JP2004285344A - Aqueous recording liquid of pigment dispersion and printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous recording liquid given by dispersing pigment therein, having satisfactory storage stability of the recording liquid, capable of satisfactorily preventing a nozzle from clogging, capable of giving satisfactory water resistance, weather resistance, and light resistance to printed matter, and capable of giving the printed matter blackness and a glossy feeling compartible with each other. <P>SOLUTION: This aqueous recording liquid of a pigment dispersion contains at least the pigment and a resin, wherein the resin is contained in an amount of 50-200 pts.wt. based on 100 pts.wt. of the pigment, the resin contains a water-dispersible urethane-based resin, a polyurethaneurea part is contained in a weight ratio of ≤2.0 wt% in the urethane-based resin, and the pigment in the recording liquid has a dispersed particle diameter (D50) of 40-100 nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pigment-dispersed aqueous recording liquid, and more particularly, to a pigment-dispersed aqueous recording liquid and a printed matter which are particularly suitable for an ink-jet recording liquid or a writing instrument recording liquid.

  Ink jet recording has been used as a printing method for photographic digital images because of its high resolution. Most of photographic ink jet recording used for home and office use is a special paper or film made by coating an aqueous recording liquid using a dye as a colorant with a resin or inorganic material using an ink jet method. (Both are called exclusive paper). Dyes have been used for a long time as coloring materials for ink jet recording liquids because they hardly harden during long-term storage of the recording liquid and hardly clog nozzles of ink jet printers. In addition, since the dye dyes the coat layer of the ink jet dedicated paper relatively uniformly, it can be colored without deteriorating the glossiness due to the smoothness of the coat layer, and a glossy printed material can be obtained.

However, an ink jet print using an aqueous recording liquid using a dye as a coloring material is inferior in water resistance, weather resistance, and light resistance.
For this reason, attempts have been made to improve the water resistance, weather resistance and light resistance of printed matter by using a pigment as a coloring material having excellent water resistance, weather resistance and light resistance as an improvement in the ink jet recording liquid. However, recording liquids using pigments have poor storage stability due to aggregation and sedimentation of the pigments, so-called storage stability, and are easily clogged with ink jet nozzles.

In addition, when it penetrates into the coating layer of the inkjet paper, the gloss is good, but the color developability is lower than that of the dye, and when it is solidified on the coating layer to form the pigment layer, the color is good but the gloss is high. There was a problem that did not come out. Attempts have also been made to increase the gloss by adding a water-soluble resin such as a styrene derivative (for example, Patent Documents 1 and 2). However, when such a water-soluble resin is added, the solid content is reduced. When the amount is increased, the viscosity is increased, the ejection becomes difficult, and the storage stability tends to be deteriorated.
Further, in order to solve such an increase in viscosity and storage stability, use of a urethane resin as a water-soluble resin has been proposed (for example, see Patent Documents 3 to 5). For example, in Patent Document 3, an ink jet having a specific functional group such as a carboxyl group and a urethane resin having a molecular weight of 5,000 or less is used to suppress clogging of a discharge nozzle and improve printing performance and scratch resistance. A recording liquid has been proposed.
Patent Document 4 proposes an intermediate transfer type ink jet recording liquid which exhibits excellent printing quality and abrasion resistance as an intermediate transfer type recording liquid by using a colloidal dispersion resin such as a urethane resin and a volatile alkali substance. Have been.
In Patent Document 5, as an ink-jet printing method, an aqueous recording liquid containing a urethane resin and having an acid value as high as 100 to 250 [mgKOH / g], which is obtained from a carboxylated diol and a polyisocyanate, is used. It is described. It has been proposed to form a high-density image without bleeding by using such a recording liquid.

JP-A-6-116,522 JP 2002-20673 A JP-A-6-279,718 JP-A-7-82,516 JP-A-10-168,151

  As described above, as a result of many attempts, an aqueous recording liquid in which a pigment is dispersed can satisfy the storage stability of the recording liquid, the difficulty of nozzle clogging, and the water resistance, weather resistance, and light resistance of a printed matter. ing. For example, in the case of a black recording liquid, HP51645A of Hewlett-Packard and BCI-3eBK of CANON, ICBK23 and ICMB23 of Seiko Epson, FPG-BK of Roland (these are model numbers) and the like are listed.

  However, with the technologies up to now represented by these recording liquids, photographic recording liquids that achieve the photographic blackness and glossiness of printed materials and that have high abrasion resistance on the printed surface, which are aimed at photographic quality paper, are not available. Not. That is, so-called paper for exclusive use of photographic quality, and paper for exclusive use of ink jet such as PM photographic paper, photo professional, and QP photographic paper are sold for the purpose of photographic blackness and glossiness. These are provided on at least one side of a print medium with an ink receiving layer composed of a porous layer having pores of nanometer scale or smaller, or an ink receiving layer formed by applying a swelling type polymer, and the surface of a photographic paper is provided. Although such a smoothness is imparted, the pigment-based ink has not been able to achieve a sufficient glossiness and blackness with respect to a photographic quality paper having an ink receiving layer on the surface thereof.

  The present invention satisfies the storage stability of the recording liquid in the aqueous recording liquid in which the pigment is dispersed, the difficulty of clogging of the nozzles, the water resistance of the printed matter, the weather resistance, the light resistance, and the surface such as photographic quality paper. It is an object of the present invention to provide a recording liquid which achieves both the photographic blackness and glossiness of a printed material, and the extremely high scratch resistance of the printed surface, which is aimed for a smooth medium.

The present inventors have intensively studied a water-soluble polymer added for the purpose of improving the abrasion resistance of a recording liquid, the glossiness of a printed matter, and the dispersion stability of a pigment. As a result, among the urethane-based resins, the use of a relatively high-purity resin having few hydrolyzable groups such as ester bonds and amide bonds, specifically having a small number of polyurethaneurea portions and having a molecular weight of more than 5000, is used. Even if this resin is used in a large amount with respect to the pigment (specifically, 60 parts by weight or more with respect to 100 parts by weight of the pigment) for improving the abrasion resistance, the increase in the viscosity of the aqueous dispersion is suppressed and the dispersion stability of the pigment is suppressed. Can be maintained.
Further, in such a pigment dispersion aqueous liquid using a urethane-based resin, when the dispersed particle diameter of the dispersed pigment is within a specific range, when a printed matter is formed on the recording material, the surface of the recording material Were found to be densely arranged, and the gloss and scratch resistance of the printed matter were significantly improved, thereby completing the present invention.

That is, the present invention
(1) A pigment-dispersed aqueous recording liquid containing at least a pigment and a resin, wherein the resin contains 60 to 200 parts by weight based on 100 parts by weight of the pigment, and the resin contains a water-dispersible urethane-based resin. A pigment-dispersed aqueous recording liquid, wherein the weight fraction of the polyurethane urea portion is 2.0% by weight or less, and the dispersed particle diameter D50 of the pigment in the recording liquid is 40 to 100 nm,
(2) The pigment-dispersed aqueous recording liquid according to the above (1), wherein the pigment contains carbon black having a DBP absorption of 30 ml / 100 g or more and 100 ml / 100 g or less as a pigment.
(3) The aqueous pigment-dispersed recording liquid according to the above (1) or (2), wherein the molecular weight of the urethane-based resin is more than 5,000 and not more than 100,000.
(4) The aqueous pigment-dispersed recording liquid according to any one of (1) to (3), wherein the acid value of the urethane resin as a free acid is from 20 mgKOH / g to 100 mgKOH / g.
(5) The resin as described in any of (1) to (4) above, wherein the resin contains, in addition to the water-dispersible urethane resin, a resin having an acid value as a free acid of 100 mgKOH / g or more. Pigment-dispersed aqueous recording liquid,

(6) When a printed matter is formed by attaching 14.5 mg of a pigment-dispersed aqueous recording liquid per square inch to the paper for exclusive use of photographic quality by ink jet printing by solid printing, the thickness of the printed matter is 20 nm or more, and the OD is 2 or more. The pigment-dispersed aqueous recording liquid according to any one of the above (1) to (5), wherein the 20 ° gloss value is 60 or more,
(7) The pigment-dispersed aqueous recording liquid according to any one of (1) to (6) above, wherein the pigment contains carbon black and a pigment other than carbon black.
(8) The pigment-dispersed aqueous recording liquid according to (7), wherein the pigment other than carbon black is a cyan pigment,
(9) A printed matter formed from the pigment-dispersed aqueous recording liquid according to any one of (1) to (8),
(10) The printed matter according to (9), wherein the pigment-dispersed aqueous recording liquid is ejected from an inkjet nozzle to form a recording material.

(11) The printed matter according to the above (9) or (10), wherein the printed matter formed by the pigment-dispersed aqueous recording liquid has a thickness of 20 nm or more, an OD of 2 or more, and a 20 ° gloss value of 60 or more.
(12) The printed matter according to any one of the above (9) to (11), wherein the arithmetic average roughness is 0.04 or less,
(13) The printed matter according to any one of the above (9) to (12), wherein the pigment-dispersed aqueous recording liquid contains at least carbon black, and the printed matter is a black printed matter.
(14) When a printed matter is formed by attaching 14.5 mg of a pigment-dispersed aqueous recording liquid per square inch to a paper dedicated to photographic quality by an ink jet printing method using a solid printing method, the printed matter has a thickness of 20 nm or more and an OD of 2 or more. ° pigment dispersion aqueous recording liquid characterized by a gloss value of 60 or more,
(15) The pigment-dispersed aqueous recording liquid according to (14), which comprises at least carbon black.
(16) A printed material formed by discharging a pigment-dispersed aqueous recording liquid from an ink jet nozzle onto a recording material, wherein the printed material has a thickness of 20 nm or more, an OD of 2 or more, and a 20 ° gloss value of 60 or more. Printed matter,
(17) The printed matter according to the above (16), wherein 14.5 mg or more of ink per square inch is adhered to a photographic quality paper.

Exists.

  According to the present invention described above, the aqueous recording liquid in which the pigment is dispersed satisfies the storage stability of the recording liquid, the difficulty of clogging of the nozzles, the water resistance of the printed matter, the weather resistance, and the light resistance, and is especially dedicated to photographic image quality. Even on paper, it is possible to provide a recording liquid that achieves both blackness and glossiness of a printed matter.

Hereinafter, the present invention will be described in detail.
First, the pigment used in the present invention will be described. The pigment that can be used in the present invention is not particularly limited, and may be either an organic pigment or an inorganic pigment. These specific examples are as follows.

  In the present invention, black pigments, particularly carbon black, are used as pigments having high performance such as blackness and gloss as pigments. The carbon black that can be used is not limited, and carbon blacks such as acetylene black, channel black, and furnace black can be used. Among them, channel black and furnace black have high blackness, and furnace black is particularly preferable.

  The DBP absorption of the carbon black is usually preferably 30 ml / 100 g or more and 100 ml / 100 g or less, particularly preferably 50 ml / 100 g or more and 80 ml / 100 g or less, from the viewpoint of print quality. If the DBP absorption is less than 30 ml / 100 g, dispersion is difficult, and if it is more than 100 ml / 100 g, the finally obtained dispersed particle diameter is large, and the gloss of the printed matter may be low. This is because carbon black having a large DBP absorption does not collapse more than the structure no matter how small it is because the structure is developed.

The volatile content of carbon black is usually 8% by weight or less, preferably 6% by weight or less. The pH is from 1 to 11, preferably from 3 to 10, and particularly preferably from 6 to 9, from the viewpoint of storage stability of the recording liquid. BET specific surface area is are 100 m ² / g or more, preferably 150~600m ² / g, especially 260~500m ² / g are preferred. When the specific surface area is small, the area for absorbing light is small, so that the blackness is reduced. When the specific surface area is large, the amount of the dispersant required for dispersion is large, so that it becomes difficult to discharge. The primary particle size is 30 nm or less, preferably 20 nm or less, more preferably 16 nm or less, and particularly preferably 15 nm or less.

  Here, the DBP absorption is a value measured by the JIS K6221A method, the volatile content is a value measured by the JIS K6221 method, and the primary particle diameter is an arithmetic average diameter (number average) by an electron microscope.

As the above carbon blacks, # 2650, # 2600, # 2300, # 2200, # 1000, # 980, # 970, # 966, # 960, # 950, # 900, # 850, MCF-88, # 55
# 52, # 47, # 45, # 45L, # 44, # 33, # 32, # 30 (Mitsubishi Chemical Corporation), Special Blaek4A, 550, Printex
95, 90, 85, 80, 75, 45, 40 (all made by Degussa), Regal660, Rmogul L, monarch1400, 1300, 1100, 800, 900 (all made by Cabot), Raven
Specific examples include 7000, 5750, 5250, 3500, 3500, 2500 ULTRA, 2000, 1500, 1255, 1200, 1190 ULTRA, 1170, 1100 ULTRA, Raven5000UIII, (all manufactured by Columbian), and the like.

Specific examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, and 128.
, 129, 151, 154 and the like.

Further, as specific examples of the magenta pigment, CI Pigment Red 5, 7, 12, 48 (Ca), CI48 (Mn), 57 (Ca), 57: 1, 112
, 123, 168, 184, 202 and the like.
Specific examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15: 3 and 15:
4, 16, 22, 60, 4, 60 and the like.

In addition to the above, CI Pigment Red 209, 122, 224, 177, 194, CI Pigment Orange 43, CI Pigment Violet 19, 23, 37, CI Pigment Green 36, 7
CI Pigment Blue 15: 6, 209 and the like can also be used.

Further, the pigment used in the present invention is not limited to one, and some of the above-mentioned pigments may be used in combination.
When the present invention is used for a black pigment-dispersed aqueous recording liquid, particularly excellent performance can be obtained. As the black pigment-dispersed aqueous recording liquid, it is particularly preferable to use carbon black among the above-mentioned pigments. Further, by using carbon black in combination with the above-mentioned other pigments, it is possible to obtain a black print having a preferable bluish color. As the pigment to be combined, a cyan pigment is preferable, and CI Pigment Blue 15: 3 is more preferable.

  As the pigment used in the pigment-dispersed aqueous recording liquid of the present invention (hereinafter sometimes simply referred to as “recording liquid”), those obtained by chemically treating the above pigment (oxidation treatment, fluorination treatment) And the like, and those in which a dispersant, a surfactant, and the like are physically or chemically bonded (grafting treatment, a dispersant that has been adsorbed in advance before dispersion), and the like may be used. Specific examples of such a product include Cab-o-jet 200 or Cab-o-jet 300 (products of Cabot Corporation).

Next, the urethane resin used in the present invention will be described.
Here, the urethane-based resin refers to a polymer mainly composed of a polyurethane skeleton in which a main chain is connected with urethane bonds, and includes a so-called urethane resin.
In the present invention, a water-dispersible urethane resin is particularly used among the urethane resins. Such a water-dispersible urethane resin is obtained by introducing a hydrophilic component necessary for stable dispersion in water into the main chain of the polyurethane skeleton, or dispersing the polyurethane with an external emulsifier. Although a body is generally used, a self-dispersion type (self-emulsification type) in which a hydrophilic component is introduced into the main chain is more preferable. It may be in any form such as colloidal dispersion, emulsion, suspension, and slurry.

  As the urethane resin used in the present invention, a diisocyanate compound, a polyether diol, a polyester diol, a diol compound such as a polycarbonate diol, and a carboxylic acid group, an acid group-containing diol such as a sulfonic acid group are reacted. The various water-dispersible urethane resins (ester urethane resins, ether urethane resins, carbonate urethane resins, etc.) obtained by the above method are suitable.

  Examples of the diisocyanate include aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, 1,4-cyclohexane diisocyanate, and 4,4′- Alicyclic diisocyanate compounds such as dicyclohexylmethane diisocyanate, aromatic aliphatic diisocyanate compounds such as xylylene diisocyanate and tetramethyl xylene diisocyanate, aromatic diisocyanate compounds such as toluylene diisocyanate and phenylmethane diisocyanate, and modified products of these diisocyanates (carbodiimide, uretdione And uretoimine-containing denatured products).

  Examples of the diol compound include polyether diols such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyethylene adipate, polybutylene adipate, polyneopentyl adipate, and poly-3-methylpentyl. Examples include polyester diols such as adipate, polyethylene / butylene adipate, polyneopentyl / hexyl adipate, polylactone diols such as polycaprolactone diol, and polycarbonate diols. From the viewpoint of storage stability of the ink, a polyether-based, polyester-based, or polycarbonate-based diol compound is preferable, a polyether-based or polycarbonate-based compound is more preferable, and a polyether-based compound is more preferable. Polyether-based and polycarbonate-based materials are less likely to be degraded by hydrolysis in water, and thus have good storage stability.

  Examples of the acid group-containing diol include dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, and dimethylolbutyric acid. Particularly, dimethylolbutanoic acid is preferable.

  As a method for synthesizing a urethane-based resin, an isocyanate-terminated prepolymer is synthesized in a low-boiling solvent (such as acetone) that does not react with isocyanate groups, a hydrophilic group is introduced with a diamine, a polyol, or the like, and then diluted with water and phase-changed. , A solvent method in which a solvent is distilled off to obtain a polyurethane dispersion, a prepolymer method in which a isocyanate group-terminated prepolymer having a hydrophilic group introduced therein is first synthesized, dispersed in water, and then chain-extended with an amine, and other hot melt methods A method of using a water as a chain extender in a urethane prepolymer in an aqueous solution of an emulsifier, a step of sulfonating an aromatic ring of a urethane prepolymer having a free isocyanate group obtained from a hydrophobic polyol and an aromatic polyisocyanate. Various methods are known, such as the method using That is, the present invention is not particularly limited.

  In particular, the urethane resin may be synthesized by a prepolymer method, and in that case, a low molecular weight polyhydroxy compound may be used. Examples of the low molecular weight polyhydroxy compound include glycol and alkylene oxide low-mol adducts mentioned above as raw materials for the above-mentioned polyester diols, trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane, and alkylene oxide low-mol adducts thereof. Is mentioned.

  In the case of an aqueous urethane resin, a method of phase inversion and emulsification of a urethane prepolymer prepared in an organic solvent phase and further extending the chain in an aqueous phase is generally known. Polyamines such as diamines are generally used as chain extenders in this case. Specifically, the urethane prepolymer undergoes water extension or di- or triamine extension after or while neutralizing acid groups derived from dimethylolalkanoic acid. As the polyamines used as a chain extender at the time of amine extension, diamines or triamines are usually mentioned. Specific examples thereof include hexamethylenediamine, isophoronediamine, hydrazine, piperazine and the like.

  However, it was found that when a urethane resin using a polyamine as a chain extender was used, the storage stability of the recording liquid tended to be poor. This is because the amine-extended urethane resin (polyurethane resin containing a polyurethane urea portion) is easily hydrolyzed, and the polyamines generated by the hydrolysis also act as a flocculant in the pigment dispersion recording liquid. It is presumed that it is having a bad effect.

One of the features of the present invention is to use, as the urethane-based resin, one in which the weight fraction of the polyurethane urea portion in the urethane-based resin is 2.0% by weight or less. By using such a specific urethane-based resin and allowing the resin to be present at a specific ratio with respect to the pigment, and by setting the dispersed particle size of the pigment to a specific range as described later, the stability of the system is extremely high. It maintains excellent physical properties as an inkjet recording liquid that is ejected and printed under severe conditions, and improves the stability of pigment dispersion especially when drying the surface of photographic quality paper. Prevention) and the glossiness of the resin as a polymer mainly composed of the urethane resin, and the glossiness in the ink receiving layer on the surface of paper dedicated to photographic image quality due to the uniform presence of the pigment in the film due to the film forming property It is thought that it contributes to both improvement and blackness. It is presumed that the pigment is dispersed in a state capable of exhibiting high optical performance and is stably maintained without being disturbed, and at the same time, the urethane resin itself contributes to the improvement in gloss.
The weight fraction of the polyurethane urea portion in the urethane resin is 2.0% by weight or less, preferably 1.8% by weight or less, particularly preferably 1.5% by weight or less, and further preferably 1.0% by weight or less. Is more preferably not substantially contained.
In order to obtain such a urethane-based resin, a urethane-based resin having a high molecular weight may be obtained by a conventionally known method without using a chain extender such as polyamine. It is preferred that the production of the urethane resin is performed under substantially anhydrous conditions. This is to prevent the polyisocyanate compound, which is a raw material of the urethane-based resin, from reacting with moisture to form a polyamine and form a polyurethaneurea portion.
The weight fraction of the polyurethane urea portion in the urethane-based resin, that is, the chain fraction of the chain-extended portion such as diamines introduced by amine extension is determined, for example, from the weight ratio of the polyamines in the raw materials used for producing the polyurethane-based resin used in the present invention. You can ask. Specifically, the ratio can be determined by dividing the weight of the polyamines by the weight of all the raw materials used for producing the urethane-based resin.

  Conventionally, when a pigment-based ink is used for photographic quality paper having a glossy surface on the surface, it is considered that the gloss has been reduced by riding on the glossy surface in a state where fine aggregation of the pigment has occurred. Thus, it is presumed that aggregation of the pigment is suppressed and a good dispersion state is maintained on the surface of the recording material, which leads to both improvement in gloss and blackness.

  In the present invention, as the urethane-based resin, a polyether-based urethane resin is particularly preferable from the viewpoints of ink stability and gloss of printed matter.

  The urethane-based resin can be used in the form of an alkali metal salt such as Li, Na, and K, and an organic amine salt such as ammonia, dimethylamine, and (mono, di, tri) ethanolamine. These can be obtained by further neutralizing the urethane-based resin obtained by the method described above. The base used in the neutralization can be appropriately selected according to the counter ion of the desired salt and the like, for example, butylamine, alkylamines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine and the like. Inorganic bases such as alkanolamine, morpholine, ammonia, sodium hydroxide and the like can be mentioned.

  The acid value of the free acid of the urethane resin used in the present invention is preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g, from the viewpoint of further improving the storage stability and ejection stability of the recording liquid. g or more, more preferably 50 mgKOH / g or more, even more preferably 60 mgKOH / g or more.

The upper limit of the acid value is 200 mgKOH / g or less, preferably 100 mgKOH / g or less, more preferably 85 mgKOH / g or less, and particularly preferably 70 mgKOH / g or less. If the lower limit of the acid value is lower than 15 mgKOH / g, water solubility will be lost, and if it is higher than 200 mgKOH / g, there will be problems such as abrasion resistance of the coating film, lower water resistance, excessively high viscosity, and poor discharge. Points may occur. Further, the weight-average molecular weight of the polymer is from the viewpoint of discharge stability, and the weight-average molecular weight of the polymer is, from the viewpoint of discharge stability, usually 300,000 or less, further 100,000 or less, among which It is preferably 50,000 or less, particularly preferably 30,000 or less. The lower limit is usually more than 5000, more preferably 8000 or more, especially 10,000 or more, and particularly preferably 12,000 or more. The higher the molecular weight, the higher the viscosity, which makes it difficult to discharge.
On the other hand, when it is 5000 or less, the urethane resin tends to be water-soluble, and the gloss-imparting effect is reduced. Liquid stability also tends to be low.

In addition, it is preferable to use other various water-soluble resins together with the urethane-based resin. Representative examples of such a water-soluble resin include an anionic water-soluble polymer.
From the viewpoint of storage stability of the recording liquid, the anionic water-soluble polymer generally has an acid value in the form of a free acid of 40 mgKOH / g or more, preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, and still more. Preferably, the amount is at least 150 mgKOH / g. If the acid value is less than 40 mgKOH / g, the electrostatic repulsion resulting from the functional group of the resin adsorbed on the pigment becomes small, and the dispersion and dispersion stability deteriorate. Further, a copolymer having a hydrophobic group is preferable in view of dispersion stability of carbon black, water resistance of printed matter, and abrasion resistance.

  Examples of the hydrophobic group in the polymer include an organic group having an aromatic ring such as a phenyl group, a benzyl group and a naphthyl group which may be substituted, an alkyl having 4 or more carbon atoms and which may be branched or substituted. Examples thereof include a group, an alkenyl group, an alkynyl group, and a cycloalkyl group. Among them, an organic group having an aromatic ring is preferable.

  As the anionic water-soluble polymer used in the present invention, specifically, (α-methyl) styrene / maleic acid copolymer, (α-methyl) styrene / (meth) acrylic acid copolymer, (α -Methyl) styrene / (meth) acrylate / (meth) acrylic acid copolymer, (meth) acrylate / (meth) acrylic acid copolymer, (meth) acrylic acid ester / maleic acid copolymer and And / or salts thereof, preferably (α-methyl) styrene / (meth) acrylic acid copolymer. Here, (α-methyl) styrene refers to α-methylstyrene and / or styrene, and (meth) acrylic acid refers to methacrylic acid and / or acrylic acid.

  The anionic water-soluble polymer used here may be any of a block polymer, a graft polymer, and a random polymer, but is preferably a graft polymer or a random polymer, particularly preferably a random polymer, mainly from the viewpoint of production cost. The weight average molecular weight is preferably 50,000 or less, more preferably 15,000 or less, and particularly preferably 10,000 or less, from the viewpoint of ejection stability. As the molecular weight increases, the viscosity increases, and the ejection properties deteriorate. Further, a copolymer having an acid value of 150 mgKOH / g or more is used in the form of alkali metal salts such as Li, Na, and K, and organic amine salts such as ammonia, dimethylamine, and (mono, di, tri) ethanolamine. it can.

  Commercial products of the above-mentioned polymer or polymer solution include “Johncryl 67”, “679”, “680”, “682”, “683”, “690” manufactured by Johnson Polymer and / or Salt, "Jonkrill 52", "57", "60", "62", "63", "70", "354", "501", "6610" and the like.

  As the medium of the recording liquid of the present invention, an aqueous medium mainly composed of water is usually used. In this case, it is preferable to use a water-soluble organic solvent added to water.

The above water-soluble organic solvents are roughly classified into those that function as humectants and those that function as penetrating solvents.
Specifically, examples of the former include ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, triethylene glycol, and polyethylene glycol (specific examples: “# 200”, “# 300”, “# 300” manufactured by Wako Pure Chemical Industries, Ltd.) # 400 ","# 4000 ","# 6000 "), glycerin, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolinone, thiodiglycol, sulfolane, dimethylsulfoxide, neopentyl alcohol, Trimethylolpropane, 2,2-dimethylpropanol and the like.

Specific examples of the penetration solvent (penetration aid) include ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol monoisopropyl ether, and ethylene glycol. Mono-n-butyl ether, ethylene glycol mono-sec-butyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-tert-butyl ether, ethylene glycol mono-n-amyl ether, ethylene glycol mono-n-hexyl ether, propylene glycol monomethyl ether , Propylene glycol dimethyl ether, propylene glycol monoethyl ether Propylene glycol diethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-sec-butyl ether, propylene glycol monoisobutyl ether, propylene glycol mono-tert-butyl ether, Diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-sec-butyl ether, diethylene glycol monoisobutyrate Ether, diethylene glycol mono-tert-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, triethylene glycol mono-n-butyl ether, polyethylene glycol monopropyl ether, polyethylene glycol mono Butyl ether and ethylene glycol adducts of glycerin (specific examples: Liponic EG-1 (manufactured by Lipo Chemical Co., Ltd.)) and the like.
These organic solvents can be used alone or in combination of two or more.

  Further, in order to increase the permeability of the recording liquid, various surfactants can be used in the recording liquid according to the present invention. For example, various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants and the like can be mentioned.

  Nonionic surfactants include fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl sulfates , Polyoxyethylene alkylaryl sulfates, alkane sulfonates, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphates, N-methyl-N-oleoyl taurate, α-olefin sulfonates And the like.

  The nonionic surfactant is not particularly limited, but preferably has an ethylene oxide structure or a propylene oxide structure from the viewpoint of storage stability and print density, and among them, those having an HLB of 9 to 17, especially 10 to 16 Is more preferred.

  Specific examples of the nonionic surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, Polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkylamine, aminopolyoxyethylene, sorbitan fatty acid ester, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan stearate, polyoxy Ethylene sorbitan oleate, naphthol ethylene oxide adduct, acetylene glycol ethylene oxide addition , Bisphenol A ethylene oxide adduct, oxyethylene oxypropylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, α- Olefin sulfonate and the like. Commercially available nonionic surfactants can also be used, including Surfynol 440, Surfynol 465, Surfynol 485 (all manufactured by Air Products), acetylenol EH, and acetylenol EL (all manufactured by Kawaken Fine Chemical). No.

  On the other hand, examples of the cationic surfactant and the amphoteric surfactant include alkylamine salts, quaternary ammonium salts, alkylbetaines, and aminooxides.

The amount of the low molecular weight nonionic surfactant to be used is generally 0.1 to 3 parts by weight, preferably 0.5 to 1 part by weight, per 100 parts by weight of the recording liquid. The surface tension of the recording liquid is appropriately controlled by the type and amount of the low molecular weight nonionic surfactant, and the surface tension of the recording liquid of the present invention is preferably 25 dyne / cm or more and 54 dyne / cm or less. If the surface tension is greater than 54 dyne / cm, when printing is performed as a recording liquid, the penetration of the recording liquid into the recording material is slowed, resulting in a disadvantage that the printing speed must be reduced. Further, when the surface tension of the recording liquid is less than 25 dyne / cm, the penetration of the recording liquid into the recording medium becomes too large, and the print density is impaired.
As a specific example of the composition of the recording liquid, for example, as described in JP-A-2001-302,950, a surfactant having an acetylene bond is contained to provide excellent continuous ejection stability and penetration into a recording medium. It can be an ink composition which requires the property. Here, a propylene oxide adduct of a lower alcohol can be added and used in combination. Further, a specific compound having an acetylene bond, 1,5-pentanediol, and a butyl ether-based solvent described in JP-A-2000-3,760 can also be contained.
Further, as described in JP-A-2000-30,237, as an ink composition having excellent color reproducibility, high permeability and short drying time, an acetylene glycol-based surfactant and / or a polysiloxane-based interface can be used. An ink composition containing an alkyl ether derivative of a polyhydric alcohol having 3 or more (preferably 3 or more and 6 or less) carbon atoms as an activator and an organic solvent, and / or a 1,2-alkanediol can also be used. .

  In addition to the above components, a fungicide, a bactericide, a pH adjuster, urea, and the like may be added to the recording liquid of the present invention as needed. In particular, alkanolamines such as diethanolamine and triethanolamine are preferred as pH adjusters, dissolution aids and antioxidants.

  The method for obtaining the recording liquid of the present invention is not particularly limited, but according to a known method, the pigment is subjected to a dispersion treatment in the presence of the necessary water-soluble resin and the necessary additive component in a medium to obtain a high concentration. A method of preparing a recording liquid by adding the urethane-based resin and the above-mentioned necessary additional components and medium to the obtained dispersion liquid to adjust the concentration (master batch method) or In general, a recording liquid is prepared by subjecting the pigment to a dispersion treatment in a medium in the presence of each of the resin components and the necessary additional components. The above-mentioned master batch method is efficient in that the dispersion treatment is performed at a high concentration and the particle size is adjusted to a desired dispersion particle size.

  Examples of the dispersing machine used for the dispersing process include a dispersing machine using a medium and a medialess dispersing machine. Examples of the dispersing machine using the media include a ball mill, a sand mill, a dyno mill, and a DCP mill. Examples of the media-less disperser include a roll mill and an ultrasonic disperser, and these and other known dispersers may be used.

  In the present invention, it is preferable to remove coarse particles by a filter or a centrifugal separator after the above-mentioned grinding and dispersion treatment by the disperser.

  The amount of the pigment used is preferably in the range of 0.1 to 10% by weight, preferably 0.2 to 5% by weight, and more preferably 1 to 4% by weight based on the total weight of the recording liquid. If the amount is less than 0.1% by weight, coloring becomes poor, and if it is more than 10% by weight, the viscosity becomes high and the gloss becomes poor. The amount of the water-soluble resin (here, other than the specific urethane resin which is an essential component of the present invention, typically refers to the above-mentioned water-soluble anionic polymer) is used with respect to 100 parts by weight of the pigment. It is preferably used in the range of 5 to 100 parts by weight in terms of solid content, particularly preferably 10 to 50% by weight.

  The amount of the urethane resin used is preferably in the range of 60 to 200 parts by weight, and particularly preferably 70 to 150 parts by weight, in terms of solid content based on 100 parts by weight of the pigment. The total amount of these resins is 60 to 200 parts by weight in terms of solid content based on 100 parts by weight of the pigment. Preferably it is 70 to 150 parts by weight. If the amount of the resin is small, the stability of the recording liquid is poor, and if the amount of the resin is large, the viscosity is high, so that the ejection is poor and the gloss of the obtained printed matter is poor. Therefore, the above range is an appropriate range. The amount of the water-soluble organic solvent used in the above recording liquid is in the range of 5 to 30% by weight, preferably 5 to 20% by weight in terms of storage stability, and particularly preferably 8 to 20% by weight.

Each of these pigments, resins, additives, and organic solvents may be used alone, but in some cases, two or more of them may be used in combination to further improve the physical properties.
The average dispersed particle size of the pigment in the recording liquid is preferably adjusted to a range of 40 to 100 nm from the viewpoints of dispersion stability, ejection stability, and print quality, but is more preferably 50 to 85 nm. Further, the maximum dispersed particle diameter of the pigment is preferably 5 μm or less from the viewpoint of dispersion stability and discharge stability, and more preferably 1 μm or less.

  In the present invention, the average dispersion particle size and the particle size distribution of the pigment in the recording liquid are measured by a light scattering particle size analyzer (“Microtrack UPA150” manufactured by Nikkiso Co., Ltd.). (Indicating that 50% of the particles have a size smaller than this particle size) is defined as the value of the average dispersed particle size of the recording liquid. The maximum dispersed particle size is a value of the smallest particle size among particle sizes in which no dispersed particles having a larger size exist.

  The recording liquid of the present invention can be used not only for ink jet and writing instruments but also for other purposes. The recording liquid of the present invention is particularly suitable for inkjet recording, that is, for use in a method of forming (printing) a printed material on a recording material by discharging from an inkjet nozzle.

  Recording materials are roughly classified into plain paper having a single layer structure composed of cellulose, filler, sizing agent, and the like, and special paper having a multilayer structure having an ink receiving layer provided on at least one side of a support. The recording liquid can be used for all recording materials (plain paper, recycled paper, inkjet-only paper (coated paper, glossy paper, etc.), inkjet-only film (coating film, glossy film, etc.), OHP film, etc.). Especially, it has an ink receiving layer consisting of a porous layer of nanometer scale or smaller, or an ink receiving layer formed by applying a swelling type polymer, on at least one side of the print medium, which has been developed especially for obtaining photographic image quality. Even when used on a recording material (paper for exclusive use of photographic quality), printing with high gloss and OD value is possible.

  In the case of printing by such an ink-jet method on such photographic-quality paper, as a photographic print, it is preferable that the 20 ° gloss is 60 or more in order to give a glossy photographic-like gloss by visual judgment. It is preferably at least 65, particularly preferably at least 70. The printed matter giving such glossiness preferably has an arithmetic average roughness Ra of 0.04 μm or less, particularly preferably 0.03 μm or less. Further, in order to obtain a clear image with high contrast, the print density (OD) of the printed matter is preferably 2 or more, more preferably 2.2 or more, and particularly preferably 2.3 or more. Further, in order to achieve such a high OD, the printed film thickness is preferably 20 nm or more, more preferably 100 nm or more, further preferably 150 nm or more, particularly preferably 200 nm or more. Is preferred. On the other hand, it has been found that when the print film thickness is too large, the gloss of the printed surface tends to decrease. Desirably, the printed film thickness is 300 nm or less, particularly 250 nm or less. In particular, it is desirable that a printed matter obtained by attaching 14.5 mg or more of ink per square inch by solid printing satisfies these conditions.

Further, as a recording liquid for providing such a photographic print, when 14.5 mg of ink per square inch is applied by solid printing to photographic quality paper, the print film thickness of the print is 20 nm or more and the OD is A recording liquid having 2.0 or more and 60 ° gloss of 60 or more is preferable.
Further, a recording liquid having a printed film thickness of 100 nm or more is more preferable, a recording liquid having a thickness of 150 nm or more is more preferable, and a recording liquid having a thickness of 200 nm or more is particularly preferable. Further, a recording liquid having a printed film thickness of 300 nm or less, particularly 250 nm or less is preferable, and a recording liquid having a printed film thickness of 100 to 300 nm, particularly 150 to 200 nm, is most preferable. Further, a recording liquid having an OD of 2.2 or more is more preferable, and a recording liquid having a OD of 2.3 or more is particularly preferable. Further, a recording liquid having a gloss of 20 ° or more of 65 or more in the printed matter is more preferable, and a recording liquid of 70 or more is particularly preferable. Further, a recording liquid having an arithmetic average roughness Ra of the printed surface of 0.04 μm or less, particularly 0.03 μm or less is preferable.

In the present specification, the photographic quality exclusive paper refers to a PM photographic paper manufactured by Seiko Epson KK, and specifically refers to a printed material having a blank of 20 ° gloss of 15 or more.
To attach 14.5 mg of ink per square inch in solid printing, for example, fill the ink into a printer MJ8000C manufactured by Seiko Epson Corporation and select “Super Fine Mode” (see “Basic” in the printer properties). In “Setting”, “Mode setting” is “Recommended setting” and “Paper type” is “Super fine exclusive paper”.), And solid printing is performed.

  Hereinafter, the present invention will be described more specifically with reference to examples. “Parts” and “%” are based on weight unless otherwise specified. The physical properties of the carbon black used are as shown in Table 1 below, and the methods of evaluating the obtained dispersion and printed matter and measuring the physical properties are as described in (1) to (9) below.

(1) Dispersion Particle Size Distribution Measurement The dispersion or recording liquid was diluted with ion-exchanged water, and the particle size distribution was measured using a particle size distribution meter (“Microtrack UPA150” manufactured by Nikkiso Co., Ltd.). The value of D50 (indicating that 50% of the particles have a size smaller than this particle size) in the particle size distribution is defined as the average dispersed particle size.

(2) Viscosity measurement
The viscosity of the recording liquid was measured at 25 ° C. using an E-type viscometer.

(3) Storage stability test The recording liquid is placed in a glass sample bottle, kept at 70 ° C. for 1 week in a sealed stopper, and then the dispersion particle size distribution is measured. The difference between the D50 values before and after holding at 70 ° C for one week is defined as the difference.
○ Absolute value of difference of D50 value before and after holding at 70 ° C for 1 week is 2nm or less △ Absolute value of difference of D50 value before and after holding at 70 ° C for 1 week is more than 2nm and 6nm or less × D50 before and after holding at 70 ° C for 1 week The absolute value of the difference between the values is greater than 6 nm

(4) Printing test Fill the recording liquid into the cartridge of the inkjet printer MJ8000C manufactured by Seiko Epson Corp., and print solid on the glossy paper (PM photo paper) for exclusive use of inkjet printer photographic quality in "Super Fine Mode". The evaluation was based on the following criteria.
良好 A good printed matter with no print omission and no blur was obtained.
Δ: There is slight printing omission, but there is no practical problem.
× Printout is remarkable.

(5) Print Density Measurement The density (OD) of the printed matter obtained in the above print test was measured using a Macbeth densitometer (RD914). The higher the value, the better the print density, and a pass of 2 or more was considered acceptable.

(6) Gloss measurement The gloss at 20 ° of the printed matter obtained in the above printing test was measured using a gloss meter (“Micro Tri-Gloss” manufactured by Big Gardner Co., Ltd.). A larger value indicates better gloss, and a value of 60 or more was judged to be acceptable.

(7) Printed film thickness measurement and printed surface roughness (Ra) measurement Droplet was measured at an observation magnification of 2000 times using “Ultra Deep Shape Measurement Microscope VK-8500” manufactured by Keyence Corporation. And surface roughness were measured.

(8) Visual Photographic Judgment The degree of phototone of the printed matter obtained in the above printing test was visually judged according to the following four-step criteria.
○ It is glossy and dark.
△ Glossy but not black.
× Black but not glossy.
XX Not black or shiny.

(9) Water Resistance Test The printed matter obtained in the above printing test was immersed in ion-exchanged water at 25 ° C. for 1 minute, and it was confirmed whether or not bleeding occurred.
○ There is no bleeding.
× There is bleeding.

(Synthesis of urethane resin)
(1) Synthesis of urethane resins (A) to (C) (i) Synthesis of urethane prepolymer
Urethane resins (A) to (C) were synthesized by the following method. The components shown in Table 2 were reacted in an acetone solvent under a stream of N ₂ to obtain a urethane prepolymer.

(Ii) Synthesis of Water-Based Polyurethane Emulsion The urethane prepolymer was dropped and dispersed in deionized water containing 12 parts of triethylamine, and subjected to vacuum deacetone to obtain a polyurethane emulsion. Table 2 shows the solid content, weight average molecular weight (Mw), and acid value of the obtained polyurethane emulsion.
The weight average molecular weight is a value measured by GPC in terms of polystyrene, and the acid value is DIN.
According to 53402.

(2) Synthesis of urethane resin (D) A urethane resin (D) was synthesized by the following method. Polyester polyols composed of neopentyl glycol, 1,6-hexanediol, adipic acid, dimethylolbutanoic acid, IPDI and TMXDI were prepared using the above-mentioned “(1) urethane resin (A)-( In the "Synthesis of C)", a urethane prepolymer was obtained in the same manner as in "(i) Synthesis of urethane prepolymer". The urethane prepolymer was dispersed in deionized water containing 8 parts of triethylamine, and 2.4 parts of 2-[(2-aminoethyl) amino] ethanol was added dropwise and dispersed. Got. Table 2 shows the solid content, weight average molecular weight (Mw), and acid value of the obtained polyurethane emulsion.

(Example 1)
Each component shown in the following Table 3 was dispersed with a bead mill disperser using zirconia beads having a diameter of 0.8 mm, the particle size distribution was monitored, and the particles were dispersed until the average dispersed particle diameter became 61.9 nm. Separated and filtered through a 5 μm filter to remove coarse particles to obtain a carbon black dispersion.

（なお「プロキセルGXL S」はアビシア社製の防腐剤である。）

("Proxel GXL S" is a preservative manufactured by Avicia.)

To this carbon black dispersion, 26 parts by weight of the 30% by weight ether-based urethane-based resin (A) obtained in [Synthesis of urethane-based resin] was added and mixed, and then 32.5 parts of triethylene glycol monobutyl ether and 32.5 parts of glycerin were added. 3.25 parts of "Surfinol 465" (trade name, manufactured by Air Products) and 130.75 parts of ion-exchanged water were added to obtain a recording liquid. The average dispersion particle size of the recording liquid is 67 nm and the viscosity is 4.05
mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

(Example 2)
Each component shown in the following Table-4 was dispersed with a bead mill disperser using zirconia beads of 0.8 mm, the particle size distribution was monitored and dispersed until the average dispersed particle size became 59.8 nm, and then centrifuged. Separated and filtered through a 5 μm filter to remove coarse particles to obtain a carbon black dispersion.

To this carbon black dispersion, 34.67 parts of the 30% by weight ether-based urethane-based resin (A) obtained in [Synthesis of urethane-based resin] was added and mixed, and then 32.5 parts of triethylene glycol monobutyl ether and glycerin were added. 32.5 parts, 3.25 parts of "Surfinol 465", and 122.08 parts of ion-exchanged water were added to prepare a recording liquid. The average dispersion particle size of the recording liquid is 60 nm, and the viscosity is 4.63.
mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

(Example 3)
A carbon black dispersion was obtained in the same manner as in Example 2.
Separately, each component shown in the following Table 5 was dispersed using a bead mill disperser using zirconia beads having a diameter of 0.8 mm, the particle diameter distribution was monitored, and the particles were dispersed until the average dispersed particle diameter became 81 nm. The resulting mixture was filtered through a 5 μm filter to remove coarse particles to obtain a cyan pigment dispersion.

The above carbon black dispersion and the cyan pigment dispersion are mixed, and 34.7 parts of a 30% by weight ether-based urethane-based resin (B) obtained in [Synthesis of urethane-based resin] is added and mixed. 36.52 parts of triethylene glycol monobutyl ether, 36.52 parts of glycerin, 3.65 parts of "Surfinol 465", and 141.49 parts of ion-exchanged water were added to prepare a recording liquid. The average dispersion particle size of the recording liquid is 78 nm, and the viscosity is 4.30.
mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

(Example 4)
The same operation as in Example 2 was performed, except that “# 45” manufactured by Mitsubishi Chemical Corporation was used instead of “carbon black (A)” as the carbon black, to obtain a carbon black dispersion.
After mixing this carbon black dispersion with the cyan pigment dispersion obtained in Example 3, 43.35 parts of the 30% by weight ester-based urethane-based resin (C) obtained in [Synthesis of polyurethane-based resin] was added. After mixing, 36.52 parts of triethylene glycol monobutyl ether, 36.52 parts of glycerin, 3.65 parts of "Surfinol 465", and 132.8 parts of ion-exchanged water were further added to obtain a recording liquid. The average dispersion particle diameter of the recording liquid is 80 nm, and the viscosity is 4.25.
mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

(Example 5)
The same operation as in Example 2 was performed except that “MCF88” manufactured by Mitsubishi Chemical Corporation was used instead of “carbon black (A)” as carbon black, to obtain a carbon black dispersion.
After mixing this carbon black dispersion and the cyan pigment dispersion obtained in Example 3, 43.35 parts of the 30% by weight ester-based urethane-based resin (C) obtained in [Synthesis of urethane-based resin] was added. After mixing, 36.52 parts of triethylene glycol monobutyl ether, 36.52 parts of glycerin, 3.65 parts of "Surfinol 465", and 132.8 parts of ion-exchanged water were added to obtain a recording liquid. The average dispersion particle diameter of the recording liquid was 72 nm, and the viscosity was 4.10 mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

(Comparative Example 1)
26 parts of the 30% by weight ester-based urethane-based resin (D) obtained in [Synthesis of urethane-based resin] was added to the carbon black dispersion obtained by the same operation as in Example 5 and mixed. A recording liquid was prepared by adding 32.5 parts of ethylene glycol monobutyl ether, 32.5 parts of glycerin, 3.25 parts of "Surfinol 465", and 130.75 parts of ion-exchanged water. The average dispersion particle size of the recording liquid is 60 nm and the viscosity is 3.08
mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

(Comparative Example 2)
After mixing the carbon black dispersion obtained in the same manner as in Example 5 with the cyan pigment dispersion obtained in Example 3, the 30% by weight urethane resin (C) obtained in [Synthesis of urethane resin] was obtained. ) Was added and mixed, and then 36.52 parts of triethylene glycol monobutyl ether, 36.52 parts of glycerin, 3.65 parts of "Surfinol 465", and 158.91 parts of ion-exchanged water were added. A recording liquid was used. The average dispersion particle diameter of the recording liquid was 81 nm, and the viscosity was 5.18 mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

[Comparative Example 3]
The genuine ink HP51645A was set with an inkjet printer DJ970Cxi manufactured by Hewlett-Packard Co., Ltd., and solid printing was performed in a normal mode on paper dedicated to an inkjet printer (PM photo paper), and evaluated by the above method. The evaluation results are shown in Table-6.

[Comparative Example 4]
The genuine ink BCI-3eBK was set with an ink jet printer BJ610F manufactured by Canon Inc., and solid printing was performed in a normal mode on ink jet printer paper (PM photographic paper), and evaluated by the above method. The evaluation results are shown in Table-6.

[Comparative Example 5]
8.67 parts of the 30% by weight ester-based urethane-based resin (C) obtained in [Synthesis of urethane-based resin] was added to the carbon black dispersion obtained in Example 2 and mixed, and then triethylene glycol monobutyl ether was added. 32.5 parts, 32.5 parts of glycerin, 3.25 parts of “Surfinol 465” and 148.08 parts of ion-exchanged water were added to prepare a recording liquid. The average dispersion particle diameter of the recording liquid is 47 nm, and the viscosity is 3.40.
mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

[Comparative Example 6]
A carbon black dispersion was obtained in the same manner as in Example 5.
After mixing this carbon black dispersion and the cyan pigment dispersion obtained in Example 3, 8.66 parts of the 30% by weight ester-based urethane-based resin (C) obtained in [Synthesis of urethane-based resin] was added. After mixing, 36.52 parts of triethylene glycol monobutyl ether, 36.52 parts of glycerin, 3.65 parts of "Surfinol 465", and 167.49 parts of ion-exchanged water were added to obtain a recording liquid. The average dispersion particle diameter of the recording liquid was 66 nm, and the viscosity was 4.19 mPa · s. This recording liquid was evaluated by the evaluation methods (1) to (9) described above. The evaluation results are shown in Table-6.

Claims (17)

  A pigment-dispersed aqueous recording liquid containing at least a pigment and a resin, wherein the resin is contained in an amount of 60 to 200 parts by weight based on 100 parts by weight of the pigment, the resin contains a water-dispersible urethane-based resin, and a polyurethane in the urethane-based resin is used. A pigment-dispersed aqueous recording liquid, wherein the weight fraction of the urea portion is 2.0% by weight or less, and the dispersed particle diameter D50 of the pigment in the recording liquid is 40 to 100 nm.   2. The pigment-dispersed aqueous recording liquid according to claim 1, wherein the pigment contains at least a carbon black having a DBP absorption of 30 ml / 100 g or more and 100 ml / 100 g or less.   3. The pigment-dispersed aqueous recording liquid according to claim 1, wherein the urethane resin has a molecular weight of more than 5,000 and not more than 100,000.   The pigment-dispersed aqueous recording liquid according to any one of claims 1 to 3, wherein the urethane resin has an acid value as a free acid of from 20 mgKOH / g to 100 mgKOH / g.   The pigment-dispersed aqueous recording liquid according to any one of claims 1 to 4, wherein the resin contains a resin having an acid value as a free acid of 100 mgKOH / g or more, in addition to the water-dispersible urethane-based resin.   When 14.5 mg of pigment-dispersed aqueous recording liquid per square inch is applied by solid-state printing to the paper dedicated to photographic quality by ink-jet printing, the print thickness is 20 nm or more, OD is 2 or more, and 20 ° gloss value is 60 or more. A pigment-dispersed aqueous recording liquid according to any one of claims 1 to 5, wherein   The pigment-dispersed aqueous recording liquid according to any one of claims 1 to 6, wherein the pigment contains carbon black and a pigment other than carbon black.   The pigment-dispersed aqueous recording liquid according to claim 7, wherein the pigment other than carbon black is a cyan pigment.   A printed matter formed from the pigment-dispersed aqueous recording liquid according to any one of claims 1 to 8.   The printed matter according to claim 9, wherein the pigment-dispersed aqueous recording liquid is discharged from an inkjet nozzle and formed on a recording material.   The printed matter according to claim 9, wherein the printed matter formed by the pigment-dispersed aqueous recording liquid has a thickness of 20 nm or more, an OD of 2 or more, and a 20 ° gloss value of 60 or more.   The printed matter according to any one of claims 9 to 11, wherein the arithmetic average roughness is 0.04 or less.   The printed matter according to any one of claims 9 to 12, wherein the pigment-dispersed aqueous recording liquid contains at least carbon black, and the printed matter is a black printed matter.   14.5 mg of pigment-dispersed aqueous recording liquid per square inch is applied to paper for exclusive use in photographic quality paper by solid printing using an ink jet method to form a printed material with a thickness of 20 nm or more, OD of 2 or more, and 20 ° gloss value. Is 60 or more.   The pigment-dispersed aqueous recording liquid according to claim 14, comprising at least carbon black.   A printed matter formed by discharging a pigment-dispersed aqueous recording liquid from an inkjet nozzle onto a recording material, wherein the printed thickness is 20 nm or more, the OD is 2 or more, and the 20 ° gloss value is 60 or more.   17. The printed matter according to claim 16, wherein 14.5 mg or more of ink per square inch is adhered to a photographic quality paper.