JP2013163705A - Inkjet printing method and ink set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printing technique that can perform the coloring improvement of a printed image that uses a non-aqueous dye ink.SOLUTION: An ink set for inkjet printing that consists of a pretreatment liquid containing at least an inorganic particle, water, and a solvent and a non-aqueous dye ink containing a dye and a solvent is used, the pretreatment liquid is applied to a print medium surface beforehand, and then printing is performed by ejecting the non-aqueous dye ink. The inorganic particle shows an oil absorption amount of 10-200 ml/100 g and a specific surface area of 1-600 m/g, and has preferably an average particle diameter in a range of 0.5-15 μm. The non-aqueous dye ink preferably contains at least a fluorescent dye, a solvent, and a urethane modified acrylic resin.

Description

The present invention relates to an ink jet printing method and an ink set that improve printing density by suppressing penetration of ink into a printing medium and preventing back-through and bleeding.

  Fluorescent pigments and fluorescent dyes exist as color materials that generate fluorescence. Fluorescent pigment inks using fluorescent pigments have an average pigment particle size increased to a submicron size in order to obtain fluorescence intensity. The storage stability of the ink has been a problem (see Patent Document 1).

  As for fluorescent dye inks, a production method has been conventionally known in which a fine particle polymer dispersion dyed with a dye is used (see Patent Document 2). However, the fluorescent dye ink has a problem in that the color material penetrates from the surface of the printing medium to the inside, so that sufficient fluorescence intensity cannot be obtained and it is easy to get through. This is a problem applicable not only to fluorescent dyes but also to all non-aqueous inks using dyes.

  On the other hand, conventionally, there are various types of special paper having an ink receiving layer composed of inorganic particles and a fixing resin on the surface in order to keep the color material on the surface of a printing medium such as paper. However, in order to obtain the same effect with plain paper, a means for keeping the color material on the paper surface during printing is required. In the case of water-based ink, as a method of keeping the color material on the surface of plain paper without penetrating with the solvent, a reactive liquid is contained in the ink and a treatment liquid containing a substance that reacts with the substance is prepared. In addition, a method has been proposed in which a coloring material is aggregated and hardly penetrated by discharging the treatment liquid over the ink and causing both substances to react on the paper surface (see, for example, Patent Document 3). ). However, no method has yet been proposed that shows the same effect for non-aqueous dye inks.

JP 08-281930 A JP 2000-198263 A JP 2007-276387 A

  In view of the above circumstances, the present invention can improve the color development of a printed image using a non-aqueous dye ink, and the non-aqueous dye ink using a fluorescent dye ink can increase the fluorescence intensity in addition to improving the color development. It aims to provide a method.

  As a result of intensive studies of the above object, the present inventors applied a predetermined pretreatment liquid to the printing surface of the print medium, and discharged a non-aqueous dye ink using a fluorescent dye thereon, The inventors have found that the color development and the fluorescence intensity of a printed image are improved, and have completed the present invention.

  That is, according to one aspect of the present invention, the object is an ink jet printing comprising a pretreatment liquid containing at least inorganic particles, water, and a solvent, and a non-aqueous dye ink containing a dye and a solvent. Achieved with an ink set.

  According to another aspect of the present invention, the object is to apply a pretreatment liquid containing at least inorganic particles, water, and a solvent to a print medium, and then print a non-aqueous dye ink on the application surface. This is achieved by the characteristic ink jet printing method.

  According to the present invention, by treating the surface of the print medium with a pretreatment liquid containing at least inorganic particles, water, and a solvent, the surface of the print medium is sealed, and the dye in the printed dye ink is printed. It stays on the medium and the penetration of the coloring material into the printing medium is suppressed. Color development is achieved with dyes, and color development and fluorescence intensity are improved with fluorescent dyes. Further, since the penetration of the coloring material into the printing medium is suppressed, it is inevitably prevented from see-through and bleeding.

Hereinafter, the present invention will be described in more detail.

1. Non-aqueous dye ink The non-aqueous dye ink used in the present invention is mainly composed of at least a dye and a solvent, but may contain other components as necessary.

1-1. Examples of the dye include conventionally known azo-based, anthraquinone-based, and azine-based oil-soluble dyes and fluorescent dyes.
Specific examples of fluorescent dyes are color index numbers (CI): BASIC YELLOW 1, BASIC YELLOW 40, BASIC RED 1, BASIC RED 13, BASIC VIOLET 11: 1, BASIC VIOLET 7, BASIC VIOLET 10, BASIC ORANGE 22, BASIC BLUE 7, BASIC GREEN 1, ACID YELLOW 3, ACID YELLOW 7, ACID RED 52, ACID RED 77, ACID RED 92, ACID BLUE 9, DISPERSE YELLOW 82, DISPERSE ORANGE 11, DISPERSE RED 58, DISPERSE BLUE 7 , DIRECT YELLOW 85, DIRECT ORANGE 8, DIRECT RED 9, DIRECT BLUE 22, DIRECT GREEN 6, FLUORESCENT BRIGTHING AGENT 55, FLUORESCENT BRIGTHING WHITE XWS 52, FLUORESCENT 162, FLUORESCENT 112, SOLVENT YELLOW 44, SOLVENT YELLOW 116, SOLVENT RED 49, Typical examples include SOLVENT BLUE 5, SOLVENT PINK, SOLVENT GREEN 7, IGMENT YELLOW 1, PIGMENT BLUE 15, PIGMENT GREEN 7, PIGMENT RED 53, PIGMENT RED 57, and FBA 184. These fluorescent dyes can be used alone or in combination of two or more. These fluorescent dyes may be used in combination with the above oil-soluble dye or other dyes having no fluorescence. Furthermore, in a color tone in which a fluorescent color is difficult to obtain, a known ordinary dye / pigment and a fluorescent brightening agent may be combined to give a pseudo fluorescence.

  The content of the fluorescent dye in the fluorescent dye ink can be set to about 0.01 to 5% by mass, preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass. If it is less than the above range, the printing density is low and the color development and fluorescence intensity are insufficient, and if it exceeds the above range, it is difficult to speak the effect of fluorescence intensity.

1-2. Solvent The solvent is not particularly limited as long as it functions as an ink solvent, that is, a vehicle, and may be any of a volatile solvent and a hardly volatile solvent. However, in the present invention, from the environmental viewpoint, the solvent preferably contains a hardly volatile solvent as a main component. The boiling point of the hardly volatile solvent is preferably 200 ° C. or higher, more preferably 240 ° C. or higher. It is preferable to use a solvent solubility parameter (SP value) of 6.5 (cal / cm ³ ) ^1/2 or more and 10.0 (cal / cm ³ ) ^1/2 or less, 7.0 ( It is more preferable to use a cal / cm ³ ) ^1/2 or more and 9.0 (cal / cm ³ ) ^1/2 or less.

  As the solvent, any organic solvent such as a nonpolar organic solvent and a polar organic solvent can be used. These may be used alone or in combination of two or more as long as they form a single phase. In the present invention, a nonpolar organic solvent and a polar organic solvent are preferably used in combination, and the solvent is preferably composed of 20 to 80% by mass of a nonpolar solvent and 80 to 20% by mass of a polar solvent. More preferably, the solvent is composed of ˜45 mass% nonpolar solvent and 55-70 mass% polar solvent.

1-2-1. Nonpolar solvent As the nonpolar organic solvent, hydrocarbon solvents such as naphthenic, paraffinic, and isoparaffinic solvents can be used. Specifically, aliphatic saturated hydrocarbons such as dodecane, “Isoper, Exol” manufactured by ExxonMobil Corporation (Both are trade names), “Solvent, normal paraffin H” (both trade names) manufactured by Nippon Oil Corporation, “Sansen, Thamper” (both trade names) manufactured by Sun Sekiyu Co., Ltd., and the like. These can be used alone or in combination of two or more.

1-2-2. Polar solvent Examples of the polar organic solvent include ester solvents, alcohol solvents, fatty acid solvents, ether solvents, and the like. These can be used alone or in combination of two or more.

  Examples of the ester solvent include higher fatty acid esters having 5 or more, preferably 9 or more, and more preferably 12 to 32 carbon atoms in one molecule. For example, isodecyl isononanoate, isotridecyl isononanoate, and isononanoic acid. Isononyl, methyl laurate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, isooctyl palmitate, hexyl palmitate, isostearyl palmitate, isooctyl isopalmitate, methyl oleate, ethyl oleate, isopropyl oleate, oleic acid Butyl, hexyl oleate, methyl linoleate, isobutyl linoleate, ethyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isopate isostearate Pill, 2-octyldodecyl pivalate, soybean oil methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, diisopropyl adipate, diisopropyl sebacate, diethyl sebacate, propylene glycol monocaprate, trimethylol tri-2-ethylhexanoate Examples thereof include propane and glyceryl tri-2-ethylhexanoate.

  Examples of the alcohol solvent include aliphatic higher alcohols having 12 or more carbon atoms in one molecule. Specifically, higher alcohols such as isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, and oleyl alcohol. Examples include alcohol.

  Examples of the fatty acid solvent include fatty acids having 4 or more, preferably 9 to 22 carbon atoms in one molecule, such as isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, and isostearic acid. Can be mentioned,

  Examples of ether solvents include glycol ethers such as diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, propylene glycol dibutyl ether, and acetates of glycol ethers.

1-3. Resin As the resin, an alkyd resin, an acrylic resin or the like having a polar functional group such as a urethane group, an epoxy group, or an ester group can be suitably used. More preferably, a urethane-modified acrylic resin, particularly a fine particle comprising an acrylic polymer containing an alkyl (meth) acrylate unit having a long-chain alkyl group having 12 or more carbon atoms and a (meth) acrylate unit having a urethane group. It is good to use. Here, “(meth) acrylate” means acrylate and methacrylate.

  The alkyl (meth) acrylate unit has a long-chain alkyl group having 12 or more carbon atoms, so that it has excellent affinity with a non-aqueous solvent and functions to increase the dispersion stability of the resin in the non-aqueous solvent. Can do. The alkyl chain of the ester moiety may be linear or branched. The upper limit of the carbon number of the alkyl group is not particularly limited, but is preferably 25 or less from the viewpoint of easy availability of raw materials. Examples of the alkyl group having 12 or more carbon atoms include dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosanyl group, heenicosanyl group, docosanyl group, isododecyl group, isooctadecyl group. Etc. These alkyl (meth) acrylate units may contain a plurality of these.

  The (meth) acrylate unit having the urethane group has a highly polar urethane group (urethane bond), thereby taking in the dye and forming an insoluble part in the solvent. The urethane group constitutes a side chain (branch) together with the long-chain alkyl group with respect to the main chain (trunk) of the acrylic polymer. The branch containing the urethane group may be a polyurethane in which urethane bonds are repeated to form a branch polymer.

The molecular weight (mass average molecular weight) of the acrylic polymer is not particularly limited, but when used as an inkjet ink, it is preferably about 10,000 to 100,000, and preferably about 20,000 to 80,000 from the viewpoint of ink ejection. Is more preferable.
The glass transition temperature (Tg) of the acrylic polymer is preferably normal temperature or lower, and more preferably 0 ° C. or lower. Thereby, when the ink is fixed on the recording medium, the film formation can be promoted at room temperature.

  The particle size of the fine resin is not particularly limited, but when used as an inkjet ink, it is necessary to make the particle size sufficiently small with respect to the nozzle diameter, and usually 0.3 μm or less is more preferable. Is 0.1 μm or less.

The acrylic polymer has an alkyl (meth) acrylate (A) having an alkyl group having 12 or more carbon atoms (hereinafter also referred to as “monomer (A)”) and a reactivity having a functional group capable of reacting with an amino group. In a copolymer of a monomer mixture containing (meth) acrylate (B) (hereinafter also referred to as “monomer (B)”) (hereinafter, this copolymer is also referred to as “trunk polymer”), an amino group and It can manufacture preferably by introduce | transducing a urethane group by reaction of the functional group which can react, amino alcohol, and a polyvalent isocyanate compound.

  Examples of the alkyl (meth) acrylate (A) having a long chain alkyl group having 12 or more carbon atoms, preferably 12 to 25 carbon atoms, include lauryl (meth) acrylate, cetyl (meth) acrylate, and stearyl (meth) acrylate. And behenyl (meth) acrylate, isolauryl (meth) acrylate, and isostearyl (meth) acrylate. These may contain multiple types.

  Preferred examples of the functional group capable of reacting with the amino group in the reactive (meth) acrylate (B) include a glycidyl group, a vinyl group, and a (meth) acryloyl group. Examples of the monomer (B) having a glycidyl group include glycidyl (meth) acrylate, and examples of the monomer (B) having a vinyl group include vinyl (meth) acrylate, 2- (2-vinyloxyethoxy) ethyl (meta). ) Acrylate is preferred. Examples of the monomer (B) having a (meth) acryloyl group include dipropylene glycol di (meth) acrylate and 1,6-hexanediol di (meth) acrylate. A plurality of these reactive (meth) acrylates (B) may be contained.

  A monomer mixture can contain the monomer (C) which can be copolymerized with these other than said monomer (A) and (B) within the range which does not inhibit the effect of this invention. Examples of the monomer (C) include styrene monomers such as styrene and α-methylstyrene; vinyl ether polymers such as vinyl acetate, vinyl benzoate, and butyl vinyl ether; maleates, fumarates, acrylonitrile, methacrylo Nitriles, α-olefins and the like can be mentioned. In addition, alkyl (meth) acrylates having an alkyl chain length of less than 12 carbons such as 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, tert-octyl (meth) acrylate, and the like can also be used. These can be used alone or in combination of two or more.

  In the monomer mixture, the alkyl (meth) acrylate (A) is preferably contained in an amount of 30% by mass or more, more preferably 40 to 95% by mass, and even more preferably 50 to 90% by mass. It is preferable that 1-30 mass% of reactive (meth) acrylate (B) is contained, and it is more preferable that it is 3-25 mass%. The monomer (C) other than the monomers (A) and (B) is preferably contained in an amount of 60% by mass or less, and more preferably 10 to 40% by mass.

  As the monomer (C), it is preferable to use a monomer (C1) having a β-diketone group or a β-keto acid ester group. By including this monomer (C1), the viscosity of the ink can be lowered. Therefore, when selecting a solvent for the ink, restrictions based on the viscosity value of the solvent itself are reduced, and the range of selection of the non-aqueous solvent can be expanded. In addition, when blending a fixing resin or an additive as necessary, the allowable range of ink viscosity increase due to the blended components is widened, and the degree of freedom of ink formulation can be expanded. Furthermore, by including this monomer (C1), it is possible to introduce a functional group having an ionic group into the trunk polymer. In general, when an ionic group is introduced into a non-aqueous solvent having a low polarity, an increase in the viscosity of the ink is caused. However, the increase in the viscosity can be suppressed by the presence of the monomer (C1). This contributes to electrostatic aggregation and fixing of the ink when the ink lands on the recording medium, and as a result, it is possible to improve the printing density and suppress the back-through.

  Furthermore, by printing the black ink containing the monomer (C1) on top of the cyan ink, it is possible to obtain a printed matter with a higher printing density while suppressing the image see-through. According to the knowledge of the present inventors, this effect becomes remarkable by including the monomer (C1) as compared with the case where the trunk polymer does not include the monomer (C1).

Examples of the β-diketone group of the monomer (C1) include acetoacetyl group and propionacetyl group as preferred examples. Examples of the β-keto acid ester group include acetoacetoxy group and propionacetoxy group as preferred examples. Although it is mentioned, it is not limited to these.
Preferred examples of the monomer (C1) include (meth) acrylates and (meth) acrylamides containing a β-diketone group or β-keto acid ester group in the ester chain. More specifically, examples include acetoacetoxyalkyl (meth) acrylates such as acetoacetoxyethyl (meth) acrylate, acetoacetoxyalkyl (meth) acrylamides such as hexadione (meth) acrylate, acetoacetoxyethyl (meth) acrylamide, and the like. These may be used alone or in combination of two or more.

  When the monomer (C1) is contained, the blending amount is preferably 3 to 30% by mass in the monomer mixture in consideration of the effect obtained by blending and the storage stability of the ink, and 5 to 20% by mass. It is more preferable that

Each of the above monomers can be easily polymerized by known radical copolymerization. The reaction system is preferably carried out by solution polymerization or dispersion polymerization. In this case, in order to make the molecular weight of the acrylic polymer after polymerization within the above-mentioned preferred range, it is effective to use a chain transfer agent in combination during the polymerization. Examples of the chain transfer agent include thiols such as n-butyl mercaptan, lauryl mercaptan, stearyl mercaptan, and cyclohexyl mercaptan.

  As polymerization initiators, azo compounds such as AIBN (azobisisobutyronitrile), t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate (perbutyl O, manufactured by NOF Corporation), etc. A known thermal polymerization initiator such as a product can be used. In addition, a photopolymerization initiator that generates radicals upon irradiation with active energy rays can be used. As a polymerization solvent used for solution polymerization, for example, a petroleum solvent (aroma free (AF) system) or the like can be used. As the polymerization solvent, it is preferable to select one or more kinds of solvents (described later) that can be used as they are as a non-aqueous solvent for the ink. In the polymerization reaction, other commonly used polymerization inhibitors, polymerization accelerators, dispersants and the like can also be added to the reaction system.

Next, in the obtained copolymer (trunk polymer), a urethane group is introduced by a reaction between a functional group capable of reacting with an amino group, an amino alcohol, and a polyvalent isocyanate compound. The amino group of the amino alcohol reacts with the functional group capable of reacting with the amino group in the monomer (B) to be bonded. Then, the isocyanate group (R ¹ N═C═O) of the polyvalent isocyanate compound undergoes an addition reaction with the hydroxy group of this amino alcohol as follows, and a urethane group (urethane bond) (carbamic acid ester: R ¹ NHCOOR) is obtained.
R ¹ N═C═O + R—OH → ROCONHR ¹
Here, R- represents an amino alcohol moiety bonded to the functional group of the trunk polymer.

Examples of amino alcohols include monomethylethanolamine, diethanolamine, and diisopropanolamine. Among these, since the number of urethane groups formed by providing two hydroxy groups can be increased, dialkanolamine (secondary) represented by the general formula (HOR) ₂ NH (R is a divalent hydrocarbon group) Alkanolamine) is preferable. These amino alcohols can also be used in combination of multiple types.

  This amino alcohol is preferably reacted at 0.05 to 1 molar equivalent from the viewpoint of introducing an appropriate amount of urethane group to the functional group capable of reacting with the amino group of the monomer (B). It is more preferable to make it react by 1-1 molar equivalent. When the amino alcohol is less than 1 molar equivalent, an unreacted functional group remains in the monomer (B), but the remaining functional group is considered to act as an adsorbing group for the pigment.

  Examples of the polyvalent isocyanate compound include aliphatic compounds such as 1,6-diisocyanate hexane, 1,3-bis (isocyanate methyl) benzene, 1,3-bis (isocyanate methyl) cyclohexane, 1,5-naphthalene diisocyanate, An alicyclic type and an aromatic type are mentioned, and multiple types can also be used. In order to prevent unreacted raw materials from remaining when the urethane group is introduced by the reaction with the hydroxy group, the polyvalent isocyanate compound is approximately equivalent to the hydroxy group contained in the charged raw material (0.98 to 0.98 to (1.02 molar equivalent) is preferable.

  In this way, an unnecessary urethane side chain portion (graft portion) is formed in the solvent, based on the amino alcohol bonded to the monomer (B), for the copolymer portion (trunk polymer) soluble in the solvent, This forms dispersed particle nuclei. By this process, finally, polymer particles (resin particles) wrapped in a shell structure (trunk polymer) that can be solvated in a solvent are formed.

In the above reaction, it is also preferable to add a polyhydric alcohol and react the polyhydric alcohol with the polyvalent isocyanate compound. By adding a polyhydric alcohol, formation of a urethane group is repeated, and a polyurethane side chain (branched polymer) that becomes a more polar side chain can be obtained.
Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, dipropylene glycol, 1,3 propanediol, polyethylene glycol, polypropylene glycol and the like, and a plurality of types can be used. The polyhydric alcohol is also important for controlling the particle size of the resin, and the particle size increases as the polyhydric alcohol content increases. On the other hand, if the particle size becomes extremely large, the ejection stability of the ink and the pigment dispersibility are impaired. Therefore, it is preferable to react the polyhydric alcohol with amino alcohol at 0 to 20 molar equivalents. It is more preferable to make it react by 10 molar equivalent.

  The mass ratio of the copolymer part (trunk polymer) and the introduced urethane base part (branch or branch polymer) in the acrylic polymer is preferably 60:40 to 99: 1, and 70:30 to 99: 1 is more preferable. The mass of the copolymer part in the acrylic polymer is the total mass of the monomers used in the copolymerization, and the mass of the introduced urethane base is the mass of the amino alcohol and polyvalent isocyanate compound used in the reaction, If polyhydric alcohol is used, this is also the total mass.

1-4. Other Components In addition to the solvent and the dye, other components such as a pigment, a surfactant, a fixing agent, and an antiseptic can be added to the dye ink of the present invention as long as the properties of the ink are not adversely affected.

1-5. Method for Producing Non-Aqueous Dye Ink The non-aqueous dye ink of the present invention is a known mixture such as a membrane filter, if desired, after heating a mixture obtained by mixing a predetermined amount of each of the components and reacting for about 2 to 8 hours. It can be prepared by passing through a filter. For example, the dye ink can be adsorbed to the resin component simultaneously with the creation of the resin component. Alternatively, after preparing a non-aqueous dye ink having a high dye concentration, the dye ink can be prepared by diluting to a desired concentration.

2. Pretreatment liquid The pretreatment liquid used in the present invention comprises at least inorganic particles, water, and a solvent, and may contain other components as necessary.

2-1. Inorganic particles As inorganic particles, inorganic particles used as extender pigments can be used. For example, silica, calcium carbonate, barium sulfate, titanium oxide, alumina white, aluminum hydroxide, white clay, talc, clay, diatomaceous earth, kaolin And inorganic particles such as mica. Of these, it is preferable to use silica. The average particle diameter of these inorganic particles needs to be 0.1 μm or more and 20 μm or less, preferably 0.1 μm or more and 15 μm or less, and more preferably 0.1 μm or more and 12 μm or less. In both cases where the average particle diameter is smaller than 0.1 μm and the average particle diameter is larger than 20 μm, the sealing action on the printing medium is not sufficient, and the effect of improving the printing density is not sufficiently obtained.

  The inorganic particles are preferably contained in the range of 0.01 to 40% by mass, more preferably in the range of 5 to 30% by mass with respect to the total amount of the pretreatment liquid.

  When using inorganic particles of 1 μm or more and 20 μm or less, it is preferable to use those having a liquid absorbency (A) value of 0.2 to 1.4 represented by the following formula (1). It is more preferable to use one having a range of 3 to 1.0. When the value of the liquid absorbency (A) of the inorganic particles is smaller than the above range, the blur of the printed dots becomes large, and the effect of sufficiently increasing the density and suppressing the back-through cannot be obtained. When the value of the liquid absorbency (A) of the inorganic particles is larger than the above range, the blurring of the printed dots becomes too small, and the dot size is sufficient to form a solid when printing with a resolution of about 300 × 300 dpi. In other words, show-through is suppressed, but a high-density printed matter cannot be obtained. On the other hand, if the liquid absorptivity (A) is too large, it cannot be dispersed well in the processing liquid, the viscosity of the processing liquid rises rapidly, and uniform coating becomes difficult.

In addition, when the amount of oriented particles (g / m ² ) when the pretreatment liquid is applied to the printing paper is too large, bleeding of the printed dots becomes too small, and a solid image is printed when printing at a resolution of about 300 × 300 dpi. The dot size is not sufficient for formation, and show-through is suppressed, but a high-density printed matter cannot be obtained. Therefore, the coating amount of the pretreatment liquid is preferably from ^{1g / m 2 ~10g / m 2} , 2.6g / m 2 ~6g / m 2 is more preferable.
It is preferably 0.1~2.5g / ^{m 2} and the amount of the inorganic particles, more preferably 0.3 to 1 g / ^{m 2.}

2-2. Solvent The solvent of the pretreatment liquid used in the present invention can be selected from the group consisting of water and organic solvents. The organic solvent may be a water-soluble organic solvent or a water-insoluble organic solvent as long as the solubility parameter is within a specified range.
Water-soluble organic solvents include glycol solvents, glycol ethers, glycol ether acetates, lower alcohols, glycerol, diglycerol, triglycerol, polyglycerol, imidazolidinone solvents, 3-methyl-2,4-pentane. Examples include diols. These may be used alone or in combination of two or more as long as a single phase is formed.

  Examples of the glycol solvent include alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol.

  Examples of glycol ethers include alkylene glycol alkyl ethers and polyalkylene glycol alkyl ethers (herein, both are collectively referred to as (poly) alkylene glycol alkyl ethers). For example, compounds represented by the following chemical formula (1) Is mentioned.

(In Formula (1), R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably 4 to 6 carbon atoms, and n is an integer of 1 to 4).

  Specific examples of the (poly) alkylene glycol alkyl ether represented by the chemical formula (1) include, for example, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol mono Propyl ether, triethylene glycol monobutyl ether, triethylene glycol monohexyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monopropyl ether, tetraethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl Ether, triethylene glycol diethyl ether, and triethylene glycol dibutyl ether.

  Specific examples of other (poly) alkylene glycol alkyl ethers include compounds represented by the following chemical formula (2).

(In Formula (2), R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably 4 to 6 carbon atoms, and n is an integer of 1 to 4).

  Specific examples of the (poly) alkylene glycol alkyl ether represented by the chemical formula (2) include, for example, propylene glycol monobutyl ether, propylene glycol dibutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono Examples include propyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether, dipropylene glycol dibutyl ether, and tripropylene glycol dibutyl ether.

  Examples of the lower alcohol include aliphatic alcohols having 1 to 6 carbon atoms in one molecule, and specific examples include ethyl alcohol, propyl alcohol, isopropyl alcohol, and butyl alcohol.

Of these water-soluble organic solvents, glycol solvents, glycol ethers, glycerin, diglycerin, triglycerin and polyglycerin are preferably used.
Specific examples of the water-insoluble organic solvent include dimethyl carbonate and diethyl carbonate.

  The solvent of the pretreatment liquid may be composed of one or more selected from the group consisting of water and the above-mentioned various organic solvents. However, in order to obtain a solvent having a specific SP value, only one solvent is used. It is more convenient and preferable. When water is used as the solvent for the pretreatment liquid, if the printing medium is a printing paper such as plain paper, the paper is deformed, the transportability of the printing medium is lowered, and it becomes an obstacle to high-speed printing. So be careful. In order to prevent this, it is preferable that the solvent of the pretreatment liquid is composed of the total amount of organic solvent.

2-3. Other components In the pretreatment liquid used in the present invention, other components such as a dispersant, a surfactant, a fixing agent, a preservative, etc., in addition to the solvent and the inorganic particles, as long as the properties are not adversely affected. Can be added. In particular, the fixing agent is useful for preventing bleeding of a printed image. As the fixing agent, various water-soluble polymers or water-dispersible polymer particles can be used. Polymer types include acrylic acid copolymer, acrylic / styrene copolymer, polyurethane, polyester, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, styrene-butadiene rubber (SBR), starch, alkyd resin, poly Acrylamide, polyvinyl acetal and the like are preferable.

  Among these, when water is used as the solvent of the pretreatment liquid, it is preferable to use polyvinyl alcohol having a polymerization degree of 500 or less and a saponification degree of 60 mol% or more as a fixing agent. When such polyvinyl alcohol is used, a high printing density can be obtained when printing at a relatively low resolution of 300 × 300 dpi or less. The polyvinyl alcohol is preferably contained in the range of 3.0 to 35.0% by mass and more preferably in the range of 6.0 to 30.0% by mass with respect to the amount of inorganic particles. When there is too much addition amount of polyvinyl alcohol, since dot size will become large and a brightness | luminance will become high, image quality will fall. Moreover, when there is too little addition amount of polyvinyl alcohol, the intensity | strength of coating layer itself will fall and it will become easy to peel from the printing medium surface.

2-4. Method for Producing Pretreatment Liquid The pretreatment liquid used in the present invention is, for example, a known disperser such as a bead mill or the like. Can be prepared. For example, after preparing a mixed liquid in which a part of the solvent and the whole amount of the pigment are uniformly mixed in advance and dispersing with a disperser, the remaining components are added to this dispersion and the mixture is passed through a filter. can do.

3. Inkjet Printing Method The inkjet printing method of the present invention is performed by discharging a non-aqueous dye ink onto the printing medium after applying a pretreatment liquid to the printing medium. The pretreatment liquid may be applied to the printing medium by uniformly coating the surface of the printing medium using a brush, roller, bar coater, or the like, or by printing means such as inkjet printing and gravure printing. This may be done by printing an image. For example, an inkjet printer may be used to perform printing by ejecting a pretreatment liquid onto a print medium and then continuously ejecting a fluorescent dye ink over the pretreatment liquid. In the present invention, it is preferable that after the pretreatment liquid is applied to the printing medium, the fluorescent dye ink is discharged after the applied treatment liquid has permeated and evaporated and dried. Therefore, when the amount of water in the pretreatment liquid is large, a drying step may be applied before printing the fluorescent dye ink. For the drying step, an existing method such as applying hot air to the print medium after applying the pretreatment liquid or transporting the print medium under a heated roll can be used.

  It is advantageous to constitute and sell an ink set including at least the pretreatment liquid and the non-aqueous dye ink so that the ink jet printing method of the present invention can be easily carried out.

  In the present invention, the printing medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, film, OHP sheet and the like can be used. In particular, according to the present invention, even when printing on plain paper, the dye does not penetrate into the printing paper and stays on the surface of the printing paper, so that the print density is improved, and the back-through and bleeding are reduced. The curling of the printing paper inside is prevented, and a great merit that high-speed printing is not hindered is obtained.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited only to this Example.
1. Adjustment of non-aqueous dye ink (1) Adjustment of acrylic resin Into a 300 ml four-necked flask, put 75 g of naphthenic solvent AF-7 (manufactured by Nippon Oil Co., Ltd.), ventilate nitrogen gas and stir while stirring. The temperature was raised to ° C. Next, while maintaining the temperature at 110 ° C., the monomer mixture shown in Table 1 was placed in the four-necked flask, and further 16.7 g AF-7 and 4 g perbutyl O (t-butylperoxy 2-ethylhexa Noate; Nippon Oil & Fats Co., Ltd.) was added dropwise over 3 hours. Thereafter, 0.2 g of perbutyl O was added after 1 hour and 2 hours while maintaining at 110 ° C. Further, aging was carried out at 110 ° C. for 1 hour and diluted with 12.7 g of AF-7 to obtain a copolymer solution of a yellow transparent acrylic resin having a solid content of 40%.

(2) Preparation of diethanolamine derivative 35.05 g of diethanolamine was placed in a 300 ml four-necked flask, heated to 50 to 60 ° C., and 61.4 g of 2-ethylhexyl acrylate was added dropwise with stirring, and then a temperature of 100 to 120 ° C. For 1 to 3 hours to obtain a diethanolamine derivative.

(3) Preparation of urethane-modified acrylic resin Using the acrylic resin copolymer and diethanolamine derivative obtained by the above (1) and (2), each component was reacted according to the formulation shown in Table 4 according to the following procedure, An acrylic resin having a urethane bond was prepared. First, in a 500 ml four-necked flask, 100 g of an acrylic resin copolymer solution (solid content: 40 g) and the addition amount of diethanolamine and diethanolamine derivative shown in Table 2 were added, while nitrogen gas was bubbled and stirred. The temperature was raised to 110 ° C. and left at that temperature for 1 hour. 0.2 g of dibutyltin dilaurate was added to the obtained reaction product, and the amount of Takenate 600 shown in Table 4 and 3.88 g of isooctyl palmitate were added dropwise over 1 hour. After the addition, the temperature was raised to 110 ° C., reacted for 6 hours, cooled, and the amount of AF-7 (naphthenic solvent; manufactured by Shin Nippon Oil Co., Ltd.) shown in Table 3 was added, and the solid content was 40%. A urethane-modified alkyl methacrylate copolymer resin dispersion was obtained.

The details of the raw materials in Table 2 are as follows.
Takenate 600: “Takenate 600 (trade name)” (1,3-bis (isocyanatomethyl) cyclohexane: aliphatic primary diisocyanate) manufactured by Mitsui Chemicals Polyurethanes, Inc.
-Isooctyl palmitate: manufactured by Nikko Chemicals Co., Ltd.

  The urethane bond part of the obtained resin was about 7% by mass of the copolymer. Moreover, the weight average molecular weight of polystyrene of this resin measured by GPC was 15000-25000.

(4) Preparation of Non-Aqueous Dye Ink In the non-aqueous dye ink of the present invention, the components shown in Table 1 were mixed in the formulation shown in the table, and the mixture was heated to 110 ° C. and reacted for 4 hours. Ink was prepared by filtering in order with a 3.0 μm and 0.8 μm membrane filter to remove dust and coarse particles.

In Table 3, the details of the following components are as follows.
-RED-C-BH: “RED-C-BH (trade name)” manufactured by Hodogaya Chemical Co., Ltd.
-Butisenol 30: “Butisenol 30 (trade name)” (triethylene glycol monobutyl ether) manufactured by Kyowa Hakko Chemical Co., Ltd.
AF-7: Shin Nippon Oil Co., Ltd., “AF-7 (trade name)” (naphthenic solvent).
・ Isooctyl palmitate: manufactured by Nikko Chemicals Co., Ltd.

2. Preparation of aqueous inorganic particle treatment liquid Components other than the inorganic particles shown in Table 4 were mixed while heating at 100 ° C. in the proportions shown in Table 4, and the inorganic particles shown in Table 4 were added in the amounts shown in Table 4, and ultrasonic waves were added. Treatment liquids A to G were prepared by dispersing for 1 minute using a disperser SONIC Vibra cell VC-750 & CV33 (trade name, manufactured by Probe SONIC & MATERIALS INC.).

The details of the raw materials listed in Table 4 are as follows.
Mizukasil P-758: “Mizukasil P-758 (trade name)” (powdered silica) manufactured by Mizusawa Chemical Co., Ltd.
Mizukasil P-73: “Mizukasil P-73 (trade name)” (powdered silica) manufactured by Mizusawa Chemical Co., Ltd.
Mizukasil P-526: “Mizukacil P-526 (trade name)” (powdered silica) manufactured by Mizusawa Chemical Co., Ltd.
・ Titanium oxide: “Titanium R-62N (trade name)” manufactured by Sakai Chemical Industry Co., Ltd.
・ White gloss flower PZ: “White gloss flower PZ” manufactured by Shiraishi Calcium Co., Ltd.
・ Callite SA: “Callite SA (trade name)” manufactured by Shiroishi Central Research Laboratory.
・ Callite KT: “Callite KT (trade name)” manufactured by Shiroishi Central Research Laboratory.
JMR-10M: “JMR-10M (trade name)” manufactured by Nippon Vinegar Poval Co., Ltd.
・ Movinyl 966A: “Movinyl 966A (trade name)” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
・ Slout 33: Nippon Enviro Chemical Co., Ltd. antiseptic “Slout 33 (trade name)”
・ Surfinol DF-58: “Surfinol DF-58 (trade name)” manufactured by Nissin Chemical Industry Co., Ltd.
-Demol EP: "Demol EP (trade name)" manufactured by Kao Corporation (special polycarboxylic acid type polymer surfactant, solid content 25%).

3. Examples 1 to 11 and Comparative Example 1
A plain paper “Ideal paper thin mouth (trade name)” manufactured by Riso Kagaku Co., Ltd. is used as the inkjet printing paper, and each pretreatment liquid listed in Table 4 is applied to the entire surface of one side of the printing paper with a solid content of 1. Each was applied with a coating roller so as to be 0 g / m ² , and the solvent was dried with a dryer. Thereafter, the fluorescent dye ink listed in Table 1 was introduced into the discharge path of an inkjet printer HC5500 (trade name; manufactured by Riso Kagaku Kogyo Co., Ltd.), and the fluorescent dye ink was discharged onto the pretreated surface of each printing paper, Solid images and single dots were printed (Examples 1 to 11). In addition, printing paper that had not been pretreated was prepared and printed on the surface in the same manner (Comparative Example 1). Printing was performed at a resolution of 300 × 300 dpi and an ink amount of 30 pl / dot. The color development and fluorescence intensity of the obtained printed matter were measured and evaluated by the following methods. The results are shown in Table 5.

4). Evaluation method and evaluation criteria
The color of the printed image on the surface of the printed material obtained was measured using a color development spectral color difference meter (SpectroColorMeter SE2000, manufactured by Nippon Denshoku Co., Ltd.), and the values of L, a, and b were determined for each color. From the measurement result of each example and the measurement result of Comparative Example 1, the color difference ΔE was calculated according to the following formula and evaluated according to the following evaluation criteria.
Evaluation criteria:
A: ΔE ≧ 15.0
○: 15.0> ΔE ≧ 10.0
Δ: 10.0> ΔE
×: (unprocessed)

Fluorescence intensity of the printed matter The fluorescence intensity of the printed image on the surface of the printed matter was visually observed, and the fluorescence intensity of Comparative Example 1 was evaluated as x, and the fluorescence intensity was evaluated in the following five stages based on this.
Fluorescence intensity ◎ (strong)>○>△>×> ×× (weak)

From the results of Table 5, in Examples 1 to 11 using the pretreatment liquid of the present invention, the color development and fluorescence intensity of the printed image are superior to Comparative Example 1 for the paper that has not been pretreated, and the pretreatment It can be seen that the larger the coating amount of the liquid, the better the color development and the fluorescence intensity. It is considered that the inorganic particles have a function of sealing, and the coloring material tends to remain on the paper surface, the color development is improved, and the back-through is reduced. In addition, it is considered that the color material is likely to remain on the paper surface, so that the distance between the color materials is reduced and excitation is facilitated, and the fluorescence intensity is increased.
Further, if the oil absorption using 130~180ml / 100g, a specific surface area of 330~530 m ² / g, the inorganic particles liquid suction amount is ^{0.25 × 10 -2 ~0.55 × 10 -2} ml / m 2, very While good color development and fluorescence intensity are obtained, the oil absorption is 19 to 47 ml / 100 g, the specific surface area is 6 to 37.5 m ² / g, and the liquid absorption is 3.03 × 10 ^{−2 to} 8.41 × 10 ⁻² ml / It was found that when m ² inorganic particles were used, the effects on color development and fluorescence intensity were reduced. This indicates that inorganic particles that have a large specific surface area and can absorb a large amount of solvent on the surface of the inorganic particles can provide better color development and fluorescence intensity.
Further, from the results of Examples 1 to 11, it was found that when the coating amount is increased, the color material is likely to aggregate, and the dot diameter is reduced, so that the solid is less likely to be buried.

  The ink-jet printing method and ink set of the present invention can be easily implemented with an ink-jet printer that can print on the treated surface of the print medium by discharging the fluorescent dye ink from the nozzle head after surface-treating the print medium with the pretreatment liquid. Can be widely used in the field of inkjet printing.

Claims (8)

  An ink set for ink-jet printing comprising a pretreatment liquid containing at least inorganic particles, water and a solvent, and a non-aqueous dye ink containing a dye and a solvent. ^2. The ink set according to claim 1, wherein the inorganic particles exhibit an oil absorption of 10 to 200 ml / 100 g and a specific surface area of 1 to 600 m ² / g.   The ink set according to claim 1 or 2, wherein the inorganic particles have an average particle size in a range of 0.5 to 15 µm.   The ink set according to any one of claims 1 to 3, wherein the non-aqueous dye ink includes at least a fluorescent dye, a solvent, and a urethane-modified acrylic resin.   The ink set according to claim 4, wherein the urethane-modified acrylic resin contains at least a monomer having a long-chain alkyl group having 12 to 25 carbon atoms and a monomer having an epoxy group.   An ink jet printing method comprising: applying a pretreatment liquid containing at least inorganic particles, water, and a solvent to a printing medium, and then printing a non-aqueous dye ink on the coated surface. The coating amount to the printing medium of the pretreatment liquid printing method according to claim 6 is ^{1g / m 2 ~10g / m 2} . The coating amount to the printing medium of the pretreatment liquid printing method according to claim 6 is ^{2.6g / m 2 ~6g / m 2} .