the binder resin particles in the dispersion solution is improved, and ink bleeding can be more effectively prevented. Also, by coating the surface of the binder resin particles with a surfactant, the particle surface is strengthened, the light resistance and color development of the ink are improved, and a strong ink film can be formed on the printing medium.

  In the ink according to the present invention, the binder resin particles preferably include flat particles having an ellipse in at least one cross section.

  According to the above configuration, when the ink lands on the print medium by including flat particles of the binder resin having at least one elliptical cross section in the ink, on the print medium surface, The flat particles fall down so that the long axis, which is the longest diameter among the diameters passing through the center of gravity of the flat particles, is along the surface of the print medium. That is, in the ink layer formed on the print medium, the flat particles are oriented so that their long axes are along the surface of the print medium.

  For this reason, the level difference of the unevenness | corrugation which arises on the ink layer surface on a printing medium resulting from the shape of the particle | grains of binder resin can be reduced. As a result, light scattering caused by unevenness on the surface of the ink layer can be reduced, so that a highly glossy printed matter can be obtained.

  The ink jet recording method according to the present invention includes a discharge step of discharging the ink onto a print medium, and a first heating step of heating the ink that has landed on the print medium at a temperature at which the solvent in the dispersion solution is evaporated. It is characterized by doing.

  With the above configuration, it is possible to suitably print on various print media.

  In the inkjet recording method according to the present invention, when the binder resin is a polymer compound that is cured by heat, the ink that has landed on the print medium is dissolved at a temperature at which the binder resin is dissolved after the first heating step. It is preferable to further include a second heating step of heating.

  With the above configuration, the ink can be fixed more firmly on the print medium.

  In the ink jet recording method according to the present invention, when the binder resin is a polymer compound that is cured by light, the method further includes an irradiation step of irradiating the ink landed on the print medium with light after the first heating step. It is preferable to do.

  With the above configuration, it is possible to fix an ink film having higher gloss and strength on a printing medium.

  In the ink jet recording method according to the present invention, the average particle diameter of the binder resin particles is preferably 1/10 or less of the nozzle diameter of the nozzle that discharges the ink in the discharging step.

  With the above configuration, the ejection stability is further improved.

  In the ink jet recording method according to the present invention, the printing medium is particularly effective when it is a non-absorbing medium such as plastic that is likely to cause bleeding, paper, or fabric.

  According to the above configuration, since the colorant is included in the binder resin particles in the ink and the ink is rapidly evaporated on the print medium, it is possible to prevent bleeding of the ink on the print medium. Yes, by using such inks, even on non-absorbent media, paper, fabrics, leather, and other print media that tend to bleed, bleed occurs without any pretreatment of the print media. Can be printed without

  The ink production method according to the present invention is not limited to a specific method, but is any one of a binder resin liquid and a binder resin material liquid in which a colorant is dispersed or dissolved. It is characterized by including a step of putting the liquid in a liquid incompatible with the liquid and stirring.

  With the above configuration, the ink according to the present invention can be preferably manufactured.

  According to the ink of the present invention, the binder resin particles are dispersed in the dispersion solution as a dispersoid, and the colorant is dispersed or dissolved in the binder resin particles. While maintaining, it is possible to prevent the ink from bleeding on the print medium.

It is a figure which shows typically the structure of the binder resin particle contained in the ink which concerns on one Embodiment of this invention. FIG. 4 is a schematic diagram illustrating a state where ink according to an embodiment of the present invention lands on a medium (print medium) and prints the medium. It is a graph which shows the relationship between the particle size of the coloring agent contained in an ink, and the performance of an ink. It is a schematic diagram which shows a mode that a medium is printed with the ink which concerns on other embodiment of this invention. It is a figure which shows the flow of one Embodiment of the manufacturing method of the ink which concerns on this invention. It is a figure which shows schematically the structure of the apparatus used with one Embodiment of the manufacturing method of the ink which concerns on this invention. It is a graph which shows the relationship between the particle size of the particle | grains contained in an ink, and ejection stability.

〔ink〕
In the ink according to the present invention, the binder resin particles are dispersed as a dispersoid in the dispersion solution, and the colorant is dispersed or dissolved in the binder resin particles.

  Hereinafter, for convenience of explanation, the binder resin particles are referred to as “binder resin particles” in the present specification. Further, in this specification, “ink” includes not only a colored liquid for coloring a printing medium but also a coating agent for coating the printing medium, and may be a transparent liquid.

  In the present invention, the colorant is dispersed or dissolved in the binder resin particles, and is configured as shown in FIG. 1, for example. FIG. 1 is a diagram schematically showing the configuration of binder resin particles contained in an ink according to an embodiment of the present invention. As shown in FIG. 1, a plurality of colorants are dispersed or dissolved in one binder resin particle.

  In the ink of the present invention, the colorant is encapsulated in a hydrophilic binder resin or a solution-processed binder resin that has been hydrophilically processed and polymerized in a spheroidized state due to the surface tension of the liquid binder resin. The problem caused by the non-uniformity of the characteristics and the problem caused by the variation in the shape of the colorant are solved. In addition, since the surface area where the binder resin and the solvent come into contact with each other can be minimized, the disturbance of the solvent performance due to the particles is eliminated, and the discharge stability is improved. Examples of the method of encapsulating the colorant particles in the binder resin and the method of obtaining the binder resin particles having a desired particle diameter include an emulsion polymerization aggregation method, a suspension polymerization method, a dissolution suspension method, and an ester extension polymerization method. It is done.

  Further, in the ink of the present invention, since the binder resin particles encapsulating the colorant are dispersed in the dispersion solution, the pigment is dispersed in the dispersion solution as compared with the conventional ink in which the pigment is dispersed in the dispersion solution as it is. When the diameter of the particles increases and lands on the print medium, bleeding due to the fine colorant that easily moves in the solvent is less likely to occur. Further, in the ink of the present invention, since the binder resin particles are dispersed in the dispersion solution as a dispersoid, even when the ink is rapidly evaporated and the average particle diameter of the binder resin particles is small, the binder resin particles are dispersed on the printing medium. Ink bleeding can be further prevented. Therefore, printing on various print media is possible.

  In general, in the case of an ink that contains pigment particles as they are in the ink, the discharge stability decreases when the particle size of the pigment particles exceeds 200 nm. However, according to the ink of the present invention, the colorant is contained inside the ink. Even if the particles of the dispersed or dissolved binder resin are enlarged, the particles are easily formed into a substantially spherical shape or a substantially elliptical shape, so that the discharge stability can be ensured. That is, it is possible to prevent bleeding of the ink on the print medium, particularly by making the binder resin particles larger than 200 nm while maintaining the ejection stability of the ink.

  The specific material of the binder resin used in the ink of the present invention is not particularly limited as long as it is insoluble in the vehicle, but is at least selected from a polymer compound that is cured by polymerization with light or heat or is cured. It is preferably a kind of resin, and may be a monomer, an oligomer, and a low molecular weight resin that are cured by polymerization reaction by irradiation with energy rays such as ultraviolet rays, electron beams, radiation, or heat. Here, the “vehicle” refers to a component other than the binder resin in which fine particles are dispersed or dissolved in the ink according to the present invention, and a dispersion solution, an additive, a cosolvent, and the like described later are intended.

  Examples of binder resins include vinyl resins, acrylic resins, alkyd resins, polyester resins, urethane resins, styrene resins, styrene copolymer resins, silicon resins, fluorine resins, epoxy resins, Examples thereof include phenoxy resins, polyolefin resins, and modified resins thereof. Among these, more preferred are acrylic resins, polyurethane resins, polyester resins, and acrylic resins, and particularly preferred are polyester resins and acrylic resins.

  Other examples of the binder resin include natural rubber latex, styrene butadiene latex, styrene-acrylic latex, polyurethane latex and the like. As the binder resin, for example, it is more preferable to use a stock solution of these resins and a solution obtained by subjecting the stock solution to an emulsion polymerization reaction, since the low-viscosity liquid resin before polymerization tends to be spherical when dispersed in water. When these resins are employed as the binder resin, they may be a polymer dispersion type that requires a dispersant or a self-dispersion type (reference: see JP-A-2001-152063).

  Examples of the cured polymer compound include those listed in Table 1 below. These can be used alone or in combination. Furthermore, in order to improve the adhesion to the recording medium and the fixing property at low temperature heating, it is preferable to use a combination of a resin having a small glass transition point (TG) and a resin having a large TG and high fastness.

  The ink of the present invention is particularly preferably an aqueous latex ink containing water or a hydrophilic organic solvent as a dispersion solution, and a binder resin being emulsified or suspended in the water or the hydrophilic organic solvent. The aqueous latex ink may contain a non-hydrophilic organic solvent having an affinity for the hydrophilic organic solvent in addition to water or the hydrophilic organic solvent.

  When the ink of the present invention is an aqueous latex ink in which the binder resin is emulsified or suspended in water, it can be said that an aqueous emulsion or aqueous suspension is formed from the resin.

  The aqueous latex ink may further contain an emulsifier for emulsifying or suspending the resin.

  Specific examples of the colorant dispersed or dissolved in the binder resin particles are not particularly limited as long as they are insoluble in the vehicle, and various colorants can be employed depending on the purpose. Specific colorants include, for example, organic pigments, inorganic pigments, disperse dyes, oxidation dyes, reactive dyes, hollow organic resin particles, titanium oxide, magnetic particles, alumina, silica, ceramics, carbon black, metal nanoparticles, and organic There may be mentioned at least one kind of particles selected from the group consisting of metals. Examples of the metal nanoparticle material include gold, silver, copper, and aluminum. In the case of titanium oxide, it can be suitably used as a white paint. Further, the surface of the colorant may be coated with a polymer or a surfactant in order to improve the dispersibility in the binder resin.

  In the ink of the present invention, it is sufficient that a plurality of colorant particles are dispersed or dissolved in the binder resin particles. For example, five or more colorant particles are dispersed or dissolved. The colorant dispersed or dissolved in the binder resin particles may be one type, but may be a plurality of types.

  Specific examples of the dispersion solution are not limited as long as they do not dissolve the binder resin, and various dispersion solutions can be employed depending on the purpose. Specific examples of the dispersion solution include water. Water can be suitably used for applications such as inks for commonly used ink jet printers because of its safety and no environmental pollution. Since water alone has a high drying speed and causes nozzle clogging of the inkjet head, it is more preferable to add a humectant to the water. Also, in order to prevent bleeding by rapid evaporation when heated by a heater on the media, an organic solvent having a boiling point lower than that of water is added to water, or higher than water is used to reduce nozzle clogging. More preferably, a boiling organic solvent is added to water.

  What is necessary is just to set suitably about the density | concentration of the binder resin particle in an ink according to the objective. For example, when the pigment fine particles are dispersed in the binder resin particles, the binder resin particles are more preferably 5% by volume to 60% by volume with respect to the total amount of the ink, and 7% by volume to 40% by volume. Further preferred.

  The ink according to the present invention may contain an additive in addition to the binder resin particles containing the colorant and the dispersion solution. The kind of the additive may be appropriately selected depending on the purpose, and examples thereof include a surfactant, a coupling agent, a buffering agent, a biocide, a metal ion sealing agent, a viscosity modifier, and a solvent. The additive may be dispersed in the binder resin particles, or may be present outside the binder resin particles and in the dispersion solution.

  As another embodiment of the present invention, the binder resin itself colored with a dye may be used as the binder resin particles. For example, a polyester resin encapsulating a disperse dye is heated to dissolve the disperse dye, and the resin dyed with the disperse dye, a nylon resin mixed with an acid dye or a reactive dye is heated to dissolve the dye, and the acid dye Or what dye | stained resin with the reactive dye is used as a binder resin particle. As a result, an ink for inkjet printing with high transparency, no bleeding, and high definition can be obtained.

  In the ink of the present invention, the average particle diameter of the binder resin particles is preferably 50 nm or more, more preferably 50 nm or more and 500 nm or less, and most preferably 80 nm or more and 300 nm or less. Here, the average particle diameter of the binder resin means an average particle diameter of a plurality of binder resin particles dispersed in the dispersion solution. In addition, by making the average particle diameter of the binder resin particles within the above range and making it 1/10 or less of the nozzle diameter of the nozzle that discharges the ink containing the binder resin particles, the ejection stability from the nozzle is further improved. Can be made.

  The particle size of the binder resin particles is controlled by controlling the polymerization conditions when forming the binder resin particles by the emulsion polymerization aggregation method, suspension polymerization method, dissolution suspension method, ester elongation polymerization method, etc. Can do.

  In the ink of the present invention, since the colorant is dispersed or dissolved in the binder resin particles, the fine particles of the colorant that cause aggregation are not present in the ink as they are, and aggregation of the colorant can be prevented. In addition, a dispersant for dispersing the colorant in the dispersion solution becomes unnecessary. In other words, the disadvantage of the conventional ink that the fine particles of the pigment are aggregated can be solved.

  Furthermore, since the aggregation of particles is suppressed as the particle diameter in the dispersion solution is larger, by making the average particle diameter of the binder resin larger than 50 nm, aggregation of the binder resin particles is suppressed, Further, since the colorant dispersed or dissolved in the binder resin particles is fixed in the binder resin, aggregation of the colorant can be completely suppressed.

  Further, in the ink of the present invention, since the colorant is included in the binder resin and protected by the binder resin, the influence of ultraviolet rays on the colorant can be suppressed and the light resistance of the ink can be improved. In addition, the influence of oxygen on the colorant can be suppressed. That is, it is possible to greatly suppress colorant alteration due to the influence of ultraviolet rays or oxygen.

  Furthermore, the larger the diameter of the binder resin particles encapsulating the colorant, the more the deterioration of the colorant can be suppressed. Therefore, by making the average particle diameter of the binder resin larger than 50 nm, the quality of the colorant Can be further suppressed.

  Further, since the binder resin particles are dispersed as a dispersoid in the dispersion solution, the ink evaporates quickly, and even when the average particle diameter of the binder resin particles is as small as 50 nm, for example, on the printing medium. Ink bleeding can be further prevented. As a result, if the ink of the present invention is used, it is possible to print on various printing media.

  In the ink of the present invention, the average particle size of the colorant may be smaller than the particle size of the binder resin particles, and is preferably 80 nm or less, more preferably 5 nm or more and 80 nm or less, and 10 nm or more and 50 nm. Most preferably: Here, the average particle diameter of the colorant means the average particle diameter of a plurality of colorants dispersed in the binder resin particles.

  As a method of making the colorant into fine particles so as to have the above-mentioned particle diameter, or a method for producing the colorant fine particles, a mechanical crushing method such as a roll crusher, a ball mill, a jet mill, a sand grinder mill, an edge runner, an underwater crystal Liquid phase such as vapor deposition method, emulsion polymerization, emulsion polymerization, etc., such as crystallization method, hydrothermal method, thermal decomposition method, thermal decomposition method, etc. and CVD (gas phase chemical deposition method, Chemical Vapor Deposition) According to the law, it may be appropriately selected according to the intended colorant and application. Fine particles having a constant particle size distribution can be obtained by controlling the particles to have a constant particle size distribution in the production process or by classifying particles having a wide particle size distribution after production.

  In the ink of the present invention, even if the colorant is reduced in size, aggregation and bleeding are less likely to occur. Therefore, the colorant can be further reduced in diameter, and the colorability of the ink is improved and high-definition printing can be realized. .

  Moreover, since the colorant is improved as the colorant is smaller in diameter, when the average particle diameter of the colorant is 50 nm or less, the colorability of the ink is further improved, and higher-definition printing is possible. Furthermore, since the colorant is encapsulated in the binder resin particles, the light resistance of the ink can be improved even if the average particle diameter of the colorant is reduced to 50 nm or less.

  In the ink of the present invention, the average content ratio of the binder resin and the colorant in the binder resin particles is preferably 20:80 to 95: 5, and 75:25 to 95: 5 in terms of weight ratio. Is more preferable, and most preferably 65:35 to 90:10. The average content ratio between the binder resin and the colorant means the average content ratio between the binder resin and the colorant in the plurality of binder resin particles dispersed in the dispersion solution. Control of the average content ratio of the binder resin and the colorant is to control the polymerization conditions when forming the binder resin particles by the emulsion polymerization aggregation method, suspension polymerization method, dissolution suspension method, ester elongation polymerization method, etc. Etc.

  In the ink of the present invention, since the colorant is dispersed or dissolved and fixed in the solid or semisolid binder resin particles, precipitation of the colorant can be prevented.

  If the resin ratio of the binder resin is small, the colorant is exposed on the surface of the binder resin particle sphere, and the ejection becomes unstable.If the resin ratio is too large, the coloring power of the colorant is reduced, and sufficient saturation or The concentration cannot be obtained. Therefore, the ratio between the binder resin and the colorant that forms the binder resin particles is preferably within a certain range in order to achieve both the coloring power and the inclusion of the colorant in the binder resin. The average content ratio between the binder resin and the colorant is preferably in the range of 40:60 to 95: 5 by weight. By including the colorant in the binder resin, the average specific gravity is lower than that of the colorant alone, and the effect that precipitation can be suppressed even when the particle size is large is obtained.

  In particular, when the ink is white ink, the resin ratio in the binder resin particles is preferably 50% or more, and when the ink is another color ink, the resin ratio in the binder resin particles is 70% or more. It is preferable that

  In the ink of the present invention, the binder resin particles preferably have a substantially spherical shape or a substantially elliptical shape in order to reduce the specific surface area. When the binder resin particles are substantially spherical or elliptical, ink ejection stability is further improved.

  The binder resin particles in the ink of the present invention may be formed by emulsion polymerization or suspension polymerization, or dissolution suspension polymerization or ester extension polymerization of a binder resin material monomer and a colorant. Details of the method of forming the binder resin particles will be described later.

  According to the ink of the present invention, it is possible to prevent bleeding of the ink on the print medium while maintaining the ejection stability of the ink. Further, according to the ink of the present invention, it is possible to prevent the aggregation and precipitation of particles in the ink, to suppress the influence of ultraviolet rays and oxygen on the colorant, to prevent the colorant from deteriorating, and to improve the colorability of the ink. It is possible to improve and achieve higher-definition printing.

  The reason why the above-described effect can be obtained by the ink of the present invention will be described with reference to FIG. FIG. 3 is a graph showing the relationship between the particle size of the binder resin particles contained in the ink and the performance of the ink. In FIG. 3, the horizontal axis represents the particle diameter, and the particle diameter is larger toward the left in the figure. In FIG. 3, the vertical axis represents the state of each property of the ink, and the upper part of the figure indicates that the state of each property of the ink is better.

  The line (a) in FIG. 3 shows the relationship between the colorability of the ink and the particle size of the binder resin particles in the ink, and the line (b) shows the ink ejection stability and the binder resin in the ink. The line of (c) shows the relationship between the precipitation state of the binder resin particles in the ink and the particle size of the binder resin particles in the ink. Also, the line (d) in FIG. 3 shows the light resistance of the binder resin particles in the ink, and the line (e) shows the state of ink bleeding on the print medium and the binder resin particles in the ink. The line (f) shows the relationship between the aggregated state of the binder resin particles in the ink and the particle size of the binder resin particles in the ink.

  In general, the colorability, ejection stability, and precipitation state of ink are better (good) as the particle size is smaller, and worse (inferior) as the particle size is larger. That is, when the diameter of the particles in the ink is increased, the colorability and ejection stability are lowered, and the particles are easily precipitated.

  On the other hand, the light resistance, bleeding, and aggregation state of the ink are better (good) as the particle size is larger, and worse (inferior) as the particle size is smaller. That is, when the particles in the ink have a small diameter, the light resistance is lowered, the ink is likely to bleed, and the particles are likely to aggregate.

  In the conventional ink, since the particle size of the pigment contained in the ink is small, the colorability, the ejection stability, and the precipitation state are good, but the light resistance, bleeding, and aggregation state are not good.

  In the ink of the present invention, since the binder resin particles in which the colorant is dispersed or dissolved are used, the particle size can be increased. Therefore, as represented by the lines (d) to (e), the ink of the present invention is excellent in light resistance, particles are less likely to aggregate, and are less likely to bleed.

  In the ink of the present invention, since the binder resin particles are formed by emulsion polymerization or suspension polymerization, the particles are likely to be spherical, and even if the particle size is increased, the ejection stability is not easily lowered. Accordingly, the discharge stability is excellent as represented by the line (b).

  Further, in the ink of the present invention, since the binder resin particles in which the colorant is dispersed are dispersed, the content ratio of the binder resin to the colorant in the ink is increased, and even if the particle size is increased, the colorant Since the average specific gravity is smaller than that of the single substance, the colorant is hardly precipitated as represented by the line (c). Moreover, since the particle | grains of the colorant disperse | distributed in a binder resin particle can be made into a small diameter, even if a particle size becomes large, the coloring property represented by the line of (a) can be kept favorable.

  In general, when the content ratio of the colorant in the ink is increased in order to increase the concentration of the ink, the average specific gravity of the colorant increases and the ink tends to precipitate. In order to solve this problem, in the ink of the present invention, when the content ratio of the colorant is increased, the particle size of the binder resin particles encapsulating the colorant is reduced. On the other hand, in the case of the conventional ink, if the particle size of the particles in the ink is reduced, another problem that the ink easily bleeds occurs. However, in the ink of the present invention, the binder resin particles are dispersed in the dispersion solution as a dispersoid, and therefore, when applied on a print medium, the ink is quickly evaporated and hardly spreads. As described above, according to the ink of the present invention, even when the content ratio of the colorant is increased, the ink has an excellent effect that it is difficult to precipitate and does not spread easily. Therefore, in the ink of the present invention, particularly from the viewpoint of preventing precipitation and bleeding, the average particle size of the binder resin particles may be 50 nm or more, more preferably 50 nm or more and 500 nm or less, and more preferably 80 nm or more. Most preferably, it is 300 nm or less.

  In the ink of the present invention, since the binder resin particles in which the colorant is dispersed or dissolved are used, the particle size of the particles contained in the ink is increased. Therefore, with regard to the light resistance, bleeding, and aggregation states that are improved by increasing the particle size, the resin particles having a large particle size serve as anchors, so that they are naturally superior to conventional inks. Become.

  As described above, in the ink of the present invention, even if the binder resin particle diameter in the dispersion solution is increased by dispersing the binder resin particles in which the colorant is dispersed or dissolved in the dispersion solution, the ejection stability is increased. In addition, the precipitation state and the colorability can be kept good. That is, it can be said that the ink of the present invention is a next-generation ink that can keep the discharge stability, the precipitation state, and the colorability comprehensively while improving the light resistance, bleeding, and aggregation state.

  Since the ink of the present invention has good light resistance, bleeding and aggregation, and good discharge stability, precipitation and colorability, it can be used for printing on various printing media. It can also be suitably used for textile printing. In addition, the ink of the present invention can be used as an adhesive or a release agent, or can be used as a coating agent such as a UV cut clear coating agent by adding an ultraviolet absorber. It can also be applied to inorganic hybrid inks and the like.

  In the ink of the present invention, when the dispersion solution is water or a hydrophilic solvent, the surface of the binder resin particles may be subjected to a hydrophilic treatment. Thereby, since the surface of the binder resin in contact with water or the hydrophilic solvent has an affinity for water or the hydrophilic solvent, the binder resin is suitably dispersed in the dispersion solution. Usually, the binder resin is lipophilic and easily separated in a hydrophilic solvent. In particular, when the particle size of the binder resin is increased, it becomes easier to separate from the hydrophilic solvent, so that there is a problem that the ink is divided and misted when ejected from the nozzle.

  Here, the relationship between the particle size of the binder resin contained in the ink and the ejection stability will be described with reference to FIG. FIG. 7 is a graph showing the relationship between the particle size of the particles contained in the ink and the ejection stability. In FIG. 7, the vertical axis represents an evaluation value obtained by evaluating the ink ejection stability in five stages, and the upper part in the figure indicates that the ejection stability is more excellent. In FIG. 7, the horizontal axis represents the average particle diameter (nm) of the particles contained in the ink.

  The line A (dotted line) in FIG. 7 shows the average particle diameter and ejection stability of the binder resin particles when the ink of the present invention containing the binder resin whose surface is hydrophilized is ejected from a nozzle having a nozzle diameter of 25 μm. Shows the relationship. The line B (solid line) in FIG. 7 shows the relationship between the average particle diameter of the pigment and the ejection stability when conventional ink containing the pigment is directly ejected from a nozzle having a nozzle diameter of 25 μm.

  As shown in FIG. 7, the ink of the present invention has good ejection stability even when the average particle diameter of the binder resin particles is as large as 1200 nm. Further, when the nozzle diameter of the nozzle that discharges the ink is increased, the discharge stability of the ink of the present invention is as indicated by the line A ′ (dotted line) in FIG. 7, and the average particle diameter of the binder resin particles is further increased. Even if it is changed, the discharge stability is good. On the other hand, the ejection stability of the conventional ink is lowered even when the average particle diameter of the pigment is 200 nm. That is, when the ink of the present invention is compared with the conventional ink, as shown by the arrows in FIG. 7, the ink of the present invention has greatly improved ejection stability, and even if the contained particles have a large particle size. Discharge stability does not decrease.

  Thus, according to the ink of the present invention, even if the particle size of the binder resin particles is increased, the particles are not separated in the hydrophilic solvent, so that the ink is not divided in the nozzle, and a predetermined amount of ink is discharged from the nozzle. Can be reliably discharged. In addition, since the affinity with the dispersion solution is ensured on the surface of the new aqueous binder resin, it is not necessary to select hydrophilic binder resin materials and colorants, and various binder resin materials and colorants can be used. Can be used.

  The hydrophilic treatment on the surface of the binder resin can be performed by a method such as an emulsification treatment in which the surface is emulsified with a surfactant or a dispersant, and an adhesion treatment in which a hydrophilic group is attached to the surface.

  In the ink of the present invention, the surface of the binder resin particles may be coated with a polymer or monomer surfactant. For example, in the ink of the present invention, the binder resin particles may be microencapsulated with a surfactant, and the surface of the binder resin particles may be covered with the hydrophobic portion of the surfactant and may be micellar. Good. When the particle diameter of the binder resin particles is reduced, the colorant may be exposed from the surface of the binder resin particles. In this way, the colorant is exposed from the surface of the binder resin particles, and the ink ejection stability is lowered. By coating the surface of the binder resin particles with a surfactant, the colorant is not exposed from the surface of the binder resin particles even when the particle diameter of the binder resin particles is reduced.

  In addition, by coating the surface of the binder resin particles with a surfactant, the dispersibility of the binder resin particles in the dispersion solution can be improved and ink bleeding can be more effectively prevented. Also, by coating the surface of the binder resin particles with a surfactant, the particle surface is strengthened, the light resistance and color development of the ink are improved, and a strong ink film can be formed on the printing medium.

  The surfactant that coats the surface of the binder resin particles may be any one that covers the surface of the binder resin particles with the surfactant. For example, as the surfactant for covering the binder resin particles and encapsulating them, a monomer surfactant, a polymer surfactant, an aqueous surfactant, and a non-aqueous surfactant can be mentioned. Examples of the monomer surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. The polymer surfactants are classified into natural polymer surfactants, condensation polymer surfactants, and polymerized polymer surfactants. Examples of aqueous surfactants include inorganic compounds, natural derivatives, formalin condensates, polymers, and special surfactants. Examples of non-aqueous surfactants include alkylbenzene sulfonates, dioctyl sulfosuccinates, alkyl fatty acid salts, olefin / maleic anhydride copolymers, rosinates, alkyl imidazolines, alkyl diamates, and alkylamine acetates. Is mentioned.

Anionic surface active agents are those having a negative charge when dissolved in water, as a hydrophilic group, a carboxyl group, sulfuric acid group, sulfate group, and a phosphoric acid ester group, etc., as lipophilic group, C ₁₀ Those having ~ _C18 hydrocarbons and the like are generally used. Examples of anionic surfactants include fatty acid soap, alkenyl succinate, alkylbenzene sulfonate sodium salt, alkyl naphthalene sulfonate sodium salt, alkyl sulfate sodium salt, polyoxyethylene alkyl ether sulfate sodium salt, dialkyl sulfosuccinate sodium Examples thereof include salts, sodium alkyl phosphate, and polycarboxylic acid type polymer surfactants.

  Cationic surfactants have a positive charge when dissolved in water, and those having an amine group in a hydrophilic group are generally used. Examples of the cationic surfactant include alkyltrimethylammonium chloride and alkyldimethylbenzylammonium chloride.

  Nonionic surfactants have an oxyethylene chain in a hydrophilic group, and are classified into an ether type and an ester type. Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, and sorbitan fatty acid ester.

  Amphoteric surfactants have a negative charge or a positive charge when dissolved in water. Examples of amphoteric surfactants include alkyl betaines and amide betaines.

  Examples of the natural polymer surfactant include lignin sulfonate obtained by sulfonating natural lignin, carboxymethyl cellulose modified with cellulose, and hydroxyethyl cellulose. Examples of the condensation polymer surfactant include polymers obtained by formalin condensation of naphthalene sulfonate or melamine sulfonate.

  Examples of the polymeric polymer surfactant include ionic polymers or nonionic polymers obtained by polymerizing monomers having unsaturated bonds typified by acrylic acid. Examples of polymeric high molecular surfactants include homopolymers containing aqueous dispersants such as polyacrylates, polystyrene sulfonates, and acrylamides, and non-aqueous dispersants such as polyvinylpyrrolidone. . Examples of the polymeric high molecular surfactant include copolymers such as (meth) acrylic acid-maleic acid type, styrene-maleic acid type, acrylic acid-methyl acrylate (ethyl or butyl), maleic acid-isobutylene. It is done.

  As a method for microencapsulating the binder resin particles with a surfactant, for example, as described in Reference 1 (Japanese Patent Laid-Open No. 2005-97476), aqueous dispersion of binder resin particles having an anionic group on the surface Examples include a method in which a cationic surfactant is added to the liquid and mixed, and then an anionic surfactant is added for emulsification, and a polymerization initiator is added for emulsion polymerization. Also, for example, by optimizing the glass transition point and neutralization rate of a surfactant such as a styrene-acrylic acid-methacrylic acid terpolymer and a binder resin, Can be microencapsulated.

  In the ink of the present invention, the binder resin particles may include flat particles having at least one elliptical cross section. By including the flat particles of the binder resin having at least one elliptical cross section in the ink, when such ink lands on the print medium, it passes through the center of gravity of the flat particles on the surface of the print medium. The flat particles fall so that the long axis, which is the longest diameter, is along the surface of the print medium. That is, in the ink layer formed on the print medium, the flat particles are oriented so that their long axes are along the surface of the print medium.

  For this reason, the level difference of the unevenness | corrugation which arises on the ink layer surface on a printing medium resulting from the shape of the particle | grains of binder resin can be reduced. As a result, light scattering caused by unevenness on the surface of the ink layer can be reduced, so that a highly glossy printed matter can be obtained. Such flat particles of the binder resin can be produced by an extension polymerization method.

  In the case of ejecting the ink of the present invention onto paper, fabric, etc. that are particularly susceptible to bleeding, from the viewpoint of preventing bleeding, the average particle diameter of the binder resin particles may be 800 nm or more, or 800 nm or more. More preferably, it is 3000 nm or less. Accordingly, it is possible to more reliably prevent bleeding on the printing medium, so that printing can be performed without causing any bleeding without performing any pretreatment on the printing medium such as paper and fabric. Accordingly, it is possible to provide an ink particularly suitable for paper and textile printing.

  Furthermore, in the ink of the present invention, the colorant may be particles containing a rare earth metal (hereinafter also referred to as rare earth metal particles). As the rare earth metal particles, conventionally known phosphor particles containing rare earth metals can be used.

  If the colorant is a phosphor particle containing a rare earth metal, it can be suitably used as a so-called stealth ink. Stealth ink emits visible light and can be observed with the naked eye when the printed matter is irradiated with specific light rays such as ultraviolet rays or infrared rays. Ink that can not be. Therefore, stealth ink is used for printing markings for authenticating banknotes, apparel products, and the like. By using an ink containing rare earth metal particles as the stealth ink, the ink is more stable and a printed matter with high brightness can be obtained.

  Further, in the ink of the present invention, since the rare earth metal particles are encapsulated in the binder resin particles, it is possible to prevent bleeding on the printing medium. By using such an ink, fabric, leather Even on a print medium that easily bleeds, the print medium can be printed without causing any pretreatment without causing any pretreatment. That is, using the ink of the present invention as stealth ink, it can be suitably printed on fabric, leather, etc., and ink suitable for printing a mark for authenticity identification on fabric and leather products is used. Can be provided.

  In the ink of the present invention, the dispersion solution may further contain an emulsifier for emulsifying or suspending the binder resin. Further, the dispersion solution may contain other resin dissolved in the dispersion solution in addition to the emulsion resin or the suspended binder resin. The other resin is dissolved in the dispersion solution and can adjust the viscosity of the ink. In addition, when moisture dries by drying, when another film is formed into a film by bonding between emulsion resins or suspended binder resins, the other resin is further used as a binder as an emulsion or suspension of binder resins. It may have a function of strongly bonding. As another resin that functions as such a binder, PVA, polyvinylpyrrolidone, rosin, vinyl acetate, acrylic, and the like can be used. By using the other resin as a binder and binding the binder resins strongly, it is possible to prevent ink bleeding on the print medium.

[Inkjet recording method]
An ink jet recording method for printing on a print medium using the ink of the present invention will be described. The inkjet recording method of the present invention includes a discharge step of discharging the ink of the present invention onto a printing medium, and a first heating step of heating the ink that has landed on the printing medium at a temperature at which the dispersion solution is evaporated. . In the ink jet recording method of the present invention, when the binder resin is a polymer compound that is cured by heat, after the first heating step, the ink that has landed on the printing medium is dissolved at a temperature at which the binder resin is dissolved. A second heating step of heating may be further included.

  In the ink jet recording method of the present invention, only the first heating step can be performed by using a low TG resin or a mixture of a high TG resin and a low TG resin as the binder resin. There is an advantage that the heating temperature of the heating process can be lowered.

  The manner in which the ink of the present invention lands on the print medium and is fixed will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating a state in which ink according to an embodiment of the present invention lands on a medium (print medium) and prints the medium.

  As shown in FIG. 2A, before landing on the medium, the binder resin particles 1 are dispersed in the dispersion solution. As shown in FIG. 2B, the ink immediately after being ejected onto the medium and landed on the medium has the binder resin particles 1 laminated on the medium (ejection step). Here, the ink ejected to the medium can be ejected from the nozzle, but the average particle diameter of the binder resin particles 1 contained in the ink may be 1/10 or less of the nozzle diameter of the nozzle that ejects the ink. preferable. Thereby, the discharge stability from a nozzle improves more.

  Next, the ink is heated at a temperature at which water (solvent) in the dispersion solution is evaporated (first heating step). The heating means in the first heating step only needs to be able to heat the ink layer on the medium and evaporate the solvent. Therefore, the heating means is not limited to the above-described form, and the surface on which the ink of the medium has landed is infrared or far. Heating may be performed by irradiating infrared rays, electromagnetic induction heating, applying hot air, or the like. In addition, the installation position of the heating means may be in the vicinity of the platen on which the medium is placed in the printer used in the ink jet recording method of the present invention, but may be installed in front of or behind the platen, or outside the printer. It may be attached. As a result, the installation position is not limited as long as the solvent can be evaporated and the ink layer can be dried, polymerized, melted and fixed.

  Depending on the purpose of printing, the printing can be completed only by heating the ink from the state shown in FIG. 2B and removing the dispersion solution. That is, when a binder resin that does not have thermoplasticity, thermal melting property, or thermal polymerization property is used, the ink can be fixed on the medium only by the first heating step. Since the colorant 2 is dispersed or dissolved in the binder resin particles 1, the heating ink is heated at a high temperature in order to disperse or dissolve the colorant in the binder resin. There is no need to go through.

  When a heat-curing polymer compound or a heat-curing polymer compound is used as the binder resin, the ink on the medium is further heated at a temperature at which the binder resin is melted (second heating step). When the heated and melted binder resin is integrated, the state shown in FIG. As a result, the binder resin is firmly fixed on the medium.

  At this time, the colorant 2 is already dispersed or dissolved in the binder resin. Therefore, even when the binder resin is finally fixed to the medium, a high-temperature heating step is further performed to dissolve the binder resin and disperse or dissolve the colorant therein as in the case of the conventional ink. There is no need to do it. In addition, the ink according to the present invention has an advantage that the heating temperature for fixing the ink to the medium is low.

  In the conventional ink, since the colorant and the resin particles are dispersed independently in the dispersion solution, the colorant cannot be dispersed in the dispersion solution unless the resin particles are melted. However, in the ink according to the present invention, since the colorant is already dispersed or dissolved in the binder resin, it is not necessary to increase the heating temperature in order to disperse or dissolve the colorant in the binder resin. The heating temperature required for melting and integrating and fixing to the medium is low.

  That is, in the ink jet recording method according to the present invention, the ink is heated at a low temperature of, for example, 40 ° C. to 60 ° C., so that the ink in the nozzles of the ink jet head is dried by the high temperature during the ink heating. Can be prevented. As a result, ink ejection failure can be prevented.

  Next, how the ink is fixed on the medium when an ultraviolet curable resin is used as the binder resin will be described with reference to FIG. FIG. 4 is a schematic diagram illustrating a state in which ink according to another embodiment of the present invention is fixed to a medium.

  As shown in FIG. 4 (a), the water (solvent) in the dispersion solution 3 is caused by the heater 5 placed on the surface of the medium 4 facing away from the ink landing surface. It heats at the temperature which evaporates (1st heating process). The ink includes binder resin particles 1 in which a colorant 2 is dispersed or dissolved, and a dispersion solution 3 containing water, a solvent, and a dispersant. As the binder resin, a high molecular compound curable with ultraviolet light or a high molecular compound curable with ultraviolet light is used.

  As shown in FIG. 4B, the heated ink evaporates the moisture (solvent) in the dispersion solution 3 and is prevented from oozing and is deposited on the medium 4. At this time, the binder resin may be temporarily cured by irradiating weak ultraviolet rays together with heating by the heater 5.

  Next, as shown in FIG. 4 (c), the ink on the medium 4 is irradiated with the UV lamp 6 (irradiation process) to cure the binder resin and firmly fix the ink on the medium 4. 7 is formed. As described above, when an ultraviolet curable resin is used as the binder resin, the solvent of the ink is evaporated by heating in the first heating process and is cured by ultraviolet irradiation in the irradiation process. A high ink film can be fixed on the media.

  In the ink jet recording method according to the present invention, the medium (printing medium) 4 is particularly effective when it is a non-absorbing medium such as plastic that easily causes bleeding, paper, or fabric. In the ink jet recording method according to the present invention, since the colorant 2 is printed on the media 4 using the ink according to the present invention in which the binder resin particles 1 are encapsulated, the ink bleeding on the media 4 is prevented. By using such an ink, it is possible to carry out no pretreatment on the medium 4 even on the medium 4 that is easy to bleed, such as non-absorbent media, paper, fabric, leather, etc. It is possible to print without causing bleeding.

<Ink production method>
The method for producing an ink according to the present invention is a liquid that is either a binder resin liquid or a binder resin material liquid in which a colorant is dispersed or dissolved. Placing in a liquid that does not dissolve and stirring.

  The binder resin material liquid is intended to be a monomer liquid that becomes a desired binder resin by a polymerization reaction, a polymer liquid that becomes a desired binder resin by crosslinking, or the like.

  Any one of the binder resin liquid and the binder resin material liquid (hereinafter referred to as the binder resin liquid) is in a liquid incompatible with the liquid, that is, the ink dispersion according to the present invention. It is preferable to inject a binder resin liquid into the liquid to be used because the binder resin or particles of the material can be dispersed in the dispersion solution. When the binder resin liquid is sprayed, it is preferably sprayed at a high speed, and for example, spraying using a sprayer or the like is preferable.

  In the binder resin liquid to be sprayed, a colorant is dispersed or dissolved in advance. Therefore, a binder resin particle in which a colorant is dispersed or dissolved therein or a binder resin material particle dispersed in a dispersion solution is obtained. Then, this dispersion solution is stirred at high speed to be emulsified (emulsified), and binder resin particles having a substantially spherical shape or a substantially elliptic shape are formed in the dispersion solution.

  When a binder resin material is used, after emulsifying the dispersion solution containing the binder resin material or suspending the binder resin material in the dispersion solution, the binder resin material is appropriately polymerized. A binder resin may be formed by a crosslinking reaction or the like (emulsion polymerization or suspension polymerization). Alternatively, a binder resin material may be polymerized after preparing a mixed solution of an emulsified dispersion solution containing a binder resin material and a binder resin material suspended in the dispersion solution.

  Thereby, the ink which concerns on this invention or the undiluted | stock solution of the ink which concerns on this invention before making it a desired density | concentration can be obtained.

  When the dispersion solution containing the binder resin liquid and the binder resin material liquid is stirred at high speed, the binder resin particles become substantially spherical or elliptical due to the surface tension of the binder resin. In conventional inks, it is difficult to use a polymer resin because the chains between the resins are entangled and the ejection becomes unstable and the solubility in the dispersion is poor. However, according to the method for producing an ink of the present invention, the dispersion liquid containing the binder resin liquid and the binder resin material liquid is emulsified or suspended at high speed, so that the binder resin particles are substantially spherical or It becomes a substantially elliptical shape, and the chains between the resins do not entangle. As a result, the ejection stability of the ink is improved and the solubility in the dispersion solution is also improved.

  Further, in the ink production method of the present invention, a colorant dispersion solution in which a colorant is dispersed in a binder resin dispersion solution prepared by emulsion polymerization of a dispersion solution containing a binder resin material, a wax dispersion solution, a flocculant, Alternatively, the binder resin particles may be produced by an emulsion polymerization aggregation method in which an electrolyte is added and mixed, and heated and stirred to form aggregated particles of the colorant and the binder resin. In this method, the fusion state, shape, and surface properties of the aggregated particles can be controlled by controlling the pH, temperature, time, and the like during aggregation. After controlling these, the aggregated particles are washed and dried to produce binder resin particles.

  Furthermore, in the method for producing the ink of the present invention, a colorant is added to a thermosetting binder resin material, the resin material is dissolved in a solvent, and the solvent is vigorously mixed to finely form suspension droplets. The binder resin particles may be produced by a dissolution suspension method in which the particle size is increased.

  In addition, a polyester resin, colorant and wax are dispersed in an organic solvent to form an oil phase, and the water phase in which the particle control agent is dispersed in water and the oil phase are mixed to contain a colorant having a sharp particle size distribution. Create resin oil droplets. In this process, polyester polymer particles containing a colorant may be formed by simultaneous polymerization reaction and used as binder resin particles contained in the ink of the present invention.

  An embodiment of an ink production method according to the present invention will be described. Here, as an embodiment of the ink according to the present invention, a mode in which the binder resin is a polymer compound that is cured by heat, the colorant is pigment fine particles, and the dispersion solution is water will be described. Moreover, FIG.5 and FIG.6 is used in description of the following manufacturing methods. FIG. 5 is a diagram showing a flow of an embodiment of the ink manufacturing method according to the present invention. FIG. 6 is a diagram schematically showing a configuration of an apparatus used in an embodiment of the ink manufacturing method according to the present invention.

  As shown in FIG. 5, first, a stock solution of a polymer compound is generated (step S1). Here, the pigment fine particles to be dispersed in the polymer compound particles are added to the stock solution of the polymer compound and dispersed. Additives may be added according to the purpose.

  Here, a method for producing pigment fine particles will be described as a pre-process of step S1. Examples of the method for producing pigment fine particles include a build-up method. The build-up method is a method for producing fine particles by producing solid-phase materials (raw materials) through reaction, supersaturation, nucleation, and growth from high-purity raw materials in the order of vapor, liquid atoms, molecules, and ions. is there. Industrially, it is a method used for the synthesis of high-purity fine particles having a particle size of several nm to several tens of nm. As a build-up method, Japanese Patent No. 3936558 can be referred to as a reference.

  Next, the stock solution of the polymer compound is emulsified (step S2). That is, the apparatus shown in FIG. 6 includes a container 10 and a stirrer 20. A stock solution of a polymer compound composed of unreacted monomers is contained in the container 10. A solvent for dispersing polymer compound particles such as water and a solvent is contained in the stirrer 20.

  The stock solution is agitated at high speed by the agitating blade 21 while injecting the stock solution from the container 10 to the agitator 20 via the pipe 11 by the pump 12. By this operation, an emulsion liquid composed of spherical, particle-sized particles of the polymer compound stock solution dispersed in a solvent composed of water or the like is formed.

  As the means for emulsification, an apparatus used for emulsification and dispersion such as an ultrasonic stirrer can be used in addition to various mechanical stirrers.

  In addition, since the pigment is dispersed in advance in the stock solution, fine particles of the pigment are dispersed in the polymer solution stock particles constituting the emulsion. In addition, aggregation of pigment fine particles present in the stock solution of the polymer compound is suppressed by the viscosity of the stock solution. In this way, particles of a polymer compound stock solution in which pigment fine particles are uniformly dispersed inside can be formed in water.

  Next, the stock solution of the polymer compound is emulsified or suspended to produce a stock solution of ink (step S3). For example, the stock solution may be heated or emulsified or suspended by polymerization reaction of the stock solution to make it rubber (for example, using a cross-linking agent mixed in water). By emulsifying or suspending the stock solution of the polymer compound, the pigment fine particles in the polymer compound particle are fixed, and reaggregation is completely eliminated. Further, depending on the application, it is not essential to emulsion or suspend the stock solution of the polymer compound, and the procedure may proceed to step S4 with the stock solution particles dispersed in water.

  Finally, the ink stock solution obtained in step S3 is diluted to a desired concentration to obtain an ink having a desired concentration or viscosity (step S4). In step S4, an additive may be appropriately added to adjust the surface tension of the ink.

<Additional notes>
As described above, in one embodiment of the ink according to the present invention, the binder resin particles 1 are dispersed in the dispersion solution 3 as a dispersoid, and the colorant 2 is dispersed or dissolved in the binder resin particles 1. .

  According to the ink according to the present invention, the surface area of the ink can easily be substantially spherical or oval even if the binder resin particles 1 in which the colorant 2 is dispersed or dissolved are enlarged. In addition, by ensuring the lyophilicity between the resin itself and the dispersion solvent 3 by surface treatment or encapsulation, it is possible to ensure ejection stability without being affected by the nonuniformity caused by the colorant 2. Can do. That is, by increasing the size of the binder resin particles 1 encapsulating the colorant 2 contained in the ink, ink bleeding on the medium 4 can be prevented while maintaining ink ejection stability without being affected by the colorant 2. It is possible to prevent.

  In the ink according to the present invention, the average particle size of the binder resin particles 1 is 50 nm or more.

  With the above configuration, even when the average particle diameter of the binder resin particles 1 is 50 nm or more, the ejection stability can be ensured, so that the ink bleeding on the medium 4 and the binder resin particles are ensured while ensuring the ejection stability. 1 aggregation and colorant 2 alteration can be further prevented.

  In the ink according to the present invention, the average particle diameter of the binder resin particles 1 is 80 nm or more.

  With the above configuration, even when the average particle diameter of the binder resin particles 1 is 80 nm or more, the ejection stability can be ensured, so that the ink bleeding on the medium 4 and the binder resin particles are ensured while ensuring the ejection stability. 1 aggregation and colorant 2 alteration can be further prevented.

  In the ink according to the present invention, the binder resin particles 1 are formed by emulsion polymerization or suspension polymerization of a monomer of the binder resin material and the colorant.

  With the above configuration, the binder resin particles 1 can be easily formed into a substantially spherical shape or a substantially elliptical shape. Therefore, even when the diameter of the binder resin particles 1 is increased, discharge stability is ensured.

  Furthermore, in the ink according to the present invention, in the binder resin particles 1, the average content ratio of the binder resin and the colorant 2 is 20:80 to 95: 5 by weight ratio.

  With the above configuration, precipitation of the binder resin particles 1 can be further suppressed.

  In the ink according to the present invention, the binder resin particles 1 have a substantially spherical shape, a substantially oval shape, or a substantially disk shape.

  With the above configuration, ink ejection stability is further improved.

  Furthermore, in the ink according to the present invention, the average particle diameter of the colorant 2 is 50 nm or less.

  With the above configuration, the colorability of the ink is further improved, and high-definition printing is possible. Moreover, since the colorant is included in the particles of the binder resin, the light resistance of the ink can be improved even if the average particle diameter of the colorant is reduced to 50 nm or less.

  Further, in the ink according to the present invention, the colorant 2 includes an organic pigment, an inorganic pigment, a disperse dye, an acid dye, a reactive dye, titanium oxide, magnetic particles, alumina, silica, ceramic, carbon black, metal nanoparticles, and an organic metal. And at least one selected from the group consisting of:

  With the above configuration, ink that can be used for various purposes can be provided.

  In the ink according to the present invention, the binder resin is at least one resin that is cured by light or heat or selected from a cured polymer compound.

  With the above configuration, ink that can be used for various purposes can be provided.

  In the ink according to the present invention, the binder resin is an ultraviolet curable polymer compound.

  With the configuration described above, it is possible to provide an ink that fixes a highly glossy and high-strength ink film on the medium 4.

  Furthermore, in the ink according to the present invention, the main component of the dispersion solution 3 is at least one of water and a hydrophilic solvent, and the binder resin particles 1 are emulsion or suspended in at least one of the water and the hydrophilic solvent. . Thereby, more suitable printing is possible.

  In the ink according to the present invention, the main component of the dispersion solution 3 is at least one of water and a hydrophilic solvent, and the surface of the binder resin particles 1 is subjected to a hydrophilic treatment.

  According to said structure, since the surface of the binder resin particle 1 which touches water or a hydrophilic solvent has affinity with respect to water or a hydrophilic solvent, the binder resin particle 1 is disperse | distributed suitably in the dispersion solution 3. The Even if the particle diameter of the binder resin particle 1 is increased, the ink is not separated in the nozzle, and a predetermined amount of ink can be reliably discharged from the nozzle. Furthermore, since the affinity with the dispersion solution 3 is ensured on the surface of the hydrophilic binder resin particles 1, it is not necessary to select hydrophilic binder resin materials and colorants 2, and various binder resin materials can be used. And Colorant 2 can be used.

  Furthermore, in the ink according to the present invention, the hydrophilization treatment is preferably an emulsification treatment in which the surface is emulsified using a surfactant or a dispersant, or an introduction treatment in which a hydrophilic group is introduced into the surface. Thereby, the surface of binder resin can be suitably hydrophilized. Thereby, the surface of the binder resin particle 1 can be suitably hydrophilized.

  In the ink according to the present invention, the average particle size of the binder resin particles 1 is 800 nm or more.

  According to the above configuration, since it is possible to prevent bleeding on the medium 4 more reliably, even when ink is ejected onto paper, fabric, or the like that is likely to cause bleeding, there is nothing on the medium 4. It is possible to perform printing without causing blurring without performing the pretreatment. Accordingly, it is possible to provide an ink particularly suitable for paper and textile printing.

  In the ink according to the present invention, the colorant 2 is a particle containing a rare earth metal.

  According to said structure, it can use suitably as what is called stealth ink. By using an ink containing particles containing a rare earth metal as the stealth ink, the ink is more stable and a printed matter with high brightness can be obtained. Further, since the particles containing rare earth metal are encapsulated in the binder resin particles 1, it is possible to prevent the ink from bleeding on the media 4. By using such an ink, fabric, leather, etc. Even on the medium 4 that is likely to bleed, printing can be performed without causing bleed without performing any pretreatment on the medium 4. That is, using the ink of the present invention as stealth ink, it can be suitably printed on fabric, leather, etc., and ink suitable for printing a mark for authenticity identification on fabric and leather products is used. Can be provided.

  In the ink according to the present invention, it is preferable that a resin different from the binder resin is dissolved in the dispersion solution 3.

  According to said structure, it is possible to adjust the viscosity of an ink. Further, when moisture in the ink flies by drying, the binder resin can be further strongly bonded as a binder when the other resin is formed into a film by bonding between the binder resins. Then, by using the other resin as a binder and binding the binder resins strongly, it is possible to prevent ink bleeding on the print medium.

  In the ink according to the present invention, the surface of the binder resin particle 1 is coated with a polymer or monomer surfactant.

  According to said structure, the binder resin particle 1 is microencapsulated with surfactant. When the particle diameter of the binder resin particles 1 is reduced, the colorant 2 may be exposed from the surface of the binder resin particles 1. As described above, when the colorant 2 is exposed from the surface of the binder resin particles 1, the ejection stability of the ink is lowered. By coating the surface of the binder resin particle 1 with a surfactant, the colorant 2 is not exposed from the surface of the binder resin particle 1 even when the particle diameter of the binder resin particle 1 is reduced.

  Also, by coating the surface of the binder resin particles 1 with a surfactant, the dispersibility of the binder resin particles 1 in the dispersion solution 3 can be improved and ink bleeding can be more effectively prevented. Further, by coating the surface of the binder resin particles 1 with a surfactant, the particle surface is strengthened, the light resistance and color development of the ink are improved, and a strong ink film can be formed on the medium 4.

  In the ink according to the present invention, the binder resin particles 1 include flat particles having at least one elliptical cross section.

  According to the above configuration, when the ink lands on the medium 4 by including flat particles of the binder resin having at least one elliptical cross section in the ink, on the surface of the medium 4, The flat particles fall down so that the long axis, which is the longest diameter among the diameters passing through the center of gravity of the flat particles, is along the surface of the media 4. That is, in the ink layer formed on the medium 4, the flat particles are oriented so that their long axes are along the surface of the medium 4.

  For this reason, the height difference of the unevenness generated on the surface of the ink layer on the medium 4 due to the shape of the binder resin particles 1 can be reduced. As a result, light scattering caused by unevenness on the surface of the ink layer can be reduced, so that a highly glossy printed matter can be obtained.

  One embodiment of the inkjet recording method according to the present invention includes a discharge step of discharging the ink onto a print medium, and first heating that heats the ink that has landed on the print medium at a temperature at which the solvent in the dispersion solution is evaporated. Process.

  With the above configuration, it is possible to suitably print on various media 4.

  In the inkjet recording method according to the present invention, when the binder resin is a polymer compound that is cured by heat, the ink that has landed on the printing medium is dissolved in the binder resin after the first heating step. A second heating step of heating at a temperature is further included.

  With the above configuration, the ink can be more firmly fixed on the medium 4.

  Furthermore, in the ink jet recording method according to the present invention, when the binder resin is a polymer compound that is cured by light, an irradiation step of irradiating the ink landed on the printing medium with light after the first heating step is performed. In addition.

  With the configuration described above, it is possible to fix an ink film having higher gloss and strength on the medium 4.

  In the ink jet recording method according to the present invention, the average particle diameter of the binder resin particles is 1/10 or less of the nozzle diameter of the nozzle that discharges the ink in the discharging step.

  With the above configuration, the ejection stability is further improved.

  In the ink jet recording method according to the present invention, the printing medium exhibits a particularly great effect when it is a non-absorbing medium such as plastic that is likely to cause bleeding, paper, or fabric.

  According to the above configuration, since the colorant 2 is included in the binder resin particles 1 in the ink, it is possible to prevent bleeding of the ink on the medium 4, and by using such an ink, Even on a medium 4 that is easy to bleed, such as non-absorbent media, paper, fabric, leather, etc., printing can be performed without causing bleed without performing any pretreatment on the medium 4.

  Although one embodiment of the ink manufacturing method according to the present invention is not limited to a specific method, it is one of a binder resin liquid and a binder resin material liquid, and the colorant is It includes a step of putting the liquid that is dispersed or dissolved in a liquid that is incompatible with the liquid and stirring.

  With the above configuration, the ink according to the present invention can be preferably manufactured.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be suitably used for inks such as dyes and coating agents.

1 Binder resin particles (binder resin particles)
2 Colorant 3 Dispersion solution 4 Media (printing medium)

Claims (20)

  Binder resin particles are dispersed in a dispersion solution as a dispersoid, and a colorant is dispersed or dissolved in the binder resin particles.   The ink according to claim 1, wherein the binder resin particles have an average particle size of 50 nm or more.   The ink according to claim 1, wherein the binder resin particles have an average particle diameter of 80 nm or more.   4. The binder resin according to claim 1, wherein the binder resin particles are formed by emulsion polymerization or suspension polymerization of a binder resin material monomer and the colorant. 5. ink.   5. The binder resin according to claim 1, wherein the binder resin particles have an average content ratio of the binder resin and the colorant of 20:80 to 95: 5 by weight. The ink described.   The ink according to any one of claims 1 to 5, wherein the binder resin particles have a substantially spherical shape, a substantially elliptical shape, or a substantially disk shape.   The ink according to claim 1, wherein the average particle diameter of the colorant is 50 nm or less.   The ink according to any one of claims 1 to 7, wherein the binder resin is at least one resin selected from a polymer compound that is cured by light or heat or is cured. The main component of the dispersion solution is at least one of water and a hydrophilic solvent,
The ink according to claim 1, wherein the binder resin particles are emulsified or suspended in at least one of the water and the hydrophilic solvent. The main component of the dispersion solution is at least one of water and a hydrophilic solvent,
The ink according to claim 1, wherein the surface of the binder resin particles is subjected to a hydrophilic treatment.   The ink according to claim 10, wherein the hydrophilization treatment is an emulsification treatment in which the surface is emulsified using a surfactant or a dispersant, or an introduction treatment in which a hydrophilic group is introduced into the surface.   The ink according to claim 1, wherein the binder resin particles have an average particle size of 800 nm or more.   The ink according to claim 1, wherein the colorant is a particle containing a rare earth metal.   The ink according to claim 1, wherein a resin different from the binder resin is dissolved in the dispersion solution.   The ink according to any one of claims 1 to 9, wherein the surface of the binder resin particles is coated with a surfactant.   The ink according to claim 1, wherein the binder resin particles include flat particles having at least one elliptical cross section. A discharge step of discharging the ink according to any one of claims 1 to 16 to a print medium;
And a first heating step of heating the ink landed on the printing medium at a temperature at which the solvent in the dispersion solution is evaporated.   When the binder resin is a polymer compound that is cured by heat, the method further includes a second heating step of heating the ink landed on the printing medium at a temperature at which the binder resin is dissolved after the first heating step. The inkjet recording method according to claim 17, wherein:   18. The ink jet recording method according to claim 17, wherein an average particle diameter of the binder resin particles is 1/10 or less of a nozzle diameter of the nozzle for discharging the ink in the discharging step. The ink jet recording method according to claim 17, wherein the print medium is a fabric.

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