JP2018114748A - Pretreatment liquid, ink set, and printed matter production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a pretreatment liquid which can provide a high-quality image with a sufficient density without causing cracks or defects of the image such as irregular color or bleeding in high-speed, high-resolution inkjet printing and regardless of a substrate used, does not cause the setoff upon stacking such substrates after printing or the adhesion into a coating device, and has excellent storage stability; and an ink set comprising an inkjet ink and the pretreatment liquid.SOLUTION: A pretreatment liquid for use with aqueous inkjet ink containing at least a pigment contains melt inorganic and/or organic metal salts, and an organic solvent.SELECTED DRAWING: None

Description

  The present invention can obtain a high-quality image having a sufficient density without causing image defects such as blurring and color unevenness regardless of the base material, adhesion in the coating apparatus, and printing. The present invention relates to a pretreatment liquid that does not cause set-off when a subsequent base material is stacked and has excellent storage stability, and an ink set comprising the pretreatment liquid and inkjet ink. The present invention also relates to a method for producing a printed matter using the ink set.

  Inkjet printing is a recording method in which droplets of inkjet ink ejected from an inkjet head are directly applied to a substrate to form characters and images. Compared to conventional plate-type printing such as offset printing and gravure printing, it is not necessary to make a plate and can support variable printing. It is easy to operate and adjust the printing device and has low noise during printing. In recent years, there has been an increase in demand for industrial use, including home use and household use.

  Ink jet inks used for ink jet printing are classified into solvent type, aqueous type, UV curable type and the like according to the composition. On the other hand, in recent years, the movement to regulate the use of organic solvents and photosensitive monomers, which are harmful to humans and the environment, has been accelerating, and from solvent-based inks and UV curable inks using these materials to water-based inks. There is a growing demand for replacements.

  The water-based (type) ink-jet ink contains water as a main component, and a water-soluble organic solvent such as glycerin or glycol is added to control wettability and dryness of the substrate. Moreover, when a character or image pattern is printed (applied) on a substrate using an aqueous inkjet ink composed of these liquid components, the liquid component penetrates into the substrate and / or evaporates from the substrate. And is fixed on the substrate.

  On the other hand, there are various types of substrates used in inkjet printing, from those with high permeability such as fine paper and recycled paper to those with low (no) permeability such as coated paper, art paper, and plastic film. To do. In general, water-based (ink) ink-jet inks can be printed to a certain degree of practical quality on highly penetrating paper such as high-quality paper and recycled paper, whereas coated paper, art paper, and plastic It is difficult to obtain a practical level of image quality for a film with low (no) permeability, such as a film, because blurring occurs between colors and image quality deteriorates. In order to further expand the demand for ink-jet printing, the development of water-based ink-jet inks that can be applied to various substrates has become a major challenge for those skilled in the art.

  As a measure against the above problem, a pretreatment liquid treatment for a substrate is known. In general, as a pretreatment liquid for water-based ink-jet inks, a layer (ink receiving layer) that absorbs liquid components in the ink-jet ink and improves drying properties (see Patent Documents 1 to 4), a coloring material, Forming a layer (ink aggregation layer) that prevents blurring and color unevenness between droplets and improves image quality by intentionally aggregating solid components contained in inkjet ink such as resin (see Patent Documents 5 to 6) ) Are known.

  However, in the case of an ink receiving layer, for example, when a large amount of ink is received at one time, the substrate is wavy, curled, the image is cracked due to swelling of the ink receiving layer, blurring of the image, bleeding or color due to excess of the acceptable amount Unevenly, there may be a decrease in density due to absorption of the ink component into the receiving layer. Conversely, in the case of an ink agglomerated layer, absorption of liquid components does not occur basically, so these phenomena are difficult to occur. On the other hand, if the ink agglomerated layer does not have a uniform film thickness, the image quality deteriorates. In addition, problems associated with partial deterioration of dryness may occur. That is, in the region where the thickness of the ink aggregation layer is small, the ink aggregation effect is small, and bleeding and color unevenness occur. Conversely, in areas where the film thickness is large, bleeding and color unevenness can be suppressed, but the pretreatment liquid and the drying property of the ink applied thereon are reduced, so that the pretreatment liquid and ink are contained in the coating apparatus. If it adheres or the substrates are stacked after printing, settling occurs. In particular, in the case of printing at high speed and high recording resolution, these problems are likely to occur, and there is a possibility that the quality may be greatly deteriorated. Therefore, when the pretreatment liquid for forming the ink aggregation layer is employed, the uniform application becomes an important issue.

  Conventionally, in order to ensure uniform application of the pretreatment liquid, the substrate wettability has been improved by the addition of an organic solvent, but this has not been sufficient. For example, Patent Document 5 discloses a pretreatment liquid containing a polyvalent metal ion and an organic solvent. However, since the organic solvent used in the literature has a high surface tension such as glycerin, the pretreatment liquid cannot be applied uniformly, especially when printing at high speed and high recording resolution, and the above image quality There is a risk of lowering or poor drying.

  As described above, with the conventional technology, high-quality image quality can be obtained regardless of the base material used, and even after high-speed, high-recording-resolution inkjet printing, In this situation, there was no pretreatment liquid that would not cause set-off when the substrates were stacked.

  Until now, little attention has been paid to the storage stability of a pretreatment liquid for forming an ink aggregation layer containing a metal salt. For example, Patent Document 6 discloses a pretreatment liquid containing polyvalent metal ions and an organic solvent, and mentions storage stability as one of the effects. However, there is no description regarding a method or basis for specifically improving storage stability in the above-mentioned document.

JP 2000-238422 A JP 2000-335084 A JP 2012-131108 A JP 2009-241304 A JP 11-010856 A JP 2004-276253 A

  The present invention has been made to solve the above-mentioned problems, and its object is to eliminate image defects such as bleeding and color unevenness and cracking in high-speed, high-resolution inkjet printing regardless of the substrate used. High-quality images with sufficient density can be obtained without waking up, and there is no adhesion to the inside of the coating device or set-up when the base material after printing is stacked, and storage stability The present invention provides a pretreatment liquid excellent in properties, and an ink set comprising the pretreatment liquid and inkjet ink. The present invention further provides a production method effective in solving the above-mentioned problems in producing a printed matter using the ink set.

  As a result of intensive studies to solve the above problems, the present inventors can solve the above problems by using a pretreatment liquid containing a specific amount of a specific material and an ink set comprising the pretreatment liquid and inkjet ink. The present invention was completed.

That is, the present invention is a pretreatment liquid used with an aqueous inkjet ink containing at least a pigment,
The pretreatment liquid includes a dissolved inorganic metal salt and / or organic metal salt, and an organic solvent,
The metal ion derived from the inorganic metal salt and / or the organic metal salt contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid. ,
The organic solvent contains a compound having one or more hydroxyl groups in the molecular structure, and the content of the organic solvent having a boiling point of 180 ° C. or higher is 15% by weight or less based on the total amount of the pretreatment liquid. This relates to a pretreatment liquid.

Further, the present invention is characterized in that the polyvalent metal ion includes at least one selected from Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Fe ²⁺ , and Fe ^3+. The present invention relates to the pretreatment liquid.

  The present invention also relates to the pretreatment liquid, wherein the pretreatment liquid further contains a water-soluble binder resin.

  The present invention also relates to the pretreatment liquid, wherein the binder resin contains a nonionic water-soluble resin.

  The present invention is also characterized in that the weight ratio of the content of the binder resin to the content of metal ions derived from the inorganic metal salt and / or the organic metal salt is more than 0 and less than 20. Regarding liquids.

  The present invention also relates to the pretreatment liquid, wherein the pretreatment liquid has a viscosity of more than 9 mPa · s and not more than 30 mPa · s.

  The present invention also relates to the pretreatment liquid, wherein the pretreatment liquid contains a surfactant and the surface tension of the pretreatment liquid is 20 to 45 mN / m.

The present invention also relates to a coating film formed by applying the pretreatment liquid, wherein the coating amount of the pretreatment liquid is 1 to 25 g / m ² .

  The present invention also relates to an ink set comprising the pretreatment liquid and a water-based inkjet ink containing a pigment, a water-soluble organic solvent, and water.

  In the present invention, the water-soluble organic solvent contained in the water-based inkjet ink contains two or more glycol ether solvents and / or alkyl polyol solvents having a boiling point of 180 ° C. or higher and 280 ° C. or lower at 1 atmosphere. To the above ink set.

  Further, the invention is characterized in that the water-based inkjet ink contains a water-soluble organic solvent having a boiling point of 240 ° C. or higher under 1 atm to 0% by weight or more and less than 10% by weight with respect to the total amount of the water-based inkjet ink. The present invention relates to the ink set.

  In the invention, it is preferable that the water-based inkjet ink contains a water-soluble organic solvent having a boiling point of 240 ° C. or higher at 1 atm to 0% by weight or more and less than 7% by weight based on the total amount of the water-based inkjet ink. The present invention relates to the ink set.

  Further, the present invention is characterized in that the water-based inkjet ink contains a water-soluble organic solvent having a boiling point of 210 ° C. or higher under 1 atm to 0% by weight or more and less than 20% by weight with respect to the total amount of the water-based inkjet ink. The present invention relates to the ink set.

  The present invention also relates to the above ink set, wherein the water-based inkjet ink contains a pigment in an amount of 2% by weight to less than 15% by weight based on the total amount of the water-based inkjet ink.

  The present invention also relates to the above ink set, wherein the water-based inkjet ink further contains a water-soluble resin as a binder resin.

  According to the invention, the water-based inkjet ink has at least a magenta ink, and the magenta ink is a C.I. I. Pigment Bio Red 19 is included, and the present invention relates to the ink set.

  The present invention also relates to a pretreatment liquid as described above or a method for producing a water-based inkjet ink print using the ink set as described above, wherein the pretreatment liquid is applied to a substrate conveyed at a speed of 30 m / min or more. And a step of applying the aqueous inkjet ink to the portion applied with the pretreatment liquid by a one-pass printing method.

  The present invention also relates to a method for producing the water-based inkjet ink printed material, wherein the substrate is a paper or film substrate.

According to the present invention, regardless of the substrate used, it is possible to obtain a high-quality image having a sufficient density without causing image defects such as bleeding and uneven color, and adhesion within the coating apparatus. In addition, it has become possible to provide a pretreatment liquid that does not cause set-off when the printed substrates are stacked and has excellent storage stability, and an ink set comprising the pretreatment liquid and inkjet ink. . Furthermore, when manufacturing a printed matter using the said ink set, the manufacturing method effective in the solution of the said subject came to be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, embodiment described below demonstrates an example of this invention. The present invention is not limited to the following embodiments, and includes modifications that are implemented without departing from the scope of the present invention.

  The pretreatment liquid of the present invention contains a dissolved inorganic metal salt and / or organic metal salt, a metal ion derived from the inorganic metal salt and / or organic metal salt contains a polyvalent metal ion, and The content of the valent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid, and contains an organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure, and has a boiling point Is characterized in that the content of the organic solvent at 180 ° C. or more is 15% by weight or less. As described in the prior art, the combined use of an inorganic metal salt and / or an organic metal salt and an organic solvent has been conventionally performed, but the present invention includes a specific amount of polyvalent metal ions, and This is characterized in that the structure of the organic solvent to be used in combination and the upper limit amount of the high boiling point organic solvent are defined. The effect will be described below.

  The pretreatment liquid of the present invention is applied on a substrate before printing inkjet ink, and forms an ink aggregation layer on the substrate. The inorganic metal salt and / or organic metal salt contained in the pretreatment liquid is ionized in the presence of water or a compound containing one or more hydroxyl groups in the molecular structure, and the pretreatment liquid on which the aqueous inkjet ink is printed There will be a high concentration of metal cation component in the layer. This metal cation component causes anion-cation interaction and adsorption equilibrium transfer to a solid component having an anion charge such as a pigment or a resin that is dissolved and / or dispersed in the ink-jet ink. , The dissolution and / or dispersion function is lowered, and the color mixture between the pigments is suppressed. In addition, the ink-jet ink can be printed before the pretreatment liquid of the present invention is dried. In this case, the mixing equilibrium and the adsorption equilibrium of the solid component are changed by mixing the ink-jet ink and the pretreatment liquid. The dissolution and / or dispersion function of the solid component can be reduced.

The metal ion derived from the inorganic metal salt and / or the organic metal salt used in the present invention contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2 wt% or more based on the total amount of the pretreatment liquid. % By weight or less. Among metal ions, polyvalent metal ions have higher anion-cation interaction and adsorption equilibrium transfer reaction rate and higher ability than monovalent metal ions.
However, of course, when the content of the polyvalent metal ion is too small, the ability to cause the anion-cation interaction and the adsorption equilibrium transfer is poor, and blurring and color unevenness occur. Bleeding and color unevenness can be suppressed by increasing the content of polyvalent metal ions. On the other hand, when the content of polyvalent metal ions is excessive, the present inventors have a printed matter depending on the substrate used. It was found that the image quality and dryness of the product deteriorated. Although the detailed reason is not clear, an excessive amount of polyvalent metal ions causes coating unevenness due to deterioration of the wettability of the pretreatment liquid with respect to the substrate, and the degree of aggregation in the printed surface varies. In addition, it is considered that the boiling point increase phenomenon due to the inorganic metal salt and / or the organic metal salt occurred.

  Therefore, in the present invention, the above problem is solved by setting the content of polyvalent metal ions to 2 wt% or more and 8 wt% or less. That is, by keeping the content of polyvalent metal ions in the above range, while suppressing bleeding and uneven color, the wettability of the pretreatment liquid with respect to the substrate is ensured, and the inorganic metal salt and / or the organic metal salt The boiling point rise caused by is minimized.

  On the other hand, in order for the pretreatment liquid of the present invention to function properly regardless of the type of base material, while ensuring the wettability of the pretreatment liquid for various base materials, the liquid absorption characteristics of the base material Regardless, it is necessary to develop excellent drying properties. Therefore, in the pretreatment liquid of the present invention, by using an organic solvent as an essential component, the surface tension of the pretreatment liquid is reduced, and uniform coating on a substrate having a small surface energy is possible. Moreover, the residue of the high boiling point organic solvent in printed matter is prevented by making content of the organic solvent whose boiling point is 180 degreeC or more into 15 weight% or less. As a result, adhesion to the inside of the coating apparatus and set-off when the base materials are stacked are suppressed, and high-speed printing that does not depend on the base materials is possible.

  However, inorganic metal salts and / or organic metal salts containing polyvalent metal ions are inferior in solubility compared to salts containing monovalent metal ions. In general, organic solvents are less polar than water, and salts are difficult to dissolve. Therefore, storage is possible simply by combining an inorganic metal salt and / or organic metal salt containing a polyvalent metal ion with an organic solvent. It becomes a pretreatment liquid inferior in stability.

  Therefore, in the present invention, the problem is solved by using a compound containing one or more hydroxyl groups in the molecular structure as the organic solvent. Although the detailed factor is unknown, in addition to water molecules, compound molecules containing one or more hydroxyl groups in the molecular structure also cause solvation with respect to polyvalent metal ions. It is considered that the polyvalent metal ions are compatible with other organic solvents through compound molecules containing at least one compound, thereby stabilizing the entire system and thus improving the storage stability of the pretreatment liquid.

  As described above, even in high-speed, high-recording-resolution ink-jet printing, a high-quality image can be obtained regardless of the substrate, and adhesion to the coating apparatus and the substrate after printing are stacked. The combination of the constituent elements of the present invention is indispensable for obtaining a pretreatment liquid that does not cause any setback and has excellent storage stability.

  On the other hand, since the ink aggregating layer is inferior in the ability to accept moisture, when a large amount of inkjet ink is applied at once or in a short time, the ink of different colors bleeds, color unevenness, drying loss, There is a possibility of causing the settling in the coating apparatus and the settling of the base material. In order to obtain a high-quality image even in high-speed printing, it is necessary that the ink landing accuracy and ejection stability are excellent, and that the solid printing portion is well filled. Therefore, in the present invention, it is particularly preferable to solve the above problems by making the configuration of the inkjet ink suitable for the pretreatment liquid. Specifically, by adjusting the type and amount of the water-soluble organic solvent contained in the ink-jet ink and controlling the drying property, prompt drying on the ink agglomerated layer is promoted, and adhesion to the coating apparatus and the substrate are prevented. Suppresses the set-off when the materials are stacked, and suppresses the occurrence of bleeding and uneven color.

  Subsequently, components of the pretreatment liquid of the present invention will be described in detail below.

<Inorganic metal salt and / or organic metal salt>
The pretreatment liquid of the present invention contains an inorganic metal salt and / or an organic metal salt in a dissolved state. In the present invention, the metal salt lowers the dissolution and / or dispersion function of the solid component in the ink-jet ink on the substrate and causes aggregation of the solid component, thereby causing bleeding and color unevenness due to mixing of ink droplets. It is to improve. Examples of materials that exhibit this effect include cationic resins and organic acids. Compared with these materials, metal salts have a low molecular weight and can easily move the cation component, and dissolve instantly in water. Because it generates a cation component that causes aggregation of solid components, when inkjet ink is ejected onto a substrate coated with a pretreatment liquid, it instantly reaches the top of the inkjet ink layer even at high printing rates. The cationic component migrates to the pigment and can cause pigment aggregation. As a result, bleeding and color unevenness do not occur even in high-speed printing, and a high-quality printed matter can be obtained.

  In the present invention, the “dissolved state” represents a state in which an inorganic metal salt and / or an organic metal salt and water are uniformly mixed to form a transparent solution. Whether or not it is in a dissolved state can be determined, for example, by confirming whether or not the liquid is transparent when the pretreatment liquid left at 25 ° C. for 24 hours is observed with the naked eye. In addition, when the pretreatment liquid used for the above determination contains an inorganic metal salt and / or an organic metal salt and materials other than water, a liquid in which those materials are replaced with water is prepared and evaluated.

A metal salt may be used individually by 1 type, or may be used in combination of 2 or more type. Moreover, the said metal salt will not be specifically limited if it is a metal salt comprised from the anion couple | bonded with a metal ion and the said metal ion. Among them, it is preferable to contain a polyvalent metal salt from the viewpoint that it can interact instantaneously with the pigment, suppress bleeding, and obtain a clear image with no color unevenness. The polyvalent metal ion contains at least one selected from Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Fe ²⁺ , Fe ³⁺ , and solid components such as pigments and resins It is preferable from the viewpoint of easily causing the interaction. Furthermore, among them, polyvalent metal ions selected from Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , and Al ³⁺ have an advantage that they have a large agglomeration effect because they have a large tendency to ionize and easily generate cation components. More preferably used. In particular, a polyvalent metal ion selected from Ca ²⁺ and Mg ²⁺ is very preferably selected because it has a small ionic radius and easily moves within the ink-jet ink layer.

  Specific examples of the inorganic metal salt include calcium chloride, magnesium chloride, aluminum chloride, calcium bromide, magnesium bromide, calcium nitrate, magnesium nitrate, magnesium sulfate, aluminum sulfate, calcium carbonate, and magnesium carbonate. It is not limited to these. Among these inorganic metal salts, a chloride having high solubility in water is generally more preferable. Further, among these inorganic metal salts, calcium chloride and calcium nitrate are particularly preferable from the viewpoint that the solubility in water and the interaction with the components in the ink-jet ink occur efficiently and quickly. Specific examples of organic metal salts include, but are not limited to, calcium salts, magnesium salts, nickel salts, zinc salts, and the like of organic acids such as pantothenic acid, propionic acid, ascorbic acid, acetic acid, and lactic acid. It is not a thing. Among these organic acid metal salts, lactic acid and / or calcium salt of acetic acid is more preferable from the viewpoints of solubility in water and interaction with components in the inkjet ink.

  The content of the metal salt in the pretreatment liquid of the present invention is preferably 2 to 8% by weight, particularly 2.5 to 5% by weight as polyvalent metal ions with respect to the total amount of the pretreatment liquid. preferable. By keeping the content of the metal ions within the above range, as described above, while suppressing bleeding and uneven color, the wettability of the pretreatment liquid with respect to the substrate is ensured, and the inorganic metal salt and / or organic metal The rise in boiling point due to salt can be minimized. When the content of the polyvalent metal ion is less than 2% by weight, the ability to instantaneously cause the ink aggregation cannot be exhibited sufficiently, and bleeding and color unevenness occur. On the other hand, when the content exceeds 8% by weight, the wettability of the pretreatment liquid with respect to the base material is deteriorated, so that coating unevenness occurs, or the boiling point rise phenomenon due to inorganic metal salt and / or organic metal salt occurs. This is not preferable because it occurs and the drying property deteriorates. In addition, content of the polyvalent metal ion with respect to pretreatment liquid whole quantity is calculated | required by following formula (1).

Formula (1):

(Polyvalent metal ion content) (wt%) = WC x MM / MC

  In the general formula (1), WC represents the content of the inorganic metal salt and / or organic metal salt relative to the total amount of the pretreatment liquid, and MM represents a polyvalent metal ion constituting the inorganic metal salt and / or organic metal salt. MC represents the molecular weight of the inorganic metal salt and / or organometallic salt.

<Organic solvent>
The pretreatment liquid of the present invention is characterized by containing an organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure in addition to the inorganic metal salt and / or the organic metal salt. By using an organic solvent in combination, the drying property of the pretreatment liquid can be controlled, and at the same time, the wettability to the substrate during high-speed printing can be adjusted to a more suitable one, and uniform coating can be performed. . Further, as described above, the storage stability of the pretreatment liquid is improved by using a compound containing one or more hydroxyl groups in the molecular structure.

Examples of the compound having at least one hydroxyl group in the molecular structure, which is essential as an organic solvent that can be used in the pretreatment liquid of the present invention, include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2- Monohydric alcohols such as butanol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol,
1,2-ethanediol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2- Pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1, 3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl- 1,3-propanediol, 2-methylpentane-2,4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, ethyl Glycol, diethylene glycol, triethylene glycol, dipropylene glycol, butylene glycol, dihydric alcohols (glycols) such as dibutylene glycol,
Trihydric alcohols such as glycerin,
Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether Ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, Pyrene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, etc. And glycol monoalkyl ethers.
In the present invention, it is preferable to select an alcohol among the above exemplified compounds because of its excellent affinity with polyvalent metal ions, water molecules, and other organic solvents, particularly ethanol, 1-propanol, 2-propanol, It is preferable to use monohydric alcohols such as 3-methoxy-1-butanol and 3-methoxy-3-methyl-1-butanol.
Moreover, the compound which contains one or more hydroxyl groups in said molecular structure may be used independently, and may use 2 or more types together.

  The content of the compound containing one or more hydroxyl groups in the molecular structure contained in the pretreatment liquid of the present invention is preferably 0.1 to 20% by weight or less based on the total amount of the pretreatment liquid, 0.5 It is more preferably 10 to 10% by weight, and particularly preferably 1 to 5% by weight. By keeping the content of the compound within the above range, it is possible to obtain a pretreatment liquid having both drying property, wettability and storage stability, and stable printing over a long period regardless of the printing method of the pretreatment liquid. Is possible.

In the pretreatment liquid of the present invention, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether, triethylene glycol Glycol dialkyl ethers such as diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol butyl methyl ether, tetraethylene glycol diethyl ether,
2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, ε-caprolactam, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, N, N-dimethyl-β-methoxypropionamide, N, N- Dimethyl-β-ethoxypropionamide, N, N-dimethyl-β-butoxypropionamide, N, N-dimethyl-β-pentoxypropionamide, N, N-dimethyl-β-hexoxypropionamide, N, N- Dimethyl-β-heptoxypropionamide, N, N-dimethyl-β-2-ethylhexoxypropionamide, N, N-dimethyl-β-octoxypropionamide, N, N-diethyl-β-butoxypropionamide, N, N-diethyl-β-pentoxypropionamide, N, N-diethyl-β-he Sokishi propionamide, N, N- diethyl -β- heptene Toki Cipro propionamide, N, nitrogen-containing solvents such as N- diethyl -β- octoxynol propionamide,
Heterocyclic compounds such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone can be used.
Said organic solvent may be used independently and may use 2 or more types together.

  The total amount of the water-soluble organic solvent contained in the pretreatment liquid of the present invention is preferably 0.1 to 50% by weight or less and 0.15 to 30% by weight based on the total amount of the pretreatment liquid. It is more preferable that the content is 0.2 to 20% by weight. By keeping the content of the water-soluble organic solvent within the above range, it is possible to achieve both dryness of the pretreatment liquid, uniform application due to wettability to the substrate, and storage stability.

  The pretreatment liquid of the present invention is characterized in that the content of an organic solvent having a boiling point of 180 ° C. or higher is 15% by weight or less based on the total weight of the pretreatment liquid. “The content is 15% by weight or less” means that the organic solvent having a boiling point of 180 ° C. or higher is not included or, when it is included, the content is 15% by weight or less. By keeping the content of the organic solvent at 180 ° C. or higher within the above range, the drying property of the pretreatment liquid is improved, and the drying property of the ink applied later is not adversely affected. By eliminating the residue of the organic solvent in the printed matter, it is possible to suppress adhesion to the inside of the coating apparatus and set-off when the substrates are stacked, thereby realizing high-speed printing. Although detailed factors are unknown, when inkjet printing is performed on an ink aggregation layer prepared using a pretreatment liquid that satisfies the above conditions, polyvalent metal ions are instantly dissolved in the ink applied later. Therefore, it is possible to exhibit a sufficient bleeding / color unevenness suppressing effect. Of the organic solvents exemplified above, 1,2-ethanediol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol have boiling points of 180 ° C. or higher. 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 1 2-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, butylene glycol, dibutylene glycol and other dihydric alcohols, glycerin and other trihydric alcohols, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, Diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, Ziplo Glycol monoalkyl ethers such as lenglycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether, Glycol dialkyl ethers such as triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol butyl methyl ether, tetraethylene glycol diethyl ether, and the nitrogen-containing solvents and heterocyclic compounds exemplified above Either of these can be mentioned.

  Further, the water-soluble organic solvent contained in the pretreatment liquid may contain an organic solvent having a low surface tension in order to make the pretreatment liquid of the present invention correspond to ensuring high-speed printability on various substrates and improving image quality. preferable. As described above, in the present invention, in order to obtain a high-quality printed material in high-speed printing, it is important that the substrate can be applied uniformly regardless of the liquid absorbency and unevenness of the substrate, and by using an organic solvent having a small surface tension. It is considered that the wettability of the pretreatment liquid containing a polyvalent metal salt can be dramatically improved. In addition, since the wettability of the pretreatment liquid on the substrate and the image quality improvement of the inkjet ink applied later can be achieved, an organic solvent having a small surface tension and a surfactant described below are used in combination. It is particularly preferable to control the surface tension of the treatment liquid.

  The organic solvent having a small surface tension in the present embodiment preferably has a surface tension at 25 ° C. of 20 to 32 mN / m, more preferably 20 to 30 mN / m, and more preferably 20 to 28 mN / m. Particularly preferred. By using the organic solvent having the surface tension, the surface tension of the pretreatment liquid can be kept within a suitable range.

  The content of the organic solvent having a small surface tension is preferably 35 to 100% by weight, more preferably 40 to 100% by weight, based on the total amount of the water-soluble organic solvent in the pretreatment liquid. It is particularly preferable that it is contained in an amount of 50 to 100% by weight. By keeping the content of the organic solvent having a small surface tension within the above range, the effect of lowering the surface tension by the organic solvent having a small surface tension can be suitably expressed.

Among the water-soluble organic solvents exemplified above, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3 are used as organic solvents having a surface tension at 25 ° C. of 20 to 32 mN / m. Monohydric alcohols such as -methoxy-1-butanol and 3-methoxy-3-methyl-1-butanol;
1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methylpentane-2, Dihydric alcohols (glycols) such as 4-diol, 2-ethyl-1,3-hexanediol, 1,2-octanediol,
Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether Ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Glycol monoalkyl ethers such as polyglycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether ,
Diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol And glycol dialkyl ethers such as methyl ethyl ether, tetraethylene glycol butyl methyl ether, and tetraethylene glycol diethyl ether.
Among these compounds, for the reasons described above, it is more preferable to select a compound having at least one hydroxyl group in the molecular structure, more preferably at least an alcohol, and at least a monohydric alcohol. Most preferred.
In addition, said organic solvent may be used independently and may use 2 or more types together.

<Binder resin>
The pretreatment liquid of the present invention can further contain a binder resin. The binder resin is a polymer that does not participate in the reaction between the inkjet ink and the reaction liquid. By using the binder resin in combination, the water resistance of the printed material can be improved, and the printed material can be used for various applications. In general, water-soluble resins and resin fine particles are known as binder resins, and either one can be used in the present invention, but when mixed with a metal salt, it does not cause thickening or sedimentation in the long term. A water-soluble resin was selected because it is stable, instantly mixed with inkjet ink, expresses the coagulation ability of the pretreatment liquid more effectively in high-speed printing, and has excellent drying properties until film formation. Is preferred.

  The content of the binder resin is defined with respect to the amount of metal ions, and the weight ratio of the content of the binder resin to the content of metal ions contained in the pretreatment liquid is greater than 0 and less than 20. Is more preferable, more preferably 0 and less than 10, and particularly preferably 0 and less than 4. In the case of the above range, the water resistance is improved, the coating film is not cracked, and the dissolution of the polyvalent metal salt is not inhibited as compared with the case where the binder resin is not contained, so that a high-quality and high-quality printed matter can be obtained.

  In the present invention, any binder resin can be used. However, as described above, it is preferable to select a water-soluble resin. Among these, when a nonionic water-soluble resin is used, water resistance is improved and cracking is suppressed. It is preferable because it is effective and does not generate thickening or sedimentation and has good stability as a pretreatment liquid. Moreover, as long as the basic performance of the reaction solution can be maintained, a resin obtained by adding an anion unit or a cation unit to these nonionic polymers may be used, but a resin that does not substantially contain the unit is used. Is more preferable. The “resin substantially free of anion unit or cation unit” means a resin having an acid value of 0 to 10 mgKOH / g and an amine value of 0 to 10 mgKOH / g. The acid value and amine value can be measured by, for example, a potentiometric automatic titrator described later.

Specific examples of the binder resin that can be used in the present invention include polyethyleneimine, polyamide, various quaternary ammonium base-containing water-soluble resins, polyacrylamide, polyvinylpyrrolidone, polyalkylene oxide, starch, methylcellulose, hydroxycellulose, carboxymethylcellulose. Needless to say, water-soluble cellulose such as hydroxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinyl methyl ether, polyvinyl acetal, polyvinyl alcohol, and modified products thereof are not limited thereto.
Among these, it absorbs liquid components in inkjet inks to be printed later, and can improve the drying property especially in high-speed printing, so that polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetal, polyalkylene oxide, water-soluble It is preferable to select at least one of cellulose and a modified product thereof.
In particular, polyvinyl alcohol has the physical properties necessary for pretreatment agents for inkjet inks, such as transparency, film strength, and binder strength against pigments. It is particularly preferable from the point of being.
Furthermore, it is most preferable to use polyvinyl alcohol having a saponification degree of 95% or more because pH change with time is suppressed.
That is, by using polyvinyl alcohol having a saponification degree of 95% or more as the binder resin, an ink jet agglomerated layer excellent in gloss and transparency can be obtained in addition to improving water resistance and suppressing cracking of the coating film, and over time. A pretreatment liquid having excellent pH stability can be obtained.
In particular, a modified product of polyvinyl alcohol, particularly polyvinyl alcohol modified with a hydrophobic group, is selected very preferably because it leads to improved storage stability of the liquid and further improved water resistance.

  When the pretreatment liquid of the present invention contains a binder resin, the number average molecular weight (Mn) is preferably 3,000 to 90,000, and particularly preferably 4,000 to 86,000. In the above-mentioned range binder resin, it is possible to sufficiently move the polyvalent metal ions in addition to the occurrence of cracking of the ink coating film due to the swelling of the ink aggregation layer while sufficiently expressing the generally required water resistance. It is preferably selected because it does not inhibit the aggregation effect. Furthermore, the viscosity of the pretreatment liquid can be kept within a suitable range by using a binder resin having the above number average molecular weight range.

  In addition, the number average molecular weight in this invention and the weight average molecular weight mentioned later can be measured by a conventional method. As an example, using a TSKgel column (manufactured by Tosoh Corp.), GPC (manufactured by Tosoh Corp., HLC-8120GPC) equipped with an RI detector was measured as a polystyrene-equivalent number average molecular weight measured using THF as a developing solvent. can do.

<Surfactant>
The pretreatment liquid of the present invention preferably uses a surfactant in order to adjust the surface tension and improve the wettability on the substrate. Various surfactants such as acetylene-based, siloxane-based, acrylic-based, and fluorine-based surfactants are known, but wettability on the substrate and wettability of inkjet ink applied later. In order to achieve both the printing stability of the pretreatment liquid and siloxane-based and / or acetylene-based surfactants, it is preferable to prevent unevenness when the pretreatment liquid is applied. Therefore, it is most preferable to use an acetylene surfactant.

The surfactant used in the present invention can be synthesized by a known method, or a commercially available product can be used. When the surfactant is selected from commercially available products, for example, BY16-201, FZ-77, FZ-2104, FZ-2110, FZ-2162, F-2123, L-7001, L-7002 as siloxane surfactants. SF8427, SF8428, SH3749, SH8400,8032ADDITIVE, SH3773M (manufactured by Dow Corning Toray Co., Ltd.), Tegoglide410, Tegoglide432, Tegoglide435, Tegoglide440, Tegoglide450, Tegotwin4000, Tegotwin4100, Tegowet250, Tegowet260, Tegowet270, Tegowet280 (manufactured by Evonik Degussa), SAG- 002, SAG-503A (manufactured by Nissin Chemical Industry Co., Ltd.), B K-331, BYK-333, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYKUV3500, BYK-UV3510 (manufactured by BYK Chemie), KF-351A, KF-352A, KF-353 KF-354L, KF355A, KF-615A, KF-640, KF-642, KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.
As acetylene-based surfactants, Surfinol 61, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 420, 440, 465, 485, SE, SE-F, Dinol 604, 607 (manufactured by Air Products) ), Olfin E1004, E1010, E1020, PD-001, PD-002W, PD-004, PD-005, EXP. 4001, EXP. 4200, EXP. 4123, EXP. 4300 (manufactured by Nissin Chemical Industry Co., Ltd.).
Said surfactant may be used independently and may use 2 or more types together.

  The addition amount of the surfactant contained in the pretreatment liquid of the present invention is preferably 0.01 wt% or more and 5.0 wt% or less, and 0.05 wt% or more and 3.0 wt% with respect to the total amount of the pretreatment liquid. The following are particularly preferred: However, the content of the surfactant needs to be determined in consideration of the surface tension of the inkjet ink described later.

  In the present invention, from the viewpoint of preventing bleeding of the printed matter, the surface tension of the pretreatment liquid is preferably set to be equal to or higher than the surface tension of the inkjet ink. By making the surface tension of the pretreatment liquid larger than the surface tension of the ink-jet ink, when the pre-treatment liquid is applied to the substrate, the surfactant does not hinder the wetting and spreading of the ink-jet ink printed later. Is preferable because it is appropriately oriented on the surface of the coating film.

  Further, in order to make the pretreatment liquid of the present invention compatible with high-speed printing on various substrates, as a surfactant contained in the pretreatment liquid, HLB (Hydrophile-Lipophile) which is a parameter representing the hydrophilicity / hydrophobicity of the material. It is preferable to use one having a balance value of 1 to 8. Since the surfactant having an HLB value of 8 or less has an excellent orientation speed on the surface of the pretreatment liquid, the surfactant moves to the interface between the substrate and the pretreatment liquid immediately after being applied to the base material. And improving the wettability of the pretreatment liquid. Moreover, by setting the HLB value to 1 to 8, the wettability of the inkjet ink applied later can be secured, and the image quality can be further improved. It is more preferable to use a surfactant having an HLB value of 1.5 to 6.5, and it is particularly preferable to use a surfactant having a HLB value of 2 to 5.

  The HLB value of the surfactant can be calculated using the Griffin method when the structure of the surfactant is clearly known, but when a compound with an unknown structure is included, for example, “Surfactant Handbook” (edited by Nishiichiro et al., Sangyo Tosho Co., Ltd., 1960), p. The HLB value of the surfactant can be experimentally determined by the method described in H.324. Specifically, after dissolving 0.5 g of the surfactant in 5 mL of ethanol, the solution was titrated with a 2 wt% aqueous phenol solution while stirring at 25 ° C., and the end point was when the solution became cloudy. . When the amount of the phenol aqueous solution required up to the end point is A (mL), the HLB value can be calculated by the following formula (2).

Formula (2):

HLB value = 0.89 × A + 1.11

<Water>
The content of water contained in the pretreatment liquid of the present invention is preferably in the range of 10 to 90% by weight, more preferably 20 to 85% by weight, and more preferably 30 to 80% with respect to the total amount of the pretreatment liquid. More preferably, it is% by weight.

<Other materials>
The pretreatment liquid of the present invention suppresses damage to members used in the coating apparatus, exerts the effect of suppressing bleeding as an ink agglomerated layer to the maximum, and further suppresses pH fluctuation over time. For the purpose of maintaining the performance as a liquid for a long period of time, a pH adjuster can be added to the pretreatment liquid. In the present invention, a material having pH-adjusting ability can be arbitrarily selected, and in the case of basification, alkanolamine such as dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine; aqueous ammonia; water Alkali metal hydroxides such as lithium oxide, sodium hydroxide, and potassium hydroxide; alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate can be used.
When acidifying, use hydrochloric acid, sulfuric acid, acetic acid, citric acid, maleic acid, maleic anhydride, succinic acid, tartaric acid, malic acid, phosphoric acid, boric acid, fumaric acid, malonic acid, ascorbic acid, glutamic acid, etc. be able to.
Said pH adjuster may be used independently and may use 2 or more types together. In order to strictly control the pH and to maximize the desired physical properties, it is preferable to use two or more in combination.

  As a compounding quantity of a pH adjuster, it is preferable that it is 0.01-5 weight% with respect to the pretreatment liquid whole quantity, and it is more preferable that it is 0.1-4.5 weight%. If the added amount of the pH adjuster is too small, the pH will change immediately due to external stimuli such as dissolution of carbon dioxide, but if the pH adjuster is contained excessively, the function of the metal salt in the pretreatment solution will be inhibited. Therefore, the blending amount is preferably within the above range.

<Other ingredients>
The pretreatment liquid of the present invention can be appropriately added with additives such as antifoaming agents and preservatives as necessary in order to obtain desired physical property values. When using these additives, the blending amount is preferably 0.01% by weight or more and 10% by weight or less, and preferably 0.01% by weight or more and 5% by weight or less with respect to the total amount of the pretreatment liquid. Further preferred. If it is excessively mixed, the function of the metal salt in the pretreatment liquid may be hindered, so the addition amount is preferably in the above range.

<Pretreatment liquid production method>
The pretreatment liquid of the present invention comprising the above components is appropriately selected from, for example, a metal salt, water, an organic solvent, and, if necessary, a binder resin, a surfactant, a pH adjuster, and the above-mentioned examples The additive component to be added is added, stirred and mixed, and then filtered as necessary. The binder resin may be previously dissolved or dispersed in water or an organic solvent and added in the form of a binder resin solution / dispersion. However, the method for producing the pretreatment liquid of the present invention is not limited to the above.

  In addition, when the binder resin is dissolved and / or the pretreatment liquid is stirred and mixed, the mixture may be heated in the range of 40 to 100 ° C. as necessary. However, when resin fine particles are used as the binder resin, it is preferable to heat at a temperature equal to or lower than the MFT of the resin fine particles.

  Moreover, when filtering, a filter opening diameter will not be restrict | limited especially if a coarse particle and dust can be removed, However, Preferably it is 0.3-10 micrometers, More preferably, it is 0.5-5 micrometers. Moreover, when filtering, a filter may use single type or may use multiple types together.

<Characteristics of pretreatment liquid>
The pH of the pretreatment liquid of the present invention is not particularly limited, but 4 ≦ pH ≦ 9 is preferable because the aggregation effect of the inorganic metal salt and / or the organic metal salt is increased. A particularly preferred pH range is 5-8.

  The pH can be measured by a known method, for example, a desktop pH meter F-72 manufactured by HORIBA, Ltd. using a standard ToupH electrode or a sleeve ToupH electrode.

  The pretreatment liquid of the present invention preferably has a viscosity at 25 ° C. adjusted to be higher than 9 mPa · s and not higher than 30 mPa · s. By keeping the viscosity within the above range, the pretreatment liquid does not flow at the time of drying, and the film thickness does not partially change, and uniform coating becomes possible. Any pretreatment liquid that satisfies the above viscosity range can be applied to various printing methods described below. Moreover, the viscosity at 25 degreeC of the said pretreatment liquid is 9.5 from a viewpoint which is excellent in the uniform coating property at high speed, and can express the outstanding function irrespective of the printing method of a pretreatment liquid. 29 mPa · s is more preferable, and 10 to 28 mPa · s is most preferable.

  The viscosity of the pretreatment liquid in the present invention can be measured using, for example, an E-type viscometer (TVE25L viscometer manufactured by Toki Sangyo Co., Ltd.).

  The surface tension at 25 ° C. of the pretreatment liquid of the present invention is preferably 20 to 45 mN / m. By keeping the surface tension of the pretreatment liquid in the above range, the instantaneous wettability is made suitable, and uniform coating can be realized particularly by suppressing the occurrence of coating unevenness during high-speed printing. Also, the wettability of the ink applied on the top is improved. That is, even during high-speed printing, filling of the printed matter and uniform coatability are improved, and a high-quality printed matter can be obtained. From the viewpoint of obtaining a pretreatment liquid that can be applied to ultra high speed printing close to 100 m / min, the surface tension of the pretreatment liquid at 25 ° C. is more preferably 21 to 43 mN / m, and preferably 22 to 42 mN / m. Particularly preferred is 23 to 40 mN / m. Further, as described above, the surface tension of the pretreatment liquid is preferably equal to or higher than the surface tension of the ink jet ink because the wettability of the ink applied thereon is improved and bleeding and color unevenness can be reduced.

  The surface tension of the pretreatment liquid in the present invention can be measured by a platinum plate method in a 25 ° C. environment using, for example, a surface tension meter (CBVPZ manufactured by Kyowa Interface Science Co., Ltd.).

<Amount of pretreatment liquid applied>
When the pretreatment liquid of the present invention is applied to a substrate to obtain a coating film, the coating amount of the pretreatment liquid of the present invention is preferably ¹ to 25 g / m2. By keeping the coating amount within the above range, bleeding and cracking are suppressed, and the pretreatment liquid layer after coating is excellent in drying property, and adhesion to the inside of the coating apparatus and the base material after printing are stacked. It is possible to obtain a printed matter that is free from tackiness (stickiness).

  The amount of the pretreatment liquid applied to the substrate is obtained by the following equation (3) based on, for example, the weight increment when the entire surface is applied to a predetermined area in the substrate.

Formula (3):

(Application amount of pretreatment liquid) (g / m ² ) = (A−B) × 10000 ÷ C ÷ D

In formula (3), A represents the weight (g) of the base material after the entire surface of the pretreatment liquid has been applied, B represents the weight of only the base material before coating, and C Represents the area (cm ² ) of the coated substrate, and D represents the specific gravity (g / cm ² ) of the pretreatment liquid.

  Subsequently, components of the inkjet ink of the present invention will be described below.

<Pigment>
In addition to the viewpoint of having water resistance, light resistance, weather resistance, gas resistance, etc., the ink-jet ink of the present invention has a high aggregation rate and high speed compared to dyes when the pretreatment liquid of the present invention is used in high-speed printing. From the viewpoint of obtaining an image with high image quality, a pigment is included as a coloring material. In the present invention, any of known organic pigments and inorganic pigments can be used. These pigments are preferably contained in the range of 2% by weight or more and 15% by weight or less, more preferably 2.5% by weight or more and 15% by weight or less, more preferably 3% by weight or less based on the total amount of the ink-jet ink. It is particularly preferable that it is contained in the range of from 10% to 10% by weight. By setting the pigment content to 2% by weight or more, sufficient color developability can be obtained even in one-pass printing. In addition, by setting the pigment content to 15% by weight or less, the viscosity of the ink-jet ink can be kept in a range suitable for ink-jet printing, and the long-term stability of the ink-jet ink can be maintained as a good result. Printing stability can be ensured.

  Examples of the cyan organic pigment that can be used in the present invention include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64, 66, and the like. In particular, C.I. I. One or more selected from CI Pigment Blue 15: 3 and / or 15: 4 are preferred.

  Examples of magenta organic pigments that can be used in the present invention include C.I. I. Pigment Red 5, 7, 12, 22, 23, 31, 48 (Ca), 48 (Mn), 49, 52, 53, 57 (Ca), 57: 1, 112, 122, 146, 147, 150, 185 238, 242, 254, 255, 266, 269, C.I. I. Pigment Bio Red 19, 23, 29, 30, 37, 40, 43, 50 and the like. In particular, C.I. I. Pigment red 122, 150, 185, 266, 269 and / or C.I. I. One or more selected from the group consisting of CI Pigment Bio Red 19 is preferable. Among them, C.I. I. Pigment Bio Red 19 is particularly preferable because it exhibits color reproduction close to Japan Color 2011 and European color standard FOGRA39, and also exhibits particularly high color developability when used in combination with the pretreatment liquid of the present invention.

  Examples of the yellow organic pigment that can be used in the present invention include C.I. I. Pigment Yellow 10, 11, 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, 213 and the like. Among these, C.I. I. One or more selected from the group consisting of CI Pigment Yellow 13, 14, 74, 120, 180, 185 and 213 are preferred.

  Examples of the black organic pigment that can be used in the present invention include aniline black, lumogen black, and azomethine azo black. Further, a plurality of chromatic color pigments such as the above-mentioned cyan pigments, magenta pigments, yellow pigments, and the following orange pigments, green pigments, brown pigments can be used to form black pigments.

  Special colors such as orange pigments, green pigments and brown pigments can also be used in the inkjet ink of the present invention. Specifically, C.I. I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 64, 71, C.I. I. Pigment green 7, 36, 43, 58, pigment brown 23, 25, 26, and the like.

  Although it does not specifically limit as an inorganic pigment used by this invention, For example, a carbon black and iron oxide can be mentioned as a black pigment, and a titanium oxide can be mentioned as a white pigment.

Examples of the carbon black pigment that can be used in the present invention include carbon black produced by a furnace method or a channel method. Among these, these carbon blacks have a primary particle size of 11 to 50 nm, a specific surface area by BET method of 50 to 400 m ² / g, a volatile content of 0.5 to 10% by weight, a pH of 2 to 10 and the like. Those having the following are preferred. As a commercial product having such characteristics, for example, No. 25, 30, 33, 40, 44, 45, 52, 850, 900, 950, 960, 970, 980, 1000, 2200B, 2300, 2350, 2600; MA7, MA8, MA77, MA100, MA230 (Mitsubishi Chemical Corporation) Manufactured), RAVEN 760UP, 780UP, 860UP, 900P, 1000P, 1060UP, 1080UP, 1255 (manufactured by Colombian Carbon), REGAL330R, 400R, 660R, MOGUL L (manufactured by Cabot), Nexex 160IQ, 170IQ, 35, 75; PrintX30, 35, 40, 45, 55, 75, 80, 85, 90, 95, 300; Special Black 350, 550; Nerox 305, 500, 505, 600, 605 (Orion Engineered Carbon Etc.) and any of them can be preferably used.

  Moreover, as a titanium oxide used suitably as a white inorganic pigment, both an anatase type and a rutile type can be used, but it is preferable to use a rutile type in order to improve the concealability of printed matter. Moreover, although what was manufactured by any methods, such as a chlorine method and a sulfuric acid method, it is preferable to use the titanium oxide manufactured by the chlorine method from whiteness high.

  The surface of the titanium oxide pigment that can be used in the present invention is preferably treated with an inorganic compound and / or an organic compound. Examples of inorganic compounds include silicon, aluminum, zirconium, tin, antimony, titanium compounds, and hydrated oxides thereof. Examples of organic compounds include polyhydric alcohols, alkanolamines or derivatives thereof, higher fatty acids or metal salts thereof, organometallic compounds, and the like. Among them, polyhydric alcohols or derivatives thereof highly enhance the surface of titanium oxide. It can be hydrophobized to improve dispersion stability and is preferably used.

  In the present invention, in order to keep the hue and color developability of the printed matter within a suitable range, a plurality of the above pigments can be mixed and used. For example, a small amount of one or more pigments selected from a cyan organic pigment, a magenta organic pigment, an orange organic pigment, and a brown organic pigment is used to improve the color tone at a low printing rate with respect to black ink using a carbon black pigment. Can be added.

<Pigment dispersion resin>
As a method of stably dispersing and holding the pigment in the ink-jet ink, a method of adsorbing and dispersing a pigment dispersion resin on the pigment surface, a method of adsorbing and dispersing a water-soluble and / or water-dispersible surfactant on the pigment surface , A method of chemically and physically introducing a hydrophilic functional group on the pigment surface and dispersing it in the ink without a dispersant or surfactant, a method of coating the pigment with a self-dispersing resin and microencapsulating it, etc. Can be mentioned.

  For the ink-jet ink used in the present invention, it is preferable to select a method using a pigment-dispersed resin among the above. By selecting and examining the monomer composition and molecular weight of the pigment dispersion resin, the resin adsorption capacity for the pigment and the charge of the pigment dispersion resin can be easily adjusted, resulting in imparting dispersion stability to the fine pigment and pre-treatment This is because the ability to reduce the dispersion function of the pigment by the liquid can be controlled.

  The kind of pigment dispersion resin used by this invention is not specifically limited, For example, an acrylic resin, a styrene acrylic resin, a maleic acid resin, a styrene maleic acid resin, a urethane resin, an ester resin etc. can be used. In the present invention, it is particularly preferable to use an acrylic resin or a styrene acrylic resin in terms of material selectivity and ease of synthesis. In addition, the pigment dispersion resin used by this invention can synthesize | combine by a well-known method, and can also use a commercial item.

  In the present invention, it is preferable to introduce an alkyl group having 10 to 36 carbon atoms into the pigment dispersion resin. This is because the viscosity of the pigment dispersion, further dispersion stabilization, and viscosity stabilization can be realized by setting the alkyl group to have 10 to 36 carbon atoms. In addition, as carbon number of an alkyl group, Preferably it is C12-30, More preferably, it is C18-24. Further, the alkyl group may be linear or branched as long as it has 10 to 36 carbon atoms, but is preferably linear. Linear alkyl groups include lauryl group (C12), myristyl group (C14), cetyl group (C16), stearyl group (C18), aralkyl group (C20), behenyl group (C22), lignoceryl group (C24), serotoyl Examples thereof include a group (C26), a montanyl group (C28), a meristyl group (C30), a dotriacontanoyl group (C32), a tetratriacontanoyl group (C34), and a hexatriacontanoyl group (C36).

  The content of the monomer-containing copolymer containing an alkyl chain having 10 to 36 carbon atoms contained in the pigment-dispersed resin used in the present invention is low in viscosity of the pigment dispersion and rub resistance of the printed matter. From the viewpoint of achieving good balance with gloss and gloss, it is preferably 5% by weight to 60% by weight, more preferably 10% by weight to 55% by weight, and particularly preferably 20% by weight to 50% by weight.

  In the present invention, it is particularly preferable to introduce an aromatic group into the pigment-dispersed resin, since the ability to adsorb the pigment can be improved and the dispersion function of the pigment can be quickly reduced when mixed with the pretreatment liquid. . This is a strong molecule called cation-π interaction between the cation component in the metal salt contained in the pretreatment liquid and the pigment dispersion resin having an aromatic group when the pretreatment liquid and the inkjet ink are mixed. This is because interstitial force works and both are preferentially adsorbed. Examples of aromatic groups include phenyl, naphthyl, anthryl, tolyl, xylyl, mesityl, and anisyl groups. Of these, a phenyl group and a tolyl group are preferable from the viewpoint of ensuring sufficient dispersion stability.

  From the viewpoint of coexistence of the dispersion stability of the pigment and the adsorption performance of the pretreatment liquid, the content of the monomer containing an aromatic ring is preferably 5 to 65% by weight based on the total amount of the pigment dispersion resin, More preferably, it is 10 to 50% by weight.

  In the present invention, it is preferable that the acid value of the pigment-dispersed resin is 30 to 400 mgKOH / g. By keeping the acid value within the above range, it is preferable because the solubility of the pigment dispersion resin in water can be secured and the viscosity of the pigment dispersion can be suppressed. When the acid value of the pigment dispersion resin is smaller than 30 mgKOH / g, the solubility in water is too low so that the pigment dispersion does not get wet and the pigment dispersion becomes unstable. In addition, it is difficult to cause anion-cation interaction and adsorption equilibrium transfer, and the effect of suppressing color mixture between pigments is reduced. On the contrary, when the acid value of the pigment dispersion resin is larger than 400 mgKOH / g, it is preferable because the interaction between the pigment dispersion resins becomes stronger and the viscosity becomes higher or the effect of the pretreatment liquid becomes insufficient. Absent. The acid value of the pigment-dispersed resin is preferably 50 to 350 mgKOH / g, more preferably 100 to 300 mgKOH / g.

  The acid value can be measured by a potentiometric titration method using a known apparatus, for example, “potentiometric automatic titration apparatus AT-610” manufactured by Kyoto Electronics Industry Co., Ltd.

  In the present invention, the acid group is preferably neutralized with a base in order to increase the solubility in ink. However, if an excessive amount of base is added, the cation component contained in the pretreatment liquid is neutralized, and a sufficient effect cannot be exhibited. Therefore, attention must be paid to the amount added. Whether or not the amount of the base added is excessive can be confirmed, for example, by preparing a 10% by weight aqueous solution of the pigment dispersion resin and measuring the pH of the aqueous solution. In this invention, in order to fully express the function of a pretreatment liquid, it is preferable that the pH of the said aqueous solution is 7-11, and it is more preferable that it is 7.5-10.5.

  Examples of the base for neutralizing the pigment dispersion resin used in the present invention include alkanolamines such as diethanolamine, triethanolamine and N-methyldiethanolamine; ammonia water; lithium hydroxide, sodium hydroxide and potassium hydroxide. Examples thereof include alkali metal hydroxides; alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium hydrogen carbonate, and potassium carbonate.

  Regarding the molecular weight of the pigment-dispersed resin, the weight average molecular weight is preferably in the range of 1,000 to 100,000, and more preferably in the range of 5,000 to 50,000. When the molecular weight is in the above range, the pigment is stably dispersed in water, and viscosity adjustment when applied to a water-based ink composition is easy to perform. If the weight average molecular weight is 1,000 or less, the dispersion resin is easy to dissolve in the solvent added to the ink composition, and the resin adsorbed to the pigment is detached, so that the dispersion stability is significantly deteriorated. Resulting in. When the weight average molecular weight is 100,000 or more, the viscosity at the time of dispersion becomes high and the ejection stability from the ink jet head is remarkably deteriorated, so that the printing stability is lowered.

  The content of the pigment dispersion resin of the present invention is preferably 1 to 50% by weight based on the pigment. By setting the content of the pigment dispersion resin to 1 to 50% by weight with respect to the pigment, the viscosity of the pigment dispersion is suppressed, and the viscosity stability and dispersion stability of the pigment dispersion and inkjet ink are improved. This is preferable because when it is mixed with the pretreatment liquid, it can cause a rapid decrease in the dispersion function. The content of the pigment dispersion resin is more preferably 2 to 45% by weight with respect to the pigment, further preferably 4 to 40% by weight with respect to the pigment, and most preferably 5 to 35% by weight with respect to the pigment.

<Water-soluble organic solvent>
As the water-soluble organic solvent used in the ink-jet ink of the present invention, a known organic solvent can be arbitrarily used, but a glycol ether solvent and / or an alkyl polyol having a boiling point of 180 ° C. or higher and 280 ° C. or lower at 1 atmosphere. It is preferable to contain 2 or more types of solvent. The boiling point under 1 atm is preferably in the range of 183 ° C. or more and 270 ° C. or less, and more preferably in the range of 185 ° C. or more and 250 ° C. or less. By using a water-soluble organic solvent that satisfies the above boiling range, the wettability and drying property of the ink-jet ink can be controlled within a suitable range, and the ejection stability is improved and combined with the pretreatment liquid. In this case, image quality defects such as bleeding can be prevented.

  In addition, the boiling point under 1 atmosphere in this invention can be measured by using thermal analyzers, such as DSC (differential scanning calorimetry).

  Examples of glycol ether solvents that have a boiling point under 1 atm of 180 ° C. or higher and 280 ° C. or lower that are preferably used in the present invention include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol mono Hexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, dipropylene Glycol monomethyl ether, dipropy Glycol monoalkyl ethers such as diglycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether; diethylene glycol diethyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl Glycol dialkyl ethers such as ether, triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol diethyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether and tetraethylene glycol methyl ethyl ether That.

  In the present invention, among the above glycol ether solvents, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, triethylene glycol monoethyl ether, triethylene glycol monoethyl ether, triethylene glycol monoethyl ether, Ethylene glycol monopropyl ether, triethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, diethylene glycol butyl methyl ether, triethylene glycol methyl ethyl ether, Triethylene glycol diethyl ether, triethylene glycol Chill methyl ether, it is preferable to select a tetraethylene glycol methyl ethyl ether.

  Examples of the alkyl polyol solvent having a boiling point under 1 atm of 180 ° C. or higher and 280 ° C. or lower include 1,2-ethanediol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2 -Heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,3 -Butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methylpenta 2,4-diol, 2-ethyl-1,3-hexanediol, ethylene glycol, diethylene glycol, dipropylene glycol, and the like dibutylene glycol.

  In the present invention, among the above alkyl polyol solvents, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1, It is preferable to select 2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, and 1,2-heptanediol.

  The total amount of the glycol ether solvent and / or alkyl polyol solvent having a boiling point of 180 ° C. or higher and 280 ° C. or lower under the above-mentioned 1 atm used in the present invention is 5 wt% or more and 50 wt% or less with respect to the total amount of the inkjet ink. Preferably there is. Further, from the viewpoint of ensuring the discharge stability from the ink jet nozzle and sufficient wetting and spreading properties when combined with the pretreatment liquid, the total amount of the water-soluble organic solvent is 10% by weight or more and 45% by weight. More preferably, it is 15 to 40% by weight. If the total amount of the water-soluble organic solvent is less than 5% by weight, the moisture retention of the ink is insufficient, and the ejection stability may be impaired. Conversely, when the total content of the water-soluble organic solvent is more than 65% by weight, the viscosity of the ink becomes too high, which may undesirably impair ejection stability.

  In the present invention, in order to adjust the moisture retention and wettability of the ink-jet ink, an organic solvent other than the glycol ether solvent and / or the alkyl polyol solvent having a boiling point of 180 ° C. or higher and 280 ° C. or lower at 1 atm. Can be used together. Specifically, monohydric alcohols, trihydric alcohols, nitrogen-containing solvents, heterocyclic compounds and the like listed above can be used as water-soluble organic solvents that can be used in the pretreatment liquid. These solvents may be used alone or in combination.

  The total amount of the water-soluble organic solvent in the inkjet ink of the present invention is preferably 5% by weight or more and 70% by weight or less based on the total amount of the inkjet ink, from the viewpoint of achieving both moisture retention, drying property, and wettability of the inkjet ink. It is more preferably 10% by weight or more and 60% by weight or less, and particularly preferably 15% by weight or more and 50% by weight or less.

In the present invention, a water-soluble organic solvent having a boiling point of 240 ° C. or higher under 1 atm as a water-soluble organic solvent contained in the ink-jet ink further contains 0% by weight or more and less than 10% by weight with respect to the total amount of the water-based ink-jet ink. And / or a water-soluble organic solvent having a boiling point of 210 ° C. or higher under 1 atm is preferably contained in an amount of 0% by weight to less than 20% by weight based on the total amount of the water-based inkjet ink. By controlling the amount of the organic solvent within the above range, it is possible to improve the drying property to such an extent that there is no sufficient settling even in high-speed printing.
In addition, when combined with a pretreatment liquid, the content of the water-soluble organic solvent having a boiling point of less than 240 ° C. under 1 atm from the viewpoint of obtaining an image having excellent image quality even at a high printing speed is More preferably, the content is 0% by weight or more and less than 7% by weight, particularly preferably 0% by weight or more and less than 5% by weight, based on the total amount of the water-based inkjet ink.
For the same reason, the content of the water-soluble organic solvent having a boiling point of less than 210 ° C. at 1 atm is more preferably 0% by weight or more and less than 18% by weight based on the total amount of the water-based inkjet ink. It is particularly preferable to contain more than 16% by weight.
In the above, “contains 0% by weight” means that a water-soluble organic solvent having a boiling point of 240 ° C. or higher under 1 atm is not included.

<Binder resin>
It is preferable to add a binder resin to the inkjet ink of the present invention. As described above, water-soluble resins and resin fine particles are generally known as binder resins. Among these, the resin fine particles have a higher molecular weight than the water-soluble resin, and the resin fine particles can lower the viscosity of the inkjet ink, and a larger amount of resin can be blended in the inkjet ink. Suitable for increasing resistance. Examples of the resin used as the resin fine particles include acrylic, styrene acrylic, urethane, styrene butadiene, vinyl chloride, and polyolefin. Among these, acrylic and styrene acrylic resin fine particles are preferably used in consideration of the stability of the ink composition and the durability of the printed matter.

  However, when the binder resin in the inkjet ink is resin fine particles, it is necessary to consider the minimum film-forming temperature (MFT) of the resin fine particles. When resin particles with a low MFT are used, the MFT of the resin particles is further reduced by the water-soluble organic solvent added to the ink-jet ink, causing the resin particles to be fused and aggregated even at room temperature. This is because clogging may occur. In order to avoid the above problem, it is preferable that the MFT of the resin fine particles is set to 60 ° C. or higher by adjusting the monomer constituting the resin fine particles.

  The MFT can be measured by, for example, an MFT tester manufactured by Tester Sangyo Co., Ltd. Specifically, a 25 wt% aqueous solution of resin fine particles was applied on the film so as to have a WET film thickness of 300 μm, and then allowed to stand on the tester with a temperature gradient applied. The temperature at the boundary between the generated region and the region where the transparent resin film is formed is defined as MFT.

  However, considering the maintenance performance of the ink jet printer, in the present invention, the binder resin is more preferably a water-soluble resin. The water-soluble resin preferably has a weight average molecular weight in the range of 8,000 to 50,000, and more preferably in the range of 10,000 to 40,000. When the weight average molecular weight is 10,000 or more, the coating film resistance of the printed matter can be improved, and when the weight average molecular weight is 50,000 or less, the ejection stability from the inkjet head is excellent. Inkjet ink can be obtained.

  Moreover, when selecting water-soluble resin for binder resin, an acid value is also important, and it is preferable that an acid value is 10-80 mgKOH / g, and it is more preferable that an acid value is 20-50 mgKOH / g. When the acid value is less than 10 mgKOH / g, the re-solubility of the solidified ink-jet ink is poor, and clogging on the ink-jet head nozzle is generated as in the case of the resin fine particles. When combined, it is difficult to cause thickening and aggregation of the ink due to the anion-cation interaction, so the effect of suppressing bleeding and color unevenness is reduced, which is not preferable. An acid value of 80 mgKOH / g or more is not preferable because the water resistance of the printed film is significantly deteriorated although the ink can be dissolved again even when the ink-jet ink is solidified.

  The content of the binder resin in the total amount of the ink-jet ink is in the range of 1% by weight to 20% by weight and more preferably in the range of 2% by weight to 15% by weight of the total amount of the ink-jet ink in terms of solid content. Particularly preferably, it is in the range of 3 wt% to 10 wt%.

<Surfactant>
The inkjet ink of the present invention preferably uses a surfactant for the purpose of adjusting the surface tension and improving the image quality. On the other hand, if the surface tension is too low, the nozzle surface of the ink jet head gets wet with the ink jet ink and impairs the discharge stability. Therefore, the selection of the type and amount of the surfactant is very important. From the viewpoint of ensuring optimal wettability and realizing stable ejection from the inkjet nozzle, it is preferable to use siloxane, acetylene, and fluorine surfactants, and siloxane and acetylene surfactants are used. It is particularly preferable to do this. The addition amount of the surfactant is preferably 0.01% by weight or more and 5.0% by weight or less, and more preferably 0.05% by weight or more and 3.0% by weight or less with respect to the total amount of the inkjet ink.

  In addition, the molecular weight of the surfactant is also important in terms of controlling wettability during the process of evaporating the inkjet ink and improving the quality of printed matter such as abrasion resistance and solvent resistance. The molecular weight of the surfactant is preferably 1,000 or more and 7,000 or less, more preferably 1,500 or more and 5,000 or less in terms of weight average molecular weight. By setting it as 1,000 or more, the effect which controls the wetting with respect to a printing base material can be heightened, and the inkjet ink excellent in storage stability can be obtained by setting it as 7,000 or less.

  The surfactant used in the present invention can be synthesized by a known method, or a commercially available product can be used. When the surfactant is selected from commercially available products, for example, as a siloxane surfactant or acetylene surfactant, those listed above as surfactants that can be used in the pretreatment liquid, and as fluorine surfactants Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, Capstone FS-30, FS-31 (DuPont), PF-151N, PF-154N (Omnova) Can be mentioned. Said surfactant may be used independently and may use 2 or more types together. However, when ink is applied on the pretreatment liquid layer, high-concentration polyvalent metal ions may be mixed into the ink layer, causing the ink surface tension to fluctuate greatly and cause mixed-color bleeding. Therefore, two or more surfactants are preferably used in combination in order to suppress fluctuations in the surface tension of the ink.

  The surfactant used for the inkjet ink and the surfactant used for the pretreatment liquid may be the same or different. When using different surfactants, it is better to determine the blending amount after paying attention to the surface tension of both as described above.

<Water>
As water contained in the ink-jet ink of the present invention, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions.

  The content of water that can be used in the present invention is preferably in the range of 20 to 90% by weight of the total weight of the ink.

<Other ingredients>
In addition to the above-described components, the ink-jet ink of the present invention may contain a pH adjuster in order to obtain an ink having desired physical properties as required. In the present invention, a material having pH adjusting ability can be arbitrarily selected. In the case of basification, alkanolamines such as dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine; ammonia water; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide; carbonic acid Alkali metal carbonates such as lithium, sodium carbonate, sodium hydrogen carbonate and potassium carbonate can be used. When acidifying, use hydrochloric acid, sulfuric acid, acetic acid, citric acid, maleic acid, maleic anhydride, succinic acid, tartaric acid, malic acid, phosphoric acid, boric acid, fumaric acid, malonic acid, ascorbic acid, glutamic acid, etc. be able to. Said pH adjuster may be used independently and may use 2 or more types together.

  The blending amount of the pH adjuster is preferably 0.01 to 5% by weight, more preferably 0.1 to 3% by weight, and preferably 0.2 to 1.5% by weight with respect to the total amount of the inkjet ink. Most preferably it is. By staying within the above range, pH change due to dissolution of carbon dioxide in the air does not occur, and when the pretreatment liquid and ink come into contact, the solid component aggregation effect by polyvalent metal ions is inhibited. Therefore, the effect of the present invention can be suitably expressed, which is preferable.

  In addition to the above components, the ink-jet ink of the present invention may contain additives such as antifoaming agents, preservatives, infrared absorbers, and ultraviolet absorbers in order to obtain inks having desired physical properties as required. It can be added appropriately. As an example of the addition amount of these additives, 0.01% by weight or more and 10% by weight or less is preferable with respect to the total weight of the ink.

  In addition, it is preferable that the inkjet ink of this invention does not contain a polymerizable monomer substantially. Here, “substantially does not contain” means that the ink is not intentionally added, and does not exclude a slight amount of mixing or generation when the ink-jet ink is manufactured and stored.

<Inkjet ink set>
The ink-jet ink of the present invention may be used in a single color, but it can also be used as an ink-jet ink set in which a plurality of colors are combined according to the application. The combination is not particularly limited, but a full color image can be obtained by using three colors of cyan, yellow, and magenta. Moreover, the black feeling can be improved by adding black ink, and the visibility of characters and the like can be improved. Furthermore, color reproducibility can be improved by adding colors such as orange and green. When printing on a print medium other than white, a clear image can be obtained by using white ink together. Further, when the water-based inkjet ink has magenta ink, the magenta ink may be C.I. I. It is particularly preferred to have CI Pigment Bio Red 19.

<Method for producing inkjet ink>
The ink-jet ink of the present invention comprising the above-described components is produced, for example, through the following process. However, the manufacturing method of the inkjet ink of the present invention is not limited to the following.

(1) Production of Pigment Dispersion First, a pigment is added to an aqueous medium in which a pigment dispersion resin and water are mixed, and after mixing and stirring, dispersion processing is performed using a disperser. Thereafter, centrifugation or filtration is performed as necessary to obtain a pigment dispersion.

  It is effective to perform premixing before the dispersion processing. Premixing may be performed by adding a pigment to an aqueous medium in which at least a pigment dispersion resin and water are mixed. Such a premixing operation is preferable because it improves wettability of the pigment surface and promotes adsorption of the dispersant to the pigment surface.

  The disperser used in the pigment dispersion treatment may be any commonly used disperser, and examples thereof include a ball mill, a roll mill, a sand mill, a bead mill, and a nanomizer. Among the above, a bead mill is preferably used, and specifically, it is commercially available under trade names such as a super mill, a sand grinder, an agitator mill, a glen mill, a dyno mill, a pearl mill, and a cobol mill.

  In the pigment premixing and dispersion treatment, the pigment dispersant may be dispersed only in water or may be dispersed in a mixed solvent of an organic solvent and water.

  As a method for controlling the particle size distribution of the pigment dispersion, it is possible to reduce the size of the grinding media of the disperser mentioned above, change the material of the grinding media, increase the filling rate of the grinding media, The shape of the agitator) can be changed, the dispersion treatment time can be lengthened, classification can be performed with a filter or a centrifuge after dispersion treatment, and a combination of these methods. In the present invention, in order to keep the pigment in a suitable particle size range, it is preferable that the diameter of the pulverization media of the disperser is 0.1 to 3 mm. Further, glass, zircon, zirconia, and titania are preferably used as the material for the grinding media.

(2) Preparation of inkjet ink Next, the water-soluble organic solvent, water, and, if necessary, the binder resin, surfactant, and other additives mentioned above are added to the pigment dispersion, followed by stirring and mixing.

  In addition, you may stir and mix the said mixture, heating in the range of 40-100 degreeC as needed. However, when resin fine particles are used as the binder resin, the heating temperature is preferably set to be equal to or lower than the MFT of the resin fine particles.

(3) Removal of coarse particles The coarse particles contained in the above mixture are removed by a technique such as filtration and centrifugation to obtain an inkjet ink. A known method can be appropriately used as the filtration separation method. The filter pore diameter is not particularly limited as long as coarse particles and dust can be removed, but is preferably 0.3 to 5 μm, more preferably 0.5 to 3 μm. Moreover, when filtering, a filter may use single type or may use multiple types together.

<Characteristics of inkjet ink>
The inkjet ink of the present invention preferably has a viscosity at 25 ° C. adjusted to 3 to 20 mPa · s. If it is this viscosity area | region, the stable discharge characteristic will be shown also in the high frequency head of 10-70 KHz especially from the head which has a frequency of normal 4-10 KHz. In particular, by setting the viscosity at 25 ° C. to 4 to 10 mPa · s, even when used for an inkjet head having a design resolution of 600 dpi or more, it can be stably discharged.

  The viscosity at 25 ° C. of the inkjet ink in the present invention can be measured by a conventional method. Specifically, an E type viscometer (TVE25L type viscometer manufactured by Toki Sangyo Co., Ltd.) can be used and measured using 1 mL of ink.

  The inkjet ink of the present invention preferably has an average secondary particle diameter (D50) of the pigment of 40 nm to 500 nm, more preferably 50 nm to 400 nm, and particularly preferably in order to obtain a printed matter having excellent color developability. Is 60 nm to 300 nm. In order to keep the average secondary particle diameter within the preferable range, the pigment dispersion treatment step may be controlled as described above.

<Method for producing printed matter>
As a method for producing a printed matter using an ink set comprising the pretreatment liquid of the present invention and an inkjet ink, after applying the pretreatment liquid on a substrate conveyed at a speed of 30 m / min or more, the pretreatment liquid is used. A method of applying inkjet ink to the applied portion by a one-pass printing method is preferably used.

  The “one-pass printing method” is a printing method in which an ink jet head is scanned only once with respect to a stopped base material, or a base material is passed only once under a fixed ink jet head. Ink is not printed on the top again. The one-pass printing method has fewer scans than the conventional ink-jet printing method (multi-pass printing method) in which the ink-jet head is scanned a plurality of times, and can increase the printing speed. Preferred. In particular, the adoption of this method is indispensable for realizing inkjet printing as an alternative to offset printing and gravure printing, which has been actively studied in recent years.

  On the other hand, various problems must be solved in order to replace inkjet printing with offset printing or gravure printing. Regarding the printing speed, in order to replace the conventional printing method, it is necessary to support high-speed printing of at least 30 m / min. Needless to say, there is no image defect such as blurring or color unevenness in the printed matter, but it is essential to obtain a high-quality image at a recording resolution of 600 dpi or higher. “Recording resolution” is expressed in units of dpi (DotsPerInch) and represents the number of inkjet ink droplets applied per inch. The “recording resolution” in this specification refers to both the recording resolution in the transport direction of the substrate and the recording resolution in the direction perpendicular to the transport direction (hereinafter referred to as the recording width direction) within the substrate surface. Shall.

  As described above, in order to realize high-speed printing in inkjet printing, it is essential to employ a one-pass printing method. On the other hand, in order to complete printing in one scan, the amount of ink droplets (drop volume) ejected from the inkjet head nozzle at a time is larger than when the same image is printed by the multi-pass printing method. As described in the prior art, in the case of inkjet inks that contain water as a component and fix the image by penetrating the base material and / or evaporating the liquid component, an increase in the drop volume will cause the inkjet ink to fall through and cause poor drying. In addition, since the permeability of the ink-jet ink differs depending on the base material, it was extremely difficult to obtain a high-quality image regardless of the base material.

  In the present invention, the inorganic metal salt and / or the organic metal salt in the dissolved state described above are included, and the metal ion derived from the inorganic metal salt and / or the organic metal salt includes a polyvalent metal ion, and A content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less based on the total amount of the pretreatment liquid; and an organic solvent containing a compound containing one or more hydroxyl groups in the molecular structure; By using a pretreatment liquid whose content of the organic solvent having a boiling point of 180 ° C. or higher is 15% by weight or less with respect to the total amount of the pretreatment liquid, the above problem is solved. That is, the pretreatment liquid is applied on the base material before printing the inkjet ink, and the ink aggregation layer is formed on the base material, thereby eliminating the influence due to the difference in the base material type. In addition, by using the inkjet ink of the present invention, it is possible to achieve rapid aggregation of solid components and drying of liquid components, and to obtain high-quality images in high-speed and high-resolution inkjet printing regardless of the substrate. Is possible.

  Below, the manufacturing method of the printed matter using the ink set of this invention is demonstrated.

<Method of applying pretreatment liquid>
In this invention, before printing inkjet ink, a pretreatment liquid is provided on the base material conveyed at a speed of 30 m / min or more. As a method of applying the pretreatment liquid on the substrate, either a method of printing without contact with the substrate, such as inkjet printing, or a method of printing with the pretreatment liquid in contact with the substrate is adopted. May be.

  In recent years, inkjet heads capable of discharging even a liquid composition having a viscosity of about 100 mPa · s at 25 ° C. have been developed by adopting a heater in the head and optimizing the flow path and nozzle structure in the head. The preferred viscosity range at 25 ° C. of the pretreatment liquid of the present invention is 2 to 100 mPa · s, and the pretreatment liquid can be printed without any problem even by ink jet printing. In addition, when adopting inkjet printing as a method for applying the pretreatment liquid, it is possible to apply the pretreatment liquid only to a portion to which the inkjet ink is applied, from the viewpoint of leaving a texture unique to the base material in the non-printing portion. preferable.

  On the other hand, from the viewpoint of preventing damage to members constituting the ink jet head and ensuring ink jet printing suitability, a printing method in which a pretreatment liquid is brought into contact with the substrate is preferably used in the present invention. As the printing method for contacting the pretreatment liquid, a conventionally known printing method can be arbitrarily selected, but from the viewpoint of simplicity of the apparatus, uniform coating property, work efficiency, economy, etc., the roller type is selected. It is preferable to adopt. The “roller format” refers to a printing format in which a pretreatment liquid is applied in advance to a rotating roll and then the pretreatment liquid is transferred to a substrate. Examples of the roller type coating machine preferably used in the present invention include an offset gravure coater, a gravure coater, a doctor coater, a bar coater, a blade coater, a flexo coater, and a roll coater.

<Thermal energy action after pretreatment liquid application>
In the present invention, after applying the pretreatment liquid to the substrate, it is preferable to apply thermal energy to the substrate and dry the pretreatment liquid on the substrate before applying the ink jet ink. In particular, it is preferable that the pretreatment liquid is completely dried before applying the ink jet ink, that is, the liquid component of the pretreatment liquid is completely removed. When the inkjet ink is applied before the pretreatment liquid is completely dried, the dissolution and / or dispersion function of the solid component in the inkjet ink can be further promoted, while the liquid component on the substrate becomes excessive, If the thermal energy applied after ink jet printing is insufficient, image defects such as waving and blurring of the substrate may occur.

  There is no restriction | limiting in particular in the effect | action method of the heat energy used by this invention, For example, a heat drying method, a hot air drying method, an infrared rays drying method, a microwave drying method, a drum drying method etc. can be mentioned. The above drying methods may be used alone or in combination. For example, by using the heat drying method and the hot air drying method in combination, the pretreatment liquid can be dried more quickly than when each of them is used alone.

  In the present invention, from the viewpoint of preventing damage to the substrate and bumping of the liquid component in the pretreatment liquid, when employing the heat drying method, the drying temperature is set to 35 to 100 ° C. When employing a drying method, the hot air temperature is preferably 50 to 250 ° C. From the same point of view, when the infrared drying method is employed, it is preferable that 50% or more of the integrated value of all infrared output used for infrared irradiation exists in the wavelength region of 700 nm or more and 1500 nm or less.

<Pretreatment liquid application / drying device>
The pretreatment liquid application / drying apparatus of the present invention is equipped in-line or off-line with respect to the ink jet printing apparatus described later, but is preferably equipped in-line from the viewpoint of convenience during printing.

<Inkjet ink application method>
As described above, the inkjet ink is applied to the substrate by a one-pass printing method. Note that, as described above, there are two types of one-pass printing methods: a method in which the inkjet head is scanned only once with respect to the stopped substrate, and a method in which the substrate is passed only once under the fixed inkjet head. However, when the inkjet head is scanned, it is necessary to adjust the discharge timing in consideration of the movement of the inkjet head, and the landing position is likely to be shifted. A method of scanning is preferably used. In that case, it is preferable that the conveyance speed of a base material shall be 30 m / min or more. In particular, when the pretreatment liquid application apparatus is installed in-line with respect to the ink jet printing apparatus, the pretreatment liquid application apparatus to the ink jet printing apparatus are continuously arranged, and the substrate to which the pretreatment liquid is applied remains as it is. It is preferable to be conveyed to the ink jet printing unit.

  Further, as described above, by using the ink set of the present invention, a high-quality image can be produced even at a recording speed of 600 dpi or higher, but the same as offset printing or gravure printing. The recording resolution of the printed material is particularly preferably 1200 dpi or more from the viewpoint that a printed material having image quality can be provided.

<Inkjet head>
When adopting a method of passing the substrate only once under the fixed inkjet head as a one-pass printing method, the recording resolution in the recording width direction is determined by the design resolution of the inkjet head. As described above, in the present invention, since the recording resolution in the recording width direction is preferably 600 dpi or more, it is inevitably preferable that the design resolution of the inkjet head is 600 dpi or more. If the design resolution of the inkjet head is 600 dpi or more, printing can be performed with one inkjet head for each color, which is preferable from the viewpoint of miniaturization of the apparatus and economy. When an inkjet head having a design resolution lower than 600 dpi is used, a plurality of inkjet heads for each color are used side by side in the transport direction of the substrate, so that the recording resolution in the recording width direction can be achieved even in one-pass printing. 600 dpi or more can be realized.

  The printing resolution in the substrate transport direction depends not only on the design resolution of the inkjet head but also on the driving frequency and printing speed of the inkjet head. For example, the printing speed is halved or the driving frequency is doubled. By doing so, the recording resolution in the transport direction is doubled. If it is impossible to achieve 600 dpi or more as the print resolution in the transport direction at a print speed of 30 m / min or more due to the design of the ink jet head, printing can be performed by arranging a plurality of ink jet heads for each color in the transport direction of the substrate. It is possible to achieve both speed and printing resolution.

  In the ink jet one-pass printing of the present invention, the drop volume of the ink jet ink largely depends on the performance of the ink jet head, but is preferably in the range of 1 to 30 pL in order to realize a high quality image. In order to obtain a high-quality image, it is particularly preferable to use an ink jet head having a gradation specification capable of changing the drop volume.

<Thermal energy action after application of inkjet ink>
In order to dry the inkjet ink and the undried pretreatment liquid after applying the ink jet ink onto the base material to which the pretreatment liquid has been applied, it is preferable to apply thermal energy to the base material. The heat energy operating method and conditions preferably used in the present invention are the same as those used for drying the pretreatment liquid.

<Inkjet ink dryer>
The ink-jet ink drying apparatus is equipped inline or offline with respect to the ink-jet printing apparatus, but is preferably equipped inline from the viewpoint of convenience during printing. In the present invention, in order to prevent bleeding, color unevenness, curling of the substrate, etc., it is preferable to apply the thermal energy within 30 seconds after printing, more preferably within 20 seconds, and within 10 seconds. It is particularly preferable to apply.

<Amount of pretreatment liquid and inkjet ink applied>
In the present invention, it is preferable that the ratio of the applied amount of the inkjet ink to the applied amount of the pretreatment liquid is 0.1 or more and 10 or less. The ratio of the applied amounts is more preferably 0.5 or more and 9 or less, and particularly preferably 1 or more and 8 or less. When the ratio of the applied amount falls within the above range, the change in the texture of the base material caused by the excessive amount of the pretreatment liquid or the effect of the pretreatment liquid becomes insufficient due to the excessive amount of the ink jet ink. A high-quality printed matter can be obtained without causing bleeding or uneven color.

<Print speed>
As described above, when a printed matter is produced using the ink set of the present invention, the printing speed is preferably 30 m / min or more, more preferably 50 m / min or more, and 75 m / min or more. More preferably, it is particularly preferably 100 m / min or more.

<Base material>
When printing using the ink set of the present invention, known substrates can be arbitrarily used as the substrate to be used, such as fine paper, recycled paper, coated paper, art paper, cast paper, fine coated paper, A paper substrate such as synthetic paper, a plastic substrate such as a polyvinyl chloride sheet, a PET film, a polypropylene film, and a polyethylene film can be used. The substrate may have a smooth print medium surface or an uneven surface, and may be transparent, translucent, or opaque. Further, two or more of these print media may be bonded to each other. Furthermore, a peeling adhesive layer or the like may be provided on the opposite side of the printing surface, and an adhesive layer or the like may be provided on the printing surface after printing. Further, the shape of the substrate used in the present invention may be a roll or a sheet.

  In the present invention, in order to sufficiently develop the function of the pretreatment liquid, the substrate is preferably paper or a PET film, a polypropylene film, or a polyethylene film, and particularly preferably a paper substrate. Among the paper base materials, it is particularly preferable to use the pretreatment liquid of the present invention for hard-to-absorb base materials such as coated paper, art paper, cast paper, fine coated paper, and synthetic paper. Since these base materials have low liquid permeability, they tend to cause image defects such as bleeding and color unevenness, undulations, curls, etc., but these problems can be suitably solved by using the pretreatment liquid of the present invention. it can.

In the present invention, the “hardly absorbable substrate” means that the absorption coefficient with respect to water measured by the Bristow method (J. TAPPI paper pulp test method No. 51-87) shown below is 0 to 0.6 ml / m ^2. Represents a substrate that is msec ^1/2 . The absorption coefficient can be measured, for example, by using an automatic scanning liquid absorption meter manufactured by Kumagai Riki Kogyo Co., Ltd. Specifically, the relationship between the water absorption amount (ml / m ² ) and the square root of contact time (msec ^1/2 ) obtained using the above device and water for a contact time of 100 to 1000 milliseconds. Therefore, the slope of the straight line obtained by the least square method is taken as the absorption coefficient.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.

<Production example of resin varnish A>
The following materials were mixed for 1 hour with stirring, heated to 90 ° C., and further mixed for 1 hour. Then, the resin varnish A was obtained by cooling to room temperature.
25 parts of PVA103 (polyvinyl alcohol manufactured by Kuraray Co., Ltd., saponification degree 98-99% (complete saponification), polymerization degree 300)
・ Ion exchange water 75 parts

<Production example of resin varnish B>
The following materials were mixed for 1 hour with stirring, heated to 90 ° C., and further mixed for 1 hour. Then, the resin varnish B was obtained by cooling to room temperature.
-PVA103 25 parts-PVA217 10 parts (polyvinyl alcohol manufactured by Kuraray Co., Ltd., saponification degree 87-89% (partial saponification), polymerization degree 1 700)
・ Ion exchange water 75 parts

<Production example of resin varnish C>
The following materials were mixed for 1 hour with stirring, heated to 90 ° C., and further mixed for 1 hour. Then, the resin varnish C was obtained by cooling to room temperature.
-RS1113 25 parts (modified Kuraray polyvinyl alcohol, saponification degree 97-98% (complete saponification))
・ Ion exchange water 75 parts

<Production example of resin varnish D>
The following materials were mixed for 1 hour with stirring, heated to 90 ° C., and further mixed for 1 hour. Then, the resin varnish A was obtained by cooling to room temperature.
・ PVA103 55.4 parts ・ Ion-exchanged water 44.6 parts

<Production example of pretreatment liquid 1>
The ingredients listed below were added sequentially with stirring. The mixture was mixed at room temperature for 1 hour, heated to 60 ° C. and further mixed for 1 hour, allowed to cool to room temperature, and filtered through a membrane filter having a pore size of 1 μm to obtain a pretreatment liquid 1.
・ Resin varnish A 20 parts ・ Calcium chloride dihydrate 7.5 parts (manufactured by Tokuyama)
・ 2-propanol 4 parts ・ Surfinol 465 (acetylene surfactant manufactured by Air Products) 0.5 part ・ Proxel GXL 0.05 part (preservative, 1,2-benzisothiazole-3-made by Arch Chemicals) ON solution)
・ Ion-exchanged water 67.95 parts

<Production example of pretreatment liquids 2 to 31>
Pretreatment liquids 2 to 31 were obtained in the same manner as pretreatment liquid 1 using the materials listed in Tables 1 and 2 below.

In addition, the material described in Tables 1-2 is as follows.
・ CaCl2 · 2H2O: Calcium chloride dihydrate • MgCl2 · 6H2O: Magnesium chloride hexahydrate • MgSO4: Magnesium sulfate • Ca (NO3) 2 · 4H2O: Calcium nitrate tetrahydrate • Zn (CH3COO) 2 · 2H2O : Zinc acetate dihydrate [Al2 (OH) nCl6-n] m: Polyaluminum chloride (manufactured by Taki Chemical Co., Ltd.)
FeSO4 · 7H2O: Iron sulfate heptahydrate YNO3 · 6H2O: Yttrium nitrate hexahydrate • (CH3COO) 2Ca · H2O: Calcium acetate monohydrate • (CH3CH (OH) COO) 2Ca · 5H2O: DL— Calcium lactate pentahydrate NH4 (C2H4 (OH) COO): ammonium lactate Jonkrill 1673: acrylic emulsion manufactured by BASF (solid content 45%)
・ Hydran CP-7020: Cationic polyurethane manufactured by Dainippon Ink & Chemicals, Inc. (solid content 40%)
IPrOH: 2-propanol MB: 3-methoxybutanol 1,2-PD: 1,2-propanediol 1,2-HexD: 1,2-hexanediol EDG: diethylene glycol monoethyl ether Surfynol 465 (Acetylene-based surfactant manufactured by Air Products)
-Dynol 607: Acetylene-based surfactant manufactured by Air Products-TegoWet 280: Siloxane-based surfactant manufactured by Evonik Degussa-Zonyl FS-300: Fluorine-based surfactant manufactured by DuPont-Proxel GXL (preservative, manufactured by Arch Chemicals 1 , 2-Benzisothiazol-3-one solution)

<Example of production of pigment dispersion resin 1>
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 93.4 parts of butanol and replaced with nitrogen gas. The inside of the reaction vessel was heated to 110 ° C., and a mixture of 40 parts of styrene as a polymerizable monomer, 30 parts of acrylic acid, 30 parts of behenyl acrylate, and 6 parts of V-601 (manufactured by Wako Pure Chemical) as a polymerization initiator. The polymerization reaction was carried out dropwise over 2 hours. After completion of the dropwise addition, the mixture was further reacted at 110 ° C. for 3 hours, then 0.6 part of V-601 (manufactured by Wako Pure Chemical Industries) was added, and the reaction was further continued at 110 ° C. for 1 hour to obtain a dispersion resin 1 solution. It was. Further, after cooling to room temperature, 37.1 parts of dimethylaminoethanol was added for neutralization, and then 100 parts of water was added to make it aqueous. Then, it heated to 100 degreeC or more, butanol was azeotroped with water, butanol was distilled off, and it adjusted so that solid content might be 30%. As a result, an aqueous solution having a solid content of 50% of the pigment dispersion resin 1 was obtained. It was 9.7 when pH of the aqueous solution (solid content 30%) of the said pigment dispersion resin 1 was measured using the desktop type pH meter F-72 by Horiba Ltd. Further, the weight-average molecular weight of the pigment-dispersed resin was measured by using the above-mentioned method using HLC-8120GPC manufactured by Tosoh Corporation. As a result, it was 22,500.

<Example of production of pigment dispersion resin 2>
An aqueous solution with a solid content of 30% of the pigment dispersion resin 2 was obtained by using the same method as the pigment dispersion resin 1 except that 50 parts of acrylic acid and 50 parts of lauryl methacrylate were used as the polymerizable monomers. The pH of the aqueous solution (solid content 30%) of the pigment dispersion resin 2 was 8.1, and the weight average molecular weight of the pigment dispersion resin 2 was 15,000.

<Example of production of pigment dispersion 1>
20 parts of pigment, 20 parts of an aqueous solution of pigment dispersion resin 1 (solid content 30%) and 60 parts of water were mixed, predispersed with a disper, and then filled with 1800 g of zirconia beads having a diameter of 0.5 mm. This dispersion was performed for 2 hours using a 6 L dyno mill to obtain Pigment Dispersion Liquid 1. The pigments used for preparing each ink are as follows.
Cyan: LIONOL BLUE 7358G manufactured by Toyocolor Co.
(C.I. Pigment Blue 15: 3)
Magenta: Inkjet Magenta E5B02 manufactured by Clariant
(CI Pigment Bio Red 19)
Yellow: LIONOL YELLOW TT-1405G manufactured by Toyocolor Co., Ltd.
(C.I. Pigment Yellow 14)
Black: PrinteX85 manufactured by Orion Engineered Carbons
(Carbon black)

<Example of production of pigment dispersion 2>
Pigment dispersion 1 except that an aqueous solution of pigment dispersion resin 2 (solid content 30%) is used as the pigment dispersion resin, and FASTOGEN SUPER MAGENTA RG (CI Pigment Red 122) manufactured by DIC is used as the Magenta pigment. By using the same method as in Example 1, pigment dispersion 2 was obtained.

<Production example of water-soluble resin varnish>
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, 20 parts of Jonkrill 819 (acrylic resin manufactured by BASF, weight average molecular weight 14,500, acid value 75 mgKOH / g), dimethylaminoethanol 2.38. And 77.62 parts of water were added to make it water-soluble. 1 g of this mixed solution was sampled, heated and dried at 180 ° C. for 20 minutes, and the solid content concentration was measured. Based on the obtained solid content concentration, water was added so that the produced water-soluble resin varnish had a non-volatile content of 20%, thereby obtaining a water-soluble resin varnish having a solid content concentration of 20%.

<Production example of CMYK inkjet ink set 1>
The materials described below were sequentially added to the mixing container while stirring with a disper, and stirred until it was sufficiently uniform. Then, it filtered with the membrane filter with a hole diameter of 1 micrometer. CMYK inkjet ink set 1 was obtained by using four colors of CMYK as pigment dispersion 1.
Pigment dispersion 1 30 parts Water-soluble resin varnish 13 parts 1,2-butanediol 30 parts Surfinol 465 0.2 parts TegoWet 280 0.5 parts Triethanolamine 0.5 parts Proxel GXL 0. 05 parts ・ Ion-exchanged water 25.75 parts

<Examples of inkjet inks 2-12>
Inkjet inks 2 to 12 were obtained in the same manner as inkjet ink 1 using the materials listed in Table 3 below.

In addition, the material which is not described in Tables 1-2 among the materials described in Table 3 is as follows.
・ Johncrill 538: BASF acrylic resin emulsion, 46% solids
1,2-PG: 1,2-propanediol 1,2-BuD: 1,2-butanediol 1,2-PenD: 1,2-pentanediol 1,5-PenD: 1,5- Pentanediol-DEG: Diethylene glycol-TEG: Triethylene glycol-MFG: Propylene glycol monomethyl ether-iPDG: Diethylene glycol monoisopropyl ether-BDG: Diethylene glycol monobutyl ether-NaOHaq: 4 wt% sodium hydroxide aqueous solution

<Example of production of base material provided with pretreatment liquid>
Using the printing test machine K lock sprufer (manufactured by Matsuo Sangyo Co., Ltd.) and the pretreatment liquids 1 to 31 created above at the coating speeds shown in Table 4, OK top coat + paper (manufactured by Oji Paper Co., Ltd.) Was applied uniformly. At this time, using a ceramic roller having a different number of lines, coating was performed a plurality of times as necessary, so that the WET coating amount was the pretreatment liquid coating amount described in Table 4 ± 0.1 g / m ² .

Immediately after applying the pretreatment liquid, the substrate was fixed on a conveyor capable of transporting the substrate. Thereafter, the conveyor is operated at a predetermined speed shown in Table 4, and the pretreatment liquid is dried by passing through a box provided with a mechanism that generates hot air of 100 ° C. inside the conveyance path. A base material provided with a pretreatment liquid was prepared. In addition, the time when the base material on the conveyor was exposed to hot air in the box was as follows.
・ For conveyance speed of 75 m / min: 0.8 seconds ・ For conveyance speed of 50 m / min: 1.2 seconds

<Examples of ink-jet ink prints>
An ink jet head KJ4B-QA (manufactured by Kyocera Corporation) was installed on the upper part of the conveyor capable of transporting the substrate and filled with ink jet ink. The inkjet head has a design resolution of 600 dpi and a maximum drive frequency of 30 kHz. When printing is performed at the maximum drive frequency and a printing speed of 75 m / min, the recording resolution in the substrate transport direction is 600 dpi.

  Next, after fixing the substrate to which the pretreatment liquid has been applied on the conveyor, the conveyor is driven at the speed shown in Table 4 and when passing through the installation section of the inkjet head, the inkjet ink is dropped in the order of CMYK. The sample was discharged at 12 pL, and sample No. 5 (bicycle) of high-definition color digital standard image data (ISO / JIS-SCID JISX9201 compliant JSA-00001) was printed. Immediately after printing, the substrate was fixed on a conveyor that can convey the substrate. Thereafter, the conveyor was operated at a predetermined speed shown in Table 5, and the ink-jet ink printed matter was created by passing through a box provided with a mechanism for generating hot air at 100 ° C. in the transport path. The above was carried out under each of the two types of printing conditions shown in Table 4 below, and a printed material was created.

  The combinations of the pretreatment liquid and the inkjet ink used in the production of the printed material are as shown in Table 5 below.

<Example of production of a base material provided with a pretreatment liquid to which a dye has been added>
In order to improve the visibility, 0.1 g of KayfectRed PLIquid (a dye made by Nippon Kayaku Co., Ltd.) was added to 10 g of each of the pretreatment liquids 1 to 31 prepared above, and the mixture was well mixed and dissolved. The pretreatment liquid to which the dye was added was uniformly applied to OK top coat + paper (Oji Paper Co., Ltd.) using a printing tester K lock sprufer (manufactured by Matsuo Sangyo Co., Ltd.). At this time, using a ceramic roller having a different number of lines, and applying as many times as necessary, the WET application amount becomes the pretreatment liquid application amount described in Table 4 ± 0.1 g / m ^2. One pretreatment liquid was applied at three coating speeds of 30 m / min, 50 m / min, and 75 m / min.

  Immediately after applying the pretreatment liquid to which the dye was added, the base material was then placed in an air oven at 50 ° C. and dried for 3 minutes to prepare a base material to which the pretreatment liquid to which the dye had been added was applied.

<Evaluation>
The following evaluation was performed about the base material which provided the pre-processing liquid which added the pre-processing liquid which added the dye, the inkjet ink printed material, and the dye which were produced above. The results of evaluation were as shown in Tables 5-6.

<Evaluation of uneven coating of pretreatment liquid>
About the base material which gave the pretreatment liquid which added dye and added the pretreatment liquid created by changing coating speed, the applicability of the pretreatment liquid was evaluated by visually observing the degree of color unevenness. The evaluation results were as follows, and Δ or better was considered good.
A: Coating unevenness was not observed in any of the coatings at any speed.
A: Coating unevenness was not observed at 50 m / min or less, and coating unevenness was observed at 75 m / min.
Δ: Coating unevenness was not observed at 30 m / min, and coating unevenness was observed at 50 m / min or more.
X: The coating unevenness was seen also in what applied at any speed.

<Evaluation of pretreatment liquid drying property>
Another OK top coat + paper is layered on the base material to which the pretreatment liquid added with the dye prepared at a coating speed of 50 m / min is applied, and a load of 200 g is applied from above, and it is allowed to stand at 25 ° C. for 24 hours. I put it. Thereafter, the stacked OK topcoat + paper was peeled off, and the pretreatment liquid was confirmed to be set off. Moreover, the base material which added the pretreatment liquid which added the dye immediately after preparation was rubbed 10 times with a cotton swab, and the drying property of the base material was evaluated together with the result of the set-off. The evaluation results were as follows, and Δ or better was considered good.
(Double-circle): Pretreatment liquid did not adhere to a cotton swab by 10 reciprocating rubs, and no set-off was observed.
○: Although the pretreatment liquid adhered to the cotton swab after 5 reciprocations, no set-off was observed.
Δ: Adhesion of the pretreatment liquid to the cotton swab was observed by reciprocating rubbing, but no set-off was observed.
X: Both adhesion of the pretreatment liquid to the cotton swab and set-off were observed.

<Evaluation of tack>
Overlay another OK top coat + paper on the base material to which the pretreatment liquid added with the dye prepared at a coating speed of 50 m / min was applied, and apply a load of 200 g from above, and heat at 35 ° C. and 80% It was allowed to stand for 24 hours under humidified conditions. Thereafter, the stacked OK topcoat + paper was peeled off, and the pretreatment liquid was confirmed to be set off. Moreover, the base material which gave the pretreatment liquid which added the dye after leaving still under heating and humidification conditions was rubbed 10 times with a cotton swab, and the tack of the base material was evaluated together with the result of the set-off. The evaluation results were as follows, and Δ or better was considered good.
(Double-circle): Pretreatment liquid did not adhere to a cotton swab by 10 reciprocating rubs, and no set-off was observed.
○: Although the pretreatment liquid adhered to the cotton swab after 5 reciprocations, no set-off was observed.
Δ: Adhesion of the pretreatment liquid to the cotton swab was observed by reciprocating rubbing, but no set-off was observed.
X: Both adhesion of the pretreatment liquid to the cotton swab and set-off were observed.

<Evaluation of uneven helicopter coating>
About the base material to which the pretreatment liquid added with dye was added, which was created by changing the coating speed, the film thickness uniformity of the helicopter in the coating part was evaluated by visually observing the degree of coating unevenness of the helicopter. . The evaluation results were as follows, and Δ or better was considered good.
A: The coating applied at any speed showed no unevenness in the helicopter coating.
○: Helicopter coating unevenness was not seen at 50 m / min or less, and coating unevenness was seen at 75 m / min.
Δ: Edge coating unevenness was not observed at 30 m / min, and coating unevenness was observed at 50 m / min or more.
X: Helicopter coating unevenness was observed in those coated at any speed.

<Evaluation of blur>
While visually observing the image quality of the 4C (CMYK) printed part of ink-jet ink printed matter (the image of the clock present in the printed matter of high-definition color digital standard image data (sample number 5)), the dot shape was magnified 200 times with a microscope. It was observed by magnifying, and the blur was evaluated. The evaluation results were as follows, and Δ or better was considered good.
A: No blur was observed visually, and the dots were independent even under a microscope, and no blur was observed.
○: No blurring was visually observed, and even with a microscope, up to 3C (CMY) dots were independent, but only K ejected to the top showed blurring in a slightly elliptical shape.
Δ: No blurring was visually observed, and up to 2C (CM) dots were independent on the microscope, but Y and K were slightly elliptical and blotted.
X: Bleeding was observed visually, and M, Y, and K did not retain a circular shape in the 4C printing portion, and color mixing occurred.

<Evaluation of ink drying properties>
Another OK topcoat + paper was overlaid on the ink-jet ink print, a load of 200 g was applied from above, and the mixture was allowed to stand at 25 ° C. for 24 hours. Thereafter, the stacked OK top coat + paper was peeled off, and the ink was confirmed to be transferred. In addition, 4C (CMYK) printing part of ink-jet ink print immediately after creation (clock image existing in the print of high-definition color digital standard image data (sample number 5)) is rubbed 10 times with a cotton swab, and the result of set-off In addition, the dryness of the printed material was evaluated. The evaluation results were as follows, and Δ or better was considered good.
(Double-circle): The ink did not adhere to a cotton swab by 10 reciprocating rubs, and no set-off was seen.
○: Adhesion of ink was observed on the swab after 5 reciprocations, but no set-off was observed.
Δ: Ink adhesion was observed on the cotton swab by reciprocating rubbing, but no set-off was observed.
X: Both adhesion and set-off of ink to the cotton swab were observed.

<Evaluation of crack>
At the same time as visually observing the coating cracks in the 4C (CMYK) printing part of the inkjet ink printed matter (the image of the clock present in the printed matter of high-definition color digital standard image data (sample number 5)), the presence or absence of fine cracks Was observed with a microscope at 200 times to evaluate cracking. The evaluation results were as follows, and a value of Δ or more was good.
A: No crack was observed visually, and no crack was observed even with a microscope.
○: No cracks were visually observed, and 1 to 2 fine cracks were observed with a microscope.
Δ: No crack was observed visually, and 3-5 fine cracks were observed with a microscope.
X: A large crack that could be confirmed visually was observed.

<Evaluation of solid filling>
Using the equipment used in the manufacture of the ink-jet ink prints, OK top coat + paper (Oji Paper Co., Ltd.) using cyan (C), magenta (M), yellow (Y), and black (K) inks one by one. The product was discharged at a drop volume of 12 pL to produce a solid print.

About the solid printed matter of each color created above, it was observed visually or with a microscope whether there was a portion where the embedding was insufficient and the base material was exposed, and the solid embedding was evaluated. The evaluation results were as follows, and Δ or better was considered good. The evaluation was performed for all colors of CMYK, and the worst evaluations are listed in Table 4.
◎: The solid part was completely buried by visual observation and microscopic observation. ○: A part of light color was observed when observed with a microscope, but it was sufficiently buried by visual observation. The visible part was observed, but it was sufficiently buried visually. ×: Visual density unevenness was observed or the substrate was exposed.

<Evaluation of water resistance>
The solid printed matter of each color was rubbed 10 times with a cotton swab soaked in water, and the water resistance of the printed matter was evaluated. The evaluation results were as follows, and Δ or better was considered good. The evaluation was performed for all colors of CMYK, and the worst evaluations are listed in Table 4.
A: No ink adhered to the cotton swab even after 10 reciprocations.
○: No ink adhered to the swab after 7 reciprocations, but ink adhered to the swab within 10 reciprocations.
Δ: No ink adhered to the swab after 5 reciprocations, but no ink adhered to the swab within 7 reciprocations.
X: Adhesion of ink was observed on the cotton swab within 5 round trips.

<Evaluation of concentration>
About the solid print of each said color, the spectrophotometer X-RITE528 was used, OD value was measured by status E in the light source D50, the viewing angle of 2 degrees, and the CIE color system. In each of the magenta, yellow, and cyan color regions, it was evaluated whether the density was high when compared with Japan Color 2011. The evaluation results were as follows, and Δ or higher was judged as a practical level.
◎: Magenta, yellow, and cyan all have a density of 0.1 or more higher than Japan Color 2011 ○: Magenta, yellow, and cyan have a density in the range of 0 to 0.1 from Japan Color 2011 High, 0.1 or more higher than Japan Color 2011 in any two areas Δ: Density is higher in the range of 0 to 0.1 than Japan Color 2011 in any two areas of magenta, yellow, and cyan, either In one area, it was 0.1 or more higher than Japan Color 2011. x: Magenta, yellow, and cyan were all lower in density than Japan Color 2011

<Evaluation of ejection stability>
An ink jet discharge device equipped with an ink jet head KJ4B-QA (manufactured by Kyocera Corporation) was prepared and filled with black ink jet ink. After confirming that there is no missing nozzle, after discharging for 2 hours continuously under the conditions of drop volume 5pL and driving frequency 30kHz, the nozzle check pattern is printed and the number of missing nozzles is counted. Was evaluated. The evaluation criteria were as follows, and Δ or better was considered good.
◎: No nozzle missing in nozzle check pattern 2 hours after printing started ○: 1-2 nozzle missing in nozzle check pattern 2 hours after printing started △: Nozzle check 2 hours after printing started Nozzle missing 3-4 in the pattern ×: Nozzle missing 5 or more in the nozzle check pattern 2 hours after the start of printing

  The pretreatment liquid, ink set, and printed matter manufacturing method of the present invention can obtain high-quality images regardless of the substrate, and are suitably used particularly in high-speed, high-recording-resolution ink jet printing. be able to.

Claims (18)

A pretreatment liquid used with an aqueous inkjet ink containing at least a pigment,
The pretreatment liquid includes a dissolved inorganic metal salt and / or organic metal salt, and an organic solvent,
The metal ion derived from the inorganic metal salt and / or the organic metal salt contains a polyvalent metal ion, and the content of the polyvalent metal ion is 2% by weight or more and 8% by weight or less with respect to the total amount of the pretreatment liquid. ,
The organic solvent contains a compound having one or more hydroxyl groups in the molecular structure, and the content of the organic solvent having a boiling point of 180 ° C. or higher is 15% by weight or less based on the total amount of the pretreatment liquid. Pre-treatment liquid. 2. The polyvalent metal ion includes at least one selected from Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Al ³⁺ , Fe ²⁺ , and Fe ^3+. The pretreatment liquid described.   The pretreatment liquid according to claim 1 or 2, wherein the pretreatment liquid further contains a water-soluble binder resin.   The pretreatment liquid according to claim 3, wherein the binder resin contains a nonionic water-soluble resin.   The weight ratio of the content of the binder resin to the content of metal ions derived from the inorganic metal salt and / or organic metal salt is more than 0 and less than 20, Treatment liquid.   The pretreatment liquid according to claim 1, wherein the viscosity of the pretreatment liquid is higher than 9 mPa · s and 30 mPa · s or less.   The pretreatment liquid according to claim 1, wherein the pretreatment liquid contains a surfactant, and the surface tension of the pretreatment liquid is 20 to 45 mN / m. A coating film obtained by coating the pretreatment liquid according to claim 1, wherein the coating amount of the pretreatment liquid is 1 to 25 g / m ² . An ink set comprising the pretreatment liquid according to claim 1, a water-based inkjet ink containing a pigment, a water-soluble organic solvent, and water.
  The water-soluble organic solvent contained in the water-based ink-jet ink contains two or more glycol ether solvents and / or alkyl polyol solvents having a boiling point of 180 ° C. or higher and 280 ° C. or lower at 1 atm. Item 10. The ink set according to Item 9.   The water-based ink-jet ink contains a water-soluble organic solvent having a boiling point of 240 ° C. or higher under 1 atm of 0 to 10% by weight based on the total amount of the water-based ink-jet ink. The ink set according to 10.   The water-based ink-jet ink contains a water-soluble organic solvent having a boiling point of 240 ° C or higher under 1 atm of 0 to 7% by weight based on the total amount of the water-based ink-jet ink. 11. The ink set according to any one of 11.   The water-based ink-jet ink contains a water-soluble organic solvent having a boiling point of 210 ° C or higher at 1 atm with respect to the total amount of the water-based ink-jet ink of 0 to 20% by weight. 12. The ink set according to any one of 12.   The ink set according to any one of claims 9 to 13, wherein the water-based inkjet ink contains 2% by weight or more and less than 15% by weight of the pigment with respect to the total amount of the water-based inkjet ink.   The ink set according to claim 9, wherein the water-based inkjet ink further contains a water-soluble resin as a binder resin.   The water-based inkjet ink has at least a magenta ink, and the magenta ink is a C.I. I. The ink set according to any one of claims 9 to 15, comprising Pigment Bio Red 19.   It is a manufacturing method of the water-based inkjet ink printed matter using the pretreatment liquid in any one of Claims 1-7, the coating film of Claim 8, or the ink set in any one of Claims 9-16, Comprising: 30m Including a step of applying a pretreatment liquid to a substrate conveyed at a speed of at least / min, and a step of applying the water-based inkjet ink to the portion provided with the pretreatment liquid by a one-pass printing method. The manufacturing method of water-based inkjet ink printed material.   The method for producing a water-based inkjet ink print according to claim 17, wherein the substrate is a paper or film substrate.